Group 3 ITI Consensus Report: Materials and antiresorptive drug-associated outcomes in implant dentistry.

OBJECTIVES: The aim of Working Group 3 was to address the influence of both material- and anti-resorptive drug- related factors on clinical and biological outcomes and complications in implant dentistry. Focused questions were addressed on (a) implant materials other than titanium (alloy)s, (b) transmucosal abutment materials and (c) medications affecting bone metabolism were addressed. MATERIALS AND METHODS: Three systematic reviews formed the basis for discussion in Group 3. Consensus statements and clinical recommendations were formulated by group consensus based on the findings of the systematic reviews. Patient perspectives and recommendations for future research were also conveyed. These were then presented and accepted following further discussion and modifications as required by the plenary. RESULTS: Zirconia is a valid alternative to titanium as material for implant and transmucosal components, allowing soft and hard tissue integration with clinical outcomes-identified by implant survival, marginal bone loss and peri-implant probing depths-up to 5-years comparable to titatnium. However, most of the evidence for zirconia implants is based on 1-piece implants limiting the indication range. Furthermore, based on expert opinion, zirconia transmucosal components might be preferred in the esthetic zone. In patients receiving low-dose bisphosphonate therapy, the rate of early implant failure is not increased, while the long-term effects remain poorly studied. Although it has not been sufficiently addressed, similar outcomes can be expected with low-dose denosumab. A drug holiday is not recommended when considering implant placement in patients treated with low-dose ARD. However, the specific therapeutic window, the cumulative dose and the administration time should be considered. Access to peri-implant supportive care is mandatory to prevent peri-implantitis-related medication-related osteonecrosis of the jaw (MRONJ) or implant-related sequestra (IRS). In patients receiving low-dose anti-resorptive drugs (ARD) therapy, the risk of complications related to implant placement is high, and implant procedures in this specific population should be strictly treated in a comprehensive multidisciplinary center. Finally, healthy dental implants should not be removed before low or high-dose ARD. CONCLUSIONS: Zirconia implants can be an alternative to titanium implants in selected indications. However, the current state of evidence remains limited, especially for 2-piece implant designs. Administration of low-dose ARD did not show any negative impact on early implant outcomes, but careful follow-up and supportive care is recommended in order to prevent peri-implant MRONJ and IRS. Implant placement in high-dose patients must be strictly considered in a comprehensive multidisciplinary center.

Crestal bone response to loaded zirconia and titanium implants: a radiographic and histometric analysis in canines.

OBJECTIVES: To evaluate the crestal bone response to a two-piece zirconia implant compared with a control titanium implant using periapical radiographs (PAs) and histometry. MATERIALS AND METHODS: Thirty zirconia and 30 titanium implants were placed in healed posterior mandibles of five canines. Full-ceramic single-tooth restorations were cemented after 6 weeks of healing. Three observers measured the distance between the implant shoulder and the crestal bone (DIB) at placement, loading, and harvesting after 4 or 16 weeks in function. The influence of implant material and loading time on DIB as well as the inter-observer agreement were analyzed. Additionally, histometric distance between implant shoulder and most coronal bone-to-implant contact (IS-cBIC) was compared with DIB. RESULTS: Mean DIB values increased between 4 and 16 weeks of loading for both zirconia (from 1.66 to 2.25 mm; P < 0.0001) and titanium (from 1.81 to 1.95 mm; P = 0.06). Zirconia yielded mean IS-cBIC values of 2.18 mm and 2.48 mm (P < 0.001) and titanium 2.23 mm and 2.34 mm (P = 0.27) after 4 and 16 weeks, respectively. The raters reached an excellent intraclass correlation coefficient. PAs underestimated the bone loss on average by 0.39 mm. CONCLUSIONS: Zirconia implants showed a greater increase of DIB during early healing and function than titanium. CLINICAL RELEVANCE: Crestal peri-implant tissue dimensions may show more pronounced changes around two-piece zirconia implants during early healing. PAs may underestimate peri-implant bone loss.

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.

Bone response to functionally loaded, two-piece zirconia implants: A preclinical histometric study.

