JNPS 2019, Volume 2, Number 2 (July - Dec)
Comparison on the Transverse Strength of Heat Cure Polymethylmethacrylate Denture Base Resin Repaired with Different Surface Treatments and Surface Design Modifications (78 - 85)
Introduction: Fracture of denture being most common clinical complain in daily Prosthodonticpractice, results in great inconvenience to patient and humiliation to Prosthodontist. A satisfactoryrepair should be cost-effective, simple to perform, match the original color and not cause distortion tothe existing denture.
Objective: The aim of the present study is to investigate the effect of different surface treatments andsurface design modifications on the transverse strength of repaired heat cure polymethylmethacrylatedenture base resin.
Materials and Methods: A total of 135 rectangular specimens measuring 65 x 10 x 2.5 mm weremade from heat cure PMMA resin using standardized mould. They were further divided into following5 groups with 27 specimens in each group with simple random sampling method. Group A: control,Group B: 45° bevel of the edge, Group C: rounded contour of the edge, Group D: dichloromethaneapplication at the edge and Group E: sandblasting of the edge. The repair index was fabricated withpoly vinyl siloxane (putty). The specimens in each sample group were sectioned in the center to form 2parts with approximately 3mm gap in between them. The sectioned surface of each sample group wasmodified according to their group specification and repaired using autopolymerizing acrylic resin. Allthe repaired specimens were tested for transverse strength in universal testing machine by subjectingthem to 3-point bend test and the value at which the fracture of specimen occurred were noted. Datawere analyzed with one-way ANOVA for multiple group comparisons followed by Tukey post hoc forgroup comparison (p<0.05).
Results: Transverse strength of original specimen was higher than that of repaired specimen. Transversestrength of specimen repaired with surface design modification with rounded contour of the edge washigher than chemical and mechanical treatment and 45bevel of the edge.
Conclusion: Within the limits of the study, irrespective of the method of repair, the transverse strengthof surface design modification with rounded contour of the edges was significantly higher than thegroup repaired with surface design modification 45 bevel of the edge, chemical treatment withdichloromethane application at the edge and mechanical treatment by sandblasting of the edge.
Key words: Acrylic resin; Joint contours; Dichloromethane; Sandblasting; Repair; Transverse strength
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