Jaw Opening Research Articles

Effect of Short-Term Forward Head Posture Correction for Masseter Muscle Activity and Temporomandibular Joint Function for People with Upper Cross Syndrome

Background. In 1996, meta-analysis of studies was performed and it showed the connections between head posture changes and temporomandibular joint (TMJ) dysfunctions (Harrison et al., 1996), but the abnormalities of the mandibular usually were treated as the only pathology leading to poor clinical effect (Lee et al., 2017). Supposedly, occlusion problems are related not only to the position of the jaw and skull, but also to the shoulder and spine, which act as a biomechanical chain (Moreno, Aranza, 2013; Shousha et al., 2018). There is a lack of evidence how head posture correction changes stomatognathic system functions, that is why our study aimed to determine if a short-term head posture correction affects the system. Research aim. Determine the effect of short-term forward head posture correction for temporomandibular joint (TMJ) function. Research methods. Evaluation of posture, TMJ range of motion, jaw opening stereotype. Research results. After a short-term head posture correction, head inclination angle alteration was as follows: ScapularR = 5.65°, ScapularL = 3.9°. Jaw opening alteration was ScapularR 15.09 mm, ScapularL 15.58 mm. The difference between mandibular deviations decreased to ScapularR 0.32 mm; ScapularL 1.60 mm. Deviation during jaw opening reduced ScapularR 2.06 mm; ScapularL 2.38 mm. Conclusion. Short-term head posture correction signifcantly reduced head inclination angle, mandibular opening movement amplitude and deviation from the centre line in individuals with upper cross syndrome and asymmetric scapular position.Keywords: temporomandibular joint, head posture, upper cross syndrome.

Two applications of movable mandible for physical models of the human vocal tract

The first application of a movable mandible for physical models of the human vocal tract is based on the 2017 static-model, the vocal-tract configuration of which was set to produce the vowel /a/. Two parts of the model, upper and lower jaws, are combined with a miniature robot hand unit to achieve articulatory movements for visual cues in a speech perception study. The second application is based on the 2018 dynamic-model, which is physically able to produce human-like speech sounds with a flexible material. Because portions of the articulators including the top surface of the tongue are made of a gel-type material, a user can manipulate the shape of the tongue and articulate different vowels and a certain set of consonants for educational purposes, for example. However, the mandible of the model is fixed, making it difficult to manipulate different sounds with different jaw openings, such as high versus low vowels. Therefore, a new model was developed by adding an additional mandible mechanism to the 20...

Improved Lung Sparing by Limiting Jaw Opening During Volumetric Modulated Arc Therapy for Mesothelioma Involving All Ipsilateral Pleural Surfaces

Improved Lung Sparing by Limiting Jaw Opening During Volumetric Modulated Arc Therapy for Mesothelioma Involving All Ipsilateral Pleural Surfaces

Canine Masticator Myositis in a Rottweiler Breed Dog

Canine masticator muscle myositis is an autoimmune disease which reasons are unclear. This muscle myositis generally seen in big dog breeds. General symptoms are pain and atrophy in the chewing muscle group, difficulty in opening jaw and weight loss. Our case was 2 years old, castrated male, rottweiler breed dog which was brought to our clinic with the complaints of face swelling and difficulty in chewing in 2 weeks. Complete blood count and serum biochemistry was carried out and eosinophilia was determined. We have used computed tomography to detect structural changes in masticatory muscles and diagnosed masticatory muscle myositis according to CT and laboratory test results. Cortisone treatment was started with out loosing any time and also laser therapy was added to the classical treatment to reduce pain. In the following days, because of the difficulty of the feeding and severe losing in body weight like reasons, euthanesia was recommended.

