Masseter response to long-term experimentally induced anterior crossbite in Sprague-Dawley rats.

OBJECTIVE: To detect the long-term response to unilateral anterior crossbite (UAC) in masticatory muscles and in molecular biomarkers of peripheral blood leukocytes. DESIGN: Fifty-six six-week-old Sprague-Dawley rats were used. The gene-fold changes in peripheral blood leukocytes were detected by the microarray analysis to compare the rats that received 20-week UAC treatment with age-matched controls (n = 4). Muscle atrophy-related gene Fbxo32 was selected based on the data of the microarray analysis verified by using real-time PCR. The remaining 36 rats were randomly separated in the UAC and control groups at 12 and 20 weeks (n = 12). The protein expression of Fbxo32 and the muscle injury and myogenesis-related markers, αB-crystallin and desmin, were detected in the masseter and lateral pterygoid muscles by western blot assay. RESULTS: In the 20-week UAC group, the masseter muscle weight was lower than that in the age-matched control group, and the expression level of Fbxo32 gene in peripheral blood leukocytes was increased according to the microarray analysis confirmed by real-time PCR detection. The increased protein expression levels of Fbxo32 were detected in the masseter in the 20-week UAC group, and the protein expression levels of desmin and αB-crystallin were decreased at this time point. No similar changes were detected in the lateral pterygoid muscle. CONCLUSIONS: Masseter atrophy is induced by long-term stimulation of UAC. The increased expression of the Fbxo32 gene in peripheral blood leukocytes may be a candidate biological marker of masseter atrophy.

Assessment of Masticatory Muscle Function in Patients with Bilateral Complete Cleft Lip and Palate and Posterior Crossbite by means of Electromyography.

Aim: The aim of this study was to evaluate the electrical activity of the masticatory muscles in children with a bilateral complete cleft lip and palate (BCCLP) and posterior crossbite as well as in noncleft subjects with no malocclusion. Another purpose of the study was to examine the possible factors associated with this muscle activity. Methods: The study included 52 children with mixed dentition and Class I occlusions (20 patients with nonsyndromic BCCLP and 32 subjects with no clefts). All the cleft patients had posterior crossbite. The surface electromyography (sEMG) was used to identify the electrical potentials of the temporalis and masseter muscles. The electromyographical (EMG) recordings were taken with a DAB-Bluetooth Instrument (zebris Medical GmbH, Germany) at rest and during maximum voluntary clenching (MVC). The relationships between muscle EMG activity and independent variables were identified through multivariate logistic regression analysis. Results: The EMG activity of the temporalis muscles at rest was significantly higher in BCCLP patients with malocclusion in comparison with the noncleft subjects with normal occlusion. During MVC, significantly lower electrical potentials of the temporalis and masseter muscles were observed in cleft patients compared to the noncleft group. The presence of BCCLP, unilateral posterior crossbites, increased vertical overlap, and increased overjet are factors strongly associated with higher temporalis muscle EMG activity at rest. Conclusion: The use of surface electromyography in imaging muscle function showed that children with BCCLP and posterior crossbite exhibited altered masticatory muscle potentials at rest and during clenching. The presence of unilateral posterior crossbites, increased vertical overlap, and increased overjet had a significant impact on temporalis muscle activity in cleft patients. This knowledge is important in the aspect of early and proper diagnosis and orthodontic treatment of malocclusions, thereby achieving correct occlusion and improvement in muscle function.

The influence of malocclusion, sucking habits and dental caries in the masticatory function of preschool children.

