Initial tooth displacement in vivo as a predictor of long-term displacement.
(1/20)
In the past, the dry skull has been used as a hypothetical model to test initial orthodontic and orthopaedic force systems. However, the question as to whether this hypothetical model can be used as a predictor of long-term displacements in vivo remains unanswered. In this study, an attempt was made to compare initial tooth displacement with the long-term effect after application of the force system for a longer period of time, in six adult dogs. Tooth displacement was obtained by applying a force by means of a coil spring (push) system. Following application of a force of 50 g in the first series (n = 3) and 80 g in the second series (n = 3), initial displacements were registered by means of speckle interferometry. The long-term displacement was registered by means of standardized cephalometry in the same dog by leaving the force system in place for 5 weeks. The mean values of the displacement vectors of the second premolars in the six dogs were compared. A paired t-test revealed no significant differences between the initial and long-term displacements in any of the dogs. The results show that both groups of measurements belong statistically to the same sample and that initial tooth displacement measured by means of speckle interferometry is a valuable predictor for forecasting long-term displacement in vivo after 5 weeks. (+info)
Longitudinal post-eruptive mandibular tooth movements of males and females.
(2/20)
Unbiased estimates of post-eruptive eruption and migration of the mandibular teeth for large representative samples are presently unavailable. The purpose of this study was to evaluate pure tooth movements of untreated children and adolescents longitudinally. Lateral cephalograms of 214 French-Canadians, followed bi-annually between 8 and 15 years of age, were traced, and the positions of the mandibular permanent central incisors and first molars were digitized. Temporal changes in tooth position were evaluated relative to naturally stable mandibular reference structures, using the mandibular reference line for orientation. The statistical analyses included t-tests to assess gender differences and Pearson product-moment correlations to evaluate associations. The results showed that the incisors proclined significantly more for males (6 degrees) than females (3 degrees). The incisor tips displayed early mesial movements that were countered by later distal movements. The incisor apex showed a consistent pattern of distal migration between 8 and 15 years. Mandibular arch length decreased over the 7-year observation period. Rates of mesial molar migration accelerated until 11 years of age and then decelerated. There was no significant change in the mandibular occlusal plane angle between 8 and 15 years of age. Incisor eruption showed the greatest rates during adolescence, attaining peaks at approximately 12 years for females and 14 years for males. The molars erupted approximately 5 mm between 8 and 15 years of age. The greatest gender differences occurred at the older ages, with males showing greater eruption potential than females. It was concluded that the mandibular teeth show significant migration and eruption during childhood and adolescence, with gender differences in the amount, direction, and timing of movement. (+info)
Mesio-marginal findings at tilted molars. A histological-histomorphometric study.
(3/20)
The aim of this study was to investigate the mesio-marginal findings at tilted molars (TM) by means of histological-histomorphometric evaluation. Eight lateral tooth bone segments with TM (six mandibular, two maxillary) from males aged 20-32 years were compared with those of eight samples with non-tilted molars (NTM) in males aged 18-35 years. In comparison with the NTM samples, the TM revealed a higher amount of supra- and subgingival plaque, a significantly higher total number of inflammatory cells (P < 0.05) and blood vessels (P < 0.05) in the connective tissue adjacent to the junctional epithelium, and a lower density and corono-apical width of gingival fibres. No significant differences (P > 0.05) were found between the mesio-marginal bone level of the TM (mean: 978 microns) and that of the NTM (mean: 1222 microns). In contrast, indications were found that TM may affect the disto-marginal bone level of the mesial tooth. (+info)
Unilateral distalization of a maxillary molar with sliding mechanics: a case report.
(4/20)
INTRODUCTION: A unilateral Class II relationship could arise due to early loss of an upper second deciduous molar on one side during the mixed dentition period. This would allow the mesial drift of the molars, which may block the eruption of the second premolar. METHODS AND RESULTS: A 15-year 8-month-old male patient presented with a Class II molar relationship on the right, and Class I canine and molar relationship on the left side. His E was extracted when he was 5 years old. The 54 were impacted and the 3 was ectopically positioned due to the space loss from the mesial migration of the 76. In addition 21 1 were in cross-bite. Skeletally he had Class III tendency with low MMPA. He presented with a straight profile and retruded upper lip. For maxillary molar distalization, a newly developed 'Keles Slider' was used. The appliance was composed of one premolar and two molar bands, and the anchorage unit was composed of a wide Nance button. 46 were connected to the Nance button and, therefore, included into the anchorage unit. The point of distal force application was close to the centre of resistance of the 6 and parallel to the occlusal plane. Ni-Ti coil springs were used and 200 g of distal force was applied. Seven months later the space required for eruption of the permanent premolars and canine was regained, and the anterior cross-bite corrected. The appliance was removed and final alignment of the teeth was achieved with fixed appliances. CONCLUSION: At the end of the second phase treatment Class I molar and canine relationship was achieved on the both sides, the anterior cross-bite was corrected, inter-incisal angle was improved, and ideal overbite and overjet relationship was achieved. The active treatment time was 27 months. (+info)
A randomized clinical trial to compare the effectiveness of canine lacebacks with reference to canine tip.
