Erosion of Sound/eroded Enamel Treated with Nd:YAG-Laser and Fluoride

Objectives: The aim of this in vitro study was to evaluate the effect of Nd:YAG laser-irradiation and/or fluoride on sound and previously eroded enamel subjected to erosive cycling.

Methods: Sixty bovine enamel blocks were subjected to short-term acidic exposure by immersion in cola drink for 6 min, resulting in surface softening without tissue loss. Than 40 sound and 40 eroded enamel blocks were randomly and equally divided into 4 groups (n=10) according to treatment: C- untreated (control); Nd- Nd:YAG laser irradiation 56.6 J/cm²; F- AmF (1% F) fluoride application; Nd + F- Nd:YAG laser irradiation and subsequent fluoride application. The Nd:YAG laser used emits pulses at 1.064 µm, with a 300 µm quartz fiber optic delivery system operating in contact mode, temporal width of 100 µs with 10 Hz repetition rate. A coal paste photosensitizer was applied before irradiation. During 1 day the erosive cycle was conducted by immersion of the blocks in cola drink for 2 min, followed by immersion in artificial saliva for 120 min. This procedure was consecutively repeated 4 times. On the 18 h left, the blocks were maintained in artificial saliva. Enamel loss was measured profilometrically after treatment and after the erosive challenge. The data were tested using two way ANOVA and Tukey’s test (p<0,05).

Results:

Enamel alteration was observed on groups Nd and Nd + F for sound and eroded enamel after initial treatments, which were significantly different from control. After erosive challenge, for both enamel conditions (sound or eroded) only fluoride treatment (F) resulted in less enamel loss compared to control group. 

Conclusions: Based on the results, Nd:YAG laser irradiation did not show preventive effect against dental erosion and independently of enamel condition (sound or eroded) fluoride still the most effective treatment for enamel prevention.