Effects of applying procyanidins on the bond strength of bleached dentin to composite resin / 口腔疾病防治

Objective@#To study the influence of procyanidins on the bonding strength of dentin bleached by carbamide peroxide to composite resin.@*Methods @#By applying different treatments to dentin bonding interfaces, 120 human third molars were randomly divided into 12 groups (n = 10): W group (no bleaching+deionized water), Wa group (no bleaching+deionized water+aging), WT1 group (no bleaching+5% procyanidins for 1 min), WT1a group (no bleaching+5% procyanidins for 1 min+aging), WT2 group (no bleaching+5% procyanidins for 5 min), WT2a group (no bleaching+5% procyanidins for 5 min+aging), C group (carbamide peroxide+deionized water), Ca group (carbamide peroxide+deionized water+aging), CT1 group (carbamide peroxide+5% procyanidins for 1 min), CT1a group (carbamide peroxide+5% procyanidins for 1 min+aging), CT2 group (carbamide peroxide+5% procyanidins for 5 min), and CT2a group (carbamide peroxide+5% procyanidins for 5 min+aging). The bond strength to composite resin was measured by universal mechanical testing machine, microstructure and the nanoleakages were measured by scanning electron microscope immediately or after the thermal cycling aging test.@*Results@#The immediate bond strength of the bleached groups pretreated with procyanidins for 1 min (P<0.001) and 5 min (P<0.001) was higher than that of Group C, and the difference was statistically significant. Meanwhile, there was no statistically significant difference between Group CT1 and Group CT2 (P = 1.000). After the thermal cycles, the bond strength of each group declined. The differences between Group W and Group Wa (P<0.001) and Group C and Group Ca (P<0.001) were statistically significant, but no significant differences between Group CT1 and Group CT1a (P = 0.052) or Group CT2 and Group CT2a (P = 0.053) were found. The main effects of “aging” (P<0.001), “bleaching” (P<0.001) and “procyanidins” (P<0.001) and the second-order interaction effects of “bleaching * procyanidins” (P = 0.008), “bleaching * aging” (P = 0.024), and “aging * procyanidins” (P<0.001) were statistically significant. SEM observations showed that the hybrid layers in Groups C, CT1 and CT2 were not clear, and the hybrid layers in Groups Ca, CT1a and CT2a were partially destroyed and disintegrated. Under backscattering mode, it was observed that there were a large number of silver nitrate particles in the hybrid layer of Group Ca, and the residual silver ions in the hybrid layer of Groups CT1a and CT2a were decreased. @*Conclusion@# Pretreatment with 5% procyanidins for 1 min can improve the immediate bond strength of dentin bleached by carbamide peroxide to composite resin and maintain bonding durability.

Effects of different pretreatment agents on primary tooth dentin bonding durability / 口腔疾病防治

Objective@#To explore the effects of different pretreatment agents on primary tooth dentin bonding durability.@*Methods @#Forty-two retained primary molars were selected, 24 of which were cut along the mesial and distal directions; thus, 48 samples were obtained for shear bond strength tests, and the other 18 teeth were used for nanoleakage tests. According to different pretreatments, both experimental samples were divided randomly into three groups (Group A: distilled water pretreatment group; Group B: 2% chlorhexidine pretreatment group; Group C: 10 mg/mL resveratrol pretreatment group). The test specimens were prepared, the shear bond strength was tested, and interfacial nanoleakage evaluation and scanning electron microscope observation were performed to evaluate the effects of different pretreatment agents on the bonding interface immediately and after aging for one hour with 10% sodium hypochlorite aqueous solution.@*Results @#The immediate shear bond strength results showed that there was no significant difference among the three test groups. After aging, the shear bond strength of Group C was significantly higher than that of Group A and Group B (P<0.05). After aging, the shear bond strength of Group A was significantly lower than the immediate shear bond strength (P<0.05), whereas there was no significant difference in shear bond strength before and after aging in Group B and Group C (P>0.05). For Group C, there was no significant difference in interfacial nanoleakage before and after aging. In addition, among the three groups, Group C had the lowest interfacial nanoleakage (P<0.05).@*Conclusion@# Both chlorhexidine and resveratrol pretreatment can improve the adhesion durability of deciduous dentin, but the effects of resveratrol are better than those of chlorhexidine.

