Mário Honorato Silva e Souza Junior

Adhesive systems: important aspects related to their composition and clinical use

This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classified according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-andrinse systems require a specific acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and deficiencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplified ones due to some chemical associations and interactions. The SeM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

Low shrinkage composite resins: influence on sealing ability in unfavorable C-factor cavities

The present investigation observed the sealing ability of low shrinkage composite resins in large and deep cavities, placed and photocured in one increment. Large, deep cavities (5.0 mm diameter and 2.5 mm deep) surrounded by enamel were prepared in bovine teeth, which were then divided into five groups. Groups 1, 2, 3 and 4: acid conditioning + Adper Single Bond (3M/ESPE, St Paul, MN, USA) and restoration with Aelite LS Posterior (BISCO Inc. Schaumburg, IL, USA) (G1); Filtek Z-350 (3M/ESPE,St Paul, MN, USA) (G2); Filtek Z-350 Flow (3M/ESPE, St Paul, MN, USA) (G3); Premisa (KERR Corporation, Orange, CA, USA) (G4). Group 5: Silorane Adhesive system (3M/ESPE, St Paul, MN, USA) + restoration with Filtek Low Shrinkage Posterior P90 (3M/ESPE, St Paul, MN, USA). After polymerization, the teeth were immersed in 0.5% basic fuchsine solution and immediately washed. Using the Imagetool Software, the extent of dye along the margins was calculated as a percentage of total perimeter. The restorations were then transversally sectioned and the depth of dye penetration was calculated in mm, using the same software. Kruskal-Wallis analysis for all groups showed no statistical differences for extent (p = 0.54) or depth (p = 0.8364) of dye penetration. According to this methodology, the so-called low shrinkage composite resins had the same sealing ability compared to regular and flowable nanocomposite materials.

Etidronate from Medicine to Endodontics: effects of different irrigation regimes on root dentin roughness

An increase in dentin roughness, associated with surface composition, contributes to bacterial adherence in recontaminations. Surface roughness is also important for micromechanical interlocking of dental materials to dentin, and understanding the characteristics of the surface is essential to obtain the adhesion of root canal sealers that have different physico-chemical characteristics. Objectives To evaluate the effects of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic (EDTA), etidronic (HEBP), and citric acid (CA) associated with different irrigation regimens on root dentin roughness. Material and Methods Forty-five root halves of anterior teeth were used. The root parts were sectioned in thirds, embedded in acrylic resin and polished to a standard surface roughness. Initially, the samples of each third were randomly assigned into 3 groups and treated as follows: G1 - saline solution (control); G2 - 5% NaOCl+18% HEBP mixed in equal parts; and G3 - 2.5% NaOCl. After initial measuments, the G3 samples were distributed into subgroups G4, G5 and G6, which were subjected to 17% EDTA, 10% CA and 9% HEBP, respectively. Following the new measuments, these groups received a final flush with 2.5% NaOCl, producing G7, G8 and G9. The dentin surface roughness (Ra) was determined before and after treatments using a profilometer. The Wilcoxon test (α<0.05) was used to compare the values before and after treatments, and the Friedman test (α<0.05) to detect any differences among root thirds. Results (i) NaOCl did not affect the surface roughness; (ii) there was a significant increase in roughness after the use of chelating agents (P<0.01); and (iii) only the G3 group showed a difference in surface roughness between apical third and other thirds of the teeth (P<0.0043). Conclusion Only the irrigation regimens that used chelating agents altered the roughness of root dentin.

A New Weak Chelator in Endodontics: Effects of Different Irrigation Regimens with Etidronate on Root Dentin Microhardness

This study investigated the effect of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic (EDTA), etidronic (HEBP), and citric acid (CA) associated in different irrigation regimens on root dentin microhardness. Forty-five root halves of single-rooted teeth were sectioned into thirds that were embedded in acrylic resin, polished, randomly assigned into 3 groups, and treated as follows: G1: saline solution; G2: 5% NaOCl + 18% HEBP, mixed in equal parts; and G3: 2.5% NaOCl. After measurements, the G3 samples were distributed into subgroups G4, G5, and G6, which were submitted to 17% EDTA, 10% CA and 9% HEBP, respectively. Following the new measurements, these groups received a final flush with 2.5% NaOCl, producing G7, G8, and G9. Microhardness was measured with Knoop indenter under a 25 g load for 15 seconds, before and after treatments. The data were statistically analyzed using paired Students t-test (α<0.05) to compare values before and after treatments and analysis of variance (ANOVA) (α<0.05) to detect any differences among thirds. Except G1, all tested irrigation regimens significantly decreased the microhardness. There were no differences between root thirds before treatments, and all root thirds exhibited equal responses to same treatment. Except saline, all tested irrigation regimens reduced the root dentin microhardness.

Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations

The aim of this study was to determine the effect of a softstart polymerization method from Quartz-Tungsten-Halogen (QTH) and Plasma Arc (PAC) curing units on microleakage of Class V composite resin restorations with dentin cavosurface margins. Seventy-five bovine incisors received standardized class V cavities in all dentin margins. Teeth were divided into 5 equal groups according to the curing cycle. The cavities were incrementally restored with a composite resin (Single Bond/Z-100, 3M). Light curing was applied as follows: Group I: PAC light continuous-cycle curing at 1600 mW/cm² for 3s; Group II: PAC light step-cycle curing (2s at 800 mW/cm² then 4s at 1600 mW/cm²); Group III: QTH light continuous-cycle curing at 400 mW/cm² for 40s; Group IV: QTH light ramp-cycle curing (from 100 to 600 mW/cm² in 15s followed by 25s at 600 mW/cm²); Group V: QTH light pulse-delay curing (200 mW/cm² for 3s followed by 3 min delay then 600 mW/cm² for 30s). Teeth were stored in distilled water at 37ºC for 30 days and then subjected to thermocycling for 500 cycles at 5 and 55ºC. Root apices were sealed and teeth coated with nail varnish before they were immersed in 0.5% fuchsine red dye solution. Teeth were then sectioned and slices were scanned with a computer scanner to determine the area of dye leakage using a computer program (Image Tools). Images of tooth slices were also visually examined under magnification and dye penetration along the tooth/restoration interface was scored. Significant differences in the degree of dye penetration and leakage were detected between groups (p<.05). Groups I and II had significantly higher values of dye penetration and leakage than groups III, IV and V. In conclusion, the use of PAC light curing in a continuous or step cycle modes resulted in increased microleakage of Class V resin composite restorations compared with medium intensity QTH light curing. Pulse, ramp and continuous-cycle curing modes with QTH light resulted in similar degrees of microleakage.

Clinical evaluation of postoperative sensitivity using self-etching adhesives containing glutaraldehyde

The present clinical study aimed to assess the postoperative sensitivity (POS) after 48 hours and seven days in occlusal restorations bonded with three different adhesive systems, two of them containing glutaraldehyde. The restorative procedures were performed using the three-step etch-and-rinse Adper SBMP-Plus adhesive (SBMP), the two-step etch-and-rinse Gluma Comfort One Bond + Desensitizer adhesive (GC+D) and the all-in-one self-etching/priming I Bond (IB) adhesive, which also has glutaraldehyde in its formula. All cavities were restored with Filtek Supreme nanoparticle composite resin. After 48 hours and seven days the patients were recalled and the postoperative sensitivity evaluated. The data analyzed by non-parametric Friedman test showed no significant differences in POS among the three tested groups after 48 hours and seven days.

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.

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.