The aim of this study was to evaluate the association of malocclusion, nutritive and non-nutritive sucking habits and dental caries in the masticatory function of preschool children. A cross-sectional study was conducted with a sample of 384 children aged 3-5 years. A single examiner calibrated for oral clinical examinations performed all the evaluations (kappa > 0.82). Presence of malocclusion was recorded using Foster and Hamilton criteria. The number of masticatory units and of posterior teeth cavitated by dental caries was also recorded. The parents answered a questionnaire in the form of an interview, addressing questions about the child's nutritive and non-nutritive sucking habits. The masticatory function was evaluated using Optocal test material, and was based on the median particle size in the masticatory performance, on the swallowing threshold, and on the number of masticatory cycles during the swallowing threshold. Data analysis involved simple and multiple linear regression analyses, and the confidence level adopted was 95%. The sample consisted of 206 children in the malocclusion group and 178 in the non-malocclusion group. In the multiple regression analysis, the masticatory performance was associated with age (p = 0.025), bottle feeding (p = 0.004), presence of malocclusion (p = 0.048) and number of cavitated posterior teeth (p = 0.030). The swallowing threshold was associated with age (p = 0.025), bottle feeding (p = 0.001) and posterior malocclusion (p = 0.017). The number of masticatory cycles during the swallowing threshold was associated with the number of cavitated posterior teeth (p = 0.001). In conclusion, posterior malocclusion, bottle feeding and dental caries may interfere in the masticatory function of preschool children.

Analysis of temporomandibular joint dysfunction in paediatric patients with unilateral crossbite using automatically generated finite element models.

The evaluation of temporomandibular joint (TMJ) dysfunction using finite element models is a time consuming process that requires extensive technical knowledge. We combined a statistical active appearance model with automated modelling algorithms to biomechanically study the relationship between TMJ malformations and dysfunction in radiographs from 20 paediatric patients with unilateral crossbite. A fitting algorithm (fitting error < 4%) recognised the TMJ shape and adjusted the dimensions of each patient-specific 2D FE model, which was then used to compute 2 different joint movements. Significant functional differences were observed between the crossbite and non-cross bite sides, and the shape-function relation was verified.

Correlation between the cephalometric measurements and acoustic properties of /s/ sound in Turkish.

Objectives To evaluate the acoustic properties of the /s/ sound in individuals with different occlusion types and to investigate relationships between these properties and cephalometric measurements. Methodology Sixty patients were divided into three groups based on malocclusion. Group 1 included 20 patients (mean age: 14.85±2.01 years) with Class I skeletal and dental relationships. Group 2 included 20 patients (mean age: 13.49±1.78 years) with Class II skeletal and dental relationships. Group 3 included 20 patients (mean age: 12.46±2.62 years) with Class III skeletal and dental relationships. Cephalometric tracings were obtained from cephalometric radiographs. All included patients were native speakers of Turkish. The /s/ sound was selected for center of gravity analysis. Correlations between cephalometric values and acoustic parameters were also investigated. Results The center of gravity of the /s/ sound had the lowest value in Group 2 (p<0.05). For the /s/ sound in Group 3, moderate positive correlations were found between center of gravity and Sella-Nasion to Gonion-Gnathion angle (p<0.05, r=0.444) Lower incisor to Nasion-B point (p<0.023, r=0.505), and Lower incisor to Nasion-B point angle (p<0.034; r=0.476). No correlation was found in other cephalometric measurements. Conclusions The /s/ sound was affected by malocclusion due to the changing place of articulation. Therefore, referral to an orthodontist for malocclusion treatment especially patients with class III in the early period is suggested for producing acoustically ideal sound.

Effects of Rapid Palatal Expansion on Chewing Biomechanics in Children with Malocclusion: A Surface Electromyography Study.

Malocclusion during childhood may affect both morphology and masticatory function and could greatly affect the subsequent growth and development of the jaws and face. The purpose of this study was to evaluate the efficiency of surface electromyography in describing the effects of the rapid palatal expansion (RPE) on Masseter (M) and Temporalis Anterior (T) muscles' activity in 53 children with different types of malocclusion: bilateral posterior crossbite (BPcb), underdeveloped maxillary complex without crossbite (NOcb) and unilateral posterior crossbite on the right (UPCBr) and on the left (UPCBl). The muscular activities during chewing tasks were assessed bilaterally before and after RPE application and three months after removal. Both the envelope's peak (µV) and its occurrence (% of chewing task) were extracted from the surface electromyography signal. Our results showed the presence of statistically significant differences (p < 0.05) on temporomandibular joint muscles, across different assessments, in all the tested populations of subjects. Surface electromyography demonstrated a relationship between the correction of a maxillary transverse discrepancy and the restoration of a muscle's activation patterns comparable to healthy subjects for both T and M.

