Are the bite force and electromyographic activity altered in muscle TMD patients with abfraction lesions?

Objective: To verify if the maximal molar bite force (BF) and the electromyographic activity (EMG) are altered in TMD patients with abfraction lesions (AL) when compared to those without AL.

Methods: The sample was composed of 45 patients (18–60 years old), 30 diagnosed with TMD (RDC/TMD) (15 with AL and 15 without AL) and 15 controls. The BF and the EMG of the masticatory muscles (maximal voluntary contraction (MVC) and chewing gum) were measured.

Results: TMD patients showed decreased BF (p < 0.001), without differences between patients with and without AL. The electromyographic activity during MVC was similar among all groups (p > 0.05), although there was a greater trend of muscular balance for the control group (percentage overlapping coefficient and electromyographic indexes). The TMD group without AL showed a lower number of cycles and masticatory frequency.

Discussion: TMD patients with and without AL exhibited similar results in the analysis of the BF and EMG, without differences.     

Temporomandibular clinical exploration in Italian adolescents

Objective: This study investigated the prevalence of the signs and symptoms of temporomandibular disorders (TMD) among Italian adolescents.

Methods: The data were recorded from 567 subjects (246 males and 321 females; age range 11–19 years), grouped according to age and molar class relationship.

Results: Forty-four point one percent of subjects showed at least one sign or symptom of TMD, which were significantly more frequent in the 16–19 year-old group (52.9%) in respect to the 11–15 year-old group (39.8%) (χ ² = 8.78; p = 0.003). Signs and/or symptoms were about 1.6 times more frequent in subjects with Class II/1 malocclusion (χ ² = 13.3, p = 0.0003), mostly for TMJ sounds (χ ² = 1.444; p = 0.036). Myalgia was more frequent in females than in males (χ ² = 3.882; p = 0.049).

Conclusion: TMD signs and/or symptoms among Italian adolescents seem diffused (44.1%). Therefore, all adolescents should be screened thorough medical history and clinical examination.     

Management of pain in TMD patients: Bio-oxidative ozone therapy versus occlusal splints

Objective: To compare the effects of bio-oxidative ozone application with occlusal splints in temporomandibular disorder (TMD) patients with pain.

Methods: Forty participants were selected after the diagnosis of TMD and randomly divided into two groups: ozone group (OG, n = 20) and occlusal splint group (OCSG, n = 20). Ozone was applied to patients three times per week, for a total of six sessions. Patients in the OCSG were instructed to use occlusal splints every night over a period of four weeks.

Results: Mandibular movements showed significant differences for the time factor in OG and OCSG. Pressure pain thresholds of the temporal and masseter muscles at follow-up were significantly higher in the OCSG group. Both treatments statistically decreased the visual analog scale (VAS) scores. However, no statistically significant difference was observed between groups after the application of treatments.

Discussion: Occlusal splint treatment is still the gold treatment modality for objective pain relief in patients with TMD pain.     

Evaluation of ultrasonography guidance for single-puncture temporomandibular joint arthrocentesis: A randomized clinical study

Objective To evaluate ultrasonography (US) guidance on the single-puncture temporomandibular joint (TMJ) arthrocentesis technique.

Methods Twenty-four patients were randomly divided into two groups (n = 12 in each group), and single puncture arthrocentesis (SPA) was performed with and without US guidance in groups 1 and 2. During the one-year follow-up period, the groups were statistically evaluated by the visual analog scale for pain, maximum mouth opening, lateral excursion, and protrusion within each group and between the two groups.

Results Both treatment groups showed significant improvement, compared to the baseline levels for almost all outcome variables. However, there were no statistically significant differences between groups 1 and 2 (p > 0.05).

Conclusion US guidance can be used for cannula placement in SPA. However, the outcome results are the same with or without its use.     

