In vivo fractures of endodontically treated posterior teeth restored with enamel-bonded resin

The cumulative survival rate of 190 endodontically treated posterior teeth were assessed in a retrospective study; all teeth had an MO/DO or an MOD cavity restored with a composite resin without cuspal overlays after previous acid-etching of the enamel. In contrast to our previous study on endontically treated posterior teeth restored with amalgam, the survival rate of the MOD resin-restored teeth was equal to that of MO/DO teeth. Teeth restored with a light-activated resin had a much lower survival rate than teeth restored with a chemically-activated material, the cause presumably being that the light-activated resins were insufficiently irradiated. Nearly 25% of the teeth had been restored with a microfilled resin for anterior use and these teeth had a lower survival rate than had teeth restored with a macrofilled or hybrid resin. It was also found that a beveling technique did not decrease the fracture rate while the use of an intermediate layer of low-viscosity resin resulted in a significant improvement.     

In vivo fractures of endodontically treated posterior teeth restored with amalgam

Abstract The cumulative survival rate (retention of both cusps) and the fracture pattern of 1639 endodontically treated posterior teeth were assessed in a retrospective study. All teeth had an MO/DO or an MOD cavity restored with amalgam without cuspal overlays. The 20-year survival rate of teeth with an MO/ DO cavity was markedly higher than that of teeth with an MOD cavity. The lowest survival rate was found for the upper premolars with an MOD cavity: 28% of these teeth fractured within 3 years after endodontic therapy, 57% were lost after 10 years, and 73% after 20 years. Generally, the cusp most prone to fracture was the lingual one, and lingual fractures caused significantly more damage to the periodontal tissues than did facial or total crown fractures. The severity of periodontal damage increased with posterior location of the tooth. By far the most serious failures, irrespective of the cavity type, were found for the upper second molar, as 10 of 29 fractures led to extraction. It is concluded that amalgam, especially in MOD cavities, is an unacceptable material for restoration of endodontically treated posterior teeth if used without cuspal overlays.     

In vivo fractures of endodontically treated posterior teeth restored with amalgam

The cumulative survival rate (retention of both cusps) and the fracture pattern of 1639 endodontically treated posterior teeth were assessed in a retrospective study. All teeth had an MO/DO or an MOD cavity restored with amalgam without cuspal overlays. The 20-year survival rate of teeth with an MO/DO cavity was markedly higher than that of teeth with an MOD cavity. The lowest survival rate was found for the upper premolars with an MOD cavity: 28% of these teeth fractured within 3 years after endodontic therapy, 57% were lost after 10 years, and 73% after 20 years. Generally, the cusp most prone to fracture was the lingual one, and lingual fractures caused significantly more damage to the periodontal tissues than did facial or total crown fractures. The severity of periodontal damage increased with posterior location of the tooth. By far the most serious failures, irrespective of the cavity type, were found for the upper second molar, as 10 of 29 fractures led to extraction. It is concluded that amalgam, especially in MOD cavities, is an unacceptable material for restoration of endodontically treated posterior teeth if used without cuspal overlays.     

Resistance to fracture of restored endodontically treated teeth

Abstract Endodontically treated teeth were restored by 8 different methods. Copper rings were filled with commercial hard setting cement and the teeth were placed into the cement to the level of the cemento-enamel junction. The teeth were grouped according to restorative methods, mounted in an Instron T.T. machine and subjected to a slowly increasing compressive force until fracture occurred. The force of fracture for each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner, irrespective of restorative method used. Preparation of a post space in the roots significantly weakened the teeth. Cementation of a steel parapost with zinc oxyphosphate cement did not significantly strengthen the teeth. Filling the post space and the access cavity with a composite resin following acid etching of the root canal and cavity walls strengthened the teeth more than other methods used to restore them. This finding may be of clinical importance, for instance in the restoration of endodontically treated young teeth with incomplete root formation and wide root canals.     

