Kortam Sahira Ibrahim

Buccal Bone Changes With Self Ligating Brackets Versus Conventional Brackets.A Comparative Study Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Sahira Ibrahim Kortam, B.D.S., M.Sc. Graduate Program in Dentistry The Ohio State University 2010 Master‟s Examination Committee: Dr. Do-Gyoon Kim, Advisor Dr. Henry Fields Dr. Martin Palomo Dr. William Johnston Copyright by Sahira Ibrahim Kortam 2010 ABSTRACT Introduction: Self ligating brackets (SLB) manufacturers claim that expansion of arches and alveolar bone building is facilitated by their bracket design. The objective of this study was to determine whether SLB brackets have a different effect on buccal bone changes compared with conventional brackets (NSLB) during orthodontic treatment. Methods: Cone beam computed tomography (CBCT) images were obtained before and after treatment of 45 patients (26 treated with conventional brackets (NSLB) and 19 with SLB). The CBCT images were compared between groups for buccal bone height and thickness at the maxillary first molars, maxillary second and first premolars using imaging software. The intermolar distance and buccolingual angulation were assessed for the maxillary first molars as potentially confounding factors. Differences for each variable measured before and after treatment were compared between the two groups. Results: Initial and final thickness and height of buccal bone were significantly different between the teeth (p <0.001). The buccal bone height (p <0.001) and thickness (p= 0.018) significantly decreased after treatment for both groups. The mean changes of buccal bone height and thickness measured were not significantly different between SLB and NSLB groups (p>0.05). The intermolar distance and molar angulation changes were not significantly different between the 2 groups (p >0.05). The change in bone height depended on the initial bone thickness where the greater the initial bone thickness, the less the decrease in bone height (p <0.01). The change in bone thickness was affected by the change ii there is a trend that increased arch dimensions may lead to adverse bony changes depending on the patient‟s initial bony status. Conclusions: The buccal bone changes during orthodontic treatment regardless of which bracket type is used. Arch expansion and molar angulation can be similarly controlled by either type of appliance. Based on these data and those from RME studies.in intermolar distance where the bone thickness decreased when the intermolar distance increased (p <0. the implication is that. in the absence of other data. iii .01). Dedicated to my family iv . residents and staff of The Ohio State University Section of Orthodontics. I would like to thank my family for their love and support over the years. Lastly. Dr. Martin Palomo and Dr. I would like to thank Paul Geuy for his diligent work in helping with the measurements. residents and staff of Case Western Reserve University for their tireless support in gathering data and making this project successful. v . Ohio. Dr. Henry Fields. I would like to thank faculty. Dr. and Indiana. William Johnson for their time and tremendous effort.ACKNOWLEDGMENTS I would like to thank my Thesis committee. I would like to recognize the financial support for this research provided by the Dental Master‟s Thesis Award Program sponsored by Delta Dental Foundation which is the philanthropic affiliate of Delta Dental of Michigan. Do-Gyoon Kim. I would like to thank the faculty. . Egypt 1998………………………………. Egypt 2007-present………………………Graduate Resident in Orthodontics The Ohio State University Columbus.VITA Feb. Cairo University. Cairo University.S... Ohio FIELDS OF STUDY Major Field: Dentistry Specialty: Orthodontics vi .Sc.D.B. 8. Egypt 2005…………………………………M. 1974…………………………Born.Cairo. 1 2.....TABLE OF CONTENTS Page Abstract………………………………………………………………..viii List of Figures………………………………………………………….iv Acknowledgments……………………………………………………..………………………………………………….. Manuscript…….53 Bibliography……………………………………………………………57 vii . Introduction……………………………………………………….30 4.25 3..ii Dedication……………………………………………………………..v Vita……………………………………………………………………. Discussion and Conclusions……………………………………….ix Chapters: 1..vi List of Tables…………………………………………………………... Materials and Methods……………………………………………. .4 3.LIST OF TABLES Table 3.…………………49 3.…………………………………………………………………. final and change in intermolar distance .1 3.49 Means and standard deviations for the initial. final and change in bone height… ………………………………………………………………….48 Means and standard deviations for the initial.5 viii .2 Page Demographic distribution of patients studied……………………………48 Means and standard deviations for the initial.3 3. final and change for molar angulation………………………………………….…. final and change in bone thickness …………………………………………………………………48 Means and standard deviations for the initial. .1 Page The orientation was set to be parallel to the occlusal plane of the first molar...46 Buccolingual angulation and intermolar distance measurements………….………………………….………44 Buccal bone height and thickness measurements…………………………. The trough was drawn to bisect the maxillary first molar.47 3...45 Landmark identification for buccolingual angulation and intermolar distance measurements……………………………………………………………….. the cut was done at the level of the cementoenamel junction.LIST OF FIGURES Figure 3.4 ix .2 3.3 3. SPEED (Strite Industries. Speed. in which the clip. and inout). Time. and an undersized wire would not touch the walls of the bracket slot. Forestadent Mobil-Lock (1980). and the Damon 2 and In-Ovation brackets in 2000. and In-Ovation R.3 SLB have an inbuilt labial face. the popular SLB are Damon. does not press against the wire. and “A” Company Activa (1986).CHAPTER 1 INTRODUCTION Self ligating brackets (SLB) have received much popularity in the past few years.1 Some early SL brackets were the Ormco Edgelok (1972). the TwinLock bracket in 1998. Orec SPEED (1980). However.2 Other designs have appeared including the Time bracket in 1994. the Damon SL bracket in 1996.4 They are promoted on the premise that elimination of ligatures reduces friction and allows for better sliding mechanics. Cambridge.1 Currently. the term “passive” is somewhat of a misnomer because it is passive only when teeth are ideally aligned in 3 dimensions (torque. Canada). SmartClip. Ontario. angulation. They were introduced in the early 20th century with the „Russell Lock‟ edgewise attachment being described in 1935. which can be opened and closed. ideally. They are not new in orthodontics. Many manufacturers offer SLB indicating the increased demand of this product. SLB can be dichotomized into those with a spring clip that can press against the archwire (active) and those with a passive system of ligation. NY). Examples of active brackets are In-Ovation “R” (GAC International. and Time 1 . Bohemia. Examples in the passive group are the Damon bracket (Ormco. no documented evidence exists on the manufacturer's claims on the efficiency of self-ligating brackets in both. whereas torque control necessitates the development of frictional forces between the wire and the bracket slot walls. Low friction and low force are purported to be good for physiologically rebuilding the alveolar bone.(American Orthodontics. For example. Calif). Wis). shorter treatment time. better oral hygiene.7 This can ultimately cause bone dehiscence. space closure and torque control. This is particularly intriguing because of the contradictory demands involved in the mechanotherapeutic setup for these cases. and gingival recession. the evidence for most claims is lacking. some of these claims are increased patient comfort. less chair time.Glendora. Sheboygan. increased patient cooperation. Calif) and the SmartClip bracket (3M Unitek. as space closure with sliding mechanics requires low friction.5 Various claims are made by SLB manufacturers.8 2 .6 On the other hand. Monrovia. Unfortunately. greater patient acceptance. Sound scientific evidence is needed before we accept manufacturers‟ claims about SLB.3 The Damon system claims that using biologically sensible forces which work with the body‟s natural adaptive processes will create space naturally so most cases can be treated without extraction and without the need for headgear or palatal expanders. They also claim that posttreatment CT image shows transverse arch development and normal alveolar bone on lingual and buccal surfaces. excessive expansion can force the teeth through the cortical plate. and expansion.3 Despite the presentation of much empirical and anecdotal evidence. 14. Several clinical studies found no evidence to support the claim of reduced treatment time with self-ligating 3 . Frictional resistance: Several investigators11. 20. 15. 21 found that SLB had lower frictional resistance than conventional brackets. Burrow23 in 2009 pointed out that the clinical advantage of reduced resistance to sliding should be a reduction in the amount of time to align the teeth and close the spaces. 18. static or kinetic due to contact of the wire with bracket surfaces. created when the tooth tips or the wire flexes so that there is contact between the wire and the corners of the bracket (3) notching. (2) binding. when permanent deformation of the wire occurs at the wire-bracket corner interface. 17. 12. 16. 10 REVIEW OF THE LITERATURE Self ligating brackets (SLB) versus conventional brackets (NSLB) Various researchers have conducted studies to investigate the differences between SLB and NSLB. This often occurs under clinical conditions.The three-dimensional capability of cone-beam computed tomography (CBCT) technology makes it possible to assess alveolar bone loss for posterior teeth 9 where buccal bone defects can be detected and quantified.13. Tooth movement stops when a notched wire catches on the bracket corner and resumes only when the notch is released. Kusy and Whitley22 divided resistance to sliding into 3 components: (1) friction. 