An in vitro study evaluating the effect of ferrule length on fracture resistance of endodontically treated teeth restored with fiber-reinforced and zirconia dowel systems

STATEMENT OF PROBLEM: There are few published studies analyzing the effects of different ferrule lengths of endodontically treated teeth in relationship to newly developed fiber-reinforced and zirconia dowel systems. PURPOSE: This in vitro study compared the effect of 3 different ferrule lengths on the fracture resistance and fracture patterns of crowned endodontically treated teeth restored with 4 different esthetic dowel systems. MATERIAL AND METHODS: The crowns of 123 human maxillary canines were removed at the cementoenamel junction and the roots were endodontically treated. Three master tooth models were prepared to ferrule lengths of 1.0 mm, 1.5 mm, and 2.0 mm to produce 3 master analogs. Each root was embedded in autopolymerizing resin with a 0.2-mm layer of silicone impression material to simulate the periodontal ligament. Forty analogs of each master tooth, with ferrule lengths of 1.0 mm, 1.5 mm, and 2.0 mm were produced with copy-milling (Celay system). Each group was further subdivided into 4 groups of 10 specimens each and restored with 4 different esthetic dowel systems (quartz fiber, glass fiber, glass fiber plus zirconia, and zirconia). All dowels were luted with adhesive resin cement (RelyX ARC), restored with composite cores (Valux Plus), and Ni-Cr alloy (Wiron 99) complete crowns. All specimens were loaded at 130 degrees to the long axes in a universal testing machine at a crosshead speed of 1 mm/min until fracture. Fracture patterns were classified as failures above or below the incisal third of the roots. The data were analyzed with 2-way ANOVA and Tukey HSD tests (alpha=.05). A Fisher exact test was conducted for evaluation of the mode of failure (alpha=.05). RESULTS: Mean failure loads (kg) for quartz fiber, glass fiber, glass fiber plus zirconia, and zirconia groups, respectively, with the 3 ferrule lengths were: 1.0-mm ferrule specimens: 98.09 +/- 2.90, 85.36 +/- 2.82, 80.24 +/- 1.88, 70.11 +/- 2.48; 1.5-mm ferrule specimens: 101.0 +/- 2.88, 87.58 +/- 2.83, 89.8 +/- 2.09, 82.71 +/- 2.14; 2.0-mm ferrule specimens: 119.5+/-1.78, 99.84+/-1.23, 98.6 +/- 1.64, 95.42 +/- 1.02. Teeth prepared with 2.0-mm ferrules demonstrated significantly higher fracture thresholds (P<.001). There were no significant differences in fracture patterns. CONCLUSION: Increasing the ferrule length of the endodontically treated teeth from 1 mm to 1.5 mm in specimens restored with quartz-fiber and glass-fiber dowels did not produce significant increases in the failure loads (P=.084, P=.119, respectively). No significant difference was detected between glass-fiber and glass-fiber plus zirconia dowels with 1.5-mm and 2.0-mm ferrules (P=.218, P=.244, respectively). However, fracture thresholds were higher for all 4 dowel systems when the specimens were prepared with a 2.0-mm ferrule length (P<.001).     

In vitro evaluation of the fracture resistance of anterior endodontically treated teeth restored with glass fiber and zircon posts

