A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

Comparison of retention characteristics of Essix and Hawley retainers / 대한치과교정학회지

OBJECTIVE: We aimed to compare the retention characteristics of Essix and Hawley retainers. METHODS: Adolescents undergoing fixed appliance treatment at 2 centers were recruited for this study. Twenty-two patients (16 women and 6 men) wore Essix retainers (Essix group) while 20 (14 women and 6 men) wore Hawley retainers (Hawley group). The mean retention time was 1 year, and the mean follow-up recall time for both groups was 2 years. Two qualified dental examiners evaluated the blind patient data. Maxillary and mandibular dental casts and lateral cephalograms were analyzed at 4 stages: pretreatment (T1), post-treatment (T2), post-retention (T3), and follow-up (T4). RESULTS: The results revealed that Essix appliances were more efficient in retaining the anterior teeth in the mandible during a 1-year retention period. The irregularity index increased in both arches in both groups after a 2-year post-retention period. The mandibular arch lengths increased during treatment and tended to return to their original value after retention in both groups; however, these changes were statistically significant only in the Hawley group. Cephalometric variables did not show any significant differences. CONCLUSIONS: The retention characteristics of both Essix and Hawley retainers are similar.

Late development of a mandibular second premolar / 대한치과교정학회지

In this report, we present the case of a girl with delayed odontogenesis of a lower second premolar for which she was followed up for 8.5 years. Congenital absence of permanent mandibular second premolars was observed at the initial radiographic examination at 8 years and 1 month. One year later, during the treatment period, an unexpected odontogenesis of a right second premolar was diagnosed on follow-up radiography. The original treatment plan was revised and a new plan was successfully implemented. Th is unusual case showed that the orthodontist's clinical philosophy must be flexible because unexpected situations can arise, especially when treating growing patients.

Effects of direct and indirect bonding techniques on bond strength and microleakage after thermocycling / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the shear bond strength (SBS) of brackets and microleakage of a tooth-adhesive-bracket complex bonded with a direct and an indirect bonding technique after thermocycling. METHODS: Fifty non-carious human premolars were divided into two equal groups. In the direct bonding group a light-cured adhesive and a primer (Transbond XT) was used. In the indirect-bonding group, a light-cured adhesive (Transbond XT) and chemical-cured primer (Sondhi Rapid Set) were used. After polymerization, the teeth were kept in distilled water for 24 hours and thereafter subjected to thermal cycling (500 cycles). For the microleakage evaluation, 10 teeth from each group were further sealed with nail varnish, stained with 0.5% basic fuchsin for 24 hours, and examined under a stereomicroscope. Fifteen teeth from each group were used for SBS testing with the universal testing machine and adhesive remnant index (ARI) evaluation. Data were analyzed using the Mann-Whitney U test, Chi-square test, and Fisher's exact test. RESULTS: There were no statistical differences on SBS and microleakage between the two bonding techniques. The indirect bonding group had a significantly lower ARI score. Bracket failures were obtained between enamel-resin interfaces. CONCLUSIONS: The type of bonding technique did not significantly affect the amount of microleakage and SBS.