Evaluation of one-piece zirconia dental implants: An 8-year follow-up study.

OBJECTIVES: Long-term studies of modern zirconia implants are still insufficient. This prospective 8-year follow-up study investigated one-piece zirconia implants. MATERIALS AND METHODS: Patients who had received a one-piece zirconia dental implant (PURE ceramic implant, Institut Straumann GmbH, Basel, Switzerland) were included in this study. Next to the implant survival and success rates, the radiographic and clinical implant parameters were assessed. RESULTS: The overall survival rate of 67 zirconia implants in 39 patients was 100%. The overall success rate was 89.6%. Around the immediate zirconia implants, the success rate was 94.7%, and around the delayed implants, 87.5%. The immediate implants showed a significantly higher bone crest compared to the delayed implants (p = 0.0120). According to the pink esthetic score, the immediate implants revealed more favorable esthetic results compared to the delayed implants after an 8-year follow-up (p = 0.0002). CONCLUSIONS: After 8 years, the one-piece zirconia implants presented an 89.6% success rate. Regarding the timing of implantation, in individual cases, immediate implantation can have slight advantages over delayed implantation. CLINICAL RELEVANCE: Immediate implants can also be considered for zirconia implants and should not be excluded on principle.

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.

Papilla-Crown Height Dimensions around Zirconium Dioxide Implants in the Esthetic Area: A 3-Year Follow-Up Study.

PURPOSE: Soft tissue interactions with ceramic dental implants have previously been shown to have favorable esthetic outcomes. This study aimed to evaluate the papilla-crown proportion around zirconia implants in a 3-year follow-up study and the correlation between the gingival biotype and changes in papillary height. MATERIALS AND METHODS: This was a prospective study of 39 patients with 40 single-gap implants (Straumann PURE Ceramic ZLA Implant). The papilla-crown proportion was assessed after 3 months, 1 year, and 3 years. In addition, correlations between the peri-implant biotypes and changes in papillary heights were evaluated. RESULTS: The papilla-crown proportion improved from 35.5% after 3 months to 41.7% after 3 years. The gingival biotype was correlated very weakly to papilla height alterations. Significant papillary fill was observed in the interdental space between 3 months and 3 years (p < 0.001). CONCLUSIONS: An ideal papilla-crown proportion of 40% around single implants was observed after 3 years. A thin or thick gingival biotype showed a very weak correlation with soft tissue alterations.

Esthetic Evaluation of Maxillary Single-Tooth Zirconia Implants in the Esthetic Zone.

The purpose of this study was to evaluate ceramic dental implants using different esthetic scores. A total of 53 ceramic dental implants were evaluated using the Pink Esthetic Score (PES), White Esthetic Score (WES), and Peri-Implant and Crown Index (PICI). Prosthodontists, orthodontists, oral surgeons, and dentistry students independently performed assessments. The mean value of combined PES + WES was 17.4 points, and the PICI was 523.2 points. Orthodontists assessed a significantly lower result in both indices compared to all other assessor groups (P ≤ .05). Patient satisfaction was very high. The esthetic scores around ceramic implants were considerably higher than the suggested threshold of clinical acceptability.

Experimental peri-implant mucositis around titanium and zirconia implants in comparison to a natural tooth: part 1-host-derived immunological parameters.

The purpose of this study was to assess host-derived parameters around dental zirconia and titanium implants and natural teeth during the occurrence of mucositis. After 4 weeks of perfect oral hygiene, 16 clinically profiled patients were asked to refrain from oral hygiene for 2 weeks, resulting in experimental plaque accumulation. This was followed by 4 weeks of perfect oral hygiene to reverse the inflammation. Immunological samples were analyzed for interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-α), and interleukin 1ß (IL-1ß). Immunological parameters were measured each week, starting at week 4 (session 2) and ending at week 10 (session 8). There were significant differences in IL-6 between the groups (zirconia vs. tooth and titanium vs. tooth), with unfavourable values for the tooth unit (P<0.05). After reinstitution of oral hygiene, there was a significant increase in TNF-α values for the tooth but not for the zirconia and titanium implants. There were significant differences in IL-1ß between the groups (zirconia vs. titanium and titanium vs. tooth), with higher IL-1ß levels around titanium implants (P<0.05). The soft tissue around titanium implants developed a stronger inflammatory response to experimental plaque accumulation in terms of IL-1ß values, whereas the teeth presented an increase in IL-6 and TNF-α values.