Evaluation of fracture resistance of endodontically treated teeth restored with composite resin along with fibre insertion in different positions in vitro

This study was carried out to compare the different techniques of placement of polyethylene fibre (Ribbond) on reinforcement of endodontically treated teeth with MOD cavities in vitro. Forty extracted human premolars were randomly assigned to four groups (n = 10). Teeth in Groups I–IV received root canal treatment and a MOD cavity preparation, with gingival cavosurface margin 1.5 mm in coronal to cementoenamel junction. Group I served as no fibre group, Group II as occlusal fibre group, Group III as base fibre group and Group IV as dual‐fibre group (occlusal and base both). Subsequent to restoring with composite resin and thermocycling, a vertical compressive force was applied at a cross‐head speed of 0.5 mm min^?1 using universal testing machine until fracture. Data were analysed using one‐way analysis of variance and Tukey's post hoc tests. Fracture resistance was significantly highest in dual‐fibre group (P < 0.001) as compared with other groups. The highest favourable fracture rate was observed in the base fibre group (70%). This study concluded that the use of polyethylene fibre inserted over or under the restoration significantly increased the fracture strength of the root canal‐treated teeth and maximum fracture resistance was observed when cavity was restored using dual‐fibre technique.     

Resistance to fracture of restored endodontically treated premolars

Abstract Endodontically treated premolars were restored using 5 different methods. Copper rings were filled with commercial hard-setting cement and the teeth were placed into the cement up to the level of the cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instron TT machine and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. The resistance to fracture of the teeth increased significantly when MOD cavities in the teeth were acid etched prior to the restoration with a composite resin. The use of a bonding agent after acid etching did not further increase the resistance to fracture of the premolars restored with a resin. The acid etch composite resin technique was as effective in preventing fractures of the teeth when 2 mm of the resin was removed and replaced with an amalgam as when the entire cavities were filled with the resin material.     

可塑纤维桩修复对根管治疗牙抗折强度的影响

目的比较不同桩修复离体牙对修复体整体抗折强度的影响。方法将32颗上颌前磨牙行根管治疗并从唇侧釉牙骨质界上2 mm处截断后随机分为4组,A组采用镍铬金属铸造桩核加铸造冠修复,B组采用Tenax FiberWhite纤维桩、树脂核加铸造冠修复,C组采用EverStick可塑纤维桩单根（直径1.5 mm）、树脂核加铸造冠修复,D组采用EverStick可塑纤维桩双根（直径1.5 mm和1.2 mm）、树脂核加铸造冠修复。所有离体牙均由自凝树脂包埋,电子万能试验机加载头与牙体长轴成45°,以1 mm/min的加载速度加载直至试件任何部分折裂,记录读数并观察修复体折裂模式。结果A、B、C、D组间修复体的整体抗折强度差异无统计学意义（P>0.05）。各纤维桩组牙体折裂位置较铸造桩更接近牙颈部。结论尽管可塑纤维桩自身的弯曲强度较低,但是修复离体牙后整体抗折强度较高,可以满足临床要求。各纤维桩组折裂模式较铸造桩组更有利于修复体失败后的再修复。     

磨牙根管治疗后直接充填修复效果的3年临床评价

目的:评价磨牙根管治疗后直接充填修复的临床效果及影响因素。方法:采用回顾性研究的方法,回访检查磨牙根管治疗后直接充填修复3年的牙体和充填物状况,对修复效果和可能的影响因素进行分析。结果:269个磨牙牙体充填修复3年成功率为68.8%。对不同类型牙体缺损的修复效果进行比较发现,剩余牙体组织最多的Ⅰ型缺损成功率最高,为75.8%,剩余牙体组织最少的Ⅲ型最低,为51.6%,三者存在显著性差异(P<0.05)。比较不同充填材料的修复效果,银汞合金充填组的成功率在Ⅰ型缺损略低于树脂充填组,Ⅱ、Ⅲ型缺损均高于复合树脂充填组,且Ⅱ型缺损比较两者存在显著性差异(P<0.05)。结论:牙体缺损的大小影响直接充填的修复效果;对Ⅰ型缺损的磨牙,无论选用何种充填材料,均可获得较好的修复效果。     

