IU Indianapolis ScholarWorks :: Browsing by Author "Arbuckle, Gordon R."

Browsing by Author "Arbuckle, Gordon R."

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A Cephalometric Skeletal and Dental Analysis of Selected Black American Children in the Indianapolis Area
(1975) McDonald, Jeanne L.; Garner, LaForrest D.; Shanks, James C., Jr.; Arbuckle, Gordon R.; Potter, Rosario H.; Dirlam, James H.
This study was conducted to obtain hard-tissue cephalometric standards for Black American children of twelve years of age. A sample of twenty-four Black American children from the Indianapolis area (thirteen boys and eleven girls} was analyzed and compared with the existing Denver (Caucasian} sample of comparable age. This study was conducted to obtain hard-tissue cephalometric standards for Black American children of twelve years of age. A sample of twenty-four Black American children from the Indianapolis area (thirteen boys and eleven girls} was analyzed and compared with the existing Denver (Caucasian} sample of comparable age. There were only eight measurements that showed no statistical difference from the White standards for both males and females: cranial flexure angle, gonial angle, mandibular plane angle, A-B(OP}, A-B(FH}, A-Pg(OP}, Y-axis angle, and cant of the occlusal plane. There were no significant differences between Black males and Black females. All the linear measurements were significantly larger for the Black sample, except for the chin button (which was significantly smaller in the Blacks}. There was a proportionally larger increase in the mandibular body over the ramus of the mandible in the Black sample; there was a proportionally larger increase in the lower facial height over the upper facial height. In the Black sample, the nasal floor converged upward anteriorly with respect to Frankfort Horizontal. The denture bases and lower face were more protrusive in Blacks; the incisors were more flared and bodily forward. Black patients, therefore, should not be compared to standards set up for Caucasians, but to a set of standards based on normals of their own ethnic group.
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.
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.
Analysis of Bone Remodeling in the Mandibular Condyle of Female Retired-Breeder Rabbits Following Altered Loading
(1992) Hunt, J. Todd; Garetto, Lawrence P.; Roberts, W. Eugene; Arbuckle, Gordon R.; Brown, David T.; Shanks, James C.
Previous studies have associated increased occlusal loads with degenerative changes of the temporomandibular joint (TMJ). The purpose of this study was to analyze effects of increased occlusal loads in adult animals. It was hypothesized that increased functional loading would cause degeneration of the mandibular condyle. Twelve female retired-breeder rabbits (mean age = three years, one month) were divided equally into three experimental groups and one control group. Each of the experimental rabbits received maxillary and mandibular light-cured anterior splints at the beginning of the study to create a bilateral posterior openbite (~2 mm). Theoretically, this should have resulted in increased loads to the TMJ. The first two groups wore the appliances for six and 12 weeks, respectively, prior to euthanasia. The third group wore the appliances for 12 weeks and then had them removed for 12 weeks prior to being euthanized. Fluorescent bone labels were utilized, and the specimens were analyzed histomorphometrically. The cartilage thickness was not statistically different between groups, nor were there any signs of cartilage degeneration. There was a trend, however, toward thinner condylar cartilage in the 12-week group. The six-week group showed significantly less labeled subchondral bone than the control group (0.5 ± 0.1 % versus 2.6 ± 0.3%, respectively; p<.05). The six- and 12-week groups both revealed significantly less periosteal surface label of the condylar neck than the control group (1.5 ± 0.8% and 5.3 ± 1. 7% versus 22.0 ± 3.5%, respectively; p<.05). Likewise, they both showed significantly more label at the cartilage-bone interface (1.0 ± 0.2% and 1.4 ± 0.2% versus 0.4 ± 0.2%, respectively; p<.05) and moderately more label along the trabecular surfaces than the control group. These results indicated that the increased loading of the mandibular condyle initially (at six weeks) depressed remodeling of the subchondral bone and decreased periosteal bone formation. Modeling increased at the cartilage-bone interface and potentially along the trabecular bone surfaces. With continued elevated occlusal loads (at 12 weeks), modeling still was quite active at the cartilage-bone interface and on the trabecular surfaces. Periosteal surface modeling remained depressed compared to the control group, but remodeling in the subchondral bone region increased to that of the control group. The 12/12-week group tended to show findings similar to the control group. This suggests that once loading was returned to normal, the condyle also returned toward preexperimental physiologic conditions. Although this study did not show the obvious degenerative changes one typically equates with osteoarthrosis, the elevated modeling at the cartilage-bone interface following increased joint loads was consistent with the early degenerative changes observed by Radin et al. in their joint-loading model. However, the rapid osseous changes seen in this study refute the theory that the adult TMJ is unable to adapt to altered functional loading.
