Comparative study using video analysis and an ultrasonic measurement system to quantify mandibular movement

Chewing Analysis by Means of Electromagnetic Articulography: Current Developments and New Possibilities

Chewing is a complex procedure that involves sensory feedback and motor impulses controlled by the trigeminal system in the brainstem. The analysis of mandibular movement is a first approximation to understanding these mechanisms. Several recording methods have been tested to achieve this. Video, ultrasound, the use of external markers and kinesiographs are examples of recording systems used in research. Electromagnetic articulography is an alternative method to those previously mentioned. It consists of the use of electromagnetic fields and receiver coils. The receiver coils are placed on the points of interest and the 3D coordinates of movement are saved in binary files. In the Oral Physiology Laboratory of the Dental Sciences Research Center (Centro de Investigación en Ciencias Odontológicas-CICO), in the Faculty of Dentistry at the Universidad de La Frontera (Temuco, Chile) several research studies have been carried out using the AG501 3D EMA articulograph (Carstens Medizinelektronik, Lenglern, Germany). With this device, they developed a series of protocols to record mandibular movement and obtain new information, such as the 3D Posselt polygon, the area of each polygon, individualized masticatory cycles and speed and acceleration profiles. Other investigations have analyzed these parameters, but separately. The AG501 allows for holistic analysis of all these data without altering natural movement. A limitation of this technology is the interference generated by its metallic elements. The aim of the present work is to show the developed methods used to record mandibular movement in the CICO, using the AG501 and compare them with others used in several research studies.

Changes in Maximum Mandibular Mobility Due to Splint Therapy in Patients with Temporomandibular Disorders

Splint therapy is widely used in the treatment of myofascial pain, but valid studies on the efficacy of this therapy are rare. The purpose of the present study was to investigate which qualifiable and quantifiable effects of splint therapy are detectable. For this purpose, 29 patients (21 women, mean age 44.6 ± 16 years) diagnosed with myofascial pain (RDC/TMD) were investigated in this prospective clinical trial (10/6/14An). Patients were treated with Michigan splints applied overnight for three months. Before (T1) and after three months of treatment (T2), patients were registered with an electronic ultrasound device with qualitative and quantitative evaluation of the registrations and a qualitative assessment of pain symptoms using a verbal analog scale. Significant differences were found between maximum mouth opening (MMP) (p < 0.001) and right condylar movement (CM) at MMP (p = 0.045). Qualitative assessment revealed that 24 of 29 patients experienced an improvement in pain symptoms, 17 of whom experienced complete remission. The results of the qualitative and quantitative analysis provide indications of the effectiveness of the splint therapy. In addition to quantitative measurements, the ultrasound facebow technique was also able to provide qualitative information.

Mandibular border movements: The two envelopes of motion

BACKGROUND

The envelope of motion is a diagrammatic representation of the mandibular border movements. Classically, those movements are carried out eccentrically; starting from the position of maximal intercuspation, the mandible describes an excursion movement until reaching maximal mouth opening. Reverse movements would describe a different path, but up to now concentric development of mandibular border movements has not been considered. Literature states that beyond mandibular border movements limits, no movement is possible. Therefore, it is of great interest to compare both paths-both envelopes of motion-and define the actual limits of mandibular movement.

OBJECTIVE

The aim of this study was to compare the geometric characteristics of mandibular border movements carried out eccentrically and concentrically by healthy subjects.

METHODS

Sixteen individuals aged between 18 and 27 years, molar class I and with no temporomandibular disorders, participated in the study. Eccentric and concentric mandibular movements were recorded using a 3D electromagnetic articulograph. Data were processed with computational scripts developed in MATLAB. Maximum mouth opening, trajectories, displacement ranges, polygon areas and chewing cycle area/ mandibular border movements area ratio were analysed.

RESULTS

The frontal plane showed significant differences in all the parameters evaluated. Higher values were registered in the concentric area of the border movement envelope (P = .008) and in the trajectories on both sides. Statistical differences were observed in polygon areas (P = .006) in the sagittal plane and right ranges (P = .046) in the horizontal plane.

CONCLUSION

Concentric mandibular movements revealed significant differences in three-dimensional trajectories in the frontal plane.

Assessment of early orthodontic treatment on functional shifts by telemonitoring mandibular movements using a smart phone

Introduction

To assess effect of orthodontic treatment on anterior or lateral functional shift in mixed dentition stage by telemonitoring mandibular movements in four-dimensions using a novel objective method that can assist in orthodontics and other dental specialties without the need of expensive, bulky or complicated equipment.

Methods

A sample of 60 patients was divided into two groups. Group I included 30 patients with normal occlusion and TMJ functions. Group II included 30 patients that were diagnosed with an abnormal path of closure in antero-posterior or transverse directions due to disharmony between centric occlusion and centric relation. The latter group was orthodontically treated and mandibular movements were measured before, during, directly after orthodontic treatment, and one year after treatment using our proposed method. To evaluate validity and reliability of our method, it was compared with two methods, a commercially available mandibular scanner, and a low-cost graphical method that utilizes a sheet of wax and a stylus.

Results

It was found that the overall differences between opening and closing curves of our proposed method and the other two methods were small and negligible (p > 0.05).

Discussion

It was found that our proposed method is offering a reasonably accurate, simple and rapid way to telemonitor the mandible movements in four-dimensions using the rear/front camera of any smart-phone.