Relationship of self-reported sleep bruxism and awake bruxism with chronotype profiles in Italian dental students

Objectives: A cross-sectional study was performed to assess the association between possible sleep bruxism (SB) and awake bruxism (AB) with sleep characteristics and chronotype (i.e. circadian cycle preference).

Methods: One-hundred-nineteen young adults filled out a self-reported questionnaire to assess SB and AB, a questionnaire about daily life aspects, as well as the Morningness-Eveningness Questionnaire (MEQ) to profile chronotype.

Results: The frequency of self-reported SB and AB was 25.2% and 37.0%, respectively. Both SB and AB were significantly more frequent in females than males. Most participants had an intermediate chronotype profile (n = 85; 71.4%). Neither SB (p = 0.556) nor AB (p = 0.334) were associated with chronotype. Nightmares were more prevalent among individuals with possible SB (38.3%). Difficulty concentrating in daily activities was more frequently reported among individuals with AB (51.9%).

Conclusion: There was no association between possible SB and AB or the chronotype profiles among Italian dental students.     

Potential orofacial hazards of resistance training: A controlled comparative study*

Objective: To evaluate the effect of resistance training (RT) regarding potential hazard for dental wear, tooth abfractions, temporomandibular joint disc displacement, limitation in mouth opening, and existence of cervical spine disorders. The initial study hypothesis was that extensive resistance trainees (ExRT) would suffer from the above-mentioned symptoms more often than recreational trainees (RcT).

Methods: A controlled comparative study among male gym members via questionnaires and a clinical examination.

Results: ExRT had a higher prevalence of teeth indentations on the tongue (26% vs. 2% p < 0.001) and a higher prevalence of tooth abfractions than RcT (28% vs. 4% p < 0.005). ExRT exhibited a higher prevalence of cervical movement limitations (p < 0.05) and inadequate posture (p < 0.001).

Conclusion: RT by itself may not be a risk factor for disc displacement. Nevertheless, it may act as a potential risk factor for irreversible hard tooth tissue damage and contribute to neck postural and mobility impairments.     

TMJ symptoms reduce chewing amplitude and velocity,and increase variability

Objective: The null hypothesis was that mandibular amplitude, velocity, and variability during gum chewing are not altered in subjects with temporomandibular joint (TMJ) internal derangements (ID).

Methods: Thirty symptomatic subjects with confirmed ID consented to chew gum on their left and right sides while being tracked by an incisor-point jaw tracker. A gender and age matched control group (p > 0.67) volunteered to be likewise recorded. Student’s t-test compared the ID group’s mean values to the control group.

Results: The control group opened wider (p < 0.05) and chewed faster (p < 0.05) than the ID group. The mean cycle time of the ID group (0.929 s) was longer than the control group (0.751 s; p < 0.05) and more variable (p < 0.05).

Discussion: The ID group exhibited reduced amplitude and velocity but increased variability during chewing. The null hypothesis was rejected. Further study of adaptation to ID by patients should be pursued.     

Lithuanian dentists’ knowledge,attitudes, and clinical practices regarding obstructive sleep apnea: A nationwide cross-sectional study

Objective: To investigate the knowledge, attitudes toward, and aspects of clinical practice regarding obstructive sleep apnea (OSA) among Lithuanian dentists.

Methods: A cross-sectional study was carried out during the period from December 2016 to March 2017. A survey instrument was designed and pilot tested prior to full-scale administration. Self-administered questionnaires, including a cover letter, were distributed to 550 dentists during continuing dental education programs.

Results: A total of 353 participants (64.2%) completed and returned the questionnaire. Increased years of experience were significantly associated with lesser knowledge about OSA (p < 0.05). However, there were no significant differences between general practitioners and specialists (p = 0.243). Most respondents indicated strong positive attitudes regarding OSA. The majority did not have any clinical experience regarding the management of OSA patients.

Discussion: Development of additional education and practical implementation strategies should be considered in order to overcome the examined barriers.     