Collagen cross-linking agents + dimethyl sulfoxide improving the adhesive properties of erosive lesion dentin

Abstract To investigate the effect of the dimethyl sulfoxide combined with cross-linking agents on microtensile bond strength, silver nitrate penetration and in situ degree of conversion analysis of adhesives to the erosive dentin treatment with Cola-based soft drink. One hundred and sixty-six molars were assigned to 20 groups: (1) Treatment: Sound dentin; Erosive dentin; Erosive dentin treated with primer of dimethyl sulfoxide; Erosive dentin treated with DMSO primer containing proanthocyanidin and rivoflavin; (2) Adhesive systems: iBond Universal and Scotchbond Universal; and (3) adhesive strategy: etch-and-rinse or self-etch strategy. After restoration, specimens were sectioned into sticks to be tested. The data from microtensile bond strength (MPa), silver nitrate penetration (%) and in situ degree of conversion (%) were analyzed by (three- and two-factor ANOVA; Tukey's test α=5%). The application of dimethyl sulfoxide combined of not with cross-linkers improved all properties evaluated when compared to only erosive dentin treatment with Cola-based soft drink. However, only when dimethyl sulfoxide was combined to cross-linkers, the values of the microtensile bond strength, silver nitrate penetration and in situ degree of conversion in erosive dentin treatment with Cola-based soft drink was similar to sound dentin, for both adhesives and adhesive strategies. The application of dimethyl sulfoxide combined with the collagen cross-linking agent contributed to increasing the bond strength and degree of conversion in erosive lesion dentin, at the same time that significantly reduction of nanoleakage in this substrate.

Resumo Este estudo investigou o efeito do dimetil sulfóxido combinado a agentes de reticulação de colágeno na resistência de união à microtração, infiltração de nitrato de prata e análise do grau de conversão por Micro-Raman de sistemas adesivos universais para a dentina erosionada por refrigerante a base de Cola. Cento e sessenta molares foram divididos em 20 grupos: (1) Tratamento: Dentina sadia; Dentina erosionada; Dentina erosionada tratada com primer de dimetil sulfóxido; Dentina erosionada tratada com primer contendo 6,5% de proantocianidina e; Dentina erosionada tratada com primer contendo 0,1% de rivoflavina; (2) Sistemas adesivos: iBond Universal e Scotchbond Universal; e (3) estratégia adesiva: estratégia condicionamento e lavagem ou autocondicionate. Após a restauração, os espécimes foram seccionados em palitos e testados. Os dados dos três testes foram analisados estatisticamente (ANOVA de 2 e 3 fatores e teste de Tukey; α = 5%). A aplicação de dimetil sulfóxido combinado ou não agentes de reticulação de colágeno melhorou todas as propriedades avaliadas quando comparado a dentina erosionada. Entretanto, apenas quando o dimetil sulfóxido foi combinado com agentes de reticulação de colágeno, os valores de adesão a dentina, infiltração de nitrato de prata e grau de conversão em dentina erosionada foi semelhante a dentina sadia, para os dois adesivos e estratégias adesivas. A aplicação de dimetil sulfóxido combinado com agentes de reticulação de colágeno contribuiu para aumentar a resistência de união e o grau de conversão dentro da camada híbrida na dentina erodida, ao mesmo tempo que reduziu significativamente a nanoinfiltração neste substrato.

The finish line location of the cemented crown is an influencing factor for tensile bond strength, marginal adaption and nanoleakage? / A localização do término marginal em coroas cimentadas é um fator que influencia a resistência à tração, adaptação marginal e nanoinfiltração?

