Department of Orthodontics and Oral Facial Genetics

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An engineering model of the Stuart pantograph
(1993-12) Katona, Thomas R.; Garetto, Lawrence P.; Drum, Raymond K.
A comprehensive analysis of normal variation and disease-causing mutations in the human DSPP gene
(Wiley, 2008-12) McKnight, Dianalee A.; Hart, P. Suzanne; Hart, Thomas C.; Hartsfield, James K.; Wilson, Anne; Wright, J. Timothy; Fisher, Larry W.; Orthodontics and Oral Facial Genetics, School of Dentistry
Within nine dentin dysplasia (DD) (type II) and dentinogenesis imperfecta (type II and III) patient/families, seven have 1 of 4 net -1 deletions within the approximately 2-kb coding repeat domain of the DSPP gene while the remaining two patients have splice-site mutations. All frameshift mutations are predicted to change the highly soluble DSPP protein into proteins with long hydrophobic amino acid repeats that could interfere with processing of normal DSPP and/or other secreted matrix proteins. We propose that all previously reported missense, nonsense, and splice-site DSPP mutations (all associated with exons 2 and 3) result in dominant phenotypes due to disruption of signal peptide-processing and/or related biochemical events that also result in interference with protein processing. This would bring the currently known dominant forms of the human disease phenotype in agreement with the normal phenotype of the heterozygous null Dspp (-/+) mice. A study of 188 normal human chromosomes revealed a hypervariable DSPP repeat domain with extraordinary rates of change including 20 slip-replication indel events and 37 predominantly C-to-T transition SNPs. The most frequent transition in the primordial 9-basepair (bp) DNA repeat was a sense-strand CpG site while a CpNpG (CAG) transition was the second most frequent SNP. Bisulfite-sequencing of genomic DNA showed that the DSPP repeat can be methylated at both motifs. This suggests that, like plants and some animals, humans methylate some CpNpG sequences. Analysis of 37 haplotypes of the highly variable DSPP gene from geographically diverse people suggests it may be a useful autosomal marker in human migration studies.
Pathways in external apical root resorption associated with orthodontia
(Wiley, 2009-08) Hartsfield Jr., J.K.; Department of Orthodontics and Oral Facial Genetics, IU School of Dentistry
To review studies investigating if genetic factors play a role in external apical root resorption (EARR) during orthodontic treatment. Heritability estimation in human sib-pairs, comparison of multiple inbred mouse strains, human sib-pair linkage and parents-child trio association studies, and two gene (Il-1b, and P2rx7) knock out mouse models. Heritability for EARR of the maxillary central incisors concurrent with orthodontic treatment is 0.8. DBA/2J, BALB/cJ, and 129P3/J inbred mouse strains are highly susceptible (p < .05) to histological root resorption (RR) associated with orthodontic force (RRAOF), whereas A/J, C57BL/6J and SJL/J mice are resistant. Non-parametric sibling pair linkage analysis identified evidence of linkage (LOD = 2.5; p = 0.02) of EARR with microsatellite D18S64 (tightly linked to TNFRSF11A, also known as RANK). There is significant linkage disequilibrium of IL-1B (p = 0.0003), and OPG (p = 0.003) with EARR. RRAOF increases in Il1b KO (p < or = 0.013), and increases in P2rx7 KO (p < 0.02) mice compared to wild-type. Genetic factors play a marked role in EARR concurrent with orthodontic force, accounting for one-half to two-thirds of the variation. Two pathways for this may involve: 1) activation control of osteoclasts through the ATP/P2XR7/IL-1B inflammation modulation pathway; and 2) RANK/RANKL/OPG osteoclast activation control. Histological RR occurs and is typically healed. If resorption outpaces healing, then EARR develops. Normal and parafunctional forces, as well as orthodontic forces, may add to or interact with the individual's susceptibility to pass the threshold of developing EARR.
