Masticatory properties in pre-modern Holocene populations from Northern China.

Recent studies indicate that evolution of the craniofacial skeleton is influenced by dietary behavior, which in turn alters masticatory efficacy and temporomandibular joint (TMJ) stability. In this study the mechanical properties of the masticatory system and the integrity of the TMJ in human populations from Northern China, dated to between 3800 BCE and 100 CE, were assessed. The results demonstrate that the mechanical efficiency is comparable to other modern human populations, though variations are present across different populations. While the ratio of overall weighted muscle efficiency for incisor loading vs. molar loading in pastoral and some recent agricultural groups is similar to early Homo sapiens, the ratio in more ancient agricultural groups is similar to the ratio in populations with heavy anterior paramasticatory activities, such as Neandertals, Inuits, and Native Americans. The TMJ vulnerability negatively correlates with the maxillary dental arch size, and positively with the condylar size. These findings suggest that there are multi-directional strategies in adaptation to heavy anterior teeth loading, such as increasing anterior teeth loading efficiency, increasing facial height, increasing facial breath and facial orthognathy, or decreasing anterior facial length. Furthermore, populations or individuals with a smaller dental arch and high biting efficiency could more easily injure the TMJ during unilateral loadings, which may explain the higher prevalence of TMJ disorders in modern humans, especially in women. These findings further reflect the impact of diachronic changes of the masticatory apparatus and lifestyle and their impact on oral health during recent human history.

Evidence - The intraoral palpability of the lateral pterygoid muscle - A prospective study.

The intraoral palpability of the inferior caput of the lateral pterygoid muscle has been a matter of ambiguity because of its topography. Thus, none of the recently published studies has provided reliable proof of the possibility of digital intraoral palpation, although palpation of the muscle is part of most of the examination catalogs for clinical functional analysis and functional therapy. Digital muscle palpation was performed intraorally on five preparations after exposure of the infratemporal fossa and visualization of the lateral pterygoid muscle. Direct digital palpation of the lateral pterygoid muscle was seen in all five cases. The successful palpation was carried out and approved during laterotrusion to the examined side (relaxation). While opening and closing the mouth (contraction) the muscle is palpable. In real-time kinematic measurements (MRI) an impression of the lateral caput of the left lateral pterygoid muscle of a 30-year-old control male person was found up to 6mm. Electromyographic detection by direct signal conduction with concomitant palpation is possible. The injection electrode tested in situ in the muscle was felt transorally with the palpating finger. The intraoral palpability of the inferior caput of the lateral pterygoid muscle is verified. The basic requirement for successfully palpating the lateral pterygoid muscle is the exact knowledge of muscle topography and the intraoral palpation pathway. After documented palpation of the muscle belly in cadaverous preparations, MRI and EMG also visualized palpation of the lateral pterygoid muscle in vivo. The palpation technique seems to be essential and basically feasible.

Cadaveric validation of dry needle placement in the lateral pterygoid muscle.

OBJECTIVE: The aim of this anatomical study was to determine if a needle is able to reach the lateral pterygoid muscle during the application of dry needling technique. METHODS: A dry needling approach using 2 needles of 50 to 60 mm in length, one inserted over the zygomatic process posterior at the obituary arch (for the superior head) and other inserted below the zygomatic process between the mandibular condyle and the coronoid process (for the inferior head), was proposed. A progressive dissection into 3 stages was conducted into 2 heads of fresh male cadavers. First, dry needling of the lateral pterygoid muscle was applied on the cadaver. Second, a block dissection containing the lateral pterygoid was harvested. Finally, the ramus of the mandible was sectioned by osteotomy to visualize the lateral pterygoid muscle with the needle placements. RESULTS: With the needles inserted into the cadaver, the block dissection revealed that the superior needle reached the superior (sphenoid) head of the lateral pterygoid muscle and the inferior needle reached the inferior (pterygoid) head of the muscle. At the final stage of the dissection, when the ramus of the mandible was sectioned by osteotomy, it was revealed that the superior needle entered into the belly of the superior head of the lateral pterygoid muscle. CONCLUSIONS: This anatomical study supports that dry needling technique for the lateral pterygoid muscle can be properly conducted with the proposed approach.

