聚酰胺/纳米羟磷灰石复合生物材料盖髓封闭性能的体外实验研究

目的　比较新型聚酰胺 /纳米羟磷灰石复合生物材料 (PA/ n- HA)和硬质氢氧化钙 Dycal对体外新鲜健康恒牙穿髓孔的机械封闭能力。方法　采用新鲜拔除的人活髓牙共 6 4颗 ,随机均分为两组。模拟体内直接盖髓过程 ,通过髓腔内注入染液 ,体视显微镜下观察短时间根管内液体在穿髓孔处的微渗漏情况。结果　 PA/ n- HA组和 Dycal组发生渗漏牙数分别为 14颗和 2 2颗 ,差异有显著性 (P<0 .0 5 ) ;但在出现渗漏的牙齿中 ,其渗漏的严重程度两组无显著性差异 (P>0 .0 5 )。结论　 PA/ n- HA在体外对穿髓孔有较好的机械封闭能力 ,其作为盖髓剂较硬质氢氧化钙 Dycal与牙髓界面的微渗漏更小。     

Polymerization contraction stress in dual-cure cements and its effect on interfacial integrity of bonded inlays

Objectives. To compare the polymerization contraction stress of resin cements in dual-cure and self-cure modes, and verify its effect on microleakage and gap formation in class I cavities restored with porcelain inlays.

Methods. Dual-cure cements (Calibra, Choice and RelyX ARC) were monitored for contraction stress during 30 min in the tensilometer, in the presence or absence of photo-activation. Microleakage was evaluated in porcelain inlays bonded to cavities prepared in bovine incisors, combining the same adhesive (One-Step) with each of the cements in both activation modes. Epoxy replicas of the sectioned specimens were analyzed in the SEM to determine the percentage of discontinuous margins.

Results. The stress developed in dual-cure mode was higher than in self-cure mode for all cements. In self-cure mode, no significant difference in stress was found among materials. Choice and RelyX ARC showed higher microleakage in dual-cure mode than in self-cure mode. Calibra did not show a significant difference in microleakage between activation modes. Contraction gap results showed wide variations, and no significant differences were detected among the groups. Gaps occurred more often in dentin, with an overall average of 22±17.5%.

Conclusions. The higher stress generated in dual-cure cements subjected to photo-activation may lead to higher marginal leakage. In the confinement condition represented by the class I inlay, even the lower contraction stress of the cements in self-cure mode had enough magnitude to disrupt the bonding to dentin.     

Influence of operator skill on microleakege of total-etch and self-etch bonding systems

OBJECTIVES: To evaluate the influence of operator skill on microleakage in class V restorations using simplified bonding systems. METHODS: Two cavities were carried out on the buccal and lingual surfaces of 50 human bicuspid teeth. The teeth were randomly assigned to two groups according to the operator's skill: student group and expert group. The two cavities of each tooth were randomly treated with Adper Scotchbond 1 XT (total-etch adhesive) and Adper Prompt L-Pop (self-etch adhesive). All cavities were restored with a 0.2mm thick layer of flowable composite (Filtek flow) followed by one bulk increment of resin composite (Filtek Supreme XT). Specimens were thermocycled, immersed in 2% methylene blue and sectioned in a bucco-lingual plane. They were then examined under a stereomicroscope and scored according to microleakage. The data was subjected to a multilevel statistical model. RESULTS: At the dentine margin the microleakage resulting from both the self-etch adhesive and the total-etch one was similar in the student and in the expert groups. The interaction term skill x adhesive was not statistically significant (p=0.4156). At the enamel margin the self-etch adhesive microleakage within the student group resulted lower than that within the expert group. On the other hand, the total-etch adhesive microleakage within the expert group resulted lower than that within the student group. The interaction term skill x adhesive was statistically significant (p=0.0037). CONCLUSIONS: Both the adhesives used were sensitive to operator skill in obtaining a reliable seal with the enamel. On the dentine, both adhesives demonstrated little sensitivity to operator skill.     

