Indexes of jaw muscle function in asymptomatic individuals with different occlusal features.

This study aims to assess the correlation between indexes of jaw muscle function and dento-skeletal morphology. A sample of 35 temporomandibular disorders-free healthy individuals (10 males, mean age 26.7 ± 9.8 years) underwent surface electromyographic (sEMG) assessment of bilateral masseter and temporalis muscles, to evaluate sEMG activity during maximum voluntary clenching (MVC) with a dedicated device (Easymyo®, T.F.R. Technology, Udine, Italy). Four outcome parameters were assessed for each individual: MCV on cotton rolls; MVC on teeth; chewing on right and left sides; clench/relax test. Electromyographic recordings were assessed based on five standardized indexes of muscle function, to evaluate the degree of muscle asymmetry during static and dynamic function (i.e., percentage overlapping coefficient [POC], Impact, Asymmetry, Activation, and Torque). For each individual, the presence of a number of occlusal and skeletal features was assessed: asymmetry of molar class; deviated incisor midline; deep bite; open bite; and crossbite. Skeletal class and vertical dimension of occlusion were also evaluated. Based on normality distribution of data, t test and analysis of variance, when needed, were used to compare muscle function indexes between individuals with and without the different dento-skeletal features. None of the muscle function indexes (POC, Impact, Asymmetry, Activation, and Torque) was significantly different between individuals with or without the various dental and skeletal features. Gender differences were also not significant (p > 0.05). Despite some minor differences were observed, none of them was significant. Thus, the interaction between form and function is too complex for hypothesizing a simple one-to-one relationship between interarch tooth relationship and muscle function patterns.

A comparison trial between three treatment modalities for the management of myofascial pain of jaw muscles: A preliminary study.

OBJECTIVES: To compare three treatment modalities for the management of myofascial pain of jaw muscles. METHODS: Thirty (N = 30) patients with low pain-related impairment were randomly assigned to receive laser therapy (LST), oral appliance therapy (OA), or counseling (CSL). Visual Analog Scale (VAS) pain levels and the Muscular Index (MI) of the Craniomandibular Index were the outcome variables, which were assessed at baseline, at three weeks, three months, and six months. RESULTS: At six months, improvement in the MI was maintained both in the LST (p = .025) and OA groups (p < .001). As for VAS values, positive changes were still shown for LST (p = .001), and were also shown for the OA (p = .002) and CSL groups (p = .048). CONCLUSIONS: Despite differences in the short-term effectiveness of LST and OA, with respect to CSL alone, all three treatment groups improved at six months. This suggests that active treatments should be directed to maximize the positive changes in the short-term period.

Multidisciplinary correction of anterior open bite relapse and upper airway obstruction.

A 27-year-old man presented an anterior open bite relapse. He had low tongue posture positioned anteriorly at rest and during swallowing and reported chronic difficulty in nose breathing. Head cone-beam computed tomography revealed nasal septum deviation, right turbinate hypertrophy, and left maxillary sinus congestion, which were thought to contribute to the breathing problem, encourage the improper tongue posture, and thereby cause the relapse. Multidisciplinary treatment involving an otorhinolaryngologist, an orthodontist, and a periodontist resolved the upper airway obstruction and corrected the malocclusion. The follow-up examination after 3 years 5 months demonstrated stable results.

A conservative surgical approach to temporomandibular joint ankylosis.

The current article describes a case of a patient with temporomandibular joint (TMJ) ankylosis undergoing surgery performed with a tailored technique for condylar reshaping. A patient with posttraumatic bilateral TMJ ankylosis underwent interpositional arthroplasty with temporalis fascia, and focus was put on the need to maintain the vertical height of the mandible. The postoperative course was uneventful, and positive outcomes were kept during a 1-year follow-up span. The adoption of surgical strategies aiming at restoring a condylar shape as similar as possible to the natural one may be important in the light of the search for surgeries providing and/or recreating normal function of the TMJ.

Surface electromyography findings in unilateral myofascial pain patients: comparison of painful vs. non painful sides.

OBJECTIVES: To answer the clinical research question: in patients with myofascial pain, are there any differences in the surface electromyography (sEMG) activity of muscles of the painful and nonpainful sides that can be detected by commercially available devices? METHODS: The study sample (N = 39; 64% F, mean age 35.7 ± 15 years) consisted of patients seeking for temporomandibular disorders Temporomandibular Disorders (TMD) treatment and meeting Research Diagnostic Criteria for TMD (RDC/TMD) diagnosis of myofascial pain, with pain referred only in muscles on one side. They underwent sEMG of jaw muscles to record levels of standardized sEMG activity at rest, as well as during maximum clenching on teeth for the four investigated muscles, viz., bilateral masseter and temporalis. The existence of differences between sEMG values of muscles of the painful and nonpainful sides during the standardization test (i.e., clenching on cotton rolls) at rest and during clenching on teeth was assessed. RESULTS: At the study population level, differences between the sEMG values of muscles of the painful and nonpainful sides were not significant in any conditions, viz., either at rest or during clenching tasks. At the individual level, the difference between the sEMG activity of painful and nonpainful sides was very variable. CONCLUSIONS: The above findings were not supportive of the existence of any detectable difference in sEMG activity between jaw muscles of the painful and nonpainful sides in patients with unilateral myofascial pain. Centrally mediated mechanism for pain adaptation may explain these findings, and the role of sEMG as a diagnostic tool for muscle pain needs to be carefully reconceptualized.

An assessment of the usefulness of jaw kinesiography in monitoring temporomandibular disorders: correlation of treatment-related kinesiographic and pain changes in patients receiving temporomandibular joint injections.

