渗透性树脂对树脂修复体微渗漏影响的实验观察

目的:观察使用渗透性树脂ICON对修复体边缘进行处理后的微渗漏变化。方法:20颗健康离体牙随机分为2组,颊面制备深度2mm的窝洞,Z350树脂充填,A组使用渗透性树脂ICON处理树脂修复体边缘处的牙体组织及树脂牙体结合处,B组为对照组。37℃水浴条件下分别置于0.1%罗丹明B荧光染料浸染,24h后激光扫描共聚焦显微镜测量染液渗入深度,定量评价微渗漏程度,对检测结果进行统计学分析。结果:A、B组微渗漏差异有统计学意义(P<0.05)。结论:渗透性树脂对改善树脂修复体微渗漏状况有明显效果。     

A randomized double-blind clinical trial of posterior composite restorations with or without bevel: 1-year follow-up

Objective

This randomized double-blind clinical trial compared the performance of posterior composite restorations with or without bevel, after 1-year follow-up.

Material and Methods

Thirteen volunteers requiring at least two posterior composite restorations were selected. Twenty-nine cavities were performed, comprising 14 without bevel (butt joint) and 15 with bevel preparation of the enamel cavosurface angle. All cavities were restored with simplified adhesive system (Adper Single Bond) and composite resin (Filtek P60). A halogen light curing unit was used through the study. Restorations were polished immediately. Analysis was carried out at baseline, after 6 months and after 1 year by a calibrated evaluator (Kappa), according to the FDI criteria. Data were statistically analyzed by Mann-Whitney test (p<0.05).

Results

Beveled and non-beveled cavities performed similarly after 1 year follow-up, regarding to fractures and retention, marginal adaptation, postoperative hypersensitivity, recurrence of caries, surface luster and anatomic form. However, for surface and marginal staining, beveled cavities showed significantly better performance (p<0.05) than butt joint restorations.

Conclusions

It was concluded that the restorations were acceptable after 1 year, but restorations placed in cavities with marginal beveling showed less marginal staining than those placed in non-beveled cavities.     

The effect of temperature changes on adaptation of resin fillings. II

In earlier laboratory investigations of thermal percolation at resinous fillings the duration of the heating periods was too long to be realistic. The aim of the present work was to investigate the effect of repeated heatings of realistic duration on the formation of marginal gaps between filling and tooth during a subsequent cooling below the minimum value in the temperature cycling process. Fillings made in extracted human teeth were studied. The brands investigated were Adaptic, Blendànt, Concise, Opotow, Sevriton Simplified, and Swedon. After closure of the initial gaps by water absorption expansion the fillings were polished and subjected to thermal cycling. The specimens were cycled between either 37° and 50° C or 37° and 60° C, the duration of each immersion in the warmer bath was 2 or 5 seconds, and the number of cycles was 1, 10, 100 or 1000. The effect of the cycling was investigated by measuring the width of marginal gaps appearing at a temperature lower than 37° C. It was found that the width of the gaps was only little affected by thermal cycling between 37° and 50° C. Cycling between 37° and 60° C increased the gap widths only with Opotow, Sevriton Simplified, and Swedon. The data indicate that thermal percolation for a number of brands may be of no clinical importance.     

口腔修复用钛锆铌锡合金研制及铸造性能研究

目的：研制口腔修复用钛锆铌锡（Ti-12.5Zr-3Nb-2.5Sn）合金,并评价合金铸造加工性能。方法：制备Ti-Zr-Nb-Sn合金,采用国产LZ5型离心铸钛机铸造试样,测试合金的铸流率,铸造反应层和线收缩率。结果：400℃时铸造,合金铸流率为100%,铸造线收缩率,表面反应层满足修复支架的铸造要求。结论：Ti-12.5Zr-3Nb-2.5Sn合金具有良好铸造加工性能,可满足口腔修复材料的临床应用要求。     

外伤前牙即刻种植美学修复的临床研究

目的：观察前牙外伤后即刻种植关学修复的临床效果。方法：前牙外伤根折患者25例,共植入牙种植体36枚,其中21例（30颗）行不翻瓣种植,4例（6颗）行翻瓣骨引导再生种植技术,术后1周行临时粘结桥修复,3个月后行二期手术,制作由种植体支持的螺丝固位型修复体,对种植体周围软组织挤压塑形。戴用时间为3个月左右,使其逐渐达到类似天然牙的穿龈轮廓和外形,之后采用个性化转移杆技术将种植体周围软组织形态精确转移到石膏模型上,制作最终修复体。定期随访1～3年,观察修复体周围软组织美学情况及种植体骨结合状况。结果：所有种植体美学情况良好,均发生了良好的骨结合,种植体存留率100%,患者均较满意。结论：前牙外伤后采用即刻种植关学修复,具有治疗周期短、早期恢复美观及功能等优点,是一种良好的修复方法。     

