Bite Force Research Articles

Effect of Oral Function Training on Swallowing Function in Community-Dwelling Older Individuals

Background: Dry mouth, masticatory discomfort, and swallowing in older individuals are important factors affecting overall health. To improve their quality of life, efforts are required to improve their oral function. Therefore, this study implemented a training program evaluating oral function to confirm improvements in swallowing. Methods: The study was conducted for approximately 4 months, from Jul to Oct 2023. Participants aged 65 yr or older were selected from welfare facilities in the metropolitan region, with 24 participants in both the intervention and control groups. Results: As a result of a study conducted on oral function training program, the intervention group exhibited significant improvements in the simulated swallowing flow rate (P <0.05), bite force (P <0.001), and tongue pressure (P <0.001). Conclusion: The oral function training program effectively improved simulated swallowing flow rate, bite force, and tongue pressure. Consequently, there is an opportunity to implement oral function training programs at accessible welfare centers for older individuals in the community.

Quantitative Comparison of Age-Related Development of Oral Functions During Growing Age.

This cross-sectional study aimed to investigate the age-related development of five major oral functions-tongue pressure, lip pressure, masticatory efficiency, bite force, and occlusal contact area-in subjects aged 5-20 years. Ninety-two subjects were divided into four age groups: 5-8, 9-12, 13-16, and 17-20 years. Oral functions were evaluated using standardized methods, including Chew Check Gum for assessing masticatory efficiency, Dental Prescale II for measuring occlusal force and contact area, JMS tongue pressure measuring device for evaluating tongue pressure, and Ripple-Kun for measuring lip pressure. Occlusal contact area, maximum bite force, tongue pressure, and masticatory efficiency gradually increased with age, whereas lip pressure remained stable. The occlusal contact area temporarily decreased between 5 and 12 years of age, likely due to the replacement of erupting lateral teeth. Some differences were observed between males and females; however, overall trends in oral function parameters were similar. Spearman's rank correlation analyses revealed significant positive correlations between age and occlusal contact area, bite force, tongue pressure, and masticatory efficiency. Oral function parameters exhibited different age-related development patterns. Occlusal contact area, maximum bite force, tongue pressure, and masticatory efficiency gradually increased with age. Interestingly, the occlusal contact area tended to reduce temporarily between 5 and 12 years of age due to the replacement of erupting lateral teeth. Conversely, lip pressure was almost stable during this period. Our findings provide valuable insights into the developmental patterns of oral functions during the growing years.

Synthesis of SrZnOSe Crystals with Low Phonon Energy for Enhancing Near-Infrared Mechanoluminescence.

Near-infrared (NIR) light is promising for bioimaging and information technology due to its high penetration ability and resistance to interference with environmental radiation. Here, a new class of lanthanide-doped SrZnOSe crystals are developed for the self-sustainable generation of NIR emissions under mechanical excitation. It is shown that the SrZnOSe crystals render ≈5-fold stronger NIR emissions than the well-established CaZnOS due to the low phonon energies of the selenide host, as confirmed by Raman spectroscopy. The potential utility of the crystals is demonstrated by integration with a mouthguard, which can generate bright NIR emissions by bite force to transmit encrypted optical signals through thick tissues (up to 8mm) in ambient environments. The findings provide a powerful addition to the toolbox of self-recovery mechanoluminescent materials and open new possibilities for applied research.

Relationship between tooth macrowear and jaw morphofunctional traits in representative hypercarnivores.