OBJECTIVE: To evaluate the bone response to a two-piece zirconia implant in comparison with a control titanium implant in the canine mandible 4 and 16 weeks after restoration. MATERIAL AND METHODS: Zirconia and titanium implants were alternately placed bilaterally in healed mandibular molar and premolar sites of five canines. Full-ceramic single-tooth restorations were cemented after 6 weeks of transmucosal healing, allowing for full functional loading of the implants. Histologic and histometric analyses were performed on orofacial and mesiodistal undecalcified sections of the specimens obtained upon sacrifice after 4 and 16 weeks of functional loading. Bone-to-implant contact (BIC), multinucleated giant cells-to-implant contact (MIC), crestal bone level, and peri-implant bone density were histometrically assessed. RESULTS: All 60 implants and 60 restorations were still in function after 4 and 16 weeks of loading in both test and control groups. No implant loss, no implant or abutment fracture, and no chipping of the restorations could be detected. Histometric analysis showed no statistically significant differences between zirconia and titanium implants in BIC, crestal bone level, and peri-implant bone density at both time points. Between 4 and 16 weeks, the crestal bone level around zirconia implants showed a small but statistically significant increase in its distance from the implant shoulder. MIC was very low on both implant types and both time points and decreased statistically significantly overtime. CONCLUSION: The present two-piece zirconia implant showed a similar bone integration compared to the titanium implant with similar surface morphology after 4 and 16 weeks of loading.

Group 2 ITI Consensus Report: Prosthodontics and implant dentistry.

OBJECTIVES: Working Group 2 was convened to address topics relevant to prosthodontics and dental implants. Systematic reviews were developed according to focused questions addressing (a) the number of implants required to support fixed full-arch restorations, (b) the influence of intentionally tilted implants compared to axial positioned implants when supporting fixed dental prostheses (FDPs), (c) implant placement and loading protocols, (d) zirconia dental implants, (e) zirconia and metal ceramic implant supported single crowns and (f) zirconia and metal ceramic implant supported FDPs. MATERIALS AND METHODS: Group 2 considered and discussed information gathered in six systematic reviews. Group participants discussed statements developed by the authors and developed consensus. The group developed and found consensus for clinical recommendations based on both the statements and the experience of the group. The consensus statements and clinical recommendations were presented to the plenary (gathering of all conference attendees) and discussed. Final versions were developed after consensus was reached. RESULTS: A total of 27 consensus statements were developed from the systematic reviews. Additionally, the group developed 24 clinical recommendations based on the combined expertise of the participants and the developed consensus statements. CONCLUSIONS: The literature supports the use of various implant numbers to support full-arch fixed prostheses. The use of intentionally tilted dental implants is indicated when appropriate conditions exist. Implant placement and loading protocols should be considered together when planning and treating patients. One-piece zirconia dental implants can be recommended when appropriate clinical conditions exist although two-piece zirconia implants should be used with caution as a result of insufficient data. Clinical performance of zirconia and metal ceramic single implant supported crowns is similar and each demonstrates significant, though different, complications. Zirconia ceramic FDPs are less reliable than metal ceramic. Implant supported monolithic zirconia prostheses may be a future option with more supporting evidence.

A prospective clinical study to evaluate the performance of zirconium dioxide dental implants in single-tooth edentulous area: 3-year follow-up.

BACKGROUND: Traditionally, dental implants have been made from titanium or titanium alloys. Alternatively, zirconia-based ceramic implants have been developed with similar characteristics of functional strength and osseointegration. Ceramic implants offer advantages in certain settings, e.g. in patients who object to metal dental implants. The aim of this study was to investigate the mid-term (36 months) clinical performance of a ceramic monotype implant in single-tooth edentulous area. METHODS: This was a prospective, open-label, single-arm study in patients requiring implant rehabilitation in single-tooth edentulous area. Ceramic implants (PURE Ceramic Implant, Institut Straumann AG, Basel, Switzerland) with a diameter of 4.1 mm were placed following standard procedure and loaded with provisional and final prostheses after 3 and 6 months, respectively. Implant survival rate and implant success rate were evaluated and crestal bone levels were measured by analysing standardized radiographs during implant surgery and at 6, 12, 24 and 36 months. RESULTS: Forty-four patients received a study implant, of whom one patient withdrew consent after 3 months. With one implant lost during the first 6 months after surgery, the implant survival rate was 97.7% at 6 months. No further implants were lost over the following 30 months, and 3 patients were lost to follow-up during this time frame. This led to a survival rate of 97.5% at 36 months. Six months after implant surgery 93.0% of the implants were considered "successful", increasing to 97.6% at 12 months and remaining at this level at 24 months (95.1%) and 36 months (97.5%). Bone loss was most pronounced in the first half-year after implant surgery (0.88 ± 0.86 mm). By contrast, between 12 and 36 months the mean bone level remained stable (minimal gain of 0.06 [± 0.60] mm). Hence, the overall bone loss from implant surgery to 36 months was 0.97 (± 0.88) mm. CONCLUSIONS: In the follow-up period ceramic implants can achieve favourable clinical outcomes on a par with titanium implants. For instance, these implants can be recommended for patients who object to metal dental implants. However, longer term studies with different edentulous morphology need to confirm the present data. TRIAL REGISTRATION: Registered on www.clinicaltrials.gov : NCT02163395 .

