Effect of Fiber Post and Cusp Coverage on Fracture Resistance of Endodontically Treated Maxillary Premolars Directly Restored with Composite Resin

IntroductionThere are different reinforcement methods in restoring root-filled teeth. The aim of this in vitro study was to evaluate the effect of fiber post and cusp coverage on fracture resistance of endodontically treated maxillary premolars directly restored with composite resin.MethodsSeventy-five maxillary premolars were divided into 5 groups (n = 15). Except for the control group (intact teeth), in other groups mesio-occlusodistal (MOD) cavities were prepared after endodontic treatment. In the groups with cusp coverage, both buccal and lingual cusps were reduced up to 2 mm. Then specimens in the experimental groups were prepared as follows: composite resin restoration without post and cusp capping, composite resin restoration without post but with cusp capping, composite resin restoration with post but without cusp capping, and composite resin restoration with post and cusp capping. After finishing and polishing, the specimens were stored in distilled water at 37°C for a week. Subsequent to thermocycling and exertion of compressive forces parallel to the long axes of the teeth at a strain rate of 2 mm/min, data were analyzed by using one-way analysis of variance and χ² test.ResultsThere were no significant differences in fracture resistance between the groups (P = .057). However, χ² test showed statistically significant differences between the groups in failure mode (P < .001). The highest number of favorable fractures was observed in the control group (intact teeth).ConclusionsRoot-filled maxillary premolars, restored with direct resin composite with or without fiber post and cusp capping, had similar fracture resistance under static loading.     

Fracture resistance of endodontically-treated maxillary premolars restored with different type of posts and direct composite reconstructions: A systematic review and meta-analysis of in vitro studies

ObjectiveTo conduct a systematic review and meta-analysis to assess if the presence of an endodontic post may increase the fracture resistance of endodontically-treated maxillary premolars directly restored with composite.MethodsA comprehensive systematic literature search according to the PRISMA statement was conducted to assess in vitro studies including endodontically-treated maxillary premolars, restored with different type of posts supporting direct composite reconstructions. Two groups of meta-analyses were performed using fixed effects model and additional Trial Sequential Analysis (TSA) was carried out. Moreover, risk of bias was conducted and quality of evidence for any performed meta-analysis was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).ResultsTwenty-four articles met the inclusion criteria and 13 studies also underwent quantitative evaluation. Fracture resistance of endodontically-treated premolars restored with fiber posts was significantly less than sound teeth (p value: < 0.00001), however endodontically-treated premolars with a fiber post provided an increase in fracture resistance when compared to equivalent teeth restored without post (p value: 0.003). TSA revealed high power of both meta-analyses. Moderate risk of bias was reported in 23/24 studies; only 1 study showed high risk of bias. GRADE system showed moderate strength of evidence due to the presence of a study with high risk of bias and to wide confidence intervals.SignificanceWithin the limitation of the present systematic review and meta-analysis, it can be concluded that endodontically-treated maxillary premolars restored with a fiber post and direct composite restoration demonstrated increased fracture resistance when compared to equivalent teeth without post.     

两种桩核修复系统对上前牙抗折性能的临床对比

目的 评价玻璃纤维桩树脂核和钴铬合金铸造桩核修复对上颌前牙抗折性能的影响。方法 临床收集上颌前牙牙体缺损患者 251 例,326 颗患牙,随机分为 A、B 两组,A 组采用玻璃纤维桩树脂核修复,B 组采用钴铬合金铸造桩核修复。随访观察2~3年内出现上颌前牙牙体折裂的情况。结果 两种修复方式的牙体折裂率差异具有统计学意义（P<0.05)。结论 采用玻璃纤维桩树脂核修复上颌前牙的抗折性能明显优于钴铬合金铸造桩核。     

The effect of the post length and cusp coverage on the cycling and static load of endodontically treated maxillary premolars

