Influence of loading and aging on the fracture strength of an injection-molded two-piece zirconia implant restored with a zirconia abutment.

OBJECTIVE: To investigate the fracture strength and potential phase transformation of an injection-molded two-piece zirconia implant restored with a zirconia abutment after loading and/or aging. METHODS: Thirty-two two-piece zirconia implants (4.0 mm diameter) restored with zirconia abutments were embedded according to ISO 14801 and divided into four groups (n = 8/group): Three groups were either exclusively hydrothermally treated (group HT; 85°C), dynamically loaded (group DL; 107 cycles; 98 N), or subjected to both treatments simultaneously (group DL/HT). One group remained untreated (group 0). A sample from each group was cross-sectioned and examined by scanning electron microscopy for possible crystal phase transformation. The remaining samples were then loaded to fracture in a static loading test. A one-way ANOVA was used for statistical analyses. RESULTS: During dynamic loading, three implants of group DL and six implants of group DL/HT fractured at a load of 98 N. The fracture strength of group DL/HT (108 ± 141 Ncm) was significantly reduced compared to the other groups (group 0: 342 ± 36 Ncm; HT: 363 ± 49 Ncm; DL: 264 ± 198 Ncm) (p < .05). Fractures from group 0 and HT occurred at both implant and abutment level, whereas implants from group DL and DL/HT fractured only at implant level. A shallow monoclinic transformation zone of approximately 2 µm was observed following hydrothermal treatment. CONCLUSIONS: Within the limitations of this study, it can be concluded that dynamic loading and the combination of loading and aging reduced the fracture strength of the implant abutment combination. Hydrothermal treatment caused a shallow transformation zone which had no influence on the fracture strength.

A systematic review and meta-analysis evaluating the survival, the failure, and the complication rates of veneered and monolithic all-ceramic implant-supported single crowns.

OBJECTIVE: To assess the survival, failure, and complication rates of veneered and monolithic all-ceramic implant-supported single crowns (SCs). METHODS: Literature search was conducted in Medline (PubMed), Embase, and Cochrane Central Register of Controlled Trials until September 2020 for randomized, prospective, and retrospective clinical trials with follow-up time of at least 1 year, evaluating the outcome of veneered and/or monolithic all-ceramic SCs supported by titanium dental implants. Survival and complication rates were analyzed using robust Poisson's regression models. RESULTS: Forty-nine RCTs and prospective studies reporting on 57 material cohorts were included. Meta-analysis of the included studies indicated an estimated 3-year survival rate of veneered-reinforced glass-ceramic implant-supported SCs of 97.6% (95% CI: 87.0%-99.6%). The estimated 3-year survival rates were 97.0% (95% CI: 94.0%-98.5%) for monolithic-reinforced glass-ceramic implant SCs, 96.9% (95% CI: 93.4%-98.6%) for veneered densely sintered alumina SCs, 96.3% (95% CI: 93.9%-97.7%) for veneered zirconia SCs, 96.1% (95% CI: 93.4%-97.8%) for monolithic zirconia SCs and only 36.3% (95% CI: 0.04%-87.7%) for resin-matrix-ceramic (RMC) SCs. With the exception of RMC SCs (p < 0.0001), the differences in survival rates between the materials did not reach statistical significance. Veneered SCs showed significantly (p = 0.017) higher annual ceramic chipping rates (1.65%) compared with monolithic SCs (0.39%). The location of the SCs, anterior vs. posterior, did not influence survival and chipping rates. CONCLUSIONS: With the exception of RMC SCs, veneered and monolithic implant-supported ceramic SCs showed favorable short-term survival and complication rates. Significantly higher rates for ceramic chipping, however, were reported for veneered compared with monolithic ceramic SCs.

Fracture resistance and crystal phase transformation of a one- and a two-piece zirconia implant with and without simultaneous loading and aging-An in vitro study.

