Neutral Occlusion Research Articles

Prevalence of sleep-disordered breathing in children and adolescents with large horizontal maxillary overjet due to mandibular retrognathia: a case control study.

The aim of the study was to examine the prevalence of sleep-disordered breathing (SDB) in children and adolescents with large overjet due to mandibular retrognathia compared to a control group. In this case-control study children with large overjet ≥ 6 mm due to mandibular retrognathia (study group) were compared to a group with neutral occlusion (controls). All participants underwent respiratory polygraphy (PG) and questionnaires regarding sleepiness and snoring. Differences across groups were tested by: Chi-square, general linear model adjusted for age, sex, and body mass index (BMI), and Mann-Whitney test. Differences in results of PG were also tested by general linear model adjusted for age, sex, and BMI according to severity of mandibular retrognathia. Thirty-seven (19 male;18 female, median age 12.3 years) participants were included in the study group and 32 (16 male;16 female, median age 12.2 years) in the control group. No significant difference in SDB assessed by PG or questionnaires between the groups was found even though the snore index was higher in the study group (p=0.051). The snore index was higher than the parent-reported snoring. Respiration rate was significantly reduced in the study group (p=0.043), and estimated sleep time efficiency was significantly reduced in males compared to females (p<0.001). No significant differences in SDB were found between the groups even though the snore index was higher in the study group. The snore index of the PG was higher than the parent-reported snoring. Estimated sleep time efficiency was reduced in males. The study improves the understanding of risk of SDB in non-obese children with large overjet due to mandibular retrognathia and may contribute to an interdisciplinary approach of risk assessment of SDB in children with malocclusion. NCT04964830.

The influence of oral breathing type on the formation of occlusion in students of general educational institutions of the Ministry of Defense of Russian Federation

BACKGROUND: Among students of general education organizations of the Ministry of Defense of Russian Federation, respiratory diseases is the leading cause of general somatic morbidity and amount to 1543.5‰. When examining students, pathology of the upper respiratory tract is often diagnosed, such as partial or complete obstruction of the nasopharynx and/or oropharynx. Against this background, the formation of the oral type of breathing occurs, which affects the state of general somatic health and growth and development of the facial skeleton. AIM: To evaluate the influence of oral breathing on the dentoalveolar and gnathic parameters of the maxillofacial region in students of educational institutions of the Ministry of Defense of Russian Federation. MATERIALS AND METHODS: This study examined two groups of students aged 13–15 years from the St. Petersburg Cadet Military Corps named after Prince Alexander Nevsky: group 1, 30 cadets with oral breathing, and group 2 (control), 30 cadets with nasal breathing. All patients underwent an examination of the oral cavity, a photo protocol, scanning of the dentition, and cone-beam computed tomography of the skull bones and first cervical vertebrae in natural occlusion with a resolution of 17×15. The data were checked for normal distribution of features. The article presents arithmetic averages and their errors (M±m). RESULTS: All the examined group 1 students with oral breathing were diagnosed with distal bite in combination with other dental anomalies: combined anomalies in the form of distal bite and disocclusion in the frontal region (56.7%); close position of the anterior group of teeth (93.3%); and unilateral (30.0%) and bilateral (13.3%) cross occlusion due to narrowing of the upper and lower jaws. In most cases, the group 1 students were diagnosed with a gnathic form of dentoalveolar anomaly (ANB parameter, 6.6±2.4°; Beta parameter, 24.7±3.1°) against the background of retroposition of the lower jaw (SNB parameter, 75.4±2.8°) and a decrease in the length of the lower jaw (Co–Gn parameter, 106.0±2.8 mm). All the group 2 (control) students had a neutral occlusion with a normal position of the upper jaw (SNA parameter, 81.4±2.1°) and a normal position of the lower jaw (SNB parameter, 79.8±1.6°) and the first skeletal class (ANB parameter, 2.3±1.1°; Beta parameter, 30.1±2.5°). CONCLUSION: Oral breathing is accompanied by the development of disto-occlusion with the formation of a vertical gap in combination with cross occlusion in the lateral sections and close position of the anterior group of teeth against the background of a narrowing of the upper and lower jaws. Prompt diagnosis of upper respiratory tract pathology prevents the development of dentoalveolar and gnathic disorders of the maxillofacial area. To treat patients with oral breathing, a simultaneous approach is required with the involvement of a full-time otolaryngologist at the medical center.