Fixed‐jaw technique to improve IMRT plan quality for the treatment of cervical and upper thoracic esophageal cancer

The purpose of this study was to investigate the potential advantages of the fixed‐jaw technique (FJT) over the conventional split‐field technique (SFT) for cervical and upper thoracic esophageal cancer (EC) patients treated with intensity‐modulated radiotherapy. The SFT and FJT plans were generated for 15 patients with cervical and upper thoracic EC. Dosimetric parameters and delivery efficiency were compared. An area ratio (AR) of the jaw opening to multileaf collimator (MLC) aperture weighted by the number of monitor units (MUs) was defined to evaluate the impact of the transmission through the MLC on the dose gradient outside the PTV50.4, and the correlation between the gradient index (GI) and AR was analyzed. The FJT plans achieved a better GI and AR (P < 0.001). There was a positive correlation between the GI and AR in the FJT (r = 0.883, P < 0.001) and SFT plans (r = 0.836, P < 0.001), respectively. Moreover, the mean dose (Dmean), V5Gy–V40Gy for the lungs and the Dmean, V5Gy–V50Gy for the body‐PTV50.4 in the FJT plans were lower than those in the SFT plans (P < 0.05). The FJT plans demonstrated a reduction trend in the doses to the spinal cord PRV and heart, but only the difference in the heart Dmean reached statistical significance (P < 0.05). The FJT plans reduced the number of MUs and subfields by 5.5% and 17.9% and slightly shortened the delivery time by 0.23 min (P < 0.05). The gamma‐index passing rates were above 95% for both plans. The FJT combined with target splitting can provide superior organs at risk sparing and similar target coverage without compromising delivery efficiency and should be a preferred intensity‐modulated radiotherapy planning method for cervical and upper thoracic EC patients.

The pro-algesic effect of γ-aminobutyric acid (GABA) injection into the masseter muscle of healthy men and women.

Background and aims Preclinical studies have reported that activation of peripheral γ-aminobutyric acid A (GABAA) receptors may result in analgesia. The current study was conducted in young healthy men (n = 30) and women (n = 28) to determine whether injections of GABA into the masseter muscle reduce pain in a sex-related manner. Methods The effect of injection of GABA alone, or in combination with the non-inflammatory algogen glutamate, was assessed in two separate studies. Lorazepam, a positive allosteric modulator of the GABAA-receptor, was co-injected with GABA in both studies to explore the role of this receptor in muscle pain responses of healthy human volunteers. Masticatory muscle mechanical pain intensity was recorded on an electronic visual analogue scale (VAS) while muscle pain sensitivity was assessed by determining the pressure pain threshold (PPT), tolerance and maximal jaw opening (MJO) of the subjects prior to, and again after the various intramuscular injections. Results Intramuscular injection of GABA alone was reported to be significantly more painful, in a concentration related manner, than saline control injections, and this pain was further increased by co-injection of lorazepam with GABA. Co-injection of GABA with glutamate was found to significantly increase glutamate-evoked masseter muscle pain in men, but not in women. There was no effect of injections of either GABA alone, or GABA with glutamate, on PPT, tolerance or maximum jaw opening. Conclusions Injection of GABA into the human masseter muscle appears to excite nociceptors to produce muscle pain without a longer term effect on mechanical pain sensitivity in the muscle. The findings suggest that GABA-mediated pain in humans is produced through peripheral GABAA receptor activation. The mechanism underlying the sex-related difference in the effect of GABA on glutamate-evoked muscle pain was speculated to be due to a methodological artifact. Implications This study was designed to detect analgesic rather than algesic effects of peripherally administered GABA, and as a result, the concentration of glutamate chosen for injection was close to the maximal pain response for healthy women, based on previously determined pain-concentration response relationships for glutamate. This may explain the finding of greater pain in men than women, when GABA and glutamate were co-injected. Overall, the findings suggest that activation of peripheral GABAA receptors in human masticatory muscle produces pain, possibly due to depolarization of the masticatory muscle afferent fibers.

BIS guided conditions for ProSeal laryngeal mask airway insertion – A comparison of Propofol versus sevoflurane with or without fentanyl

BIS guided conditions for ProSeal laryngeal mask airway insertion – A comparison of Propofol versus sevoflurane with or without fentanyl - IJCA- Print ISSN No: - 2394-4781 Online ISSN No:- 2394-4994 Article DOI No:- 10.18231/j.ijca.2019.061, Indian Journal of Clinical Anaesthesia-Indian J Clin Anaesth

Effects of jaw exercise intervention timing on outcomes following oral and oropharyngeal cancer surgery: Pilot study.

