Twin Block Research Articles

Does Appliance Design Affect Treatment Outcomes of Class II Division 1 Malocclusion? A Two-Center Retrospective Study.

ABSTRACTObjectivesThe purpose of this retrospective study was to compare the pre- and post-treatment values of patients treated with monoblock and twin-block appliances with the values of the skeletal Class I individuals.Material and MethodsThe initial lateral cephalometric radiographs of the pubertal untreated skeletal class I patients and cephalometric radiographs of 60 (30 monoblock, 30 twin-block) patients before and after the functional treatment were included in the study. Skeletal, dental, and soft tissue measurements were performed by a single researcher using Dolphin Imaging software version 11.95 (Dolphin Imaging, Chatsworth, CA, USA). Paired t-test was used for statistical evaluation and P < 0.05 was considered statistically significant.ResultsIn both monoblock and twin-block groups, there was a statistically significant increase in the measurements of the lower jaw and the vertical direction values (sella nasion B point (SNB), pogonion nasion perpendicular, Y-axis, sella nasion-gonion gnathion, palatal-mandibular angle, anterior facial height, mandibular length P < 0.05); however, in the Twin-block group, the lower jaw was found to be displaced more forward (change for twin-block; SNB = 2.35, Wits appraisal = -4.77). The most measurements of the twin-block treated group were similar to the control group.ConclusionsBoth functional appliances have been identified to be useful in achieving treatment targets; however, with twin-block, results closer to ideal values are obtained.

Comparative Evaluation of Esthetic and Structural Aspects in Class II Functional Therapy. A Case-Control Retrospective Study.

Background: To compare the skeletal, dental, and esthetic changes produced by three functional devices, Fränkel-2 appliance (FR-2), Twin Block (TB), and Occlus-o-Guide® (O-o-G®), for the treatment of Class II malocclusion. Methods: Sixty-five patients with Class II Division 1 malocclusion were divided into three groups and were analyzed through cephalometric analysis of skeletal, dental, and esthetic variables before and after treatment. The first group of 23 patients (F: 9; M: 14; mean age: 10.3 ± 1.08 years) was treated with FR-2, the second group of 18 patients (F: 8; M: 10; mean age 10.7 ± 1.05 years) was treated with TB, the third group (F: 11; M: 13; mean age: 9.05 ± 0.39 years) of 24 patients was treated with O-o-G®. The structural effects of the three devices were compared with a control group generated by the growth variations reported in the cephalometric atlas of Bhatia and Leighton. Esthetic analysis was performed comparing the results of the patients treated with a control group of 20 subjects with mandibular retrognathia and Class II Division 1 malocclusion, not subjected to therapy. Results: The three devices resulted in a significant increase in mandibular length, with higher results obtained for FR-2 and TB. A statistically significant increase in the IMPA angle was found for the O-o-G® group, and a notable reduction of both overjet and overbite was detected in all three groups of treated patients. The esthetic evaluation showed overall more significant results in the TB group, especially with regard to the reduction of facial convexity. The retrusion of the upper lip was on average more significant in the O-o-G® group, followed by that in the TB. Conclusions: All three devices have proven to be effective overall in resolving skeletal changes and improving facial esthetics.

Managing Class II Malocclusion Using Twin Block Therapy in a Young Adolescent Female: A Case Report

Twin block therapy is highly effective in patients with remaining growth potential. However, its successful use is confounded by many patient related factors such as age, gender, compliance of the patient and other miscellaneous criteria’s. If treated within time, growth modification and orthopedics can harness suitable forces to cause skeletal correction of the malocclusion. The appliance is highly successful in a patient with retruded mandible and presenting with a positive visual treatment objective. This paper discusses a case of 11-year-old female patient with characteristic twin block appliance indication in which successful skeletal modification was achieved.