Assessment of early orthodontic treatment on functional shifts by telemonitoring mandibular movements using a smart phone.

Introduction: To assess effect of orthodontic treatment on anterior or lateral functional shift in mixed dentition stage by telemonitoring mandibular movements in four-dimensions using a novel objective method that can assist in orthodontics and other dental specialties without the need of expensive, bulky or complicated equipment. Methods: A sample of 60 patients was divided into two groups. Group I included 30 patients with normal occlusion and TMJ functions. Group II included 30 patients that were diagnosed with an abnormal path of closure in antero-posterior or transverse directions due to disharmony between centric occlusion and centric relation. The latter group was orthodontically treated and mandibular movements were measured before, during, directly after orthodontic treatment, and one year after treatment using our proposed method. To evaluate validity and reliability of our method, it was compared with two methods, a commercially available mandibular scanner, and a low-cost graphical method that utilizes a sheet of wax and a stylus. Results: It was found that the overall differences between opening and closing curves of our proposed method and the other two methods were small and negligible (p > 0.05). Discussion: It was found that our proposed method is offering a reasonably accurate, simple and rapid way to telemonitor the mandible movements in four-dimensions using the rear/front camera of any smart-phone.

The influence of malocclusion, sucking habits and dental caries in the masticatory function of preschool children

Abstract The aim of this study was to evaluate the association of malocclusion, nutritive and non-nutritive sucking habits and dental caries in the masticatory function of preschool children. A cross-sectional study was conducted with a sample of 384 children aged 3-5 years. A single examiner calibrated for oral clinical examinations performed all the evaluations (kappa > 0.82). Presence of malocclusion was recorded using Foster and Hamilton criteria. The number of masticatory units and of posterior teeth cavitated by dental caries was also recorded. The parents answered a questionnaire in the form of an interview, addressing questions about the child's nutritive and non-nutritive sucking habits. The masticatory function was evaluated using Optocal test material, and was based on the median particle size in the masticatory performance, on the swallowing threshold, and on the number of masticatory cycles during the swallowing threshold. Data analysis involved simple and multiple linear regression analyses, and the confidence level adopted was 95%. The sample consisted of 206 children in the malocclusion group and 178 in the non-malocclusion group. In the multiple regression analysis, the masticatory performance was associated with age (p = 0.025), bottle feeding (p = 0.004), presence of malocclusion (p = 0.048) and number of cavitated posterior teeth (p = 0.030). The swallowing threshold was associated with age (p = 0.025), bottle feeding (p = 0.001) and posterior malocclusion (p = 0.017). The number of masticatory cycles during the swallowing threshold was associated with the number of cavitated posterior teeth (p = 0.001). In conclusion, posterior malocclusion, bottle feeding and dental caries may interfere in the masticatory function of preschool children.

Correlation between the cephalometric measurements and acoustic properties of /s/ sound in Turkish

Abstract Objectives To evaluate the acoustic properties of the /s/ sound in individuals with different occlusion types and to investigate relationships between these properties and cephalometric measurements. Methodology Sixty patients were divided into three groups based on malocclusion. Group 1 included 20 patients (mean age: 14.85±2.01 years) with Class I skeletal and dental relationships. Group 2 included 20 patients (mean age: 13.49±1.78 years) with Class II skeletal and dental relationships. Group 3 included 20 patients (mean age: 12.46±2.62 years) with Class III skeletal and dental relationships. Cephalometric tracings were obtained from cephalometric radiographs. All included patients were native speakers of Turkish. The /s/ sound was selected for center of gravity analysis. Correlations between cephalometric values and acoustic parameters were also investigated. Results The center of gravity of the /s/ sound had the lowest value in Group 2 (p<0.05). For the /s/ sound in Group 3, moderate positive correlations were found between center of gravity and Sella-Nasion to Gonion-Gnathion angle (p<0.05, r=0.444) Lower incisor to Nasion-B point (p<0.023, r=0.505), and Lower incisor to Nasion-B point angle (p<0.034; r=0.476). No correlation was found in other cephalometric measurements. Conclusions The /s/ sound was affected by malocclusion due to the changing place of articulation. Therefore, referral to an orthodontist for malocclusion treatment especially patients with class III in the early period is suggested for producing acoustically ideal sound.