Common in head and neck cancer patients, trismus can make speech and swallowing difficult and can compromise quality of life (QOL). Jaw range of motion exercise therapy may prevent or treat trismus in surgical patients. While the importance of these exercises is well-documented, there is little literature regarding the optimal timing of exercise initiation. A prospective pilot study investigated the effects of early vs late jaw exercise intervention on postoperative jaw opening and QOL measures, which were examined descriptively. Timing of exercise intervention was not found to significantly impact the measured outcomes. However, provisional, descriptive findings showed that jaw opening was significantly associated with multiple QOL measures, with greater jaw opening associated with improved QOL. For certain QOL measures, this positive association was stronger at earlier time points than at later time points. The exploratory findings of this pilot study support further research into possible benefits of early jaw exercise intervention.

Feeding kinematics and morphology of the alligator gar (Atractosteus spatula, Lacépède, 1803).

Living gars are a small clade of seven species that occupy an important position on the actinopterygian phylogenetic tree as members of Holostei, sister-group to teleosts, and exhibit many plesiomorphic traits used to interpret and reconstruct early osteichthyan feeding mechanisms. Previous studies of gar feeding kinematics have focused on the ram-based, lateral-snapping mode of prey capture found in the narrow-snouted Lepisosteus genus, whereas this study focuses on a member of the broad-snouted Atractosteus sister-genus, the alligator gar (Atractosteus spatula, Lacépède, 1803). High-speed videography reveals that the feeding system of alligator gars is capable of rapid expansion from anterior to posterior, timed in a way to generate suction, counteract the effects of a bow-wave during ram-feeding, and direct a unidirectional flow of water through the feeding system. Reconstructed contrast-enhanced μCT-based cranial anatomy and three-dimensional modeling of linkage mechanics show that a lateral-sliding palatoquadrate, flexible intrasuspensorial joint, pivoting interhyal, and retractable pectoral girdle increase the range of motion and expansive capabilities of the alligator gar feeding mechanism. Reconstructions of muscular anatomy, inferences from in vivo kinematics, and in situ manipulations show that input from the hyoid constrictors and hypaxials play an important role in decoupling and modulating the dual roles of the sternohyoideus during feeding: hyoid retraction (jaw opening) and hyoid rotation (pharyngeal expansion). The alligator gar possesses an intricate feeding mechanism, capable of precise control with plesiomorphic muscles that represent one of the many ways the ancestral osteichthyan feeding mechanism has been modified for prey capture.

Maximal Jaw Opening as a Method of Producing Concurrent Activation Potentiation

Purpose: The purpose of this study was to examine maximal jaw opening as a strategy to elicit concurrent activation potentiation during countermovement vertical jump performance and bilateral grip strength assessment in both males and females. Methods: Twenty-four males (age 21.25 ± 1.45 years; height 177.64 ± 7.67 cm; mass 83.87 ± 9.08 kg) and 24 females (age 21.38 ± 2.12 years; height 165.84 ± 8.96 cm; mass 66.4 ± 13.42 kg) participated in this investigation. Maximal countermovement jump height was recorded using a Just Jump Mat, and dominant and non-dominant handgrip strength was recorded using a digital hand dynamometer under two experimental conditions: jaw relaxed and jaw maximally opened. Paired-sample t-tests were conducted for each dependent variable of interest to determine the differences between the research conditions. Results: Maximally opening the jaw led to improvements in vertical jump height (p = 0.013, d = 0.225), dominant hand (p = 0.028, d = 0.162), and non-dominant handgrip strength (p = 0.011, d = 0.241) in males, and although these variables were improved in females under the jaw open condition, that improvement did not reach statistical significance (p &gt; 0.05). Conclusion: This study supports maximally opening the jaw as an effective strategy for producing concurrent activation potentiation, particularly in males.

A comparative clinical study on physiotherapy outcomes with wooden tongue depressors versus Heister jaw opener in oral submucous fibrosis patients

ObjectiveThe aim of this study was to compare mouth opening exercise outcomes with wooden tongue depressors (WTDs) versus Heister jaw opener (HJO) in improving mouth opening after reconstruction of the surgical defect with buccal fat pad (BFP) in oral submucous fibrosis (OSF) patients. Materials and methodsFifty consecutive patients were divided randomly into two groups (25 patients in each group) corresponding to postoperative physiotherapy with WTDs (group 1) and HJO (group 2) respectively. Groups 1 and 2 were evaluated for maximum interincisal distance at 3, 6 and 12 months of follow up. In groups 1 and 2, mouth opening differed substantially at all periods of follow up from preoperative values. ResultsThe increase in mouth opening was greater in group 2 at 3 (P = 0.003) and 6 (P = 0.010) month follow up visit respectively. No relevant difference was observed in mouth opening between groups 1 and 2 at 12 months (P = 0.066). The mean increase in mouth opening at 12 months compared with the preoperative value was 22.2 mm in group 1 and 25 mm in group 2. ConclusionWe conclude both WTDs and HJO are effective in improving postoperative mouth opening in OSF surgical patients.

