| Objective The formation of the black triangle after orthodontic treatment is related to various factors.Exclude other influential factors in this clinical experiment,the aim of the study is to investigate the effects of force direction on the formation of black triangle in anterior maxillary region in orthodontic treatments.This paper could be a theoretical basis for the prevention of black triangle.Methods Patients were chose from male patients who received orthodontic treatment between August 2015 to March 2016,and they are all patients with permanent teeth aged from 18 to 20 years old.In this study,we chose 96 dental class cases,including 48 maxillary incisors' protrusion cases,48 maxillary incisors' lingual inclination cases.Besides,we chose 30 patients with maxillary incisors' straight-wire appliance as control group.Before treatment,the head side slice was measured for all patients.Based on the results,48 cases with U1/NA>28.5° was allocated to the incisor lip dip group;48 cases with U1/NA<17.1° was allocated to the incisor tongue dip group;others with 17.1°<U1/NA<28.5° was allocated to incisor upright group.For all patients,they should have good compliance and good oral hygiene.And in orthodontic treatment straight wire arch correction technique was adopted.One dentist accomplished the treatment throughout the whole procedure,recording changes in the teeth and writing clinical record.Before the treatment the same dentist chose patients for clinical studies according to the standard to adopt patients.After the orthodontic treatment,patients would receive periodontal treatment in order to eliminate the influence that gingival inflammation caused by orthodontic treatment for fixed orthopedics and clinical operation may disturb the judgement of the occurrence of black triangle in anterior maxillary teeth after orthodontic treatment.Usually it takes about a month to get rid of gum inflammation.Hence we judged the occurrence of black triangle in anterior maxillary teeth one month after the orthodontic treatment.All measurement of all kinds of data during the whole treatment should be done by one same dentist.During the study,clinical data was elaborately collected,such as panoramic radiograph in pretherapy and post-treatment,lateral cephalometric radiographs,image of occlusion,models and medical records.Through statistically analyzing for the formation of black triangle in anterior maxillary region in pretherapy and post-treatment,the effects of force direction on the formation of black triangle in anterior maxillary region in fixed appliance was discussed in detail.Results Through the analysis of data collected before and after orthodontic treatment,we found that: compared with control group,the formation of black triangle in anterior maxillary region increased for maxillary incisors' lingual inclination patients(P<0.05),while it decreased for maxillary incisors' protrusion patients(P<0.05).For the former phenomenon,the teeth moved on to the lip dip when they were under the orthodontic force to the lip way,and it may cause gingival tissue to become thin and move toward the root of the tooth and the height of the gingival nipples to reduce.In this situation,the black triangle occurred more likely.For the latter phenomenon,it may cause the gingival tissue to thicken and move towards the jaw during the process of lip-dip teeth moving towards the tongue or adducting low to the inside,which helped to eliminate the black triangle a lot.Conclusion The formation of black triangle in anterior maxillary region increases when applying force to the direction of lips in orthodontic treatment.Therefore,we should apply force to the direction of tongue when conducting orthodontic treatment,which decreases the formation of black triangle for sake of oral facial aesthetics.Force to the direction of lips should be avoided.When making orthodontic treatment,the dentist should consider the patients' condition and choose a method balancing the function and aesthetic after orthodontic treatment. |
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