Alexandre Henrique Susin

Morphology of the smear layer after the application of simplified self-etch adhesives on enamel and dentin surfaces created with different preparation methods

Mild self-etching adhesive systems modify and/or incorporate the smear layer into the resin-infiltrated demineralised dentin. Some factors such as type of bur and use of water spray might affect the thickness of the smear layer on substrates, enamel and dentin. Because of this, the present study evaluated the thickness of smear layers created by different finishing procedures, after the application of three simplified self-etching primers (Adper Prompt L-Pop and two experimental formulations) on enamel and dentin. After the application and removal of the primers’ resinous component, the specimens were prepared for examination under a scanning electron microscope. Smear layers were thicker on enamel than on dentin, irrespective of the finishing methods used. Therefore, different thicknesses of smear layer on enamel/dentin might be an important factor to consider when evaluating the bonding efficacy of self-etching adhesives to both tooth substrates.

Micromorphological effects and the thickness of the hybrid layer – A comparison of current adhesive systems

PURPOSE the aim of this study was to evaluate the effect of dental conditioners in terms of dentin micromorphology and the thickness of the hybrid layer obtained by using the self-etching adhesive systems Adhe SE (AD), G Bond (GB), Adper Prompt L Pop (LP) and Tyrian (TY) and the etch-and-rinse Single Bond (SB). MATERIALS AND METHODS dentin sticks from 50 third human molars were obtained by first cutting dentin disks out of crowns; the disks were subsequently sectioned into sticks. The sticks were assigned to experimental groups as follows: G1: phosphoric acid 37%, Single Bond (SB); G2: Adhe SE (AD); G3: G Bond (GB); G4: Adper Prompt L-Pop (LP); G5: Tyrian SPE (TY). Half the samples served to investigate the dentin micromorphology. To this end, the proprietary conditioner of the respective adhesive system was applied to these samples, and conditioner effects were examined with SEM. The other half of the samples was hybridized and restored with composite resin to investigate the thickness of the hybrid layer, which was also evaluated with SEM. Statistical analysis was performed with ANOVA, Tukeys, and the Kruskal-Wallis tests. RESULTS SEM observation showed significant differences of the hybrid layer thickness. LP presented the highest average thickness, 3.45 microm, while SB presented an average of 2.44 microm and AD an average of 1.43 microm. The averages of TY and SB did not show any statistically significant differences. The adhesive system GB presented the lowest average in hybrid layer, 0.37 microm. The micromorphological evaluation showed that the conditioners commonly removed the smear layer. CONCLUSION all the micromorphological alterations and the hybrid layer thickness show that the adhesive systems studied performed distinct actions. Although there is no apparent correlation of the pH of the conditioners with the thickness of the hybrid layer, it is clear that more acidic conditioners promote more severe transformations in the dentin micromorphology.

Effect of sodium hypochlorite as dentinal pretreatment on bonding strength of adhesive systems.

AIM This study aimed to evaluate the effect of sodium hypochlorite (NaOCl) pretreatment on bond strength of adhesive systems to different dentin regions. MATERIALS AND METHODS Forty human molars were randomly assigned according to different adhesive systems (Adper Single Bond 2; Clearfil SE Bond; Adper SE Plus; G-Bond), pretreatments (control and NaOCl - deproteinization) and dentin regions (proximal, superficial occlusal [SO] and deep occlusal [DO]), n = 5. Cylindrical cavities were performed at the proximal and occlusal surfaces of each sample. For deproteinization, 10% NaOCl was applied on conditioned dentin for 60 s before the adhesive systems application. Two occlusal and one proximal slice were obtained from each sample and submitted to the push-out test. The mode of fracture was analyzed. The data were subjected to three-way ANOVA and Tukey test (P < 0.05). RESULTS There was statistically significant difference between the adhesive systems (P < 0.01) and dentin regions (P < 0.01); however, the pretreatment did not significantly affect the bond strength values (P > 0.05). The bond strength values were higher for the proximal surface, followed by SO and later by DO, being influenced by the adhesive system. The two-step self-etch adhesive systems presented the highest bond strength results. CONCLUSION The deproteinization pretreatment showed similar bonding effectiveness to the conventional adhesive technique. The dentin region plays a rule on the bond strength values.

Starch tubing: an alternative method to build up microshear bond test specimens.

