Prevalence of proximal contact loss between implant-supported prostheses and adjacent natural teeth: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Proximal contact loss between implant-supported prostheses and adjacent natural teeth is a complication that has been reported in clinical practice. However, the prevalence of the condition is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to assess the proportion of reported proximal contact loss between implant-supported prostheses and adjacent natural teeth. MATERIAL AND METHODS: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology criteria and was registered on the international prospective register of systematic reviews (PROSPERO) platform (CRD42021225138). The electronic search was conducted by using the PubMed/MEDLINE, Embase, and Cochrane Library databases to September 2020. The formulated population, intervention, comparison, outcome (PICO) question was "Is there a correlation of the proximal contact loss between implant-supported prostheses and the adjacent natural tooth?" A single-arm meta-analysis of proportion was performed to evaluate the cumulative prevalence of survival and complication rates. RESULTS: This review included 10 studies, half of which presented proximal contact loss rates higher than 50%. In the general analysis, the open proximal contact showed a cumulative proportion of 41% (confidence interval: 30% to 53%; heterogeneity: I2=98%; t2=0.578; P<.01). From the subanalysis, the mesial contact (47%; confidence interval: 32% to 62%; heterogeneity: I2= 96%; t2=0.657; P<.01) and the mandibular arch (41%; confidence interval: 30% to 52%; heterogeneity: I2=92%; t2=0.302; P<.01) were found to have higher prevalence. CONCLUSIONS: The prevalence of proximal contact loss was high, occurring more frequently with the mesial contact and in the mandibular arch. Significant differences were not found in relation to sex or between the posterior and anterior regions.

Should the restoration of adjacent implants be splinted or nonsplinted? A systematic review and meta-analysis.

STATEMENT OF PROBLEM: The decision to splint or to restore independently generally occurs during the planning stage, when the advantages and disadvantages of each clinical situation are considered based on the proposed treatment. However, clinical evidence to help clinicians make this decision is lacking. PURPOSE: The purpose of this systematic review and meta-analysis was to assess the marginal bone loss, implant survival rate, and prosthetic complications of splinted and nonsplinted implant restorations. MATERIAL AND METHODS: This study was designed according to the Cochrane criteria for elaborating a systematic review and meta-analysis and adopted the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Also, this review was registered at the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42017080162). An electronic search in the PubMed/MEDLINE, Cochrane Library, and Scopus databases was conducted up to November 2017. A specific clinical question was structured according to the population, intervention, comparison, outcome (PICO) approach. The addressed focused question was "Should the restoration of adjacent implants be splinted or nonsplinted?" The meta-analysis was based on the Mantel-Haenszel and inverse variance methods to assess the marginal bone loss, implant survival, and prosthetic complications of splinted and nonsplinted implant restorations. RESULTS: Nineteen studies were selected for qualitative and quantitative analyses. A total of 4215 implants were placed in 2185 patients (splinted, 2768; nonsplinted, 1447); the mean follow-up was 87.8 months (range=12-264 months). Quantitative analysis found no significant differences between splinted and nonsplinted restorations for marginal bone loss. The assessed studies reported that 75 implants failed (3.4%), of which 24 were splinted (99.1% of survival rate) and 51 were nonsplinted (96.5% of survival rate). Quantitative analysis of all studies showed statistically significant higher survival rates for splinted restorations than for nonsplinted restorations. Ceramic chipping, screw loosening, abutment screw breakage, and soft tissue inflammation were reported in the selected studies. The quantitative analysis found no statistically significant difference in the prosthetic complications of splinted and nonsplinted restorations. CONCLUSIONS: Within the limitations of this systematic review and meta-analysis, it was concluded that there was no difference in the marginal bone loss and prosthetic complications of splinted and nonsplinted implant restorations; this is especially true for restorations in the posterior region. However, splinted restorations were associated with decreased implant failure.

[Effect of Aging on the Mechanical Properties of CAD/CAM-Milled and 3D-Printed Acrylic Resins for Denture Bases].

PURPOSE: The purpose of this study was to investigate the mechanical properties of acrylic resins at different aging times for denture bases manufactured using the conventional method, microwave processing, milling, and 3D printing. MATERIALS AND METHODS: A total of 160 rectangular samples (64 Å~ 10 Å~ 3.3 ± 0.03 mm) were prepared, divided among the four main resin groups, and subdivided into four analysis times (T0, T1, T2, and T3), resulting in 10 samples per subgroup. The samples were stored in distilled water at 37° ± 2°C for 24 hours (T0), then subjected to thermocycling at temperatures of 5° ± 1°C and 55° ± 1°C in different numbers of cycles: 5,000 (T1); 10,000 (T2); and 20,000 (T3). The mechanical properties evaluated were surface microhardness, flexural strength, and modulus of elasticity. Statistical differences between resin groups and aging time were evaluated using two-way analysis of variance (P < .05). RESULTS: The 3D-printed resin showed the significantly lowest values of microhardness, flexural strength, and modulus of elasticity compared to other resins (P < .001). CONCLUSIONS: The CAD/CAM-milled denture resin showed mechanical properties similar to those of traditional resins (conventional and microwave-processed). The 3D-printing resin did not show adequate mechanical properties for long-term clinical use. Despite this, new studies are developing better properties of this resin for long-term use.