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

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). 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. 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. 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. 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.

Sleepiness in children with severe malocclusion compared with in children with neutral occlusion

The study aimed to compare daytime sleepiness in children with severe malocclusion with healthy children with neutral occlusion (controls) and to analyze associations between daytime sleepiness and craniofacial morphology in children with severe malocclusion. In 120 children with severe malocclusion (73 girls, 47 boys; mean age, 11.96 years; mean body mass index [BMI] score, 18.97 kg/m2) and 35 controls (18 girls, 17 boys; mean age, 11.97 years; mean BMI score, 20.28 kg/m2), sleep and daytime sleepiness were recorded using Epworth Sleepiness Scale and Berlin Questionnaire. Occlusion was registered clinically, and craniofacial morphology was assessed on lateral cephalograms. Differences in daytime sleepiness and sleep between the groups and associations between daytime sleepiness and sleep and craniofacial morphology were analyzed by a general linear model adjusted for age, gender, and BMI score. Daytime sleepiness occurred significantly more often in children with malocclusion than in control subjects (P= 0.015). There was a tendency for children with malocclusion to feel extremely tired during the day more often than controls (P= 0.054). There was no significant difference between the groups in sleeping hours during night-time, but the amount of sleep was negatively associated with age (P<0.001) and BMI score (P= 0.004). Only maxillary inclination was significantly associated with daytime sleepiness (P= 0.043). Daytime sleepiness occurred significantly more often in children with severe malocclusion than in those with neutral occlusion, and the association between daytime sleepiness and craniofacial morphology may exist. The results might prove valuable in interdisciplinary collaboration between medical doctors and orthodontists in diagnostics, prevention, and treatment of children at risk for sleep-disordered breathing.

The impact of masticatory muscles hypertonicity on the bite formation

Was to assess the impact of masticatory muscles hypertonicity on the bite formation. The study comprised 60 patients aged 7-14 years. Group 1 consisted of 20 individuals with Angle class 1 occlusion without masticatory muscle hypertonicity. Group 2 comprised 20 patients with class II malocclusion with hypertonicity of the masticatory muscles, group 3 - 20 patients class II malocclusion and no hypertonic masticatory muscles. All patients were examined according to common diagnostic protocol that included electromyography of the temporal and masticatory muscles at rest and in dynamics). In group 1 the mean IMPACT at rest was 242.8±133.6 µV, IMPACT during contraction was 880.50±201.5 µV; in group 2 - 797.9±413.0 and 1561.23±568.0 μV; in group 3 - 236.7±93.5 and 955.60±295.5 μV, correspondingly. The ratio of the activity of the temporal muscles to the masticatory muscles with neutral occlusion at rest correlates as 1:09, with compression 1:1. In patients with distal occlusion and the presence of hypertonicity at rest, the temporal muscles correspond to the chewing proper as 1:0.8, and with compression 1:09. The estimated ratio can contribute to the retroposition of the mandible, as well as inhibition of the growth of the mandible in the sagittal direction.

Clinical condition of teeth and dentition in children and adolescents with cerebral palsy

