Browsing by Subject "Incisor"

Now showing 1 - 5 of 5
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    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.
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    Effects of rapid maxillary expansion on the cranial and circummaxillary sutures
    (Elsevier, 2011-10) Ghoneima, Ahmed; Abdel-Fattah, Ezzat; Hartsfield, James; El-Bedwehi, Ashraf; Kamel, Ayman; Kula, Katherine; Department of Orthodontics and Oral Facial Genetics, IU School of Dentistry
    INTRODUCTION: The aim of this study was to determine whether the orthopedic forces of rapid maxillary expansion cause significant quantitative changes in the cranial and the circummaxillary sutures. METHODS: Twenty patients (mean age, 12.3 ± 1.9 years) who required rapid maxillary expansion as a part of their comprehensive orthodontic treatment had preexpansion and postexpansion computed tomography scans. Ten cranial and circummaxillary sutures were located and measured on one of the axial, coronal, or sagittal sections of each patient's preexpansion and postexpansion computed tomography scans. Quantitative variables between the 2 measurements were compared by using the Wilcoxon signed rank test. A P value less than 0.05 was considered statistically significant. RESULTS: Rapid maxillary expansion produced significant width increases in the intermaxillary, internasal, maxillonasal, frontomaxillary, and frontonasal sutures, whereas the frontozygomatic, zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures showed nonsignificant changes. The greatest increase in width was recorded for the intermaxillary suture (1.7 ± 0.9 mm), followed by the internasal suture (0.6 ± 0.3 mm), and the maxillonasal suture (0.4 ± 0.2 mm). The midpalatal suture showed the greatest increase in width at the central incisor level (1.6 ± 0.8 mm) followed by the increases in width at the canine level (1.5 ± 0.8 mm) and the first molar level (1.2 ± 0.6 mm). CONCLUSIONS: Forces elicited by rapid maxillary expansion affect primarily the anterior sutures (intermaxillary and maxillary frontal nasal interfaces) compared with the posterior (zygomatic interface) craniofacial structures.
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    Force Values and Rate of Movement in Closure of Space Between Maxillary Central Incisors
    (1962) Levihn, Henry L.
    A study was conducted to determine the rate of tooth movement, pain response and tooth mobility when closing the space between the maxillary central incisors. Twenty children age 8 to 18 were selected who had a minimum of two millimeters space between the maxillary centrals. The forces used were 10, 20, 50, 75, 125, and 200 grams. It was found that there was a fast initial movement followed by a latent period of varying lengths of time. In most instances the lag period is from seven to ten days, but in three cases it was as high as eighteen to twenty-five days. The five patients in the 50 gram group had the shortest latent period. The three patients with the extended latent periods happened to be the three oldest patients in the sample. That is, they were from 16 ½ to 18 years of age, while the average age for the entire sample was about 11 years. After the latent period, the rate of movement in the 10 and 20 gram groups was slower than the rate of movement with higher force. When the higher forces in the 125 and 200 gram range were used, the rate did not continue to increase but was comparable to the rates in the 50 and 75 gram groups. What was noticed in the higher range of force was an increase in the amount of pain and mobility. From these observations it was felt that for tipping of the maxillary centrals the optimal range of force to be used would be 50 to 100 grams. At these forces the rate of tooth movement was rapid and the patient’s response to pain was at a minimum.
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    The Effect of Continuous Torquing Forces on Maxillary Central Incisors in Macaque Rhesus Monkeys
    (1963) Willian, David E.
    Continuous torquing moments on the maxillary central incisors were studied cephalometrically and histologically. The experimental sample consisted of five Macaque rhesus monkeys which were subjected to continuous torquing moments applied to the maxillary central incisor for a period varying from nine to twenty weeks. The following conclusions were drawn: On the basis of cephalometric evaluation, the greater the magnitude of the amount of the moment the greater the amount of tooth movement that occurred. The total movement of the apices of the incisors diminished with a decrease in the level of the moment. The incisors (M V) which were subjected to a heavy torquing moment showed considerable root resorption. In contrast, the incisors which were exposed to intermediate (M IV) and light (M I and M II) moments exhibited minimal root resorption. Clinically, the lighter forces produced less mobility of the maxillary central incisors. The application of a heavy continuous moment (M V) resulted in excessive mobility of the incisors. Microscopically, there was no evidence in any of the monkeys of inflammation in the pulp or periodontal membrane of those teeth which were moved orthodontically. Depressive forces delivered by the base arch produced truncation of the apices of the incisors in each animal.
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    The Relation between Force Magnitude and the Center of Rotation in the Maxillary Incisor
    (1962) Kulis, LeRoy Howard
    When a tooth is tipped, it moves about a center of rotation, but the exact location of this center has been the subject of much discussion and confusion. This study was designed to locate the centers of rotation of upper central incisors by application of known forces to the teeth of fourteen patients. Records were taken to ascertain the rate of movement and pain threshold, and the axis of rotation was located by superposing accurate periapical films. The results show that there is no significant difference in the centers of rotation when forces of 51 and 121 gms. were used. The teeth tipped about points located apically at 1.2 and 1.2 mm. from the centroid of the root for groups studied. The teeth moved most rapidly immediately following the first application of force, and then a lag period followed with no tooth movement. This was followed by a steady small incremental rate until the space closed. The pain threshold dropped greatly during the first day of tooth movement. The direction and type of tooth movement were able to be observed on the films. Both the rate of movement and the pain response recorded concurred with observations made daily in the clinic. This study was designed to test the validity of the Moment/ Force Ratio used to locate the centers of rotation. The results obtained were very close to those found using this ratio, and therefore gave clinical support to this theory. The conclusion reached by this study indicates that the procedure was able to accurately locate the center of rotation, found to be just apical by 1.2 to 1.3 mm. from the centroid of the root.