Dentoskeletal effects during Herbst-Multibracket appliance treatment: a comparison of lingual and labial approaches

Dentoalveolar process remodelling in the anterior mandible after Class III camouflage treatment with lower premolar extractions

BACKGROUND

The aim of this investigation was to evaluate if the hard and soft tissue dentoalveolar process of the mandible follows the tooth movements after lower premolar extractions and anterior retraction in Class III camouflage treatment.

METHODS

This retrospective study included 25 patients in retention (f/m 12,13) who had previously been treated with lower premolar extractions for Class III camouflage with a completely customized lingual appliance (Wits at T0 -6.7, ± 2.5 mm). The periodontal and dental health of the lower 6 anterior teeth was evaluated (T1) by a thermal sensitivity test, probing and visual inspection after a mean retention period of 3.1 years (± 2.5, min/max 1.0/9.6 years). A novel non-invasive method was used to measure the thickness of the hard and soft tissue dentoalveolar process on the labial and lingual side of the teeth before treatment (T0) and in retention (T1) at 3 different levels using superimposed intraoral scans. A paired t-test with α = 5% was used to evaluate differences between the endpoints.

RESULTS

At T1, all 25 patients (mean age 26.8 ± 9.7 years, min/max 16.3/49.5 years) presented uncompromised periodontal and dental situations in the lower anterior segment. The presented digital method for evaluating dimensional changes of the dentoalveolar process had excellent reliability (ICC) with a method error of 0.01 mm. The mean total labio-lingual dimension of the hard and soft tissue dentoalveolar process (min/max 7.89/10.02 mm at T0) was identical at T0 and T1 (mean change of 0.00 ± 0.33 mm, min/max -0.98/0.8 mm). At all levels, the teeth moved only 0.12 mm to the lingual side within the dentoalveolar process and therefore, they moved with the dentoalveolar process and not through it.

CONCLUSION

In non-surgical camouflage treatment with lower premolar extractions in moderate to severe Class III malocclusions, the dentoalveolar process can follow the movement of the mandibular incisors and canines during controlled retraction without any adverse effects.

Quality of occlusal outcome in adult Class II patients treated with completely customized lingual appliances and Class II elastics compared to adult Class I patients

OBJECTIVES

The aim of this investigation was to evaluate whether Class II malocclusion in adult patients can be successfully corrected using a completely customized lingual appliance (CCLA) in combination with Class II elastics.

METHODS

In order to detect differences in the final treatment outcome, two groups were matched for age and gender. Treatment results of 40 adult orthodontic patients with a Class I malocclusion (Group 1) were compared to 40 adults with a Class II malocclusion (Group 2). All patients had completed treatment with a CCLA (WIN, DW Lingual Systems, Bad Essen, Germany) without known centric occlusion-centric relation discrepancies, issues of compliance, or overcorrection in the individual treatment plan which was defined by a target set-up. In order to compare the treatment results of the two groups, 7 measurements using the American Board of Orthodontics Model Grading System (ABO MGS) and linear measurements for anterior-posterior (AP) and vertical dimensions were assessed at the start of lingual treatment (T1), after debonding (T2B) and compared to the individual target set-up (T2A).

RESULTS

A statistically significant AP correction was achieved in Group 2 which represented 95% of the planned amount. The planned overbite correction was fully achieved in the Class I and Class II group. In both groups, there was a statistically significant improvement in the ABO scores, with no significant difference between the two groups at T2. 100% of the patients in Group 2 and 92.5% in Group 1 would meet the ABO standards after CCLA treatment.

LIMITATIONS

The main limitation of this study is that only patients who were wearing the elastics as prescribed were retrospectively included. Therefore, the results of this study may have limited generalizability.

CONCLUSIONS

Completely customized lingual appliances in combination with Class II elastics can correct a Class II malocclusion successfully in adult patients. The final treatment outcome can be of a similar high quality in Class I and Class II patients.

