Etching time and bonding of adhesive systems to dentin of primary teeth: A systematic review and meta‐analysis

Abstract

Aesthetic and conservative restorations render adhesive systems essential for Pediatric Dentistry. There are, however, no protocols firmly established by manufacturers for using it in primary teeth, as the same adhesive protocol is assigned to permanent and primary teeth, disregarding the chemical and morphological differences between these dentin substrates. 1,2 Primary dentin has a higher tubular density, with a larger diameter in peritubular and intertubular dentin and the lower mineral content, 2,3 turning this substrate more reactive to acid conditioners. 4 Therefore, an increased demineralization occurs in primary dentin, producing a thicker hybrid layer and lower bond strength values 4-6 when submitted to the same etching time used for dentin in permanent teeth. 4 The deeper demineralization of primary dentin jeopardizes the adhesion by the collapse of collagen fibrils and calcium phosphate crystal precipitation, and thus, less

Long‐term microtensile bond strength of self‐etch adhesives and influence of 7‐s phosphoric acid etching on adhesion of a 3‐step etch‐and‐rinse adhesive to the dentine of primary teeth

“…Although it has to be taken into consideration that the risk of bias of the included studies was rated high, it was shown that the instant µTBS of etch‐and‐rinse and self‐etch adhesives were not affected by shortening the etching procedure. For aged specimens evaluated in two of the included studies, reduction in etching time yielded positive results for the bond strength of etch‐and‐rinse adhesives 7 …”

“…Hashimoto et al (2000) reported that prolonged application of phosphoric acid to dentine tended to increase the thickness of the hybrid layer and to decrease the µTBS 36 . A recently published systematic review and meta‐analysis assessed the influence of shortening the primary dentine etching time on the µTBS of etch‐and‐rinse as well as self‐etch adhesives 7 . Although it has to be taken into consideration that the risk of bias of the included studies was rated high, it was shown that the instant µTBS of etch‐and‐rinse and self‐etch adhesives were not affected by shortening the etching procedure.…”

“…These micromechanical 9 and microstructural characteristics 10‐12 may influence the bond strength to primary dentine 11 and may increase its susceptibility to demineralization during phosphoric acid conditioning resulting in an increased hybrid layer thickness 13,14 . Shortening primary dentine etching time may have beneficial effects as it reduces the hybrid layer thickness 13,14 and enhances the long‐term µTBS of etch‐and‐rinse adhesives to the dentine of primary teeth 7 …”

“…[2][3][4] A systematic review revealed the lowest annual failure rates for resin composite restorations compared to amalgam, glass ionomer cements, compomer and stainless steel crowns in primary teeth, although this restorative approach is rather time-consuming and technique-sensitive. 5 Despite the high number of adhesive systems available on the market, manufacturers do not specify their application for primary teeth, 6,7 even though the dental hard tissue of primary teeth shows morphological features [8][9][10] that may influence the performance of adhesives. 11 The characteristics of primary tooth dentine are the lower mineral content compared with permanent tooth dentine, 8 a decrease in dentinal hardness and elastic modulus toward the pulp, 9 and either a reduced tubular density with a smaller diameter of dentinal tubules 12 or an increased tubular density in primary molars with a diameter of dentinal tubules similar to permanent teeth and increasing toward the pulp.…”

“…13,14 Shortening primary dentine etching time may have beneficial effects as it reduces the hybrid layer thickness 13,14 and enhances the long-term µTBS of etch-and-rinse adhesives to the dentine of primary teeth. 7 Due to the limited cooperation of children, the duration of the restorative treatment should be minimal. 5 The use of self-etch adhesives may be favorable, as renouncing the phosphoric acid etching reduces the treatment time and simplifies the bonding procedure.…”