Abstract: Forty-nine individuals, aged 15–24 years, who had been out of retention for 3–8 years after treatment of distal occlusion with the Herren type of activator were examined for stability of the treatment results and the function of the masticatory system. The examination comprised measurements on dental casts of the overjet, overbite, molar relation and length, widths and relative space of the dental arches. Facial morphology was analysed from profile cephalograms and the function of the masticatory system by means of a questionnaire and a clinical examination. The treatment had brought about a substantial reduction of the overjet that was essentially stable after retention. The long-term effect on the overbite was slight. After retention, a partial relapse in the molar relation improvement achieved during active treatment occurred in the majority of subjects. The changes in upper arch widths were within the limits for normal growth. There were no marked changes in lower arch widths but the width between the lower canines tended to decrease. The dental arch lengths decreased and the crowding increased in both arches after retention. The morphology of the face at the follow-up examination was within normal limits except for a total facial retrognathism. The treatment had generally not brought about a lasting proclination of the lower incisors. The lip profile was also normal. The prevalence of symptoms and signs of mandibular dysfunction was in agreement with that found in random samples of untreated individuals. The prevalence of a large distance between the retruded contact and intercuspal positions of the mandible was high, however, indicating a functionally less statisfactory occlusion in part of the sample.

Abstract: The study models of a sample of 51 cases with Class II division 1 malocclusions treated in the General Dental Service in Scotland, were investigated and analysed with respect to the changes which had taken place in the overjet, overbite and incisor alignment. Residual spacing in the arches was also measured. Occlusal Index scores were calculated at the start and finish of treatment.The results suggest that only a limited measure of success was achieved; they indicate a need to improve orthodontic treatment standards.

Abstract: In order that relationships between dental irregularities and the caries and periodontal status of individual teeth can be examined, the STRAIT index (standardized technique for recording the alignment of individual teeth) was developed. Tooth position scores representing vertical relationship, rotation, mesio-distal inclination, displacement and radial relationship are recorded using three- or five-category scales. Contact point scores representing bucco-lingual and mesio-distal relationships are measured directly. These characteristics are recorded for each tooth in the dentition, together with overjet and overbite measures for maxillary incisors and canines. Repeat measurement of 50 sets of models was undertaken by two examiners in order to assess intra-and interreproducibility of the index. A formula for adjusted agreement was employed for analysis of the categorized variables, and reproducibility was typically 80 per cent or better. Analysis of the reproducibility of the continuous variables was based on calculation of root mean square values of the difference between data sets and t-tests. In the main, intra- and interreproducibility was within 0.5 mm. These levels of accuracy meet the requirements of the index and it has since been used in an investigation of 1000 subjects.

Abstract: A follow-up study of the effect of activator treatment on the incisors is presented. Much of the effect of activator treatment is due to movement of the incisors. It has been claimed that the upper incisors become retroclined, however, a proclination of the lower incisors may also occur and this has been regarded by many as a contra-indication, This aspect has been studied in a material consisting of 40 Angle Class II:1 cases treated with the activator. Mean age at the start of treatment was 11 years and at the end of treatment 12.5 years. Incisor position and inclination were recorded on radiographs taken before and after treatment. The results indicate a significant improvement regarding upper incisor position and inclination whereas the lower incisors had moved forward 2.6 mm and proclined 16° on average. A regression analysis suggested, however, that cases with proclined lower incisors prior to treatment underwent retroclination during treatment (p<0·001).Furthermore, 25 per cent of the patien...