Changes in the Skeletodental, Soft tissue and TMJ of Class II Division.1 Malocclusion Patient Following Orthodontic Treatment with Twin block Appliance: A Prospective Clinical Study

The purpose of this study was to evaluate the treatment outcome of Twin Block functional appliance and to determine the skeletodental, soft tissue and TMJ changes concurrent with the treatment. Ten subjects 5 males and 5 females with age ranged from 9 to 11 years were used in this study. All the cases showed Angle's Class II division 1 malocclusion due to mandibular retrusion. For each case out of the ten, lateral Cephalometric x-ray, right and left tomographic X-ray were done before and after treatment. On the base of the data obtained from this study both skeletodental and soft tissue improvement were detected after treatment. Also a significant reduction of the posterior joint space with significant increase of the condylar head thickness was seen. These outcomes make the appliance very effective in cases with retrognathic mandible, orthognathic maxilla and normal incisors inclination.

Nickel, chromium and methyl methacrylate monomer release from orthopaedic functional appliances.

This study was purposed to evaluate release of nickel and chromium ions and methyl methacrylate (MMA) monomers from functional appliances and their possible health effects. Study design: Twin-block appliances and Bionators were immersed in artificial saliva and kept in a thermal incubator. Control group was established as artificial saliva without appliances. Artificial saliva was analysed after 7 days, 30 days and 90 days. Inductively coupled plasma mass spectrometry and gas chromatography-mass spectrometry was used for detection of nickel and chromium ions and MMA monomers. MTT assays and cytokine array were performed. One way ANOVA with Tukey test and Dunnett's T3 for post-hoc analysis was used for evaluation of time-dependent changes and independent t-test was used for evaluation of MTT assay results. The results revealed that metal ions and MMA monomers are released from the appliances. Metal ion detection pattern was irregular and could not be analysed. Twin-block group showed significantly larger amount of MMA release. MTT assay revealed statistically significant but minimally reduced cellular activity on Bionator and twin-block groups compared to control groups. Cytokine array showed no or less inflammatory cytokine release on Bionator and twin-block groups. MMA monomer release was confirmed but the cytotoxic effect of functional appliance material release is minimal or negligible. General toxicity of the functional appliance from the MMA monomer release is likely to be minimal or negligible.

Twin Block Appliance-A Review

Twin block appliance is mostly for correction of class II malocclusion part with mandibular skeletal retrusion. This appliance uses the force of occlusion of teeth, the most natural functional mechanism to initiate bone remodelling process for functional correction of malocclusion.

Does daily wear time of Twin Block reliably predict its efficiency of classII treatment?

PurposeThe objective of this study was to investigate how daily wear time (DWT) influences class II malocclusion treatment efficiency.Materials and methodsThe study group consisted of 55 patients (mean age 10.4 years) diagnosed with a class II/1 malocclusion. Twin block appliances, with built-in Theramon® microsensors (MC Technology, Hargelsberg, Austria) to monitor patients’ cooperation (daily wear time assessment), were used for treatment. Cephalograms were taken and the following initial and final measurements were compared: Co-Gn, Co-Go, Co-Olp, Pg-Olp, WITS, SNA, SNB, ANB, Co-Go-Me, overjet, molar and canine relationships. The Shapiro–Wilk test, Wilcoxon signed-rank test, Student’s t-test, Levene’s test, Mann–Whitney U test, Kruskal–Wallis test, χ2 test, and Spearman’s rank correlation coefficient with p < 0.05 set as the statistical significance level were used to determine the correlation of the outcomes with DWT; a ROC (receiver operating characteristic) curve was calculated to illustrate diagnostic ability of the binary classifier system.ResultsDWT was very highly positively correlated with change of the Pg-Olp parameter and highly with an improvement in the ANB, SNA, and SNB angles, an increase in the WITS parameter and an increase in Co-Gn distance. DWTs < 7.5 h correlated with significantly less improvement of the investigated variables. However, DWT > 7.5 h did not significantly correlate with the improvement of the overjet and most of the linear parameters in the mandible. The ROC curve and its AUC (area under curve) allowed the determination of a DWT of 7 h and 48 min to be capable of establishing a class I relationship with 83% probability.ConclusionsClass II treatment efficiency was influenced by DWT; an 8 h threshold value had an 83% probability of establishing a class I relationship.

