银汞合金粘结修复后微渗漏及抗力性能的研究

目的 研究不同银汞合金粘结剂微渗漏及抗力性情况.方法 在新鲜离体牙上制备标准的Ⅰ类洞型并随机分为三组.在洞壁分别涂上牙本质树脂粘结剂、玻璃离子并建立空白对照组,冷热交替试验(4～60℃,循环600次),观察修复体与洞壁间边缘微渗漏的差异及抗压测试银汞合金或牙齿断裂时的压力.结果 玻璃离子和牙本质树脂粘结剂作为银汞合金粘结剂与对照组相比,能更好的减少微渗漏(P＜0.05),玻璃离子粘结剂能起到更好的封闭修复体边缘的作用(P＜0.01).两者与对照组相比都可以增大牙体承载的压力(P＜0.05),但两者之间差异无统计学意义(P＞0.05).结论 玻璃离子和牙本质树脂粘结剂作为银汞粘结剂都可以起到很好的边缘封闭作用,并能增大牙体的承受能力.     

2种单组份自酸蚀黏结剂在牙V类洞边缘微渗漏的对比研究

目的单组份自酸蚀黏结剂是最新一代牙科黏结剂,操作简便。为研究其对牙本质和牙釉质的黏结性能,文中将S3BOND与ibond用于Ⅴ类洞树脂充填,对其边缘封闭性进行比较。方法 10颗新拔除的磨牙随机分为2组,在颊舌面分别制备Ⅴ类洞,龈壁位于釉牙本质界下方,A组用S3BOND自酸蚀黏结剂,B组用ibond自酸蚀黏结剂,2组均用维纳斯前后牙通用型纳米树脂充填,2%甲苯胺蓝染色,从充填体正中剖开牙齿,观察每个充填体龈壁和颌壁边缘微渗漏情况。结果2组龈壁存在不同程度微渗漏,差异有统计学意义(P<0.05),而颌壁间差异无统计学意义(P>0.05)。A组龈壁与颌壁染色的差异有统计学意义(P<0.05),B组龈壁与颌壁染色的差异无统计学意义(P>0.05)。结论自酸蚀黏结剂S3BOND在牙本质的边缘封闭性优于ibond,在牙釉质的边缘封闭性虽低于ibond,但差异不显著。     

Marginal integrity and secondary caries of selectively excavated teeth in vitro

Objectives

Selective caries removal involves sealing of carious dentine beneath restorations, which might decrease their marginal integrity and increase the susceptibility for secondary caries and microleakage. The present study compared these marginal characteristics of restorations in selectively and completely excavated teeth.

Methods

In 32 premolars, shallow and deep artificial lesions were created on pulpo-axial walls of mesial-distal-occlusal cavities, with mesial and distal margins located in enamel and dentine, respectively. Demineralised dentine was either removed or left before adhesively restoring the teeth (n = 8), which were then submitted to thermo-mechanical cycling. The integrity of gingivo-cervical margins was assessed using scanning electron microscopy. In half of each margin, caries was induced adjacent to restorations using a continuous-culture biofilm model, and resulting lesions were evaluated using transversal microradiography. The other half of each margin was used to assess microleakage.

Results

Integrity or microleakage of margins located in enamel did not differ significantly between groups, and bacterial biofilms did not induce distinct caries lesions in enamel. Dentinal margins in teeth with deep compared with shallow lesions showed a significantly higher proportion of marginal imperfections, gaps and microleakage (p ≤ 0.05, Mann–Whitney/χ²-test). In contrast, neither marginal integrity nor microleakage differed significantly between completely and selectively excavated teeth (p > 0.05). Dentinal mineral loss adjacent to restorations did not differ significantly between groups (p > 0.80).

Conclusions

The marginal characteristics of restorations were affected by the depth of sealed or excavated lesions, but not by the performed caries excavation. This study did not find selective excavation detrimental for restoration integrity in vitro.

Clinical significance

Selective excavation of deep lesions was shown to reduce pulpal risks, whilst leaving caries beneath restorations is feared to compromise the marginal characteristics of the subsequently placed restoration. Based on the present in vitro study, such assumptions cannot be supported.     

固化光源光照方向和角度对微渗漏影响的研究

目的：研究固化光源光照方向及角度对复合树脂固化后微渗漏的影响。方法：选择63颗离体前磨牙,在颊面牙颈部以釉牙骨质界为中心制备圆形V类洞,常规酸蚀粘结,充填复合树脂,将所有实验牙以光源不同朝向随机分为A组：光源方向朝向龈壁;B组：光源方向朝向牙合壁;C组：光源方向朝向近中壁。再将A、B、C每组按固化光源与充填材料表面所成的角度不同随机分1组：成30°光照;2组：成60°光照;3组：成90°光照。所有实验牙均光照40s。分别浸泡于0.1%罗丹明B荧光染色剂中24h。然后经修复体中央,沿牙体长轴沿颊舌向纵向剖成两半,在激光扫描共聚焦显微镜（Laser Scanning Confocal Microscopy,LSCM）下分别观察检测微渗漏大小。结果：龈壁处的微渗漏情况：在光源的不同朝向下,不同的光照角度对龈壁处微渗漏的影响均具有统计学意义,光照角度均为90°时微渗漏值最小（P〈0.05）;牙合壁处的微渗漏情况：当光源朝向牙合壁及近中壁照射时,牙合壁处3组之间微渗漏有明显差异（P〈0.05）,光照角度90°时微渗漏最小;当光源朝向龈壁时,牙合壁处微渗漏之间没有明显的差异。结论：固化光源的光照方朝向及光照角度对微渗漏有影响。     

Influence of resin-based composite restoration technique and endodontic access on cuspal deflection and cervical microleakage scores

Objectives

To assess cuspal deflection and cervical microleakage of mesio-occlusal-distal cavities in standardised premolar teeth restored incrementally with resin-based composite (RBC) placed horizontally or obliquely and with endodontic access cavities (with and without gutta percha and epoxy resin sealer obturation).