Assessment of Osteoporosis Risk Factors in the Female Dental Patient: A Demographic Study
(1996) Becker, Angela R.; Garetto, Lawrence P.; Arbuckle, Gordon R.; Clark, David B.; Roberts, W. Eugene; Shanks, James C.
Osteoporosis has become a major public health problem as the size of the elderly population has continued to increase. While it is unclear as to the exact relationship between systemic bone disease and the craniofacial skeleton, the dental implications of osteoporosis could include dental implant failure, decreased residual ridge height, and unsuccessful orthodontics or oral surgery procedures. While these concerns remain speculative, it is important for dentists to recognize patients who exhibit high risk for osteoporosis. The purpose of this study was to evaluate risk factors for osteoporosis exhibited by female dental patients at Indiana University School of Dentistry and to assess this risk among the various dental specialty subpopulations. Based on general population averages, we hypothesized that approximately 20 percent of the female patients were at high risk for osteoporosis and that differences would be found among the various dental subpopulations. We also hypothesized that the number of teeth present would decrease as the risk for osteoporosis increased. A 12 question survey assessment tool was devised and administered to 220 female dental patients 18 years and older. This survey asked the patient to report selected vital statistics, menstrual status, and other aspects of lifestyle. The average overall age of the patients was 48.2±1.1 years. Of the 220 subjects, 34 percent exhibited serious risk factors for osteoporosis. The orthodontic subpopulation contained the fewest number of patients at high risk for osteoporosis (6 percent). However, they were also the youngest group (33.9±2.0). The complete denture subpopulation had the highest number of patients at high risk for osteoporosis (53 percent) and was the oldest (60.0±2.3). There was a trend for number of teeth to decrease as the risk for osteoporosis and age increased. We also found that in women who had taken hormone replacement therapy for at least five years, there was no association between number of teeth and years postmenopause. However, women who had very little or no hormone replacement therapy, there was a strong correlation for number of teeth retained to decrease as the number of years postmenopause increased (r=0.6). We concluded that there is a difference in dental subpopulations for osteoporosis risk. The clinical implications are that osteoporosis risk is much higher in specific classes of dental patients. Clinicians treating these patients must recognize the need to refer high risk patients for appropriate medical assessment.
Bone Remodeling and Strain Variation Following Altered Mandibular Condyle Loading in Retired Breeder Rabbits
(1993) Puntillo, Anthony M.; Garetto, Lawrence P.; Roberts, W. Eugene; Arbuckle, Gordon R.; Chen, Jie; Burr, David B.
Several investigators have demonstrated modeling of the mandibular condyle foil following a change in load. A recent study evaluated the effect of age on the ability of the condyle to adapt to such a change. The present study explored the early changes in the mandibular condyles of retired breeder rabbits following an alteration in load, and attempted to quantify this load. Twelve female retired breeder New Zealand white rabbits were divided into four equal groups. Under general anesthesia strain gauges were placed on the lateral inferior body of the mandible bilaterally in two of the groups. Two days post-surgery acrylic splints were placed on the anterior teeth (resulting in a posterior open bite) of one the strain gauge groups and one group that did not receive strain gauges. The splints were maintained for 26 days. A control group received neither strain gauges nor splints. Intravital bone labels were administered to all groups to allow for histomorphometric analysis of condylar modeling and remodeling. In addition, principal strain measurements were recorded pre- and post-splint placement. The histomorphometric findings revealed a significant (p<.03) decrease in the subcondylar space of animals that received splints. Splinted animals also showed a significant increase in labeled surface area (p<.02) and in volume percent label (p<.05) of the trabeculae in the condylar neck region. In addition, surgical placement of the strain gauges significantly (p<.05) decreased the labeling of the periosteal surface in the neck region. The strain gauges proved functional in most rabbits for only a few days and registered large variations and no discernible differences in average maximum microstrain, and average change in microstrain. It was concluded from these results that an incisal prematurity (causing a posterior openbite), 26 days in duration, caused an increase functional load on the condyle. This load resulted in an increase in trabecular label and decrease in porosity of the subchondral plate. The decreased subcondylar space is possibly an indication of stiffening in this region. A stiffening of this nature has been suggested in previous studies to be a precursor to osteoarthritic degeneration.
