Browsing by Subject "Maxilla"

Now showing 1 - 10 of 12
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    An Investigation of Intermaxillary Tooth Mass Discrepancy: A New Approach
    (1974) Williams, James E.; Garner; Tomich; Potter; Dirlam; Shanks
    This study investigated the incidence, amount, and location of intermaxillary tooth mass discrepancy in a sample of malocclusion cases. Obtaining accurate tooth measurements was a primary concern of the investigation. Interproximal separation was achieved in each case prior to the taking of a silicone rubber impression. Individual tooth dies were then produced from the impression and measured with direct reading instruments. A model of occlusion was adopted as a reference for evaluating tooth mass problems. Each case demonstrated some tooth mass discrepancy. The discrepancies in the posterior segments were generally very minor and of limited clinical significance. Larger discrepancies were found in the anterior segments. Most of these were small enough to be managed by clinical manipulation of tooth position, but approximately one-fifth were large enough to have significant effects on occlusion. The labia-lingual thickness of incisors was found to have considerable potential in affecting the anterior occlusion. Statistical analysis revealed no difference in the amount of tooth mass discrepancy between males and females. Likewise, there was no difference between Class I and Class II malocclusion groups. An anterior ratio and ''Anterior Percentage Relation" were calculated and they compared favorably with the results of the original investigators. The malocclusion cases had a wider range of values than those cases of excellent occlusion. Right-left tooth size asymmetry was investigated. The results indicated that the problem is not nearly as great as previously reported.
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    Antero-Posterior Movement of the Maxillae with a Modified Sutural Expansion Device
    (1967) Gersh, Gary Paul
    It was the purpose of this study to discover if anteroposterior movement of the maxillary bones was possible. Seven cats were used as the experimental animals. An expansion device which produced a diagonal force from one maxillary cuspid to the opposite molar was inserted in five of the animals. Two animals were used as controls. The effects of the lateral and antero-posterior components of the force were studied by means of before and after models, oriented occlusal radiographs, and histologic sections. Antero-posterior movement did occur. The anterior movement was more evident than the posterior movement due to the response evoked in the premaxillary-maxillary and the maxillary-palatine sutures. The sutures which were compressed showed very little response when viewed in horizontal histologic sections as compared to the sutures which were under tension. The sutures under tension showed marked osteophytic production which generally grew parallel to the line of force application. This difference in response allowed one side to remain as an anchorage unit while the opposite side moved anteriorly. The lateral increase in width appeared to be stable. In one animal the force was removed for thirty six days prior to sacrifice. In this animal the stability of the antero-posterior movement was questionable.
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    Comparison of movement rate with different initial moment-to-force ratios
    (Elsevier, 2019-08-01) Li, Shuning; Chen, Jie; Kula, Katherine S.; Mechanical Engineering and Energy, School of Engineering and Technology
    Introduction: The objective of this clinical prospective study was to evaluate the effect of the two treatment strategies, translation or controlled tipping followed by root correction, on canine retraction efficiency, specifically canine movement rate. Methods: Twenty-one patients who needed bilateral maxillary canine retraction to close extraction space as part of their treatment plan were selected for this study. Segmental T-loops designed for controlled tipping or for translation were applied randomly to each side. Two digital maxillary dental casts (taken pre- and post-treatment) were used to measure the tooth displacements of each patient. The coordinate system located at the center of canine crown on the pre-treatment model with the three axes defined in the mesial-distal (M-D), buccal-lingual (B-L), and occlusal-gingival (O-G) directions was used to express the six tooth displacement components. The movement rates on the occlusal plane and in the M-D direction were computed. Movement rates were calculated by dividing the M-D displacements or the resultant displacement on the occlusal plane with the corresponding treatment time. Results: T-loops for controlled tipping moved canines faster (33.3% on occlusal plane and 38.5% in the M-D direction) than T-loops for translation. The differences are statistically significant (p = 0.041 on the occlusal plane and 0.020 in the M-D direction). Conclusion: 1. Moment-to-force ratio (M/F) impacts on the canine movement rate in a maxillary canine retraction treatment with segmented T-loop mechanism. 2. Within the neighborhood of the ratio for translation, lower M/F moves canine faster than higher M/F both on occlusal plane and in the M-D direction.
