Pilot study for three-dimensional cephalometric Enlow's counterpart analysis: Vertical track. Two-dimensional and three-dimensional comparison.

BACKGROUND: The introduction of cone beam computed tomography (CBCT) in dentistry has given orthodontists the possibility of studying craniofacial structures in three dimensions. Despite the possibility to obtain lateral cephalograms synthesized from CBCT, this approach still does not provide a fully three-dimensional evaluation of the patient's anatomy. While there has been some success in adapting traditional two-dimensional cephalometric analyses to three dimensions, the specific application of Enlow's cephalometric analysis using CBCT remains unexplored. AIM: This pilot study aims to introduce a novel approach for performing Enlow's vertical track analysis using CBCT images. MATERIALS AND METHODS: Eighteen CBCT images of skeletal Class I (ANB = 2 ± 2) subjects (12 males and 6 females, aged from 9 to 19 years) with no history of previous orthodontic treatment were selected. For each subject, 2D Enlow's vertical track analysis was performed on lateral cephalograms extracted from the CBCT images, and separately, 3D vertical track analysis was directly performed on the CBCT images. To validate the proposed method, we compared the differences between the posterior vertical counterpart (PVC) and the middle vertical counterpart (MVC), as well as between the middle vertical counterpart (MVC) and the anterior vertical counterpart (AVC), as obtained from both the two-dimensional and three-dimensional analyses. The Kolmogorov-Smirnov normality test was applied for each variable to check whether data were normally distributed and a paired Student's t-test was performed. The level of statistical significance was .05. RESULTS: The comparison between three-dimensional PVC-MVC (-0.43 ± 0.37 cm) and two-dimensional PVC-MVC (-0.53 ± 0.36 cm) revealed no statistical difference (P = .27). Similarly, no significant difference (P = .28) was observed between two-dimensional MVC-AVC (-0.56 ± 0.34 cm) and three-dimensional MVC-AVC (-0.47 ± 0.37 cm). CONCLUSIONS: The method proposed by this study to realize the vertical track analysis on 3D images is valid and superimposable on that described by Enlow on lateral cephalograms.

Three-Dimensional Enlow's Counterpart Analysis: Neutral Track.

The aim of this study is to provide a novel method to perform Enlow's neutral track analysis on cone-beam computed tomography (CBCT) images. Eighteen CBCT images of skeletal Class I (ANB = 2° ± 2°) subjects (12 males and 6 females, aged from 9 to 19 years) with no history of previous orthodontic treatment were selected. For each subject, 2D Enlow's neutral track analysis was performed on lateral cephalograms extracted from CBCT images and 3D neutral track analysis was performed on CBCT images. A Student's t-test did not show any statistically significant difference between the 2D and 3D measurements and therefore the method proposed by this study to realize the neutral track analysis on 3D images is valid and superimposable on that described by Enlow on lateral cephalograms. Further studies with a large sample and different skeletal class subjects are needed to confirm the results of this research.

Sports performance adaptations through occlusal splint: Case reports of triathlon athletes.

OBJECTIVE: Occlusal disturbances affect human posture and sports performance. This study aimed to monitor biomechanical adaptations to personalized occlusal splints. METHODS: Splints were customized based on stabilometry, thermography, sEMG, and kinesiography, and administered to three triathlon athletes. They were evaluated during a 4-month period, using isokinetic indexes, running kinematics and anaerobic outputs. RESULTS: Individuality emerged as a key factor driving type, quantity, quality, and time trajectories of adaptations. The use of instrumental and clinical tests allowed the detection of static balance and biting function improvements, but not necessarily parallel to sports performance improvements. CONCLUSION: The authors argue that strength and kinematic imbalances are joint and task-specific and support the use of multi-stage monitoring of the biomechanical effect of mouthpieces. Kinematics of cycling and running may be widely assessed with ecological and inexpensive methods. Strength imbalances need to be continuously monitored due to the high informative value to injury prevention.

"3D Counterpart Analysis": A Novel Method for Enlow's Counterpart Analysis on CBCT.