STATEMENT OF PROBLEM: The published information is equivocal regarding the fracture resistance of endodontically treated teeth restored with fiber posts. Additionally, little is known about the biomechanical performance of glass fiber and zircon posts. PURPOSE: This in vitro study investigated the fracture resistance of anterior endodontically treated teeth prepared with a 2-mm ferrule, restored with glass fiber and zircon posts and composite resin cores or cast posts and cores. MATERIAL AND METHODS: Twelve matched pairs of teeth were obtained from 4 cadavers, and all were endodontically treated and prepared with a standardized 2-mm ferrule. According to a random number table, the 2 teeth from each matched pair were randomly divided into 2 groups. The test group consisted of 12 specimens restored with a glass fiber and zircon post (Fibio) and composite resin (Durafil) core. Twelve matching specimens restored with a nickel-chromium (NiCr) cast post and core served as the control. Specimens in both groups were cemented with resin cement (Panavia F). After cementation of cast NiCr complete crowns with zinc polycarboxylate cement (ShangChi), the specimens were loaded with an incremental static force at an angle of 135 degrees to the long axis of the root until failure occurred. A paired sample t test was used to compare the fracture resistance (N) of teeth restored with the 2 post-and-core systems (alpha=.05). RESULTS: The mean failure load of paired differences between the 2 groups was -261.3+/-237.3 N. The test group exhibited significantly lower failure loads than the control group (P=.004). All specimens displayed root fractures, most of which were oblique, with cracks initiating from the palatal cervical margin and propagating in a labial-apical direction. CONCLUSION: Within the limitations of this study, the teeth restored with glass fiber and zircon posts demonstrated significantly lower failure loads than those with cast NiCr post and cores. All specimens failed via root fractures.     

Cyclic loading of endodontically treated teeth restored with glass fibre and titanium alloy posts: fracture resistance and failure modes

The aims of this in-vitro investigation were to compare the fracture resistance and the failure modes of endodontically treated teeth restored with glass fibre-reinforced posts with those of teeth restored with titanium-alloy posts. A total of 60 single-rooted human mandibular premolars were endodontically treated. The teeth were divided into two experimental and one control group. Post spaces 9mm long were prepared in the roots of the experimental groups in which glass fibre-reinforced posts (Group A) and titanium-alloy posts (Group B) were cemented. In the control group (Group C), no post was inserted. The specimens were stored in normal saline for a period of three weeks before being intermittently loaded at an angle of 30 degrees degrees to the long axis of the tooth at a frequency of two loads of 40N per second. Log-rank test used for the overall analysis revealed that there was no significant difference of fracture resistance between teeth restored with glass fibre-reinforced posts (Group A) and titanium-alloy posts (Group B). The survival of the control group was found to be significantly inferior to that of the experimental groups. There was no significant difference in the number of failures between the two experimental groups. There was significantly more core and post failure for the glass fibre-reinforced posts, root and core failure for the titanium-alloy posts and core failure for the control group. The results suggest that post failures are more frequent in teeth restored with quartz fibre posts and root fractures are more frequent in teeth restored with titanium posts.     

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.     

The fracture behavior of premolar teeth with class II cavities restored by both direct composite restorations and endodontic post systems

PURPOSE: The aim of the study was to evaluate the influence of different posts on the fracture load and fracture mode of endodontically treated premolars with class II cavities and direct composite restorations in an ex vivo setting. METHODS: Forty-eight single-rooted human premolars were endodontically treated and prepared with standardized MO (mesio-occlusal) cavities. Eight teeth each received either no posts or were restored with titanium screws (BKS), glass fiber posts (DentinPost), or quartz fiber posts (DT Light SL). Sixteen teeth were restored with zirconium dioxide posts (CeraPost). BKS-screws and eight zirconium dioxide posts were cemented conventionally with glass ionomer cement; Panavia F resin cement was used for all others. The specimens were restored with direct composite restorations. Eight sound premolars served as the controls. After thermomechanical fatigue testing, the samples were loaded until fracture occurred at an angle of 45 degrees . All specimens were evaluated for fracture lines. RESULTS: The sound teeth showed the significant highest fracture load (792.50+/-210.01 N). The group restored with quartz fiber posts differed not significantly from the control. In the groups with fiber posts and titanium screws significant higher fracture load values occurred as in the group with direct composite restorations without posts. The groups with fiber posts did not show a more favorable fracture mode than the other groups. CLINICAL SIGNIFICANCE: The use of an intraradicular post in premolars with class II cavities can significantly increase the resistance towards extra-axial forces.     

