Effect of malocclusion on jaw motor function and chewing in children: a systematic review

The prevalence of masticatory muscle pain in healthy individuals with class I and class II malocclusion: a cross-sectional study

Introduction

The etiopathogenesis of TMD is complex and involves multiple factors. The role of occlusal abnormalities in the painful form of TMD remains controversial. This study aimed to determine the prevalence of myalgia in patients with class I and class II malocclusion.

Materials and methods

A total of 256 generally healthy patients, aged 25-30, with class I and class II malocclusion, were examined. Medical histories and physical examinations were conducted using the DC/TMD Form. Based on the clinical findings, the patients were divided into three groups: Group I consisted of patients with class I malocclusion; Group II included patients with class II malocclusion and proclined incisors; and Group III comprised patients with class II malocclusion and retruded incisors. Within each group, cases with muscle pain and those without were identified based on the data from the DC/TMD Form.

Results

All studied groups (Groups I, II, and III) showed a high incidence of myalgia. However, statistical analysis did not show a significant difference in the overall occurrence of muscle pain between the groups, nor were there significant differences in pain incidence when examining individual muscles among the groups.

Conclusion

No association was found between malocclusion and the occurrence of muscle pain. However, the more frequent presence of symptoms related to functional disorders, such as myalgia, highlights the need for screening and treatment even in generally healthy patients.

Stress distribution in zirconia-reinforced glass ionomer restorations in molar incisor hypomineralization: A finite element analysis

OBJECTIVE

Investigating stress distribution in zirconia-reinforced glass ionomer cement (GIC), used to restore hypomineralized permanent first molars (HPFMs), under dynamic occlusal loading, using Finite Element Analysis (FEA).

METHODS

CBCT and intra-oral scans of HPFM of an 8-year-old child were obtained. Three models were constructed using 3D-CAD software 'MIMICS 21.0'. Model I represented a sound PFM, Model II: HPFM, and Model III: HPFM restored with zirconia-reinforced GIC (Zirconomer®). An idealized dynamic occlusal loading cycle (duration 0.25 s) was simulated consisting of Phases I and II, separated by point of Maximum Intercuspation (PoMI). The maximum and mean loads were 321 and 168 N, respectively. Abaqus-FEA software was used to record Von Mises (vM), and Maximum Principal (Pmax) stresses in the assembly (A), and in the models' components: normal enamel (E), hypomineralized enamel (HE), restorative area (RA), and dentine (D).

RESULTS

Maximum vM and Pmax stresses were obtained at 0.18 s. Enamel was the stress-bearing component in all models. Model II revealed high stress concentration between E and HE. The highest stresses in the RA were obtained in Model II, and the lowest in Model III.

CONCLUSIONS

Favorable stress distributions were obtained in HPFM restored with zirconia-reinforced GIC. The high stress concentrations found at the junction between normal and hypomineralized enamel, and the poor physical properties of HE, may lead to post-eruptive enamel breakdown (PEB) common in HPFMs.

CLINICAL SIGNIFICANCE

Glass ionomer cements placed as interim restorations in molar incisor hypomineralization require strong physical properties and distribution of occlusal forces. This study shows that zirconia-reinforced GIC is an acceptable restoration in HPFMs.

Changes in the electromyographic activity of masticatory muscles in patients undergoing bimaxillary surgery

OBJECTIVE

The aim of this study is to investigate short-term changes in the electromyographic (EMG) activity of masticatory muscles in individuals with skeletal Class III malocclusion undergo double-jaw orthognathic surgery.

MATERIAL AND METHODS

In patients with skeletal Class III anomaly, EMG activity changes in the anterior temporalis and masseter muscles were measured before T0 and at 3 (T1) and 6 (T2) months after bimaxillary orthognathic surgery. Recordings were obtained using the 'MP100' device and circular Ag-AgCl electrodes during closure, clenching, chewing and swallowing. Data from 26 individuals (12 males, 14 females) with a mean age of 21.7 years were analysed using the Friedman test.

RESULTS

A significant decrease was observed in the right/left masseter muscles during clenching/chewing from T1 to T0 (right and left masseter clenching: p < 0.001, left masseter chewing: p < 0.01, right masseter chewing: p < 0.05), while a significant increase was noted in the right masseter's clenching function from T2 to T1 (p < 0.01). The EMG activity of the right anterior temporal muscle decreased during clenching at T1-T0 (p < 0.001), increased at T2-T1 (p < 0.05), and decreased during chewing/swallowing at T1-T0 (chewing: p < 0.001, swallowing: p < 0.05) and T2-T0 (p < 0.05). The left anterior temporal muscle showed decreased EMG activity during clenching at T1-T0 (p < 0.001), increased at T2-T1 (p < 0.05), and decreased during chewing at T1-T0 (p < 0.001). During swallowing, a decrease was observed at T2-T0 (p < 0.001).

