Parametric Optimization of Dental Implants

Osseointegration is a fundamental phenomenon of dental implantology. It ensures the stability, the safety and the durability of dental implants and predictable clinical success in long-term. The geometric form of the implant is a defining parameter of osseointegration and implant-bone charge transfer. This is the essential constitutes of this study. In fact, we demonstrate using the finite elements method with tridimensional numerical computations, that the geometrical parameters of the implant conditionate the level and the repartition of the stresses, induced in the cortical bone and the spongy bone during the masticatory process, simulated here by dynamic charging. The effect of several parameters [size and conicity of the implant neck, size and radius of curvature of the implant apex] and the shape of the implant corps on the biomechanical behavior of the bone. The latest was analyzed in terms of variation of the equivalent stress induced in the bone. The purpose of this analysis was the developing of an implant form allowing stress relaxation, during the mastication process, in the living tissue.

Trigeminal Neuralgia, Glossopharyngeal Neuralgia, and Myofascial Pain Dysfunction Syndrome: An Update

Neuropathic pain is a common phenomenon that affects millions of people worldwide. Maxillofacial structures consist of various tissues that receive frequent stimulation during food digestion. The unique functions (masticatory process and facial expression) of the maxillofacial structure require the exquisite organization of both the peripheral and central nervous systems. Neuralgia is painful paroxysmal disorder of the head-neck region characterized by some commonly shared features such as the unilateral pain, transience and recurrence of attacks, and superficial and shock-like pain at a trigger point. These types of pain can be experienced after nerve injury or as a part of diseases that affect peripheral and central nerve function, or they can be psychological. Since the trigeminal and glossopharyngeal nerves innervate the oral structure, trigeminal and glossopharyngeal neuralgia are the most common syndromes following myofascial pain dysfunction syndrome. Nevertheless, misdiagnoses are common. The aim of this review is to discuss the currently available diagnostic procedures and treatment options for trigeminal neuralgia, glossopharyngeal neuralgia, and myofascial pain dysfunction syndrome.

VIDEOFLUOROSCOPIC EVALUATION OF SWALLOWS IN ANOREXIA NERVOSA

ABSTRACT Background There are some studies in the literature about the feeding behavior and masticatory process in patients with feeding disorders; however, it is not very well known if there are alterations in oral-pharyngeal swallowing dynamics in subjects with anorexia nervosa. Objective To evaluate the oral and pharyngeal bolus transit in patients with anorexia nervosa. Methods The study was conducted with 8 individuals clinically diagnosed and in treatment for restricting-type anorexia nervosa (seven women and one man), and 14 healthy individuals with no digestive or neurological symptoms (10 women, 4 men). Swallows were evaluated by videofluoroscopy with three swallows of 5 mL liquid bolus and three swallows of 5 mL paste bolus consistency, given in a random sequence. The participants were asked after each swallow about the sensation of the bolus passage. Results In the analysis of oral-pharyngeal transit duration, the mean duration of pharyngeal transit with paste bolus in patients with anorexia was shorter than in healthy volunteers (P=0.02). In the duration of movement of the hyoid bone, longer movement was observed in anorexia than in healthy volunteers with liquid bolus (P=0.01). With liquid bolus, five (62.5%) patients and one (7.1%) control had sensation of the bolus passage (P<0.05). Conclusion There seems to be no important alterations of swallowing in subjects with anorexia nervosa, although the results suggest that pharyngeal transit has shorter duration than that seen in healthy volunteers and the hyoid movement duration is longer in patients than in healthy volunteers. Fast pharyngeal transit may be the cause of bolus transit perception in patients with anorexia nervosa.

Review: the Use of Electromyography on Food Texture Assessment

Sensory evaluation (SE) involves evoking, measuring and interpreting human responses to the properties of foods. Among these properties texture is an important one for food acceptability. Texture is mainly perceived through mastication, a process that changes food characteristics throughout time by comminuting and salivation. Electromyography (EMG) has emerged as a new tool in sensory evaluation mainly for assessing texture characteristics. Thus, it is interesting to analyze the knowledge so far generated and the procedures employed. Bipolar surface electrodes are placed on the four main masticatory muscles (masseter right-left and temporalis right-left) and their electric activity recorded during mastication. The signals need to be amplified and filtered, and afterwards their acquisition by a computer allows conditioning and analysis. The output is a series of bursts corresponding to the chews during mastication. EMG parameters include the area under the curve (linked to masticatory work) and voltage (linked to the force exerted) at different moments of the process. Many other parameters are derived from the recording and related to food texture characteristics. EMG allows the study of changes throughout the masticatory process, these changes in EMG parameters permit a better assessment of sensory characteristics than mechanical measurements. Nevertheless, close-fitting correlations have been found between sensorymechanical-EMG measurements. In the literature, texture assessment by using EMG includes many products like carrots, biscuits, cooked meat, cooked rice, cheese, etc., as well as different texture characteristics like tenderness, hardness, crunchiness, juiciness, among others. Nowadays, texture studies involving EMG are mainly linked to describing changes or differences in the signals, good descriptors of perceived differences. Nevertheless for quantifying purposes, in order to allow comparisons among authors, a first step should be undertaken to standardize EMG parameters definition and procedures used in SE.