19. and possibly reducing the overall treatment time. Also in 2007. Damon27 in 1998 stated that the self-ligating bracket design allowed for rapid leveling because teeth drifted along the path of least resistance with little or no friction between the bracket and slot of the wire. 25. is the major determinant of how well bracketed teeth move along an archwire and that is about the same with conventional and self-ligating brackets. this system was capable of increasing the appointment intervals. Miles26 in 2005 concluded that SLB were no more effective in reducing irregularity than NSLB. several clinical studies found no evidence to support the claim of reduced treatment time with self-ligating brackets. not frictional resistance. Miles et al25 in 2006 found that SLB were no better during initial alignment than a conventional bracket. On the other hand. 1 He concluded that a binding and releasing phenomenon. Miles1 compared the rate of enmasse space closure and found that there was no significant difference in the rate of en-masse space closure between SLB and NSLB.brackets. Hamilton et al30 in 2008 conducted a study to determine if self4 . Thus. Eberting et al28 in 2001 found an average reduction in treatment time of 6 months (from 31 to 25) and 7 visits (from 28 to 21) for SLB patients compared with conventional ligation patients. Harradine2 in 2001 found that SLB cases required an average of four fewer months and four fewer visits to be treated to an equivalent level of occlusal regularity as measured by the PAR scores. Treatment duration: Several investigators assessed the treatment efficiency of SLB. Scott et al29 in 2008 concluded that SLB were no more efficient than NSLB during tooth alignment. 26.24. 019 x 0.022-inch slot size and were torqued with 0. Ormco. Torque control: Pandis et al5 in 2006 found that self-ligating brackets were equally efficient in delivering torque to maxillary incisors relative to conventional brackets in extraction and non-extraction cases. ceramic. Six types of orthodontic brackets were included in the study: the self-ligating Speed and Damon2. They concluded that SLB appear to offer no measurable advantages in orthodontic treatment time. Smart Clip. Brillant. They concluded that active self-ligating brackets were more effective in torque expression than passive self-ligating brackets. number of treatment visits and time spent in initial alignment over NSLB. Orange. and the polycarbonate bracket. The ceramic bracket (Fascination 2) presented the highest torquing moment and. polycarbonate. and 5 . Fascination 2. Ultratrimm and Discovery. Canada) and 2 passive selfligating brackets (Damon2. Cambridge. Self-ligating. GAC. Morina et al33 in 2008 examined the torque expression of active and passive self-ligating brackets compared with metallic. Calif.6 degrees). Ontario. Calif) using a bracket/wire assembly torsion device.025-inch SS archwires. the stainless steel (SS). NY. the lowest torque loss (4. Strite Industries. Bohemia. Monrovia. Fleming et al31 in 2009 concluded that efficiency of alignment in the mandibular arch in nonextraction patients is independent of bracket type. the ceramic bracket. All brackets had a 0. Badawi et al32 examined the torque expression of 2 active self-ligating brackets (In-Ovation. Speed. together with a SS bracket.ligating brackets are more efficient. and polycarbonate edgewise brackets. 3M Unitek. and the self-ligating appliance of Damon-3MX brackets (Ormco). normal overbite. both appliances increased maxillary dentoalveolar widths. The traditional appliance was composed of Victory Series MBT brackets (3M Unitek). and intermolar widths in the maxilla were recorded before treatment (T0) and 12 months later (T1).77 mm by Jiang and Fu37. 1. Other researchers investigated the mandibular dental arch changes. On the other hand. first and second interpremolar.selective metallic brackets demonstrated almost a 7-fold decreased moment developed during insertion and a 100 per cent increase in loss.91 mm by Fleming et al35 . Mandibular arch alignment resulted in transverse expansion and incisor proclination irrespective of the appliance system used. Intercanine. but no significant difference was observed between groups. Scott et al29 found no significant difference for either bracket system where their patients had premolar extractions. the difference was only 0. They found in both groups.3 mm by Pandis et al36 and 0. Forty consecutive patients (age range 14 to 30 years) with normal or low mandibular plane angle. They concluded that within 12 months of treatment. 6 . However a statistically greater increase in intermolar width in the group treated with the self-ligating appliance. a significant increase was recorded for all transverse measurements from T0 to T1. Transverse dimensions: Tecco et al34 in 2009 evaluated the transverse dimensions of the maxillary arch induced by fixed self-ligating and traditional straight-wire appliances during orthodontic therapy. and mild crowding were included. Systematic reviews: Fleming and Johal41 in 2010 conducted a systematic review to evaluate the clinical differences (alleviation of irregularity using Little‟s irregularity index. Pandis et al40 in 2010 investigated the salivary Streptococcus mutans levels in patients with conventional and self-ligating brackets. extent of root resorption developing during treatment. plaque retention.Periodontal condition: Pandis et al38 in 2008 investigated the periodontal condition of the mandibular anterior dentition in patients with conventional and self-ligating brackets to explore whether the use of selfligating brackets is associated with better values for periodontal indices because of the lack of elastomeric modules and concomitantly. and attachment debond rate) in relation to the use of self7 . They concluded that self ligating appliances promote reduced retention of oral bacteria. No difference was found in the oral hygiene indices between the two groups. Pellegrini et al39 in 2009 examined plaque retention by self-ligating vs elastomeric orthodontic brackets. reduced availability of retentive sites for microbial colonization and plaque accumulation. They concluded that the self-ligating brackets do not have an advantage over conventional brackets with respect to the periodontal status of the mandibular anterior teeth. The levels of S. rate of orthodontic space closure. mutans in whole saliva of orthodontically treated patients were not significantly different between conventional and self-ligating brackets. dimensional changes during orthodontic alignment. a significant reduction in buccal alveolar bone thickness of maxillary molars with 8 . They concluded that compared with conventional brackets. self-ligating brackets produce lower friction compared with conventional brackets. Each patient underwent expansion of 7 mm. self-ligating brackets produce lower friction when coupled with small round archwires in the absence of tipping and/or torque in an ideally aligned arch. at the end of the active expansion phase (T1). with a mean age of 11. In the evaluation of T0-T1 changes.2 years. Ballanti et al43 in 2009 investigated by low-dose computed tomography (CT) protocol the dental and periodontal effects of rapid maxillary expansion (RME). and after a retention period of 6 months (T2). Sufficient evidence was not found to claim that with large rectangular wires.ligating brackets in orthodontics. Ehsani et al42 in 2009 conducted a systematic review on frictional resistance in self-ligating orthodontic brackets and conventionally ligated brackets in vitro. They concluded that at this stage there is insufficient high-quality evidence to support the use of self-ligating fixed orthodontic appliances over conventional appliance systems or vice versa. in the presence of tipping and/or torque and in arches with considerable malocclusion. Rapid maxillary expansion studies and buccal bone The effect of rapid maxillary expansion on buccal bone has been investigated utilizing computed tomography. Multislice CT scans were taken before rapid palatal expansion (T0). All interdental transverse measurements were significantly increased at both T1 and T2 with respect to T0. Their sample comprised 17 subjects (7 males and 10 females). 1 ± 4.3 mm.4mm. Factors that showed significant correlation to buccal bone changes and dental tipping were age. periodontal measurements were significant on the lingual aspects. Rungcharassaeng et al44 in 2007 used cone-beam computed tomography (CBCT) images to determine the factors that might affect buccal bone changes of maxillary posterior teeth after rapid maxillary expansion. and differential expansion. Garib et al45 in 2006 examined the periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders by computed tomography.8 to 1.6 to 0.8 ± 4. In the evaluation of changes between the end of active expansion (T1) and the end of retention (T2). The appliances were activated 7-mm. They found that RME reduced the buccal bone plate thickness of supporting teeth 0. 9 .9 mm and increased the lingual bone plate thickness 0. Spiral CT scans were taken before expansion and after the 3-month retention period when the expander was removed.4 mm at the mesiobuccal area of the first molars. appliance expansion. RME induced bone dehiscences on the anchorage teeth‟s buccal aspect where there was a significant reduction of alveolar crest level of 7.the greatest amount of bone resorption being 0. and of overall T0-T2 changes. They found a negative statistically significant correlation between the thickness of the buccal alveolar crest at treatment onset and the alveolar crest level changes after expansion. but rate of expansion and retention time had no significant association. They found that buccal crown tipping and reduction of buccal bone thickness and buccal marginal bone level of the maxillary posterior teeth are immediate effects of RME. Their sample comprised 8 girls. 