The mammalian adult dentition is a non-renewable resource. Tooth attrition and disease must be accommodated by individuals using behavioral, physiological, and/or musculoskeletal shifts to minimize impact on masticatory performance. From a biomechanical perspective, the musculoskeletal system becomes less efficient at producing bite force for a given amount of muscle input force over an individual's life, because tooth-food contact area increases as cusps wear. In this study we ask the question: does mandibular biomechanical performance show evidence of compensation with increasing tooth wear? We use representative taxa of three carnivoran ecomorphologies (meat specialist, scavenger, bone cracker) as a study system to compare morphofunctional data on tooth macrowear, jaw depth, bite mechanical efficiency, and jaw stress during biting. No significant shifts in adult mandibular corpus dimensions occurs in the sampled taxa as canine and carnassial teeth wear. In bone cracking spotted hyenas carnassial biting mechanical efficiency increases significantly with increasing tooth wear, with no significant change in mandibular stress. Analyses of the fossil carnivore Hyaenodon suggests an increase in canine biting efficiency with increased tooth wear, but this may reflect interspecific variation or phylogenetic contingency rather than a life history shift. Overall, these findings indicate that scavenging hyaenids and felid meat specialists do not exhibit morphofunctional compensation for the decreased mechanical capability of worn and dull teeth. Behavioral modifications, rather than musculoskeletal adjustments, may instead play a major role in maintaining food acquisition and processing capabilities for individuals surviving into advanced ontogenetic age and tooth wear. These observations highlight the mammalian masticatory system as having a dynamic performance profile through its useful lifespan, and encourage a more nuanced understanding of past and present carnivore guilds by considering wear-dependent performance changes as a possible source of selection.

Evaluation of patient satisfaction and maximum biting force of three differently constructed bars on two implants retaining mandibular overdenture - one year follow-up (a randomized controlled clinical trial)

BackgroundDifferent bar construction techniques will affect the bar passive fitness, which may induce stresses or strain on the implant and/or tightening screw and sequentially may affect the biting force and patient satisfaction.Aim of the studyThis clinical investigation assessed patient satisfaction and maximum biting force (MBF) using three differently constructed (conventional casting, milling, and 3D printing CAD/CAM techniques) cobalt-chromium (Co-Cr) bar-retained implants mandibular overdentures over a one-year period of follow-up.Materials and methodsThirty edentulous patients seeking for two implants bar-retained mandibular overdentures were randomly assigned into three groups as the following: Group I: 10 patients received a Co-Cr conventional casting bar, Group II: 10 patients received a Co-Cr CAD/CAM milled bar, and Group III: 10 patients received a Co-Cr CAD/CAM 3D-printed bar. All the bar groups were connected to two implants in the canine area bilaterally. Within the first two weeks following implant placement, patients received the definitive prosthesis. Patient satisfaction was evaluated by using the (OHIP-EDENT-19) questionnaire form after 6, and 12 months. Additionally, the maximum biting force was tested at after delivery, 3, 6, and 12 months for each group. The results were collected, tabulated, and statistically analyzed. Trial registration: This study was recorded on ClinicalTrials.gov retrospectively registered (ID: NCT06401187) on 30/04/2024.ResultsAfter one year follow up, regrading patient satisfaction the three groups showed no statistically significant difference. Although, the functional limitation domain was in favor of the milled bar. Regarding the maximum biting force, no statistically significant difference was found among three groups. However, at 12 mouths follow-up the milled bar showed statistically value.ConclusionWithin the limitations of this study, the conventional, milled and 3D printed bar overdentures groups can be used as a satisfactory treatment modality for edentulous mandible in terms of patient satisfaction and maximum biting force.

Comparison of Postorthodontic Occlusal Force Distributions between Nonextraction and Extraction Treatment Approaches of Premolars for Orthodontic Treatment by Using T-Scan III System.