Class II Malocclusion and Traumatized Incisors in Adolescent with Twin Block and Fixed Appliance

This case report presents the outcome of atypical extraction and effect of Twin Block appliance on a growing adolescent. A 12-year-old boy who had complained about protrusive upper lips after being involved in a traffic accident. Tooth 11 was replanted at a local dental clinic, while tooth 21 was lost. In extra-oral examination, this patient had convex profile, obtuse nasolabial angle, and receded chin position. In intra-oral examination, bilateral Class II molar and canine relation were shown, the overjet was 11 mm between tooth 11 and 41; 7 mm between tooth 22 and 31; the overbite was 6 mm. Cephalometric analysis showed skeletal Class II jaw relationship with mandibular retrusion, and average mandible plane angle. The cervical vertebrae maturation stage was in late stage II to stage III. In the first stage of treatment, he received partial fixed orthodontic appliance to increase the overjet; then, Twin Block was used to facilitate mandibular growth. In the second stage, full-mouth fixed edgewise appliance was bonded and teeth 11 and 42 were extracted due to poor prognosis. After treatment, a harmonious profile was achieved. With proper case selection, good patient cooperation and appropriate appliance construction, distinct result with Twin Block appliance can be achieved. Early treatment using Twin Block appliance is effective in reduction of anterior-posterior discrepancy and severity of malocclusion.

Three-Dimensional Evaluation of Soft Tissue Changes after Functional Therapy.

This study was aimed at proposing a three-dimensional (3D) evaluation method for the soft tissue effects of Twin Block (TB) functional appliance therapy by using cone beam computed tomography (CBCT) images. In this retrospective study, a total of 60 pre- and posttreatment (T0 and T1) CBCT images of Class II patients with mandibular retrognathia treated with a TB appliance were used. Volumetric and linear soft tissue changes were evaluated quantitatively with 3D measurements and qualitatively with color mapping visual. Linear (NV-A and NV-Pog) and angular (SNA, SNB, and ANB) skeletal changes were also measured on 3D images. The Wilcoxon signed-rank test was used to compare statistical differences, and the scores of male and female participant differences were observed with the Mann–Whitney U test. In this study, a decrease was observed in SNA (p < 0.05), ANB (p < 0.01), and NV-Pog (p < 0.05) while an increase in SNB (p < 0.01) was found. However, decrease in NV-A distance was not statistically significant (p > 0.05). As a result of the evaluation of soft tissue changes, while the anterior reposition of the lower lip, soft tissue pogonion, and soft tissue gnathion was found to be significant (p < 0.01, p < 0.01, and p < 0.05, respectively), the upper lip and subnasale repositions were not statistically significant (p > 0.05). 3D soft tissue changes after TB therapy can be evaluated quantitatively and qualitatively by using CBCT images. Anterior repositioning of the mandible with functional therapy also provides improvement in soft tissue profile, especially in the lower facial region.

Evaluation of head and cervical spine posture after functional therapy with Twin‑Block and Bionator appliances: A pilot randomized controlled trial

ABSTRACT Objective Evaluation of head and cervical spine posture and estimation of sample size. Methods Thirty eligible participants who required functional therapy were randomly assigned to the Control group (C), Twin Block group (TB), or the Bionator group (B). Randomization was accomplished by means of blocks of fixed size stratified by sex and age, with the allocations concealed in opaque and sealed envelopes. Results Significant differences were identified between the pre -and post-functional SNB (p = 0.024) and ANB (p = 0.034) angles in the Twin Block group and SNA (p = 0. 019) and ANB (p = 0. 028) angles in the Bionator group. No statistically significant changes were seen in the head or cervical variables in the three groups. Conclusion The functional appliance did not cause any statistical change in head posture or cervical spinal column in comparison with the non-treatment group.

