RESUMO
The concept of denture frame, both the vertical and horizontal relationship of the dentitions are ultimately related to a skeletal configuration, leads to postulate that the vertical overbite will be determined by the jaw rotations and anteroposterior jaw relationship. Also, ODI is analyses to be composed of the determinant factors of overbite such as FMA, PPA and FABA. From the geometric analyses of an interrelationship between the ODI and the overbite determinants, the following formula can be induced : ODI norm =85degrees- 0.5PMA-(1.08-0.01 FMA)(FABA-81degrees). This formula indicates that the norm of ODI is not constant value but variable one accordint to the individual skeletal frames. Through the application of the formula to the various clinical cases, it is proved that the new concept, relativity of the ODI norm, is very diagnostically useful.
Assuntos
Dentição , Dentaduras , Arcada Osseodentária , SobremordidaRESUMO
In almost all biologic systems, mechanically induced electric charge separation is a fundamental phenomenon. Since the hypothesis was established that the generation of electric potentials in bone by mechanical stress including muscular force might control the activity in bone by mechanical stress including muscular force might control the activity of osseous cells and their biopolymeric byproduct, the concept of electrically mediate growth mechanism, which involves biological growth and bone remodeling by any means, in living systems has been applied clinically and experimentally to orthopedic fracture repair, the regulation of orthodontic tooth movement, epiphyseal cartilage regeneration, etc. On the other hand, recent numerous research data available show apparently that the mandibular condyle has the characteristics of growth center as well as growth site. In addition, there exists a considerable difference of opinion as to the role of external pterygoid muscle in condylar growth. In view of these evidences, this. experiment was performed to investigate the effect of the galavic current on the growth of the mandible and condyle for elucidating the nature of condylar growth. The bimetallic device was composed of silver and platinum electrode connected with resistor (3.9 Mohm), which was expected to produce galvanic current of 23.6 nA according to the galvanic principle. The 25 Sprague-Dawley rats were divided into two group, 2 week group comprising 8 animals exposed to galanic current for 2 weeks and 3 control animals not exposed for 2 weeks, 4 week group comprising 10 animals in experimental group and 4 animals in control group applied for 4 weeks respectively. The experimental rats were subjected to application of the galvanic current invasively to codylar head surface and the control groups with sham electrode. On the basis of anatomic and histologic data from the mandibular condyle of experimental and control group, the following results were obtained. 1. After 2 weeks, there was no increase of mandibular size in experimental group over that of the control group. 2. After 4 weeks, the size of the condylar head was larger in experimental group than that of the control. 3. In 2 week group, the thickness of the mitotic compartment and hypertrophic chondroblastic layer was increased in experimental group. 4. In 4 week group, the number and the size of the hypertrophic chondroblasts were increased significantly on experimental group over that of the control group. 5. The application of the galanic current caused an increase in chondrocytic hypertrophy and intercellular matrix in both groups.