Preferred Side Research Articles

Primary hemifacial spasm: anatomical insights.

Primary Hemifacial Spasm (pHFS) is a disorder caused by compression of vessels on the root of the facial nerve. There has been conflicting evidence regarding the side of the face that is more frequently affected. Moreover, it has been found in several studies that women are afflicted by approximately twice as many as men. We reviewed the literature to explain HFS tendencies from an anatomical aspect. We wanted to see whether there are anatomical variations that can increase the risk of developing HFS or underlie its tendency to a specific gender and side of the face. A PubMed search was done for the articles on "Hemifacial Spasm" published in English literature, and we selected the articles regarding the significant anatomical differences in HFS patients. AICA proximal branching pattern, highly originated PICA, VA dominancy, and VA deviation are among the predisposing anatomical variances. Overall, both sides of the face are equally affected in HFS. However, there are side preferences based on the causative vessels, which may be due to differences in the anatomical features of the left and right side vessels. Various anatomical variations regarding posterior circulation can increase the risk of HFS. Recent evidence suggests whether there is no side dominance or a tendency exists toward the left side. There is no comprehensive explanation for precise reasons underlying the tendency of HFS to affect women. Evidence regarding anatomical variations of the posterior circulation comparing men and women with HFS is scarce, and further studies are required.

The relationship between facial directional asymmetry, handedness, chewing side preference, and eyedness

We aimed to describe facial directional asymmetry (DA) in individuals with different manifestations of laterality. Due to the overlap between brain and face development, a relationship between the manifestation of brain laterality and DA is hypothesised. These findings could clarify the relationship between the brain and facial phenotype and help to plan facial or oral motor rehabilitation. The DA of 163 healthy individuals was assessed by two complementary 3D methods: landmark and polygonal surface analysis using colour-coded maps. Handedness was assessed using the Edinburgh Handedness Inventory, while chewing side and eye preferences were self-reported. The results showed a similar DA pattern regardless of sex and laterality (the right-sided protrusion of the forehead, nose, lips, and chin) and a slightly curved C-shape of the midline in landmark analysis. A relationship between lateralized behaviours and DA was found only in males, in females the DA pattern was more homogenous. Right-handed individuals and right-side chewers showed a protrusion of the right hemiface. Males, left-handed and left-side chewers, manifested a protrusion of the left lateral hemiface. We suggest that these specific differences in males may be due to their typically higher level of brain asymmetry. No apparent relationship was found between eyedness and DA.

Perforator Selection with Computed Tomography Angiography for Unilateral Breast Reconstruction: A Clinical Multicentre Analysis.

Background and Objectives: Despite CTAs being critical for preoperative planning in autologous breast reconstruction, experienced plastic surgeons may have differing preferences for which side of the abdomen to use for unilateral breast reconstruction. Large language models (LLMs) have the potential to assist medical imaging interpretation. This study compares the perforator selection preferences of experienced plastic surgeons with four popular LLMs based on CTA images for breast reconstruction. Materials and Methods: Six experienced plastic surgeons from Australia, the US, Italy, Denmark, and Argentina reviewed ten CTA images, indicated their preferred side of the abdomen for unilateral breast reconstruction and recommended the type of autologous reconstruction. The LLMs were prompted to do the same. The average decisions were calculated, recorded in suitable tables, and compared. Results: The six consultants predominantly recommend the DIEP procedure (83%). This suggests experienced surgeons feel more comfortable raising DIEP than TRAM flaps, which they recommended only 3% of the time. They also favoured MS TRAM and SIEA less frequently (11% and 2%, respectively). Three LLMs-ChatGPT-4o, ChatGPT-4, and Bing CoPilot-exclusively recommended DIEP (100%), while Claude suggested DIEP 90% and MS TRAM 10%. Despite minor variations in side recommendations, consultants and AI models clearly preferred DIEP. Conclusions: Consultants and LLMs consistently preferred DIEP procedures, indicating strong confidence among experienced surgeons, though LLMs occasionally deviated in recommendations, highlighting limitations in their image interpretation capabilities. This emphasises the need for ongoing refinement of AI-assisted decision support systems to ensure they align more closely with expert clinical judgment and enhance their reliability in clinical practice.

