A New Tridimensional Insight into Geometric and Kinematic Characteristics of Masticatory Cycles in Participants with Normal Occlusion

Abstract

The aim of this study was to analyze the general, geometric, and kinematic characteristics of the masticatory cycle's movements in a tridimensional way, using a method developed by our study group to provide a new insight into the analysis of mandibular movements due to advancement in the potential of computational analysis. Ten individuals (20.1 ± 2.69 years), molar class I, without mandibular movement problems participated in this study. The movements of the masticatory cycles, frontal and sagittal mandibular border movements, were recorded using 3D electromagnetic articulography and processed with computational scripts developed by our research group. The number of chewing cycles, frequency (cycles/s), chewing cycle areas/mandibular border movements areas ratios, and the mouth opening and closing speeds on the 3D trajectory of the chewing cycle were compared. The cycles were divided and analyzed in thirds. The masticatory cycles showed high variation among the individuals (21.6 ± 9.4 cycles); the frequency (1.46 ± 0.21 cycles/s) revealed a moderate positive correlation (R = 0.52) with the number of cycles. The frontal area ratios between the cycle area and the mandibular border movement presented higher values in the first third (6.65%) of the masticatory cycles, and the ratios of sagittal areas were higher and more variable (first, 7.67%; second, 8.06%; and third, 10.04%) than the frontal view. The opening and closing mouth speeds were greater in the second third of the masticatory cycles (OS, 57.82 mm/s; CS, 58.34 mm/s) without a significant difference between the opening and closing movements when the same thirds were evaluated. Further studies are necessary to improve the understanding of the masticatory cycles regarding the standardization of parameters and their values.

Synchronization of surface electromyography and 3D electromagnetic articulography applied to study the biomechanics of the mandible: proof of concept.

“…Our recording method is a novelty in the scienti c literature, and has the advantage of the high accuracy of the movement-recording method demonstrated in previous articles from our research group [22][23][24]. In addition, this synchronization was performed using only the components that already accompany both equipment selected, a fact that besides facilitating its realization and replication, does not add costs to its realization.…”

“…The induced current is analyzed to calculate the spatial position of the sensors [19]. Fuentes et al employed the AG501 articulograph to assess cinematic characteristics of masticatory cycles in healthy participants with normal occlusion tracking the position of an EMA sensor placed in the interincisal midline of the mandible [22][23][24]. Hoke et al employed the Wave articulograph to analyze the micro-movement of dental prosthesis during mastication [25].…”

Mandibular border movements: The two envelopes of motion

“…10,11 Others allow 3D recording of the movements, such as electrognathography and 3D electromagnetic articulography. 5,7,8,12 Among the available techniques, the use of 3D electromagnetic articulography (3D-EMA) allows more natural movements because they do not restrict the movement of the patient's head and it also reach high temporal (up to 1 kHz) and spatial (up to 0.3 mm) precision. 6,8 Three-dimensional EMA has been used to study the characteristics of mandibular border movements and masticatory cycles of asymptomatic participants with normal occlusion.…”

“…6,8 Three-dimensional EMA has been used to study the characteristics of mandibular border movements and masticatory cycles of asymptomatic participants with normal occlusion. 7,8,12 In several studies, the data collected by articulography are digitally processed to obtain several kinematic parameters such as trajectories, displacement ranges and distances. 7,8,12,13 Literature states that beyond mandibular border movement limits, no movement is possible.…”

“…7,8,12 In several studies, the data collected by articulography are digitally processed to obtain several kinematic parameters such as trajectories, displacement ranges and distances. 7,8,12,13 Literature states that beyond mandibular border movement limits, no movement is possible. Therefore, it is of great interest to compare both paths-both eccentric and concentric envelopes of motion-and define the actual limits of mandibular movement.…”