Browsing by Author "Shanks, James C."
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Item A Bolton Analysis Comparison of Hispanic vs. Caucasian Samples in Indianapolis, Indiana(2004) Kutsch, Devon R.; Roberts, W. Eugene; Baldwin, James J.; Hohlt, William F.; Hathaway, Ronald R.; Shanks, James C.Although many studies examining tooth size discrepancy have been conducted, many were originally done on unknown populations and genders. They were also conducted on Class I ideal occlusions. Since that time, there have been many studies of the Caucasian population, but little has been done to compare the differences between Caucasian and Hispanic patients. The objective of this study was to establish whether there is a greater incidence of Bolton tooth mass discrepancies in the Hispanic population than in the Caucasian population of Indianapolis, Indiana. Secondly, the objective was to examine possible differences in the incidence of tooth mass discrepancy according to gender and dental malocclusion in the same sample. A sample of 292 pretreatment casts was measured to determine the incidence in both populations. The sample was composed of 146 Caucasian patients and 146 Hispanic patients. The patient sample was composed of 86 Caucasian females, 60 Caucasian males, 87 Hispanic females, and 59 Hispanic males. Patient's ethnicity was defined by photos and patient history. Individuals with a known mixed ethnicity were excluded. The sample was taken from patients in both the pre- and postdoctoral clinics at Indiana University School of Dentistry Section of Orthodontics, and the offices of selected private practitioners. Mesio-distal width of all teeth from first molar to first molar was measured with the mesio-buccal and disto-buccal contact areas normally being the widest area. The inter-incisal angle was evaluated utilizing lateral cephalometric radiographs. The molar and cuspid classification, overjet, overbite, and maxillary central incisor anterior-posterior dimension was measured from the dental casts. Results demonstrated that overjet, overbite, interincisal angle, molar class, and cuspid class did not have a significant effect on the Bolton discrepancy with each gender or between the two ethnic groups. Ethnicity did have a significant effect on the overall and anterior Bolton discrepancy with the ratio the Hispanics showing a significantly higher proportion of cases outside normal. Exploratory analysis also demonstrated which teeth were most discrepant. Clinicians are faced daily with the challenge of trying to produce ideal occlusions with optimal esthetics. Tooth mass discrepancies present an impediment to the clinician in trying to achieve this goal. By studying malocclusions common to a population, the clinician can more effectively treat his/her patients by being aware of potential problems that might compromise the final outcome. With the burgeoning Hispanic population in the US, this study was indicated using the Hispanic population as a patient base to ascertain how commonly used norms relate to the Hispanic population. This study demonstrated Hispanics have a significantly greater proportion of patients with a significant Bolton discrepancy. Being aware of this will allow the clinician to treat his/her patients more effectively and obtain an optimum esthetic and functional result.Item A Cephalometric Investigation of Hypohidrotic Ectodermal Dysplasia(1981) Harbour, John P.; Bixler, David; Garner, LaForrest D.; Sondhi, Anoop; Shanks, James C.; Bowman, Sally A.The characteristic features of hypohidrotic ectodermal dysplasia were first reported in 1848 by Thurnam. Since this first classification, the characteristic facies of this syndrome have often been reported. Individuals with this disease have been described by various authors as having a prognathic mandible, an underdeveloped mandible, a small face, an elongated maxilla, an anteriorly positioned maxilla, a midface hypoplasia, and more. Only one cephalometric study of this syndrome exists and it was performed to study growth. The present study was designed to describe and quantify, through the use of cephalometric analysis, any facial and cranial variations in these patients. The study also attempted to describe the variations found in female heterozygotes. Nine hypohidrotic ectodermal dysplasia patients and their families were studied. A total of 31 individuals participated. When the data obtained from the cephalometric measurements were grouped into probands, gene carriers (heterozygous females), and normals, it was found that certain variations did exist. The size and position of cranial base and the mandible in all three groups were within normal limits (±2 S.D.). The maxillae of the probands were significantly short, yet positioned normally. The gene carriers also showed this trend, but the results were not significant. Profiles (soft and hard tissue) were significantly concave in the proband and gene carrier groups due to a combined effect of altered maxillary and mandibular positions.Item A Cephalometric Study of Non-Cleft Parents of Children with Cleft Lip, Cleft Lip and Palate, and Cleft Palate : Evidence to Support a Different Etiology for Isolated Cleft Palate Versus Cleft Lip?