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The restoration of endodontically treated teeth involves a difficult decision-making process, especially when it comes to more complex prosthetic rehabilitations. Regarding singletooth restoration, there are high-level requirements for the restorative components and the application of all necessary treatment steps to achieve the final restoration. So when is there a need for a single-crown restoration or when might a composite resin restoration also be sufficient? For the assessment of endodontically treated teeth as abutment teeth for prosthetic restorations, there are no clear guidelines beyond single-tooth restorations. The aim of this article is to compile important aspects of the restoration of endodontically treated single teeth, including more complex prosthetic reconstructions, based on the scientific literature.

This study introduces a modified dynamic testing mode with gradual load increase and examines whether this could be an alternative to customary methods of static loading or chewing simulation. Seventy-two extracted human maxillary root-canal-treated central incisors were randomly divided into six groups with 12 teeth each. Three groups were restored with titanium posts cemented with chemically curing resin cement. The other three groups were restored with glass-fiber posts cemented with dual-curing composite cement. All teeth were capped with full ceramic crowns. Both kinds of restoration were tested by linear compressive (static) loading, a modified gradual (cycling) dynamic loading, and by chewing simulation followed by static loading until failure occurred. The maximum load capacity was recorded. Statistical comparison showed that maximum load capacities of the same post material obtained from gradual dynamic loading did not differ significantly from that of linear compressive loading or of chewing simulation. In contrast, comparisons of different post materials under static loading resulted in significantly different load capacities. Dynamic testing with gradual load increase can be considered an economic alternative for chewing simulation, because it provides equivalent results. Both procedures, however, imply different conclusions than static loading with respect to post materials., (Copyright 2005 Wiley Periodicals, Inc.)

Purpose: The objective of this systematic review was to assess the impact of endodontic post insertion on the clinical performance of endodontically treated teeth (ETT). Materials and Methods: A specific PICO question was developed and a Medline search was performed in January 2017 using relevant terms in order to identify studies comparing the success/survival of dental restorations using endodontic posts or no posts. Additionally, the electronic databases "Opengrey", "BBO", "LILAC" and "IBECS" were assessed and a hand search of cross references from original articles and reviews was performed. The methodological quality of the included studies was assessed independently by three referees using (1) the critical appraisal skills program (CASP) and (2) Cochrane checklist (version 5.1.0). Results: A total of 14 studies were included, among them 11 randomized controlled trials (RCT), two prospective clinical trials, and one retrospective clinical trial. The overall quality of the studies was good according to the CASP. However, the Cochrane rating showed that in seven studies, the risk of bias was high in > 40% of the items, indicating a relevant level of methodological flaws. Three studies showed a low risk of bias in > 80% of the items. The majority (10 out of 14) of the clinical studies included failed to show a positive effect of post placement. A post effect is possible when no cavity wall is present. Conclusion: There is no unequivocal clinical evidence to support or reject the use of posts even for no-wall cavities, either for direct or indirect restorations. [ABSTRACT FROM AUTHOR]

Objective: The prognosis of endodontically treated teeth depends not only on the success of the endodontic treatment, but also on the type of reconstruction. These considerations include the decision of whether or not to use posts. Methods and materials: A literature review has been performed to create guidelines for the reconstruction of endodontically treated teeth by posts and cores. Results: Posts should only be used for the retention of core material in cases where little dental substance remains, ie, one or no cavity walls. A ferrule of 2 mm has to be provided, by surgical means if necessary The post length is limited by the necessary apical seal of 4 to 6 mm. In cases of short posts, adhesive fixation is preferred. Ceramic posts show a higher risk of fracture than fiber posts which are retrievable. Composites have proven to be a good core material. Posts should be inserted if endodontically treated teeth are used as abutments for removable partial dentures. Conclusion: These guidelines are based mainly on in vitro studies with an evidence level of II a or II b, as there is a lack of randomized clinical studies available. The remaining tooth structure is an important factor influencing the indication of posts and cores, yet it is not sufficiently recognized in clinical studies and in vitro. Therefore, further prospective clinical studies are needed. [ABSTRACT FROM AUTHOR]

