Twin Blocks Research Articles

Clear Twin Block Versus Traditional Twin Block: a Clinical Electromyographic Comparison

Background: Functional appliances such as twin blocks are widely used to treat skeletal Cl II malocclusions. Myofunctional effects are one of the critical features of these appliances. The present study aimed to investigate the muscular effects of clear and traditional twin blocks. Methods: In this randomized clinical trial, 60 skeletal Cl II div 1 patient were randomly divided into two groups: clear twin block (CTB) and traditional twin block (TTB). Electromyographic (EMG) evaluation of masseter, anterior temporalis, orbicularis oris, and mentalis muscles was carried out during deglutition, rest, whistling, and forced occlusion before insertion (T1) and six months (T2) after insertion of the appliance. Data were analyzed using independent t-test, paired t-test, and Wilcoxon’s signed rank at the 0.05 significance level. Results: There were no significant differences in T2 values between the groups (P>0.05). The intragroup comparisons showed a significant change from T1 to T2 in the CTB group for the clenching of the masseter muscle and in the TTB group for swallowing and rest position of the anterior temporalis muscle and swallowing of the masseter muscle (P<0.05). Conclusion: Both CTB and TTB changed the muscular activity of circumoral muscles. No significant difference was found when the post-treatment muscular activity of the two groups was compared.

Incline Correct: A Novel Device for Accurate Inclination of Twin Block Appliances

Retrognathic mandible is the most common feature in growing children with skeletal Class II malocclusion. This does not self-correct with growth. Functional appliances are known to exert beneficial effects to improve this skeletal pattern. Among several removable functional appliances, Twin Block is the most preferred. Twin Blocks are designed for full-time wear such that maximum benefit from functional forces can be obtained. The maxillary and mandibular bite blocks occlude at a 70° angle on complete closure. It is important to angulate the inclines at exactly 70°, as an increase in this angulation will require a conscious effort from the patient. Incline Correct is designed to accurately measure and construct inclines at 70° to the occlusal plane.

Distal mandibular position treatment in adolescence: use of twin blocks

Class II malocclusion was described by Angle, a classification based on the discrepancy in the anteroposterior direction. From the therapeutic point of view, Class II malocclusion due to mandibular retrusion has been approached with different treatments. Twin blocks are functional appliances that reposition the mandible and redirect occlusal forces. A clinical case of a young Class II patient with mandibular distoposition using Twin Blocks is developed. It will be confirmed if the principles and objectives developed by Clark are evident in our patients.

3D printed twin block: A feasibility study

AimsTwin blocks are appliances used for Class II skeletal discrepancies, where the lower jaw is positioned more posteriorly compared to the upper. The conventional method of fabrication of this appliance is tedious and labour-intensive; hence this study intends to explore the feasibility of a digital workflow to three-dimensionally (3D) print them. MethodsThree sets of twin blocks, identical except for amount of offset (0.0 mm, 0.1 mm and 0.2 mm), were designed and 3D printed for 5 anonymized scans of patients with Class II skeletal discrepancies. The intaglio surfaces of the 0.0 mm offset twin blocks were scanned and superimposed onto their original computer-aided-design files. The resultant colour maps, root mean square (RMS) deviations, and percentage in-tolerance values at thresholds of 0.1 mm and 0.2 mm were assessed. The fit and retention of all twin blocks were assessed on their 3D printed models via a fit and retention score (FRS). ResultsThe median RMS deviation was 0.10 mm; percentage in-tolerance values at thresholds of 0.1 mm and 0.2 mm were 79.90%, and 94.51%. Printing deviations occurred most often at labial and incisal edges anteriorly, and buccal and occlusal surfaces posteriorly. There was no significant difference between the total FRS for the three groups (p = 0.076). However, the frequency of satisfactory scores for upper fit (p = 0.049), lower fit (p = 0.018), upper retention (p = 0.038) and lower retention (p = 0.015) differed significantly between the three groups. ConclusionThis study demonstrated the viability of a digital workflow to 3D print twin blocks. Print accuracy was satisfactory, with 0.1 mm offset providing the best fit and retention.