To compare bite force distributions in corresponding mouth regions between postorthodontic patients who underwent nonextraction and extraction approaches using the T-Scan III system (Tekscan, Inc, Massachusetts, United States). Thirty-six postorthodontic patients were divided into two groups: (1) 18 subjects with the nonextraction treatment and (2) 18 subjects with the extraction of four first-premolar treatments. The measurements were performed using the T-Scan to collect the occlusal bite force at the maximal intercuspal position to generate the bite force in the anterior region (incisors and canines) and posterior region (premolars and molars), the bite force in individual teeth, and the anteroposterior bite force ratio (A-P ratio). The mean bite force in each region, individual teeth, and the A-P ratio were compared between the two groups by the Mann-Whitney's U-tests. Within-group comparisons of the mean bite force in each region were performed using Wilcoxon's signed rank tests. The bite force in anterior and posterior regions, and the A-P ratio of the nonextraction group show no significant difference compared with the extraction group (p > 0.05). For individual teeth (central incisors, lateral incisors, canines, second premolars, first molars, and second molars), each tooth exhibited nonsignificantly different bite forces (p > 0.05) except for the second molars. The second molars in the nonextraction group had significantly less bite force than in the extraction group (p = 0.001). The comparison of occlusal bite force between the right and left sides showed that in the nonextraction group, the right side had significantly greater force (p < 0.05). In the extraction group, there was no significant difference between the sides (p > 0.05). Both nonextraction and extraction orthodontic treated patients exhibited the similar bite force distribution patterns in regions and individual teeth except for the higher occlusal force on the second molars in the extractions compared with the nonextractions.

Three-dimensional finite element analysis of occlusal stress on maxillary first molars with different marginal morphologies restored with occlusal veneers

BackgroundThere are differences in the research results regarding which edge design of occlusal veneers can achieve the best long-term success rate as a relatively new fixed prosthesis restoration method. Further research is needed. The three-dimensional finite element method was used to conduct stress analysis on occlusal veneers of maxillary first permanent molars with different thicknesses and margin preparation designs. The aim of this study was to provide mechanical research evidence and a reference for exploring standardized clinical protocols for the design of occlusal veneer restorations of maxillary first molars.MethodA 3Shape (Intraoral Scanner) was used to scan the maxillary first molar teeth in vitro, after which 3D printing was carried out. Three different edge designs were applied to identical teeth: straight-beveled finishing line(SFL), chamfer finishing line(CFL), and standard cuspal inclination(SCI). Preparation was carried out with a thickness of 0.5 mm. Using the surface deformation feature, the occlusal veneer was thickened to 0.5 mm and 1.0 mm, and periodontal ligaments were added. They were then placed into the upper and lower jaws and dental arches. Finite element analysis was performed after applying bite force dispersion to the loading area on the mandible following dynamic contact.Results(1) As the thickness increased, the maximum Von Mises stress in the occlusal veneers SFL and CFL also increased, while the SCI exhibited the opposite trend. (2). The trend of the maximum Von Mises stress in the adhesive layer decrease gradually with increasing thickness of the occlusal veneer. The stresses of the SFL and CFL is concentrated primarily at the edge position below the functional cusp, resulting in relatively low adhesive stress. However, in the SCI group, the maximum stress at the edge of the adhesive layer exceeds the maximum shear strength of commonly used adhesives.ConclusionsUnder the experimental conditions, the mechanical properties of the maximum Von Mises stress in the SFL, CFL, and SCI occlusal veneers meet clinical needs. Incorporating the minimally invasive concept of tooth preservation, a thickness of 1.0 mm are optimal for glass ceramic occlusal veneers on maxillary first molars.

Functional and Character Disparity Are Decoupled in Turtle Mandibles.

Turtles have high shape variation of their mandibles, likely reflecting adaptations to a broad variety of food items and ingestion strategies. Here, we compare functional disparity measured by biomechanical proxies and character disparity measured by discrete morphological characters. Functional and character disparities vary between clades and ecological groups and are thus decoupled. Comparisons with cranial disparity also indicate decoupled patterns within the turtle skull. Exploration of mandibular patterns reveals that several biomechanical configurations or character state combinations can lead to the same feeding type (i.e., convergence) or that high functional disparity can be achieved at a low exhaustion of character state combinations (e.g., cryptodires). Dietary specialists show larger functional disparity than generalists, but the phylogenetically widespread generalist ecology leads to high character disparity signals in the ecotype. Whereas character disparity generally shows high phylogenetic signal, functional disparity patterns correspond to dietary specializations, which may occur convergently across different groups. Despite this, individual functional measurements have overlapping ranges across ecogroups and do not always conform to biomechanical expectations. Jaw opening and closing biomechanical advantages model trade-offs between force transmission and opening/closing speeds, and turtles show a variety of combinations of values that we try to synthesize into several "jaw types". Closing mechanical advantage shows that turtles retain high levels of force transmission at the anterior jaw end compared with other groups (e.g., pseudosuchians). This can possibly be explained as an evolutionary adaptation to retain high bite forces at small head sizes.

