Influence of the Extended Use of Desensitizing Toothpastes on Dentin Bonding, Microhardness and Roughness

Abstract The aim of this study was to evaluate the influence of an extended use of desensitizing toothpastes (DTs) on dentin bonding, microhardness and roughness. One hundred and twenty bovine incisor teeth were randomly divided into four groups: G1, distilled water (WATER); G2, Colgate Total 12 (CT12); G3, Colgate Sensitive Pro-Relief (CSPR); and G4, Sensodyne Repair ?αμπ; Protect (SRP). Dentin surfaces were etched with 17% EDTA and 2 years of simulated tooth brushing (20,000 cycles) was performed on their surfaces. Knoop microhardness, surface roughness and scanning electron microscopy (SEM) were performed before and after the simulated tooth brushing. For microshear bonding test, a 2-step self-etching adhesive system (Clearfil SE Bond) was used and 0.8 mm diameter composite resin (Filtek Z350 XT) cylinders were built. Microshear test was performed with an orthodontic wire and with a crosshead speed of 0.5 mm/min. The data were analyzed for: 1) bond strength (one-way ANOVA), 2) microhardness intra-group (Student's test) and inter-group (one-way ANOVA/Tukey's test) comparisons, 3) roughness intra-group (Student's test/Wilcoxon's test) and inter-group (Kruskal-Wallis/Student-Newman-Keuls test) comparisons. The extended use of both dentifrices (conventional and for sensitive teeth) did not affect the bond strength and produced a significant increase in microhardness and roughness of the dentin, except for the microhardness of the SRP group. The simulated tooth brushing technique with water produced an increase in roughness, without reducing significantly the dentin microhardness.

Resumo O objetivo deste estudo foi avaliar a influência do uso prolongado de dentifrícios dessensibilizantes (DTs) na adesão, microdureza e rugosidade da dentina. Cento e vinte dentes incisivos bovinos foram divididos aleatoriamente em quatro grupos: G1, água destilada (WATER); G2, Colgate Total 12 (CT12); G3, Colgate Sensitive Pro-alívio (CSPR); e G4, Sensodyne Repair ?αμπ; Protect (SRP). As superfícies dentinárias foram condicionadas com EDTA a 17% e foram realizados 2 anos de escovação dental simulada (20.000 ciclos) em suas superfícies. A microdureza Knoop, rugosidade de superfície e microscopia eletrônica de varredura (MEV) foram realizadas antes e após escovação dental simulada. Para o teste de adesão por microcisalhamento, foi aplicado um sistema adesivo auto condicionante de 2 passos (Clearfil SE Bond) e foram construídos cilindros de resina composta (Filtek Z350 XT) de 0,8 mm de diâmetro. O teste de microcisalhamento foi realizado com um fio ortodôntico e com velocidade de 0,5mm/min. Os dados foram analisados para: 1) resistência de união (ANOVA 1 fator), 2) comparações de microdureza intra grupo (teste t de Student) e inter grupo (ANOVA 1 fator / teste de Tukey), 3) comparações de rugosidade intra grupo (teste t de Student / teste de Wilcoxon) e inter grupo (Kruskal Wallis / teste de Student-Newman-Keuls). O uso prolongado de ambos dentifrícios (convencional e para dentes sensíveis) não interferiu na resistência de união e produziu um aumento significativo na microdureza e rugosidade da dentina, exceto para a microdureza do grupo SRP. A técnica de escovação dental simulada com água promoveu aumento na rugosidade, sem reduzir significativamente a microdureza da dentina.

Effectiveness of nano-calcium phosphate paste on sensitivity during and after bleaching: a randomized clinical trial

The study aimed to evaluate the effectiveness of in-office bleaching and associated tooth sensitivity on application of nano-calcium phosphate paste as desensitizing agent. Bleaching was performed with 35% hydrogen peroxide gel in 40 patients who were randomly divided into placebo and nano-calcium phosphate paste groups. Bleaching efficacy (BE) was evaluated using a value-oriented Vita shade guide. Tooth sensitivity was recorded using a numeric rating scale (0–4) during bleaching and up to 48 h after each session. The primary outcome of absolute risk of tooth sensitivity was compared using the Fisher’s exact test (α = 0.05). The intensity of tooth sensitivity and the efficacy of in-office bleaching were also statistically evaluated. No significant differences in absolute risk and intensity of tooth sensitivity were detected between the groups (p = 1.0 and p = 0.53, respectively). BE was also found to be similar between the groups (p = 0.67). Although the use of a nano-calcium phosphate paste associated with fluoride and potassium nitrate did not influence the whitening outcome, but it also did not reduce bleaching-induced tooth sensitivity.