The Effect of Hypergravity (2g) on Osteoblast Precursor Cells in the Periodontal Ligament of the Rat
(1994) Becker, Robert F.; Garetto, Lawrence P.; Arbuckle, Gordon R.; Hancock, Everett B.; Katona, Thomas R.; Roberts, W. Eugene
The effect of weightlessness on bone and osteoblast precursor cells has previously been studied. A marked decrease in bone formation, an increase in less differentiated committed osteogenic cells (A+A'), and a decrease in preosteoblast cells (C+D) was noted. To date, the effect of hypergravity (2g) on osteoblast histogenesis has not been studied in vivo. In vitro studies using nonphysiologic high levels of gravity (20,40g) have shown an increased proliferation of cloned osteoblast-like cells. The purpose of the present study was to evaluate the effect of hypergravity (2g) on osteoblast histogenesis in the rat periodontal ligament (PDL), on the width of the mesial PDL, and on the percentage of forming bone surface on the mesial side of the tooth. Twenty male Wistar rats (SPF: Harlan Sprague Dawley) were randomly assigned to the centrifuge (experimental) or to the stationary (control) group. The experimental group was centrifuged for 14 days at 2g and the stationary group was housed in identical cages in the centrifuge room. The PDL of the mesial and distal surface of the mesial root of the first maxillary molar was analyzed microscopically 100 μm above and below the midroot area. Nuclear volume morphometry was used to classify periodontal ligament cells as: L cells (<40 μm3), A+A' cells (40-79 μm3), B cells (80-119 μm3), C cells (120-169 μm3), and D cells (>170 μm3). The percent of forming bone surface on the mesial side and the width of the PDL were also measured. A 2x2 factorial ANOVA with repeat measures revealed a significant (p < 0.05) decrease in the C cell population and a nearly significant (p < 0.06) increase in the A+A' cell population in the centrifuge group. Comparing bone surfaces, the forming surface had a significant (p < 0.01) increase in the C and D cell populations, a significant (p < 0.01) decrease in the L and A+A' cell populations, and a significant (p < 0.05) decrease in the B cell population. The stationary group weighed significantly (p < 0.01) more than the centrifuge group post-experiment. And an unpaired t-test revealed a nearly significant (p < 0.06) increase in the percent forming bone surface on the mesial side of the maxillary first molar and no significant difference in mesial PDL width. The results showed that the centrifuge group had a trend toward a block in preosteoblast formation. This is similar to that seen with hypogravity. However, it cannot be concluded at this time if this is a direct gravitational effect or related to other factors such as physiological response to stress. Physical stress has been suggested as a potential mechanism for the observed decrease in weight seen in centrifuged animal, while the PDL width does not seem to be affected by gravitational forces, and thus may not be a sensitive marker to osteoblast differentiation inhibition. Finally, the reason for the increase in forming bone surface in the centrifuged group is unclear.
