Teaching and Research
Teaching — Graduate students are involved as teaching assistants in the DMD curriculum during their second and third year. They take an active part in all three components of the courses by preparing some lectures, directing small group discussion and providing clinical coverage for the dental students. Such experience is limited to the orthodontic component of the DMD curriculum and students receive a stipend for this effort. This stipend amounts to $2175 over an 11 month period each year.
Research — Graduate students must successfully investigate and defend an independent research project before they graduate. They are encouraged to identify a topic and select an advisor by the completion of their first year. Students are encouraged to first pursue their natural sense of curiosity, as there are many resources available within the College, Medical Center and Land-grant University campus. Award-winning research is being conducted in our Program within the College, and students are encouraged to prepare their thesis in a manuscript for publication.
Dr. Billy Millay, Class of 2006
Title: "A Regional Comparison of Hypodontia in Kentucky and Mexico"
The prevalence of hypodontia in the United States has ranged between 2.9% and 10%. Multiple genetic and non-genetic factors have been linked to hypodontia. Recently dentists and orthodontists from southeastern Kentucky have reported higher rates of hypodontia. These reports have led to recent studies that have demonstrated a relatively higher prevalence of hypodontia in Kentucky; 7.9% to 13.3%.
Objective: To compare the prevalence and severity of hypodontia in Kentucky to the geographically distant and racially different area of Mexico City.
Methods: 996 consecutively treated patients from the University of Kentucky orthodontic clinic(514) and the orthodontic clinic at the Universidad Nacional Autonomo de Mexico(482) were examined in this retrospective, descriptive study. Panoramic radiographs were examined for missing permanent teeth. The study included males and females ages 6 to 17 years old. Third molars were not included. Patients with syndromes and dento-alveolar clefts were excluded. Patient records were used to determine that the missing teeth were not absent due to extractions or avulsions. Molar and skeletal classification was recorded as well.
Results: The percentage of patients with missing teeth was 5.06 % of Kentucky patients and 4.34% of Mexico patients. According to Chi-square test (P = .59), there was no significant difference between the two groups in the number of patients who had at least one missing tooth. The severity, however, was very different between the two groups. The percentage of patients from Kentucky missing 5 or more teeth was 19.25% and the percentage from Mexico was 0% demonstrating a greater severity of hypodontia in Kentucky (p=.0561).
Conclusions: This study demonstrated a similar prevalence of hypodontia in Mexico and Kentucky. Kentucky, however, has a greater severity of hypodontia than Mexico.
Dr. Steve Parle, Class of 2006
Title: “Facial Assessment of Class II ABO Certification Cases”
Class II patients comprise a large component of the orthodontic patient population and pose significant challenges for achieving excellent treatment outcomes.
Objectives: The purpose of this study is to evaluate the soft-tissue and skeletal profile changes associated with non-surgical treatment of skeletal Class II patients using comparative cephalometric analysis. The study group includes Class II, past American Board of Orthodontics patients whose treatment has met the criteria for certification, indicating complete Class II dental correction.
Methods: 29 Class II ABO patients (mean pre-treatment age: 11.9 yrs., post-treatment age: 15.2 yrs.) lateral cephalograms were digitized and measured using Dolphin Imaging 9.0® software. Various pre- and post-treatment soft-tissue and skeletal measurements were calculated and analyzed for statistically significant profile changes. Treatment results were compared with normative data to determine improvement of cephalometric parameters.
Results: Statistically significant measurements include SNA, ANB, facial convexity, and facial divergence (p<.05). 13.8% of patients showed unfavorable soft-tissue profile changes during the course of treatment as determined by facial convexity and divergence, while 75.9% showed improvement.
Conclusions: The majority of ABO Class II case reports showed improvement in skeletal and soft-tissue measurements. Patients who showed unfavorable profile outcomes are under further study and will be discussed.
