Journal of Nepalese Prosthodontic Society



Introduction: Impression materials are used to record the anatomical topography of oral tissues.Irreversible hydrocolloid is an impression material routinely used in dentistry. However, it retainsbacteria, 2 to 3 times higher than other impression material. Spraying and immersion technique hasbeen employed for disinfection of irreversible hydrocolloid with varying degree of success. Thus theneed of impression material that has self-disinfecting capacity seems to be very important to haveinfection control in dentistry.

Methodology: This invitro study was done in two parts. Assessment of self-disinfecting capacity ofirreversible hydrocolloid impression material mixed with different concentrations of chlorhexidinesolution and dimensional stability of irreversible hydrocolloid impression material mixed with differentconcentrations of chlorhexidine solution.For assessment of self-disinfecting capacity, irreversible hydrocolloid was mixed with variousconcentrations of chlorhexidine (0.05%, 0.1%, 0.2%) and distilled water. Total 64 culture plateswere prepared, n=16 for each group of microorganisms (E. coli, S. aureus, Pseudomonas, Klebsiella).Inhibition zones were measured for each microorganism.For dimensional stability, the specimens were divided into four groups similar to specimen forself-disinfecting ability. Total 56 samples were prepared, n=14 for each group. Interpretation (IP),Mesiodistal (MD), Buccolingual (BL), Occlusogingival (OG) dimensions were measured by digitalVernier caliper.One-way analysis of variance was done for assessment of self-disinfecting capacity and for dimensionalstability. Dunnett comparison test was performed to test the significance between test and control. Pvalue was calculated under the predetermined level of significance (0.05).

Results: Zones of inhibition were observed around test specimens (groups 0.05, 0.1, 0.2), but notaround control specimen (Group d/w). There was a significant difference in the mean diameters of theinhibition zones between test groups and control which was statistically highly significant (p < 0.001).In the test for dimensional stability, no significant differences were detected among groups for all themeasured dimensions (p> 0.05).

Conclusion: Irreversible hydrocolloid impression material mixed with chlorhexidine exhibits varyingdegrees of self-disinfecting activity without influencing the dimensional stability of set material.

Key words: Irreversible hydrocolloid. Chlorhexidine, Self-disinfecting capacity, Dimensional stability.

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