Bite Position Research Articles

Physical aspects of live clarinet performances

The clarinet is arguably the wind instrument that has been most extensively studied and described from the point of view of its physics. It has a relatively simple geometry, its embouchure can be fairly well approximated by a set of two control variables, and the air column can be accessed relatively easily, allowing for the measurement of control variables and acoustic variables close to the mouthpiece. As a result, extensive datasets have been collected, allowing understanding of how the sound produced by the instrument changes as a function of its control parameters. In this presentation, we explore a new dataset of control variables (mean reed displacement, blowing pressure, bite position, and others) and acoustic variables (sound level, pitch, spectral centroid, and others) recorded in performances on the clarinet by expert players. These data are compared with measurements and modeling of the instrument blown in mechanical conditions.

Evaluation of the thickness and internal structure of the masseter muscle with ultrasonography in female bruxism patients.

The aim of this study was to evaluate the differences in the thickness and internal structure of the masseter muscle in individuals with and without bruxism by ultrasonography. A total of 60 female patients with and without bruxism whose ages were ranging between 20 and 35 were included in the study. The masseter muscle thickness was measured during rest and maximum bite position. Ultrasonographic internal structure of the masseter muscle is classified according to the visibility of echogenic bands. In addition, the echogenic internal structure of the masseter muscle was evaluated with quantitative muscle ultrasound. The masseter muscle thickness was significantly higher in both positions in patients with bruxism (p < 0.05). There was no significant difference between two groups in the evaluation of echogenicity (p > 0.05). Ultrasonography is a useful and important diagnostic method for evaluating masseter muscle without using radiation.

A well-preserved 'placoderm' (stem-group Gnathostomata) upper jaw from the Early Devonian of Mongolia clarifies jaw evolution.

The origin of jaws and teeth remains contentious in vertebrate evolution. 'Placoderms' (Silurian-Devonian armoured jawed fishes) are central to debates on the origins of these anatomical structures. 'Acanthothoracids' are generally considered the most primitive 'placoderms'. However, they are so far known mainly from disarticulated skeletal elements that are typically incomplete. The structure of the jaws-particularly the jaw hinge-is poorly known, leaving open questions about their jaw function and comparison with other placoderms and modern gnathostomes. Here we describe a near-complete 'acanthothoracid' upper jaw, allowing us to reconstruct the likely orientation and angle of the bite and compare its morphology with that of other known 'placoderm' groups. We clarify that the bite position is located on the upper jaw cartilage rather than on the dermal cheek and thus show that there is a highly conserved bite morphology among most groups of 'placoderms', regardless of their overall cranial geometry. Incorporation of the dermal skeleton appears to provide a sound biomechanical basis for jaw origins. It appears that 'acanthothoracid' dentitions were fundamentally similar in location to that of arthrodire 'placoderms', rather than resembling bony fishes. Irrespective of current phylogenetic uncertainty, the new data here resolve the likely general condition for 'placoderms' as a whole, and as such, ancestral morphology of known jawed vertebrates.

A deep dive into the static force transmission of the human masticatory system and its biomechanical effects on the temporomandibular joint

ObjectiveThis study aims to investigate the biomechanical behavior and reveal the force transmission patterns of the human masticatory system through advanced three-dimensional finite element (FE) models. MethodsThe FE model was constructed according to the medical images of a healthy male adult. It contains full skull structures, detailed temporomandibular joints (TMJs) with discs, complete dentitions, masticatory muscles, and related ligaments. Several static bite scenarios were simulated to demonstrate the effects of bite positions and muscle force recruitments on the force transmission patterns. ResultsMolar occlusal surfaces are the primary force transmission region for clenching. Sensitivity analysis demonstrated that the stiffness of the bite substance would not alter the force transmission patterns but could affect the maximum contact stresses on the discs and the occlusal surfaces. During the unilateral clenching tasks, the high-stress region on the discal surfaces shifted ipsilaterally. The presence or absence of the molar cushions would significantly affect the biomechanical response of the masticatory system. SignificanceFE analysis is an effective way of investigating biomechanical responses involving complicated interactions. Enriching the static analysis of the masticatory system with a detailed model can help understand better how the forces were transmitted and the significance of TMJs during the clenching process.

