Fracture Resistance of a Two-Piece Zirconia Implant System after Artificial Loading and/or Hydrothermal Aging-An In Vitro Investigation.

The purpose of the present study was to assess the fracture resistance of a two-piece alumina-toughened zirconia implant system with a carbon-reinforced PEEK abutment screw. METHODS: Thirty-two implants with screw-retained zirconia abutments were divided into four groups of eight samples each. Group 0 (control group) was neither loaded nor aged in a chewing simulator; group H was hydrothermally aged; group L was loaded with 98 N; and group HL was subjected to both hydrothermal aging and loading in a chewing simulator. One sample of each group was evaluated for t-m phase transformation, and the others were loaded until fracture. A one-way ANOVA was applied to evaluate differences between the groups. RESULTS: No implant fracture occurred during the artificial chewing simulation. Furthermore, there were no statistically significant differences (p > 0.05) between the groups in terms of fracture resistance (group 0: 783 ± 43 N; group H: 742 ± 43 N; group L: 757 ± 86 N; group HL: 740 ± 43 N) and bending moment (group 0: 433 ± 26 Ncm; group H: 413 ± 23 Ncm; group L: 422 ± 49 Ncm; group HL: 408 ± 27 Ncm). CONCLUSIONS: Within the limitations of the present investigation, it can be concluded that artificial loading and hydrothermal aging do not reduce the fracture resistance of the investigated implant system.

Long-Term Stability of Hydrothermally Aged and/or Dynamically Loaded One-Piece Diameter Reduced Zirconia Oral Implants.

The aim of this in vitro study was to evaluate the long-term stability of one-piece diameter reduced zirconia oral implants under the influence of loading and artificial aging in a chewing simulator as well as the fracture load in a static loading test. Thirty-two one-piece zirconia implants with a diameter of 3.6 mm were embedded according to the ISO 14801:2016 standard. The implants were divided into four groups of eight implants. The implants of group DLHT were dynamically loaded (DL) in a chewing simulator for 107 cycles with a load of 98 N and simultaneously hydrothermally aged (HT) using a hot water bath at 85 °C. Group DL was only subjected to dynamic loading and group HT was exclusively subjected to hydrothermal aging. Group 0 acted as a control group: no dynamical loading, no hydrothermal ageing. After exposure to the chewing simulator, the implants were statically loaded to fracture in a universal testing machine. To evaluate group differences in the fracture load and bending moments, a one-way ANOVA with Bonferroni correction for multiple testing was performed. The level of significance was set to p < 0.05. In the static loading test, group DLHT showed a mean fracture load of 511 N, group DL of 569 N, group HT of 588 N and control group 0 of 516 N. The average bending moments had the following values: DLHT: 283.5 Ncm; DL: 313.7 Ncm; HT: 324.4 Ncm; 0: 284.5 Ncm. No significant differences could be found between the groups. Hydrothermal aging and/or dynamic loading had no significant effect on the stability of the one-piece diameter reduced zirconia implants (p > 0.05). Within the limits of this investigation, it can be concluded that dynamic loading, hydrothermal aging and the combination of loading and aging did not negatively influence the fracture load of the implant system. The artificial chewing results and the fracture load values indicate that the investigated implant system seems to be able to resist physiological chewing forces also over a long service period.

One-Piece Zirconia Oral Implants for Single Tooth Replacement: Five-Year Results from a Prospective Cohort Study.

The intention of this 5-year prospective cohort investigation was to clinically and radiographically investigate the outcomes of a one-piece zirconia implant system for single tooth replacement. Sixty-five patients received a total of 66 single-tooth implants. All implants immediately received temporary restorations and were finally restored with all-ceramic crowns. Follow-ups were performed at the prosthetic delivery, after 1, 3, and 5 years. Peri-implant and dental soft-tissue parameters were evaluated and patient-reported outcomes recorded. To monitor peri-implant bone remodelling, standardised radiographs were taken at the implant insertion and at the 1-, 3-, and 5-year follow-ups. In the course of 5 years, 14 implants were lost, resulting in a cumulative implant survival rate of 78.2%. The mean marginal bone loss from the implant insertion to the 5-year follow-up amounted to 1.12 mm. Probing depth, clinical attachment level, bleeding, and plaque index increased over time. In 91.5% of the implants, the papilla index showed levels of 1 or 2, respectively. At the end of the study, the patient satisfaction was higher compared to the pre-treatment measurements. Due to the low survival rate after five years and the noticeably high frequency of advanced bone loss observed in this study, the implant has not met the launch criteria, as it would have not been recommended for routine clinical use.

One-Piece Zirconia Oral Implants for the Support of Three-Unit Fixed Dental Prostheses: Three-Year Results from a Prospective Case Series.

The objective was to investigate the clinical and radiological outcome of one-piece zirconia oral implants to support three-unit fixed dental prostheses (FDP) after three years in function. Twenty-seven patients were treated with a total of 54 implants in a one-stage surgery and immediate provisionalization. Standardized radiographs were taken at implant placement, after one year and after three years, to evaluate peri-implant bone loss. Soft-tissue parameters were also assessed. Linear mixed regression models as well as Wilcoxon Signed Rank tests were used for analyzing differences between groups and time points (p < 0.05). At the three-year evaluation, one implant was lost, resulting in a cumulative survival rate of 98.1%. The mean marginal bone loss amounted to 2.16 mm. An implant success grade I of 52% (bone loss of ≤2 mm) and success grade II of 61% (bone loss of ≤3 mm) were achieved. None of the evaluated baseline parameters affected bone loss. The survival rate of the zirconia implants was comparable to market-available titanium implants. However, an increased marginal bone loss was observed with a high peri-implantitis incidence and a resulting low implant success rate.

