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The reaction of previously traumatized teeth to orthodontic force application was investigated. Four groups of children were examined: group T comprised 56 children who encountered trauma to their maxillary incisors; group O comprised 29 orthodontic patients with intact incisors; group TO comprised 28 previously traumatized orthodontic patients; and group C served as the control group (n = 26). Orthodontic treatment was restricted to tipping movement executed only by means of removable appliances. Groups T, O, and TO were followed up longitudinally by means of clinical and radiographic examinations. In most of the cases the reported trauma occurred to teeth with completed roots and affected the crown only. Group TO presented the highest, though relatively moderate, prevalence of root resorption (27.8 per cent) and was followed by groups O and T (6.7 and 7.8 per cent, respectively) while in the control group no resorption was observed. Electrical pulp testing revealed the highest prevalence of loss of tooth vitality in group TO (7.3 per cent) in which the highest prevalence of pulp obliteration was also found. It can be concluded that the combination of trauma with orthodontic tipping renders the teeth more susceptible to complications, especially to root resorption and loss of vitality.

Morphological and functional aspects were investigated in children with unilateral posterior cross-bite (UPXB) before and after treatment. Sixty-five patients with Class I malocclusion with UPXB in the mixed dentition stage (mean age 8.8 +/- 1.6 years) served as the experimental group and 10 children of comparable age, with normocclusion or very mild Class I malocclusion (without UPXB) served as controls. The morphological aspects were examined on a longitudinal basis while the functional recordings, by means of a sirognathograph, were performed in a cross-sectional fashion. Complete elimination of cross-bite was maintained in 61 per cent and was accompanied by a dramatic reduction in the prevalence of functional mandibular displacement. However, the prevalence of mandibular midline deviation related to the maxillary midline as recorded in the intercuspal position was not affected. In addition, the high prevalence of Class II subdivision relationships which accompanied the UPXB in the intercuspal position was resolved in 50 per cent of the cases only. The sirognathographic recordings of the masticatory pattern showed a very high prevalence of a 'reverse sequencing' type pattern before treatment which was significantly lower following the elimination of UPXB, but still notably higher when compared with the controls. Reasons for these results are suggested and possible inter-relationships between the morphological and functional aspects are discussed.

Increased overjet and inadequate lip coverage of the maxillary incisors are considered significant risk factors in many clinical studies. The purpose of the present study was to examine this issue of dental injury by actual cephalometric measurements in orthodontic patients. Pretreatment cephalograms (taken with lips in repose) of consecutive patients were used. The patients were allotted to two groups Group T (trauma): 56 patients who had injured their maxillary incisors prior to their orthodontic treatment, mean age at the start of treatment 11.9 years (SD = 1.5); and Group C (control): 98 patients with intact maxillary incisors, mean age at the start of treatment 11.6 years (SD = 1.3). Twelve cephalometric landmarks on the soft and hard tissue profile were identified and digitized and the relevant dental, skeletal and soft tissue measurements recorded. The variables in Groups T and C were compared and their predictive values for possible occurrence of trauma were tested by logistic regression analysis. No statistically significant differences between boys and girls were found. Overjet or maxillary incisor exposure or interlabial gap, each as a single variable, could differentiate between the two groups. Logistic regression analysis indicated that only a small percentage (28.7%) of the dependent variable variation (trauma vs control) can be explained by interlabial gap, gender, upper incisor long axis to facial plane (degree), upper incisor long axis to interlabial gap and overjet.