Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

Objectives:

To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine.

Material and Methods:

A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer''s instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37º C, and sectioned into resin-dentin bonded sticks (0.8 mm²⁾ and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers'' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey''s tests (α=0.05).

Results:

The duplication of the conditioning time favored only the GO adhesive (p<0.05). Both application methods significantly increased the tubule area opening (p<0.05) compared to the controls.

Conclusions:

The efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested.     

自酸蚀与全酸蚀粘接剂对牙釉质和牙本质的剪切粘接强度比较

目的 比较自酸蚀与伞酸蚀粘接剂对牙釉质和牙本质剪切粘接强度,以期为临床提供参考.方法 选择因牙周病拔除的上颌中切牙20颗,使用两种自酸蚀粘接剂[A(ClearfilTM Protect Bond)、B(AdporTM PromptTM)]和两种全酸蚀粘接剂[C(SwissTEC SL Bond)、D(Single Bond)]按照厂家推荐步骤对牙釉质和牙本质进行粘接,并测试牙釉质和牙本质粘接样本的剪切粘接强度.结果 4种粘接剂对牙釉质和牙本质粘接强度分别为:粘接剂A(25.33±2.84)、(26.07±5.56)MPa;粘接剂B(17.08±5.13)、(17.93±4.70)MPa;粘接剂C(33.14±6.05)、(41.92±6.25)MPa;粘接剂D(22.51±6.25)、(21.45±7.34)MPa.粘接剂C对牙釉质和牙本质剪切粘接强度显著高于其他3种粘接剂(P<0.05);粘接剂B的剪切粘接强度显著低于其他3种粘接剂(P<0.05).结论 本研究所选用的自酸蚀两步法粘接剂的剪切粘接强度与部分伞酸蚀粘接剂相当,高于自酸蚀一步法粘接剂.     

牙本质表面状态对丙酮基粘结剂强度和界面的影响

目的：研究干燥或湿润的牙本质表面状态对丙酮基粘结剂粘结强度和粘结界面微观结构的影响，并探讨粘结强度和粘结界面微观结构之间的内在联系。方法：选用3种含有丙酮的湿粘结系统Gluma One-Bond、Bond-1和One-Step，将Chrisma树脂分别粘结在干燥或湿润的人牙本质表面，测试各组试件的微拉伸强度，并用扫描电镜观察和比较各组试件粘结界面超微结构的异同。结果：湿粘结时，粘结剂对牙本质表面的渗透较为充分，混合层均匀，厚度约为5μm，并可观察到牙本质小管和侧支小管中有明显的树脂突形成；干燥粘结时，形成的混合层变薄，并有不完全渗透的混杂层形成。干燥粘结时，3种粘结系统的微拉伸强度均有显著降低，下降幅度最高为39％，微拉伸破坏的方式主要是粘结界面的破坏。结论：含有丙酮的粘结系统在干燥粘结时，对牙本质表面的渗透性下降，微拉伸强度明显降低；微拉伸强度的测试，可以更客观地反映粘结强度的大小。     

Calcium leaching from dentin and shear bond strength after etching with phosphoric acid of different concentrations

Based on the H2O-P2O5-CaO phase diagram, we hypothesize that a phosphoric acid concentration around 27 wt% leaches most calcium from dentin. We also hypothesize that bond strength is affected by resin infiltration, and that resin infiltration becomes incomplete when calcium leakage exceeds a certain value. Dentin disks were cut from human molars. Eight phosphoric acid concentrations were prepared (15.7-51.2 wt%). For each acid group, there were four etch time subgroups (15, 30, 60 and 120 s). The dentin disks were etched in acid and rinsed in water for times corresponding to 15 s, 30 s, 60 s and 120 s. The calcium concentrations were analyzed using atomic absorption spectroscopy. Composite cylinders were bonded to the remaining parts of the teeth using the same etching protocol, and shear bond strength was determined. The 29.2 wt% group demonstrated the highest and the 15.7 wt% group the lowest calcium leaching value. Even though there were trends towards lower bond strength for longer etch times, a statistically significant difference was only found between 30 and 120 s. There was no significant correlation between calcium leaching and bond strength. The results support the tested hypothesis that the highest leaching value would be around 27 wt% phosphoric acid.     

