Effect of framework type on survival probability of implant-supported temporary crowns: An in vitro study.

BACKGROUND: This in vitro study evaluated the effect of framework type on the survival probability of temporary implant-supported crowns and on the implant platform structure after dynamic fatigue. MATERIAL AND METHODS: Thirty (30) external hexagon implants (3.75 x 10 mm) were embedded in acrylic resin following the ISO-14801. Standardized temporary crowns (n=10, N=30) were manufactured in acrylic resin and divided according to the framework type: Total plastic, Plastic with CoCr base and Titanium. The crowns were installed onto the implants (20N.cm) and fatigued (100N, 2 Hz) to determine the crowns' survival probability for missions of 300.000 and 600.000 cycles. Fatigue data were submitted to the Kaplan-Meier test followed by Wilcoxon and Log Rank, all with α = 5%. The implant platforms were parametrically inspected based on the scanning before and after the fatigue to evaluate the damage. The strain values were analyzed using One-way ANOVA and Tukey test, all with α = 5%. RESULTS: ANOVA revealed that the Total plastic showed less implant damage (-0.07 ± -0.03 mm) than the Plastic with CoCr base (-0.08 ± -0.04 mm) and the Titanium (-0.10 ± -0.01 mm) frameworks. Therefore, the framework type to manufacture implant-supported temporary crowns influences the fatigue survival of the restoration and the implant platform damage. The Plastic with CoCr base and Titanium frameworks showed superior reliability than the Total plastic framework which could not survive 600,000 cycles. CONCLUSIONS: The Plastic with CoCr base and the Titanium framework are suitable for restorations over 3 months in use, without a difference in the implant platform damage. Key words:Implant dentistry, axial loading, occlusion, methodo-logical study.

The correlation of research diagnostic criteria for temporomandibular disorders and magnetic resonance imaging: a study of diagnostic accuracy.

OBJECTIVE: The aim of this study was to evaluate the performance of research diagnostic criteria for temporomandibular disorders (RDC/TMD) as a diagnostic test for temporomandibular joint problems using magnetic resonance imaging (MRI) as the gold standard. STUDY DESIGN: Sixty-seven women were assessed with RDC/TMD (2 examiners) and underwent MRI examination (3.0 T). Images were evaluated by 2 independent radiologists blinded to the clinical diagnoses. Results were analyzed by the Catmaker system. RESULTS: Of the 67 patients, 44 were diagnosed with temporomandibular disorders (TMD) according to RDC/TMD, but 21 (32%) of the diagnoses were not confirmed by MRI. The RDC/TMD sensitivity was 83.0%, specificity was 53.0%, and the positive likelihood ratio was 1.77, whereas the negative likelihood ratio was 0.32 (P = 0.16). CONCLUSIONS: Our data suggest that RDC/TMD is a good research tool, but the high rate of false-positive results limits its use in clinical practice.

Estudo comparativo entre um novo método de transferência de planos guias no preparo de boca para Próteses Parciais Removíveis e outras duas técnicas / Comparative study between a new method for tranferring guide planes on mouth preparation for Removable Partial Denture and two other techniques

A confecção de uma prótese parcial removível exige a correta determinação do eixode inserção e, consequentemente, o preparo cuidadoso de planos guias parasatisfazer os princípios de retenção e estabilidade. Entretanto, grande parte dosprofissionais negligencia esta etapa, seja por desconhecimento de sua importância,dificuldade técnica, quantidade limitada de opções cientificamente comprovadas deseus resultados, ou pela aparente e ilusória economia de tempo e de trabalho quesua realização possa tomar. Então, em função do número limitado de técnicaseficientes para transferência de planos guias e da necessidade de um método queotimize o tempo dos profissionais de forma prática e didática, o presente estudobuscou introduzir uma nova maneira de transferir os planos guias. A nova técnicaconsiste na utilização de uma placa de vacuum-form (PV), comparando-a compreparos realizados em delineador e com duas outras técnicas pré-existentes: à mãolivre (ML) e coroas-guia (CG), analisando sua eficácia e precisão. Réplicas idênticas(n=44) de um modelo de gesso representativo da arcada inferior foram divididas em11 grupos, com 4 modelos cada. Cada um dos onze estudantes de Odontologiarecebeu 4 modelos - em um deles os planos guias já tinham sido previamentepreparados com delineador, os quais serviram apenas de referência para quefossem empregados os outros métodos. As diferenças angulares dos planos guiasnos 44 modelos, nos sentidos ântero-posterior, látero-Iateral e cruzado forammensuradas por meio de uma máquina de medição por coordenadas. A análise devariância para medidas repetidas e o Teste de Comparações Múltiplas (método deTukey) revelaram que tanto no sentido látero-Iateral, como na avaliação cruzada,houve diferença significativa na média dos preparos feitos no delineador em relaçãoa todas as outras técnicas. No entanto, não foram identificadas diferenças

