Browsing by Author "Garner, LaForrest"

Now showing 1 - 7 of 7
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    A Study of Nasopharyngeal Airway Size and its Relationship to Maxillary Morphology and Position in Monozygotic Twins
    (1983) Schmidt, Randall A.; Garner, LaForrest; Arbuckle, Gordon R.; Barton, Paul; Kafrawy, Abdel; Shanks, James C.
    This investigation was undertaken to study possible relationships between the size of the nasopharyngeal airway space and the morphology of the growing face. With reduction of the nasopharyngeal airway space, mouth breathing often becomes necessary. If mouth breathing becomes the dominant form of respiration it is believed to cause morphologic alterations in the cranioskeleton, as in the so-called "adenoid facies" individual. This environmental alteration in facial growth pattern, in contrast to the facies derived from genetic predisposition, can be tested only by using a sampling of monozygotic (identical) twins. It is assumed that since both twins have identical growth determinants any variances in their facial morphology would be due to environmental factors. Thirty-five pairs of monozygotic twins were divided on the basis of having a significantly differing intrapair airway size or a similar intrapair airway size. Thus, the independent variable in this investigation was the airway size difference between identical twins in a pair. Seven parameters were chosen to identify any maxillary morphologic changes among twin pairs. From lateral cephalometric radiographs and study casts of the twin pairs, data were accumulated for statistical analysis. It was hypothesized that significant differences between the variances in the maxillary traits of the two groups would be related to the size differences of the airways used in dividing these groups. Lower facial heights and intermolar distances were significantly different between the two groups of twins. The findings of this investigation support the opinion that nasal obstruction is related to changes in the morphology of the maxilla. The relationship is such that with decreased nasopharyngeal airway size the lower facial height tends to increase and the maxillary intermolar widths decrease. No significant changes appear to occur concomitantly in the maxillary antero-posterior relationship to the cranial base, cant of the maxilla, maxillary incisor flaring, upper facial height, and posterior vertical height of the nasomaxillary complex.
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    An Analysis of the Fatigue Resistance of Beta Titanium and the Effect of Spot-Welding Upon the Fatigue Resistance of this Alloy
    (1984) Wong, Michael B.; Garner, LaForrest; Baldwin, James; Moore, Keith; Barton, Paul; Shanks, James
    This investigation was designed to establish a fatigue curve for beta titanium, determine the effect of spot-welding upon the fatigue resistance of this alloy, and provide qualitative observations about surface characteristics of different batches of TMA in relation to their fatigue lives. Rectangular .016" x .022" 1MA was evaluated. Twelve specimens in each group were tested, making the total sample size 108. The wire samples were evaluated using a cantilever bend test in which specimens were stressed cyclically at varying deflections. Two welded groups were also tested. An auxiliary .016" x .022" TMA was welded to a main test segment of TMA with the .016" side against the opposing .016" side. The weld overlap varied at 25% for one group and 50% for the other. These specimens were stressed at the area adjacent to the weld. One specimen from each group was viewed under the scanning electron microscope to evaluate the fractured area. Specimens from three different batches of 1MA were tested and their fatigue lives compared at .625 inch deflection. One specimen from each batch was viewed under the scanning electron microscope to evaluate its surface structure. A fatigue curve for TMA was plotted from the data. At .625 inch deflection, welding an auxiliary onto the main segment significantly decreased the fatigue resistance of the wire. However, both welded groups had comparable fatigue lives. These wire specimens fractured at some point adjacent to the welded site. Fatigue resistance differed significantly between one batch of TMA and the other two. The scanning electron micrographs of representative specimens from each batch seemed to indicate that the fatigue resistance of each batch was inversely related to its surface roughness.
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    An Evaluation of the Bond Strength and Failure Site of Two Orthodontic Direct Bonding Systems
    (1979) Hyde, Kenneth R.; Garner, LaForrest; Tomich, Charles E.; Dirlam, James; Kasle, Myron
    Two commercially available orthodontic direct bonding systems were evaluated for ultimate tensile strength and failure site. Both Endur (Ormco Corp.) and Solo-Tach (L. D. Caulk Co.) are Bis-GMA resin adhesives, but only Endur required the use of a sealant prior to bonding. Metal brackets intended for use with Endur are backed by a thin stainless steel pad and fine wire mesh. Bracket bases for use with Solo-Tach were fully perforated stainless steel pads (GAC International, Inc.). Two hundred human bicuspid teeth were divided into four groups to test the four combinations of bracket and adhesive types. Half of each group was tested 30 minutes after bonding and half was tested after 3 weeks, with thermocycling in the final week. Failure sites were completely opposite for these two adhesives regardless of which bracket type was used. Endur (sealant and adhesive) failed primarily at the bracket-adhesive interface, while Solo-Tach (adhesive only) failed primarily at the enamel-adhesive interface. The sealant-adhesive seems to form a more tenacious bond to enamel. Mesh bracket bases formed a significantly (p<.025) stronger bond than fully perforated bracket bases with either adhesive. Some difference was still apparent after correcting for the difference in base area between mesh and perforated base types. No significant difference in tensile bond strength were found between the two adhesives or between 30-minute and 3-week tests. It was noted that several other factors, such as protection of oral tissues, working time, and ease of manipulation must be evaluated in chasing a satisfactory bonding system.
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    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.
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    Displacement of Anchorage in Controlled Root Movement at Various Force Values
    (1970) Winkler, Robert A.; Cunningham, Donald; Garner, LaForrest; Mitchel, David; Norman, Richard; Shanks, Jim
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    The Prevalence of Intermaxillary Tooth Size Discrepancies
    (1984) Oppenhuizen, Gregory J.; Garner, LaForrest; Arbuckle, Gordon; Barton, Paul; Goldblatt, Lawrence
    The purpose of this study was to determine the percentage of patients with malocclusions who have intermaxillary tooth size discrepancies. After a range of acceptable anterior and first molar to first molar intermaxillary tooth size ratios was obtained from an analysis of 30 excellent occlusions, the mesiodistal tooth size from first molar to first molar of 100 patients with malocclusions (43 class I, 42 class II, 15 class III) was measured. Of the total sample, 43% had an anterior intermaxillary discrepancy and 12% had a first molar to first molar intermaxillary tooth size discrepancy. Regarding the anterior ratio, 81% of patients with discrepancies (35% of the total sample) had maxillary teeth which were too small or mandibular teeth which were too large and 19% of those with discrepancies (8% of the sample) had maxillary teeth which were too large or mandibular teeth which were too small. Regarding the first molar to first molar ratio, 75% of patients with discrepancies (9% of the total sample) had maxillary teeth which were too small or mandibular teeth which were too large and 25% of those with discrepancies (3% of the total sample) had maxillary teeth which were too large or mandibular teeth which were too small. Separate calculations for patients with class I, class II and class III malocclusions showed discrepancies in anterior intermaxillary tooth size ratio in 49% of class I patients, 29% of class II, and 53% of class III. There were 14% of both class I and class II groups, and 7% of class III. Since many patients who seek orthodontic correction of their malocclusion will have intermaxillary tooth size discrepancies, orthodontists should routinely investigate the possibility of such discrepancies.
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    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.