ABSTRACT
Os implantes osseointegrados demonstram, com o passar dos anos, que são uma opção viável na reabilitação de pacientes desdentados parciais ou totais, tendo resultados satisfatórios e com considerável longevidade clínica quando utilizados em reabilitação oral. Porém, o afrouxamento e fratura dos parafusos de retenção do pilar são as principais complicações em próteses sobre implantes, o que compromete a longevidade da reabilitação, sendo necessário buscar alternativas viáveis para reduzir ao máximo tal intercorrência. O objetivo do trabalho foi avaliar a manutenção do torque remanescente e ocorrência de falhas em parafusos de retenção de pilares protéticos, para implantes de conexão hexagonal externa. Os parafusos foram revestidos por filmes de carbono tipo diamante (DLC) dopados ou não com nanopartículas de prata (Ag). Foram utilizados 30 implantes de conexão hexagonal externa com plataforma regular e seus respectivos pilares protéticos, distribuídos em 3 grupos de acordo com o tipo de tratamento superficial do parafuso protético (n=10): Grupo A (controle) - sem tratamento na superfície do parafuso; Grupo B - parafuso revestido com filme de DLC; Grupo C - parafuso revestido com filme de DLC/Ag. Os filmes de DLC e DLC/Ag foram depositados pelo processo PECVD (Plasma Enhanced Chemical Vapour Deposition). A manutenção do torque após envelhecimento mecânico foi avaliada em todos os grupos. Será realizada microscopia eletrônica de varredura (MEV) antes e após o teste de fadiga, para avaliar possíveis alterações no filme de DLC. Os resultados serão analisados primeiramente de forma descritiva para determinação das análises estatísticas inferenciais a serem realizadas. (AU)
Over the years, osseointegrated implants have shown that they are a viable option in the rehabilitation of partially or totally edentulous patients, with satisfactory results and considerable clinical longevity when used in oral rehabilitation. However, loosening and fracture of the abutment retention screws are the main complications in implant-supported prostheses, which compromises the longevity of rehabilitation, making it necessary to seek viable alternatives to minimize this complication. This study aimed to evaluate the maintenance of the remaining torque and the occurrence of failures in retention screws of prosthetic abutments, for implants with external hexagonal connection. The screws were coated with diamond-like carbon (DLC) films, doped or not with silver nanoparticles (Ag). Thirty external hexagonal connection implants with a regular platform and their respective prosthetic abutments were used, divided into 3 groups according to the type of surface treatment of the prosthetic screw (n=10): Group A (control) - no treatment on the screw surface ; Group B - screw coated with DLC film; Group C - screw coated with DLC/Ag film. The DLC and DLC/Ag films were deposited by the PECVD (Plasma Enhanced Chemical Vapour Deposition) process. Torque maintenance after mechanical aging was evaluated in all groups. Scanning electron microscopy (SEM) will be performed before and after the fatigue test to evaluate possible changes in the DLC film. The results will be analyzed first in a descriptive way to determine the inferential statistical analyzes to be performed. (AU)
Subject(s)
Prostheses and Implants , Microscopy, Electron, Scanning , Dental Implants , Fractures, BoneABSTRACT
This study evaluated the influence of retorque on loosening torque (Lt) of prosthetic screws in implant-supported dentures with different fit levels. Ten mandibular implant-supported dentures were fabricated and then 20 cast models were then prepared using prosthetic structures to create 2 fit levels: passive fit (Pf) and misfit (Mf). Two tightening techniques were also evaluated: initial torque only (T1); and initial torque and retorque after 10 min (T2). Gold or titanium screws were used, resulting in 4 groups to each one: Pf/T1, Pf/T2, Mf/T1, Mf/T2. The Lt was measured 24 h after the tightening torque using digital torque meter. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05), separately for each screw material. For titanium screws, no significant difference (p>0.05) was found between Pf/T1 and Pf/T2, or between Pf/T2 and Mf/T2. However, statistically significant difference (p<0.05) was found between Pf/T1 and Mf/T1, and between Mf/T1 and Mf/T2. Mf reduced the Lt using T1, while and T2 increased the Lt for Mf. Retorque and fit were shown to have no significant influence on the Lt of the gold screws. Retorque application made insignificant the misfit effect on the Lt of the titanium screws, suggesting that this procedure should be performed routinely during the screw tightening in multi-unit dentures.
Este estudo avaliou a influência do retorque no Ta dos parafusos protéticos em próteses implantossuportadas com diferentes níveis de adaptação. Foram confeccionadas 10 próteses mandibulares implantossuportadas. Vinte modelos de gesso foram fabricados utilizando as estruturas protéticas para criar os 2 níveis de adaptação: adaptação passiva (AP) e desajuste (D). Foram avaliadas 2 técnicas de aperto do parafuso: inicial torque (T1); e inicial torque e retorque após 10 min (T2). Foram usados parafusos de ouro e titânio, resultando em 4 grupos para cada material do parafuso: AP/T1, AP/T2, D/T1, D/T2. O Ta foi mensurado 24 h após o torque de aperto utilizando torquímetro digital. Os resultados foram analisados pela ANOVA (2 fatores) e teste de Tukey (α=0,05), separadamente para cada material dos parafusos. Para os parafusos de titânio, não foi encontrada diferença estatística significante entre AP/T1 e AP/T2, ou AP/T2 e D/T2; porém, diferença significante foi encontrada entre AP/T1 e D/T1, ou D/T1 e D/T2. Onde, D reduziu a Ta utilizando T1; e T2 aumentou o Ta para D. Retorque e adaptação não apresentaram influência significante no Ta dos parafusos de ouro. A aplicação do retorque tornou insignificante o efeito do desajuste no Ta dos parafusos de titânio, sugerindo que este procedimento deveria ser usado rotineiramente durante os parafusos protéticos de titânio em próteses múltiplas.
Subject(s)
Humans , Dental Abutments , Dental Implants , Dental Marginal Adaptation , Dental Prosthesis, Implant-Supported , Acrylic Resins/chemistry , Chromium Alloys/chemistry , Denture Design , Denture, Complete, Lower , Dental Alloys/chemistry , Dental Marginal Adaptation/classification , Dental Materials/chemistry , Denture Retention/instrumentation , Gold Alloys/chemistry , Materials Testing , Time Factors , Tooth, Artificial , Torque , Titanium/chemistryABSTRACT
OBJECTIVES: This study evaluated the influence of prosthetic screw material on joint stability in implantsupported dentures at two levels of fit. METHODS: Ten mandibular implant-supported dentures were fabricated. Twenty cast models were fabricated using these dentures. Four groups (n=10) were tested, according to the vertical fit of the dentures [passive and non-passive] and prosthetic screw materials [titanium (Ti) or gold (Au) alloy]. The one-screw test was performed to quantify the vertical misfits using an optic microscope. The loosening torque for the prosthetic screws was measured 24 hours after the tightening torque (10 Ncm) using a digital torque meter. Data were analyzed by two-way ANOVA and Tukey's test (alpha=0.05). RESULTS: Overall, dentures with passive fit and Ti screws resulted in significantly higher loosening torque of the prosthetic screws (p<0.05). No significant interaction was found between fit level and screw material (p=0.199). The prosthetic screw material and fit of implant-supported dentures have an influence on screw joint stability. Ti screws presented higher joint stability than Au screws and minimum of misfit should be found clinically to improve the mechanical behavior of the screw joint.