Analysis of dental compensation in patients with facial asymmetry using cone-beam computed tomography.

INTRODUCTION: The purpose of this research was to evaluate dental compensation in facial asymmetry and its correlation with skeletal variables using cone-beam computed tomography. METHODS: Sixty adult patients were retrospectively divided into asymmetry (mean age, 21.8 ± 5.4 years) and symmetry groups (mean age, 28.1 ± 4.1 years); both groups comprised 30 patients. Independent and paired t tests were used for comparisons between the asymmetry and symmetry groups and between deviated (Dv) and nondeviated (NDv) sides of the asymmetry group, respectively. Pearson correlation between dental and skeletal variables was performed. RESULTS: The mean value of menton deviation was 9.4 mm in the asymmetry group. Compared with the symmetry group, the direction and amount of dental compensation of the asymmetry group were as follows: 2.5-mm extrusion of the maxillary first molar (UM6) at NDv (P <0.05); 1.8-mm higher position of the mandibular canine (LC) from the mandibular horizontal plane using mental foramen (MHP_mf) at NDv (P <0.05); 6°-more buccoversion of UM6 at Dv; 3.7°-more linguoversion of UM6 at NDv; 4.8°-more buccoversion of the maxillary canine (UC) at Dv; 4.9°-more buccoversion of the mandibular molar (LM6) at NDv; and 2.6°-more linguoversion of LC at Dv. Dental compensation correlated or marginally correlated with skeletal variables of the deviated mandible. CONCLUSIONS: Dental compensations, extrusion of the maxillary molars on the NDv, and buccal tipping of the maxillary teeth and lingual tipping of the mandibular teeth on the Dv, were observed. The mandibular body length was associated with linguoversion of the mandibular molars on the Dv. The ramal inclination was related to the extrusion of the maxillary molars on the NDv.

Comparison of Oral Health-Related Quality of Life in Treated and Non-Treated Orthodontic Patients.

INTRODUCTION: Malocclusion as an oral disorder can cause negative impact on individuals oral conditions, social interactions and self-esteem. AIM: The aim of this study was to compare oral health-related quality of life (OHQoL) of patients who had received fixed orthodontic treatment and patients who had not received fixed orthodontic treatment. MATERIALS AND METHODS: Data were collected from 178 participants attended at professional dental office (mean age 22.71 years) in two groups (experimental and control). The experimental group comprised of 90 subjects who were in the retention phase, after their orthodontic treatment, and the control group comprised of 88 untreated subjects. Oral Health Impact Profile (OHIP-14) was used to assess the patients oral health related quality of life (OHQoL). RESULTS: The control group had significantly higher OHIP-14 scores than experimental group (p < 0.001). Participants with treatment need reported a significantly greater negative impact on the overall OHRQoL score. CONCLUSION: Subjects with no history of orthodontic treatment had more negative oral health related quality (OHRQoL), than subjects who had completed orthodontic treatment. Dental malocclusion has significant negative impact on OHRQoL.

Factors associated with spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction.

INTRODUCTION: This study aimed to identify significant factors affecting the spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction. Temporary skeletal anchorage devices in the missing mandibular first molar (ML-6) or missing deciduous mandibular second molar (ML-E) with missing succedaneous premolar spaces provided traction. METHODS: Forty-one mandibular third molars of 34 patients (10 male and 24 female; mean age 18.3 ± 3.7 years) that erupted after second molar protraction were included in this study. They were classified into upright (U) and tilted (T) groups. Linear and angular measurements were performed at the time of treatment initiation (T1) and of ML-6 or ML-E space closure (T2). Regression analyses were used to identify significant factors related to third molar uprighting. RESULTS: Nolla stage (odds ratio [OR] 4.1), sex (OR 0.003 for male), third molar angulation at T1 (OR 1.1), missing tooth space (OR 0.006), rate of third molar eruption (OR 23.3), and rate of second molar protraction (OR 0.2) significantly affected third molar uprighting. Age, third molar angulation at T1, rate of third molar eruption, and rate of second molar protraction were significant factors for predicting third molar angulation at T2. CONCLUSIONS: Available space for third molar eruption before and after second molar protraction is not associated with uprighting of erupting third molars. Older patients whose third molars are in greater Nolla stage, are in a more upright position at T1, and have a greater eruption rate have a greater chance for third molar uprighting. Alternatively, an increase in second molar protraction rate results in mesial tipping of the third molars.