Influence of endodontic posts on the fracture behavior of crowned premolars with Class II cavities

AIM: The aim of the study was to evaluate the influence of different posts and types of cementation on the fracture load and fracture mode of crowned, endodontically treated premolars with class II cavities in an ex vivo setting. METHODS: Forty-eight single-rooted human premolars were endodontically treated and prepared with standardized MO (mesio-occlusal) cavities and a circular chamfer preparation. Eight teeth each received either no posts or were restored with screws (BKS), glass fiber posts (DentinPost), or quartz fiber posts (DT Light SL). Sixteen teeth were restored with zirconium dioxide posts (CeraPost). BKS-screws and eight zirconium dioxide posts were cemented conventionally with glass ionomer cement; Panavia F was used for all others. The specimens were restored with composite cores and crowns cast from a non-precious metal. Eight sound premolars served as the controls. After thermomechanical fatigue testing, the samples were loaded until fracture occurred at an angle of 45 degrees. All specimens were evaluated for fracture lines. RESULTS: The sound teeth showed the significant highest fracture load (792.50+/-210.01 N). Conventionally cemented zirconium dioxide posts showed the lowest fracture load (327.00+/-45.84 N); the highest fracture load occurred with quartz fiber posts (421.75+/-90.19 N). Only the difference between these two groups was statistically significant. With glass fiber posts and conventionally cemented zirconia posts, restored teeth failed mostly in an "unfavourable" mode. CONCLUSIONS: With respect to the fracture load, there was no statistical difference between the restoration of non-vital premolars with class II cavities with crowns and posts or crowns alone.     

Fracture resistance and failure patterns of endodontically treated mandibular molars with and without glass fiber post in combination with a zirconia-ceramic crown

OBJECTIVE: The aim of this study was to investigate the influence of a fiber post on the fracture mechanics of zirconia crowns inserted over endodontically treated teeth with different extent of coronal damage. METHODS: Endodontically treated human molars with three types of coronal damage received fiber posts before cementation of zirconia-veneered crowns. Controls received composite resin cores without fiber posts. The specimens were loaded to failure and fractographically examined using a scanning electron microscope (SEM). RESULTS: Statistical analysis revealed that specimens with fiber posts demonstrated significantly higher failure loads and favorable fracture pattern compared to the controls. At fractographic analysis, specimens with fiber posts demonstrated delamination of the veneer ceramic from intact zirconia under structure. Meanwhile, the specimens that were restored without a fiber post demonstrated micro-cracking of the composite core build-up resulting in loss of the support under the zirconia crowns which was responsible for the initiation of radial crack and catastrophic damage. CONCLUSIONS: Within the limitation of this study, the insertion of fiber post improved the support under zirconia crowns which resulted in higher fracture loads and favorable failure type compared to composite core build-up.     

Fracture resistance and failure patterns of endodontically treated mandibular molars restored using resin composite with or without translucent glass fiber posts

The elastic modulus of the restorative material is important in restoring endodontically treated teeth. This study aimed to compare the fracture resistance and failure patterns of 90 mandibular molars restored using resin composites with or without fiber posts, with respect to the number of residual cavity walls. Five restoration types were performed corresponding to different wall defects (groups 1-5). Groups were divided in two subgroups corresponding to the use or absence of fiber posts. Teeth were loaded and resistance of specimens was measured as the axial compressive load to cause fracture and macroscopic fracture patterns were observed. One way ANOVA revealed a significant difference in fracture resistance (p < 0.001). Tukey post hoc test also revealed significant differences between groups as samples restored with fiber posts exhibited mostly restorable fractures. It was concluded that the resistance of endodontically treated mandibular molars restored with composite resins is mainly affected by the number of residual walls. Using fiber-reinforced posts optimized fracture patterns.     

