An evaluation of microbial coronal leakage in the restored pulp chamber of root-canal treated multirooted teeth

This in vitro study investigated the effect of a resin-reinforced glass ionomer lining material on the coronal leakage of a mixed obligate microbial marker in maxillary molars obturated with lateral condensation of cold gutta-percha and Tubliseal sealer, after 2 years' storage. Forty maxillary first molars were prepared chemomechanically to a size 30–40 master apical file. The teeth were divided into an experimental group (30 teeth) and control group (10 teeth). In the experimental group, the floor of pulp chamber and the root-canal opening of 15 teeth were covered with Vitrebond as a lining; the remaining 15 teeth received no lining. These teeth were tested for leakage using a microbiological marker consisting of anaerobic streptococci and Fusobacterium nucleatum . The teeth were checked daily for bacterial leakage for 60 days. All positive control teeth leaked within 48 h, while the negative control teeth remained uncontaminated throughout the test period. The teeth restored with Vitrebond liner showed no leakage whilst 60% of the specimens with no Vitrebond liner showed leakage after 60 days.     

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.     

Fracture resistance of endodontically treated teeth restored with composite posts

STATEMENT OF PROBLEM: The most recent application of fiber-reinforced composites involves their use as post and core systems to restore endodontically treated teeth. Even though this last application has been advertised and used clinically by many dentists, there is very little information regarding the physical properties of these post systems. PURPOSE: The purpose of this study was to compare the effect of 3 fiber-reinforced composite post systems on the fracture resistance and mode of failure of endodontically treated teeth. MATERIAL AND METHODS: Ninety maxillary central incisors were divided into 8 experimental groups and 1 stainless steel (ParaPost) control group of 10 specimens each. Eighty teeth were assigned to 2 main experimental groups called "narrow" and "flared" canals. For the narrow canal group, post spaces were prepared with the corresponding reamer to restore the teeth with FibreKor, Luscent anchors, and Ribbond posts of 1.5 mm, 1.6 mm, and 2.0 mm in diameter, respectively. For the flared canals group thin-walled canals were simulated. Teeth for the flared canals were restored with the same posts but were cemented into tapered 2 mm wide canals created with a tapered diamond bur. Prefabricated posts (FibreKor and Luscent anchors) for narrow and flared canals were cemented with an autopolymerized resin cement and a flowable composite, respectively, whereas customized Ribbond posts were luted with a light-polymerized flowable composite for both canal types. An additional set of 20 Ribbond posts with coronal portions of variable size and shape referred to as "Ribbond nonstandardized" were also prepared and evaluated. Specimens were loaded to failure (kg) with a universal testing machine at a crosshead speed of 0.05 cm/min until failure occurred. Data were analyzed with analysis of variance and Student t tests (P<.05). RESULTS: Statistical analysis revealed no significant difference between flared and narrow canals in mean load to failure between the post systems except for the Ribbond posts (P<.01). For the narrow canal, the mean load ranged from a low of 4.55 (+/-1.49) kg for the Ribbond standard to a high of 12.9 (+/-1.64) kg for the Luscent anchors. For the flared canal the low mean was 9.04 (+/-1.76) kg for FibreKor and the high was equal for both Luscent anchors and Ribbond standard, 12.87 (+/-2.69) and 12.87 (+/-3.54), respectively. Overall, the ParaPost control group had the highest load value (18.33 +/- 3.27 kg) (P<.05). Ribbond nonstandardized had a mean load to failure of 24.91 (+/-11.53) Kg for the narrow canal group and 31.95 (+/-11.98) kg for the flared canal. Results from these groups were excluded from the statistical analysis because of the uncontrolled core sizes and high standard deviations. No root fractures occurred in any of the experimental groups. CONCLUSION: Results from the study show that the load to failure of the stainless steel posts were significantly stronger than all the composite posts studied. However, the mode of failure or deflection of the fiber-reinforced composite posts is protective to the remaining tooth structure.     

