Hydroxyapatite, a potent agent to reduce dentin hypersensitivity; systematic review

Objective: This study reviews different modes of application of hydroxyapatite for treatment of dentin hypersensitivity via dentinal tubule occlusion. Methods: Literature search was performed using keywords, “hydroxyapatite and dentin hypersensitivity, hydroxyapatite and dentinal tubule occlusion, hydroxyapatite and dentin permeability, dentinal tubule occlusion” on Pubmed, Science Direct and Web of Science, which involved the results of previous 10 years (2009-2018). After screening, 16 studies were included in systematic review. Results: The results of in-vitro studies showed that application of hydroxyapatite caused dentinal tubule occlusion leading to reduction in dentin permeability and reduction in dentin hypersensitivity. Conclusion: Hydroxyapatite has the potential to reduce dentin hypersensitivity via dentinal tubule occlusion within 2-8 weeks. Keywords: Dentin hypersensitivity, Hydroxyapatite, Dentinal tubule occlusion. Continuous...

Impact of Immediate Dentin Sealing Using Universal Adhesive under Simulated Pulp Pressure on Microtensile Bond Strength of Indirect Resin Composite Restorations and Dentin Permeability

Objective The aim of this study was to investigate the effect of immediate dentin sealing (IDS) technique using universal adhesive under simulated pulp pressure on microtensile bond strength (µTBS) of indirect resin composite restorations and dentin permeability. Materials and Methods Fifty extracted caries-free human third molars were used for specimens' preparation. Each molar's occlusal table was abraded flat and their roots were separated under continuous water cooling. Forty specimens were used for microtensile bond strength test (µTBST) evaluation. The µTBST specimens were randomly assigned to two groups according to the dentin sealing time; Immediate dentin sealing (IDS) and delayed dentin sealing (DDS). Each group was further subdivided into two subgroups according to the adhesive system used for dentin sealing: iBOND self-etch adhesive and GLUMA Bond Universal. All specimens were exposed to simulated pulp pressure for 1 week then restored using computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite blocks. The µTBS was evaluated for all tested subgroups after 24 hours and 6 months of water storage. The remaining 10 teeth were used for the preparation of dentin discs for dentin permeability evaluation. They were divided into two groups according to type of self-etch adhesive used. Fluid filtration rate was evaluated after etching, with smear layer and after adhesive application. Results obtained were statistically analyzed using Shapiro–Wilk test and Weibull analysis. Results Statistically significant difference was recorded between μTBS mean values of both IDS and DDS techniques at 24 hours and after 6 months of water storage. GLUMA Bond Universal adhesive had significantly higher bond strength compared with iBond at both IDS and DDS techniques, but both adhesives showed a significant reduction in the Weibull characteristic strength after 6 months of water storage. Significant reduction in dentin permeability was recorded by both adhesives without any significant difference between them. Conclusions The IDS technique using universal adhesive in self-etch mode is an effective strategy for improving the final bond strength of CAD/CAM resin composite restorations and reducing dentin permeability.

Dentin Permeability and Nanoleakage of Universal Adhesives in Etch-and-rinse vs Self-etch Modes

Clinical Relevance Universal adhesives do not seem to have the ability to effectively seal dentin, regardless of the mode of application. SUMMARY Purpose: This study evaluates the reduction in dentin permeability (P) and the expression of nanoleakage in resin-dentin interfaces made with universal adhesives, comparing the self-etch mode of application with the etch-and-rinse mode of application. Methods and Materials: To measure dentin P at the baseline and after adhesive polymerization, 80 extracted noncarious human third molars (N=80) were sectioned to obtain 0.7-mm-thick midcoronal dentin disks. The specimens were randomly assigned to 8 groups according to the different adhesive systems and application modes used: Scotchbond Universal (SBU; etch-and-rinse [ER] mode vs self-etch [SE] mode), OptiBond XTR (OPT; etch-and-rinse mode vs self-etch mode), Clearfil Universal Bond Quick (CL; etch-and-rinse mode vs self-etch mode), and Adhese Universal (ADH; etch-and-rinse mode vs self-etch mode). A two-way analysis of variance with interaction was used to evaluate the P reduction differences among the groups (α=0.05). Sixteen additional 0.7-mm-thick dentin disks were similarly prepared and treated, immersed in 50 wt% ammoniacal silver nitrate, and then processed according to conventional methods for analysis under transmission electron microscopy. Results: The differences in P reduction among the adhesives were significant (p=0.029). For OPT and ADH (p=0.0304 and p=0.0120, respectively), the P reduction was higher in the ER mode than in the SE mode. For CL and SBU, no differences in P reduction was observed between the two application modes (p>0.05). All the groups showed some pattern of nanoleakage. Conclusions: No adhesive system completely reduced dentin P. Dentin sealing was higher for OPT and ADH in the ER mode, while for SBU and CL, there was no difference between the two modes. All the adhesive systems showed nanoleakage.

