Sandro Cordeiro Loretto

Influence of photopolymerization light source on enamel shear bond strength after bleaching

This study evaluated the influence of 3 different photopolymerization sources on enamel shear bond strength after bleaching with 10% carbamide peroxide. Seventy-two incisive bovine teeth were randomly divided into 6 groups (n=12) according to bleaching treatment and photopolymerization source used: G1 -- Bleached / Halogen lamp; G2 -- Not bleached / Halogen lamp (control); G3 -- Bleached / Light-emitting diodes (LED); G4 -- Not bleached / Light-emitting diodes (LED) (control); G5 -- Bleached / Xenon plasma arc; G6 -- Not bleached / Xenon plasma arc (control). Experimental groups were exposed to bleaching agent for a period of 14 days, with a daily contact of 4 h and then stored in artificial saliva at 37 degrees C. Control groups were stored in artificial saliva at 37 degrees C for same period of bleaching treatment. Procedures for bonding composite resin to enamel were carried out according to manufacturer instructions. After storage in distilled water at 37 degrees C for 24 hours, all samples were submitted to shear bond strength test. G2 had the highest mean value (14.86 MPa) while G5 had the lowest (12.32 MPa). The comparison of groups by 2-way ANOVA showed that there were no significant differences for either of the factors considered in this study (bleaching and photopolymerization source), hence the interaction between these factors. It was therefore possible to conclude that neither enamel bleaching nor the photopolymerization source used had any influence on enamel shear bond strength.

One-Year Evaluation of a Simplified Ethanol-Wet Bonding Technique: A Randomized Clinical Trial

The objective of this randomized clinical trial was to evaluate the clinical performance of adhesive restorations using a three-step etch-and-rinse adhesive (TSER), a one-step self-etching adhesive (OSSE), and a simplified ethanol-wet bonding technique (EWBT) prior to the application of a composite resin in non-carious cervical lesions. Ninety-three restorations (31 for each group) were placed in 17 patients by a single operator. No cavity preparation was performed. After 6 and 12 months, the restorations were assessed by two previously trained examiners using modified Ryge criteria for retention (kappa=1.00) and marginal adaptation/staining (kappa=0.81), and the results were analyzed by Fishers exact and Kruskal-Wallis tests, respectively. No significant differences were observed among groups at the 6- and 12-month time points for any of the assessed criteria (p≥0.05). The intra-group analysis performed by Cochrans test (for retention) and Wilcoxon test (for marginal adaptation/staining) revealed significant differences between the baseline/12-month time intervals in marginal adaptation in OSSE (p=0.0180) and in marginal staining in TSER (p=0.0117). The survival analysis for retention criteria performed using a log-rank test did not show significant differences (p>0.05). The restorations placed using the simplified EWBT performed equally well as the other adhesive strategies employed.

Influence of Prolonged use of Desensitizing Dentifrices on Dentin Bond Strength of Self-Etching Adhesive System

La hipersensibilidad dentinaria es una condicion clinica relativamente comun, que afecta a una gran parte de la poblacion mundial. El objetivo fue evaluar la influencia del tratamiento previo y prolongado con dentifricos desensibilizantes (DD) en fuerza de adhesion a la dentina, que promueve un sistema adhesivo de autograbado. Se utilizaron 70 incisivos bovinos no cariados, y se dividieron en cinco grupos (n= 14), de acuerdo con la pasta de dientes desensibilizante utilizada: G1: agua destilada (agua) (control), G2: Colgate Total 12 (CT12) (control), G3: Colgate Sensitive Pro-Alivio (CSPR), G4: Sensodyne Rapido Alivio (SRR) y G5: Sensodyne Repair & Protect (SRP). Los dientes tenian sus superficies bucales aplanadas hasta la exposicion de la dentina, y se obtuvieron fragmentos de 4x4x2 mm. Los fragmentos se incluyeron en cilindros de cloruro de polivinilo y se expusieron a 17 % de EDTA durante un 1 min. Despues, las muestras se sometieron a 20 000 ciclos de cepillado dental simulado. Despues de 24 h en saliva artificial, las muestras se hibridaron (Clearfil SE Bond - Kuraray), y cilindros de resina compuesta fueron construidos sobre superficies de dentina. Las muestras se almacenaron en agua destilada, a 37 °C durante 24 h y luego se determino la resistencia al cizallamiento. El mayor valor de resistencia a la union (MPa) se observo en el grupo CT12 (4,39), y el menor en el grupo CSPR (3,34). Los datos fueron analizados estadisticamente mediante ANOVA de un factor 1 (ð= 0,05), y los resultados no mostraron diferencias significativas (p= 0,5986) teniendo en cuenta el factor de los DD. El patron de fractura predominante sobre la dentina fue el cohesivo. El uso previo y prolongado de diferente DD no afecto resistencia de union a la dentina promovido por un sistema adhesivo de autograbado.