(1993) Sadler, Charles A., Jr.; Ward, Richard E.; Bixler, David; Hathaway, Ronald R.; Shanks, James C.; Roberts, W. EugeneCleft lip with or without cleft palate (CLI P) and isolated cleft palate (CP) have been shown to be separate epidemiologic and embryologic entities. Furthermore, it has been proposed that noncleft biologic parents of children with facial clefts may demonstrate craniofacial differences genetically predisposing them to pass on the cleft phenotype to their offspring. With these two hypotheses in mind, the objective of the present study was to determine if differences exist in the craniofacial morphology between parents of CL/P children and parents of CP children. Twenty-seven measurements were obtained from anterior-posterior (AP) cephalograms on 127 biologic parents of sporadic CL/P and CP children. Each measurement was compared with sex and age-matched normals, and Z-scores were determined. The mean Z-scores for each group were tested for significant differences from normal and from each other. In agreement with past literature, the craniofacial morphology of parents of cleft children was generally found to have greater facial widths and shorter facial heights. Differences between the findings of the present study and the past literature are discussed. Although CL/P and CP are thought to be separate entities, differences between the parents of CL/P and CP children were not statistically evident.Item A Comparison of Shear-Peel Bond Forces of Flattened and Unaltered Brackets on Flattened and Curved Enamel Surfaces(2007) Wyatt, Tracy D.; Katona, Thomas R.; Baldwin, James J.; Hohlt, William F.; Moore, B. Keith; Shanks, James C.One aspect of bond strength testing that varies among researchers is the contour of the tooth and bracket bases that are tested. Unaltered teeth with as-manufactured brackets are the most commonly used combination. Flattened teeth with unaltered bracket bases and mechanically flattened teeth and brackets are also used. The intended purpose of this project was to determine the effect of tooth and bracket contour combinations on the shear, tension and torsional bond forces of bonded brackets. The crowns of two-hundred and four bovine incisors were potted in acrylic tubes with their facial surfaces slightly protruding. The facial surfaces of half of them were ground flat on a Wehmer model trimmer (The Wehmer Corporation, Lombard, IL). The remainder were contoured on a Wehmer model trimmer using a jig that rotated the tooth's facial surface on a radius of approximately 3 inches. One-hundred and two maxillary right central incisor brackets (3M Unitek, Monrovia, CA. Victory Series, .022 slot) were flattened, ten at a time with a 2000 N force on a self-leveling plate in the MTS Bionix testing machine (MTS Systems Corporation, Eden Prarie, MN). Another 102 brackets were unaltered. The Day 1 data set samples (shear-peel loading) were etched with 35% phosphoric acid gel and bonded with Transbond XT Light Cured Adhesive Paste (3m Unitek). This provided 17 specimens for each of four groups: curved tooth/curved bracket (C/C), curved tooth/flat bracket (C/F), flat tooth/curved bracket (F/C), and flat tooth/flat bracket (F /F). The samples were de-bonded in the MTS Bionix testing machine with the force applied parallel to the bracket base, (i.e., in shear-peel) and the peak forces were recorded. Due to large variations in the results and low forces compared with previously published studies from this laboratory, the bonding protocol and loading were altered for Day 2 testing. Rather than torsion loading, the shear-peel debond set was repeated. The following changes were made to the bonding protocol. The samples were pumiced following sanding and stored in fresh de-ionized water prior to bonding. The samples were also dried with compressed air following etching and the primer was thinned with compressed air. Following preparation the samples were debonded in the MTS Bionix testing machine and peak forces were recorded. These results were also inexplicably variable and relatively low. Day 3 samples, intended for torsion debonding, were bonded the same as the Day 2 samples except that a 3 7% phosphoric acid liquid (Reliance, Itasca IL) was used to etch the samples and a new bottle and tube of Trans bond XT Light Cured Adhesive Primer and Transbond XT Light Cured Adhesive Paste (3M Unitek) were used. The samples were also debonded in shear-peel in the MTS Bionix testing machine and peak forces were recorded. Despite the outlined efforts, these results were also scattered and relatively lower than obtained previously. An analysis of variance model was used to evaluate the bond forces and showed no statistical difference among the groups except that in the Day 2 data set the C/C group was significantly weaker than the F/F group (p= .0452). In the Day 3 data set the C/C group was also weaker than the F/F group though the results were not significant (p=.0739). There is a trend to suggest that the bracket base and crown curvatures may be important factors in determining shear bond force.Item A Comparison of Three Debonding Techniques Employing Two Different Cements(2004) McCabe, Russell; Katona, Thomas R.; Baldwin, James J.; Hohlt, William F.; Moore, B. Keith; Shanks, James C.The theory and practice of bonding orthodontic brackets to enamel has become the accepted standard. However, regardless of the