Browsing by Author "Kafrawy, Abdel"

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    A Study of Nasopharyngeal Airway Size and its Relationship to Maxillary Morphology and Position in Monozygotic Twins
    (1983) Schmidt, Randall A.; Garner, LaForrest; Arbuckle, Gordon R.; Barton, Paul; Kafrawy, Abdel; Shanks, James C.
    This investigation was undertaken to study possible relationships between the size of the nasopharyngeal airway space and the morphology of the growing face. With reduction of the nasopharyngeal airway space, mouth breathing often becomes necessary. If mouth breathing becomes the dominant form of respiration it is believed to cause morphologic alterations in the cranioskeleton, as in the so-called "adenoid facies" individual. This environmental alteration in facial growth pattern, in contrast to the facies derived from genetic predisposition, can be tested only by using a sampling of monozygotic (identical) twins. It is assumed that since both twins have identical growth determinants any variances in their facial morphology would be due to environmental factors. Thirty-five pairs of monozygotic twins were divided on the basis of having a significantly differing intrapair airway size or a similar intrapair airway size. Thus, the independent variable in this investigation was the airway size difference between identical twins in a pair. Seven parameters were chosen to identify any maxillary morphologic changes among twin pairs. From lateral cephalometric radiographs and study casts of the twin pairs, data were accumulated for statistical analysis. It was hypothesized that significant differences between the variances in the maxillary traits of the two groups would be related to the size differences of the airways used in dividing these groups. Lower facial heights and intermolar distances were significantly different between the two groups of twins. The findings of this investigation support the opinion that nasal obstruction is related to changes in the morphology of the maxilla. The relationship is such that with decreased nasopharyngeal airway size the lower facial height tends to increase and the maxillary intermolar widths decrease. No significant changes appear to occur concomitantly in the maxillary antero-posterior relationship to the cranial base, cant of the maxilla, maxillary incisor flaring, upper facial height, and posterior vertical height of the nasomaxillary complex.
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    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.
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    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.