11 to 14 years old.6mm at the first premolars and 3. but not on the buccal side. initial buccal bone thickness. and crowding measurements. physical measurements were made by a third examiner using a digital caliper and a digital goniometer. Moreira et al47 in 2009 researched the precision and accuracy of maxillofacial linear and angular measurements obtained by cone-beam computed tomography (CBCT) images.03%.76° and the lowest value was −0.CBCT validity Several studies have been conducted to examine the validity and reliability of linear and angular measurements made on CBCT images. They concluded that CBCT digital models are as accurate as OrthoCAD digital models in making linear measurements for overjet. Calif) software. San Jose. They concluded that CBCT images can be used to obtain dimensionally accurate linear and angular measurements from bony maxillofacial structures and landmarks. Linear and angular measurements based on conventional craniometric anatomical landmarks. overbite. The highest difference between the physical and 3D-based angular measurements was 2. Thirty human skulls were scanned with dental CBCT. and were identified in CBCT images by 2 radiologists on two occasions. Baumgaertel et al48 in 2009 investigated the reliability and accuracy of dental measurements made on cone-beam computed tomography (CBCT) reconstructions. Kau et al46 in 2010 analyzed CBCT scans of 30 subjects using InVivoDental (Anatomage. Regarding accuracy tests. The mean difference between the physical and 3D-based linear measurements varied from 0.04 to −0. Subsequently. They utilized 15 dry human skulls that were submitted to CBCT. independently. no statistically significant differences were found from the comparison between the physical and CBCT-based linear and angular measurements for both examiners.27 mm. Others examined the ability of CBCT to detect periodontal bone defects. Ten 10 . and 3-dimensional reconstructions of the dentitions were generated. Stratemann et al49 in 2008 conducted a study to determine the accuracy of measuring linear distances between landmarks commonly used in orthodontic analysis on a human skull using two cone beam CT (CBCT) systems.39 mm to 0. The error was slightly smaller in the CB MercuRay than in the NewTom. Japan). and arch length required) were made directly on the dentitions of the skulls with a high-precision digital caliper and on the digital reconstructions with commercially available software. with a median of 0. Measurements on the CBCT images were compared to measurements on a full mouth X-ray series. overjet. A sample of 146 sites in 5 dry skulls provided the ground truth. They concluded that the NewTom 9000 cone beam CT scanner provides better diagnostic and quantitative information on periodontal bone levels in three dimensions than conventional radiography. Half of the sample had bone loss of at least 3 mm. FL) and the Hitachi MercuRay (Hitachi Medico Technology. They concluded that dental measurements from CBCT volumes can be used for quantitative analysis. 11 . Mol and Balasundaram. which became statistically significant only when combining several measurements. Tokyo. The accuracy in the anterior aspect of the jaws is limited. They concluded that the volumetric data rendered with both CBCT systems provided highly accurate data compared with the gold standard of physical measures directly from the skulls.9 in 2008 assessed the accuracy of NewTom 9000 cone beam CT images for the detection and quantification of periodontal bone defects in three dimensions.measurements (overbite. with less than 1% relative error. arch length available.24 mm. maxillary and mandibular intermolar and intercanine widths.22 mm. Sarasota. the NewTom® QR DVT 9000 (Aperio Inc. They found a small systematic error. the mean absolute error to the gold standard caliper measurements for the human skull was 0.01 mm and a range of –0. For the CB MercuRay.00±0. All bony defects were identifiable and measurable directly or with CBCT.5mm). At the time of extraction of the tooth and after the tooth had been removed. buccal and lingual defects could not be measured with radiographs. Artificial osseous defects were created on mandibles of dry skulls. a pocket depth 0. The width was measured 1mm apical to the alveolar crest level. intra-operative measurements of the socket. periapical radiography (PA). Orthodontic treatment and periodontal condition Huynh-Ba et al50 in 2010 analyzed the socket bone wall dimensions in the upper maxilla in relation to immediate implant placement. on average. A systematic review by Bollen et al51 in 2008 found that subjects in the orthodontically treated group had.5–3mm. The relationship between orthodontic treatment and the periodontal condition has been investigated in various studies. The mean alveolar bone loss was 0.3 millimeter deeper than that of subjects in the untreated groups. SD 0. They concluded that all three modalities are useful for identifying interproximal periodontal defects and that compared to radiographs. the three-dimensional capability of CBCT offers a significant advantage because all defects including buccal and lingual defects can be detected and quantified. In comparison. CBCT scanning.1mm (range: 0. including the width of the buccal and palatal walls of the sockets were recorded.Misch et al10 in 2006 evaluated the accuracy of cone beam computed tomography for periodontal defect measurements. and direct measurements using a periodontal probe were compared to an electronic caliper that was used as a standard reference. Premolars buccal bone thickness mean was 1.13 mm greater among the groups that had been 12 . 22 mm for the controls. The orthodontically treated group had gingival recession 0. statistically significant CEJ-AC distances than the untreated group. This mean difference of 0. The distances from the AC to the cementoenamel junction (CEJ) on the mesial and distal surfaces of the first molars and second premolars and on the distal surface of the canines were measured. One hundred and fifty pairs matched by age and sex were selected using simple random sampling. The first premolars were extracted in every treated patient. the edgewise straight-wire system.17 years.36 mm for treated subjects and 0. The mean value of the extent of recession of the four lower incisors amounted to 0. primarily at the extraction areas.orthodontically treated than among the groups that had not. no significant difference in the mean recession value could be found between cases and controls. Janson et al53 in 2003 compared the heights of the alveolar bone crests among orthodontic patients treated with either the standard edgewise technique.14 mm was not clinically relevant. They analyzed study casts and intra oral slides of 300 adult patients. These 3 groups were compared with an untreated control group. All treated groups had larger. and measurements were performed on bitewing radiographs taken after a mean posttreatment period of 2. or bioefficient therapy.03 mm greater than did the untreated group. Allais and Melsen52 in 2003 evaluated the association between the extent of labial movement of the lower incisors and the prevalence and severity of gingival recession in orthodontically treated adult patients. 13 . They recommended that labial movement of lower incisors is a valuable alternative to extraction leading to no clinically relevant deterioration of the periodontium. Although the difference in prevalence of individuals with gingival recession among cases and controls was statistically significant. 11 years after the end of treatment. They found some additional loss of periodontal attachment for the treated group. Bondemark55 in 1998 investigated the periodontal condition for two groups of 20 adolescents. Zachrisson and Alnaes57. a distance > 2 mm between the cementoenamel junction and the alveolar bone crest. 1 malocclusion treated with all first premolars extracted. the first at the start of treatment. no significant difference in alveolar bone level between treated and untreated groups was found.1 and 0. It was demonstrated that there was a small but significant decrease in interdental alveolar bone support ranging between 0.. i.e. The treatment duration was 19. 31 former patients were compared with a control group of matched age and sex distribution. the second after 2.8 years. At the start of this study. one treated orthodontically and one untreated. and the third at the end of the 5-year study period. Neither group had any sites with clinically significant bone loss. or tooth loss between those who had and had not been treated by the age of 26. The interdental alveolar bone level was estimated as the distance between the cementoenamel junction and the alveolar bone crest on bite-wing radiographs of the upper and lower premolars and molars on three occasions. periodontal disease occurrence. the 14 . there were no significant differences in caries experience. however the differences were not considered to be of clinical significance.5 mm during the 5-year observation period both in the treated and untreated group.Thomson54 in 2002 examined the long term outcomes of orthodontic treatment.1 months. and followed them longitudinally for 5 years. According to his findings. 58 in 1973 and 1974 examined 51 patients with Cl II Div. Jager et al56 in 1990 examined the long term influence of orthodontic mandibular arch expansion therapy on the periodontal condition of the posterior teeth. Radiographically the orthodontic patients showed more alveolar bone loss than did the control group. This study will examine the buccal bone changes and will investigate the difference in posterior arch dimensions and molar angulation for the different types of brackets. Statement of the Problem Based on this review of the literature. Several studies have investigated the buccal bone changes with rapid maxillary expansion and indicated that bone loss occurs with expansion. Specific Aim and Hypothesis to be tested The specific aim is to compare the changes in buccal bone and buccal angulation of posterior teeth after orthodontic treatment with SLB or conventional brackets and to determine if the change in tooth position affects the buccal bone changes. There are limited reports that compared the arch dimension changes but none compared the angulation changes for the posterior teeth. Several clinical studies indicate that orthodontic treatment can have a mild detrimental effect on the periodontium but there is limited quantitative data. They clinically found the orthodontic patients to demonstrate slightly but significantly more loss of attachment than the control group.2 years. The first null hypothesis is that there is no difference between patients treated with SLB or conventional brackets for buccal bone changes (buccal bone height and buccal bone thickness).mean age of the patients was 16. They selected 54 individuals to match the treated group. several aspects of differences between SLB and NSLB have been studied however there are no reports that investigated the difference in the buccal bone changes between the SLB and NSLB. The patients were examined 2 years after finishing orthodontic treatment. 