CONCLUSIONS

Partial changes in EMG activity were observed during some functions in the 3-month period; however, no significant overall change was recorded in the 6-month period.

The impact of malocclusion on the prevalence of pain-related temporomandibular disorders in children and adolescents: a systematic review

Background

The connection between occlusion and temporomandibular disorders (TMD) remains a topic of discussion, and current research does not provide a definitive answer. Pain-related TMD are the most common types of TMD. They include myalgia, arthralgia, and headaches attributed to TMD. This systematic review aims to synthesize the current scientific evidence regarding impact of malocclusion on the prevalence of pain-related TMD in individuals under 18 years.

Methods

The study was based on a searching of the PubMed, Scopus, Embase, and Web of Science databases. Selection was limited to studies that explored the link between malocclusion and pain-related TMD in young individuals. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the selected research. The certainty of evidence was assessed using the Grading Recommendations Assessment, Development and Evaluation (GRADE) approach. A visual representation of the screening and inclusion processes was created using a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) diagram. The information from the research was then summarized in a descriptive format.

Results

Out of 868 potentially relevant articles initially identified, 13 studies were selected based on the inclusion criteria. The majority of these studies were determined to be of moderate quality, according to the NOS assessment. The certainty of evidence was assessed as low, according to the GRADE approach. Most of the studies showed that malocclusion may be associated with TMD-pain signs/symptoms in children and adolescents. The most frequent relationship was found between the prevalence of pain-related TMD and posterior crossbite, Class II malocclusion, Class III malocclusion, and anterior open bite.

Conclusion

Certain types of malocclusion may have an impact on the prevalence of some TMD-pain signs and symptoms in young individuals. However, given the limited reliability of existing research and the inconsistencies observed across studies, additional well-structured, long-term investigations are necessary.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024570950.

Expert consensus on early orthodontic treatment of class III malocclusion

The prevalence of Class III malocclusion varies among different countries and regions. The populations from Southeast Asian countries (Chinese and Malaysian) showed the highest prevalence rate of 15.8%, which can seriously affect oral function, facial appearance, and mental health. As anterior crossbite tends to worsen with growth, early orthodontic treatment can harness growth potential to normalize maxillofacial development or reduce skeletal malformation severity, thereby reducing the difficulty and shortening the treatment cycle of later-stage treatment. This is beneficial for the physical and mental growth of children. Therefore, early orthodontic treatment for Class III malocclusion is particularly important. Determining the optimal timing for early orthodontic treatment requires a comprehensive assessment of clinical manifestations, dental age, and skeletal age, and can lead to better results with less effort. Currently, standardized treatment guidelines for early orthodontic treatment of Class III malocclusion are lacking. This review provides a comprehensive summary of the etiology, clinical manifestations, classification, and early orthodontic techniques for Class III malocclusion, along with systematic discussions on selecting early treatment plans. The purpose of this expert consensus is to standardize clinical practices and improve the treatment outcomes of Class III malocclusion through early orthodontic treatment.

THE USAGE AND REPORTING OF DENTAL PATIENT-REPORTED OUTCOMES AMONG SYSTEMATIC REVIEWS IN ORTHODONTICS: A METHODOLOGICAL STUDY

OBJECTIVE

To summarize and analyze the usage and reporting of dental patient-reported outcomes (dPROs) within systematic reviews (SRs) published in 5 leading orthodontic journals between 2015 and 2023.

METHODS

A manual search was conducted to identify intervention (therapeutic or preventive) involved SRs published in selected journals between 2015 and 2023 from the official online archives. Two authors independently and in duplicate extracted the characteristics of each included SR, recording both the usage of dPROs in the Methods sections and the reporting of dPROs in the Results sections.

RESULTS

A total of 244 SRs were found eligible and included, of which 81 (33.2%) included dPROs. Out of the 81 SRs, 19 (23.5%) described dPROs in the Methods sections, 6 (7.4%) reported dPROs exclusively in the Results sections, and 56 (69.1%) included dPROs in both sections. In the 75 SRs that stated dPROs in their Methods sections, 38 (50.7%) identified them as primary outcomes, while 37 (49.3%) considered them secondary outcomes. Among the 62 SRs that reported dPROs in the Results section, 17 (27.4%) performed quantitative synthesis, and the remaining 45 (72.6%) conducted only qualitative synthesis. A total of 26 dPROMs were identified, of which only 11 were included in meta-analyses.