Non-Surgical Transversal Dentoalveolar Compensation with Completely Customized Lingual Appliances versus Surgically Assisted Rapid Palatal Expansion in Adults-Tipping or Translation in Posterior Crossbite Correction?

The aim of this study was to investigate buccolingual tooth movements (tipping/translation) in surgical and nonsurgical posterior crossbite correction. A total of 43 patients (f/m 19/24; mean age 27.6 ± 9.5 years) treated with surgically assisted rapid palatal expansion (SARPE) and 38 patients (f/m 25/13; mean age 30.4 ± 12.9 years) treated with dentoalveolar compensation using completely customized lingual appliances (DC-CCLA) were retrospectively included. Inclination was measured on digital models at canines (C), second premolars (P2), first molars (M1), and second molars (M2) before (T₀) and after (T₁) crossbite correction. There was no statistically significant difference (p > 0.05) in absolute buccolingual inclination change between both groups, except for the upper C (p < 0.05), which were more tipped in the surgical group. Translation, i.e., bodily tooth movements that cannot be explained by pure uncontrolled tipping, could be observed with SARPE in the maxilla and with DC-CCLA in both jaws. Dentoalveolar transversal compensation with completely customized lingual appliances does not cause greater buccolingual tipping compared to SARPE.

Controlling incisor torque with completely customized lingual appliances

PURPOSE

To test the null hypothesis of no significant deviation between the center of rotation (C_ROT) and the center of resistance (C_RES) during space closure in Angle class II division 2 subjects achieved using a completely customized lingual appliance (CCLA) in combination with class II elastics and elastic chains.

METHODS

This retrospective study included 29 patients (male/female 11/18; mean age 15.6 [13-27] years) with inclusion criteria of an Angle class II/2 occlusion of least of half of a cusp, maxillary dental arch spacing, completed CCLA treatment (WIN, DW Lingual Systems, Bad Essen, Germany) in one center with a standardized archwire sequence and use of class II elastics and elastic chains only. Maxillary incisor root inclination was assessed by X‑ray superimpositions of the maxilla at the beginning (T1) and the end (T3) of CCLA treatment. Using Keynote software (Apple®, Cupertino, CA, USA), the incisor's C_ROT was assessed with the point of intersection of the incisor axes (T1; T3) following vertical correction of overbite changes. C_RES was defined at 36% of the incisor's apex-incisal edge distance.

RESULTS

The null hypothesis was rejected: the mean C_ROT - C_RES difference was 52.6% (p < 0.001). The mean C_ROT was located at 88.6% (min-max 51-100%) of the incisor's apex-incisal edge distance. Although 6.9% of C_ROT were located between the C_RES and the alveolar crest, the vast majority (93.1%) were assessed between the alveolar crest and the incisal edge, or beyond.

CONCLUSION

CCLAs can create upper incisor palatal root torque even in cases in which lingually oriented forces applied incisally to the center of resistance of the upper incisors counteract these intended root movements.

Long-term (≥15 years) post-treatment changes and outcome quality after Class II:1 treatment in comparison to untreated Class I controls

Aim

To investigate the long-term (≥15 years) post-treatment (Tx) occlusal changes and outcome quality after Class II:1 Tx.

Subjects and Methods

Herbst-MBA Tx had been performed at age 12.8 ± 2.7 years in 119 patients. A recall was conducted and study models from before and after active Tx, after retention as well as after recall were evaluated using standard occlusal variables and the PAR index. These data were compared to 31 untreated Class I controls.

