Browsing by Author "Nelson, Charles L."
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Item A Clinical Study Evaluating a Mandibular Repositioning Appliance to Treat Obstructive Sleep Apnea(1992) Coghlan, J. Kevin; Roberts, W. Eugene; Beiswanger, Bradley B.; Shanks, James C.; Garner, LaForrest D.; Hennon, David K.; Nelson, Charles L.The study evaluated the effects of a mandibular repositioning appliance (MRA) in patients with obstructive sleep apnea. The MRA was designed to hold the mandible anteriorly in an attempt to maintain a patent airway. Eleven subjects completed a full-night polysomnogram wherein their normal sleep was recorded half the night without the appliance (control) and the other half with the appliance (test). The sequencing of test and control halves was randomly assigned to avoid bias. After seven subjects were tested with the MRA, the MRA was modified for four additional patients by placing anterior vertical elastics (MRA*) to minimize the opening of the mandible. The skeletal and soft tissue changes with both appliances were analyzed using lateral cephalometric radiographs. The MRA was found to have no significant effect on the obstructive sleep apnea patients as a group. Individual response to the appliance varied from noticeably worse to marked improvement. Subject #2A exhibited the reduction of a moderate-to-severe apnea (Apnea-hypopnea index 55.92) to a clinically acceptable level (Apnea-hypopnea index 9.57) with appliance wear. The treatment was considered successful. Significant cephalometric changes with appliance wear were increased lower facial height, a superiorly positioned hyoid bone relative to the mandibular plane, and a decreased posterior airway space. No cephalometric measurement could accurately predict the outcome of the treatment, and posterior airway space, commonly measured in sleep research, was not reliable. The mandibular repositioning appliance was effective in treating a small percentage of individuals with obstructive sleep apnea. A polysomnogram was needed to quantitatively measure the effectiveness of treatment. Under no circumstance should a subjective evaluation by the patient or the clinician be used to assess treatment results. Further investigation is required to evaluate the long-term effectiveness of this treatment. Periodic follow-up sleep studies are required for any patient treated with this appliance until more long term studies are completed.Item A Comparison Study of Temporomandibular Joint Symptoms in Patients Following Mandibular Advancement by Bilateral Sagittal Split Osteotomies: Rigid Fixation Versus Nonrigid Fixation(1989) Flynn, Brent Cameron; Roberts, W. Eugene; Brown, David T.; Nelson, Charles L.; Shanks, James C.; Hennon, David K.Primary consideration must be given to the temporomandibular joint when planning and performing orthognathic surgical procedures. It has long been understood that the status of the temporomandibular joint can easily and unintentionally be altered during orthognathic surgery, regardless of the method of fixation used. With the advent of modern fixation techniques, many clinicians and investigators have questioned the effects of rigid fixation on the temporomandibular joint. To investigate this, a clinical study of 40 patients treated with mandibular advancement for retrognathism was performed. Twenty patients were treated with rigid fixation while another 20 patients had inferior border wires placed with anterior skeletal fixation. All patients were asked questions regarding the history of their temporomandibular joints. In addition, all patients received a clinical postoperative temporomandibular joints. In addition, all patients received a clinical postoperative temporomandibular joint evaluation. The results were statistically analyzed with the Chi-square analysis and Standard T test. It was determined that the Null Hypothesis could not be rejected for any of the symptoms evaluated in this study. The results support the belief that rigid fixation is no different when compared to wire osteosynthesis in terms of prevalence of temporomandibular joint symptoms.Item The effects of primary alvelar bone grafting on maxillary growth and development(1993) Tanimura, Leslie K.; Avery, David R.; Hennon, David Kent, 1933-; Nelson, Charles L.; Sadove, A. Michael; Branca, Ronald A.This investigation served as a follow-up of the unilateral and bilateral cleft lip and palate patients who underwent primary alveolar bone grafting at James Whitcomb Riley Hospital of the Indiana University Medical Center. The sample consisted of 18 patients, 15 males and three females, who received primary alveolar grafts between September 7, 1983 and March 5, 1985. Thirteen had complete unilateral clefts, and five had complete bilateral clefts of the lip and palate. The mean age of the group was 8 years, and none had received orthodontic treatment. The statistical analysis of the lateral cephalometric