Browsing by Subject "Cuspid"
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Item A Comparison of Frictional Forces During Simulated Cuspid Retraction on a Continuous Edgewise Archwire(1982) Allai, W. Wesley; Garner, LaForrest D.; Sondhi, Anoop; Shanks, James C.; Swartz, Marjorie L.; Barton, PaulThis investigation was designed to compare the force (grams) required to overcome a simulated cuspid retraction assembly capable of three dimensional control during the retraction process. It was hypothesized that a significant difference in the mean retraction values exists between the newer orthodontic alloys of Nitinol, Beta-Titanium, as well as Stainless Steel. One hundred eighty bracket and archwire combinations were examined as follows: Sample # Wire Cross-section Wire Material 30 .016”x.022” Stainless Steel 30 .017”x.025” ” 30 .016”x.022” Nitinol 30 .017”x.025” ” 30 .016”x.022 Beta-Titanium (TMA) 30 .017”x.025” ” A statistically significant difference was shown to exist between all six groups examined regarding the variables of wire size and wire material. The statistical analysis revealed that increasing rectangular archwire cross-sectional size from .016"x.022" to .017"x.025” rectangular wire when simulating canine retraction using an .018" slotted Lewis bracket will lead to significantly greater functional forces. The analysis of wire materials indicated that a significant difference (p=.01) exists between rectangular Beta-Titanium (TMA), Nitinol, and stainless steel during simulated cuspid retraction utilizing a narrow .018" Lewis bracket ligated with A-lastik ligatures. The least frictional force was observed with the .016"x.022" stainless steel test cells. The largest frictional force was found in the .017”'x.025" Beta-Titanium retraction specimens. Nitinol revealed force data intermediate between stainless steel and Beta-Titanium. The maximum resistance assembly developed 2.3 times the minimum frictional force observed. The mean grams of frictional force within these test cells ranged from 55.03 grams for the .016"x.022" retraction assembly to 132.68 grams for the .017"x.025" Beta-Titanium assembly. A topographical scanning electron microscope survey of the brackets and archwires utilized was included to provide qualitative insights into the quantitative results described.Item Effects of rapid maxillary expansion on the cranial and circummaxillary sutures(Elsevier, 2011-10) Ghoneima, Ahmed; Abdel-Fattah, Ezzat; Hartsfield, James; El-Bedwehi, Ashraf; Kamel, Ayman; Kula, Katherine; Department of Orthodontics and Oral Facial Genetics, IU School of DentistryINTRODUCTION: The aim of this study was to determine whether the orthopedic forces of rapid maxillary expansion cause significant quantitative changes in the cranial and the circummaxillary sutures. METHODS: Twenty patients (mean age, 12.3 ± 1.9 years) who required rapid maxillary expansion as a part of their comprehensive orthodontic treatment had preexpansion and postexpansion computed tomography scans. Ten cranial and circummaxillary sutures were located and measured on one of the axial, coronal, or sagittal sections of each patient's preexpansion and postexpansion computed tomography scans. Quantitative variables between the 2 measurements were compared by using the Wilcoxon signed rank test. A P value less than 0.05 was considered statistically significant. RESULTS: Rapid maxillary expansion produced significant width increases in the intermaxillary, internasal, maxillonasal, frontomaxillary, and frontonasal sutures, whereas the frontozygomatic, zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures showed nonsignificant changes. The greatest increase in width was recorded for the intermaxillary suture (1.7 ± 0.9 mm), followed by the internasal suture (0.6 ± 0.3 mm), and the maxillonasal suture (0.4 ± 0.2 mm). The midpalatal suture showed the greatest increase in width at the central incisor level (1.6 ± 0.8 mm) followed by the increases in width at the canine level (1.5 ± 0.8 mm) and the first molar level (1.2 ± 0.6 mm). CONCLUSIONS: Forces elicited by rapid maxillary expansion affect primarily the anterior sutures (intermaxillary and maxillary frontal nasal interfaces) compared with the posterior (zygomatic interface) craniofacial structures.Item Hounsfield unit change in root and alveolar bone during canine retraction(Elsevier, 2015-04) Jiang, Feifei; Liu, Sean S.