15 . Harradine NW. Am J Orthod. Miles PG. 16 . Rinchuse DJ. 2.78(5):511-27. Self-ligating brackets and treatment efficiency. 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Portelli M. Alonzo TA. et al. Festa F. Am J Orthod Dentofacial Orthop. Am J Orthod Dentofacial Orthop. Scribante A. Am J Orthod Dentofacial Orthop. 19. Sherriff M. Resistance to sliding of self-ligating brackets versus conventional stainless steel twin brackets with second-order angulation in the dry and wet (saliva) states. 20.116(3):336-45. Auricchio F. 1998 Oct. 2008 May. Nucera R. 1999 Sep. Klersy C. 2003 Oct. Festa F.133(5):708-15. In vitro evaluation of the frictional forces between brackets and archwire with three passive self-ligating brackets. Militi A. Matarese G. Stoner JA. 2001 Oct.120(4):361-70. Thorstenson GA. Loftus BP. Grossi GB. Birnie D. Mazza M. Eur J Orthod.20(5):589-96. Eur J Orthod.16. 2009 Dec. Sfondrini MF. Evaluation of frictional forces during dental alignment: an experimental model with 3 nonleveled brackets. Cordasco G. 18. Evaluation of friction during sliding tooth movement in various bracket-arch wire combinations. Thomas S.31(6):643-6. 17. 18 . Nucera R. Farronato G. Ricciardi A. 23. Friction and resistance to sliding in orthodontics: a critical review.132(2):208-15.4(4):228-34. 26. Treatment time.1(1):52-61. 1999 Apr. Self-ligating vs conventional brackets in the treatment of mandibular crowding: a prospective clinical trial of treatment duration and dental effects. 28. 19 . Rustveld L.135(4):442-7. Tuncay OC. Scott P. Influence of archwire and bracket dimensions on sliding mechanics: derivations and determinations of the critical contact angles for binding. Burrow SJ. Eberting JJ. 29. DiBiase AT.134(4):470. Clin Orthod Res. Straja SR. The rationale. Polychronopoulou A.e1. Eur J Orthod. Am J Orthod Dentofacial Orthop. Weyant RJ. Damon DH. Clin Orthod Res. Miles PG. 27.21(2):199-208. SmartClip versus conventional twin brackets for initial alignment: is there a difference? Aust Orthod J. Am J Orthod Dentofacial Orthop. 2001 Nov. Eliades T. Kusy RP. 2005 Nov. Miles PG. 2007 Aug.470.76(3):480-5. Whitley JQ. 2008 Oct. outcome. 25. 24. 2006 May. 2009 Apr. Sherriff M. Pandis N. Angle Orthod. 1998 Aug. A clinical trial of Damon 2 vs conventional twin brackets during initial alignment. Cobourne MT.22.e8. evolution and clinical application of the self-ligating bracket. Alignment efficiency of Damon3 self-ligating and conventional orthodontic bracket systems: a randomized clinical trial. and patient satisfaction comparisons of Damon and conventional brackets.21(2):123-7. Am J Orthod Dentofacial Orthop. DiBiase AT. Perillo L. 2009 Sep. Comparison of active self-ligating brackets and conventional pre-adjusted brackets. Non-extraction treatment with self-ligating and conventional brackets. Jager A. 2008 Nov. Jiang RP. 34. 37. DiBiase AT. Toogood RW. Chimenti C. Torque expression of self-ligating brackets. and plastic brackets. Badawi HM. Am J Orthod Dentofacial Orthop. Sarri G. ceramic. Am J Orthod Dentofacial Orthop. Eur J Orthod.136(3):340-7. Lee RT. 33. 2009 May. Pandis N. 2008 May. Tete S. 32. Eliades T. 31. 2009 Winter. Pandis N. Eur J Orthod. 35. 2008 Aug. Comparison of mandibular arch changes during alignment and leveling with 2 preadjusted edgewise appliances. Fu MK. Mandibular dental arch changes associated with treatment of crowding using self-ligating and conventional brackets. 2008 Jun.135(5):597-602.10(4):290-4. Makou M. Goonewardene MS. Murray K. Hamilton R.133(5):721-8. Eliades T. Morina E. Torque expression of self-ligating brackets compared with conventional metallic. Zhonghua Kou Qiang Yi Xue Za Zhi. 36. Heo G. Fleming PS. Am J Orthod Dentofacial Orthop. Bourauel C. Lee RT.43(8):459-63. 2009 Dec 3. Efficiency of mandibular arch alignment with 2 preadjusted edgewise appliances. Sarri G. Tecco S. World J Orthod.24(2):102-9. Aust Orthod J. Major PW. Fleming PS. Polychronopoulou A. Maxillary arch width changes during orthodontic treatment with fixed self-ligating and traditional straight-wire appliances. Festa F. Carey JP. 20 .30(3):233-8.30. Plaque retention by self-ligating vs elastomeric orthodontic brackets: quantitative comparison of oral bacteria and detection with adenosine triphosphate-driven bioluminescence. Frictional resistance in self-ligating orthodontic brackets and conventionally ligated brackets. Papaioannou W. et al. A systematic review. Nakou M.9. 42. Johal A. Pandis N.135(4):426. Covell DA. Pellegrini P. Eur J Orthod. Pandis N. Periodontal condition of the mandibular anterior dentition in patients with conventional and self-ligating brackets.38. Franchi L. Angle Orthod. McLeod J. Salivary Streptococcus mutans levels in patients with conventional and self-ligating brackets. Lione R. Polychronopoulou A. Finlayson T. Ehsani S. discussion 426-7. Orthod Craniofac Res. Ballanti F. 2009 Apr. Fleming PS. Am J Orthod Dentofacial Orthop. Eliades T. Fanucci E. Eliades T. 2010 Feb. 2009 May. El-Bialy TH. Kontou E. Vlachopoulos K.80(3):57584. Makou M. Angle Orthod. 39. Maier T. Immediate and post-retention effects of rapid maxillary expansion investigated by computed tomography in growing patients. Flores-Mir C.32(1):94-9. Cozza P. 2008 Nov. 2010 May.e1.79(3):592-601. 43. 21 . 2009 Jan. Madianos P.Jr. 40. Angle Orthod. Baccetti T.79(1):24-9. Mandich MA. Sauerwein R. 41. Self-ligating brackets in orthodontics.11(4):211-5. 22 . Kan JY.37(2):80-93. 47.25.e1. Baumgaertel S. Am J Orthod Dentofacial Orthop.129(6):749-58. 46. Garib DG. Littlefield J. 2010 May. Stratemann SA. Oral Surg Oral Med Oral Pathol Oral Radiol Endod.80(3):435-9. Comparison of cone beam computed tomography imaging with physical measures. Cavalcanti MG.428. 2009 Jul.e8. 2008 Feb. Am J Orthod Dentofacial Orthop. Angle Orthod. 45. Palomo L. Caruso JM. Lopes PM. Hans MG. Rainy N. discussion 25-8. Nguyen JT. 48. Moreira CR. Sales MA.44. 2007 Oct. Am J Orthod Dentofacial Orthop. 2009 Apr 20. Miller AJ. Assessment of linear and angular measurements on three-dimensional cone-beam computed tomographic images. Palomo JM. Kim J. Taylor G. Henriques JF. Periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders: a computed tomography evaluation. Creed B. Reliability and accuracy of cone-beam computed tomography dental measurements. Evaluation of CBCT Digital Models and Traditional Models Using the Little's Index. 49.132(4):428. Fernandes AY.136(1):19. Maki K. Huang JC. 2006 Jun. Hatcher DC. Dentomaxillofac Radiol. Factors affecting buccal bone changes of maxillary posterior teeth after rapid maxillary expansion. Janson G. de Freitas MR. Rungcharassaeng K. Kau CH. 51.139(4):413-22. Alnaes L. de Freitas MR. 56. Cecchinato D. Lindhe J. Zachrisson BU.72(5):449-55. Hujoel PP. 2003 Aug. Bakko DW. 54. 2010 Jan.25(4):343-52. Does labial movement of lower incisors influence the level of the gingival margin? A case-control study of adult orthodontic patients. Effects of orthodontic expansion of the mandibular arch on the periodontal condition of the posterior teeth.50. Jager A. Cunha-Cruz J.124(2):157-64. Periodontal condition in orthodontically treated and untreated individuals. 55. Angle Orthod. Interdental bone changes after orthodontic treatment: a 5-year longitudinal study. Analysis of the socket bone wall dimensions in the upper maxilla in relation to immediate implant placement. 2008 Apr. Dtsch Zahnarztl Z. The effects of orthodontic therapy on periodontal health: a systematic review of controlled evidence. Huynh-Ba G.21(1):37-42. Orthodontic treatment outcomes in the long term: findings from a longitudinal study of New Zealanders. Allais D. 52. Bondemark L. Comparative radiographic evaluation of the alveolar bone crest after orthodontic treatment. 53. Angle Orthod. Brandao AG. Janson G. Bombonatti R. 1998 Jul. 2002 Oct. Melsen B. Sanz M. et al. 1990 Feb. Am J Orthod Dentofacial Orthop. Eur J Orthod. 2003 Aug. Mausberg R. J Am Dent Assoc. Thomson WM. Polley J. Pjetursson BE.114(1):25-31. Henriques JF. 57.44(1):48-55. Ferrus J.45(2):113-5. Am J Orthod Dentofacial Orthop. Huang GJ. Alveolar bone loss: radiographic findings. 23 . 1974 Jan. Clin Oral Implants Res. II. Bollen AM. 43(4):402-11. gingival pocket depth and clinical crown height. 1973 Oct. Periodontal condition in orthodontically treated and untreated individuals. I.58. Angle Orthod. Zachrisson BU. Loss of attachment. Alnaes L. 24 . The exclusion criteria were patients who received RPE or headgear. bone height of 0. patients with facial asymmetry or patients who had orthognathic surgery. The patients were treated with full fixed appliances-. Patient Selection The CBCT images before and after treatment of fifty patients were obtained from a university graduate clinic.CHAPTER 2 MATERIALS AND METHODS Human Subjects Approval This study was approved by the Institutional Review Board of the Ohio State University. waiver of the consent process.3⁰.2mm. Bohemia. patients with craniofacial anomalies. The SLB used were Damon 3 (Ormco. Columbus. A sensitivity power analysis was compled using G power software.2mm and bone thickness of 0. Orange. California) and GAC Innovation R (GAC. Smart clip (3M Unitek. NY). Monrovia.either SLB or NSLB. Forty five images (26 with NSLB and 19 with SLB) were analyzed because five images were removed due to errors in the data set. 10 A sample size of 45 patients had 85% power and could detect a difference in intermolar distance of 1. the research was approved for the inclusion of children. molar angulation of 3.9. The 25 . California). In addition.5mm. OH (OSU protocol number: 2008H0210). and waiver of HIPAA Research Authorization throughout the entire research study. 