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The purpose of this report is to compare a Swedish so-called normal material (Thilander et al.1983) with previously presented normal materials of Scandinavian origin and with standards for parameters in some frequently used roentgencephalometric systems. The material comprises Swedish children and young adults who fulfil special criteria of normal occlusion and harmonius skeletal relations and in whom roentgencephalometric data were collected. Parts of the material here reported are designated the 10-, 13- and 16-year-old groups. Comparison of the cephalometric data for the age-group 10 years in our material and a previously presented Norwegian normal material (Humerfelt 1970) showed remarkably good agreement for both angular and linear measurements in both sexes. Good agreement was also found between angular measurements in the 16-year-old group and those presented by Werner(1954) for Swedish 13-16-year-old children, but there seem to be differences for certain mandibular parameters. Comparison with data for 12-year-old Swedish boys with varying occlusion, presented by Björk(1947), reveals differences for several angular mandibular measurements. The highly significant differences between the linear measurements in the two materials are probably partly explained by age differences but also tend to corroborate the indications of differences in skeletal pattern suggested by the angular measurements, which are due to the selection criteria. Finally, comparison with the Bergen norms for the straight face (Hasund 1973) shows that the agreement is generally acceptable for angular measurements and the standards may be considered sufficiently reliable for use in clinical orthodontics. They should be supplemental with the age-related variations, however.

The purpose of the study was to evaluate the result in adults of Class I malocclusion cases who had all their first premolars extracted as the sole treatment of space deficiency in the mixed or early permanent dentition. The mean age at premolar removal was 10 1/2 years. Forty-two out of 44 cases were re-examined at a mean age of 30 years and 4 months. Observations of dental occlusion and oral health were compared to observations of control samples. The average malocclusion in the adults, as judged by a score method, was similar to that reported for an appliance-treated sample. Marked spontaneous arch alignment and residual space closure with age was seen in most cases. Despite earlier tooth removal, on average crowding developed to about the same degree as that of an non-extraction normal occlusion sample. No detrimental effects were seen with regard to overjet or overbite. Neither did the figures for lower incisor position at the follow-up examination differ from that of the normal occlusion sample. Although tipping of adjacent teeth towards the extraction site was frequent, especially in the mandible, no effect on marginal bone height was evident as judged by comparison with a non-extraction control sample. The results reveal a significant capacity for spontaneous improvements with age in dental arch morphology and relationship in extraction cases, provided that specific features have been looked for in case selection.