Anelise Fernandes Montagner

Does air particle abrasion affect the flexural strength and phase transformation of Y-TZP? A systematic review and meta-analysis

OBJECTIVES A systematic review was conducted to assess the effects of air-particle abrasion procedures on the mechanical strength and phase transformation of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). DATA This report followed the PRISMA Statement. From 1013 eligible studies, 78 were selected for full-text analysis, from which 37 were excluded. The 41 remaining papers were included for the systematic review; hand-searching yielded three papers. The review comprised a total of 44 studies; 21 were included in the meta-analysis. SOURCES Searches were performed with no publication year limit through November 2015 in PubMed/MEDLINE, Web of Science (Core Collection) and Scopus databases. STUDY SELECTION In vitro studies evaluating the effect of air-particle abrasion protocols on the mechanical strength and/or phase transformation of Y-TZP zirconia specimens, immediately or after aging. For the meta-analysis, flexural strength data of air-particle abrasion vs. control (nonabraded) were globally and subgroup analyzed. Subgroup analyses assessed blasting parameters (particle size, pressure, or time duration) and the effect of aging. Statistical analyses were conducted using RevMan 5.1 (Cochrane Collaboration, Copenhagen, Denmark). Comparisons were performed with random-effect models at a 5% significance level. Phase transformation data were included only in the systematic review, as insufficient data were available for meta-analysis. CONCLUSIONS Airborne-particle abrasion improved flexural strength of Y-TZP, regardless of abrasion parameters and the presence or lack of aging (p≤0.05). Phase transformation tended to be increased by air abrasion immediately or with up to 2h of aging. However, after aging for 12h or more, the abraded Y-TZP showed less monoclinic content than the control.

Are self-etch adhesive systems effective in the retention of occlusal sealants? A systematic review and meta-analysis.

BACKGROUND Occlusal sealants are an effective method for caries prevention, although the effectiveness of different application strategies has not been established yet. AIM This systematic review compared the retention rate of sealants placed on occlusal surfaces following the use of self-etch adhesive systems and traditional acid etching, with or without the application of adhesive system. DESIGN Literature searching was carried out until June 2015 in PubMed/MEDLINE, CENTRAL, and ClinicalTrials databases selecting randomized clinical trials that evaluated self-etch adhesive systems associated with pit and fissure sealants in primary or permanent molars comprising retention as outcome. From 683 potentially eligible studies, 10 were selected for full-text analysis and 5 were included in the meta-analysis. Two reviewers independently selected the studies, extracted the data, and assessed the bias risk. Pooled-effect estimates were obtained by comparing the retention failure rate between groups (self-etch systems vs acid etching with or without adhesive systems). RESULTS Significant difference was found between groups, favoring the control group (prior acid etching) (P < 0.05), which showed lower failure rate in the retention of occlusal sealants. High heterogeneity was found on the meta-analysis. Most trials showed good evidence strength. CONCLUSIONS Occlusal sealants applied with self-etch systems show lower retention throughout time than sealants applied in the conventional approach, regardless of the use of adhesive systems.

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.

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.

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 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.

Effectiveness of pre-treatment with chlorhexidine in restoration retention: A 36-month follow-up randomized clinical trial

OBJECTIVES This study evaluated the effect of the pre-treatment with 2% chlorhexidine digluconate (CHX) as coadjutant in restoration retention of noncarious cervical lesions (NCCL), after 36 months of follow-up. METHODS A randomized controlled split-mouth and triple-blind (operators, patients and evaluator) trial was carried out. Patients (n=42) with at least two non-carious cervical lesions were included. The teeth with NCCL were randomly assigned to two treatment groups: application of 2% CHX (experimental group) or a placebo solution (control group) for 60s after acid etching and before the adhesive application. A trained and calibrated examiner evaluated the restorations at baseline (1 week) and at each recall (6, 12, 24 and 36 months) using the FDI criteria. A total of 225 restorations were evaluated after 36-month follow-up. Data were subjected to survival analysis using the Kaplan-Meier method, and the log-rank test was used to evaluate the existence of differences between the survival curves (α=0.05). RESULTS The restorations survival rate after 36 months of follow-up was 76.1%. There was no difference in the retention and failure rates between the experimental and the control group (p=0.968). There was an increased failure trend when restorations were located subgingival compared to those at the gingival level or supragingival. CONCLUSION The pre-treatment with 2% chlorhexidine digluconate did not promote further restoration retention of noncarious cervical lesions. CLINICAL SIGNIFICANCE The cavity pre-treatment with chlorhexidine for inhibition of hybrid layer degradation does not add any beneficial effect to the clinical performance of restorations.