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.

Survival of Double Crown-Retained Implant-Tooth-Supported Removable Partial Dentures: A ≥ 5-Year Clinical Follow-up Study.

PURPOSE: This retrospective clinical follow-up study assesses double-crown retained implanttooth- supported removable partial dentures (DCR-ITSRPDs) survival, evaluates abutment survival and identifies first aftercare measures. MATERIALS AND METHODS: The influence of various factors on the survival of the DCR-ITSRPDs and the abutments were observed in this retrospective clinical follow-up study using Kaplan-Meier estimate. In addition, the first occurred aftercare measure per prosthesis was evaluated. RESULTS: 47 DCR-ITSRPDs were investigated (mean observation: 4.3 ± 3.8 years; max. 14.3 years) out of which three (6.4%) had to be replaced. The 5- and 10- year survival probability for DCR-ITSRPDs was 100% and 75%. A total of 297 abutments (120 natural teeth and 177 dental implants) were observed, of which 22 (7.4%; 6 teeth and 16 implants) failed. The 5- and 10-year survival probability for teeth was 90.2% and for dental implants 90.4% and 76.3%. CONCLUSION: DCR-ITSRPDs are a successful and durable treatment option for patients with substantially reduced residual dentitions. Both, prostheses and abutments show good survival times after 5- and 10-years in function. The patient associated factors tested showed no influence on the survival of DCR-ITSRPs and abutments. Peri implant infection was the decisive factor for abutment loss, therefore, regular dental prophylaxis and examinations are of major importance.

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