Zirconia Implant May 2013

J Clin Periodontol 2013; 40: 553–562 doi: 10.1111/jcpe.12093 One-piece zirconia oral implants: one-year results from a prospective case series. 2. Three-unit fixed dental prosthesis (FDP) reconstruction Kohal R-J, Patzelt SBM, Butz F, Sahlin H. One-piece zirconia oral implants: one-year results from a prospective case series. 2. Three-unit fixed dental prosthesis (FDP) reconstruction. J Clin Periodontol 2013; 40: 553–562. doi: 10.1111/ jcpe.12093. Ralf-Joachim Kohal1, Sebastian B. M. Patzelt2,3, Frank Butz3 and Herman Sahlin4 Department of Prosthodontics, School of Dentistry, Albert-Ludwigs University, Freiburg, Germany; 2Department of Periodontics, School of Dentistry, University of Maryland, Baltimore, USA; 3Department of Prosthodontics, School of Dentistry, Albert-Ludwigs University, Freiburg, Germany; 4Nobel Biocare, Gothenburg, Sweden 1 Abstract Aim: To evaluate the clinical and radiological outcome of one-piece zirconia oral implants for three-unit fixed dental prosthesis (FDP) replacement after 1 year. Materials: Twenty eight patients were recruited for the investigation and signed an informed consent. All patients were treated with a one-stage implant surgery and a three-unit immediate temporary restoration on two one-piece zirconia implants. The implants were fabricated of yttria-stabilized tetragonal zirconia (y-TZP). The endosseous part of the implants was tapered with a porous surface. A total of 56 implants were inserted in the 28 patients. A total of 12 implants were placed in the upper jaws (six in the anterior area and six in the posterior area) and 44 in mandibles (all in the posterior area). At implant insertion and after 1 year, standardized radiographs were taken to evaluate the peri-implant bone loss. To evaluate any influences from different baseline parameters on the marginal bone loss a univariate analysis was performed. Clinical soft tissue parameters probing depth (PD), clinical attachment level (CAL), modified bleeding index (mBI) and modified plaque index (mPI) were recorded. Implant cumulative survival rates were calculated using actuarial life table analysis. Changes in the clinical variables were assessed using the Wilcoxon Signed Ranks test (PD, CAL) and the Sign test (mBl, mPl). All significance tests were conducted at a 5% level of significance. Results: After 1 year, one implant was lost resulting in a survival rate of 98.2%. The patient was excluded from further analysis. The marginal bone loss after 1 year amounted to 1.95 mm. In 40% of the patients a bone loss of at least 2 mm and in 28% of the patients a loss of more than 3 mm were observed. The PD decreased for implant and tooth sites over time, the values being significantly higher for implants than for teeth. Over 1 year, the CAL increased slightly around the implants and decreased around the teeth. At the 1-year follow-up, the CAL at the implant sites was statistically significantly higher than at the reference teeth. The mBI was significantly lower at implants than at teeth. The same result was found for the plaque index. Conclusions: A high frequency of increased radiographic bone loss (>2 mm) after 1 year around the presented one-piece zirconia implant system was found. The bone loss seems to be higher compared to the very limited availability of zirconia implant data. Therefore, within the limits of the present investigation, it may be concluded that the presented zirconia implant system possibly performs inferior to conventional titanium implants and to other zirconia implants regarding peri-implant bone loss. Key words: clinical investigation; fixed dental prosthesis; oral implant; prospective; three-unit bridge; zirconia Accepted for publication 3 February 2013 © 2013 John Wiley & Sons A/S 553 28 patients were recruited and were informed on the content and duration of the study. The need for extended bone augmentation before implant installation to obtain a prosthetically correct implant position was an exclusion criterion as well. (2010) and Payer et al. the patients’ medical history was recorded and a clinical and radiographic examination was performed. Aboushelib €ller et al. Switzerland. In addition. The positive biomechanical as well as pre-clinical biological results might encourage the use of zirconia implants and therefore several implant companies brought zirconia oral implants to the market (Silva et al. 2010. heart disease or disease of the circulatory system. Local contraindications were.3 mm and minimal length of 10 mm. 2009. 2012). ulcers. According to the available bone. those implants are on the market for a certain period of time. Cannizzaro et al. Freiburg. Thayngen. Numerous additional animal experiments. The zirconia implants and the zirconia frameworks were provided by Nobel Biocare. Materials and Methods Conflict of interest and source of funding statement Dr. bone metabolism disorders. Switzerland. 