CONCLUSIONS

Only about one-third of SRs published in leading orthodontic journals included dPROs. It is recommended that researchers consider the usage of dPROs and dPROMs during the design and registration stages of orthodontic SRs and ensure transparent reporting of the results, thus facilitating evidence-based practice and shared decision-making in clinical care.

Automated orthodontic diagnosis via self-supervised learning and multi-attribute classification using lateral cephalograms

BACKGROUND

Malocclusion, characterized by dental misalignment and improper occlusal relationships, significantly impacts oral health and daily functioning, with a global prevalence of 56%. Lateral cephalogram is a crucial diagnostic tool in orthodontic treatment, providing insights into various structural characteristics.

METHODS

This study introduces a pre-training approach using multi-center lateral cephalograms for self-supervised learning, aimed at improving model generalization across diverse clinical data domains. Additionally, a multi-attribute classification network is proposed, leveraging attribute correlations to optimize parameters and enhance classification performance.

RESULTS

Comprehensive evaluation on both public and clinical datasets showcases the superiority of the proposed framework, achieving an impressive average accuracy of 90.02%. The developed Self-supervised Pre-training and Multi-Attribute (SPMA) network achieves a best match ratio (MR) score of 71.38% and a low Hamming loss (HL) of 0.0425%, demonstrating its efficacy in orthodontic diagnosis from lateral cephalograms.

CONCLUSIONS

This work contributes significantly to advancing automated diagnostic tools in orthodontics, addressing the critical need for accurate and efficient malocclusion diagnosis. The outcomes not only improve the efficiency and accuracy of diagnosis, but also have the potential to reduce healthcare costs associated with orthodontic treatments.

Development and validation of an AI-driven tool to evaluate chewing function: a proof of concept

BACKGROUND

Masticatory function is an important determinant of oral health and a contributing factor in the maintenance of general health. Currently, objective assessment of chewing function is a clinical challenge. Previously, several methods have been developed and proposed, but implementing these methods in clinics may not be feasible. Therefore, more efforts are needed for accurate assessment of chewing function and clinical use.

AIM

The study aimed to establish a proof of concept for development and validation of an automated tool for evaluating masticatory function.

METHODS

YOLOv8, a deep neural network, was fine-tuned and trained to detect and segment food fragments. The model's performance was assessed using bounding box recall metrics, segmentation metrics, confusion matrix, and sensitivity values. Additionally, a separate conversion test set evaluated the model's segmentation performance using physical units, demonstrated with Bland-Altman diagrams.

RESULTS

The YOLOv8-model achieved recall and sensitivity rates exceeding 90 %, effectively detecting and classifying food fragments. Out of 316 ground truth fragments, 301 were correctly classified, with 15 missed and 5 false positives. The Bland-Altman diagram indicated general agreement but suggested a systematic overestimation in measuring the size of post-masticated food fragments.

CONCLUSION

Artificial intelligence presents a reliable approach for automated analysis of masticatory performance. The developed application proves to be a valuable tool for future clinical assessment of masticatory function.

CLINICAL SIGNIFICANCE

The current study provides a proof of concept for development of an automated tool for clinical assessment of masticatory function.

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

OBJECTIVES

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Biomechanical effects of different mandibular movements and torque compensations during mandibular advancement with clear aligners: a finite element analysis

Introduction

This study aimed to evaluate the biomechanical effects of different mandibular movements and torque compensations during mandibular advancement with clear aligners using finite element analysis.

Methods

Models were constructed to include the mandible, teeth, periodontal ligament (PDL), and clear aligners with buccal wings. Five oral muscles (superficial masseter, deep masseter, medial temporalis, posterior temporalis, and medial pterygoid) were represented as springs. Muscle values were measured and applied during different mandibular movements, including advancement distances (1-7 mm) and occlusal opening distances (2-4 mm). Different torque compensation angles (0°, 1°, 2°, and 3°) were applied to the mandibular central incisor.

Results

When the mandibular advancement was equal to or slightly excessed the occlusal opening distance, stress on the posterior PDL decreased and became more evenly distributed. Increasing the occlusal opening distance significantly raised stress on the posterior PDL and caused grater labial inclination of the mandibular anterior teeth. As the torque compensation increased, the labial inclination of the mandibular central incisor decreased, but stress on the PDL increased. Nearly complete bodily movement of the lower central incisor was achieved with torque compensation angles of approximately 15°, 19°, and 20° in models M1-2, M2-3, and M3-4, respectively.