Does observational study on the effectiveness of the Twin Blocks overestimate or underestimate the results? A comparative analysis of retrospective samples versus randomized controlled trial

Class II malocclusion is one of the most common orthodontic problems. The Twin Block appliance has proven to be the most popular appliance for the correction of these malocclusions. Although randomized controlled trials (RCTs) on the Twin Block appliance have reported the changes to be mainly dentoalveolar, several nonrandomized studies have reported a significant skeletal improvement in these patients. Hence, the aim of this study was to compare the effectiveness of Twin Block appliance evaluated using an RCT or retrospectively selected cases (RSC) for the treatment of Class II Division 1 malocclusion in an adolescent population. This was a retrospective study. The results for an RCT were selected from a UK Class II multicenter study. Sixty-three patients from the trial were included. This group was matched with retrospectively selected Class II cases treated with a Twin Block functional appliance and their results submitted for Membership in Orthodontics examination in the United Kingdom, from four centers. The primary outcome was skeletal measurement ANB (A point, nasion, B point). Secondary outcomes included final peer assessment rating (PAR) scores and final overjet. Intrarater reliability of measurements was assessed. Independent samples t-test was carried out to look at the difference between the groups. The reliability assessment showed excellent agreement for all measurements. The data were normally distributed. There was a statistically significant difference favoring the RSC group for final overjet (mean difference [MD]=1.068, 95% confidence interval [CI] -0.67 to 1.47, P=0.000) and final PAR (MD=4.0, 95% CI -0.79 to 5.5, P=0.000). There was no significant difference in the scores for final ANB (MD=0.34, 95% CI -0.39 to 1.07, P=0.33). The RSCs show significantly improved overjet and PAR scores at the end of treatment and no statistically significant difference for skeletal change. The study raises the question of a potential role of observational studies in evaluating the effect of an intervention in orthodontics.

Orthodontic management of skeletal class II malocclusion with horizontally impacted maxillary canine: A case report

Management of skeletal class II relation in growing patient require careful evaluation of growth status, proper diagnosis and treatment plan to address the patient’s need. Twin block is the appliance of choice among functional appliance to correct the skeletal class II malocclusion due to it’s acceptability by the patient and simplified design. Maxillary canine impaction is the second most prevalent impaction after the third molars. Treatment of maxillary canine impaction is usually a challenge to orthodontic approach as the defect lies in the esthetic region of the jaw.&#x0D; This case report describes the orthodontic management of a 9 years male patient having skeletal Class II malocclusion with horizontally impacted maxillary canine. Some modifications in the treatment mechanics are deemed essential to address the patient’s need for achieving the optimal esthetic and to improve the occlusion.&#x0D; Twin block is beneficial for the treatment of skeletal malocclusion in a growing patient to achieve the maximum benefit. The orientation of impacted teeth may change from horizontal to favorable one, hence it should be considered a viable treatment alternative. In such case, early diagnosis and interception at the right time along with radiographic follow-ups are necessary to achieve successful results.&#x0D; Keywords: Canine Impaction, Class II malocclusion, Growth modification, Twin block appliance

English

BACKGROUND Skeletal class II division 1 malocclusion is an antero posterior discrepancy between maxilla and mandible which is usually treated by functional appliances when the patient is in the growing phase. It has been shown that these functional orthodontic appliances may lead to pressure on the oral mucosa, soft tissue tension, oral constriction, toothache and pain. They may also lead to fatigue or to functional speech and respiratory disorders, and they may affect the appearance of the face. All of these undesired consequences affect the patients’ degree of compliance in a negative manner, and may in turn affect the patients’ perception towards the treatment. This study was conducted to investigate patient perception of treatment need, appliance acceptance, expectations of treatment influence on oral health, value of dental aesthetics and information concerning treatment procedures. METHODS Total 30 samples were selected 15 samples were cases treated with twin block appliance and other 15 samples were treated with clear block appliance. After 8 months of treatment, a questionnaire survey was conducted assessing discomfort, expectations and experiences of all patients being treated with clear block appliance and twin block appliance. RESULTS Clear block seemed to be better with regard to all the parameters used in the study but on statistical analysis the difference between the two groups was insignificant. CONCLUSIONS Clear block appliance was designed to increase the compliance of the patient. However, clear block and twin block appliance have similar effects. KEY WORDS Class II, Clear Block, Twin Block