2010.e. 2010. BPISystems. the biological behaviour (i. Gothenburg. they had to sign an informed consent. 2010. Stadlinger et al. disorders of the endocrine system and pregnancy. 2010) showed that the utilized zirconia implants developed a similar bone-to-implant contact as did the titanium implant controls. 2012b) and three clinical investigations for the White Sky implant system of Bredent medical (Borgonovo et al. The areas of implantation were evaluated with a cone beam computed tomogram (Newtom 3G. Koch et al. the scientific backup on the clinical use of such implants is lagging behind or non-existent. (2010). were published at some period after the launch of the respective implant system. 2011). 2012). Dentalpoint. no clinical investigations could be found for the Incermed system. Pre-treatment examination This study was a prospective investigation. Main inclusion criteria were that the subjects were between 18 and 70 years old. Schliephake et al. Mo of those investigations could even show slightly superior results of the zirconia implants (Koch et al. Sahlin is an employee of Nobel Biocare. 2012). Ceraroot. Dr. another aspect of interest might be that all clinical investigations or reports. Germany). For the remaining zirconia implant systems no scientific literature regarding implant survival/ implant success could be found in peer-reviewed journals (case reports excluded). Kohal was a lecturer for Nobel Biocare from 2005 to 2008 and Dr. when a non-systematic electronic search (key words: zirc* AND impl*) and a hand search were performed. 2010) (e. Sindelfingen. osseointegration) of zirconia implants was elucidated (Wenz et al. Gahlert et al. Granollers. Apart of the investigations of Cannizzaro et al. Sweden. 2007. 2012). However. Two scientific reports could be located for the CeraRoot System (Oliva et al. © 2013 John Wiley & Sons A/S . 2009. Stadlinger et al. supported the findings that zirconia implants obtained an amount of osseointegration not different from titanium implants (Gahlert et al. Metoxit. infectious disease. Marburg. Some et al. The investigation was approved by the ethics committee of the University Medical Center Freiburg. in contrast to this study. Prior to the start of the study. Aboushelib et al. Z-systems. 2010). – to name a few). The soft and hard tissue response around these implants was the secondary objective. A compilation of animal experiments in the review of Silva and co-workers (Silva et al. Switzerland. Depprich et al. Lambrich & Iglhaut 2008. and some of these data are of questionable scientific quality (Andreiotelli et al. Butz was a lecturer for Nobel Biocare in 2007. haematological disorders. It was the objective of this investigation to obtain 1 year data on the survival/ success of a newly developed zirconia implant system when applied as abutments for three-unit fixed dental prostheses. Cohort investigations with a prospective study design are rare for zirconia oral implants (Payer et al. Germany implant surgery and a three-unit immediate temporary restoration supported by two implants. a sufficient bone volume in the prospective implant regions had to be present for receiving implants with a diameter of at least 4. Gothenburg. 2011. In this context. published after the review of Silva et al. metabolic disease. 2010. for example. Germany (investigation number: 337/04). 2010. 2012). The minority of these companies has clinical research data for their implant systems. Germany. general health conditions that did not permit a surgical procedure. (2012). all other reports had a low level of evidence due to a questionable study design (Depprich et al. Oensingen. Exclusion criteria were among others: alcohol or drug abuse. Although. This investigation was supported by a grant from Nobel Biocare. tumours. Zurich. All 28 patients were treated with a one-stage Before treatment. a minor augmentation procedure to cover exposed threads due to deficient sites was not an exclusion criterion. it was the aim of the present cohort investigation to clinically evaluate a zirconia implant system prior to market launch. Furthermore. 2011. Spain. Payer et al. Incermed. for example. Silva et al. 2010).554 Kohal et al. Andreiotelli et al. Lausanne. 2008. had to be in need of an implant-supported three-unit fixed dental prosthesis (FDP) supported by two implants. Switzerland. 2010.g. Germany. 2012a. Newtom. disturbance of the hematopoietic system. Mellinghoff 2006. Therefore. Marburg. Bredent medical. Creamed. and had to be systemically healthy. the lengths and the diameters of the implants were selected. wound healing disturbances. Sweden grant # T-114. Senden. Five clinical investigations were found for the z-systems system (Blaschke & Volz 2006. For example. Zirconia oral implants are a topic of interest to dental researchers and dentists. In different review articles. 