RESUMO
OBJECTIVE: The purpose of this study is to assess the effects of rapid maxillary expansion on metabolic activity in the temporomandibular joints of young adult patients using scintigraphy. METHODS: The images belonging to temporomandibular joints were obtained from the retrospective scintigraphic records taken from 17 adult females (16.1 and 18.8 years of age and the mean age was 17.3±0.86 years) who had non-functional bilateral posterior crossbite, deep palatal vault and dental crowding, and had been treated with rapid maxillary expansion. Bone scintigraphy images were collected at three-time intervals: at the beginning of treatment (T1), during the opening of the mid palatal suture (T2), and at the end of screw activation (T3). Alteration in bone activity in the temporomandibular joint regions were evaluated in sagittal and transaxial slices. To determine the differences between the intervals, repeated analysis of variance and Bonferroni multiple comparison tests were applied. RESULTS: In the right and left temporomandibular joint regions, significantly increased metabolic activity was exhibited between T1-T2 (p<0.001). At the time of opening the maxillary mid-palatal suture, the metabolic activity increased approximately 60% compared to the initial status. At the end of the active expansion period (T3), the change in metabolic activity was approximately 20% reduced compared to T2. CONCLUSION: Metabolic activity intensification occurs in the regions of interest in the temporomandibular joint during rapid maxillary expansion. After mid-palatal suture opening, activity noticeably decreased (T2-T3). This decrease in bone activity suggests that the temporomandibular joint complex adapts to rapid maxillary expansion forces.
RESUMO
Objective: This study evaluates the shear bond strength (SBS) and Vickers micro-hardness (VHN) of the orthodontic adhesive resin Transbond XT using thermocycled samples. The study also measures the degree of cure by poliwave light curing unit Valo. Materials and Methods: 135 brackets were bonded for the SBS test, and 90 disc-shaped orthodontic adhesive resins were prepared for the VHN test. The measurements were taken either immediately or after 500 or 10.0000 thermocycling. The SBS and VHN test data were statistically evaluated using a Two-way ANOVA and Tukey multiple comparison tests. The degree of conversion (DC) was measured by FTIR. Results: The 10-sec polymerized control group (57.08) and the 10.000 termocycled samples (55.96) had the highest VHN scores. On the other hand, the 3 second polymerized and the 10.000 termocycled samples (39.22) had the lowest VHN scores. There was no significant difference in the bracket SBS values between the termocycled and immediate groups. An evaluation of the bond failure surfaces revealed that the ARI scores did not differ between the immediate and the thermo-cycled groups according to the power modes. The FTIR results revealed that the lowest DC was seen in the 3 second light-cured sample. Conclusion: TransbondXT provided sufficient bond strength, microhardness and DC under in vitro bracket bonding conditions after 3 and 10 s of Poliwave LED curing. However, low mean values were seen in the groups that received Poliwave LED curing for only 3 s (AU)
Objetivo: Este estudo avalia a resistência ao cisalhamento (SBS) e a microdureza Vickers (VHN) da resina adesiva ortodôntica Transbond XT utilizando amostras termocicladas. O estudo também mede o grau de cura pela unidade de fotopolimerização Valo poliwave. Materiais e Métodos: 135 braquetes foram colados para o teste SBS e 90 discos de resina adesiva ortodôntica foram preparados para o teste VHN. As medições foram feitas imediatamente ou após 500 ou 10.000 ciclos de termociclagem. Os dados dos testes SBS e VHN foram avaliados estatisticamente usando ANOVA 2 fatores e teste de comparação múltipla de Tukey. O grau de conversão (DC) foi medido por FTIR. Resultados: O grupo controle polimerizado por 10segundos (57,08) ciclados por 10.000 ciclos (55,96) tiveram os valores VHN mais altos. Por outro lado, as amostras polimerizadas de 3 segundos e 10.000 ciclos (39,22) os valores de VHN mais baixos. Não houve diferença significativa nos valores de SBS do braquete entre os grupos termociclados e imediato. Uma avaliação das superfícies de falha de adesão revelou que os escores do ARI não diferiram entre os grupos imediato e termociclados de acordo com as densidades de potência. Os resultados do FTIR revelaram que o menor DC foi observado nas amostras fotopolimerizadas de 3 segundos. Conclusão: Transbond XT forneceu suficiente resistência de união, microdureza e DC sob condições de colagem de braquetes in vitro após 3 e 10 s de polimerização em LED Poliwave. No entanto, valores médios baixos foram observados nos grupos que receberam a cura do LED Poliwave por apenas 3 s (AU)