Reliability, reference values and factors related to maximum bite force measured by the Innobyte system in healthy adults with natural dentitions

ObjectivesWe aimed to determine the predictors of maximum bite force (MBF), as measured with the Innobyte system, and to assess the reliability and reference values for MBF in young adults with natural dentitions.MethodsThis cross-sectional test–retest study included 101 dental students with natural dentitions. Participants had their dental occlusion examined and completed three questionnaires: the Temporomandibular disorders Pain Screener, Oral Behavior Checklist, and Jaw Functional Limitation Scale. Body mass index and muscle mass percentage were determined, and handgrip strength was measured with a dynamometer. The MBF was measured with Innobyte, with reliability assessed by the intraclass correlation coefficient, expressing reference values as MBF percentiles. Bivariate tests and multiple linear regression models were used for statistical analysis.ResultsThe intraclass correlation coefficient for the MBF was 0.90, with 10th to 90th percentiles of 487–876 N for females and 529–1003 N for males. A positive relationship existed between the MBF and male sex, muscle mass percentage, overbite, handgrip strength, and possible sleep/awake bruxism. Stepwise regression showed that overbite, handgrip strength, and possible sleep/awake bruxism had the greatest effect on the MBF, explaining 27% of the variation.ConclusionsThis study provides reference values for MBF when using the Innobyte system and shows excellent reliability. Overbite, general strength, and self-reported bruxism appear to be important predictors of MBF.Clinical relevanceInnobyte is a reliable device that can be used to measure MBF bilaterally. Self-reported bruxism is associated with an 8%–10% increase in MBF.

Facial and dental arch shape in individuals with different bite force levels : A pilot study using geometric morphometrics.

This pilot study aimed to assess the relationship between bite force variation and dental arch and facial shape using geometric morphometrics, an advanced method of statistical analysis that provides adetailed shape analysis of astructure considering the spatial relationship of its parts. The sample consisted of 16German adult men and women. For each individual, maximum bite force was recorded in four positions: maximum intercuspation, protrusion, laterotrusion to the right and to the left. Facial and three-dimensional (3D) dental reconstructions were obtained from 3D facial photographs and 3D scans of dental stone models. Atotal of 51landmarks were placed. General shape variation was assessed by principal component analysis. Partial least squares analyses were performed to evaluate the covariation between bite force, facial shape, and dental shape. There was no clear pattern or statistically significant covariation between our variables. Our results suggest aweak relationship between bite force, dental arch, and facial shape. Considering previous work in this field, we propose that low masticatory loads, characteristic in Western urban populations, may explain this. Further studies should, therefore, address this issue, taking into account effect size, the mechanical properties of the diet, and other relevant variables.

Tooth eruption status and bite force determine dental microwear texture gradients in albino rats (Rattus norvegicus forma domestica).

Dental microwear texture analysis (DMTA) is widely applied for inferring diet in vertebrates. Besides diet and ingesta properties, factors like wear stage and bite force may affect microwear formation, potentially leading to tooth position-specific microwear patterns. We investigated DMTA consistency along the upper cheek tooth row in young adult female rats at different growth stages, but with erupted adult dentitions. Bite forces for each molar (M) position were determined using muscle cross-sectional areas and lever arm mechanics. Rats were categorized into three size classes based on increasing skull length. Maximum bite force increased with size, while across all size classes, M3 bite force was almost 1.4 times higher than M1 bite force. In size class 1, M1 and M2 showed higher values than M3 for DMTA complexity, height, and volume parameters, while in size class 3, M1 had the lowest values. Comparing the same tooth position between size classes revealed opposing trends: M1 and M2 showed, for most parameters, decreasing roughness and complexity from size class 1-3, while M3 displayed the opposite trend, with size class 1 showing lowest, and either size class 2 or 3 the highest roughness and complexity values. This suggests that as rats age and M3 fully occludes, it becomes more utilized during mastication. DMTA, being a short-term diet proxy, is influenced by eruption and occlusion status changes. Our findings emphasize the importance of bite force and ontogenetic stage when interpreting microwear patterns and advise to select teeth in full occlusion for diet reconstruction.