adhesive of choice, much controversy exists regarding bond strength values and testing protocols. Most bond strength testing has been done in either shear/shear-peel or tension. Some studies have used shear and tension and very few have used shear, tension and torsion. Some authors contend there is no difference in the stress required to produce bond failure by either tensile or shear test models. However, it has been shown that stress is not distributed uniformly during loading and each mode of strength testing produces unique stress patterns. Additionally, since in the oral cavity brackets are subject to shear, tensile and torsion forces, it seems logical that a complete picture of bond strength could not be formulated without all three test methods. Confounding the issue is the fact that adhesive research is being performed in non-standardized manners making it impossible to compare results among different researchers. Despite the vast amount of information presented in articles, this has resulted in a lack of consensus regarding clinical bond strength values. The purpose of this investigation was to evaluate the three debonding techniques (shear-peal, tension, torsion) using stainless steel brackets and two different bonding agents (traditional resin cement vs. resin reinforced glass ionomer). The hypotheses of this investigation were (1) the relative shear-peal, tensile and torsional bond strengths will show consistent results and (2) cement type will have a significant effect on the bond strengths. One hundred sixty-two bovine incisors were randomly assigned to 6 groups of 27 specimens per group. Teeth were bonded with either a resin composite adhesive or a resin reinforced glass ionomer cement following manufacturers' instructions. Bonding was performed under controlled temperature and humidity (71 °F± 2° and 56% RH± 5%). In addition, specimens were bonded utilizing a bonding jig that held the thickness of the adhesive constant at 0.006 inches. All groups were tested to failure using the MTS Bionix machine in shear, tension and torsion. The results showed that the resin composite had a significantly higher load at failure in shear and torque than the resin-modified glass ionomer. However, in tension, no significant difference was found between the two cements. Additionally, analysis of relative strength indicated a difference between shear strength and tension suggesting that testing mode influences bond strength values. It is the conclusion of this study that the load at failure for resin composite and resin-modified glass ionomer are not consistent and depend on the loading mode.Item A Comparison of Three Debonding Techniques Employing Two Methods of Tooth Preparation(2003) Long, Robert W.; Katona, Thomas R.; Baldwin, James J.; Hohlt, William F.; Moore, B. Keith; Shanks, James C.Traditionally, orthodontic adhesive systems consisted of three separate agents: an enamel conditioner, a primer solution, and an adhesive resin. Newer systems have combined the conditioning and priming agents into a single acidic primer solution. The purpose of this investigation is to evaluate the three debonding techniques (shear-peel, tension, torsion) using stainless steel brackets and two different methods of tooth preparation (37% phosphoric acid+ primer vs. self-etching primer). The null hypotheses of this investigation are (1) the method of tooth preparation will not have a significant effect on the bond strengths and (2) the relative shear-peel, tensile and torsional bond strengths will show consistent results. One hundred and fifty bovine incisors were randomly assigned to 6 groups of 25 specimens per group. Teeth were prepared for bonding by employing either (1) acid-etching with 37% phosphoric acid+ primer or (2) self-etching primer. The brackets were bonded with a resin composite adhesive under controlled temperature and humidity conditions at 74°F ± 2 and 54% ± 5 RH. In addition, specimens were bonded utilizing a bonding jig that held the thickness of the adhesive constant at 0.152 mm. All groups were tested to failure using the MTS Bionix machine. Results from this study showed that the prime-etching method of tooth preparation had significantly greater mean shear-peel bond strength than did the self-etch method and that the prime-etching method had significantly less mean tensile bond strength than did the self-etch method; however there were no significant differences in torque strengths between the two methods of tooth preparation. In addition, results for the true ratio of mean forces showed shear-peel bond strengths lies clearly above the confidence intervals for the other debonding measures, thus the three measures of debonding are dissimilar in the comparison of the two tooth preparation methods. Thus, both null hypotheses were rejected.Item A Frictional Evaluation of a New Surface-Modified Titanium Orthodontic Bracket(2000) Olsen, Marc E.; Oshida, Yoshiki; Andres, Carl J.; Katona, Thomas R.; Moore, B. Keith; Roberts, W. Eugene; Shanks, James C.Sliding mechanics is a popular method of moving teeth orthodontically. Sliding mechanics refers to the guiding of a tooth by means of the bracket slot along an archwire in response to some applied force. This concept of tooth movement is subject to both static and kinetic friction. An accurate