Browsing by Author "Nelson, Charles"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Changes of the Nasolabial Angle Due to Orthodontic Treatment and Facial Growth
    (1987) Sessions, Jeffrey D.; Garner, LaForrest; Miller, James; Nelson, Charles; Shanks, James; Barton, Paul
    This study addressed the quantitative changes of the Nasolabial angle, lip retraction and columellar changes due to treatment with concomitant growth. Sixty initial and final lateral headplates were examined on prepubertal children who underwent comprehensive orthodontic treatment. The angular changes in the Nasolabial angle (△NLA), Labial angle (△A) and Nasal angle (△B) were measured along with the horizontal (△H) and vertical (△V) linear changes of maxillary central incisor. Each of these five measurement changes was tested for the effects of extraction and gender. Correlations were drawn between the △NLA: △AH, △NLA: △V, NLA: △A, △NLA: △B, and △A: △H. Analysis of variance showed that extraction therapy exhibited a larger treatment change than non-extraction therapy for the NLA and upper lip, with the NLA increasing in magnitude and the Labial angle showing upper lip retraction. There was also a sex difference for the treatment change in the lower border of the nose. The only high correlation found was between the opening of the NLA and the retraction of the upper lip (NLA: △A gave r = -0.84). The other correlations were significant but low. These findings could aid in orthodontic treatment planning when changes in the upper lip and NLA will affect the facial esthetics.
  • Thumbnail Image
    Item
    Time Course of Osseous Healing at Endosseous Implant Interfaces
    (1992) Tardy, Shelley R.; Roberts, W. Eugene; Garetto, Lawrence P.; Hohlt, William F.; Shanks, James C.; Nelson, Charles
    The purpose of this study was to examine the time course of endosseous implant healing in trabecular bone. Thirty-six, six month old rabbits were used and stratified into three groups of twelve animals (six control, six experimental). Each experimental animal had two implants placed, bilaterally, in the dorsal surface of the nasal bones. Control animals had soft tissue reflection on the left side nasal dorsum and soft tissue reflection with periosteal removal on the right side nasal dorsum. Prior to surgical procedures and implant placement, a series of intravital bone labels were initiated for all animals. The three groups were allowed to heal four, eight, and 12 weeks, respectively. Immediately after euthanizing the animals, torque test procedures were performed on all left side implants. Following histologic processing, analyses were conducted on midfrontal sections of control sites and implants using microradiography, polarized-light microscopy and epifluorescent microscopy. The implants were divided into three regions: supraflange, coronal, and apical. Control sites were separated into cortical and trabecular regions. Within each implant region, the percent woven and lamellar bone was recorded as well as the percent of bone in contact with or near the implant. Osseous remodeling was detected by fluorescent bone labels. Using these markers, data were categorized as old bone, new bone (woven or lamellar), and unmineralized tissue. In control animals, periosteal removal from the rabbits' nasal dorsum had a limited effect on producing noticeable differences in physiologic response compared to the soft tissue reflection-only control sites. The primary responses found in experimental animals were in the coronal implant region. Significantly more new and old bone was present within this region than in the supraflange and apical regions for all healing times. The only significant time factor found was the increased amount of new woven bone in the four week healing group of the coronal and apical regions. Implant geometry, length and the presence of a flange, appears to have been a more significant influence on osseous response than healing time. Little periosteal woven callus and essentially no trabecular response were observed in experimental animals at the time studied. Because of the shortness of the implant (4.0 mm), the most apical portion had limited extension into trabecular anatomy. Limited proximity to osseous tissue in the apical region may explain the lack of trabecular response. The majority of bone and its physiologic adaptation response occurred in the coronal region since this area is more cortical in nature.