Conclusion

To maintain periodontal health during mandibular advancement, it is recommended that the mandibular advancement distance be equal to or slightly excessed the occlusal opening distance. Excessive occlusal opening distance increases stress on the posterior PDL and the labial inclination of mandibular anterior teeth, requiring careful control. Additionally, proper torque control of the mandibular interior teeth is crucial for optimal outcomes.

Evaluation of the bioelectrical activity of the masticatory muscles in patients with narrowed maxillary transverse dimension compared to the occlusal norm

OBJECTIVE

The aim of the study was to determine how the electrical activity of the temporalis, masseter and sternocleidomastoid muscles differs in children with reduced transverse jaw dimension compared to children with normal occlusion.

DESIGN

It was a experimental study. Thirty-seven patients were included in the study. 18 in the study group received orthodontic treatment with removable appliances and 19 subjects were classified as normal occlusion subjects in the control group. A panoramic X-ray and digital intraoral scan were taken, followed by an surface electromyography of three muscle pairs (temporalis muscles, masseter muscles, sternocleidomastoid muscles) in resting position, while clenching and clenching on cotton rollers.

RESULTS

There was significantly greater activity in the experimental group than in the control group comparing muscles: temporalis muscles and masseter muscles in the resting position. Additionally, significantly greater activity of muscles in the control group was found during clenching. However, the asymmetry index of muscles indicates that there is significantly greater asymmetry of muscles activity in the experimental group. Compared to children with normal occlusion, children with a narrowed transverse dimension of the jaw have statistically significant differences in the bioelectrical activity of the temporalis, masseter and sternocleidomastoid muscles, as well as greater asymmetry in the bioelectrical voltage of the masseter muscles.

CONCLUSIONS

Patients with reduced transverse dimension of the jaw are characterized by increased resting activity of the masticatory muscles and reduced functional activity of the masticatory muscles. These patients have increased asymmetry in the bioelectrical tension of the masticatory muscles.

Comparison of the Opinions of Adolescents With Different Orthodontic Treatment Needs

BACKGROUND

The aim of this study was to compare oral health-related quality of life (OHRQoL) among adolescents granted (G) versus not granted (NG) publicly funded orthodontic treatment.

MATERIALS AND METHODS

Adolescents aged 15-20 years who were granted versus not granted publicly funded orthodontic treatment responded to a web-based survey, assessing OHRQoL in relation to functional impact, psychological impact, and motivators for orthodontic treatment. Before the survey, pretesting of the questionnaire was conducted to ensure its reliability. Differences between the groups were tested using the chi-squared and Mann-Whitney U-tests. Reliability was assessed using Cohen's κ and Pearson's correlation coefficient during the pretest phase.

RESULTS

One hundred and forty patients, equally distributed between a G and an NG group, responded to the survey. Gender, age, and demographic distribution were comparable in both groups. All respondents expressed a high subjective treatment need and similar answers regarding functional aspects. Orthodontic treatment motivators (G: 86.2% and NG: 94.7%, p = 0.443) were primarily related to improved self-esteem, overall well-being, facial appearance, and being able to laugh without embarrassment. The NG group expressed a more negative OHRQoL impact due to the appearance of their teeth compared with the G group (p < 0.001) and a negative impact caused by the position of their teeth (p < 0.001).

CONCLUSIONS

Orthodontic treatment need indices should aim to reinforce subjective measures as adolescents express similar motivators for orthodontic treatment, regardless of the clinician's objectively based decision about treatment need.

Prevalence of Malocclusion Traits in Primary Dentition, 2010-2024: A Systematic Review

The present review was aimed to describe the prevalence and the regional distribution of malocclusion among preschool children worldwide. Two independent reviewers performed a systematic literature search to identify English publications from January 2010 to May 2024 using PubMed, ISI Web of Science and Embase. Search MeSH key words were "malocclusion", "primary dentition" and "child, preschool". The reporting quality was assessed by the modified Newcastle-Ottawa Quality Assessment Scale. We identified 2599 publications and recruited 47 articles. Fourteen of the included studies were conducted in Asia, four in Europe, twenty-eight in South America and one in Africa. The prevalence of malocclusion ranged from 28.4% to 83.9%, and half of the reported prevalences were higher than 50%. The highest percentage was in Asia (61.81%), followed by Europe (61.50%), South America (52.69%) and Africa (32.50%). Statistically significant differences existed in deep overbite, anterior open bite, posterior crossbite, edge-to-edge incisor relationship and distal step between continents (p < 0.05). Europe showed the highest prevalence (33.08%) of deep overbite. Africa showed the highest prevalence (18.60%) of anterior open bite. Europe showed the highest prevalence (15.38%) of posterior crossbite. The most common malocclusion traits were increased overjet and deep overbite. To conclude, malocclusion remained prevalent in the primary dentition and varied between countries.

