Accuracy of new implant impression technique using dual arch tray and bite impression coping

PURPOSE: The purpose of this in vitro study was to evaluate the accuracy of a new implant impression technique using bite impression coping and a dual arch tray. MATERIALS AND METHODS: Two implant fixtures were placed on maxillary left second premolar and first molar area in dentoform model. The model with two fixtures was used as the reference. The impression was divided into 2 groups, n=10 each. In group 1, heavy/light body silicone impression was made with pick up impression copings and open tray. In group 2, putty/light body silicone impression was made with bite impression copings and dual arch tray. The reference model and the master casts with implant scan bodies were scanned by a laboratory scanner. Surface tessellation language (STL) datasets from test groups was superimposed with STL dataset of reference model using inspection software. The three-dimensional deviation between the reference model and impression models was calculated and illustrated as a color-map. Data was analyzed by independent samples T-test of variance at α=.05. RESULTS: The mean 3D implant deviations of pick up impression group (group 1) and dual arch impression group (group 2) were 0.029 mm and 0.034 mm, respectively. The difference in 3D deviations between groups 1 and 2 was not statistically significant (P=.075). CONCLUSION: Within limitations of this study, the accuracy of implant impression using a bite impression coping and dual arch tray is comparable to that of conventional pick-up impression.

Transferência anatômico-funcional de implantes / Anatomical-functional transfer of implants

Na cavidade bucal existem estruturas rígidas (dentes) e resilientes (tecidos moles) que deverão ser reproduzidas e, infelizmente, apresentam comportamentos distintos durante o contato com os materiais de moldagem: as estruturas rígidas não sofrem deformações e poderão gerar cópias precisas; as estruturas resilientes sofrerão deformações que precisarão ser convenientemente tratadas para que a prótese não gere traumatismos para os tecidos moles. É fundamental que a transferência espacial dos implantes para o modelo de trabalho gere posicionamentos precisos para os análogos e, com isso, o técnico de laboratório tenha condições de confeccionar peças protéticas que possuam adaptação apropriada em boca. Utilizamos transferentes parafusados em técnica de transferência direta. As moldagens são realizadas em duas etapas: (I) moldagem anatômica com moldeira de estoque e utilização de materiais de moldagem de diferentes consistências, em camadas; (II) moldagem funcional realizada com moldeira individual e poliéteres ou silicones de adição com distintas fluidezes, em camadas. Após a polimerização dos materiais de moldagem, os excessos extravasados devem ser removidos e os transferentes devem ser fixados à moldeira individual de resina com acrílico de baixa contração, pela técnica do pincel. Uma vez polimerizada a resina acrílica, os transferentes devem ser desparafusados e a moldagem removida da cavidade bucal. A transferência anatômico-funcional de múltiplos implantes é fundamental para que possamos obter modelos fiéis, e sobre esses construir próteses que possuam adequada adaptação sobre os implantes e apropriado contacto com os tecidos moles, não gerando traumatismos

In the oral cavity there are ridig structures (teeth) and resilient (soft tissue) to be reproduced and that unfortunately present different behaviors during the contact of impression materials: Rigid structures do not suffer deformation and can generate accurate copies; resilient structures suffer deformations that need to be conveniently performed so that the prosthesis does not create injuries to the soft tissues. It is essential that the spatial transfer of the implants for work model manages precise positioning for analogs and therefore the lab technician is able to fabricate prosthetic piecesd that have an appropriate adaptation to mouth. We use screwed transferents on direct transfer technique. The casts are performed in two steps: (I) anatomical impression with stock tray and use of impression materials of different consistencies, in layers; (II) functional impression with individual tray and polyether or addition-cured silicones of different flows, in layers.After curing the impression materials, spilled excess should be removed and the transferents should be fixed to individual acrylic tray with low shrinkage resin, using the technique of the brush. Once polymerized acrylic resin, transferents must be unscrewed and the impression removed from the oral cavity.The anatomical and functional transfer of multiple implants is essential so that we can get models faithful and build on these prostheses that have adequate fit on the implants and proper contact with soft tissues, generating no injuries.