两种桩系统修复对根管治疗牙强度的影响

目的比较两种不同弹性模量的桩系统对根管治疗牙修复后强度的影响。方法20颗近期拔除的完整人上颌中切牙,根管治疗后随机分成两组,每组10颗。组一进行玻璃纤维桩ParaPost Fiber white(Coltene/ whaledent Inc)、复合树脂核及铸造全冠修复。组二进行铸造镍铬桩核及铸造全冠修复。每组牙均保留1.5mm的牙本质肩领(Ferrule)。实验标本包埋于自凝树脂块中,固定在DCS5000材料试验机上。加栽头以1mm/min的速度,与牙长轴成130°进行加载直至标本断裂。断裂强度采用独立样本t检验,断裂方式采用Fisher’s精确概率法(P <0.05)。结果组一断裂强度为43.406±18.959kg,组二33.680±9.675kg,差异无显著性(P>0.05)。可修复性断裂方式见于玻璃纤维桩核,而不可修复性的破坏多见于铸造镍铬桩核组(P<0.001)。结论在牙体预备保留1.5mm牙本质肩领(Ferrule)的情况下,两种不同弹性模量的桩对根管治疗牙桩核加全冠修复后的强度影响无差异,可修复性的破坏见于弹性模量与牙本质近似的玻璃纤维桩组。     

根管治疗后牙体修复的治疗方案选择

冠部修复的质量是影响根管治疗后患牙预后的重要因素之一。如何根据患牙的具体情况选择最适合的修复方式,一直以来存在争议。本文介绍了根管治疗后冠部修复的目的与时机,选择修复方式需考虑的因素及具体修复方案的选择等,对近年来关于根管治疗后牙齿修复的研究进展进行分析,旨在为临床决策提供指导。     

Fracture resistance and stress distribution in endodontically treated maxillary premolars restored with composite resin.

PURPOSE: The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. MATERIALS AND METHODS: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.5 mm/min. Fracture patterns were analyzed at four levels. Five 2D numerical models were created by Ansys 10.0 for finite element analysis (FEA). RESULTS: Mean values of compressive strength for all groups were (Kgf): G1 (83.6 +/- 25.4); G2 (52.7 +/- 20.2); G3 (82.1 +/- 24.9); G4 (40.2 +/- 14.2); G5 (64.5 +/- 18.1). Statistical analysis (ANOVA and Tukey's test) showed that fracture resistance of G1 was significantly higher than that of G5, G2, and G4. Resistance of G3 was also higher than that of G2 and G4. Results showed that the tooth resistance is completely maintained when MOD preparation is restored with composite resin and partially recovered when MOD preparation associated with an endodontic access is restored in the same way. The endodontic treatment and composite resin restoration influenced stress distribution in the dental structure. CONCLUSIONS: Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.     

两种桩系统修复对根管治疗牙强度影响的有限元应力分析

目的比较两种不同弹性模量的桩修复对根管治疗牙应力分布的影响。方法建立根管治疗后的上颌中切牙分别采用玻璃纤维桩树脂核及铸造镍铬桩核修复的二维有限元模型，牙体预备均保留1．5mm的牙本质肩领。分析受力后的应力分布规律。结果不同材料的桩修复会在根管治疗牙牙根内产生明显不同的应力分布形式。玻璃纤维修复时牙根内的应力分布与天然牙近似，并且整体应力水平较低。铸造镍铬合金桩修复改变了天．然牙原有的应力分布形式，在桩一牙本质界面和桩末端出现了明显的应力集中。结论在选择桩的材料时要考虑其对根管治疗牙应力分布的影响。在保证牙颈部的强度和边缘密合性的同时，选择与牙本质弹性模量相近的桩可以减少根折的可能。     

应用釉质成形预防性树脂修复年轻恒牙畸形中央尖的临床观察

目的观察釉质成形预防性树脂修复法预防年轻前磨牙畸形中央尖折断的临床效果,并与一次性磨除间接/直接盖髓后树脂修复法作一比较。方法选择口内前磨牙畸形中央尖对称性萌出且未达咬合平面的患儿20例,62颗患牙,随机分为两组:釉质成形预防性树脂修复组(即树脂加固组)和一次性磨除间接或直接盖髓后树脂修复组,每组各31颗患牙,随访观察1年。结果釉质成形预防性树脂修复组未发现有失败病例,一次性磨除组31颗患牙中有4颗失败,成功率为87.10%,二者差异无统计学意义(P>0.05)。结论早期发现畸形中央尖患牙,并在其未达咬合平面之前应用釉质成形预防性树脂修复方法加固畸形中央尖,可以有效预防畸形中央尖的折断,保证其牙根正常发育。     

