Effect of surface treatment on etched procelain bond strength to enamel

The purpose of this study was to evaluate the effect of mechanical retention by etching and chemical bonding by silanizing porcelain surfaces on their shear bond strength to etched enamel. The individual contributions of the two processes were compared with the bond strength obtained by the combined treatment. The effect of applying fit-checker paste to etched porcelain surface was also examined before and after re-etching. The 5 groups were compared between Mirage shade A₂ (N=25) and Mirage shade 65 (N=25) porcelains. Following surface treatment of porcelain and resin bonding to etched enamel, the specimens were thermocycled 600 times between 5° and 55°C and debonded in shear mode. Results indicated that, overall, Mirage shade 65 porcelain was twice as strong as Mirage shade A₂. However, the 5 treatment groups for each shade showed remarkable similarity, with the highest bond achieved by both etching and silanizing the porcelain. The bond strength from etching or silanizing alone was not significant. Use of a fit-checker paste lowered the bond strength, possibly by chemical contamination. There was no evidence of physical obliteration of the microporosities on the etched surface with the use of a silane coupling agent or the fit-checker if removed completely. It was concluded that optimum bond strength of porcelain to etched enamel is obtained by both etching and silanizing the surface. Caution should be exercised when using a silicone-based fit-checker paste. Further study is recommended.     

Preliminary surface analysis of etched, bleached, and normal bovine enamel

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.     

Surface analysis of etched molar enamel by gas adsorption

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson's Correlation Coefficient showed a lack of relationship between etch pattern and total surface area.     

激光与磷酸刻蚀牙釉质表面粗糙度及剪切力的比较

目的 :对激光和磷酸刻蚀牙釉质进行比较 ,探讨激光刻蚀是否可作为酸蚀牙釉质表面的一种替代方法。方法 :以 42颗离体上颌双尖牙作为研究标本 ,对其唇面牙釉质表面分别进行不同能量的激光刻蚀和 37%磷酸刻蚀处理 ,同时模拟光固化治疗。体视显微镜和扫描电镜下观察牙釉质表面粗糙度及形态特征 ,以CL -C测力仪对光固化材料粘结强度的剪切力进行测试。结果 :牙釉质表面粗造度与激光能量密度呈正相关性。pps2 0Hz 75～ 87mj条件下的激光刻蚀 ,其粘结力、微形态学改变等均较接近磷酸刻蚀的程度。结论 :pps2 0Hz 78～ 87mj条件下的激光刻蚀可以作为磷酸刻蚀牙釉质表面 ,增加粘结固位力的另一种替代方法。     

An X-ray crystallographic study on effect of acid etching method to enamel and enhancement of crystallinity of the etched enamel with gel method

With the purpose of studying the influence of enamel acid etching technique, and the effectiveness of a strengthening of tooth enamel by silicahydro gel method, the following groups were compared, analyzed and observed by the measurements of diffracted X-ray from thin layer specimens and by microarea X-ray diffraction from an X-ray crystallographic point of view. Group I: non-treated tooth enamel Group II: acid-etched tooth enamel Group III: tooth enamel by application of silicahydro gel method after being acid etched. The results obtained were as follows: 1. Qualitative analyses by the measurements of diffracted X-ray from thin layer specimens 1) Ca5(PO4)3F, Ca5F (PO4)3 and Ca3(PO4)2.xH2O were detected in every group, and Ca3(PO4)2.xH2O demonstrated a high reliable value in group III. 2) In comparison with groups I and II, group III clearly revealed a peak shift toward high angle side, however, a halo peak was not recognized in every group. 3) As a result of evaluating crystallinity, crystallinity became favorable in order of group II, group I and group III. 4) A-axis lattice constant shortened in order of group II greater than group I greater than group III, and c-axis lattice constant shortened in order of group II greater than group I = group III. 2. Qualitative analyses by microarea X-ray diffraction 1) Solid solution of Ca5(PO4)3F and Ca5(PO4)3(OH) proved to exist in every group and in each microarea. 2) A halo peak appeared in group II and showed the trend of disappearance in group III, however, no peak shift was observed in all groups. From the foregoing results, the loss of the utmost enamel surface layer exhibiting high crystallinity and the lowering of crystallinity by acid etching technique were revealed from an X-ray crystallographic point of view and furthermore if silicahydro gel method was applied, it was suggested that enamel would be restored or that crystallinity would be enhanced.     

Contralateral symmetry of acid etched enamel surfaces

abstract — Scanning electron microscopy (SEM) of phosphoric acid etched labial enamel surfaces of human permanent incisors and canines showed that the etch pattern, including the depth of the etched relief, may vary significantly from tooth to tooth and between different areas of the same tooth. On the other hand, pairs of contralateral teeth showed a very similar etch pattern symmetrically along the midline. No difference in the pattern could be found in enamel etched with three different orthophosphoric acids: 50% with 7% ZnO, 37%, and 35%. Therefore, when comparing the depth of penetration of different coldcuring restorative resins, composite or non-composite, into the etched enamel relief, it seems appropriate to study these materials two-by-two on pairs of contralateral teeth.     