Objective: Assessment of long-term clinical data regarding post-endodontic restorations is essential for the evaluation of different post-and-core concepts. The aim of the present study was to assess the diagnostic accuracy of patient self-reporting on post-endodontic restorations after 11 years of clinical service.Materials and methods: Twenty-nine patients (61 ± 15 years old) with endodontic glass-fibre and titanium post-endodontic restorations were examined within the 11-year follow-up of a randomized controlled trial. Restorations were assessed by self-reports during a telephone interview (one item), the completion of a four-item questionnaire and clinical and radiographic examination. A gold standard for restoration in situ or 'failure' was defined by clinical and radiographic examination. Diagnostic accuracy of patients' self-reports was evaluated by calculating the sensitivity, specificity, and positive (PPV) and negative predictive values (NPV).Results: After a mean observation time of 137 months (min/max: 125/154 months), 25 (86.2%) restorations were in situ and 4 (13.8%) failures were detected. Self-report during a telephone interview and the four-item questionnaire correctly identified all in situ restorations (specificity = both 100%, NPV = 92.6%/96.2%). Self-report during a telephone interview identified two out of four failures (sensitivity = 50%, PPV = 100%), and self-report on the four-item questionnaire identified three out of four failures (sensitivity = 75%, PPV = 100%).Conclusions: When the clinical examination is not feasible, patients' self-report shows valuable diagnostic potential in the identification of the post-endodontic failure. [ABSTRACT FROM AUTHOR]

Introduction Both the role of an endodontic post and the ferrule effect have been discussed for decades. The clinical impact of endodontic posts compared with post-free restoration with or without ferrule support was not systematically reviewed so far. It was assumed that the effect of an endodontic post compared with a post-free restoration can be evaluated only when at the same time a ferrule or no-ferrule situation was clinically compared. Methods The specific PICO question was as follows: Patient: adults with sufficient endodontic treatment needing a core or post; Intervention: post-endodontic treatment using posts with or without ferrule; Comparison: post-endodontic treatment without posts with or without ferrule; Outcomes: failure rates of post/core complexes with or without ferrule support. A Medline search was performed via PubMed in June 2017 using relevant electronic databases. Additionally, hand search was performed. Only prospective clinical studies in humans comparing the success/survival of teeth restored with or without posts over a minimum time of observation of 5 years were included. Results In total, 7 randomized controlled trials and 1 prospective clinical trial met inclusion criteria. Cochrane rating showed high risk of bias in 5 studies. Two of 3 studies support the ferrule-effect concept. Seven of 8 show no post effect. Clinical evidence regarding the influence of tooth location on its survival is scarce. Conclusion Ferrule effect and maintaining cavity walls are the predominant factors with regard to tooth and restoration survival of endodontically treated teeth. Most studies do not confirm a positive effect of post placement. [ABSTRACT FROM AUTHOR]