evaluation of an appliance's frictional properties enables a clinician to identify applications where the utilization of a new appliance may be advantageous. The aim of this study was to evaluate the frictional properties of this new surface-modified titanium orthodontic bracket compared with a traditional stainless steel orthodontic bracket and a currently available non-surface modified titanium bracket. Fifteen brackets (5 Stainless steel, 5 Titanium, 5 Coated Titanium) were combined with five archwires from each material type (SS, NiTi, βTi). Frictional evaluation was completed on each bracket material utilizing .021" x .028" size archwire materials in a specially designed apparatus under wet conditions. The frictional resistance was measured on an Instron Universal Testing machine (Instron Corp, Canton, Mass). The brackets/archwire samples were tested one at a time individually. In addition, a single bracket/ archwire sample from each group was repeatedly tested five times. Measurements were made at every 0.1mm for 30mm via a computer attached to the testing machine. An ANOV A was used to determine differences between groups. The results indicate that stainless steel brackets exhibited significantly better static and kinetic frictional properties than the titanium brackets. Stainless steel wires possessed superior frictional properties to NiTi and β-Ti wires. NiTi wires were generally superior than β-Ti wires. As brackets and archwires were reused, the overall frictional values showed a distinct trend to increase.Item A Manpower Study of Orthodontic Specialists for the State of Indiana(1992) Clark, David B.; Roberts, W. Eugene; Arbuckle, Gordon R.; Garner, LaForrest D.; Garetto, Lawrence P.; Shanks, James C.Dental manpower has been studied at national, state and local levels.2, 4, 6, 11, 14, 15, 17-19 Manpower studies of orthodontic specialists also have been conducted,1, 5, 13, 16 but there has been no recent manpower study relative to orthodontic specialists in Indiana. The purpose of this study was to evaluate the busyness and distribution of orthodontic specialists in Indiana and project the need for orthodontists. In early 1990 a survey questionnaire was mailed to Indiana orthodontists. A telephone survey of orthodontic receptionists/appointment clerks was conducted during the same time period to obtain a separate source of data relative to practice busyness and to help evaluate the reliability of the mailed survey questionnaire. The distribution of orthodontists was evaluated by comparing the state population-to-orthodontist ratio to county and regional ratios. The response rate of the mailed survey questionnaire was 91 percent. The ages of orthodontists were evenly distributed with the exceptions of the 46-50 year age group and groups approaching retirement ages. The perceived level of busyness was low with a busyness index of 1.32. A relatively short wait was necessary to examine and start new patients, and few reported a waiting list. There was a high response emphasizing no need for additional orthodontists. Seventy percent felt that they were not busy enough; 99 percent reported that they would like more patients; and many desired large numbers of additional patients (41 or more). A large number of orthodontists had satellite offices or were considering establishing satellite offices with an insufficient patient base listed as the primary reason. There was a significant difference between the number of additional patients desired based on the age of the orthodontist. More orthodontists reported that patient loads were remaining the same or declining rather than increasing. The present data did not support the premise that the number of patients started was less than that seen in previous studies, suggesting that the low perception of busyness may be related to other factors such as a more recent decline in patient load, improved efficiency, decreased profitability or a combination of these or other factors. The telephone survey differed significantly from the mailed survey questionnaire indicating a possible bias in the survey questionnaire. A geographic maldistribution of orthodontists in Indiana was found. A slight increase in the number of orthodontists over the next decade would be necessary to maintain the present population-to-orthodontist ratio. However, the declining child population, representing the majority of orthodontic patients, will require a reduction in the number of orthodontists to maintain the present adjusted population-to-orthodontist ratio or patient-to orthodontist ratio over the next two decades.Item A Study of Craniofacial Asymmetry in Monozygotic and Dizygotic Twins Using Posteroanterior Radiographs(2002) Russell, Jennifer A.; Hartsfield, James K., Jr.; Everett, Eric T.; Roberts, W. Eugene; Shanks, James C.; Ward, Richard E.This project investigated craniofacial asymmetry in a prospective study among monozygotic (identical) versus dizygotic (fraternal) twins and sibling pairs. Posteroanterior radiographs that had previously been collected were used in this study and the zygosity of the twins had previously been determined. We hypothesized that in this study measuring craniofacial asymmetry there would be a greater concordance between monozygotic twins than between dizygotic twins for each