Prevalence of temporomandibular symptoms and parafunctional habits in a university dental clinic and association with gender,age, and missing teeth

Objective To assess the prevalence of symptoms of temporomandibular disorder (TMD) and parafunctional habits as well as to investigate their association with age, gender, and number of missing teeth.

Methods This retrospective study is based on 4204 randomly selected patients who were examined to determine their symptoms of TMD, such as clicking, difficulty chewing, difficulty opening/closing, as well self-reported joint pain and parafunctional habits.

Results Clenching/grinding was reported by 26.5% of the examined population, clicking by 14.8%, and difficulty chewing and closing by 3.6%. Significant associations between the number of missing teeth with clenching/grinding (p = 0.05) and difficulty chewing (p < 0.001) were detected. Age and gender showed significant effects on the examined parameters (p < 0.05).

Discussion Understanding the TMD subjective symptoms in relation to age, gender, and tooth loss would be of great value for treatment planning and could provide other perspectives to establish preventive measures.     

Amyotrophic lateral sclerosis presenting as the temporomandibular disorder: A case report and literature review

Background: Spasticity and pain in the masticatory muscles or mouth opening limitation have been reported as early signs and symptoms of amyotrophic lateral sclerosis (ALS). These signs and symptoms are also frequently seen in, and thus mistaken for, temporomandibular disorders (TMD).

Clinical presentation: The authors report a case of ALS initially presenting with signs and symptoms of TMD. The TMD was followed by dysarthria of insidious onset, leading to the diagnosis of ALS. This case highlights the importance of considering TMD as a potential early form of presentation of ALS, requiring multidisciplinary treatment, especially by dental professionals.

Conclusion: A review of the literature was conducted to elucidate the oral and facial signs and symptoms of ALS and to identify ways of improving the quality of life of patients through a multidisciplinary approach.     

Adolescent internal condylar resorption (AICR) of the temporomandibular joint,part 1: A review for diagnosis and treatment considerations

Background: Adolescent internal condylar resorption (AICR) is a temporomandibular joint (TMJ) pathology that develops predominately in teenage females during pubertal growth (onset between ages 11 and 15 years), with a distinct clinical, radiographic, and magnetic resonance imaging (MRI) presentation.

Clinical and imaging presentation: The condition usually occurs bilaterally with: (1) Progressive retrusion of the mandible; (2) High occlusal plane angle facial morphology; (3) Worsening Class II occlusion; and (4) TMJ symptoms such as pain, headaches, noises, etc. MRI imaging demonstrates decreased condylar head size and anterior disc displacement.

Treatment protocol: AICR can be successfully treated when the condyles and discs are salvageable with the following surgical protocol: (1) Removal of bilaminar tissue surrounding the condyle; (2) Reposition the disc with the Mitek anchor technique; and (3) Orthognathic surgery to advance the maxillo-mandibular complex in a counterclockwise direction.

Conclusion: AICR can be successfully treated using the specific protocol presented herein to provide stable and predictable outcomes.     

Temporomandibular joint MR images: Incidental head and neck findings and pathologies

Objective: To report the number and frequency of incidental findings (IFs) detected during magnetic resonance (MR) imaging screening of the temporomandibular joint (TMJ) and to define related diseases.

Methods: Bilateral TMJ MR images in the sagittal and coronal sections, from 518 patients with TMJ symptoms were evaluated retrospectively. Patients who were diagnosed with IFs were sent for consultation and clarification of the findings. Patient age, gender, IFs, locations, and diseases were classified and noted. 

Results: Seventy-eight (15%) patients were diagnosed with 117 IFs. Of them, 43 were diagnosed with a single IF, and 35 were diagnosed with more than one IF. The most frequent locations were paranasal sinuses and mastoid air cells. The most frequent diseases were inflammatory and cystic lesions. 

Discussion: While examining TMJ MR images, it is important to check for evidence of IFs or pathologies that may have mimicked signs and symptoms of TMJ disorders.     