Comparison of twin block appliance and Forsus Fatigue Resistant Device therapies on uvulo-glossopharyngeal dimensions: A retrospective study

Objectives: The aim of this study was to compare the effects of two different functional appliances on skeletal, dental, and uvulo-glossopharyngeal dimensions. Materials and Methods: Pre- and post-treatment lateral cephalograms of 50 adolescent Class II patients with a retrognathic mandible were obtained from an archive and divided into two groups according to functional therapy. Twenty-five patients (14 females, 11 males, mean age: 13.5 ± 2.8) who were treated with Forsus Fatigue Resistant Device (FFRD) and 25 patients (17 females, eight males, mean age: 12.5 ± 0.4) who had received functional therapy through the twin block (TWB) were enrolled. Skeletal, dentoalveolar, tongue, uvula, hyoid position, and oropharyngeal airway parameters were measured using the Dolphin software, and uvulo-glossopharyngeal area measurements were performed with the AutoCAD software. Results: The TWB group exhibited remarkable mandibular advancement compared to the FFRD group (P &lt; 0.05). Both of the treatments proclined mandibular incisors, and tongue dimensions increased significantly in both groups (P &lt; 0.05). While the hyoid point moved forward and the oropharyngeal area increased significantly in the TWB group, no significant changes were observed in the FFRD group. The comparison of the TWB and FFRD groups with regard to uvulo-glossopharyngeal dimensions showed no significant differences between the groups (P &gt; 0.05). Conclusion: Changes in uvulo-glossopharyngeal dimensions did not significantly vary between the two different functional therapies.

Comparative evaluation of Skeletal, Dental, and Soft Tissue Changes in Class II Division 1 Malocclusion Cases Treated with Twin Block and innovative Clear Block Appliance - A Prospective Interventional Study

The present study was undertaken to evaluate and compare the skeletal, dental, and soft tissue changes in skeletal Class II division 1 cases treated with Twin Block and Clear Block appliances using a cephalogram. A total of 40 patients of age between 12-14 years were randomly divided into two equal groups. Group 1: treated with Twin Block appliance and Group 2: treated with Clear Block appliance. The pre-treatment lateral cephalogram was taken and skeletal, dental, and soft tissue parameters were evaluated and the appliance was delivered. After 8 months, another lateral cephalogram of all the cases was taken and analyzed. The pre and post-treatment values were compared between the two groups. The pre-treatment cases were almost comparable in skeletal, dental, and soft tissue features in both groups. There was a significant change in mandibular growth by SNB angle. The retrusion and extrusion of maxillary incisors as well as a proclination and extrusion of mandibular incisors were seen in group 1 while no change was observed in group 2. Treatment with Clear Block appliances has shown significant and favorable Skeletal, Dental and Soft tissue changes which are similar to already proven by the Twin Block appliance. Clear Block provides an esthetic and less bulky option for growth modification with similar results as compared to conventional Twin Block with the additional benefit of preventing lower incisor proclination.

Biphasic Treatment of Class II division 1 Malocclusion Using Twin Block Appliance Coordinated with Fixed Orthodontics

Biphasic Treatment of Class II division 1 Malocclusion Using Twin Block Appliance Coordinated with Fixed Orthodontics

THEEFFICIENCY OF ORTHODONTIC TREATMENT OF CLASSII MALOCCLUSION IN CHILDREN WITH β -THALASSEMIA MAJO

Aims: Evaluation of the effectiveness of orthodontic treatment of Class II malocclusion with the Twin-block appliance in children withβ-thalassemia major. Methods: The study was conducted with 49 patients with Class II malocclusion aged 10-14 years. The control group included 23 healthy patients. The main group included 26 patients with β-thalassemia major. Patients had received orthodontic treatment with a Twin-block appliance. The duration of orthodontic treatment was 1.5–2 years. Results: In both groups, a statistically significant increase in the SNB angle was observed. Subsequently, the ANB angle was normalized. The effective length of the maxilla growing and mandibular length increasing was observed. Overjet distance is decreased due to favorable torque changes. Pretreatment assessment revealed that overbite was smaller in children with β-thalassemia major. As the effect of orthodontic treatment, statistically, significant changes were observed on both overjet and overbite distances (p &lt;0.001). Conclusions: Orthodontic treatment of β-thalassemia major of patients with Twin-block appliance in mixed dentition stage is effective in improving inter arch relationships and the orofacial functions.