2010. reasons to believe that the treatment might have a negative effect on the subject’s psychological situation were exclusion criteria. The subjects had to have a stable occlusal relationship with no severe parafunctional habits and the implant sites had to be free of infection and/ or tooth remnants. 2% chlorhexidine solution and were instructed not to clean the surgical areas with their tooth brush for at least 1 week. After cementation of the temporary bridges. all non-smokers) were included in this investigation and a total of 56 implants were placed supporting 28 three-unit fixed dental prostheses. The flap design for the placement of the implants into the healed sites was flapless. The topographical analysis of the implant surface revealed for Sa (average surface roughness) 1. two implants with a flapless procedure). 3M Espe. After a week. There was no restriction in the study design regarding the type of implant receiving sites. 1). Implant placement The implants were placed under peri-operative antibiotic coverage (Clindamycin 300 mg N1. evaluated the radiographs indepen- For prosthesis fabrication. and for Sdr (developed surface area) 83% (Sennerby et al. 3 9 per day. 4. If there was a problem in alignment or reproducibility in the holder position. Of the 56 implants. NobelBiocare. whereas the coronal part. Sweden). 12 implants were placed in the upper jaws (6 in the anterior area and 6 in the posterior area) and 44 in the lower jaws (all in the posterior area). a soft tissue punch technique or a full-thickness mucoperiosteal flap. 24 patients were older than 41 years. Sweden) and a glass-ceramic veneering material (NobelRondo. The lower edge of the implant abutment part – where the transition zone between the straight abutment part and the implant threads was located – was utilized as the reference point for the measurements of bone remodelling/ loss (Fig. Finally. the implant abutment part was slightly prepared for the incorporation of the three-unit temporary bridge. 2005). had a machined surface. after FDP delivery. 2005). The transmucosal part of the one-piece zirconia implants was also roughened in its apical part.09/lm2. The endosseous part of the implants was tapered and roughened (ZiUniteTM surface technology. A porous implant surface was achieved by a sintering-on technique of zirconia slurry onto the implant cylinder that contained zirconia powder and a burnable pore former. as well as the approximal contacts. Care was taken to parallel the alignment of the x-ray film in the film holder to the anticipated long axis of the implants. Delivery of the prosthesis jaw. All implants were CE-marked.3 mm Regular Platform (RP) and 5. Dentsply Rinn. leaving a porous implant surface. Further controls and professional cleanings of the surgical areas were performed after 2. The implants were either placed immediately into extraction sockets or in so called healed sites (healing time at least 4–6 months). starting 1 day before surgery and lasting 2 days after the day of surgery) and pain control was executed using ibuprofen. The status quo of the marginal bone was recorded by taking standardized radiographs with a customized intra-oral x-ray film holder bite block (Rinn XCP. the entire procedure was repeated until a satisfying result was obtained. (Sennerby et al. In a malleable condition. for Sds (value for the number of peaks per area unit) 0. excess material was removed and the film holder position again inspected intraorally for fit and alignment. impressions of the implants were performed after approximately 6 weeks in the lower jaw and 14 weeks in the upper . © 2013 John Wiley & Sons A/S After implant placement. Summary information on patients and implants Overall. the acrylic was attached to the holder. Bad Homburg. Sweden. The three-unit fixed dental prostheses were conventionally cemented using glassionomer cement (KetacTM Cem.24 lm. for the placement of the bridge retainer (abutment part). All implants were immediately restored with provisionals that were re-lined using a self-curing acrylic material. The radiographs at implant placement were used as baseline values.0 mm wide [Wide Platform (WP)].3 mm. All centric and eccentric contact points. The implant lengths available were 10. five implants (9%) were placed in extraction sockets (two implants in a flapped procedure) and 51 implants in healed sites (five implants using a punch technique. 28 patients (11 females and 17 males. Germany). All-ceramic three-unit bridges were processed with a zirconia framework (Procera. the patients were scheduled for wound inspection and for suture removal. All implants were placed according to the manufacturer’s recommendations. Then. Bone remodelling/loss from implant placement to the 1-year follow-up was evaluated. Germany) were meticulously removed. A radiologist at the Gothenburg University. 