Experimental Study on the Mechanical Properties of Basalt Fiber Geogrids Reinforced with Cement-Stabilized Macadam

Cement-stabilized crushed stone is widely used in the construction of high-grade highways because of its good durability and stability. However, cement-stabilized gravel is also easily affected by temperature and humidity, resulting in a reduction in the overall strength and durability of asphalt pavement. In response to this problem, in this study, we lay a single layer of a basalt fiber geogrids in a cement-stabilized gravel base of a test section of the Yan-Chong Expressway. The bonding and friction forces formed between the basalt fiber geogrids and the base as well as the mechanical bite force, play an anti-cracking role. We conducted a comparative experimental study on the mechanical properties of basalt fiber geogrids reinforced or not reinforced with cement-stabilized gravel specimens of different ages. The results showed that (1) the unconfined compressive strength of cement-stabilized gravel was slightly reduced; (2) the splitting strength was somewhat improved; (3) the compressive elastic modulus was slightly reduced; (4) the flexural and tensile strengths were significantly increased. An improvement in the crack resistance in semi-rigid base materials can improve the service life of high-grade asphalt pavements.

Dimensions of Posterior Implant Restorations Related to Intra-Coronal Cantilever and Occlusal Forces: An In Vitro Study.

The aim of the present study was to investigate the relation of the implant position to the implant crown and analyze the location and magnitude of bite force. The dimensions of 49 posterior implant-supported restorations were recorded in terms of: 1. implant diameter, 2. crown length, 3. crown width, 4. crown height, 5. occlusal surface of the restoration. The crown/implant height was measured and the distance between the implant center and the restoration center revealed the size of intra-coronal cantilevers. The occlusal force analysis determined the point and magnitude of loading. Correlation coefficient r was used for the statistical process and statistical control was carried out with the aid of t-test with minimum level of significance p < 0.05. - The mean crown-to-implant ratio was 0.9 and in short implants (< 10mm) the ratio was 1.28. - Intra-coronal cantilever extensions ranged from 2.1 mm to 6.35 mm depending on crown size. - Occlusal loading was identified in cantilever areas of the crown. - Implant center deviates from crown center in 71%-82% of the cases depending on site location. - Implants with non-ideal position may support a functionally occluding crown. Intra-coronal cantilevers are a critical factor to avoid clinical complications and should be taken under consideration both in the planning and fabrication phase of implant restorations.

Oral functions in adult persons with spinal muscular atrophy compared to a healthy control group: a prospective cross-sectional study with a multimodal approach

BackgroundOral function tests have been shown to reliably detect impaired bulbar function in adults with spinal muscular atrophy (SMA). Although not routinely recorded, it is known that persons with SMA are affected to varying degrees. Detecting differences in bite and tongue force, endurance, and maximum mouth opening has become particularly promising since the introduction of causal therapy for SMA. This study aimed to compare oral function among adult persons with SMA with different SMA types, walking abilities, and treatment status to a healthy control group.MethodsData from oral function tests conducted on 58 persons with SMA and 45 healthy individuals were analyzed. Differences in oral function between SMA subgroups were pairwise tested and compared to the healthy control group using Wilcoxon rank sum tests.ResultsIn an overall comparison, three out of five oral function tests revealed lower values for the SMA group compared to the control group. Subgroup analyses indicated lower scores for most oral function tests in non-ambulatory, untreated patients with SMA type 2 compared to controls. Ambulatory, treated patients with SMA type 3 achieved strength and endurance values comparable to those of healthy individuals.ConclusionsThe impairment of oral function varies across persons with SMA. Routine measurement of oral function is warranted to determine individual bulbar involvement stages. Further evaluation should be scheduled if indicators such as restricted maximum mouth opening arise.Trial registration DRKS, DRKS00015842. Registered 30 July 2019, https://drks.de/register/de/trial/DRKS00015842/preview.

