Twin Block Research Articles

Influence of myofunctional therapy on oropharyngeal airway dimensions in skeletal class II cases - a cephalometric study

Skeletal Class II malocclusion is associated with a multitude of functional problems one of which is reduced oropharyngeal airway dimension. The airway is receiving renewed attention in recent literature regarding snoring and obstructive sleep apnoea syndrome especially as a retrognathic mandible is often implicated as its cause. The study was undertaken to investigate the myofunctional appliance (TWIN BLOCK) effects on the oropharyngeal airway dimensions in Skeletal Class II individuals in the average age of 11-13 years. This study also expresses the existence of any correlation between airway dimension and craniofacial morphology.

A radiographic comparison of apical root resorption between Herbst and Jumper twin block bite appliances

Objectives: The objectives of this study were to compare the amount of apical root resorption after orthodontic treatment with Herbst and Twin Block Bite Jumping screw (TBBJS) functional appliances, also to determine the prevalence of root resorption in the maxillary and mandibular incisors and the dental arches. Methods: 30 patients were divided into two groups 15 patients each. The first group was treated with Herbst appliance and the second group with TBBJS appliance. After treatment, periapical radiographs were obtained of the maxillary and mandibular incisors with the long-cone paralleling technique. Root resorption was scored according to the method of Levander and Malmgren. Results: Results of the Mann-Whitney U test showed that there were no statistically significant differences between the Herbst and TBBJS groups. The amounts of root resorption were predominantly small. The prevalence of resorption for the incisors was greatest for the maxillary central, followed by the maxillary lateral, mandibular central, and mandibular lateral incisors. Conclusions: There was no difference in the amount of root resorption between the Herbst and TBBJS groups with more resorption in maxillary arch than mandibular arch.

Early Orthodontic Treatment may be Effective in Modifying Class ll Skeletal and Dental Outcomes

Effectiveness of early orthodontic treatment with the twin block appliance: a multicenter, randomized controlled trial. Part 1: Dental and skeletal effects. O’Brien K, Wright J, Conboy F, Sanjie YW, Mandell N, et al. Am J Orthod Dentofacial Orthop 2003;124:234-43. Katherine W.L. Vig, BDS, MS, D Orth, FDS.RCS (Eng) In children with Class ll malocclusion, is early treatment with a functional appliance (Twin Block) effective in improving skeletal and dental changes when treatment is provided in private orthodontic practices? National Health Service in UK Randomized controlled trial Level 1: Good quality, patient-oriented evidence Grade A: Consistent, good-quality, patient-oriented evidence.

Soft tissue effects of Twin Block and Herbst appliances in patients with Class II division 1 mandibular retrognathy

The aim of this study was to evaluate and compare the changes in soft tissue profile related to treatment with Twin Block and Herbst appliances. Sixty Class II, division 1, mandibular retrognathic patients were divided into three groups. Forty patients were randomly allocated to one of two functional appliance treatment groups. The first group comprised 11 girls and 9 boys (mean age= 12.74 ± 1.43 years) treated with the Herbst appliance. The second group comprised 10 girls and 10 boys (mean age = 13.0 ± 1.32 years) who received treatment with Twin Block appliance. The untreated control group included 9 girls and 11 boys with a mean age of 12.17 ± 1.47 years. Mean treatment time was 15.81 ± 5.96 and 16.20 ± 7.54 months for Herbst and Twin Block groups, respectively. The observation period of the control group was 15.58 ± 3.13 months. Pre-treatment (T0) and post-treatment (T1) cephalograms were used to evaluate skeletal, dentoalveolar, and especially soft tissue changes. The groups were compared at T0 and T1 using analysis of variance, and treatment/observation differences (T1 - T0) were evaluated with paired samples t-test at P < 0.05 level. Soft tissue convexity, H angle, and mentolabial angle decreased in both treatment groups compared to control. Statistically significant treatment changes were found for mandibular soft tissue measurements in Twin Block group and to a lesser extend in Herbst group. Both appliances reduced the soft tissue profile convexity when the nose is not taken into consideration. Greater advancement of mandibular soft tissues was observed in Twin Block group.