BACKGROUND: Literature and statistical data reveal the increasing incidence of psychoneurological diseases (PND) and thus dental pathologies with PND in children and adolescents. Thus, the authors examined the structures and frequency of dental defects and deformities in patients with PND. Children and adolescents with PND aged 718 years are at high risk for the development of dental pathologies, and oxidative stress and immune system disorder present major associations with the pathogenesis of dental pathologies.&#x0D; AIM: To determine the structure and frequency of dental defects and deformities in children and adolescents with PND and study the etiopathogenetic factors and mechanism of pathology formation to guide the development of preventive measures.&#x0D; MATERIAL AND METHODS: The study comprehensively analyzed the data of 299 patients aged 718 years, of which 143 were diagnosed with PND based on the International Classification of Disease 10th Revision (main group; МG) and 156 somatically healthy patients with dental pathologies (control group; CG). The participants were divided into two subgroups: 75 patients aged 712 years (52.44%; МG-1) and 68 patients aged 1318 years (47.55%; МG-2) from the main group (MG) and 65 (41.66%; CG-1) and 91 (58.33%; CG-2) patients from the CG of the respective age groups.&#x0D; RESULTS: The incidence rates of caries in the temporary teeth of MG-1 and CG-1 were 97.33% and 84.61% and in the permanent teeth of MG-2 and CG-2 were 95.58 and 87.91%, respectively. In the pre-eruptive period, the rates of dental lesions were as follows: hypoplasia, 20.97%; impaired dentition, 49.65%; primary adentia, 47.55%; anomalies of the completeness of teeth, 64.33%; endemic fluorosis of teeth, 2.79% in patients with PND; and 12.17%, 12.17%, 26.92%, 11.53%, and 0.6% in children and adolescents in CG, respectively (p 0.0001): disappearance of dental hard tissues, 9.09%; dental injuries, 24.47%; enamel necrosis, 7.7%; enamel erosion, 17.5% of patients with MG. In children and adolescents of CG, only tooth trauma was noted in 7.7% and enamel necrosis in 1.3%. In patients with PND, 49.6% had distal occlusion; 37.8%, cross occlusion; 31.6%, neutral occlusion; 29.9%, deep incisor occlusion; 25.9%, deep incisor malocclusion; 54.5%, narrowing of the lower dentition; 43.3%, crowding of teeth in the lower jaw; 26.6%, diastemas; and tremas, 23.8%.&#x0D; CONCLUSION: Non-carious lesions of the teeth and a shift in the timing of the development of temporary and permanent teeth are more common in MG than in CG and lead to impaired dental anatomy and disrupt the aesthetics of smiles, speech, etc. Moreover, hypertrophic gingivitis and local periodontitis were characteristic of children with severe PND, who are at high risk for dental pathologies associated with oxidative stress and genetically related immune system disorders, especially in older children with PND.

Bite Force, Occlusal Contact and Pain in Orthodontic Patients during Fixed-Appliance Treatment.

Previously, bite force, occlusal contact and pain were investigated in orthodontic patients with moderate-to-severe malocclusion, but not in patients with minor malocclusion. The purpose of this study was to investigate changes in bite force, teeth in occlusal contact and pain in orthodontic patients with minor crowding before orthodontic treatment (T0), after bonding (T1), during treatment (T2), post-treatment (T3) and during retention (T4). In total, 27 patients (21 females, 6 males, median age 15.3 years) with neutral occlusion and normal craniofacial morphology were treated with non-extractions and fixed appliances. Differences in the registered data were analysed by a mixed linear model with repeated measures. Bite force and teeth in occlusal contact significantly decreased between T0 and T1 (p < 0.0001, respectively) and between T0 and T2 (p < 0.01, respectively). Bite force and teeth in occlusal contact significantly increased between T1 and T4 (p < 0.05, p < 0.0001, p < 0.001, respectively) and between T2 and T4 (p < 0.05, p < 0.0001, p < 0.01, respectively). No significant difference in pain was found. The results indicate that bite force and teeth in occlusal contact significantly decreased during treatment and reached baseline level at retention. The findings may prove valuable for informing orthodontic patients with minor malocclusion.

