Twin Block Functional Appliance Research Articles

Removable versus fixed myo-functional appliances in class II malocclusion among Indians.

It is of interest to compare two myofunctional appliances (frankal appliance and twin bloc) and two fixed orthodontic appliances (PowerScope and Forsus) in management of class II div 1 malocclusion. A total of 56 Class II division 1 malocclusion patients indicated for treatment with myofunctional appliances and fixed functional appliances were randomized. They were equally divided among frankal appliance (n=14), twin block appliance (n=14), PowerScope (American Orthodontics) (n=14), Forsus (3M Unitek Corp) groups (n=14). Skeletal and dentoalveolar effects of all appliances were compared. SNB increased remarkably by 4.2° in the Twin block group and it was high among all treatment groups. There was a significant decrease in vertical dimensions (SN-GoGn) in the Twin block (p = 0.002). Early treatment of Class II due to mandibular retrusion with Twin block functional appliance is recommended due to its favorable skeletal effect.

Reflection on patients’ experience with orthodontic appliances wear and its impact on oral health related quality of life: observational comparative study

BackgroundThe objective of this study was to explore and compare patient’s experience with the use of a removable functional appliance or fixed orthodontic appliance and its influence on oral health-related quality of life.Material and methodsThis clinical trial included 81 participants having Class II Division 1 and age ranging between 10 and 16 years. The participants were included in any of a three equal groups according to the set inclusion and exclusion criteria; Group 1: patients treated with a Twin-Block functional appliance; Group 2: patients treated with a fixed orthodontic appliance only; and Group 3 (control group): patients not in orthodontic treatment yet. The COHIP SF-19 was used. Patients were given the questionnaire as follows: Group 1: (1) after at least 8 months from starting treatment; (2) after completing phase 1 by 2–3 months without wearing the appliance; Group 2: (1) just before debonding; (2) after finishing the treatment by 2–3 months without any appliances; and Group 3: (1) at the patient’s first visit to the orthodontic clinic; (2) after 2–3 months from the first visit to the orthodontic clinic and before starting any treatment.ResultsThe 81 participants were 31 males and 50 females with median age of 13 years. The total COHIP SF-19 scores at baseline were 57 (49–64), 67 (63–72), and 47 (42–53) for the Twin-Block, the fixed appliance, and the malocclusion groups, respectively. Two-month mean scores adjusted to the baseline scores were 64.82 ± 1.15, 65.65 ± 1.47, and 54.45 ± 1.44 for the Twin-Block, the fixed appliance, and the malocclusion groups, respectively.ConclusionsBoth at baseline and two-months (adjusted to the baseline scores), participants in the malocclusion group showed compromised socio-emotional quality of life and reported the poorest total OHRQoL. At the baseline, better socio-emotional and total OHRQoL was reported by the fixed appliance group compared to the Twin-Block group but, after two months both groups gave similar sores. Therefore; patients’ perceptions about their experience with the orthodontic appliance might change.

The use of the Hanks Herbst vs Twin-block in Class II malocclusion: A randomized controlled trial

This 2-arm parallel study aimed to compare and evaluate the efficiency of Hanks Herbst (HH) and Twin-block (TB) functional appliances in treating adolescents with Class II malocclusion. A parallel-group randomized controlled trial was undertaken in a single United Kingdom hospital. Eighty participants were recruited and randomized in a 1:1 ratio to receive either the HH or TB appliance. Eligibility criteria included children aged 10-14 years with an overjet of ≥7 mm without dental anomalies. The primary outcome was the time (in months) required to reduce overjet to normal limits (<4 mm). Secondary outcomes included treatment failure rates, complications and their impact on oral health-related quality of life (OHRQOL). Randomization was accomplished using electronic software with allocation concealed using sequentially numbered, opaque, and sealed envelopes. Blinding was only applicable for outcome assessment. Data were analyzed using descriptive statistics and regression analyses to detect between-group differences, including Cox regression for time to treatment success. HH was significantly faster than TB in reducing the overjet to within normal limits (95% confidence interval [CI], -3.00 to -0.03; P= 0.046). Mean overjet reduction was more efficient with the HH than the TB appliance (ß= 1.3; 95% CI, 0.04-2.40; P= 0.04). Fifteen (37.5%) of the participants in the TB group and 7 (17.5%) in the HH group failed to complete the treatment (hazard ratio= 0.54; 95% CI, 0.32-0.91, P= 0.02). However, TB was associated with fewer routine (incidence rate ratio= 0.81; 95% CI, 0.7-0.9; P= 0.004) and emergency (incidence rate ratio= 0.1; 95% CI, 0.1-0.3; P= 0.001) visits. Chairside time was greater with the HH (ß= 2.7; 95% CI, 1.8-3.6, P= 0.001). Participants in both groups experienced complications with similar frequency. A greater deterioration in OHRQOL was found during treatment with the TB. Treatment with HH resulted in more efficient and predictable overjet reduction than TB. More treatment discontinuation and greater deterioration in OHRQOL were observed with the TB. However, HH was associated with more routine and emergency visits. ISRCTN11717011. The protocol was not published before trial commencement. No specific external or internal funding was provided. Treatment for participants was provided as part of routine orthodontic treatment in the hospital.