Occlusal traits of 4-5-year-old Estonians. Parents' perception of orthodontic treatment need and satisfaction with dental appearance.

This study aims to evaluate the prevalence of occlusal traits and to assess parents'/caregivers' satisfaction with child's dental appearance and perception of orthodontic treatment need in 4-5-year-old Estonians. Clinical records and plaster casts of 390 children (190 girls and 200 boys, mean age 4.7 years, range 4 - 5 years) were analyzed. Assessed occlusal traits included deciduous canine and second molar sagittal relationship, overjet, overbite, crowding, midline diastema, crossbite, and scissor bite. Parents'/caregivers' opinions regarding their child's teeth were determined with a questionnaire. The most prevalent occlusal traits were symmetrical sagittal relationship in deciduous canines (78.2%) and molars (75.1%), Class I sagittal relationship in deciduous canines (69.7%) and midline diastema (67.7%). Asymmetrical sagittal canine relationship was registered in 21.8% deciduous canines and in 24.9% second deciduous molars. Parents'/caregivers' perceived orthodontic treatment need was related to Class III sagittal relationship in canines, increased overjet and overbite, negative overbite, and crossbite. Prevalence of most occlusal traits in Estonian children were in line with those reported in neighboring countries. Parents/caregivers were well able to observe occlusal traits that deviated from acceptable occlusion.

Dental occlusion and body balance: A question of environmental constraints?

BACKGROUND: In the past few years, growing interest was given to the relationship between the dental occlusion and the body balance. While most research focused on this relationship at static conditions, it is evident that the contribution of the sensory information for balance control is different depending on the environmental constraints. RESEARCH QUESTION: The aim of the present paper was to elucidate whether the stomatognathic system (SS) contributes differently on body balance regulation according to the presence of external disturbances. METHODS: Literature regarding the different sources involved in the proprioceptive information to the SS was reviewed. The influence of dental occlusion on balance control at different external environments was then explored. RESULTS: The main findings are: (a) a plausible evidence between the masticatory and cervical muscles can be described; (b) a reciprocal connection between the trigeminal and vestibular nuclei supports the influence of the SS on body balance; (c) traditionally, research involving the relationship between the SS and balance control has focused on strictly controlled situations, thus, ignoring the sensory reweighting which occurs depending on the external disturbances; and (d) the afferences of dental occlusion for balance control seem strengthened when more difficult conditions are present. CONCLUSION: Results of the present review suggest that afferent signals from dental occlusion effectively contribute to balance control when more external perturbations are present, that is unstable support surface, fatigue and tasks being performed. However, more studies are needed to elucidate the mechanisms by which dental occlusion may influence balance control focusing on different external environments.

Pre-operative parafunctional or dysfunctional oral habits are associated with the temporomandibular disorders after orthognathic surgery: An observational cohort study.

BACKGROUND: Temporomandibular disorders (TMDs) are frequent and disabling, and hence, preventing them is an important health issue. Combining orthodontic and surgical treatments for malocclusions has been shown to affect temporomandibular joint (TMJ) health. However, publications regarding the risk factors that predict negative TMJ outcomes after orthognathic surgery are scarce. OBJECTIVE: Present prospective cohort study was conducted to identify an association between pre-operative dysfunctional/parafunctional oral habits and the presence of TMD symptoms after orthognathic surgery. METHOD: We included 237 patients undergoing orthodontics and surgical treatment for malocclusions associated with dentofacial deformities within the Department of Oral and Maxillofacial Surgery of the University of Lille. Their parafunctional and dysfunctional oral habits were recorded through clinical examination along with the presence of TMD symptoms before and after the surgery. According to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) classification, the TMD symptoms studied were myalgia, arthralgia, disc displacement with or without reduction. RESULTS: Multivariate analysis revealed significant associations among bruxism (odds ratio [OR] 3.17 [1.066; 9.432]), lingual interposition (OR 4.241 [1.351; 13.313]), as well as primary swallowing (OR 3.54 [1.225; 10.234]) and the presence of postoperative symptoms of myalgia. Moreover, a significant association was observed between the presence of any dysfunctional oral habit and postoperative disc displacement with reduction (OR 4.611 [1.249; 17.021]). CONCLUSION: Bruxism and dysfunctional oral habits were shown to be risk factors for the presence of TMD symptoms also after combined orthodontic and surgical treatment. Treating such habits before orthognathic surgery should help prevent TMD.