预成钛合金螺纹桩保留残根的临床修复观察

目的观察钛合金螺纹桩对残根残冠的修复效果。方法对2002年~2009年5月份期间采用钛合金螺纹桩加双固化树脂核修复的病例进行复诊观察并用预定标准评价修复效果。根据患牙的牙位、余留牙体组织量、桩与牙根的直径比及桩在根管内的密合程度对复诊的病例进行分组比较。结果复诊病例共40例,有49颗修复牙,门诊复诊病例23例共25颗修复牙。失败病例中桩折断两例,桩脱落三例。失败病例均发生在余留牙体组织量不理想组。结论螺纹桩在余留牙体组织量理想的情况下可以获得满意修复效果,在牙体缺损较多的情况下修复效果欠佳。     

Coronal leakage inhibition in endodontically treated teeth using resin-coating technique

The purpose of this study was to evaluate coronal leakage inhibition using a resin-coating technique after endodontic treatment. Thirty-six human incisors were cut at the cementoenamel junction, and endodontic obturations were performed. The specimens were randomly divided into three groups according to post space preparation (10 mm depth), resin coating, and temporization. For the resin coating, the dentin surface was coated with either a combination of Clearfil SE Bond and Protect Liner F (SE/PLF) or RZII (RZ). Then, the specimens were stored in 37 degrees C distilled water for 24 hours and placed in 1% methylene blue solution for 48 hours. After which, the specimens were sectioned faciolingually along the root canal and the length of dye penetration was measured from the cementoenamel junction. Three-way ANOVA revealed that the dye penetration scores were influenced by post space preparation, resin coating, and temporization. Resin coating with RZ significantly reduced the dye penetration score and SE/PLF completely eliminated dye penetration.     

Fatigue resistance of endodontically treated teeth restored with three dowel-and-core systems

STATEMENT OF PROBLEM: The successful restoration of endodontically treated teeth is enhanced by a crown design employing the ferrule effect. However, it is unclear which dowel-and-core system most effectively supports successful treatment. PURPOSE: The purpose of this study was to compare the load fatigue resistance of 3 dowel-and-core systems. MATERIAL AND METHODS: Fifteen endodontically treated maxillary central incisors were sectioned perpendicular to the long axis at a point 1.5 mm incisal to the cemento-enamel junction (CEJ). At the level of the CEJ, specimens were then prepared for crowns with 1-mm complete shoulder finish lines and 1.5 mm of axial wall height. The prepared teeth were divided into 3 groups (n=5) and restored with 1 of the following dowel-and-core combinations: Group CG, cast gold dowels and cores; Group TA, titanium alloy dowels (ParaPost XH) with composite cores; or Group FR, fiber-reinforced resin dowels (ParaPost FiberWhite) with composite cores. A dentin bonding agent (OptiBond Solo) was placed prior to the composite cores. Dowel-and-core castings and titanium alloy dowels were cemented with zinc phosphate cement. The fiber-reinforced dowels were cemented with a resin cement (ParaPost Cement). The crowns for all specimens were cast with an incisal notch for applying the fatigue load. The independent variable measured was the number of load fatigue cycles required to cause luting cement failure. The data were subjected to 1-way analysis of variance and the Student-Newman-Keuls test for 3 subsets (alpha=.05). RESULTS: The mean value+/-standard deviation for the cycles to failure for each group was: Group CG: 11,897+/-4080 load cycles, Group TA: 24,384+/-8231 load cycles, and Group FR: 50,696+/-7063 load cycles. Significant differences were found between all groups ( P<.05). CONCLUSIONS: Fiber-reinforced resin dowels and bonded composite cores under fatigue loading provided significantly stronger crown retention than cast gold dowels and cores and titanium alloy dowels with composite cores under fatigue loading.     

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.     