THE TECHNIQUE FOR MAKING AESTHETIC ACRYLIC RESIN REMOVABLE PARTIAL DENTURES IN AN ANTERIOR CROSS BITE CASE

Background: Certain cases such as anterior cross bites require a different aesthetic removable denture technique from the conventional removable denture. Purpose: To provide an overview of a case about the technique of making aesthetic acrylic resin removable partial dentures for anterior tooth replacement in cases of anterior cross bite. Case analysis: The study examined the working model with maxillary and mandibular anterior cross bite cases. Result: The arrangement of artificial teeth was carried out as ideally as possible, so that it became harmonious. In this case, the incisal artificial teeth 11, 12, 21 were brought forward labially, so that an edge-to-edge position was formed with the opposing teeth. The clasp made was a half jackson which was placed on teeth 15 and 25, so that when the patient smiles the clasp is not visible to fulfill the aesthetic requirements. Conclusion: The technique of making aesthetic removable partial dentures in cases of anterior cross bite that has received more attention is the arrangement of the dental elements because it is different from the normal tooth arrangement. The artificial teeth were arranged in edge-to-edge bite position in order to obtain a harmonious occlusion while taking into account of the labial arch of the adjacent tooth as well as occlusion with the opposing tooth.

Diagnostic value of routine dental radiographs for predicting the mandibular canal localization validated by cone-beam computed tomogram measurements.

To test the hypothesis that routine dental radiographs can be used to draw conclusions regarding the mandibular canal (MC) localization. MATERIALAND METHODS: A total of 108 radiographs (36 orthopantomograms [OPTs], 36 lateral cephalograms [LCs], and 36 cone-beam computed tomograms [CBCTs]) of 36 patients were analyzed. Statistical analysis included all cephalometric parameters obtained by OPTs, LCs, and CBCTs. Potential influencing parameters were calculated using linear and logistic regression with a backward removal algorithm. For predictability of MClocalization, parameters were correlated using Pearson's correlation. The MCran along the lingual half (n = 24) twice as often as in the buccal half (n = 12) in the population studied. The position was always symmetrical contralaterally. No sex-specific influence was observed (p = .34). Lingual and buccal MCcourses were statistically significantly correlated to increased and decreased jaw angles (LC/OPT), respectively (p = .003; r = -.48/p = .010; r = -.42). An increased jaw angle was significantly correlated with a more cranial MCposition (p = .013; r = -.41); a deep and distal bite position was significantly correlated with a caudal and buccal MCposition (p = .004; r = -.47/p = .001; r = .57). Moreover, an increase of 1 point in the Hasund score predicted an increased probability of a buccal MCposition by 18.6%. The jaw angle analyzed in OPTand LC images were positively correlated (r = .89, p < .001). Routine dental radiographs provide informative guidance on the location of the MCin the vertical and transverse levels. This finding could be used in the initial consultation and treatment planning to consider more invasive diagnostic methods further down the line.

Orthodontic Interceptive Treatment on Obstructive Sleep Apnea Cases

Background: Obstructive sleep apnea (OSA) is a breathing disorder that occurs during sleep and results in decreased or complete cessation of airflow despite attempts to breathe. Specific populations, such as children with certain craniofacial or other genetic syndromes and who are obese have a higher prevalence of OSA than the general population. Craniofacial abnormalities are one of the causes of OSA in the upper airway. Craniofacial morphologies that may predispose to OSA include retrognathia, anterior open bite, midface deficiency, and lower hyoid position. Therefore, interceptive orthodontic treatment in children is needed as one of the treatment options that can be chosen. Purpose: this study aimed to describe the interceptive orthodontic treatments and their effects on OSA cases in children. Review: Interceptive orthodontic treatment has various types depending on how the dentocraniofacial abnormality occurs. Orthodontic treatment aims to reduce the severity of OSA through maxillary and mandibular expansion, thereby increasing air space and airflow. Conclusion: Interceptive orthodontic treatment in pediatric OSA cases include; Rapid Maxillary Expansion, Twin-block, Propulsor Universal Light appliance, Planas appliance modified, Fränkel-II appliance, and BioAJustax oral appliance.

