Investigation of Malocclusion and Associated Factors in Preschoolers: A Cross-Sectional Questionnaire Study

This study aims to describe the prevalence of malocclusion and identify associated factors in preschool children. Completed in 2022-2023, this cross-sectional study included 523 children aged 26 to 80 months in municipal schools in Salvador. An oral examination was carried out on the children, and a questionnaire was self-administered by the parents. Descriptive analyses and multivariate logistic regression (the backward method, p-value ≤ 0.05, 95% CI) were conducted. The majority of children were female (51.82%), over 54 months old (52.2%), Black or mixed race (90.63%), and not affected by COVID-19 (92.35%). The prevalence of malocclusion was 43.21%, with open bite as the most common condition. There was a significant association between malocclusion and screen time (OR: 1.34; p: 0.116; CI: 1.0-1.94), physical/psychological aggression (OR: 2.55; p: 0.031; CI: 1.0-5.98), consumption of ultra-processed foods (OR: 1.77; p: 0.003; CI: 1.22-2.57), digital suction (OR: 3.1; p: 0.001; CI: 1.56-6.16), and the habit of biting objects (OR: 1.56; p: 0.121; CI: 1.0-2.73). The promotion of comprehensive health in early childhood and psychosocial interventions are recommended, aiming to reduce screen time, aggression, consumption of ultra-processed foods, thumb sucking, and the habit of biting objects to prevent malocclusion.

Bite Force Mapping Based on Distributed Fiber Sensing Network Approach

Bite force measurements are crucial in the realm of biomedical research, particularly in the areas of dentistry and orthodontic care. Various intraoral devices have been used to assess biting force, but each has limitations and drawbacks. Fiber optic sensors (FOSs) offer advantages such as electrical inertness, immunity to electromagnetic interference, and high sensitivity. Distributed fiber optic sensing allows an increase in the number of sensing points and can interrogate numerous reflections from scattering events within an optical fiber. We present four dental bites with heights of 6 mm, which enabled bilateral measurements. U-shaped sensors were prepared by embedding fibers into silicone by folding a single-mode fiber into four lines and multiplexing eight parallel nanoparticle-doped fibers. Dental bite models were created using two silicone materials (Sorta Clear 18 and Sorta Clear 40). The developed sensors were calibrated by applying weights up to 900 g, resulting in a linear response. Experiments were conducted to compare the efficacy of the dental bites. The collection of massive data was enabled by constructing a 2D map of the dental bites during multi-point sensing.

A Chewing Study of Abuse-Deterrent Tablets Containing Polyethylene Oxide Using a Robotic Simulator

Abuse-deterrent formulations (ADFs) refer to formulation technologies aiming to deter the abuse of prescription drugs by making the dosage forms difficult to manipulate or extract the opioids. Assessments are required to evaluate the performance of the drugs through different routes including injection, ingestion, and insufflation and also when the drugs are manipulated. Chewing is the easiest and most convenient way to manipulate the drugs and deserves investigation. Chewing is one of the most complex bioprocesses, where the ingested materials are subject to periodic tooth crushing, mixed through the tongue, and lubricated and softened by the saliva. Inter- and intra-subject variations in chewing patterns may result in different chewing performances. The purpose of this study is to use a chewing simulator to assess the deterrent properties of tablets made of polyethylene oxide (PEO). The simulator can mimic human molar grinding with variable chewing parameters including molar trajectory, chewing frequency, and saliva flow rate. To investigate the effects of these parameters, the sizes of the chewed tablet particles and the chewing force were measured to evaluate the chewing performance. Thirty-four out of forty tablets were broken into pieces. The results suggested that the simulator can chew the tablets into smaller particles and that the molar trajectory and saliva flow rate had significant effect on reducing the size of the particles by analysis of variance (ANOVA) while the effect of chewing frequency was not clear. Additionally, chewing force can work as an indicator of the chewing performance.

Sagittal crest morphology decoupled from relative bite performance in Pleistocene tapirs (Perissodactyla: Tapiridae)

Bite force is often associated with specific morphological features, such as sagittal crests. The presence of a pronounced sagittal crest in some tapirs (Perissodactyla: Tapiridae) was recently shown to be negatively correlated with hard-object feeding, in contrast with similar cranial structures in carnivorans. The aim of this study was to investigate bite forces and sagittal crest heights across a wide range of modern and extinct tapirs and apply a comparative investigation to establish whether these features are correlated across a broad phylogenetic scope. We examined a sample of 71 specimens representing 15 tapir species (5 extant, 10 extinct) using the dry-skull method, linear measurements of cranial features, phylogenetic reconstruction, and comparative analyses. Tapirs were found to exhibit variation in bite force and sagittal crest height across their phylogeny and between different biogeographical realms, with high-crested morphologies occurring mostly in Neotropical species. The highest bite forces within tapirs appear to be driven by estimates for the masseter-pterygoid muscle complex, rather than predicted forces for the temporalis muscle. Our results demonstrate that relative sagittal crest height is poorly correlated with relative cranial bite force, suggesting high force application is not a driver for pronounced sagittal crests in this sample. The divergent biomechanical capabilities of different contemporaneous tapirids may have allowed multiple species to occupy overlapping territories and partition resources to avoid excess competition. Bite forces in tapirs peak in Pleistocene species, independent of body size, suggesting possible dietary shifts as a potential result of climatic changes during this epoch.