OBJECTIVE: To evaluate the influence of artificial aging on the transformation propagation and fracture resistance of zirconia implants. METHODS: One-piece (with integrated implant abutment, 1P; regular diameter [4.1mm]; n = 16) and two-piece (with separate implant abutment, 2P; wide diameter [5 mm]; n = 16) zirconia implants were embedded according to ISO 14801. A two-piece titanium-zirconium implant (Ti-Zr; 4.1 mm diameter) served as a control (n = 16). One subgroup (n = 8) of each system was simultaneously dynamically loaded (107 cycles; 98N) and hydrothermally aged (85°C, 58 days), while the other subgroup (n = 8) remained untreated. Finally, specimens were statically loaded to fracture. Potential crystal phase transformation was examined at cross sections using scanning electron microscopy (SEM). A multivariate linear regression model was applied for statistical analyses. RESULTS: The fracture resistance of 1P (1,117 [SD = 38] N; loaded/aged: 1,009 [60] N), 2P (850 [36] N; loaded/aged: 799 [84] N), and Ti-Zr implants (1,338 [205] N; loaded/aged: 1,319 [247] N) was not affected significantly by loading/aging (p = .171). However, when comparing the systems, they revealed significant differences independent of loading/aging (p ≤ .001). Regarding the crystal structure, a transformation zone was observed in SEM images of 1P only after aging, while 2P showed a transformation zone even before aging. After hydrothermal treatment, an increase of this monoclinic layer was observed in both systems. CONCLUSIONS: The Ti-Zr control implant showed higher fracture resistance compared to both zirconia implants. Loading/aging had no significant impact on the fracture resistance of both zirconia implants. The wide-body 2P zirconia implant was weaker than the regular body 1P implant.

Rehabilitation of shortened dental arches: A fifteen-year randomised trial.

BACKGROUND: Few long-term studies on treatments in the shortened dental arch (SDA) are available. OBJECTIVE: The objective of this trial was to analyse the long-term success of two different treatment concepts. METHODS: Patients over 35 years of age with missing molars in one jaw and at least the canine and one premolar present on both sides were eligible. In the partial removable dental prosthesis (PRDP) group (N = 81), molars and missing second premolars were replaced by a precision attachment retained prosthesis. In the SDA group (N = 71), the dental arch ended with the second premolar that had to be present or replaced by a cantilever fixed dental prosthesis. Follow-up examinations were carried out over 15 years. RESULTS: A comprehensive outcome variable comprised four failure categories for which Kaplan-Meier survival (success) analyses were conducted. Half of the patients exhibited a continuous preservation of the per protocol prosthetic status that remained totally unaffected by complications for more than 10 years. The event-free success rates for moderate or worse failure implied a loss of the per protocol prosthetic status. The respective survival rates fell below 50% at 14.2 years in the PRDP group and 14.3 years in the SDA group. In none of the analyses, a significant group difference was found. CONCLUSIONS: In patients with an SDA condition, changes in the prosthetic status have to be expected. The affected proportion increases almost linearly from shortly after treatment and comprises the majority after 15 years. The influence of the examined treatments on success appears to be low.

Zirconia implants restored with single crowns or fixed dental prostheses: 5-year results of a prospective cohort investigation.

AIM: To evaluate the clinical and radiological outcomes of one-piece zirconia implants restored with single crowns (SCs) or fixed dental prostheses (FDPs) over an observation period of 5 years in function. MATERIALS AND METHODS: In a prospective cohort investigation with two investigational centers, one-piece zirconia implants were placed in anterior and posterior sites. After a healing period of at least 2 months in the mandible and 4 months in the maxilla with immediate provisional reconstructions, the final all-ceramic SCs or three-unit FDPs were cemented. Patients were followed for 5 years. Clinical parameters and radiological measurements of the implants and the neighboring teeth were assessed. For the statistical analysis, linear mixed models were applied. RESULTS: A total of 71 implants were placed in 60 patients. Sixty-three implants in 53 patients could be evaluated at the 5-year follow-up. Six patients with a total of seven implants were counted as dropouts. One implant did not achieve adequate osseointegration and had to be removed 5 weeks after implantation. The 5-year survival rate was calculated as 98.4% (95% CI 91.6, 99.9). The mean overall marginal bone loss from implant placement to the 5-year follow-up was 0.7 ± 0.6 mm. After an initial mean marginal loss before loading the implants (0.7 mm), no further statistically significant change in marginal bone level (p = .458) could be observed. CONCLUSION: The investigated one-piece zirconia implant showed a high survival rate, very stable marginal bone, and mucosal margin levels after 5 years in function. Therefore, it can be considered safe and reliable for the reconstruction of implant-supported SCs or FDPs over a mid-term period.

