INTRODUCTION: Chlorhexidine (CHX) is the most popular and effective disinfectant used in modern dentistry. CHX prevents the adherence of the pellicle to the tooth surface and therefore diminish the formation of plaque, has strong bactericidal and bacteriostatic effect, widely used pre- and post-operatively, in elderly patients, as well as mentally or cognitively challenged patients and immunocompromised patients. One of the side effects of CHX is extrinsic brown coloration of teeth after long-term use. There were many methods proposed to reduce this aesthetic concern, including “chilling” of the solution. The aim of the study is to test the hypothesis that at lower temperatures, 0.12% Chlorhexidine oral rinse solution will reduce the extrinsic staining of teeth.

METHODS: Non-molar extracted teeth collected at Colorado University School of Dental Medicine’s Surgery Department were apicocoronally sectioned and randomly assigned to five different groups based on the temperature of the 0.12% CHX solution that will be used to rinse them: common refrigerator solution (4 degrees Celsius), room temperature (25 degrees Celsius); body temperature (37 degrees Celsius), warm temperature (50 degrees Celsius) and control group with no CHX rinse used. All teeth were kept in standardized mix of human saliva-tea mix. Experimental teeth were rinsed twice a day for 1 minute in aforementioned CHX solutions for twenty-one days to simulate the time usually used for post-operative care/home use. Photographs were taken using binocular scope and analyzed in grey scale using Image-J software (NIH) in standardized environment. T-test for the feasibility study was performed to calculate the p-value. ANOVA Two-Factor with Replication and a Paired two sample T-Test to determine the statistical significance of the difference between mean values of day 0 and day 18 of the samples.

RESULTS: The analysis of variance among groups and days showed that there was a statistically significant change within groups one and two, which pertained to 25 degrees Celsius and 4 degrees Celsius respectively at p < 0.0010 and p < 0.0002. Group 1 (25 °C) demonstrated a 19.87%, change and Group 2 (4 °C) demonstrated a 19.30% change. Group 4 (50 °C), which also had a significant change in darkness, did not present with a statistically significant change. Group 5, which was the control at room temperature, underwent a 10.63% change in darkness with a p value of 0.0864. Although there was significant difference between groups (p < 0.00026) and days (< 0.000146), ANOVA test did not find significant differences due to interactions between Groups and Days. All teeth stained regardless of pretreatment shade.

CONCLUSIONS: The design of the study proved to be effective in demonstrating staining effect and can be used in the future models. Although the study was able to confirm results of previous studies regarding the potentiating effects on staining of teeth by CHX in the presence of chromogens, the study failed to show statistically significant change in staining based on temperature differences.