Relationship between number of proximal contacts and survival of root canal treated teeth

A systematic review of single crowns on endodontically treated teeth

OBJECTIVES

To test the hypothesis that the placement of a crown is associated with improved (long term) survival of root canal treated teeth, using a systematic review process of clinical studies.

DATA SOURCES

Papers referring to single crowns on endodontically treated teeth were located by a MEDLINE search and hand searching. One thousand six hundred and nine references were found, and they were subjected to a systematic review procedure.

STUDY SELECTION

A three-step inclusion-exclusion procedure was applied to identify papers that represented; good scientific practice (GSP), reported results of all patients, restorations on root canal treated teeth (RCT) for more than 2 years and had sufficient data to generate life table analyses. The outcomes were 'survival of RCT restored with crowns' and 'survival of RCT with direct restorations'. Ten studies survived. These data showed an overall mean GSP of 0.605 with a 10-year survival of 81% for crowned RCT and a 10-year survival of 63% for RCT with direct restorations (resin composites, amalgam, cements).

CONCLUSION

RCTs restored with crowns show an acceptable long-term survival of 10 years, while direct restorations have a satisfactory survival only for a short period.

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.

Reinforcement effect of adhesively luted fiber reinforced composite versus titanium posts

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.

The effect of alveolar bone loss on the load capability of restored endodontically treated teeth: A comparative in vitro study

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 2 mm 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 (v=1 mm/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.

Treatment concepts for restoration of endodontically treated teeth: A nationwide survey of dentists in Germany

STATEMENT OF PROBLEM

Opinions concerning proper restoration of endodontically treated teeth (ETT) vary. A variety of techniques and materials for post-and-core restorations are available. The rationale for post placement performed by German dentists was unknown.

PURPOSE

The purpose of this study was to determine current opinions, applied techniques, and materials for the restoration of ETT in Germany.

MATERIAL AND METHODS

A nationwide questionnaire-based survey containing 18 multiple choice questions regarding treatment philosophies, favored post type, and materials for core foundations was mailed to 36,500 German general dentists. A total of 6029 questionnaires (16.5%) were returned. Data were evaluated in terms of the dentists' occupational experience and the frequency of post placement. Descriptive statistics were used to analyze the data.

RESULTS

Irrespective of their occupational experience, 52% of the surveyed dentists consider post placement for almost every postendodontic restoration of ETT. The majority of dentists (54%) believe that a post reinforces ETT. Cast posts and cores are used by 55% of all dentists, whereas 34% use prefabricated posts exclusively. Screw posts are the most popular prefabricated post type (47%). Composite resin (51%) is preferred for core foundation, followed by glass ionomer cements (GICs) (26%). Amalgam is seldom used (0.5%). Posts are placed primarily with zinc phosphate cement (51%), followed by GIC (38%).

CONCLUSION

The treatment philosophy of German dentists is not in complete agreement with recommendations found in the literature. The belief that a post would reinforce an ETT might explain the high frequency of post placements. Due to the partially inconsistent responses, it is difficult to derive a generalized treatment concept.

A new approach to define defect extensions of endodontically treated teeth: inter- and intra-examiner reliability

For endodontically treated teeth, there are no standardized measures available to define the extent of loss in tooth substance prior to final restoration. In this study, defect size was classified and the applicability of the classification was tested related to the inter- and intra-examiner reliability. For classification, three parameters were investigated: (i) remaining tooth substance in the vertical dimension (level A-D, aspect I), (ii) remaining tooth substance as regarded horizontally (mm; bucco-lingual and mesio-distal, aspect II), and (iii) size of the orifice (mm; aspect III). Four non-calibrated or (pre-trained) examiners were asked to gauge and classify 20 casts of clinically broken down teeth. The measurements were repeated twice every alternative week giving three separate readings. Inter-examiner reliability was determined at weeks 1, 3 and 5. The intra-examiner reliability was compared between readings 1 and 2, 1 and 3, and 2 and 3. As statistical tests, intra-class correlation (ICC) and Cohen's kappa (weighted) were used at a significance level of P < 0.05. Inter- and intra-examiner reliability for ordinal data (aspect I) revealed, with one exception, 'moderate' to 'very good' evaluations. Inter- and intra-examiner reliability (ICC) of metric data of aspect II and III was primarily 'excellent'. It may be concluded that the newly developed classification could be applied as an appropriate and reproducible method to define defect extension in endodontically treated teeth.

Risk factors for failure of glass fiber-reinforced composite post restorations: a prospective observational clinical study

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.

Root Canal Filled Versus Non-Root Canal Filled Teeth: A Retrospective Comparison of Survival Times

OBJECTIVE

This matched cohort study used data from a large dental HMO in the Pacific Northwest to evaluate the degree to which pulpal involvement and subsequent endodontic therapy affects tooth survival. Root canal filled (RCF) teeth were used as an indicator of pulpal involvement. Our hypothesis was that RCF teeth would be extracted sooner than non-RCF teeth matched within subjects, controlling for tooth-level variables of interest.

METHODS

The HMO's treatment databases and a subsequent chart audit were used to identify 202 eligible subjects, each of whom had one tooth endodontically treated in 1987-88 and a similar contralateral tooth that was non-RCF at that time. Both teeth were followed from the endodontic access date through the extraction date, the endodontic access date (for initially non-RCF teeth), or 12/31/94, whichever was earliest. Time-to-event analyses were carried out, with Kaplan-Meier curves generated and multivariable marginal proportional hazards regression models fitted to describe the effect of RCF status on tooth survival. All statistical analyses accounted for the complex sampling strategy used in generating the dataset.

RESULTS

Teeth were followed for up to eight (median = 6.7) years. RCF teeth had substantially worse survival than their non-RCF counterparts (p < 0.001), with a greater effect of RCF status evident among molars than non-molars. Adjusted hazard ratios (95% confidence intervals) for loss of RCF versus non-RCF molars and non-molars were 7.4 (3.2-15.1) and 1.8 (0.7-4.6), respectively.

CONCLUSION

Though endodontic therapy can prolong tooth survival, pulpal involvement still may hasten tooth loss, underscoring the importance of caries prevention and prompt restorative care.