Effect Of Desensitizers On Dentin Micro-tensile Bond Strengths Of One-bottle Self-etching Adhesives

Objectives:The aim of this study evaluated the influence of two dentin desensitizers on micro-tensile bond strengths (μTBS) of two one-bottle self-etching adhesives and analyzed dentin-resin interfaces by scanning electron microscopy.Materials and Methods:Twenty seven intact, non-carious human premolars extracted for orthodontic reason were used in this study. The cusps of18teeth were cut off to expose mid-coronal dentin surfaces. The specimens were randomly divided into three groups with6teeth each. The dentin surfaces were treated with dentin desensitizers (Gluma, Heraeus, Germany; Green Or, Italmed, Italia) according to the manufactures’instructions, or not further treated as control. Subsequently6teeth from each group were divided into2subgroups. One-bottle self-etching adhesives (BeautiBond, Shofu, Japan; G-Bond, GC, Japan) were respectively applied onto the dentin surfaces according to manufacturer’ instructions before the respective restorative materials from the same manufacturer (Beautifil II, Shofu; Gradia Direct, GC) were placed with two2-mm increments, light-cured for20s each. After24h water storage, the specimens were perpendicularly sectioned through the resin-dentin interfaces with a slow-speed diamond saw (Isomet1000) under running water. The specimens were prepared into sticks with1mm2cross-sectional areas for μTBS. The μTBS tests were performed with a micro-tensile testing machine (Bisco) at a crosshead speed of1mm/min. The cross-sectional areas were measured and μTBS were calculated in Mpa. The data were analyzed with one-way ANOVA. The dentin-resin interfaces and the dentin surfaces after application of the desensitizing agents were observed by scanning electron microscope (SEM).Results:Compared with control, Green Or significantly reduced the dentin μTBS of BeautiBond and G Bond (p<0.05), but, Gluma could not (p>0.05). SEM findings revealed intimate contact at resin-dentin interfaces in groups of (control, Gluma), and gaps between dentin and adhesive layer in Green Or group. The dentin surface after application of Gluma has no obvious different with the untreated dentin surface and irregular crystal structures were seen on the Green Or treated dentin surface.Conclusions:Dentin desensitizer Gluma did not detrimentally influence the dentin bond strengths of one bottle self-etching adhesives (BeautiBond, G Bond), but, Green Or could reduce both of them remarkably.