The aim of this study was to propose a novel 3D Enlow's counterpart analysis traced on cone-beam computed tomography (CBCT) images. Eighteen CBCT images of skeletal Class I (ANB = 2° ± 2°) subjects (12 males and 6 females, aged from 9 to 19 years) with no history of previous orthodontic treatment were selected. For each subject, a 2D Enlow's counterpart analysis was performed on lateral cephalograms extracted from the CBCT images. The following structures were identified: mandibular ramus, middle cranial floor, maxillary skeletal arch, mandibular skeletal arch, maxillary dento-alveolar arch, mandibular dento-alveolar arch. The differences between each part and its relative counterpart obtained from the 2D analysis were than compared with those obtained from a 3D analysis traced on the CBCT images. A Student's t-test did not show any statistical significant difference between the 2D and 3D measurements. The landmarks proposed by this study identified the cranio-facial structures on the 3D images in a way that could be superimposed on those described by Enlow in his analysis performed on 2D lateral cephalograms.

Quantitative Measurement of Swallowing Performance Using Iowa Oral Performance Instrument: A Systematic Review and Meta-Analysis.

Swallowing is a complex but stereotyped motor activity aimed at serving two vital purposes: alimentary function and the protection of upper airways. Therefore, any impairment of the swallowing act can represent a significant clinical and personal problem that needs an accurate diagnosis by means of reliable and non-invasive techniques. Thus, a systematic review and meta-analysis was performed to investigate the reliability of the Iowa Oral Pressure Instrument (IOPI) in distinguishing healthy controls (HC) from patients affected by swallowing disorders or pathologies and conditions that imply dysphagia. A comprehensive search was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and using PubMed, Scopus, Web of Science, Cochrane, and Lilacs databases. Overall, 271 articles were identified and, after a three-step screening, 33 case-control and interventional studies reporting IOPI measurements were included. The methodological quality of the retrieved studies resulted in being at a low risk of bias. The meta-analysis on case-control studies showed that maximum tongue pressure (MIP) values were always higher in HC than in patients, with an overall effect of the MIP difference of 18.2 KPa (17.7-18.7 KPa CI). This result was also confirmed when the sample was split into adults and children, although the MIP difference between HC and patients was greater in children than in adults (21.0 vs. 15.4 KPa in the MIP mean difference overall effect, respectively). Tongue endurance (TE) showed conflicting results among studies, with an overall effect among studies near zero (0.7 s, 0.2-1.1 s CI) and a slight tendency toward higher TE values in HC than in patients. Among the intervention studies, MIP values were higher after treatment than before, with a better outcome after the experimental tongue training exercise than traditional treatments (the MIP mean difference overall effect was 10.8 and 2.3 KPa, respectively). In conclusion, MIP values can be considered as a reliable measure of swallowing function in adults and in children, with a more marked MIP difference between HC and patients for the children population. MIP measures in patients are also able to detect the best outcome on the tongue function after the training exercise compared to traditional training.

Prevalence of Obstructive Sleep Apnea Syndrome: A Single-Center Retrospective Study.

Obstructive sleep apnea syndrome (OSAS) is a sleep breathing disorder that often remains undiagnosed and untreated. OSAS prevalence is increasing exponentially. Starting on the dentist's role as an epidemiological and diagnostic "sentinel", the purpose of this study was to assess the prevalence of OSAS. The clinical diaries of 4659 patients were reviewed through a single-center retrospective analytic study. Descriptive statistical analysis was performed. Only 0.26% of patients reported to suffer from sleep apnea and were then diagnosed with OSAS. It was found that, out of 4487 patients, 678 suffered from hypertension (14.80%), 188 from gastro-esophageal-reflux-disease (GERD = 4.10%) and 484 from gastritis (10.78%). These results could be related to a difficult diagnosis of OSAS and to the absence of a dedicated section on sleep disorders in medical records. Therefore, the introduction of a question dedicated to sleep disorders, the administration of questionnaires (such as the STOP-BANG questionnaire) for early diagnosis, a multidisciplinary approach and pneumological examination could support the dentist in identifying patients at risk of OSAS.

Effects of Induced Malocclusion on Vertebral Alignment in Rats: A Controlled Study by CBCTs.

This study aimed to evaluate with CBCTs the alteration of vertebral alignment over time of induced malocclusion in rats. Crown pads increasing the vertical dimension of 0.5 mm were applied on the upper molars at one randomly selected side of the maxilla in rats (premature contact side) while the opposite side was left untreated (control side). Four groups were organized, ten animals each. In groups A, B, and C, the crowns were applied at time 0 (t-0). In group A, the crowns were removed after 2 weeks (t-2w) and euthanized after two more weeks, while in groups B and C, the animals were euthanized after 2 and 4 weeks (t-4w), respectively. No premature contacts were applied in group D. CBCTs were taken at t-0 in all animals before applying the crowns, at t-2w in group A before removing the crowns, and in all groups before the euthanasia. The changes in the iliac crest angle (ICA) that formed between the superior external margin of the iliac crest and the vertebral spine were evaluated. In groups A and B, after 2 weeks, the changes in ICA were statistically significant at p = 0.028 and p = 0.042, respectively. In group C, and in the control group D, the changes of ICA were not statistically significant (p = 0.058 and p = 0.414, respectively). In conclusion, the incease in monolateral occlusion in the molar region yielded a rotation of the lumbo-sacral segment towards the same side of the occlusal bite-raising.

