Composite filling removal with erbium:yttrium–aluminum–garnet laser: morphological analyses

Abstract

Considering the increase in esthetic restorative materials and need for improvement in unsatisfactory restoration substitution with minimal inadvertent removal of healthy tissues, this study assessed the efficacy of erbium:yttrium-aluminum-garnet (Er:YAG) laser for composite resin removal and the influence of pulse repetition rate on the morphological analyses of the cavity by scanning electron microscope. Composite resin fillings were placed in cavities (1.0 mm deep) prepared in bovine teeth, and the 75 specimens were randomly assigned to five groups according to the technique used for composite filling removal (high-speed diamond bur, group I, as a control, and Er:YAG laser, 250 mJ output energy and 80 J/cm(2) energy density, using different pulse repetition rates: group II, 2 Hz; group III, 4 Hz; group IV, 6 Hz; group V, 10 Hz). After the removal, the specimens were split in the middle, and we analyzed the surrounding and deep walls to check for the presence of restorative material. The estimation was qualitative. The surfaces were examined with a scanning electron microscope. The results revealed that the experimental groups presented bigger amounts of remaining restorative material. The scanning electron microscopy (SEM) analyses showed irregularities of the resultant cavities of the experimental groups that increased proportionally with increase in repetition rate.

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.…”

“…Furthermore, all of the irradiated samples displayed rough areas, craters, and cracks, consistent with the results of previous studies. [4][5][6][7][8][9] The use of SEM has provided relevant findings for the study of enamel morphological changes after laser irradiation. However, the addition of EDS as an analytical technique provides valuable information about the chemical changes on the irradiated enamel surface.…”

“…During irradiation, the laser's energy is absorbed selectively by water molecules and hydrous organic components of the biological tissues, which causes the evaporation of water and organic components, resulting in thermal effects caused by the heat generated by this process (called ''photothermal evaporation''). 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.…”

Analysis of enamel surface roughness after different adhesive removal techniques for orthodontic bracket debonding

“…These lines marked the area to be tested and evaluated for each tooth. The bonded teeth were then placed into distilled water at 37°C for 24 h to simulate the oral environment allowing for complete polymerization of the adhesive as previously reported [2,10,16,21,22]. Immediately after, the brackets were removed with shear force using a debonding plier [15].…”

“…Er:YAG laser increases bonding strength of sealants [21], removes resin restorations [22], debonds porcelain veneers [23], can be used in cavity preparation in enamel and dentin [24], and in fluoride absorption into enamel [25].…”