Oro-facial function and quality of life in children and adolescents with large horizontal maxillary overjet-A case-control study

BACKGROUND

Large horizontal maxillary overjet (overjet) is associated with reduced bite force (BF) and number of contacts, which influence the chewing effectivity (CE). Oral health, oro-facial function (OF) and malocclusion have great impact on psychological well-being and quality of life (QoL).

OBJECTIVES

The aims of the study were to examine OF, temporomandibular disorders (TMD), BF, CE, QoL and well-being in children and adolescents with large overjet.

METHODS

The study was a case-control study including healthy children with large overjet in the study group compared to a control group of healthy children with neutral occlusion, all 9-14 years old. OF was examined by use of Nordic Orofacial Test-Screening (NOT-S), Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and registration of morphological and functional occlusion. QoL and well-being were examined using KIDSCREEN-10 and Strengths and Difficulties Questionnaire.

RESULTS

The study and control groups included 37 and 32 participants, respectively. Significantly increased NOT-S score (p < .001) and reduced BF (p = .011), numbers of contacts (p < .001) and CE (p = .005) were found in the study group. BF, numbers of contacts and CE were negatively associated with erupting canines and premolars. No significant difference was found in age, gender, dental eruption, TMD diagnosis or QoL between the groups. Significantly increased emotional symptoms (p = .007), hyperactivity (p = .043) and total difficulties score (p = .009) were found in the study group.

CONCLUSION

The study group showed higher NOT-S score and reduced BF, number of contacts and CE. No difference in QoL were found between the groups, although reduced well-being and increased emotional symptoms, hyperactivity and total difficulties were found in the study group.

Electromyographic Assessment of Muscle Activity in Children Undergoing Orthodontic Treatment-A Systematic Review

Background: Surface electromyography (sEMG) can provide an objective and quantitative image of the functional state of neuromuscular balance in the stomatognathic system. The objective of this systematic review is to examine current scientific evidence regarding the effects of orthodontic treatment on muscle electromyographic (EMG) activity in children. Methods: The search strategy included the PubMed, PubMed Central, Web of Science, Scopus, and Embase databases. The inclusion criteria were studies assessing EMG muscle activity in children undergoing orthodontic treatment compared with untreated children. The Cochrane risk-of-bias tool (RoB2) and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of the studies. The quality of evidence assessment was performed using GRADE analysis. The PRISMA diagram visually represented the search strategy, as well as screening and inclusion process. Results: The search strategy identified 540 potential articles. Fourteen papers met the inclusion criteria. Six studies were judged at a low risk of bias. The certainty of evidence was rated as moderate to low, according to the GRADE criteria. Studies showed alterations in EMG muscle activity in children undergoing orthodontic treatment. Conclusions: Orthodontic treatment appears to affect muscle activity in children undergoing orthodontic treatment. However, the quality of evidence is low and, therefore, it is not possible to definitively state this effect. Further long-term studies are needed to confirm the findings of this review. Study protocol number in PROSPERO database: CRD42023491005.

Association between occlusal features and masticatory function in Hong Kong preschool children: a survey with one-year longitudinal follow-up

BACKGROUND

Mastication is important for breaking down food, aiding swallowing and nutrients absorption, and is therefore fundamental to a child's development. Studies have shown poor masticatory function to be associated with younger age and presence of caries. However, studies of the association between masticatory function and malocclusion yielded contradictory results. The aim of this study is therefore to investigate the association between three-dimensional occlusal features with masticatory function, among preschool children in Hong Kong.

METHODS

Self-administered questionnaires on masticatory function in three domains, namely general chewing difficulty, requiring help when eating different food types and increased preference for soft food were completed by parents. Information on non-nutritive sucking habits and basic demographics were also collected in the questionnaire. Clinical examinations were conducted to record three-dimensional occlusal features and presence of caries. Baseline investigations and one-year follow-ups were undertaken for 1,566 and 996 preschool children. Association of poor masticatory function with occlusal features, sucking habits and caries was investigated using chi-squared tests. Binomial logistic regressions were then carried out incorporating any significant factors identified. Longitudinal analysis of the one-year follow-up data was carried out to investigate whether improved occlusal features, sucking habits and caries resulted in better masticatory function.

