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The aim of the present clinical investigation was to assess the effects of continuous and interrupted continuous forces of the same magnitude (50 cN≈50 g) on orthodontic tooth movement and related adverse tissue reactions, i.e., root resorption. Thirty-two maxillary first premolars in 16 patients, 8 boys and 8 girls (mean age 13.9 years), were moved buccally by means of a fixed orthodontic appliance with a sectional arch. The patients were divided into two groups of 8, for experimental periods of 4 and 7 weeks. The continuous force was checked and reactivated weekly to 50 cN. The interrupted continuous force applied to the contralateral premolars was left uncontrolled for 3 weeks, after which the arch was made passive for 1 week for tissue rest and recovery. Tooth movements were studied on dental casts using a coordinate measuring machine (Validator 100, TESA SA, Renens, Switzerland). Horizontal tooth movement with continuous force was more effective than with interrupted continuous force after 7 weeks. Histological sections of the experimental teeth, however, showed no difference in the amount or severity of root resorption between the two forces. Individual variations in both the magnitude of tooth movement and the amount and severity of root resorption for both of the two force systems were great.

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The aim of this investigation was to study the reparative potential of orthodontically induced root resorption. Sixty-four maxillary right and left first premolars in 32 patients (15 boys and 17 girls, mean age 13.7 years) were moved buccally with fixed orthodontic appliances and a continuous force of 50 cN (≈50 g), activated weekly for 6 weeks. The patients were divided into 4 groups of 8. Retention periods varied from 1 week to 8 weeks. Histological preparations showed that root resorption affected all the test teeth. The percentage of resorptive areas that had begun to repair ranged from 28% after 1 week of retention to 75% after 8 weeks. The healing cementum was almost exclusively of the cellular type. Partial repair, with the resorption cavity walls only partially covered with cementum, was the most frequent type of repair during the first 4 weeks of retention (17% to 31%). Functional repair, with the total surface of the resorption cavity walls covered with varying thicknesses of cementum, dominated after 5, 6, 7 and 8 weeks of retention (33% to 40%). There were no large differences in the healing potential in the cervical, middle, and apical thirds of the root. After 8 weeks, three out of four resorptive areas showed some degree of repair. Individual variations in healing potential were large.

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Increased overjet has been associated with teasing, negative stereotyping, and low self-concept. Early treatment for children with Class II malocclusion is often recommended under the assumption that an improved dental appearance may benefit a child by increasing his or her social acceptance and hence self-concept. The self-concept of 208 patients, age 7 to 15 years and with increased overjet, was measured before treatment using the Piers-Harris self-concept scale; a subset of 87 of these children were measured again after 15 months of early growth modification. The mean self-concept score for these children was above the population norm, and there was no association between the child's score and the magnitude of his or her overjet or age. Although some significant associations were found between Class II malocclusion features and self-concept scores, the explained variation in self-concept scores was low (R² from 5% to 8%). There was no change in the mean self-concept score of these children during early treatment, nor was there any association between reduction of Class II malocclusion features and improved self-concept. These findings suggest that children with Class II malocclusion do not generally present for treatment with low self-concept and, on average, self-concept does not improve during the brief period of early orthodontic treatment.

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The purpose of this study was to analyze the types and prevalence of malocclusions that remain to be corrected after a period of combined activator-headgear treatment. Study models of all patients who started treatment with an activator-headgear appliance in the graduate orthodontic clinic at the University of Oslo between 1972 and 1982 were screened. Patients initially judged to need a second phase of treatment and those later judged to have poor cooperation were omitted from the study. The results show that the most frequently remaining problems following activator-headgear treatment were overbite, overjet, and the presence of interdental spaces. Correction of the Class II skeletal and dental relationship was achieved in the majority of the cases. The only predictor for success was age at the time of treatment.

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The purpose of this study was to determine the changes in the soft tissue profile in patients treated in the mixed dentition with a bionator. Two groups of 30 individuals, between 9 and 12 years old and with Class II, Division 1, malocclusion were matched forage, sex, observation time, and dentofacial characteristics. Patients in the first group were treated with a bionator for an average of 18.7 months, resulting in a Class I molar relationship and reduction of overjet. The second group acted as a control and individuals did not receive any form of orthodontic treatment. Pretreatment and posttreatment cephalograms were analyzed and paired t-tests were used to compare the significance of changes between the two groups. Compared with the control group, the treated group demonstrated 1.97° decrease in ANB, a 3.35 mm increase in anterior facial height, 2.22° decrease in soft tissue profile convexity, and 17.4° increase in mentolabial angle.

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The aim of this study was to investigate stability and patterns of relapse tendency in 42 children in whom mandibular incisors had been proclined as part of orthodontic treatment. All patients were selected on the basis of their predicted anterior rotational mandibular growth pattern. Results were based on study casts and standardized cephalometric profile radiographs, registered before and after active treatment as well as after a postretention period.

Results demonstrate the clinical acceptability of the treatment principle employed in that the majority of the treatment changes were maintained well after the cessation of retention. There was, however, a general tendency to slight crowding in the mandibular incisor region in connection with bite deepening and reduction in intercanine distance. The reliability of prediction of mandibular rotation using the morphological criteria method is discussed.

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The orthodontic treatment need of 105 first year university students (51 males and 54 females, mean age 19.75 years) at the University of Hong Kong was assessed using the Occlusal Index (OI) and the Index of Orthodontic Treatment Need (IOTN). The results were compared with the subjects' orthodontic treatment demand derived from a questionnaire. The OI assessment correlated better with the individuals' own perceptions of appearance than did the IOTN, and the treatment need indicated by the OI also correlated better with the individuals' actual treatment demands.