Introduction This is the first long-term randomized controlled trial to evaluate dentin-like glass fiber posts (GFPs) compared with rather rigid titanium posts (TPs) for post-endodontic restoration of severely damaged endodontically treated teeth with 2 or fewer remaining cavity walls. Methods Ninety-one subjects in need of post-endodontic restorations were randomly assigned to receive either a tapered GFP ( n = 45) or TP ( n = 46). Posts were adhesively luted by using self-adhesive resin cement, followed by composite core build-up and preparation of 2-mm ferrule design. Primary end point was loss of restoration for any reason. Kaplan-Meier curves were constructed, and log-rank test was calculated ( P < .05). Results After a follow-up of 132 months, 17 GFP and 20 TP restorations survived, and 19 failed (12 GFP, 7 TP). Failure modes for GFP were root fracture ( n = 4), core fracture ( n = 1), secondary caries ( n = 1), endodontic failure ( n = 2), extraction because of tooth mobility grade III associated with insufficient design of removable partial denture ( n = 1), tooth fracture ( n = 1), and changes in treatment plan ( n = 2); failure modes for TP were endodontic failure ( n = 5), root fracture ( n = 1), and 1 extraction for other reasons. Cumulative survival probability was 58.7% for GFP and 74.2% for TP. Conclusions When using self-adhesively luted prefabricated posts, resin composite core build-up, and 2-mm ferrule to reconstruct severely damaged endodontically treated teeth, tooth survival is not influenced by post rigidity. Survival decreased rapidly after 8 years of observation in both groups. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to assess current opinions, applied techniques, and materials for the restoration of endodontically treated teeth (ETT) in a nationwide survey in Germany. Material and methods: Completed questionnaires from 1,648 dentists were returned (response rate 63 %). Results: In general, posts were reported to be used more frequently (51 %) for indirect restorations than for direct restorations (21 %). Dentists restored anterior teeth (65 %) more frequently with direct restorations than posterior teeth (48 %). Compared to an earlier survey, fewer dentists stated that posttreatment stabilizes the remaining tooth structure. The ferrule effect as a key success factor was held by the vast majority of dentists (88 %). A trend towards adhesive techniques both for post placement and core build-up was observed. Composite resins (49 %) were reported to be used twice as much as zinc phosphate cement (24 %) for the luting of posts; composite resins were the core build-up material of choice (75 %). Amalgam was rarely used (0.2 %). Irrespective of the final restoration, fiber posts were the most popular post material (46 % for telescopic crowns vs. 69 % for single crowns). Conclusion: Adhesive composite core build-ups with and without fiber posts were the predominant treatment approach to restore ETT in Germany. There was widespread agreement with the ferrule effect as a key restorative success factor for indirect restorations. Clinical significance: Today, it is general accepted that ferrule preparation is key. Glass-fiber posts appear to be most popular. Still different systems are used depending on type of final restoration, while the reasons to do so remain unclear. [ABSTRACT FROM AUTHOR]

A biography of Michael Naumann, Professor, Department of Prosthetic Dentistry at the Center of Dentistry, University of Ulm, Ulm Germany is presented. He was board certified and licensed to practice dentistry from the Dental School, Charite, Humboldt University, Berlin, Germany in 1999 and received his doctoral degree from the same university in 2001. His research interests include the areas of adhesive post-endodontic restorations and implantology.

The article discusses a clinical study conducted to evaluate the survival rate of teeth that were endodontically treated and restored with endodontic posts and either fixed partial or combined removable dentures. The authors concluded that teeth restored with post-and-cores has a high risk of failure when used as abutments for fixed-removable partial dentures. It cites the need to evaluate carefully the degree of destruction before endodontic therapy in terms of mechanical integrity.

Abstract: Introduction: This is the first clinical long-term pilot study that tested the biomimetic concept of using more flexible, dentine-like (low Young modulus) glass fiber–reinforced epoxy resin posts (GFREPs) compared with rather rigid, stiff (higher Young modulus) titanium posts (TPs) in order to improve the survival rate of severely damaged endodontically treated teeth. Methods: Ninety-one subjects in need of postendodontic restorations in teeth with 2 or less remaining cavity walls were randomly assigned to receive either a tapered TP (n = 46) or a tapered GFREP (n = 45). The posts were adhesively luted using self-adhesive resin cement. The composite core build-ups were prepared ensuring a circumferential 2-mm ferrule. The primary endpoint was a loss of restoration for any reason. To study group differences, the log-rank test was calculated (P < .05). Hazard plots were constructed. Results: After 84 months of observation (mean = 71.2 months), 7 restorations failed (ie, 4 GFREPs and 3 TPs). The failure modes were as follows: GFREP:root fracture (n = 3), core fracture (n = 1) and TP:endodontic failure (n = 3). No statistical difference was found between the survival rates (GFREPs = 90.2%, TPs = 93.5%, P = .642). The probability of no failure was comparable for both post materials (risk ratio; 95% confidence interval, 0.965–0.851/1.095). Conclusions: When using self-adhesive luted prefabricated posts in severely destroyed abutment teeth with 2 or less cavity walls and a 2-mm ferrule, postendodontic restorations achieved high long-term survival rates irrespective of the post material used (ie, glass fiber vs titanium). [Copyright &y& Elsevier]