Results

52 out of 119 patients could be located and participated at 33.6 ± 3.1 years. Compared to the 67 patients who did not participate in the recall, the pre- and post-Tx occlusal data of the participants did not differ systematically; however, the PAR scores were higher by 3.0-4.7 points at all times. Pre-Tx, the mean values of the 52 participants were: PAR = 27.2 ± 7.6, Class II molar relationship (MR) = 0.7 cusp widths (cw), overjet = 8.2 mm, overbite = 4.1 mm. After Tx, the PAR score was 3.4 ± 2.2. A Class I MR (0.0 ± 0.1 cw) with normal overjet (2.3 ± 0.7 mm) and overbite (1.3 ± 0.7 mm) existed. At recall, a mild PAR score increase to 8.2 ± 5.5 points had occurred; this was mainly due to increased overjet and overbite values (3.6 ± 1.1 and 2.8 ± 1.6 mm) while the MR was stable (0.0 ± 0.2 cw). For all these variables, similar findings were made in the untreated controls.

Conclusion

The occlusal outcome of Class II:1 Tx showed very good long-term stability. While mild changes occur post-Tx, the long-term result is similar to untreated Class I controls.

Are there differences in treatment effects between labial and lingual fixed orthodontic appliances? A systematic review and meta-analysis

Background

An evaluation is made of possible differences in treatment effects between labial and lingual fixed appliances.

Methods

A comprehensive search was made of the PubMed-Medline, Cochrane Library and LILACS databases, with an additional manual search covering the period up until April 2017. There were no restrictions in terms of year of publication or language. Agreement between the authors was quantified by the Cohen kappa statistic. A random-effect model was applied to calculate weighted mean differences with 95% confidence intervals.

Results

A total of 249 patients corresponding to four eligible studies were included in the systematic review. Among the six angles and distances entered in the meta-analysis, a tendency was observed in lingual appliances to increase the interincisal angle (95% CI −0.80-8.99; p = 0.101) and reduce the angle between the major axis of upper central incisor and the sellar-nasion plane - though statistical significance was not reached (95% CI −5.75-0.32; p = 0.079).

Conclusion

The results obtained indicate that treatment with lingual appliances favors incisor tipping by exerting lingual crown torque, but there are no differences in cephalometric values between labial and lingual fixed appliances. Because of the small number of included studies, the results of this meta-analysis should be interpreted with caution. Future research should focus on the generation of a consensus document allowing selection of the type of orthodontic approach not only conditioned to the esthetic requirements of the patient but also considering the characteristics of the malocclusion. On the other hand, standardized international guidelines are lacking; the measurements of angles and distances therefore have to be unified with a view to future investigations.

Mode of correction is related to treatment timing in Class II patients treated with the mandibular advancement locking unit (MALU) appliance

OBJECTIVE

To investigate the proportion of skeletal/dentoalveolar components for correction of Class II malocclusion in relation to the pubertal growth peak (PGP) among patients treated with the mandibular advancement locking unit (MALU) appliance.

MATERIALS AND METHODS

We conducted a retrospective study of 27 orthodontic patients (age range: 12-18 years; mean age 14.9 years) with skeletal Class II Division 1 malocclusion who were treated with the MALU appliance until they reached Class I occlusion with overjet and overbite within normal range. Pretreatment (T1) and posttreatment (T2) lateral cephalograms were analyzed using standard cephalometrics and sagittal occlusion analysis to assess changes in the dentoalveolar and skeletal complex. The cervical vertebral maturation (CVM) method was used to determine participants' skeletal maturation in T1 cephalograms. Based on this maturation, participants were divided into two groups: the peak group (treatment initiation before or during PGP [peak group, n=15]) or the postpeak group (treatment initiation after the PGP [n = 12]).

RESULTS

No significant differences between groups were found at T1 for most of the skeletal and dental parameters investigated. At T2, the mean ANB angle and proclination of the mandibular incisors were significantly smaller in the peak group than in the postpeak group. In the peak group, skeletal correction comprised 54% and dental correction 46% of the total change at T2, while in the postpeak group the corresponding figures were 24% and 76%, respectively.

CONCLUSIONS

Treatment initiated before or during PGP seems to result in a more favorable SNA/SNB relationship and less tipping of the mandibular incisors than when treatment is initiated after PGP.