Pterin-Based Red Coloration Predicts the Outcome of Male-Male Competition in Guinan Toad-Headed Lizard.

Animal coloration offers a unique opportunity to explore the evolutionary mechanisms underlying phenotypic diversity. Conspicuous coloration caused by pigments plays a crucial role in social signaling across multiple species by conveying information about individual quality, social ranks, or reproductive condition. Nevertheless, most previous studies have focused predominantly on colors produced by the exogenous pigments-carotenoids. Pterins are another prevalent group of conspicuous pigments, which can be produced endogenously and have received comparatively little attention. Whether pterin-based colors represent reliable signals remains elusive. The remarkable red ventrolateral coloration exhibited by males of the Guinan toad-headed lizard (Phrynocephalus guinanensis) in the Mugetan Desert presents an ideal model for investigating pterin-based coloration. Through electron microscopy and metabolomic identification, we discovered three types of pterin pigments within xanthophores. Integrating a series of morphological measurements and behavioral experiments, we found that this red coloration was not correlated with body size, bite force, and testosterone level, nor did females show a preference bias toward it. However, the red intensity predicted male-male competition outcomes, with deeper red males being more likely to emerge as winners. Our results indicated that the pterin-based coloration could convey information about male quality, suggesting its potential role in honest signaling, given the vital importance of pterin metabolism in physiological processes. This study provides a novel case into the understanding of pterin-based colors in animals.

Temporomandibular joint space variation and masticatory muscle activation during clenching with full versus partial covering occlusal splints

ObjectivesOcclusal splints are the main therapeutic choice in the treatment of temporomandibular disorders (TMD). However, their precise working mechanism is unclear. This study aimed to compare the biomechanical effect of three commercially available splint designs (full covering splint, anterior bite splint and posterior bite splint) during biting in a sample of healthy subjects.Materials and methodsMagnetic resonance imaging (MRI) was combined with jaw tracking to measure the minimal intraarticular distance (MID) of 20 human temporomandibular joints (TMJ) whilst simultaneously recording the electromyogram (EMG) of the masticatory muscles. The changes caused by clenching with a bite force of 100 N without splint (baseline) and on each splint were calculated. Repeated measures ANOVA was performed on the means of the MID variations and EMG amplitudes.ResultsClenching on the anterior bite splint resulted in two times less activation of the anterior temporalis muscle than baseline (p = 0.003), full covering (p = 0.011) and posterior bite splint (p = 0.011). MID was reduced by clenching in all conditions, but the reduction was almost three times larger with the anterior bite splint compared to no splint (p = 0.011). The full covering splint and the posterior bite splint did not differ significantly in EMG activation of both masseter and temporalis muscles and MID variation.ConclusionsThis study showed that splint designs have a different impact on the MID and EMG activation while clenching. The anterior bite splint had a greater impact on the reduction of the muscle activation, whereas clenching on the anterior bite splint led to bigger reduction of MID and thus had the greatest influence on alteration in the condylar position.Clinical relevanceThe design of the splint can affect MID and muscle activation and is a variable to consider in the treatment of patients with TMD according to their symptoms.