1) Buccal bone height and bone thickness measurements (Fig. the first perpendicular line (PL1) was drawn to LA. The trough was drawn to bisect the maxillary first molar mesiodistally and buccolingually (Fig. La Porte. the orientation was set to be parallel to the occlusal plane of the first molar with the cut at the level of the cementoenamel junction.The slice with the maximum bone thickness was utilized for comparison. Ten cross sections with a thickness of 1mm and uniform spacing were made through the maxillary first molar (M1). The distance on the LA from PL2 to the cusp tip represented the buccal bone thickness level (BTL) 26 . 1). A vertical orientation line was constructed perpendicular to the horizontal line at hard tissue Nasion. The orientation tool was used where the image was first oriented from the front so that a horizontal line connected hard tissue Orbitale to Orbitale. Chatsworth. The distance on the LA from the PL1 to the cusp tip was the BBH. CA). 2) The pretreatment images were designated T1 and the post treatment images were designated T2. The CBCT images were analyzed using Dolphin Imaging software (version 10.conventional brackets used were preadjusted edgewise twin bracket (3M Unitek. IN). the second premolar (P2) and the first premolar (P1). To measure buccal bone height (BBH). TP Orthodontics. the long axis of the buccal root (LA) was drawn from the buccal cusp tip to the buccal root tip. A second perpendicular line (PL2) was drawn where the buccal bone curvature stabilized and reached a consistent maximum thickness. At the most occlusal point where the bone was in contact with the tooth.5 Dolphin Imaging and Management Solutions. For the measurements of the first molar. The distance from the root surface to the bone surface on the second perpendicular line was the buccal bone thickness (BBT). a line connecting the central fossae was drawn and the measurement represented the intermolar distance (ID). whereas the BBH change was derived by subtracting the T2 value from the T1 value. This method of measurement was adopted from a previous study by Rungcharassaeng et al. at the crown level of the maxillary first molar. 3) Molar angulation (MA) measurement (Fig. a cut was made buccolingually at the center of the crown (determined both mesiodistally and buccolingually) so that it passed through the greatest depth of the central fossae bilaterally. and their difference represented the amount of molar tipping. 2). The procedure was repeated for the T2 measurements and BTL at T1 determined the position of PL2 on the T2 image (Fig.and where the BBT of the post treatment (T2) image would be measured. Negative values of those changes accounted for bone loss. and their difference was the amount of dental expansion (positive) or constriction (negative). The procedure was repeated for the T2 measurements. The BBT change resulted by subtracting the T1 value from the T2 value. The same procedure was repeated for the measurements of the first and second maxillary premolar. A 27 .1 2) Intermolar distance (ID) measurement (Fig. 3) On the coronal image derived from the previous cut. 3) From the axial section of the T1 images. On the coronal image derived from the cut. lines were drawn from the central fossa to the furcation area. The procedure was repeated for the T2 measurements. The angle formed by the intersection of this line and a line tangent to the greatest height of the palate represented the buccolingual inclination of the tooth. intermolar distance and molar angulation measurements.positive value represented buccal crown tipping and a negative value represented lingual crown tipping. ANOVA and ANCOVA. The data were analyzed with SAS 9. bone thickness. P1) and side (right and left) on the measured parameters (buccal bone height and thickness. ANOVA was used to detect the effect of the bracket type (SLB and NSLB). final and change in intermolar distance and buccolingual angulation of the maxillary first molars. maxillary first and second premolars. The difference between SLB and NSLB were compared in terms of: initial. T-tests was used to compare the difference between SLB and NSLB for initial. initial. time.. final and change in buccal bone height and buccal bone thickness for the maxillary first molar. Cary. The data was analyzed by the t-test. maxillary first and second premolars. 28 . P2. final and change in intermolar distance and buccolingual angulation of the maxillary first molars. NC). intermolar distance and molar angulation). tooth (M1.2 software (SAS Institute Inc. and for initial. final and change in buccal bone height and buccal bone thickness of the maxillary first molar. Means and standard deviations were calculated for each parameter. Statistical analysis Ten CBCT images were randomly selected and remeasured at least 2 weeks apart to assess intraexaminer reliability for bone height. 29 . molar angulation and intermolar distance depended on their respective initial values. Am J Orthod Dentofacial Orthop. ANCOVA was also used to determine if the change in molar angulation and intermolar distance affected the change in buccal bone thickness and height and whether the change in buccal bone height depended on the initial buccal bone thickness.ANCOVA was used to determine if the change in buccal bone height.e8. Taylor G.132(4):428. Rungcharassaeng K.05 was used for all statistical analyses.e1. thickness. Kim J. References 1. Factors affecting buccal bone changes of maxillary posterior teeth after rapid maxillary expansion. The significance level of 0. Caruso JM.428. Kan JY. 2007 Oct. M. The Ohio State University. 30 . Fields is Professor and Chair.S. College of Dentistry. PhD Henry W.. Division of Orthodontics.S.. College of Dentistry. PhD Dr.D. M. College of Dentistry.S. The Ohio State University.. Division of Restorative and Prosthetic Dentistry. Johnston is a Professor.D. Do-Gyoon Kim.D. The Ohio State University.D. Paul Geuy is a student at The Ohio State University.S. Martin Palomo.. Fields.CHAPTER 3 MANUSCRIPT BUCCAL BONE CHANGES WITH SELF LIGATING BRACKETS VERSUS CONVENTIONAL BRACKETS.S. Dr. A COMPARATIVE STUDY AUTHORS: Sahira Kortam. D. D. D. M. Kortam is a resident. M. Paul Geuy William Johnston.D.S. Dr.Sc. Dr. Palomo is an Associate Professor, Program Director, Department of Orthodontics, Craniofacial Imaging Center Director, Case Western Reserve University, School of Dental Medicine. Dr. Kim is an Assistant Professor, Research Program Director, Division of Orthodontics, The Ohio State University, College of Dentistry. ABSTRACT Introduction: Self ligating brackets (SLB) manufacturers claim that expansion of arches and alveolar bone building is facilitated by their bracket design. The objective of this study was to determine whether SLB brackets have a different effect on buccal bone changes compared with conventional brackets (NSLB) during orthodontic treatment. Methods: Cone beam computed tomography (CBCT) images were obtained before and after treatment of 45 patients (26 treated with conventional brackets (NSLB) and 19 with SLB). The CBCT images were compared between groups for buccal bone height and thickness at the maxillary first molars, maxillary second and first premolars using imaging software. The intermolar distance and buccolingual angulation were assessed for the maxillary first molars as potentially confounding factors. Differences for each variable measured before and after treatment were compared between the two groups. Results: Initial and final thickness and height of buccal bone were significantly different between the teeth (p <0.001). The buccal bone height (p <0.001) and thickness (p= 0.018) significantly decreased after treatment for both groups. The mean changes of buccal bone height and thickness measured were not significantly different between SLB and NSLB groups (p>0.05). The intermolar distance and molar angulation changes were not significantly different between the 2 groups (p >0.05). The change in 31 bone height depended on the initial bone thickness where the greater the initial bone thickness, the less the decrease in bone height (p <0.01). The change in bone thickness was affected by the change in intermolar distance where the bone thickness decreased when the intermolar distance increased (p <0.01). Conclusions: The buccal bone changes during orthodontic treatment regardless of which bracket type is used. Based on these data and those from RME studies, the implication is that, in the absence of other data, there is a trend that increased arch dimensions may lead to adverse bony changes depending on the patient‟s initial bony status. Arch expansion and molar angulation can be similarly controlled by either type of appliance. KEY WORDS: CBCT, self ligating, buccal bone, intermolar INTRODUCTION Self ligating brackets (SLB) have received much attention in the past few years and many manufacturers now offer SLB, but they are not new in orthodontics. They were introduced in the early 20th century with the „Russell Lock‟ edgewise attachment described in 1935.1 Some early SLB were the Ormco Edgelok (1972), Forestadent Mobil-Lock (1980), Orec SPEED (1980), and “A” Company Activa (1986).2 Other designs have appeared, but currently the popular SLB are Damon, Time, Speed, SmartClip, and In-Ovation R.3 Various claims are made by SLB manufacturers. One of these possibilities is increased arch dimension changes. Sound scientific evidence is required in order to accept manufacturers‟ claims about SLB. 32 The Damon self ligating system claims that using biologically sensible forces which work with the body‟s adaptive processes will naturally create space allowing most cases to be treated without extraction and without the need for headgear or palatal expanders. They also claim that posttreatment computed tomography (CT) images show transverse arch development and normal alveolar bone on lingual and buccal surfaces. Low friction and low force are purported to be good for physiologically rebuilding the alveolar bone.4 On the other hand, excessive expansion can force the teeth through the cortical plate.5 This can ultimately cause bone dehiscence and gingival recession.6 The three dimensional capability of cone beam computed tomography (CBCT) technology makes it possible to non-invasively assess alveolar bone changes for posterior teeth7 where buccal bone defects can be detected and quantified.8 The objective of this study was to compare the difference between patients treated with SLB and conventional brackets (NSLB) in regards to the changes in buccal bone height and thickness, while monitoring buccolingual root angulation and intermolar distance. MATERIALS AND METHODS This study was approved by the Institutional Review Board. The CBCT images before and after treatment of fifty patients were obtained from a university graduate clinic. The patients were treated with full fixed appliances either SLB or NSLB. A sensitivity power analysis was done using G power software.9, 10 A sample size of 45 patients was used for 85% power that could detect a 33 bone height of 0. 