In endodontically treated teeth, cuspal coverage plays a fundamental role in reducing the risk of fracture. However, the adhesive techniques with or without fiber post increased the possibilities in restoring root-filled teeth. The aim of this study was to determine the effect of the fiber post and/or post length and/or cuspal coverage on the fracture resistance of endodontically treated maxillary premolars. Seventy intact single-rooted maxillary premolars were selected and divided in seven groups of ten each: “intact teeth” (control), “inlay without fiber post” (G1), “inlay with long fiber post” (G2), “inlay with short fiber post” (G3), “onlay without fiber post” (G4), “onlay with long fiber post” (G5), and “onlay with short fiber post” (G6). Except for intact teeth, all specimens were prepared with a mesio–occluso–distal (MOD) cavity, endodontically treated and restored with or without long or short post, with or without cusp coverage. All specimens were thermal-cycled, exposed to a cyclic loading, and then submitted to the static fracture resistance test. Fracture loads and mode of failure were evaluated. A statistically significant difference in fracture resistance was found between group 1 and the other groups (p < 0.001). χ2 test showed statistically significant differences in the patterns of fractures between the groups (p < 0.001). The highest number of favorable fractures was observed in groups 3 and 4. Similar fracture resistance was detected in maxillary premolars endodontically treated with MOD cavity preparations, restored with either direct resin composite with fiber post or cusp capping. The “short post” direct restoration may be a valid alternative in the restoration of root-filled premolars.     

上颌前磨牙根管治疗后MOD洞型不同修复方式对牙体抗力的影响

目的：使用不同方式修复上颌前磨牙牙体缺损后,比较牙体修复方式和材料对牙齿抗力的影响。方法：选择60颗单根上颌前磨牙,随机分为4组：A组,对照组;B组,复合树脂充填组;C组,复合树脂覆盖牙尖充填组;D组,聚合瓷嵌体覆盖牙尖修复组。完成所有的修复后,制备抗折强度检测试件。使用万能试验机进行压力试验,直到样本劈裂。每个样本劈裂时的压力及劈裂的类型,分别进行记录。结果：C组和D组的抗折强度明显高于B组（P〈0．05）,C组和D组抗折强度差别不明显。样本的劈裂形式四组存在差异,劈裂形式为Ⅱ型的比例D组低于C组。结论：覆盖牙尖的修复方式修复根管治疗后牙齿的大面积缺损（MOD洞型）,有利于提高牙齿的抗力;聚合瓷嵌体修复要优于复合树脂充填修复。     

Effect of restoration method on fracture resistance of endodontically treated maxillary premolars

PURPOSE: The aim of the present study was to compare the fracture resistance of endodontically treated maxillary premolars with mesio-occlusodistal (MOD) cavities restored using various restorative materials and luting agents. MATERIALS AND METHODS: Eighty extracted human maxillary premolars satisfying certain predetermined criteria were subjected to seven different restoration methods (10 premolars per method). After endodontic treatment, an MOD cavity was prepared in each specimen, and restoration was carried out by one of the following methods: group 1 = control (intact premolars); groups 2 and 3 = restoration using a photo-cure resin composite with and without bonding, respectively; groups 4 and 5 = restoration using a cast-metal inlay with zinc phosphate and adhesive resin cements, respectively; groups 6 and 7 = restoration using a cast-metal onlay with zinc phosphate and adhesive resin cements, respectively; and group 8 = restoration using a hybrid resin onlay. A fracture test was conducted to determine the fracture resistance and fracture mode of each specimen. RESULTS: Fracture resistance was greatest for teeth restored using a cast-metal onlay cemented with adhesive resin cement, but those fractures that did occur were generally unrestorable. Fracture resistance of teeth restored using a cast-metal inlay was also high. Fracture resistance for teeth restored using a resin composite was significantly lower, but the majority of these fractures were restorable. CONCLUSION: Endodontically treated maxillary premolars with MOD cavities could be successfully restored by cast onlay and inlay restorations luted with adhesive resin cement, but their failure mode was often unfavorable.     