Evaluation of Articular Eminence Inclination in Normo-Divergent Subjects with Different Skeletal Classes through CBCT.

(1) We aimed to compare articular eminence inclination (AEI) in normo-divergent subjects (SN^GoGn = 32° ± 5°), with different anteroposterior sagittal skeletal classes through a cone beam computed generated tomography (CBCT). (2) In this cross-sectional study, CBCT records were retrospectively analysed. From the original sample of 52 CBCT records, 33 records of normo-divergent adult subjects were selected (11 Class I, 13 Class II and 9 Class III). On mid-sagittal section of the Temporomandibular Joint (TMJ) on both sides, AEI was calculated by graphic method. (3) The Kruskal-Wallis test was used to evaluate any difference between AEI on both left and right sides in the three groups. No statistically significant difference was observed on either the right side (p = 0.174) or the left side (p = 0.624). (4) Articular eminence inclination seems to be not related with skeletal class. Given the lack of significance in the observed differences between AEI and skeletal classes, we believe that future studies should focus on assessing possible relationships between AEI and different vertical skeletal patterns.

Obstructive Sleep Apnea and Periodontal Disease: A Systematic Review.

Background and Objectives: The objective of this study was to evaluate the association between periodontal disease and obstructive sleep apnea syndrome (OSAS). Materials and Methods: Electronic search using PubMed, Scopus, LILACS, and Cochrane library was carried out for randomized controlled trials, cohort, case-control, longitudinal and epidemiological studies on humans published from January 2009 until September 2020. The participants had to be male and female adults who were diagnosed with OSAS either by overnight polysomnography (carried out at a sleep laboratory or at home) or by a home sleep testing monitor (Apnea Risk Evaluation System). Methodological quality assessment was carried out using the Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies while an adapted form of NOS was used for cross-sectional studies. Results: Ten studies fulfilled the inclusion criteria of our review, 5 were case-control studies, and 5 cross-sectional. Sample size ranged from 50 to 29,284 subjects, for a total of 43,122 subjects, 56% of them were male, their age ranged from 18 to 85 years old. The heterogeneity among the studies regarding the classification of periodontal disease, and the different methods for OSAS severity assessment, complicated the comparison among the studies. Conclusions: There is low evidence of a possible association between OSAS and periodontitis. The pathophysiological mechanism, cause-effect, or dose-response relationship are still unclear. Further studies are needed and should use a precise classification of OSAS subjects, while the new classification of periodontitis from the World Workshop of Chicago 2017 should be used for the periodontal assessment.

Early Orthodontic Treatments of Unilateral Posterior Crossbite: A Systematic Review.

We aimed to report an update of the systematic review by Petrén et al. (2003). The objective was to evaluate how orthodontic treatments can affect unilateral posterior crossbite (UPXB) in primary and early mixed dentition. Several databases were consulted, and articles published between January 2002 and March 2020 were selected. This review examines the following studies: randomized clinical trials, prospective and retrospective studies with concurrent untreated or normal control groups, and clinical trials comparing at least two treatment strategies. Among the 1581 articles retrieved from the searches, 11 studies were included. Quad-helix (QH) and expansion plate (EP) appliances were compared in three studies. One study compared rapid maxillary expansion (RME) treatment anchored on primary dentition otherwise on permanent molars. One study compared RME and a modified RME with arms extended until deciduous canine and EP. Four studies evaluated the effects of expansion appliances compared with a control group. Compared with the previous review, the quality of the included studies is higher. However, heterogeneity of treatments, different strategies in measurements, lack of a similar follow-up length, and absence of a cost-effectiveness analysis preclude the possibility of providing reliable scientific evidence on the most effective UPXB treatment in primary and early mixed dentition.

Evaluation of Knowledge among Dentists on Symptoms and Treatments of Temporomandibular Disorders in Italy.