Injeção de sangue autógeno no tratamento da luxação recidivante da articulação temporomandibular / Autologous blood injection for treatment of recurrent mandibular dislocation

A articulação temporomandibular (ATM) é uma articulação complexa com características e funções únicas. Certamente é uma das articulações mais utilizadas e seu uso inadequado e excessivo consequentemente promove inúmeros transtornos. Dentre as alterações de hipermobilidade articular, o deslocamento mandibular refere-se ao posicionamento, geralmente anterior, do côndilo mandibular sobre a eminência articular, com completa separação das superfícies articulares e consequente travamento. Quando os episódios se tornam frequentes, algum método de tratamento, seja conservador ou cirúrgico, deve ser utilizado, devido ao grande transtorno funcional e social gerados. A injeção de sangue autógeno na articulação temporomandibular é uma técnica minimamente invasiva, com escassos relatos na literatura e que foi recentemente reintroduzida. Onze pacientes diagnosticados com luxação recidivante da articulação da cabeça mandibular receberam injeções bilaterais de sangue autógeno no compartimento articular superior e região pericapsular. Em acompanhamento, que variou de 24 a 35 meses (média de 29,6 meses), 3 (27,3%) pacientes apresentaram recidivas. O mesmo protocolo de tratamento foi repetido para estes três casos, porém sem sucesso, sendo então encaminhados para procedimento cirúrgico de eminectomia. Dessa forma, dos 11 pacientes inicialmente tratados, 8 (72,7%) não apresentaram episódios de deslocamento mandibular recorrente após o procedimento proposto. Trata-se de um procedimento simples, rápido, pouco invasivo, de baixo custo e com mínima possibilidade de complicações, sendo uma alternativa de tratamento viável, antes de se indicar procedimentos cirúrgicos

The temporomandibular joint (TMJ) is a complex joint with unique features and functions. It is certainly one of the most used joints and its improper and excessive use consequently promotes numerous breakdowns. Among the changes of joint hypermobility, the mandibular displacement refers usually as an anterior displacement of the condyle on the articular eminence with complete separation of the articular surfaces and consequent locking. When episodes become frequent, some method of treatment, either conservative or surgical, should be used, because of the functional and social disturbances. The injection of autologous blood in the temporomandibular joint is a minimally invasive technique, recently reintroduced. Eleven patients diagnosed with recurrent mandibular dislocation received bilateral injections of autologous blood in the upper joint compartment and pericapsular region. In follow-up ranging from 24 to 35 months (mean 29.6 months), 3 (27.3%) patients had recurrences. The same treatment protocol was repeated for these cases without success and were taken to surgical eminectomy. Thus, of the 11 patients initially treated, 8 (72.7%) didn’t show any episode of recurrent mandibular dislocation after the proposed procedure. It is a simple, quick, minimally invasive procedure, with low cost and with minimal possibility of complications making a viable alternative treatment before recommending surgical procedures

The relationship between dental occlusion/temporomandibular joint status and general body health: part 2. Fascial connection of TMJ with other parts of the body.

In part 1 of this study, it was discussed that dental occlusion/temporomandibular joint (TMJ) status is functionally connected to general body health. The purpose of this part of the study was to attempt to formulate a conceptual account, the "fascial connection theory for TMJ and other parts of the body," to explain the functional connection between TMJ and other parts of the body. The first hypothesis that was studied is that TMJ and other parts of body are connected through the fascia as asserted by the myofascial-release schools, and the second one is that they are connected through the meridian system constituted of fascia (connective tissue). The fascial connection theory proposed here can explain the functional connection between dental occlusion/TMJ and other parts of the body based on either myofascial release or the qi and meridian system, or a combination of the two. Therefore, dental occlusion should be built up and maintained in a normal natural condition, and causes of deterioration of TMJ status should be treated in an effort to restore the natural condition. Other possible mechanisms that can account for these connections require elucidation, and additional experimental investigation should be undertaken.

Neuromuscular diagnosis in orthodontics: effects of TENS on the sagittal maxillo-mandibular relationship.