All-ceramic single crowns supported by zirconia implants: 5-year results of a prospective multicenter study.

OBJECTIVES: To assess survival/success rates and patient-reported outcome of zirconia-based posterior single crowns (SCs) supported by zirconia implants in a prospective two-center study after five years of observation. MATERIAL AND METHODS: Forty-five patients were restored with 45 zirconia implant-supported posterior SCs composed of zirconia frameworks hand-layered with a leucite-reinforced feldspathic ceramic. Survival rates of SCs were assessed and technical success was evaluated according to modified United States Public Health Care (USPHS) criteria. Furthermore, patient-reported outcome measures (PROMs) were assessed by applying visual analog scales (VAS). Wilcoxon matched-pairs signed-rank test, mixed-effects ordered logistic regression, and linear mixed models were used to evaluate time effects on response variables. RESULTS: Forty patients were available after a mean observation period of 61.0 ± 1.4 months. One SC had to be replaced, resulting in a Kaplan-Meier (KM) survival estimate for the SCs of 97.5 ± 2.47%. Since nine reconstructions showed at least in one category a major deviation from the ideal (five major chippings, four with increased occlusal roughness, one significant crevice, and one pronounced over-contouring), the KM success estimate was 79.3 ± 5.8%. Incidence of chipping (n = 19) and occlusal roughness (n = 35) was frequent (p < 0.001). All PROMs at prosthetic delivery except for speech (p = 0.139) showed significantly improved VAS scores (81%-94%; p < 0.001) compared to pre-treatment evaluations. Thereafter, no decrease in satisfaction could be observed until the 5-year follow-up (93%-97%). CONCLUSION: Veneered zirconia-based SCs supported by zirconia implants showed high survival rates and highly satisfied patients' needs. However, significant incidence of technical complications is compromising the clinical long-term outcome for this indication.

One-piece zirconia oral implants for single-tooth replacement: Three-year results from a long-term prospective cohort study.

AIM: This 3-year report of a prospective long-term cohort investigation aimed to evaluate the clinical and radiographic outcomes of a one-piece zirconia oral implant for single-tooth replacement. MATERIALS AND METHODS: Sixty-five patients received a 1-stage implant surgery with immediate temporization. Standardized radiographs were taken at implant insertion, after 1 year, and after 3 years to monitor peri-implant bone levels. A univariate analysis of the association of different baseline parameters on marginal bone loss from implant insertion to 36 months was performed. Soft-tissue parameters were evaluated at prosthesis insertion, after 6 months, after 1 year, and at the 3-year follow-up. RESULTS: After 3 years, six posterior site implants were lost, giving a cumulative survival rate of 90.8%. The mean marginal bone loss was 1.45 mm; 35% of the implants lost at least 2 mm bone, and 22% more than 3 mm. The univariate analysis did not identify any parameter associated with marginal bone loss. Probing depth, clinical attachment level, and bleeding index increased over 3 years, and plaque index decreased. CONCLUSIONS: The low survival rate of the presented ceramic implant and especially the high frequency of advanced bone loss are noticeable but remain unexplained.

Clinical and patient-reported outcomes of zirconia-based implant fixed dental prostheses: Results of a prospective case series 5 years after implant placement.