To determine the knowledge of general dentists and dental specialists on temporomandibular disorders (TMD) in Italy, a web-based questionnaire including 20 multiple- choice questions was sent to all general dental practitioners and specialists in Italy. Mean score of diagnosis and treatment knowledge of all participants was 23.8 ± 7.3 out of 40 achievable scores. There was a significant difference between the knowledge of dentists and the variables of sex, age, and years of experience (p < 0.05). However, overall, it is not possible to state a significant difference between the final score of dentists with different specializations (p = 0.89). The results of this study showed an acceptable knowledge of participants regarding TMD.

A Novel Role of Ascorbic Acid in Anti-Inflammatory Pathway and ROS Generation in HEMA Treated Dental Pulp Stem Cells.

Resin (co)monomers issued from restorative dental materials are able to distribute in the dental pulp or the gingiva, to get to the saliva and to the flowing blood. Many authors have recently shown that methacrylate-based resins, in particular 2-hydroxyethylmethacrylate (HEMA), are responsible of inflammatory and autophagic processes in human dental pulp stem cells (hDPSCs) while ascorbic acid (AS), an antioxidant molecule, can assume a protective role in cell homeostasis. The purpose of the current work was to study if 50 µg/mL AS can affect the inflammatory status induced by 2 mM HEMA in hDPSCs, a tissue-specific cell population. Cell proliferation, cytokine release, morphological arrangement and reactive oxygen species (ROS) formation were determined respectively by MTT, ELISA, morphological analysis and dichlorofluorescein assay. The hDPSCs exposed to HEMA let to an increment of ROS formation and in the expression of high levels of inflammatory mediators such as nuclear factor-κB (NFkB), inflammatory cytokines such as interleukin IL6, IL8, interferon (IFN)É£ and monocyte chemoattractant protein (MCP)1. Moreover, HEMA induced the up-regulation of pospho-extracellular signal-regulated kinases (pERK)/ERK signaling pathway associated to the nuclear translocation. AS treatment significantly down-regulated the levels of pro-inflammatory mediators. Then, the natural product AS reduced the detrimental result promoted by methacrylates in clinical dentistry, in fact restore cell proliferation, reduce the pro-inflammatory cytokine, downregulate ROS production and of NFkB/pERK/ERK signaling path. In synthesis, AS, could improve the quality of dental care and play a strategic role as innovative endodontic compound easy to use and with reasonable cost.

Failure in evoking the trigeminal cardiac reflex by mandibular stretching in healthy volunteers.

Stimulation of trigeminal sensory afferences has been reported to evoke hypotension and bradycardia, a phenomenon known as the trigeminal cardiac reflex. We attempted to evoke such a reflex through cycles of alternate mandibular stretching in healthy volunteers, as previously reported, for its possible therapeutic exploitation. In Phase 1 of the study, 10 healthy volunteers [5 male, 5 female, age (mean ± SD) 27±2 years)] underwent 2 randomized sessions of automated monitoring, every 6 minutes, of systolic blood pressure (SBP), diastolic (D) BP, and heart rate (HR), with a one-week interval, either with mandibular stretching (12 minutes with a spring device fitted in the mouth), or nothing (control). Observation was prolonged for 180 minute after the end of the stretching. In Phase 2, 7 other volunteers (4 male and 3 female, age 24±1.3 years) repeated the protocol with a sampling interval of 2 minutes until the end of stretching. Baseline levels of SBP, DBP and HR were similar in the test and control sessions. There was a progressive fall of BP and HR as a function of time during the test session. With stretching: SBP changed from 119.2±10.1 to 118.1±10.1 to 115.8±10.5 mmHg, at baseline, end of stretching and 180 minutes after, respectively, p<0.001 at ANOVA for time effect). However, similar changes occurred in the control group: from 120.7±12.0 to 120.8±12.0 to 115.4±3.6 mmHg at the same times, P=0.822 for group effect). In Phase 2, again we observed no significant changes for any of the parameters investigated as a function of treatment. Despite attempts at maximum standardization of study condition and the use of operator-independent BP and HR measurements, we could not detect significant BP or HR effects of repeated mandibular stretching.

Effects of affective picture viewing on postural control in healthy male subjects.

Emotion theory holds that unpleasant events prime withdrawal actions, whereas pleasant events prime approach actions. Recent studies have suggested that passive viewing of emotion-eliciting images results in postural adjustments. The main objective of this research was to investigate the effects of emotional inputs on the postural control. Ten healthy young adults looked at a series of emotion-eliciting images while standing on a force plate. The images were taken from the International Affective Picture System (IAPS). The posture-stabilometric parameters were statistically analyzed (RM ANOVA on Ranks). The results showed that the emotional inputs might influence body balance.