(5/20)
AIM: To assess the effectiveness of canine lacebacks on the proclination of the upper incisors with reference to pre-treatment canine tip. STUDY DESIGN: Randomized clinical trial. SAMPLE: Patients receiving upper and lower fixed appliances attending the orthodontic departments of five orthodontic treatment providers. Sixteen patients received canine lacebacks as part of their treatment and 19 patients did not have canine lacebacks. METHOD: Patients were randomly allocated to receive canine lacebacks or not receive canine lacebacks. Upper study models were collected at the initial archwire placement and then when the working 0.019 x 0.025-inch stainless steel archwire was placed. The start canine angulation, change in upper incisor proclination/overjet, and any mesial movement of the upper first permanent molars during levelling and aligning was measured with a reflex metrograph. STATISTICS: The effect of the use of canine lacebacks on upper incisor proclination and mesial molar movement was assessed using Student t-tests. Regression analysis was used to evaluate any effect of the initial angulation of the canine. RESULTS: A mean incisor retroclination of 0.5 mm was observed in the canine lacebacks compared with a mean proclination of 0.36 mm when canine lacebacks were not used (P = 0.025). There was no statistically significant difference between groups for mesial movement of upper first molars (P = 0.99). If the canine was more distally inclined at the start of treatment, the incisors was more likely to procline, regardless of whether or not canine lacebacks were used (P = 0.027). CONCLUSIONS: The effect of canine lacebacks on preventing upper incisor proclination at the start of treatment is in the order of 1 mm and their effect on mesial molar movement is insignificant. Canines lacebacks have similar effects that are independent of pre-treatment canine angulation. (+info)
Effects of a segmented removable appliance in molar distalization.
(6/20)
The aim of the present investigation was to evaluate the skeletal and dentoalveolar treatment effects of a segmented removable appliance [removable molar distalizer (RMD)] for molar distalization. The study was conducted on 28 patients (12 females and 16 males), with a mean age of 11.8 years. All presented with a skeletal Class I malocclusion and a bilateral dental Class II molar relationship. The pre- and post-distalization records included lateral head films, study models and standard photographs. The findings were evaluated with a paired samples t-test. The average maxillary first molar distalization with the RMD was 3.98 mm, with 4.61 degrees of distal tipping. The maxillary second premolars drifted distally 2.13 mm on average with 1.54 degrees of distal tipping, while the maxillary first premolars showed 1.23 mm of mesial movement and 1.98 degrees of mesial tipping. The incisors protruded 1.09 mm with 1.27 degrees of labial tipping. The RMD was effective in distal molar movement and all patients attained a bilateral Class I molar relationship in an average period of 4.5 months. Hygiene problems and mucosal irritations, frequently found with fixed intraoral distalization techniques, were not observed during the distalization period. (+info)
Transmigration of impacted lower canine. Case report and review of literature.
(7/20)
Retention, that is, a permanent tooth which is unerupted more than a year after the normal age of eruption, is a relatively rare event, except in the case of the third molars and the upper canines. Transmigration is defined as the phenomenon of more than half an unerupted impacted tooth crossing the midline. We report the clinical case of a twenty-year-old patient presenting transmigration of the lower left canine, with a type 4 transmigration pattern (Mupparapu). Likewise, we carried out a review of the literature of the cases that have been published on transmigration, updating the main aspects of this pathology. (+info)
Transmigration of impacted mandibular canines--report of 4 cases.
(8/20)
Impacted canines are not uncommon in clinical practice, but intraosseous movement of impacted canines crossing the midline (transmigration) is a rare phenomenon. We report 4 cases of mandibular canine transmigration to emphasize the need to supplement periapical radiographs with a panoramic radiographic examination in patients with over-retained deciduous canines or missing permanent canines. (+info)