Introduction: This ex vivo pilot study tested the influence of defect extension and quartz-fiber post placement (QFP) on the ex vivo survival rate and fracture resistance of root-treated upper central incisors served as abutments for zirconia 2-unit cantilever fixed partial dentures (2U-FPDs) exposed to 10 years of simulated clinical function. Methods: Human maxillary central incisors were endodontically treated and divided into the following 5 groups (n = 8): (1) access cavity filled with core build-up composite, (2) biproximal class III cavities filled as in group 1, (3) specimens restored as in group 2 with QFP placed, (4) specimens decoronated and core buildup as in group 1, and (5) specimens restored as in group 4 but with QFP as in group 3. On all specimens, 2U-FPDs were placed with dual-curing resin cement. In order to simulate 10 years of clinical function, specimens were exposed to thermal cycling and mechanical loading with subsequent loading to failure. Kaplan-Meier curves were constructed, and log-rank tests were performed. Fracture force and patterns were compared by means of Kruskal-Wallis, Mann-Whitney U (post hoc), and Fisher exact tests, respectively (P = .05). Results: For specimens only with an access cavity, it was observed that 25% had catastrophic tooth fractures and the lowest load-to-fracture values. In all other groups, chipping combined with or without debonding occurred. Groups did not differ significantly regarding the survival rate (P = .603) and fracture patterns (P = .633), but they did for fracture load including technical failures (P = .017). Conclusions: After 10 years of simulated clinical function, both defect extension and placement of QFP had no significant influence on survival of root-treated upper central incisors as abutments restored with zirconia-based 2U-FPDs. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Glass-fiber–reinforced endodontic posts (GFRPs), in combination with composite resin core materials, are commonly used to build up damaged endodontically treated teeth. However, long-term clinical data are scarce. Thus, the aim of this investigation was to evaluate the survival of 3 different GFRP systems, taking into account several other relevant factors. Methods: One-hundred forty-nine GFRPs in 122 patients were followed for up to 120 months. GFRPs were adhesively luted using the etch-and-rinse technique. The core was built with a chemically curing composite resin and restored according to the specific prosthetic treatment plan. Cox proportional hazards models were used to evaluate the association between clinical variables and the time until failure. Results: Within 10 years, 55 failures could be observed (annual failure rate = 4.6%) with the most frequent ones being post fracture, loss of post retention (both n = 17), endodontic problems (n = 7), and those resulting in tooth extraction (n = 10). Sixty posts could be followed up for 105 to 120 months (34 posts lost to follow-up, [mean (standard deviation) survival time: 74 (43) months]). In crude analyses, only the tooth type in favor of posterior teeth compared with anterior teeth and the number of remaining cavity walls (in favor of ≥1compared with no wall) were significantly associated with the failure rate. Cox regression analysis revealed a significant hazard ratio of 2.0 (95% confidence interval, 1.1–3.5; P = .021) for tooth type in favor of posterior teeth. Conclusions: The relatively high annual failure rate of GFRPs highlights that the treatment decision should take into account the most relevant factors as tooth type and the number of remaining cavity walls. [Copyright &y& Elsevier]