The effectiveness of an occlusal disclosure sheet to diagnose sleep bruxism: A pilot study

Objective: To evaluate the utility of vacuum-pressed, BruxChecker^® sheets for the diagnosis of sleep bruxism.

Methods: Twenty subjects participated in this study. Tooth contact during sleep was recorded using a 0.1 mm-thick polyvinyl chloride sheet called BruxChecker^®. The area of the BruxChecker^® in which the red dye was removed was measured. In addition, the EMG activity of the masseter muscle during sleep was recorded. The numbers of bruxism bursts and episodes were counted, and their correlations with the peeled area of the red dye on the BruxChecker^® were evaluated.

Results: The number of bruxism bursts and episodes/hr significantly correlated with the peeled area at all cut-off values. The peeled area significantly correlated with the number of phasic type bruxism episodes but not with tonic or mixed type bruxism episodes.

Discussion: Since the BruxChecker^® peeled area reflected phasic type sleep bruxism, the sheets may be useful in sleep bruxism screening.     

Outcomes and patient satisfaction following individualized physical therapy treatment for patients diagnosed with temporomandibular disc displacement without reduction with limited opening: A cross-sectional study

Objective: To investigate physical therapy treatment outcomes and patient satisfaction in patients with a diagnosis of disc displacement without reduction with limited opening (DDWoR wLO).

Methods: Records of 97 patients with DDWoR wLO who received physical therapy in one outpatient clinic were used in this cross-sectional study. Outcomes included number of visits, maximum active interincisal opening, self-reported pain, and patient satisfaction.

Results: The average number of physical therapy visits per patient was 5.5, and there were significant improvements in pain rating and interincisal opening following physical therapy. Effect sizes for these comparisons were large (>1.0). Mean patient satisfaction responses across all symptom areas was consistent with patients being more than less satisfied following treatment.

Discussion: Individualized physical therapy treatment is an effective conservative intervention to improve mouth opening, reduce pain, and provide patient satisfaction in patients with one specific sub-type of temporomandibular disorder (TMD), DDWoR wLO.     

Expression of MMP-13 in human temporomandibular joint disc derangement and osteoarthritis

Objective: MMP-13 performs digestion of collagen, which is a primary component of the temporomandibular joint (TMJ) articular disc. This study evaluated the expression of MMP-13 in patients with anterior disc displacement with (ADDwR) and without reduction (ADDwoR), and in the presence of TMJ osteoarthrosis.

Methods: Thirty-nine human temporomandibular joint disc samples were collected and divided in two ways: ADDwR (21 samples), ADDwoR (10 samples), and a control group (8 samples); and with osteoarthrosis (10 samples) and without osteoarthrosis (29 samples). Immunostaining of the TMJ discs was statistically compared between the groups.

Results: There was no statistically significant difference for the area of MMP-13 immunostaining between the control group, ADDwR, and ADDwoR, nor between groups with and without osteoarthrosis.

Conclusion: This study suggests MMP-13 is not significantly involved in collagen degradation in human TMJ disc displacement or osteoarthrosis.     

Mandibular condylar dimensions: Correlation between 3D tomography and dried skull measurements

Objective Compare the anatomical dimensions of mandibular condyles with the same CBCT measurements.

Methods Four landmarks were identified on the condyles of dried skulls and are measured with their corresponding areas in CBCT images: Right Width of Condyle (RW), Left Width of Condyle (LW), Right Length of Condyle (RL), and Left Length of Condyle (LL).

Results With respect to direct measurements on the dry skulls, statistically significant differences were found between sexes (p < 0.001). When the real values were compared with the CBCT, it was observed that the bias depends on the magnitude of the measurement. It means that there is an underestimation for smaller values and an overestimation for larger values.

Conclusion CBCT is reliable imaging modality, but when compared real measures of condyle length are more reliable then width.     

Impact of mounting methods in computerized axiography on assessment of condylar inclination*

Objective: Valid and reliable recording is a key requirement for accurately simulating individual jaw movements.