Verification of mechanical load generated by functional orthodontic appliances

Functional appliances are widely used for promoting mandibular growth by utilizing a construction bite position. We aimed to measure the mechanical load generated by movement of functional appliances and determine the factors influencing this load. Thirteen patients aged 8–12 years were selected for the study, and the load was measured using a previously developed measurement device. To investigate the factors affecting the load, the temporomandibular joint morphology and muscles related to the mandible were examined using cone-beam computed tomography. The standard regression coefficients of the factors affecting the load per millimeter of movement distance were 0.64 and 0.66 for (a) the inclination of the articular eminence and (b) the angle between occlusal plane and posterior temporalis, respectively. Measurement of the occlusal plane to the posterior temporalis and the inclination of the articular eminence were significantly different (p < 0.05). The angle of inclination of the articular eminence emerged as a strong influencing factor. Similarly, the influence of measurements from the occlusal plane to the posterior temporalis was considerable since the posterior temporalis muscle is the most active when the mandible is extended forward. We also found a possible relationship between the occlusal force and load at the construction bite position. To our knowledge, this is the first study to determine the actual load associated with the angle of the temporalis muscle to the occlusal plane, inclination angle of the articular eminence, angle between the occlusal plane and the Frankfort plane, and the angle between the geniohyoid muscle and the occlusal plane. Therefore, mechanical considerations need to be more accurate to facilitate safe orthodontic treatment.

Comparing a sibilant phoneme denture bite position with an anterior protrusive mandibular positioning device in oral appliance therapy for dental treatment of obstructive sleep apnea: A systematic review

Comparing a sibilant phoneme denture bite position with an anterior protrusive mandibular positioning device in oral appliance therapy for dental treatment of obstructive sleep apnea: A systematic review

Systematic changes of the static upper body posture with a symmetric occlusion condition

BackgroundTemporary occlusal changes and their influence on the upper body statics are still controversially discussed. Furthermore, concrete statements on whether age- or gender-specific differences in neurophysiological reactions exist are missing. Therefore, it is the aim of this study to evaluate the immediate effects of a symmetrical occlusion blocking on the upper body posture. These effects shall be investigated for both genders and for a larger age range.MethodsIn this study, 800 (407f/393 m) subjects volunteered aged from 21 to 60 years. Both genders were divided into four age groups according to decades. The three-dimensional upper body posture was measured by using the rasterstereography (ABW-Bodymapper). The habitual static posture was measured in two dental occlusion conditions (a) in rest position and (b) symmetrical blocking in the bicuspid region by cotton rolls.ResultsA significant reduction of the trunk length (0.72 mm; p < 0.001), an increase of the lumbar (0.30°; p < 0.001) and the thoracic bending angle (0.14°; p = 0.001), a reduction of the spinal forward decline (0.16°; p < 0.001) and a reduction of the scapular distance (0.36 mm; p = 0.001) was found. Gender-specific reactions can only be recorded in scapular distance, in that regard men reduce this distance while over all age groups women did not show a significant change.DiscussionSlight gender- and age-independent reactions due to a symmetric occlusion blockade are shown: A gender independent reaction of the spinal related variables in the sagittal plane (thoracic and lumbar flexion angle, trunk length, spinal forward decline). In addition, a gender specific change of the shoulder blade distance could be observed, where men reduced the distance while female did not show a change. However, since these reactions are of a minimum amount, it can be concluded that neurophysiological compensation mechanisms work equally well regardless of age and sex, and the upper body posture of healthy people changes only very slightly due to a temporarily symmetrical altered bite position.

Maximum voluntary retrusion or habitual bite position for mandibular advancement assessment in the treatment of obstructive sleep apnoea patients.

