Caries resistance of lased human enamel with Er:YAG laser – morphological and ratio Ca/P analysis

Abstract

Abstract:Objective: "In vitro" analysis of caries resistance of dental enamel under caries simulation after irradiation with Er:YAG laser. Background Data: More susceptible to caries development spots at adjacent hard tissues from cavity preparations of dental tissues using burrs or lasers are quite common. Methods: Thirteen caries-free third permanent human molars were distributed as follows: G1: sound control and caries control; G2: Er:YAG 100, 200, 300, or 400 mJ/ 10 Hz/ 3 sec.; G3: the same parameters of G2 followed by artificial caries simulation, through dynamic model of demineralization and remineralization (DE/RE). Caries resistance analysis was evaluated through scanning electron microscopy (SEM) and Ca/P rate (X-Rays spectroscopy -EDX). Results: Photomicrographs showed that the Er:YAG laser created craters with rough aspect which became more evident as the energy per pulse was increased, but without change of regular morphology of enamel prisms. Significant statistical changes among the irradiated and control groups was observed considering the Ca/P ratio. Conclusion: Irradiated groups showed higher caries resistance than control groups. However, it is not possible to affirm that the enamel surface accidental irradiation could be a benefit to caries resistance for other situations can be considered, as biofilm deposit, which could increase the caries susceptibility.Image from G1 group (control + caries) under 1000× magnification

Dental Enamel Irradiated with Infrared Diode Laser and Photo-Absorbing Cream: Part 2—EDX Study

“…In agreement with previous studies with Er:YAG laser, 44 all groups showed negative balance with the Ca=P ratio ( Table 6, Fig. 5), with the Ca=P ratio being reduced after the …”

“…The reduced acid solubility of dental enamel after irradiation with high-intensity lasers has been well documented in literature, 4,[20][21][22][42][43][44][45][46][47] and this change is related to the physical and chemical alterations caused by photothermal and photochemical effects. 46 It is well known that intrinsic factors of the laser source (wavelength, emission mode, pulse energy, spot size, pulse duration, and application method on the tissue) and external parameters (energy density and time exposition) are relevant to understanding the mechanism of interaction between the laser and biological tissue.…”

Morphological and Structural Changes on Human Dental Enamel After Er:YAG Laser Irradiation: AFM, SEM, and EDS Evaluation

“…It has been reported [4][5][6][7][8][9][10][11][12][13][14] that Er:YAG laser irradiation induces morphological changes in the enamel that include the formation of rough surfaces, cracks, and craters, which seem to be more prone to bacterial accumulation. Such morphological changes create favorable conditions for the development of carious lesions.…”

“…Moreover, in hard-tissue procedures, the water vapor production induces an increase of the internal pressure within the tissue, resulting in an explosive expansion called a ''microexplosion'' 2,3 that produces changes in the morphology of the enamel, [4][5][6][7][8] including undesirable effects that have been described as craters and cracks. [9][10][11][12][13][14] Furthermore, the results in the available literature regarding subablative Er:YAG laser irradiation as a method to increase enamel acid resistance for caries prevention have been contradictory. 15,16 One previous study evaluated enamel morphological changes and acid resistance after subablative Er:YAG laser irradiation.…”

“…Regarding enamel structural changes associated with Er:YAG laser irradiation, alterations to apatitic inorganic component of tooth enamel, 22 as well as differences in the calcium/phosphorus (Ca/P) ratio, 13 and significant laserinduced reduction of carbonate and modification of organic material content, have been reported. 23 Therefore, the aim of the present study was to evaluate, using AFM and SEM, the morphological changes of the enamel surface after irradiation with the Er:YAG laser, and the structural changes through the weight percentages (wt%) of Ca, P, oxygen (O) and chlorine (Cl) in the resulting craters and periphery area with energy dispersive X-ray spectroscopy (EDS).…”