A comparison of children’s experiences with fixed and removable functional appliances: A qualitative study

The objective of this study was to compare children's experiences and perceptions of treatment with Hanks-Herbst (HH) and modified Twin-block (MTB) functional appliances. A pragmatic nested qualitative study was undertaken in a single hospital setting. Participants from a randomized controlled trial (International Standard Randomised Controlled Trial Number 11717011) wearing HH and/or MTB appliances were interviewed using a topic guide in a one-to-one, semistructured format. Interviews were recorded and transcribed verbatim for framework methodology analysis until data saturation was reached. Eighteen participants (HH, 7: MTB, 4; switched group, 7) were interviewed. Thirteen codes were constructed and grouped into 3 themes: (1) functional impairment and symptoms, (2) psychosocial factors and impacts, and (3) feedback on appliances and patient care. Both appliances had a negative impact on quality of life, with disruption to children's daily routines and psychological well-being. Speaking was more problematic for MTB participants, whereas HH participants encountered mastication and breakage issues. HH was preferred by most participants, as its nonremovable feature meant less managing and self-discipline was required. MTB was considered a suitable option for children with good self-discipline and who preferred a versatile lifestyle. Feedback included wishes for the availability of multiple appliance options and a degree of autonomy in decision-making processes. HH and MTB can negatively affect children's quality of life. Participants preferred HH over MTB because of its nonremovable feature, and children requested to be empowered during decision-making processes.

Evaluation of Changes in Soft and Hard Tissues of TMJ among Class II Division 2 Patients after Prefunctional Orthodontics and Twin Block Functional Appliance Therapy: A Prospective MRI Study.

No study has been conducted to explore soft and hard tissue changes brought by functional appliances within the temporomandibular joint (TMJ) after correction of class II division 2 (div 2) malocclusion. Hence, we planned this study to evaluate the mandibular condyle disk-fossa relationship before and after prefunctional and twin block therapy using a magnetic resonance imaging (MRI) scan. This prospective observational study was conducted among 14 males treated with prefunctional appliances for 3-6 months, followed by 6-9 months of fixed mechanotherapy. MRI scan was evaluated for changes in the TMJ at baseline after completion of prefunctional phase and after completion of functional appliance therapy. At pretreatment, there was a flat contour on the posterosuperior surface of the condyles and a notch-like projection on its anterior surface. After functional appliance therapy, slight convexity appeared on the posterosuperior surface of the condyle and the prominence of the notch was reduced. There was a statistically significant anterior shift of condyles both after prefunctional and twin block treatment. The meniscus on both sides had significantly shifted posteriorly over three stages with respect to the posterior condylar (PC) plane and Frankfort horizontal (FH) plane. The superior joint space had significantly increased with significant linear glenoid fossa displacement between pre and posttreatment stages. Prefunctional orthodontics induced favorable changes in TMJ soft and hard tissues of patients, but they were not sufficient to place the soft and hard tissues in their normal positions. A functional appliance phase is needed to place the TMJ in their respective normal positions. Patel B, Kukreja MK, Gupta A, et al. Evaluation of Changes in Soft and Hard Tissues of TMJ among Class II Division 2 Patients after Prefunctional Orthodontics and Twin Block Functional Appliance Therapy: A Prospective MRI Study. Int J Clin Pediatr Dent 2022;15(5):479-488.