OBJECTIVE: To evaluate the clinical and patient-reported outcome of all-ceramic zirconia implant supported fixed dental prostheses (FDPs) 5 years after implant installation. MATERIALS AND METHODS: Thirteen patients were treated with two terminally placed one-piece zirconia implants for a three-unit FDP each. The FDPs consisted of a CAD/CAM-fabricated zirconia framework over-pressed with a fluor-apatite veneering ceramic and were adhesively cemented. Survival and success were assessed by applying modified US Public Health Service (USPHS) criteria and preparation of Kaplan-Meier (KM) plots. Alpha and Bravo ratings were accepted for success (among others including small area veneer chippings and occlusal roughness), whereas Charlie ratings allowing for intra-oral correction (e.g., polishing) were accepted for survival. Furthermore, patient-reported outcome measures (PROMs) were analyzed with the help of visual analogue scales (VAS). Wilcoxon matched-pairs signed-rank test (USPHS criteria) and linear mixed models (PROMs) were used to evaluate time effects on response variables. RESULTS: All patients were available 61.8 ± 1.1 months after implant installation (53.6 ± 3.1 months after final prosthesis insertion). FDP survival was 100%. Significant incidence of veneer chipping (p = .0096) and occlusal roughness (p = .0019) was observed. Charlie rated extent of both phenomena resulted in a KM success estimate of 38.5% (95% CI: 14.1%-62.8%; seven FDPs with obvious roughness, three of them with extended veneer chipping). Compared with the pre-treatment assessments (30%-81% of satisfaction), all surveys at prosthetic delivery showed significantly improved VAS scores (66%-93%; p ≤ .038), except for speech (p = .341). Concerning function, esthetics and self-esteem, no decrease in satisfaction could be observed until the end of follow-up (90%-96%; p ≥ .057), whereas perception of sense (92%) and speech (95%) increased over time (p ≤ .030). Occurrence of technical complications did not correlate with patient satisfaction. CONCLUSIONS: Bi-layered FDPs made from zirconia/fluor-apatite highly satisfied patients but showed significant incidence of technical complications.

The clinical performance of all-ceramic implant-supported single crowns: A systematic review and meta-analysis.

OBJECTIVE: This review aimed at evaluating the survival and technical complication rates of all-ceramic implant-supported single crowns (SC). MATERIAL AND METHODS: Three electronic databases were searched for clinical studies conducted at ≥ 15 patients examining implant-supported all-ceramic SCs over ≥ 12 months. Survival rates of implants and restorations plus technical complication rates of SCs were calculated and tested for statistical correlation with confounding variables. Statistical analysis was performed using a negative binomial distribution model to calculate 5- and 10-year survival and complication estimates. RESULTS: Forty-one included studies reported on implant-supported SCs made of veneered and monolithic high-strength oxide ceramics, monolithic, and veneered glass-based ceramics and of a monolithic resin-nano-ceramic (RNC). Survival estimates for SCs of 93% (95% CI: 86.6%-96.4%) after 5 years and 94.4% (95% CI: 91.1%-96.5%) after 10 years were calculated, corresponding values for implant survival were 95.3% (95% CI: 90.6%-97.7%) and 96.2% (95% CI: 95.1%-97.1%). Technical complication rates after 5/10 years were as follows: chipping 9.0% (95% CI: 5.4%-14.8%)/2.7% (95% CI: 2.1%-3.5%), framework fractures 1.9% (95% CI: 0.7%-4.9%)/1.2% (95% CI: 1%-1.5%), screw loosening 3.6% (95% CI: 1.6%-8.4%)/5.2% (95% CI: 3.6%-7.5%), and decementations with 1.1% (95% CI: 0.4%-2.8%) after 5 years. Some confounding variables influenced the above-mentioned estimates significantly. CONCLUSIONS: All-ceramic implant-supported SCs showed-with the exception of a RNC material-high survival rates. However, failures and technical complications occurred which have to be considered when informing patients on the treatment with implant-supported all-ceramic SCs.

Clinical outcomes of partial and full-arch all-ceramic implant-supported fixed dental prostheses. A systematic review and meta-analysis.