自制透明硅胶导板在前牙树脂嵌体修复中的微渗漏研究

目的:研究自制透明硅橡胶导板在前牙微创美学修复中对树脂嵌体与牙体之间微渗漏的影响,以期为临床修复方法提供更丰富的选择及理论依据。方法:选择30颗离体前牙作为实验对象,按嵌体制作标准预备成Ⅳ类牙体缺损洞型,随机分为3组:A组(自制透明硅橡胶导板制作树脂嵌体);B组(传统硅橡胶导板制作树脂嵌体);C组为对照组(全酸蚀直接法树脂充填),其中A组嵌体借助透明硅橡胶导板辅助就位粘接,所有标本经冷热循环和染色处理后,体式显微镜下观察试件的微渗漏情况。结果:3组均产生了微渗漏,A、B两组的微渗漏值均较C组小(P＜0.05),有统计学意义。A组的微渗漏值略小于B组,但差异无统计学意义。结论:自制透明硅橡胶导板能够减少修复体与牙体之间的微渗漏。     

Influence of different restorative techniques on marginal seal of class II composite restorations

Objective

To evaluate the gingival marginal seal in class II composite restorations using different restorative techniques.

Material and Methods

Class II box cavities were prepared in both proximal faces of 32 sound human third molars with gingival margins located in either enamel or dentin/cementum. Restorations were performed as follows: G1 (control): composite, conventional light curing technique; G2: composite, soft-start technique; G3: amalgam/composite association (amalcomp); and G4: resin-modified glass ionomer cement/ composite, open sandwich technique. The restored specimens were thermocycled. Epoxy resin replicas were made and coated for scanning electron microscopy examination. For microleakage evaluation, teeth were coated with nail polish and immersed in dye solution. Teeth were cut in 3 slices and dye penetration was recorded (mm), digitized and analyzed with Image Tool software. Microleakage data were analyzed statistically by non-parametric Kruskal-Wallis and Mann-Whitney tests.

Results

Leakage in enamel was lower than in dentin (p<0.001). G2 exhibited the lowest leakage values (p<0.05) in enamel margins, with no differences between the other groups. In dentin margins, groups G1 and G2 had similar behavior and both showed less leakage (p<0.05) than groups G3 and G4. SEM micrographs revealed different marginal adaptation patterns for the different techniques and for the different substrates.

Conclusion

The soft-start technique showed no leakage in enamel margins and produced similar values to those of the conventional (control) technique for dentin margins.     

玻璃离子水门汀边缘封闭性的研究

玻璃离子水门汀作为齿科充填和黏结材料,以其优良的性能在口腔临床得到广泛应用。随着材料学的发展,出现了更适于临床应用的改良型玻璃离子水门汀。边缘封闭性是评价修复充填材料的重要标准,其好坏影响了黏结修复的稳定性。目前认为,改良型玻璃离子水门汀具有良好的边缘封闭性和更少的微渗漏,可以应用于口腔黏结修复。现就传统型和改良型玻璃离子水门汀及其在不同口腔黏结修复应用中的边缘封闭性进行综述。     

万能金相显微镜在牙体充填材料微渗漏研究中的应用

目的:定量观测玻璃离子在人离体牙充填后的微渗漏情况,比较传统型玻璃离子水门汀和树脂改性玻璃离子水门汀的边缘封闭性;试用万能金相显微镜为观测仪器,评价其应用效果.方法:选取新鲜无龋前磨牙,备洞,充填玻璃离子水门汀,37℃水浴条件下置于1%甲基蓝溶液浸染,万能金相显微镜下测量染液渗入深度,定量评价微渗漏程度.结果:在分别充填传统型玻璃离子水门汀和树脂改性玻璃离子水门汀的情况下,万能金相显微镜下测得的渗漏值分别为(27.11±6.23)μm和(26.92±5.02)μm,P>0.05,二者比较差异无统计学意义.结论:传统型玻璃离子水门汀和树脂改性玻璃离子水门汀充填后的边缘封闭性无显著差异;万能金相显微镜可用于牙体充填材料微渗漏的观测.     