There is no consensus on whether the range of mandibular advancement for the construction of mandibular advancement devices in obstructive sleep apnoea (OSA) patients should be measured from a starting position of maximum voluntary retrusion or habitual bite position. The purposes of this study were to investigate the differences in mandibular advancement registrations starting from maximum voluntary retrusion or from habitual bite position and to evaluate the reliability of these assessments. A retrospective cohort analysis of 126 patients with OSA was performed. All patients had their mandibular range of motion evaluated twice (starting from maximum voluntary retrusion and from habitual bite position) through the George Gauge before undergoing drug-induced sleep endoscopy. The Dahlberg formula and paired t test were used to calculate random and systematic errors of dental positions assessment. Test-retest reliability was quantified using the intra-class correlation coefficient (ICC). The mean mandibular range starting from maximum voluntary retrusion and from habitual bite position were 12.49±2.19mm and 7.68±2.29mm, respectively, with a mean distance between the two starting positions of 4.81±1.75mm. No systematic error was found (P>.05), and random errors ranged from 0.30 to 0.95mm. ICC values were excellent for maximum voluntary protrusion (ICC=0.986) and maximum voluntary retrusion (ICC=0.956), whereas habitual bite position showed a good value (ICC=0.818). The difference between maximum voluntary retrusion and habitual bite position is potentially relevant. Maximum retrusion is advisable as starting point of the mandibular advancement registration since it provides a more reliable measure.

The evolution of bite force in horned lizards: the influence of dietary specialization.

Dietary specialization is an important driver of the morphology and performance of the feeding system in many organisms, yet the evolution of phenotypic specialization has only rarely been examined within a species complex. Horned lizards are considered primarily myrmecophagous (ant eating), but variation in diet among the 17 species of horned lizards (Phrynosoma) makes them an ideal group to examine the relationship between dietary specialization and the resultant morphological and functional changes of the feeding system. In this study, we perform a detailed analysis of the jaw adductor musculature and use a biomechanical model validated with invivo bite force data to examine the evolution of bite force in Phrynosoma. Our model simulations demonstrate that bite force varies predictably with respect to the gape angle and bite position along the tooth row, with maximal bite forces being attained at lower gape angles and at the posterior tooth positions. Maximal bite forces vary considerably among horned lizards, with highly myrmecophagous species exhibiting very low bite forces. In contrast, members of the short-horned lizard clade are able to bite considerably harder than even closely related dietary generalists. This group appears to be built for performing crushing bites and may represent a divergent morphology adapted for eating hard prey items. The evolutionary loss of processing morphology (teeth, jaw and muscle reduction) and bite force in ant specialists may be a response to the lack of prey processing rather than a functional adaptation per se.

Experimental and Numerical Characterization of the Mechanical Masseter Muscle Response During Biting.

Predictive simulations of the mastication system would significantly improve our understanding of temporomandibular joint (TMJ) disorders and the planning of cranio-maxillofacial surgery procedures. Respective computational models must be validated by experimental data from in vivo characterization of the mastication system's mechanical response. The present pilot-study demonstrates the feasibility of a combined experimental and numerical procedure to validate a computer model of the masseter muscle. An experimental setup is proposed that provides a simultaneous bite force measurement and ultrasound-based visualization of muscle deformation. The direct comparison of the experimentally observed and numerically predicted muscle response demonstrates the predictive capabilities of such anatomically accurate biting models. Differences between molar and incisor biting are investigated; muscle deformation is recorded for three different bite forces in order to capture the effect of increasing muscle fiber recruitment. The three-dimensional (3D) muscle deformation at each bite position and force-level is approximatively reconstructed from ultrasound measurements in five distinct cross-sectional areas (four horizontal and one vertical cross section). The experimental work is accompanied by numerical simulations to validate the predictive capabilities of a constitutive muscle model previously formulated. An anatomy-based, fully 3D model of the masseter muscle is created from magnetic resonance images (MRI) of the same subject. The direct comparison of experimental and numerical results revealed good agreement for maximum bite forces and masseter deformations in both biting positions. The present work therefore presents a feasible in vivo measurement system to validate numerically predicted masseter muscle contractions during mastication.