OBJECTIVE: To assess the survival and technical complication rate of partial and full-arch all-ceramic implant-supported fixed dental prostheses (P-FDP/FA-FDP) and supporting implants. MATERIALS AND METHODS: An electronic search through three databases (MEDLINE/Pubmed, Cochrane Library, Embase) was conducted to identify relevant clinical studies with an observation period of at least 12 months, including ≥15 patients. Reconstruction and implant survival rates, technical complications and confounding variables such as processed/installed materials, retention mode and location in the mouth were obtained. Failure and complication rates were analyzed using standard Poisson regression models to calculate 5-year survival and complication estimates. RESULTS: A total of five studies for the P-FDP group and seven studies for the FA-FDP group were included, throughout evaluating veneered zirconia reconstructions. In the P-FDP group, reconstructions were located in posterior regions. Meta-analysis indicated survival estimates on the reconstruction level of 98.3% and 97.7% for P- and FA-FDPs after 5 years. However, chipping of the veneering ceramic was frequent, resulting in estimated 5-year complication rates of 22.8% (P-FDPs) and 34.8% (FA-FDPs). Five-year survival estimates of implants supporting P-FDPs and FA-FDPs of 98.5% and 99.4% were calculated, respectively. Including a total of 540 FDPs, one screw-loosening and 11 de-cementations were reported. Confounding variables were not found to have a significant influence on survival and complication rates. CONCLUSIONS: All-ceramic implant-supported P- and FA-FDPs comprising veneered zirconia frameworks showed high survival but clinically inacceptable fracture rates of the veneering ceramic. Their suitability with regard to this indication and a successful long-term outcome needs to be further evaluated.

Three-year analysis of zirconia implants used for single-tooth replacement and three-unit fixed dental prostheses: A prospective multicenter study.

AIM: The aim of the present investigation was to evaluate clinically and radiographically the outcome of zirconia oral implants after 3 years in function. MATERIALS AND METHODS: In 60 patients in need of either a single-tooth replacement or a three-unit fixed dental prosthesis (FDP), a total of 71 one-piece zirconia implants were placed and immediately restored with temporary fixed prostheses. After a period of at least 2 months in the mandible and at least 4 months in the maxilla, zirconia-based reconstructions were cemented. The implants were clinically and radiologically examined at implant insertion, prosthetic delivery, at 6 months and then yearly up to 3 years. A linear mixed model was used to analyze statistically the influence of prognostic factors on changes in the marginal bone level. RESULTS: Seventy-one implants (48 in the mandible, 23 in the maxilla) inserted in 60 patients were restored with 49 crowns and 11 FDP. One patient lost his implant after 5 weeks. Five patients with one implant each could not be evaluated after 3 years. Based on 55 patients with a total of 66 implants, the mean survival rate was 98.5% after 3 years in function. A statistically significant mean marginal bone loss (0.70 mm ± 0.72 mm) has been detected from implant insertion to the 3-year follow-up. The largest marginal bone loss occurred between implantation and prosthetic delivery (0.67 mm ± 0.56 mm). After delivery, no statistically significant bone level change was observed (0.02 mm ± 0.59 mm). None of the investigated prognostic factors had a significant influence on changes in the marginal bone level. CONCLUSIONS: After 3 years in function, the investigated one-piece zirconia implant showed a high survival rate and a low marginal bone loss. The implant system was successful for single-tooth replacement and three-unit FDPs. Further investigations with long-term data are needed to confirm these findings.

Contemporary Digital Restorative and Minimal-Invasive Preservative Surgical Techniques in the Esthetic Zone: A Case Report.

When immediately temporizing an implant, relining and cementation of the provisional can be a challenging, time-consuming, and contaminating procedure. Excess resin and cement need to be carefully removed from the fresh wound. This can be overcome by digitally backward planning the treatment with subsequent production of a surgical guide to be used by both the technician and the dentist. In this report, a patient with a fractured and hopeless central incisor and an apical radiolucency at his compromised (root-canal treated, post and core build-up) contralateral counterpart was treated using guided implant installation, immediate placement of a prefabricated screw-retained provisional, and apicoectomy. Dehiscence of the buccal plate after tooth extraction resulting in the need for hard- and soft-tissue grafting and delayed surgery did not affect the clinical outcome.

