Up to 17-year controlled clinical study on post-and-cores and covering crowns

OBJECTIVE: The aim of this long-term follow-up was to collect up to 17-year survival data of different metal post-and-core restorations with a covering crown. METHODS: At initiation of the study, a controlled clinical trial, single tooth was provided with an artificial covering crown, by 18 operators. Restorations under investigation were the post-and-core restorations: cast post-and-core restorations, prefabricated metal post and resin composite core restorations, and post-free all-composite core restorations. Before treatment allocation, the recipient tooth was categorized according to the expected dentin height after tooth preparation. A tooth was assessed to have "substantial dentin height" (Trial 1) or "minimal dentin height" (Trial 2). The study sample consisted of 257 patients that received 307 core restorations. The performance of the restorations was based on data collected from the files of the current dentists monitoring the oral health of the patients. The survival probability was analyzed at different levels: on the restoration level (S(R)), and on the level of the tooth carrying the restoration (S(T)). Kaplan Meier analyses were used to compare survival probabilities. RESULTS: "Type of post-and-core restoration" showed no influence on the survival probability (at both levels) in both trials (P-value>0.05). The 17-year survival rates at restoration level varied from 71% to 80%, and at tooth level from 83% to 92%. CONCLUSIONS: The results of this study showed no difference in survival probabilities among different core restorations under a covering crown of endodontically treated teeth. The preservation of substantial remaining coronal tooth structure seems to be critical to the long-term survival of endodontically treated crowned teeth.     

Clinical evaluation of root filled teeth restored with or without post-and-core systems in a specialist practice setting

AIM: To assess survival rates and complications of root-filled teeth restored with or without post-and-core systems over a mean observation period of >or=4 years. METHODOLOGY: A total of 325 single- and multirooted teeth in 183 subjects treated in a private practice were root filled and restored with either a cast post-and-core or with a prefabricated titanium post and composite core. Root-filled teeth without post-retained restorations served as controls. The restored teeth served as abutments for single unit metal-ceramic or composite crowns or fixed bridges. Teeth supporting cantilever bridges, overdentures or telescopic crowns were excluded. RESULTS: Seventeen teeth in 17 subjects were lost to follow-up (17/325: 5.2%). The mean observation period was 5.2 +/- 1.8 (SD) years for restorations with titanium posts, 6.2 +/- 2.0 (SD) years for cast post-and-cores and 4.4 +/- 1.7 (SD) years for teeth without posts. Overall, 54% of build-ups included the incorporation of a titanium post and 26.5% the cementation of a cast post-and-core. The remaining 19.5% of the teeth were restored without intraradicular retention. The adjusted 5-year tooth survival rate amounted to 92.5% for teeth restored with titanium posts, to 97.1% for teeth restored with cast post-and-cores and to 94.3% for teeth without post restorations, respectively. The most frequent complications included root fracture (6.2%), recurrent caries (1.9%), post-treatment periradicular disease (1.6%) and loss of retention (1.3%). CONCLUSION: Provided that high-quality root canal treatment and restorative protocols are implemented, high survival and low complication rates of single- and multirooted root-filled teeth used as abutments for fixed restorations can be expected after a mean observation period of >or=4 years.     

Survival rate and fracture strength of endodontically treated maxillary incisors with moderate defects restored with different post-and-core systems: an in vitro study

PURPOSE: This study compares the survival rate and fracture strength of endodontically treated maxillary incisors with moderate coronal defects restored with different post-and-core systems after exposure to an artificial mouth. MATERIALS AND METHODS: Sixty-four caries-free human maxillary central incisors were selected for standardized size and quality, endodontically treated, and decoronated 2 mm coronal to the cementoenamel junction. Group 1 was restored with titanium posts and composite cores, group 2 received zirconia posts and a composite core, and in group 3 zirconia posts with a heat-pressed ceramic core were used. Teeth restored with cast posts and cores served as controls. All teeth were prepared and restored with complete cast crowns. All samples were exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling. In addition, the samples were loaded until fracture in a static testing device. RESULTS: The survival rates of the different groups were: 94% for titanium/composite, 63% for zirconia/composite, 100% for the all-ceramic post and core, and 94% for the cast post and core. The following mean fracture strengths were obtained: titanium/composite = 425 +/- 155 N, zirconia/composite = 202 +/- 212 N, zirconia/ceramic = 378 +/- 64 N, cast post and core = 426 +/- 178 N. The lower fracture load in the group with zirconia posts and composite cores was statistically significant. The use of zirconia posts resulted in fewer oblique root fractures. CONCLUSION: Prefabricated titanium posts with composite cores, zirconia posts with heat-pressed ceramic cores, and cast posts and cores yield comparable survival rates and fracture strengths for the restoration of crowned maxillary incisors with moderate coronal defects. Survival rates and fracture strengths for zirconia posts with composite cores are significantly lower, so this combination cannot be recommended for clinical use.     

