Influence of pre-orthodontic trainer treatment on the perioral and masticatory muscles in patients with Class II division 1 malocclusion

Electromyographic Assessment of Muscle Activity in Children Undergoing Orthodontic Treatment-A Systematic Review

Background: Surface electromyography (sEMG) can provide an objective and quantitative image of the functional state of neuromuscular balance in the stomatognathic system. The objective of this systematic review is to examine current scientific evidence regarding the effects of orthodontic treatment on muscle electromyographic (EMG) activity in children. Methods: The search strategy included the PubMed, PubMed Central, Web of Science, Scopus, and Embase databases. The inclusion criteria were studies assessing EMG muscle activity in children undergoing orthodontic treatment compared with untreated children. The Cochrane risk-of-bias tool (RoB2) and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of the studies. The quality of evidence assessment was performed using GRADE analysis. The PRISMA diagram visually represented the search strategy, as well as screening and inclusion process. Results: The search strategy identified 540 potential articles. Fourteen papers met the inclusion criteria. Six studies were judged at a low risk of bias. The certainty of evidence was rated as moderate to low, according to the GRADE criteria. Studies showed alterations in EMG muscle activity in children undergoing orthodontic treatment. Conclusions: Orthodontic treatment appears to affect muscle activity in children undergoing orthodontic treatment. However, the quality of evidence is low and, therefore, it is not possible to definitively state this effect. Further long-term studies are needed to confirm the findings of this review. Study protocol number in PROSPERO database: CRD42023491005.

Electromyography: Processing, Muscles' Electric Signal Analysis, and Use in Myofunctional Orthodontics

Electromyography, commonly known as EMG, utilizes superficial or needle electrodes to record and analyze the fundamental electrical characteristics of skeletal muscles, determining whether the muscles are contracting. The motor unit, which consists of a collection of group muscle fibers and the motor neurons that govern them, is the structural basis of EMG. Three types of electrode are used in EMG which are needle electrode, fine wire electrode, and surface electrode. A significant amount of literature indicates that the correction of muscle function affects the relationships between teeth within the same jaw and between the jaws on opposing sides. The mechanism of action in myofunctional appliance therapy is linked to neuromuscular and skeletal adaptations resulting from altered function in the orofacial region. Both myofunctional therapy and orthodontics aim to address abnormal muscular behavior, restore abnormal muscle activity, and maintain proper alignment in various areas, including the lips, lower jaw, and tongue. This knowledge is essential for functions such as swallowing, speaking, chewing, and respiration as well as for minimizing incorrect movements and positioning. This article aims to describe the application of surface EMG as a diagnosis tool for assessing muscle activities in various orthodontic disorders, such as class II malocclusion open bite, crossbite, maxillary constriction, cleft lip and palate (CLP), and temporomandibular dysfunction, in patients. The electrodes used in EMG can be utilized to detect bioelectric activity in the muscles of the jaws and abnormalities in jaw movement. Analyzing EMG data is vital for obtaining a comprehensive understanding of the masticatory muscle system.

Effect of pre-orthodontic trainer treatment on the masticatory and perioral muscles in patients with class II subdivision 1 malocclusion evaluated by surface EMG

INTRODUCTION

Myofunctional appliances have been shown to have a positive effect on the muscles in the facial area. Surface electromyography (sEMG) is one of the reliable methods used to investigate these effects.

Effects of orthodontic treatment on masticatory muscles activity: a meta-analysis

Context: A comprehensive meta-analysis was carried out to investigate the impact of orthodontics on masticatory muscles.Methods: A thorough search of various databases, including CNKI, Wan Fang, VIP, CBM, MEDLINE, PubMed, Cochrane Library, EMBASE, Web of Science, and Google Scholar, was performed to identify relevant studies on patients undergoing orthodontics or functional corrections. Six case-control studies were finally included in this analysis, which specifically examined the effect of orthodontic treatment on masticatory muscle function.Results: The results revealed that the mean masticatory muscle voltage in patients treated with orthodontics was found to be higher after treatment compared to before treatment [odds ratio (OR)=1.57, 95% confidence interval (CI) (0.57, 2.57), p = 0.002], which could potentially have an impact on masticatory muscle function, particularly in individuals with Class II Division 1 malocclusion.Conclusion: These findings contribute to our understanding of the effects of orthodontic interventions on masticatory muscles, further highlighting the importance of orthodontics in optimising masticatory function.

