Activity of the masticatory muscles and occlusal contacts in young adults with and without orthodontic treatment.

Abstract

BackgroundSymmetry evaluation of the craniofacial complex generally involves models of mandibular movement and masticatory muscle activity, especially during the development of the craniofacial complex.The aim of this screening study was to detect differences in the asymmetry and activity indices and in the occlusal contact distribution in groups with and without orthodontic treatment, and between the sexes in the healthy population.Material and MethodThis screening study involved the participation of 149 Caucasian (F = 101, M = 48) 18-year-old volunteers, of whom 77 had received orthodontic treatment (Group I) and 72 had not (Group II). All participants underwent sEMG recording with an eight-channel electromyograph (Bio EMG III). A T-Scan III device was used to analyze the occlusal contact points.We measured the voltage of the right and left temporalis anterior (RTA, LTA) and of the right and left masseter muscles (RMM, LMM). On the basis of the Naeije study, we calculated the Asymmetry and Activity indices (AsI, AcI).ResultsNo significant differences were found in the asymmetry or activity indices, or in the occlusal contact distribution of young adult subjects with or without orthodontic treatment.There were two findings in the females. First (p = 0.04), a higher voltage (131.12 μV) was recorded in the right temporalis anterior muscle in female group, compared to 119.65 μV in the male group. Secondly (p = 0.002), the activity index showed a predominance of the temporalis anterior (AcI = 10.52). In the males, the activity index showed a predominance of the masseter muscles (AcI =−1.22).ConclusionsThe null hypothesis was supported, as we found that no significant differences were observed in occlusal contact, asymmetry, or activity indices between healthy young adults with or without orthodontic treatment. However, there do exist significant differences in the activity index between genders.

Electromyographic activity of the jaw muscles and mandibular kinematics in young adults with theoretically ideal dental occlusion: Reference values

“…Although the results reflect a balanced contribution of AT and MA muscles in both sexes, MA predominates over TA in men, whereas in women the opposite is true. Similar results have been found in other studies ( 9 , 10 , 15 ). Similar to other studies of normo-occlusive subjects ( 9 , 11 , 22 , 26 ), torque indices in our participants showed a certain degree of lateral jaw torque effect, generated by AT activity on one side and contralateral MA activity.…”

“…To the best of our knowledge, no single study in subjects with healthy normo-occlusion has used inclusion criteria covering all of these variables. To name some specific studies, Ferrario et al ( 9 ) examined 92 healthy young people, but used the soft criteria of absence of moderate or severe clinical mandibular disorders (no temporomandibular jointsounds, no tenderness on palpation of the temporomandibular joint or of the masticatory muscles, no painful limitation of mandibular movement), which could have allowed inclusion of patients with some clinical symptoms of mandibular disorders ( 10 ). De Felício et al ( 11 ) only analyzed 20 normal subjects, and recognized that “even in this normal group, TMD signs and symptoms were reported by a few subjects.” Even the recent study by Wieczorek and Loster ( 10 ) included Class I, II, and III patients in their control group of non-orthodontically treated participants.…”

Electromyographic Patterns of Masticatory Muscles in Relation to Active Myofascial Trigger Points of the Upper Trapezius and Temporomandibular Disorders

“…Based on the bioelectric data obtained, the following indices were calculated according to standardized protocols: MCV (maximum voluntary contraction) based on the formula [ 28 ]: MCV = [voluntary teeth clenching/voluntary teeth clenching on cotton rollers] × 100% POC (percentage overlapping coefficient) based on the formula [ 29 ]: POC = [(MM right + TA right )/(MM left + TA left )] × 100% AsI (asymmetry index) based on the formula [ 30 ] ASI = [(RMS right − RMS left )/(RMS right + RMS left )] × 100 AcI (activity index) based on the formula [ 30 ]: ACI = [(RMS masseter − RMS temporal )/(RMS masseter + RMS temporal )] × 100 TC (torque) based on the formula [ 31 ]: TC = [(TA right + MM left ) − (TA left + MM right )] × 100% …”

Novel Functional Indices of Masticatory Muscle Activity

“…Surface electromyography (sEMG) is widely applied in dentistry to analyze bioelectric masticatory muscle activity and is commonly practiced in both clinical and research fields [ 1 ]. In numerous studies, electromyographic assessment of masticatory muscle activity has been used in individuals with temporomandibular disorders (TMDs) [ 2 ], bruxism [ 3 ], tension-type headaches [ 4 ], Down syndrome [ 5 ], motor neuron diseases [ 6 ], and different occlusal features [ 7 ]; during orthodontic treatment [ 8 ]; and in healthy populations [ 9 ]. Moreover, the sEMG measurement is also used to assess the effectiveness of therapeutic methods within the stomatognathic system [ 10 , 11 , 12 , 13 , 14 ].…”