The hypothesis was rejected. Both the orthodontists and dental students preferred broader smiles to medium or narrow smiles.

The aim of this study was to evaluate the influence of the amount of gingival display on smile aesthetics as assessed by Japanese orthodontists and dental students. A coloured photograph of a smiling female, displaying the first molar to first molar, whose upper lip was tangent to the upper gingival margin of the upper central incisors (zero point), was constructed from different subjects. Gingival displays were modified by moving the teeth within the lip frame in 1 mm increments, from -5 to 5. Using a visual analogue scale (VAS), 31 Japanese orthodontists and 55 Japanese dental students rated the attractiveness of the 11 smiles with altered gingival display. There was no significant difference when judging the effects of the gingival display on the smile attractiveness between the male and the female raters for both the orthodontists and dental students. Kruskal-Wallis tests revealed significant differences in the median aesthetic scores for both the orthodontists and dental students. For the orthodontists, the median aesthetic score increased gradually from -5 to 0 mm and then decreased from 0 to 5 mm. In particular, it decreased to become clinically significant (15 per cent VAS difference) from 0 to 3 mm. For the dental students, the median aesthetic score increased gradually from -5 to -2 mm and then decreased from -2 to 5 mm. The dental students were less tolerant of a more 'gummy' smile than the orthodontists.

No abstract

The aims of this study were to determine Japanese cephalometric norms in the antero-posterior and vertical dimension, and to test the hypothesis that there are racial differences in cephalometric measurements between Japanese and Caucasian norms. Radiographs were obtained from 25 healthy Japanese males (aged 25.1 +/- 2.7 years) and 24 healthy Japanese females (aged 23.6 +/- 1.3 years). Inclusion criteria were an ANB angle between 2 and 5 degrees, a normal occlusion with minor or no crowding, all teeth present except third molars, no previous orthodontic treatment, and no prosthetic replacement of teeth. Two angular and five linear measurements were constructed for the skeletal hard tissue analysis, one angular and six linear measurements for the dental hard tissue analysis, and two angular and seven linear measurements for the soft tissue analysis. The mean and standard deviations for the hard and soft tissue measurements were determined for each gender. Unpaired t-tests were used to determine the mean differences for each cephalometric measurement between the Japanese and the Caucasians. In the antero-posterior dimension, the Japanese subjects had a significantly more retruded chin position (P < 0.001), typically protruding mandibular incisors, and protruded lip positions compared with the Caucasian norms. In the vertical dimension, the Japanese had a significantly steeper mandibular plane (P < 0.01). The Japanese females had a significantly larger lower face height and increased dental height (P < 0.001). The results of this study suggest that these cephalometric measurements might be helpful to formulate treatment plans for Japanese patients.

Aim: To estimate the changes in the lip with the retraction of anterior teeth in orthodontically treated patients. Objective: To study the amount the amount of changes seen in the upper lip with the various degrees of retraction of the upper anterior teeth in patients under orthodontic correction. Background: In orthodontic treatment the correction of anterior teeth proclination is carried out by creating space with extractions. With the retraction of the proclined anterior teeth, the lip which is in close contact with it also undergoes changes based on the degree of retraction. This study aims to analyse the various changes of the lip with the changes in anterior teeth position. Materials and method: Pre-and post-treatment cephalogramsof 41 patients who have undergone correction of class I or class II division I malocclusion is collected and traced manually and analysed cephalometricallyfor this study. Result: Positive correlation between the retractions of the upper lip following the upper teeth retraction is seen in an average of 0.51 cases. Negative correlation i.e. increase in the lip thickness with the retraction of upper anterior teeth is seen in an average of 0.29 cases and no changes are seen after the anterior teeth retraction in average of 0.19 cases.

No abstract

These results suggest that, when we formulate a treatment plan, we should ask the patients about lip position before we start treatment.

The purpose of this retrospective study was to investigate the relationship between the unilateral temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA), mandibular asymmetry and electromyographic (EMG) activity of the masticatory muscles. Twenty-two Japanese women (aged 23.2 +/- 5.4 years) and 10 Japanese men (aged 22.4 +/- 2.8 years) exhibiting unilateral TMJ OA were included in this study. Two angular and seven linear measurements were obtained for the analysis of the skeletal hard tissues. The cephalometric measurement values (CV) were normalized using the CV ratio for the evaluation of the degree of mandibular asymmetry. The EMG was recorded during maximal voluntary clenching efforts for 10 s in the intercuspal position. The average values of integral EMG (iEMG) of three trials were normalized using the iEMG ratio for the evaluation of the functional balance of the masticatory muscles. The mandibular midline was shifted to the TMJ OA side with a median value of 9.85 mm. The CV ratio of the ramus height of the TMJ OA side was significantly smaller than that of the non-OA side. For the masseter muscle, the iEMG ratio of the TMJ OA side was significantly larger than that of the non-OA side (P < 0.05). These results suggest that unilateral TMJ OA is related to the dentofacial morphology, thus resulting in a mandibular midline shift to the affected side and it is associated with a masticatory muscle imbalance.