冠折年轻恒牙根管治疗后不同修复方法的抗折强度研究

目的:对比不同修复方法的根管治疗后的冠折年轻恒牙的抗折强度差异.方法:选择30颗牙体完好的单根管的下颌第一前磨牙,经根管治疗后,随机分成6组:A组不截冠为对照组,其余五组沿着牙冠各轴面水平向中线的连线进行截冠;B组采用聚合瓷贴面修复;C组直接树脂修复;D组预成玻璃纤维桩+树脂修复;E组预成玻璃纤维桩十树脂核十聚合瓷冠修...     

A comparative evaluation of fracture resistance of endodontically treated teeth restored with different post core systems - an in-vitro study

PURPOSE

To compare the fracture resistance and the mode of failure of endodontically treated teeth restored with different post-core systems.

MATERIALS AND METHODS

Root canal treatment was performed on 40 maxillary incisors and the samples were divided into four groups of 10 each. For three experimental groups post space preparation was done and teeth were restored with cast post-core (Group B), stainless steel post with composite core (Group C) and glass fiber post with composite core using adhesive resin cement (Group D). Control group (A) samples were selected with intact coronal structure. All the samples were prepared for ideal abutment preparation. All the samples were subjected to a load of 0.5 mm/min at 130° until fracture occurred using the universal testing machine. The fracture resistance was measured and the data were analyzed statistically. The fracture above the embedded resin was considered to be favorable and the fracture below the level was considered as unfavorable. The statistical analysis of fracture resistance between different groups was carried out with t-test. For the mode of failure the statistical analysis was carried out by Kruskal-Wallis test and Chi-Square test.

RESULTS

For experimental group Vs control group the fracture resistance values showed significant differences (P<.05). For the mode of failure the chi-square value is 16.1610, which means highly significant (P=.0009) statistically.

CONCLUSION

Endodontically treated teeth without post core system showed the least fracture resistance demonstrating the need to reinforce the tooth. Stainless steel post with composite core showed the highest fracture resistance among all the experimental groups. Teeth restored with the Glass fiber post showed the most favorable fractures making them more amenable to the re-treatment.     

纤维桩对穿髓型楔状缺损抗折性修复的临床对比观察

目的：针对穿髓型楔状缺损牙颈部抗力薄弱易折断的潜在隐患,评价不同修复术式对牙颈部抗折性能的临床效果。方法：临床随机选择穿髓型楔状缺损患者48例,（牙合）面完整,男性20例,女性28例,年龄45-73岁。其中第一前磨牙28例（上颌19例,下颌9例）,第二前磨牙9例（上颌6例,下颌3例）;尖牙11例（上颌8例,下颌3例）。在（牙合）面开髓根管治疗后,将所有患者随机分为A、 B两组各24颗牙,以2种术式分别进行修复。 A组：（牙合）面及楔状缺损处以Filtek Z350 XT纳米树脂完成修复; B组：根管纤维桩粘固后（牙合）面及楔状缺损处以Filtek Z350 XT纳米树脂完成修复。结果：临床观察2年, A组出现6例颈部折断, B组未出现颈部折断,经卡方检验连续校正公式计算,χ^2=4.68, P〈0.05,说明是否使用纤维桩修复与牙颈部折断间有统计学差异,使用纤维桩可增强牙颈部抗折断力。结论：在穿髓型楔状缺损根管内粘固玻璃纤维桩的一端,再以复合树脂将纤维桩的另一端与牙冠粘接,使纤维桩、树脂、整个牙齿（冠与根）三者整合为一体,不但增强了颊颈部修复体的固位,更提高了牙颈部的抗折性能,是一种合理、微创的牙颈部抗折修复形式,较好地体现了整体修复理念。     

