Structural and Morphological Changes in Human Dentin after Ablative and Subablative Er:YAG Laser Irradiation

Abstract

Introduction: This study investigated the influence of Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser on microhardness, chemical composition and subsurface morphology of dentin cavity walls. Methods: Forty sound human premolars were selected and randomly assigned into four groups. Class V cavities were prepared either with an Er:YAG laser (groups 1 and 2; 15 Hz, 250 mJ for enamel, 10 Hz, 200 mJ for dentin) or with a high speed handpiece (groups 3 and 4). The specimens in groups 1 and 3 served as the control, whereas those in groups 2 and 4 were exposed to subablative laser irradiation following cavity preparation (10 Hz, 50 mJ). After bisecting the specimens, one half was subjected to microhardness assessment and the other half was evaluated by SEM-EDS analysis. Results: Microhardness was significantly greater in the specimens prepared by both ablative and subablative laser irradiation (group 2) than that of the bur-prepared cavities (groups 3 and 4) (P < 0.05). The quantity of calcium ion was significantly greater in cavities prepared by the Er:YAG laser (groups 1 and 2) compared to that of the bur cavities (groups 3 and 4) (P < 0.05). Subablative irradiation improved microhardness and weight percentage of calcium ion in both laser and bur cavities, but the difference was not significant compared to that of the relevant control group (P > 0.05). Conclusion: Cavity preparation with an Er:YAG laser could be considered as an alternative to the conventional method of drilling, as it enhances the mechanical and compositional properties of lased dentin, especially when combined by subablative irradiation.

The Effect of the Bioactive Glass and the Er:YAG Laser on the Remineralization of the Affected Dentin: A Comparative In Vitro Study

“…33 In this study, the microhardness value and thus the rate of remineralization using the Erbium YAG laser in all groups were significantly higher than the control group. This result is consistent with studies by Moosavi et al 13 and Hossain et al 34 Perito et al also reported secondary caries that occurred less frequently in laser-prepared cavities compared with a bur. 35 Ana et al pointed to the increased resistance of enamel and dentin using the Erbium laser in the treatment of dental caries.…”

“…The FESEM examination showed that the partial dentinal tubule occlusion was observed with sub-mineral materials in each of the groups of bioactive glass, glass ionomer and the laser compared to the control group, in line with Saffarpour et al 19 and Moosavi et al 13 The results obtained in this study had an experimental nature, as it may be better to carry out this study on the basis of clinical design to determine whether the results of this study are in agreement with the clinic. It is recommended that a variety of different lasers and liners should be investigated on the affected dentin in future studies in order to scrutinize closely which of the cases would increase the dentin mineralization, particularly in the case of a laser whose results in this test are promising.…”

“…These changes lead to the formation of compounds with less dissolution and greater stability, which may make the exposed substrate more resistant to demineralization. 30 In this test, the subablative parameters of the Erbium YAG Laser with a power of 0.5 W and a frequency of 10 Hz were used to prevent dental caries according to Fornaini et al and Moosavi et al 13,31 The use of the laser with subablative parameters and low-level energy, relative to higher energy, could prevent microcracks and damage to surrounding tissues. 32 In a study, the subablative laser irradiation caused dense and compact regions with less open tubules due to the greater amount of tubule occlusion or recrystallization after surface heating.…”

“…12 In a study by Moosavi et al that examined the structural and morphological changes of dentin after irradiation with the Erbium YAG laser, it was found that cavity preparation by the laser increased mechanical properties and chemical compositions and improved tooth decay resistance. 13 No study has been made so far to compare the effects of bioactive glasses, glass ionomers, and lasers in order to determine which of these are more successful in the remineralization of dentin; therefore, the purpose of this study was their comparison.…”

The Effect of the Er:YAG Laser and MI Paste Plus on the Treatment of White Spot Lesions

“…Mechanisms such as connection due to melting and strength of enamel crystals, the reduction of water and enamel carbonate, an increase in hydroxyl ions, and changes in the structure of enamel proteins are theories that explain the increased resistance of teeth against acid in laser irradiation. [15][16][17] High-power lasers such as Er: YAG lasers can induce cracks in the enamel. It can also roughen the enamel surface, which can make the tooth more susceptible to decay.…”