Efeito de agentes dessensibilizantes na resistência de união de um sistema adesivo autocondicionante / Effect of desensitizing agents on shear bond strength of a self-etching adhesive

Uma adesão satisfatória pode ser dificultada na presença de agentes dessensibilizantes, como nas cavidades do tipo Classe V. Este estudo teve como objetivo investigar a influência de dois agentes dessensibilizantes na resistência de união de um sistema adesivo autocondicionante quando aplicados previamente ao sistema adesivo. Foram utilizadas 30 coroas de incisivos bovinos, sendo incluídos em buchas de redução de PVC pré-fabricadas, com auxílio de resina acrílica. A superfície vestibular foi preparada, deixando a dentina exposta e os 30 conjuntos foram divididos em três grupos: G1 (adesivo + resina), G2 (oxagel + adesivo + resina) e G3 (G.H.F + adesivo + resina). Então, cilindros de resina composta (4 mm de diâmetro e 4 mm de altura) foram confeccionados. Decorridas 24 horas, os espécimes foram submetidos ao ensaio de cisalhamento e velocidade do atuador de 0,5 mm/min. Os dados foram submetidos ao teste de análise de variância de um fator (Anova - one way), complementados pelo teste de Tukey. Houve diferença estatística significante entre os tratamentos (G2 - 2,49 < G1 - 11,01 = G3 - 10,1). Assim, conclui-se que a resistência de união do sistema adesivo autocondicionante na dentina pré-tratada com agentes dessensibilizantes é prejudicada pelo uso do produto à base de oxalato.

A satisfactory bonding may be hampered in the presence of desensitizers agents, such as class V cavities. The aim of this study was to compare the effect of two different desensitizers on shear bond strength of a self-etch adhesive system. Thirty crowns of bovine incisors were mounted in pre-fabricated acrylic PVC using acrylic resin. The vestibular surface was prepared exposing the dentin and the crowns were divided into three groups: G1 (adhesive + resin), G2 (oxagel + adhesive + resin), and G3 (GHF + adhesive + resin). Resin composite cylinders (4 mm in diameter and 4 mm in height) were then placed. After 24 hours, shear bond strengths were measured using a circular knife-edge and crosshead speeds of 0.5 mm/minute. One-way ANOVA and Tukey’s tests were used to compare the different conditions for bonding system. There was a statistically significant difference between treatments (G2 – 2.49 < G1 – 11.01 = G3 – 10.1). It was concluded that the shear bond strength of the self-etch adhesive system on dentin pre-treated with desensitizing agents is decreased by the use of the product based on oxalate

Comparative evaluation of different strengths of electrical current in the management of dentinal hypersensitivity.

Background : Dentinal hypersensitivity is a commonly occurring but less understood and poorly managed problem of the teeth. Iontophoresis is a technique wherein desensitizing agents can be transferred under electrical pressure into the tooth structure to manage hypersensitivity. Aim : The purpose of present study is to compare the effect of different strengths of electrical current used for varying lengths of time, keeping the electrical dosage constant with the iontophoretic unit in the management of dentinal hypersensitivity. Materials and Methods : This study was conducted among the patients attending the Periodontal Department of the Government Dental College and Hospital, Patiala, Punjab, specifically complaining of tooth hypersensitivity. The Verbal Rating Scale (VRS) was used to record scores pre-, during, and post-treatment. Ten percent SrCl2 solution was applied with an iontophoretic unit. Three applications were performed at weekly intervals, up to the second week, using the same electric current dosage. The data compiled was statistically analyzed. Results : A remarkable reduction in dentinal hypersensitivity to both air blast and cold water stimuli was noted at the end of two months after iontophoresis with each current group / method, namely, I (0.25 mA for 4 minutes), II (0.5 mA for 2 minutes), and III (1 mA for 1 minute). However, the differences in effectiveness / improvement within the three current groups during the entire duration of the study were found to be statistically insignificant. Conclusion : Within the limits of this study, it could be implied that for relieving hypersensitivity, iontophoresis for all three current groups was almost equally effective, and it was found that repeated applications (up to three) gave good relief. Iontophoresis was found to be effective and safe.

Clinical evaluation of desensitizing treatments for cervical dentin hypersensitivity

The aim of this study was to compare different treatments for dentin hypersensitivity in a 6-month follow-up. One hundred and one teeth exhibiting non carious cervical lesions were selected. The assessment method used to quantify sensitivity was the cold air syringe, recorded by the visual analogue scale (VAS), prior to treatment (baseline), immediately after topical treatment, after 1 week, 1, 3 and 6 months. Teeth were randomly assigned to five groups (n = 20): G1: Gluma Desensitizer (GD); G2: Seal&Protect (SP); G3: Oxa-gel (OG); G4: Fluoride (F); G5: Low intensity laser-LILT (660 nm/3.8 J/cm²/15 mW). Analysis was based on the non-parametric Kruskal-Wallis test that demonstrated statistical differences immediately after the treatment (p = 0.0165). To observe the individual effects of each treatment, data was submitted to Friedman test. It was observed that GD and SP showed immediate effect after application. Reduction in the pain level throughout the six-month follow-up was also observed. In contrast, LILT presented a gradual reduction of hypersensitivity. OG and F showed effects as of the first and third month respectively. It can be concluded that, after the 6-month clinical evaluation, all therapies showed lower VAS sensitivity values compared with baseline, independently of their different modes of action.