Survival time of post and cores after recementation: A 16-year retrospective study with special focus on loss of retention

Post and Core Treatment to Refit Telescopic Crown-Retained Dentures after Abutment Tooth Fracture: An Evaluation of Therapy by Retrospective Survival Analysis

Telescopic crown-retained dentures (TCDs) are one of the most common types of prosthetic restorations for partially edentulous patients; however, post and core (PC) treatment shows the worst survival probability if the tooth is used as an abutment for the TCD. Due to extra axial forces, abutment tooth fracture is a common cause of failure for TCDs; thus, PC treatment is often needed to refit the existing telescopic crown (TC). However, there are no clinical survival data on whether the PC treatment was used to refit the TC after abutment tooth fracture (PC2) or the PC was already fitted at the time of TCD treatment (PC1). A total of 246 patients with 399 PC treatments were retrospectively evaluated for follow-ups up to 17.33 years. The files were analysed for PC1 and PC2. Furthermore, the influence of the jaw, type of tooth, luting material, PC material, bone attachment, therapist and cause of failure was recorded. For statistical analysis, Kaplan-Meier and Cox regression analyses were conducted. PC2 showed highly significant lower survival probabilities than PC1 (p < 0.001). Moreover, the bone attachment and the age of the patient at the time of fitting the PC crown had an influence on the survival (p < 0.001). Therefore, PC2 should be carefully discussed with the patient and PC1 should be favoured in endodontically treated abutment teeth for TCDs.

How long must a post be? A retrospective survival analysis on a large cohort with long follow-ups

OBJECTIVES

Post and core (PC) is frequently used, but clinical evidence concerning how long a post must be is scarce. Recommendations in dental literature range from half of the root which should be incorporated, to post space preparations conducted as deep as possible increasing the risk for root perforation thus tooth loss. Therefore, the aim of this retrospective survival analysis is to evaluate the post length as well as the post-clinical crown ratio on a large patient cohort with long follow-ups.

MATERIALS AND METHODS

Overall 1026 PC in 731 patients could be included in this study (2004-2023). The files were analysed due to the parameters post length and post-clinical crown ratio on X-Ray. Furthermore, the influence of the type of covering prosthetic restoration, location, type of tooth, luting material, PC material, bone attachment and therapist was evaluated. The statistical analysis was assessed using Kaplan-Meier (univariate influences) and Cox regression (multifactorial influences).

RESULTS

Survival until extraction as well as decementation was significantly influenced by bone attachment and covering prosthetic restoration. Posts reaching the middle third of the root showed highly significant (p < 0.001) better survival probabilities than those reaching the coronal or apical third. Regarding the post-clinical crown ratio, no significant difference was found for post = crown/post > crown, whereas post

CONCLUSIONS

The post space preparation should not be extended over the middle third of the root, but has to be deep enough to ensure that the post is at least as long as the clinical crown.

CLINICAL SIGNIFICANCE

Against the background of the large sample size and the long follow-ups, the results of this retrospective survival analysis are suitable to give general recommendations regarding how long a post has to be in order to ensure the best survival probability for PC treatment.

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Key Words

• Cox regression
• Kaplan-Meier analysis
• Post length
• Post-clinical crown ratio
• Survival time

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MESH Headings

• Humans
• Retrospective Studies
• Follow-Up Studies
• Post and Core Technique
• Dental Restoration Failure
• Crowns
• Survival Analysis

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Affiliation(s)

Sarah Marie Reich Justus Liebig University, Dental Clinic - Department of Prosthodontics, Schlangenzahl 14, 35392 Giessen, Germany
Kay-Arne Walther Justus Liebig University, Dental Clinic - Department of Prosthodontics, Schlangenzahl 14, 35392 Giessen, Germany
Bernd Wöstmann Justus Liebig University, Dental Clinic - Department of Prosthodontics, Schlangenzahl 14, 35392 Giessen, Germany
Peter Rehmann Justus Liebig University, Dental Clinic - Department of Prosthodontics, Schlangenzahl 14, 35392 Giessen, Germany
Jonas Adrian Helmut Vogler Justus Liebig University, Dental Clinic - Department of Prosthodontics, Schlangenzahl 14, 35392 Giessen, Germany.

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Survival of teeth treated with post and core - A retrospective study of more than 1000 cases with observation periods up to 18 years

OBJECTIVES

Even if survival of post and core (PC) itself was frequently investigated in recent literature, clinical data concerning the risk for extraction of teeth restored with PC is still scarce. Since most authors found the loss of retention of refitable post and cores as the most common cause of failure, it is impossible to draw a conclusion on tooth survival on the results of those studies. Therefore, the aim of the present study was to improve the clinical evidence on the survival of teeth treated with post and cores on a large number of cases over a long observation period.

MATERIALS AND METHODS

735 patients were treated with 1053 post and cores in the observation period (2004-2022) and could be included in the study. The patient files were analysed due to the parameters: Type of covering prosthetic restoration, location, type of tooth, luting material, post and core material, bone attachment and therapist. The survival probability was assessed using Kaplan-Meyer analysis. Cox regression was used to assess possible multifactorial influences.

RESULTS

The overall average survival time until necessary extraction of a tooth restored with a post and core was 11.74 years. A root fracture in primary crown retained removeable partial dentures (RPDs) during the first five years was the most common reason for extraction in this study. A significant influence on the survival time of teeth restored with post and cores was found for the type of covering restoration, bone attachment, age of the patient and post and core material.

CONCLUSIONS

Post and core restored teeth should be avoided as abutments for primary crown retained RPDs.

CLINICAL SIGNIFICANCE

If it is inevitable to utilise post and core restored teeth for primary crown retained RPDs, post and core materials with matching mechanical properties to that of dentine should be preferred.