Variation in the Pattern of Acid Etching of Human Dental Enamel Examined by Scanning Electron Microscopy

Abstract

This study has shown that the exposure of human dental enamel to acid solutions in vitro produces three basic etching patterns. In the most common, called type 1 etching pattern, prism core material was preferentially removed leaving the prism peripheres relatively intact. In the second, type 2 etching pattern, the reverse pattern was observed. The peripheral regions of prisms were removed preferentially, leaving prism cores remaining relatively unaffected. In the type 3 etching pattern, there was a more random pattern, areas of which corresponded to types 1 and 2 damage together with regions in which the pattern of etching could not be related to prism morphology. These findings differ from previous studies in which the type 1 pattern was ascribed to acid action and type 2 etching pattern to attack by chelators. The results therefore suggest that there is no one specific etching pattern produced in human dental enamel by the action of acid solutions. Such differences produced by acids are difficult to explain on the basis of variation in chemical composition, and crystallite orientation. This further highlights the variation in structure that can occur in enamel not only from tooth to tooth, or surface to surface, but also from site to site on a single tooth surface.

Consequences of enamel preparation with sodium hypochlorite, polyacrylic and phosphoric acids for the bonding of brackets with resin-modified glass ionomer cements

“…A larger number of type 1 and 2 decalcification patterns were observed, whereas a predominance of type 3 patterns was noted in the absence of NaOCl. When assessing enamel micromorphology, Silverstone 16 noted a higher degree of retention for type 1 and 2 decalcification patterns than for type 3. The topographic quality of the conditioning cannot be clinically observed.…”

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

“…Acid etching of enamel appears to improve reten-tion by selectively eroding certain hydroxyapatite formations and facilitating penetration by the development of resin tags. 2,3 Development of these micromechanical bonds contributes to long-term bonding strength.…”

Influence of dentin and enamel pretreatment with acidic sulfur compounds on adhesive performance

“…The untreated specimen showed smear-layer-coated surfaces with distinct polishing patterns on the dentin and enamel (corresponding to the groups E4, E6 and D4, D6 respectively). On enamel, specimens revealed predominantly a type 2 etching pattern where the prism core material was preferentially left intact and the prism peripherals were removed (corresponding to the groups E1, E2, E3 and E5) [21]. On dentin, etching with phosphoric acid alone (D3) or etching with ASC followed by etching with phosphoric acid (D1) led to dissolution of the smear layer and opening of the dentinal tubules.…”