Full-crown restorations made by galvano forming may be considered as highly biocompatible, stable and aesthetic restorations. Therefore, they represent an alternative to conventional metal-ceramic crowns (MC), which might be associated with an allergic or toxic reaction due to metal oxides. In current literature, there are few clinical reports available, but no comparative clinical evaluation of these two systems. Thus, the purpose of this clinical observation was to compare the long-term success of galvano-formed crowns (GC) and MC and to evaluate post-operative complications. The working hypothesis was that there was no difference in clinical success between crowns based on galvano-forming procedure or conventional metal-ceramic crowns. A prospective, randomised, double-blinded clinical trial was conducted. 48 GC and 48 MC were placed in 48 periodontal healthy patients (male = 24; female = 24) in a split-mouth design. Prosthetic parameters as technical, biological and endodontic problems were recorded. Restoration survival-MC vs. GC-was compared using a non-parametric Chi-square test by McNemar at 5% level of significance. The crown restorations were re-evaluated after an observation time of 13 to 64 months (mean = 40.5; SD = 11 months). 45 GC and 45 MC (94%) were in situ without any complications. No significant differences were found between GC and MC. Surface conditions differed only in part. Fractures of the veneering material were observed in one (2%) and two (4%) for MC and GC, respectively. The presented data indicate that GC appears to be a successful alternative to conventional MC systems. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the survival of glass fiber reinforced composite post (GFP) restorations and to identify risk factors for restoration failure. Methods: GFPs of three consecutively placed post systems, two tapered and one parallel-sided, were adhesively luted and the core was built with a resin composite. Teeth served as abutment teeth according to the prosthetic treatment plan. 149 GFP in 121 patients (age: 53 ± 15 year; 50 men; 71 women) were followed for 5-79 months (mean ± SD: 50 ± 21 months). Cox proportional hazards models were used to evaluate the association between several clinical variables and the failure rate. Results: After exclusion of endodontic failures (n=3), significantly higher failure rates were found for restorations of anterior teeth compared to posterior teeth (hazard regression (HR): 2.8; 95% confidence interval (CI): 14; 58: P= 0.004). Restorations in teeth with no proximal contacts compared to at least one proximal contact, single crowns compared to fixed partial dentures and less than two remaining cavity walls had a HR of 2.4 (C.I.: 0.8 - 7.1), 2.4 (CI: 0.6 - 8.7), and 1.5 (CI.: 0.6 - 3.8), respectively. However, these correlations were not statistically significant (P> 0.05). [ABSTRACT FROM AUTHOR]

Abstract: Recently, the appropriate, durable bond of adhesive systems and composite resin cements to retain endodontic posts was challenged. The question arises whether it would be possible to place glass fiber posts in a less technique sensitive conventional nonadhesive approach. The influence of nonadhesive, self-adhesive, and etch-and-rinse systems on load capability of postendodontic restorations was studied. Human maxillary central incisors were divided into 4 groups (n = 10). Teeth were endodontically treated and restored by using glass fiber posts luted with different cements/composite resin combinations: (1) RelyX Unicem (3M ESPE, Seefeld, Germany)/Clearfil Core (Kuraray Europe, Duesseldorf, Germany), (2) RelyX Unicem/LuxaCore, (3) zinc phosphate cement/Clearfil, and (4) LuxaCore (DMG, Hamburg, Germany)/Clearfil. A 2mm-ferrule preparation was performed. All specimens received adhesively luted all-ceramic crowns and were exposed to thermal cycling and mechanical loading before subsequent static loading. Significant differences between the experimental groups regarding load capability and fracture patterns were observed. The conventional non-adhesive post cementation is less reliable to withstand simulated functional forces compared to adhesive approaches. [Copyright &y& Elsevier]

Adhesive luting of the final restorations is supposed to support the overall strength of post-endodontically restored teeth. For evaluating adhesive vs conventional cementation, the load capability of adhesively restored endodontically treated teeth (ETT) with glass fibre-reinforced composite posts (GFRCP), resin composite cores and all-ceramic crowns was determined. Thirty-two caries-free human upper, central incisors were randomly assigned to four groups, endodontically treated and cut 2 mm above the cemento-enamel junction. All teeth were restored with GFRCP, composite core build-ups and all-ceramic crowns. All-ceramic crowns were cemented with zinc phosphate cement (I), glass ionomer cement (II), and a self-adhesive resin cement (III and IV). After thermo-mechanical loading, the specimens were loaded to fracture. Maximum load capability F max and fracture patterns were compared using non-parametric statistics. Median values for the maximum load capability F max (minimum/maximum) in [N] were: I = 503 (416/1,038), II = 442 (369/711), III = 502 (326/561) and IV = 518 (416/652). No statistically significant differences were found for F max ( p = 0.761) and fracture patterns ( p = 0.094) between the experimental groups. The type of cementation of all-ceramic crowns, whether self-adhesive or conventional, appears to have no impact on the load capability of ETT restored with GFRCP and composite core build-ups. [ABSTRACT FROM AUTHOR]