Dr. Judah Garfinkle, Class of 2005
Title: "Evaluation of Orthodontic Mini-Implant Anchorage in Adolescent Premolar Extraction Therapy"
The application of orthodontic mini-implants (OMIs) has recently increased considerably. Current clinical recommendations are based largely on case reports and animal studies, leaving many important issues unresolved.
Objectives: The aim of this study was to evaluate OMIs in relation to success rate, positional stability, and patient response, while providing anchorage for the closure of premolar extraction space in an adolescent population. Success rate would be evaluated in relation to the latency period, placement technique, and placement location. Success was defined as any OMI that provided anchorage until adequate tooth movement had occurred.
Methods: Eligible patients (n = 13, 8 female, 5 male with average age of 14y10m) received OMIs (n = 82 measuring 1.6mm-diameter/6mm-long fabricated/donated by OsteoMed Corporation, Addison, TX) in the buccal alveoli (one unloaded-OMI/one loaded-OMI per quadrant). The right or left side was randomly selected for early-loading (average of 1.6 days post insertion) with up to 250grams of direct force, with the contralateral side being delayed-loaded (average of 34 days post insertion). Serial impressions, clinical observations and orthodontic maintenance were carried out at 3-5 week intervals until adequate space closure had occurred.
Results: The overall success rate of the OMIs was 70.73%. As calculated with a mixed model analysis to account for the dependence among implants from the same subject, there was no significant difference between the early-loaded (80.0%) and the delayed-loaded (80.95%) OMIs. The combined loaded-OMI success rate (80.49%) was significantly greater than that of the unloaded-OMI success rate (60.98%). OMIs placed in the maxilla (72.92%) had a significantly greater success rate than the OMIs in the mandible (67.65%). OMIs placed with a cortical notching protocol (78.85%) were significantly more successful than OMIs placed with the direct protocol (56.67%). Response to the patient surveys indicated that the insertion, use, and removal of OMIs were well tolerated procedures. Conclusions: The use of OMIs provided a predictable, effective, and well tolerated anchorage source in this adolescent population. Neither the timing of force application nor the force itself precipitated failure of the OMIs. Orthodontic forces can be applied immediately to OMIs. The size of the OMI, various anatomic and behavioral conditions unique to adolescents, and a clinical learning curve (both surgical and orthodontic), all impacted the overall success rate in this preliminary study.
Dr. Blaine Hansen, Class of 2005
Title: "Skeletal, Dental and Soft Tissue Cephalometric Values in Non-Caucasian Mexican Adolescents
It is known that there are differences in craniofacial morphology among racial and ethnic groups. Americans of Mexican descent make up an increasing percentage of the United States population. Yet historically little has been studied with regards to cephalometrics and influences on the craniofacial complex within the Mexican population.
Objectives: The aim of this study was to cephalometrically analyze non-Caucasian Mexican adolescents to determine skeletal, dental and soft tissue contributions to the facial profile. The aim of this study was not to discriminate between the various subpopulations of Mexican patients, but rather to take a broad cross section of non-Caucasian Mexicans that present in an orthodontic office and compare them to known Caucasian normative values.
A second component of the study will compare soft tissue values from the Mexican males and females to previously reported values for Caucasian and African American adolescents.
Methods: Lateral head films of 200 age and sex matched non-Caucasian Mexicans were studied. Comparisons were made with Caucasian norms by age: 10, 11, 12 and 13 year old females; 11, 12, 13, 14 year old males (25 films per age group). Selected cephalometric variables were chosen for comparison and significant differences determined (P<.05) Age groups for the Mexican males and Mexican females were then combined and compared to soft tissue values for Caucasian and African American adolescents.
Results: Although the Mexican and Caucasian populations shared many similarities there were several important differences. Mexican subjects showed more protrusive lips, teeth and maxilla. Mexican subjects also had an increased ANB angle, maxillo-mandibular differential and generally an increased anterior face height coupled with an increased mandibular plane angle. A comparison between the ages and sexes showed similar trends with some differences. Generally the African American had thicker tissues and more protrusive lips followed by the Mexican and Caucasian respectively.
