Dental compensation for skeletal Class III malocclusion by isolated extraction of mandibular teeth. Part 1: Occlusal situation 12 years after completion of active treatment

Favourable dentoalveolar changes after lower premolar extractions for Class III camouflage with completely customized lingual appliances

BACKGROUND

The aim of the investigation was to evaluate if the inclination of the lower anterior teeth can be controlled reliably after lower premolar extraction for Class III camouflage treatment with completely customized lingual appliances (CCLAs). Treatment outcome was tested against the null hypothesis that lower premolar extractions for non-surgical camouflage treatment of a Class III malocclusion will lead to further compensation by retroclining mandibular incisors during CCLA treatment.

METHODS

This retrospective study included 25 patients (f/m 12/13; mean age 20.7 years, SD 9.5 years) with uni- or bilateral Class III molar relationship and a Wits value of ≤ -2 mm. In all consecutively debonded patients, lower premolars were extracted to correct the sagittal relationship with a non-surgical camouflage approach. Lateral head films prior to (T1) and at the end of lingual orthodontic treatment (T2) were used to evaluate skeletal and dentoalveolar effects. A paired t-test with alpha = 5% was used to define differences between the endpoints. The linear correlation between the inclination of the mandibular incisors at T1 and the achieved correction was measured with the Pearson correlation coefficient (PCC). A Schuirmann's TOST equivalence test was used to check if the final lower incisor inclination was within the defined norms.

RESULTS

The null hypothesis was rejected as the mean lower incisor inclination was improved by 1.8° despite lower premolar extractions (T1: 86.8°/ T2: 88.6°). There was a strong correlation (-0.75) between the lower incisor inclination at T1 and the achieved correction indicating a controlled correction towards the norm regardless of the initial incisor position. At T2, the interincisal angle as well as the lower incisor inclination were within the norm.

CONCLUSION

Lower premolar extractions for non-surgical camouflage treatment of a Class III malocclusion will not lead to undesired retroclining of mandibular incisors during CCLA treatment even in severe cases.

Clear Aligners Treatment of Class III Subdivision with an Extraction of a Lower Bicuspid

The aim of this study was to show a case of a Class III subdivision adult patient treated with clear aligners (CA) and the extraction of a lower bicuspid. A 19-year-old male with a class III canine and molar relationship on the right side and a deviation of lower dental midline to the left asked for an aesthetic treatment. He refused orthognathic surgical procedures, so he was offered a camouflage orthodontic treatment with the extraction of lower right first premolar to achieve a canine Class I relationship and to center the lower midline. The treatment was performed with clear aligners and the use of Class III elastics to maintain distal anchorage on the right side during the canine distalization. At the end of the treatment, the occlusal objectives were achieved.

Factors associated with the stability of compensatory orthodontic treatment of Class III malocclusion in the permanent dentition

INTRODUCTION

This study aimed to assess the stability of compensatory treatment of Class III malocclusion in permanent dentition.

METHODS

Thirty-six patients (21 women and 15 men; mean age, 20 years) with Class III malocclusion were subjected to the compensatory treatment of permanent dentition and followed up for at least 3 years after orthodontic treatment (T3). Multivariate Poisson regression was performed to assess the influence of clinical, cephalometric, and dental cast variables at the beginning (T1) and the end of treatment on the stability of Class III malocclusion.

RESULTS

Overjet changed from -0.25 mm (-3 to 0.5 mm) at T1 to 1.4 mm (1-2.5 mm) at the end of treatment and 0.8 mm (0-1.5 mm) at T3. Clinical relapse (overjet <1 mm and/or canine Class III relations) was observed in 11 patients (30.6%). Patients treated with extraction of mandibular premolars (risk ratio [RR] = 2.13 × 10^-07, P <0.001), with better orthodontic end outcomes (RR = 1.16, P = 0.009) and which had lower maxillary incisor inclination at T1 (RR = 1.08, P = 0.035) showed a lower risk of relapse. Demographic (sex, age), clinical (length of treatment and posttreatment, number of treatment phases, time of Class III elastics), cephalometric (SNA, SNB, ANB, Wits appraisal, SNGoGn, IMPA), and dental cast (peer assessment rating index and arch dimensions) variables were not significantly associated with clinical relapse at T3.

