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Item 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.Item Normal Postural Changes of the Soft Tissue Facial Profile During Function(1958-04) Hamula, WarrenA sample of 32 adolescents with acceptable facial proportions was procured. Using the Bolton method, cephalometric records were taken on each patient. Radiographic and developing techniques were used which gave the maximum definition to hard and soft tissues. Four basic positions were recorded. Two variations of lip posture, relaxed and light closure, were taken at two mandibular positions, rest and centric. Two exposures of each position were taken so that mean values could be used and aid in the accuracy of the study. Integumental landmarks were established relative to hard tissue structures. A horizontal plane was constructed by using hard tissue areas sella and nasion, SN-6. A perpendicular to this plane was constructed through sella. Linear measurements in a horizontal and vertical direction to the SN-6 ° located the landmarks in space. These planes also served as guide lines to superpose various positions so movements of soft tissue points could be observed. Mandibular rest position with the lips relaxed was used as the basic position for superposing. Variation in soft tissue points were related to this position designating movements in a plus or minus direction. Means of the differences were determined to evaluate the special movement of the integumental landmarks. The following conclusions have been established by this study: In normals soft tissue movement when significant are low in value. To effect lip closure from a relaxed position integumental landmarks moved minimally. In general vertical movements are greater than horizontal movements. Greatest activity of soft tissue landmarks occurs when the lips are closed from mandibular rest position. In most cases the lips when relaxed do not touch. This is true in both rest and centric position of the mandible. Only four cases of the 32 touched in centric position, and none touched in rest position. The average distance of inter-labial gap in rest position was 3.7 mm. The average distance of inter-labial gap in centric position was 1.9 mm. The upper lip plays a minor role relative to the lower effect lip closure. Subnasale and superior labial sulcus moved only in a vertical direction during closure. Labrale superior moved posteriorly and inferiorly during closure. In the lower lip, labrale superior moves only in a superior direction during lip closure. Inferior labial sulcus moves both anteriorly and superiorly. Menton moves superiorly with no significant horizontal deviations when considering only lip closure. Its horizontal deviation is only present when the mandible moves from rest to centric position. The integumental landmarks of the profile show a great deal of independence from mandibular positioning. The vertical positioning of the mandible from rest to centric position does not move soft tissue points equally or proportionately. Only one integumental landmark, menton, moves anteriorly during mandibular closure from rest position. A standard for normals has been developed and a graphic picture, a grid, of normal lip behaviour has been presented. The grid was developed to better understand the information gathered in this study. It is hoped that it will prove a valuable tool to evaluate soft tissue variations in a sample of malocclusions.