Replantation of avulsed primary incisors: a risk benefit assessment.
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Parents of preschool children with avulsed primary incisors may request replantation. Although dental textbooks uniformly recommend that primary teeth not be replanted, some case reports advocate the procedure. This review of case reports identifies a number of pathological outcomes of replantation and provides information for clinicians and parents on the risks that may accompany replantation. (+info)
Location of the centre of resistance of the upper dentition and the nasomaxillary complex. An experimental study.
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The purpose of this study was to investigate the initial displacement of the upper dentition and the nasomaxillary complex as a result of different directions of force application, and to determine the initial centres of resistance for both the upper dentition and the nasomaxillary complex. A macerated human skull with a well-aligned upper arch was used as one experimental model and Araldit 208 as a substitute for the periodontal ligament (PDL). Specifically designed 'antenna-headgear' was developed in an attempt to create different points of force application to simulate high-pull and horizontal traction, and orthopaedic force magnitudes of 8 N were applied to the upper dentition and the nasomaxillary complex. Double exposure holography was used to measure the initial displacement. Reproducibility of the technique was tested and found to be reliable. According to the registered fringe patterns, the force application transmitted by the headgear resulted in complex displacement of facial bones. Pure translation of the maxilla and the upper dentition was observed when the force vector passed by in the area of the key-ridge. No obvious difference was found between the centre of resistance of the upper dentition and the nasomaxillary complex. The location of two different centres of resistance could not be confirmed by measuring initial displacements on this macerated human skull. (+info)
Craniofacial morphology of Japanese girls with Class II division 1 malocclusion.
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OBJECTIVE: To identify the craniofacial features of Japanese girls with Class II division 1 malocclusions. METHOD: One hundred and ninety lateral cephalometric radiographs were analysed, and the subjects whose age ranged from 7 years 6 months to 15 years 10 months were divided into three groups by their dentition: middle mixed dentition, late mixed dentition, and early permanent dentition. The mean values of 5 linear and 16 angular cephalometric parameters were compared with established Japanese Class I control values. RESULTS: Japanese girls with Class II division 1 malocclusion had a significantly small S-N-B angle (p < 0.001), short mandibular ramus (p < 0.05-0.001), and a large mandibular plane angle (p < 0.05-0.001). CONCLUSION: Japanese girls with Class II division 1 malocclusion had a high-angle facial pattern associated with the short mandibular ramus. (+info)
Temporal and spatial mRNA expression of bone sialoprotein and type I collagen during rodent tooth movement.
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To investigate the mechanism of bone formation during tooth movement, in situ hybridization was performed with digoxigenin-labelled RNA probes to detect bone sialoprotein (BSP) and type I collagen mRNAs in the dentoalveolar tissue of 72 Sprague-Dawley rats. An elastic band was inserted between the first and second right maxillary molars, and the teeth experimentally moved for 1, 3, and 7 days. The left first maxillary molar was used as the control. For the untreated molars, osteoblasts and osteocytes near the distal surface of the interradicular septum (IRS) expressed a high level of both BSP and type I collagen mRNAs, while cells on the mesial side of the IRS showed a low level of these mRNAs. For the first molars subjected to experimental tooth movement, a high level of type I collagen mRNA expression was found in the osteoblasts on the tension side of the IRS after 1 day of experimental tooth movement. A high level of BSP mRNA was detected after 3 days of experimental tooth movement. However, a negligible amount of both mRNAs was found in cells on the compression side. These results support the hypothesis that BSP may be involved in mineralization during physiological bone remodelling. On application of orthodontic force, osteoblasts were activated and induced to express BSP mRNA, which is involved in bone remodelling due to orthodontic force. In addition, response to the orthodontic force was observed in osteocytes. (+info)
Craniofacial growth and skeletal maturation: a mixed longitudinal study.