CONCLUSIONS

The stability of compensatory treatment of Class III malocclusion in permanent dentition is multifactorial, with few predictive variables. Patients treated with extraction and better orthodontic finishing had a lower risk of relapse, whereas larger maxillary incisor inclination at baseline increased the risk of relapse.

Efficiency of class III malocclusion treatment with 2-premolar extraction and molar distalization protocols

INTRODUCTION

Different treatment protocols have been implemented for management of Class III malocclusion with aim of achieving ideal occlusal goals. The aim of current study was to compare the efficiency of Class III treatment with mandibular 2-premolar extraction and mandibular molar distalization protocol.

METHODS

This retrospective cross sectional study was conducted on pre-treatment and post-treatment dental casts of 60 orthodontic patients who had Class III malocclusion and were treated with a mandibular dentition distalization and mandibular 2-premolars extraction protocol. The study was conducted at orthodontic departments of Dental Section, Faisalabad Medical University/Punjab Medical College and de'Montmorency College of Dentistry, Pakistan. The sample was classified into 2 groups. Group A consisted of 30 patients (20 females, 10 males) (mean age, 18.02years) treated with distalization protocol and Group B consisted of 30 patients (18 females, 12 males) (mean age, 18.97years) treated with mandibular 2-premolars extraction protocol. To compare the efficiency of the treatment protocol in each group, the initial and final occlusal results were assessed on dental models using PAR index while treatment efficiency was assessed using a treatment efficiency index (TX). The groups were compared with t and Mann-Whitney tests.

RESULTS

There were no significant differences in the initial age, treatment time, treatment efficiency and any occlusal feature between the groups.

CONCLUSION

Treatment efficiency of Class III malocclusions with mandibular 2-premolar extractions or mandibular dentition distalization protocol is similar.

Compensation of skeletal Class III malocclusion by isolated extraction of mandibular teeth: Part 2: Skeletal, dentoalveolar and soft tissue parameters in comparison with nonextraction Class III therapies

OBJECTIVES

To retrospectively compare two compensatory approaches taken in skeletal Class III patients during the main treatment stage, including a study group of multiband treatment plus isolated extraction of mandibular teeth and a control group of multiband treatment without extraction of teeth.

PATIENTS AND METHODS

The extraction group included 22 (12 female, 10 male) patients receiving compensatory multiband treatment for a mean of 3.47 ± 1.14 years and 16.22 ± 1.92 years old at debonding. The nonextraction group included 24 (14 female, 10 male) patients undergoing multiband treatment for 2.76 ± 1.28 years and 15.38 ± 1.46 years old at debonding. Lateral cephalograms obtained at baseline and upon completion of active treatment were traced for skeletal, dentoalveolar, and soft tissue parameters. Welch and Wilcoxon tests were used to analyze intergroup differences (initial values, final values, initial-to-final changes) and within-group differences (p < 0.05).

RESULTS

Upon completion of active treatment, the only significant intergroup differences were noted for U1NA and L1ML. Significant within-group changes over the courses of treatment were seen for SNB, MLNL, U1NA, U1NL, L1NB, L1ML, H-angle, ULipEL, and LLipEL (extraction group) or for SNB, ANB, individual ANB, Wits appraisal, U1NA, U1NL, H-angle, Naslab-a, ULipEL, and LLipEL (nonextraction group). Parameters that changed by significantly different amounts in both groups included Wits appraisal, L1NB, L1ML, and LLipEL.

CONCLUSION

The added value of isolated extraction therapy basically lies in increasing the potential for retruding the lower incisor inclinations, so that compensatory treatment becomes an option even in selected patients presenting with adverse occlusal situations that would otherwise require orthognathic surgery. Given the successful outcomes in both groups, which had been established by Peer Assessment Rating (PAR) scores, it was possible to define the skeletal, dentoalveolar, and soft tissue characteristics of successful treatment more precisely than before.