A prospective clinical study to evaluate the performance of zirconium dioxide dental implants in single-tooth gaps.

INTRODUCTION: Dental implants have traditionally been made from titanium or its alloys, but recently full-ceramic implants have been developed with comparable osseointegration properties and functional strength properties to titanium. These ceramic implants may have advantages in certain patients and situations, for example, where esthetic outcomes are particularly important. OBJECTIVE: The objective of this investigation was to evaluate the performance of a newly developed full-ceramic ZrO2 monotype implant design (PURE Ceramic Implant; Institut Straumann AG, Basel, Switzerland) in single-tooth gaps in the maxilla and mandible. MATERIAL AND METHODS: This was a prospective, open-label, single-arm study in patients requiring implant rehabilitation in single-tooth gaps. Full-ceramic implants were placed, with provisional and final prostheses inserted after 3 and 6 months, respectively. Crestal bone level was measured at implant placement and after 6 and 12 months. Implant survival and success were evaluated after 6 and 12 months. Further evaluations are planned after 24 and 36 months. RESULTS: Forty-six patients were screened for potential study participation, of whom 44 (17 men and 27 women, mean age 48 ± 14 years) were recruited into the study. The majority of implants (90.9%) were placed in the maxilla. The implant survival and implant success rate after 12 months were 97.6%. A minor change of the mean bone level occurred between implant loading (final prosthesis insertion after 6 months) and 12 months (-0.14 mm) after initial bone remodeling was observed between implant placement and loading (-0.88 mm). CONCLUSIONS: The results indicated that monotype ceramic implants can achieve clinical outcomes comparable to published outcomes of equivalent titanium implants.

Biomechanical evaluation of a microstructured zirconia implant by a removal torque comparison with a standard Ti-SLA implant.

OBJECTIVES: The purpose of this study was to evaluate the biomechanical bone tissue response to novel microstructured zirconia implants in comparison to sandblasted and acid-etched (SLA) titanium implants through the analysis of removal torque (RTQ) measurements. MATERIALS AND METHODS: Ti-SLA implants with a sandblasted, large-grit and acid-etched surface were compared with zirconia implants with an acid-etched surface. All implants had the same shape, a diameter of 4.1 mm and a length of 10 mm. A total of 136 implants were placed in the maxillae of 17 miniature pigs. Six animals were sacrificed after both 4 and 8 weeks and five animals were sacrificed after 12 weeks, thus providing a total of 102 implants for RTQ testing (34 implants were reserved for future histological analysis). The RTQ analysis was successfully performed, using a mixed model regression with P-values calculated using the nonparametric Brunner-Langer method, on 100 of the 102 implants, two were excluded from the analysis. RESULTS: The adjusted mean RTQ values for Ti-SLA implants were 131 Ncm (95% CI: 107-155) at 4 weeks, 128 Ncm (108-148) Ncm at 8 weeks, and 180 Ncm (153-207 Ncm) at 12 weeks of healing, whereas RTQ values for the zirconia implants were 110 Ncm (86-134), 97 Ncm (76-118) and 147 Ncm (121-174) at the corresponding time intervals. A comparison of the implant materials resulted in P-values of P = 0.114 at 4 weeks, P = 0.034 at 8 weeks and P = 0.105 at 12 weeks (significance set at P < 0.05). CONCLUSIONS: Within the limits of the present study, it could be confirmed that the biomechanical bone-tissue response of the investigated zirconia implants is non-inferior to that of the well-documented, roughened titanium surface, at each time point, within the set tolerance. There were no statistically significant differences between the two materials after a healing period of 4 and 12 weeks. The RTQ values of both implant types increased significantly from the 8-week to the 12-week time point.

