Daigo Komazawa

Evaluation of mechanical properties of esthetic brackets.

Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing.

Effects of different alveolar bone heights on the center of resistance of the maxillary and mandibular first molars: A 3-D finite element analysis study

A statistical analysis covering the past 10 years was carried out using new outpatients since 2001 in the Clinic of Orthodontics of Meikai University Hospital. The materials used in this study were obtained from 2739 patients who sought orthodontic treatment in our clinic. We recorded the monthly number of patients, genders, and chronological and dental ages at the initial visit, along with their addresses, patient referrals, chief complaints, public insurance coverage, and types of malocclusion. Female patients exceeded male patients by 1.9-fold. The most common average age range of the patients’ initial visits were 19–29 years, followed by 7–9 and 10–12. The rate of adult patients was 37.0%, and the most common Hellman’s dental age was IV A. A total of 77.4% of patients lived in an area of less than 20 km, and the largest number lived in Sakado city, where our hospital is located. We found that 66.4% of patients were referred from other hospitals and clinics. Most of these patients were referred from general private dental clinics (47.0%)or other clinics in our hospital (41.5%). The most common chief complaint was crowding, followed by mandibular protrusion and/or crossbite and maxillary protrusion. The rate of public insurance coverage was 20.3%, and patients with jaw deformities totaled 13.1%. Angle Classes I, II, and III were 29.2%, 42.2%, and 27.8%, respectively, showing that Class II patients totaled the highest rate. All these findings demonstrate how our clinics are based on the community’s dental health. An increased number of adult patients indicated the variety of patient characteristics.

Evaluation of children with habitual snoring and unilateral cleft lip and palate by Ricketts analysis—Relationship between craniofacial morphology and pharyngeal airway space

Our previous studies reported that habitual snoring children with unilateral cleft lip and palate (UCLP) had a large anterior facial height and narrow airway, but the sagittal position of maxilla and mandible did not differ from non-snoring children with UCLP. Also reported was an inverse relationship between the pharyngeal airway space and maxillary position in the sagittal dimension of habitual snoring children with UCLP. To further clarify the relationship between craniofacial morphology and pharyngeal airway space, the skeletal pattern was evaluated by Ricketts analysis. Lateral cephalograms of 12 UCLP children with habitual snoring (7.0 2.1 years old), 12 non-clefted children with habitual snoring (7.3 1.1 years old), and 12 non-clefted children without habitual snoring (7.4 0.9 years old) were examined. Habitual snoring children with UCLP had an inverse relationship between the lower pharyngeal airway space and the anterior position of maxilla and a positive relationship between the lower pharyngeal airway space and the mandibular position. In contrast, habitual snoring children without unilateral cleft lip or palate showed an inverse relationship between the upper pharyngeal airway space and the maxillary position, and a positive relationship between the upper pharyngeal airway space and the mandibular body size. Obtained findings by Ricketts analysis suggest a differential relationship between the lower pharyngeal airway space and the craniofacial morphology, and they provide useful information on the mandibular growth in habitual snoring children with UCLP.