Influence of prefabricated post dimensions on restored maxillary central incisors

The aim of this study was to test the following hypothesis: biomechanical performance (fracture strength and stress distribution) of restored teeth is less sensitive to post diameter and post length when using glass fibre posts than when using stainless steel posts. First, an experimental fracture strength test was performed on 80 extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (40 with glass fibre posts and 40 with stainless steel posts), and the length and diameter of the posts varied uniformly. Failure loads were recorded and results were compared using an ancova analysis. Secondly, the finite element technique was used to develop a model of the restored tooth. The post diameter had a significant effect on the biomechanical performance of teeth restored with stainless steel posts. Lower failure loads were found as post diameter increased. However, the post diameter of those teeth restored with glass fibre posts, and the post length for both post systems under consideration, did not affect the biomechanical performance of restored teeth to a significant degree. The stress distributions predicted by the developed model corroborated these findings, confirmed the assumed hypothesis, and permitted the proposal of the use of glass fibre posts to achieve a restorative technique that is less sensitive to post dimensions, and thus more robust.     

Effect of post type and restorative techniques on the strain and fracture resistance of flared incisor roots

Restoring flared endodontically treated teeth continues to be a challenge for clinicians. This study evaluated the effect of post types and restorative techniques on the strain, fracture resistance, and fracture mode of incisors with weakened roots. One hundred five endodontically treated bovine incisors roots (15 mm) were divided into 7 groups (n=15). The two control groups were (C) intact roots restored with Cpc (cast posts and core) or Gfp (glass fiber posts). The five experimental groups were (F) flared roots restored with GfpAp (Gfp associated with accessory glass fiber posts), GfpRc (anatomic Gfp, relined with composite resin), and GfpRcAp (anatomized Gfp with resin and accessory glass fiber posts). All teeth were restored with metal crowns. Mechanical fatigue was performed with 3x10(5)/50 N. Specimens were loaded at 45o, and the strain values (μS) were obtained on root buccal and proximal surfaces. Following that, the fracture resistance (N) was measured. One-way ANOVA and Tukey's HSD tests (α=0.05) were applied, and failure mode was checked. No significant difference in strain values among the groups was found. Cpc presented lower fracture resistance and more catastrophic failures in flared roots. Gfp associated with composite resin or accessory glass fiber posts seems to be an effective method to improve the biomechanical behavior of flared roots.     

Influence of coronal restorations on the fracture resistance of root canal‐treated premolar and molar teeth: A retrospective study

To evaluate the influence of coronal restorations on the fracture resistance of endodontically treated teeth, 676 root canal‐filled and restored posterior teeth were evaluated after a mean period of 9.7 (±2.8; minimum: 5) years. A total of 86.2% of the endodontically treated and restored teeth survived the mean observation period of 9.7 years without fracture. The overall survival period was 13.6 (± 0.2) years. All teeth with gold partial crowns survived without fractures (n = 24). Teeth with crowns and adhesively sealed access cavities showed a mean survival period of 15.3 (± 0.4) years, with crown and bridge restorations 14.0 (± 0.3), with individual metal posts 13.9 (± 0.2), with composite fillings 13.4 (± 0.5), with prefabricated metal posts 12.7 (± 0.6), with amalgam fillings 11.8 (± 0.6) and with glass ionomer cements (GIC) 6.6 (± 0.5) years. Teeth with one or two surfaces restored by amalgam, composite or GIC showed a significantly lower fracture rate than teeth with three and more restored surfaces (P < 0.05). The mean fracture rate of teeth restored with GIC was significantly higher when compared with all other groups (P < 0.001). In general, endodontically treated teeth restored with prosthetic restorations demonstrated a significantly lower mean fracture rate than teeth restored with fillings. Cavities with up to three surfaces may well be successfully restored adhesively with composite filling material.     

Fracture resistance of composite resin cores with or without prefabricated posts over different substrates

The fracture resistance of endodontically treated teeth has been an obstacle to the durability of the remaining teeth and restorations. The aim of this study was to evaluate the fracture resistance of endodontically treated bovine and human teeth that were restored with either prefabricated metal posts, glass fiber posts, or composite resin cores. Statistical analysis revealed significant difference between different substrates, but there was no statistically significant difference between different types of intraradicular posts or in the interaction between substrate and post types. The intraradicular posts do not increase the fracture resistance of endodontically treated teeth. The metal posts presented more unfavorable fracture modes when compared to glass fiber posts and composite resin cores.     