RESULTS

In the cross-sectional study, the first domain of general chewing difficulty was associated with caries and thumb/digit sucking. The second domain of requiring help when eating different food types was associated with the male sex, younger age, caries and pacifier use. The last domain of increased preference for soft foods was associated with caries and thumb/digit sucking. Occlusal features, including abnormal overjet and unilateral permanent molars not in contact, were significantly associated with poor masticatory function in the bivariate analyses, but were not significant in the logistic regressions. In the longitudinal analysis, general chewing difficulty was found to improve in those of older age and those with resolved anterior crossbite. Less help was required to eat meat in those with fewer caries. Similarly, less help was required to eat food containing bones in those with reduced pacifier use. Preferences for eating soft foods was reduced in those who developed a normal overjet.

CONCLUSIONS

The study identified significant relationships between masticatory difficulties and factors associated with age, gender, active caries, and non-nutritive oral habits such as thumb/digit sucking and pacifier use. Younger children and males required more assistance with certain food types. Active caries and thumb/digit sucking habits contributed to general masticatory difficulties and preference for soft foods. The one-year follow-up indicated that improvement in masticatory function varies across age cohorts and were associated with improved occlusal features, such as resolution of anterior crossbite and normalized overjet, reduced pacifier use, and a decrease in the number of decayed teeth.

An assessment of masticatory efficiency and occlusal load distribution in adolescent patients undergoing orthodontic treatment with functional jaw orthopedics: A prospective cohort study

INTRODUCTION

Functional jaw orthopaedics, produces a radical change in the occlusal scheme and the masticatory apparatus, particularly in patients with Class II malocclusion. It remains to be seen how the changes brought about by a functional appliance alter the masticatory ability of a growing child, who needs the necessary nutrition to properly grow the craniofacial region.

MATERIALS AND METHODS

Pretreatment and Post-treatment values of masticatory efficiency and the distribution of the occlusal load at centric occlusion were evaluated and compared for 20 patients with Class II division 1 malocclusion undergoing functional jaw orthopaedics.

RESULTS

Significant increase in the masticatory efficiency was seen during and after treatment (p < 0.5) There was an increase in the anterior distribution of occlusal load associated with a concomitant decrease in the posterior region at centric occlusion.

CONCLUSION

Improvement in the masticatory efficiency was observed after treatment of a retrognathic mandible with functional jaw orthopaedics in the adolescent participants with Class II malocclusion. This highlights the importance of treatment with functional jaw orthopaedics, which apart from providing esthetic and functional improvement also improves the ability of a growing child to extract proper nutrition from his/her diet.

Comparison of masticatory myofunctional rehabilitation combined with conventional functional appliances for the treatment of class Ⅱ, division 1 malocclusion. A retrospective cohort study

OBJECTIVE

To estimate the clinical efficacy of early masticatory myofunction rehabilitation combined with conventional functional appliances for the treatment of class Ⅱ, division 1 malocclusion in orthodontic children during the growing phase.

MATERIALS AND METHOD

A comparative retrospective cohort study, enrolled patients diagnosed with class Ⅱ/1 in the stage of late mixed or early permanent dentition. Patients were divided into a TBA group (Cohort 1): receiving Twin-block appliance treatment; and a MMR group (Cohort 2): receiving either early masticatory myofunction rehabilitation as adjunctive therapy combined with the same conventional functional appliances. The study variables were active (Phase 1) treatment duration, oral esthetic subjective impact score (OASIS), several cephalometric indices calculated from X-ray photographs, the maximum voltage (mV) and asymmetry index (AsI) of anterior temporalis (TA) and masseter muscles (MM) before and after treatment. Complications were also recorded.

RESULTS

A total of 424 cases were enrolled. The mean treatment duration in the MMR group was 168.33 days (SD: 25.43) and 215.00 days (SD: 28.81) in the TBA group; mean difference: -46.67 days (95% CI: [-81.62, -11.71]), P<0.001. For the OASIS outcome measure, there was no statistically significant difference between the mean total scores for the MMR group (18.83±7.73) or TBA group (17.67±6.47) groups adjusted to include pre-treatment OASIS scores (P = 0.783). After treatment, sella-nasion-B point (SNB), mandibular incisor angle, maxillary base and mandibular base in both two groups were significantly increased, while AB plane angle (ANB), maxillary incisor angle, overjet and overbite were significantly decreased. The mV and AsI of TA and MM were also improved following treatment. However, no significant differences were observed between two groups.