13 and 16 mm and the diameters were 4. the pore former burnt out. Sweden). Gothenburg. Nobel Biocare). the holder including the x-ray film was brought into the intended position in the patient’s oral cavity.Zirconia implants for fixed prosthesis Investigational zirconia implants 555 The yttria-stabilized tetragonal zirconia polycrystal implants (y-TZP. GC Germany. The cement remnants were thoroughly removed and the patients inspected again after one to three days. USA). After curing of the acrylic material under continuous cooling with water spray. standardized radiographs were taken after implant placement. NobelBiocare. Neuss. Elgin. 30 implants had a diameter of 5 mm and 26 of 4. the patients were provided with maintenance instructions which consisted of rinsing the oral cavity with a 0. The patients used the analgesic after the surgery according to their individual needs. were removed to avoid any forces from occlusion onto the implants. The film holder was individualized with a self curing acrylic material before implant placement. zirconia implants) (Nobel Biocare) featured a design similar to the titanium one-piece NobelDirectTM implant (Nobel Biocare. Follow-ups Radiographic assessment With the application of the individualized x-ray holder (long-cone parallel technique). and at the 1-year follow-up. 6 and 8 weeks and then on a monthly basis until the delivery of the final prosthesis. temporary cement remnants (Freegenol. While sintering the implant coating. A calibration of all radiographs was performed using the known width of the base of the abutment part of the ceramic implants. The values for the PD and for the CAL were rounded to the nearest millimetre. the modified bleeding index (mBI) according to Mombelli et al. Bone loss criteria and implant success rating In the present investigation. mPI) and the values for the implants were compared to values obtained from the neighbour teeth using the Mann–Whitney U-test. Figures 2 and 3 present radiographs of two patients that experienced increased bone loss. The cumulative survival rate of the implants after 1 year was 98. Again. the rec€ ommendation of Ostman et al. Changes in the clinical variables over time were assessed using the Wilcoxon Signed Ranks test (PD. To evaluate the effects of ordered categorical and continuous baseline variables. the implant sites gained some bone. The implant sites in seven patients (28%) lost more than 3 mm of bone and implant sites in three patients (12%) even lost more than 4 mm of peri-implant bone.2%. including mean values and standard deviations. © 2013 John Wiley & Sons A/S . failed after 21 days and had to be removed. One implant was lost in one patient prior to reconstruction. CAL) and the Sign test (mBl. At the 6-month follow-up. index (mPI) also according to Mombelli et al. Bone remodelling was calculated for each side of the implant (mesial and distal) separately. the implant sites lost more than 2 mm of bone. In 10 patients (40%). 1. The clinical evaluation around the implants as well as around the adjacent natural teeth comprised the recording of probing depth (PD). USA). Life-table analysis (on implant level) One implant. The soft tissue measurements were performed using a periodontal probe. Marginal bone remodelling (Marginal bone loss/gain on patient level) (Table 1 & 2) Fig.65 mm could be observed from implant insertion to the bridge delivery. In two patients (2%). The marginal bone loss evaluation from implant insertion to prosthesis insertion could be evaluated for 24 patients (for three patients one of the x-rays was rated as non-readable) and for 25 patients (for two patients the x-rays from the insertion time point were rated as non-readable) from implant insertion to the 1-year follow-up. in nine patients (38%) implant sites lost more than 2 mm of peri-implant bone. were used for the presentation of the bone remodelling results. 25 patients were seen (two patients did not attend the follow-up due to time conflicts). However. mBI. their success grade I was applied to implants showing 2 mm bone loss after 1 year and no clinical and radiographic signs of pathology. CAL. Spearman correlation coefficient was used. mPl). At the 1-year follow-up.0. All significance tests were two-tailed and conducted at a 5% level of significance. (1987). as the difference between bone levels at two time points. IBM Corporation. all 27 patients were available for clinical and radiographic evaluation. NY. From implant insertion to the 1-year follow-up. Results Status of follow-up and implant failure dently. Clinical evaluation The follow-ups were scheduled for 6 months and 1 year after implant placement. Therefore. clinical