A Possible Mechanism of Acquired Acid Resistance of Human Dental Enamel by Laser Irradiation

Abstract

A possible mechanism of acquired acid resistance of lased enamel was proposed on the basis of the investigations of optical properties, compositional and structural changes and permeability of lased and unlased human dental enamel. Lased enamel showed a high positive birefringence, suggesting the formation of ‘microspaces’ in enamel. No new products were found, though a decrease of lattice strain and a slight a-axis contraction were recognized in lased enamel compared with unlased enamel. The contents of water, carbonate and organic substances were reduced in lased enamel. Gradual changes of birefringence were observed in lased enamel during treatment with acid solutions, and this change was attributed to mineralization of the microspaces. The ions released by an acid decalcification would be trapped in the microspaces in lased enamel, whereas such ions diffuse to the surrounding solution in unlased enamel.

An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching

“…Dentinal permeability might also be reduced as a result of sealing the dentinal tubules up to a considerable depth. [41][42][43] Such alterations in dentinal surfaces might impede the proper bonding of restorative materials and cause cohesive micro-fractures.…”

Etching Enamel for Orthodontics with an Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet Laser System

“…Acid etching results in chemical changes that may modify the organic matter and decalcify the inorganic component. 14,15 As a result of this demineralization, enamel becomes more susceptible to caries attack, which is induced by plaque accumulation around the bonded orthodontic attachments. Hossain et al 12 reported an increase in the calcium to phosphorus ratio achieved during laser irradiation, which leads to caries inhibition.…”

Shear bond strength of pit and fissure sealants on permanent teeth after several etching protocols: In vitro study

“…3 Additionally, there have been several studies in which it has been observed that enamel structure is modified, increasing the resistance against caries, due to thermally induced chemical and structural changes in the intrinsic mineral and organic matrix, as well as reduction of carbonates. [4][5][6] The aim of this in vitro study was to evaluate and compare shear bond strength of sealants prior to enamel conditioning under several etching protocols in permanent teeth.…”