Two-phase treatment of class II malocclusion in young growing patient

The use of functional jaw orthopedics, at the correct time during growth, can ultimately result in malocclusion patients achieving a broad beautiful smile, an excellent functional occlusion, a full face with a beautiful jaw line and lateral profile. Following is a case report of a young growing individual with mandibular retrognathia. Treatment was planned in two stages with the use of twin block during the first phase for correction of skeletal malocclusion and forward positioning of the mandible, followed by the second phase of fixed pre-adjusted edgewise orthodontic appliance for camouflaging the remaining skeletal discrepancy and achieving a stable harmonious occlusion.

Accidental ingestion of a fractured Twin-block appliance

Orthodontic appliances that become dislodged can cause problems in the airway or the gastrointestinal tract. Accidental ingestion of an appliance during a chair-side procedure or because of inadequate retention of the appliance can create a medical emergency with potentially serious complications, including death from aspiration of the foreign body. This article reports the accidental ingestion of a fractured Twin-block appliance. The ease with which removable appliances can become dislodged if retention is inadequate is discussed, and some serious complications that can arise are described. Precautions the orthodontist can take to prevent such accidents are presented.

Malocclusions de classe II : bien choisir le moment du traitement pour optimiser l’effet orthopédique des appareils fonctionnels

Time can be considered the fourth dimension in dento-facial orthopedics. Treatment timing can play a significant role in the outcomes of treatment aimed to produce an orthopedic effect in the craniofacial structures. The results of methodologically-sound cephalometric studies of both the past and the recent history of orthodontics clearly indicate that optimal treatment timing for Class II skeletal disharmony with a functional appliance (e.g. twin block) is during or slightly after the peak in mandibular growth as revealed by a reliable biologic indicator of individual skeletal maturity such as the cervical vertebral maturation method.

The effect of a Clark twin block on mandibular motion: a case report

Abstract Aims To investigate mandibular motion in six degrees of freedom before, during and after twin block treatment in one individual. Methods The appliance was worn for eight months, and motion recordings, using a 12-camera opto-electric system, were captured prior to placement of a twin block appliance and 2, 4, 14 and 52 weeks after insertion. Results The wide variations in mandibular motion that accompany twin block wear disappeared post-treatment, except for an increase in anteroposterior movement of the mandible. Conclusion Twin block therapy appears to affect mandibular motion temporarily.

Treatment effects of the R-appliance and twin block in Class II division 1 malocclusion

The purpose of this study was to compare the effects of a differently designed functional appliance (the R-appliance) with a twin-block (TB)-treated group. Thirty patients (18 girls and 12 boys) with a mean age of 10.5±0.7 years were treated with the R-appliance for 16.2±0.3 months and 25 (11 boys and 14 girls) with a mean age of 11.2±1.3 years with a TB for 16.1±1.4 months (control). All had a Class II division 1 malocclusion due to mandibular deficiency. Lateral cephalograms obtained at the beginning (T1) and end (T2) of the study were analysed. Paired t-tests showed that SNB significantly increased in both groups. The incisor mandibular plane angle (IMPA) was reduced in the R-appliance group by 1.9±4.9 degrees (P<0.04) but increased by 0.5±5.1 degrees (P<0.6) in the TB group. SNA in the R-appliance group showed an increase of 0.2±1.8 degrees (P<0.5), while it was decreased by 0.2±1.3 degrees (P<0.3) in the TB group. Both treatment modalities were successful in moving the mandible forward. However, with the R-appliance, this was achieved without retroclination of the lower incisors.

Class II malocclusion treatment using combined Twin Block and fixed orthodontic appliances - A case report.

The effect of the Twin Block functional orthodontic appliances is mostly dento-alveolar with small skeletal effect. There are certain clinical indications where functional appliances can be used successfully in class II malocclusion e.g. in a growing patient. The use of these appliances is greatly dependent on the patient's compliance and they simplify the fixed appliance phase. In this case, a 13-year old adolescent was treated with Twin Block appliance followed by fixed appliance to detail the occlusion. The design and treatment effects were demonstrated in this case report.