attachment level (CAL). Mean and standard deviation values were calculated for the clinical variables (PD. She was not involved in the clinical part of the investigation. Descriptive statistics. was adopted. implant sites in two patients (2%) gained some bone. The mean value for all implants in each patient was further calculated from the mean of each implant. A bone loss of 1. No signs of acute infection were detectable. The implant was mobile 2 weeks after insertion and had to be removed. (1987). Statistical analysis Implant cumulative survival rates were calculated using actuarial life table analysis (Altman 1999). and the modified plaque Of the 28 patients. an average bone loss of 1.556 Kohal et al. The effects of dichotomous baseline variables on bone remodelling were evaluated using the Mann– Whitney U-test. (2007) that more than 1 mm of bone loss during the first year is acceptable for one-piece implants. Armonk. 27 patients received the final FDP. The coronal reference points differed in height at the mesial and distal implant aspect due to the starting thread. All analyses were performed using SPSS (version 20.95 mm was found. The success grade II was applied to implants showing no pathology but a bone loss/resorption of 3 mm at the 1-year follow-up. Indication of reference points for the bone level measurements. No further implant losses occurred. A univariate analysis of marginal bone loss from implant insertion to the 1-year follow-up was performed evaluating the effect of different baseline variables. The average of mesial and distal remodelling was then calculated for each implant site. A bone loss of more than 3 mm occurred around implants in three patients (13%). placed into an extraction socket. 6 À1. Peri-implant soft tissue evaluation (on patient level) (Table 4) 557 Table 2.0 X-ray not usable À1.3 À2.059).0 À6.2 0.0 À1.0 À4.3 À4.5 À0.39 mm around the reference teeth was observed (p = 0.3 À0.5 À1.7 À2.3 X-ray not usable À1.04 mm at the reference teeth when the bridges were installed.0 À0.9 À0.3 X-ray not usable At the time-point of the insertion of the three-unit fixed dental prostheses.1 to À4. An increased bone loss around the distal implant is visible.0 mm 3 (13) < À 4.1 À0.2 0. Until the 1-year follow-up.6 À1.284).0 À1.2 À1.0 À7.007).2 À3.5 À2. Marginal bone remodelling (on patient level) Implant Implant insertion insertion to Prosthesis to 1-year insertion follow-up Number 24 Mean value (mm) À1.3 À1.001).65 SD (mm) 1. A correlation could be found for bone loss and the flap design (p = 0.5 À1.5 À4.8 À5. Bone loss at all individual implant sites Patient Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Mesial bone loss anterior implant Distal bone loss anterior implant Mesial bone loss posterior implant Distal bone loss posterior implant À0.5 À4.0 À4.4 1.5 1.0 À6.0 À0.0 À1.1 À2.0 mm 0 (0) © 2013 John Wiley & Sons A/S 25 À1.4 À0.65 mm and for the teeth 1.3 À2.5 À2.5 À2.8 À1. 2008) were applied to the present findings of bone loss. the PD decreased from prostheses insertion to the 1-year followup.97 mm at 1 year.9 X-ray not usable À3.4 Radiograph from insertion time point not readable À1. the CAL increased slightly around the implants to 3.0 À1.Zirconia implants for fixed prosthesis When the success criteria defined € according to Ostman and co-workers € (Ostman et al.8 0.27 n (%) >0 mm 2 (8) 0 mm 0 (0) À0. 2.0 mm 6 (25) À2.5 À5. At the 1-year follow-up.5 À1. 62% of the patients were classified as success grade I and 87% as success grade II at the time-point of FDP installation.6 2.24 mm (p = 0.1 to À2.0 1.5 0.95 1.0 À5.3 À0. At the 1-year follow-up.0 À1.1 3.5 À4.8 0.584) and decreased around the teeth to 2.5 À2.1 À0.3 À4.9 À0. The difference between implants and teeth was again statistically significant (p < 0.3 À1.5 À2. a mean PD of 2.3 À1. Implants either placed without a flap or implants placed with the punch technique showed significantly more bone loss than implants that were placed in a flapped approach.3 À1.0 0.0 mm 7 (29) À1. 60% of the patients were success grade I and 72% success grade II.0 À7.2 À2.0 À5.5 À2. .1 to À1.9 0. dropout À0. The reduction in PD was significant for the teeth (p = 0.432).1 to À3.0 À3.0 À5. The upper radiograph was taken at implant insertion.1 À2.3 À5. The PD for implants was 2.5 À1.7 The CAL had a mean of 3.4 À1.5 À1.0 0.0 À4. 2007.85 mm around the zirconia implants and of 2.8 À4.9 ? À0.7 À2.69 mm (p = 0.2 À1.71 N (%) 2 (8) 0 (0) 7 (28) 6 (24) 3 (12) 4 (16) 3 (12) Fig.5 X-ray not usable À5.0 À4.002) but not for the implants (p = 0.4 Implant loss.6 À0. At the implant sites as well as at the tooth sites.01).0 0. The univariate analysis of the baseline variables possibly influencing the bone loss around the implants is shown in Table 3.0 mm 6 (25) À3. Radiograph from insertion time point not readable À2.4 À1.14 mm at the implant sites and 3. The difference was statistically not significantly different (p = 0.6 2.0 À1. the lower radiograph at the 1-year follow-up. the CAL at the implant sites was Table 1.5 À1. 