-Y.; Xia, Zeyang; Li, Shuning; Chen, Jie; Kula, Katherine S.; Eckert, George; Department of Orthodontics and Oral Facial Genetics, IU School of DentistryINTRODUCTION: The objective of this study was to determine the Hounsfield unit (HU) changes in the alveolar bone and root surfaces during controlled canine retractions. METHODS: Eighteen maxillary canine retraction patients were selected for this split-mouth design clinical trial. The canines in each patient were randomly assigned to receive either translation or controlled tipping treatment. Pretreatment and posttreatment cone-beam computed tomography scans of each patient were used to determine tooth movement direction and HU changes. The alveolar bone and root surface were divided into 108 divisions, respectively. The HUs in each division were measured. Mixed-model analysis of variance was applied to test the HU change distribution at the P <0.05 significance level. RESULTS: The HU changes varied with the directions relative to the canine movement. The HU reductions occurred at the root surfaces. Larger reductions occurred in the divisions that were perpendicular to the moving direction. However, HUs decreased in the alveolar bone in the moving direction. The highest HU reduction was at the coronal level. CONCLUSIONS: HU reduction occurs on the root surface in the direction perpendicular to tooth movement and in the alveolar bone in the direction of tooth movement when a canine is retracted.Item Load System of Segmental T-Loops for Canine Retraction(Elsevier, 2013) Xia, Zeyang; Chen, Jie; Jiang, Feifei; Li, Shuning; Viecilli, Rodrigo F.; Liu, Sean Y.; Orthodontics and Oral Facial Genetics, School of DentistryIntroduction: The orthodontic load system, especially ideal moment-to-force ratios, is the commonly used design parameter of segmental T-loops for canine retraction. However, the load system, including moment-to-force ratios, can be affected by the changes in canine angulations and interbracket distances. We hypothesized that clinical changes in canine position and angulation during canine retraction will significantly affect the load system delivered to the tooth. Methods: The load systems of 2 T-loop groups, one for translation and the other for controlled tipping, from 9 bilateral canine retraction patients were made to the targeted values obtained from finite element analyses and validated. Each loop was tested on the corresponding maxillary dental cast obtained in the clinic. The casts were made before and after each treatment interval so that both initial and residual load systems could be obtained. The pretreatment and posttreatment interbracket distances were recorded for calculating interbracket distance changes. Results: As the interbracket distances decreased, the average retraction-force drop per interbracket distance reduction was 36 cN/mm, a 30% drop per 1 mm of interbracket distance decrease. The average antitipping-moment drops per interbracket distance reductions were 0.02 N-mm per millimeter for controlled tipping and 1.4 N-mm per millimeter for translation, about 0.6% and 17% drops per 1 mm of interbracket decrease, respectively. Consequently, the average moment-to-force ratio increases per 1 mm of interbracket distance reduction were 1.24 mm per millimeter for controlled tipping and 6.34 mm per millimeter for translation. There was a significant residual load, which could continue to move the tooth if the patient missed the next-scheduled appointment. Conclusions: Clinical changes in canine position and angulation during canine retraction significantly affect the load system. The initial planned moment-to-force ratio needs to be lower to reach the expected average ideal value. Patients should be required to follow the office visit schedule closely to prevent negative effects because of significant moment-to-force ratios increases with time.Item Mechanical environment change in root, periodontal ligament, and alveolar bone in response to two canine retraction treatment strategies(Wiley Blackwell (Blackwell Publishing), 2015-04) Jiang, F.; Xia, Z.; Li, S.; Eckert, G.; Chen, J.; Department of Engineering Technology, School of Engineering and TechnologyOBJECTIVE: To investigate the initial mechanical environment (ME) changes in root surface, periodontal ligament (PDL), and alveolar bone due to two treatment strategies, low or high moment-to-force ratio (M/F). SETTING AND SAMPLE POPULATION: Indiana University-Purdue University Indianapolis. Eighteen patients who underwent maxillary bilateral canine retraction. MATERIAL AND METHOD: Finite element models of the maxillary canines from the patients were built based on their cone beam computed