Clinical outcomes of lingual fully customized vs labial straight wire systems

Conventional and self-ligating lingual orthodontic treatment outcomes in Class I nonextraction patients: A comparative study with the American Board of Orthodontics Objective Grading System

INTRODUCTION

This study aimed to assess and compare the duration and outcomes of orthodontic treatment with conventional and self-ligating lingual fixed appliances with the American Board of Orthodontics (ABO) Objective Grading System.

METHODS

Thirty consecutive patients with a complete dentition and Angle Class I malocclusion treated with a conventional lingual bracket system (STb; Ormco, Glendora, Calif) or self-ligating lingual bracket system (GC Experience-L; GC Orthodontics, Breckerfeld, Germany) were included. The occlusal outcome was assessed with the ABO instrument. The treatment duration and ABO scores of the 2 groups were recorded. Statistical analyses were evaluated using independent-sample t tests.

RESULTS

The conventional group had a mean treatment time of 2.10 ± 0.69 years, and the self-ligating group had a treatment duration of 1.68 ± 0.48 years (P >0.05). The mean posttreatment ABO scores in the conventional group were 20.23 ± 5.13, and the mean posttreatment ABO scores in the self-ligating group were 21.00 ± 5.66. No difference was found between the groups regarding the criteria of ABO (P >0.05). The highest scores were given in the assessment of buccolingual inclinations in both conventional and self-ligating lingual bracket groups.

CONCLUSIONS

The design of the lingual appliances used in this study did not influence the treatment duration and the total ABO scores in treating patients with a Class I relationship in this sample. Both types of lingual brackets were especially deficient in correcting buccolingual inclinations. The strengths were their ability to close spaces and correct anterior rotations and overjet regardless of the bracket types.

3D Finite Element Study of the Physiological Anchorage Control Concept on Anchorage Molars in Lingual Orthodontics

Objective. To study the effect of the physiological anchorage control concept on anchorage molars in lingual and labial orthodontic techniques. Methods. Three-dimensional finite element models, including the right maxillary first molar, periodontal ligament, alveolar bone, and buccal tube, were established. The models were divided into the McLaughlin–Bennett–Trevisi (MBT™) straight-wire model with 0-degree maxillary first molar axial inclination and the physiologic anchorage Speewire system (PASS) model with −7-degree maxillary first molar axial inclination. Simulated sliding retraction forces (1 N, 1.5 N, and 2 N) were loaded on the buccal side and lingual side, and retraction forces (0.5 N, 0.75 N, and 1 N) were loaded on the buccal and lingual sides simultaneously. The displacements, principal stresses, and von Mises stresses of the periodontal ligament under different conditions were derived. Results. The anchorage molars showed different degrees of rotation, tipping, intrusion, and extrusion. As the force increased, these displacement trends also increased. The mesial displacement of the buccal + lingual force loading was less than that of the other two groups. Under the same force load method, the mesial displacement of the PASS group was less than that of the MBT group. Tilt movement increases the tensile stress of the distal cervical margin and root mesial apical third and the compressive stress of the mesial cervical margin and root distal apical third. The maximum stress of the periodontal ligament was less than that of the other two groups when the lingual force was loaded. Conclusion. The physiological anchorage control concept in lingual orthodontics provides better sagittal anchorage control than in labial orthodontics, but there is no significant difference numerically. Attention should be given to the control of torsion, torque, and arch width. Tilt movement increases the PDL stress of the cervical margin and root apical third. The sliding retraction force should be loaded lingually to maintain the force value of 1∼1.5 N.

Agreement of the Discrepancy Index Obtained Using Digital and Manual Techniques—A Comparative Study

The discrepancy index evaluates the complexity of the initial orthodontic diagnosis. The objective is to compare whether there is a difference in the final discrepancy index score of the American Board of Orthodontics (ABO) when obtained using digital and manual techniques. Fifty-six initial orthodontic records in a digital and physical format were included (28 each) in 2022 at the Center for Research and Advanced Studies in Dentistry. For the digital measurements, iTero and TRIOS 3 intraoral scanners were used, along with Insignia software and cephalometric tracing with Dolphin Imaging software. Manual measurements were obtained in dental casts using the ruler indicated for the previously mentioned discrepancy index, in addition to conventional cephalometric tracing. Student’s t-test did not show statistically significant differences between the digital and manual techniques, with final discrepancy index scores of 24.61 (13.34) and 24.86 (14.14), respectively (p = 0.769). Cohen’s kappa index showed very good agreement between both categorical measurements (kappa value = 1.00, p = 0.001). The Bland–Altman method demonstrated a good agreement between continuous measurements obtained by both techniques with a bias of 0.2500 (superior limit of agreement =9.0092988, inferior limit of agreement = −8.5092988). Excellent agreement was observed in obtaining the discrepancy index through digital technique (Intraoral scanning and digital records) and manual technique (conventional records).

Objective treatment outcome assessment of a completely customized lingual appliance: A retrospective study

OBJECTIVE

To assess the outcome quality of subjects treated with a completely customized lingual appliance (CCLA) in a postgraduate university program, using the ABO Objective Grading System (OGS), by testing the null-hypothesis of a significant proportion of post-treatment cases exceeding an adjusted 'exam failure' threshold value of OGS=24.

MATERIALS AND METHODS

This retrospective single-arm study included 66 consecutively debonded CCLA cases (m/f 19/47; mean age: 25.1±9 years) treated at Hannover Medical School (MHH, Hannover, Germany). The discrepancy index (DI) was assessed on initial plaster casts. The OGS of the cast-radiograph evaluation was scored for both set-up and post-treatment casts, including the seven components of alignment/rotation, marginal ridges, buccolingual inclination, overjet, occlusal contacts, occlusal relationships and interproximal contacts, to parameterize differences between those.

RESULTS

DI score distribution (≥20, <20) was 25 (37.9%)/41 (62.1%) subjects. Mean initial DI was 17.3±8.5. Mean set-up OGS was 10.4±4.4 (min-max: 3-21), mean final OGS was 17.7±5.9 (min-max: 7-33), and the difference 7.3 (post-treatment - set-up) was statistically significant (p<0.0001; 95% CI [5.8, 8.7]). The null-hypothesis was rejected: A statistically significant proportion of the final casts (n=58; 87.8%) scored below OGS=24 by exact binomial test (P<0.0001; 95% CI [77.5%, 94.6%]). The rate of a final OGS score<24 was not significantly different (P=0.98) between both DI (≥20, <20) groups.

CONCLUSIONS

The outcome quality of the CCLA treatment in this postgraduate university setting was high and therefore sufficient for a vast majority of treated cases to pass the ABO-OGS clinical examination.