Comparative study of multidirectional pedestrian flows: Insights and dynamics

This study investigates multidirectional pedestrian flow by examining walking characteristics and behavioral factors impacting pedestrian dynamics. Parameters such as mean walking velocities, distance covered, and time taken by pedestrians were analyzed. Contrary to the expected inverse relationship between velocity and density, our findings revealed an increase in mean velocities in certain scenarios, attributed to conditions where the pedestrian density had not reached its maximum possible level and unpredicted pedestrian behaviors. Comparative analysis revealed that both Pakistani and Chinese pedestrians walk at nearly similar speeds. For instance, Pakistani pedestrians maintain a mean velocity of 1.36 ± 0.42 m/s at a density of 0.48 ped/m², while Chinese pedestrians maintain 1.27 ± 0.23 m/s at a density of 0.41 ped/m². Behavioral characteristics such as aggressive behavior, crowd avoidance, and waiting behavior were identified, with aggressive pedestrians exhibiting higher velocities than those avoiding crowds. A space-time diagram was utilized to categorize pedestrian flow types and behaviors, demonstrating increased stopping times with higher pedestrian numbers. Cultural factors, including side preferences, were analyzed using a binomial test, which returned a p-value of 0.968, indicating no significant preference for right-hand movement among Pakistani participants. These insights enhance the understanding of pedestrian dynamics and the influence of cultural norms on movement efficiency.

Frequency and variability of nonmetric dental crown traits of primary and permanent molars in agroup of orthodontic patients.

The present study aimed to assess the frequency and variation of 13nonmetric dental crown traits (NDCT) in permanent and primary molars in German orthodontic patients. Dental records from orthodontic patients were screened and evaluated. First and second permanent and primary upper and lower molars (from left and right sides) were assessed. Teeth with cavitated dental caries, occlusal wear, restorations and obvious dental deformities were not evaluated. The NDCT for permanent molars were identified and scored according to the odontoscopic system developed by Arizona State University Dental Anthropology System (ASUDAS). The NDCT for primary molars were identified and scored according to ASUDAS, Hanihara's method and Sciulli's method. The χ2 test was used to investigate side preference and sexual dimorphism at asignificance level of p ≤ 0.050. Atotal of 163 orthodontic patients (82males and 81females) aged 8-14years were included. Asexual dimorphism was observed for the hypocone in first upper permanent molar (p = 0.041). The protostylid was observed in lower permanent molars (range 2.1-10%). Males presented more hypoconulid than females (p = 0.019). Only females presented the distal trigonid crest in lower first permanent molars (p = 0.002). The most common groove pattern in primary molars wasY; male presented more Ygrade than females in the lower second primary molar (p = 0.039). Asymmetry was observed in some traits, ranging from 0 to 100%. The present study showed the frequency of NDCT of molars in German orthodontic patients and demonstrated that some traits present sexual dimorphism.

Should I Just Stick to the Wall? Evaluating the Social Acceptance and Preferred Driving Side of Wall Following

The need for safe, predictable, and reliable robot navigation is fundamental for mobile robots to move around in home and office environments. Shortest-path navigation is a popular robot navigation method that uses the most efficient path to get to the desired goal. This behaviour is not always easy to interpret, understand, and avoid in a congested hallway. Instead, more predictable navigation methods, such as a robot following a wall, can help increase social acceptance and help avoid the robot crossing the pedestrian path. If a robot follows along a wall, a key variable to consider is the preferred driving side of the robot (left or right) in areas such as in narrow passages, and its perceived impact on social acceptance. This international user study (n = 143) involved an online video-based test to compare robot evaluation and social acceptance for two types of mobile navigation (Wall-Following and Shortest Path), including the preferred driving side for Wall-Following. A Fetch robot navigated from start to goal position in a series of indoor scenarios with a pedestrian. Select scenarios included a hallway, doorway, and intersection. Independent Sample T-Tests results found that Wall-Following was rated significantly higher than Shortest Path for being perceived as more comfortable and predictable, regardless of robot driving side. The preference for the driver side of the robot did not match the country of residence, nor did it have a significant impact on robot ratings. There were significant interaction effects for comfort, safety and predictable scores across two timepoints. Given the popularity of Shortest Path navigation, the findings indicate that this approach might not be the most appropriate for human settings. Additional investigation into Wall-Following behaviours is recommended for social acceptance, even if the method compromises the efficiency of the robot to acheive its objective.