Is the Ethanol Wet-bonding Technique a Promising One?

La tecnica de la adhesion humeda en etanol (TAHE) se introdujo en un intento de superar los problemas causados por la alta hidrofilicidad y/o la penetracion incompleta de la mayoria de los sistemas adhesivos disponibles comercialmente. Esta estrategia ofrece mejores condiciones para la interdifusion de monomeros dentinarios hidrofobicos. Hoy en dia, hay muchos protocolos TAHE que producen las interfaces de union con minima degradacion y mayor durabilidad en comparacion con los sistemas adhesivos hidrofilicos comerciales. El objetivo de esta revision es discutir con mas detalle la TAHE, explicando los siguientes aspectos relacionados: la saturacion de la dentina, la preparacion del primer hidrofobico, la inactivacion de las metaloproteinasas (MMPs), remineralizacion biomimetica de la dentina, y las perspectivas clinicas de esta tecnica. La presente revision sobre la TAHE proporciona soporte para una mejor comprension del comportamiento de la dentina cuando es expuesto a la deshidratacion y la interaccion con monomero hidrofobo. Ademas, se sugieren estudios adicionales para investigar la estabilidad a largo plazo de este tipo de camada hibrida.

Evaluation of metallic brackets adhesion after the use of bleaching gels with and without amorphous calcium phosphate (ACP): in vitro study

OBJECTIVE To evaluate in vitro the effects of tooth whitening using gel with Amorphous Calcium Phosphate (ACP) on the bond strength of metal brackets. METHODS Thirty-six bovine incisors were sectioned at the crown-root interface, and the crowns were then placed in PVC cylinders. The specimens were divided into 3 groups (n = 12) according to whitening treatment and type of gel used, as follows: G1 (control) - no whitening; G2 - whitening with gel not containing ACP (Whiteness Perfect - FGM), G3 - whitening with gel containing ACP (Nite White ACP - Discus Dental). Groups G2 and G3 were subjected to 14 cycles of whitening followed by an interval of 15 days before the bonding of metal brackets. Shear bond strength testing was performed on a Kratos universal test machine at a speed of 0.5 mm/min. After the mechanical test, the specimens were assessed to determine the adhesive remnant index (ARI). The results were subjected to ANOVA, Tukeys test and Kruskal-Wallis test (5%). RESULTS Significant differences were noted between the groups. Control group (G1 - 11.10 MPa) showed a statistically higher shear bond strength than the groups that underwent whitening (G2 - 5.40 Mpa, G3 - 3.73 MPa), which did not differ from each other. There were no significant differences between the groups in terms of ARI. CONCLUSIONS Tooth whitening reduces the bond strength of metal brackets, whereas the presence of ACP in the whitening gel has no bearing on the results.

Ethanol-Wet Bonding Technique: 18-month Clinical Evaluation

El proposito de este ensayo clinico aleatorizado fue evaluar, durante 18 meses, el exito clinico de las restauraciones realizadas por la tecnica de adhesion humeda en etanol (TAHE) en comparacion con las tecnicas de grabado independiente de tres pasos (GTP) y de autograbado de un paso (AUP). Un solo operador, especializado en odontologia restaurativa, realizo sobre 17 pacientes 93 restauraciones en lesiones cervicales no cariosas (31 para cada grupo). Los diferentes protocolos adhesivos se distribuyeron aleatoriamente en las lesiones cervicales hasta que los tres grupos estuviesen presentes en el mismo paciente y en cantidades iguales. Las restauraciones fueron evaluadas a los 6, 12 y 18 meses, por dos examinadores calibrados y que no participaron del procedimiento restaurador. Las directrices modificadas del Servicio de Salud Publica de Estados Unidos (SSPEU) fueron la base para las evaluaciones de las siguientes variables: retencion (kappa= 1,00), adaptacion y decoloracion marginal (kappa= 0,81). Estas variables fueron analizadas mediante la prueba exacta de Fisher y Kruskal-Wallis, respectivamente. No se observo diferencia significativa entre los grupos despues de 18 meses en las tres variables evaluadas (p >0,05). El analisis intra-grupo hecho por la prueba de Cochran (para la retencion) y la prueba de Wilcoxon (para la adaptacion y decoloracion marginal) revelaron diferencias significativas entre los intervalos de tiempo de la linea de base / 18 meses para la retencion (p= 0,0101) y adaptacion marginal en el grupo AUP (p= 0,0117), y para la decoloracion marginal en los grupos GTP (p= 0,0051) e TAHE (p= 0,0277). El analisis de supervivencia para la retencion, asi como la comparacion del exito clinico de los protocolos adhesivos, fueron realizados con la prueba de log-rank, y no hubo diferencias significativas (p >0,05) entre los grupos. No hubo diferencia en el exito clinico de los tres protocolos adhesivos despues de 18 meses.

