RESUMEN
OBJECTIVE: To analyze the long-term changes in maxillary arch widths and buccal corridor ratios in orthodontic patients treated with and without premolar extractions. METHODS: The study included 53 patients who were divided into the extraction (n = 28) and nonextraction (n = 25) groups. These patients had complete orthodontic records from the pretreatment (T1), posttreatment (T2), and postretention (T3) periods. Their mean retention and postretention times were 4 years 2 months and 17 years 8 months, respectively. Dental models and smiling photographs from all three periods were digitized to compare the changes in three dental arch width measurements and three buccal corridor ratios over time between the extraction and nonextraction groups. Data were analyzed using analysis of variance tests. Post-hoc multiple comparisons were made using Bonferroni correction. RESULTS: Soft-tissue extension during smiling increased with age in both groups. The maximum dental width to smile width ratio (MDW/SW) also showed a favorable increase with treatment in both groups (p < 0.05), and remained virtually stable at T3 (p > 0.05). According to the MDW/SW ratio, the mean difference in the buccal corridor space of the two groups was 2.4 ± 0.2% at T3. Additionally, no significant group × time interaction was found for any of the buccal corridor ratios studied. CONCLUSIONS: Premolar extractions did not negatively affect transverse maxillary arch widths and buccal corridor ratios. The long-term outcome of orthodontic treatment was comparable between the study groups.
RESUMEN
OBJECTIVE: To determine if repeated sterilization has deleterious effects on the clinical stability of mini-screws. MATERIALS AND METHODS: Thirty each of the following mini-screws were tested: Aarhus (American Orthodontics, Sheboygan, Wisc), VectorTAS (Ormco Corporation, Orange, Calif), Dual-Top (RMO, Denver, Colo), and Ortho Anchor (KLS Martin, Jacksonville, Fla). Controls were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa). Each group of mini-screws was divided into three groups: the control (n = 10) and two test groups (n â=10, each). Test groups were cycled five and 10 times respectively. All screws were inserted into custom-designed synthetic blocks that simulated mandibular bone. Maximum insertion torque and lateral displacement force data were recorded and subjected to statistical testing. Two-way analysis of variance (ANOVA) and three-way mixed ANOVA were used for statistical analyses for maximum insertion torque data and lateral displacement force data, respectively. Level of significance was established at P < .05. RESULTS: Insertion torque values displayed significant differences between both of the groups and sterilization cycles (P < .05). Significant differences were observed between American Aarhus mini-screws and both RMO and KLS Martin mini-screws. Ormco Vector mini-screws also differed significantly from the KLS Martin mini-screws in this comparison (P < .05). For lateral displacement, there was a significant main effect of groups, F(1,36) = 14.5 (P < .05). Significant differences were observed between American Aarhus mini-screws and all three of the other groups (P < .05). CONCLUSIONS: The examined groups displayed statistical differences of variable quality that may not affect their clinical stability.
Asunto(s)
Tornillos Óseos , Métodos de Anclaje en Ortodoncia/instrumentación , Esterilización/métodos , Fenómenos Biomecánicos , Fuerza Compresiva , Aleaciones Dentales/química , Humanos , Mandíbula/anatomía & histología , Mandíbula/cirugía , Ensayo de Materiales , Modelos Anatómicos , Diseño de Aparato Ortodóncico , Resistencia al Corte , Vapor , Estrés Mecánico , Resistencia a la Tracción , Titanio/química , TorqueRESUMEN
BACKGROUND: 3D cone beam imaging allows localization of impacted canines, using spatial relationships, with excellent tissue contrast. The aim of this project was to assess the degree of difficulty for the treatment of impacted canines, based on the 3D information provided by cone beam imaging. METHODS: 3D cone beam images taken from subjects with impacted canines were obtained from a private practice and school setting. RESULTS: A novel measuring scale was devised, based on three different viewpoints, in order to grade the difficulty of impaction and the potential efficacy of treatment. Depending on its anatomical location, the cusp tip and the root tip are each given a number 0-5 in three dimensions taken from a pretreatment image. The sum of the cusp tip and root tip scores in the three views dictated our anticipated difficulty of treatment. CONCLUSIONS: A novel method of analysing impactions using cone beam imaging was proposed. This method utilizes the entire three views of a CBCT image.