PURPOSE To evaluate an alternative device using starch tubes to build up resin composite specimens for microshear bond tests. MATERIALS AND METHODS Twenty human molars were selected and sectioned mesiodistally to obtain two sections. The teeth were randomly divided into 4 groups (n = 10) according to the adhesive system - a two-step etch-and-rinse adhesive (Adper Single Bond) and a two-step self-etching adhesive (Clearfil SE Bond) - and the type of tube, starch or polyethylene. The tubes were evaluated under a stereomicroscope at 25X magnification to observe the variation in internal diameter. The resin composite was bonded to flat enamel surfaces using one of the adhesive systems and tube types. After 24 h storage in distilled water, the microshear bond strength (µSBS) was determined and the fracture pattern was analyzed under a stereomicroscope (400X magnification). The microshear bond strength values were subjected to two-way ANOVA. The chi-square test was used to compare pre-test failures and fracture patterns between the groups (p < 0.05). RESULTS The type of tube, the adhesive system, and their interaction did not influence the bond strength values (p = 0.062, p = 0.122, and p = 0.301, respectively). No significant differences were observed for pre-test failures or fracture patterns (p = 0.320 and p = 0.561, respectively). CONCLUSION Using starch tubes is an alternative to build up composite resin specimens for microshear bond strength testing with the two tested adhesive systems.

Microshear bonding effectiveness of different dentin regions

AIM The aim of this in vitro study was to evaluate the influence of dentin surfaces with different tubule orientation on bond strength of a multimode adhesive system. MATERIALS AND METHODS Twenty human molars were selected and prepared in different ways in order to produce different dentin regions. The teeth were randomized (n = 5) according to the application modes of a multimode adhesive system (etch-and-rinse and self-etching) and to the dentin region (occlusal and proximal - 1.5 mm depth from dentinoenamel junction). Cylindrical restorations were performed on dentin with a starch tube. The samples remained immersed in distilled water for 24 h and the microshear bond strength (μSBS) test was performed. The μSBS values were expressed in MPa and analyzed with ANOVA and Tukeys test (P < 0.05). RESULTS There was no significant difference in the bond strength values between the application modes of the adhesive system (P = 0.19); however, the dentin regions (P < 0.05) significantly affected the μSBS. The proximal dentin presented higher bond strength values than occlusal dentin. CONCLUSION The dentin surfaces with different tubule orientation influenced the bonding effectiveness of the adhesive system tested.

Color stability of a resin composite: Effect of the immersion method and surface treatments

Background: In vitro staining methods expose the entire specimen to staining solutions. In a real clinical situation, this is not observed, since one should consider that the bonded surface is not exposed to the oral environment. Theoretically, the clinical condition would be the best simulated if the specimens were exposed to staining solutions by partial immersion. Aims: To evaluate if different immersion methods and surface treatments influence the color stability of resin-based specimens. Methodology: A stainless steel matrix was used to prepare 30 disc-shaped specimens that were randomly allocated in three groups: Without polishing, polishing with abrasive discs, and surface sealant. Half of the specimens were isolated to maintain only the upper surface exposed to staining (partial immersion) and the other half was totally immersed in coffee solution for 48 h (total immersion). The coordinates ΔE*, ΔL*, Δa*, Δb* were assessed by spectrophotometer. Statistical Analysis: Two-way ANOVA and Tukeys post hoc tests (α =0.05). Results: Specimens submitted to partial immersion showed lower values of ΔE*, ΔL*, Δa*, Δb*, in comparison to total immersion (P = 0.000). Specimens covered by a surface sealant presented lower ΔE* values regardless of the immersion method. Conclusions: Specimens totally immersed in staining solutions could in somehow overestimate the color change, once that in most clinical conditions not all of the restoration surfaces are exposed to the oral environment. Moreover, as the surface sealant application produces color change values that are clinically acceptable, it might be used in esthetic restorations as an adjunct treatment.

Influence of Smear Layer on Depth of Demineralization and Thickness of Hybrid Layer

In order to evaluate the thickness of the hybrid layer and depth of demineralization of dentin surfaces submitted to different treatments, dentin slices from human teeth were divided into two groups: one polished with 60-grit SiC paper and the other with 600-grit SiC paper. The adhesive systems applied were: Adhe SE®, Clearfil SE™ Bond, G Bond™ and Adper Single Bond™. After treatment, the samples were fractured and prepared and the smear layer, the effect of conditioners, and thickness of the hybrid layer were analyzed by SEM. The adhesive system and smear layer influenced thickness of the hybrid layer. The conditioners were more efficient over thin smear layer. A direct correlation was demonstrated between depth of demineralization and thickness of the hybrid layer. The smear layer was able to influence the depth of demineralization and thickness of the hybrid layer; however, for the total-etching adhesive system, thickness of the hybrid layer was independent of the smear layer.