Objective: The aim of this study was to evaluate the influence of different crowns finishing line location on the crown tensile bond strength, marginal adaption and nanoleakage. Material and Methods: Sixty healthy third molars were collected. For tensile bond strength, a self-adhesive resin cement was used. For marginal adaption, epoxy resin models were prepared. Prior to tensile bond strength test, images for the epoxy resin models were measured under scanning electron microscopy (SEM). Nanoleakage was measured using same protocol. Failure mode was evaluated through SEM and classified: adhesive failure, cohesive in cement, cohesive in dentin, cohesive in resin composite, cohesive in enamel, and mixed. Statistical analysis was performed using Shapiro-Wilk and Kolmogorov Smirnov normality tests, two-way ANOVA, Bonferroni (posthoc) parametric test, with significance level of 5% (P < .05), Spearman correlation test. Results: tensile bond strength was not statistically different between the cemented groups with composite resin and ceramic. Cementation of ceramic was not statistically different between the groups (enamel, 3.28 Pa; dentin, 3.14 Pa; resin, 2.85 Pa). Marginal adaption was statistically different between resin and ceramic; finish line location varied between enamel and resin (175.91 µm vs. 433.58 µm). Nanoleakage rate was statistically different among all groups, except for resin: with resin (9.49%) and ceramic (9.35%). There was a predominance of adhesive failure in all groups. Conclusion: finish line location can be performed safely in enamel and dentin. Composite resinas substrate present an alternative, but still need to be more studied. Regarding the crown's material, it is possible to perform a satisfatory restoration in both: resin and ceramic. With ceramics presenting better results. (AU)

Objetivo: O objetivo deste estudo foi avaliar a influência da localização do término marginal na cimentação de coroas, na resistência à tração, adaptação marginal e nanoinfiltração, de acordo com os fatores: término marginal (dentina, esmalte e resina composta), e material restaurador (resina composta e cerâmica). Material e Métodos: Foram coletados 60 terceiros molares hígidos. Para o teste de resistência à tração, todas as amostras foram praparadas com término em chanfro e um cimento resinoso autoadesivo foi utilizado para a cimentação. Para a avaliação da adaptação marginal, foram confeccionados modelos em resina epóxica da linha de cimentação das amostras, previamente ao teste de tração, e submetidas à avaliação em microscopia eletrônica de varredura (MEV), para obtenção de imagens que posteriormente foram mensuradas. Para a nanoinfiltração, foram confeccionados fragmentos dos substratos e materiais restauradores, que foram cimentados com o mesmo protocolo. As amostras/imagens foram obtidas em MEV e mensurada a área infiltrada. O padrão de fratura foi avaliado através de imagens obtidas no MEV e classificados em: falha adesiva, coesiva em cimento, coesiva em dentina, coesiva em resina composta, coesiva em esmalte e mista. A análise estatística foi realizada utilizando os testes de normalidade Shapiro-Wilk e Kolmogorov Smirnov, ANOVA a dois fatores, teste paramétrico Bonferroni (post-hoc), com nível de significância de 5% (P <0,05), teste de correlação de Spearman. Resultados: a resistência à tração não foi estatisticamente diferente entre os grupos cimentados com resina composta e cerâmica. A cimentação da cerâmica não foi estatisticamente diferente entre os grupos (esmalte, 3,28 Pa; dentina, 3,14 Pa; resina, 2,85 Pa). A adaptação marginal foi estatisticamente diferente entre resina e cerâmica; a localização da linha de chegada variou entre esmalte e resina (175,91 µm vs. 433,58 µm). Para a nanoinfiltração foi estatisticamente diferente entre todos os grupos, exceto a resina: com resina (9,49%) e cerâmica (9,35%). Houve predomínio de falha adesiva em todos os grupos. Conclusão: a localização da linha de chegada pode ser realizada com segurança no esmalte e dentina. O substrato em resina composta apresenta uma alternativa promissora, mas ainda precisa ser mais estudado. Em relação ao material da coroa, é possível realizar uma restauração satisfatória tanto em resina composta quanto em cerâmica. Sendo a cerâmica, o material que apresentou melhores resultados. (AU)

