RESUMO
BACKGROUND: Dilaceration is a rare dental developmental anomaly characterized by an abrupt deviation along the longitudinal axis of the root in which an angulation forms between the root and the crown. Here, we report on dilacerated bilateral maxillary central incisors in mixed dentition. CASE SUMMARY: A 10-year-old girl presented with a chief complaint of unerupted central incisors. An oral examination and radiography provided the basis for a diagnosis of dilaceration of the maxillary central incisors. After surgical exposure of the impacted teeth, a button with an attached chain was applied to the palatal surface of teeth 11 and 21. After 8 mo, a button was bonded to the labial surface of the crown to fix an elastic chain and move the teeth toward the maxillary arch. Finally, a fixed appliance was applied to tooth alignment to Class 1 malocclusion using a 0.019 × 0.025-inch nickel-titanium wire. After 3 years of follow-up, the clinical findings and radiographic assessment showed that the roots had developed with vital dental pulp and healthy periodontium, were acceptable aesthetically, and showed no resorption. CONCLUSION: The rare occurrences of dilacerated bilateral maxillary central incisors can be successfully treated through surgical exposure and orthodontics.
RESUMO
Custom-made GC-MS and GC-ECD in-situ measurement systems were established at the Shangdianzi GAW Regional station. From May 2010 to May 2011, the precisions for GC-MS and GC-ECD systems were 0.23% and 0.88%, respectively, and the HCFC-142b mole fraction during the observation period ranged from 21 x 10(-12) to 355 x 10(-12). The result of the independent-sample T test was P > 0.05, and there was no significant difference in HCFC-142b mole fraction measured by the two systems. The small difference of HCFC-142b mole fraction measured by GC-MS and GC-ECD might be associated with the different sampling time and precision of the two systems. A statistical filter of "robust local regression" was applied to separate HCFC-142b background and pollution data. The mean difference, median difference, 25 and 75 percent difference of background data measured by GC-MS and GC-ECD were all within the precisions. The pollution events captured by the two systems showed similar characters. Results from both systems showed a higher HCFC-142b level in summer and autumn than in winter. The pollution mole fraction of the two systems showed similar seasonal changes.
