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Effect of different materials, trays and procedures on the accuracy of impression techniques. A clinical-laboratory study

Grant number: 11/19314-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): April 01, 2012
Effective date (End): December 31, 2012
Field of knowledge:Health Sciences - Dentistry - Dental Clinics
Principal researcher:José Maurício dos Santos Nunes Reis
Grantee:Aion Mangino Messias
Home Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil


The success and longevity of fixed dental prostheses (FPDs) are related to an adequate and accurate marginal fit, which depends on the quality of impression technique, impression material and gypsum cast obtained. Thus, the purpose of this study is to clinically evaluate the accuracy of impression techniques for FDPs, using different materials and trays. Initially, an estimated sample of 10 patients will be selected for the pilot study. For each patient, 20 impressions from teeth 13 to 16 will be made, according to five impression techniques: (1) single-step; (2) two-step/reline - relief with PVC film; (3) two-step/reline - relief with Maxicut bur and scalpel blade; (4) two-step/reline - relief with small movement of the tray and (5) two-step/reline - without relief. Impression techniques will be made with metal stock or individual acrylic resin partial trays, using condensation-polymerized silicone (Speedex; Coltène/Whaledent Inc.) or addition-polymerized silicone (Express XT; 3M ESPE). To standardize the passive seating position of the trays during impression procedures on the oral cavity, a position guide will be fabricated in acrylic resin (Pattern Resin LS, GC America) on the surfaces of lateral incisor and second molar. Impressions will be made by a single calibrated operator and disinfected with 0.5% sodium hypochlorite for 10 minutes. After that, it will be expected 10 and 110 minutes to pouring with type IV gypsum (GC Fuji Rock EP) the condensation and addition silicone impressions, respectively. Three lateral photographs of the patient will be obtained using a tripod and a customized radiographic positioner, being the images imported into the Image Tool software (version 3.0). The total area of the buccal surface of canine-first molar region will be measured. A 4.0% coefficient of variance will be criterion for using these measurements as a standard baseline for comparison with those obtained on gypsum working casts. The gypsum casts will be photographed and analyzed using the same photograph procedures and imaging software used for the clinical images. The total mean area (mm2) value for each group will be compared with the initial area obtained from the patient's photographs. Regardless of the patient used, the results of each technique will be tabulated and grouped in a same experimental condition with the aim to compare the effect of the factors technique, material and tray on the gypsum cast reproduced dimensions.

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
AION MANGINO MESSIAS; STEPHANIA CAROLINE RODOLFO SILVA; FILIPE DE OLIVEIRA ABI-RACHED; RAPHAEL FREITAS SOUZA; JOSÉ MAURÍCIO DOS SANTOS NUNES REIS. Effect of techniques, trays and materials on accuracy of impressions clinically made. Rev. odontol. UNESP, v. 48, p. -, 2019.
RODOLFO SILVA, STEPHANIA CAROLINE; MESSIAS, AION MANGINO; ABI-RACHED, FILIPE DE OLIVEIRA; DE SOUZA, RAPHAEL FREITAS; DOS SANTOS NUNES REIS, JOSE MAURICIO. Accuracy of Gypsum Casts after Different Impression Techniques and Double Pouring. PLoS One, v. 11, n. 10 OCT 13 2016. Web of Science Citations: 0.

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