1) Buccal bone height and bone thickness measurements (Fig.The slice with the maximum bone thickness was utilized for comparison. For the measurements of the first molar. Chatsworth. the second premolar (P2) and the first premolar (P1).5 Dolphin Imaging and Management Solutions.2mm and bone thickness of 0. Smart clip (3M Unitek. The exclusion criteria were patients who received RPE or headgear. patients with craniofacial anomalies. The trough was drawn to bisect the maxillary first molar mesiodistally and buccolingually (Fig.5mm. the orientation was set to be parallel to the occlusal plane of the first molar with the cut at the level of the cementoenamel junction. The CBCT images were analyzed using Dolphin Imaging software (version 10. Bohemia. A vertical orientation line was constructed perpendicular to the horizontal line at hard tissue Nasion. NY). 34 . Ten cross sections with a thickness of 1mm and uniform spacing were made through the maxillary first molar (M1). The conventional brackets used were preadjusted edgewise twin bracket (3M Unitek. molar angulation of 3. The orientation tool was used where the image was first oriented from the front so that a horizontal line connected hard tissue Orbitale to Orbitale. 2) The pretreatment images were designated T1 and the post treatment images were designated T2. Forty five images (26 with NSLB and 19 with SLB) were analyzed because five images were removed because of errors in the data set. TP Orthodontics. California) and GAC Innovation R (GAC. 1). California). CA).2mm.3⁰. Orange. Monrovia.difference in intermolar distance of 1. IN). The SLB used were Damon 3 (Ormco. patients with facial asymmetry or patients who had orthognathic surgery. La Porte. On the coronal image derived from the cut. A second perpendicular line (PL2) was drawn where the buccal bone curvature stabilized and reached a consistent maximum thickness. The distance from the root surface to the bone surface on the second perpendicular line was the buccal bone thickness (BBT). The procedure was repeated for the T2 measurements and BTL at T1 determined the position of PL2 on the T2 image (Fig. 3) From the axial section of the T1 images. a line connecting the central fossae was drawn and the measurement represented the intermolar distance (ID). a cut was made buccolingually at the center of the crown (determined both mesiodistally and buccolingually) so that it passed through the greatest depth of the central fossae bilaterally. 2). The BBT change resulted by subtracting the T1 value from the T2 value.11 2) Intermolar distance (ID) measurement (Fig. whereas the BBH change was derived by subtracting the T2 value from the T1 value. At the most occlusal point where the bone was in contact with the tooth. the first perpendicular line (PL1) was drawn to LA. This method of measurement was adopted from a previous study by Rungcharassaeng et al. The distance on the LA from the PL1 to the cusp tip was the BBH. The procedure was repeated for the T2 35 . at the crown level of the maxillary first molar. Negative values of those changes accounted for bone loss. the long axis of the buccal root (LA) was drawn from the buccal cusp tip to the buccal root tip. The same procedure was repeated for the measurements of the first and second maxillary premolar. The distance on the LA from PL2 to the cusp tip represented the buccal bone thickness level (BTL) and where the BBT of the post treatment (T2) image would be measured.To measure buccal bone height (BBH). Means and standard deviations were calculated for each parameter. 3) On the coronal image derived from the previous cut. 36 . bone thickness. maxillary first and second premolars. final and change in buccal bone height and buccal bone thickness for the maxillary first molar. 3) Molar angulation (MA) measurement (Fig. initial. The procedure was repeated for the T2 measurements. NC).2 software (SAS Institute Inc.. Cary. A positive value represented buccal crown tipping and a negative value represented lingual crown tipping. Statistical analysis Ten CBCT images were randomly selected and remeasured at least 2 weeks apart to assess intraexaminer reliability for bone height. and their difference represented the amount of molar tipping. final and change in intermolar distance and buccolingual angulation of the maxillary first molars. The difference between SLB and NSLB were compared in terms of: initial. and their difference was the amount of dental expansion (positive) or constriction (negative). The data was analyzed by the t-test. lines were drawn from the central fossa to the furcation area.measurements. intermolar distance and molar angulation measurements. The angle formed by the intersection of this line and a line tangent to the greatest height of the palate represented the buccolingual inclination of the tooth. ANOVA and ANCOVA. The data were analyzed with SAS 9. The measurement error for the bone thickness and bone height measurements were 0. ANCOVA was used to determine if the change in buccal bone height. The intraclass correlation coefficients for the intermolar distance and molar angulation measurements were 0.3 years and a range of 12-17 years. The 37 . respectively. The demographic distribution for the patients is presented in Table I.05 was used for all statistical analyses. final and change in buccal bone height and buccal bone thickness of the maxillary first molar. ANCOVA was also used to determine if the change in molar angulation and intermolar distance affected the change in buccal bone thickness and height and whether the change in buccal bone height depended on the initial buccal bone thickness.32mm and 0. maxillary first and second premolars. The significance level of 0. final and change in intermolar distance and buccolingual angulation of the maxillary first molars.ANOVA was used to detect the effect of the bracket type (SLB and NSLB). respectively. RESULTS The study included 45 patients. molar angulation and intermolar distance depended on their respective initial values. Twenty-six patients had NSLB and 19 had SLB. The intraclass correlation coefficients for the bone thickness and bone height measurements were 0.78.1 ± 1.73 and 0.88 and 0. and for initial. 18 males and 27 females with a mean age of 14. time. intermolar distance and molar angulation). respectively. P1) and side (right and left) on the measured parameters (buccal bone height and thickness. P2. tooth (M1.4mm. T-tests was used to compare the difference between SLB and NSLB for initial. thickness.81. intermolar distance and molar angulation at pretreatment (T1). The change in bone thickness was not affected by the initial bone thickness (p=0. post treatment (T2) and the change (T1-T2) are shown in Table II through V.001) regardless of bracket type.187).8mm and 2.021) and the final bone thickness (p=0.017).719) in intermolar distance were not significantly different between the 2 bracket types. The intermolar distance increased after treatment for both bracket types.001).183).184) and change (p=0. The bone height significantly decreased after treatment for both bracket types (p <0. the right side was greater.097). There was a significant difference between the right and left side for bone thickness (p= 0. second premolar and first premolar (p <0.001) regardless of bracket type.973) in bone height were not statistically significantly different between the two bracket types. There was no significant difference between right and left side for bone height (p=0. The initial (p=0. The initial bone thickness (p=0. The change in intermolar distance was affected by the initial intermolar distance 38 . Bone height (initial and final) was significantly different between the maxillary first molar.652). second premolar and first premolar (p <0. final (p=0.270) was not significantly different between the two bracket types.71. final (p=0.022).measurement error for the intermolar distance and molar angulation measurements were 0. Bone thickness (initial and final) were significantly different between the maxillary first molar.⁰ respectively. bone thickness. The bone thickness significantly decreased after treatment for both bracket types (p= 0. The means and standard deviations for the buccal bone height.006) were significantly different between the two bracket types (the initial and final bone thickness was less for the self ligating bracket group) but the change (p=0. The change in bone height was not affected by the initial bone height (p=0.159) and change (p=0.130). The initial (p=0. 