Conclusions: This study shows that there are significant differences in non-Caucasian Mexican, Caucasian and African American populations for a large number of the variables tested. This study provides a foundation upon which practitioners can diagnose and make treatment planning decisions that are race and age appropriate for their patients.
Dr. Meridith Long, Class of 2005
Title: "The Effects Of Dietary Liquids On The Elastic Properties Of Orthodontic Elastics"
Intraoral elastics are frequently used to deliver force during orthodontic treatment. We hypothesize that dietary liquids may reduce the force exerted by elastics.
Objectives: Our purpose is to compare the forces exerted by latex and non-latex elastics in the presence of dietary liquids and a water control group.
Methods: Latex and non-latex ¼" x 4 oz. elastics from two manufacturers, GAC International (Bohemia, NY) and Masel (Bristol, PA), were stretched 19 mm, tested dry, and immersed in 37o C distilled water. At 15 min, 30 min, 1, 3, 6, 12, and 24 hours, each member of a set of elastics (n = 17) was briefly removed from solution, and its restoring force at 19 mm extension measured with a mechanical testing machine (Model TTC; Instron Corporation; Canton, MA). Control and test groups (each n = 17) were maintained in either water or test solution except during testing. For five minutes before each test measurement, the test elastics were immersed in either Coca-Cola (Atlanta, GA), 5% acetic acid, or 75% ethanol - each maintained at 25° C.
Results: Forces exerted by non-latex elastics were not significantly affected by solution type 6 h or earlier, but at 12 h., solution type had a significant effect (2-factor-ANOVA; F = 12.54; P < 0.001). For both GAC and Masel non-latex elastics, acetic acid and ethanol produced significantly lower forces than water (Tukey HSD test, P < 0.001). Solution type had a significant effect on latex elastics at 30 min (F = 7.18; P < 0.001) and thereafter. GAC elastics in acetic acid and Masel elastics in cola, acetic acid, or ethanol each exhibited significantly lower forces (Tukey HSD test, P < 0.001) than controls in water.
Conclusions: Dietary liquids can degrade forces exerted by both latex and non-latex elastics. Degradation occurs earlier in latex elastics.
Dr. Wade Housewright, Class of 2004
Title: "Tooth Agenesis In Colorado And Kentucky Orthodontic And Pediatric Dental Patients: A Comparison"
Reported prevalence of hypodontia in the US ranges between 2.9% and 13%. Genetic and non-genetic etiologies have been implicated. Regional trends are unknown. Increased prevalence and severity of hypodontia in central and southeastern Kentucky were recently reported. The purpose of this retrospective study was to compare the prevalence and severity of hypodontia in Kentucky to geographically distant Colorado. Records of 2269 orthodontic and pediatric dental patients in the University of Kentucky (UKO, UKP) and private practices in central Kentucky (LXO, LXP) and Colorado (CCO, CCP) were examined. Panoramic radiographs of patients 6 to 17 years old were examined for missing permanent teeth. Third molars, extractions and avulsions were not included. Patients with syndromes or clefts were excluded. Prevalence varied between the groups: CCO = 8.63%, CCP = 5.25%, LXO = 5.50%, LXP = 7.87%, UKO = 13.33%, UKP = 7.94%. Chi-square analyses showed UKO to have significantly higher prevalence than any other group. ANOVA and Fisher's LSD tests showed severity of hypodontia was significantly higher in University of Kentucky patients primarily due to the high degree of severity found in UKO population (3.74 missing teeth/affected individual). Conclusion: Prevalence and severity of hypodontia in University of Kentucky orthodontic patients is significantly higher than in Colorado or Kentucky private practices.