Orofacial myofunctional disorder characteristics in cerebral palsy and their treatment methods

Relevance. The variety of clinical manifestations of orofacial myofunctional disorders in cerebral palsy determines the need to improve diagnosis and treatment approaches. According to the authors, the planning of rehabilitation measures for children with cerebral palsy and orofacial pathology should be individual.Materials and methods. 120 children (mean age 8.7 years) with cerebral palsy and orofacial myofunctional disorders participated in the study with subsequent assessment of dental and neurological statuses during treatment, prevention and rehabilitation.Results. The study established correlations between general motor pathology, malocclusion and changes in the speech organs depending on the clinical form of cerebral palsy. Spastic dysarthria and anarthria were detected in 82 cases, age-appropriate speech and language development - in 38. Occlusion assessment revealed malocclusion in 88 subjects, neutral occlusion – in 32.Conclusions. Modern approaches to the treatment of malocclusion and orofacial myofunctional disorders in children with cerebral palsy allow increasing the effectiveness and quality of rehabilitation, organizing the sequence and continuity of specialist actions in a multidisciplinary rehabilitation team.

Craniofacial Morphology and Upper Airway Dimensions in Patients with Hypermobile Ehlers-Danlos Syndrome Compared to Healthy Controls.

ABSTRACTObjectivesThe aims of the present case-control study were to compare craniofacial morphology, airway minimum cross-sectional area and airway volume between patients with hypermobile Ehlers-Danlos syndrome and healthy controls. Material and MethodsThe sample comprised 18 hypermobile Ehlers-Danlos syndrome (hEDS) patients (16 females, 2 males, mean age 34.1 [SD 10.35] years), clinically diagnosed and genetically tested in order to exclude other types of EDS, and 16 controls (14 females, 2 males, mean age 37.9 [SD 10.87] years) with neutral occlusion and normal craniofacial morphology. Craniofacial morphology was assessed on lateral cephalograms. Minimum cross-sectional area and upper airway volume were assessed on cone-beam computed tomography and analysed by standard and well-validated methods. Differences were tested by logistic regression analysis adjusted for age, gender and body mass index (BMI).ResultsNo significant differences in craniofacial morphology were found between hEDS patients and controls. Airway minimum cross-sectional area (P = 0.019) and airway volume (P = 0.044) were significantly smaller in hEDS patients compared to controls. When adjusted for age, gender and BMI no significant differences were found. However, minimum cross-sectional area was almost significant (P = 0.077). ConclusionsThe craniofacial morphology and airway dimensions of hypermobile Ehlers-Danlos syndrome patients were comparable to controls, with a tendency towards a smaller minimum cross-sectional area in the hypermobile Ehlers-Danlos syndrome group. The results may prove valuable for understanding the effect of hypermobile Ehlers-Danlos syndrome on craniofacial morphology and the upper airways.

TO JUSTIFY A DIFFERENTIATED APPROACH TO PRESERVATION OF THIRD MOLARS DURING ORTHODONTIC TREATMENT BY DETERMINING THEIR CONDITION AND POSITION IN THE JAW

TO JUSTIFY A DIFFERENTIATED APPROACH TO PRESERVATION OF THIRD MOLARS DURING ORTHODONTIC TREATMENT BY DETERMINING THEIR CONDITION AND POSITION IN THE JAW