Submerged and transmucosal healing yield the same clinical outcomes with two-piece implants in the anterior maxilla and mandible: interim 1-year results of a randomized, controlled clinical trial.

OBJECTIVES: To test whether or not transmucosal healing at two-piece implants is as successful as submerged placement regarding crestal bone levels and patient satisfaction. MATERIAL AND METHODS: Adults requiring implants in the anterior maxilla or mandible in regions 21-25, 11-15, 31-35 or 41-45 (WHO) were recruited for this randomized, controlled multi-center clinical trial of a 5-year duration. Randomization was performed at implantation allowing for either submerged or transmucosal healing. Final reconstructions were seated 6 months after implantation. Radiographic interproximal crestal bone levels and peri-implant soft tissue parameters were measured at implant placement (IP) (baseline), 6 and 12 months. Patient satisfaction was assessed by a questionnaire. A two-sided t-test (80% power, significance level α=0.05) was performed on bone-level changes at 6 and 12 months. RESULTS: One hundred and twenty-seven subjects were included in the 12-month analysis (submerged [S]: 52.5%, transmucosal [TM]: 47.2%). From IP to 6 months, the change in the crestal bone level was -0.32 mm (P<0.001) for the S group and -0.29 mm (P<0.001) for the TM group. From IP to 12 months, bone-level changes were statistically significant in both groups (S -0.47 mm, P<0.001; TM -0.48 mm, P<0.001). The mean differences of change in the bone levels between the two groups were not statistically significant at either time point, indicating the equivalence of both procedures. For both groups, very good results were obtained for soft tissue parameters and for patient satisfaction. CONCLUSIONS: Transmucosal healing of two-piece implants is as successful as the submerged healing mode with respect to tissue integration and patient satisfaction within the first 12 months after IP.

Prospective Clinical Multicenter Study Evaluating the 5-Year Performance of Zirconia Implants in Single-Tooth Gaps.

PURPOSE: In recent years, ceramic implants made of zirconia have secured a niche position next to established titanium implants, due partly to new scientific findings and positive clinical experience with the handling of ceramic implants. The aim of this study was to assess the clinical and radiographic data for monotype ceramic implants that have remained in place for 60 months under masticatory loading. MATERIALS AND METHODS: In 2011, this prospective clinical study included patients with a single-tooth gap in the maxilla and mandible. Monotype ceramic implants (Straumann) were used according to a standard protocol. Provisional prostheses were placed after 3 months, followed by final prostheses 3 months later. Patients were invited for a 60-month follow-up. Implant survival was analyzed from lifetime data. Success rates and crestal bone levels were evaluated from implant placement to 6, 12, 36, and 60 months after surgery. RESULTS: From the initial 44 patients recruited, 36 were analyzable for the 60-month follow-up. With one implant lost before the 6-month followup, the survival rate after 60 months was 97.7%, and the mean survival time was 58.7 months. Sixty months after implant placement, the success rate was 97.2% (95% confidence interval = 84.6% to > 99.9%). Mean bone loss after 60 months was 0.99 (± 0.59) mm. CONCLUSION: After 60 months, monotype ceramic implants made of zirconia achieved success and survival rates comparable with those reported for titanium implants in selected patient populations. Ceramic implants can be used as an alternative to titanium implants at the request of patients and if specifically indicated, for example, due to titanium intolerance.

Titanium and zirconium release from titanium- and zirconia implants in mini pig maxillae and their toxicity in vitro.