CONCLUSION

Our results confirmed that early masticatory myofunction rehabilitation in combination with conventional TBA for patients in the growing phase was significantly effective in the management of class Ⅱ/1 in orthodontic treatment, which could significantly shorten the treatment duration and had the similar improvement in the cephalometry data, OASIS scores and masticatory muscles function when comparing to conventional TBA alone.

Pre-Adolescent Diet Normalization Restores Cognitive Function in Young Mice

Mastication is a fundamental function critical for human health. Controlled by the central nervous system (CNS), it influences CNS development and function. A poor masticatory performance causes cognitive dysfunction in both older adults and children. Improving mastication may prevent cognitive decline. However, no study has determined the period of masticatory dysfunction that impairs children's later acquisition of cognitive function. Herein, we developed an animal model wherein a soft diet was switched to a normal diet at early and late time points in young mice. We aimed to investigate the impact of restored mastication on learning and memory function. Behavioral studies were conducted to evaluate learning and memory. Micro-CT was used to evaluate orofacial structural differences, while histological and biochemical approaches were employed to assess differences in the hippocampal morphology and function. Correction to a hard-textured diet before adolescence restored mastication and cognitive function through the stimulation of neurogenesis, extracellular signal-regulated kinases, the cyclic adenosine monophosphate-response element-binding protein pathway, and the brain-derived neurotrophic factor, tyrosine receptor B. In contrast, post-adolescent diet normalization failed to rescue full mastication and led to impaired cognitive function, neuronal loss, and decreased hippocampal neurogenesis. These findings revealed a functional linkage between the masticatory and cognitive function in mice during the juvenile to adolescent period, highlighting the need for adequate food texture and early intervention for mastication-related cognitive impairment in children.

Chewing Efficiency Test in Subjects with Clear Aligners

The aim of this study was to evaluate the masticatory function of subjects with clear aligners and to propose a simple and repeatable method for the clinical and experimental evaluation of masticatory function. For the testing we used almonds, a natural substance that can be easily found and stored, has intermediate consistency and hardness, is insoluble in saliva, and has the ability easily lose the moisture absorbed in the mouth. Thirty-four subjects using the Invisalign® (Align Technology, Santa Clara, CA, USA) protocol were randomly selected. This was an “intercontrol test”, i.e., all subjects under the same conditions acted as controls but also as cases whilst wearing the clear aligners. Patients were asked to chew an almond for 20 s, once with aligners and once without aligners. The material was then dried, sieved, and weighted. Statistical analysis was performed to investigate any significative differences. In all our subjects, the efficiency of chewing with clear aligners was found to be comparable to the efficiency of chewing without clear aligners. In detail, the average weight after drying was 0.62 g without aligners and 0.69 g with aligners, while after sieving at 1 mm, the average weight was 0.08 g without aligners and 0.06 g with aligners. The average variation after drying was of 12%, and after sieving at 1 mm, it was 25%. In summary, there was no substantial difference between chewing with or without clear aligners. Despite some discomfort in chewing, the clear aligners were well tolerated by most subjects, who wore them without difficulty even during meals.

Evaluation of occlusion parameters using T-scan III in patients receiving fixed orthodontic treatment

Objectives:

The aim of this study is to examine the relationship between occlusal factors and temporomandibular joint diseases (TMD).

Material and Methods:

In our study, 43 individuals who had fixed orthodontic treatment and 20 individuals who did not need treatment at Istanbul Aydin University Faculty of Dentistry Department of Orthodontics were included in the study. Evaluations were made at the beginning of treatment (T0) and at 6 months (T1). T-Scan® computerized Occlusion Analyzer was used to evaluate the number of contact points, occlusal force parameters during centric occlusion and lateral movements, and occlusion and disclusion times. Differences between groups were evaluated with Mann–Whitney or independent t-test, and within-group differences were evaluated with Wilcoxon sign test or paired t-test, depending on whether the data showed normal distribution or not.

Results:

There was no statistically significant distinction between the gender-based parameters and right and left joint of Joint Vibration Analysis record in all three groups (P > 0.05). At the beginning of orthodontic treatment, there was no statistical difference in the variables within the group and between the groups. As a result of the comparison between the beginning of treatment (T0) and the 6th month (T1), no significant difference was found between the parameters of the anterior/posterior occlusal force distribution of the right-left quadrant and the force distribution of the working and non-working sides in lateral movements, and the occlusion and disclusion time parameters. Maximum intercuspal position left/right (MxlntlTSCANT1) was found to be statistically significant at 6 months in individuals who received fixed orthodontic treatment with extraction compared to the none xtraction treatment group (P < 0.05).