Fatigue resistance of restored endodontically treated teeth: a multiparametric analysis

PURPOSE: To evaluate the failure patterns of teeth restored with both cast metal and fiber posts after fatigue cycling. MATERIALS AND METHODS: Thirty-five crownless human teeth subdivided into 5 groups were subjected to 2 x 106 100-N fatigue cycles at 8 Hz under 37 degrees C water. RESULTS: No root fatigue fractures were recorded. High microleakage values were found in specimens that survived fatigue. No statistically significant relationships were found for fatigue (P > .4), fracture strength (P > .8), and microleakage (P > .1). CONCLUSIONS: Cast-metal and fiber posts undergo insidious microscopic adhesive failures at similar levels. Increasing the post diameter and/or post stiffness could improve the core stabilization.     

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.     

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.     

Resistance to fracture of endodontically treated teeth restored with different post systems

STATEMENT OF PROBLEM: Very little is known about the resistance to fracture of endodontically treated teeth restored with newly developed esthetic post systems. Purpose. This in vitro study compared the effect of 1 titanium and 3 esthetic post systems on the fracture resistance and fracture patterns of crowned, endodontically treated teeth. MATERIAL AND METHODS: A total of 40 recently extracted human maxillary canines with their crowns removed were endodontically treated. Four groups of 10 specimens were formed. Teeth were restored with titanium, quartz fiber, glass fiber, and zirconia posts and numbered as groups 1, 2, 3, and 4, respectively. All posts were cemented with Single Bond dental adhesive system and dual-polymerizing RelyX ARC adhesive resin cement. All teeth were restored with composite cores, and metal crowns were fabricated and cemented with glass ionomer cement. Each specimen was embedded in acrylic resin and then secured in a universal load-testing machine. A compressive load was applied at a 130-degree angle to the long axis of the tooth until fracture, at a crosshead speed of 1 mm/min. One-way analysis of variance and a Tukey test were used to determine the significance of the failure loads between groups (P<.001). A non-parametric chi(2) test was conducted for evaluation of the mode of failure (P<.001). RESULTS: The mean failure loads (kg) were 66.95, 91.20, 75.90, and 78.91 for groups 1 to 4, respectively. Teeth restored with quartz fiber posts (group 2) exhibited significantly higher resistance to fracture (P<.001) than the other 3 groups. Teeth restored with glass fiber and zirconia posts (groups 3 and 4) were statistically similar (P>.05). Fractures that would allow repair of the tooth were observed in groups 2 and 3, whereas unrestorable, catastrophic fractures were observed in groups 1 and 4 (P<.001). CONCLUSION: Within the limitations of this study, significantly higher failure loads were recorded for root canal treated teeth restored with quartz fiber posts. Fractures that would allow repeated repair were observed in teeth restored with quartz fiber and glass fiber posts.     

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。     

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

Abstract 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.     

Fracture resistance of endodontically treated anterior teeth restored with four post-and-core systems.

OBJECTIVE: The purpose of this study was to evaluate the fracture resistance and the mode of failure of endodontically treated teeth restored with four post-and-core systems. METHOD AND MATERIALS: Forty intact human incisors were randomly divided into four groups. Teeth from each group received endodontic therapy and one of four post-and-core systems: serrated, parallel-sided, cast post and core; serrated, parallel-sided, prefabricated post and resin-composite core; carbon-fiber-reinforced (CFC) post and resin-composite core; and ceramic post and resin-composite core. A full-coverage metal crown was fabricated and cemented onto each tooth. Each specimen was subjected to a compressive load at a 45-degree angle to its axis until failure. The failure load was recorded and compared statistically. The mode of failure of the specimens was analyzed. RESULTS: There was no significant difference in the failure loads among groups. More catastrophic root fracture was detected in the group restored with ceramic posts and resin-composite cores. CONCLUSION: The fracture resistance of endodontically treated teeth restored with these four post-and-core systems could be accepted clinically. Unfavorable tooth fracture was shown in all groups.     