Effects of viewing affective pictures on sEMG activity of masticatory and postural muscles.

Recently there has been an upsurge of interest in the question to what extent the human motor control system is influenced by the emotional state of the actor. The aim of this study was to evaluate whether emotional inputs modify the activity of masticatory and postural muscles. Twenty healthy young adults viewed affective pictures, while surface electromyography (sEMG) of masticatory and postural muscles was recorded to investigate the coupling between emotional reactions and body muscular activity. One hundred and twenty pictures, chosen from the International Affective Picture System (IAPS), divided in two blocks of six sets, were presented to the subjects. sEMG data were statistically analyzed (RM ANOVA on Ranks). Root Mean Square (RMS) amplitudes, comparing the subsequent sets (Neutral, Unpleasant, Neutral, Pleasant) with the first and the last Baseline set, changed significantly only randomly. The results show that emotional inputs seems not influence the activity of masticatory and postural muscles, recorded by sEMG.

Condylar volume and condylar area in class I, class II and class III young adult subjects.

AIM: Aim of this study was to compare the volume and the shape of mandibular condyles in a Caucasian young adult population, with different skeletal pattern. MATERIAL AND METHODS: 200 Caucasian patients (15-30 years old, 95 male and 105 females) were classified in three groups on the base of ANB angle: skeletal class I (65 patients), skeletal class II (70 patients) and skeletal class III (65 patients). Left and right TMJs of each subject were evaluated independently with CBCT (Iluma). TMJ evaluation included: condylar volume; condylar area; morphological index (MI). Condylar volumes were calculated by using the Mimics software. The condylar volume, the area and the morphological index (MI) were compared among the three groups, by using non-parametric tests. RESULTS: The Kruskal-Wallis test and the Mann Whitney test revealed that: no significant difference was observed in the whole sample between the right and the left condylar volume; subjects in skeletal class III showed a significantly higher condylar volume, respect to class I and class II subjects (p < 0.05); significantly lower condylar volume was observed in class II subjects, respect to class I and class III (p < 0.05). In the whole sample condylar volume (699.8 ± 63.07 mm3 in males and 663.5 ± 81.3 mm3 in females; p < 0.01) as well as condylar surface (423.24 ± 63.03 mm2 in males and 389.76 ± 61.15 mm2 in females; p < 0.01) were significantly higher in males than in females. CONCLUSION: Skeletal class appeared to be associated to the mandibular condylar volume and to the mandibular condylar area in the Caucasian orthodontic population.

Orbital volume and surface after Le Fort III advancement in syndromic craniosynostosis.

There are no quantitative standards for the volumetric measurements of the orbital cavity after Le Fort III advancement. Computed tomography (CT) scan images have given the opportunity to compare with accuracy the real anatomic changes and potentially the functional improvements that resulted after a surgical treatment.Three-dimensional CT scan images processed by DICOM files in Dolphin 3D Software were used to assess orbital volume and surface in 12 subjects affected by craniofacial syndromic malformations treated with Le Fort III advancement. The preoperative (T0) and postoperative (T1: 6 months after surgery) three-dimensional craniofacial CT scans of the subjects were collected and retrospectively analyzed. Image segmentation of the anatomic orbital cavity and the three-dimensional graphic rendering were done by using the Dolphin Imaging Plus 11.0 software.The orbital volume was increased after surgery, with statistical significance, from 22,267 to 22,706.3 mm(3) in the right eye and from 26,511 mm(3) to 26,256.4 mm(3) in the left eye. The surface of both bony orbits had an expansion, which is statistically significant. In conclusion, this study showed that the orbital advancement in white subjects after Le Fort III advancement was significant and produced a significant augmentation of the orbital volume and surface area with correction of the ocular bulb proptosis.

Relationship between facial morphology on lateral skull radiographs and sEMG activity of neck and trunk muscles in Caucasian adult females. A cross-sectional study.