OBJECTIVE: Titanium (Ti)- and Zirconia (ZrO2)-implants in mini pig maxillae were compared with respect to Ti/zirconium (Zr) release into the surrounding bone tissues, the resulting short term tissue responses and the potential toxicity. METHODS: Ti/Zr release from Ti- and ZrO2-implants in mini pig maxillae was determined with inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). The spatial distribution of Ti and Zr in maxilla tissues near the implant surface was assessed with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). A histological analysis was performed to investigate the tissue responses after 12 weeks of implantation. The cytotoxicity and DNA damage of Ti particles and ZrO2 particles were studied with XTT and Comet assay. RESULTS: The mean Ti content in the bone adjacent to Ti-implants was 1.67 mg/kg-bone weight. The highest Ti content detected was 2.17 mg/kg-bone weight. The mean Zr content in the bone adjected to ZrO2-implants was 0.59 mg/kg-bone weight. The highest Zr content was 0.75 mg/kg-bone weight. The spatial distribution of the Ti and Zr in bone showed mainly a higher intensity of Ti and Zr close to the screw thread outer tip rather. Histological analysis indicated that near both implant-types signs of bone marrow fibrosis were present. EC50 of commercially available ZrO2-nanoparticles (NPs, <100 nm) and ZrO2-microparticles (MPs, <5 µm) was 13.96 mg/ml and 80.99 mg/ml, respectively. ZrO2-NPs and ZrO2-MPs can induce DNA damage at 70 µg/ml and 810 µg/ml, respectively. SIGNIFICANCE: After 12-weeks of implantation, increased concentrations of Ti and Zr can be detected in bone/tissues near Ti- and ZrO2-implants in mini pig maxillae. Ti content released from Ti-implants is two times higher than the Zr content released from ZrO2-implants. ZrO2-NPs showed lower cytotoxicity and DNA damage compared to results reported for Ti-NPs in human cells.

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.

Translational research on clinically failed zirconia implants.

OBJECTIVES: To provide fractographic analysis of clinically fractured zirconia implants recovered with their cemented crown. To calculate bending moments, corresponding stress and crack onset location on the implant's fracture surface using a mathematical model integrating spatial coordinates of the crown-implant part and occlusal loading obtained from 2D and 3D images. METHODS: 15 fractured zirconia implants parts (11 posterior and 4 anterior) with their all- ceramic crowns still cemented on it were recovered. The implants were first generations from four manufacturers (AXIS Biodental, Z-Systems, Straumann, Swiss Dental Solutions). The time-to-failure varied between 2weeks and 9years. Fractography was performed identifying the failure origin and characteristic surface crack features. From 2D and 3D digital images of the crown-implant part, spatial coordinates anchoring the crown's occlusal contacts with the implant's central axis and reference plane were integrated in a mathematical model spreadsheet. Loads of 500 N in total were selectively distributed over identified occlusal contacts from wear patterns. The resultant bending and torsion moments, corresponding shear, tensile, maximum principal stress and von Mises stress were calculated. The fracture crack onset location on the implant's fracture surface was given by an angular position with respect to an occlusal reference and compared with the location of the fracture origin identified from fractographic analysis. RESULTS: Implants fractured from the periphery of the smaller inner diameter between two threads at the bone-entrance level except for one implant which failed half-way within the bone. The porous coating (AXIS Biodental) and the large grit alumina sandblasting (Z-System) created surface defects directly related to the fracture origin. The model spreadsheet showed how occlusal loading with respect to the implant's central axis affects bending moments and crack onset. Dominant loads distributed on contacts with important wear pattern provided a calculated crack onset location in good agreement with the fractographic findings of the fracture origin. SIGNIFICANCE: Recovered broken zirconia implant parts with their restorative crowns can provide not only information regarding the failure origin using fractography but also knowledge regarding occlusal crown loading with respect to the implant's axis. The mathematical model was helpful in showing how occlusal loading affects the location of the fracture initiation site on clinical zirconia implant fracture cases.

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.

Evaluation of Hard and Soft Tissue Dimensions Around Zirconium Oxide Implant-Supported Crowns: A 1-Year Retrospective Study.

BACKGROUND: This study aims to evaluate the effect of the distance between the alveolar crest of a full-ceramic implant to the lowest point of the contact area of the crowns on the interdental papilla. Therefore, the authors proposed a new concept of linear measurements for the reproducible and metric evaluation of distances relevant for the assessment of hard and soft tissue changes around dental implants. METHODS: A total of 216 sites were examined in 87 patients. In a radiographic and clinical evaluation, four relevant distances were evaluated. In the x-ray image, the tip of the papilla was marked with a radiodense mixture of tungsten powder and temporary cement. In a clinical photograph, the lowest point of the interdental contact zone of the crowns was visualized by a metallic interdental ligature. RESULTS: Using the proposed measuring methodology, four different papilla-deficit situations around ceramic implants could be reproducibly distinguished. When the measurement from the bone crest at the implant was ≤5 mm, the papilla was completely present in 100% of cases. When this distance was 10 mm, the papilla was still present in 67% of the cases, without any cosmetically apparent deficit. CONCLUSIONS: A close relationship is observed between the distance from the contact point to the bone and the presence of the papilla. Using a combination of radiographically and clinically visible landmarks allows the reproducible measurement of these distances.