过氧化氢酶对外漂白后树脂充填体边缘微渗漏的影响

目的： 观察过氧化氢酶对10%过氧化脲外漂白后复合树脂充填体边缘微渗漏的影响。方法： 选取牙体健康完整的人离体前磨牙40颗,随机分为4组,第1组不漂白直接进行树脂充填,第2组外漂白后立即树脂充填,第3组外漂白后将牙在人工唾液中浸泡3周再进行树脂充填,第4组外漂白后先用过氧化氢酶处理窝洞再进行树脂充填。然后将4组样本进行2000个周期的冷热循环,应用2%亚甲基蓝染色24 h,体视显微镜下观察剖面树脂充填体的微渗漏程度,采用SPSS17.0软件包对数据进行统计学分析。结果： 第1组微渗漏值最低,第2组微渗漏值最高,第3组微渗漏值显著高于第1组但与第2组相比无显著差异（P>0.05）;第4组微渗漏值较第2组显著下降（P<0.05）。结论： 10%过氧化脲外漂白致树脂充填体边缘微渗漏明显增加,树脂充填前应用过氧化氢酶处理窝洞,可有效减少微渗漏,延迟充填不能有效改善微渗漏。     

不同预处理方法对龋齿牙本质微渗漏和粘结效果的影响

目的:观察不同预处理方法对龋齿牙本质微渗漏和粘结效果的影响,为临床应用提供依据.方法:收集2020年1月-12月南昌大学附属口腔医院口腔颌面外科门诊拔除的离体有龋牙60颗,沿前体牙长轴正中磨为两半,获得120个牙样本.根据预处理方式不同分为A组(2％NaClO)、B组(2％氯己定)和C组(75％乙醇),比较3组牙体粘结...     

An in vitro evaluation of microleakage of resin based composites bonded to chlorhexidine-pretreated dentin by different protocols of a universal adhesive system

PurposeThis study compared microleakage of different resin based composite (RBC) materials bonded to dentin, after chlorhexidine (CHX) application, by different adhesion protocols of a universal adhesive system.MethodsClass V cavities were prepared on the buccal and lingual surfaces of 40 premolar teeth. The “etch-and-rinse” technique of a universal bond adhesive system (Single Bond Universal Adhesive) was used on buccal preparations, while the “self-etch” protocol was used on the lingual surfaces. Two RBCs, one bulk fill (Filtek Bulk Fill [FBF]) and one conventional (Filtek Z350 XT [Z350XT]), were used. Teeth were divided into two groups of 20 teeth each, 10 per each RBC (n = 10): (1) control; and (2) pretreatment with 2% CHX. For FBF groups, teeth were restored with a single increment; however, for Z350XT, a layering technique was used. Teeth were aged by thermo-cycling and prepared for microleakage testing. Dye penetration was evaluated and scored from 0 to 4. Data were analyzed at a significance level of P < 0.05.ResultsThe highest microleakage mean scores were found in the control group of the etched margins for both RBCs (2.80 ± 1.033 FBF and 2.10 ± 1.370 Z350XT). The CHX-pretreated group showed significantly lower microleakage than the control for FBF only (P = 0.008). No significant difference was found between groups for the “self-etch” protocol (χ² = 0.884, P = 0.08). No significant differences were found between FBF and Z350XT in all study groups (P > 0.2).ConclusionsWhen the “self-etch” protocol of the universal adhesive system was used, dentin microleakage was not affected by CHX-pretreatment when teeth were restored with bulk fill or conventional RBCs. In the “etch-and-rinse” protocol, CHX application improved the marginal seal before restoration with bulk fill material. However, in the absence of CHX, the “etch-and-rinse” protocol negatively affected marginal integrity.