Changes in Angulation and Eruption Space of Developing Mandibular Third Molars Following Twin Block Treatment

The aim of this study was to assess the effects of twin block functional appliance three dimensionally on mandibular third molars angulation and eruption space. This retrospective study included cone beam computer tomography (CBCTs) of 34 Class II females (11.84 ± 0.94 years) who were divided into 2 groups. The first group received a standard twin block appliance (intervention group), while the other was considered as a control. CBCT images were obtained for all patients before the start of the intervention (T0) and after the active phase (9.4 ± 1.33 months) in the intervention group and at the beginning (T0) and after the observation period (T1) in the control group (8.12 ± 2.72 months). Measurements for the retromolar space were performed on the axial views, while those for molar angulation were performed on sagittal views as well as CBCT panoramic reformatted images. Both twin block and control groups showed non-significant changes in the angular measurements (sagittal L8/MP° and panoramic L8/MP°) denoting lack of change in the angulation of the third molars in relation to the mandibular plane after treatment. On the other hand, retromolar spaces showed a statistically significant increase (P ≤ .05) in both groups. The change was much significant for the twin block group, measuring 1.95 mm and 1.56 mm on the right and left sides, respectively, as compared to the control group which revealed less than 1 mm increase in the retromolar space on both the right and left sides. In spite of their positive impact on the retromolar space, twin block bite jumping appliances have a non-significant influence on the angulation of the developing mandibular third molars.

Comparison of cephalometric measurements of the Twin Block and A6 appliances in the treatment of Class II malocclusion: a retrospective comparative cohort study.

BackgroundSkeletal Class II malocclusion is a common malocclusion that seriously affects patients’ profile and occlusal function. The key to treatment is to use functional appliances guide the mandible forward. This study aimed to evaluate the clinical efficacy of traditional functional appliance Twin Block (TB) and invisible functional appliance (A6).MethodsIn the retrospective cohort study, 46 patients with Class II Division 1 mandibular retrognathia (23 females, 23 males; mean age 13.66±4.25 years) from the Third Affiliated Hospital of Sun Yat-sen University were selected. They were divided into A6 group and TB group according to the type of appliance guided mandibular forward used in orthodontic treatment (n=23 each; average treatment time 9.82±3.52 months). Lateral cephalometric radiographs were taken before and at the end of each treatment, and paired t-test or paired rank-sum tests were performed when appropriate to detect any statistical significance at the level of α=0.05.ResultsThe baseline characteristics of the two groups of patients were similar. Treatment with both appliances helped correct Class II malocclusion, improve the discrepancy between the maxilla and mandible, reduce the labial inclination of the maxillary anterior teeth, and relieve the deep overbite. A comparison of the treatment effects of the TB and A6 groups showed that the A6 had a better effect when moving Point A backward, and performed better in the abduction of the anterior teeth. TB group has more advantages than A6 group in moving forward point B and improving the nasolabial angle.ConclusionsBoth the A6 and TB can significantly improve Class II malocclusion. A6 showed an obvious advantage in moving Point A backward and adducting the anterior teeth, which better corrects a skeletal Class II malocclusion.

Treatment of a class II malocclusion patient with twin block appliance: a case report

&lt;p&gt;Class II malocclusions in growing patients is commonly encountered and respond well to functional appliances, provided the clinical and cephalometric findings are favourable. In case of class II hypodivergent malocclusion, the hypodivergent pattern is established early and become prominent with progression of time. These patients have significantly smaller mandibular plane angles and smaller gonial angles. This case report describes the treatment planning of a patient of age 14 years with class II malocclusion showing hypodivergent growth pattern and moderate crowding. Treatment was started with twin block functional appliance and non-extraction approach was planned. As the patient was in his peak growth spurt stage, the functional appliance therapy use at this stage was started to take advantage of that. Fixed orthodontic appliances were placed after completion of functional appliance therapy. The treatment resulted in achievement of class I molar relation bilaterally, normal overjet and overbite and favourable soft tissue profile, facial balance and harmony.&lt;/p&gt;

The Effectiveness of Using Twin Block Functional Appliances and Activators in Class II Malocclusion

The Effectiveness of Using Twin Block Functional Appliances and Activators in Class II Malocclusion

Predictors of soft tissue profile outcomes after Twin-Block appliance

Clark's Twin-Block (CTB) functional appliance is commonly used to treat mandibular deficiency in skeletal class II growing patients. This study was conducted to identify cephalometric predictors for favorable soft tissue profile outcomes with CTB appliance. Using pre- and post-functional lateral cephalograms of 50 subjects treated with CTB, profile silhouettes were evaluated by a panel of orthodontists to assess improvement using the Visual Analogue Scale (VAS). Subjects were divided into favorable and unfavorable groups on the basis of VAS scores. Independent sample t-test was used to compare cephalometric skeletal and soft tissue measurements between the groups. Predictors of favorable and unfavorable outcomes were identified using the logistic regression analysis. Statistically significant differences in multiple pre-treatment values between favorable and unfavorable groups were observed. Multivariable logistic regression analysis found the decreased value of lower lip to E line (95% CI: 0.142, 0.800) and decreased pogonion to nasion perpendicular distance (95% CI: 1.05, 1.85) to be significantly associated with favorable soft tissue profile outcomes. Pre-treatment hypodivergent skeletal pattern, reduced ANB, reduced lower incisor to pogonion distance and soft tissue recumbency were identified as predictors of favorable soft tissue outcomes for CTB treatment in growing patients with mandibular retrognathism.

