Dentoskeletal effects of class II malocclusion treatment with the modified Twin Block appliance

Dentoalveolar changes and transverse discrepancies through the treatment of class II division 1 malocclusion in children using a twin block device

Background

This study aims to analyze dentoalveolar changes and transverse discrepancies in the treatment of class II division 1 dentoskeletal malocclusion before and after treatment using a functional twin block device.

Material and Methods

This study used a comparative analytical study to compare dentoalveolar changes and maxillary transverse discrepancies. The research sample was a study model of patients aged 7-15 years with 23 study models with class II division 1 dentoskeletal malocclusion cases at the clinic of the Department of Pediatric Dentistry, Hasanuddin University Educational Oral and Dental Hospital (RSGMP UNHAS). A sampling of the study model was carried out by purposive sampling. The measurement data was tested using the chi-squared normality test and then the statistical test was the paired t test.

Results

Based on the statistical analysis of paired t-test there is a change in the distance between the mandibular canines, there is a change in the distance between the first premolars or between the mandibular first primary molars, there is a change in the distance between the second premolars or between the maxillary second primary molars, and there is a change in the distance between the maxillary molars after treatment using a twin block device.

Conclusions

There were substantial dentoalveolar alterations in overjet, overbite, molar relation, and distance between premolars and molars after using the twin block device. Key words:Malocclusion, twin block, dentoalveolar, jaw discrepancy.

Dentoskeletal effects of aesthetic and conventional twin block appliances in the treatment of skeletal class II malocclusion: a randomized controlled trial

Twin block appliances are commonly used to treat skeletal class II malocclusion. However, many adverse effects, such as lower incisor protrusion and a bulky nature, can be observed. To overcome these effects, a modified twin block was designed, which uses vacuum-formed hard plates (VFPs) instead of acrylic plates. This clinical trial evaluated the skeletal and dentoalveolar changes resulting from a modified twin block (aesthetic twin block) (ATB) in comparison with conventional twin block (CTB) in addition to levels of esthetics and discomfort. A two-arm parallel group randomized clinical trial was performed at the Department of Orthodontics, University of Damascus, Syria. Fifty-two patients (33 females and 19 males) aged 12.23 ± 0.77 years with skeletal class II division 1 malocclusion caused by mandibular retrognathism were included. The participants were randomly assigned to a study group according to a simple randomization method using a numbered and sealed envelope. The experimental group was treated with an aesthetic twin block, and the control group was treated with a conventional twin block. Sixteen angular variables and eleven seventeen linear variables (measured in millimeters) were evaluated before the treatment (T0) and at the end of the active phase of the treatment (T1) on lateral cephalometric radiographs and dental casts to study the skeletal and dentoalveolar changes, and a questionnaire was used to assess the levels of esthetic and discomfort. There was a statistically significant change in the ANB angle between the ATB group (-2.70 ± 0.84) and the CTB group (-1.92 ± 0.81°) (P = 0·002) and between the SNB angle of the ATB group (2.72 ± 1.54°) and the CTB group (1.72 ± 1.41°) (P = 0·02). The Jarabak ratio decreased significantly in the CTB group (-0.65 ± 1.37%) (P = 0.02) and increased significantly in the ATB group (0.84 ± 1.44%) (P = 0.007), with significant differences between the two groups (P = 0.000). The change in upper incisor angulation was statistically significant (-1.88 ± 1.48°) for the ATB group and (-3.5 ± 4.18°) for the CTB group (P = 0·001). The change in lower incisor angulation was 1.34 ± 2.08° for the ATB group and 3.88 ± 2.47° for the CTB group, which was statistically significant (P = 0·000). ATB had more control of vertical growth, lower incisor and upper incisor angulation and was more aesthetically acceptable.Trial registration: (NCT05418413) (14/06/2022).

Comparison of Twin Block appliance and Herbst appliance in the treatment of Class II malocclusion among children: a meta-analysis

BACKGROUND

Our meta-analysis aimed to evaluate the efficacy of applying Herbst and Twin Block appliances in the treatment of Class II malocclusion among children.

METHODS

Databases, including PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), China VIP Database (VIP), and Wanfang were thoroughly searched from inception to August 9, 2023. The outcomes included skeletal, dental, and soft tissue changes. The weighted mean difference (WMD) was used as the effect indicator, and the effect size was expressed with a 95% confidence interval (CI). The heterogeneity of each outcome effect size was tested, and the heterogeneity statistic I2 ≥ 50% was analyzed by the random-effect model, otherwise, the fixed-effect model was conducted. Sensitivity analysis was performed.