Restoration of the endodontically treated posterior tooth

ObjectivesTo analyse the key factors of the restoration in the posterior endodontically treated teeth, through a literature review and clinical cases presentation. To focus on the clinical advantages of the adhesive indirect restorations, describing the basic principles for long-term success.Materials and methodsThe biomechanical changes due to the root canal therapy and the degree of healthy dental tissue lost because of pathology and iatrogenic factors are the critical points leading the clinician to the restorative treatment planning. The full crown is considered by the literature as the gold standard and is indicated in case of teeth heavily weakened by dental caries, fractures or previous conservative-prosthetic preparations. The improvement of the adhesion and the composite materials, with mechanical properties close to those of dental tissues, offers to the clinician the option of a conservative restoration, able to seal, reinforce and protect the tooth and to delay the execution of a full crown, with the subsequent sacrifice of dental tissue. Although in the presence of small-sized cavity, direct bonded restoration is considered an effective short and medium-term restoration, cuspal coverage with indirect restoration is the treatment of choice in case of mesio-occlusal-distal cavities. Adhesive overlays preserve coronal structure, avoid contamination of the root canal system, reinforce residual dental tissues, guarantee optimal form, function, aesthetics and offer ergonomic and economic undoubted clinical advantages.Results and conclusionsDirect adhesive restorations, indirect bonded restorations and traditional full crown are three therapeutic options for the single posterior endodontically treated teeth. The amount of remaining sound tooth structure is the most significant factor influencing the therapeutic approach. The clinician's operative skill is a determining aspect for long-term success of adhesive inlays.     

Prevalence of vertical root fractures in extracted endodontically treated teeth

AIM: The aim of this study was to evaluate the prevalence of vertical root fractures (VRF) in extracted endodontically treated teeth and to correlate the findings to previous studies and surveys. METHODOLOGY: Root-canal-treated teeth were referred for extraction from a public dental clinic. The endodontic therapy had been completed by a variety of dentists. Each tooth was evaluated following extraction by the oral surgeon who performed the procedure: the exact aetiology for the clinical diagnosis that led to the extraction was recorded. RESULTS: The major reasons for extraction were restorative (43.5%) and endodontic (21.1%), followed by vertical root fractures (10.9%). CONCLUSIONS: The relatively high prevalence of vertical root fractures in this survey compared with previous clinical and radiographic surveys was probably related to the difficulties in making a clinical diagnosis of vertical fractures before extraction.     

In vivo cusp fracture of endodontically treated premolars restored with MOD amalgam or MOD resin fillings

The frequency of cusp fracture of endodontically treated premolars was investigated in a retrospective study. After endodontic therapy, the teeth were either restored with a MOD amalgam filling, or with an enamel-bonded MOD resin filling. A very high frequency of cusp fracture was found in premolars restored with amalgam: nearly one-third fractured within 3 years after endodontic treatment. The frequency of cusp fracture differed among the 4 amalgam-restored teeth; the lower first premolar had a 15-year survival rate of 74%, in contrast to an average of 32% for the other 3 premolars. No resinrestored premolar fractured during the first 3 years, and the difference between amalgam and resin-restored teeth was highly significant at the 0–3 year interval. However, fracture of resin-restored premolars did happen in the following 3–10 year interval. From a periodontal point of view, a low frequency of cusp fracture carries great weight, and it is therefore concluded that an enamelbonded resin filling may be a treatment option much preferred to amalgam in temporarily restoring endodontically treated premolars with MOD cavities.     

Targis高嵌体修复无髓后牙缺损的观察

目的：考察Targis瓷聚体作高嵌体修复无髓后牙缺损的临床效果。方法：对47例患者的53个经完善根管治疗术的后牙缺损，采用Targis高嵌体修复。根据改良的USPHS修复体评价标准，分别于修复后1、2,3年对Targis高嵌体进行随访复查。结果：Targis高嵌体的颜色协调性、边缘适合性和边缘着色在观察期内无明显改变，也未见继发龋和余留牙体的折裂，其累计成功率为94．3％。结论：Targis瓷聚体用于无髓后牙缺损的高嵌体修复效果良好，为牙体缺损的美观修复提供了新的选择，但其远期效果有待进一步观察。