Estimating long-term survival of densely sintered alumina crowns: a cohort study over 10 years.

STATEMENT OF PROBLEM: Alumina-core crowns have become a standard treatment option in contemporary dental practice. The short-term survival of alumina crowns has been well documented. However, there is still a paucity of long-term survival data. PURPOSE: The purpose of this prospective cohort study was to estimate long-term survival of alumina crowns in anterior and posterior areas over an observation period of up to 10 years. MATERIAL AND METHODS: Between 1997 and 2005, 155 alumina crowns were placed in 50 subjects. Clinical and technical parameters were assessed at baseline. In 2005 and 2008, the crowns were clinically assessed using modified U.S. Public Health Service (USPHS) guidelines. Treatment failure was defined as crown or tooth loss and separated into technical or biological failures. Survival probabilities were estimated using the Kaplan-Meier method. RESULTS: In 2008, 29 subjects with 112 alumina crowns, including 86 (77%) posterior and 26 (23%) anterior crowns, were available for clinical assessment. The average observation period for these subjects was 7.8 years, with a range from 3 to 10.7 years. In total, 3 technical and 8 biological failures were observed. The estimated survival probability considering technical failures only was 95% (95% Confidence Interval (CI), 89% to 100%). The estimated overall survival probability after 10 years was 84% (95% CI, 74% to 95%). There was no significant difference in treatment failures in posterior as compared to anterior crowns (all failures: P=.713; technical failures: P=.352). CONCLUSIONS: The results suggest that the expected 10-year survival rate of alumina crowns due to technical failures is 95% (95% CI, 89% to 100%).

[Low-cost simple anchorage systems in the removable hybrid prosthesis. Locator Root Attachment and Würzburg post]. / Kostengünstige, einfache Retentionsmöglichkeiten in der abnehmbaren Hybridprothetik. Locator Root Attachment und Würzburger Stift.

For a simple and provisional retention of a removable prosthesis, less expensive direct retainers are an option compared to indirect cast gold copings with attachment. The Dalbo-Rotex-retainer and the Ticap-system are clinically established. The Locator Root attachment and the Würzburger Stift were recently introduced. The Locator Root attachment uses a massive profiled cylindrical post as a radicular anchorage. The Würzburger Stift has a small endodontic part which is retained by four spreadable lamellae in a convergent cavity. They further differ in the design of the male and female part. Depending on the clinical situation these characteristics can offer benefits and disadvantages. Both systems are documented and their indication, advantages and restrictions are discussed with clinical relevance.

Clinical evaluation of Procera AllCeram crowns in the anterior and posterior regions.

The aim of this prospective clinical study was to investigate the long-term survival of Procera AllCeram all-ceramic crowns in the anterior and posterior regions. Between 1997 and 2005, 155 Procera crowns with aluminum oxide cores were placed in 50 patients. Patients were recalled in 2005 for a clinical assessment. Thirty-nine patients with 135 crowns attended the recall examination. Of the 135 total crowns, 103 were located in the posterior region and 32 were located in the anterior region. The cumulative survival rate was 100% in the anterior region and 98.8% in the posterior region (1 crown fracture) after 5 and 7 years. Clinical success was achieved irrespective of the tooth position, cement used (resin composite or glass-ionomer cement), or the core design with reduced or conventional margins. Procera AllCeram seems to be a predictable technique for esthetic all-ceramic single crown restorations in the anterior and posterior regions.

[Long-term clinical results with Procera AllCeram full-ceramic crowns]. / Klinische Langzeiterfahrungen mit Procera-AllCeram-Vollkeramikkronen.

The aim of this prospective clinical study was to investigate the long-term survival rate of Procera AllCeram full-ceramic crowns, which were fabricated with aluminiumoxide cores. In 50 patients, 155 Procera crowns with a conventional or reduced core (porcelain collar) were placed on natural abutment teeth. 78% of this group (39 patients with 135 crowns) were examined between May and August 2005 according to the modified USPHS-Criteria. These crowns had been in place for a period of one to 92 months (mean 55 months). Almost half of the crowns were located in the molar region, while 28% were premolars and 24% anterior crowns. Due to one crown fracture the cumulative survival rate was 99% after five and seven years. The clinical success was achieved irrespective of the tooth position, tooth vitality, the preparation margin and the cementum medium used (composite resin or glasionomer cement). In addition, survival was neither influenced by the core design with reduced or conventional margin nor by the core thickness, which measured regularly 0.6 mm in the majority of the specimens. Based on the present findings, it can be concluded that Procera AllCeram is a predictable technique for metal-free, esthetic full-ceramic crowns in the anterior and posterior region.