Implant-retained prostheses: ball vs. conus attachments - A randomized controlled clinical trial.

OBJECTIVE: To evaluate implant survival, peri-implant tissue conditions, prosthodontic maintenance requirements and patient satisfaction of two differently retained implant-supported mandibular overdentures (IOD) after the 3 years of observation. MATERIALS AND METHODS: Twenty-five patients with edentulous mandibles received two implants each. Twelve patients were randomly selected to receive ball attachments, whereas 13 patients received prefabricated coni. Implant survival, peri-implant parameters (modified Plaque Index, Bleeding on Probing, modified Gingival Index, probing depth and marginal bone loss) and patient satisfaction were assessed. Additionally, prosthodontic maintenance was monitored. Clinical and radiographic follow-ups were performed 1, 2 and 3 years after prosthetic delivery. The Kaplan-Meier method was used to calculate complication rates. RESULTS: After a mean observation period of 29.6 months, an implant survival rate of 100% could be observed. There were no significant differences in the peri-implant parameters. During the observation period, six patients with conus attachment refused to further participate in follow-ups due to dissatisfaction with their treatment and had to be regarded as dropouts. Based on the Kaplan-Meier method, inacceptable retention was calculated for 80% and 75% of the patients in the ball and the conus groups, respectively. Patient satisfaction was 64% for the ball- and 100% for the conus-retained IODs, the latter only respecting five of initially 13 patients. CONCLUSION: The evaluated treatment method revealed high implant survival rates, but the prosthetic reconstruction required intensive maintenance. Therefore, a trend toward the reduced patient satisfaction was observed, and the promoted economy of the evaluated attachment systems should be questioned. For the conical attachment, the recommendation of the manufacturer is to use four interforaminal implants to support a removable prostheses.

Evaluation of zirconia-based posterior single crowns supported by zirconia implants: preliminary results of a prospective multicenter study.

OBJECTIVE: The aim of this uncontrolled prospective multicenter study was to determine the success and survival rate of posterior single crowns composed of zirconia frameworks hand-layered with a leucite-reinforced feldspathic ceramic supported by one-piece zirconia oral implants. MATERIAL AND METHODS: In two centers, sixty patients received 71 zirconia oral implants. To obtain a clear indication of posterior implant-supported single crowns (ISSCs), 14 patients (25 implants) were excluded from the analysis (11 bridges, three anterior crowns). The remaining patients were provided with single implants in posterior regions. As one patient lost his implant and another refused further participation after final prosthesis insertion, 44 ISSCs/patients (19 females, 25 males) were available for evaluation. Of these patients, all were seen at prosthetic delivery and the 6- and 12-month follow-up appointments. Evaluations were performed using modified United States Public Health Service (USPHS) criteria. Restorations within Alpha and Bravo ratings were regarded as success. This included minor chippings, a slight roughness, slightly soundable restoration margins and minimal contour deficiencies. In case of more distinct defects that could, however, be repaired to a clinically acceptable level, restorations were regarded as surviving. Kaplan-Meier plots and log-rank tests were used for the success/survival analyses and the calculation of potential group differences (gender, jaw and center). RESULTS: After a mean observation period of 12.5 months (SD: 0.8 months), no ISSC had to be replaced, resulting in a Kaplan-Meier survival rate of 100%. The Kaplan-Meier success rate was 90.9% (one major chipping, one obvious roughness, one significant crevice and one pronounced over-contouring). Minor chippings and occlusal roughness were frequent complications. No significantly different survival/success rates could be observed between the mentioned groups. CONCLUSION: The frequent incidence of minor chippings suggests a high technique sensitivity when providing zirconia implants with veneered zirconia-based crowns questioning its suitability for this indication.

Monolithic lithium-disilicate single crowns supported by zirconia oral implants: three-year results of a prospective cohort study.

