The purpose of this study was to investigate the position of the mandibular foramen from deciduous (Hellman's stage IIA) to early permanent dentition (Hellman's stage IVA). Panoramic radiographs of 311 Taiwanese children were used. The results revealed that the distances between the mandibular foramen and ramus anterior plane were greater than those between the mandibular foramen and ramus posterior plane through all stages. The mean difference between them was the smallest (0.25 mm) in stage IIA and the greatest (1.18 mm) in stage IIIC. The distance from the mandibular foramen to the alveolar crest plane showed a little change from stage IIA (3.99 mm) to IVA (5.26 mm). The gonial angle had a negative correlation with the distances between the mandibular foramen and each mandibular border. Evaluation of the mandibular foramen from the oral aspect can be influenced by the degree of mouth opening.

Objective: To determine if there is an indicator on the lateral cephalometric radiograph that can be used for the differential diagnosis of severe obstruct sleep apnea syndrome and simple snoring in nonobese young male adults. Materials and Methods: The subjects were Taiwanese male patients with a complaint of snoring and/or sleep apnea, whose body mass index was less than 25 kg/m 2 and who were younger than 40 years old. Forty-six patients with severe obstructive sleep apnea and 36 patients with simple snoring were selected and underwent lateral cephalometric radiography, from which 24 linear and 34 angular measurements were calculated. Differences between the two groups were studied, and a discriminatory analysis was performed. Results: Soft palate length, mandibular body length, tongue size, and distance from the hyoid bone to the mandibular plane were significantly larger in patients with severe obstructive sleep apnea syndrome. Of the original grouped cases, 76.5% were correctly classified using these five variables. The position of the hyoid bone in simple snorers was near the straight line from the third vertebra to the menton, whereas the position of the hyoid bone in severe obstruct sleep apnea syndrome patients was far below the line from the third vertebra to the menton. Conclusion:The position of the hyoid bone relative to the line from the third vertebra to the menton can be used as an indicator for a diagnosis of severe obstruct sleep apnea syndrome in nonobese young male Taiwanese adults.

A retrospective study, using panoramic radiographs, was conducted on 152 Taiwanese (72 males and 80 females) to investigate mandibular third molar eruption and impaction. The following measurements were made: inclinations and mesiodistal crown widths of the mandibular molars, vertical and horizontal spaces between the distal surface of the second molar and the anterior surface of the ramus, lengths and widths of the mandibular ramus and body, the ramus inclination, the mandibular plane angle, and the mandibular gonial angle. Differences between non-impaction and impaction groups were studied, and the variables were analyzed with multivariate discriminatory analysis. Significant differences between the two groups were found; variables describing spaces between the anterior of the ramus and the distal of the mandibular second molar and tooth size appeared to be the primary contributors to the differences observed.

The purpose of this study was to compare the bond strengths and debonded interfaces achieved with light-cured resin-modified glass ionomer cement (RMGIC) and conventional light-cured composite resin. In addition, the effects of acid etching and water contamination were examined. One hundred human premolars were randomly divided into five equal groups. The mini Dyna-lock upper premolar bracket was selected for testing. The first four groups were treated with light-cured RMGIC with or without 15 per cent phosphoric acid-etching treatment and with or without water contamination preceding bracket bonding. The control samples were treated with the conventional light-cured Transbond composite resin under acid etching and without water contamination. Subsequently, the brackets were debonded by tensile force using an Instron machine. The modified adhesive remnant index (ARI) scores were assigned to the bracket base of the debonded interfaces using a scanning electron microscope. The bond strength and modified ARI scores were determined and analysed statistically by one-way analysis of variance and chi-square test. Under all four conditions, the bond strength of the light-cure RMGIC was equal to or higher than that of the conventional composite resin. The highest bond strength was achieved when using RMGIC with acid etching but without water contamination. The modified ARI scores were 2 for Fuji Ortho LC and 3 for Transbond. No enamel detachment was found in any group. Fifteen per cent phosphoric acid etching without moistening the enamel of Fuji Ortho LC provided the more favourable bond strength. Enamel surfaces, with or without water contamination and with or without acid etching, had the same or a greater bond strength than Transbond.