Evaluation of masticatory muscle activity in patients with unilateral posterior crossbite before and after rapid maxillary expansion.

Objectives: The relationship between unilateral posterior crossbite (UPCB) and the possible asymmetric activation of the jaw muscles in children is still under debate. This study aimed at evaluating the jaw muscle activity of children with UPCB before and after rapid maxillary expansion (RME) by means of surface electromyography and a standardized sampling protocol. Subjects and methods: Twenty-nine children with UPCB (UPCB-group, mean age 9.6 ± 1.6 years) and 40 UPCB-free controls (Control-group, 10.5 ± 1.1) were recruited. The activity of the left and right anterior temporalis (AT) and superficial masseter muscles (MM) was recorded during maximum voluntary clenching and a chewing task (T0). In the UPCB-group, data were collected, also, after the correction of the UPCB with RME (T1) and 6 months later (T2), without any further treatment. Electromyographic indices comparing the activity of paired muscle were computed via software to estimate the extent of asymmetric AT and MM activity. Paired and unpaired t-test or Wilcoxon-signed rank and Mann-Whitney U test, ANOVA or Friedman test and chi-squared test were used in the statistical analysis. Results: Both groups presented with asymmetric activity of the muscles, which did not differ between groups (T0, all P > 0.05). The treatment determined a decrease in muscular activity (T1, P = 0.040), and a more asymmetric pattern of muscle activation during chewing (T1, P = 0.040), which returned similar to baseline values at T2 (all P > 0.05). Conclusions: UPCB does not contribute to an asymmetric activation of AT and MM during functional tasks. The treatment of UPCB by RME did not determine a more symmetric activity of the assessed muscles.

Influence of dental occlusion on the athletic performance of young elite rowers: a pilot study.

OBJECTIVES: The present study aimed to assess the influence of dental occlusion on body posture and the competitive performance of young elite rowers. METHOD: Dental occlusion disturbance devices were used to simulate dental malocclusions. We assessed the influence of malocclusion on the body balance, paravertebral muscle contraction symmetry, and muscular power of young elite rowers. A nonparametric permutation test for repeated measures ANOVA, a Cochran's Q test for paired data and a paired Student's t-test were used in order to statistically evaluate the influence of artificial occlusal disturbance on each factor. A force platform and a Dyno Concept 2 machine were used as measuring instruments. RESULTS: A total of 7 members of the "Pôle France Aviron" (age range of 15-17 years) were enrolled in the study. None of the body balance parameters was significantly influenced by the artificial occlusal disturbance. The interposition of an occlusal silicone splint significantly increased the proportion of athletes presenting asymmetric muscular contractions from 14.3% to 85.7% (p=0.025) and induced a significant 17.7% decrease in the athletes' muscular power (p=0.030). CONCLUSIONS: This study shows the negative impacts of an occlusal disturbance on the athletic performance of young elite rowers. The detection of malocclusion traits by regular occlusal monitoring would be of great interest in this population.

New application of dynamic magnetic resonance imaging for the assessment of deglutitive tongue movement.

