Profilometric Evaluation of Casts Obtained from Irreversible Hydrocolloid Impressions

Objectives:  Dustless irreversible hydrocolloid (IH) is commonly used in clinical practice today. This preliminary study measured average surface roughness (Ra) of casts obtained from a dustless and regular (containing crystalline silica) IH impression materials. Methods: Six impressions were made of the maxillary anterior teeth of a subject for each IH impression material studied (A:Jeltrate Plus dustless, and B:Jeltrate) for a total of 12 impressions.  Two gypsum casts were obtained for each combination of gypsum material (1:Resin Rock, 2:Microstone, and 3:Silky) and IH. Five profilometric measurements were obtained of teeth #8 and #9 from each cast with a Pocket Surf III profilometer  (Federal Products, Co.) in an inciso-gingival path at different locations, approximately 0.5 mm apart for each tooth. Means were calculated for each IH/gypsum cast group (1A:2.10, 1B:2.19, 2A:2.20, 2B:3.15, 3A:2.12, 3B:2.38) and were analyzed with a repeated measures ANOVA (a<.05). Results: All gypsum casts produced from dustless IH impressions gave significantly (p=.044) lower average Ra than all casts produced from regular  IH impressions. Conclusion: From these preliminary results it appears that this dustless IH impression material may produce different detail reproduction than regular IH impression material. Further research is needed to determine this difference.