Effect of Simple Swallowing Training Program on Early Oropharyngeal Dysphagia in Community-Dwelling Older Adults: A Randomized Controlled Study

ObjectivesOropharyngeal dysphagia (OD) in community-dwelling older adults continues to be a challenge due to its insidious onset. This study developed a simple swallowing training program (SSTP) to address these issues and conducted a randomized controlled trial to explore its effect on swallowing function and quality of life. DesignTwo-arm randomized controlled trial. Setting: and ParticipantsA total of 248 community-dwelling older adults with OD from were included in 2024 and randomly divided into intervention and control groups. MethodsThe SSTP was developed through expert consultation. A total of 248 community-dwelling older adults with OD were included in 2024 and randomly divided into intervention and control groups. The intervention group underwent the SSTP twice daily for 21 days, with weekends off, and the control group participants did light physical activities by themselves. The primary outcome was the Gugging Swallowing Screen (GUSS), and the secondary outcomes were the Eating Assessment Tool-10 (EAT-10), Swallowing Quality of Life questionnaire (SWAL-QoL), maximum tongue pressure, masticatory ability, bite force, and meal duration. Assessments were conducted on days 1 and 21, while meal duration was assessed every 3 days for lunch. ResultsTwenty-seven participants withdrew halfway. There were no significant differences in baseline assessments (P > .05). There were significant between-group and interactive effects in the GUSS [(19.07 ± 1.38) vs (17.28 ± 2.17), Fbetween-group = 6.893, Pbetween-group = .009, Finteractive = 59.504, Pinteractive<.001], EAT-10 {[4.00 (3.00, 5.00)] vs [9.00 (7.00, 10.00)], zbetween-group = −3.502, Pbetween-group<.001; zinteractive = −6.252, Pinteractive<.001}, SWAL-QoL {[166.00 (163.00, 171.50)] vs [154.00 (150.00, 158.00)], zbetween-group = 2.681, Pbetween-group = .007; zinteractive = 5.475, Pinteractive<.001}, maximum tongue pressure {[33.10 (26.48, 36.86)] vs [28.85 (19.21, 35.77)], zbetween-group = 3.377, Pbetween-group = .001; zinteractive = −6.208, Pinteractive<.001}, masticatory ability {[176.92 (133.10, 212.91) vs [163.33 (116.66, 189.32)], zbetween-group = 4.801, Pbetween-group<.001; zinteractive = 6.979, Pinteractive<.001}. Between-group, time, and interactive effects were significant in the meal duration [(23.39 ± 4.32) vs (27.64 ± 5.63), Fbetween-group = 8.692, Pbetween-group = .004, Ftime = 138.683, Ptime< 0.001, Pinteractive = 73.196, Pinteractive<.001]. Conclusions and ImplicationsThe SSTP can effectively improve early OD and swallowing-related quality of life in community-dwelling older adults.

Masticatory function and three-dimensional facial morphology of soft tissues: One year after orthognathic surgery

ObjectiveDentofacial deformities (DFD) require orthodontic treatment, orthognathic surgery, and speech therapy for aesthetic and functional problems. This longitudinal study analyzed changes in masticatory function and three-dimensional (3D) facial soft tissue in patients with Class II and Class III DFD after orthognathic surgery. In addition, the study investigated the relationship between facial measurements, maximum bite force (MBF), and orofacial myofunctional status (OMS). DesignThe sample consisted of 46 participants, including 10 patients with Class II DFD, and 11 patients with Class III DFD. These groups were assessed before (T0) and 6 months (T1) after surgery. Twelve patients who completed the treatment protocol were evaluated 12 months post-surgery (T2). The patient groups were compared with each other and with a control group (CG) of 25 healthy subjects. The participants underwent MBF and clinical evaluation of OMS, including masticatory behavior, using a validated protocol. The 3D facial soft tissue was assessed using laser scanning. ResultsCompared to the CG, DFD patients showed reduced MBF, masticatory behavior, and OMS scores at T0. At T2, there was an improvement in MBF, masticatory, and OMS scores, but differences were observed compared to the CG. Changes in facial soft tissue followed the underlying hard tissue movement resulting from surgery, and reduction of vertical measurements contributed to improvements in masticatory function. ConclusionThese findings indicated that combined surgery, orthodontic treatment, and speech therapy can lead to a significant improvement in masticatory function and facial soft tissue in DFD patients, although not completely 12 months post-surgery.

