Attitudes and perceptions of adults towards orthodontic treatment in an Asian community.

A retrospective survey of 358 local Chinese adult orthodontic patients was undertaken to determine the motivating factors behind orthodontic treatment and the discomfort caused by fixed orthodontic appliances. From the completed questionnaires of 203 patients, the principal conclusions were that the improvement in dento-facial aesthetics following orthodontic treatment enhanced their self-confidence and self-esteem in a majority of patients; discomfort in oral soft tissues and teeth were transient and did not exceed 7 days; transient pain from teeth was experienced by 91% of patients and in 39% of these patients the discomfort to teeth was experienced with each new archwire or elastic force application. These results may be useful in relating discomfort levels to prospective orthodontic patients. It was also evident in the study that several cross-cultural differences existed in the attitudes of our patients compared to those reported in Caucasians.

Assessment of orthodontic treatment needs by teenagers in an Asian community in Singapore.

The purpose of this study was to determine (1) the preference of dental occlusion types among teenagers, and (2) their assessment of the necessity for orthodontic treatment. A total of 1189 teenagers (mean age 15.3 +/- 3.2 years) were asked to rank a series of colour photographs of seven occlusion types. Their ranking, in descending order of attractiveness, were as follows: Class I occlusion, anterior open bite, Class III occlusion, Class II occlusion, anterior spacing, anterior crowding and deep bite occlusion. The perceived need for treatment was found to be inversely correlated with the rank order of attractiveness. There appeared to be no statistical difference (P less than 0.05) in the perception for treatment among different racial and income groups. However, with the exception of anterior open bite and deep overbite occlusions, a statistically significant (P less than 0.05) greater number of females than males perceived a need for treatment. Assessment of occlusal disharmonies among teenagers could provide clinicians and health care personnel with an indication of the relative attractiveness among occlusion types and hence the establishment of treatment priorities.

Extremes in second molar eruption in two oriental patients.

Two cases are presented where the maxillary second molars were just erupting. The first was a Chinese boy of 8 years 2 months and the other, a Chinese boy of 17 years 4 months. These extremes in eruption time are unusual and do not appear to have been reported in the literature.

A ten-year follow-up case report following surgical correction of anterior open bite.

A case is reported whereby an anterior open-bite was treated with the Köle osteotomy in an adult Chinese girl. This study documents cephalometrically the post-treatment changes occurring in the dento-alveolar complex over a ten year follow-up period and describes the possible mechanisms contributing to the remarkable stability of the open-bite correction.

Malocclusion prevalence in an ethnic Chinese population.

Population norms derived from one ethnic group may not necessarily be valid and accurate for other ethnic groups. With the increasing number of ethnic Chinese immigrants in Australia, Europe, and America, it would be useful for dental practitioners to be informed about malocclusion prevalence among Chinese. This study was carried out on 1050 Chinese school children (aged 12-14 years) to assess both qualitatively and quantitatively certain occlusal features. The population was found to have a high incidence of Class III malocclusions compared with caucasians. However, the incidence of Class II malocclusions was quite similar to those reported in caucasians. Normal occlusions occurred in about 7 per cent of this population. Although this percentage was much lower than those reported in blacks, it was similar to those reported in caucasians. Crowding occurred in about 50 per cent of cases, which was slightly less than for those reported for caucasians. Increased overbites were also less common in this Chinese population compared with caucasians. Compared with caucasians, crossbites were also less frequent in this Chinese population.

A removable appliance to extrude teeth.

A simple removable appliance to effect minor tooth extrusion of anterior teeth is described and its use is illustrated. This technique uses a labial bow in conjunction with a composite resin button bonded to the labial surface of the tooth or teeth to be extruded.

Enamel stripping and the spring aligner appliance--an update.

Irregularity of the mandibular incisors in an otherwise good occlusion is quite common in young adult patients. Through use of enamel stripping in the incisor region, it is possible to create sufficient space to align the teeth with a mandibular sectional removable appliance, commonly known as the spring aligner. This article reviews the methods of enamel stripping and describes the author's preferred technique of enamel stripping and the various modifications of the spring aligner appliances that can be prescribed by the general practitioner to correct mandibular anterior crowding.

Head positioning and projection errors in submentovertex radiographic analysis.

This study examined the changes seen on the submentovertex radiograph when the head is not extended sufficiently. A human dry skull supported on a cephalostat was used to simulate head extension. The range of rotation tested was an under-rotation of the skull of 30 degrees to an over-rotation of 10 degrees in intervals of 5 degrees. The measured variables were the intercondylar axis angles, corpus lengths and condylar widths. The relationships between skull rotation and changes in these variables were determined. Three selected landmarks, the spinosa points (right and left) and the pogonion point of each radiograph were located and compared spatially with the same points on the ideal radiograph. The results showed that variation in skull rotation affects both linear and angular measurements significantly (P < 0.01). Landmarks further away from the axis of rotation are affected by distortion more than those nearer to it.

Lower incisor angulation differences in Class II division 1 malocclusions with and without full 'lip trap'.