Reflections about Adhesive Systems

Los sistemas adhesivos son responsables de una union eficaz entre los dientes y la resina, dando como resultado una restauracion durable. Son moleculas organicas bi o multifuncionales que contienen grupos reactivos que interactuan con la dentina y con el monomero de resina de composite. Los sistemas adhesivos se caracterizan por la adhesion humeda, que es el resultado de la presencia de radicales hidrofilicos en sus composiciones, para promover una mejor adherencia y las mejores propiedades de la adhesion. Los sistemas adhesivos pueden utilizar dos estrategias diferentes para interactuar con la estructura dental: Tecnica de grabado total y auto-grabado. Los sistemas de grabado total requiere un acondicionamiento, un lavado y un paso de priming con el fin de permitir la participacion de las fibras de colageno por los monomeros de resina y la formacion de la llamada capa hibrida. El grabado total promueve la limpieza de la dentina, tambien promueve la desmineralizacion superficial y condiciona a las fibrillas de colageno para participar de un mecanismo de interfaz de union diente/sistema adhesivo /material de restauracion. Los sistemas adhesivos autograbantes se caracterizan por la desmineralizacion y la infiltracion de los monomeros de resina de forma simultanea. Esta tecnica es atractiva debido a la sensibilidad reducida asociada a conservar la capa de barro dentinario y tapones de barro dentinario, reduciendo al minimo la posibilidad de contaminacion accidental de la superficie de union con la superficie de la dentina a traves del liquido dentinario trasudado.

Effect of caries-affected dentin on one-step universal and multi-step etch-and-rinse adhesives’ bond strength

Objetivo Avaliar a influencia da dentina afetada na resistencia de uniao de um sistema adesivo universal e de um adesivo de condicionamento acido total acetonado. Material e metodo As faces oclusais de 60 terceiros molares humanos, higidos e cariados, foram removidas a fim de expor o substrato dentinario. Os dentes foram divididos aleatoriamente em 6 grupos: Single Bond Universal (3M Dental Products, Seefeld, Germany), nos protocolos de condicionamento total e autocondicionante, e Prime&BondNT (DentsplyDeTrey, Konstanz, Germany), em dentina higida e afetada. A smearlayer de 30 especimes de dentina higida foi padronizada com lixas de granulacao 600. A dentina residual infectada de 30 especimes foi removida com uma broca carbide numero 4 ate que nada fosse detectavel por uma inspecao clinica. Pinos de resina composta (Filtek Z350 XT, 3M ESPE, St. Paul, MN) foram construidos usando tubos de amido como matriz. O teste de microcisalhamento foi realizado em uma maquina universal de testes ate que houvesse a fratura. Resultado Diferencas significantes foram observadas na resistencia de uniao apenas para os especimes de dentina afetada. A resistencia de uniao do Single Bond Universal nao foi influenciada pelo protocolo de aplicacao nos especimes de dentina higida, mas diminuiu para os especimes de dentina afetada, enquanto que o desempenho da adesao do Prime&BondNT nao foi influenciada pela condicao dentinaria. Conclusao A dentina afetada reduziu a resistencia de uniao do Single Bond Universal, em comparacao a dentina higida. A resistencia de uniao do Prime & Bond NT nao foi alterada pela condicao dos substratos.

Effect of 180‐Day Water Storage on Bonding Effectiveness of Self‐Adhesive Systems to Occlusal and Proximal Dentin

PURPOSE This study aimed to evaluate the microshear bond strength (μSBS) values of adhesive systems to occlusal and proximal dentin submitted to water storage aging. MATERIALS AND METHODS Occlusal and proximal dentin surfaces were obtained from 90 molars, polished with 600-grit SiC and divided according to the type of adhesive system: one total-etch and two self-etch. Starch tubing was used to perform 1 mm2 cylindrical composite resin restorations. The specimens were aged in distilled water during different storage times: 24 hours, 3 months, and 6 months (n = 10). The specimens were submitted to μSBS test. The μSBS values in MPa were subject to three-way ANOVA and post hoc Tukey test (p < 0.05). RESULTS There was no statistical difference in the μSBS values among the storage times (p = 0.72); however, the dentin region (p < 0.01) and the adhesive system (p < 0.01) significantly affected the μSBS. The proximal surface (14.7 ± 3.3 MPa) presented higher μSBS values than the occlusal dentin (10.9 ± 4.1 MPa). The all-in-one adhesive system (GB) achieved the highest μSBS mean (17.0 ± 1.7 MPa). CONCLUSION Both material and dentin surface factors affected the composite-dentin bond strength; however, the water storage did not influence bonding effectiveness over time.