Dr. Susan Nordstrom, Class of 2004
Title: "Salivary Biofilm Contamination After Application Of Orthodontic Self-Etching Primer"
Abstract: The purpose was to investigate the effect of saliva/biofilm contamination on bond strength of an orthodontic self-etching primer (SEP)/adhesive system. Methods: Prior to bonding with orthodontic cement (Transbond XT; 3M Unitek), we randomly assigned 120 SEP-coated (Transbond Plus SEP, 3M Unitek) bovine enamel sections into four groups: 1) no saliva (control); 2) wet saliva; 3) evaporated saliva; or 4) rinsed and dried saliva. Using a mechanical testing machine to fracture the specimens at .5 mm/min, we calculated the bond strength (MPa) and at 63x, assessed the adhesive remnant index. Results: Examinations revealed that nearly all the specimens fractured nearly parallel to the enamel surface. The mean bond strengths (MPa) were: Grp.1. 24.8 ± 8.3; Grp.2. 16.7 ± 8.3; Grp. 3. 16.9 ± 9.9; and Grp.4. 21.0 ± 7.7. ANOVA showed that at least one treatment had a significant effect on bond strength (F = 5.93; p < 0.0001). Tukey HSD test ranked the groups, descending: 1, 4, 3, 2. Conclusions: Neither drying the saliva nor rinsing and drying the saliva restored the enamel bond strength to that of uncontaminated specimens. Even the saliva-contaminated specimens had enamel bond strengths that may be sufficient for retention of orthodontic brackets.
Dr. Michael Cherubini, Class of 2003
Title: "Rofecoxib, A Cyclooxygenase-2 Selective Inhibitor, and its Analgesic Efficacy in Orthodontically Induced Pain: A Randomized, Controlled Trial"
Abstract: This study aimed to determine the analgesic efficacy of rofecoxib, establish that cyclooxygenase-2 is involved in the pathophysiology, and evaluate the influence of psychological functioning on orthodontically induced pain. This randomized, double-masked, placebo and active-comparator controlled study compared the preemptive analgesic effects of rofecoxib 50 mg. ibuprofen 400 mg, and a placebo in 99 healthy volunteers after the placement of unilateral, elastomeric separators. Subjects took one dose of a randomly assigned medication and monitored their pain over a 24-hour period. Measurements included pain intensity, pain relief, global efficacy, and the pain patient profile. Controlling for gender, age , weight, and psychological variables, the placebo group had significantly higher pain intensity scores than either of the two active drugs for most of the time points in the trial. There were no differences in subjects' responses for pain intensity between the two active drugs. The psychological pain profiles indicated that the discomfort felt during the trial period was not due to abnormal levels of depression, anxiety, or somatization. Therefore, for this orthodontic pain model the preemptive administration of rofecoxib was efficacious, cyclooxygenase-2 derived prostanoids play a primary role in its pathophysiology, and differences in psychological functioning were not accountable for the differences in pain intensity and pain relief.
Dr. Ross Russell, Class of 2003
Title: "A Self-etching Primer, Saliva Contamination, and Bond Strength of Orthodontic Brackets"
Abstract: Objective: The purpose of this study was to assess the effects of saliva contamination on the bond strength of orthodontic brackets using a self-etching primer (SEP)/resin cement system. Methods: We randomly assigned 61 freshly extracted bovine incisors into three groups:
1) uncontaminated controls, 2) saliva contaminated before SEP application, and 3) saliva contaminated after SEP application but before cementing the bracket. We polished each tooth with pumice, rinsed it, and blotted it with a cotton roll. After applying the SEP (Transbond™ Plus Self Etching Primer, 3M Unitek; Moravia, CA; USA) we bonded metal brackets with an orthodontic cement (Transbond™ XT; 3M Unitek) using <~ 250 g finger pressure for 3 s. We removed excess cement with a sharp explorer and light cured for 20 s. We contaminated the bond site with 1.0 μof human saliva. After storage in distilled water for 24-36 h, we used a tiltable mounting vice enabling alignment of a wire loop along a force vector parallel to the bonded surface. Using a mechanical testing machine, we sheared the bracket at 1.0 mm/min. We measured the force (N) to fracture the bond, calculated the bond strength (MPa), and at 20x magnification, assessed the adhesive remnant index (ARI).
