Evolution of Chewing Force in Geriatric Edentulous Patients

Objective The aim of this study was to assess the evolution of chewing force in edentulous geriatric patients rehabilitated with complete dentures. Chewing function is compromised in individuals who lose all their teeth, as well as in those with complete dentures. The maintenance and recovery of the chewing function in these patients require replacement of the lost natural teeth. Materials and Methods In this study, the chewing force was evaluated by electromyographic analysis of the temporalis and masseter muscle endings in 120 patients with old and new bimaxillary complete dentures. Results Replacement of complete dentures was shown to improve stability, retention, occlusion, and support of the prosthesis. All jaw movements were evaluated using electromyography to assess the evolution of chewing force with and without occlusal adjustment, identify premature contact points, identify occlusal interference, respect the balanced occlusal scheme, and assess the increase in muscle strength. This study found that muscle strength in patients with prosthesis without occlusal adjustment was 527.1 N but was higher for prostheses with occlusal adjustment at 614.7 N, and this strength of 614.7 N was maintained after 1 month of control. Conclusion The chewing force evolved in patients with complete dentures, and an increase was observed when occlusal adjustment was performed.

Full mouth rehabilitation for severely worn dentition using fixed prostheses and tooth-supported partial overdenture: a case report.

Rehabilitation of severely worn dentition represents a significant clinical challenge, especially when the restorative space is not sufficient. Creating restorations that fulfil the aesthetic, occlusal and functional parameters are essential to long-term success. This case report describes a 48-year-old male, who had severely worn dentition, which resulted in collapsed vertical dimension. The initial treatment involved careful planning, stabilization of existing dental diseases and construction of provisional prostheses at increased vertical dimension. Once the compatibility of the new vertical dimension had been confirmed, permanent reconstruction was performed. As with all full mouth prosthetic rehabilitation cases, equal-intensity centric occlusal contacts on all teeth and an anterior guidance in harmony with functional jaw movements were critically taken into account in each treatment phases.

Relationship between the Types of Malocclusion and the Localization of Headaches in Adults

The aim of this study was to investigate the manifestations of headaches in adult patients with types of malocclusion and occlusion deformities. Methods and Results: The study was conducted in 171 adult patients (43 men and 128 women) with malocclusion and occlusion deformities at the age of 18 to 62 years old, who were examined in the orthopedic dentistry clinic. The nature of the dentition closing was studied directly in the patient's oral cavity, and with the help of the "Gnatomat" universal articulator on diagnostic plaster models of the jaws. The occlusal relationships of the teeth were analyzed in the position of the central, anterior, lateral and dynamic occlusions. The biomechanics of the lower jaw movements were studied in 3 mutually perpendicular directions. The detected anomalies and deformities of the occlusion were grouped as sagittal, transversal and vertical. Each group was diagnosed as independent forms of malocclusion, and combined with other anomalies and deformities of the dentoalveolar system. All the subjects were asked to answer the questions of a questionnaire specially developed for our study. The unified questionnaire was developed based on a modified rating questionnaire and the determination of the life disorders index in neck pain. The questionnaire includes blocks of questions aimed at identifying the localization of the headache in the temporal, parietal (in one or both) regions, occipital, frontal regions and in the longitudinal seam region. We identified complaints of patients with pain in adjacent regions of the head. Of the 171 examined adult patients with malocclusion and occlusion deformities, 99 (57.9%) complained of headaches. The presence of a headache in the parietal region of the head was associated most often with sagittal and transversal malocclusions. The presence of a headache in the temporal part of the head was associated often with vertical malocclusion The results of correlation analysis showed that pain in 2 regions of the head was associated with malocclusion: the temporal region (rb=0.9892, P=0.0013) and parietal region (rb=0.9712, P=0.0058). Other regions were not statistically significantly associated with malocclusion. Conclusion: There is a certain relationship between the types of malocclusion, occlusion deformities and localization of headaches in adults. Headaches in the parietal and temporal regions of the head are associated with malocclusion and occlusion deformities more often. The obtained data can serve as a basis for the development of recommendations for appropriate corrective measures in orthodontic practice.

Regional tongue deformations during chewing and drinking in the pig

As a muscular hydrostat, the tongue undergoes complex deformations during most oral behaviors, including chewing and drinking. During these behaviors, deformations occur in concert with tongue and jaw movements to position and transport the bolus. Moreover, the various parts of the tongue may move and deform at similar timepoints relative to the gape cycle or they may occur at different timepoints, indicating regional biomechanical and functional variation. The goal of this study is to quantify tongue biomechanics during chewing and drinking in pigs by characterizing intrinsic deformations of the tongue across multiple regions simultaneously. Tongue deformations are generally larger during chewing cycles compared to drinking cycles. Chewing and drinking also differ in the timing of regional length and width, but not total length, deformations. This demonstrates functional differences in the temporal dynamics of localized shape changes whereas the global properties of jaw-tongue coordination are maintained. Finally, differences in the trade-off between length and width deformations demonstrate that the properties of a muscular hydrostat are observed at the whole tongue level, but biomechanical variation (e.g., changes in movements and deformations) at the regional level exists. This study provides new critical insights into the regional contributions to tongue deformations as a basis for future work on multidimensional shape changes in soft tissues.