OBJECTIVE: To evaluate whether there is an association between facial morphology on cephalometrics and surface electromyographic (sEMG) recordings of head, neck and trunk muscles. MATERIALS AND METHODS: 31 Caucasian adult females, average age 26 years (range 21-29) underwent lateral skull radiographs in natural head position (mirror position) and the sEMG recordings for the following muscles: masseter, anterior temporal, digastric, posterior cervicals, sternocleidomastoid, and upper and lower trapezius. All muscles were monitored in the mandibular rest position, and during maximal voluntary clenching (MVC). RESULTS: Spearman's correlation coefficient revealed significant correlations (P<0.01): (i) between the variables controlling mandibular position, and the inclination of the lower incisors, and the sEMG activity of the trapezius; (ii) between the sEMG activity of sternocleidomastoid and the variables indicating the height of the mandibular ramus; (iii) between the sEMG activity of anterior temporal and the incisive angle, the inclination of the upper incisors and the maxillary base length, and (iv) between the sEMG activity of cervical muscles and the anterior cranial base length. CONCLUSIONS: Some associations between cephalometric variables and sEMG of the neck and trunk muscles were observed. However, in view of the cross-sectional nature of the study and the limited sample, no conclusion was possible about the mechanism concerning these results. Future longitudinal studies are required to investigate the "mechanism at work".

Prevalence and type of pain during conventional and self-ligating orthodontic treatment.

This study investigated the prevalence and type of pain experienced during orthodontic treatment in 30 subjects (12 males, 18 females, aged 12-18 years) with crowding. Fifteen patients were treated with conventional brackets (Victory Series) and 15 with self-ligating brackets (Damon SL II). The first archwire for all patients was a 0.014 inch nickel-titanium (NiTi) archwire with a force of approximately 100 g. Conventional brackets were ligated with elastomeric modules. A visual analogue scale (VAS) was used daily to assess the intensity of pain; the use of pain medication was also reported in a specially designed daybook for a total period of 3 months. Pearson's chi-square was used to investigate the difference between groups in the frequency of pain experience, its nature, and the use of analgesia. Non-parametric statistics (Mann-Whitney U-test) were computed to compare pain intensity between the groups. To investigate reported pain assessments, Friedman's two-way analysis of variance was used and the differences were estimated using Wilcoxon's signed-rank test. The results showed that pain was reported for a period of 9 days after archwire insertion. Patients treated with self-ligating brackets reported the highest pain intensity on the day following placement of the first archwire (VAS mean = 42.6), while those treated with conventional brackets experienced the greatest pain intensity at placement of the first archwire (VAS mean = 52) and after the second orthodontic appointment (VAS mean = 59.6). Analgesics were used by 16.5 per cent of patients treated with self-ligating brackets and by 10 per cent of those treated with conventional brackets, most often during the first 2 days after archwire placement. Patients treated with conventional brackets reported significantly more 'constant' pain than those treated with self-ligating brackets who complained of 'chewing/biting' pain. Pain appears to be common during orthodontic treatment but perhaps less intense when self-ligating brackets are used, although no difference was observed in the use of analgesics between those treated with self-ligating or conventional brackets. There were no reports of pain after 7-9 days in either group.

Surface electromyographic patterns of masticatory, neck, and trunk muscles in temporomandibular joint dysfunction patients undergoing anterior repositioning splint therapy.

The aim of this study was to investigate the surface electromyographic (sEMG) activity of neck, trunk, and masticatory muscles in subjects with temporomandibular joint (TMJ) internal derangement treated with anterior mandibular repositioning splints. sEMG activities of the muscles in 34 adult subjects (22 females and 12 males; mean age 30.4 years) with TMJ internal derangement were compared with a control group of 34 untreated adults (20 females and 14 males; mean age 31.8 years). sEMG activities of seven muscles (anterior and posterior temporalis, masseter, posterior cervicals, sternocleidomastoid, and upper and lower trapezius) were studied bilaterally, with the mandible in the rest position and during maximal voluntary clenching (MVC), at the beginning of therapy (T0) and after 10 weeks of treatment (T1). Paired and Student's t-tests were undertaken to determine differences between the T0 and T1 data and in sEMG activity between the study and control groups. At T0, paired masseter, sternocleidomastoid, and cervical muscles, in addition to the left anterior temporal and right lower trapezius, showed significantly greater sEMG activity (P = 0.0001; P = 0.0001; for left cervical, P = 0.03; for right cervical, P = 0.0001; P = 0.006 and P = 0.007 muscles, respectively) compared with the control group. This decreased over the remaining study period, such that after treatment, sEMG activity revealed no statistically significant difference when compared with the control group. During MVC at T0, paired masseter and anterior and posterior temporalis muscles showed significantly lower sEMG activity (P = 0.03; P = 0.005 and P = 0.04, respectively) compared with the control group. In contrast, at T1 sEMG activity significantly increased (P = 0.02; P = 0.004 and P = 0.04, respectively), but no difference was observed in relation to the control group. Splint therapy in subjects with internal disk derangement seems to affect sEMG activity of the masticatory, neck, and trunk muscles.