Mandible Position and Chewing Preference Side Do Not Alter Plantar Support in Children Aged 4-11 Years.

Mandible positioning can cause global postural adaptations. Physiotherapists and dentists try to relate the mandible position and chewing side to plantar support; however, this indication is uncertain. To check the existence of a relationship between mandible position, preferred chewing side, age, and plantar support in children. This is a cross-sectional study with 93 children, aged between 4 and 11 years. Photogrammetry was used to confirm the mandibular positions (centralized, to the right, and to the left), and baropodometry was used to measure plantar support. The mandibular displacement distance to the right and left was evaluated, and the plantar support in the three mandibular positions was compared as a function of age (4-7 and 8-11 years) and preferred chewing side. There was greater mandibular displacement in left laterality [13 (9-19) cm] compared to right laterality [7 (3.50-12.00) cm] (p < 0.01). Mandibular position did not alter mean pressure, maximum pressure, or plantar support surface (p > 0.05). With the mandible centralized, higher mean pressure, maximum pressure, and surface area were observed in the left foot (p < 0.01). Older children showed greater mandibular displacement to the left (p < 0.01). No differences were observed for the variables of plantar support as a function of age (p > 0.05) and chewing side (p > 0.05). There was a moderate to strong correlation between age, body mass, height, and plantar surface area (0.63 < r < 0.83; p < 0.05) and between mean and maximum pressures of plantar support (0.58 < r < 0.89; p < 0.05). Mandibular position, age, and preferred chewing side do not influence plantar support in children. Bittar KCB, Zamboti CL, Macedo CSG. Mandible Position and Chewing Preference Side Do Not Alter Plantar Support in Children Aged 4-11 Years. Int J Clin Pediatr Dent 2024;17(6):658-664.

Mandibular overdenture with a single implant in the canine region (c-SIMO): a feasibility study

ObjectivesThe aim of this multi-center pilot study was to assess the viability and feasibility of a novel treatment concept – the canine-positioned single implant mandibular overdenture (c-SIMO), with the single implant placed on the patient's preferred chewing side instead of the midline.Materials and methodsParticipants received a single implant in the canine region of their preferred chewing side, based on an Asymmetry Index observed during mastication. The pre-existing mandibular denture was transformed into a c-SIMO on a spherical attachment. The primary outcome was oral health-related quality of life (OHRQoL), measured with GOHAI and OHIP-EDENT. Secondary outcomes included denture satisfaction index (DSI), chewing efficiency (CE), maximum bite force (MBF), implant survival and success, and prosthetic maintenance. Data analysis included descriptive statistics and bivariate comparison tests.ResultsFifteen participants received the c-SIMO treatment (mean age: 69.9 ± 7.0). Implant success and survival rates were 100% at 1 year. Patient-reported outcome measures improved significantly compared to pre-treatment values (OHIP-EDENT: p = 0.001; DSI: p = 0.001; GOHAI: p = 0.002). Masticatory outcomes also improved significantly (CE: p = 0.001; overall MBF: p = 0.005). Post-implant, MBF was significantly higher in the ipsilateral side compared to the contralateral side at 2 weeks (p = 0.019) and 3 months (p = 0.015), but no longer at T3 (p = 0.730). Common prosthodontic events included denture base adjustments (n = 17) and matrix activation (n = 9).ConclusionsThis pilot study concludes that c-SIMO is a promising treatment option, and a potential alternative to the single midline implant overdenture.Clinical relevanceThe novel treatment concept of a canine-positioned single implant mandibular overdenture could be a viable treatment alternative to the midline positioning.