Effects of low occlusal loading on the neuromuscular behavioral development of cortically-elicited jaw movements in growing rats

The effect of altered occlusal force on masticatory-related neuromuscular control, which projects from the anterior part of the cortical masticatory area (A-CMA), during growth remains unclear. This study sought to evaluate the effect of occlusal hypofunction on neuromuscular development of jaw muscle activities and cortically-induced rhythmic jaw movements (RJMs) in growing rats. Sixty-four 2-week-old male albino Wistar rats were divided into the control (fed normal diet) and experimental (fed soft diet) groups soon after weaning. Electromyographic activity was recorded at 5, 7, 9, and 11 weeks from the right masseter and anterior digastric along with RJMs. We found a significantly longer onset latency and smaller peak-to-peak amplitude in the experimental group than that in the control group. The RJMs showed an increase in gape size and lateral excursion until up to 9 weeks in both groups. However, both the average gape size and lateral excursion were significantly smaller in the experimental group than that in the control group after 9 weeks. The jaw movement pattern also showed a significant decrease at the maximum opening period in the experimental group. Our findings indicate that inadequate occlusal function during growth alters neuromuscular control of masticatory behaviors and impairs the pattern of RJMs.

Jaw kinematics and tongue protraction-retraction during Chewing and drinking in the pig

Mastication and drinking are rhythmic and cyclic oral behaviors that require interactions between the tongue, jaw, and a food or liquid bolus, respectively. During mastication, the tongue transports and positions the bolus for breakdown between the teeth. During drinking, the tongue aids in ingestion and then transports the bolus to the oropharynx. The objective of this study is to compare jaw and tongue kinematics during chewing and drinking in pigs. We hypothesize there will be differences in jaw gape cycle dynamics and tongue protraction-retraction between behaviors. Mastication cycles had an extended slow-close phase, reflecting tooth-food-tooth contact, whereas drinking cycles had an extended slow-open phase, corresponding to tongue protrusion into the liquid. Compared to chewing, drinking jaw movements were of lower magnitude for all degrees of freedom examined (jaw protraction, yaw, and pitch), and were bilaterally symmetrical with virtually no yaw. The magnitude of tongue protraction-retraction (Txt), relative to a mandibular coordinate system, was greater during mastication than drinking, but there were minimal differences in the timing of maximum and minimum Txt relative to the jaw gape cycle between behaviors. However, during drinking, the tongue tip is often located outside the oral cavity for the entire cycle, leading to differences between behaviors in the timing of anterior marker maximum Txt. This demonstrates that there is variation in tongue-jaw coordination between behaviors. These results show that jaw and tongue movements vary significantly between mastication and drinking, which hint at differences in the central control of these behaviors.

Effects of low occlusal loading on the neuromuscular behavioral development of cortically-elicited jaw movements in growing rats

The effect of altered occlusal force on masticatory-related neuromuscular control, which projects from the anterior part of the cortical masticatory area (A-CMA), during growth remains unclear. This study sought to evaluate the effect of occlusal hypofunction on neuromuscular development of jaw muscle activities and cortically-induced rhythmic jaw movements (RJMs) in growing rats. Sixty-four two-week-old male albino Wistar rats were divided into the control (fed normal diet) and experimental (fed soft diet) groups soon after weaning. Electromyographic activity was recorded at 5, 7, 9, and 11 weeks from the right masseter and anterior digastric along with RJMs. We found a significantly longer onset latency and smaller peak-to-peak amplitude in the experimental group than that in the control group. The RJMs showed an increase in gape size and lateral excursion until up to 9 weeks in both groups. However, both the average gape size and lateral excursion were significantly smaller in the experimental group than that in the control group after 9 weeks. The jaw movement pattern also showed a significant decrease at the maximum opening period in the experimental group. Our findings indicate that inadequate occlusal function during growth alters neuromuscular control of masticatory behaviors and impairs the pattern of RJMs.

Spatiotemporal Control of Articulation During Speech and Speechlike Tasks in Amyotrophic Lateral Sclerosis

Purpose This study examined the articulatory control of speech and speechlike tasks in individuals with amyotrophic lateral sclerosis (ALS) and neurologically healthy individuals with the aim to identify the most useful set of articulatory features and tasks for assessing bulbar motor involvement in ALS. Method Tongue and jaw kinematics were recorded in 12 individuals with bulbar ALS and 10 healthy controls during a speech task and two speechlike tasks (i.e., alternating motion rate [AMR], sequential motion rate [SMR]). Eight articulatory features were derived for each participant per task, including the range, maximum speed, and acceleration time of tongue and jaw movements as well as the coupling and timing between tongue and jaw movements. The effects of task (i.e., AMR, SMR, speech) and group (i.e., ALS, control) on these articulatory features were evaluated. For each feature, the task that yielded the largest difference between the ALS and control groups was identified. The diagnostic efficacy of these task-specific features was assessed using the receiver operating characteristic analysis; the relation of these task-specific features to a well-established bulbar severity index—speaking rate—was determined using Spearman's rank correlation. Results Seven task-specific articulatory features were identified, including (a) tongue and jaw acceleration time during the AMR task, (b) tongue–jaw coupling during the SMR task, and (c) range of tongue movement, maximum tongue and jaw speed, and temporal lag between tongue and jaw movements during the speech task. Among these features, tongue and jaw acceleration time and their temporal lag showed relatively high accuracy (i.e., 0.83–0.95) in differentiating individuals with ALS from healthy controls. Range of tongue movement and maximum tongue and jaw speed showed significant correlations with speaking rate. Conclusion Findings provided preliminary evidence for the utility of task-specific articulatory measurements as a novel quantitative assessment to detect and predict bulbar motor involvement in ALS.