复合树脂多色分层美学修复用于Ⅳ类洞的美学探讨

目的:应用多色分层复合树脂修复前牙Ⅳ类洞,观察其美学修复效果。方法:选取40颗Ⅳ类洞患牙,先经牙体预备,而后制备硅橡胶背板,比色,粘结,多色分层树脂修复,最后进行咬合调整,精细抛光,分别于术后1周、3、6、12、24月复查修复体充填效果。结果:36例充填体在24个月内的各项评价指标均达到临床满意的美学效果。结论:多色分层复合树脂修复前牙牙体,在较少磨除牙体组织的同时取得较好的临床美学效果。     

牙齿重度磨耗伴牙列缺损咬合重建固定义齿修复的临床观察

目的：观察临床重度磨耗伴牙列缺损咬合重建应用固定义齿修复的临床效果。方法：选取2009～2011年在我院收治的牙齿重度磨耗伴牙列缺损患者31例,根据患者口腔健康环境,在适宜的时间先后对其进行咬合重建与固定修复。修复6个月、1年、2年,对患者进行随访观察患者口颌生理功能,义齿固位、稳定情况,面容、牙齿、牙龈美观情况。结果：经过咬合重建以及固定义齿修复后,患者义齿的固位良好,咀嚼、发音功能,牙齿、面容美观显著改善,牙周及咀嚼肌群疲劳均有明显好转。结论：通过对患者进行咬合重建以及固定义齿修复治疗后,对改善患者的咀嚼、发音功能、颜面美观以及口颌系统其他功能均有良好疗效,值得进行医疗推广。     

The cross‐pin retained implant supported restoration: a study of gasket placement and leakage

Background: Advantages of cross‐pin retained implant supported restorations (ISRs) include predictable retrieval and predictable retention. Unlike direct to fixture (DTF) or cement retained restorations, the prosthetic design of a cross‐pinned restoration retains gaps at the interfaces between the crown, abutment and cross‐pin screw. These spaces permit leakage into the suprastructure and gasket placement has been recommended to prevent this leakage. Methods: Five different gaskets were assessed for their ability to prevent leakage into a cross‐pinned ISR. The gaskets tested were: cement admixture on the cross‐pin screw; cement admixture on the inner surface of the coping and the cross‐pin screw; cement admixture on the inner surface of the coping only; cement admixture placed 1 mm from the margin of the coping and a filler placed in the abutment chimney. Results: Only gaskets which sealed both the cross‐pin screw interface and the abutment‐crown interface prevented leakage. A filler placed in the abutment chimney prevented leakage into this space but did not prevent fluid accumulating between the coping and abutment. Conservative placement of cement at the margin of the coping failed to prevent leakage. Conclusions: Cement gaskets may effectively prevent leakage into a cross‐pinned ISR. However, the use of a cement as a gasket has to be weighed against the issue of predictable retrieval, cement extrusion and incomplete seating.     

Numerical analysis of the biomechanical behaviour of a weakened root after adhesive reconstruction and post-core rehabilitation

Objectives

The purpose of this study was to perform a finite element analysis to determine whether adhesive reconstruction is able to restore the original biomechanical behaviour of weakened roots, in terms of fracture resistance, when compared with post/crown-restored teeth with intact roots.

Methods

A three-dimensional model of a maxillary central incisor was created. The model simulated an endodontically treated tooth restored with a glass-fibre post, a composite-resin core and a metal crown (Model 1). Based on Model 1, a new volume was created in the root cervical third that represented the area where the dentine structure was lost, resulting in a structurally damaged root (Model 2). A 100 N load was applied to the palatal surface at 130° from the long axis of the tooth. After processing (Ansys^® 10.0 – Canonsburg, PA, USA), the principal normal stress data were analyzed (S1, tensile; S3, compressive).

Results

The models demonstrated a similar S1 distribution concentrated in the lingual cervical region but different S1 levels (Model 1: 28.7 MPa; Model 2: 35.3 MPa). The S3 distribution indicated differences in behaviour between the models (Model 1: −18 to −27 MPa along the buccal root surface; Model 2: −25 to −32 MPa on the post buccal surface and along the buccal root wall).

Conclusions

Although the stress distribution within the root walls remained below the ultimate stress limit of the root dentine, the adhesive reconstruction of the weakened roots did not recover the load resistance of structurally intact roots.

Clinical significance

The decision of when to prosthetically rehabilitate weakened roots with cervical dentine structural tissue loss is a challenge for clinicians. A ‘monoblock’ adhesive reconstruction has been proposed for root reinforcement. During treatment planning, the possibility of restoring the mechanical resistance of the root must be evaluated if successful long-term results are to be achieved.