2008. 2012). 1987) was slightly higher at the implants (0.65 mm. the indication of implant placement was the single tooth restoration. At prosthesis insertion. The upper radiograph was taken at implant insertion.014). Ganeles & Wismeijer 2004. the mPI was 0.026).35.558 Kohal et al. (2011) reported mean PD of 3. 2012). In the current investigation.72 mm around implants and 2. The decrease in both groups was not statistically significant (implants: p = 0. mBI: 0. Romanos et al. Cutrim et al. 2007. The success rate dropped to 60% when applying the success grade I (bone loss 2 mm) according to € Ostman et al.37–2. the mBI decreased at both – implants and teeth – sites. An increased bone loss around the distal implant is visible. 2011). and better than other investigations on one-piece zirconia implants showing survival rates of 87. Altthough PDs and CALs were significantly higher around the implants than around the teeth. this result was shown to be a normal finding. Such a correlation. 2010. The results of the present investigation corroborated the results obtained in the previous investigation of our group when using the one-piece zirconia implant for single tooth reconstruction (Kohal et al. cantly lower in comparison to the literature for immediately restored € implants (Ostman et al.27.30.001). 2008. 2012). € Finne et al.51 for the implant sites and 0.46) compared to the reference teeth (0.09. the mean pocket PD was 3. Payer et al. the lower radiograph at the 1-year follow-up. 2007. In their recent investigation they showed that after a follow-up period of 5 years. Ostman et al. Since the peri-implant soft tissue conditions did not indicate towards any pathology (PD: 2. Cooper et al.15). Kohal et al.15. 2012. De Bruyn et al. teeth: p = 0. the mBI (Mombelli et al. however. one implant was lost. the clinical parameters in the present investigation did not indicate the presence of any peri-implant tissue problem. giving a survival rate of 98. At bridge installation. 2002). p = 0. could not be found in the investigation of one-piece zirco© 2013 John Wiley & Sons A/S Fig. These results were supported by Wolleb et al. The success rate of the implants in our study was considerably lower than the survival rate when bone loss was considered. the reason(s) for the increased frequency of bone loss of ! 2 mm have to be attributed to factors other than an inflammatory reaction to plaque accumulation and bacterial burden. 2001. Van de Velde et al. p = 0. During the interval of this 1 year investigation. In a recent report (Kohal et al.078.523). showed a similar development over time. At the 1-year follow-up. 2008.39 mm around implants and of 2.51 for the reference teeth (p = 0. The implant survival rate in our investigation was comparable to the implant survival rates reported in investigations over different evaluation periods with immediately restored implants (Chaushu et al. mPI: 0. Discussion This case series is the first report on using one-piece zirconia oral implants for three-unit fixed implant supported reconstructions. It was stated that periimplant soft tissues did not give as much resistance to probing as the periodontal tissues (Ericsson & Lindhe 1993. Schou et al. p = 0. Nissan et al. The plaque index (mPI).44 mm around reference teeth after 1 year. The univariate analysis of the marginal bone loss evaluating the effect of different baseline variables revealed that the flap design had an influence on periimplant bone loss. The implants were immediately temporized after insertion and definitively restored after 8 to 16 weeks. At the 1-year follow-up.2%. 2010.09) of the peri-implant tissues.95 mm) after 1 year has to be taken into consideration. 3.023). Crespi et al. However. p = 0.5% to 95% (Cannizzaro et al. teeth: 0. (2007) and to 72% when success grade II (bone loss 3 mm) was used. These success rates after 1 year were signifi- . Zembic et al. statistically significantly higher than at the reference teeth (p = 0. the indication was extended towards the rehabilitation of patients with a three-unit FDP. for this high survival rate the increased bone loss (1. was significantly different from the teeth (0. 2010. 2012). (2012). Clinical investigations have also shown that probing values around implants are generally higher than around teeth. the values dropped significantly in both groups (implants: 0. 2012).484).001.36 mm around teeth. however. Although increased bone loss was found radiographically.669). The value for implants (0. The difference between implants and teeth was – similar to our investigation – of statistical significance (Cutrim et al. After 1 year. 2010.31–3. Animal investigations demonstrated that even in healthy conditions the tip of a periodontal probe was closer to the bone around implants than around teeth. 