13 have indicated that CBCT images can be used to obtain accurate linear and angular measurements. The change in bone thickness was not affected by the change in molar angulation (p=0.007) where the bone thickness decreased when the intermolar distance increased. The initial (p=0. the lesser the change in molar angulation (p=0.006) where the greater the initial bone thickness. The change in bone height depended on the initial bone thickness (p=0. The change in molar angulation was affected by the initial molar angulation where the greater the initial molar angulation.037). which became statistically significant only when combining several measurements. The accuracy of CBCT images for the detection and quantification of periodontal bone defects in three dimensions has been evaluated.220).402). the lesser the change in intermolar distance (p=0. Various studies12. the less the decrease in bone height. The molar angulation decreased after treatment for both bracket types.007). DISCUSSION Information from available CBCT images can provide noninvasive insight into the dynamics of tooth movement. The change in bone height did not depend upon the change in molar angulation (p=0.919) and intermolar distance (p=0.748) however it was affected by the change in intermolar distance (p=0. Others14 found a small systematic error.489) and change (p=0.312). There was no significant difference between right and left side for molar angulation (p=0.767) in molar angulation were not significantly different between the two bracket types.where the greater the initial intermolar distance. Misch et al8 concluded that the three dimensional capability 39 . final (p=0. 11. Mol and Balasundaram7 concluded that CBCT images provide better diagnostic and quantitative information on periodontal bone levels in three dimensions than conventional radiography but the accuracy in the anterior aspect of the jaws was limited.8 ± 4. 16 This appears to verify the usual pretreatment status of posterior buccal bone. 16 The initial bone height and thickness dimensions were comparable for the current study and previous studies.6 to 0. 15. Our findings also showed small.11. a significant amount of bone loss was reported by Garib et al15 who found that RME reduced the buccal bone plate thickness of supporting teeth 0. most probably changes that would be considered clinically insignificant. 15.4 mm at the mesiobuccal area of the first molars. Our data represents baseline information for buccal bone height and thickness in cases of comprehensive orthodontic treatment that can be compared to rapid maxillary expansion (RME) studies.1 ± 4. gingival recession and increased pocket depth. 40 .9 mm and induced bone dehiscences on the buccal aspect where there was a significant reduction of alveolar crest level of 7.4mm.6 mm at the first premolars and 3. they suggested that orthodontic therapy was associated with small amounts of alveolar bone loss. With rapid maxillary expansion. but statistically significant buccal bone loss after orthodontic treatment.of CBCT offered a significant advantage because all defects including buccal and lingual defects could be detected and quantified. Ballanti et al16 found a significant reduction in buccal alveolar bone thickness of maxillary molars with the greatest amount of bone resorption being 0. Rungcharassaeng et al11 found that buccal crown tipping and reduction of buccal bone thickness and height of the maxillary posterior teeth were immediate effects of RME. In a systematic review by Bollen et al17. Garib et al15 also found a negative correlation between the thickness of the buccal alveolar crest at treatment onset and the alveolar crest level changes after expansion.6 Localized recession during orthodontic treatment has been associated with excessive forces that have not permitted the repair and remodeling of the alveolar bone. again. a significant amount of bone loss was reported. and can be associated with orthodontic treatment. We found that the change in bone height depends on the initial bone thickness where the greater the initial bone thickness.So. In the absence of a practical means to assess buccal bone thickness on a routine basis and given the potential for buccal bone loss as noted above. We found that increasing the intermolar distance minimally would negatively affect the bone thickness. This appears to suggest there is a trend and relationship between bone loss and increased transverse dimension. it appears judicious to avoid aggressive transverse arch expansion. Without precise data for intervening magnitudes of expansion. The clinical significance of buccal bone loss is the accompanying gingival recession with exposure of cementum that has been reported to occur at an early age on single or multiple teeth. in cases where substantial and purposeful RME expansion was accomplished.6 Pretreatment buccal bone thickness appears to be a determining factor related to bone loss.5 Gingival recession is always accompanied by bone dehiscence which can happen as a result of uncontrolled expansion of teeth through the cortical plate. 41 . regardless of the appliance used in order to avoid potential bone loss. there is a need for care when decisively increasing posterior arch width. This is in agreement with the findings of Rungcharassaeng et al11 whose results suggest that buccal bone level was better preserved with greater buccal bone thickness. the less the decrease in bone height. in the absence of other data. Morina et al21 found that the torque expression of SLB was less than conventional brackets. 2. the implication is that. It does not appear that one appliance offers an advantage over the other in terms of changes in buccal bone and control of molar angulation and intermolar distance when modest changes in arch form are the goal and result.Claims have been made that SLB can result in broader archforms than conventional brackets. We found no difference in controlling buccolingual angulation of the maxillary first molar between the two bracket types.18 We found that the maxillary intermolar width increased insignificantly for both the SLB group and the NSLB group and there was no significant difference between the two brackets groups. there is a trend that increased arch dimensions may lead to adverse bony changes depending on the patient‟s initial bony status. There is no difference between patients treated with SLB or conventional brackets for buccal bone changes (buccal bone height and buccal bone thickness). Other studies evaluated torque control for maxillary incisors where Pandis et al20 found that SLB were equally efficient in delivering torque to maxillary incisors. On the other hand. Tecco et al19 found that both self ligating and traditional straight wire appliances increased maxillary dentoalveolar widths but there was no significant difference between the groups in patients with mild crowding. 42 . Based on these data and those from RME studies. Buccal bone height and buccal bone thickness decrease significantly after treatment. CONCLUSIONS 1. Consistent with this finding. the less the decrease in bone height. The change in bone height depends on the initial bone thickness where the greater the initial bone thickness. 5. 4. There is no difference between patients treated with SLB or conventional brackets for buccal angulation of maxillary first molar and intermolar distance. 43 . The change in bone thickness is affected by the change in intermolar distance where the bone thickness decreases when the intermolar distance increases.3. The orientation was set to be parallel to the occlusal plane of the first molar.LEGEND Fig 1. the cut was done at the level of the cementoenamel junction. 44 . The trough was drawn to bisect the maxillary first molar. 2 Buccal bone height and thickness measurements 45 .Fig. 3 Landmark identification for buccolingual angulation and intermolar distance measurements 46 .Fig. Fig. 4 Buccolingual angulation and intermolar distance measurements 47 . 59 -0. final and change in bone height (mm) Type SLB Tooth* T1 (Mean ± SD) T2 (Mean ± SD) Change (T1-T2)** M1 7.61 8. SLB: Self ligating brackets Type of bracket Number of patients Age Mean ± SD 14.08 ± 0. P1: Maxillary first premolar *Significant difference between teeth ** Significant difference for the initial values between SLB and NSLB † Significant difference for the initial values between SLB and NSLB †† Significant difference for the change Type SLB 48 .54 1.3y 13.11 ± 0.30 T1: Before treatment.1 ± 3.12 ± 0.07 ± 0.5 ± 4.6 m 19.87 ± 0.08 ± 0. P2: Maxillary second premolar.12 ± 0.43 1.3 ± 1.65 8.22 ± 0.79 ± 0.92 ± 0.54 8.16 ± 0.05 ± 0.37 P1 1.54 2.8 m Table II: Means and standard deviations for the initial. NSLB: Conventional brackets M1: Maxillary first molar.91 ± 0.42 1.11 ± 0.75 ± 0. P2: Maxillary second premolar.Table I: Demographic distribution of patients studied Gender Male Female NS 26 12 14 S 19 6 13 Overall 45 18 27 NSLB: Conventional brackets.62 -0.11 ± 0.14 ± 0.78 ± 0.3y Treatment duration Mean ± SD 20.54 -0.40 0.96 ± 0.80 -0.42 -0.16 NSLB M1 7. P1: Maxillary first premolar * Significant difference between teeth **Significant difference for the change Table III: Means and standard deviations for the initial.40* -0.29 T1: Before treatment.78 ± 0.34 P1 1.1 ± 1.23 ± 0.04 ± 0.56 ** -0.44 * -0.66 ± 0.00 ± 0. NSLB: Conventional brackets M1: Maxillary first molar.14 NSLB M1 2.60 -0.16 ± 0.23 ± 0. T2: After treatment SLB: Self ligating brackets.47 -0. T2: After treatment SLB: Self ligating brackets.20 P1 8.1 m 20.90 ± 0.7 ± 1.5 ± 3.26 P2 7.20 ± 0.21 ± 0.04 ± 0.49 -0.30 P1 9.57 7.96 ± 0.26 P2 1.28 P2 7. final and change in bone thickness (mm) Tooth * T1 (Mean ± SD)** T2 (Mean ± SD) † Change (T2-T1) †† M1 1.3y 14.71 9.38 2.46 -0.21 P2 2.01 ± 0.12 ± 0.59 8.96 ± 0.19 ± 0.11 ± 0. 83 Table V: Means and standard deviations for the initial.41 ± 2.15 ± 2. We would like to thank the Orthodontic Department at Case Western Reserve University for providing us with the CBCT images needed for this study.48 ± 2.23 NS 93.38 ± 3. Ohio.64 T1: Before treatment. T2: After treatment NSLB: Conventional brackets.27 NS 44.86 44. Self-ligating vs conventional twin brackets during en-masse space closure with sliding mechanics.77 ± 3.30 -0.59 94.39 0. final and change in intermolar distance (mm) Type T1 (Mean ± SD) T2 (Mean ± SD) S 45.132(2):223-5.Table IV: Means and standard deviations for the initial.56 ± 2.15 ± 2.22 Acknowledgements We would like to recognize the financial support for this research provided by the Dental Master‟s Thesis Award Program sponsored by Delta Dental Foundation which is the philanthropic affiliate of Delta Dental of Michigan.11 93. References 1. 2007 Aug. 49 . Miles PG.09 ± 3. final and change for molar angulation (⁰) Type T1 (Mean ± SD) T2 (Mean ± SD) S 95.87 ± 5.47 45.39 T1: Before treatment.33 ± 1. SLB: Self ligating bracket Change (Mean ± SD) -0.96 ± 5. Am J Orthod Dentofacial Orthop. and Indiana.15 ± 1. T2: After treatment NSLB: Conventional brackets. SLB: Self ligating brackets Change (Mean ± SD) 0. Self-ligating brackets and treatment efficiency. 