Clinical Outcomes of 0.018-Inch and 0.022-Inch Bracket Slot Using the ABO Objective Grading System
(E.H Angle Education and Research Foundation, 2010-05-01) Detterline, David A.; Isikbay, Serkis C.; Brizendine, Edward J.; Kula, Katherine S.; Orthodontics and Oral Facial Genetics, School of Dentistry
Objective: To determine if there is a significant difference in the clinical outcomes of cases treated with 0.018-inch brackets vs 0.022-inch brackets according to the American Board of Orthodontics (ABO) Objective Grading System (OGS). Materials and Methods: Treatment time and the ABO-OGS standards in alignment/rotations, marginal ridges, buccolingual inclination, overjet, occlusal relationships, occlusal contacts, interproximal contacts, and root angulations were used to compare clinical outcomes between a series of 828 consecutively completed orthodontic cases (2005–2008) treated in a university graduate orthodontic clinic with 0.018-inch- and 0.022-inch-slot brackets. Results: A two-sample t-test showed a significantly shorter treatment time and lower ABO-OGS score in four categories (alignment/rotations, marginal ridges, overjet, and root angulations), as well as lower total ABO-OGS total score, with the 0.018-inch brackets. The ANCOVA—adjusting for covariants of discrepancy index, age, gender, and treatment time—showed that the 0.018-inch brackets scored significantly lower than the 0.022-inch brackets in both the alignment/rotations category and total ABO-OGS score. Conclusions: There were statistically, but not clinically, significant differences in treatment times and in total ABO-OGS scores in favor of 0.018-inch brackets as compared with the 0.022-inch brackets in a university graduate orthodontic clinic (2005–2008).
Influence of ceramic (feldspathic) surface treatments on the micro-shear bond strength of composite resin
(E.H Angle Education and Research Foundation, 2010-07-01) Yadav, Sumit; Upadhyay, Madhur; Borges, Gilberto Antonio; Roberts, W. Eugene; Orthodontics and Oral Facial Genetics, School of Dentistry
Objective: To test the null hypothesis that surface treatment has no influence on the micro-shear bond strength between orthodontic composite resin cement and ceramics (feldspathic porcelain). Materials and Methods: Circular specimens of feldspathic porcelain were fabricated and randomly divided into six groups: (1) no treatment; (2) treatment with a mixture of acidic primer and silane agent for 20 seconds; (3) etching with 9.5% hydrofluoric acid; (4) etching with 9.5% hydrofluoric acid and coating with a mixture of acidic primer and silane agent for 20 seconds; (5) airborne-particle abrasion with 50-μm aluminum oxide; and (6) airborne-particle abrasion and coating with a mixture of acidic primer and silane agent for 20 seconds. The porcelain disks were then bonded to resin cylinders with composite resin cement. A micro-shear bond test was carried out to measure the bond strength. Moreover, each ceramic surface was observed morphologically by scanning electron microscopy. One-way analysis of covariance was used to compare the groups for differences in micro-shear bond strength. Results: The mean micro-shear bond strength varied as a function of surface treatment. It ranged from 3.7 to 20.8 MPa. The highest values for micro-shear bond strength were found when the surface was acid-etched with hydrofluoric acid and coated with silane. On the other hand, the control group (no treatment) had significantly lower micro-shear bond strength than all the other groups. Conclusion: The null hypothesis that the surface treatment has no influence on the micro-shear bond strength of orthodontic composite resin was rejected. The bond strength between ceramics and orthodontic resin cement is affected by the ceramic surface treatment. The bond failure was of the adhesive type, except with the hydrofluoric acid + silane group, where it was a cohesive bond failure.
Quantification of three-dimensional orthodontic force systems of T-loop archwires
(E.H Angle Education and Research Foundation, 2010-07-01) Chen, Jie; Isikbay, Serkis C.; Brizendine, Edward J.; Orthodontics and Oral Facial Genetics, School of Dentistry
Objective: To demonstrate the three-dimensional (3D) orthodontic force systems of three commercial closing T-loop archwires using a new method and to quantify the force systems of the T-loop archwires. Materials and Methods: An orthodontic force tester (OFT) and a custom-made dentoform were developed to measure force systems. The system simulated the clinical environment for an orthodontic patient requiring space closure, which included measurement of three force components along, and three moment components about, three clinically defined axes on two target teeth. The archwires were attached to the dentoform and were activated following a standard clinical procedure. The resulting force system was measured using the OFT. Results: The force systems of the T-loops on the teeth were 3D. Activation in one direction resulted in force and moment components in other directions (side effects). The six force and moment components as well as the moment-to-force ratios in the clinically defined coordinate system were quantified. Conclusions: The commercial archwires do not provide force systems for pure translation. Quantification of the force system is critical for the selection and design of optimal orthodontic appliances.