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.

Implant Supported Fixed Dental Prostheses Using a New Monotype Zirconia Implant-A Case Report.

Currently, titanium or specific titanium alloys are the most often used materials for the fabrication of dental implants. Many studies have confirmed the osseointegrative capacity and clinical long-term performance of moderately rough titanium implants. However, disadvantages have also been reported with regard to peri-implant infections and the titanium metal properties. Tooth colored ceramic implants have attracted the interest of clinicians since the end of the 1960s. Initially, alumina was used for the fabrication of ceramic implants; however, due to the poor biomechanical properties, alumina implants are not commercially available any more. Since end of the 1990s, zirconia has been established in dentistry due to its superior biomechanical properties compared to other oxide ceramics such as alumina. Currently, zirconia is the material of choice for the fabrication of ceramic implants. Zirconia implants show superior biocompatibility compared to titanium and other metals. Additionally, it has been reported that zirconia implants with a micro-rough surface topography show at least a comparable osseointegrative capacity and similar clinical survival rates to moderately rough titanium implants. The present case reports a fixed implant-supported reconstruction of a large edentulous space with compromised local bone conditions using new monotype zirconia dental implants with a micro-rough surface topography.

Clinical and radiologic outcomes after submerged and transmucosal implant placement with two-piece implants in the anterior maxilla and mandible: 3-year results of a randomized controlled clinical trial.

PURPOSE: The aim of this investigation was to evaluate the 3-year outcomes regarding crestal bone level, clinical parameters, and patient satisfaction, following submerged and transmucosal implant placement for two-piece implants in the anterior maxilla and mandible. MATERIALS AND METHODS: Patients requiring dental implants for single-tooth replacement in the anterior maxilla or mandible were enrolled in a randomized, controlled, multicenter clinical trial. The implants were randomized at placement to either submerged or transmucosal healing, with final restorations placed after 6 months. Radiographic and clinical parameters were recorded after 1, 2, and 3 years; a questionnaire was also used to assess patient satisfaction. A two-sided, unpaired T-test (significance level p ≤ .05) was used to statistically evaluate the differences between the two groups. RESULTS: A total of 106 patients were included in the 3-year analysis. The mean change in crestal bone level from implant placement to 3 years was 0.68 ± 0.98 mm (p < .001) and 0.58 ± 0.77 mm (p < .001) in the submerged and transmucosal groups, respectively; the differences between the groups were not significant. Clinical parameters remained stable throughout the study, with no significant differences between the groups, and patient satisfaction was good or excellent for over 90% of subjects in both groups. CONCLUSIONS: The results demonstrate excellent clinical and radiographic conditions after 3 years for implants supporting single-tooth restorations, regardless of whether a submerged or transmucosal surgical technique was used.

Dental zirconia implants up to three years in function: a retrospective clinical study and evaluation of prosthetic restorations and failures.

PURPOSE: The clinical evaluation of one-piece zirconia dental implants with different diameters to determine survival rate and type of implant failure. MATERIALS AND METHODS: Information concerning implant surgery (number, diameter, length, and position of inserted implants; patient age, sex, risk factors, and bone quality) was extracted from the clinical records. All treated patients were then recalled for a follow-up examination to check the current clinical parameters concerning soft tissue, implants, and prosthetic reconstructions. RESULTS: A total of 79 patients received 170 implants (diameter-reduced 3.25 mm: n = 59; diameter 4.0 mm: n = 82; diameter 5.0 mm: n = 29). The clinical examination showed no signs of gingival inflammation. Prosthetic information was available for 119 implants restored with single crowns (87 implants), fixed partial dentures (25 implants), and removable hybrid dentures (7 implants). Overall, 30 implants were lost due to lack of osseointegration (n = 17) or fracture (n = 13). The diameter-reduced implants showed the lowest survival rate (59.5%) compared to the implants with a diameter of 4.0 mm (90.6%) and 5.0 mm (73.9%). The survival rate for diameters of 3.25 mm was significantly lower than that for diameters of 4.0 mm. The estimated cumulative survival rate up to 3 years demonstrated a survival probability of 82.4% for all types of implant diameters and failure. CONCLUSIONS: Based on these results, diameter-reduced zirconia dental implants cannot be recommended for clinical use. The overall survival rate of 82.4% is not acceptable in comparison to the well-established survival rate of titanium implants.