Effect of scan delay on measurements of an occlusal pressure sensitive film: An in-vitro study

Background/purpose

While scan delay may affect the measurements of an occlusal pressure-sensitive film, Dental Prescale II (DPS2), the duration of scan delay was rarely reported in previous studies. This study aimed to clarify the effect of scan delay on DPS2 measurements.

Materials and methods

Two experiments were performed to clarify the effect of 0- to 10-min scan delay after DPS2 force registration. In both experiments, 11 loads were applied separately on a DPS2 film at 1-min interval between loads. Scanning was performed immediately after the 11th load in the 1-scan experiment and immediately after each load in the 11-scan experiment. A 300-N load was applied with a universal testing machine on 10 DPS2 films in each experiment and the DPS2 film was scanned with Bite Force Analyzer. Load measured, contact area, mean pressure, and maximum pressure were reported. ANOVA and Scheffé test were performed to compare the effect of number of scans and delay scan duration on these measurements with the critical value set at P ≤ 0.05.

Results

Number of scans had no significant effect on the four measurements studied. However, all measurements, except contact area, were significantly affected by scan delay; the longer the scan delay, the greater the increase in measurements. The load measured showed a rapid increase (13%) in the first 2 min, followed by a gradual increase from 2 min to 10 min (10%).

Conclusion

Scan delay does affect DPS2 measurements, and it is important to standardize and report scan delay duration in clinical studies.

Supplied Food Consistency and Oral Functions of Institutionalized Elderly

Background

Maintaining good oral function is one of the goals of dental treatment. The Japanese national insurance system newly introduced the concept of management of oral function according to the life stage. For the application of management of oral functions of the elderly, seven kinds of examination is a must for the diagnosis: xerostomia, oral hygiene status, maximum occlusal pressure, tongue and labium function, tongue pressure, chewing ability, and swallowing function. We analyzed the relationship between oral functions and supplied food consistency.

Methods

Oral functions and supplied food consistency of sixty-nine institutionalized elderly were investigated. There were 13 men and 56 women, and their mean age was 86.23 ± 7.02. Oral functions were measured and evaluated according to the Japanese insurance system. Data were analyzed by item response theory analysis, ROC analysis, and decision analysis.

Results

By the item response theory analysis, tongue pressure and swallowing functions had high discrimination ability. The subjects who had malfunction of the tongue and labium all had processed food. The subjects with difficulty in swallowing, even without malfunction of the tongue and labium, all had processed food.

Conclusion

Supplied food consistency may depend on the oral functions. However, as oral function has some dimension, a systematic evaluation system is necessary to decide the supplied food consistency.

Occlusal force predicts global motion coherence threshold in adolescent boys

Background

Beneficial effects of mastication on cognitive abilities in the elderly have been shown in human studies. However, little is currently known about the effect of masticatory stimulation on cognitive and perceptual ability in younger populations. The purpose of the present study is to investigate the influences of masticatory stimulation on perceptual ability in adolescent boys.

Methods

The present study examined the relationship between occlusal force (i.e., masticatory stimulation) and visual perception ability in adolescent boys. Visual perception ability was quantified by measuring global motion coherence threshold using psychophysical method. As an index of masticatory stimulation, occlusal force was measured by pressure sensitive film. We also measured participants’ athletic ability, e.g. aerobic capacity and grip strength, as potential confounding factor.

Results

The multiple regression analysis revealed a significant negative correlation between global motion coherence threshold and occlusal force, which persisted after controlling for confounding factors such as age and aerobic capacity.

Conclusions

This finding indicates that masticatory stimulation enhances visual perception in adolescent boys, indicating the possibility that beneficial effects of masticatory stimulation are observed not only in the elderly but in developing population consistently with the findings of the previous animal studies.

Perception and measurement of food texture: Solid foods

There is still a gap between instrumental measurement and sensory evaluation because of the complexity of food texture in spite of many efforts. In sensory evaluation, the terms describing the texture should be well understood by panelists, which poses a problem of establishing lexicons and training panelists. In the instrumental measurement, more efforts are required to understand the large deformation and fracture behavior of foods. The texture profile analysis (TPA) proposed by Alina Szczesniak, Malcolm Bourne, and Sherman has been applied to many foods, and was useful to develop the understanding of textures. But sometimes confusion of the interpretation of TPA parameters appeared. Many new techniques have been introduced to quantify TPA parameters. Recent efforts to fill the gap between sensory evaluation and instrumental measurements, human measurements, or physiological measurements have been introduced. This endeavor is an effort of synthesizing the dentistry and biomedical approach, sensory and psychological approach, and material science approach, and therefore, the collaboration among these disciplines is necessary. This manuscript mainly discusses texture studies for solid foods.

