Subject(s)
Mouth Protectors , Paraplegia/rehabilitation , Self-Help Devices , Equipment Design , Female , Humans , Mandible , MusicABSTRACT
The relation of the Frankfort-mandibular plane angle (FMA) to naturally occurring occlusion groups was studied in 112 subjects. Occlusion types were categorized into four groups depending on the magnitude of first-molar contact on the working side. Percentage (frequency) of occurrence of occlusion groups were: disclusion, 17.9 per cent; delayed disclusion, 19.6 per cent; progressive disclusion, 8.9 per cent; and group function, 53.6 per cent. The mean FMA for the study sample was 25.68 degrees with a range of 13 to 40 degrees. Mean FMA's for the occlusion groups showed a progressive increase from disclusion (19.6 degrees) to group function (28.9 degrees). A statistical test, extension of the median, indicated a highly significant relation between occlusion groups and the FMA. Considering these results, an FMA determination provides a structure-function basis to consider in selecting a scheme for occlusal reconstruction and should be incorporated in the treatment planning procedure as a major adjunctive diagnostic tool. However, further research, focused upon the many variables that determine a type of occlusion, must precede the formulation of a set of "rules" for selection of occlusion.
Subject(s)
Cephalometry , Face/anatomy & histology , Malocclusion/pathology , Mandible/anatomy & histology , Adolescent , Adult , Female , Humans , Malocclusion/classification , Malocclusion/epidemiologyABSTRACT
Cephalometric information, specifically, vertical facial types and the Frankfort-mandibular plane angle, pertinent to prosthodontics has been discussed. The Frankfort-mandibular plane angle (FMA) is formed by the intersection of the Frankfort horizontal plane and the mandibular plane. This angle can be traced and measured by means of a diagnostic overlay. An FMA of 25 +/- 5 degrees is within normal range. A high-angle patient has an FMA of 30 degrees or more, and a low-angle patient has an FMA of 20 degrees or less. A high FMA is characterized by open-bite skeletal patterns, and a low FMA by closed-bite skeletal patterns. The clinical manifestations pertinent to prosthodontics in high- and low-angle (FMA) patients are shown in Table I. However, not all clinical characteristics are present in a given patient. The classification in Table I is a beginning. The authors consider the prosthodontic study of cephalometrics an unexploited research tool. Hopefully, in the future, it will help to bridge the gap of the biological-technical interplay that is such an integral part of prosthodontics.