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 .

Peri-implant Crestal Bone Changes Around Zirconia Implants in Periodontally Healthy and Compromised Patients.

PURPOSE: No consensus regarding the efficacy of zirconia implants in maintaining peri-implant hard and soft tissue health has yet been obtained. The aim of this retrospective follow-up study was to gain knowledge about peri-implant bone behavior and about implant survival and success after treatment with zirconia dental implants in patients with normal and compromised soft and hard tissue conditions. MATERIALS AND METHODS: This follow-up study involved 86 patients with 123 zirconia implants (Straumann PURE Ceramic Implant) that were radiographically investigated directly after implant placement (day 0), 3 months after placement, and 1 year after the definitive implant crown placement. The clinical assessment was done at the 1-year postloading appointment and also included the modified Plaque Index, modified Sulcus Bleeding Index, and sulcus pocket depths. Eighteen patients with periodontally compromised conditions were compared to 68 patients with healthy periodontal conditions. RESULTS: The survival rate was 100% and success rate was 94.5%, with no differences between the two groups. The alveolar crest around the ceramic implants showed no significant difference between day 0 and 1 year postloading for both groups (P > .05). There was also no significant difference at 1 year postloading between the groups in the distance from the implant shoulder to the peri-implant bone crest (P = .67) or in pocket depth (P = .07). CONCLUSION: No significant peri-implant bone loss was observed in the first year. The survival and success rates showed no differences between the periodontally healthy and periodontally compromised groups; however, only a limited number of patients with periodontally compromised conditions were included in this study.

Influence of horizontal dimensions around single gap and adjacent zirconia implants on the papilla - a cross-sectional survey.

PURPOSE: To evaluate a possible association between the inter-implant distance and the papilla deficit. Additionally, the effect of high or low contact points of the crowns on the papilla deficit was investigated. MATERIALS AND METHODS: Periapical radiographs taken 1 year after loading were used to assess the distance from the shoulder of the implant to the adjacent tooth or implant. On the clinical images, the interdental papilla height, soft tissue deficit and crown length were evaluated. The papilla crown proportion and the proportion of the height of the contact point to the crown length were assessed. RESULTS: Eighty-one patients, with a total of 104 zirconia implants and 208 measurements were involved in this cross-sectional survey. Considering patient means, the correlation between the papilla deficit and the interproximal distance, respectively inter-implant distance, was very low (r = -0.05220; P = 0.6435, N = 81). Logistic regression at implant-level showed that there was no significant difference in the likelihood for a papilla deficit between a high and a low contact point of the crowns with P = 0.8191 (Odds ratio: 1.106 with 95%CI 0.461; 2.654). CONCLUSIONS: Horizontal interproximal dimensions around zirconia implants showed very weak influence on the papilla height. A high or a low contact point position of the crowns did not affect the papilla deficit. Conflict of Interest and sources of funding: All authors reported no conflict of interest. There were no sources of funding for the research.

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 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.

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.

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.

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.

A comparison study of the osseointegration of zirconia and titanium dental implants. A biomechanical evaluation in the maxilla of pigs.

OBJECTIVES: The purpose of the present study was to investigate the osseointegration of microstructured zirconia implants in comparison with sandblasted and acid-etched (SLA) titanium implants in a biomechanical study. MATERIALS: Zirconia implants (4.1 mm in diameter, 10 mm in length) were produced using a new low pressure injection molding technique. After that the implants were acid-etched with hydrofluoric acid. Standard Ti-SLA implants of the exact same shape served as controls. Six months after extraction of incisors 2 and 3, 16 adult pigs received a total of 64 implants in the maxillae. After 4, 8, and 12 weeks the animals were sacrificed, and 59 implants could be analyzed to removal torque (RTQ) testing. RESULTS: The mean RTQ values for zirconia implants were 42.4 Ncm at 4 weeks, 69.6 Ncm at 8 weeks, and 69.3 Ncm at 12 weeks of healing, whereas RTQ values for the Ti-SLA implants were 42.1 Ncm, 75.0 Ncm, and 73.1 Ncm at corresponding time intervals. There is no statistical difference in RTQ values between Ti-SLA and zirconia implants at 8 weeks. CONCLUSIONS: Within the limits of the present study it was concluded that acid-etching of zirconia implants enhances bone apposition resulting in RTQ values which were equivalent to that of Ti-SLA.