Abstract: Objective: The aim of the present study was to investigate the influence of the rigidity of different post materials (titanium versus glass fiber reinforced composite [FRC]) on the fracture resistance of endodontically treated teeth (ETT). Method: Forty-eight caries-free maxillary central incisors were randomly assigned to six groups (n =8). After endodontic treatment, teeth of four groups were flattened 2mm above and two groups at the cemento-enamel junction (CEJ). As control, specimens of one group received neither composite build-up nor post, and teeth were left empty (E). In another group only a resin composite build-up was placed (C). In two groups, both titanium and FRC posts were inserted. One group with titanium (2/T) and FRC (2/FRC) post received a 2mm deep ferrule preparation. For one group with titanium (0/T) and FRC (0/FRC) post no ferrule design was provided. All-ceramic crowns were adhesively luted on all specimens. Specimens were exposed to thermomechanical loading and finally statically loaded until failure. Results: The median fracture load values (min–max) were: E=317 (242–404); C=387 (335–475); 0/FRC=352 (0–440); 2/FRC=502 (326–561); 0/T=420 (0–548), 2/T=517 (416–653). Statistically significant differences were computed between E, C, 2/FRC, 0/T and 2/T; between C, 2/FRC and 2/T; between 0/FRC, 2/FRC and 2/T; between 0/T and 2/T regarding maximum fracture load. Significance: Fracture resistance of ETT is not influenced by the rigidity of the post material. The combination of ferrule preparation and endodontic post results in higher load resistance after TML than any other build-up design. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of the present investigation was to study the influence of a reduced bone support on the fracture resistance of endodontically treated teeth restored with glass fibre-reinforced posts (FRC). Methods: 30 caries-free maxillary central incisors were divided into 3 groups (n =10). Endodontic treatment was performed. Teeth were flattened 2mm above the cemento–enamel junction. Group I (control) simulated a clinical situation without horizontal bone loss. In group II a horizontal bone loss of 25% and in group III of 50% was simulated. All specimens received FRC posts and composite core restorations. All-ceramic crowns were adhesively cemented. Specimens were exposed to thermal cycling and mechanical loading (TCML) and finally statically loaded until failure in a universal testing machine ( =1mm/min). Non-parametric tests were used to compare median fracture loads between groups. Fracture modes were compared using Fisher''s exact test. Results: The median fracture load values (min/max) in [N] were: group I=501 (326/561), group II=422 (323/495); group III=352 (266/406), p =0.004. Two specimens in each group II and III failed during TCML. Statistical analysis revealed statistically significant differences between all test groups regarding maximum fracture load and mode of fracture. Conclusions: The fracture resistance of endodontically treated teeth restored adhesively with a FRC post, composite core, and all-ceramic crown is dependent on the level of surrounding supporting periodontal bone. Loss of alveolar bone loss due to periodontal disease may lead to an increased risk of failure. [Copyright &y& Elsevier]