OBJECTIVE: To determine the survival and success rate of CAD/CAM-fabricated monolithic lithium-disilicate crowns supported by zirconia oral implants after 3 years. MATERIAL AND METHODS: Twenty-four patients in need of a single tooth replacement received a zirconia implant and were finally restored with 24 single crowns (SCs) ground out of pre-crystallized lithium-disilicate blanks. The restorations were adhesively cemented and evaluated using modified United States Public Health Service (USPHS) criteria. In case of clinically relevant defects that could be repaired to an acceptable level, SCs were regarded as surviving. Restorations with minor chippings, a small-area roughness (ø <2 mm), slightly soundable marginal gaps, minimal under-/overcontours, and tolerable color deviations (<1 Vitashade) were regarded as success. The Kaplan-Meier method and log-rank tests were used for the success/survival analyses and the calculation of potential group differences (gender, location, jaw). Additionally, several patient-reported outcome measures (PROMs) were evaluated. RESULTS: Twenty-three patients were seen 3 years after implant placement. No SC had to be replaced, resulting in 100% survival. No chippings were observed. As one SC showed a major occlusal roughness, the Kaplan-Meier success rate after a mean observation period of 31 months was 95.7%. No group differences could be calculated. Compared with the pre-treatment surveys, the further PROMs showed a permanently improved perception of function, esthetics, sense, and speech. CONCLUSION: Monolithic lithium-disilicate SCs supported by zirconia implants showed promising survival and success rates after an observation period of 3 years. It remains to be seen whether the further observation period confirms this positive results.

Bi-layered zirconia/fluor-apatite bridges supported by ceramic dental implants: a prospective case series after thirty months of observation.

OBJECTIVE: The aim of this study was to determine the success and survival rate of all-ceramic bi-layered implant-supported three-unit fixed dental prostheses (IS-FDPs) 3 years after implant placement. MATERIAL AND METHODS: Thirteen patients (seven males, six females; age: 41-78 years) received two one-piece ceramic implants (alumina-toughened zirconia) each in the region of the premolars or the first molar and were finally restored with adhesively cemented bi-layered zirconia-based IS-FDPs (3 in the maxilla, 10 in the mandible) composed of CAD/CAM-fabricated zirconia frameworks pressed-over with fluor-apatite glass-ceramic ingots. At prosthetic delivery and the follow-ups after 1, 2 and 3 years, the restorations were evaluated using modified United States Public Health Service (USPHS) criteria. Restorations with minor veneer chippings, a small-area occlusal roughness, slightly soundable restoration margins, minimal contour deficiencies and tolerable color deviations were regarded as success. In case of more distinct defects that could, however, be repaired to a clinically acceptable level, IS-FDPs were regarded as surviving. Kaplan-Meier plots were used for the success/survival analyses. To verify an impact on subjective patients' perceptions, satisfaction was evaluated by visual analog scales (VAS). RESULTS: All patients were seen 3 years after implant installation. No IS-FDP had to be replaced, resulting in 100% survival after a mean observation period of 29.5 months (median: 30.7). At the 3-year follow-up, 7/13 IS-FDPs showed a veneer chipping, 13/13 an occlusal roughness and 12/13 minimal deficiencies of contour/color. Since six restorations showed a major chipping and/or a major occlusal roughness, the Kaplan-Meier success rate was 53.8%. However, patients' significantly improved perceptions of function, esthetics, sense, and speech at prosthetic delivery remained stable over time. CONCLUSION: Bi-layered zirconia/fluor-apatite IS-FDPs entirely survived the observation period but showed a high frequency of technical complications. Nevertheless, the treatment highly satisfied patients' expectations.

Alumina reinforced zirconia implants: 1-year results from a prospective cohort investigation.