Methods: Horizontal condylar inclination (HCI) and Bennett’s angle were measured using a digital jaw tracker (Cadiax® Compact 2) in 27 young adults. Three mounting methods (paraocclusal tray adapter, periocclusal tray adapter, and tray adapter with mandibular clamp) were tested.

Results: The mean values of the HCI differed by up to 10° between the mounting methods; however, the values for Bennett’s angle did not differ substantially. While the intersession reliability of the Bennett’s angle assessment did not depend on the mounting method, the reliability of the HCI assessment was only fair to good for the paraocclusal mounting method but poor for both periocclusal mounting methods.

Discussion: For attaching the tracing bow of jaw trackers to the mandible, a paraocclusal tray adapter should be applied, to achieve the most reliable results.     

Effect of breathing type on electromyographic activity of respiratory muscles during tooth clenching at different decubitus positions

Objective: To compare the effect of breathing type on electromyographic (EMG) activity of respiratory muscles during tooth clenching at different decubitus positions.

Methods: Forty young men participants were included, 11 with upper costal, 9 with mixed, and 20 with costo-diaphragmatic breathing type. EMG recordings of diaphragm (DIA), external intercostal (EIC), sternocleidomastoid (SCM), and latissimus dorsi (LAT) muscles during tooth clenching in the intercuspal position were performed in dorsal, left lateral, and ventral decubitus positions.

Results: DIA EMG activity was higher in subjects with upper costal or mixed than with costodiaphragmatic breathing type (p = 0.006; 0.021, respectively), whereas it was similar between upper costal and mixed breathing types. EIC, SCM, and LAT activity was similar among breathing types.

Conclusion: Higher DIA activity would be a risk factor to exceed the adaptive capability of healthy subjects with upper costal or mixed breathing type.     

Brain activation patterns during unilateral premolar occlusion

Objective: To observe the characteristics of brain activation during unilateral premolar occlusion.

Methods: Functional magnetic resonance imaging was collected from 10 healthy volunteers during occlusion of the left first premolar (L1), left second premolar (L2), and right first premolar (R1). The brain activation patterns were analyzed, and the primary sensorimotor cortex, supplementary motor area, insula, thalamus, and prefrontal cortex were chosen as regions of interest.

Results: Single premolar occlusion activated the precentral gyrus, postcentral gyrus, cerebellum, thalamus, frontal lobe, hippocampus, cingulate gyrus, and parietal lobe. The brain areas showing activation during single premolar occlusion were similar to those activated by chewing. The activation pattern of L1 was more similar to that of L2 than R1. No significant left and right hemisphere differences in signal intensity were detected within the regions of interest.

Conclusion: Brain activation patterns from two ipsilateral premolars were more similar than the pattern from a contralateral premolar.     

Osseous changes of the mandibular condyle affect backward-rotation of the mandibular ramus in Angle Class II orthodontic patients with idiopathic condylar resorption of the temporomandibular joint

Objective: To evaluate whether osseous changes of the temporomandibular joint (TMJ) condyle affect backward rotation of the mandibular ramus in Angle Class II orthodontic patients with idiopathic condylar resorption (ICR).

Methods: Twenty Japanese women with Class II malocclusion with ICR (ICR group) and 24 women with Class II malocclusion without ICR (non-ICR group) were examined. Pre-treatment panoramic radiographs were used to measure condylar ratios. Pre-treatment lateral cephalograms were used to evaluate maxillofacial morphology.

Results: The ICR group had a significantly smaller condylar ratio, greater backward rotation of the ramus, less labially inclined upper incisors, and a steeper occlusal plane. The increased backward rotation of the ramus in the ICR group was significantly associated with a smaller condylar ratio.

Conclusion: Angle Class II patients with ICR had shorter condylar height attributable to osseous changes of the TMJ condyle, and the shorter condylar height may affect subsequent backward rotation of the ramus.