Özel Bakım Gereksinimi Olan Bireylerde Ağız-Diş Bulgularının Değerlendirilmesi

Amac: Ozel bakim gereksinimi olan cocuklarda agiz sagligi problemleri, genel saglik sorunlarina ek olarak ortaya cikan buyuk bir saglik sorunudur. Bu calismanin amaci, Istanbul ilinde ozel egitim veren okullarda muayene edilen ozel bakim gereksinimi olan bireylerin agiz-dis sagligi verilerinin degerlendirilmesidir. Gerec ve Yontemler: Bu kesitsel calisma Istanbul Universitesi Dis Hekimligi Fakultesi Pedodonti Anabilim Dali ile Istanbul Universitesi Dis hekimligi Fakultesi Engelsiz Gulusler Ogrenci Kulubu sosyal sorumluluk projesi olarak Istanbul ili icerisinde ozel egitim veren okullarda gerceklestirildi. Agiz ve dis sagligi taramalari icin her bir tarama oncesi ozel olarak izin alindi. Agiz muayenesi gun isiginda tek kullanimlik ayna, sond ve presel yardimi ile yapildi. Muayenede cocuklarin yaslari, engel durumlari, ilac kullanip kullanmadiklari, dis curugu varligi, dental travma varligi, dis sikma ve malokluzyon durumlari kaydedildi. Verilerin degerlendirilmesinde uygun istatistiksel testler/analizler kullanildi ve anlamlilik duzeyi 0,05 olarak belirlendi. Bulgular: 42’sinde otizm, 111’inde mental retardasyon ve 10’unda Down sendromu olmak uzere 163 ozel bakim gereksinimi olan bireyin agiz ici muayenesi yapildi. Her uc grubun DMFT ve dft ortalamalari arasinda istatistiksel olarak anlamli bir fark bulunmadi (p>0,05). Down sendromlu bireylerde notral okluzyon gorulme orani, otizmli bireylerden daha dusuk bulundu (p<0,05). Sinif II malokluzyon icin gruplar arasi fark gorulmezken, Sinif III malokluzyon gorulme oraninin zihinsel engellilerde otizmlilere gore daha yuksek, Down sendromlu bireylerde hem zihinsel engelli bireylerden hem de otizmli bireylerden daha yuksek oldugu goruldu (p<0,05). Sonuc: Ozel bakim gereksinimi olan bireylerin dis curukleri, malokluzyon, dislerde asinma, bruksizm, dental travma ve agiz-dis sagligi acisindan takip edilmeleri ve agiz-dis sagligi acisindan yakindan takip edilmeleri gerekmektedir.

Standartized indicators of masticatory muscles functional activity for patients with transversal intermaxillary anomalies

The study involved patients with a normal intermaxillary ratio and with a transversal maxillary deficiency. The age of the patients varied between 25 and 40 years. In all the examined patients, orthodontic treatment had not been previously performed. The group of patients with transversal anomalies involved 45 clinical cases, the group of patients with neutral occlusion involved 42 cases. Superficial electromyographic research was carried out according to the method of Professor V.F. Ferrario. The comparison of the functional activity parameters of the maxillofacial region using standardized coefficients of surface electromyography revealedsignifica abnormal indicators in the patients with transversal anomalies compared to the patients with neutral occlusion. This fact must be taken into account when planning orthodontic treatment.

INTERACTION BETWEEN DENTO-MAXILLOFACIAL ANOMALIES AND GENERAL-SOMATIC HUMAN CONDITION (LITERATURE REVIEW)

The main task of modern orthodontics is to create a balanced and morphologically stable occlusion in harmony with facial aesthetics and functional adaptation. Over the last decade, there has been a clear trend towards an increase in the prevalence of malocclusion, which reaches 80% according to current scientific literature and sometimes it exceeds this percentage. Researchers note a constant and statistically significant correlation between the permanent occlusion pathology and the state of somatic health in adolescence. On the other hand, the interdisciplinary approach is one of the most urgent tasks of modern orthodontics and a constant object of searching for new methods of diagnosis and treatment.&#x0D; The aim of the study is to investigate the relationship between dento-facial anomalies and somatic pathology.&#x0D; Materials and methods. Literary sources were reviewed on the relationship of malocclusion with the general diseases and the obtained data were analysed.&#x0D; Discussion. The human body is a biological system consisting of interconnected and subordinate elements. The peculiarities of their structure and relations are subordinated to their functioning as part of a single integral mechanism. Most authors note the existence of a direct interconnection between the general somatic pathology and anomalies of the dento-facial system. When analysing the literature data, several major groups of diseases that have the greatest impact on the development of the dento-facial system are clearly distinguished: diseases of the ENT organs, the gastrointestinal tract, endocrine and musculoskeletal systems. At present the scientists have substantiated the concept of commonality of factors that shape both dental status and state of somatic health. An increase in the frequency of dento-facial anomalies and deformations in 1,6-2,3 times is noted in disorder of the musculoskeletal system. In this category of children, deep incisor occlusion, distal occlusion and neutral occlusion with anomalies of individual teeth predominate. In children with scoliosis, 72.9-84.3% of cases are diagnosed with dento-facial anomalies and deformations. The position of the jaws has an effect on the spatial orientation of the head and this in turn affects the position of other structures of the body. Some researchers point to the “anterior” position of the head of patients with dysfunction of the temporomandibular joints associated with the shortening of the extensors of the sternocleidomastoid muscles. Research showed that in 89,3% of cases, children with bronchial asthma have dento-facial anomalies. Adolescence is one of the critical periods of human life, since it is precisely in adolescence that the neuroendocrine system begins to function, and sex hormones which affect the development of many body systems and the formation of reproductive health are produced. Under the action of steroid hormones, an active development of the musculoskeletal system occurs, which is manifested by the acceleration of total body growth and dento-maxillofacial growth. Insufficient secretion of estrogen leads to impaired bone mineralization and may cause abnormalities in the maxillofacial area. Impaired growth and development of the dento-facial system was detected in case of juvenile rheumatoid arthritis. In juvenile idiopathic arthritis, one third of the patients were examined. The skeletal pathology of the Angle I class, as well as impaired functional state of the TMJ were diagnosed. Thyroid hormone and thyroxin stimulates growth in the sphenoid-occipital synchondrosis, nasal cartilage and the growth of the upper jaw in the area of bone sutures, thereby determining of the size and position of the upper jaw. As a result of a decrease in thyroxin level, there is a delay in craniofacial growth, disproportional development, retroposition of the upper jaw and decrease in the length of the mandible.&#x0D; Thus, the correlation of malocclusion in children and adolescents with common diseases arise. Therefore, the diagnosis, tactics of treatment and prevention of dental anomalies and deformities should be considered in the context of the integrity of the unformed organism of the child, the interdependence of the form and functions of its organs and systems.