Precisão de duas técnicas de esplintagem com resina acrílica de transferentes para próteses sobre implantes / Accuracy of two acrylic resin splinted techniques used for multiple abutment implant impression

Dois métodos de esplintagem com resina acrílica de transferentes quadrados usados para moldagem em próteses sobre implantes foram avaliados. Dois implantes foram posicionados no centro de um bloco de poliuretano, e sobre eles foram instaladas pilares protéticos “microunit”. Dezesseis amostras foram fabricadas neste modelo, cada uma empregando dois transferentes quadrados, rigidamente conectados com resina acrílica autopolimerizável. Metade das amostras formaram o grupo 1 (n=8). Para o grupo 2 (n=8) a outra metade das amostras foi armazenada durante 24 horas. Neste grupo a esplintagem foi seccionada e os dois segmentos foram unidos novamente. Quatro extensômetros (Excel Sensores Ltda.) posicionados ao redor dos implantes registraram as deformações geradas por cada amostra. Os sinais foram amplificados e transferidos, para então serem registrados e analisados pelo software (AqDados & AqAnalysis). Para o grupo 1, as mensurações foram feitas após a polimerização do bloco de resina acrílica; para o grupo 2 foram realizadas após a nova união dos segmentos. A análise estatística foi realizada empregado-se o teste t de Student para amostras independentes (5%). Diferença significante (p <.05) foi encontrada entre as duas técnicas. Resina acrílica em monobloco (G1) produziu valores de deformação mais altos (143.25 ±53.48mμ) que a técnica com separação e união após 24 horas (G2 - 70.83 ±29.03mμ). Concluiu-se que a técnica de esplintagem de transferentes com resina acrílica seguida da separação do bloco.

Two acrylic resin splinted techniques used for direct implant impression were assessed for accuracy in a laboratory model that simulated clinical practice. Two implants were embedded in the center of a polyurethane block. Microunit abutments were placed on the implants. Sixteen samples were fabricated on this model, using two square transfer copings rigidly connected to each other with autopolymerizing acrylic resin. Half the samples formed group 1 (n=8). For group 02 (n=8) the other half were stored at ambient conditions for 24 hours; then, the acrylic resin splint was sectioned in this group, and the segments were reconnected. Strain measurements were performed by four strain gauges (Excel Sensores Ltda.) placed on the superior surface of the polyurethane block. For group 1, measurements were made after the polymerization of the acrylic resin splint; for group 2 after the segments were reconnected. Student’s t-test for independent samples, with statistical significance at 5%, was applied to analyze the data. Significant difference (p< .05) was found between the 2 techniques. The 1-piece acrylic resin splinted technique (G1) produced significantly higher strain values (143.25 ±53.48mμ) than the other technique (G2/70.83mμ ±29.03mμ). It was concluded that the acrylic resin splinted technique with separation and reconnection after 24 hours was significantly more accurate than the 1-piece acrylic resin splinted technique.

Comparative accuracy of new implant impression technique using abutments as impression copings with an angulated implant model / 대한치과보철학회지

STATEMENT OF PROBLEM: A new implant impression technique which use abutments as impression coping, and use resin cement as a splinting material was described. Accuracy of this technique was compared with conventional closed tray and resin splinted open tray technique for a 15degrees angled 3-implant model MATERIAL AND METHODS: A dental stone master model with 3 linearly positioned implant analogue and a reference framework which was passively fitted to it were fabricated. The center analogue was perpendicular to the plane of model and the outer analogues had a 15degrees angulation forward or backward. 10 closed tray impressions, 10 resin splinted open tray impressions, 10 abutment-resin framework cementation impressions and 10 abutment-metal framework cementation impressions were made with additional silicone material and poured with dental stone. A light microscope with image processing was used to record the vertical gap dimension between reference framework and analogue of duplicated cast made with each 4 impression techniques. Statistical analysis used one-way ANOVA with post-hoc tests Tukey test of .05 level of significance RESULTS: Significant difference in the vertical gap dimension was found between closed tray technique; 74.3 (+/-33.4)micrometer and resin splinted open tray technique, and two other new technique. (P>.05) Abutment-metal framework cementation technique;42.5 (+/-11.9)micrometer was significantly different from resin splinted open tray technique. (P.05) CONCLUSION: Within limitations of this study, the accuracy of implant level impressions of resin splinted open tray technique was superior to that of closed tray technique. A new technique using abutment and metal framework cementation was more accurate than resin splinted open tray technique.