Skeletal Class III correction in permanent dentition using reverse twin block appliance and fixed mechanotherapy

M. Effectiveness of Management of Skeletal Class III Malocclusion during Primary, Mixed, and Permanent Dentition Period – A Literature Review

Skeletal class III malocclusion is one of the most challenging conditions in clinical dental practice. Various treatment options are available for the management of the condition such as reverse twin block appliance, facemask appliance, chin cup therapy, bone anchorage maxillary protraction device, and tandem traction bow appliance. However, treatment timing is controversial. There are various advantages and disadvantages following the correction of skeletal class III malocclusion during primary, mixed and permanent dentition period. Hence, this review aims to compile the available literature regarding the effectiveness of correction of skeletal class III malocclusion during primary, mixed, and permanent dentition.

[Therapeutic effect analysis of skeletal class Ⅲ malocclusion treatment by transmission straight wire technique]

OBJECTIVE

This study aimed to investigate the therapeutic effects and advantages of skeletal class Ⅲ malocclusion treatment by transmission straight wire technique.

METHODS

Ninety-seven patients who received treatment for skeletal class Ⅲ malocclusion at the Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2012 to January 2017 were selected for this retrospective study. All these patients refused surgery. They were divided into two groups in accordance with the type of skeletal malocclusion: mild-to-moderate skeletal malocclusion group (-4°≤ANB <0°) and severe skeletal malocclusion group (-8°≤ANB<-4°). Each of the two groups was divided further into two small groups in accordance with the technique used: T group (transmission straight wire technique) and M group (MBT technique).

RESULTS

The crossbite of all 59 patients in the mild-to-moderate skeletal malocclusion group was successfully treated. The molars were classified as classⅠrelationship, and the facial profile improved. Significant differences were found in the values of U1/SN angle, L1/MP angle, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05). In the severe skeletal malocclusion group, the crossbite of all 38 patients was cured or partially cured. Fourteen patients showed severe lower anterior teeth inclination (five in the T group and nine in the M group), and the profiles did not significantly improve. Significant differences were observed in the values of U1-NA value, U1/SN angle, L1-NB value, L1/MP angle, LLP, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05).

CONCLUSIONS

Relative to the MBT technique, the transmission straight wire technique has great advantages in improving facial profile, reducing the compensatory inclination of the upper and lower anterior teeth, and reducing the risk of root resorption in the treatment of skeletal class Ⅲ malocclusion.