radiographs revealed significant differences in maxillofacial growth between the Riley sample population and the non-cleft, age-matched patients in the University of Michigan Growth Study. The Riley data were, overall, statistically and proportionately smaller than the normal population. These findings are due to the smaller skeletal size of the Riley group. Arch symmetry measurements indicated that at 8 years of age there were significant differences from ideal or perfect symmetry. Due to existent dental development and scarring from the palatal procedure, these findings were expected. Ideal symmetry may not be a realistic achievement for the cleft patients. Palatal surface area values were visually analyzed through graphs. The growth patterns of the Riley population were similar to those of the normal and non-grafted cleft groups in a study from the University of Miami. The data supports the theory that primary alveolar bone grafting, as performed at James Whitcomb Riley Hospital, does not result in growth attenuation.Item Histological and Mechanical Analysis of Bone/Implant Interface in Female Retired-Breeder Rabbits(1992) Bruch, Christopher G.; Roberts, W. Eugene; Garetto, Lawrence P.; Arbuckle, Gordon R.; Nelson, Charles L.; Shanks, James C.Endosseous implants have been accepted as a viable dental and medical adjunct and are now used for multiple dental applications. The majority are placed in patients of relatively advanced age, and, as such, the increased use of implants has raised questions in the areas of bone healing and metabolism associated with their placement. This study evaluated the mechanical and histological aspects of the bone/metal interface of endosseous titanium implants in compact and trabecular bone. Two implants were placed: one in the distal metaphysis (M) and one 2.0 cm proximal in the diaphysis (D). Right side limbs were subjected to a sham surgery and served as controls. The rabbits were sacrificed at six, 12, and 24 weeks healing time. Multiple fluorochrome labels were given to mark sites of bone formation. At sacrifice, all implants were tested for interface torque strength. Microradiography and fluorescent light microscopy were used to determine percent volume of bone and marrow space, bone/implant interface characteristics, percent labeled bone surface area, and percent labeled bone volume. D implants required about 20 percent more torque to mechanically disrupt the bone/implant interface than M implants. Values were M (combined groups) 33.4 N-cm ±15.5 N-cm, and D (combined groups) 41.5 N-cm ±16.0 N-cm (Mean ±SD, n = 8, p<.07). The percent of bone in direct contact with the implant surface appeared to increase only slightly with time. Direct contact occurred on 11.2%, 9.5% ±8.5% and 13.9% ±6.6% of the M implant surface in six, 12, and 24 week specimens, respectively. Direct contact occured on 11.7%, 10.2% ±2.4% and 19.5% ±0.35% of the D implant surface in six, 12, and 24 week specimens, respectively. Total bone volume in implanted D specimens was less [Exp.= 91.1% ± 3.1%, Cont. = 95.5% ± 0.73% (Mean ±SD)] and marrow space volume was greater [Exp. = 8.9% ±3.02%, Cont. = 4.6% ±0.73% (Mean ±SD)] than in controls (p<.02). The percent labeled bone volume was greater in the implanted specimens than in their controls (p<.001). This difference decreased over time. Implanted D specimens also showed significantly more (p<.001) labeled bone surface area than controls. These findings suggest that when implants are placed in elderly subjects, normally inactive bone becomes very active. Also, it seems that bone quality, not quantity, determines interface strength.Item Tensile Bond Strength of Light-Activated Composite for Bonding Metal and Ceramic Brackets(1989) Shepherd, Jeffrey Dean; Roberts, W. Eugene; Moore, B. Keith; Shanks, James C.; Hennon, David K.; Nelson, Charles L.Visible light-activated composite adhesives offer several advantages over conventional autopolymerizing adhesives such as extended working time, immediate ligation and easier cleanup. This study compared in vitro tensile bond strength and site of failure of a new light-activated adhesive and a commonly used two-paste adhesive for bonding ceramic and metal brackets. Manufacturer recommended light-activation times were evaluated using hardness as an indicator of cure. Light-activated composite specimens 0.3 mm in thickness were cured beneath metal brackets for 30 seconds and ceramic brackets for 10 seconds. Knoop hardness values were determined at various time intervals over a seven-day period. An evaluation of the hardness testing data indicated that manufacturer recommended cure times for both brackets were adequate. A significant increase in hardness over time also was noted for all specimens. Mean tensile bond strength comparisons were determined by dividing 88 human maxillary premolars into four groups of 22 specimens each. Each group had either metal or ceramic brackets bonded with either