A comparison of composite post buildups and cast gold post-and-core buildups for the restoration of nonvital teeth after 5 to 10 years

PURPOSE: The aim of this study was to compare the cumulative survival rates and the complication rates of established methods of indirect cast posts and cores and direct posts and composite cores over at least 5 years within a retrospective study of patients who received fixed restorations. MATERIALS AND METHODS: The patients were questioned according to a protocol and were examined clinically and radiologically. Of the 101 patients who were recruited, 72 came for a follow-up examination. RESULTS: Forty-one cast posts and cores and 31 composite cores were examined clinically and radiologically after an average observation period of 8.56 (SD 1.45) years. Four teeth were extracted during the observation period, and 2 more were extracted at the time of the examination. This resulted in cumulative survival rates of 90.2% for cast posts and cores and 93.5% for composite cores. There were 28 complications altogether, consisting of 2 (7.1%) root fractures, 8 (28.6%) teeth with increased probing depths, 3 (10.7%) with increased degrees of mobility, 4 (14.3%) with caries, 9 (32.1%) with periapical radiolucency and/or retrograde filling, and 2 (7.1%) with loss of retention. No statistically significant differences between the 2 methods could be found regarding survival and complication rates. CONCLUSION: It can be concluded that over an average observation period of 8.56 years the indirect cast post-and-core buildup and the direct composite post buildup can be considered of similar value.     

Investigation of the fracture resistance of three types of zirconia posts in all-ceramic post-and-core restorations

PURPOSE: All-ceramic post-and-core restorations offer a number of advantages compared with systems that use metal cores. In certain clinical cases, however, fractures at the junction between the post and the core have been reported. The objective is therefore to improve the strength between the post and the core. MATERIALS AND METHODS: Three different methods were used to fabricate all-ceramic post-and-core restorations: pressing IPS Empress cores directly to CosmoPost zirconia posts, adhesively luting IPS Empress cores to CosmoPost zirconia posts, and Celay milling In-Ceram zirconia blanks to one-piece post-and-core restorations. Ten restorations were prepared with each of the three methods. The post-and-core complexes were tested to failure with the load applied perpendicular to the post axis. The load and deflection at fracture were recorded. RESULTS: The highest breaking load and highest deflection were recorded for the luting technique, with values of 25.3 N and 394 microns, respectively. The corresponding values for the pressed cores and the milled zirconia cores were 22 N and 301 microns, and 13 N and 160 microns. All differences were statistically significant at P < .05. Regarding the load dependence of the deflection, the luted cores again demonstrated the highest mean value, with 15.5 microns/N, while this value was 13.6 microns/N and 13 microns/N for the pressed-on and milled cores, respectively. These differences were not statistically significant. CONCLUSION: Adhesively luted all-ceramic cores on zirconia posts offer a viable alternative to the conventional pressed technique.     

不同材质桩核修复漏斗状残根的抗疲劳强度

目的探讨不同材质桩核修复对漏斗状前牙牙根抗疲劳强度的影响。方法30颗离体上颌中切牙均分为无领圈和有领圈2个实验组。各实验组再分为3部分,各5颗样牙。本分别用铸造金属桩核(MPC)、单纯复合树脂桩核(RCP)及预成碳纤维桩联合复合树脂桩核(FRC)进行修复。测定各样本牙疲劳强度并对实验结果进行双因素方差检验(α=0.05)。结果各实验组用FRC修复者与用其他2种材料者相比,均表现出明显高的平均疲劳强度(P<0.05)。预备牙本质领圈可明显提高不同材质桩核修复牙的疲劳强度(P<0.05)。结论FRC在提高前牙牙根抗疲劳强度方面具有明显优点。为提高前牙牙根的抗疲劳强度,预备牙本质领圈是必要的。     