On the Antiquity of Trisomy 21: Moving Towards a Quantitative Diagnosis of Down Syndrome in Historic Material Culture
(2011) Starbuck, John M
Down syndrome was first medically described as a separate condition from other forms of cognitive impairment in 1866. Because it took so long for Down syndrome to be recognized as a clinical entity deserving its own status, several investigators have questioned whether or not Down syndrome was ever recognized before 1866. Few cases of ancient skeletal remains have been documented to have Down syndrome-like characteristics. However, several forms of material culture may depict this condition. Within this paper the history of our understanding of Down syndrome is discussed. Both skeletal remains and different forms of material culture that may depict Down syndrome are described, and where relevant, debates within the literature about how likely such qualitative diagnoses are to be correct are also discussed. Suggestions are then made for ways in which a quantitative diagnosis can be made to either strengthen or weaken qualitative arguments for or against the diagnosis of Down syndrome in different forms of historic material culture.
The effect of pH levels on nonlatex vs latex interarch elastics
(Allen Press, 2011) Sauget, Paul S.; Stewart, Kelton T.; Katona, Thomas R.; Orthodontics and Oral Facial Genetics, School of Dentistry
Objective: To evaluate the force decay characteristics of nonlatex vs latex interarch elastics within the normal range of salivary pH levels. Materials and methods: Two nonlatex groups and one latex quasi-control group were tested. Elastics were stretched to 15 mm and were held for 10 seconds (baseline), 4 hours, 8 hours, and 12 hours in artificial saliva solutions with pH levels of 5.0, 6.0, and 7.5. Force magnitudes were measured at 25 mm of activation. Each specimen was used once. Measurements were assessed using three-way analysis of variance (ANOVA). Results: The three-way interaction between group, pH, and time was not significant (P = .13); the group-by-pH interaction also was not significant (P = .70). However, pH-by-time (P = .0179) and group-by-time (P = .0001) interactions were significant. American Orthodontics nonlatex generated significantly higher loads than Auradonics nonlatex. American Orthodontics nonlatex produced significantly higher forces than American Orthodontics latex at 4, 8, and 12 hours, but not at 10 seconds. American Orthodontics latex was significantly stronger than Auradonics nonlatex at 10 seconds, but not at 4, 8, and 12 hours. Conclusions: No clinically significant correlation between pH and force decay was observed.
The relationship between the ABO discrepancy index and treatment duration in a graduate orthodontic clinic
(Allen Press, 2011) Parrish, Laura D.; Roberts, W. Eugene; Maupome, Gerardo; Stewart, Kelton T.; Bandy, Robert W.; Kula, Katherine S.; Orthodontics and Oral Facial Genetics, School of Dentistry
Objective: To test the hypothesis that there is no relationship between the components of the American Board of Orthodontics (ABO) discrepancy index (DI) and duration of orthodontic treatment. Materials and methods: A retrospective review of 732 patient records with permanent dentition was performed. Pretreatment radiographs and casts were used to determine the DI score. Other data collected were total treatment duration, age, sex, ethnicity, and the date fixed appliances were removed. Reliability tests showed substantial agreement between examiners (Cohen's kappa 0.68-0.94). Pearson and Spearman correlation coefficients were used to assess the association between the DI scores and length of treatment. A multiple variable regression analysis was used to determine which variables predict treatment duration (P < .05 significant). Results: There was a significant association between the DI and treatment duration. There was a significant multivariate association for DI components (occlusions, crowding, overjet, cephalometrics, overbite, lateral open bite, and tooth transposition) and treatment duration. Conclusions: The hypothesis was rejected. This retrospective study of university clinical records showed that the average increase in treatment duration was about 11 days for each point increase in total DI score. Treatment duration was differentially increased by various components of the DI: approximately 6.5 months for tooth transposition; approximately 1 month for crowding, overjet, or overbite; approximately 3 weeks for occlusion discrepancies; approximately 2 weeks for lateral open bite; and approximately 5 days for cephalometric discrepancies.
A Qualitative Engineering Analysis of Occlusion Effects on Mandibular Fracture Repair Mechanics
(SAGE-Hindawi, 2011-08) Katona, Thomas R.
Objectives. The purpose of this analytical study was to examine and critique the engineering foundations of commonly accepted biomechanical principles of mandible fracture repair. Materials and Methods. Basic principles of static equilibrium were applied to intact and plated mandibles, but instead of the traditional lever forces, the mandibles were subjected to more realistic occlusal forces. Results. These loading conditions produced stress distributions within the intact mandible that were very different and more complex than the customary lever-based gradient. The analyses also demonstrated the entirely different mechanical environments within intact and plated mandibles. Conclusions. Because the loading and geometry of the lever-idealized mandible is incomplete, the associated widely accepted bone stress distribution (tension on top and compression on the bottom) should not be assumed. Furthermore, the stress gradients within the bone of an intact mandible should not be extrapolated to the mechanical environment within the plated regions of a fractured mandible.

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