Temporomandibular disorders - Heterogeneous disorders with need for treatment individualization

The term "temporomandibular disorders" (or TMD) is a collective term used to describe a group of craniofacial pain problems that involve the jaw, temporomandibular joints (TMJs), muscles of mastication, surrounding bony and soft tissue components, and associated head -and-neck musculoskeletal structures or any combinations of these. Most frequently the patients present with pain, limitation and/ or deviation of the jaw opening and TMJ sounds (clicking). It may be associated with other symptoms, including ear pain and stuffiness, tinnitus, dizziness, cervical pain, and headache. Some patients may present with acute onset with self-limiting symptoms.

Interpositional gap arthroplasty with pedicled temporalis galea flap in bilateral temporomandibular joint ankylosis

Background: Neglected condylar fractures often cause several jaw dysfunction such as deviation of jaw, facial asymetri and ankylosis. Ankylosis of the jaw could involve the intra capsular,extracapsular compartement and the arcus zygomaticus involvement. Limitation of jaw opening as the result of ankylosis could decrease patient's quality of life due to mastication, speaking and esthetic disturbance. Gap arthroplasty and interpositional arthroplasty become the treatment of choice for TMJ ankylosis. Temporalis muscle flap and temporal fascia flap are commonly used material for interpositioning in gap arthroplasty. Interpostitional gap arthroplasty using pedicled temporalis galea flap provides less complicated but fully vascularized flap TMJ ankylosis.

Voice and swallowing dysfunction in X‐linked dystonia parkinsonism

To systematically characterize and describe voice and swallowing manifestations in patients with X-linked dystonia parkinsonism (XDP) and correlate with quality-of-life (QOL) measures. Thirty-four patients with XDP with communication and swallowing difficulties underwent neurological examination, head and neck examination, nasopharyngoscopy, QOL surveys (Swallowing Quality of Life questionnaire [SWAL-QOL] and Voice Handicap Index [VHI]), and functional endoscopic evaluation of swallowing (FEES) to assess the extent of dysfunction. All patients showed high rates of lingual, oromandibular, and laryngeal dysfunction, as well as severe QOL changes in swallowing and communication ability. The most common head and neck manifestations of dystonic symptoms were difficulty coordinating the mouth and tongue (79%), uncontrollable tongue thrusting (53%), and jaw opening (35%). Laryngeal symptoms including vocal strain (adductor voice breaks) or stridor (32%), as well as velopharyngeal insufficiency (20%), were also identified. Of the patients with laryngeal symptoms, 18% had respiratory dystonia. Swallowing assessments showed significant abnormalities in oral bolus control and oropharyngeal dysphagia. FEES examinations showed that 87.5% of the study group had penetration or aspiration. QOL scores showed an average VHI of 94.4 (severe dysfunction), and SWAL-QOL showed an average of 37.7 (severe dysfunction). Swallowing and voice impairment in XDP is not well characterized and presents a more distinctive phenomenology than other neurological disorders, with a unique set of challenges for treatment. This is the first study to systematically evaluate laryngeal and pharyngeal dysfunction in XDP patients and correlate with QOL measures. 4 Laryngoscope, 130:171-177, 2020.

