Journal of Orthodontics

To assess applicability of the Tanaka–Johnston and Moyers prediction methods in a Han ethnic group from Northeast China and to develop prediction equations for this same population.

Cross-sectional study.

Department of Orthodontics, School of Stomatology, Jiamusi University, Heilongjiang, China.

A total of 130 subjects (65 male and 65 female) aged 16–21 years from a Han ethnic group of Northeast China were recruited from dental students and patients seeking orthodontic treatment. Ethnicity was verified by questionnaire.

Mesio-distal tooth width was measured using Digital Vernier calipers. Predicted values were obtained from the Tanaka–Johnston and Moyers methods in both arches were compared with the actual measured widths. Based on regression analysis, prediction equations were developed. Results: Tanaka–Johnston equations were not precise, except for the upper arch in males. However, the Moyers 85th percentile in the upper arch and 75th percentile in the lower arch predicted the sum precisely in males. For females, the Moyers 75th percentile predicted the sum precisely for the upper arch, but none of the Moyers percentiles predicted in the lower arch.

Both the Tanaka–Johnston and Moyers method may not be applied universally without question. Hence, it may be safer to develop regression equations for specific populations. Validating studies must be conducted to confirm the precision of these newly developed regression equations.

The aim of this study was to assess the amount of torsional play in 32 commercially available self-ligating and conventional 0·018-inch and 0·022-inch bracket systems in relation to 0·017×0·022-inch and 0·019×0·025-inch stainless steel wires, respectively, and compare the results with the theoretical amount of play for the given bracket/wire combinations.

Torque moments were measured in a mechanical force testing system by twisting straight pieces of stainless steel wire seated in the bracket slot in increments of 0·5° until a full torsional expression was registered. Five upper central incisor brackets from each of the 32 different bracket systems were selected for the study.

The result from the laboratory testing clearly showed that wire/slot play was larger than anticipated from the nominal values, especially regarding the 0·022-inch brackets and particularly in relation to the passive self-ligating brackets. The play ranged from 19·8 to 36·1° of play for the most imprecise bracket system.

The result does not favour the use of self-ligating brackets when focussing on torque control. The actual play is larger due to oversized slots and the inability of self-ligation brackets to press the archwire into the bottom of the slot. In conventional brackets, the initial torque moment is generated by the steel ligatures pressing the arch wire against the bottom of the slot. The oversize of the slot is thus less critical in relation to the conventional than in relation to the passive self-ligation bracket.

Orthodontic appliances are known to cause patients difficulty with eating. Learning more about the issues patients face, while eating with orthodontic appliances in place, will allow us to create more informative and relevant patient information, thereby improving patient compliance and treatment success. This study aims to understand how orthodontic appliances impact on eating in the broader context and to explore adolescent patients’ perceptions of eating with orthodontic appliances.

Purposive sampling was used and 19 participants currently undergoing orthodontic treatment and aged 11–14 years were selected for either a focus group or semi-structured interview to explore eating-related issues. Data collection and analysis were carried out as an iterative process broadly following principles of thematic analysis. Data collection ceased when no new themes emerged.

Two main themes relating to eating problems emerged: restriction of food choice and problems associated with the eating process. Participants reported restricting food choice due to physical aspects of the appliance, advice given by their orthodontist, fear of breakage and also to minimize embarrassment. Participants also reported problems with the time taken to eat, chewing problems, taste change and being messy while eating. Additionally, time in treatment, the location of eating and relationship with those present during eating influenced emotions. Some participants indicated a positive impact of orthodontic appliances on their diet.

These results can be used to further inform dietary advice offered to patients. Factors were identified which may not be considered in clinical practice but which could improve the value of dietary advice given to patients.

New methods of teaching and learning are constantly being sought in the adult learning environment. Audience Response Systems (ARS) have been used in many different learning environments, especially in the field of medical education. The objective of this investigation was to ascertain the effect of ARS use in undergraduate teaching in a UK dental school.

A cross-over clustered randomized educational trial.

Leeds Dental Institute.

Year 4 undergraduate dental students in orthodontics.

Students at Leeds Dental Institute were taught two different topics within the curriculum to test the use of ARS in a cross-over trial. A questionnaire was delivered to the test (ARS) and control (non-ARS) groups.

The response rate to the questionnaires was 89·5% (test group) and 82·9% (control group). The ARS enabled students to perform better as shown by knowledge retention (P = 0·013). Students found the seminar more interesting (P = 0·013), easier to concentrate (P = 0·025) and easier to participate in (P = 0·020) when ARS was used. When ARS was used, students were more able to answer questions (P<0·0001), were more likely to prepare for the seminar (P<0·0001) and significantly preferred using ARS (P<0·0001).

ARS was found to significantly improve student concentration and participation in small group seminar teaching and significantly improved knowledge retention. ARS may be useful in facilitating orthodontic teaching in the future.