AIM: This study was conducted in order to assess the changes in the occlusal position of the mandible after ULF (Ultra Low Frequency)-TENS relaxing procedure in subjects in pubertal growth phase with diagnosed Angle Class II division 1 and mandibular dentoalveolar retrusion. MATERIALS AND METHODS: This study was performed on 19 patients (13 females, 6 males) with an Angle Class II division 1, aged between 10 and 15 years old (mean age 12.26, SD 1.32), characterised by mandible dentoalveolar retrusion and optimal vertical facial dimension, diagnosed by clinical and cephalometric evaluation. Diagnostic neuromuscular registrations were made for all subjects. The casts were mounted on articulator in habitual intercuspal position with a tooth-guided wax bite registration. Reference points were chosen at molar level. Subsequently the same casts were mounted in myocentric position and compared to the habitual intercuspal position, assessing the sagittal shift after TENS procedure. STATISTICS: Mean and standard deviation were calculated on the amount of shifting at the left molar reference point after TENS procedure. Analysis of variance (ANOVA), using STATA statistics package, was carried out in order to evaluate the influence of sex and age on the amount of molar shift. RESULTS: Nine subjects showed, in the sagittal plane, a forward mandibular shift in neuromuscular myocentric position compared to habitual intercuspal position. Six subjects showed no differences between habitual and myocentric position in the sagittal plane. Four individuals showed a backward mandible shift after TENS indicating worsening of the II molar class in the sagittal plane. CONCLUSION: This study suggests that TENS recorded occlusion in subjects with Class II division 1 with mandible dentoalveolar retrusion allows to visualise an unusual trend of growth. The advancements of the mandible were not taken into account. These results could offer new diagnosis and prognosis methods for Class II malocclusions.

Otalgia e desordens temporomandibulares / Otalgia and temporomendibular disorders

A correlação entre manifestações otológicas e desordens temporomandibulares tem sido um assunto de grande pesquisa e controvérsia na literatura. Dentre os sintomas otológicos relatados por pacientes portadores de DTM, a otalgia merece destaque por sua importância clínica como queixa do paciente. Algumas explicações da base anatômica e fisiológica tentam elucidar esta correlação, porém muitas são refutadas e desconsideradas. Apesar da polêmica e das diversas teorias sobre o assunto, realizou-se uma revisão da literatura sobre as possíveis explicações para a sensação de otalgia, muitas vezes relatada por pacientes que apresentam desordens temporomandibulares

Animating functional anatomy for the web.

The instructor sometimes has a complex task in explaining the concepts of functional anatomy and embryology to health professional students. However, animations can easily illustrate functional anatomy, clinical procedures, or the developing embryo. Web animation increases the accessibility of this information and makes it much more useful for independent student learning. A modified version of the animation can also be used for patient education. This article defines animation, provides a brief history of animation, discusses the principles of animation, illustrates and evaluates some of the video-editing or movie-making computer software programs, and shows examples of two of the author's animations. These two animations are the inferior alveolar nerve block from the mandibular nerve anesthetics unit and normal temporomandibular joint (TMJ) function from the muscles of the mastication and the TMJ function unit. The software discussed are the industry leaders and have made the job of producing computer-based animations much easier. The programs are Adobe Premiere, Adobe After Effects, Apple QuickTime and Macromedia Flash .

Chiropractic manipulation of anteriorly displaced temporomandibular disc with adhesion.

OBJECTIVE: This AB, single-subject case study was conducted to investigate the capability of chiropractic manipulation of the temporomandibular joint (TMJ) in treating unilateral anterior displacement of the articular disc with adhesion to the articular eminence. A specific joint manipulation was designed to reduce the anteriorly displaced and adhered TMJ disc. CLINICAL FEATURES: A 21-yr-old woman suffered from a four year history of right-sided temporomandibular joint pain and clicking, with limitation of mandibular opening. The patient reported previous unsuccessful treatments for her condition. An exhaustive history, a complete review of systems and a physical examination (including, but not limited to, eyes, ears, nose, throat and motor, sensory and reflex neurological tests) were obtained. Relevant or contributory findings are extracted for this article. A clinical diagnosis of left-sided anteriorly displaced TMJ disc with adhesion to the articular eminence was made. INTERVENTION AND OUTCOME: Patient's pain level, presence of joint clicking upon mandibular opening and the amount of mandibular opening were used as outcome measures for capability of treatments. An AB, single-subject study was used where A was the baseline period and B the therapeutic intervention period. The patient was treated twice a week for a total of 19 visits. During the baseline period no treatment was given to the TMJ (3 visits) where the patient received cervical manipulation alone. During the experimental period the patient received both cervical spine manipulation and a specific manipulation to the left mandible. There were no physical therapeutic modalities applied to the jaw. The specific TMJ manipulation used requires a very low-amplitude high velocity thrust parallel to the slope of the articular eminence. The results of this study show mandibular opening distance was returned to normal in addition to the abolition of the patient's TMJ pain and clicking. During the three baseline visits mandibular opening showed no significant change, with an average of 25.3 mm (range 25-26 mm). There was also no change in the patient's TMJ pain or clicking during this baseline period. The patient's TMJ clicking was absent following the third treatment and the patient reported significant subjective pain relief as well. Temporomandibular pain was again reported during the fifth, sixth and seventh post-treatment visits due to exacerbations caused by daily activities. There was no pain reported from the beginning of the eighth post-treatment visit to the end of the study. CONCLUSION: The findings of this study show this specific manipulation of the TMJ may be appropriate for the conservative treatment of adhered anteriorly dislocated disc.