PRACTICAL APPLICATIONS

To fill the gap between the sensory evaluation and the instrumental measurement of texture, it is necessary to examine the physical change of foods during the oral processing. This will give us the designing principle of palatable and safe foods.

Differences between the chewing and non-chewing sides of the mandibular first molars and condyles in the closing phase during chewing in normal subjects

OBJECTIVE

This study aimed to assess differences between the closing paths of the chewing and non-chewing sides of mandibular first molars and condyles during natural mastication, using standardized model food in healthy subjects.

DESIGN

Thirty-two healthy young adults (age: 19-25 years; 22 men, 10 women) with normal occlusion and function chewed on standardized gummy jelly. Using an optoelectric jaw-tracking system with six degrees of freedom, we recorded the path of the mandibular first molars and condyles on both sides for 10 strokes during unilateral chewing. Variables were compared between the chewing side and the non-chewing side of first molars and condyles on frontal, sagittal, and horizontal views during the early-, middle- and late-closing phases.

RESULTS

On superior/inferior displacements, the chewing side first molar and condyle were positioned superior to those on the non-chewing side during the early- and middle-closing phases. Conversely, the first molar and condyle on the non-chewing side were positioned significantly superior to those on the chewing side during the late-closing phase. On anterior/posterior displacements, the chewing side mandibular first molar and condyle were positioned significantly posterior to those on the non-chewing side throughout all closing phases.

CONCLUSION

Our results showed the differences between the mandibular first molars and condyles on both sides with respect to masticatory path during natural chewing of a model food. These differences can be useful for informing initial diagnostic tests for impaired masticatory function in the clinical environment.

Dynamic Modelling of Tooth Deformation Using Occlusal Kinematics and Finite Element Analysis

Background

Dental biomechanics based on finite element (FE) analysis is attracting enormous interest in dentistry, biology, anthropology and palaeontology. Nonetheless, several shortcomings in FE modeling exist, mainly due to unrealistic loading conditions. In this contribution we used kinematics information recorded in a virtual environment derived from occlusal contact detection between high resolution models of an upper and lower human first molar pair (M¹ and M₁, respectively) to run a non-linear dynamic FE crash colliding test.

Methodology

MicroCT image data of a modern human skull were segmented to reconstruct digital models of the antagonistic right M¹ and M₁ and the dental supporting structures. We used the Occlusal Fingerprint Analyser software to reconstruct the individual occlusal pathway trajectory during the power stroke of the chewing cycle, which was applied in a FE simulation to guide the M₁ 3D-path for the crash colliding test.

Results

FE analysis results showed that the stress pattern changes considerably during the power stroke, demonstrating that knowledge about chewing kinematics in conjunction with a morphologically detailed FE model is crucial for understanding tooth form and function under physiological conditions.

Conclusions/Significance

Results from such advanced dynamic approaches will be applicable to evaluate and avoid mechanical failure in prosthodontics/endodontic treatments, and to test material behavior for modern tooth restoration in dentistry. This approach will also allow us to improve our knowledge in chewing-related biomechanics for functional diagnosis and therapy, and it will help paleoanthropologists to illuminate dental adaptive processes and morphological modifications in human evolution.

Influence of surgical orthodontic treatment on masticatory function in skeletal Class III patients

Skeletal Class III patients exhibit malocclusion characterised by Angle Class III and anterior crossbite, and their occlusion shows total or partially lateral crossbite of the posterior teeth. Most patients exhibit lower bite force and muscle activity than non-affected subjects. While orthognathic surgery may help improve masticatory function in these patients, its effects have not been fully elucidated. The aims of the study were to evaluate jaw movement and the electromyographic (EMG) activity of masticatory muscles before and after orthognathic treatment in skeletal Class III patients in comparison with control subjects with normal occlusion. Jaw movement variables and EMG data were recorded in 14 female patients with skeletal Class III malocclusion and 15 female controls with good occlusion. Significant changes in jaw movement, from a chopping to a grinding pattern, were observed after orthognathic treatment (closing angle P < 0.01; cycle width P < 0.01), rendering jaw movement in the patient group similar to that of the control group. However, the grinding pattern in the patient group was not as broad as that of controls. The activity indexes, indicating the relative contributions of the masseter and temporalis muscles (where a negative value corresponds to relatively more temporalis activity and vice versa) changed from negative to positive after treatment (P < 0.05), becoming similar to those of control subjects. Our findings suggest that orthognathic treatment in skeletal Class III patients improves the masticatory chewing pattern and muscle activity. However, the chewing pattern remains incomplete compared with controls.