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.     

In vitro evaluation of the effect of post system and length on the fracture resistance of endodontically treated human anterior teeth

Objectives

The aim of this study was to evaluate the effect of post system and length on the fracture resistance of endodontically treated human anterior teeth.

Material and method

Seventy-five extracted human incisors were endodontically treated, out of which 60 were decoronated 2?mm above the cementoenamel junction and divided into two experimental groups based on the type of post system to be used: glass fiber post (GFP) and Ribbond fiber post groups (RFP). Endodontically treated human anterior teeth in which no post was placed served as control group. Each group was divided into two subgroups according to the length of post space: 5 and 10?mm and all the samples were restored with metal crowns. The fracture resistance was measured by applying loads at an angle of 130° to the long axis of teeth in an Instron universal testing machine.

Results

The results revealed that GFP group at 10-mm post space length showed the significantly highest fracture resistance (740.2133?N) among all groups and subgroups. Decrease in post length resulted in the decrease in fracture resistance in GFP group (425.1867?N), whereas in group RFP 5-mm subgroup (299.6200?N) showed significantly higher fracture resistance than 10-mm subgroup (216.9300?N) but lesser than the control (437.8733?N) in both the subgroups.

Conclusion

Glass fiber posts efficiently increase the fracture resistance of an endodontically treated tooth but the determination of optimal post length is also essential.

Clinical relevance

The present investigation highlights the significance of using glass fiber posts in the restoration of endodontically treated teeth. Endodontically treated teeth restored with glass fiber posts showed increased fracture strength and favorable mode of fracture, and are therefore highly recommended to achieve better clinical outcomes.     

不同桩核金属烤瓷全冠修复后前牙抗剪切力的实验研究

目的 探讨不同桩核系统金属烤瓷全冠修复上颌前牙后修复体抗剪切力的差异.方法 对40颗大小相似的新鲜上颌中切牙行根管充填后截冠,随机分成4组,每组10颗.其中3组分别用纤维增强树脂桩和树脂核、预成钛合金桩和树脂核,铸造镍铬合金桩核修复,桩核与金属烤瓷全冠均用树脂粘接剂粘固;另1组用玻璃离子粘固剂粘固铸造镍铬合金桩核和金属烤瓷全冠作为对照组.经温度循环疲劳实验,用万能力学实验机测试样本牙的抗剪切力,并观测折裂型,进行统计学分析.结果 纤维增强树脂桩组、预成钛合金桩组、铸造桩核组及对照组的抗剪切力分别为(534.4±145.7)N、(499.8±168.9)N、(412.6±99.3)N、(337.4±121.2)N.纤维增强树脂桩组和预成钛合金桩组的抗剪切力大于对照组,差异有统计学意义(P＜0.05);纤维增强树脂桩组中可再修复折裂型样本牙数量多于其他组,差异有统计学意义(P＜0.05).结论 纤维增强树脂桩核金属烤瓷全冠修复有较好的抗剪切力,且折裂型多为可再修复型,修复后残根保存率高.     

Influence of material and diameter of pre-fabricated posts on maxillary central incisors restored with crown

Summary  Numerous research works have studied the effect of post-design parameters on the mechanical behaviour of restored teeth without reaching any clear conclusions. Previous works by the authors ascertained the effect of material and post-dimensions for non-crowned restored teeth. The aim of this work was to study the effect of post-material and diameter for crowned teeth. First, an experimental fracture strength test was performed on eighteen extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (nine with glass fibre posts and nine with stainless steel posts). Several post-diameters were used. The final crown restoration was carried out using a reinforced glass-ceramic material. Failure loads were recorded and results were compared using the one-way anova . Secondly, the finite element technique was used to model the restored teeth and to compare the estimated stress distributions. The addition of the crown did not affect the strength of the restoration to any significant extent and post-diameter did not influence the biomechanical performance of either of the post-systems. The crown acts as a protector, thus eliminating the influence of the post-diameter that was found previously when using stainless steel posts, but it does not completely rule out the possibility of a root fracture. Significantly, lower failure loads were found experimentally for teeth restored with stainless steel posts. The stress distributions predicted by the model corroborated these findings and allowed the authors to propose the use of glass fibre posts as a more robust restorative technique.     