Masseter muscle thickness as a predictive variable in treatment outcome of the twin-block appliance and masseteric thickness changes during treatment

To estimate the association of initial masseter muscle thickness with treatment outcomes using functional appliances and the effect of treatment on masseter muscle thickness. Twenty-two children, aged 8-12, with skeletal and dental class II relationships and increased overjet were treated with twin-block appliances for 9-17 months, until a class I molar relationship and decreased overjet was achieved. Dental casts, lateral cephalograms, and ultrasonographic measurements of the masseter muscle were performed before and after treatment. Twenty-two children, aged 8-12, without immediate need for orthodontic treatment, served as controls. They were observed for 11-17 months, and ultrasonographic masseter muscle measurements were taken before and after the observation period. Masseter muscles in treated children were thinner at the end of treatment, while untreated controls showed an increase in thickness. Treated children with thinner pre-treatment muscles showed greater mandibular incisor proclination, distalisation of maxillary molars, and posterior displacement of the cephalometric A point during treatment. Treatment of a dental class II relationship with functional appliances leads to mild atrophy of the masticatory muscles, possibly because of their decreased functional activity. The initial condition of the muscles may be associated with mandibular incisor proclination, and the position of maxillary first molars and A point.

Aparelho de avanço mandibular aumenta o volume da via aérea superior de pacientes com apneia do sono

INTRODUÇÃO: o diagnóstico, o tratamento e o acompanhamento de pacientes portadores da síndrome da apneia obstrutiva do sono (SAOS) são essenciais, por se tratar de um distúrbio que pode causar alterações sistêmicas. A efetividade do tratamento da SAOS com aparelhos intrabucais foi demonstrada através de estudos cefalométricos. OBJETIVO: o objetivo deste estudo foi avaliar o efeito do aparelho de avanço mandibular (Twin Block, TB) no volume das vias aéreas superiores, por meio de tomografia computadorizada Cone-Beam (CBCT). Dezesseis pacientes (6 homens e 10 mulheres) portadores de SAOS leve a moderada, idade média de 47,06 anos, utilizaram um aparelho de avanço mandibular e foram acompanhados por 7 meses, em média. MÉTODOS: foram feitas duas CBCT, sendo uma sem e outra com o aparelho em posição. A segmentação e a obtenção dos volumes das vias aéreas superiores foram realizadas e utilizado o teste t de Student pareado para análise estatística, com 5% de significância. RESULTADOS: houve aumento do volume da via aérea superior com TB quando comparado com o volume sem TB (p&lt;0,05). CONCLUSÃO: pode-se concluir que o aumento de volume da via aérea superior observado foi associado ao aparelho de avanço mandibular.

Design and management of Twin Blocks: reflections after 30 years of clinical use

The objective of this article is to correct some misconceptions that have arisen since the introduction of Twin Blocks, to identify factors leading to reduced efficiency and increased failure rate, and to improve the clinical application of Twin Block technique.

Editor's Comment and Q&A: Comparison of Twin-block and Dynamax appliances for the treatment of Class II malocclusion in adolescents: A randomized controlled trial

Introduction The aim of this study was to compare the effectiveness of Twin-block and Dynamax appliances for the treatment of Class II Division 1 malocclusion. Methods This was a randomized controlled trial involving 32 boys and 32 girls aged 10 to 14 years with Class II Division 1 malocclusion. They were randomly allocated to either the Dynamax appliance group or the Twin-block appliance group. Treatment was provided by 4 clinicians at 2 centers. Records were taken at the start and the end of the functional phase and after all treatment. In addition, incisal overjet, the number of appliance breakages, and adverse events or side effects of the treatment were recorded at each patient visit. Results The data monitoring committee in an interim analysis at 18 months after the start of the trial found significantly greater overjet reduction in the Twin-block group than in the Dynamax group and more breakages and adverse events with the Dynamax appliance. As a result, treatment with the Dynamax appliance was terminated, and those patients completed treatment with the Twin-block or a fixed appliance. Regression analysis showed a statistically significant difference in the performance over time between the Twin-block and Dynamax appliances in terms of reduction in overjet, with the Twin-block appliance performing significantly better than the Dynamax. The incidence of adverse events was greater in the Dynamax group (82%) than in the Twin-block group (16%), with a statistically significant difference (P Conclusions The Twin-block appliance was more effective than the Dynamax appliance when overjet was evaluated and the Dynamax appliance patients reported greater incidence of adverse events with their appliance than those who were treated with the Twin-block appliance.

