Clinical application on composite resin recently draw great concerns in dentistry. Especially due to advantages such as esthetics, adhesiveness, simple clinical procedures, various shapes and kinds of composite resin are widely being applied to prosthodontics, conservative dentistry, and orthodontics. But, clinical problems attributable to the polymerization shrin-kage of composite resin have been proposed, and we have to regard clinical problems such as secondary caries, loss of restoration, fracture of the surrounding tooth structure, marginal discoloration, and tooth sensitivity, and many portions are remained to be over-come. Therefore, this study attempts to analyze stress distribution between resin and tooth structure which is generated during polymerization shrinkage of composite resin using three dimensional finite element method. Three dimensional finite element models with conventional box-shape cavity and ero-sion/abrasion type V-shape lesion cavity in upper central incisor were developed. These cavities were filled with four different types of placement techniques. (bulk filling, horizontal increment filling, oblique occlusal increment filling, oblique gingival increment filling) The stresses generated by polymerization shrinkage of composite resin were calculated. The results analyzed with three dimensional finite element method were as follows : 1. The increment filling technique showed the highest maximum normal stress in both conventional box-shape and V-shape cavities and showed a tendency to decrease after complete polymerization. 2. The bulk filling technique resulted in increased stresses during the curing process in both conventional box-shape and V-shape cavities and the highest maximum normal stress occurred after complete polymerization. 3. The bulk filling resulted in the lowest maximum normal stress in both box-shape and V-shape cavities 4. Regardless of placement method, in conventional box-shape cavity, the maximum normal stress increased in dentin floor, enamel, dentin sequence and in V-shape cavity, the maximum normal stress increased in enamel, dentin sequence.
Adhesiveness ; Dental Enamel ; Dentin ; Dentistry ; Esthetics ; Finite Element Analysis* ; Incisor ; Orthodontics ; Polymerization ; Polymers ; Prosthodontics ; Tooth

The fundamental alterations in the cardiovascular system that occur consequent to aging are of great pratical importnace to clinicians. Senescent cardic muscle has many features of prolonged tension development, impaired relaxation and diminished response to receptor-mediated inotropic interactions. We estimated left ventricular mass by 2-D echo area-length method using a high quality planimeter. Age-related increments in left ventricular mass demostrated, but left ventricular enddiastolic cavity volumes were unaffected by age. The increase in left ventricular mass observed with aging is typical of pressuer-overload hypertrophy and its stimulus may be increased afterload from senescent changes.
Aging* ; Cardiovascular System ; Hypertrophy ; Relaxation