Four post-and-core combinations as abutments for fixed single crowns: a prospective up to 10-year study

PURPOSE: In the present prospective study, four different post-and-core systems were evaluated over a period of up to 10 years. MATERIALS AND METHODS: Fifty endodontically treated teeth in 31 patients were randomized to one of four groups for post-and-core placement: Group 1 received conventional tapered cast posts and cores (n = 14); group 2 received ParaPost system prefabricated gold posts with cast cores (n = 13); group 3 received ParaPost system cast posts and cores (n = 13); and group 4 received Radix-Anchor posts (n = 10). Clinical and radiologic evaluations were made. RESULTS: One post and core in group 2 was functioning well 58 months after placement when the patient died. No posts and cores in groups 1 or 2 had been lost or had any complications, one in group 3 had been lost because of a root fracture after 108 months, and two in group 4 had been lost after 54 and 88 months, respectively, because of loss of retention. The final treatment result for 46 of the 49 remaining posts (30 patients) was successful. The overall failure rate was 6%. There were no statistically significant differences between the four groups. CONCLUSION: If recommended procedures are strictly followed, posts and cores can serve as abutments for fixed single crowns with satisfactory long-term results.     

Effect of core stiffness on the in vitro fracture of crowned, endodontically treated teeth

STATEMENT OF PROBLEM: Dentin and core materials that substitute for missing dentin are dissimilar materials. A core material with a lower elastic modulus may deform more under applied stress and therefore result in reduced stress concentration at the core/dentin junction. PURPOSE: This in vitro study examined the effect of core stiffness on the fracture resistance and failure characteristics of a crowned, endodontically treated tooth under simulated occlusal load. MATERIAL AND METHODS: Forty extracted human mandibular premolars were divided equally into 4 groups and prepared for posts and cast crowns as follows: group 1 = cast post and core, cast crown; group 2 = preformed metal post, composite core, and cast crown; group 3 = preformed metal post, amalgam core, and cast crown; and group 4 (control) = preformed metal post, no core, and cast crown. All prepared teeth had 2 mm of sound dentin on which the cemented crown rested. A continuous load (kg) was applied to the buccal cusp at a 30-degree angle to the long axis of each tooth at a crosshead speed of 2 mm/min until failure. Collected data were subjected to 1-way analysis of variance with the Welch modification to compare groups (P<.05). RESULTS: Failure loads for the 4 test groups were as follows: 98.1 +/- 34.6 kg (group 1), 94.4 +/- 41.8 kg (group 2), 105.5 +/- 18.6 kg (group 3), and 101.1 +/- 55.3 kg (group 4). No significant difference in failure load values was found among the 4 groups. The primary mode of failure (80%) in all groups was an oblique radicular fracture, either apical to the post or at the post level. Horizontal fracture of the root and post was found in groups 1, 2, and 3 (20%). Loosening of the crown, post, and core was found only in group 2(20%). CONCLUSION: Within the limitations of this study, core stiffness did not affect the failure resistance of teeth restored with posts and cores and complete-coverage cast metal crowns. The dominant pattern of failure was unrepairable root fracture. Only the composite core exhibited repairable fractures.     

