To Evaluate the Effect of Water Temperature and Duration of Immersion on the Marginal Accuracy and Microhardness of Provisional Restoration: An In Vitro Study

Abstract

Introduction Provisional restoration is a critical component of fixed prosthodontics treatment, which must satisfy many inter-relative factors such as biological, mechanical, and esthetic. These restorations should have accurate marginal adaptation and optimum strength to maintain functional demands. The present “in vitro” study was conducted to evaluate the effect of water temperature and duration of immersion, on the marginal adaptation and microhardness of four different commercially available provisional restorative materials. Materials and Methods The 240 specimens were then seated on the stainless-steel die which simulated the prepared tooth, and evaluated for the marginal gap for four different provisional restorative materials and divided into four different groups A, B, C, and D. Each group was further divided into six subgroups according to temperature of water and time of immersion. In each group the samples were immersed in water at 20, 30, and 40 degrees, respectively for 5 and 10-minutes duration. Four different temporary restorative materials for crown fabrication were loaded each time to make temporary crowns. Results Each sample was placed under travelling stereoscopic microscope (20× magnification) and photographed. Results for each surface were obtained, and the average of three surfaces was calculated. Knoop hardness was measured using a microhardness tester. The study was subjected to statistical analysis, to know the statistical significance, of the effect of difference in time and temperature changes at the time of final polymerization on surface microhardness and marginal integrity of four different provisional restorative materials. Discussion The mean marginal discrepancies of bis-GMA (group B) at 20, 30, and 40°C for 5 and 10 minutes in water were smaller than the results of other groups. Microhardness evaluation showed that the poly ethyl methacrylate (PEMA) type resin exhibited significantly lower microhardness than the bis-acryl resin composites (Protemp 4 and Systemp.c&b) at both time and temperature intervals. Conclusion The bis-acryl composites material has the least marginal discrepancy in comparison with PEMA and polymethyl methacrylate (PMMA). The bis-acryl composites materials exhibit superior surface microhardness followed by PEMA and PMMA.

Marginal and internal fit and fracture resistance of three‐unit provisional restorations fabricated by additive, subtractive, and conventional methods

“…Marginal fit depends on a number of factors, such as the tooth preparation design, method of measurement, impression technique, materials used, and thermomechanical aging (Angwarawong et al, 2020 ; Nawafleh et al, 2013 ; Ryu et al, 2020 ; Verma et al, 2020 ; Wu et al, 2021 ). It should be noted that in the fabrication of multiunit provisional FPDs, the marginal discrepancy is greater than that of single‐unit crowns due to polymerization shrinkage occurring at the pontic region (Balkenhol et al, 2008 ).…”

Effect of thermo-cycling on microhardness of CAD-CAM provisional materials

“…Digholkar et al [28] evaluated and compared the flexural strength and microhardness of provisional restorative materials fabricated utilizing rapid prototyping (RP), CAD-CAM and conventional method and reported a hardness value of 25.6 KHN (knoop hardness number) for CAD-CAM resin group. Verma et al [29] investigated the effect of water temperature and duration of immersion, on the marginal adaptation and microhardness of four different commercially available provisional restorative materials and concluded that the bisacryl composite materials exhibit superior surface microhardness. Diaz-Arnold et al [30] stated that bis-acryl composite resin materials exhibited superior microhardness over the traditional methyl methacrylate resins.…”