Title: Effects of CO2 Laser and Fluoride Treatment on Enamel Hardness

Authors:

Jayapriyaa Shanmugham, Boston University
Hammam Bahammam (Presenter)
Boston University

Yuwei Fan, Boston University
Jeonghoon Kim, Boston University
Dan Nathanson, Boston University
Athanasios Zavras, Boston University

Abstract:

Objectives: To evaluate effects of CO2 laser with and without fluoride on enamel hardness (EH) in permanent teeth. Effect of demineralization on treated and untreated teeth was also analyzed.

Methods: Extracted human permanent molars (n = 60) without any decay were selected for this in-vitro study and randomly assigned to seven groups that included treatment with 1) CO2 laser (LightScalpel LS-1005) at 2 and 4 watts 2) with 5% sodium fluoride varnish, and varying sequential combinations of the two. Knoop hardness test was conducted with a microhardness tester (Buhler Micromet 2003) to measure EH at baseline, post-treatment, and following demineralization. Demineralization was achieved by placing the teeth in Coke for 30 minutes. Differences in EH values within treatment and between treatment measurements were evaluated using non-parametric univariate analyses.

Results: When comparing within each group between baseline and post-treatment, laser at 2 watts significantly increased the EH when used alone (p-value = 0.04) or followed by fluoride (p-value = 0.04). After demineralization, the group treated with fluoride first then laser at 4 watts showed the least EH reduction (p-value = 0.04). When evaluating between groups, all of the treated teeth showed a significant increase in EH when compared to untreated teeth (p-value = 0.0001); particularly the teeth treated with laser at 2 watts showed the highest increase in EH. Furthermore, laser 2 watts alone (p-value = 0.04) or followed by fluoride (p-value = 0.04) significantly increased the EH compared to the group with fluoride before laser at 2 watts. In demineralization process, teeth treated with fluoride alone showed the highest hardness loss.

Conclusions: CO2 laser treatment can be beneficial in increasing enamel hardness when used in conjunction with fluoride. In particular we observed that laser at 2 watts followed by fluoride was most effective and can be useful in preventing decay.