Structural changes in the trabecular bone of the mandibular condyle of growing patients with sagittal jaw discrepancy treated with the twin-block appliance.

The objective of this study was to evaluate the structural changes in the trabecular bone of the mandibular condyles in patients treated with the Twin-block functional orthopaedic appliance that act by promoting condylar growth and to compare the fractal dimension (FD) of condylar trabecular bone structure prior to treatment (T0) and after orthopaedic functional treatment (T1). This retrospective study included panoramic images of 112 individuals with a mean age of 11.04±1.30years in the study group (32 girls and 24 boys) and 11.6±.80years in the control group (29 girls and 27 boys). The standardized region of interest was selected as the right and left condylar areas close to the articulation surfaces from the twin-block (TB) group, which included patients who completed functional orthopaedic treatment and the control group, which included untreated individuals. FD values in the condylar region were analysed from the panoramic radiographs of both groups using a box-counting method with ImageJ software (version 1.52a, US National Institutes of Health). There was a significant decrease in the FD values of the right (-.038) and left (-.022) condylar region at T0 and T1 in the TB group. Between-group FD comparisons demonstrated that the TB group showed changes in the condylar region (right, P=.004; left, P=.022) compared to the control group. Functional orthopaedic forces caused a decrease in the trabecular structure of the condylar area examined.

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.

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.

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.

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.

Evaluation of skeletal changes in mandibular ramus height, corpus length, and mandibular angle changes following twin block appliance therapy using cone-beam computed tomography: A clinical prospective study

Aim and Objectives: This study aims to evaluate the skeletal changes in mandibular ramus height, corpus length, and mandibular angles changes following twin block (TB) functional appliance therapy using cone-beam computed tomography (CBCT).Methodology: Fifteen patients with skeletal Class II, growing of 9–14 years of age with mandibular retrognathism, were treated with TB functional appliance treatment. Pretreatment CBCT and posttreatment CBCT were taken (T0) before treatment and (T1) at the end of the 12 months following TB therapy. The data obtained are analyzed and compared for the skeletal changes in ramus height, corpus length, and mandibular angle changes following therapy. Student's paired t-test was used compare the pre- and post-treatment periods.Results: The test results demonstrate that the Ramus height (mm) in posttreatment period was significantly increased as compared to pretreatment period. The mean increase of 1.23 mm in the ramus height between pre- and post-treatment period was statistically significant at P < 0.001, and that the corpus length (mm) in posttreatment period was significantly increased as compared to pretreatment period. The mean increase of 3.35 mm in the corpus length between pre- and post-treatment period was statistically significant at P < 0.001, and demonstrate that the mean gonial angle (degrees) in posttreatment period was significantly increased as compared to pretreatment period. This mean increase of 3.18° in the gonial angle between pre- and post-treatment period was statistically significant at P < 0.001.Conclusion: TB appliance therapy increases the ramus height, and corpus length stimulating the growth of condyle in backward and upward direction and increases the gonial angle by backward rotation of mandible.

Multistage Treatment of a Class II Division 1 Malocclusion With Severe Crowding

The improvement of facial aesthetics is one of the main reasons why patients with a class II division 1 malocclusion seek orthodontic treatment. There are various techniques available to treat class II malocclusions, one of which is a two-phase approach that includes functional jaw orthopedics as well as fixed orthodontic treatment. The following case report describes the case of a 12-year-old growing female patient AK with a severe class II division 1 malocclusion. The patient was treated initially with Haas-type rapid maxillary expansion. Pre-functional orthodontics was followed with a removable twin block functional appliance and a combination pull headgear for growth modification and correction of her overjet and profile. Thereafter, a fixed, pre-adjusted MBT (McLaughlin Bennet Trevsi) prescription orthodontic appliance was utilized following the extractions of the maxillary first premolars and two lower incisors in the final phase, to ensure well-aligned arches and improved aesthetics and function.