Influence of jaw opening on occlusal vertical dimension between incisors and molars

Statement of problemModification of the occlusal vertical dimension (OVD) is a significant procedure in prosthodontics. Improper estimation of the space available between opposing teeth may lead to an improper framework design. PurposeThe purpose of this clinical study was to evaluate the average opening ratio in the molar area in relation to the extent of opening in the incisor area. Material and methodsA total 34 adults with a complete dentition and stable occlusion participated in the study. The change in vertical distance was evaluated in 3 areas: between the maxillary and mandibular central incisors, between the maxillary and mandibular canines, and between the maxillary and mandibular first molars. Digital photographs were made at the intercuspal position (ICP) and at a 2-mm and 8-mm OVD increase. The OVD opening was standardized with the aid of a Woelfel sliding guide device. The measurements were made by recording the distance between the maxillary and mandibular teeth at different openings. For calibration and quantitative evaluation of the photographs, image-processing analysis was used. ResultsThe collected data showed that the average ratio of the opening between the first molars and the opening between the central incisors was 0.73. The average ratio of the opening between the canines and the opening between the central incisors was 0.95. The values were plotted, and a mathematical model was derived. ConclusionsA vertical dimension opening of 1 mm between the central incisors resulted in 0.73 mm of occlusal clearance in the first molar region and 0.95 mm in the canines.

A comparison of normalized formant trajectories of English vowels produced by American men and women*

Formant trajectories reflect the continuous variation of speakers’ articulatory movements over time. This study examined formant trajectories of English vowels produced by ninety-three American men and women; the values were normalized using the scale function in <italic>R</italic> and compared using generalized additive mixed models (GAMMs). <italic>Praat</italic> was used to read the sound data of <xref ref-type="bibr" rid="B7">Hillenbrand et al. (1995)</xref>. A formant analysis script was prepared, and six formant values at the corresponding time points within each vowel segment were collected. The results indicate that women yielded proportionately higher formant values than men. The standard deviations of each group showed similar patterns at the first formant (F1) and the second formant (F2) axes and at the measurement points. <italic>R</italic> was used to scale the first two formant data sets of men and women separately. GAMMs of all the scaled formant data produced various patterns of deviation along the measurement points. Generally, more group difference exists in F1 than in F2. Also, women’s trajectories appear more dynamic along the vertical and horizontal axes than those of men. The trajectories are related acoustically to F1 and F2 and anatomically to jaw opening and tongue position. We conclude that scaling and nonlinear testing are useful tools for pinpointing differences between speaker group’s formant trajectories. This research could be useful as a foundation for future studies comparing curvilinear data sets.

Applying refined automatic formant measurement to determination of the orientations of vowel distributions

In order to remedy recurrent problems with false formant readings obtained with an automatic formant measurement routine, prototype-based automatic measurements were compared with manual formant measurements of the same uttered vowels. Two refinements that avoided false formants, one involving the option to skip measured formant racks and the other involving an expectation that successive formants would show successively lower amplitudes, were developed. This method was then applied to seven corpora representing diverse English dialects, with satisfactory results. The measurements of each vowel thus obtained were then subjected to principle component analysis to determine the orientation of the tokens in F1/F2 space. Most vowels exhibited distributions that apparently reflect degree of jaw opening. However, /u/ in North American varieties (with pre-/l/ and post-/j/ tokens excluded) showed mostly horizontal orientations, even when post-coronal and non-post-coronal tokens were considered separately. This pattern contrasted sharply with the vertical orientations of mid back vowels. /u/ was also the only vowel whose orientations coincided consistently with ongoing changes in the communities. We hypothesize that the factors responsible for the horizontal orientations of /u/ also lie behind its cross-linguistic tendency to shift frontward. In order to remedy recurrent problems with false formant readings obtained with an automatic formant measurement routine, prototype-based automatic measurements were compared with manual formant measurements of the same uttered vowels. Two refinements that avoided false formants, one involving the option to skip measured formant racks and the other involving an expectation that successive formants would show successively lower amplitudes, were developed. This method was then applied to seven corpora representing diverse English dialects, with satisfactory results. The measurements of each vowel thus obtained were then subjected to principle component analysis to determine the orientation of the tokens in F1/F2 space. Most vowels exhibited distributions that apparently reflect degree of jaw opening. However, /u/ in North American varieties (with pre-/l/ and post-/j/ tokens excluded) showed mostly horizontal orientations, even when post-coronal and non-post-coronal tokens were considered separately. This pa...

