Survival of resin-bonded porcelain veneer crowns placed with and without metal reinforcement

OBJECTIVES: The purpose of this retrospective case study of dental records was to compare the long-term failure rates and modes for resin-bonded sintered feldspathic porcelain veneer crowns (RBPVCs) either containing or without metal substructure reinforcement. METHODS: Two prosthodontists placed 62 RBPVCs fabricated with, and 167 without, metal reinforcement in 143 older adolescent and adult patients treated in a private practice. Clinical judgement determined the type of crown design placed. Preparation margins were generally finished on enamel, and all crowns occluded with opposing teeth. Observations included the patients, operators, crown designs and failure modes. Chi-square or Fisher's exact tests and life table survival statistics were used to evaluate the findings (alpha = 0.05). RESULTS: Over five years, failures occurred in 14.5% of RBPVCs fabricated with, and in 18.6% without, metal reinforcement. Cumulative survival estimates were 74.3 +/- 8.5(Standard Error)% and 72.9 +/- 4.8(SE)%, respectively (P = 0.96). Mandibular posterior crowns comprised 27.1% of the placements, but 47.5% of the failures. Bulk fracture of porcelain occurred in 7.0% of the crowns, all without metal reinforcement. Minor porcelain fractures and debonding were less frequent in both types of crowns. Persistent pulpitis occurred in 3.5% of all teeth. CONCLUSIONS: There was a significant risk of failure for sintered porcelain RBPVCs placed as posterior restorations. Although metal reinforcement was able to reduce the risk of bulk fracture of porcelain, other causes of failure were less affected.     

钛瓷反应层适宜厚度及元素构成分析

目的:检测钛瓷反应层适宜厚度及元素构成.方法:利用电子探针定点定量分析方法测量钛瓷反应层厚度及元素构成情况. 结果: 观测到钛元素摩尔百分比由87.92%到0.65%的6 μm反应层. 反应层由两层构成,一层钛、氧元素为主的钛氧固溶层,厚约3 μm;另一层为钛氧硅元素为主的富硅层,厚亦约3 μm. 结论: 3 μm的厚度可作为较适宜钛氧固溶层及富硅层厚度的参考标准. 钛瓷分界处钛、氧摩尔百分比约为1∶1,钛氧化层可能以TiO为主.     

金属加强结构对后牙4单位金属烤瓷固定桥强度的影响

目的比较不同桥体加强结构设计对烤瓷固定桥瓷层强度的影响,为临床使用合适的金属桥架设计提供参考。方法对C5、C6缺失采用C4-C7金属烤瓷双端固定桥模型,在烤瓷固定桥金属基底的舌侧设计点状和带状加强结构,以无加强结构设计作为对照,在桥体中央垂直于咬合面进行加载(速度0.5mm·min-1),记录饰面瓷破坏时的载荷以及破坏的形式。采用SPSS11.0软件进行统计分析,比较瓷层失败时的最大载荷值组间差异(α=0.05),并探讨不同设计组间瓷层破坏形式的差异。结果3种不同设计组发生瓷裂时的平均最大载荷分别为(0.87±0.06)kN(无加强结构)、(1.03±0.15)kN(点状加强结构)和(0.93±0.10)kN(带状加强结构)。无加强结构组与点状加强带组的最大载荷差异具有统计学意义(P<0.05),其他组间差异无统计学意义(P>0.05)。在瓷层破坏形式上,各组间没有明显的差异,瓷层破坏的位置几乎都是在加载点周围和近远中固位体的连接体部位。结论金属桥架舌侧连接体区的点状加强结构对烤瓷桥强度可以起到明显的增强效果。     

Complication and failure rates in patients treated for chronic periodontitis and restored with single crowns on teeth and/or implants

Objectives: To assess the biological and technical complication rates of single crowns on vital teeth (SC‐V), endodontically treated teeth without post and core (SC‐E), with a cast post and core (SC‐PC) and on implants (SC‐I). Material and methods: From 392 patients with chronic periodontitis treated and documented by graduate students during the period from 1978 to 2002, 199 were reexamined during 2005 for this retrospective cohort study, and 64 of these patients were treated with SCs. Statistical analysis included Kaplan–Meier survival functions and event rates per 100 years of object‐time. Poisson regression was used to compare the four groups of crowns with respect to the incidence rate ratio of failures, and failures and complications combined over 10 years and the entire observation period. Results: Forty‐one (64%) female and 23 (36%) male patients participated in the reexamination. At the time of seating the crowns, the mean patient age was 46.8 (range 24–66.3) years. One hundred and sixty‐eight single unit crowns were incorporated. Their mean follow‐up time was 11.8 (range 0.8–26.4) years. During the time of observation, 22 biological and 11 technical complications occurred; 19 SC were lost. The chance for SC‐V (56) to remain free of any failure or complication was 89.3% (95% confidence interval [CI] 76.1–95.4) after 10 years, 85.8% (95% CI 66–94.5) for SC‐E (34), 75.9% for SC‐PC (39), (95% CI 58.8–86.7) and 66.2% (95% CI 45.1–80.7) for SC‐I (39). Over 10 years, 95% of SC‐I remained free of failure and demonstrated a cumulative incidence of failure or complication of 34%. Compared with SC‐E, SC‐I were 3.5 times more likely to yield failures or complications and SC‐PC failed 1.7 times more frequently than did SC‐E. SC‐V had the lowest rate of failures or complications over the 10 years. Conclusions: While SCs on vital teeth have the best prognosis, those on endodontically treated teeth have a slightly poorer prognosis over 10 years. Crowns on teeth with post and cores and implant‐supported SCs displayed the highest incidence of failures and complications. To cite this article :
Schmidlin K, Schnell N, Steiner S, Salvi GE, Pjetursson B, Matuliene G, Zwahlen M, Brägger U, Lang NP. Complication and failure rates in patients treated for chronic periodontitis and restored with single crowns on teeth and/or implants
Clin. Oral Impl. Res. 21 , 2010; 550–557.
doi: 10.1111/j.1600‐0501.2009.01907.x     