Performance of a Universal Adhesive on Etched and Non-Etched Surfaces: Changes in Dentin Permeability

Hybridization process for dentin is well known, but remains a difficult challenge as it is dependent on many factors related to dentin substrate, adhesive nature including its solvent. The development of universal adhesives followed the all-in-one concept of existing one-step self-etch adhesives, thus requiring water in their formulation to ionize hydrophilic acid monomers. Most often, carboxylate and/or phosphate groups are their primary functional monomers [1]. Jee, et al. published in 2016 that ethanol molecules penetrate via increasing solvent accessible surfaces induced by the rearrangement of collagen monomers in the gap region [2]. The aim of this study is to evaluate the discrepancy in dentin permeability after application of a universal adhesive used in self-etching (SE) mode or etch and rinse (E&R) mode, by means of hydraulic conductance measurement.

Permeability of Modified Dentinal Surfaces

Objectives: The aim of this study was to investigate the sealing ability of three adhesives bonded to modified dentinal surfaces after short and long storage periods. Methods: Three adhesives were used in this study; two-step etch-and-rinse “Adper Single Bond 2”, two-step self-etch “AdheSE” and one-step self-etch “G-Bond” adhesives. Modifications of the dentinal surface was performed by application of adhesives after oxalate application, application of adhesive after oxalate application to sodium hypochlorite (NaOCl)-deproteinized dentinal surface, compared to control groups (application of adhesive without any surface pretreatment). Dentinal sealing was investigated by measuring dentin permeability, using a fluid transport apparatus, after two storage periods; 24 hours and 2 months. Results: After 24 hours, the control group bonded with “Adper Single Bond 2” without any surface treatment had the highest permeability (25.3%) followed by “G-Bond” (16.2%) and finally “AdheSE” (11%). Significant reductions in permeability values were observed on application of oxalate in conjunction with both “Adper Single Bond 2” and “AdheSE” (11.7% and 2.6% respectively). Further significant reductions in permeability values of those two adhesives were noted when the combined NaOCl and oxalate pretreatments were used (5.7% and 0.8% respectively). Permeability means for all groups increased after storage for 2 months. Conclusions: Dentin surface deproteinization plus oxalate application produced the best dentin sealing for two step adhesives. Key words: Etch-and-rinse adhesives, self-etching adhesives, oxalate-desensitizing agent, NaOCl-deproteinizing agent, dentin permeability.

Assessment of permeability of eroded dentin after the use of universal, self-etch, and conventional systems

Dentin hypersensitivity is caused by increased dentinal permeability due to total or partial exposure of dentinal tubules, which in turn can be produced by alterations of dental structures or failure of restorative procedures. The purpose of this in vitro study was to evaluate the efficacy of the application of different kinds of adhesive systems to prevent dentin permeability before and after an erosive challenge. Fifty bovine dentin discs (6x1 mm) were prepared and the specimens were divided into 5 groups (n=10): (SB2) Single Bond 2, (SBU) Universal Single Bond, (CSB) Clearfil SE Bond, (SM) Scotchbond Multipurpose and (C) Control. Hydraulic conductance of dentin was recorded after adhesive application (HC-1) and after erosive challenge (HC-2). Dentin surface images of post-treatment and post-erosive challenge were obtained by scanning electron microscopy (SEM). Data were analyzed using Kruskal Wallis, Mann-Whitney with Bonferroni correction and Wilcoxon tests (p<0.05). Reduction in dentin permeability was observed with the application of adhesive systems (p<0.05). After the erosive challenge, dentin permeability increased for SBU and CSB (p<0.05), while SB2 and SM did not differ in HC-1 or HC-2 (p>0.05). The conventional, self-etching and universal adhesive systems reduce dentinal permeability by more than 80%, and dentin demineralization may contribute to the increased permeability of universal and self-etching systems.

In Vitro Evaluation of Desensitizing Agents Containing Bioactive Scaffolds of Nanofibers on Dentin Remineralization

This study evaluated the effect of the incorporation of bioactive nanofibers in desensitizing agents on dentin permeability. Sixty disks of dentin were randomly distributed in four groups (n = 15). Distribution was based on the desensitizing agents, fluoride varnish and self-etching adhesive, and the presence of nanofibers: C (self-etching adhesive Clearfil SE Bond), CN (Clearfil SE Bond with 1% nanofiber), D (Duraphat varnish), and DN (Duraphat varnish with 1% nanofiber). Dentin permeability was determined using hydraulic conductivity. For a qualitative analysis, confocal laser microscopy and scanning electron microscopy were performed. The C group showed the lowest hydraulic conductance (Lp%) (89.33), while the DN group showed the highest Lp% (116.06). No statistical significance was observed in the Lp% values in all groups after the treatment and 6% citric acid challenge (p > 0.239). In the images, the CN group presented a higher superficial and intratubular deposition. In addition, this group presented a more homogeneous dentin surface and wide occlusion of dentinal tubules than the other treatments. Despite there being no statistical differences among the treatments employed, the images showed that the CN group presented a higher surface and intratubular deposition compared to the other treatments, even after the acid challenge.