A technique to investigate the three-dimensional kinesiology of the human temporomandibular joint.

Previous kinesiological studies of the temporomandibular joint (TMJ) were based on the motion of only one or two selected points on the mandible (such as the lower central incisor, the mandibular condyle). In the present study, a technique was developed to measure, analyze, and describe the full three-dimensional kinematic characteristics of the TMJ during any mandibular activity. The technique was based on determination of the relative position between the mandible and the temporal bone from measurement of the location of points on light-weight frames rigidly attached through splints to the maxillary and mandibular teeth. An optoelectric kinematic data acquisition system has been used to record the location of these points. The results of the study indicate the following major advantages of this technique over previously reported kinesiological methods: (1) the technique provides a full description of the motion of the mandible with respect to the temporal bone, including all the six degrees of freedom associated with this motion; (2) the description of motion in terms of joint parameters enhances interpretation of the data by clinicians; (3) the motion of any point of interest on the mandible can be easily derived from the data and; (4) the system provides only negligible interference with the natural jaw motion of the subject. It does not require head fixation, does not alter or interfere with the natural occlusion, and its light weight causes only minimal (and negligible) loading of the mandible.

The diagnosis and treatment of the dislocated mandible.

Dislocation of the mandible occurs commonly. Most patients present to the emergency department for treatment. This article discusses the normal temporomandibular joint (TMJ) anatomy and the etiology, types, and diagnosis of mandibular dislocation. It also describes the initial management, including techniques for reduction of the acute anteriorly dislocated mandible.

Relationships between mandibular joint size and craniofacial size in human groups.

Substantial evidence attests to the capability of the joint to undergo morphological alteration in response to biomechanical forces transmitted to it during function. Measurements expressing the size of mandibular condyles and fossae were obtained from skulls representative of a broad spectrum of subsistence practices and tooth use. Craniofacial dimensions were measured for some groups. Considerable differences in joint size were noted between groups roughly consistent with known or presumed intensity of masticatory stress. Size was largest in the hunter-gatherers, intermediate in aboriginal horticulturalists and smallest in 20th century American caucasoids and 17th century British. In each group, male joint size was absolutely larger than females. With the exception of condylar breadth, male joint dimensions were not relatively larger than female when corrected for differences in craniofacial size. In contrast, same-sex comparisons of Eskimo and American caucasoid means adjusted for differences in craniofacial size showed joint size in Eskimos to be significantly larger, both absolutely and relatively. Eskimo females had relatively larger joints than American caucasoid males. Thus, intergroup differences in joint size persist even when differences in craniofacial size are taken into account. Although the influence of genetic factors cannot be excluded, differences in the nature or intensity of tooth use during growth may account, at least in part, for the observed differences in joint size.

The influence of the loss of teeth and attrition on the articular eminence.

A review of the literature revealed that changes in the articular eminence associated with changes in the dentition were usually overlooked in most reports. An attempt was made to determine whether changes in attrition and loss of teeth would correlate with a change (decreased angulation) in the articular eminence. The population consisted of 103 adult skulls and mandibles of both sexes and three different races. They included partial and totol edentulism, mild to severe attrition, and complete dentitions in good condition. An impression of each of the 206 articular eminences was made and the angulation established. The data were transferred to computer cards and a statistical analysis performed. The level of significance for each of the variables was established and conclusions were made.

Tooth attrition and the temporomandibular joint.

1. It is thought the differences shown to exist between the unworn sample and the worn sample would have been clearer if the criteria for the classification of worn had been more severe. Examination of the ranges of measurements would make one suspect some subjects suffered dental attrition to a degree that no enamel was left on the occlusal surfaces of the third molars without showing damage elsewhere. The author did not feel competent to assess third molars that had not only lost all their occlusal enamel but also one mm of dentin, so was unable to make his worn classification more stringent. Again the reader is reminded that broeken down or "worn out" dentitions were specifically excluded from the samples...