Design: A questionnaire survey of children and their primary care-givers attending for their first consultation.

Setting: The Department of Orthodontics at the Academic Centre for Dentistry Amsterdam (ACTA), the Netherlands.

Subjects and methods: A total of 168 subjects (84 patients and 84 parents) completed the questionnaire. The children were aged 10 to 14 years. The responses of the children and parents and differences between boys and girls were examined using parametric statistical methods. The data from the Dutch sample were compared with a similar UK sample.

Results: Patients and parents shared similar expectations of orthodontic treatment, with the exception of expectations of having a brace fitted at the first appointment, orthodontic treatment involving headgear, any problems with orthodontic treatment, duration of orthodontic treatment and concerning reactions from the public. Among the child participants, boys and girls only differed in their expectations of orthodontic treatment involving jaw surgery. Differences between Dutch and English participants were found regarding the first visit, type of orthodontic treatment, reactions from the public, and pain and problems with orthodontic treatment.

Conclusions: Since the expectations of patients and their parents differ on several aspects, effective communication between the orthodontist, patient and parent is considered to be essential. Our hypothesis that Dutch patients’ and parents’ expectations of orthodontic treatment differ from the expectations of English patients and parents was supported.

Design: A longitudinal cephalometric study.

Setting: The Dental School of Paulista University, Brazil.

Participants: 36 subjects (21 females, 15 males) who were part of a longitudinal growth study and exhibited normal facial and normal vertical growth patterns.

Methods: Growth maturation of cervical vertebrae stages was assessed by two examiners independently. Cranial base measurements were carried out by one individual and repeated after one month. The growth increments over time were assessed with the one-way repeated-measures analysis of variance and post hoc Tukey multiple comparisions.

Results: There were no significant gender differences. There was a significant increase in all cephalometric measures between the different time points. Ba–Na showed the greatest amount of growth (mean change=2.8 mm). From T2–T3, the greatest amount of growth was found for Se–Na (mean change=3.4 mm) and the lowest for CC–Na (mean change=1.4 mm). Comparing overall changes (T1–T3) all the measurements showed statistically significantly increases (P<0.05). For all comparisons of between-stage changes the cranial base grew more than 2.0 mm during the pubertal growth.

Conclusions: Linear variables of cranial base showed significant growth during pubertal stages (pre-peak, peak and post-peak). No significant differences.

Design: In vitro study.

Settings: Department of Orthodontics, Faculty of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.

Materials and methods: Seventy-two human premolars were divided into three groups: Group 1 was not submitted to bleaching, Group 2 was subjected to one tooth bleaching (35% hydrogen peroxide enabled by LEDs) and Group 3 was subjected to two tooth bleachings interspersed by aging. Twenty teeth from each group were subjected to tensile test, failure pattern after debonding and evaluation of resin/enamel interface. Four teeth from each group were not submitted to tensile bond testing and had their external surfaces and internal structure analyzed by SEM and polarized light microscopy.

Results: The strength of the brackets decreased in Groups 2 and 3, but was not significant (P=0.635). In general, the failure pattern appeared at the resin/bracket interface or within the resin. The experimental groups showed an increase in slots and erosions on the surface of the enamel and were more pronounced in Group 3. There were no changes to the internal structure of the enamel.

Conclusions: The use of a 35% hydrogen peroxide in-office bleaching system, in vitro, seven days before bonding, does not significantly reduce the tensile force to debond orthodontic brackets, even after a second bleaching procedure. In most cases, debonding occurred at the adhesive/bracket interface or within the adhesive. Bleaching alters the enamel surface and the resin/enamel interface, but it does not influence bond strength.

Design: Cross-sectional study.

Setting: The Departments of Maxillofacial Orthognathics and Orthodontics, Tokyo Medical and Dental University.

Participants: Sixteen patients (5 males and 11 females, aged between 13.5 and 27.5 years) with various craniofacial skeletal patterns, who were about to start orthodontic treatment.

Methods: Lateral cephalometric radiographs and MRI scans were obtained and their images uploaded to a computer using a digitizer. The area of the medial pterygoid muscle was selected by binarization from the MRI. The mid-sagittal-plane MRI with a complete superimposed sagittal image of the medial pterygoid muscle was superimposed on the cephalogram using anatomical structures situated in the mid-sagittal plane of the head and shapes that could be identified from both the radiograph and the MRI image.

Results: These combined images showed various shapes of the medial pterygoid muscle. The inclination axis of the medial pterygoid muscle was correlated with various cephalometric variables including SNB (r=0.658), Facial angle (r=0.601), ramus inclination (r=0.676) and Ba-Po% (r=0.585).

The volume of the medial pterygoid muscle was also correlated with cephalometric variables such as ramus inclination (r=0.453), Ba-Nmm (r=0.676), Ba-Po% (depth) (r=0.447), Ar-Go% (depth) (r=0.444) and Ar-Go% (actual length) (r=0.532).

Conclusions: Morphometric analysis using a superimposed image of the medial pterygoid muscle produced from a cephalogram and MRI may help explain the influence of the medial pterygoid muscle inclination axis and volume on the shape of the mandibular bone, especially the shape of the ramus.

Design: Cross-sectional.

Source and setting: Dental, medical and nursing science students at the B.P. Koirala Institute of Health Sciences, Dharan, Nepal.

Subjects and methods: The sample consisted of 100 Nepalese males and 100 females aged between 17 and 23 years. Subjects without any previous orthodontic treatment, fully erupted permanent teeth and with no dental anomalies were recruited. Dental study models were taken and measurements of the mesio-distal widths of teeth were carried out using digital caliper. The measured values were compared with predicted values derived from Moyers method and Tanaka and Johnston equations. Independent t tests were used to examine differences between genders. Correlation coefficients and linear regression equations were used to compare the actual Nepalese tooth widths with predicted values

Results: Moyers method at 50% tends to underestimate the actual width of the canine and premolars in males by 0.3 mm and overestimate the width in females by 0.2 mm. The Tanaka and Johnston method tends to overestimate the actual width of the canine and premolars in both males (0.7 mm) and females 1.0 mm.

Conclusion: The newly developed regression equations are more accurate for prediction of width of unerupted permanent teeth in a Nepalese population. Further studies are required based on larger sample size, to confirm the applicability of the new regression equations proposed.