Zirconia compared to titanium dental implants in preclinical studies-A systematic review and meta-analysis.

OBJECTIVES: To evaluate whether zirconia implants demonstrate differences in hard and soft tissue integration compared to titanium implants in preclinical studies. MATERIAL AND METHODS: In March 2017, electronic (MEDLINE, EMBASE) and hand search was performed to identify preclinical studies comparing zirconia and titanium implants. Primary outcomes were bone-to-implant contact (BIC) and removal torque out (RTQ), respectively, push-in (PI) measurements. Secondary outcomes included biologic width (BW) dimensions. RESULTS: A total of 37 studies were included for data extraction after screening of 91 from 1,231 selected titles. Thirty-seven experimental studies using six different species were identified. The follow-up periods ranged between 0.4 and 56 weeks. For titanium, mean values of 59.1% (95% CI: 53.3 - 64.8), 102.6 Ncm (95% CI: 81.5 - 123.6), and 25.1 N (95% CI: 20.2 - 30.0) for BIC, RTQ, and PI were estimated, respectively. The mean values for zirconia were 55.9% (95% CI: 51.6 - 60.1), 71.5 Ncm (95% CI: 51.1 - 91.9), and 22.0 N (95% CI: 13.2 - 30.7) for corresponding parameters. Confounding factors such as animal species, implant material, loading protocol, and study or loading duration significantly influenced the outcomes. Similar qualitative soft tissue integration was reported for zirconia and titanium implants. However, faster maturation processes of epithelial and connective tissues around zirconia implants were assumed. Quantitatively, similar BW dimensions were evaluated for titanium (3.5 mm; 95% CI: 2.9 - 4.2) and zirconia (3.2 mm; 95% CI: 2.7 - 3.7), whereas the loading protocol significantly influenced the outcomes. CONCLUSIONS: Zirconia and titanium implants demonstrate a similar soft and hard tissue integration capacity. However, titanium tended to show a faster initial osseointegration process compared to zirconia. Importantly, not only material characteristics but predominantly animal species and study protocols can significantly influence the outcomes.

Performance and outcome of zirconia dental implants in clinical studies: A meta-analysis.

OBJECTIVES: To evaluate implant survival, peri-implant marginal bone loss, technical, and biological complications as well as aesthetic outcomes of zirconia implants in clinical studies. MATERIAL AND METHODS: Electronic (Medline, Embase) and hand searches were performed to identify clinical studies published between January 2004 and March 2017 investigating zirconia dental implants with a mean follow-up of at least 12 months. Primary outcomes were implant survival and peri-implant marginal bone loss. Secondary outcomes included technical and biological complications as well as aesthetic outcomes. Meta-analyses were performed to estimate implant survival and marginal bone loss. RESULTS: From 943 titles, 264 abstracts were selected. Subsequently, 80 full-text articles were screened, and 18 studies were included for data extraction. One- (14 studies) and 2-piece zirconia implants (4 studies) were investigated. Commercially available (CA) (510 implants, 398 patients) and not commercially available (NCA) zirconia implants (618 implants, 343 patients) were identified. For CA implants (follow-up: 12-61.20 months), technical complications (1.6%), implant fractures (0.2%) and biological complications (4.2%) were reported. Meta-analyses estimated 1- and 2-year survival rates of 98.3% (95% CI: 97.0%-99.6%) and 97.2% (95% CI: 94.7%-99.7%), respectively, and a mean 1-year marginal bone loss of 0.7 mm (95% CI: 0.4-1.0 mm). CONCLUSIONS: Since 2004, the survival rates of CA implants significantly improved compared with NCA implants. CA 1-piece zirconia implants showed similar 1- and 2-year mean survival rates and marginal bone loss after 1 year compared with published data for titanium implants. However, more clinical long-term data are needed to confirm the presently evaluated promising short-term outcomes.

Influence of clinical expertise and practical experience on transfer accuracy in guided dental implant placement - an in vitro study.

PURPOSE: To investigate whether inexperienced users applying a static navigation system can perform in-vitro a fully guided implant placement protocol and achieve similar results in terms of accuracy compared to experienced clinicians. METHODS: Based on 36 identical resin models, a computer-assisted implant planning was performed and a surgical guide was produced accordingly. Three study groups were composed with 12 operators, each: control group with experienced surgeons (DOC), test group 1 with dental technicians (TEC) and test group 2 with non-specialists (OFC). Using a fully guided drilling protocol, two implants were placed into each of the 36 models. Subsequently, the differences between the virtually planned and final implant positions were determined and the transfer accuracy was evaluated. RESULTS: For the control group DOC, the mean value of axial deviation was 1.90 ± 1.15 degrees, for 3-dimensional deviation at the implant base 0.52 ± 0.33 mm, for 3-dimensional deviation at the implant tip 0.76 ± 0.39 mm and for vertical deviation at the implant tip - 0.11 ± 0.51 mm. For corresponding parameters, the mean values of test group TEC were 1.99 ± 0.87 degrees, 0.42 ± 0.21 mm, 0.68 ± 0.30 mm and - 0.03 ± 0.33 mm and for test group OFC 2.29 ± 1.17 degrees, 0.63 ± 0.35 mm, 0.89 ± 0.43 mm and - 0.24 ± 0.57 mm, respectively. The results did not reveal any statistically significant differences between the control and the 2 test groups (p˃0.05). CONCLUSION: The results of the present in-vitro study demonstrated that inexperienced users applying a static navigation system can perform a fully guided implant placement protocol and achieve similar results in terms of accuracy compared to experienced clinicians in this specific in vitro setup.