Materials and methods

Thirty-two teeth were allocated to four groups (n = 8) and RBC restored in eight horizontal (Group A) or oblique increments (Groups B–D) using a quartz-tungsten-halogen light curing unit. The dependent variable for Groups B–D was endodontic access (none (Group B), obturated without (Group C) and with gutta percha and epoxy resin sealer (Group D)). Cuspal deflections were recorded post-irradiation using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in fuchsin dye, sectioned and examined for cervical microleakage.

Results

Tukey's post hoc tests identified a significant decrease in total cuspal deflection for the horizontal (p = 0.015) compared with the oblique placement technique. No significant difference in total cuspal deflection was evident between Groups B and D restored teeth (p > 0.318) or in cervical microleakage score between Groups A and D (p = 0.575).

Significance

Deformation is proportional to the cubed power of the length of a uniform cantilever beam and although a crude approximation of cuspal deformation, the reduction in the effective cusp length therefore significantly reduced the deflection in the MOD cavities when the horizontal rather than the oblique incremental restoration technique was employed.     

Effects of cavity preparation using a nanosecond-pulsed Nd-YAG laser on tooth-restoration interface

This study evaluated the tooth-restoration interface between composite resin or glass ionomer cement and the tooth surface in teeth where caries removal and cavity preparation were performed either with the dental drill, the dental drill and laser irradiation, or laser irradiation alone. A nanosecond-pulsed Nd-YAG laser was used at energy densities of 2–8 J cm^-2. After tooth restoration, microleakage tests were performed using methylene blue. Using general linear model procedures, no significant differences in microleakage were determined between ‘drill’ and ‘drill and laser’-prepared groups (p< 0.01) in resinand in glass-ionomer-restored teeth. These specimens showed significantly less dye penetration than the ‘laser only’ group (p< 0.0001). No correlation was found between fluence and microleakage using either restorative material (p = 0.8). Dye penetration was significantly greater in the composite-filled than in the glass-ionomer group (p< 0.05). Mechanisms influencing laser effects on bonding require further investigation before clinical application of lasers as an alternative to the dental drill can become viable.     

两种不同粘接系统在玻璃纤维桩修复中的临床效果

目的 比较两种不同粘接系统用于玻璃纤维桩核修复的临床效果.方法 选取136颗已行根管治疗的患牙随机分为自酸蚀Multilink N和自粘接RelyX Unicem两组,行玻璃纤维桩+全冠修复.分别在修复后进行随访观察,比较两组患牙的临床修复成功率.结果 修复后6、12、24月,两组成功率均在97%以上,且两组间比较差异无统计学意义(P>0.05).结论 Multilink N自酸蚀树脂水门汀和RelyX Unicem自粘接树脂水门汀用于粘接纤维桩均能获得良好的临床修复效果.     

不同根管充填技术对椭圆形根管的根尖封闭效果

目的 探讨采用不同根管充填技术对椭圆形根管根尖封闭效果的影响.方法 选取近期拔除的椭圆形单根管前磨牙120颗随机分成6组,每组20颗,采用iRoot-SP和AH-Plus根管封闭剂,结合单尖充填法、连续波热牙胶垂直加压充填法、冷牙胶侧方加压充填法,即单尖iRoot组、热牙胶iRoot组、冷牙胶iRoot组、单尖AH组、热牙胶AH组、冷牙胶AH组,采用染料渗透法观察根尖的微渗漏情况.结果 热牙胶iRoot组、热牙胶AH组的根尖染料渗入深度明显小于单尖iRoot组、单尖AH组(P<0.05);热牙胶iRoot组、冷牙胶iRoot组尖染料渗入深度明显小于热牙胶AH组、冷牙胶AH组(P<0.05);其他的组间两两比较差异均无统计学意义(P>0.05).结论 热牙胶垂直加压技术可以使椭圆形根管达到更好的根尖封闭效果,且配合使用iRoot SP根管封闭剂的封闭效果较配合使用AH-Plus根管封闭剂好.     

Dentin hypersensitivity and emerging concepts for treatments

Background

Dentin hypersensitivity is a relatively common pain symptom caused by evaporative, chemical, thermal, tactile, or osmotic stimuli. Despite its high prevalence, many aspects of dentin hypersensitivity remain unknown. Current treatments for dentin hypersensitivity include desensitizers and adhesive materials. Several factors that occur in the oral cavity, such as occlusal force and intrapulpal pressure, cause microleakage, the primary defect of adhesive treatments.

扫描电镜下三种流动树脂充填体边缘微渗漏研究

目的扫描电镜下观察比较三种流动树脂充填V类洞的微渗漏程度。方法在42颗离体的恒磨牙颊侧制备V类洞,随机分为3组,每组14颗牙。分别充填Filtek Z350流动性纳米复合树脂、Beautifil Flow流动型聚合体和Esthet.X流体复合树脂,样本经冷热循环及加压负载试验后,在扫描电镜下观察充填体龈壁边缘微渗漏情况。结果Z350流动性纳米复合树脂组充填体与牙体组织之间微缝隙宽度最窄,与Beautifil Flow流动型聚合体组、Esthet.X流体复合树脂组相比均有显著性差异(P0.01)。结论 Z350流动性纳米复合树脂适合用于牙颈部龋损的充填。