Indiana University-Purdue University Indianapolis (IUPUI) / The first part of the study describes the development of a microCT based engineering model to study orthodontic responses. The second part investigated the relationship between orthodontic stimulus, root resorption and bone modeling. It was hypothesized that stress magnitudes are insufficient to portray the mechanical environment and explain the clinical response; directions also play a role. An idealized tooth model was constructed for finite element analysis. The principal stress magnitudes and directions were calculated in tipping and translation. It was concluded that within the same region of root, PDL and bone, there can be compression in one structure, tension in another. At a given point in a structure, compression and tension can coexist in different directions. Magnitudes of compression or tension are typically different in different directions. Previously published data presenting only stress magnitude plots can be confusing, perhaps impossible to understand and/or correlate with biological responses. To avoid ambiguities, a reference to a principal stress should include its predominant direction. Combined stress magnitude/direction results suggest that the PDL is the initiator of mechanotransduction. The third part of this project tested the role of the P2X7 receptor in the dentoalveolar morphology of C57B/6 mice. P2X7R KO (knockout) mice were compared to C57B/6 WT to identify differences in a maxillary molar and bone. Tooth dimensions were measured and 3D bone morphometry was conducted. No statistically significant differences were found between the two mouse types. P2X7R does not have a major effect on alveolar bone or tooth morphology. The final part examines the role of the P2X7 receptor in a controlled biomechanical model. Orthodontic mechanotransduction was compared in wild-type (WT) and P2X7R knock-out (KO) mice. Using Finite Element Analysis, mouse mechanics were scaled to produce typical human stress levels. Relationships between the biological responses and the calculated stresses were statistically tested and compared. There were direct relationships between certain stress magnitudes and root resorption and bone formation. Hyalinization and root and bone resorption were different in WT and KO. Orthodontic responses are related to the principal stress patterns in the PDL and the P2X7 receptor plays a significant role in their mechanotransduction.

Indiana University-Purdue University Indianapolis (IUPUI) / External Apical Root Resorption (EARR) can be an undesirable side effect of orthodontic treatment. Several studies have already recognized a genetic predisposition to EARR, and some have suggested possible candidate genes that may be involved. The objective of this prospective study was to explore one possible candidate gene that may predispose individuals to EARR during orthodontic treatment. The TNFRSF11A gene encodes the receptor activator of nuclear factor-kappa β (RANK). Together with the RANK ligand, RANK mediates cell signaling that leads to osteoclastogenesis. A diallelic marker was used to investigate the possible relationship between a nonsynonymous TNFRSF11A (RANK) polymorphism and the individuals' development of EARR concurrent with orthodontic treatment. Buccal swab cells of 112 patients who had completed orthodontic treatment were collected for DNA isolation and analysis. EARR of the maxillary central incisors was calculated based on measurements from pre and post treatment occlusal radiographs. Linear regression analysis indicated that length of treatment, overjet, and molar classification are significant predictors of EARR (p=0.05). Other factors, including age, gender, and overbite, were not found to be significantly associated with EARR. An ANOVA was performed to examine the relationship of the genotyped TNFRSF11A marker with the dependent variable EARR. When individuals having at least one copy of allele 2 (1,2 and 2,3 genotypes) were pooled together, a marginally significant association was found between EARR and the marker. Further analysis using logistic regression revealed that individuals with a (1,1) genotype are 4.3 times more likely to be affected by EARR than a person with a (1,2) or (2,2) genotype. From these findings it was concluded that EARR is a complex condition influenced by several treatment variables with the TNFRSF11A gene and its product (RANK) contributing to the individuals' predisposition.

El objetivo del presente estudio fue determinar in vitro que grupo de dientes analizados con reabsorción radicular interna tratados endodónticamente y reparados con tres distintos selladores presentó la mayor resistencia a la fractura. Metodología, el estudio fue de nivel básica; de tipo prospectivo, longitudinal y exploratorio; de diseño experimental in vitro; y de enfoque cuantitativo. La población, estuvo conformada por piezas dentarias del grupo premolar mandibulares y de un sólo conducto radicular; la muestra, fue conformada de manera no aleatoria por conveniencia, constituida por 60 piezas dentarias, divididas en seis grupos de 10 dientes cada uno (A: Biodentine + Biodentine, B: Biodentine + gutapercha + Neo Sealer, C: Neo Putty + Neo Putty, D: Neo Putty + gutapercha + cemento Neo sealer, grupo control positivo y grupo control negativo); asimismo, se consideró los criterios de inclusión y exclusión. Para la medición de la resistencia a la fractura se utilizó la máquina universal Instron, en el Laboratorio High Technology Laboratory Certificate S.A.C, San Juan de Lurigancho – Lima, 2023. Resultados, se halló que la resistencia a la fractura promedio de los grupos control positivo y negativo fueron 558.147N y 648.212N, respectivamente; y, la resistencia a la fractura promedio en los grupos experimentales fueron los siguientes: 485.938N para el grupo D, 419.382N para el grupo A, 410.417N para el grupo C y 407.824N para el grupo B. Además, se mostró que existe diferencia significativa entre las medias resistencia a la fractura de los dientes de los grupos experimentales con respecto a los grupos controles, pues los grupos controles tuvieron un mayor rango promedio de la resistencia a la fractura que los dientes tratados con los sellantes endodónticos (p-valor = 0.002, p<0.05). Conclusión, se concluyó que entre los grupos experimentales, el grupo sellador Neo Putty + gutapercha + sellador Neo Sealer fue aquel que mostró la mayor resistencia a la fractura en los dientes con reabsorción radicular interna tratados endodónticamente; sin embargo, esta resistencia fue menor a la hallada en los grupos controles. / The purpose of the present study was to determine in vitro which group of teeth analyzed with internal root resorption treated endodontically and repaired with three different sealants presented the greatest resistance to fracture. Methodology, the study was basic level; prospective, longitudinal and exploratory; in vitro experimental design; and quantitative approach. The population was made up of teeth from the mandibular premolar group and a single root canal; The sample was formed in a non-random manner for convenience, consisting of 60 teeth, divided into six groups of 10 teeth each (A: Biodentine + Biodentine, B: Biodentine + gutta-percha + Neo Sealer, C: Neo Putty + Neo Putty, D: Neo Putty + gutta percha + Neo sealer cement, positive control group and negative control group); Likewise, the inclusion and exclusion criteria were considered. To measure the fracture resistance, the Instron universal machine was used, at the High Technology Laboratory Certificate S.A.C, San Juan de Lurigancho – Lima, 2023. Results, it was found that the average fracture resistance of the positive control groups and negative were 558.147N and 648.212N, respectively; and, the average fracture resistance in the experimental groups were as follows: 485.938N for group D, 419.382N for group A, 410.417N for group C and 407.824N for group B. In addition, it was shown that there is significant difference between the average fracture resistance of the teeth of the experimental groups with respect to the control groups, since the control groups had a greater average range of fracture resistance than the teeth treated with endodontic sealants (pvalue = 0.002, p<0.05). Conclusion, it was concluded that among the experimental groups, the Neo Putty sealer + gutta-percha + Neo Sealer sealer group was the one that showed the greatest resistance to fracture in teeth with endodontically treated internal root resorption; However, this resistance was lower than that found in the control groups.