Interdisciplinary approach towards full mouth rehabilitation-A case report

Full mouth rehabilitation entails the performance of all the procedures necessary to produce a healthy, esthetic, well-functioning, self-maintaining masticatory mechanism. Full mouth rehabilitation cases are one of the most difficult cases to manage in dental practice. It is basically a set of procedures that are aimed at correcting an improper bite position as well as restoring chipped or worn out teeth. This case report describes a patient with worn-out dention in lower anterior region, bilateral missing of lower posterior teeth and in maxillary arch missing 22, 24.Occlusal rehabilitation done with Pankey Mann Schyuler philosophy. This case reports that a satisfactory clinical result was achieved by restoring the vertical dimension with an improvement in esthetics and function. Keywords: Aesthetic, Masticatory. Tooth Wear; Vertical Dimension, Occlusal Rehabilitation, Face-Bow, Restoration, Worn out Teeth, Function, Philosophy

Biomechanical Evaluation of Different Musculoskeletal Arrangements in Psittacosaurus and Implications for Cranial Function.

The masseter muscle complex is a unique feature of extant mammals and their advanced cynodont precursors, originating from the zygomatic arch and inserting onto the lateral surface of the dentary. This muscle complex is absent in sauropsids, with the exception of the neomorphic m. pseudomasseter complex that is unique to psittaciform birds (parrots and cockatiels). The anterior position and anterodorsally inclined line of action of both muscle groups increases leverage of the jaw and is thought to contribute to increased bite force, particularly in psittaciforms. A corollary is that in mammals at least, the masseter places increased load on the zygomatic arch, which may be withstood by soft tissue temporal fascia. Recently the existence of a m. pseudomasster (mPSM) and m. adductor mandibulae externus ventralis (mAMEV) has been proposed in the ornithischian dinosaur Psittacosaurus. Here we use computed tomography, digital restoration of skull anatomy and adductor musculature and computational biomechanics to test how the presence of anterodorsally inclined muscle loads influences stress, strain, deformation and estimated bite forces in the skull of Psittacosaurus. We find that the m. pseudomasseter and m. amev increases bite force with an associated increase in cranial stress and deformation. There is, however, limited osteological evidence for the existence of these two additional muscles in the psittacosaur skull and geometric morphometric informed sensitivity analysis of our finite element models shows that bite position has a greater effect on loading-induced deformation than muscle loading or material property variation. Anat Rec, 300:49-61, 2017. © 2016 Wiley Periodicals, Inc.

Coxalgia and temporomandibular disorders: a case report

Background: Although the occlusal equilibration in bite plate-induced occlusal position has been reported to be effective in resolving temporomandibular disorder (TMD)-related symptoms, it still remains unclear whether coxalgia is included in those TMD-related symptoms. Method and Findings: Occlusal equilibration was performed for a TMD patient with coxalgia. First, painful symptoms were relieved by appliance therapy. Subsequently, occlusal analysis was performed on the patient by mounting dental models mounted on an articulator and identifying a deviation of the occlusal position from the bite plate-induced occlusal position (BPOP). Occlusal equilibration to the BPOP was performed for the patient by selective tooth grinding. On treatment completion, the occlusal position was shifted 1 mm forward on the left side and 1 mm backward on the right side from the previous habitual occlusal position. The TMD-related symptoms (temporomandibular joint clicking and pain) were resolved, and left coxalgia disappeared. Conclusion: Coxalgia is thought to be included in TMD-related symptoms.

Convergence analysis of a finite element skull model of Herpestes javanicus (Carnivora, Mammalia): implications for robust comparative inferences of biomechanical function.

