Browsing by Author "Mitchell, David F."

Now showing 1 - 8 of 8
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    An Analysis of Possible Factors Affecting the Soft Tissue Response in Postadolescent Orthodontic Patients
    (1975) Cowan, Richard Edward; Garner, LaForrest D.; Potter, Rosario H.; Mitchell, David F.; Tomich, Charles E.; Hutton, Charles E.; Weinberg, R. Bernd
    This study was carried out to evaluate the factors which may vary the soft tissue response in non-growing subjects. Pretreatment and post-treatment lateral cephalometric radiographs of twenty-nine postadolescent orthodontic patients were measured with a sonic digitizer using facial plane as the reference. Stepwise multiple regression analysis was performed to select those factors from the original set of 6 according to the statistical significance of their contribution in the prediction of the soft tissue response. It was found that 30.84% of the horizontal upper lip response is due statistically to the maxillary incisor change and the pretreatment upper lip thickness at the vermillion border. This study also revealed that 67.76% of the horizontal lower lip response is due statistically to the mandibular incisor change, the pretreatment upper lip thickness at A-Point, and the mandibular postural change. Additionally, 16.50% of the vertical upper lip response is due statistically to the mandibular incisor change. Further, 33.39% of the vertical lower lip response is due statistically to the mandibular postural change and the pretreatment upper lip thickness at A-Point. Finally, the majority of the total variation in lip response is still not accounted for and therefore further research is needed.
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    An evaluation of tetracycline stain removal by bleaching vital rabbit incisors
    (1974) Fleege, Patrick A.; Roche, James R., 1924-; Klein, Arthur Irving, 1922-2004; Katz, Simon, 1920-1987; Koerber, Leonard G.; Mitchell, David F.
    This study evaluated the effectiveness of bleaching tetracycline-stained teeth by measuring the loss of fluorescent intensity from teeth that were bleached. Nineteen male New Zealand white rabbits, with 58 incisors stained with oxytetracycline and 16 incisors as unstained controls, were used. Three rabbits were sacrificed to determine whether the tetracycline stain was comparable between incisors in the same jaw. Of the remaining 16 animals, 6 were bleached once and 10 were bleached twice. One maxillary and one mandibular incisor were bleached in each jaw with 30 percent hydrogen peroxide and heat for ten minutes per tooth; the other incisors were protected with a rubber dam. The animals were sacrificed 24 hours after the last bleach. The fluorescent intensity of 374 select ground sections 100 ± 5 microns thick from the incisal, middle and gingival thirds of the teeth were measured with an ultraviolet light microscope coupled to a television electronic measurement system. These measurements were statistically analyzed by t-test, and observations correlated. The dentin of tetracycline-stained maxillary incisors which were bleached twice and the dentin in the incisal one-third of the mandibular incisors which were bleached twice had a significantly (P ≤ 0.001, P ≤ 0.005) lower tetracycline fluorescent intensity than the dentin of unbleached tetracycline-stained teeth. The greatest loss of fluorescent intensity of tetracycline occurred in dentin closest to the dentino-enamel junction and varied from about 150 to 350 microns from the outer enamel surface. Clinical Kodachromes indicate that the loss of tetracycline pigment is associated with the loss of tetracycline fluorescence; The ground sections showed that the tetracycline fluorescence was never totally removed by two bleaches.
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    A Histologic Investigation of Orthodontic Tooth Movement in Hypothyroid Macaque Speciosa Monkeys
    (1974) Davis, Steven L.; Garner, LaForrest D.; Barton, Paul; Tomich, Charles E.; Mitchell, David F.; Chalian, Varoujan
    This study was undertaken to histologically evaluate orthodontic tooth movement in hypothyroid and in normal Macaque speciosa monkeys. The experimental animals were rendered hypothyroid by radiosurgically altering the thyroid gland. A clinically acceptable orthodontic force was delivered to the anterior teeth of the monkeys. After the desired movement, a histologic investigation was made to correlate tissue responses with pressure, tension and root resorption. There was no significant difference among the three experimental animals. Likewise, there was no significant difference between the control animal and the three experimental animals. Osteoblastic and osteoclastic activity occurred to a comparable degree in both the experimental and control animals and was within normal limits for the amount of orthodontic tooth movement achieved. Root resorption was evident in both orthodontically treated and non-treated teeth in both the experimental and control animals. The root resorption observed was not significantly different, quantitatively or strategically, between the experimental and the control animals. Repair of root resorption was evident in both the experimental and control animals.