Results: The mean shear bond strengths were: group 1: 9.68 ± 1.18 MPa (n=20); group 2 10.18 ± 1.45 MPa (n=23); and group 3: 4.98 ± 2.39 MPa (n=18). ANOVA showed that at least one treatment had a significant effect on bond strength (F=53.79; p < 0.0001). The mean bond strength for group 3 was significantly lower than that of the controls and group 2 (Tukey HSD test; p< 0.05).
Conclusions: With this system, saliva contamination reduced bond strength only when it occurred after SEP application.
Dr. Flora Chen, Class of 2002
Title: "Prevalence of hypodontia in rural southeastern Kentucky Appalachian region"
Abstract: Hypodontia, defined as the developmental absence of one or more teeth, has been studied for years. Recently, dentists have noted a disproportionate prevalence of tooth agenesis in the rural southeastern Kentucky Appalachian (SEKA) populations. The purpose of this paper is to determine the prevalence and degree of severity of hypodontia in rural SEKA region compared to the urban central Kentucky area (UK). Material and methods: A total of 1260 consecutively treated patients from four different clinics in urban central and rural SEKA were examined in this retrospective, descriptive study. The records originated from both orthodontic and pediatric dentistry clinics in the two areas. Diagnostic records and radiographs were examined. Boys and girls ages 6 to 17 years were included. The third molars were not considered. Patients with reported syndromes were excluded. Results suggest the percentage of patients with missing teeth did not vary across the 4 groups (13.33% UK Ortho, 7.94% UK Pedo, 11.11% SEKA Ortho, 10.16% SEKA Pedo). The average number of missing teeth per person was the highest in the urban central Kentucky orthodontic clinic, averaging 3.74 teeth per affected child. In the SEKA area, females have a much higher prevalence of hypodontia than males (13.29% vs 7.39%). This study demonstrated the average prevalence of hypodontia (10.63%) is high compared to previous reported studies.
Dr. Brian Hardy, Class of 2002
Title: "Interleukin-1 Genotypes and the Association Between Adult Orthodontic Patients and Apical Root Resorption"
Abstract: It is estimated that 25% of all orthodontic patients are adults. Several lines of evidence suggest that adult patients may respond differently than adolescents to the conventional regimen of full banded orthodontic treatment. As bone apposition and resorption occurs, a continuous state of inflammation is present. A cytokine marker, Interleukin-1 (IL-1). is a key regulator of the host response to microbial infection and inflammation. IL-1-beta (IL1-B) is a pro-inflammatory cytokine that has been implicated as a potential marker for the pathogenesis of periodontal tissue destruction in a variety of studies. Potentially magnifying the tissue destruction due to the normal host response is a genetic polymorphism that results in hyper-secretion of IL1-B. The purpose of this study was to determine if the presence of this polymorphism in the gene that encodes IL1-B is associated with apical root resorption in adult orthodontic patients. Materials and methods: Records that were used in this randomized, retrospective study included pre- and post-treatment panoramic radiographs of 30 adult orthodontic patients for whom active orthodontic treatment was complete. Cheek swabs were accomplished on all patients to gather the genetic material to run the polymerase chain reaction (PCR) analysis screening. The results showed no significance (P-value≤0.05) between genders (P-value range 0.3337 - 0.9622) or patients that were genotype positive or negative (P-value range 0.0528 - 0.8287). Of the 30 patients in the study, 12 tested positive for the IL1-B genotype (40%).
Dr. Spyros Bobetsis, Class of 2001
Title: Interleukin-1 beta in gingival crevicular fluid during orthodontic tooth movement and its association with Interleukin-1 genotype.