BACKGROUND: The authors conducted a study in patients with temporomandibular joint (TMJ) osteoarthritis to assess whether treatment-related changes in pain levels and chewing ability coincide with a change in jaw kinesiographic (KG) parameters. METHODS: The authors selected 34 patients with a diagnosis of TMJ osteoarthritis that met Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) to undergo a cycle of five weekly arthrocentesis procedures with injections of 1 milliliter hyaluronic acid. They performed a permutation test to assess the correlation between changes across time (from baseline to end of treatment) in two clinical outcome parameters-pain level and chewing ability-and changes across time in the KG outcome parameters. RESULTS: The authors observed improvement across time in both chewing ability (F = 8.328; P = .005) and pain level (F = 10.903; P = .002). The authors observed no significant changes in any KG variables. With minor exceptions, no significant correlations were shown between changes in the clinical and KG parameters during the treatment period. CONCLUSIONS: Treatment-related changes in pain levels and chewing ability in patients with TMJ osteoarthritis do not coincide with changes in KG parameters. PRACTICAL IMPLICATIONS: If one assumes pain variables to be the primary outcome measures in assessing treatment of TMJ osteoarthritis, KG recordings of the jaw are not useful for monitoring TMJ osteoarthritis in the clinical setting.

Kinesiographic recordings of jaw movements are not accurate to detect magnetic resonance-diagnosed temporomandibular joint (TMJ) effusion and disk displacement: findings from a validation study.

OBJECTIVE: The aim of this study was to perform a validation study assessing the correlation between magnetic resonance (MR) findings of temporomandibular joint (TMJ) disk displacement and effusion and some parameters drawn from kinesiographic (KG) recordings of jaw motion, i.e., deflection, deviations, incisures. STUDY DESIGN: Thirty-one patients with TMJ disorders underwent a kinesiographic recording in the same day in which the MR was performed. Regression analysis was performed to assess the correlation between the MR and KG findings. RESULTS: MR findings were not correlated with KG parameters (P > .05). The accuracy of all KG variables for diagnosing MR-detected signs was low. KG deflection ranged from 38.7% to 54.8%, KG deviation from 42% to 54.8%, and KG incisures from 9.6% to 71%. Specificity and positive predictive values were far from acceptable levels for all KG variables. CONCLUSIONS: The findings do not support the usefulness of jaw-tracking devices in dental practices that diagnose and manage temporomandibular disorders.

Comparative analysis of anchorage systems for micro implant orthodontics.

OBJECTIVE: The study analysed twelve anchorage systems based on micro implants in terms of their bio-mechanical properties and appraised their actual clinical effectiveness. MATERIALS AND METHODS: The analysed micro implants had data provided by the manufacturers or extracted from articles published in specialised journals. The parameters taken into account were: material, surface treatment, head type, length, diameter, neck length, filleted self drilling or self tapping surface, applicable orthodontic forces, possibility of immediate loading, and device removal. RESULTS: Material Grade 5 titanium, titanium alloy (TiAl6V4), surgical steel; surfaces: smooth, sand-blasted and acid etched; head type: bracket, conic with button, round, hexagonal, button with cross cuts, double melted sphere; lengths: between 8.0 to 14 mm; diameters: between 1.2 to 2.0 mms; neck lengths: inferior to 1.5mm and superior to 2.0mm; filleted portion: self tapping and/or self drilling; applicable orthodontic forces: up to 500 g, possibility of immediate loading, device removal, possibility to use in growing patients. DISCUSSION: The most widely used material was TiAl6V4; most of the surfaces were smooth; the most commonly used head type was the bracket; the most often produced length was the "short" one (8.0-9.9 mm), the most demanded diameter the "smaller" one (1.2-1.4 mms); six systems out of eleven had micro implants with "extra" and "standard" necks; only 3 systems out of eleven produced "non self drilling"devices; all the micro implants analysed were able to withstand orthodontic forces between 150 g and 350 g; all devices were suitable for "immediate loading"; all micro implants had to be removed; all micro implants could be used in growing patients. CONCLUSIONS: The comparative analysis showed that micro implants could be used as valid anchorage systems, if dental anchorage was insufficient either in qualitative terms (i.e. parodontal problems) or in quantitative terms (i.e. few dental elements remaining), and in all those situations of limited patient compliance.

Virtual study models: a comparison of modular application systems.

INTRODUCTION: Virtual study models made their first appearance on the orthodontic market in 1999. The early systems offered two-dimensional images; reliable 3D images of study models were obtained only with the introduction of laser technology. Virtual study models have reduced the number of limitations and obstacles associated with the use of conventional plaster models and resulted in the creation of the "paperless orthodontic office". To understand their drawbacks, advantages and affordability, the different systems available for virtual dental casts were compared. DISCUSSION: The systems envisaging the use of 3D virtual study models are: Orthocad, e-models, Orthoproof, SureSmile, Invisalign and Libra. All of these systems offer model "manipulation" options, whereas only Orthocad, e-models and SureSmile offer advanced levels of software complexity, so as to ensure: virtual set-up, computer-aided bracket placement, planning and construction of orthodontic appliances. The use of hand-held scanners calls for highly specific skills. Basic requirements to use digital models include: a personal computer, internet access, management software. CONCLUSION: The digital elaboration of orthodontic study models is developing beyond the collection of morphologic and diagnostic data, towards the planning and production of orthodontic devices, through the use of morphing simulating the several phases of the treatment. Digital 3D models can be used at a basic and at a more advanced level, depending on the clinician's level of experience.