Investigation and comparison of patient experiences with removable functional appliances.

To compare patients' experiences with the Invisalign Teen with Mandibular Advancement® (ITMA) and Twin Block (TB) appliances, both initially and after several months of wear. Sixty-eight patients completed an anonymous survey after at least 2 months of wearing ITMA or TB. Forty-five patients treated with ITMA (18 boys, 27 girls, mean age 13.6 years, SD ± 1.54) and 23 patients treated with TB (13 boys, 10 girls, mean age 10.60 years, SD ± 1.92) were included. More patients using the TB found their appliance to be visually intimidating as compared with patients using the ITMA (21.7% vs 8.9%). TB was more noticeable than the ITMA (69.6% vs 25%). Appliance insertion was more difficult for TB patients (21.8% vs 4.44% for ITMA). After several months, there were more reports of tooth soreness and lip/cheek soreness in the ITMA group. TB patients were more embarrassed even after several months (14.3% vs 0% for ITMA). More TB patients required extra appointments for breakage (50% vs 22.2% for ITMA). Speech, drooling, and jaw and lip/cheek soreness worsened initially for both groups but improved over time. There were no differences between the groups regarding visible facial changes, satisfaction with treatment experience, or time to acclimatize to the appliance. TB and ITMA patients shared similar experiences for most of the parameters measured, but there were significant differences between the groups regarding appliance wear and management, discomfort, and function.

Long-Term Stability of Growth Modification Treatment in Children with Obstructive Sleep Apnea; A Systematic Review

Background and Objective: The aim of this study is a systematic review on the long-term stability of growth modification treatment in children with obstructive sleep apnea (SA).Methods: At first, all the papers (n=87) related to keywords (growth modification, headgear, functional therapy, herbst, twin block, forsus, AHI, orthodontics, sleep apnea, systematic review, meta-analysis) were searched for English databases; PubMed, Scopus, Embase, google scholar and Cochrane Database of Systematic Reviews covering the period from 2000 through 2021 was studied. As a result to inclusion and exclusion criteria, papers related to growth modification treatment in children with sleep apnea were found and analyzed (n=5). Predefined inclusion and exclusion criteria were: papers related to growth modification treatment for children with SA, Children 7 to 11 years old with SA grade 2 and above, follow-up 10 months to 11 years old, use of functional appliance and headgear, papers were English, papers were original and all the papers were free full text.Results: Of the 87 studies on growth modification treatment and sleep apnea, only 5 studies clinically evaluated the long-term stability of growth modification treatment on airway dimensions. Growth modification treatments for sleep apnea are very important and can play very significant role in health improvement. So, paying more attention to benefits of orthodontics therapeutic tools in sleep apnea is necessary. On important points is the orthodontist’s active role play in screening the patients for this disease and advice oral appliance therapy, if needed.Conclusion: The long-term stability of using orthodontic functional appliances in the treatment of sleep apnea in children demonstrated that the utilization of these tools can increase the width of airways in the oral cavity improving the respiratory condition in children eliminating problems associated with apnea.

Comparative analysis of the effectiveness of the use of various orthodontic appliances in the correction of malocclusion of the II class in children and adolescents

This study is dedicated to a comparative analysis of effectiveness of using orthodontic appliances when treating class II malocclusion in children and adolescents. It was shown that treatment with the Invisalign system with a change of the lower jaw position is the most effective method for correcting class II malocclusion in growing patients. Using Invisalign aligners showed not only the best efficacy according to teleroentgenograms. but also made the treatment process comfortable for patients at all its stages. Moreover, higher level of compliance was demonstrated with treatment using the Invisalign system compared to the Twin-block appliance.