two-paste or light-activated adhesive. After bonding, specimens were thermocycled and stored in a humidor set at 37°C for seven days. Ceramic bracket specimens underwent further preparation to decrease bracket failures during debonding. At the end of seven days specimens were subjected to tensile stress using an Instron mechanical testing machine until failure occurred. No significant differences in tensile bond strength were found between light-activated and two-paste adhesives when similar brackets were used. Ceramic brackets bonded with either adhesive had significantly higher bond strengths than metal brackets bonded with the same adhesive. Nineteen ceramic brackets failed during debonding; however, tensile bond strengths of these specimens were not significantly different from those specimens where adhesive failure occurred. Specimens were viewed by light microscopy to determine percent bond failure at enamel surface. Groups using ceramic brackets tended to have a higher percent bond failure at enamel surface than did metal bracket groups. High bond strengths demonstrated by ceramic brackets coupled with the brittleness of the bracket itself requires special attention during debonding to avoid enamel damage. Early light-cured adhesives were not practical due to slow setting times plus their inability to cure beneath metal brackets. The adhesive tested in this study appears to have overcome these problems when manufacturer's recommended cure times are used.Item The Influence of Etching Times and Fluoride Acid Gels on the Bonding of Orthodontic Brackets(1988) Hoagburg, Steven Joseph; Garner, LaForrest D.; Shanks, James C., Jr.; Moore, B. Keith; Nelson, Charles L.; Hennon, David K.This study evaluated the influence of etching times and the addition of fluoride to a phosphoric acid gel on the tensile bond strength of orthodontic brackets bonded to human enamel using a 40% phosphoric acid gel containing no fluoride, 0.44% sodium fluoride and 0.8% stannous fluoride. The percent cohesive failure after debonding was also studied. In addition, the enamel surface was evaluated for reaction products and etching morphology by scanning electron microscopy. Such a reduction in etching times and the addition of fluorides into the etchants should result in less damage to the tooth and a decrease in enamel decalcification. For the tensile bond strength part of the study, 189 noncarious and nonrestored human premolar teeth were divided into three groups corresponding to the three different etching gels. Each group was subdivided into three other groups which consisted of the three etching times, 15, 30 and 60 seconds. There were a total of 21 samples in each of the nine groups. After etching with the appropriate gels and etching times, brackets were bonded to the buccal surfaces of the teeth with Concise orthodontic resin. The samples were thermocycled and stored in 37°C until testing. Seven days after bonding, the samples were tested in tension in an Instron testing machine. After debonding, the percent cohesive failure was evaluated under the microscope at 40X. All groups were compared using the two way analysis of variance. There was no significant difference in tensile bond strength between the three etchants. However, etching with the NaF etchant for 15 seconds produced significantly different results from the other NaF groups. However, there was no significant difference related to etching times for the other two etchants. The highest tensile bond strength (71.7 ± 2 3.0 kg/cm2 ) was recorded with the H3PO4 gel when etched for 60 seconds and the lowest tensile bond strength (48.9 ± 13.6 kg/cm2) was recorded with the NaF etchant when etched for 15 seconds. There was no significant difference in the percent cohesive failure between the three etchants. There was a significant difference in the NaF group when the etching times were changed. Etching with the NaF group for 15 seconds showed a significant difference when compared with the other NaF groups. However, the other two etchants showed no significant difference between the different etching times. Cohesive failure for all groups occurred mainly at the mesh-resin interface. The highest percent cohesive failure (95.7 ± 14.8%) occurred in the SnF2 group when etched for 30 seconds. The lowest percent cohesive failure (70.9 ± 40.6%) occurred in the NaF group when etched for 15 seconds. In the second part of this study nine human maxillary premolar teeth were etched with the three different gels at the three time intervals and were evaluated under the SEM at magnifications of 1500X and 5000X for reaction products and etching morphology. Fluorides incorporated into the etching gels should reduce enamel decalcification, and decreasing the etching times also reduces enamel loss. Results of the present study suggest that incorporating of these fluorides in the etchants, along with decreasing the etching times, warrants clinical evaluation.