Evaluation of a Hypergravitational Load on Mandibular Condyle Growth and Osteoblast Differentiation
(1994) Martines, Lúis E.; Roberts, W. Eugene; Garetto, Lawrence P.; Arbuckle, Gordon R.; Hohlt, William F.; Coghlan, Charles Y.; Chen, Jie
Previous studies have shown that mandibular condyle growth and development are stimulated by mechanical loading. Gravity acts as a baseline mechanical load to which every living being is exposed. The purpose of this study was to evaluate the effects of a two-week constant hypergravity load (2g) on: (1) condylar cartilage and bone parameters, and (2) osteoblast differentiation in condyle primary spongiosa. Twenty 60-day-old rats were divided into centrifuged/experimental (Expt.) and stationary/control (Cont.) groups. Ten rats were subjected to two weeks of centrifugation at the NASA Ames Research Center to simulate an increased induced-gravitational field. Comparison of Expt. and Cont. animals by Student's t-test revealed increased cartilage volume and decreased bone volume when determined as a percent of total condylar tissue (data expressed as Volume percent , mean±SD, *p< 05). Expt.: Cartilage: 42.3±7.6%; Bone: 36.7±2.9% Cont.: Cartilage: 35.2±7.8%; Bone: 40.0±3.9% The same pattern occurred when cartilage and bone volumes were expressed as a percent of the hard tissue fraction of the condyle. While there was a slight increase in the nonosteogenic cells, there were no differences in osteogenic precursor cells. Similarly, there were no differences between groups in volumes of cortical and trabecular bone, condylar perimeter, and cartilage thickness. Evaluation of condylar head shape expressed as a percent of the condylar field showed no significant differences between groups. This is in agreement with the lack of significance observed when comparing the total perimeter surface of the condylar cartilage and bone. However, a subjective evaluation of condylar head shape showed that 90 percent of the condylar heads of the Experimental group had a somewhat round shape, while 70 percent of the condylar heads of the Control group were shaped in the resemblance of a "mushroom." These results suggest that the mandibular condyle adapted to two weeks of hypergravity by increasing cartilage volume at the expense of bone volume. The rise in cartilage volume appeared to result from an increase in the resting layer of cartilage cells. The subjective visual difference on condylar head shape and the wider range of condylar head sizes in the Experimental group may reflect that rather than growth modification, mandibular condyles adapted to hypergravity within a range of developmental responses. No differences in osteoblast precursor cell differentiation or condylar size were apparent at this time. The increase in the nonosteogenic cell compartments (L and B cells) needs further evaluation. The mandibular condyle appears sensitive to both positive and negative gravitational variation. However, it may not be as sensitive to hypergravity as it is to hypogravity. The fact that no significant correlations were found in the Experimental animals between their significant weight loss or lack of weight gain during the experimental period, and variables such as linear cartilage thickness, fractional volumes of cartilage and bone over the condylar hard tissue fraction, and condylar perimeter, points toward the fact that hypergravity probably did not have a significant effect on mandibular condyle growth. It is also very likely that functional loads are more important than postural loads on the growth and development of the mandibular condyle. In fact, the functional load generated by the masticatory muscles may actually not have allowed the load of the 2g hypergravitational to be fully expressed on the mandibular condyles. This leads to speculations whether the mandibular condyles of the rats centrifuged in the 2g hypergravitational field were or were not trully exposed to hypergravity.
Evaluation of Tensile Bond Strength of a Fluoride-Releasing Resin Adhesive with Ceramic Brackets
(1991) Lehman, David Alan; Roberts, W. Eugene; Moore, B. Keith; Shanks, James C.; Arbuckle, Gordon R.; Miller, James R.