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    Diagnostic efficacy of novel cephalometric parameters for the assessment of vertical skeletal dysplasia
    (Tabriz University of Medical Sciences, 2022) Gandhi, Kaveri Kranti; Rai, Anshu; Periodontology, School of Dentistry
    Background. An accurate diagnosis of vertical skeletal abnormalities presents several challenges. Specific cephalometric parameters can be effectively used for this purpose; however, the diagnostic accuracy of these parameters has not been entirely ascertained. This study examines the effectiveness of two novel cephalometric parameters for diagnosing vertical dysplasia. Methods. In this retrospective study, orthodontic patients were distributed into three study groups: average growth (AGG), horizontal growth (HGG), and vertical growth (VGG). The efficacies of the sum of angles (maxillary, mandibular, and ramal) and the height ratio (lower anterior facial height [LAFH]/upper anterior facial height [UAFH]) in identifying different growth patterns were examined. Receiver operating characteristic (ROC) curves were employed to assess the diagnostic precision quantitatively. Results. A total of 150 patients were included and divided equally among the three study groups. The ramal and mandibular angles varied across AGG, HGG, and VGG; however, the maxillary angle and the sum of these three angles did not vary significantly. There was a substantial variance in LAHF, UAHF, and their ratio in the three groups. The height ratio had 88% and 92% sensitivity to diagnose VGG and HGG, with cut-off values of 46 and 34, respectively (P<0.001). Conclusion. Height ratio values varied considerably depending on the facial growth patterns, suggesting its efficacy as a diagnostic tool for skeletal dysplasia, with greater reliability for positive treatment outcomes.
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    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 Dentistry
    INTRODUCTION: 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.
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    Estimation of periodontal ligament’s equivalent mechanical parameters for finite element modeling
    (Elsevier, 2013) Xia, Zeyang; Jiang, Feifei; Chen, Jie; Mechanical and Energy Engineering, Purdue School of Engineering and Technology
    Introduction: Young's modulus (E) and Poisson's ratio (v) of the periodontal ligament are needed in a finite element analysis for investigating the biomechanical behavior of a tooth, periodontal ligament, and bone complex. However, large discrepancies in E (0.01-1,750 MPa) and v (0.28-0.49) were reported previously. The objective of this study was to narrow the ranges and to provide equivalent E and v pairs suitable for finite element modeling of a tooth, periodontal ligament, and bone complex by using a reported crown load-displacement relationship as the criterion. Methods: A 3-dimensional finite element model of a 3-tooth, periodontal ligament, and bone complex, consisting of a maxillary central incisor with 2 adjacent teeth, from a cone-beam computed tomography scan was created. The dimensions, constraints, and loading condition were kept similar to those reported in the human study. With the load applied to the crown, both v and E were adjusted independently, and the corresponding crown displacements were calculated. The resulting load-displacement curves were compared with those reported in the human study. The mean absolute displacement difference method was used to find the best fit. The E and v pairs that generated the minimum mean absolute displacement difference were identified. Results: The finite element model with 1 of the 3 E and v pairs (v = 0.35, E = 0.87 MPa; v = 0.4, E = 0.71 MPa; and v = 0.45, E = 0.47 MPa) simulated the tooth, periodontal ligament, and bone complex well. The mean absolute displacement differences were 0.0135, 0.0138, and 0.0138 mm, respectively; these are less than 8% of 0.175 mm, which was the crown displacement of the tooth, periodontal ligament, and bone complex under the load of 500 cN. Conclusions: The E and v values close to the 3 pairs might be used for finite element modeling of the tooth, periodontal ligament, and bone complex.
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    A Histologic and Cephalometric Investigation of Premolar Intrusion in the Macaque Speciosa Monkey
    (1965) Dellinger, Eugene L.