A cephalometric study was designed to investigate whether a difference in lower incisor angulation exists in Class II division 1 malocclusion subjects with and without the presence of a lower lip trap. Chinese subjects (N = 40) with Class II division 1 malocclusions who demonstrated a complete lower lip trap were compared to an equal number of subjects with a partial lip trap. Intergroup comparisons of several cephalometric parameters indicated the presence of statistically significant differences in both the degree of lowe incisor proclination/retroclination (p < 0.01) and the magnitude of the overjet (p < 0.05). In the complete lip trap group, the lower incisor was more retroclined and the overjets were also statistically larger than the partial lip trap group.

Anterior crown dimensions and relationship in an ethnic Chinese population with normal occlusions.

Odontometric measurements of anterior tooth crown sizes in a Chinese sample of 85 Class I occlusions were similar to those published in the white population except for larger upper lateral incisors and smaller upper central incisors in Chinese. Sex differences in tooth sizes were seen only in the maxillary and mandibular canines while differences between antimeres were not significant. The Bolton ratios of our Chinese sample revealed a Bolton ratio of 77.89 +/- 1.62 for the combined mesio-distal widths of the six mandibular anterior teeth as compared to the combined mesio-distal widths of the six maxillary anterior teeth. Surprisingly, the Bolton ratio in our sample compared favourably with those originally published by Bolton although the interfacial angles, overbite and overjet relationships were statistically different.

The use of psychometric tests in the evaluation of patients presenting for orthognathic surgery--a preliminary report.

Psychological evaluation in some orthognathic patients may be necessary as the psychosocial stress of the deformity may lead to psychiatric morbidity such as depression or paranoid disorders. It is also possible for patients with underlying psychosis to present first to the dental surgeon for jaw correction. The use of several psychological tests appropriate for patients presenting with dentofacial deformities is discussed. Nine patients with skeletal malocclusions who were referred for psychiatric assessment are reported here. Three case vignettes are included to give an impression of the type of clinical situations where such an assessment may be helpful.

Changes in tongue and hyoid bone positions following anterior mandibular subapical osteotomy in patients with Class III malocclusion.

In a sample of 28 Chinese adults (aged 24.2 +/- 3.1 years) who underwent anterior mandibular subapical osteotomy for the correction of Class III malocclusions, the interaction among intermaxillary space, tongue position, and hyoid bone variables were quantified retrospectively using pretreatment and posttreatment lateral cephalograms. Lateral cephalograms taken at the early (5 to 7 days) postsurgical period showed that the intermaxillary space decreased. The hyoid bone also moved inferiorly, while the tongue was displaced posteriorly and superiorly. The late (2 years) postsurgical lateral cephalograms showed that the hyoid bone and tongue position normalized to the pretreatment positions. These changes demonstrate the ability of the hyoid bone and tongue structures to adapt to changes in the intermaxillary space following osteotomy.

Orthodontically induced microvascular injuries in the tension zone of the periodontal ligament.

A review of the literature pertaining to the histological and ultrastructural changes related to orthodontic tooth movement reveals that much attention has been devoted to the fibrillar and cellular components of the periodontal ligament (PDL). Although the vascular response to experimental tooth movement has been investigated, specific morphological and morphometric data on changes in the tension zone of the PDL microvascular system are lacking. The present investigation was conducted to study the ultrastructural vascular response in the tension zone of the PDL following a short-term extrusive force. Six 12-week-old male Porton rats were anesthetized and cannulated via the aorta after applying a 1-N extrusive force for 30 min to the right maxillary first molar. The contralateral molar served as a control in all animals. The apical portion of both the control and experimental PDL was prepared for TEM examination. In the experimental PDL, degenerative changes in the endothelial cell wall and incipient nuclear shrinkage were observed in about 30% of the postcapillary venules and 18% of the capillaries, whereas the arterial components were generally spared. Compared to the control PDL, these degenerative changes were significantly marked in the experimental PDL (p less than 0.01). The results of this study suggest that the postcapillary venules are the most vulnerable segment in the PDL microvascular system.

The orthodontic tooth positioner--an appraisal.

The tooth positioner is a one-piece, resilient appliance which may be used for finishing orthodontic cases. The appliance fills the free-way space, and covers the clinical crowns of all the teeth and about 3-mm of the buccal and lingual gingival mucosa. The positioner is constructed over a predetermined 'set-up' and fabricated from either rubber or plastic. This article reviews the literature and describes the author's method of manufacture and usage.

The reliability of computerized cephalometric soft tissue prediction following bimaxillary anterior subapical osteotomy.

The accuracy of predicting the results of orthodontic-surgical treatment following bimaxillary anterior subapical setback osteotomy was analyzed retrospectively. Comparisons of pretreatment prediction tracings of the lateral cephalograms with the 6-month postsurgical cephalograms of 38 patients showed that there was no statistically significant difference between the actual and predicted dentoalveolar setback in both arches. The computer-generated soft tissue predictions were generally accurate, with the exception of the horizontal position of the lower lip, which was underestimated, and, to a lesser extent, the vertical position of the upper lip, which was also underestimated. Computerized cephalometric prediction following bimaxillary anterior subapical osteotomy is sufficiently accurate to be of value to be used routinely in treatment planning for the horizontal upper lip prediction, but some modifications are advisable to obtain a more accurate horizontal lower lip prediction.