An ultrastructural study of the application of dentine adhesives to acid-conditioned sclerotic dentine

Morphological categorization of acid-base resistant zones with self-etching primer adhesive systems

“…Reports on hybrid layer thickness varied, with values ranging from less than 1 µm to approximately 13 µm in sound dentin 9,[19][20][21] . Lower values were reported for sclerotic dentin 18) , while higher values for demineralized dentine 22,23) . Amongst the factors that affected hybrid layer formation, it seemed that the kind of adhesive system and application technique had a substantial influence on the extent and structure of the hybrid layer created.…”

“…Hybrid layer formation enhances resin-dentin adhesion, and good interfacial bonding is a decidedly important factor to delivering an optimal long-term clinical outcome for dental restorations. For this reason, numerous studies have employed electron microscopy tools, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), to gain more insight into the morphological and mechanical characteristics of the resin-dentin interdiffusion zone: extent and uniformity of adhesive resin penetration into tooth substrates, appearance, length, and continuity of resin tags, quality of hybridization within the interdiffusion zone, and thickness of the hybrid layer [9][10][11][12][13][14][15][16][17][18][19][20][21] . Reports on hybrid layer thickness varied, with values ranging from less than 1 µm to approximately 13 µm in sound dentin 9,[19][20][21] .…”

Bond Strength of Self-etching Adhesives Applied to Different Substrates

“…2 The bond strengths of "etch-and-rinse" adhesives and two-step self-etching adhesives have been evaluated in cases of dentinal sclerosis. [3][4][5][6] Studies have concluded that the bond strength of normal dentin is much higher than that of sclerotic dentin. Sclerotic dentin seems to restrict the action of etching acids thus, hindering demineralization and the proper formation of tags.…”

Effect of Bur Roughness on Bond to Sclerotic Dentin With Self-etch Adhesive Systems

“…3,4,6,7 The micromorphological features of this altered dentin substrate are potential obstacles to resin infiltration, which include the hypermineralized surface layer, an additional partially mineralized surface bacterial layer, and intratubular mineral casts that are comparatively more acid-resistant. 3,8,9 In vitro studies 4,7,10,11 have demonstrated that for etch-and-rinse adhesives, bond strength values in sclerotic dentin are 25%-40% lower than that achieved in sound dentin as a result of the presence of an acid-resistant hypermineralized surface layer. The causes of this mineral deposition are multifactorial, including occlusal stresses, chronic stimuli of low intensity and high frequency, and bacterial colonization.…”

“…6 Hypermineralization inside the dentinal tubules also hinders the formation of resin tags and thus promotes the formation of a thinner and less homogeneous hybrid layer. 8,9,12,13 It has been suggested 3,4,8 that removal of the upper hypermineralized surface layer by bur grinding or stronger acids offers a possible strategy with which to improve micromechanical retention in sclerotic dentin. Several researchers have investigated the effect of these approaches (ie, increasing phosphoric acid conditioning time 10,[14][15][16] and roughening the dentin surface 10,17,18 when using etch-and-rinse systems) and have obtained controversial results.…”