桩-桩道间隙的匹配对纤维桩修复牙根发育不完全牙的抗折性能的影响

目的:比较3种不同直径的纤维桩插入相同的根管桩道预备间隙对牙根发育不完全牙修复后抗折强度的影响,为临床使用桩核系统修复根尖诱导成形术后的牙提供依据。方法:收集符合纳入标准的因正畸需要拔除的第一、二前磨牙75颗,随机分为5组。其中,实验组3组(3种不同直径的纤维桩+材料充填)、阳性对照组1组(材料桩道充填)、阴性对照组1组(根管充填后不作处理),每组样本牙各15颗,常规进行相同的桩道预备后,用不同直径的桩核系统修复,将修复后的样本牙进行包埋,采用TY-8000型电子万能测试机分别测量牙根颈1/3和中1/3区域的抗折强度,比较桩—桩道间隙的匹配对牙根抗折强度的影响。采用SAS6.0软件包对数据进行统计学处理。结果:实验组1(在桩道预备间隙中插入1.3mm的玻璃纤维桩)的牙根颈部、中部的抗折强度分别为(811±33.85)N、(681±26.64)N;实验组2(在桩道预备间隙中插入1.6mm的玻璃纤维桩)为(901±39.85)N、(729±28.77)N;实验组3(在桩道预备间隙中插入1.9mm的玻璃纤维桩)为(999±75.40)N和(799±21.77)N,阴性对照组分别为(501±38.4)、(472±22.98)N,阳性对照组分别为(704±88.39)、(550±20.14)N,对实验组1、2、3,阳性对照组和阴性对照组进行两两比较,发现在牙根的不同部位,抗折强度均有显著差异(P<0.001),且与阴性对照组有显著差异。其中,插入直径最大的1.9mm玻璃纤维桩的牙根,各部位的抗折能力最强。结论:桩道预备间隙对牙根抗折性能有显著影响,植入直径最大的1.9mm玻璃纤维桩的牙,在牙根颈1/3和中1/3区域都显示出比植入其他2种直径玻璃纤维桩的牙具有更大的抗折强度。     

Effect of different all-ceramic crown system on fracture resistance and failure pattern of endodontically treated maxillary premolars restored with and without glass fiber posts

Endodontically treated teeth are traditionally restored with a crown to prevent fracture. The aim of this study was to compare the fracture resistance and failure modes of endodontically treated maxillary premolars treated with or without a fiber post and restored with different types of crowns. Eighty human maxillary premolars were selected. After root canal treatment, the teeth were embedded in resin blocks and divided into four groups. Samples received MOD cavity preparations and were divided into two subgroups: with and without fiber posts and restored using porcelain fused to metal, lithium disilicate, fiber-reinforced composite, or zirconia crowns. The specimens were vertically loaded in the central fossa using a universal loading machine until failure, and the maximum breaking loads were recorded. Samples were perfused with Indian ink to highlight the fracture lines and the mode of failure that was classified as restorable or nonrestorable. Even without post, all crown designs resisted vertically applied forces beyond those that may be encountered in the mouth. Two-way analysis of variance revealed the use of a fiber post (p = 0.007) and the type of crown (p < 0.001) significantly affected the restorability of fractured teeth. The relationship between placing or not placing the post and the type of failure (restorable/nonrestorable) was found to be significant (chi(2) test, p = 0.002). Although post placement resulted in higher fracture resistance values, these were significant for Empress II crowns only. The results suggest that the posts could contribute to the reinforcement and strengthening of pulpless maxillary premolars. With respect to failure modes, placement of fiber posts improved the fracture from nonrestorable to restorable patterns. This study suggests that the placement of fiber posts is necessary to improve fracture resistance even under full-coverage crowns.     

Structural integrity of extracted teeth restored using three different post-and-core systems: An in vitro comparative study

