Dental age estimation and different predictive ability of various tooth types in the Czech population: data mining methods.

Dental development is frequently used to estimate age in many anthropological specializations. The aim of this study was to extract an accurate predictive age system for the Czech population and to discover any different predictive ability of various tooth types and their ontogenetic stability during infancy and adolescence. A cross-sectional panoramic X-ray study was based on developmental stages assessment of mandibular teeth (Moorrees et al. 1963) using 1393 individuals aged from 3 to 17 years. Data mining methods were used for dental age estimation. These are based on nonlinear relationships between the predicted age and data sets. Compared with other tested predictive models, the GAME method predicted age with the highest accuracy. Age-interval estimations between the 10th and 90th percentiles ranged from -1.06 to +1.01 years in girls and from -1.13 to +1.20 in boys. Accuracy was expressed by RMS error, which is the average deviation between estimated and chronological age. The predictive value of individual teeth changed during the investigated period from 3 to 17 years. When we evaluated the whole period, the second molars exhibited the best predictive ability. When evaluating partial age periods, we found that the accuracy of biological age prediction declines with increasing age (from 0.52 to 1.20 years in girls and from 0.62 to 1.22 years in boys) and that the predictive importance of tooth types changes, depending on variability and the number of developmental stages in the age interval. GAME is a promising tool for age-interval estimation studies as they can provide reliable predictive models.

Bioactive glass-ceramics in facial skeleton contouring.

The removal of certain facial-bone defects is a prerequisite to restoration of function, stability, and appearance. Synthetic bone substitutes are beneficial in cases where other operative techniques would be an unacceptable burden for a patient. Satisfactory results can be achieved in one surgical intervention with low costs and low demand on technical equipment. Osteoconductive, biocompatible, non-resorbable glass-ceramic implants based on oxyfluoroapatite and wollastonite permit osteointegration--a direct physical and chemical bond between live bone tissue and the implant without formation of a fibrous capsule. They display better stress durability in simulated body fluid than hydroxyapatite implants do. This material was used for facial skeletal framework, contour restoration in 44 cases under conditions where other solutions were doubtful. Patients were observed for 24.8 months. Immediate healing occurred without any adverse reaction. The main problem was extrusion, observed in 20.45% cases over a 2-3 month period after the implantation. All cases, with one exception, were solved with a satisfactory final result by reoperation, implant size reduction, and increased soft tissue cover. This approach was found to be a suitable technique, especially for patients exhausted by prior incompetent treatment but still dissatisfied with their appearance. Successful reconstruction with a bone substitute may remarkably increase quality of life for affected persons and, at the same time, reduce surgery-related time and costs.