2010. the implant sites showed statistically less plaque than the teeth (p = 0. 52 (1.2) À1.8) À2. Ostman et al.65 (1.95 (2.0 À1. Investigations on other zirconia one-piece implant systems did not report on cases with increased bone loss (Cannizzaro et al.5) À1.0) À2.01 À3. 2012.27 Correlation r p-value 559 0.90 0.8) 0.7–0. The heterogeneous surgical protocol of immediate and late placed implants as well as the flapless and the punch technique with the rela© 2013 John Wiley & Sons A/S tively small number of subjects have to be regarded as one limitation of this study.5) À1. (2012) presented a mean bone loss of 1. Payer et al.62 (2.5) À1. 2007. Since we did not use a control group without immediate loading.0) À2.01 mm after 1 year and 1.4 to 1. 2008.94 (2.29 mm after 2 years and the authors did not indicate that increased bone loss occurred with the use of their zirconia implant.5 to 2.2) À1. Univariate analysis of marginal bone loss from implant insertion to the 1-year follow-up (three-unit fixed dental prosthesis) Difference Mean (SD) Jaw type Maxilla Mandible Ant-post Anterior Posterior Position Posterior mandible Other positions Smoking No Yes Bruxism before treatment No Yes Bone quality 1 2–3 Bone quantity A B C D Bone level at placement Platform RP WP Implant length 10 mm 13 mm 16 mm Flap design No flap Punch Flap Site Immediate Healed Bone grafting No Yes Insertion torque 45 >45 À2.08 À0.13 (1. As discussed in the report on single tooth restorations (Kohal et al.48 0. confidence interval. our investigation has been a prospective case series.5) À2.39 0.83 (2. However.3) À2.8 to 9. Zembic et al.02 (2.02 (2. Zembic et al.82 (4.1 95% CI À3.07 0.0) À1.0) À2. 2008. 2012).48 (2.2 to 1.37 – – – – 0. Van de Velde et al. De Bruyn et al. 2012).97 À0. standard deviation. 2010.1) – À1. the crown margins were placed only slightly intra-crevicularly and utmost care was given (retraction cords were placed during cementation) to remove all cement remnants. However. In the investigations reporting on increased bone loss with the onepiece titanium implants. Payer et al. Although the increased bone loss in our investigation seemed to be correlated with flapless approach. 2007). there must be other factors related to the bone loss which could not be found with the evaluated variables in our investigation.3 to 1. no differences on bone loss were reported in other investigations when the flapless/punch technique was compared to raising a flap for implant placement (Becker et al. Therefore.6) (1.6 À1.0) À1.2) À1.5) À4. A control group featuring titanium implants that would . nia implants applied for single tooth reconstructions (Kohal et al. Although.0) À1. € 2007.13 (2. 2010.3 À10.2) À1. 2006.69 SD. However.31 À2. Cannizzaro et al. 2011.1) – À1.4 – – À0. 2012) as well as two-piece titanium implants (Proussaefs & Lozada 2004. 2012) presented a marginal bone loss much lower than in above mentioned investigations and lower than in the present investigation on one-piece zirconia implants.11 (2. CI. it was discussed that one possible reason for the bone loss could have been immediate loading (Albrektsson et al. this finding. however.90 (1.41 0. Similarly.7) (2.93 (2. Sennerby et al. the increased bone loss in our investigation seems not to be related to a single variable but is to be assumed to result from a combination effect of different variables.87 À2. 2012) which is similar to the zirconia ceramic implant design.13 (3.Zirconia implants for fixed prosthesis Table 3.8 À1. other authors reported similar bone loss problems using the one-piece Nobel Direct implant design (Albrektsson et al.1) À1. € Ostman et al.20 (1. Crespi et al.98 (2. 2010.4) À4.1 0.27 – – 0. one major shortcoming is that it was not designed as a randomized controlled clinical trial.21 À2.87 (2. is not supported by other investigations.28 À0. several investigations with comparable research designs with immediate loading of the Nobel Direct implants (Siepenkothen 2007.0 to 1.1 p-value 0.52 À5. Finne et al.31 (1.3 to 3.12 0.66 (1.0) À1.2) À2.31 0. Siddiqui et al.83 (2. 2012).9 mm around the zirconia implants in their investigation. De Bruyn et al. (2010) presented a bone loss of 0.1) À1.98 (2. Van de Velde et al. A further cause for the increased bone loss might have been entrapment of cement in the periimplant sulcus.4 to 1.78 (2. 2012). we cannot support/reject this hypothesis.2) (2.87 (2. 2008. a clinical study in man.. G.85 (0. C.. doi:10. Raes.44) 27 0. Arnaboldi. 