Short Communication: Lateralised lungefeeding behaviour in Southern Hemisphere fin whales at Antarctic feeding grounds

Balaenopterids use dynamic feeding lunges to capture prey, often performing roll manoeuvres which may demonstrate a side preference or laterality. In this study, we use aerial video footage of fin whales (Balaenoptera physalus) feeding at Elephant Island, Antarctica, to investigate laterality in the Southern Hemisphere fin whale subspecies B. p. quoyi. Right‐biased lateralisation was observed in all 63 recorded side lunges, 57 of which displayed visible lunge directions, the majority being clockwise (98.3%). These results complement existing information on lateralised feeding behaviour in Northern Hemisphere fin whales, confirming a strong right‐sided bias across the different fin whale subspecies.

Contributions of Alveolar Bone Density and Habitual Chewing Side to the Unilateral Failure of Orthodontic Mini-Screws: A Cross-Sectional Study

This study aimed to analyze the relationship between bone density, habitual chewing side (HCS), and mini-screw stability to investigate the intra-individual factors contributing to mini-screw failure. This retrospective study included 86 sides in 43 adults, who underwent bilateral maxillary mini-screw placement with subsequent unilateral failure of the mini-screw. Pre-treatment cone-beam computed tomography was used to measure the buccal cortical bone thickness and bone density on the failed and successful sides. Pre-treatment mandibular kinesiographic records were used to determine the HCS. Paired t-tests, one-proportion z-tests, and multivariable multilevel Poisson regression were used to examine the statistical significance. The buccal cortical bone thicknesses were 0.93 ± 0.27 mm (unsuccessful side) and 1.01 ± 0.27 mm (successful side), with no significant difference. The bone density on the unsuccessful side (1059.64 ± 202.64 mg/cm3) was significantly lower than the success side (1317.89 ± 332.23 mg/cm3). Regarding HCS, 27.9% of failures occurred on the preferred side, and 62.8% occurred on the non-preferred side. After adjusting for all factors, the non-preferred side showed a 2.22 times higher prevalence ratio for mini-screw failure than the preferred side. HCS is significantly related to mini-screw stability, while the cortical bone thickness, bone density, and site of mini-screw implantation were not correlated.

Effect of breathing conditions on relationships between impairment, breathing laterality and coordination symmetry in elite para swimmers.

The aim was to investigate the effect of breathing conditions and swimming pace on the relationships between the impairment, the breathing laterality and motor coordination symmetry in elite front crawl Para swimmers. Fifteen elite Para swimmers with unilateral physical impairment or with visual impairment and unilateral breathing preference performed eight 25m using four breathing conditions (every three strokes, every two strokes on preferred and non-preferred breathing side and apnea) at slow and fast paces in a randomized order. Multicamera video system and five sensors have been used to assess arm and leg stroke phases and to compute symmetry of arm coordination (SIIdC) and of leg kick rate (SIKR). Our findings emphasized motor coordination asymmetry whatever the breathing conditions and swimming paces, highlighting the influence of impairment. Multinomial logistic regression exhibited a high probability for motor coordination asymmetry (SIIdC and SIKR) to be present in categories of Para swimmers with impairment and breathing laterality on the same side, suggesting the joined effect of unilateral impairment and unilateral breathing. Moreover, unilateral physical impairment and breathing laterality could also occur on different sides and generate motor coordination asymmetry on different sides and different levels (arms vs. legs). Finally, visual impairment seems amplify the effect of unilateral breathing on motor coordination asymmetry.

The biomechanical effects of bimaxillary osteotomies to the patients with mandibular retraction under incisal clenching.