Comparison of Twin-block and Dynamax appliances for the treatment of Class II malocclusion in adolescents: A randomized controlled trial

The aim of this study was to compare the effectiveness of Twin-block and Dynamax appliances for the treatment of Class II Division 1 malocclusion. This was a randomized controlled trial involving 32 boys and 32 girls aged 10 to 14 years with Class II Division 1 malocclusion. They were randomly allocated to either the Dynamax appliance group or the Twin-block appliance group. Treatment was provided by 4 clinicians at 2 centers. Records were taken at the start and the end of the functional phase and after all treatment. In addition, incisal overjet, the number of appliance breakages, and adverse events or side effects of the treatment were recorded at each patient visit. The data monitoring committee in an interim analysis at 18 months after the start of the trial found significantly greater overjet reduction in the Twin-block group than in the Dynamax group and more breakages and adverse events with the Dynamax appliance. As a result, treatment with the Dynamax appliance was terminated, and those patients completed treatment with the Twin-block or a fixed appliance. Regression analysis showed a statistically significant difference in the performance over time between the Twin-block and Dynamax appliances in terms of reduction in overjet, with the Twin-block appliance performing significantly better than the Dynamax. The incidence of adverse events was greater in the Dynamax group (82%) than in the Twin-block group (16%), with a statistically significant difference (P <0.001) between the 2 groups. The Twin-block appliance was more effective than the Dynamax appliance when overjet was evaluated and the Dynamax appliance patients reported greater incidence of adverse events with their appliance than those who were treated with the Twin-block appliance.

Functional jaw orthopaedics for management of Class II division 1 malocclusion

Malocclusion is a deviation from rarely attained ideal arrangement among teeth (normal occlusion) that does not necessarily cause a functional problem [1]. Class II Division 1 malocclusion is characterised by the mandibular dentition “distal” to the maxillary dentition; the malrelation may be due to a basic osseous dysplasia or due to forward movement of the maxillary dental arch and alveolar processes or combination of skeletal and dental factors. The purpose of dentofacial orthopaedics is to modify the pattern of facial growth and the underlying bone structure of the face. The objective is to promote harmonious facial growth by changing the functional muscle environment around the dentition. The principle of functional therapy is to reposition a retrusive mandible to forward position by constructing an appliance with a protrusive bite when the appliance is placed in the mouth. The mechanics are reversed to correct a retrusive maxilla, but the principle remains the same [2]. The twin block appliance (TBA), described by William J Clark in 1982, is considered the most successful functional appliance in the treatment of Class II division 1 malocclusion. [3]. The TBA incorporates the use of upper and lower bite blocks, interfacing at 70° to achieve the desired forward position of the mandible and redirect occlusal forces to achieve rapid correction of malocclusion.