The effects of orthodontic treatment type, depression, and treatment need on perceived pain intensity

Objectives: The objectives of this study were to evaluate how orthodontic treatment type, treatment need, and depression affect perceived pain intensity (PPI). Material and Methods: This prospective study included 172 patients (80 girls and 92 boys, mean age 14.32 ± 1.57 years) treated at the Sivas Cumhuriyet University Faculty of Dentistry, Department of Orthodontics. The patients were divided into three groups: the first group was treated with fixed orthodontic appliances, the second group was treated with twin blocks, and the third group was treated with rapid maxillary expansion and reverse headgear (RME/RH). Data were collected and classified with the Index of Orthodontic Treatment Need-Dental Health Component (DHC), Children’s Depression Scale, and Visual Analog Scale. PPI was recorded in the 1st week (T0), 2nd week (T1), the 1st month (T2), 2nd month (T3), 3rd month (T4), and the 6th month (T5). Results: PPI was higher in boys at T1 (P = 0.005) compared with girls. There was a significant difference of PPI between the treatment groups at T2 (P = 0.036), T3 (P = 0.012), T4 (P = 0.000), and T5 (P = 0.006). A statistically significant positive correlation was found between DHC and PPI at T3 (r = 0.182; P = 0.000), T4 (r = 0.161; P = 0.03), and T5 (r = 0.189; P = 0.000) time periods. There was no significant correlation between depression and PPI. Conclusion: Girls were more resistant to pain than boys. The type of treatment and the need for treatment both had an effect on PPI. Further studies are needed to investigate the effects of psychological states on PPI during orthodontic treatment.

Use of Clark Twin blocks in the treatment of Angle class II malocclusion

The purpose of the paper was to determine some practical features of the treatment of Angle class II malocclusion accompanied by mandibular retrognathia using Clark Twin blocks. The following objectives were set: 1. To determine the assessment of the clinical parameters of the face during the treatment of Angle class II Malocclusion with Clark Twin Blocks. 2. To study the degree of correct occlusal relation after the functional treatment of Angle class II malocclusion. 3. To assess changes of cephalometric indices in patients with mandibular retrognathia treated by this method. The study is based on the analysis and assessment of clinical and paraclinical parameters of 14 patients with Angle class II malocclusion, who were subject to orthodontic treatment using Clark Twin blocks. Patients` age ranged from 8 to 12 years. The following diagnostic methods were used: clinical examination, biometric model study (Pont, Korkhaus methods), and radiological examination (orthopantomography, teleradiography). Sagittal occlusal relation improved in all patients receiving treatment. Expansion contributed to an improved tortoposition of the front teeth in 10 patients and correct relation of the lateral teeth in the transverse plane in 3 patients. Asymmetric expansion was performed in 2 cases. In all patients in the study, the clinical parameters of the face, as well as the frontal and lateral occlusal relation in the three planes of space improved significantly. Assessment of the soft tissue parameters and dental relation in the lateral and frontal area can be observed in a clinical case.

Comparison of the treatment duration and effects of magnetic mandibular repositioning appliances and non-magnetic twin block in the treatment of growing patients with skeletal Class II malocclusion due to mandibular retrognathism – A systematic review

Over the past two decades, magnets have been used in orthodontics and dentofacial orthopedics and various attempts have been made to evaluate the biological implications of magnets and magnetic fields. This systematic review aims to provide a detailed comparison between magnetic mandibular repositioning appliances and non-magnetic twin blocks on mandibular growth modification. The objective was to evaluate the treatment duration and effects of magnetic mandibular repositioning appliances and non-magnetic twin block in growing children with skeletal Class II malocclusion due to mandibular retrognathism. Literature search of electronic databases and additional manual search was done till June 2021. Randomized controlled clinical trials (CCTs), non-randomized CCTs, case reports, case series, and retrospective clinical trials in which magnetic appliances and non-magnetic twin blocks were used for the correction of skeletal Class II malocclusion are included in the present review. Correction of skeletal Class II malocclusion was achieved in a shorter treatment duration with magnetic mandibular repositioning appliances. Similar dental and skeletal effects were observed with both the appliances; however, maxillary restraining effect and reduced mandibular incisor proclination was evident with magnetic mandibular repositioning appliances. Magnetic appliance is proven to be more effective in correction of skeletal Class II malocclusion with mandibular retrognathism and maxillary prognathism with proclined lower incisors. This systematic review was registered on Prospero with registration number CRD42020165297.

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.

Inclined bite plane: indications and application

Background: The prevalence of malocclusion in Indonesia is about 80% of the population and is a fairly common dental and oral health problem so that treatment of malocclusion from an early age is very important and needed. One of malocclusion treatment for preventing malocclusion is the use of removable orthodontic devices in the form of inclined bite plane. Con-clusion: Inclined bite plane can be made on the orthodontic plate of maxilla and mandible. In the maxilla inclined bite plane can function as a functional appliance in treatment of Class II malocclusion division 1, as a retention device after treatment using twin blocks and in the mandible serves to correct anterior crossbite.