The increased attention to the esthetics of orthodontic appliances has led to the popularity of ceramic brackets in the last decade. Although the bonding of ceramic brackets has become predictably successful, the extreme brittleness of ceramics coupled with higher bond strengths has caused significant clinical problems in debonding and risk of enamel damage. This study evaluated an experimental bonding resin with different levels of fluoride concentration, linking the therapeutic property of long-term fluoride release to the benefit of decreased bond strength to ceramic brackets. Four groups of 40 Transcend™ ceramic brackets each were bonded to bovine teeth, using 0, 3, 6, and 12 percent fluoride concentrations. At two weeks, one-half of each group was tested for tensile bond strength in an lnstron machine. The remaining half were tested at six months. In the groups broken at two weeks, the bond strength peaked around 6 percent fluoride, but the three top groups were not significantly different. In the groups tested at six months, peak strength was observed at 3 percent fluoride and was significantly greater than the others. The overall mean at six months than at two weeks. The study found bond strength values in the range of 25-50 kg/cm2. Although minimum values have not been established, the low values reported in this study are likely to be within acceptable clinical limits. Following debonding, the mode of bond failure was determined by viewing enamel specimens and bracket bases under a light microscope. In all but one group, 95 percent of the bond failure occurred at the bracket base/adhesive interface. No bracket failure occurred and no enamel damage could be observed under the light microscope. In a parallel study of physical properties, Knoop hardness was measured at one hour, 24 hours, and six months, and compressive strength was tested at one week and six months. While physical properties generally decreased over the period of study, bond strength was significantly greater in the six-month group. The results of this study regarding the correlation of these properties to bond strength is inconclusive. In addition, results of fluoride-release data by SISCO Inc. indicate that the 12 percent group was shown to release greater than 10 μg/g/day at six months. This was comparable to amounts known to have the clinical benefit of reducing demineralization, and equaled or exceeded other commercially available fluoride-releasing adhesives. The results of this study indicate that a fluoride-releasing resin can release clinically significant amounts of fluoride ions, and still have adequate bond strength.
Evaluation of Tensile Bond Strength of Glass Ionomer Cements for Orthodontic Bonding
(1992) Sprayberry, W. Ray; Katona, Thomas R.; Arbuckle, Gordon R.; Moore, B. Keith; Roberts, W. Eugene; Shanks, James C.
Glass ionomer cements offer advantages over conventional composite resins when used for orthodontic bonding. These include chemical bonding to enamel, fluoride release, and ease of removal from enamel upon debonding. This study evaluated the tensile bond strengths of three Type I (luting) and three Type II (restorative) glass ionomer cements when used to bond a standard stainless steel orthodontic bracket to teeth. Bovine incisors were divided into six groups of 20 each. Each group had brackets bonded with one of the following glass ionomer cements: SHOFU ® Glasionomer Type I, Fuji I™, Ketac ®-cem, SHOFU ® Glasionomer Type II, Fuji II ™, and Ketac®-fil. A new regimen of specimen preparation was used in an attempt to align the brackets so that true tensile forces could be generated at testing. After the specimens were prepared, they were stored in room temperature water for two weeks, thermocycled, returned to water storage for two additional weeks, and then tested in tension on an lnstron Testing Machine until bond failure occurred. The type bond failure was determined with light microscopic analysis of the debonded bracket bases. The finite element method was used to further evaluate the bracket/adhesive/enamel complex with varying angulation of force application at debonding. The mean tensile bond strength value of 0.82 ± 0.36 MPa for SHOFU® Glasionomer Type I was significantly less (p<0.05) than the values of 1.13 ± 0.33 MPa for Ketac®-cem and 1.26 ± 0.40 MPa for Fuji I™. For the Type II glass ionomer cements, the mean tensile bond strengths of 2.00 ± 0.28 MPa for Ketac®-fil and 1.97 ± 0.29 MPa for Fuji II™ were significantly greater (p<0.05) than the 0.95 ± 0.35 MPa for SHOFU® Glasionomer Type II. The Ketac® and Fuji™ Type II cements developed bond strengths which were significantly greater (p<0.0001) than the Type I cements. Light microscopic analysis of bond failure revealed a high degree of within group variability. As a result, trends relating failure mode to tensile bond strength could not be established. The finite element method study showed that even a slight alteration in angulation of the force applied to the bracket greatly affected the maximum principal stress developed in the adhesive layer. An increase in maximum principal stress of ≈1,000 MPa was seen when a true tensile debonding force (0° offset) was adjusted to 12° of offset. The results of this study indicate that Type II glass ionomers have potential for clinical orthodontic use and that special attention should be given to the angulation of force applied to brackets in laboratory bonding studies.

Browsing by Author "Arbuckle, Gordon R."

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