牙本质表面状态对酒精-水基粘接剂强度和界面影响的微拉伸及LSCM研究

目的 :研究干燥或湿润的牙本质表面状态对酒精 -水基粘接剂粘接强度和粘接界面微观结构的影响 ,并探讨粘接强度和粘接界面微观结构之间的内在联系。方法 :选用两种含有酒精和水的湿粘接系统OptiBondSolo和SingleBond ,将Chrisma树脂分别粘结在干燥或湿润的人牙本质表面 ,测试各组试件的微拉伸强度 ,并在激光扫描共聚焦显微镜下观察和比较各组试件粘接界面超微结构的异同。结果 :湿粘接时粘接剂对牙本质表面的渗透较为充分 ,混合层均匀 ,厚度约为 5 μm ,并可观察到牙本质小管和侧支小管中均有明显的树脂突形成 ;干燥粘结时形成的界面形态与湿粘接时没有明显区别。干燥粘接时 ,两种粘接系统的微拉伸强度均有显著降低 ,下降幅度最高为 2 3 % ,微拉伸破坏的方式主要是粘接界面的破坏。结论 :含有酒精和水的粘接系统在干燥或湿润粘接时粘接界面的超微结构变化不明显 ,其中的水分对干燥的牙本质表面有再湿润效果 ;干燥粘结时微拉伸强度则有明显的降低 ;微拉伸强度的测试可以更客观的反映粘接强度的大小。     

Influence of duration of phosphoric acid pre‐etching on bond durability of universal adhesives and surface free‐energy characteristics of enamel

The purpose of this study was to evaluate the influence of duration of phosphoric acid pre‐etching on the bond durability of universal adhesives and the surface free‐energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no‐pre‐etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre‐etching groups were prepared: enamel pre‐etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free‐energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre‐etched showed significantly higher SBS and surface free‐energy values than the specimens that had not been pre‐etched, regardless of the aging condition and adhesive type. The SBS and surface free‐energy values did not increase for pre‐etching times of longer than 3 s. There were no significant differences in SBS values and surface free‐energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre‐etching of enamel improves the bond durability of universal adhesives and the surface free‐energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre‐etching times of longer than 3 s.     

Five-year clinical evaluation of universal adhesive applied following different bonding techniques: A randomized multicenter clinical trial

ObjectivesTo evaluate the clinical performance of a universal adhesive system (Futurabond U, Voco) when applied following different adhesive strategies in non-carious cervical lesions (NCCLs) after 5 years.MethodsFifty participants were included. Futurabond U (Voco) was applied in NCCLs using four adhesive strategies (n = 50 each): only self-etch (SE); selective enamel etching + self-etch (SET + SE); etch-and-rinse with dry dentin (ERD); and etch-and-rinse with wet dentin (ERW). All cavities were restored with Admira Fusion composite resin (Voco). Restorations were evaluated after 1, 3, and 5 years using the World Federation criteria (FDI) and the modified United States Public Health Service (USPHS) criteria.ResultsAfter 5 years, retention rates were 81 % (65.8–90.5) for SE, 87 % (73.2–94.4) for SET + SE, 84 % (69.6–92.6) for ERD, and 78 % (63.6–88.9) for ERW (p > 0.05). Thirty-five restorations were considered to have minor discrepancies in marginal adaptation at the 5-year recall (14 for SE, 9 for SET + SE, 6 for ERD, and 6 for ERW; p > 0.05). Sixteen restorations were detected as a minor marginal discoloration (6 for SE, 4 for SET + SE, 1 for ERD, and 5 for ERW; p > 0.05) and one restoration showed a recurrence of caries (1 for ERW; p > 0.05) at the 5-year recall. No restorations showed postoperative sensitivity after 5 years.SignificanceNCCLs restorations using a universal adhesive showed satisfactory clinical performance after 5 years, regardless of the adhesive strategy.