Relationship between EMG features and force in orbicularis oris muscle

BACKGROUND

Lip incompetence resulting from mouth breathing is a common clinical manifestation, while there are no definite indicators of amplitude and intensity of muscle functional training in clinical practice, which leads to unsatisfactory training results.

OBJECTIVE

The aim was to quantify the relationship between electromyography (EMG) and force in orbicularis oris muscle, so that the indicators of muscle functional training can be evaluated using EMG signals, so as to improve the training effects.

METHODS

The EMG and the force signals of orbicularis oris muscle from 0% to 100% MVC within 5 s in twelve healthy subjects (six males and six females; age, 25 ± 2 years; mass, 60 ± 15 kg) were recorded simultaneously for three trials. Four EMG features consisting of RMS, WAMP, SampEn and FuzzyEn were analyzed. The regression analyses were performed using first-order and third-order polynomial model.

RESULTS

There were high correlations between the four EMG features and muscle force with the two models. The third-order model yielded a higher coefficient of determination (R2) than the linear model (p< 0.001) and the result of FuzzyEn (R2: 0.884 ± 0.059) was the highest in the four features.

CONCLUSION

The third-order model with FuzzyEn of EMG signals may be used to guide the muscle functional training.

A non-randomized concurrent controlled trial of myofunctional treatment in the mixed dentition children with functional mouth breathing assessed by cephalometric radiographs and study models

OBJECTIVES

This study aimed to examine the clinical effects of myofunctional treatment on children with functional mouth breathing by cephalometric radiographs and study models.

METHODS

A total of 224 children (6-10 years old; 114 males and 110 females; SNA°: 82.24 ± 1.67°; ANB°: 2.79 ± 0.80°, 28° < SN-GoGn° < 37°) formed three groups: MB-M group (mouth breathers with myofunctional treatment,n = 75); MB-N group (mouth breathers with no treatment,n = 70); NB group (nasal breathers with no treatment, n = 79). A blind evaluation of cephalometric radiographs and study models was conducted at T1(pre-study) and T2 (post-study), respectively.

RESULTS

Two hundred four children (MB-M:66, MB-N:68, NB:70) completed the present study. At T1, MB-M and MB-N groups, compared to their NB counterpart, had greater anterior lower facial height(P < 0.01) and overjet(P < 0.001) but shorter overbite and maxillary canines width (P < 0.001). At T2, the MB-N group exhibited a higher ANB angle, anterior lower facial height, and overjet, but shorter overbite and maxillary canines width (P < 0.001). From T1 to T2, the anterior lower facial height increased, overbite and the maxillary canines width further decreased in the MB-N group (P < 0.001). However, in the MB-M group, the incisors were retracted, overbite increased (P < 0.001), anterior lower facial height increased insignificantly (P > 0.05), and maxillary canines width increased slightly (P < 0.05). In the NB and MB-M groups, the mandible showed a normal tendency to grow forward, whereas, in the MB-N group, the mandible showed a tendency to grow downward (P < 0.001).

CONCLUSIONS

Mouth breathers demonstrated increased anterior facial height and overjet but reduced overbite and maxillary arch width, which improved significantly following myofunctional treatment.

TRIAL REGISTRATION

TCTR: TCTR20220401001 . Registered 1stApril 2022-Retrospectively registered.

Effects of an intraoral device (IOD) on electromyographic activity on the masseter and temporal muscles in Class III patients

OBJECTIVE

Class III malocclusion is characterized by a loss of vertical dimension associated with muscle imbalance. The present study was designed to determine electromyographic amplitude changes in temporal (T) and masseter (M) at rest and during clenching in Class III patients treated with an intraoral device (IOD) over a 24-hour period for 30 days with transcutaneous electrical nerve stimulation (TENS).

METHODS

Twelve patients with Class III (mean age 27.7 ± 1.2 years) were treated with TENS and IOD. Ten untreated patients composed the control group. Data were analyzed using Wilcoxon test and ANOVA.

RESULTS

Patients treated with TENS and IOD showed a marked decrease in hyperactivity of M and T at rest (p = 0.001) and an increase during clenching (p = 0.001). The control group maintained similar activity in both positions.

CONCLUSION

This study confirms that using TENS and IOD in patients improves muscle activity of T and M.