of the variables measured. If there were some genetic component to asymmetry, we would expect to find a greater correlation between monozygotic versus dizygotic twins and sibling pairs since monozygotic twins are genetically identical and the dizygotic twins and siblings share on average fifty percent of their genes. If there are no statistically significant differences between the monozygotic and dizygotic twin correlations as shown from the heritability value, one could conclude that genetic factors are not important in the development of craniofacial asymmetry. This information is clinically significant. If we find that environment plays the predominant role in the development of asymmetry, one would conclude that clinicians should be vigilant about employing a treatment plan that will modify the environment while an asymmetry is developing. Since the zygomatico-frontal sutures and crista galli were found to be relatively symmetrical landmarks in a previous investigation by Harvold, a horizontal axis was constructed through the zygomatico-frontal sutures and a perpendicular vertical axis was constructed through crista galli. Perpendicular distances of ten bilateral structures were measured from the vertical reference line. Two methods of evaluating subjects' head positioning were used and compared. Any subject that was found to have excessive rotation of their head was excluded from the sample. After a preliminary analysis it was found that the horizontal distances were strongly correlated to patient positioning even after subjects determined to have excessive rotation of the head were eliminated from the sample. For this reason, vertical measurements of eight bilateral landmarks were made perpendicular to the reference line constructed through the zygomatico-frontal sutures. Using Statistical Package for the Social Sciences, the magnitude of craniofacial asymmetry was evaluated by calculating the absolute (non-signed) asymmetry values (IL-RI) for each of the ten horizontal and eight vertical variables. The horizontal and vertical variables were evaluated for any directional asymmetry to determine if the right or left side is consistently larger by calculating signed asymmetry values (L-R) for each of the ten horizontal and eight vertical variables. Since the subjects vary in size, relative differences were subsequently calculated. The relative difference was calculated by dividing the right-left absolute difference by half the sum of the right and left measurements [IL-Rlf.5(L+R)]. The relative difference of each of the ten horizontal and eight vertical variables was calculated for each individual. Using SAS software correlation coefficients were calculated for the relative asymmetry values of the monozygotic and dizygotic twin groups for each of the ten horizontal and eight vertical variables. Subsequently heritability values of craniofacial asymmetry were calculated for each of the eighteen variables using the standard formula h2= 2(rMz-rDz). The data revealed that head positioning had significantly affected our horizontal asymmetry values. We found a significant directionality in the horizontal and vertical dimension with the left side being larger horizontally and the right side being larger vertically. However the horizontal asymmetry values must be interpreted with caution as they are significantly affected by the rotation. After analyzing the data collected, the hypothesis was rejected. We were unable to demonstrate a significant difference in correlation values between monozygotic and dizygotic twins/sibling pairs for most craniofacial asymmetry values. The few variables that did show high heritability were in the horizontal plane. The results of the horizontal data must be interpreted with caution due to the significant effect of head rotation. In contrast it was found that vertical asymmetry values were not significantly correlated to rotation and none of these had notable estimates of heritability. These findings suggest that craniofacial asymmetry is more strongly influenced by environmental factors than genetics. This finding supports treatment by clinicians to improve or prevent developing asymmetries. While genetically controlled malformations can often be improved with treatment, environmentally induced malformations may respond well to treatment that changes the faulty developmental environment. Still it will be the capability of the patient to respond to the change in environment (treatment) that will determine the efficacy of the treatment. The interaction of genetic factors with this change in environment at a particular time as represented by the treatment may have a greater influence on the outcome of the treatment than how the problem was produced in the first place. Future studies analyzing asymmetry need to take extreme care in patient positioning and calibration of the x-ray machine, for they may lead to errors which overpower the data already subject to the error of a two-dimensional representation of a three dimensional object. Keeping these technical caveats in mind, future studies should focus on whether there are genetic factors that influence a patient's response (or the difference in response among patients) to the treatment of asymmetry.Item 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.