BACKGROUND: Deglutitive motion of the tongue may function to maintain tooth position. However, the causation between abnormal patterns of orofacial muscle function and dental malocclusion remains unclear. To clarify the pathogenic mechanism of malocclusion, it is important to determine the relative positional relationship between the tongue tip and incisor edge or the dorsal tongue and palate during deglutition. Here, we assessed the utility of 3-T segmented cine-magnetic resonance (MR) imaging, combined with static MR images for hard tissue visualization, in assessing the relationship between the tongue and the surrounding tissues during deglutitive tongue movement. METHODS: Cine-MR images were acquired from three healthy female volunteers during deglutition who had no history of swallowing disorder or other chronic illness, normal alignment and occlusion, and a skeletal class I relationship. Three cine-MR images were taken during deglutition in accordance with an auditory cue for each volunteer. During static imaging, custom-made, contrast-medium-filled clear retainers were positioned in the mouth to allow visualization of the upper and lower incisors and hard palate boundaries. Static images were superimposed onto images of the three stages in deglutitive tongue movement, which were selected from a series of cine-MR images. These superimpositions were assessed five times by tracing cephalometric parameters to examine the reproducibility of the method. RESULTS: Traces varied little across repeated measurements, and all subjects had a similar pattern of dorsal tongue movement. Tongue-to-palate contact increased slightly during the first to second stage of swallowing and abruptly increased during the second to third stage, while the tongue tip position remained constant. CONCLUSIONS: Segmented cine-MR imaging combined with static MR images is useful for assessing soft tissue motion during deglutition. This method is particularly useful in dentistry to evaluate the relationship between tongue function and maxillofacial morphology in terms of orthodontic treatment and orofacial myofunctional therapy, and for improving tongue movement during speech therapy.

Vertical contact tightness of occlusion comparison between orofacial myalgia patients and asymptomatic controls: a pilot study.

OBJECTIVE: The association between occlusal contact and orofacial pain remains unclear. The aim of this study was to detect occlusal contact tightness by using a new method and to compare differences between patients and asymptomatic controls. METHODS: Fifteen female patients with orofacial myalgia and fifteen age- and sex-matched asymptomatic controls were enrolled. Occlusal contacts were recorded by making bite imprints. The numbers, sizes, and distributions of the contacts were detected by making photos of bite imprints after biting. The Mann-Whitney U test and ANOVA were used for statistical analysis. RESULTS: In myalgia patients, impact contacts at the molar regions were more frequent, larger in number and area size, and were distributed more on guiding cusps, compared with impact contacts in asymptomatic controls. CONCLUSION: Our new method revealed more prevalent and more severe impact contacts in orofacial myalgia patients, compared with asymptomatic controls.

Impact of orthognathic surgery on velopharyngeal function by evaluating speech and cephalometric radiographs.

BACKGROUND: Maxillary retrognathia is a well-known consequence of abnormal facial growth in patients with cleft lip and palate. Orthognathic surgery improves facial appearance and occlusion but may induce velopharyngeal insufficiency. The aim of this study was to evaluate the effect of orthognathic surgery on velopharyngeal function by using speech analysis and lateral cephalometric radiographs. PATIENTS AND METHODS: We conducted a retrospective study of 47 patients who underwent maxillary advancement ±â€¯mandibular setback between 2006 and 2016. Preoperative and 1 year postoperative audio recordings were blinded for scoring by three trained speech therapists. Preoperative and 1 year postoperative lateral cephalometric radiographs were used to obtain information about skeletal movement and its relationship with the velopharyngeal area. Correlations between speech outcomes and cephalometric radiographs were determined. RESULTS: Hyponasality improved significantly after surgery (p < 0.05), whereas hypernasality deteriorated significantly only in patients who underwent maxillary advancement alone (p < 0.05). No difference in speech parameters was found between patients with hypernasality or patients who had a pharyngoplasty preoperatively and the rest of the group. No correlation was found between the amount of maxillary advancement and hypernasality. A significant correlation (r < -0.49, p < 0.05) was found between the preoperative velar length and hypernasality postoperatively. CONCLUSIONS: Maxillary advancement has a negative impact on velopharyngeal function, whereas bimaxillary surgery seems to protect from deterioration. No difference was found in the amount of maxillary advancement or in velopharyngeal measurements between the Le Fort I group and the bimaxillary group. A short soft palate is a predictor of hypernasality after orthognathic surgery.