Resistance of three new esthetic post-and-core systems to compressive loading

STATEMENT OF PROBLEM: Despite their esthetic properties, the fracture resistance of newly introduced esthetic post-and-core systems has not been studied, restricting clinical use. PURPOSE: The purpose of this study was to determine and compare the fracture resistances of 3 recently introduced esthetic post-and-core systems with a cast metal post and core using a clinically related test method. MATERIAL AND METHODS: Forty recently extracted caries-free maxillary central incisors were selected, sectioned, and their roots endodontically treated. The roots were then embedded in acrylic resin blocks and assigned to 4 experimental groups (n = 10). The cast metal (Wiron 99) post-and-core group (CMDC) served as the control. Three experimental groups consisted of a stainless steel post/composite-resin (Charisma) core group (SCOM), zirconium dioxide post/composite-resin (Charisma) core group (ZCOM), and zirconium dioxide post/ceramic (Cosmopost) core group (ZCER). The post spaces were prepared, posts were seated, cores were formed, and 40 post-and-core foundations were cemented into the roots. Following thermal cycling (5000 cycles between 5 degrees C and 55 degrees C with a dwell time of 30 seconds), a compressive load was applied to the inclined surface of each specimen at a 130-degree angle to the specimen long axes in a universal testing machine at a crosshead speed of 1 mm/min until failure occurred. Force to failure (N) was recorded. Data were analyzed with a 1-way analysis of variance and Bonferroni tests to determine the difference between the groups (alpha=.05). For pairwise comparisons among group mean values, P < .0083 indicated statistical significance and established the overall confidence level at 95%. RESULTS: Groups CMDC (738.6 N +/- 10.2) and ZCER (710.2 N +/- 5.3) exhibited the highest resistance to fracture. The ZCOM group showed the lowest fracture resistance (450.3 N +/- 5.7). The fracture resistance of the SCOM group (565 N +/- 7.2) was lower than the CMDC and ZCER groups, and higher than the ZCOM group. The differences among the groups were significant (P < .001) except for CMDC and ZCER (P < .016). CONCLUSION: Within the limitations of this study, the cast metal post/core and zirconia post/ceramic core foundations were found to be more fracture resistant than the zirconia post/composite-resin core and stainless steel post/composite-resin core foundations. Aside from its desirable esthetic properties, the zirconia post/ceramic core combination demonstrated high resistance to fracture.     

Survival of Dicor glass-ceramic dental restorations over 16 years. Part III: effect of luting agent and tooth or tooth-substitute core structure.

STATEMENT OF PROBLEM: The influence of different types of restorative design features on the long-term survival of Dicor glass-ceramic restorations is only partially understood. PURPOSE: This study examined the effect of different types of luting agents and preparation core structures on the survival of Dicor glass-ceramic restorations functioning in vivo. MATERIAL AND METHODS: A total of 1444 Dicor glass-ceramic restorations were placed on the teeth of 417 adults. Failure was defined as a restoration that required remake because of material fracture. The survival of restorations of different types, with different luting agents and preparation core structures, was described with Kaplan-Meier survival functions. The significance of differences in survival between different tooth or tooth-substitute preparation core structures and different luting agents was determined with the log-rank test. RESULTS: The probability of survival of a typical acid-etched Dicor restoration luted to gold preparation core structures was 91% at 16 years compared with 75% for dentin preparation core structures (P<.01). The survival of acid-etched Dicor restorations luted to dentin preparations was significantly better than nonacid-etched restorations luted to dentin. Acid-etched Dicor restorations luted with resin composite exhibited a more favorable survival function than those luted with glass ionomer (P<.01) and zinc phosphate (P<.05). Differences between restorations luted with glass ionomer or zinc phosphate agents were not significant. CONCLUSION: Acid-etched Dicor restorations luted to gold preparation core structures exhibited significantly better intraoral survival than restorations luted to dentin. Acid-etched Dicor restorations survived better than nonacid-etched restorations when luted to dentin preparations. Acid-etched Dicor restorations luted with resin composite exhibited more favorable survivor functions than restorations luted with glass ionomer or zinc phosphate agents.     

Long-term survival of endodontically treated,maxillary anterior teeth restored with either tapered or parallel-sided glass-fiber posts and full-ceramic crown coverage

Objectives

This retrospective study investigated the clinical effectiveness over up to 8 years of parallel-sided and of tapered glass-fiber posts, in combination with either hybrid composite or dual-cure composite resin core material, in endodontically treated, maxillary anterior teeth covered with full-ceramic crowns.

Methods

The study population comprised 192 patients and 526 endodontically treated teeth, with various degrees of hard-tissue loss, restored by the post-and-core technique. Four groups were defined based on post shape and core build-up materials, and within each group post-and-core restorations were assigned randomly with respect to root morphology. Inclusion criteria were symptom-free endodontic therapy, root-canal treatment with a minimum apical seal of 4 mm, application of rubber dam, need for post-and-core complex because of coronal tooth loss, and tooth with at least one residual coronal wall. Survival rate of the post-and-core restorations was determined using Kaplan–Meier statistical analysis.

