Objective: To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. Study design: Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A. (Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (Göteborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prosthetic abutments. The implant-to-abutment fit/misfit was evaluated at four points (vestibular, lingual/palatine, mesial and distal) between implants and abutments of the same brand and different brands, with or without mechanical torque, using SEM micrographs at 5000X. Image analysis was performed using NIS-Elements software (Nikon Instruments Europe B.V.). Results: Before applying torque, vertical misfit (microgaps) of the different combinations tested varied between 1.6 and 5.4 microns and after applying torque, between 0.9 and 5.9 microns, an overall average of 3.46±2.96 microns. For manual assembly without the use of mechanical torque, the best results were obtained with the combination of the 3i implant and the BTI abutment. The Nobel implant and Nobel abutment, 3i-3i and BTI-BTI and the combination of 3i implant with BTI or Nobel abutment provided the best vertical fit when mechanical torque was applied. Conclusions: The vertical fits obtained were within the limits considered clinically acceptable. The application of mechanical torque improved outcomes. There is compatibility between implants and abutments of different brand and so their combination is a clinical possibility. Key words:Vertical fit, implant, prosthetic abutment, combination.

BackgroundThis work aims to confirm if implant-supported overdentures are a good treatment option for edentulous patients and offer an improvement in quality of life compared with traditional complete prostheses (dentures).Material and MethodsThis retrospective clinical descriptive study included three evaluation groups: validation group (n=57); control group of patients with complete removeable prostheses (n=56); study group of patients with implant-supported overdentures retained with the Locator® system (n=80). The study also validated the Oral Health Impact Profile-20 questionnaire. Individual protocols were created that included socio-demographic data, the Oral Health Impact Profile-20 (OHIP-20) questionnaire and Oral Satisfaction Scale (OSS). Descriptive and bivariate statistical analysis was carried out applying χ², Pearson, Kruskal-Wallis, and Student t tests, transferring data into SPSS-Windows® software from a Microsoft® Excel spreadsheet.ResultsThe OHIP-20 proved to be a valid instrument and provided reliable assessment of health-related quality of life among both the Spanish general population and edentulous patients. The control and study groups proved comparable, showing socio-demographic homogeneity. For patients with overdentures retained by means of the Locator® system, these restorations had significantly lower impact on quality of life (19 vs 33), both generally and for each individual questionnaire item, and much higher satisfaction with the state of their oral cavities (8.3 vs 5.3) than patients wearing dentures; both sets of data showed a direct linear relationship, so that as the level of impact on quality of life increased, perceived oral satisfaction worsened.ConclusionsPatients rehabilitated with implant supported overdentures retained by the Locator® system, presented significantly lower levels of impact on their quality of life and significantly higher oral satisfaction than patients with conventional complete prostheses. Key words: Oral health-related quality of life, OHIP-20, OSS, overdentures, dental implants, complete prostheses, Locator® system.

BackgroundIt is necessary to know the in vitro behavior of different attachment systems to be used clinically. The evolution of retention capacity over 10 years (14,600 insertion/de-insertion cycles) was determined in vitro, evaluating two overdenture attachment systems (Locator® and OT Equator®).Material and MethodsThe study used an implant replica compatible with the abutments of both systems. 10 Locator® and 10 OT Equator® attachments were screwed to the abutments. Nylon inserts were attached and tested, subjecting them to 14,600 insertion and de-insertion cycles (representing 10 years functional life) in axial direction. The universal test machine crosshead speed was 50 mm/min with a de-insertion range of 2 mm.ResultsThe initial retention of Locator® was 17.02 N and of Equator® 16.36 N. After 14,600 cycles, Locator® suffered a mean loss of retention of 50.89%, while Equator® lost 69.28%. Both systems showed retention increases up to the first 1,000 cycles, which decreased thereafter up to 14.600 cycles. Statistically significant differences between the systems were found after 7,500 cycles.ConclusionsBoth systems presented acceptable retention capacities after 14,600 cycles. Significant differences in retention force between the systems evolved after 7,500 cycles (5 years in vitro use). These results should be treated with caution and should be verified clinically. Key words:Denture, mandibular prosthesis implantation, attachment, dental implant-abutment connection, denture retention.

Background: The aim of this systematic review and meta-analysis was to determine the wear sustained in the natural antagonist tooth in cases of full-coverage fixed-base prosthetic restorations or monolithic zirconia tooth-supported crowns, as well as to determine the wear in the restoration itself, both in the short- and medium-term and considering the factors that may influence wear. Material and methods: A systematic literature review and meta-analysis, based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations, of clinical studies that evaluated wear in antagonist teeth in relation to fixed-prosthesis monolithic zirconia crowns. A total of 5 databases were consulted in the literature search: Pubmed-Medline, Cochrane, Scopus, Embase and Web of Science (WOS). After eliminating duplicated articles and applying the inclusion criteria, eight articles were selected for the qualitative analysis and four for the quantitative analysis. Results: Mean maximum wear of the antagonist tooth in relation to monolithic zirconia crowns of magnitude 95.45 µm (CI at 95% 79.57–111.33) was observed. By using a meta-regression model (R2 = 0.92) the significant effect of time in maximum wear rate (p < 0.001) was observed, estimated at 6.13 µm per month (CI at 95% 3.99–8.27). Furthermore, monolithic zirconia crowns are subject to a mean maximum wear of 58.47 µm (CI 95% 45.44–71.50). By using a meta-regression model (R2 = 0.53) the significant effect of time in the maximum wear value was observed (p = 0.053), estimated at 3.40 µm per month (CI al 95% −0.05–6.85). Conclusions: Monolithic zirconia crowns lead to a progressive maximum wear of the antagonist tooth over time which is greater than the maximum wear sustained in the crown itself. It is not possible to establish an objective and quantitative objection in relation to natural enamel wear or metal–ceramic crowns.

Background: The objective of this systematic review and meta-analysis was to analyze the periodontal behavior around teeth prepared with horizontal finishing crowns supporting fixed metal-ceramic and zirconia full coverage crowns and fixed partial dentures (FDPs). Materials and methods: An electronic search was conducted to locate relevant clinical trials in four databases: PubMed, Embase, Cochrane, and Scopus. A manual search was made in the reference sections of the articles identified for any additional articles. No restrictions were applied regarding year of publication or language. The following variables were considered in quantitative and qualitative analysis: probing pocket depth (PPD); probing attachment level (PAL); plaque control record (PCR); bleeding on probing (BOP); and gingival margin migration. Results: Twenty articles were selected for qualitative synthesis, and of these, nine underwent meta-analysis. Higher PCR was found in control teeth, while BOP, PPD, and PAL were higher around teeth prepared with horizontal finishing lines supporting complete coverage crowns/FDPs Gingival migration results were the clearest manifestation of compromised periodontal health around teeth prepared with horizontal finishing lines. Conclusions: Meta-analysis revealed that teeth prepared with horizontal finishing lines supporting crowns and FDPs present more periodontal disorders than untreated control teeth.