A Comparative Evaluation of the Dentoskeletal Treatment Effects Using Twin Block Appliance and Myobrace System on Class II Division I Malocclusion

The study aimed to evaluate the dentoskeletal effects of twin block appliance and myobrace system in treating skeletal Class II Division I malocclusions in growing children taking into account the effects of normal growth in an untreated control group. Twenty subjects with Class II Division I malocclusion considered as study group were allocated randomly to two treatment groups of 10 each, consecutively treated with twin block appliances (mean age 10.850 ± 1.37 years) and myobrace system (mean age 10.40 ± 1.89 years). Ten children (mean age 10.60 ± 1.77 years) with untreated Class II Division I malocclusion were considered as a control group to eliminate possible growth effects. At the start of the treatment and end of the observation period of 18–24 months, lateral cephalograms were taken. All the angular and linear parameters measured were subjected to statistical analysis. Twin block group subjects produced more measurable and statistically significant skeletal and dentoalveolar changes at the end of the observation period, demonstrated by correction of full cuspal Class II molar relationship to Class I molar relationship and yielding mandibular growth in increments greater in magnitude than the myobrace system. Meanwhile, the myobrace system-induced favorable dentoalveolar changes by a significant reduction of overjet. The retrognathic profile, however, improved in both the intervention groups as the upper lip protrusion, mentalis strain, and the lower lip curl were eliminated in striking contrast to the untreated control group. The study demonstrates that with appropriate patient selection both myobrace system and twin block appliances can be used in conjunction with the fixed appliance therapy to achieve more stable Class II corrections.

How to cite this article: Johnson JS, Satyaprasad S, Sharath Chandra H, et al. A Comparative Evaluation of the Dentoskeletal Treatment Effects Using Twin Block Appliance and Myobrace System on Class II Division I Malocclusion. Int J Clin Pediatr Dent 2021;14(S-1):S10–S17.

Unilateral Scissor Bite Managed with Prefabricated Functional Appliances in Primary Dentition—A New Interceptive Orthodontic Protocol

A unilateral scissor bite is a type of severe malocclusion in primary dentition that can influence the development of the mandible and face. The present case report describes an interceptive treatment on a 4-year-old girl with a unilateral scissor bite combined with an anterior crossbite, increased reverse overjet, and overbite on a skeletal Class III base. The patient was treated with a new Prefabricated Functional Appliance (PFA) which was modified from a Frankel-III appliance to induce a mandible to move backwards and relieve an occlusion discrepancy of the dental arch, and a functional dental rehabilitation with resin and myofunctional exercises with a PFA which was modified from an oral screen appliance were performed during the treatment. The total treatment time was 11 months and a satisfactory improvement of occlusion and facial esthetics was achieved. This case report presents a new PFA system and treatment protocol in primary dentition which results in a favorable outcome, and the clinical effectiveness of this appliance system warrants further investigation.

Skeletal class II malocclusion caused by mouth breathing in a pediatric patient undergoing treatment by interceptive guidance of occlusion

A 7-year 10-month-old boy was evaluated for mouth breathing and snoring habits. Examination revealed soft convex tissues, maxillary protrusion, mandibular retrusion, and a class II sagittal osteofascial pattern. The patient failed a water holding test. He was clinically diagnosed with skeletal class II malocclusion caused by mouth breathing. Under interceptive guidance of occlusion (iGo), the malocclusion improved with fixed maxillary expansion using functional appliances and interventional treatment of mouth breathing by lip closure exercises. These treatments enabled the patient to gradually return to nasal breathing and guided him to develop physiological occlusion for a coordinated jaw-to-jaw relation. At the 5-year 2-month post-correction follow-up visit (at the age of 13 years), the patient had stable occlusion, a coordinated osteofascial pattern, and normal dentition, periodontium, and temporomandibular joints.

Myofunctional Trainer versus Twin Block in Developing Class II Division I Malocclusion: A Randomized Comparative Clinical Trial

This study aimed to evaluate and compare the dentoalveolar effects of the myofunctional trainer T4K^TM versus twin block in children with class II division I malocclusion. Two parallel arm randomized comparative clinical trial was conducted, including twenty healthy children, 9–12 years old, showing Angle’s class II division I malocclusion due to mandibular retrusion. Children were randomly assigned into two groups according to the appliance used; Group 1: T4k, and Group II: twin block. Follow-up was done every 4 weeks for 9 months. Postoperative cephalometric X ray, study casts and photographs were taken for measurements and comparison. T4K showed a statistically significant reduction in the overjet (−2.50 ± 1.00 mm) (p < 0.0001), and a significant increase in the lower arch perimeter (LAP) (1.19 ± 0.96 mm) (p = 0.01). The twin block showed a statistically significant reduction in the overjet (−3.75 ± 1.10 mm) (p < 0.0001), a significant reduction in the overbite (−16.22 ± 17.02 %) (p = 0.03), and a significant increase in the LAP (1.69 ± 0.70 mm) (p < 0.0001). The overjet showed a higher significant decrease in the twin block group than in T4K (p = 0.03). The mean values of the overbite were significantly decreased in twin block than in T4k (p < 0.0001). Both groups showed significant dentoalveolar improvements toward class I occlusion; however, the twin block showed significantly better results than T4K appliance.