Cold rolling behaviour of Cu with highly oriented nanotwins: the importance of local shear strain

To clarify the deformation mechanism of nanotwinned materials under a complex stress state and large strain level, the microstructure evolution of pure Cu samples with high density of preferentially oriented nanotwins cold rolled to a strain up to 65% was systematically characterized by means of electron backscatter diffraction and transmission electron microscopy in this study. Heterogeneous deformation behavior was observed in nanotwinned Cu at different rolling strains. At a rolling strain of 15%, uniform deformation carried by the interactions between dislocations and twin boundaries dominate. At the same time, a small amount of strain localization in the direction ±45° respective to the rolling direction takes place, carried by detwinning and shear bands. As the rolling strain increased to 50%, detwinning becomes a dominant deformation mechanism and produces a large amount of coarse twin/matrix lamellae. A unique laminated structure with high angle lamellar boundaries (larger than 50° misorientation angle) and an average lamellar thickness of about 150 nm evolves from the coarse twin/matrix lamellae. As the rolling strain is increased up to 65%, an extensive laminated structures embedded with a few preserved twin blocks are prevalently formed. It is found that the local shear strain plays a critical role in the microstructure evolution of the nanotwinned Cu under cold rolling. When the local shear strains are so small as to be negligible, uniform deformation is sustained by interactions of dislocation/twin boundaries and the nanoscale twins survive. As the local shear strain increases up to 1, detwinning prevails and results in coarse twin/matrix lamellae. When the local shear strain is larger than 1, formation of shear bands composed of dislocation cells, sub-grains and fragments of twin lamellae instead of the detwinning process takes place, finally evolving into a laminated structure.

Composite Resin Twin Blocks for Correction of Angle's Class II Malocclusion

Composite Resin Twin Blocks for Correction of Angle's Class II Malocclusion

Influence of microstructural features and deformation-induced martensite on hardening of stainless steel by cryogenic ultrasonic impact treatment

Ultrasonic impact treatment of stainless steel AISI 321 was carried out at room temperature (in the argon environment – argon-UIT) and at cryogenic temperature (in liquid nitrogen – cryo-UIT) in the constrained conditions with application of the same mechanical energy to the treated specimens. The time dependencies of the surface hardness HV after the cryo-UIT and argon-UIT processes were of sigmoidal and parabolic shapes, respectively. The microstructural evolution of the surface layers of the deformed specimens was studied by X-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM) and selective area electron diffraction (SAED) analyses. The volume fractions of the deformation-induced α′ (Vα′) and ε (Vε) martensites were estimated using XRD approach and by magnetic and density measurements. Compared to the room temperature UIT in the argon environment (argon-UIT), the liquid nitrogen UIT generates a higher density of the deformation twins and stacking faults. In addition, a higher Vα′ (~53%) and Vε (~3.5%) were observed after cryo-UIT in deeper surface layers (~200μm). The argon-UIT process leads to the formation of either rectangular twin blocks or dislocation cells, which size ranged 200–500nm. Conversely, after cryo-UIT (ē≈0.95), a nanoscale grain structure of heterogeneous nature (α′ and γ phases) was formed in the outmost surface layer simultaneously with the areas filled with networks of deformation twins and stacking faults. The minimum grain size of α′-martensite Dα′ and austenite Dγ was respectively 25 and 45nm, and twin thickness/spacing was of 60–120nm. Both types of the microstructure contribute to the material strength and result in higher hardness of the cryo-UIT processed specimens (~5–5.66GPa) compared to that of the argon-UIT processed ones (~4.3GPa). With the increase in Zener-Hollomon parameter lnZ, the grain/twin/spacing size is decreased while the Vα′ and surface microhardness HV are increased.

Class II malocclusion treatment using combined twin block and fixed orthodontic appliances: A case report

Dentofacial orthopedic treatment can significantly alter and improve facial appearance in addition to correcting irregularity of the teeth. Functional appliance therapy can be used successfully in Class II malocclusion, e.g., in a growing patient. Twin blocks are simple bite blocks that interlock at a 70° angle and correct the maxillomandibular relationship through functional mandibular displacement. The twin block appliance was developed by Clark in 1980s. They modify the occlusal inclined plane, guiding the mandible forward into correct occlusion. The use of these appliances is greatly dependent on 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 are demonstrated in this case report.

An evaluation of oral health-related quality of life in orthodontic patients treated with fixed and twin blocks appliances.