Ligature-Induced Peri-implant Bone Loss Around Loaded Zirconia and Titanium Implants.

PURPOSE: To radiographically investigate ligature-induced peri-implant bone loss around loaded titanium (Ti-SLA) and zirconia (ZrO2-ZLA) implants using a canine model. MATERIALS AND METHODS: Forty sandblasted and acid-etched titanium and zirconia implants were alternately placed in the mandibles of five canines (20 Ti-SLA, 20 ZrO2-ZLA). Implants were restored after 6 weeks of unloaded healing. After 4 weeks of functional loading, oral hygiene procedures were stopped and experimental peri-implant bone loss was initiated by placing cotton ligatures. After 8 weeks of active progression, ligatures were removed and plaque was allowed to accumulate for another 16 weeks of spontaneous progression (without ligatures). Standardized radiographs were taken at implant placement, at functional loading, and every 2 weeks during active and spontaneous progression of bone loss. RESULTS: Before ligature placement, all implants were successfully osseointegrated and no clinical or radiographic signs of peri-implant infections were detectable. Two weeks after ligature removal, one titanium implant was lost; however, no zirconia implant failures were observed during the study. Radiographically, zirconia implants revealed statistically significantly less crestal peri-implant bone loss compared to titanium implants at the end of the active progression period (Ti-SLA: 3.92 mm; ZrO2-ZLA: 2.65 mm; P < .01); however, no significant differences occurred after the spontaneous progression period (P = .6). Combining the active and spontaneous progression periods together, zirconia implants demonstrated significantly reduced peri-implant bone loss compared to titanium implants (Ti-SLA: 3.76 mm; ZrO2-ZLA: 2.42 mm; P < .01). CONCLUSION: These results demonstrate a significantly reduced ligature-induced inflammation and bone loss for ZrO2-ZLA implants compared to Ti-SLA implants in the canine model.

In Vitro Biofilm Formation on Titanium and Zirconia Implant Surfaces.

BACKGROUND: It has been hypothesized that zirconia might have a reduced bacterial adhesion compared with titanium; however, results from experimental studies are rather controversial. The aim of the present study is to compare biofilm formation on zirconia and titanium implant surfaces using an in vitro three-species biofilm and human plaque samples. METHODS: Experimental disks made of titanium (Ti) or zirconia (ZrO2) with a machined (M) or a sandblasted (SLA) and acid-etched (ZLA) surface topography were produced. An in vitro three-species biofilm or human plaque samples were applied for bacterial adhesion to each type of disk, which after 72 hours of incubation was assessed using an anaerobic flow chamber model. RESULTS: Zirconia showed a statistically significant reduction in three-species biofilm thickness compared with titanium (ZrO2-M: 8.41 µm; ZrO2-ZLA: 17.47 µm; Ti-M: 13.12 µm; Ti-SLA: 21.97 µm); however, no differences were found regarding three-species-biofilm mass and metabolism. Human plaque analysis showed optical density values of 0.06 and 0.08 for ZrO2-M and ZrO2-ZLA, and values of 0.1 and 0.13 for Ti-M and Ti-SLA, respectively; indicating a statistically significant reduction in human biofilm mass on zirconia compared with titanium. Additionally, zirconia revealed a statistically significant reduction in human plaque thickness (ZrO2-M: 9.04 µm; ZrO2-ZLA: 13.83 µm; Ti-M: 13.42 µm; Ti-SLA: 21.3 µm) but a similar human plaque metabolism compared with titanium. CONCLUSION: Zirconia implant surfaces showed a statistically significant reduction in human plaque biofilm formation after 72 hours of incubation in an experimental anaerobic flow chamber model compared with titanium implant surfaces.

A Retrospective Clinical Study with Regard to Survival and Success Rates of Zirconia Implants up to and after 7 Years of Loading.

PURPOSE: The study aims to retrospectively investigate the clinical performance of first-generation zirconia implants with a sandblasted surface up to and after 7 years of loading. MATERIALS AND METHODS: Clinical records of patients treated with zirconia implants between 2004 and 2009 were screened. Consequently, adequate patients were invited to a clinical and radiographic investigation to classify each implant according to strict success criteria. RESULTS: Seventy-one patients receiving 161 implants were available for the evaluation. Overall, 36 implants (22.4%) were lost due to early (n = 14) and late failures (n = 4) or fractures (n = 18). All surviving 125 implants fulfilled the success criteria. None of the investigated implants had a history of peri-implant infections. Mean values with regard to gingival index, plaque index, modified sulcus bleeding index, and probing depth were 0.03, 0.23, 0.59, and 2.80 mm, respectively. The radiographically evaluated mean crestal bone loss was 0.97 ± 0.07 mm. Diameter-reduced implants (3.25 mm) showed lower survival (58.5%) compared with implants with a diameter of 4.0 mm (88.9%) and 5.0 mm (78.6%). The overall longitudinal survival rate was 77.3%. CONCLUSIONS: First-generation zirconia implants showed low overall survival and success rates. The evaluated clinical and radiographic parameters were consistent with healthy peri-implant tissues. Additionally, nonfractured failures were not associated with peri-implant infections.