The purpose of this study is to investigate the biomechanical effect of bimaxillary osteotomies on patients with mandibular retraction. Mandibular retraction, as a typical maxillofacial deformity, and has great adverse effects on TMJ. Bimaxillary osteotomies are widely used to correct symptoms of mandibular retraction. It is necessary to understand the effect of surgery on temporomandibular disc (TMJ). Five patients with mandibular retraction and 10 asymptomatic subjects were involved in this study. Finite element models of preoperative, postoperative and control group were constructed based on the CT data. Nine sets of concentrated forces were used to simulate the muscle effect and contact method was used to simulate the interaction within the TMJs and dentitions. The results showed that bimaxillary osteotomies could effectively improve the maxillofacial morphology and alleviate the overload in TMJ. The facial asymmetry and right chewing side preference could cause imbalanced stress distributions in the TMJs and interfere the surgical treatment.

Rare Absent Right Common Carotid Anomaly: Case Report and Current Information

This case report provides a review of the occurrence, variations, signs/symptoms, and gender/side preferences of an absent common carotid artery (CCA) anatomical variant. Normal embryology of the carotid arteries and associated structures are also discussed. The relationship between absent common carotid bifurcations and the risk for plaque development is also considered but is limited due to the lack of empirical evidence. This report also outlines and demonstrates an absent right CCA with direct, separate origins of the right external carotid artery and right internal carotid artery from the right subclavian artery. An absent CCA is a rare vascular anomaly with multiple variations. There are typically no associated signs/symptoms, and there are no gender or side preferences.

Opioid-Sparing Effects of IV Acetaminophen for Patients Undergoing Surgery

What Is the Issue?&#x0D; &#x0D; Opioids are often used to help manage postoperative pain. However, their consumption can cause side effects, in addition to the risk of developing dependence with long-term use.&#x0D; Acetaminophen is an alternative analgesic that may provide opioid-sparing benefits for patients undergoing surgery (e.g., the need for patients to use opioids later), but there is a lack of synthesized evidence to confirm. Acetaminophen is available in different formulations, such as IV, oral, and rectal. However, there is uncertainty around the benefits of using 1 formulation over another perioperatively.&#x0D; &#x0D; What Did We Do?&#x0D; &#x0D; To inform decisions about IV acetaminophen, we sought to identify and summarize literature comparing the effectiveness of IV acetaminophen to alternative analgesics (i.e., nonsteroidal anti-inflammatory drugs [NSAIDs]), alternative formulations (i.e., oral or rectal acetaminophen), or placebo for reducing opioid consumption in patients undergoing surgery.&#x0D; A research information specialist conducted a literature search of peer-reviewed and grey literature sources published between January 1, 2019, and January 9, 2024. The search was limited to English-language documents. One reviewer screened articles for inclusion based on predefined criteria. To investigate the true effect of IV acetaminophen, we excluded studies with any intraoperative opioid use.&#x0D; &#x0D; What Did We Find?&#x0D; &#x0D; For adult patients undergoing elective hip surgery, there may be no significant differences in cumulative opioid use between postoperative IV and oral acetaminophen (1 randomized controlled trial).&#x0D; For patients undergoing elective cesarian delivery, postoperative IV acetaminophen may result in a decrease in total morphine consumption after surgery compared to placebo (1 randomized controlled trial).&#x0D; For adult patients undergoing lumbar disc surgery, there may be no significant differences in total morphine consumption for patients receiving intraoperative IV acetaminophen compared to placebo (1 systematic review with 1 relevant RCT).&#x0D; We did not find any studies comparing the opioid-sparing effects of IV acetaminophen to NSAIDs that met our criteria for this review.&#x0D; &#x0D; What Does It Mean?&#x0D; &#x0D; Limited evidence from this review suggests that the opioid-sparing effect of IV acetaminophen may vary across types of surgery when compared to placebo. Additionally, IV acetaminophen may not offer additional opioid-sparing benefits compared to oral administration. However, we require more comprehensive research with rigorous methodological approaches to understand this topic better.&#x0D; Relative to opioids, IV acetaminophen has a preferable side effect profile, including a low risk of dependence; therefore, decision-makers may wish to consider using this formulation in the surgical or postsurgical setting.&#x0D;

Secondary cavitation bubble dynamics during laser-induced bubble formation in a small container.