AimThe objective of the study was to assess the in vitro fracture resistance of endodontically treated teeth restored using different post-and-core materials.Materials and methodsExtracted human mandibular premolars (n = 36) were extracted teeth and equally distributed into four (4) treatment groups: cast metal post-and-core, milled zirconia post-and-core, pre-fabricated post with composite resin core and control group. These samples were then each subjected to the load to fracture test using a universal testing machine. Fracture resistance data were compared among groups by analysis of variance and Fisher’s exact test.ResultsThe highest mean fracture resistance value was observed in the zirconia post-and-core treatment group (1567.26 ± 317.66 N), followed by the cast metal (1355.92 ± 621.56 N) and lastly the pre-fabricated post with composite resin core (725.67 ± 251.05 N) treatment group. Differences among groups were not statistically significantly different (P = 3.77).ConclusionEndodontically treated mandibular premolars with a zirconia post-and-core system exhibited the highest robustness against structural failure based on its mean fracture resistance value. In addition, extracted teeth restored with cast post-and-core resisted a greater stress load than those restored with fiber-reinforced posts. Zirconia showed a more favorable fracture mode than the other restorations.     

Fracture resistance of the buccal cusps of root filled maxillary premolar teeth restored with various techniques

AIM: To compare the cusp fracture resistance of teeth restored with composite resins and two post systems. METHODOLOGY: Eighty extracted single-rooted human maxillary premolars were randomly assigned to eight groups (n = 10). Group 1 (control) did not receive any preparation. From groups 2 to 8, the teeth were root filled and mesio-occluso-distal (MOD) cavities were prepared. Group 2 remained unrestored. Group 3 was restored with packable resin composite using a single-step adhesive. Group 4 was restored with packable resin composite using a single-step adhesive and a thin layer of flowable resin composite. Group 5 was restored with packable resin composite using a total-etch two-step adhesive. Group 6 was restored with ormocer resin composite using a total-etch two-step adhesive. Group 7 was restored with an endodontic glass fibre post and hybrid resin composite using a total-etch two-step adhesive. Group 8 was restored with an endodontic zirconium post and hybrid resin composite using a total-etch two-step adhesive. The teeth were then mounted in a universal testing machine, the buccal cusp loaded (30 degrees ) until fracture, and the data analysed statistically. RESULTS: Group 1 had the greatest fracture resistance, and group 2 the poorest. Groups 5-8 had significantly greater (P < 0.05) fracture resistance than groups 3 and 4. No significant differences were found between groups 3 and 4, or amongst groups 5-8 (P > 0.05). CONCLUSIONS: For root filled maxillary premolars with MOD cavities, adhesive resin composite restorations, with and without glass and zirconium posts, increased the fracture resistance of the buccal cuSPS. A total-etch two-step adhesive increased significantly fracture resistance more than a one-step adhesive. For the one-step adhesive, an additional layer of flowable resin composite did not enhance fracture resistance.     

Adhesive restoration of anterior endodontically treated teeth: influence of post length on fracture strength

Objectives

This study aims to evaluate the fracture resistance of endodontically treated anterior teeth restored with crowns made of composite or ceramic and retained without the use of a post (endocrowns) or with posts of 5 mm (short) and 10 mm in length (long).

Material and methods

Forty-eight intact maxillary incisors were selected for the study. After endodontic treatment, the crowns were sectioned 2 mm coronally to the cementoenamel junction provided with a ferrule of 2 mm. The roots were randomly divided into six groups (n?=?8) according to the post length and type of coronary restoration. The crowns were fabricated with the chairside economical restoration of esthetic ceramics system. Group 1 was restored with a 10-mm glass fiber post, composite core, and a full-coverage ceramic crown (LPCer); group 2, with a 5-mm glass fiber post, composite core, and a full-coverage ceramic crown (SPCer); group 3, with a 10-mm glass fiber post, composite core, and a full-coverage composite crown (LPCpr); group 4, with a 5-mm glass fiber post, composite core, and a full-coverage composite crown (SPCpr); and groups 5 (EndoCer) and 6 (EndoCpr) were restored with ceramic and composite endocrowns, respectively. The teeth were then thermomechanically loaded in a chewing machine. After fatigue, the specimens were loaded to fracture. Data were analyzed with ANOVA and chi-square test. Mode of failure was defined as repairable or non-repairable.

Results

Presence of post, post length, and crown material had no significant effect on the fracture resistance. Groups restored with endocrowns presented a higher number of repairable fractures in respect to the other groups.