Three-dimensional cone beam computed tomography analysis of temporomandibular joint response to the Twin-block functional appliance.

ObjectiveTo propose a three-dimensional (3D) method for evaluating temporomandibular joint (TMJ) changes during Twin-block treatment.MethodsSeventeen patients with Class II division 1 malocclusion treated using Twin-block and nine untreated patients with a similar malocclusion were included in this research. We collected their cone beam computed tomography (CBCT) data from before and 8 months after treatment. Segmentations were constructed using ITK-SNAP. Condylar volume and superficial area were measured using 3D Slicer. The 3D landmarks were identified on CBCT images by using Dolphin software to assess the condylar positional relationship. 3D models of the mandible and glenoid fossa of the patients were constructed and registered via voxel-based superimposition using 3D Slicer. Thereafter, skeletal changes could be visualized using 3DMeshMetric in any direction of the superimposition on a color-coded map. All the superimpositions were measured using the same scale on the distance color-coded map, in which red color represents overgrowth and blue color represents resorption.ResultsSignificant differences were observed in condylar volume, superficial area, and condylar position in both groups after 8 months. Compared with the control group (CG), the Twin-block group exhibited more obvious condyle-fossa modifications and joint positional changes. Moreover, on the color-coded map, more obvious condyle-fossa modifications could be observed in the posterior and superior directions in the Twin-block group than in the CG.ConclusionsWe successfully established a 3D method for measuring and evaluating TMJ changes caused by Twin-block treatment. The treatment produced a larger condylar size and caused condylar positional changes.

Evaluation of cervical spine posture after functional therapy with twin-block appliances: A retrospective cohort study.

It has been postulated that a change in cervical posture occurs as a consequence of forward repositioning of the mandible. Therefore, the objective of this study was to compare the cervical spine posture between subjects with and without functional appliance therapy. A retrospective cohort study was conducted with the use of pre- and post-functional therapy cephalograms of orthodontic patients. A total of 60 subjects was composed of 2 groups of 30 subjects each: those who underwent treatment with a twin-block (TB) functional appliance and a control group selected from the Bolton-Brush Growth Study. Three sagittal and 7 cervical vertebral parameters were compared between the groups. The Wilcoxon signed-rank test was used to compare pre- and postfunctional mean angular measurements. The Mann-Whitney U test was used to compare the mean changes in cervical parameters between the groups. A significant difference existed between pre- and postfunctional SNB (P<0.001) and ANB (P<0.001) angles, showing a change in maxillomandibular relationship. Comparison of mean changes in angular measurements between the 2 groups showed a significant difference (P=0.032) in the sella-nasion to odontoid process tangent (SN-OPT) angle. The SN-OPT angle predicted that the probability of developing an altered cervical posture with the TB appliance is 2.08 times greater than without the TB appliance. SN-OPT angle can predict a change in skeletal relationships after treatment with the TB functional appliance. The TB causes the craniocervical posture to be more upright. Subjects with reduced vertical dimensions have greater change in cervical posture.

Three-dimensional skeletal, dentoalveolar and temporomandibular joint changes produced by Twin Block functional appliance.

The aim of this study was to three-dimensionally analyze the net skeletal, dental, and temporomandibular joint (TMJ) treatment changes using Twin Block functional therapy in comparison to untreated subjects. The study (Twin Block) group comprised 22female patients with skeletal ClassII malocclusion due to mandibular retrusion. A total of 18skeletal ClassII untreated female subjects were included as controls. Skeletal, dental, and TMJ changes were evaluated using pre- and posttreatment/observational by cone beam computed tomography (CBCT) images. The treatment changes were compared with the growth changes observed in the control group using independent t‑tests. Compared to the changes induced by normal growth, the effective mandibular length, ramus, and corpus lengths increased by 3.19, 3.47, and 2.69 mm (P < 0.001 for all), respectively. The maxillary and mandibular incisors inclination and position were significantly reduced and increased, respectively (P < 0.001). The maxillary first molars were significantly moved distally and intruded by 1 and 0.36 mm, respectively, while the lower first molars moved mesially and intruded by 2.18 and 0.59 mm, respectively. There was asignificant change in the condylar dimensions: increase in length, width, and height by 1.28, 0.88, 1.59 on the right and by 1.60, 0.53, and 1.10 mm on the left sides, respectively. There was significant forward positioning of the right and left condyle by 1.5 and 1.3 mm, respectively. Treatment with the Twin Block functional appliance results in significant skeletal, dentoalveolar, and condylar changes in both dimensions and positions.