Browsing by Author "Standish, S. Miles"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    A Study of the Correlation of Incisive Biting Forces with Age, Sex and Anterior Occlusion
    (1971) Kotwal, Navroze Shavak; Standish, S. Miles; Chalian, Varoujan A.; Shanks, James C.
    This study was designed to prove or disprove the fact that incisive biting force can be correlated with the variables chosen which were age, sex and anterior occlusion (overjet, overbite and cuspid relation). The amount of linear contact made by the incisal edges of the upper and lower incisors was also included as one of the variables. One hundred and fifty individuals, 80 males and 70 females, between the ages of 10 and 25 were selected for this study. This was a cross sectional study in which four readings of the maximum biting ability were recorded for every individual just once during the study and an average of the four recordings was taken. An intra-oral force transducer using strain gages was employed to record incisive biting forces. The results indicated that age, sex and amount of linear contact were correlated with biting force when considered singly. When the variables were considered jointly through a stepwise regression analysis overbite also entered as a significant predictor of biting force in addition to the three mentioned variables. Multiple correlation coefficient R was 0.54 for the four entered variables (age squared, sex, overbite and linear contact squared) with biting force. The R squared value was 0.29 so that 29 percent of the variation in incisive biting force of this sample was due to these four variables. The correlated R-squared value indicates a large error of prediction and a low degree of precision in estimating biting force from these four variables. Therefore, a regression equation is not demonstrated.
  • Thumbnail Image
    Item
    Histologic Tissue Rearrangement Following a Circumferential Supracrestal Fiberotomy on Orthodontically Rotated Teeth in Dogs
    (1987) Powell, Mark L. M.; Garner, LaForrest D.; Sondhi, Anoop; Kafrawy, Abdel; Standish, S. Miles; Shanks, James
    The purpose of this study was to determine whether a circumferential supracrestal fiberotomy has a biologic basis in the management of rotational relapse. The maxillary second incisors of seven beagle dogs, approximately two years of age, were rotated orthodontically from nine to 52 degrees. The incisors were retained. A circumferential supracrestal fiberotomy was performed twice unilaterally on the maxillary left second incisor of six dogs by incising through the gingival crevice parallel to the long axis of the tooth. The seventh dog was sacrificed and used for comparison of the tissue rearrangement after rotation but before fiberotomy and/or retention. The remaining dogs were paired for retention periods of one, three, and six months. Ten days before sacrifice all seven dogs were injected intraperitoneally with procion brilliant red H-8BS to determine appositional activity. At the end of the respective retention periods, the dogs were sacrificed and the specimens were fixed, decalcified, and serially sectioned horizontally, perpendicular to the long axis of the teeth. Sections were stained with H and E for histologic examination using light microscopy. Some sections were left unstained for evaluation of procion labelling using fluorescent light microscopy. The rearrangement of the subcrestal periodontal ligament fibers was determined by whether they produced a force capable of causing an increased alveolar and/or cemental apposition and not by their angulation to the root surface. The results failed to support a biologic basis for performing circumferential supracrestal fiberotomies on orthodontically rotated teeth. The supracrestal fiberotomy combined with retention had no additional effect on increasing the rearrangement of the supracrestal tissues compared to retention alone. Six months of retention, with and without a supracrestal circumferential fiberotomy, was sufficient for the supracrestal tissues to rearrange. Some of the subcrestal periodontal fibers in the tension and pressure areas at six months in retention may play a role in relapse. Undermining root resorption was evident in some pressure areas. Neither the angulation of the subcrestal and supracrestal periodontal fibers to the tooth surface nor the angulation of the epithelium was an accurate measure of the amount of tissue rearrangement. The circumferential supracrestal fiberotomy caused a cemental hyperplasia adjacent to areas nicked by the scalpel blade.
  • Thumbnail Image
    Item
    The Response of Condylar Cartilage Stimulated by a Small Defect in the Rat Mandible
    (1983) Deguchi, Toshio; Kafrawy, Abdel; Tomich, Charles E.; Barton, Paul; Standish, S. Miles; Garner, LaForrest D.
    This study investigated the response of the condylar cartilage subjected to a small bone defect as a local stimulus in the rat mandible, in order to clarify one of the mechanisms of condylar cartilage growth. Fourteen male Wistar albino rats weighing 200 to 260 gm were divided into two groups, with two animals in a pilot study and 12 animals in the experimental group. Five male Wistar albino rats weighing 400 to 540 gm were used in a third group, which provided a basis for comparisons with the experimental group. To evaluate bone growth changes of the rat mandible, a superimpositioning method of tracings of the left and the right mandibles was done using the molars, incisors, anterior and inferior borders of the mandible. A sliding micrometer was used to measure each distance between the posterior edge of mental foramen (MF) and the posterior border of condylar process (CP) or angular process (AP). In the pilot study, one of two animals showed a decreased angular process and an increased condylar process, and the results suggested that the decreased activity of the masseter, resulting from dissecting a part of the masseter, may play an important role in changing the size or the shape of the rat mandible. In the experimental study, the masseter was not dissected and the results indicated that a hole drilled at the condylar notch did not stimulate condylar growth enough to be measurable. The third group showed that there were minor asymmetries between the left and the right mandible in normal rats, ranging from 0.49 to .0297 mm. Therefore, a larger sample size would be needed to arrive at definite conclusions.