Made available in DSpace on 2014-07-29T15:21:58Z (GMT). No. of bitstreams: 1 Dissertacao Iury Oliveira Castro.pdf: 1108480 bytes, checksum: 128afd0de2b97f12fc1f7b511b16af6f (MD5) Previous issue date: 2012-02-17 / Objective: To determine the frequency of apical root resorption in different tooth groups after the end of orthodontic treatment, detected by cone beam computed tomography. Methodology: Images of cone beam computed tomography of 30 patients who had Class I malocclusion and crowding were obtained before and after orthodontic movement. The treatment with fixed appliances was developed based on the Roth prescription. A total of 1256 dental roots were evaluated based on the measurement of linear length between root apex and incisal/cusp. It was an epidemiological, prospective, longitudinal and intra individual study. Results: The mean age of patients was 13 years, 11 were male and 19 female. One hundred percent of the patient presented teeth with apical root resorption, 46% of the roots avaluated was affected. The teeth showed higher extent of apical root resorption were upper lateral incisors, lower lateral, upper central, lower central, upper and lower first molars (p <0.05). By analyzing the roots individually, there was a high frequency of apical root resorption in maxillary central incisors (73%), maxillary lateral incisors (73%), mandibular central incisors (72%), mandibular lateral incisors (70%) and distal roots of mandibular first molar (63%). There was a low frequency of apical root resorption in the buccal roots of the maxillary second premolar (17%), distovestibular and palatine roots of maxillary second molar (18%) and distal roots of mandibular second molar (20%). The results showed that there was no association between frequency of resorption and gender (p> 0.05). The number of resorption did not vary with age when evaluated at age 11 to 16 years (p> 0.05). Conclusion: The apical root resorption was detected in 46% of the roots of teeth submitted to orthodontic treatment, diagnosed by cone beam computed tomography. The most affected teeth were central incisors, lateral and first molars. / Objetivo: Determinar a frequência de reabsorção radicular apical em diferentes grupos dentários após o término do tratamento ortodôntico identificada por meio de tomografia computadorizada de feixe cônico. Metodologia: Imagens de tomografia computadorizada de feixe cônico de 30 indivíduos, que apresentavam má oclusão Classe I e apinhamento, foram obtidas antes e depois da movimentação ortodôntica. O tratamento foi desenvolvido com aparelhos fixos com base na prescrição de Roth. Um total de 1256 raízes dentárias foram avaliadas com base na mensuração do comprimento linear entre ápices radiculares e incisais/cúspides. Resultados: A idade média dos pacientes foi de 13 anos, 11 eram do gênero masculino e 19 do feminino. Cem por cento dos pacientes apresentaram dentes com reabsorção radicular apical, com uma frequência de 46% de raízes afetadas. Os dentes que apresentaram maior extensão de reabsorção radicular apical foram incisivos laterais superiores, laterais inferiores, centrais superiores, centrais inferiores, primeiros molares superiores e inferiores (p < 0,05). Ao analisar as raízes individualmente verificou-se uma elevada frequência de reabsorção radicular apical em incisivos centrais superiores (73%), laterais superiores (73%), centrais inferiores (72%), laterais inferiores (70%) e raízes distais de primeiro molar inferior (63%). Verificou-se uma frequência baixa de reabsorção radicular apical em raízes vestibular do segundo pré-molar superior (17%), distovestibulares e palatinas de segundo molar superior (18%) e distal de segundo molar inferior (20%). Os resultados mostraram que não houve associação entre a frequência de reabsorção e gênero (p > 0,05). O número de reabsorção não variou com a idade quando avaliada a faixa etária de 11 a 16 anos (p > 0,05). Conclusão: A reabsorção radicular apical foi detectada em 46% das raízes de dentes submetidos a tratamento ortodôntico, por meio de tomografia computadorizada de feixe cônico. Os dentes mais afetados foram incisivos centrais, laterais e primeiros molares inferiores.