We investigated secondary cavitation bubble dynamics during laser-induced bubble formation in a small container with a partially confined free surface and elastic thin walls. We employed high-speed photography to record the dynamics of sub-mm-sized laser-induced bubbles and small secondary bubble clouds. Simultaneous light scattering and acoustic measurements were used to detect the oscillation times of laser-induced bubbles. We observed that the appearance of secondary bubbles coincides with a prolonged collapse phase and with re-oscillations of the laser-induced bubble. We observed an asymmetric distribution of secondary bubbles with a preference for the upstream side of the focus, an absence of secondary bubbles in the immediate vicinity of the laser focus, and a migration of laser-induced bubble toward secondary bubbles at large pulse energies. We found that secondary bubbles are created through heating of impurities to form initial nanobubble nuclei, which are further expanded by rarefaction waves. The rarefaction waves originate from the vibration of the elastic thin walls, which are excited either directly by laser-induced bubble or by bubble-excited liquid-mass oscillations. The oscillation period of thin walls and liquid-mass were Twall = 116 µs and Tlm ≈ 160 µs, respectively. While the amplitude of the wall vibrations increases monotonically with the size of laser-induced bubbles, the amplitude of liquid-mass oscillation undulates with increasing bubble size. This can be attributed to a phase shift between the laser-induced bubble oscillation and the liquid-mass oscillator. Mutual interactions between the laser-induced bubble and secondary bubbles reveal a fast-changing pressure gradient in the liquid. Our study provides a better understanding of laser-induced bubble dynamics in a partially confined environment, which is of practical importance for microfluidics and intraluminal laser surgery.

Laterality in Body Coordination of Professional and Amateur Ballet Dancers While Performing a Single Pirouette with Pointe Shoes.

Imbalances in muscle strength coordination owing to lateral preference may be a risk factor for injury in dancers. Postural control is essential for the basic turn in ballet (pirouette), owing to its lateral asymmetry. Since dance with pointe shoes demands greater range of motion, muscle strength, and balance control compared to dancing with flat shoes, pointe shoes may further add to the risk and cause an imbalance between the preferred and non-preferred legs during pirouette. In this study, we examined lateral differences in professional and experienced amateur ballet dancers during single pirouettes with pointe shoes to understand the multiple elements involved in lateral balance control in pirouettes. Eight female professionals and seven female amateur ballet dancers performed single pirouettes in pointe shoes on both the preferred and non-preferred sides. To understand the body coordination laterality in single pirouettes, statistical parametric mapping was performed for the trunk, hip, knee, ankle angle, and center of mass-center of pressure inclination angle timeframe data during the pirouette in three phases: turn with double-leg (Phase 1), single-leg (Phase 2), and finish turning with a single-leg (Phase 3). In addition, the hop-up time was calculated as the percentage when the foot is not in contact with the ground in Phases 2 and 3. There were no lateral differences in trunk and lower limb angles in either group. Professional dancers showed slightly more inclination towards the stance leg during left rotation at the beginning of the movement (Phase 1) with longer hop-up time in Phase 2, whereas amateur dancers tended to tilt forward during the left turn (Phases 1 and 2) with longer hop-up time in Phase 3. It is notable that the COP-COM inclination angle was adjusted by hop-up and it caused the lateral differences in both professional and amateur dancers during a single pirouette with pointe shoes. This study highlights elements to consider in laterality when monitoring pirouette performance with pointe shoes.

Application of Gale-Shapley algorithm in optimal matching for healthcare facilities to elderly population: the case of Hangzhou, China

ABSTRACT This paper serves as the first empirical research applying the Nobel Prize winning Gale-Shapley algorithm to study optimal stable matching of healthcare facilities to elderly population living in residential neighbourhoods in main urban districts of Hangzhou, China. Through bilateral considerations of supply side attributes of healthcare facilities and demand side preferences of elderly population, this research shows that the Gale-Shapley matching is superior to unilateral spatial or non-spatial utility matching and can optimize stable matching for elderly population in a way similar to the Pareto optimal. Further, this study provides a conceptual model classifying urban spaces for healthcare services at various levels.