RESULTS

A total of 12 studies involving 574 patients were included in this meta-analysis. Herbst appliance had a statistically significant increase in mandibular body length (WMD: 1.44, 95% CI: 0.93 to 1.96, P < 0.001) compared with the Twin Block appliance. More increases in angle and distance of L1 to mandibular plane (MP) were found in the Herbst appliance compared with the Twin Block appliance. Significant and greater improvements in molar relationship (WMD: 0.79, 95% CI: 0.28 to 1.29, P = 0.002), posterior facial height (WMD: -1.23, 95% CI: -2.08 to -0.38, P = 0.005), convexity angle (WMD: -1.89, 95% CI: -3.12 to -0.66, P = 0.003), and Sella-Nasion plane angle (U1 to SN) (WMD: 3.34, 95% CI: 2.25 to 4.43, P < 0.001) were achieved in the Twin Block appliance. Herbst and Twin Block appliances produced similar effects in the skeletal and dentoalveolar changes including Sella-Nasion-point A (SNA), Sella-Nasion-point B, point A-Nasion-point B (ANB), overjet, and overbite.

CONCLUSION

As the findings revealed both Herbst and Twin Block appliances contributed successfully to the correction of Class II malocclusion. Compared with the Twin Block appliance, the Herbst appliance may have more advantages in mandibular bone movement. Twin Block therapy resulted in more improvement in the aesthetics of the face.

Efficacy of invisible advancement correction for mandibular retraction in adolescents based on Pancherz analysis

BACKGROUND

Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication, breathing and the temporomandibular joint. The use of mandibular advancement (MA) devices has recently emerged as an adolescent mandibular retraction treatment; however, current studies regarding the effect thereof are relatively few, and there is lack of sufficient clinical support.

AIM

To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents.

METHODS

This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021. The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software. The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology.

RESULTS

There was no significant difference in the length and position of maxilla before and after the treatment. The position of the mandible moved 3.13 mm, the length increased 4.14 mm, the mandibular ramus length increased 4.09 mm, the body length increased 4.25 mm, and the position of the condyle moved 1.03 mm forward after treatment. Additionally, changes in the incisor sagittal position and labial inclination were observed. The position of the upper incisor point moved back 1.33 mm, without statistical difference, the inclination and tooth angle decreased by 3.44° and 4.06°, respectively; the position of the lower incisor point was moved 2.98 mm, and the inclination and tooth angle increased by 2.62° and 1.23°, respectively. Furthermore, changes in the incisor overjet and molar relationship were seen. Overjet decreased by 4.31 mm, of which 1.78 mm was due to dental factors, accounting for 41.3% of the effect as opposed to 58.7% due to skeletal factors. Molar relationship improved 3.87 mm, with 1.34 mm due to dental factors, and dental and skeletal factors were accounted for 34.6% and 65.4% of the effect, respectively.

CONCLUSION

For adolescent patients with mandible retraction, invisalign MA can effectively promote the mandible growth, and it was proven to be mainly due to skeletal effects.

Volumetric Evaluation of Pharyngeal Airway after Functional Therapy

The aim of this study was to evaluate three-dimensional (3D) effects of Twin-block functional appliance (TB) on the pharyngeal airway by using cone beam computed tomography (CBCT). A total of 30 patients (14 females, 16 males; mean age 12.50 ± 1.23 and 12.83 ± 1.17 years, respectively) with skeletal Class II malocclusion were included in this study and were treated with TB. On the pretreatment (T1) and posttreatment (T2) CBCT scans, volumetric changes in the pharyngeal airway; SNA, SNB, and ANB angles; and bilateral effective mandibular (Co-Gn) and midfacial length (Co-A) were also evaluated. The statistical differences were accessed by Wilcoxon signed-rank tests, and Mann-Whitney U tests were used to analyze the scores of male and female subjects. In this study, an increase was observed in SNB and Co-Gn (p < 0.01) while a decrease in ANB and SNA (p < 0.01 and p < 0.05, respectively) was found. However, increase in midfacial length was not statistically significant (p > 0.05). In the evaluation of volumetric pharyngeal airway changes, statistically significant increases (p < 0.01) in the upper and lower division and total airway volume were determined. Gender differences were insignificant for all measurements (p > 0.05). Volumetric changes in the pharyngeal airway after functional therapy can be successfully evaluated by CBCT images. The anterior repositioning of the mandible by TB increases the mandibular length and pharyngeal airway volume in patients with retrognathic mandible.