Abstract: The purpose of this investigation was to evaluate the presence of Interleukin-1 beta (IL-1b) in the gingival crevicular fluid (GCF) during initial orthodontic tooth movement and to establish a potential correlation with the IL-1 genotype. Thirty adolescent patients age 9 to 14 participated in the study. The study protocol required three visits. At the initial visit each patient received a periodontal prophylaxis, thorough oral hygiene instructions, and instructions to use a chlorhexidine rinse. Two weeks later separators were placed mesial and distal of the upper and lower first molars unilaterally. The other side acted as control. The third visit was 24 hours later. At each visit GCF samples were collected from all four first molars using periopaper strips and were analyzed for IL-1b levels by ELISA. A saliva sample was obtained to determine the IL-1 genotype. Our results show that IL-1b levels in the GCF decrease after periodontal prophylaxis and increase in response to mechanically induced orthodontic forces. The prevalence of the IL-1 genotype was found to be 30%. Furthermore, the results tend to support the idea that the IL-1 genotype is associated with increased phenotypic expression of IL-1b in the GCF in response to microbial and mechanical induced inflammation.
Dr. Jeff Hendrix, D.D.S, Class of 2001
Title: Relationships between cervical vertebrae and mandibular canine developmental stages at starting age of peak height velocity for the purpose of skeletal maturation evaluation.
Abstract: The purpose of the present investigation is threefold: (1) To determine the relationship between the developmental stages of the mandibular canine and the lateral profiles of the second, third, fourth, fifth, and sixth cervical vertebrae at starting age of peak height velocity; (2) To examine the intra-examiner and inter-examiner reliability in rating formation stages from dental radiographs, and; (3) To establish a method to stage and predict adolescent growth potential using standard orthodontic diagnostic radiographs. Overall, assessment of cervical vertebrae and mandibular canine stages utilizing the inspectional technique is extremely reliable. The association between starting age of peak height velocity versus mandibular canine stage is significant only when both sexes are considered together. The association between starting age of peak height velocity versus cervical vertebrae stage is significant for females only. No significant association exists between starting age of peak height velocity versus the combined "score" of cervical vertebrae and mandibular canine stage reported at that time. No significant association exists between the cervical vertebrae stage at starting age of peak height velocity and the mandibular canine stage at starting age of peak height velocity. No valid prediction technique is currently feasible given the limited association between these two variables.
Dr. Ulla Katriina Crouse, Class of 2001
PhD Disseration, Department of Physiology
Title: "Naso-Respiratory Function in Children and Adults."
Abstract: The effects of impaired nasal breathing on craniofacial growth and the development of the dentition have been studied for decades. Since the growth pattern of the dentofacial complex is affected by multiple genetic and environmental factors, the debate over interaction between growth and breathing mode is likely to continue until all these variables and their correlations are determined. Therefore, the purpose of this study was to define characteristics of the normal naso-respiratory function in children and in adults, and to study how naso-respiratory function relates to age and to other factors such as gender, relative body mass, smoking, and history of upper airway diseases.
For this project, the changes in nasal resistance, minimum nasal cross-sectional area, and airflow rate and oral-nasal pressure were followed longitudinally in a group of children by means of posterior rhinomanometry. The characteristics of mature naso-respiratory function were observed in a cross-sectional sample of adults, and the differences between children and adults were compared.
This normative study demonstrated age-specific means for 9-13 year old children. However, another confounding factor for the diagnosis of prolonged nasal impairment was uncovered: Overall nasal resistance decreased with age in children, but a significant transient decrease in nasal patency was seen in pre-adolescent children. In adults, the airway patency was shown to stay stable from 16 years on. Adult males are expected to have slightly higher resistance and slightly smaller airway size than females do, even though the gender difference was non-significant in children. Nasal airflow rate was found to increase with increasing body mass index. A history of nasal and other upper respiratory symptoms should not affect rhinomanometric evaluation if measurements are done during asymptomatic periods.
This study suggests that signs of nasal impairment may occur periodically in pre-adolescent children. In order to make a correct diagnosis of persistent nasal impairment more than a single time point rhinomanometric examination of nasal patency is recommended. In addition, any future research attempts to correlate nasal patency and dentofacial growth should take into consideration this pattern of development of the functional nasal airway.