The effect of washing water on bonding to etched enamel

There is current concern about bacterial contamination of dental unit waterlines. This research hypothesized that the presence of increasing concentrations of bacteria in water used to wash etched enamel would result in a corresponding decrease in both shear bond strength (SBS) and critical surface tension (gammaC) of enamel. A further hypothesis was made that there is a correlation between SBS and gammaC. The effect of 3.5 ppm iodine in the water as a bacteriostatic agent was also assessed. Five groups of 10 samples of bovine enamel were etched, washed, and a resin composite bonded to them. The control group was washed with distilled water. Another group was washed with the dilute iodine solution. The remaining three groups used a different concentration of Escherichia coli DH5alpha as follows (in cfu mL(-1)): group 1: 10(2); group 2: 10(4); group 3: 10(6). Shear bond strength data were measured on an Instron testing machine at a crosshead speed of 1 mm min(-1). Adhesion data were (MPa): control: 24.6 +/- 6.0; with iodine: 20.8 +/- 2.7; group 1: 19.8 +/- 2.7; group 2: 13.5 +/- 3.0; group 3: 13.9 +/- 3.6. The F-test yielded a highly significant difference between control group, iodine group and group 1, compared with groups 2 and 3 (P < 0.0001). Tukey's Studentized Range Test was used for pairwise comparison testing between groups. Using a Cahn dynamic contact angle analyzer and linear regression analysis, the plots of surface tension versus costheta were extrapolated to costheta = 1 to give gammaC data for the control group and groups 1-3. In all cases reasonable linearity was observed (r2 > or = 0.87). Data (mN m(-1)) were: control group: 50.8; group 1: 45.1; group 2: 43.2; group 3: 39.5. The SBS and gammaC were then plotted against each other and linear regression analysis performed. It was concluded that increasing concentrations of bacteria in wash water decreased both SBS and gammaC and that a linear correlation (R2 = 0.84) was found between the values of these two parameters.     

釉质酸蚀后牙面脱矿与再矿化的扫描电镜观察

目的:观察牙釉质酸蚀后在离体状态下和一段时间内在口腔环境中的结构变化,探讨牙釉质脱矿与再矿化的形态学改变.方法:选择因正畸需要拔除健康第一前磨牙病例10例,40个牙,使用YY0269-1995型酸蚀剂对拟拔除的第一前磨牙颊侧釉质酸蚀60 8,左侧上、下颌第一前磨牙为A组,A组再分为A1、A2组,A1组酸蚀后即刻拔除,制作扫描电镜观察标本,A2组,第一前磨牙酸蚀后即刻拔除,置37℃恒温蒸馏水中浸泡1个月后制作电镜标本观察.右侧上、下颌第一前磨牙为B组,第一前磨牙酸蚀后在口内存留1个月后拔除,用相同的方法进行观察,并比较A、B两组牙釉质形态学变化.结果:A组的牙釉质表面松软,不规则,多孔隙,表面呈蜂窝状改变;B组的牙釉质表面有大量矿物质沉积,孔隙变小,矿化物颗粒细小,沉积不均匀.结论:牙釉质脱矿后,在口腔环境中可发生再矿化,但矿化程度是有限的,提示在临床上应注意酸蚀时间及酸蚀范围.     

The adaptation of composite materials to etched enamel surfaces

The adaptation of three composite materials and one unfilled bis-GMA resin to etched enamel surfaces was investigated by examining under optical and scanning electron microscopy the adhesive-enamel junction of replicas. The length of the tags and the density of tagging observed on the replicas showed that the three composite materials, Adaptic, Concise and Delphic, adapted to the etched enamel surface equally as well as the unfilled resin Nuva Seal. The results of this study together with available results of mechanical testing and clinical studies allow the conclusion that the successful retention of the composite filling materials to an etched enamel surface is not dependent on the use of an intermediate unfilled resin or bonding agent.     

Three-dimensional aspects of etched enamel in non-erupted deciduous teeth

Acid etching with phosphoric acid on the prismless layer of human dental enamel may produce different patterns of dissolution. Consequently, the presence of several patterns of enamel acid conditioning may indicate better or worse formation of resin tags. In this study, the heterogeneous patterns of 35% phosphoric acid conditioning of human non-erupted deciduous teeth were reported. SEM images demonstrated type I, type II and type III aspects reported by Silverstone et al. (Caries Research 1975; 9:373-387), in spite of the etching time used and the surface area (buccal incisal, middle or cervical thirds). These characteristic features on the enamel surface may indicate the convenient use of this technique in deciduous teeth.     

美白凝胶及酸性饮料对离体牙釉质结构的影响

目的:观察漂白剂对牙齿脱矿的作用.方法:分别用Beyond美白胶贴片、可乐、橙汁在人工唾液中浸泡离体牙,经过即刻,7天,14天后分别用扫描电镜观察分析表面形貌和Ca/P含量变化,显微硬度仪检测釉质改变.结果:处理后3组样品的即刻Ca/P比值和平均显微硬度均降低,且明显小于对照组(P＜0.05);7天后逐渐提高,14天后与对照组差异无统计学意义(P＞0.05).橙汁组的Ca/P比值和平均显微硬度在处理后即刻处理组内对比中略小于漂白和可乐组.结论:漂白剂对人牙釉质有一过性脱矿作用,随着时间推移,釉质可再矿化而修复;漂白剂引起的脱矿与日常饮用的酸性饮料比较属于正常脱矿范围.