  • Thumbnail Image
    Item
    Tooth Movements Associated with Deep Overbite Correction of Class II Division 1 and Class II Division 2 Malocclusions in Post-Pubertal Patients Using Continuous Archwire Mechanics
    (1987) Samuelson, Greg S.; Garner, LaForrest; Hohlt, William; Shanks, James; Nelson, Charles; Barton, Paul
    The orthodontic profession has assumed much of the responsibility for the improvement of function of the teeth and jaws. Since function is closely associated with overbite, the correction of vertical overbite discrepancies comprises a major part of clinical orthodontics. This investigation was undertaken to describe the movements that teeth undergo during the correction of excessive overbites and to correlate these movements to the change in overbite. A total of 139 cases were selected from the records of the Indiana University School of Dentistry, Department of Orthodontics, including 87 Class II Division 1 and 52 Class II Division 2 cases. The selected cases had an excessive pre-treatment overbite of 4.0 nm or more as seen cephalometrically and a satisfactory post-treatment result. In addition, they were clinically determined to be post-pubertal, indicating essentially no growth potential during the treatment period. Pre and post-treatment tracings of the cephalograrns were made and measurements collected from the tracings. Superimpositions were prepared of the pre and post-treatment radiographs and the general trends that appeared were noted. The change in overbite was correlated to tooth movements in both Class II Division 1 and Class II Division 2 cases using the Pearson test of correlation coefficients. The results indicate that the tooth movements most commonly seen in treatment to reduce excessive overbite occur mainly in the mandibular arch. In Class II Division 1 cases, the change in overbite was significantly correlated to the reduction in vertical height of the mandibular incisor and to the increase in the angulation of the mandibular incisor to the mandibular plane. In Class II Division 2 cases, the change in overbite was significantly correlated to the increase in vertical height of the mandibular molar, decrease in the vertical height of the mandibular incisor, increase in angulation of the mandibular incisor to the mandibular plane and increase in the angle formed by the occlusal and mandibular planes. Not all measurements recorded were significantly correlated to the change in overbite. However, it should be noted that the findings of this study describe a group, that a great deal of individual variation exists, and that are factors which do not show any statistical significance for the group may have an effect in isolated cases.
  • Thumbnail Image
    Item
    Trabecular Adaptation to Continuously Loaded Endosseous Implants
    (1993) Bailey, Grant S.; Roberts, W. Eugene; Garetto, Lawrence P.; Baldwin, James J.; Nelson, Charles; Shanks, James C.
    Several studies have shown endosseous implants placed in areas of thick cortical bone to be an effective means of anchorage in complex orthodontic cases. The purpose of this study was to examine the viability of endosseous implants as orthodontic/orthopedic anchorage when placed in this cancellous bone. Eighteen 6-month-old male rabbits were used and stratified into three groups of six animals. Two implants placed (bilaterally) in the dorsal surface of the nasal bones. After a 12-week healing period, the control group (C) had a passive spring placed between the implants, and the 1 Newton constant group (1 NC) received a spring that delivered a constant compressive load of 1N. A 1N load was applied to the progressive load group (3NP) and sequentially increased to 3N over the course of the study. Bone labels were administered throughout the experiment at designated time intervals to provide quantification of the physiologic activity. Following histologic processing, analyses were conducted on midfrontal sections using microradiography and fluorescent microscopy. The implants were divided into three regions: supraflange, coronal, and apical. Within each region the percent woven and lamellar bone was recorded as well as the percent bone in contact with or near the implant surface. Remodeling activity was observed by using fluorescent bone labels. In the sections analyzed using fluorescent microscopy, the regions were further subdivided into zones. Using the bone label data, bone was categorized as old bone, new woven bone, new lamellar bone and marrow space. Within animal, paired t tests revealed no significant difference between right/left implants. Data was pooled and an ANOVA run to test for difference between groups. Few significant differences were seen. Student Newman-Keuls sequential range tests were used to test between region and zone. The coronal region showed trends of more bone overall in the 1NC and the 3NP load groups p < 0.10. The apical region had less bone overall. The fluorescent data showed few significant differences between groups; however, the coronal region showed trends of more bone overall. A RAP effect was observed in the zonal analysis for new lamellar bone. Sutural remodeling was observed at the cortical plate over the nasal suture. A significant trabecular response was not seen in this study; however, the implants in the experimental groups remained stable throughout the study possibly due to the implant design. It was concluded that implants placed in thin cancellous bones are suitable for use as orthodontic/orthopedic anchorage.