    It has been debated as to whether teeth may actually be intruded in their alveoli. This study was designed to measure the intrusive movement and histologic response of specific teeth to a known intrusive force. Four Macaque speciosa monkeys were used. The animals corresponded in age to a 12-14 year old human being. Intrusive forces of either 10, 50, 100, or 300 grams were placed on the maxillary first premolars; each force value was held constant during the duration of the experiment, which was 60 days. Maxillary first molars were used as anchorage. Cephalometric headplates proved that all force values were capable of giving intrusion. The 50 gram forces, however, gave the most efficient intrusion. Histologic sections were made on all experimental teeth. 300 and 100 gram forces gave excessive root resorption but the 50 and 10 gram force values elicited only slight root resorption. Root resorption seemed to be directly related to excessive force. The amount of intrusion was not related to a loss of root structure. Bone resorption appeared to allow the intrusion of teeth with minimal tissue damage if proper force values were used.
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    Orthopedic Protraction of the Maxilla in Macaca Speciosa
    (1972) Hamilton, John G.
    The intent of this study was to use orthopedic forces to move the maxilla forward in Macaca speciosa (stump tailed monkeys). Three animals were fitted with helmets and facebows to serve as extraoral anchorage. Acrylic labial-lingual splints were ligated with wire around the maxillary teeth. Calibrated coil springs were placed between the splints and facebows and activated to produce forces of two, three, and four kilograms. Paired stainless steel implants had been placed to facilitate cephalometric analysis of the position of the maxilla. The period of activation was to have been thirty days. One animal escaped from the appliance within twelve hours. The other two were taken off the appliance within forty-eight hours because pressure necrosis had developed under the helmet. No data were collected. The uninjured animal was fitted with a different design of helmet and the spring was activated to produce one kilogram. After four days the animal had developed ulcers under the helmet and the experiment was terminated. Lateral headplates were taken before and after the experimental period. Cephalometric analysis and superpositioning showed no change in the position of the maxilla. It was concluded that after four days of one kilogram anterior pull the maxilla did not move. The difficulties encountered in the study defined the problem as being the attainment of suitable anchorage from which to apply the anterior orthopedic force to the maxilla. Several areas of additional research were discussed relative to achieving protraction of the maxilla.
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    Relationship of Wound Healing and Angiogenesis to the Cell Kinetics of the Initial Osteogenic Response in Orthopedically Expanded Anterior Maxillary Suture in the Rat
    (1994-07) Chang, Hwai-nan; Roberts, W. Eugene; Chen, Jie; Christen, Arden G.; Garetto, Lawrence P.; Katona, Thomas R.; Lee, Chao-Hung; McDonald, James
    Following sutural expansion, wound healing and angiogenesis precede bone formation. The purpose of this study was to examine angiogenic and subsequent osteogenic responses during a 96 hour time-course following sutural expansion. Fifty rats were divided into: (1) control group that received only angiogenic induction via injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) experimental group that received orthopedic expansion and rhECGF; (3) sham group that received expansion and NaCl injection; and (4) baseline group that received no expansion or injection. Both experimental and sham groups were subdivided further to conduct experiments of 1, 2, 3, and 4 days. All rats were injected with 3H-thymidine (1.0 μCi/gm) 1 hour before euthanasia to label DNA of S-phase cells. The premaxilla was dissected free and demineralized. Sections (4 μm thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration were analyzed using a previously established cell kinetics model. The cells were divided into four categories according to nuclear volume: A cells (40-79 μm3), B cells (80-119 μm3), C cells (120-169 μm 3), and D cells (~169 μm3). ANOVA was used to test the hypothesis that enhancement of angiogenesis stimulates reestablishment of osteogenic capability. Blood vessel number, area and endothelial cell labeled index significantly increased in experimental groups, but no difference was found between control and baseline groups (i.e., rhECGF treatment alone). Labeled-pericyte index and activated pericyte's numbers in the experimental group were also higher than in the sham groups. Compared to sham groups, A+A' cell numbers were significantly higher during the first two days in the experimental groups, followed by a rapid decrease at days three and four; C+D cell number peaked at day three. These results demonstrate that supplemental rhECGF enhances angiogenesis in expanded suture but not in nonexpanded suture. Data also suggest that pericytes may serve as a bridge between angiogenesis and osteogenesis.