RESUMO

OBJECTIVES: The aim of this in vitro study was to evaluate the stress distribution on three implant models with narrow and extra-narrow diameters using the finite element method (FEA). MATERIALS AND METHODS: Dental implants of extra-narrow diameter of 2.5 mm for a one-piece implant (group G1), a narrow diameter of 3.0 mm for a one-piece implant (group G2) and a narrow diameter of 3.5 mm for a two-piece implant with a Morse taper connection (group G3). A three-dimensional model was designed with cortical and cancellous bone, a crown and an implant/abutment set of each group. Axial and angled (30°) loads of 150 N was applied. The equivalent von Mises stress was used for the implants and peri-implant bone plus the Mohr-Coulomb analysis to confirm the data of the peri-implant bone. RESULTS: In the axial load, the maximum stress value of the cortical bone for the group G1 was 22.35% higher than that the group G2 and 321.23% than the group G3. Whereas in angled load, the groups G1 and G2 showing a similar value (# 3.5%) and a highest difference for the group G3 (391.8%). In the implant structure, the group G1 showed a value of 2188MPa, 93.6% higher than the limit. CONCLUSIONS: The results of this study show that the extra-narrow one-piece implant should be used with great caution, especially in areas of non-axial loads, whereas the one- and two-piece narrow-diameter implants show adequate behavior in both directions of the applied load.

Assuntos

RESUMO

BACKGROUND: The goal of this study was to analyze the stress distribution on two types of extra-short dental implants with 5 mm of length: An internal hexagon (IH) and morse taper connection (MT). METHODS: The three-dimensional model was composed of trabecular and cortical bone, a crown, an extra-short dental implant and their components. An axial load of 150 N was applied and another inclined 30° with the same magnitude. RESULTS: Stress concentrations on the IH implant are observed in the region of the first threads for the screw. However, in the MT implant the highest stress occurs at the edges of the upper implant platform. CONCLUSIONS: In view of the results obtained in this study the two types of prosthetic fittings present a good stress distribution. The Morse taper connections presented better behavior than the internal in both loading configurations.

RESUMO

OBJECTIVE: The proposal of this study was to use a photoelasticity method to analyze the stress dissipation in the bone surrounding an implant under simulated loading. MATERIALS AND METHODS: Four implant systems with different internal connection designs were studied: conical connection (group 1), triangular connection (group 2), Morse taper (group 3), and internal hexagon (group 4). After the models' inclusion in a photoelastic resin, they were subjected to static loads of 100, 150, and 200 N. The lengths of fringes that were generated were measured at the bone crest parallel to the neck of the implant and along the implant body, as well as the dissipation of force across the entire area of extension. RESULTS: Lower stress was observed at the crestal bone in groups 1 and 3 with no significant increase (P < 0.05) in different levels of load, whereas the stress levels in groups 2 and 4 were observed to be higher with loads of all intensities with significant differences from the other groups (P < 0.05). CONCLUSIONS: The type of connection and the implant neck design influenced the dissipation of force. The conical-type connection exhibited better load dissipation in the neck area, regardless of the load applied on the implant.

Assuntos

RESUMO

O objetivo deste trabalho foi comparar o nível de reabsorção óssea peri-implantar, em função dos três diferentes tipos de antagonistas oclusais em pacientes portadores de próteses implantossuportadas. Partindo-se uma amostra de 52 arquivos, foram selecionados nove pacientes, que apresentavam um total de 29 implantes na região posterior da mandíbula, reabilitados com coroas de porcelana sobreimplante, que tinham como antagonistas dentes naturais (G1), próteses totais (G2), ou próteses implantossuportadas (G3). Não foi objeto deste estudo uma comparação entre implantes com hexágono interno e externo. Todos os implantes, incluídos nesse estudo, foram moldados 30 dias após a instalação dos abutments de cicatrização. Foram construídos 59 elementos, sendo que 89% receberam próteses parafusadas elaboradas a partir de Uclas totalmente plásticas e 11% foram próteses cimentadas confeccionadas sobre um munhão de titânio. As perdas ósseas ocorridas após a reabilitação protética foram medidas e comparadas através da digitalização das radiografias realizadas na reabertura, antes do carregamento protético e após dois anos em função. Os dados obtidos foram analisados pela análise de variância (Anova) e todos os implantes apresentaram perda óssea, independente do tipo do antagonista; como o valor de p encontrado foi maior do que 0,05, os grupos foram considerados semelhantes, não havendo diferença estatisticamente significativa entre eles, ao nível de significância de 5%.

The aim of this study was to compare the level of peri-implant bone resorption, according to the three different types of arch antagonists in patients with implant-supported prostheses. From 52 file recordings, nine patients with a total of 29 implant-supported porcelain crowns in the posterior mandible were selected, having natural teeth (G1), dentures (G2), or implant-supported prostheses (G3) as antagonists. Different implant connection types were not compared. All impressions procedures were made 30 days after implant and healing abutment installation. Fifty-nine elements were constructed, of which 89% were screwed prosthesis from plastic, burnout Ucla abutments and 11% were cemented prosthesis over titanium abutments. Bone loss after prosthetic rehabilitation was measured and compared by scanning the radiographs taken during reopening before prosthetic loading and after two years in function. The data were analyzed by analysis of variance (Anova), and all implants showed bone loss, regardless of antagonist type (p > .05).

Assuntos