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    A histological study of gingival implants into the dental pulp and connective tissue of dogs
    (1967) Henry, Millicent, 1936-; Mitchell, David F.; Shafer, William G.; Bixler, David; Garner, La Forrest Dean, 1933-; McDonald, Ralph E., 1920-
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    An Investigation of Depressive Root Movement in the Macaque Speciosa Monkey
    (1973) Clevenger, Victor Reid; Bixler, David; Mitchell, David F.; Tomich, Charles E.
    The purpose of this study was to investigate the possibility of accomplishing simultaneous intrusion and distal root movement of monkey premolar teeth utilizing the molar teeth as anchorage. Four Macaque speciosa monkeys were used as the experimental specimens. Root springs of the type used in the segmented arch technique were used to apply unequal moments to the premolar and molar teeth. The root movement was accomplished by a couple generated by the unequal moments. The results were analyzed cephalometrically and histologically. It was found that it is possible to accomplish distal root movement and intrusion of the monkey premolars when the anchorage is restrained from eruption. When the anchorage is not restrained intrusion is minimal. Root resorption was found to be associated with the magnitude of the difference in the moments applied and the amount of tooth movement.
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    The significance of skeletal and dental measurements obtained from a panorex radiograph
    (1973) Sigala, Joseph L.; Garner, La Forrest Dean, 1933-; Mitchell, David F.; Starkey, Paul E.
    The purpose of this study was to determine whether angular and linear measurements from tracings of a Panorex radiograph provide a valid comparison to bony relationships identified on the lateral cephalometric headplate of the same individual. A pilot study was performed on a dried skull to identify selected skeletal landmarks on Panorex radiographs. Using these landmarks, fifteen measurements of bony relationships of the head were completed on each radiograph. Values obtained on a lateral headplate were compared with measurements on the same patient's Panorex radiograph for a group of forty-eight children. The data were recorded on standard IBM punch cards and submitted for statistical analysis to the Research Computation Center of Indiana University-Purdue University at Indianapolis. The data support the conclusion that angular and linear measurements from a tracing of a Panorex radiograph cannot be compared directly or in a proportional manner to similar measurements from a tracing of a lateral headplate of the same individual. Although there was significant correlation of comparative measurements for the sample group as a whole, there was wide variation from individual to individual.
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    Vitamin - Fluoride supplements: effect on dental caries and fluorosis in sub-optimum fluoride areas
    (1975) Hennon, David Kent, 1933-; Roche, James R., 1924-; El-Kafrawy, Abdel Hady, 1935-; Bixler, David; Katz, Simon, 1920-1987; Standish, S. Miles, 1923-2003; Mitchell, David F.
    This study was designed to determine if additional fluoride, ingested as a sodium fluoride - vitamin supplement would provide added protection against dental caries without causing any significant fluorosis. A total of 456 children, one to 14 months of age, residing in cities having 0.6 - 0. 8 ppm F in the water supply were randomly assigned according to age, sex and community to the following groups : Group A, 0. 5 mg F to age 3 then 1. 0 mg thereafter; Group B (control), vitamins throughout the study; and Group C, 0.5 mg F throughout the study. Dental examinations were started at approximately 2 1/2 to 3 years of age and were repeated every six months. A fluorosis examination ended the study after about seven years. When compared according to length of time on product, Group A had a significant reduction in deft and defs of 42.2 and 47.1 percent at 60 months. Group C had a 32.1 and 37.4 percent reduction. When compared by age, Group A had a 37.5 and 44.8 percent reduction in deft and defs at 66 months. Group C had a 34.3 and 40.1 percent reduction for the same period. No significant reductions were observed in permanent teeth. Based on the fluorosis index (Group A - 0.250; Group B - 0.033; and Group C - 0.188) none of the groups had any unacceptable amounts of fluorosis. The results indicate that up to 1.0 mg per day of additional fluoride does not cause objectionable fluorosis and may be ingested safely by children residing in areas containing 0. 6 - 0. 8 ppm F in the water supply. A 0.5 mg F supplement was almost as effective as a 1.0 mg level in providing added protection against dental caries in primary teeth.