OBJECTIVE: The objective of this investigation was to determine the clinical and radiographic outcome of a one-piece alumina-toughened zirconia (ATZ) oral implant for single tooth replacement after 1 year. MATERIALS AND METHODS: A total of 27 patients received one ATZ implant each in a one-stage implant surgery with immediate temporization. Standardized radiographs were taken at implant insertion and after 1 year to monitor peri-implant bone loss. Several soft tissue parameters were evaluated at prosthesis insertion and at the 1-year follow-up. RESULTS: Three patients did not receive a prosthetic reconstruction due to implant loss during the healing period. As a result, 24 patients were seen at the 1-year follow-up, giving a cumulative survival rate of 88.9%. The average marginal bone loss after 1 year was 0.77 mm. Only two implants (8.3%) lost at least 2 mm bone, whereas none of the implants lost more than 3 mm. Probing depth and clinical attachment level increased over 1 year at the implant sites, whereas gingival recession remained stable. Mombelli's bleeding and plaque indices showed no statistically significant change within the first year. CONCLUSION: Owing to a total of 27 inserted implants, three failures within the first 4 months after implant placement carry weight. Therefore, the cumulative survival rate of the presented ceramic implant was slightly below reported survival rates of titanium implants when immediately restored. The recorded radiographic bone loss and peri-implant soft tissue parameters showed promising short-term results. The presented ATZ implant seems to be a candidate for clinical usage.

Microbial adhesion on novel yttria-stabilized tetragonal zirconia (Y-TZP) implant surfaces with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coatings.

OBJECTIVES: Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concomitant infection. The rationale of this study was to assess the initial adhesion on novel implant surfaces of Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans upon incubation. MATERIALS AND METHODS: The tested samples were 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) samples with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coating (A) and 3Y-TZP samples coated with ceria-stabilized zirconia-based (Ce-TZP) composite and a-C:H:N (B). Uncoated 3Y-TZP samples (C) and bovine enamel slabs (BES) served as controls. Once the surface was characterized, the adherent microorganisms were quantified by estimating the colony-forming units (CFUs). Microbial vitality was assessed by live/dead staining, and microbial-biomaterial surface topography was visualized by scanning electron microscopy (SEM). RESULTS: Overall, A and B presented the lowest CFU values for all microorganisms, while C sheltered significantly less E. faecalis, P. aeruginosa, and C. albicans than BES. Compared to the controls, B demonstrated the lowest vitality values for E. coli (54.12 %) and C. albicans (67.99 %). Interestingly, A (29.24 %) exhibited higher eradication rates for S. aureus than B (13.95 %). CONCLUSIONS: Within the limitations of this study, a-C:H:N-coated 3Y-TZP surfaces tended to harbor less initially adherent microorganisms and selectively interfered with their vitality. CLINICAL RELEVANCE: This could enable further investigation of the new multi-functional zirconia surfaces to confirm their favorable antimicrobial properties in vivo.

Effect of two different healing times on the mineralization of newly formed bone using a bovine bone substitute in sinus floor augmentation: a randomized, controlled, clinical and histological investigation.

PURPOSE: To investigate the amount of the mineralization of a bovine bone substitute material in sinus floor augmentation after healing times of 3 and 6 months. MATERIALS AND METHODS: Fifty-one patients were randomized into two healing time groups and received sinus floor augmentations with a bovine bone material. After 3 or 6 months of healing, trephine bone biopsies were retrieved. The biopsies were processed for histological and histomorphometric evaluations to primarily investigate the amount of mineralized bone in the augmented area and secondarily compare the amount of mineralized bone in the augmented area and in the pristine bone. Statistical tests were performed to analyse the fraction of the mineralized bone (p < 0.05). RESULTS: The biopsies of both groups showed remnants of the well-integrated bone substitute material. The histology revealed osteoblasts, osteocytes with osteoid, and osteoclasts. The mean percentage of mineralized bone in the augmented area was 23.8% (3 months group) and 23.6% (6 months group; p = 0.9246); the amount of remaining bone substitute material was 35% (3 months group) and 33.9% (6 months group; p = 0.6325). CONCLUSION: It can be concluded that the bone maturation in the augmented sinus using the bovine bone material is similar after 3 and 6 months. Thus, implant installation after 3 months following a lateral window sinus floor augmentation approach using a bovine bone material seems to be clinically acceptable.

One-piece zirconia oral implants: one-year results from a prospective case series. 2. Three-unit fixed dental prosthesis (FDP) reconstruction.

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.