Acid Microfiltration in Resins Comparing Adhesives With or Without Chlorhexidine

Objectives: To determine the degree of acid filtration in Class I cavities with resin-based restorations based on different types of adhesives.
Methods: 16 premolars extracted for dental reasons were used. These were conserved hydrated in artificial saliva until use. The teeth were divided into two groups. Cavities were made in the occlusal face with standardized dimensions (2 mm deep, 3 mm wide and 4 mm long). All preparations were made by the same operator. A different adhesive resin was randomly assigned each group. The adhesive Peak-Universal-Bond with chlorhexidine, was used in Group 1, and PQ1 adhesive without chlorhexidine in Group 2. Both groups were obturated with a standard technique (cavity cleansing, a dental etchant, Ultra-Tech), adhesive (depending on the group), and resin (Amelogen Plus). The radicular portion of all the teeth was sealed with acrylic resin. Both groups were placed in artificial saliva with sacarose 5% and inoculated with Streptococcus mutans-UA159. They were later incubated for 5 days at 37 °C in which the pH was measured daily. After incubation, the teeth were washed with sterile bidistilled water and placed in methylene blue stain 1% for 3 days. Acid filtration was evaluated in teeth sections with a stereomicroscope.
Results: According to the chi-square and t-Student test analysis, there is no significant difference between the two treatments; however, in some samples, treatment with chlorhexidine has a greater degree of filtration. Most cases with chlorhexidine have grade 3 filtrations, although there was some variation in the degree of filtration in the samples. In half the samples without chlorhexidine, filtration was not seen but in those with filtration, it was grade 2 or 3.
Conclusions: There was no significant difference between the resins (p≥0.05); however, a slight tendency in favor of resins without chlorhexidine with a pH 5 at 6 days was generated by S. mutans.