Upper cervical spine and craniofacial morphology in hypohidrotic ectodermal dysplasia.

Morphological deviations in the upper cervical spine and craniofacial morphology in patients with X-linked hypohidrotic ectodermal dysplasia (XLHED) were compared to non-syndromic controls. All children and adolescents with genetically verified XLHED, registered at the Resource Centres for Oral Health in Rare Diseases, who met the inclusion criteria, were included. The group thus comprised 15 XLHED patients (3 girls and 12 boys, aged 8-16years, mean 11.2years). The control group comprised 22 non-syndromic pre-orthodontic children (14 girls and 8 boys aged 9-16years, mean 11.9years) with agenesis of one tooth, neutral occlusion and normal craniofacial morphology. The craniofacial and upper spine morphology was analysed on lateral cephalograms by standard methods. Differences between XLHED patients and controls were tested and adjusted for age and gender by multiple regression analyses. Morphological deviations in the upper spine occur significantly more often in XLHED patients compared to controls (60 vs. 9.1%; p < 0.01). The cranial base angle (n-s-ar, p < 0.05), sagittal jaw relationship (ss-n-pg, p < 0.001), maxillary inclination (NSL/NL, p < 0.001) and mandibular inclination (NSL/ML, p < 0.01) were significantly smaller in XLHED patients compared to controls. The mandibular prognathia (s-n-pg) was significantly larger in XLHED patients compared to controls (p < 0.05). The upper spine and the craniofacial morphology were different in XLHED patients compared to controls. The results of this study may contribute to a further understanding of the craniofacial and spinal phenotypic spectrum in patients with XLHED and thus have implications for diagnosis and treatment planning of these patients.

Definition of myofunctional disorders in children in the period of the replacement bite

The article concerns the problem of myofunctional disorders in distal occlusion in the replacement bite. The authors conducted analysis of indicators of bioelectric activity of muscles of the maxillofacial region of 100 children. The authors describe the potentials of the masticatory and temporal muscles in children 8 to 12 years with the occurrence of distal occlusion and with neutral occlusion.

Interaction between deglutition, tongue posture, and malocclusion: A comparison of intraoral compartment formation in subjects with neutral occlusion or different types of malocclusion.