Conclusions

Presence of a post had no effect on the restorations’ fracture strength.

Clinical relevance

Although this in vitro study has some limitations in respect to its clinical relevance, the restoration of largely destroyed anterior teeth with the use of an endocrown or a short glass fiber post might have advantages over a large glass fiber post.     

玻璃纤维桩对不同程度牙体缺损抗折能力的影响

目的研究玻璃纤维桩核冠和树脂核冠修复下颌第一前磨牙不同数量缺损壁后的抗折能力。 方法根据不同的缺损壁数目及修复方法,随机分为6组。A1组：一壁缺损+玻璃纤维桩核冠修复;A2组：一壁缺损+树脂核冠修复;B1组：二壁缺损+玻璃纤维桩核冠修复;B2组：二壁缺损+树脂核冠修复;C1组：三壁缺损+玻璃纤维桩核冠修复;C2组：三壁缺损+树脂核冠修复。使用力学实验机对各组离体牙进行加载直至破坏,记录最大负载值及破坏模式。结果采用两独立样本的t检验进行统计。 结果一壁缺损时,纤维桩核冠修复组(A1组)与树脂核冠修复组(A2组)之间的最大负载力差异无统计学意义(t_A=1.830,P_A=0.10)。二壁及三壁缺损时,玻璃纤维桩核冠修复组(B1组、C1组)分别与树脂核冠修复组(B2组、C2组)之间的最大负载力差异有统计学意义(t_B=4.741,P_B=0.001;t_C=3.491,P_C=0.005)。不可修复性折裂主要发生在A1、A2、B2组。 结论玻璃纤维桩核冠与树脂核冠修复一壁缺损牙体后抗折能力没有显著性差异,因此临床上对一壁缺损牙体可以只作树脂核冠进行修复。当牙体有二壁或者三壁缺损时,玻璃纤维桩核冠修复后牙体的抗折能力优于树脂核冠修复后牙体的抗折能力。     

The influence of cavity design and glass fiber posts on biomechanical behavior of endodontically treated premolars

The aim of this study was to evaluate the effect of cavity design and glass fiber posts on stress distributions and fracture resistance of endodontically treated premolars. Fifty extracted intact mandibular premolars were divided into 5 groups (n = 10): ST, sound teeth (control); MOD, mesio-occlusal-distal preparation + endodontic treatment (ET) + composite resin restoration (CR); MODP, mesio-occlusal-distal + ET + glass fiber post + CR; MOD2/3, mesio-occlusal-distal + two thirds occlusal-cervical cusp loss + ET + CR; and MODP2/3, mesio-occlusal-distal + two thirds cusp loss + ET + glass fiber post + CR. The specimens were loaded on a cusp slope until fracture. Fracture patterns were classified according to four failure types. Stress distributions were evaluated for each group in a two-dimensional finite element analysis. The fracture resistance of the MODP, MOD2/3, and MODP2/3 groups was significantly lower than the ST and MOD groups (p < 0.05). The loss of dental structure and the presence of fiber post restoration reduced fracture resistance and created higher stress concentrations in the tooth-restoration complex. However, when there was a large loss of dental structure (MODP2/3), the post reduced the incidence of catastrophic fracture types.     

Fracture resistance of simulated immature roots using Biodentine and fiber post compared with different canal-filling materials under aging conditions

Objective

The aim of this study was to evaluate the fracture resistance of simulated immature roots using Biodentine (BD) and fiber post (FP) compared with different root canal-filling materials under aging conditions.

Materials and methods

One hundred and forty maxillary central anterior teeth were randomly divided into seven groups (n = 20/group). Negative control received no treatment. In the other groups, the root canals were prepared to simulate immature teeth. The root canals were filled with a 4-mm apical plug of BD and restored intraradicular with BD, BD + FP, composite resin (CR), CR + FP, and gutta-percha (GP). Positive controls were instrumented but without restoration. Teeth were subjected to thermocycling and received cyclic loading before fracture resistance test. Fracture resistance was conducted using a universal testing machine with a crosshead speed of 0.5 mm/min until fracture. Load to fracture was recorded in newtons (N). Data were statistically analyzed using one-way analysis of variance and Tukey’s test at P < 0.05.