[The contribution of orofacial myofunctional reeducation to the treatment of obstructive sleep apnoea syndrome (OSA): a systematic review of the literature]

Obstructive sleep apnoea syndrome (OSA) is a widespread and under-diagnosed condition, making it a major public health and safety problem. Orofacial myofunctional reeducation (OMR) has been shown to be effective in the multidisciplinary treatment of OSA in children, adolescents and adults and is prescribed at several stages of OSA management. The main objective of this systematic literature review was to evaluate the effectiveness of active or passive orofacial myofunctional reeducation (OMR) in the treatment of obstructive sleep apnoea syndrome in children, adolescents and adults. The systematic literature review was undertaken from the three electronic databases: Medline (via PubMed), Cochrane Library, Web of Science Core Collection, and supplemented by a limited grey literature search (Google Scholar) in order to identify the studies evaluating the effectiveness of the OMR on OSA. The primary outcome of interest was a decrease in the Apnea-Hypopnea Index (AHI) of at least five episodes per hour compared to the baseline state. Secondary outcomes were an improvement in subjective sleep quality, sleep quality measured by night polysomnography and subjectively measured quality of life. Only ten studies met all the inclusion criteria. Eight were randomized controlled clinical trials, one was a prospective cohort study and another was a retrospective cohort study. Six studies were devoted to adult OSA and four to pediatric OSA. All included studies were assessed as "low risk of bias" based on the 12 bias risk criteria of the Cochrane Back Review Group. Based on the available evidence, RMO allows a significant reduction in AHI, up to 90.6% in children and up to 92.06% in adults. It significantly reduces the intensity and frequency of snoring, helps reduce daytime sleepiness, limits the recurrence of OSA symptoms after adenoamygdalectomy in children and improves adherence to PPC therapy. Passive RMO, with the assistance provided to the patient by wearing a custom orthosis, increases adherence to reeducation, significantly improves snoring intensity, AHI and significantly increases the upper airway. Published data show that orofacial myofunctional rééducation is effective in the multidisciplinary treatment of OSA in children, adolescents and adults and should be widely prescribed at several stages of OSA management. Passive RMO, with the pearl mandibular advancement orthosis designed by Michèle Hervy-Auboiron, helps to compensate for the frequent non-compliance observed during active RMO treatments.

Treatment of a Class II Division 1 malocclusion with the combination of a myofunctional trainer and fixed appliances

This case report describes the combined use of a myofunctional Trainer for Braces and fixed appliances to treat a 10-year-old girl with a Class II Division 1 malocclusion that featured severe maxillary incisor protrusion, a large overjet, and a V-shaped maxillary arch. She had a convex profile with an underdeveloped mandible. The superiority of myofunctional training in the case was to eliminate mouth breathing and lip sucking habits, train the oral musculature, stimulate mandibular growth, and make braces work more efficiently. The posttreatment facial photographs show improvement in the facial profile. Proper occlusion and facial balance were created, which were quite stable as demonstrated by the patient's 4-year follow-up records.

Anterior Segmental Osteotomy Using Customized Spider-Plates Based on Computer-aided Surgery System

Anterior segmental osteotomy (ASO) is considered the treatment modality of choice in patients with the bimaxillary dentoalveolar protrusion. However, this meticulous surgical technique accompanies a number of possible disadvantages. The considerable time required before, during, and after the operation, limited movement of the segment, damage of the mental nerve, loss of tooth vitality, loss of a tooth or teeth, or indeed total loss of the anterior segments are those that affect the result of the surgery. Recently, the authors have devised a computer-aided surgical simulation programme and fabricated the customized osteotomy guides and the spider-shaped plates based on the programme. They were then applied to a 28-year-old patient with the complaint of a bimaxillary dentoalveolar protrusion. This approach helped to overcome several problems related to ASO reported earlier.

Changes in facial expressions following functional orthopaedic treatment for Class II division 1 malocclusion: a prospective controlled study

OBJECTIVE

The aim of this study was to quantify changes in facial expressions in children with Class II division 1 malocclusion treated with functional appliances.