Conclusion:

According to our research, T-scan is one of the best devices for the early detection of TMD, especially for people undergoing orthodontic treatment. T-scan offers fast, non-invasive, and repeatable occlusion recording.

Dietary experiences during fixed orthodontic treatment

Objectives:

Orthodontists generally recommend avoidance of certain foods during fixed appliance (FA) treatment, based on anecdotal information. This study aimed to identify the dietary preferences and experiences of patients undergoing FA treatment as a step toward the preparation of evidence-based dietary guidelines.

Material and Methods:

Questionnaires regarding dietary preferences and experiences of patients undergoing FA treatment were applied to a convenience sample of 38 adolescents (12 M; 26 F). Open-ended responses were summarized and visualized in a world cloud generator. 5-point Likert and Visual Analog Scales (VAS) were used to record the closed-ended responses. Descriptive statistics and multivariate analysis of variance were used to analyze questionnaire findings.

Results:

Lollies, apples, and nuts frequently caused problems with FA. The most frequent reason for avoiding certain types of food was worry about appliance breakage, followed by pain and sensitivity. VAS scores indicated that toffee and caramel scored highest (65.1% F and 54.1% M) for discomfort followed by corn on the cob (64.4% F and 48.7% M) and apples (56.6% F and 55.3% M). VAS scores did not differ significantly between the sexes (P > 0.05). Nearly, a quarter of the sample reported that FA negatively affected their eating behaviors, causing pain and discomfort during eating. No sex differences (P > 0.05) were found for negative experiences with food.

Conclusion:

Dietary preferences and experiences of patients undergoing FA treatment were identified concerning a New Zealand diet profile. A future study with a larger sample size will help formulate evidence-based dietary guidelines during FA treatment.

Does Orthodontic Treatment Change the Preferred Chewing Side of Patients with Malocclusion?

Whether orthodontic treatment can change the preferred chewing side (PCS) is unknown. This study examined (1) if the PCS changes after orthodontic treatment and (2) which factors contribute to this change. Two hundred fifty patients who visited the orthodontic clinic at Tokyo Medical and Dental University Hospital between 2017 and 2020 were included in the study. Mandibular kinesiograph (MKG) was taken at pre- and post-treatment, and PCS was determined. Patients who showed a change in PCS to the opposite side and those who showed no change in PCS at post-treatment were pooled into the PCS-changed and PCS-unchanged groups, respectively. The demographic, clinical, and cephalometric parameters were compared between the groups. Significant factors associated with changes in were of age < 20 years at the beginning of orthodontic treatment (odds ratio (OR), 2.00), maximum lateral mandibular movement to PCS ≥ 10.0 mm at pre-treatment (OR, 6.51), and change in occlusal canting of ≥1.0° (OR, 2.72). The predicted probability of change in PCS was 13.2%, 36.0%, and 67.5% for no factor, one factor, and two factors associated with PCS change, respectively. Orthodontic treatment may change PCS due to patient age, maximum lateral mandibular movement to PCS, and change in occlusal canting.

Mobile application for monitoring and normalizing the mastication muscle functional condition

Relevance. We have developed and patented a mobile application for monitoring and normalizing the mastication muscle functional state to solve the problems of detecting people with suspected dysfunction of the jaw muscles and increase the efficiency of muscle exercises.

Purpose. To evaluate the positive effect of the mobile application to control and normalize the mastication muscle functional state in the clinical orthodontic practice.

Material and methods. The study included 74 patients of Children Clinical Dental Clinic No. 2 of Voronezh, aged 6 to 12 years, who presented for a dental check-up. The masseter muscle tone was determined using the Mioton-3S device.

Results. The authors’ method of self-examination does not give a systematic overestimation or underestimation of parameters (p = 0.083) compared to the standard myotonometry, which evidences its reliability and the possibility to use for preliminary examination and detection of people with suspected abnormal muscle tone. The analysis of the masseter muscles’ tone one month later revealed a statistically signifcant (p = 0.034) decrease in the number of patients with tone disorder among the mobile application users compared to the patients who did not use the application.

Conclusion. The developed mobile application is efficient for preliminary assessment and detection of people with suspected abnormal muscle tone. Mobile application helps increase efficiency and awareness of muscle exercises.