Objective . The aim of this study was to compare the fracture resistance of endodontically treated maxillary central incisors with incomplete crown ferrules after chewing simulation. Material and methods . Forty caries-free maxillary central incisors were divided into 4 groups ( n =10). Endodontic treatment was performed. Teeth were decoronated 2?mm above the cemento-enamel junction (CEJ). Group I (control) provided a 360° circumferential 2-mm ferrule. In group II, a 2-mm ferrule was present on the palatal aspect (status after occlusal overload), and in group III on the facial aspect (status after traumatic injury). In group IV, the ferrule was interrupted by bi-proximal cavitations (simulating caries treatment). The teeth received glass fiber reinforced posts and composite core restorations. All-ceramic crowns were adhesively cemented. Specimens were simultaneously exposed to thermal cycling and mechanical loading (1.2 million cycles; 6,000 cycles 5°/55°C) and finally statically loaded until failure in a universal testing machine (crosshead speed?=?1?mm/min). For statistical analysis, the Kruskal-Wallis test was applied followed by the Mann-Whitney U-test as post hoc testing. Results . The median fracture load values (min./max.) were: group I?=?502 (326/561), group II?=?658 (280/827), group III?=?899 (396/1176), and group IV?=?360 (279/646). Analysis revealed statistically significant differences between test groups, except between groups I and IV and groups II and IV. Conclusions . The fracture resistance of endodontically and post/core restored teeth is dependent on the degree of tooth conservation. An incomplete crown ferrule is associated with greater variation in load capacity and, despite high fracture values, inclines to fracture. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced endodontic posts are considered to have favorable mechanical properties for the reconstruction of endodontically treated teeth. The aim of the present investigation was to evaluate the survival of two tapered and one parallel-sided glass fiber-reinforced endodontic post systems in teeth with different stages of hard tissue loss and to identify risk factors for restoration failure. One-hundred and forty-nine glass fiber-reinforced endodontic posts in 122 patients were followed-up for 5–56 months [mean ± standard deviation (SD): 39 ± 11 months]. Glass fiber-reinforced endodontic posts were adhesively luted and the core was built with a composite resin. Cox proportional hazards models were used to evaluate the association of clinical variables and failure rate. Higher failure rates were found for restorations of anterior teeth compared with posterior teeth [Hazard-Ratios (HR): 3.1; 95% confidence interval (CI): 1.3–7.4], for restorations in teeth with no proximal contacts compared with at least one proximal contact (HR: 3.0; 95% CI: 1.0–9.0), and for teeth restored with single crowns compared with fixed bridges (HR: 4.3; 95% CI: 1.1–16.2). Tooth type, type of final restoration and the presence of adjacent teeth were found to be significant predictors of failure rates in endodontically treated teeth restored with glass fiber-reinforced endodontic posts. [ABSTRACT FROM AUTHOR]

Objectives Aim of the present study was to evaluate fracture strength of endodontically treated molars with different preparations/restorations after thermomechanical loading in vitro. Methods 264 extracted human third molars were used. Beside the control group, 256 teeth in 32 test groups ( n = 8) received root canal treatment (MTwo #40/.6) and root canal obturation with AH Plus and Guttapercha. After postendodontic sealing and build-up (Syntac, SDR), specimens were additionally prepared MO or MOD. Postendodontic restorations were: Direct restorations (Tetric EvoCeram Bulk Fill bonded with Syntac; as filling or direct partial crown (PC) after reducing the cusps 3 mm; amalgam as filling or direct pin-retained partial crown (PC)), vs. indirect adhesive restorations (I: Inlay vs. PC; IPS Empress I/PC; Celtra Duo I/PC; e.max CAD I/PC; Lava Ultimate I/PC; Enamic I/PC – all inserted with Syntac/Variolink) vs. cemented cast gold I/PC. After 300,000 thermocycles (5/55 °C) and 1.2 Mio. 100 N load cycles, specimens were loaded until fracture. Results Whereas IPS Empress showed no difference between I and PC ( p > 0.05), in all other groups PC were significantly more stable than fillings/inlays ( p < 0.05), this effect was more pronounced after MOD preparations. Cast gold PC exhibited the highest fracture strengths ( p < 0.05), inlays the lowest ( p < 0.05). IPS Empress was generally inferior to the other bonded materials under investigation ( p < 0.05) which as PC almost reached the level of control specimens. Amalgam fillings showed the worst outcome ( p < 0.05). Significances Less invasive preparation designs were not beneficial for the stability of postendodontic restorations. Except for IPS Empress, PC were generally more successful in restabilization of weakened cusps after endodontic treatment and preparation. Cast gold PC remain the ultimate stabilization tool for ETT in terms of fracture resistance. [ABSTRACT FROM AUTHOR]