The confection of a removable partial denture requires accurate determination of thepath of insertion and consequently, the carefuI preparation of guide planes to meetthe principies of retention and stability. However, a great number of professionalsneglect this step because of unconsciousness of its importance, or technical difficulty,ar limited options of techniques or because of apparent and illusory saving of timeand work. Due to the limited number of proven effective techniques for guide planespreparation and the need of an effective method for optimizing time of dentalsurgeons in a clear and practical way, this present study aimed the introduction of anew technique for transferring guide planes. The new technique consists on the useaf a vacuum form splint (VF). To measure its efficiency and accuracy it wascampared with the preparations carried out in a dental surveyor and with two otherpre-existing techniques: freehand (FH) and acrylic resin guide crown (GC). Identicalreplicas (n=44) of a gypsum model representing a dentallower arch were divided into11 groups of four. Each of the eleven dental students received four models - in one ofthe models, the guide planes were previously prepared with the surveyor to be usedas a reference for the application of the three transfer techniques in the other threeremaining models. The angular differences of the the prepared guide planes on the44 models were measured by a coordinate measuring machine in theanteroposterior, laterolateral and crossed views. The Analysis of Variance and Tukeymethod revealed that, for the laterolateral evaluation and crossed evaluation,significant differences were found in the average of the preparations obtained by thesurveyor in relation to ali other techniques. There were no significant differencesamong the three techniques. Anteroposterior evaluation showed significant differencebetween the average of the preparations

Utilização de overlay removível como meio de determinação da dimensão vertical de oclusão na reabilitacão oral / Removable overlay utilization as a means of determining the vertical occlusion dimension for oral rehabilitation

O bruxismo é uma parafunção que acomete o sistema estomatognático trazendo consequências severas na postura, função mastigatória e estética dental. As primeiras teorias relacionavam o bruxismo às interferências oclusais e aos contatos prematuros. Estudos mais recentes sugerem que fatores psicossociais, distúrbios do sono, uso crônico de drogas de ação central, desarmonias oclusais e distúrbios na via neuronal dopaminérgica possam estar relacionados à etiologia dessa parafunção. A perda da dimensão vertical de oclusão (OVOl, uma das consequências do bruxismo devido aos desgastes dentais excessivos, pode ser restabelecida por várias técnicas. Entretanto, a adaptação a uma nova condição funcional deve ser observada com critério, utilizando-se provisórios como protótipos funcionais, fundamentais ao sucesso da posterior reabilitação protética. Este relato de caso clínico descreve o tratamento de um paciente bruxômano, com perda de OVO, que foi reabilitado por meio de overlay removível provisória para posteriormente receber, em caráter definitivo, uma prótese removível conjugada com prótese fixa.

Bruxism is a parafunction that affects the stomatognathic system. Bruxism brings severe consequences on the posture, masticatory functionality and dental esthetics. The first theories refer bruxism with occlusal interferences and premature contacts. Recent studies suggest that factors such as: psychosocial, sleeping disorders, abusive drugs utilization for central action, oc- clusal disharmonies and disorders in the dopominergic neuronal via, are commonly considered in its genesis. The OVO reestablishment due to excessive dental stress can be obtained through many techniques. However the adaptation to a new functional condition shall be carefully observed. The utilization of provisory such as functional prototypes is fundamental for the pros- thetic rehabilitation success. This clinical report describes a treatment in a patient with bruxism. This patient had vertical dimension perception loss. He was rehabilitated through a provisory and removable overlay and right after, through a combination of a partial removable prosthesis a nd a fixed prosthesis.