Results

The restorations were examined clinically and radiologically; mean observation period was 5.3 years. The overall survival rate of glass-fiber post-and-core restorations was 98.5%. The survival rate for parallel-sided posts was 98.6% and for tapered posts was 96.8%. Survival rates for core build-up materials were 100% for dual-cure composite and 96.8% for hybrid light-cure composite.

Conclusions

For both glass-fiber post designs and for both core build-up materials, clinical performance was satisfactory. Survival was higher for teeth retaining four and three coronal walls.     

Effects of cyclic loading on selected post-and-core systems.

OBJECTIVE: The purpose of this study was to evaluate the resistance of selected post-and-core systems to fatigue testing. METHOD AND MATERIALS: A fatigue-testing machine and data acquisition software were developed for this in vitro test. Pulpless mandibular second premolars were treated with three different types of post-and-core system: (1) two different prefabricated posts with amalgam cores, (2) the same two prefabricated posts with resin composite cores, and (3) cast post and cores, which served as the control group. The fatigue-testing machine applied alternating buccal and lingual forces to the core until lateral movement of 0.0025 inches (63.5 microns) was detected by a transducer contacting the surface of the core. This criterion represented initial cement failure. RESULTS: Although groups using the resin composite core material exhibited a higher number of cycles prior to failure, there was no statistically significant difference between the different post-and-core systems. CONCLUSION: All of the post-and-core systems that were tested may be acceptable for restoring endodontically treated teeth.     

An alternative method for fabricating a custom-made metal post with a ceramic core

Abstract –  The restoration of anterior non-vital teeth with metal posts and cores and all-ceramic restorations may lead to compromised esthetics because of the semitranslucence of ceramics and the metallic color of the underlying post and cores. This article presents a technique that combines the optical properties of ceramic cores with the mechanical properties of custom-made cast metal posts. The technique involves heat pressing of the core from leucite-enriched glass-ceramic to the underlying custom-made metal post and may provide additional esthetic benefit for anterior teeth especially with little remaining coronal dentin and with small root volume.     

An up to 3-Year Controlled Clinical Trial Comparing the Outcome of Glass Fiber Posts and Composite Cores with Gold Alloy-Based Posts and Cores for the Restoration of Endodontically Treated Teeth

Purpose: This controlled clinical trial aimed to compare the 3-year outcomes of glass fiber posts and composite cores with gold alloy-based posts and cores for the restoration of endodontically treated teeth. Materials and Methods: One hundred forty-four patients in need of 205 restorations on endodontically treated teeth were selected and followed for 7 to 37 months (mean: 21 ± 9 months). The teeth were primarily stratified based on the remaining tissue available to restore the tooth core with or without a post. Then, randomization allocated the teeth to either test group 1 (prefabricated glass fiber posts), test group 2 (custom-made glass fiber posts), or test group 3 (composite cores without posts). The control group consisted of gold alloy-based posts and cores. All posts/cores were covered with all-ceramic single crowns. Failures were either absolute, such as root fractures or irreparable fractures of the post/core, or relative, such as loss of post retention or reparable fractures of the core. Success and survival probability lifetime curves, corrected for clustering, were drawn for the entire data set. Results: The recall rate at 3 years was 97.1%. Absolute failures consisted of two root fractures and one endodontic failure, while relative failures included three instances of retention loss of the post/core and one post fracture. Because of the low number of events, no statistical tests were performed. The success and survival probabilities over all groups together at 3 years amounted to 91.7% and 97.2%, respectively. Conclusions: After being followed for up to 3 years, both cast gold and composite post and core systems performed well clinically. Longer follow-up times are needed to detect possible significant differences. Int J Prosthodont 2011;24:363-372.     

A 3-year postoperative clinical evaluation of posts and cores beneath existing crowns.