Effect of preparation design on fracture resistance of molars restored with occlusal veneers of different CAD-CAM materials: an in vitro study

BackgroundOcclusal veneer had been evaluated for mechanical properties using lithium disillicate. However, studies evaluating the mechanical properties of occlusal veneer with different preparation designs and ceramic materials are lacking. So, this in vitro study aimed to evaluate the fracture resistance of occlusal veneers with two designs fabricated from two different ceramic materials.Material and methodsFourty mandibular third molars were distributed to 2 groups (n = 20) according to preparation design: group (O) anatomical occlusal reduction and group (OA) anatomical occlusal and 1 mm axial reduction. Each group was additionally subdivided into two subgroups (n = 10) according to ceramic materials; in subgroup X, lithium disilicate (e.max CAD, Ivoclar AG, Schaan, Liechtenstein) was used, and in subgroup S, zirconia-reinforced lithium silicate (ZLS) (Vita Suprinity, VitaZahnfabrik, Bad Säckingen, Germany) was used. All specimens were cemented with a light-cure resin cement (Choice 2, Bisco, Schaumburg, USA). 5000 thermocycles were applied to all specimens with both temperatures of 5 °C and 55 °C in two water baths; the dwell time was 30s at each bath, and the transfer time was 10s. Then all specimens were subjected to a fatigue simulation under dynamic loading of 200 N for 250,000 cycles. A universal testing machine (5500R/1123, Instron, Norwood, USA) was used to evaluate the fracture strength with a crosshead speed of 1 mm/min. All data were analyzed statistically by using a two-way ANOVA, and for some violations of assumptions, these results were compared with those obtained by the nonparametric test (Scheirer Ray Hare) (α = 0.05).ResultsA statistically significantly higher fracture resistance in the ‘OA’ (3389 N) compared to the ‘O’ (2787 N) group regardless of the ceramic material (P < .001) and a statistically significantly higher fracture resistance in the ‘X’ (3295 N) compared to the ‘S’ (2881 N) regardless of the preparation design (P = .015).ConclusionsFor occlusal veneers, all preparation designs and materials (such as Vita Suprinity and e.max CAD) had clinically acceptable fracture resistance values that were greater than the maximal biting forces. On the other hand, the e.max CAD with occlusal veneer, including axial reduction design, demonstrated the maximum fracture resistance value. Finally, no relationship between fracture strength and mode of failure was found.

An analysis of three dimensional changes to comprehensively evaluate the occlusion time, disclusion time, point of first contact and force distribution at various head positions using Tekscan III: An in vivo study

Aim: This study aims to evaluate the changes in occlusal contacts resulting from variations in head postures (supine[S], semi-supine [SS], upright with head rest support [HR], and without head rest support [WHR]) after occlusal adjustment of conventional fixed dental prostheses using Tekscan III. Settings and Design: A cross-sectional study on 15 patients with missing single molars and undergone replacement with a fixed dental prosthesis. Materials and Methods: Fifteen patients with a three-unit tooth-supported fixed dental prosthesis replacing a missing single posterior tooth were included. Tekscan III was used to analyze occlusion time (OT), disclusion time (DT), initial tooth contact, and relative bite force in different head postures by adjusting the backrest position before and after equilibration. Occlusal adjustments were performed to achieve the balance between the right and left halves. Statistical Analysis Used: The data were statistically analyzed using ANOVA and paired t-test. Results: Posterior shift of initial tooth contact was observed from SS to supine and upright positions, whereas an anterior shift occurred from SS to WHR support posture. High-intensity forces were observed before the occlusal adjustment in various head positions, and these forces changed after adjustments in SS position. However, medium-intensity force occlusal prematurities persisted in other head postures even after corrections in SS position. There was a significant difference in OT but not in DT in all head postures after equilibration. When OT was compared from SS to remaining posture after equilibration, the major difference was found from SS to head rest (HR) and supine to HR posture which infers the need for selective grinding in these postures. Conclusion: Considering the various changes while changing the head position from the SS position to the other functional position, it can be inferred that there is a need to consider recalibration of occlusal contacts in all the functional postures.