Fracture resistance of endodontically treated teeth restored with three different prefabricated esthetic posts

Purpose: This study was undertaken to evaluate the role of composition of prefabricated esthetic posts in fracture resistance of endodontically treated teeth in vitro. Materials and Methods: Thirty human, single‐rooted teeth (maxillary central incisors and canines) with similar root dimensions, extracted for therapeutic reasons, were used in this study. The crowns were removed below the cementoenamel junction to obtain a standard root length of 17 mm. The roots were endodontically treated following the conventional manual technique and randomly assigned to three groups (n = 10) according to the post used: Aestheti‐Post, Bisco, Schaumberg, Illinois; FibreKor Post, Jeneric/Pentron, Wallingford, Connecticut; and CosmoPost, Ivoclar Vivadent, Schaan, Liechtenstein. The root canals were rendered patent, and the root preparations were standardized through flaring with the manufacturers' drills included in the respective kits. The posts were cemented with an adhesive system and a resin cement (All‐Bond 2 and C & B, Bisco, respectively), according to the manufacturers' directions. Composite resin (Tetric Ceram, Ivoclar Vivadent) crowns were built up using a preformed polyester matrix, and the specimens were mounted in metallic rings with cold‐cure acrylic resin and kept in saline solution at 4°C for 24 hours. Fracture resistance was then determined using an EMIC DL‐2000 universal testing machine. The crosshead speed was 0.5 mm/min with the 45‐degree compressing load at the middle third of the crown. Data were analyzed using one‐way analysis of variance and Tukey'stest (p<.001). Results: Mean fracture resistance was as follows: Aestheti‐Post, 83.5 kgf; FibreKor Post, 85.7 kgf; and CosmoPost, 36.5 kgf. The fracture strength of CosmoPost was significantly lower than that of the other posts. Teeth restored with CosmoPost had post fractures, and in three specimens, those were associated with root fractures. Teeth restored with the other two posts presented fractures on the composite crowns. CLINICAL SIGNIFICANCE Compared with ceramic posts, carbon‐fiber and glass‐fiber prefabricated esthetic posts provide endodontically treated teeth higher fracture resistance.     

Fracture resistance of endodontically treated teeth restored with bonded amalgam and full crowns

The use of dentin bonding prior to placement of core build-up restorations has been shown to reduce microleakage and reinforce remaining tooth structure. However, information is lacking about the influence a core build-up has on the fracture resistance of crowned teeth. The purpose of this in-vitro study was to compare the influence of three types of core build-ups on the fracture resistance of crowned teeth.     

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。     

Fracture strength of endodontically treated teeth restored with different strategies after mechanical cycling

The aim of this study was to analyze the fracture strength of endodontically treated teeth with different coronal restoration strategies after mechanical cycling. Thirty bovine teeth were randomly allocated into three groups (n = 10): Group 1, cast metal post and core; Group 2, glass fiber post with a composite resin core; Group 3, glass fiber post with a glass prefabricated core. For post cementation, an etch and rinse multistep adhesive system and resin cement were used. The specimens were submitted to mechanical cycling (106 cycles, 90 N, 4 Hz, 37 ± 1 degree C) and immediately loaded in a universal testing machine. The statistical analysis (one-way ANOVA) did not indicate a significant difference among the tested groups (Group 1 = 593.9 ± 128.7 N; Group 2 = 554.4 ± 213.3 N; Group 3 = 427 ± 104.8 N; P = 0.06). With regard to fracture patterns, all Group 1 specimens demonstrated catastrophic failures, while the specimens in Groups 2 and 3 demonstrated core or core/post failure. Despite the similar fracture strength observed in the tested groups, teeth restored with composite resin or glass prefabricated cores demonstrated favorable failure patterns compared to the cast metal post and core group. This study demonstrates that a glass prefabricated core can be an acceptable alternative for the reconstruction of endodontically treated teeth.