Effect of Diode Laser-Irradiation Through Topically Applied Fluoride on Masking White Spot Lesions of Enamel
MetadataShow full item record
Objectives: This study aims to evaluate the effectiveness of diode laser-irradiation at different settings in conjunction with topical fluoride application in increasing the hardness of demineralized bovine enamel, and to evaluate the esthetic improvement of the white spot lesions (WSL) using a visual analog scale (VAS) and spectrophotometer measurements. Also, to evaluate the changes in the intra-pulpal temperature of the bovine teeth when exposed to the same settings of the laser groups. Material and Methods: For this study, 120 sound bovine incisor teeth were obtained and embedded in a chemical-cure acrylic resin. A 4X4 mm artificial WSL were created in the enamel surface using an acidic buffer. The teeth were randomly assigned to 8 groups (n=15) as the following: C (control group), F (fluoride only), LF1 (15s 2W laser + fluoride), LF2 (30s 2W laser + fluoride), LF3 (60s 2W laser + fluoride), LF4 (15s 5W laser + fluoride), LF5 (30s 5W laser + fluoride), LF6 (60s 5W laser + fluoride). Vicker’s hardness number (VHN) was measured at three stages, baseline, after demineralization and after treatment. For the color changes, L*a*b values were recorded at the three stages of the experiment using a spectrophotometer, also E values of the baseline and after-treatment were calculated. To evaluate the esthetic improvement of WSL after treatment, five raters evaluated the photographs of five specimens of each group using a 100-millimeter visual analog scale; the photographs were taken at the three stages of the experiment and presented together. For the intra-pulpal temperature change assessments, 30 bovine teeth were assigned to 6 groups (n=5) to receive the same dose of laser-irradiation of the laser groups LF1-6. Temperature changes were recorded by a thermometer connected to the pulp chamber of the teeth. Statistical analysis was performed using SPSS Statistics 24 (IBM SPSS, Armonk, NY). To evaluate the influence of the different fluoride and laser applications on micro-hardness of enamel, intra pulpal temperature changes, VAS rating and ?E values of esthetic improvement, a one-way ANOVAs were performed. To assess the effects of power and the duration of laser application on micro-hardness of enamel and intra pulpal temperature changes of the laser groups, two-way ANOVAs were performed. Tukey multiple comparison tests were used to determine specific group differences. The level of significance was set at = 0.05 for all tests. Results: There was a significant difference in mean VHN between the experimental groups, F group mean was significantly higher than for group C and significantly lower than the other laser groups LF 1-6 (P<0.05). LF1 group showed a significantly lower mean VHN than LF4 and LF5 (P<0.05). No significant mean VHN differences between LF1, LF2 and LF3 were found. Results also showed a significantly higher mean VAS for the treatment groups (P<0.05) when compared with the control group. However, the mean VAS rating for group F was significantly higher than group C and significantly lower than the other laser groups LF 1-6 (P<0.05), and there were no significant differences between the laser groups (LF1-6). For the spectrophotometer measurements, results indicated a significant difference in mean E by experimental groups, and revealed significantly lower mean E for F group when compared with the other groups (P<0.05). There were no significant differences in mean E values between the control and laser groups. Thermometer results showed significantly higher mean intra-pulpal temperature change for LF4-6 when compared with the groups LF1-3 (P<0.05). No significant mean changes were detected between the groups LF1-3. Conclusions: In this study, diode laser-irradiation in conjunction with topical fluoride application significantly increased the hardness of demineralized bovine enamel when compared to control and fluoride groups. The combination of diode laser-irradiation and topical fluoride application also significantly improved the esthetic appearance of WSL when compared to control and fluoride groups. There were no significant differences in the esthetic improvement between the laser groups at 2W or 5W and for 15, 30 or 60 seconds. However, diode laser application at 5W can significantly increase the intra-pulpal temperature beyond the safe limits which makes using diode laser at 2W setting more favorable and safe for a duration of 15 to 60 seconds. Further studies are needed to investigate the effect of diode laser on human teeth and the possible changes in the enamel structure and morphology.