Influence of Time Intervals between Bleaching Procedures on Enamel Microhardness and Surface Roughness

Background: Dental bleaching has been increasingly sought out to improve dental aesthetics, but it may cause changes in dental enamel. Objective: To assess the influence of different time intervals on bleaching gel applications with regard to the Microhardness (MH) and Surface Roughness (SR) on dental enamel. Material and Methods: Forty bovine incisors were randomly divided into two groups (G1 and G2) and both were bleached with 35% Hydrogen Peroxide (HP35) (n=20; G1: seven-day interval and G2: two-day interval). The MH and SR tests were performed before bleaching (T0) and after the first (T1), second (T2), and third (T3) bleaching gel applications. The specimens were stored in artificial saliva between each application (37°C). The data were analyzed using the student’s t-test (p ≤ 0.05) for dependent samples. Results: The reduced time interval (two days) led to a significant reduction in MH, while MH was not affected during the seven-day interval. The SR results increased regardless of the bleaching gel application time interval. Conclusion: The decreased time interval of two days between bleaching gel applications caused changes in MH but did not influence the SR of dental enamel.

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

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 (Students test) and inter-group (one-way ANOVA/Tukeys test) comparisons, 3) roughness intra-group (Students test/Wilcoxons 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.

Influence of Tooth Bleaching on the Bonding Strength of Silorane-Based Restorative System

Los procedimientos de blanqueamiento dental pueden interferir en la union adhesiva de los materiales de restauracion a base de metacrilato. Despues de la introduccion de materiales compuestos a base de silorano, hay poca informacion disponible acerca de esta interaccion. El objetivo fue evaluar la influencia del blanqueamiento en la cizalladura de la fuerza de adhesion sobre esmalte del sistema restaurativo a base de silorano. Cuarenta dientes incisivos bovinos fueron divididos aleatoriamente en 4 grupos (n= 10), siendo: G1 (control) - no aclarado + Clearfil SE Bond (CSEB)/Filtek Z250 (z250), G2 (control) - no aclarado + adhesivo de silorane (AS)/Filtek P90 (P90), G3 - aclarado + CSEB / Z250; g4 - aclarado + AS/P90. Los dientes fueron seccionados, tenian coronas incluidas en anillos de pvc, y las superficies de esmalte fueron molidas y pulidas con papeles abrasivos de silicona de silicio. G1 y G2 fueron almacenados en saliva artificial (37 °C), renovada diariamente, durante un periodo de 04 dias. G3 y G4 se expusieron a 2 sesiones de peroxido de hidrogeno al 38% (38 HP) con 03 aplicaciones de 15 min en cada sesion. Los cilindros de resina compuesta fueron construidos en las superficies de esmalte. Los procedimientos de union se realizaron segun las instrucciones del fabricante. Despues del almacenamiento en agua destilada durante 24 h (37 °C), las muestras fueron sometidas al ensayo de resistencia de adhesion al cizallamiento. Los datos fueron analizados por ANOVA de dos vias y prueba t (5%). La comparacion intragrupo mostro diferencias significativas para Z250 despues del aclaramiento, pero no para P90. La resistencia al corte fue significativamente menor para P90, a pesar de los procedimientos de blanqueamiento. En conclusion, el blanqueamiento con 38HP no tuvo influencia en la resistencia de la union esmalte de P90, a pesar de presentar una fuerza de union mas baja que Z250.

Influence of whitening gel on pulp chamber temperature rise by in-office bleaching technique

INTRODUCTION: Dental bleaching is a conservative method for the aesthetic restoration of stained teeth. However, whitening treatments are likely to cause adverse effects when not well planned and executed. OBJECTIVE: This study evaluated the influence of whitening gel on temperature rise in the pulp chamber, using the in-office photoactivated dental bleaching technique. MATERIAL AND METHOD: The root portion of an upper central human incisor was sectioned 3mm below the cemento-enamel junction. The root canal was enlarged to permit the insertion of the K-type thermocouple sensor (MT-401) into the pulp chamber, which was filled with thermal paste to facilitate the transfer of heat during bleaching. Three photosensitive whitening agents (35% hydrogen peroxide) were used: Whiteness HP (FGM), Whiteness HP Maxx (FGM) and Lase Peroxide Sensy (DMC). An LED photocuring light (Flash Lite - Discus Dental) was used to activate the whitening gels. Six bleaching cycles were performed on each group tested. The results were submitted to one-way ANOVA and LSD t-test (α<0.05). RESULT: The lowest mean temperature variation (oC) was detected for Lase Peroxide Sensy (0.20), while the highest was recorded for Whiteness HP (1.50). CONCLUSION: The Whiteness HP and Whiteness HP Maxx whitening gels significantly affected the temperature rise in the pulp chamber during bleaching, and this variation was dependent on the type of whitening gel used.