tomography scans. For each patient, the canine on one side had a specially designed T-loop spring with the M/F higher than the other side. Four stress invariants (1st principal/dilatational/3rd principal/von Mises stress) in the tissues were calculated. The stresses were compared with the bone mineral density (BMD) changes reported previously for linking the ME change to bone modeling/remodeling activities. The correlation was tested by the mixed-model anova. RESULTS: The alveolar bone in the direction of tooth movement is primarily in tension, while the PDL is in compression; the stresses in the opposite direction have a reversed pattern. The M/F primarily affects the stress in root. Three stress invariants (1st principal/3rd principal/dilatational stress) in the tooth movement direction have moderate correlations with BMD loss. CONCLUSIONS: The stress invariants may be used to characterize what the osteocytes sense when ME changes. Their distributions in the tissues are significantly different, meaning the cells experience different stimuli. The higher bone activities along the direction of tooth movement may be related to the initial volumetric increase and decrease in the alveolar bone.Item Root resorptions associated with canine retraction treatment(Elsevier, 2017-09) Jiang, Feifei; Chen, Jie; Kula, Katherine; Gu, Huiying; Du, Yansheng; Eckert, George; Mechanical and Energy Engineering, School of Engineering and TechnologyINTRODUCTION: The hypothesis of this study was that multiple factors are dominant in causing external apical root resorption (EARR). The objective of this investigation was to better understand the clinical factors that may lead to EARR. METHODS: Maxillary cone-beam computed tomography scans of 18 subjects who were treated with bilateral canine retractions during orthodontics were used to calculate EARR. The subjects were treated using well-calibrated segmental T-loops for delivering a 124-cN retraction force and the moment-to-force ratio suitable for moving the canine under either translation or controlled tipping. The subjects' age, sex, treatment duration, and genotype were collected. RESULTS: Six subjects of the 18 showed definite EARR, meaning that load was not the only causing factor. All 5 subjects with the genotype identified had GG genotype of IL-1β rs11143634, indicating that people with this genotype may be at high risk. Longer treatment duration, female sex, and older age may also contribute to EARR, although the findings were not statistically significant. CONCLUSIONS: EARR appears to be related to multiple factors. The orthodontic load and the genotype should be the focuses for future studies.Item Three-dimensional canine displacement patterns in response to translation and controlled tipping retraction strategies(The Angle Orthodontist, 2015-01) Li, Shuning; Xia, Zeyang; Liu, Sean Shih-Yao; Eckert, George; Chen, Jie; Department of Mechanical Engineering, School of Engineering and TechnologyOBJECTIVE: To validate whether applying a well-defined initial three-dimensional (3D) load can create consistently expected tooth movement in patients. MATERIALS AND METHODS: Twenty-one patients who needed bilateral canine retraction to close extraction space were selected for this split-mouth clinical trial. After initial alignment and leveling, two canines in each patient were randomly assigned to receive either translation (TR) or controlled tipping (CT) load. The load was delivered by segmental T-loops designed to give specific initial moment/force ratios to the canines in each treatment interval (TI), verified with an orthodontic force tester. Maxillary dental casts were made before canine retraction and after each TI. The casts were digitized with a 3D laser scanner. The digital models were superimposed on the palatal rugae region. The 3D canine displacements and the displacement patterns in terms of TR, CT, and torque were calculated for each TI. RESULTS: The method can reliably detect a TR displacement greater than 0.3 mm and a rotation greater than 1.5°. Ninety-two TIs had displacements that were greater than 0.3 mm and were used for further analysis. Most displacements were oriented within ±45° from the distal direction. The displacement pattern in terms of TR or CT was not uniquely controlled by the initial moment/force ratio. CONCLUSIONS: The initial load system is not the only key factor controlling tooth movement. Using a segmental T-loop with a well-controlled load system, large variations in canine displacement can be expected clinically.