Non-Precious Metal Alloy Double Crown-Retained Removable Partial Dentures: A Cross-Sectional In Vivo Investigation.

(1) Background: An alternative material to precious metal alloys are non-precious metal alloys. The material properties of these are different and, therefore, their clinical, biological and mechanical behaviors may also differ. Hence, the purpose of this in vivo investigation was to analyze the clinical and patient-reported outcomes of patients restored with non-precious metal alloy double crown-retained removable partial dentures (NP-D-RPDs). (2) Methods: Partially edentulous patients were restored with non-precious metal alloy partially veneered NP-D-RPDs. Survival rates, success rates, failures and patient-reported outcomes were investigated and statistically evaluated. (3) Results: A total of 61 patients (65.6 ± 10.8 years) were included and clinically and radiographically examined. The mean follow-up time was 25.2 ± 16.5 months. In total, 82 NP-D-RPDs and 268 abutment teeth were examined. The overall survival rate of the NP-D-RPDs was 100% after a mean follow-up time of 2.1 years. The overall success rate was 68.3%. The overall satisfaction with the NP-D-RPDs was 94.3%. (4) Conclusions: Non-precious metal alloy partially veneered NP-D-RPDs seem to be an efficient alternative to precious metal alloy RPDs with excellent patient-reported outcomes.

In Vitro Time Efficiency, Fit, and Wear of Conventionally- versus Digitally-Fabricated Occlusal Splints.

The purpose of the study was to compare conventional to digital workflows of occlusal splint production regarding time efficiency, overall fit, and wear. Fifteen Michigan splints were fabricated with a conventional and digital method. The duration for the dentist's and the dental technician's workload was recorded. Subsequently, the overall fit was examined with a four-level score (1-4). Paired t-tests were used to compare the time results for the conventional and digital workflows and the sign test to compare the overall fit. The mean time (16 min 58 s) for computerized optical impressions was longer than for conventional impressions (6 min 59 s; p = 0.0001). However, the dental technician needed significantly less mean time for the digital splint production (47 min 52 s) than for the conventional (163 min 32 s; p = 0.001). The overall fit of the digitally-fabricated splints was significantly better compared to the conventionally-fabricated splints (p = 0.002). There was no impact of the different materials used in the conventional and digital workflow on the wear (p = 0.26). The results suggest that the digital workflow for the production of occlusal splints is more time efficient and leads to a better fit than the conventional workflow.

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.

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.

CAD/CAM-fabricated implant-supported restorations: a systematic review.

OBJECTIVES: The aim of this systematic review was to identify and summarize the available literature related to CAD/CAM-fabricated implant-supported restorations. MATERIALS AND METHODS: A systematic review of the literature was conducted using the Cochrane Library and the US Library of Medicine, National Institute of Health databases (Pubmed). Several search runs with specific search terms were performed and combined. All published papers available on the databases up to January 15, 2015 were considered with primarily no restrictions. RESULTS: About 12 of 3484 identified papers met the inclusion criteria and were analyzed in the present review. One paper reported results on implant-supported single crowns (SCs), one on partial fixed dental prostheses (FDPs), and 10 papers reported results on full-arch screw-retained FDPs. Publications on SCs and FDPs were very limited but it was possible to identify 10 papers reporting adequate results on full-arch screw-retained FDPs. Survival rates ranged between 92% and 100% with observation times of 1-10 years. CONCLUSION: The available data provided promising results for CAD/CAM-fabricated implant-supported restorations; nonetheless, current evidence is limited due to the quality of available studies and the paucity of data on long-term clinical outcomes of 5 years or more. In the sense of an evidence-based dentistry, the authors recommend further studies designed as randomized controlled clinical trials and reported according to the CONSORT statement.

Evaluation of Guided Bone Regeneration around Oral Implants over Different Healing Times Using Two Different Bovine Bone Materials: A Randomized, Controlled Clinical and Histological Investigation.

PURPOSE: To evaluate the potential of two bone substitute materials and the influence of different healing periods in guided bone regeneration therapy of osseous defects around implants. MATERIALS AND METHODS: Twenty-four edentulous patients received implants in the region of the lost lower incisors. Around two standardized osseous defects were created, treated either with a 50:50 mixture of PepGen P-15® and OsteoGraf®/N-700 (test group) or with BioOss® (control group), and covered with titanium membranes. After healing periods of 2, 4, 6, or 9 months, the implants were removed together with the surrounding bone and subsequently prepared for histological evaluations. RESULTS: Defect depths in both groups showed a clinical reduction after intervention. The histologically measured distance from the implant shoulder to the first point of bone-implant contact (BIC) after treatment did not differ between the two groups. The healing time influenced the level of the first point of BIC, with a longer healing period producing a more coronal first point of BIC. A greater percentage BIC and a higher fraction of mineralized bone were found in the pristine bone area compared with the augmented defect area. CONCLUSION: It can be concluded that in the treatment of osseous defects around oral implants, both materials were equally effective bone substitute materials when used in combination with guided bone regeneration.