Er:YAG Laser to Control Erosion Associated with Abrasion on Enamel

Method: Bovine incisors were sectioned, flattened and polished. To make a standardization sample, surface microhardness was assessed. To create a reference area, a part of the surface of the selected specimens was isolated (5x1.5mm). Forty-eight enamel slabs were submitted to the initial erosive challenge (1% citric acid, pH=2.3, 5 minutes, 2x/day, for 2 days). Specimens with pre-formed lesions were divided into two groups according to the surface treatment (I. irradiated or II. non-irradiated with Er:YAG laser - 5.2J/cm², 85mJ, 2Hz). After the surface treatments, 12 volunteers wore an intraoral palatal appliance containing four slabs, in one phase of 5 days. During the intraoral phase, in a split-mouth design, the volunteers performed erosive wear with citric acid on one side of the palatal appliance and erosion associated with abrasion on the other side, 3x/day for 4 days. The challenges began only on the second day of use the device to allow formation of acquired pellicle. Finished the in situ phase, the enamel structure loss was determined by an optical 3D profilometer after: initial erosive lesion formation, surface treatment and intraoral phase. Data was analyzed using the Kruskal-Wallis test. Multiple comparisons were performed using the Mann-Whitney test.

Result: After erosive and abrasive challenges, the group irradiated with Er:YAG laser (33.10±9.20) presented significantly lower enamel structure loss when compared with the group that was non-irradiated (37.36±10.60). The group that was eroded and irradiated (34.22±11.04), did not differ significantly from the eroded and non-irradiated group (31.69±10.68).

Conclusion: Thus, it can be concluded that irradiation with Er:YAG laser, controlled the structure loss of enamel submitted to abrasive processes after erosion.