MATERIALS AND METHODS

A prospective controlled study was carried out evaluating 20 children with Class II division 1 malocclusion (ages 9-13) treated with a functional appliance for 12 months (treatment group). Age- and gender-matched children without immediate orthodontic treatment need were followed up without treatment for 12 months (control group). A frame-mode video sequence was taken of each subject at the beginning and end of the 12-month study period, during which 5 distinct facial expressions (posed smile, spontaneous smile, aggressive smile, lip pucker, and maximal mouth opening) were recorded. Frames at which each facial expression was at its peak were analysed. Changes in horizontal and vertical facial anthropometric distances brought about by performing each facial expression were measured. Intragroup differences following treatment were assessed using paired t-tests, whereas intergroup differences were assessed using unpaired t-tests.

RESULTS

All treated children showed an improvement in dentoalveolar relationships. Initial facial expressions differed between groups, with the treatment group showing less marked changes during lip pucker and more marked changes during maximal mouth opening. In contrast, no statistically significant differences were found between groups for the final facial expressions.

CONCLUSIONS

This study suggests that functional appliance use in growing children with Class II division 1 malocclusion tends to normalize soft-tissue movements during facial expressions.

Efficacy of a Pre-Fabricated Myofunctional Appliance for the Treatment of Mild to Moderate Pediatric Obstructive Sleep Apnea: A Preliminary Report

OBJECTIVE

The purpose of this study was to determine the efficacy of the Myobrace/MyOSA myofunctional appliance for the treatment of mild to moderate Obstructive Sleep Apnea (OSA) in children, by means of the Apnea/Hypopnea Index (AHI).

STUDY DESIGN

Nine children with a diagnosis of mild to moderate OSA were included in the study. The subjects wore the Myobrace/MyOSA myofunctional appliance for a period of 90 days. The initial AHI, determined by means of a sleep test, was used as baseline (To), and a second AHI, computed at the end of the experimental period, was used as final data (T₁). The differences between the AHIs at To and T₁ were calculated (diff AHI) and used for statistical purposes. The level of Oxygen Saturation (SaO₂) was also recorded before and after treatment, and their differences calculated as diff SaO₂. Statistical analysis was performed with a paired-t- test and statistical significance was established at 95 per cent level of confidence.

RESULTS

A statistical significant reduction in the AHI of the studied subjects was computed at the end of the experimental period (p = 0.0425). Although there was an improvement in the SaO₂, it did not reach a statistically significant difference.

CONCLUSIONS

The present results suggest that the Myobrace/MyOSA myofunctional appliance can be an alternative to treat mild to moderate OSA in children. However further studies are necessary to determine the stability of the results after treatment.

[Morphological and functional peri-oral changes during early treatment of Class II division 1 malocclusions using EF Line ® functional education devices]

INTRODUCTION

The aim of this article was to assess the impact of a flexible functional education splint for interceptive treatment of Class II division 1 dysmorphoses.

MATERIALS AND METHODS

An observational, prospective, multi-center non-comparative EGIDYS study was conducted in 81 children with a Class II division 1 malocclusion presenting one or several functional disorders. Patients wore a flexible splint in the EF Line^® range for a minimum of two hours per day and all night over 12 months in combination with educational exercises depending on the case. Patients were followed at one month, four months and twelve months of treatment. Ventilation, lingual position, labial peri-oral muscle tension, arch forms and dentoskeletal cephalometric measurements were assessed at initiation and completion of the functional education.

RESULTS

Functional examination on inclusion showed that the majority of children displayed a low tongue position at rest, oral or mixed ventilation, abnormal labial and peri-oral muscle tone and, in many cases, a narrow maxilla. Initial cephalometric examination recorded the following parameters: overjet, deep bite, and inclination of the lower incisors relative to the A-Pog line, and the SNA, SNB and ANB angles. After twelve months of functional education with a flexible EF Line^® splint, improvement was observed in the orofacial functions as shown by correction of the tongue position at rest as well as the lingual index indicating the position of the tongue against the palate, reduced tension of both the lower lip and the buccinator muscles at rest and in function, increased nasal breathing ability and a more rounded maxillary arch form. In addition, a major reduction in overjet and deep bite were visible as well as a significant reduction of the ANB angle due to its increased SNB component. This first stage in the orthodontic treatment plan resulted in a 73% improvement of Class II division 1 malformations. Correction of the malocclusion and functional disorders correlates significantly with compliant wearing of the EF Line^® splints.