Effect of two aging methods on the bonding interface between glass ceramics and dentin / 口腔疾病防治

Objective@#To study the effects of bacterial invasion and artificial saliva immersion on the bond strength and nanoleakage between healthy dentin and glass ceramics-bonded specimens using three types of resin cements and provide a reference for the selection of clinical bonding materials.@*Methods @#One hundred eight dentin blocks were selected to prepare bonded specimens with Variolink N, Multilink N, RelyX Unicem and glass ceramics blocks. The adhesive specimens of each type of resin cements were divided into three groups according to the aging method: bacterial invasiveness group (the specimens were cultured under anaerobic conditions for 14 days after inoculation with Streptococcus mutans), artificial saliva immersion group (the specimens were immersed in artificial saliva for 6 months), and control group (the immediate test group). Each group comprised 12 specimens: 6 were selected to test the bonding strength, and 6 were observed by scanning field emission scanning electron microscopy (FESEM). @*Results @#The bond strength of Variolink N in the immediate test group was significantly higher than that of Multilink N and RelyX Unicem, and the difference was statistically significant (P < 0.05). However, no significant difference was found in the bacterial invasiveness group and artificial saliva immersion group (P > 0.05). In the bacterial invasion group, the difference in the nanoleakage of the three adhesives was statistically significant (P < 0.05), with a trend of Variolink N > Multilink N > RelyX Unicem, and pairwise comparison was statistically significant (P < 0.05). The nanoleakage of the three resin adhesives showed an increasing trend in the bacterial invasion group and artificial saliva group compared with that of the immediate test group. @* Conclusion@#Both artificial saliva soaking and bacterial invasion can reduce the sealing property of the adhesive interface of 3 types of resin cements to different degrees. The presence of Streptococcus mutans in the oral cavity may reduce the sealing performance of the resin dentine adhesive interface.

Effect of dentin proteoglycans on the stability of resin-dentin bonds against artificial saliva storage / 中华口腔医学杂志

Objective@#To investigate the potential effect of proteoglycans (PG) and glycosaminoglycans (GAG) on the stability of resin-dentin bonds against artificial saliva storage.@*Methods@#Seventy-two extracted molars were used to obtain standard dentin bonding surface, and the specimens were etched for 15 s with 37% phosphoric acid and divided into three groups using a table of random number. Then the three groups undergone different incubating procedures as follow: specimens in chondroitinase ABC (C-ABC) group were incubated with C-ABC, specimens in trypsin (TRY) group were incubated with trypsin, and specimens in the control group were incubated with deionized water. All specimens were incubated at 37 ℃ for 48 h in the oscillators. Then specimens in each group were randomly assigned into three subgroups (n=8) as follows: immediate control subgroup, aging subgroups with artificial saliva storage for 6 months and 12 months. Microtensile bond strength (μTBS), fracture mode, bonding interface morphology and nanoleakage were evaluated.@*Results@#Immediately and with artificial saliva storage for 6 months and 12 mouths, the μTBS of TRY group ([49.04±3.57], [37.01±3.21] and [35.27±3.56] MPa) were significantly higher than those in the control group ([40.71±3.32], [28.87±2.34] and [24.20±2.07] MPa) (P<0.05). The immediate μTBS of C-ABC group ([32.94±2.45] MPa) was significantly lower than that of the control group (P<0.05). While with artificial saliva storage for 6 months and 12 mouths, the μTBS of C-ABC group ([26.46±2.45] and [22.50±2.58] MPa) were no differences with those of the control group (P>0.05). The ratio of cohesive fracture increased with the extension of aging time. Some narrow gaps were found in hybrid layer of the control group with artificial saliva storage for 6 months and 12 mouths.@*Conclusions@#Removal of PG increased the μTBS and durable bonds to dentin, while removal of GAG decreased the μTBS, however, it can be of help to create more durable bonds to dentin.

