Journal of Orthodontics

The interrelationship between form, function and stomatologic health is unclear. However, tooth positions that prevent bacterial plaque removal may predispose towards periodontal disease. A frequent problem in adults is loss of posterior teeth with subsequent tip and drift of the molars. Occlusal trauma, if superimposed on gingival inflammation, can result in rapid tissue destruction. Therefore, an indication for orthodontic treatment is the restoration of normal axial inclination and tooth position so that bacterial plaque control may be effected. Simple orthodontic appliances may be used to restore the position of tipped molars. The benefits of orthodontic treatment, prior to the restoration of the posterior occlusion, are improvement in occlusal loading, improvement of periodontal health and simplification of prosthetic design and fabrication.

A system of differential rapid maxillary expansion is described. This method is particularly useful in patients with cleft lip and palate who have severe defects of lateral maxillary growth, since it enables the maxillary segments to be rotated so that intercanine width increases without a concomitant increase in the intermolar width.

Different groups, defined as morphogenetically homogeneous display an homogeneous morphology, grow alike and seem to respond alike to a given type of treatment.

A case is reported in which a modified activator has been used to correct a post-normal molar occlusion following removal of all four first premolars in a Class I (incisor) malocclusion

The cephalometric radiographs of 29 Class II division 1 cases treated with the Andresen appliance were assessed and compared with those of 19 untreated Class II division 1 cases. The findings do not support the opinion that the Andresen appliance influences the growth of the skeletal structures of the maxilla and mandible. The overjet was reduced by lingual tipping of the maxillary incisors, whilst the overbite was reduced by increased eruption of both the maxillary and mandibular molars. Associated with this was a small improvement in molar relationship. The amount of lower incisor proclination was also small, presumably due to the effectiveness of the acrylic capping in controlling their axial inclination.

Patterns of casual attenders at a teaching hospital over a 17-week period are analysed and show that fixed appliances are more prone to problems than removable appliances, and younger patients tend to break appliances more frequently than older patients.

The site prevalence and intra-oral density of Candidal organisms may be increased by local factors including prostheses. However, whether significant changes in Candidal carriage occurs with denture wearing is not clearly established. This study employed the imprint culture technique to assess the effects of fixed and removable orthodontic appliances on oral carriage, site prevalence and intra-oral density of Candida in adolescents. Moreover, alterations in plaque distribution were measured. Groups of 12–16 year olds without or wearing fixed and removable appliances were studied. Imprint cultures were taken from six intra-oral sites and colony counts recorded after 48 hours incubation on selective media. Plaque scores were recorded from non-appliance and removable appliance wearers. The prevalence of Candidal carriage in the groups was not significantly different being 46 per cent of non-appliance, 51 per cent of fixed appliance and 52 per cent of removable appliance wearers. However, the prevalence of Candidal recovery at some sites and Candidal densities at all sites were significantly increased in both fixed and removable appliance wearers. Thus orthodontic appliances may predispose to Candidal proliferation in oral carriers. However, the results do not permit the conclusion that appliances may change non-carriers of Candida to carriers. Plaque distribution was significantly altered in removable appliance wearers when compared with non-appliance wearers as a result of increases in palatal plaque scores. These findings again emphasize the particular need for oral hygiene instruction in patients wearing appliances or partial prostheses.

The force-displacement characteristics of three types of buccal-canine retraction spring to both horizontal (normal) and vertical displacements is derived from simple beam theory. The analyses are used to examine theoretically the effect of variations in the geometry of a given type of spring and also to compare the merits of three designs in terms of the force applied on activation, and their stability to vertical displacement. Experimental measurements on enlarged models of the force—displacement behaviour were in good agreement with the values predicted by the derived equations.