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The purpose of this study was to investigate the relationship between craniofacial growth and skeletal maturation. The material consisted of the cephalometric and hand-wrist film pairs of 35 males and 43 females (78 subjects) whose development was followed for a period of 4 to 7 years. The subjects were grouped according to their skeletal maturation. Their mean ages were: Group I 10.27, Group II 11.55, and Group III 14.79 years, respectively, at the beginning of the observation period. Intra- and inter-group differences were examined through paired t-tests, and Pearson correlation analysis was used to detect the relationship between craniofacial growth and skeletal maturation (percentage growth potential). The results show that the middle cranial base (T-W) maintained its stability in all pubertal growth periods. However, posterior cranial base length (T-Ba) increases significantly (P < 0.001) throughout the same period. There were similar increases in the vertical dimensions of the face and alveolar height throughout pubertal growth. Despite the intensified increases in both the sagittal and vertical directions, facial characteristics were constant in the sagittal direction. The skeletal development (percentage growth potential) has clearly been effective in the vertical facial development commencing in Group I and reaching its maximum level in Group II. However Cd-Go was the exception. (+info)
Morphological parameters as predictors of successful correction of Class III malocclusion.
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The aim of the study was to assess pre-treatment cephalometric parameters and measurements of the size of the apical bases as predictors of successful orthodontic correction of Class III malocclusions. Pre- and post-treatment lateral cephalograms and study models of 80 completed Class III subjects were examined to obtain 23 cephalometric parameters taken mainly from the analyses of McNamara and Schwarz, and to measure the size of the apical bases. Success of occlusal correction was evaluated as the percentage change of peer assessment rating score during treatment, which was used as the dependent variable in multivariate statistical analyses testing the predictive value of the parameters assessed. No improvement in the Class III skeletal pattern occurred during treatment and the treatment effects were confined to dentoalveolar changes. With the exception of the percentage midfacial length/mandibular length ratio, the net sum of maxillary and mandibular length differences, the mandibular ramus height/mandibular body length ratio and the gonion angle, most cephalometric parameters of pre-treatment craniofacial morphology assessed were poor predictors of successful correction of Class III malocclusions. Assessment of the size relationship of the maxillary and mandibular apical bases was the strongest predictor of occlusal correction achieved and may serve as a valuable diagnostic addition in the prediction of successful treatment outcome. (+info)
Functional regulator treatment of Class II division 1 malocclusions.
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This controlled retrospective study aimed to identify the contribution of skeletal and dental changes in the correction of Class II division 1 malocclusions using Frankel's functional regulator II (FRII), with reference to a concurrently recruited control group. One hundred and thirty-eight patients with Class II division 1 malocclusions were identified, those accepting treatment forming the study group and those declining treatment the control group. The study group (n = 70) were treated with a Frankel appliance. Pre- and post-treatment observation cephalometric radiographs were analysed and compared. Mean values for both skeletal and dental variables in the control group were remarkably consistent throughout the study period; however, this masked individual variations in this group. The skeletal variables in the study group that showed statistically significant differences from the control group were SNB, ANB, BaNA and ANS-Me, but none of these was sufficiently large to be regarded as clinically significant. Dental variables showed clinically and statistically significant differences, including a 10 degree reduction in UI-Max and 3.1 degree increase in LI-Mand. The Frankel appliance was thus found to be effective in producing desirable occlusal and dental changes in the majority of patients treated. (+info)
Maxillary unilateral molar distalization with sliding mechanics: a preliminary investigation.
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Fifteen patients, eight males and seven females with a mean age of 13.32 years, were selected for unilateral molar distalization. Dentally, all presented with a unilateral Class II molar relationship. The subjects were all in the permanent dentition with second molars erupted and with a well aligned lower dental arch. For maxillary molar distalization a new intra-oral appliance was developed, the Keles Slider, which comprised two premolar and two molar bands. The anchorage unit was a Nance button with an anterior bite plane. From the palatal side, the point of distal force application was carried towards the level of centre of resistance of the maxillary first molar. A Ni-Ti coil spring was used and 200 g distal force was applied to the Class II first molar. Lateral cephalograms were taken and analysed before and 2 months after molar distalization. The Class II molars were distalized bodily, on average, 4.9 mm (P < 0.001). Mesial migration of the Class II first premolars was 1.3 mm (P < 0.05), incisor protrusion was 1.8 mm (P < 0.05) and incisor proclination 3.2 degrees (P < 0.05). The overbite was reduced by 3.1 mm (P < 0.001) and the overjet increased 2.1 mm (P < 0.01). For stabilization, the corrected Class II unilateral molar relationship was maintained with a Nance button for 2 months. The results show that this newly developed device achieved bodily distal molar movement with minimum anchorage loss. (+info)