Chewing Side Preference Related to Food Texture and Occlusal Contact Area.

To determine whether food texture affects chewing side preference (CSP) and to investigate the relationship between CSP and masticatory factors, such as occlusal contact area, bite force, and masticatory performance. Forty-seven adults (20 women and 27 men; mean age: 24 years) participated in this study. Three types of food (chewing gum, beef jerky, and peanuts) were provided to assess CSP. Occlusal contact area was measured at various ranges of interocclusal distance, and the bite force was measured. Masticatory performance was assessed according to the median particle size. Asymmetry indices of each measurement were calculated and analyzed using Pearson correlation coefficient (α &#61; .05). The CSP for beef jerky and peanuts were significantly correlated with each other, whereas the CSP for chewing gum was not correlated with other food. The proportion of participants who chewed equally on both sides was higher for chewing gum than for beef jerky. There was a significant correlation between the CSP for beef jerky and occlusal contact area, especially at interocclusal distance ranges of 0 to 89 μm and 0 to 109 μm (r &#61; 0.41). Bite force and masticatory performance were not significantly correlated with CSP. Food texture seemed to affect CSP, and masticatory laterality was greater for tough foods. Moreover, CSP for tough food was closely related to the occlusal contact area at an interocclusal distance level of about 0.1 mm.

Age-related difference in oral adaptation to masticatory perturbation

ObjectivesMastication can be influenced by intraoral perturbation (e.g., hard food). We developed the masticatory perturbation task (MPT) to assess the perturbation effect during mastication and quantify the degree of adaptation to masticatory perturbation in younger and older adults. DesignThirty-eight younger and 38 older participants completed the MPT, which consisted of three trials assessing masticatory performance (MP) without perturbation (i.e., the baseline condition) and three trials assessing MP with perturbation (i.e., the perturbation condition). Perturbation was implemented by concurrently chewing test food on the preferred side and a drinking straw on the nonpreferred side. We estimated the perturbation effect as the ΔMP between the baseline and perturbation conditions and the adaptation effect as the ΔMP between the third and the first trials for both age groups. ResultsWe found a significant perturbation effect, i.e., a lower MP in the perturbation condition than in the baseline condition, and an adaptation effect, i.e., a higher MP in the third trial than the first trial, in both groups. Moreover, the older group showed a lower degree of adaptation than the younger group. ConclusionThe masticatory perturbation task revealed the perturbation effect during mastication and the adaptation to masticatory perturbation. The results revealed an association between age and masticatory adaptation.

Effect of Dental Characteristics of Stroke Patients on the Masticatory System*

Aim: The aim of this study was to assess the interplay between central facial paralysis and dental characteristics for impaired mastication in sub-acute or chronic-stage stroke patients. Method: 20 stroke patients and 27 healthy individuals were included in the study. Oral health, oral hygiene, masticatory efficiency, central facial paralysis, and forward head posture of the participants were assessed by OHIP-14 questionnaire, a self-prepared questionnaire, a two-colored chewing gum test, labial commissure, and craniocervical angle measurements. Stroke characteristics and dental characteristics were also assessed. Results: The sociodemographic and physical characteristics of both groups were similar (p&amp;gt;.05). The dental characteristics of the stroke patients were significantly poor compared to healthy individuals (p&amp;lt;.05). Masticatory efficiency of the stroke patients was nearly half that of the healthy individuals (p&amp;lt;.05). The forward head posture and facial paralysis values of both groups were similar (p&amp;gt;.05). Conclusion: Our study showed that central facial paralysis gradually loses its effect on impaired mastication in stroke patients and gives its place to dental characteristics. Masticatory muscle activation and increasing postural adaptations like forward head posture may not be preferred by stroke patients. The preferred mastication side might be used to assess the severity or existence of central facial paralysis in stroke patients.