Longevity of immediate rehabilitation with direct metal-wire reinforced composite fixed partial dentures.

OBJECTIVES: This study aimed to analyze the longevity of direct metal-wire reinforced composite fixed partial dentures (MRC-FPD) and factors influencing their survival and success. METHODS: Within one private practice 513 MRC-FPD were directly applied. The preparation of a proximal cavity in abutment teeth was not limited. MRC-FPD were reinforced by one to three metal-wires. At the last follow-up MRC-FPD were considered successful, if they were still in function without any need of therapy. MRC-FPD were considered as survived, if they were repaired or replaced. Multi-level Cox proportional hazard models were used to evaluate the association between clinical factors and time. RESULTS: Mean follow-up period (range) was 59(2-249) months. Seventy-three bridges did not survive (cumulative survival rate(CSR):86%) and further 129 bridges had received a restorative follow-up treatment (CSR:61%). AFR was 2.2% for survival and 8.6% for success. In multivariate analysis MRC-FPD with> 1 wire showed a up to 2.3x higher failure rate than MRC-FPD with one wire(p ≤ 0.023). Dentist's experience in designing MRC-FDP (p ≤ 0.017), patient's caries risk (p ≤ 0.040) and bruxism (p = 0.033) significantly influenced the failure rate: the more experience, the lower caries risk and bruxism, the lower the failure rate. SIGNIFICANCE: For directly prepared metal-wire reinforced composite bridges high survival and moderate success rates were observed. MRC-FPD might, thus, be an immediate, short- and medium-term solution for replacing missing teeth. However, several factors on the levels of practice (dentist's experience in designing MRC-FDP), patient (bruxism, caries risk) and restoration (number of wires) were identified as significant predictors for the failure rate. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00021576).

Application of morphometrical methods in studies of the mandibular condyle.

Two mandibular condyles of a growing monkey (Macaca fascicularis) were used for developing and testing a morphometrical model system suitable for generating quantitative data about the structure of and the growth activities in the articulating surface layers. The animal received 3H-proline (1 mCi/kg body weight) 24 h and 3H-thymidine (0.5 mCi/kg body weight) 3 h prior to killing. Using standardized conditions, 1-2 microns thick histological sections were processed for autoradiography. The morphometrical analysis was carried out using light microscopy at two levels of magnification. Sampling of tissue fields was performed at twenty-four (level I) and twelve (level II) different sites, respectively. These sites were distributed systematically in the anteroposterior and lateromedial dimension of the cartilaginous condylar covering. Using a multivariate analysis of variance, a parameter comparison revealed significant differences between single sampling sites in the anteroposterior as well as in the lateromedial direction, suggesting that the articulating condylar surface is inhomogeneous with respect to both structures and growth activities. The sampling mode eventually arrived at in this study was shown to be sufficient for the recording of gradients within the condylar surface layers. The model system presented permits simultaneous quantitative characterization of structure and growth activities such as mitotic cell division and extracellular matrix production of the condylar cartilage including the zone of its replacement by bone.