Results

Root canals restored intraradicular with BD + FP and CR + FP showed the highest fracture resistance compared with the other experimental groups (P < 0.001). There was no significant difference in the fracture resistance between CR and BD groups (P = 0.998). GP and positive control groups were significantly lower resistance to fracture than the other groups (P < 0.001).

Conclusions

Intraradicular reinforcement with BD + FP and CR + FP enhanced the fracture resistance of simulated immature teeth than the other experimental groups.

Clinical relevance

Biodentine or composite resin combined with fiber post could be used to reinforce immature teeth with an apical Biodentine plug.

     

Reinforcement of Simulated Immature Permanent Teeth after Mineral Trioxide Aggregate Apexification

Objectives

The objectives of this study were to compare the fracture resistance of simulated human immature teeth that have undergone mineral trioxide aggregate (MTA) apexification and have been root-filled with fiber post, composite resin, MTA, or gutta-percha.

纤维树脂桩核系统修复牙根发育不完全牙后抗折强度的分析

目的通过对经根管治疗后使用玻璃纤维桩核进行修复的牙根发育不完全牙各部位抗折强度的测量比较,以期为临床使用桩核系统修复根尖诱导成形术后的牙降低根折风险提供依据。方法收集符合纳入标准的因正畸需要拔除的根尖发育不完全,根尖孔未形成的第1、2前磨牙45颗,随机分成3组。分别为纤维桩复合树脂水门汀组(实验组)、复合树脂水门汀组(阳性对照组)、根管充填后不作处理组(阴性对照组),每组样本15颗,常规桩道预备后用复合树脂和桩核系统进行修复,将修复后的样本牙进行包埋,采用TY-8000型电子万能测试机分别测量牙根颈1/3和中1/3区域的抗折强度,比较经纤维桩核系统修复后牙根不同部位的抗折强度。采用SAS软件包对所得数据进行统计学分析。结果实验组的牙根颈部、中部的抗折强度分别为(999±75.40)N和(799±21.77)N,阴性对照组分别为(501±38.4)N和(472±22.98)N,阳性对照组分别为(704±88.39)、(550±20.14)N。实验组的牙根各部位的抗折能力均最强,与阳、阴性对照组均有显著差异(P<0.0001)。结论纤维桩核系统对牙根抗折性能有显著影响,植入纤维树脂桩的牙齿在牙根颈1/3和中1/3区域都显示出比植入复合树脂粘接材料和仅经根管充填后的牙齿具有更大的抗折强度。     

Influence of Smear Layer Treatment on Resistance to Root Fracture in Tooth Restored with Epoxy Fiber Post

To evaluate the influence of complete smear layer removal by EDTA on the resistance of root fracture of tooth restored with fiber post. Twenty single rooted premolars with average root length 16 ± 1 mm were randomly divided into two groups of ten each. All teeth were obturated with guttapercha after root canal preparation, sectioned 4 mm above the cement-enamel junction. In group I, teeth root canals were etched with 37 % phosphoric acid, fiber post cemented with self adhesive resin cement. In group II, teeth radicular dentin was treated with 17 % EDTA, followed by fiber post cementation with dual cure resin cement. Coronal part of the teeth reestablished with posterior composite and NiCr full veneer coping along with 2 mm circumferential ferrule. Restored teeth were loaded with incremental force at 30° to the long axis of the root until fracture occurred. The data obtained was evaluated with paired sample T test to compare the fracture resistance between the test groups. Group I had the mean failure load of 1,883.70 N while group II had 1,622.80 N mean failure load. Paired sample T test showed statistically significant (p value = 0.033) failure load difference between the groups tested. Within the limits of this study, it may be concluded that: the complete removal of smear layer by EDTA found to have reduced the fracture strength of tooth roots restored with an epoxy fiber post.