Journal of Orthodontics

The mandibular growth and dysfunction in a patient who has been unsuccessfully treated for a severe functional cross-bite are analysed clinically, electromyographically and cephalometrically. The analysis showed that although the occlusal dysfunction was present throughout the active growth period no asymmetric condylar growth changes occurred. The dento-alveolar process was, however, affected by the abnormal mandibular function. Orthodontic treatment of functional cross-bite should be carried out early so that growth may proceed in harmony with a balanced occlusion.

1147 children aged 11–12 years were examined to determine the mean overjet values relative to five defined postural lower lip/maxillary central incisor relationships.

A mean overjet of 3·025 mm was found in those children having a postural lower lip position related to the middle third of the maxillary central incisor; and those having no lower lip cover had a mean overjet of 4·26 mm. In contrast, the mean overjet value was 9·18 mm for those children having a “negative” lip position.

The observed differences between the mean overjet values relative to each lower lip position are statistically significant, but the only lower lip/maxillary central incisor relationship which appears to have any marked clinical significance is the one defined as—1 (i.e. the trapped lower lip).

In the interest of further clarification of the interaction of the multiple causative factors of upper incisor retroclination, the development of Class II Division 2 occlusion is contrasted to that of Class I. The patients whose records were used had not received orthodontic treatment.

It was found that upper incisor retroclination in Class II Division 2 occurred after their emergence into the oral cavity. The effect is attributed to the upper incisors being able to erupt well within the cover of the lower lip through a combination of circumstances related to the proportional balance of the patient's facial structures in the vertical dimension.

The lower lip would guide the upper incisors into retroclined positions, only if the latter were unobstructed by digit, tongue or other teeth of either arch.

This implied not only a critical balance in size and relationship of the facial structures in the vertical dimension but also equally critical balances in the antero-posterior and lateral dimensions, without which the lower lip factor alone would be ineffective.

This is the first article of a two part series in which it is proposed to discuss methods of uprighting lower second molars. In the present article control of second molars following extraction of first molars will be discussed. A subsequent article will describe the uprighting of second molars when the first molar is still present.

The prevalence of the unerupted maxillary canine is discussed. Three methods of surgical treatment to move the tooth into a functional position are mentioned. Surgical repositioning and transplantation are described. The method used by the author for transplanting and splinting the tooth is shown to differ in several important respects from those described by others.

The consistency with which two examiners were able to carry out a number of orthodontic assessments has been examined. Occlusal assessments were generally found to be the most reliable and assessments of soft tissue factors the least reliable. The implications of errors in orthodontic diagnostic assessments are discussed.

Comparisons were made between a group of 45 subjects with impacted lower third molars and a group of 50 subjects whose lower third molars had erupted, by means of various measurements made on cephalometric radiographs. Both these groups formed part of a longitudinal study of third molar development. Examination of the impacted group showed three different ways in which impactions could develop.

Sixty-three females (32 under 10 years and 31 over 16 years of age) were studied in order to investigate whether the soft tissue profile gave a reliable indication of the underlying skeletal profile. It is concluded that for a clinical assessment, the soft tissue profile may be used to estimate the skeletal pattern.

The results of an analysis of treatment and post-treatment changes in 48 unselected Class II Division 1 malocclusions are presented. All the cases were at least 1 year out of retention (mean 34·7 months).

Mean values have been given for several features. In particular, the mean overjet reduction during treatment was 7·0 mm, the mean relapse 1·1 mm and the mean net overjet reduction 5·9 mm.

The relationship of “final” overjet to overbite, overjet, skeletal pattern and lower lip height at different stages of treatment is described. There is wide variation in “final” overjet in relation to any of the single factors investigated but five significant correlations were found.

An unusual position of upper third molars seen on routine orthodontic radiographs is described. These may be unilateral or bilateral and suggestions are made for further investigations and observations.