Evaluation of microshear bond strength and nanoleakage of etch‑and‑rinse and self‑etch adhesives to dentin pretreated with silver diamine fluoride/potassium iodide: An in vitro study.

Aims: The aim of this in vitro study was to comparatively evaluate the microshear bond strength (MSBS) of etch‑and‑rinse and self‑etch (ER and SE) bonding systems to dentin pretreated with silver diamine fluoride/potassium iodide (SDF/KI) and nanoleakage at the resin‑dentin interface using transmission electron microscope (TEM). Subjects and Methods: Seventy‑two dentin slabs of 3 mm thickness were prepared from extracted human permanent third molars and divided into four groups (n = 18) based on the dentin surface treatment as follows: (1) ER adhesive bonding without dentin pretreatment; (2) SDF/KI pretreatment of dentin followed by ER adhesive bonding; (3) SE adhesive bonding without dentin pretreatment; and (4) SDF/KI pretreatment of dentin followed by SE adhesive bonding. Resin composite was built on the dentin slabs to a height of 4 mm incrementally, and dentin‑composite beams of approximately 1 mm2 cross‑sectional area were prepared. The beams were subjected to MSBS analysis, and the fractured surface was observed under scanning electron microscope to determine the mode of failure. The resin‑dentin interface was examined under TEM for evaluation of nanoleakage. Statistical Analysis Used: One‑way ANOVA followed by Tukey’s post hoc multiple comparison tests. Results: Pretreatment of dentin with SDF/KI increased the MSBS of ER and SE adhesives, though not statistically significant, except between Groups 2 and 3. In all the groups, the predominant mode of failure was adhesive followed by cohesive in resin, mixed and cohesive in dentin. TEM examination of resin‑dentin interface showed that pretreatment with 38% SDF/KI reduced nanoleakage regardless of the type of bonding system used. Conclusions: Pretreatment of dentin with SDF/KI minimized nanoleakage at the resin‑dentin interface without adversely affecting the bond strength of resin composite to dentin.

Evaluation of adhesive systems in primary dentin by nanoleakage: effects of aging

Introduction: Nanoleakage evaluation by silver uptake in permanent teeth provides good spatial resolution of submicron defects at the hybrid layer, which have not been tested in primary teeth. Objective: This study evaluated the nanoleakage at the dentin-adhesive interface in primary teeth by two methods, for three adhesive systems, immediately (IM) and six months (6M) after adhesive procedures. Material and methods: Crowns of primary molars were occlusal flat grounded and divided into three groups according to the adhesive system tested (n = 6-7). Scotchbond Multi-purpose/SMP, Single Bond/SB and Clearfil SE Bond/CSB adhesive systems were applied with a composite resin (Filtek Z-250). Crowns were sectioned so that 0.8 mm² sticks were obtained and subdivided depending on the time of evaluation: IM or 6M. They were immersed into silver nitrate solution and evaluated by SEM-EDS. Data (%) were analyzed by ANOVA (p < 0.05) and the scores by Kruskal-Wallis and U Mann-Whitney tests (p < 0.05). Results: There was no difference between groups regarding to the evaluation time (aging) percentage. In terms of scores, there was a significant difference for the adhesive variable: SMP and SB showed similar results with less leakage, while CSB demonstrated higher leakage. Conclusion: Nanoleakage was not influenced by aging, but noticeable difference was observed between total-etch and self-etching adhesives. Total-etch showed better performance.