613). Meirelles..30 (0.. R.007 p = 0.16) 27 p = 0..14 (0. (2006) Soft and hard tissue response to zirconium dioxide implants . The investigation has been © 2013 John Wiley & Sons A/S . We were not able to relate the increased bone loss to a single (evaluated) variable.000 Aboushelib. G. International Journal of Oral and Maxillofacial Implants 25. (p. Kern. P.432 p = 0. G.. Wiltfang. A. J. A clinical report. M. 111–120. M. Tzohar. when used for the treatment with a three-unit implant supported FDP.. T.1563/AAID-JOI-D11-00075. L.669 p = 0.584 0..51 (0.15 (0.33) 27 p = 0.51 (0. Cannizzaro..014 Wilcoxon signed ranks test (two-tailed.059 0. Minerva Stomatologica 59.73) 27 2. & Kohal. Altman. the success rate was significantly lower than the survival rate. J. Rocci. M. 1717–1722.97 (0. Dolci.001 1. Therefore. (2010) Edentulous jaws rehabilitation with yttrium-stabilized zirconium dioxide implants: two years follow-up experience....65 (0.09 (0.2% after 1 year has This clinical investigation has been conducted in accordance with the ethical principles of the World Medical Association Declaration of Helsinki and according to the laws of Germany.39 (0. G. 229–241. Journal of Periodontology 77. M. (2011) Use of endosseous one-piece yttrium-stabilized zirconia dental implants in premolar region: a two-year clinical preliminary re-port. G. V..62) 27 p = 0. 1222– 1232.023 p = 0. W.. G..002 3.001 p = 0.46 (0. P.. Wenz. D... Chaushu. Peri-implant soft tissue evaluation Implants Probing depth Prosthesis insertion Mean (SD) n 1-year follow-up Mean (SD) n Significance testa Clinical attachment level Prosthesis insertion Mean (SD) n 1-year follow-up Mean (SD) n Significance testa Bleeding Prosthesis insertion Mean (SD) n 1-year follow-up Mean (SD) n Significance testb Plaque Prosthesis insertion Mean (SD) n 1-year follow-up Mean (SD) n Significance testb a b Ref.284 3. the implants showed a high frequency of increased bone loss ( ! 2 mm) during the first year after implant placement.05). A. P. independently reviewed and approved by the Ethics Committee of the University Medical Center Freiburg. C. Future investigations applying implants made of high performance ceramics should include a control group and aim to specifically evaluate the different influencing parameters discussed elsewhere in the article.. Tarrida. Chaushu.. H.05). Cappare. P. Conclusions to be regarded as satisfactory and as comparable to other implant investigations. Garriga. European Journal of Oral Implantology 3. A. Wikesjo hash. (2010) Immediate occlusal versus non-occlusal loading of single zirconia implants. D.24 (0. E. R. A. L.04 (1. Felice. The implant survival rate of 98. C. Cooper..523 0. Salem. a = 0. Borgonovo. J. A multicentre pragmatic randomised clinical trial. & Dayan.55) 27 0.. M. Andreiotelli. Bianchi. Blaschke.74) 27 p = 0. 32–47. & Maiorana.35 (0. Censi. M. N. teeth Mann–Whitney 2. M.36) 27 p = 0. Crespi. Germany investigation number: 337/04. F. International Table 4.484 p = 0. 267–272. Borgonovo. Journal of Oral Implantology. L... A. € Ostman. Minerva Stomatologica 60. Abotaleb. M. cementation of restoration) might provide information on whether the observed problems were related to the implant design or to the performed procedures.52) 27 0. & Volz. (1999) Practical Statistics for medical research.560 Kohal et al..49) 27 0. 69–72. 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Principal findings: The survival rate of the zirconia implant system in the present investigation was acceptable after 1 year and comparable to survival rates of titanium oral implants. reduce plaque accumulation and they would be the only implant treatment for patients opposing metal devices in their bodies. Practical implications: Our investigation showed that the evaluated zirconia implant seems to perform inferior to titanium implants after one year when applied for fixed partial denture reconstructions and cannot be recommended for clinical routine due to the increased frequency of bone loss of more than 2 mm. Ceramic implants might improve esthetics. generally fabricated of yttria-stabilized zirconia tetragonal polycrystal. The success rate of the zirconia implants after one year was 60% on patient level when bone loss 2 mm was regarded as the acceptance limit and 72% on patient level when bone loss 3 mm was regarded as the acceptance limit. However. the mean bone loss of 1. the limits of such an implant system can be evaluated. Through conducting clinical inves- tigations. the frequency of bone loss ! 2 mm was higher compared to two-piece titanium implants. Furthermore. the safety and efficacy should have been evaluated in clinical investigations before market introduction.95 mm after one year exceeds the bone loss of two-piece titanium implants. © 2013 John Wiley & Sons A/S . Clinical Relevance Scientific rationale for the study: Ceramic implants. However.562 Kohal et al. are of certain interest in oral implantology since several companies have launched their systems on the market.