2006 Jul. Buchner A. 7. 2008 Sep. 2007 Aug. Behav Res Methods. 2001 Nov. 50 . 2007 Aug. Zachrisson BU. J Periodontol. Am J Orthod. 1980 Nov.2. 4. Mol A. Am J Orthod Dentofacial Orthop.41(4):1149-60. Self-ligating brackets: present and future. 6. 1982 Jul. Miles PG.16(4):431-5. Rinchuse DJ. Effects of incisor repositioning on monkey periodontium after expansion through the cortical plate. Engelking G. 2009 Nov. Statistical power analyses using G*Power 3. Lang AG. Am J Orthod.78(5):511-27. GEiger AM. 8.37(6):319-24. Shanghai Kou Qiang Yi Xue. Harradine NW.132(2):216-22.1: tests for correlation and regression analyses. Dentomaxillofac Radiol. Mucogingival problems and the movement of mandibular incisors: a clinical review. 9. Clin Orthod Res. Accuracy of cone beam computed tomography for periodontal defect measurements. Sarment DP.4(4):220-7. 5. In vitro cone beam computed tomography imaging of periodontal bone. Balasundaram A. Faul F. The clinical implication of self-ligating brackets. 3. Qian YF. Yu YL. Erdfelder E.82(1):23-32. Misch KA. Yi ES.77(7):1261-6. Hans MG.136(1):19. Palomo L. Cavalcanti MG. Taylor G. 2009 Jul. 14. Janson G. Erdfelder E. 11. Fernandes AY. Lopes PM. 2007 May. 2009 Apr 20. Sales MA. Huang JC. Baumgaertel S.132(4):428. 2006 Jun. Caruso JM. Moreira CR. de Freitas MR.10. 12. Dentomaxillofac Radiol. Henriques JF. Buchner A. 15.37(2):80-93. Behav Res Methods. Comparison of cone beam computed tomography imaging with physical measures. Lang AG.428. Maki K. Assessment of linear and angular measurements on three-dimensional cone-beam computed tomographic images. Factors affecting buccal bone changes of maxillary posterior teeth after rapid maxillary expansion.39(2):175-91.e1. Palomo JM. Am J Orthod Dentofacial Orthop. Periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders: a computed tomography evaluation.25. discussion 25-8. 13. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. Am J Orthod Dentofacial Orthop. behavioral. Faul F. G*Power 3: a flexible statistical power analysis program for the social. and biomedical sciences. Stratemann SA.e8. 2008 Feb. 51 . Rungcharassaeng K.129(6):749-58. Reliability and accuracy of cone-beam computed tomography dental measurements. Kim J. Am J Orthod Dentofacial Orthop. Kan JY. Miller AJ. Hatcher DC. Garib DG. 2007 Oct. 79(1):24-9.16. 2009 Mar. Bourauel C. ceramic. Bakko DW. 21. Morina E. Maxillary arch width changes during orthodontic treatment with fixed self-ligating and traditional straight-wire appliances. 20. The effects of orthodontic therapy on periodontal health: a systematic review of controlled evidence.54(1):9-11.9(4):193-8. Tecco S. Self-ligating brackets in orthodontics: Do they deliver what they claim? Aust Dent J. Strigou S. Pandis N. J Am Dent Assoc. Eur J Orthod. Jager A. Baccetti T. Cozza P. Miles PG. Immediate and post-retention effects of rapid maxillary expansion investigated by computed tomography in growing patients. Angle Orthod. Fanucci E. Huang GJ. Cunha-Cruz J. 17. Tete S. Perillo L. Hujoel PP. Orthod Craniofac Res. 2009 Jan. 2008 Jun. Lione R. 18. 2006 Nov. 2008 Apr. Chimenti C. World J Orthod. and plastic brackets. 19. 52 .139(4):413-22. 2009 Winter. Ballanti F. Eliades T. Franchi L. Torque expression of self-ligating brackets compared with conventional metallic. Festa F. Eliades T. Pandis N. Bollen AM. Maxillary incisor torque with conventional and self-ligating brackets: a prospective clinical trial.30(3):233-8.10(4):290-4. Others3 found a small systematic error. 8 This appears to verify the usual pretreatment status of posterior buccal bone. 7. Various studies1.CHAPTER 4 DISCUSSION AND CONCLUSIONS Information from available CBCT images can provide noninvasive insight into the dynamics of tooth movement. Misch et al4 concluded that the three dimensional capability of CBCT offered a significant advantage because all defects including buccal and lingual defects could be detected and quantified. which became statistically significant only when combining several measurements. The accuracy of CBCT images for the detection and quantification of periodontal bone defects in three dimensions has been evaluated.6. 2 have indicated that CBCT images can be used to obtain accurate linear and angular measurements. 7. Our data represents baseline information for buccal bone height and thickness in cases of comprehensive orthodontic treatment that can be compared to rapid maxillary expansion (RME) studies. Mol and Balasundaram5 concluded that CBCT images provide better diagnostic and quantitative information on periodontal bone levels in three dimensions than conventional radiography but the accuracy in the anterior aspect of the jaws was limited. 8 The initial bone height and thickness dimensions were comparable for the current study and previous studies. 53 .6. In a systematic review by Bollen et al9. most probably changes that would be considered clinically insignificant. gingival recession and increased pocket depth. With rapid maxillary expansion. there is a need for care when decisively increasing posterior arch width. Rungcharassaeng et al6 found that buccal crown tipping and reduction of buccal bone thickness and height of the maxillary posterior teeth were immediate effects of RME. Garib et al7 also found a negative correlation between the 54 . a significant amount of bone loss was reported.1 ± 4.4 mm at the mesiobuccal area of the first molars.8 ± 4. but statistically significant buccal bone loss after orthodontic treatment. Without precise data for intervening magnitudes of expansion.9 mm and induced bone dehiscences on the buccal aspect where there was a significant reduction of alveolar crest level of 7. We found that increasing the intermolar distance minimally would negatively affect the bone thickness.6 to 0. the less the decrease in bone height. This is in agreement with the findings of Rungcharassaeng et al6 whose results suggest that buccal bone level was better preserved with greater buccal bone thickness.6 mm at the first premolars and 3. in cases where substantial and purposeful RME expansion was accomplished. We found that the change in bone height depends on the initial bone thickness where the greater the initial bone thickness. a significant amount of bone loss was reported by Garib et al7 who found that RME reduced the buccal bone plate thickness of supporting teeth 0. regardless of the appliance used in order to avoid potential bone loss. Ballanti et al8 found a significant reduction in buccal alveolar bone thickness of maxillary molars with the greatest amount of bone resorption being 0. So. they suggested that orthodontic therapy was associated with small amounts of alveolar bone loss. This appears to suggest there is a trend and relationship between bone loss and increased transverse dimension.4mm. Our findings also showed small. Morina et al15 found that the torque expression of SLB was less than conventional brackets. We found no difference in controlling buccolingual angulation of the maxillary first molar between the two bracket types. Consistent with this finding.thickness of the buccal alveolar crest at treatment onset and the alveolar crest level changes after expansion. The clinical significance of buccal bone loss is the accompanying gingival recession with exposure of cementum that has been reported to occur at an early age on single or multiple teeth.10 Pretreatment buccal bone thickness appears to be a determining factor related to bone loss.12 We found that the maxillary intermolar width increased insignificantly for both the SLB group and the NSLB group and there was no significant difference between the two brackets groups. Other studies evaluated torque control for maxillary incisors where Pandis et al14 found that SLB were equally efficient in delivering torque to maxillary incisors. and can be associated with orthodontic treatment.11 Gingival recession is always accompanied by bone dehiscence which can happen as a result of uncontrolled expansion of teeth through the cortical plate. 55 . Tecco et al13 found that both self ligating and traditional straight wire appliances increased maxillary dentoalveolar widths but there was no significant difference between the groups in patients with mild crowding. again.10 Localized recession during orthodontic treatment has been associated with excessive forces that have not permitted the repair and remodeling of the alveolar bone. it appears judicious to avoid aggressive transverse arch expansion. In the absence of a practical means to assess buccal bone thickness on a routine basis and given the potential for buccal bone loss as noted above. Claims have been made that SLB can result in broader archforms than conventional brackets. On the other hand. 5. CONCLUSIONS 1. The change in bone thickness is affected by the change in intermolar distance where the bone thickness decreases when the intermolar distance increases. 3. in the absence of other data. the implication is that. Buccal bone height and buccal bone thickness decrease significantly after treatment. 56 . the less the decrease in bone height. Based on these data and those from RME studies. 4.It does not appear that one appliance offers an advantage over the other in terms of changes in buccal bone and control of molar angulation and intermolar distance when modest changes in arch form are the goal and result. The change in bone height depends on the initial bone thickness where the greater the initial bone thickness. there is a trend that increased arch dimensions may lead to adverse bony changes depending on the patient‟s initial bony status. There is no difference between patients treated with SLB or conventional brackets for buccal bone changes (buccal bone height and buccal bone thickness). 2. There is no difference between patients treated with SLB or conventional brackets for buccal angulation of maxillary first molar and intermolar distance. 136(1). (2009a). J. & Hans... M. 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