Effect of load cycling on nanoleakage of butt joint and beveled occlusal enamel margins in class V composite resin restorations / Efeito do ciclo de carga na nanoinfi ltração de margens de esmalte oclusal com e sem bisel em restaurações classe V

Objectives: This study evaluated the infl uence of mechanical and thermal cycling on the nanoleakageof Class V composite resin restorations with and without enamel beveling. Material and method:Using 60 Class V cavities prepared on the buccal surfaces of human molars, specimens were dividedinto two groups (n = 30) based on the confi gurations of the enamel cavosurface margins. (beveled andnon-beveled) After restoring the cavity preparations with a fl owable composite, half of the specimenswere mechanically load-cycled. The specimens were sealed leaving a 1 mm window around the cervicaland enamel margins. Specimens were placed in a 50% (W/V) silver nitrate solution then immersedin photodeveloping solution and exposed to fl uorescent light for 8h. The teeth were buccolinguallysectioned, gold sputter coated and examined with a SEM to evaluate the nanoleakage values. The datawere analyzed using two-way ANOVA (α = 0.05). Results: Enamel margin confi guration had no significant effect on nanoleakage (p > 0.05). However, the nanoleakage value was signifi cantly higher inthe load-cycled group than in the group not load-cycled (p < 0.05). Conclusion: Since enamel margin confi guration does not affect nanoleakage, there is no need to bevel enamel margins of Class V cavitypreparations for composite restorations.

Objetivos: O presente estudo avaliou a infl uência dos ciclos de carga mecânico e térmico na nanoinfi ltração derestaurações Classe V em resinas compostas, com e sem biselamento do esmalte. Material e método: Os espécimes(60 cavidades Classe V preparadas na superfície vestibular de molares humanos) foram divididos em dois grupos(n = 30) baseados nas confi gurações das margens cavosuperfi ciais do esmalte (biseladas e não biseladas). Após restauraçãodos preparos cavitários com um compósito tipo fl ow, metade dos espécimes foi carregada mecanicamente.Os espécimes foram selados mantendo janela de 1 mm em torno das margens cervical e de esmalte. Os espécimesforam colocados em solução de nitrato de prata (50%), imersos na sequência em solução processadora fotográfi cae expostos à luz fl uorescente por oito horas. Os dentes foram cortados em sentido vestíbulo-lingual, revestidos emouro e observados em microscopia eletrônica para avaliar os valores de nanoinfi ltração. Os dados foram analisadospelo ANOVA (α = 0,05). Resultados: A confi guração das margens do esmalte não teve efeito signifi cante nananoinfi ltração (p > 0,05). Entretanto, os valores da nanoinfi ltração foram signifi cativamente mais altos no grupode carga que no grupo sem carga (p > 0,05). Conclusão: Uma vez que a confi guração da margem do esmalte nãoafeta a nanoinfi ltração, não há necessidade de biselar as margens do esmalte nos preparos de cavidades Classe V emrestaurações de compósitos.

The nanoleakage patterns of experimental hydrophobic adhesives after load cycling / 대한치과보존학회지

The purpose of this study was: (1) to compare nanoleakage patterns of a conventional 3-step etch and rinse adhesive system and two experimental hydrophobic adhesive systems and (2) to investigate the change of the nanoleakage patterns after load cycling. Two kinds of hydrophobic experimental adhesives, ethanol containing adhesive (EA) and methanol containing adhesive (MA), were prepared. Thirty extracted human molars were embedded in resin blocks and occlusal thirds of the crowns were removed. The polished dentin surfaces were etched with a 35% phosphoric acid etching gel and rinsed with water. Scotchbond Multi-Purpose (MP), EA and MA were used for bonding procedure. Z-250 composite resin was built-up on the adhesive-treated surfaces. Five teeth of each dentin adhesive group were subjected to mechanical load cycling. The teeth were sectioned into 2 mm thick slabs and then stained with 50% ammoniacal silver nitrate. Ten specimens for each group were examined under scanning electron microscope in backscattering electron mode. All photographs were analyzed using image analysis software. Three regions of each specimen were used for evaluation of the silver uptake within the hybrid layer. The area of silver deposition was calculated and expressed in gray value. Data were statistically analyzed by two-way ANOVA and post-hoc testing of multiple comparisons was done with the Scheffe's test. Silver particles were observed in all the groups. However, silver particles were more sparsely distributed in the EA group and the MA group than in the MP group (p < .0001). There were no changes in nanoleakage patterns after load cycling.