Fabrication of posts and cores for fixed partial denture (FPD) and removable partial denture (RPD) abutment restorations is common in dentistry. The biocompatibility of various post and core techniques with the restorations was clinically evaluated according to location and function. In this study, 154 post and core constructions for 150 patients were observed for a 3-year period to determine if the function of the original restorations remained unsatisfactory. The following techniques were included: (1) screw post and light-curing composite resins, (2) cemented post with parallel sides and light-curing composite resins, and (3) a cast and core technique. Seventeen of the 154 restorations failed; four failures were attributed to root fractures, three to radicular caries, and five to crown dislodgement, while five failures were from detachment of the post and core from the root. The statistical analysis revealed that only the factor "type of abutment" (RPDs and FPDs) had some effect on the failure of the restorations.     

Prospective clinical trial of polyethylene fiber ribbon-reinforced, resin composite post-core buildup restorations

The aim of this prospective clinical trial was to determine the outcome of polyethylene fiber ribbon-reinforced, resin composite post-and-core restorations used as endodontic buildups to support all-ceramic crowns. A total of 42 teeth (31 anterior, 11 posterior) with a mean follow-up time of 35.85 months (range, 10 to 73 months) were treated with 3-mm-wide polyethylene fiber ribbon-reinforced resin composite as post-and-core material. The posts and cores were assessed by clinical and radiographic examination. During the evaluation period, only 1 dentin-cement failure was observed as a post dislodgement after 11 months of clinical service. Performance of polyethylene fiber ribbon post and resin composite core foundation restorations provided clinically satisfactory support for all-ceramic crowns.     

Stress generation in mandibular anterior teeth restored with different types of post-and-core at various levels of ferrule

Statement of problem

Pertinent evidence regarding the mechanical integrity of mandibular anterior teeth restored with a post-and-core is limited.

Survival rates of endodontically treated teeth restored with fiber-reinforced custom posts and cores: a 97-month study

PURPOSE: This study aimed to assess the long-term survival rates of polyethylene fiber-reinforced posts and cores used in endodontically treated teeth over a 97-month period. MATERIALS AND METHODS: Sixty-nine patients from a private dental office who underwent endodontic treatment with coronoradicular fiber-reinforced restorations were selected and invited for evaluation. All teeth were restored with the same high-molecular-weight polyethylene fiber (Ribbond, Ribbond Inc) and resin composite cement (Enforce, Dentsply) post-and-core system by a single operator and then prepared and restored with complete cast crowns or direct resin composite. Survival functions of restorations were analyzed with Kaplan-Meier and log-rank tests (alpha = .05) and displayed according to the variable tooth location and material of the definitive restoration. RESULTS: Four posts fractured among the 36 anterior restorations evaluated, and 2 posts fractured among the 73 posterior restorations. The mean overall survival estimate was 90.2 (+/- 3.7) months (95% Cl: 82.8-97.5). There were no differences between survival functions regarding tooth location or type of restorative material as variables (P> .05). CONCLUSIONS: The results suggest that polyethylene fiber-reinforced posts with composite cores may be recommended for clinical use. Restorations evaluated in this study presented high survival rates after the 97-month follow-up period.     

桩核冠受力时的应力分析

目的：用三维有限元法对桩核冠进行应力分析,研究不同材质的冠对分析结果的影响。方法：采用测量法建模,根据标准的桩核冠制作要求,应用美国I-DEAS有限元分析软件分别建立三套上中切牙的三维有限元模型．其中A组包括铸造金属桩核、制备后的牙体组织、牙周组织;B组包括金属烤瓷冠、铸造金属桩核、制备后的牙体组织、牙周组织;C组包括树脂冠、铸造金属桩核、制备后的牙体组织、牙周组织。在同等条件下以上中切牙的平均糟力分别给予加载,并对计算结果进行综合分析。结果：（1）从牙本质的应力大小来看,A组中牙本质最大应力值比B组中牙本质最大应力值增大了1倍以上（最大主应力、最小主应力和最大剪切应力A组分别是B组的236．35％、228．83％和218．05％）,而B组与C组的牙本质最大应力值相差极小;（2）从牙本质的应力分布位置来看,A组与B组的牙本质最大应力分布位置相差甚远（A组主要集中在牙颈部唇舌侧肩台部的牙本质上．B组主要集中于牙槽嵴顶附近及铸造桩核尾端相对应的唇舌侧的牙本质上）,而B组与C组的牙本质最大应力分布几乎在同一位置。结论：用三维有限元法对桩核冠进行应力分析时,不同材质的冠对分析结果无明显影响。     

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。