Effects of Disinfection Modalities on Irreversible Hydrocolloids: A Study on 2% Glutaraldehyde Spray vs. Immersion Techniques

Background: Dental impressions are widely used in prosthodontics to capture accurate oral morphology. However, contamination with oral microorganisms poses a risk of cross-infection, necessitating effective disinfection protocols. Glutaraldehyde, a high-to-intermediate level disinfectant, is commonly used via spray or immersion methods. Objective: To compare the efficacy of 2% glutaraldehyde spray versus immersion disinfection on microbial elimination and dimensional accuracy of irreversible hydrocolloid (alginate) impressions. Methodology: A prospective comparative study was conducted at the Department of Prosthodontics, Bangladesh Medical University from January to December 2019. Three hundred maxillary alginate impressions were collected and divided into Group A (spray, n=150) and Group B (immersion, n=150). Pre- and post-disinfection microbial samples were analyzed on sheep blood and MacConkey agar. Surface details were assessed by measuring inter-point distances with a slide caliper under a dental loupe. Chi-square and unpaired t-tests were used for statistical analysis. Results: Both spray and immersion techniques achieved complete microbial elimination in all impressions post-disinfection. No growth of Acinetobacter, Pseudomonas spp., or normal salivary flora was observed. Surface detail analysis showed minimal changes in inter-point distance, with no statistically significant difference between the spray and immersion groups (p>0.05). No effects on surface change. Conclusion: Both 2% glutaraldehyde spray and immersion effectively disinfect alginate impressions without affecting dimensional accuracy, with spray disinfection offering practical advantages for routine clinical use.