Shade determination for restorations has always been a challenging aspect of esthetic dentistry. This in- vitro study compared the shade matching abilities of an intra-oral spectrophotometer and the conventional visual method using two shade guides. Results revealed that visual method had greater accuracy than the spectrophotometer. The spectrophotometer, however exhibited significantly better inter rater agreement as compared to the visual method. Comparison between visual and instrumental methods revealed the pros and cons of both methods. While the spectrophotometric system does not solve...

Polyvinylsiloxane (PVS) are increasingly being used in dental laboratories for duplicating casts. A serious problem with the use of PVS material is their low surface energy which renders them difficult to wet with gypsum slurries. Laboratory applied surfactants are effective in reducing the hydrophobic nature of elastomers and increase the probability of obtaining a void free gypsum cast.But their influence on hardness has not been extensively studied. With the above background this study was undertaken to investigate the changes in the surface hardness of a two type of dental stone and an...