Predictions of skull biomechanical capability based on virtual models constitute a valuable data source for testing hypotheses about craniodental form and feeding behavior. Such comparative analyses also inform dietary reconstruction in extinct species. 3D modeling using Finite Element (FE) methods is a common technique applied to the comparative analysis of craniodental function in extinct and extant vertebrates. However, taxonomically diverse skull models in the literature often are not directly comparable to each other, in part because of distinctions in how boundary conditions are defined, but also because of substantial differences in the number of FEs composing the models. In this study, we test whether a conventional convergence test is adequate in identifying the minimum number of FEs needed to achieve internally stable results for a single species. We constructed a series of skull models of Herpestes javanicus, and simulated unilateral biting across the dentition; the models differed in the number of FEs, degrees of freedom at the joint and bite point constraints, and type of tetrahedral FEs used. We found that convergence patterns differed across constraint types, FE quantities, and bite position simulated. Four-noded tetrahedral (tet-4) FE models with relaxed constraints produced the most stable measurements compared to over-constrained tet-4 models and to relaxed tet-10 models. In absence of an optimal FE quantity from convergence testing, we propose a broadly applicable sub-sampling protocol, whereby average measurement values across multiple models per specimen are used for among-species comparisons. A regime of sampling three low FE quantity models produced the closest estimates of mean measurement values relative to larger model sets, being within the 95% bootstrap estimated confidence intervals. Future studies should focus on identifying sources of variation associated with other FE modeling protocols, so that they can be accounted for before biomechanical attributes from these simulations are used to infer form-function linkage.

Condylar position assessed by magnetic resonance imaging after various bite position registrations

In this study, we evaluated the reliability and validity of 3 bite registrations in relation to condylar position in the glenoid fossae using magnetic resonance imaging in a symptom-free population. Nineteen subjects, 14 men and 5 women (ages, 20-39 years) without temporomandibular disorders were examined. Three bite registrations were taken and evaluated on each subject: centric occlusion, centric relation, and Roth power centric relation. The differences in condyle position among the 3 bite registrations were determined for the left and right condyles: centric occlusion-centric relation, centric occlusion-Roth power centric relation, and centric relation-Roth power centric relation for each plane of space. The results indicated that (1) all measurements collected had large standard deviations and ranges with no statistical significance, and (2) of the 19 subjects and 38 condyles assessed, 33 condyles (87%) were concentric in an anteroposterior plane. In the transverse anatomic plane, all condyles were concentric. The clinical concept of positioning the condyles in specific positions in the fossae with various bite registrations as a preventive measure for temporomandibular disorders and as a diagnosis and treatment planning tool is not supported by this study.

Condylar Repositioning in Bilateral Sagittal Split Ramus Osteotomy With Centric Relation Bite

Changes in the condylar position after bilateral sagittal split ramus osteotomy (BSSO) can cause many complications, such as condylar dysfunction and increased risk of relapse. This study evaluated a simple approach for condylar repositioning in BSSO as a method to rapidly obtain the patient's centric relation (CR) bite position without prefabricated equipment. The study subjects included 9 patients (5 men and 4 women; mean age, 23.7 years) who underwent BSSO in the Department of Oral and Maxillofacial Surgery in Hallym University hospital between December 2009 and March 2012. We performed BSSO with the condylar-repositioning method according to the patient's CR bite. Measurements of changes in the condylar position via radiographic images (lateral cephalometric radiographs) did not indicate significant differences after surgery (P < 0.05). In surveys of temporomandibular joint symptoms, the scores for categories (sound, pain, mouth opening limitation) also did not show any increases after surgery. Within a standard operating time, the condyle was effectively repositioned using the condylar-repositioning method described in this study. These results indicate this new repositioning method is simple and eliminates the need for any additional device.

The importance of accurate muscle modelling for biomechanical analyses: a case study with a lizard skull

Computer-based simulation techniques such as multi-body dynamics analysis are becoming increasingly popular in the field of skull mechanics. Multi-body models can be used for studying the relationships between skull architecture, muscle morphology and feeding performance. However, to be confident in the modelling results, models need to be validated against experimental data, and the effects of uncertainties or inaccuracies in the chosen model attributes need to be assessed with sensitivity analyses. Here, we compare the bite forces predicted by a multi-body model of a lizard (Tupinambis merianae) with in vivo measurements, using anatomical data collected from the same specimen. This subject-specific model predicts bite forces that are very close to the in vivo measurements and also shows a consistent increase in bite force as the bite position is moved posteriorly on the jaw. However, the model is very sensitive to changes in muscle attributes such as fibre length, intrinsic muscle strength and force orientation, with bite force predictions varying considerably when these three variables are altered. We conclude that accurate muscle measurements are crucial to building realistic multi-body models and that subject-specific data should be used whenever possible.