Abstract
Purpose: Resin facing crowns are frequently used clinically as aesthetic restorations. Improvement of the adhesion between prosthetic composite resin and the dental alloy decreased the debonding of the resin from the metal frame. However, shade or luster of the resin surface change gradually over a long time, resulting in poor appearance. Although it is easily expected that thermo-cycle testing should affect the surface texture of prosthetic composite resin, details have never been clarified. The purpose of this investigatixon was to clarify the effects of thermo-cycle testing on surface texture of prosthetic composite resin.
Methods: Square (8×8×1.5mm) specimens were fabricated by 4 photo-curing prosthetic composite resin. The measuring surface was polished according to the clinical procedure. Surface textures before and after thermo-cycle testing (4°C60°C) were investigated by macroscopic observation, pigment penetration test, measurement of surface roughness and scanning electron microscopic (SEM) observation of the microstructure.
Results: Macroscopic observation revealed a rough mat surface, and the pigment penetrations were increased on the thermo-cycled specimens. Surface roughness of the thermo-cycled specimens was increased as compared with that of the non-thermo-cycled specimens. Furthermore, SEM observation demonstrated cracking and partial peeling of the thermo-cycled resin surface.
Conclusions: Since thermo-cycle stress causes various changes to the surface texture of the prosthetic composite resin, it is an important factor, which deteriorates the aesthetic quality.