Assessed facial normality after Twin Block therapy

The first aim of this study was to identify any difference in the perception of facial normality between orthodontists and lay people of patients with the initial presentation of a Class II division 1 malocclusion, the second is to investigate whether there was an identifiable facial change following Twin Block (TB) therapy, and lastly, the relationship between identifiable facial change and clinical measurements was explored. Animated laser scans of 16 randomly selected adolescent patients, nine males aged 12-14 years and seven females aged 11-13 years with Class II division 1 malocclusions before and after TB therapy, were assessed on a visual analogue scale (VAS) by 34 orthodontists and 35 lay people. The 'Mark and Measure' and 'Orientated' techniques were used to determine soft tissue dimensions. Overjet was also recorded. Non-parametric statistical analyses were employed, including Mann-Whitney, Wilcoxon signed value, and Spearman's rank-order correlation tests. There was no statistically significant difference in facial normality scores of adolescents before TB therapy when assessed by orthodontists (46.2 mm) and lay people (50.9 mm; P = 0.120). However, TB therapy significantly improved the assessment score of the orthodontists (54.8 mm) and lay people (57.8 mm; P = 0.000). Using a 5 per cent threshold in categorization of change in VAS scores, the majority of assessors perceived an overall 'improvement' (87.0 per cent). An increase in soft tissue lower face height (ST LFH) and overjet reduction was strongly correlated with the higher assessments of lay people (r = 0.515) and orthodontists (r = -0.505), respectively. Although orthodontists and lay people assess facial normality of patients with Class II division 1 malocclusions similarly, following TB therapy an increase in ST LFH with lay people and overjet reduction with orthodontists were most closely related to improved facial normality.

Long-Term Dentoskeletal Changes with the Bionator, Herbst, Twin Block, and MARA Functional Appliances

To determine if the long-term dentoskeletal changes in patients treated with tooth-borne functional appliances were comparable to each other and to matched controls. The experimental sample consisted of 80 consecutively treated patients who were equally divided into Bionator, Herbst, Twin Block, and mandibular anterior repositioning appliance (MARA) groups. The control group comprised 21 children with untreated skeletal Class II malocclusions. Lateral cephalograms were taken for the treated group at T1 (initial records), T2 (completion of functional therapy), and T3 (completion of fixed appliance therapy). A repeated measure analysis of variance (ANOVA) was used to assess the differences between and within groups. If ANOVA results were significant, Tukey-Kramer tests were used to determine where the significant differences occurred. (1) Temporary restriction of maxillary growth was found in the MARA group (T2-T1). (2) SNB increased more with the Twin Block and Herbst groups when compared with the Bionator and MARA groups. (3) The occlusal plane significantly changed in the Herbst and Twin Block groups. (4) The Twin Block group expressed better control of the vertical dimension. (5) The overbite, overjet, and Wits appraisal decreased significantly with all of the appliances. (6) The Twin Block group had significant flaring of the lower incisors at the end of treatment. (7) Over the long-term, there were no significant soft tissue changes among treated and untreated subjects. No significant dentoskeletal differences were observed long-term, among the various treatment groups and matched controls.

A Comparative Cephalometric Study of Skeletal and Dental Changes in Class-2 Division-1 Malocclusions Treated with Twin Block and Jasper Jumper Appliance

A Comparative Cephalometric Study of Skeletal and Dental Changes in Class-2 Division-1 Malocclusions Treated with Twin Block and Jasper Jumper Appliance

Dents-Skeletal effects of twin block-headgear in treatment of Class II malocclusion cases

Objective: To evaluate dental and skeletal effects of Twin Block-Headgear combination in treatment of Class II malocclusion cases. Material and Methods: Twenty five female growing patients with skeletal Class II due to both mandibular retrognathism and maxillary prognathism were selected. Fifteen patients were treated using Twin Block with high pull headgear (TB-HG group) for nine months, while the other ten patients had no treatments (control group). For each patient, lateral cephalometric x-ray film was taken at the start and the end of active functional treatment period and then traced and analyzed. The collected data were subjected to t test to assess the significant differences in the changes in measurements between the two groups. Results: The TB-HG group showed a significant maxillary growth restriction and enhancement of the mandibular growth. The upper and lower incisors were significantly retroclined and proclined respectively. The maxillary molars moved distally while the mandibular molars moved mesialy. The mandibular plane and palatal plane angles showed no significant changes. Conclusions: Twin Block-Headgear appliance could be used successfully in treatment of skeletal Class II malocclussion due to maxillary protrusion and mandibular retrusion without adverse changes in the mandibular plane angle.