CONCLUSIONS

This study demonstrates that the design of EF Line^® flexible functional education devices effectively corrects functional disorders linked to poor tongue position and triggers positive dentoskeletal changes, as compared with no treatment. From the clinical viewpoint, flexible EF Line^® splints can contribute to orthopedic and orthodontic treatment of Class II division 1 malformations.

Pre-Fabricated Myofunctional Appliance for the Treatment of Mild to Moderate Pediatric Obstructive Sleep Apnea: A Preliminary Report

OBJECTIVE

The purpose of this study was to determine the efficacy of the Myobrace/MyOSA myofunctional appliance for the treatment of mild to moderate Obstructive Sleep Apnea (OSA) in children, by means of the Apnea/Hypopnea Index (AHI).

STUDY DESIGN

Nine children with a diagnosis of mild to moderate OSA were included in the study. The subjects wore the Myobrace/MyOSA myofunctional appliance for a period of 90 days. The initial AHI, determined by means of a sleep test, was used as baseline (To), and a second AHI, computed at the end of the experimental period, was used as final data (T₁). The differences between the AHIs at To and T₁ were calculated (diff AHI) and used for statistical purposes. The level of Oxygen Saturation (SaO₂) was also recorded before and after treatment, and their differences calculated as diff SaO₂. Statistical analysis was performed with a paired-t- test and statistical significance was established at 95 per cent level of confidence.

RESULTS

A statistical significant reduction in the AHI of the studied subjects was computed at the end of the experimental period (p = 0.0425). Although there was an improvement in the SaO₂, it did not reach a statistically significant difference.

CONCLUSIONS

The present results suggest that the Myobrace/MyOSA myofunctional appliance can be an alternative to treat mild to moderate OSA in children. However further studies are necessary to determine the stability of the results after treatment.

Association between muscle activity and overjet in class II malocclusion with surface electromyography

OBJECTIVES

The aim of the study was to assess the association and correlation between the overjet and muscle activity (the masseter and temporalis muscles) in patient with Class II malocclusion in different genders using surface electromyography (sEMG).

MATERIALS AND METHODS

The overjet (measured clinically) and electromyographical activity (rest, chew, post chew rest, clench and post clench rest) of the masseter and temporalis muscle of class II malocclusion patient were assessed in 18 patients (3 males and 15 females) from the School of Dental Science, Hospital University Sains Malaysia.

RESULTS

The results were compared by simple linear regression test to evaluate the association between overjet and muscle activity in different genders. Class II malocclusion patients with increased overjet group showed significant association with masseter muscle activity on chewing stage (P = 0.005, F = 6.081 and adj-R2 = 0.473). Left temporalis muscle in class II malocclusion showed a significant linear association (P = 0.014, F = 0.812 and adj-R2= -0.034) with gender during clench.

CONCLUSION

In conclusion, class II malocclusion patient with increased overjet can affect masticatory muscle function and as well as clench force may differ in gender.

Impact of functional appliances on muscle activity: a surface electromyography study in children

Background

Electromyography (EMG) is the most objective tool for assessing changes in the electrical activity of the masticatory muscles.

The purpose of the study was to evaluate the tone of the masseter and anterior temporalis muscles in growing children before and after 6 months of treatment with functional removable orthodontic appliances.

Material/Methods

The sample conisted of 51 patients with a mean age 10.7 years with Class II malocclusion. EMG recordings were performed by using a DAB-Bluetooth instrument (Zebris Medical GmbH, Germany). Recordings were performed in mandibular rest position, during maximum voluntary contraction (MVC), and during maximum effort.

Results

The results of the study indicated that the electrical activity of the muscles in each of the clinical situations was the same in the group of girls and boys. The factor that determined the activity of the muscles was their type. In mandibular rest position and in MVC, the activity of the temporalis muscles was significantly higher that that of the masseter muscels. The maximum effort test indicated a higher fatigue in masseter than in temporalis muscles.

Conclusions

Surface electromyography is a useful tool for monitoring muscle activity. A 6-month period of functional therapy resulted in changes in the activity of the masticatory muscles.

Treatment of class II division 1 malocclusion with myofunctional trainer system in early mixed dentition period

Dentofacial growth interferences, caused by abnormal lip and tongue function in the mixed dentition period are a common clinical condition. The main purpose of the treatment in such cases is to eliminate oral dysfunction, establish muscular balance and correct or diminish maxillary incisor protrusion. The position of the teeth is determined by the lip and tongue pressure. Lip function may have been the cause of forcing teeth in to malposition they occupy. The case report is presented where the myofunctional trainer T4K is used during growth phase.