OBJECTIVE:To study the impact of orthodontic treatment on the quality of life in two patient groups, one treated with the twin block appliance and the other with fixed appliances.MATERIALS AND METHODS:Ninety-eight patients, aged between 10 and 16 years, were recruited in the fixed (20 males and 29 females) or functional (29 males and 20 females) treatment groups. The oral health-related quality of life (OHRQoL) was measured before treatment and followed up at the end of the treatment. The instrument used to measure OHRQoL was a modified self-administered short version of the English Oral Health Impact profile (OHIP-16[E]) questionnaire.RESULTS:OHRQoL worsened at the initial stages of the treatment. The overall score of OHRQoL reduced significantly at the end of the treatment in both groups. Both groups showed comparable improvements in OHRQoL as the treatment progressed (analysis of variance test P = 0.05).CONCLUSIONS:The OHRQoL patterns, during the treatment with fixed and twin block appliances, were very similar. This suggests that the functional appliance's impact on the QoL may be overestimates by clinicians. OHRQoL improved significantly with both fixed and functional appliances by the end of the treatment. The OHRQoL trends observed during the study can be communicated to patients and used to increase patients’ compliance since they are made aware of the whole treatment process.

An Evaluation of Oral Health-Related Quality Of Life in Orthodontic Patients Treated with Fixed and Twin Blocks Removable Appliances: Part 1

1. Abstract 1.1.Objective:The study evaluated the impact of orthodontic treatment on the quality of life in two patient groups with Class II Division 1 malocclusion. 1.2.Materials and methods:98 patients were assigned to Fixed or Twin-block appliance treatment groups. Patients’ treatment needs were categorized with IOTN. The OHRQoL was assessed by OHIP-14 during different periods of treatment. 1.3.Results:Both groups showed comparable improvements in OHRQoL as the treatment progressed (Anova test p=0.05). Similar results were observed when OHRQoL was analyzed at IOTN subgroup level (Bonferroni Test p<0.05). Conclusion:OHRQoL improved significantly with both Fixed and Functional appliances.

Multidisciplinary Approach for Correction of Obstructive Sleep Apnea

ABSTRACTObstructive sleep apnea (OSA) is the most common type of sleep apnea and is caused by complete or partial obstructions of the upper airway. In this study we are presenting a case report of 11-year-old male patient with enlarged adenoids and tonsils, convex profile, receded chin, lower lip trap, class II skeletal and dental relationship with increased overjet. Surgical removal of enlarged adenoids was done before commencement of twinblock therapy. After this, two-step advancement with expansion in both arches utilizing twin blocks was planned. Four months into the treatment, patient reported with history of facial trauma with avulsed maxillary left central incisor. Twin block was then modified with pontic as replacement for maxillary left central incisor. Sagittal correction resulting in class I molar relationship was achieved in next 6 months. Fixed appliance therapy was followed. The design of the appliance and the results achieved after the postfunctional therapy are presented in this case report.How to cite this articleMadhaswar AB, Ravindranath VK, Daga PN. Multidisciplinary Approach for Correction of Obstructive Sleep Apnea. J Contemp Dent 2016;6(3):189-193.

Skeletal Discrepancy Correction In Class II Div 1 Malocclusion Using Fixed Twin Blocks.

This case report describes the management of a male with a severe Class II skeletal discrepancy, Class II molar and canine relationship bilaterally, a large overjet and an impinging overbite . As the patient was in CVMI stage 4,it was planned to make use of remaining growth for correction of skeletal discrepancy and so the treatment was initiated with a fixed twin block. This promoted the growth of the mandible, restrained maxilla in anteroposterior direction which in combination with the fixed appliances for alignment and levelling of the dentition improved the convex soft tissue profile. Thus severe skeletal Class II discrepancy was successfully managed with the combination of functional correction along with comprehensive fixed mechanotherapy without any extraction resulting in acceptable soft tissue changes.

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.

Twin quintuplet surfaces in CVD diamond

Chemical vapor deposition (CVD) of diamond films and wafers is a well established and flexible technology in which deposition parameters control the deposition rate as well as diamond properties, quality and shape. This article deals with surface morphology and crystallography of wafers, with emphasis on twin blocks and twin quintuples. In the study described here we have determined surface facet crystallography of two diamond wafers groups, one that contains Σ3 twin blocks and the other that has a large population of twin quintuplets. The tool used for the study is a scanning electron microscope (SEM) and the technique to identify surface crystallography involves only accurate tilting and surface observation. A basic knowledge of the twin structure enables accurate determination of surface crystallography.

Maurice Berman Prize 2003

A crowded, high angle Class II case is presented and illustrated with stage clinical photographs. It was successfully treated with modified Twin Blocks and high pull headgear, extraction of all four first premolars, and upper and lower pre-adjusted edgewise appliances.