Rolling of the jaw is essential for mammalian chewing and tribosphenic molar function

Over the past two centuries, mammalian chewing and related anatomical features have been among the most discussed of all vertebrate evolutionary innovations1-3. Chief among these features are two characters: the dentary-only mandible, and the tribosphenic molar with its triangulated upper cusps and lower talonid basin3-5. The flexible mandibular joint and the unfused symphysis of ancestral mammals-in combination with transformations of the adductor musculature and palate-are thought to have permitted greater mobility of each lower jaw, or hemimandible6,7. Following the appearance of precise dental occlusion near the origin of the mammalian crown8,9, therians evolved a tribosphenic molar with a craggy topography that is presumed to have been used to catch, cut and crush food. Here we describe the ancestral tribosphenic therian chewing stroke, as conserved in the short-tailed opossum Monodelphis domestica: it is a simple symmetrical sequence of lower tooth-row eversion and inversion during jaw opening and closing, respectively, enacted by hemimandibular long-axis rotation. This sequence is coupled with an eversion-inversion rotational grinding stroke. We infer that the ancestral therian chewing stroke relied heavily on long-axis rotation, including symmetrical eversion and inversion (inherited from the first mammaliaforms) as well as a mortar-and-pestle rotational grinding stroke that was inherited from stem therians along with the tribosphenic molar. The yaw-dominated masticatory cycle of primates, ungulates and other bunodont therians is derived; it is necessitated by a secondarily fused jaw symphysis, and permitted by the reduction of high, interlocking cusps10-12. The development of an efficient masticatory system-culminating in the tribosphenic apparatus-allowed early mammals to begin the process of digestion by shearing and crushing food into small boli instead of swallowing larger pieces in the reptilian manner, which necessitates a long, slow and wholly chemical breakdown. The vast diversity of mammalian teeth has emerged from the basic tribosphenic groundplan13.

Longitudinal evaluation of the effects of low-power laser phototherapy on mandibular movements, pain, and edema after orthognathic surgery

The aim of this study was to longitudinally evaluate mandibular movements, pain, and edema in patients who underwent low-power laser (LPL) phototherapy after bimaxillary orthognathic surgery.A double-blind, randomized, controlled clinical trial was conducted using 30 patients, who were divided into a study group (n = 15) and control group (n = 15). The former group received postoperative LPL (3 J/cm2, 808 nm, and 100 mW) and the latter group received placebo LPL phototherapy.Over a period of 60 days, these groups were evaluated for: mandibular movements — opening, laterality, and protrusion; pain — visual analogue scale; and edema — measured between cephalometric points. The study group showed significantly better jaw opening (p = 0.009), laterality (p = 0.036), and protrusion (p = 0.029) after 2 weeks in most comparisons.The study group showed significantly less postoperative pain (p < 0.001) in most comparisons, and they recovered from pain earlier than the control group. There was a reduction in edema, with no statistically significant difference for most measurements.As observed in most analyses, there were increases in values for all mandibular movements, no significant differences in the occurrence of edema, and decreases in the occurrence of pain.

Optimizing beam models for dosimetric accuracy over a wide range of treatments

This work presents a systematic approach for testing a dose calculation algorithm over a variety of conditions designed to span the possible range of clinical treatment plans. Using this method, a TrueBeam STx machine with high definition multi-leaf collimators (MLCs) was commissioned in the RayStation treatment planning system (TPS). The initial model parameters values were determined by comparing TPS calculations with standard measured depth dose and profile curves. The MLC leaf offset calibration was determined by comparing measured and calculated field edges utilizing a wide range of MLC retracted and over-travel positions. The radial fluence was adjusted using profiles through both the center and corners of the largest field size, and through measurements of small fields that were located at highly off-axis positions. The flattening filter source was adjusted to improve the TPS agreement for the output of MLC-defined fields with much larger jaw openings. The MLC leaf transmission and leaf end parameters were adjusted to optimize the TPS agreement for highly modulated intensity-modulated radiotherapy (IMRT) plans. The final model was validated for simple open fields, multiple field configurations, the TG 119 C-shape target test, and a battery of clinical IMRT and volumetric-modulated arc therapy (VMAT) plans. The commissioning process detected potential dosimetric errors of over 10% and resulted in a final model that provided in general 3% dosimetric accuracy. This study demonstrates the importance of using a variety of conditions to adjust a beam model and provides an effective framework for achieving high dosimetric accuracy.