Nanoleakage phenomenon on deproteinized human dentin

OBJECTIVE: The purpose of this study was to evaluate the influence of dentin deproteinization on the nanoleakage phenomenon. MATERIAL AND METHODS: Class V cavities were prepared in 12 human molars with cervical margins located in dentin. The cavities were assigned to 2 groups (n=6) according to dentin treatment: Group I - dentin treated in accordance with the manufacturer's instructions and Group II - dentin treated following the manufacturer's instructions + 10 percent NaOCl. Each group was sub-divided into three groups, according to the DBS (dentin bonding system) used: Scotchbond Multi Purpose (SBMP), Prime & Bond NT (PB) and Clearfil SE Bond (SE), which were applied according to manufacturer's instructions. The cavities were restored with composite resin, and the specimens were immersed in a tracer agent (AgNO3 50 percent) for 24 h. The teeth were sectioned buccolingually through the center of the restorations, and nanoleakage pattern was evaluated by scanning electron microscopy (SEM) using the backscattered electron image mode. RESULTS: SEM analysis showed different nanoleakage patterns for each DBS. Irrespective of dentin treatments, all SBMP specimens showed nanoleakage. SE did not show any nanoleakage with both dentin treatments used. PB showed nanoleakage within the hybrid layer only in Group I. CONCLUSIONS: The influence of dentin deproteinization on the nanoleakage phenomenon was dependent on dentin bonding system formulation and bonding strategies.

The effect of bonding resin on bond strength of dual-cure resin cements / 대한치과보존학회지

The objective of this study is to evaluate the effect of an additional application of bonding resin on the bond strength of resin luting cements in both the light-cure (LC) and self-cure (SC) modes by means of the microTBS tests. Three combinations of One-Step Plus with Choice, Single Bond with Rely X ARC, and One-Up Bond F with Bistite II were used. D/E resin and Pre-Bond resin were used for the additional application. Twelve experimental groups were made. Three mandibular 3rd molars were used in each group. Indirect composite blocks were cemented on the tooth surface. 1 x 1 mm2 dentin-composite beam for microTBS testing were made and tested. When total-etching dentin adhesives were used, an additional application of the bonding resin increased the bond strength (P 0.05). In conclusion, the results suggest that an additional application of the bonding resin increases bond strength and enhances quality of bonding when using total-etching dentin adhesives.

Effects of acid etching time on nanoleakage and microtensile bond strength of the adhesive-dentin bond / 实用口腔医学杂志

Objective: To observe the effects of acid etching times on nano-leakage and microtensile bond strength(?TBS) of the 4 total-etching adhesives-dentin bond.Methods: Superficial occlusal dentin surfaces of 80 molars were prepared with 600-grit SiC paper under running water.4 adhesives were applied to dentin surfaces under different etching time.The bonded teeth were sectioned occluso-gingivally into 1.0 mm?1.0 mm?4.0 mm serial slabs which were prepared for TEM and ?TBS tests.Results: Under 15 s etching time for 4 adhesives,the highest ?TBS(OB(25.36?4.18) MPa,SB(24.25?3.97) MPa,OS(28.65?4.93) MPa,PB(27.12?4.13) MPa) were achieved,and the amount of nanoleakage was positively correlated with the length of etching time.Conclusion: Etching for a reasonable time demineralizes the dentin surface to a moderate depth,resulting in higher ?TBS and lower nanoleakage.