桩核修复方法对梭形根管牙断裂强度的影响

目的：比较3种不同桩核修复方法对梭形根管牙断裂强度的影响。方法：30颗近期拔除的上颌中切牙根管治疗后预备成梭形,随机分为3组,每组10颗。Ⅰ组行玻璃纤维桩、Luxacore树脂核和铸造全冠修复;Ⅱ组根管扩大预备后行铸造镍铬桩核和铸造全冠修复;Ⅲ组玻璃离子水门汀重塑根管后行铸造镍铬桩核和铸造全冠修复。Zwick z010型电子万能试验机测试断裂强度。结果：Ⅰ组与Ⅱ组、Ⅲ组试件牙的断裂强度差异有显著性,Ⅱ组与Ⅲ组差异无显著性。结论：梭形根管牙的断裂强度与其修复设计有关,采用玻璃纤维桩及树脂核修复有较高的断裂强度,且断裂方式利于再修复。     

In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement.

In an in vitro experiment, the failure loads of 59 intact endodontically treated teeth with and without Kerr Endo-Post reinforcement were compared. Fifty-eight teeth fractured below the cementoenamel junction. One tooth fractured through the pulp chamber with a chisel fracture involving both the crown and root. Teeth without posts fractured through the middle or coronal one third of the root. Teeth with posts fractured through the body of the post. No statistically significant reinforcement was demonstrated by cementing a Kerr Endo-Post No. 100 into a sound endodontically treated tooth.     

Fracture resistance of pulpless teeth restored with post-cores and crowns.

OBJECTIVES: The present study was designed to test the null hypothesis that there is no difference in the fracture resistance of pulpless teeth restored with different types of post-core systems and full coverage crowns. METHODS: Extracted human upper premolars were restored with a fiber post, prefabricated metallic post or cast metallic post-core. Teeth with full crown preparations without post-core restorations served as a control. All teeth were restored with full coverage crowns. A 90-degree vertical or 45-degree oblique load was applied to the restored teeth with a crosshead speed of 0.5 mm/min, and the fracture loads and mode of fracture were recorded. RESULTS: Under the condition of vertical loading, the fracture load of teeth restored with the cast metallic post-cores was greatest among the groups (two-factor factorial ANOVA and Scheffe's F test, P<0.05). All fractures in teeth restored with all types of post-core systems propagated in the middle portions of roots, including the apices of the posts. Under the condition of oblique loading, the fracture load of teeth restored with pre-fabricated metallic posts was significantly smaller than that in other groups. Two-thirds of fractures in the fiber post group propagated within the cervical area, while most fractures in other groups extended beyond the middle of the roots. SIGNIFICANCE: From the results of the present investigations, it was concluded that under the conditions of vertical and oblique loadings, the combination of a fiber post and composite resin core with a full cast crown is most protective of the remaining tooth structure.     

Fracture resistance and primary failure mode of endodontically treated teeth restored with a carbon fiber-reinforced resin post system in vitro

PURPOSE: This study was undertaken to characterize the fracture resistance and mode of fracture of endodontically treated incisors restored with cast post-and-core, prefabricated stainless steel post, or carbon fiber-reinforced composite post systems. MATERIALS AND METHODS: Ten endodontically treated teeth restored with each technique were subjected to a compressive load delivered at a 130-degree angle to the long axis until the first sign of failure was noted. The fracture load and the mode of fracture were recorded. RESULTS: The failure loads registered in the three groups were not significantly different. Between 70%, and 80% of teeth from any of the three groups displayed fractures that were located above the simulated bone level. CONCLUSION: The use of carbon fiber-reinforced composite posts did not change the fracture resistance or the failure mode of endodontically treated central incisors compared to the use of metallic posts.