Transversal dental arch dimensions in 9-year-old children born in the 1960s and the 1980s

A prospective 10-year follow-up dental cast study of patients with obstructive sleep apnoea/snoring who use a mandibular protruding device

Objectives

This 10-year prospective study aimed to measure and evaluate the teeth position and occlusion following 10-year nocturnal use of a mandibular protruding device (MPD) in subjects with obstructive sleep apnoea (OSA) or snoring.

Materials and methods

Seventy-seven consecutive patients diagnosed with OSA/snoring were treated with an MPD. Fabrication of dental casts with jaw registration indexes in the intercuspal position was carried out at baseline and at follow-up, a construction bite was made, and an MPD was fitted. At the 10-year follow-up, all subjects (n = 74) were invited to participate. The dental casts were analysed in a series of measurements.

Results

Sixty subjects were included in the follow-up examination-41 were still using the device and 19 had ceased using the MPD. The MPD users showed significant changes in all analysed variables-decrease of overjet (-1.8 mm), overbite (-1.5 mm)-except the mandibular intercanine width and the maxillary anteroposterior relationship. Subjects who had ceased using their MPD retained their initial values, with the exception of a decreased overbite. The MPD users also showed an increased number of subjects with mesio-occlusion and posterior infra-occlusion; those who had ceased using their MPD mostly retained their initial status.

Conclusions

Long-term nocturnal use of an MPD may cause both favourable and unfavourable occlusion changes, such as a decrease of the overjet and overbite or posterior infra-occlusion, and these changes may continue to develop during treatment with an MPD. Subjects with a Class III relationship may not be a suitable group for treatment with an MPD due to the mesial drift of the mandibular teeth.

Prevalence of dental features that indicate a need for early orthodontic treatment

The aim of the study was to establish the prevalence of dental features that indicate a need for early orthodontic treatment (EOT). A group of schoolchildren in the mixed dentition stage (7-11 years old) (n = 432) was clinically screened for indications for EOT. Over 1/3 of the youngsters (34.7 per cent) presented at least one of the indications for EOT: anterior and posterior crossbites (including edge to edge occlusion) were found in 9.5 and 23.3 per cent, respectively; Angle Class III was found in 3 per cent; increased overjet (≥7 mm) prevailed in 3.7 per cent and was significantly related to risk for dental trauma (P = 0.001); while oral habits were practiced by 10.9 per cent, open bite was found only in 6.5 per cent, both predominantly among girls (P = 0.006 and P = 0.012, respectively); impinging overbite was present in 5.2 per cent, mainly in boys (P = 0.006); crowding >5 mm was found in 6.9 per cent for the maxilla and in 6 per cent for the mandible. Loss of tooth material affecting tooth position was found in 15.3 per cent. Normal occlusal relationships were found in 10.9 per cent only. The findings indicate that almost 1/3 of the examined children in the mixed dentition stage require EOT. Sexual dimorphism was demonstrated for several occlusal features.

Malocclusion frequency in Swedish and immigrant adolescents--influence of origin on orthodontic treatment need

Sweden has become increasingly multicultural. In the year 2000, almost 25 per cent of the child and adolescent population was of foreign origin. Such a major change in demographics may lead to altered orthodontic treatment need in the community, with implications for planning appropriate levels of orthodontic resources. The aim of this study was to compare the frequency of malocclusion and orthodontic treatment need in 12- and 13-year olds of Swedish and immigrant background. The subjects, n = 493, were stratified into four groups according to family origin: (A) subject and both parents born in Sweden, and subject or at least one parent born in (B) Eastern Europe, (C) Asia, or (D) other countries. Registrations were based on available radiographs, patient records, and a clinical examination. Normative treatment need was based on a number of variables. Treatment need was expressed according to the dental health component (DHC) and aesthetic component (AC) of the Index of Orthodontic Treatment Need (IOTN). Group A exhibited the greatest space deficiencies and irregularities in the maxillary and mandibular anterior segments and also the greatest overjet. More primary molars had been extracted in groups B and C, with a positive correlation between early extraction of primary molars and retention of permanent successors. Self-assessed orthodontic treatment need, IOTN-AC, was highest in group A. For all four groups, the orthodontist's estimate of treatment need was significantly higher than the subjects' self-assessed need. This study confirms that, despite the change in demographics, variations in frequencies of malocclusion and treatment need among children of different cultural background are only minor and the overall orthodontic treatment need remains unchanged.

Craniofacial and dentofacial development in pigs fed soft and hard diets

INTRODUCTION

Several authors have found a correlation between reduced chewing activity and malocclusion. In animal experiments, it has been possible to correlate a diet of low chewing resistance to narrower arches, which predispose the subject to crowding and irregular teeth.

METHODS

In this study, 17 pigs were weaned at 5 weeks of age and divided into 2 groups according to diet and housing. The soft-diet, indoor group was housed in conventional pens, and the animals were fed aliquots of barley and oats with soya and a mineral-vitamin premix added. The food was mixed with water at a dry matter content of about 25%. The hard-diet, outdoor group was kept outdoors; the pigs were fed solid food and also ate organic matter in the soil. All pigs were killed at 22 months of age. The skulls were dissected, and transverse and sagittal craniofacial and dentofacial dimensions were measured.

RESULTS

Chewing hard food caused considerable occlusal and approximal attrition in the experimental animals. The dental arches were shorter due to this attrition and to mesial migration of the molars and premolars. The approximal attrition also reduced the tendency for crowding and rotation of the teeth. Posterior crossbite was more common among the hard-chewing animals.

CONCLUSIONS

The increase in arch width in the hard-diet animals reported in the literature was not duplicated in this study. On the contrary, the soft-diet pigs had significantly wider arches than the hard-diet animals. This was most pronounced in the premolar region and could be the result of an atypical tongue habit, caused by the nonphysiologic feeding of the pigs. The soft-diet pigs also had a greater tendency to postnormal occlusion, especially in the canine region.