一种序列3D打印导板引导的瓷贴面分区粘接技术

获得足够的釉质粘接是保证瓷贴面固位、边缘封闭及临床使用效果的共识性建议,牙体预备后,基牙的粘接面就确定下来。由于唇面釉质厚薄不均,常常存在或多或少的牙本质暴露,而分区识别粘接面上的釉质或牙本质（简称釉本）并采用“选择性酸蚀”使其获得最大粘接力的处理方式,将有助于提高瓷贴面的整体粘接强度。不同于以往“选择性酸蚀”裸眼识别釉本分区的不确定性和经验依赖,本技术方案通过第一个目标修复体空间定深导板控制预备深度,获得准确的釉本分区;并将其映射到第二个分区粘接导板里,依靠第二个导板分别对粘接面上的釉本进行不同处理,实现了精准的、可预期的瓷贴面的分区粘接,获得了更好的粘接效果。     

Influence of different light sources on microtensile bond strength and gap formation of resin cement under porcelain inlay restorations

Clinical success with ceramic inlays/onlays has been assisted by the ability to develop a reliable bond of composite resin to dental tissues. The purpose of this study was to test the efficiency of two different light sources on microtensile bond strength and the gap formation of resin cement under class II porcelain inlay restorations. Standardized mesio-occlusal cavities were prepared in 30 freshly extracted, intact human premolar teeth. Then impressions were made and ceramic inlays were fabricated. In the cementation process, the resin cement/inlay combinations were exposed to two different photopolymerization units. The polymerizations through 15 specimens were performed with a conventional halogen light source for 60 s, and the other specimens were cured by a plasma arc light for 9 s. After the cementation process, two 1.2 x 1.2 mm wide 'I' shape sections per tooth were produced with a sectioning machine and sections were subjected to microtensile testing after 24 h or 1 week. Gap formation of specimens cured by different photopolymerization units were evaluated with scanning electron microscopy (SEM). Statistically significant differences were found between the microtensile bond strength of inlays exposed to conventional light and plasma arc curing unit (P < 0.001). Plasma arc curing units make it possible to polymerize composite in much shorter times than conventional curing unit. However, the samples polymerized with conventional halogen light produced better microtensile bond strength than the plasma arc unit.     

Fractured incisors: a judicious restorative approach--Part 2

AIM: To consider different conservative options in the literature to restore fractured anterior teeth. MATERIALS AND METHODS: Only anterior tooth fractures not involving the pulp were considered, without limitation on age. Treatment options were chosen depending on the clinical situation of patients at first visit. The authors considered 15 cases each of: reattachment; porcelain veneers; direct composites. RESULTS AND CONCLUSIONS: The techniques analysed were revealed to be valid during the period of observation. No failures were recorded with vital teeth keeping their vitality and no radiographic signs of apical or root pathology. With reattachment, two cases have shown the visibility of fracture line after two years, depending on the angle of light incidence on the tooth surface. For direct restorations, three adult cases have shown partial discolouration at 24, 28 and 40 months. No fractures or debonding have occurred among porcelain veneers. The authors suggest, whenever possible, to utilise the reattachment technique. Direct restorations are suitable for young patients: they have a higher chance of sustaining further trauma than adults, and composites have a favourable failure mode compared to ceramics. In adults, where long-lasting restorations are needed, restoration with porcelain veneers is the treatment of choice.     

烤瓷用镍-铬合金金属氧化膜的研究

目的 分析国产Ｎｉ－Ｃｒ合金在烤瓷烧结条件下所生成的金属氧化膜的性能,探讨颈部灰线的成因。方法 应用Ｘ线衍射法与电子扫描法对国产Ｎｉ－Ｃｒ合金铸年经烤瓷烧结后,表现氧化膜的物相以及氧化膜与基体合金的成分进行分析;同时,应用俄歇电子能谱对经烤瓷烧结后与未经烤瓷烧结的铸件表现氧化膜的厚度、各元素变化趋势进行了分析研究。结果经烧结后的铸件表现氧化膜中主要有Ｃｒ２Ｏ３、ＮｉＣｒ２Ｏ４、ＳｉＯ２等氧化物及合