To test the null hypothesis of no significant difference in terms of intraoral pressure curve characteristics assessed simultaneously at the subpalatal space (SPS) and the vestibular space (VS), during different oral postures, between four groups with either an Angle Class II/1 (II1), Angle Class II/2 (II2), anterior open bite (O) malocclusion, or a neutral occlusion control group (I). Intraoral pressure recordings were performed simultaneously in the VS and SPS of 69 consecutive subjects (nII1 = 15; nII2 = 17; nO = 17; nI = 20; mean age/standard deviation 18.43/6.60 years). Assessments included defined sections of open mouth posture (OMP, 30 seconds), anteriorly closed mouth condition (60 seconds), dynamics by a tongue-repositioning maneuver (TRM, 60 seconds), swallowing, and positive pressure generation (PP, 10 seconds). Interactions of malocclusion, compartment location, and posture on pressure curve characteristics were analyzed by Kruskal-Wallis and Mann-Whitney U-tests, adopting an α level of 5%. Globally significant group differences were detected at the VS (plateau duration and median peak heights during TRM; area under pressure curve [AUC] during PP) and SPS (AUC during TRM and PP). Subjects with anteriorly nonopen dental configurations (groups I and II2) were able to keep negative pressure levels at the VS for longer time periods during TRM, compared to groups O and II1. The null hypothesis was rejected for mean VS plateau durations and peak heights and for SPS AUC. Negative pressures at the VS may stabilize outer soft tissues passively and may explain the dental arch form shaping effect by mimic muscles.

A pilot study of upper airway management using a remote-controlled artificial muscle device during propofol anesthesia

Study objectiveTo test the hypothesis that the jaw closure using a pneumatic actuator device affect airway collapsibility and resistance during propofol anesthesia. DesignProspective, randomized study. SettingUniversity-affiliated hospital. PatientsSix male subjects were included in the present study. InterventionWe used pressure-flow relationships to evaluate critical closing pressure (PCRIT) and upper airway resistance in different conditions of body and head position. Anesthesia was induced and maintained with a propofol infusion, targeting a constant blood concentration of 1.5 to 2.0μg/mL to establish an adequate depth of anesthesia, with patients breathing spontaneously through a nasal mask. An air-inflatable pneumatic actuator was used to achieve jaw closure. Nasal mask pressure was intermittently reduced to evaluate upper airway collapsibility (passive PCRIT) and upstream resistance under 4 different conditions: (1) neutral occlusion at 0-cm head elevation (baseline), (2) jaw closure at 0-cm head elevation, (3) neutral occlusion at 6-cm head elevation, and (4) jaw closure at 6-cm head elevation.PCRIT and upstream resistance under each condition were compared using 1-way analysis of variance. P<.05 was considered significant. MeasurementsThe pressure and inspiratory flow at the subjects' nose mask were recorded. Polysomonographic parameters (electroencephalograms, electrooculograms, submental electromyograms, and plethysmogram) were also recorded. Main resultsThe combination of 6-cm head elevation with jaw closure using the pneumatic actuator decreased upper airway collapsibility (PCRIT≈−3.0 cm H2O) compared to the baseline position (PCRIT≈−1.2 cm H2O; P=.0003). ConclusionWe demonstrated that jaw closure using an air-inflatable pneumatic actuator device can produce substantial decreases in upper airway collapsibility and maintain upper airway patency during propofol anesthesia.

Stability of orthodontic correction: preconditions of relapses caused by occlusal forces

The aim of the study was to determine the prognostic criteria of orthodontic treatment success in a group of patients with crowded teeth position and a neutral occlusion. The study included 150 patients (123 female and 27 male) with the average follow-up of 10.02±2.88 years and average retention phase of 6.15±2.98 years. Teeth positions, dental arches form, occlusal contacts and periodontal status were studied. Dentition changes after orthodontic correction should be considered as a result of adaptive compensatory balance. The resultant force acting on teeth and the direction of it determine displacement of teeth. The leading relapse precontidion induced by the occlusal forces was the interference of the canines, mandible deviation and asymmetry, muscle tone disorders.

Cranial morphology and facial type: Is it appropriate to describe the face using skull terminology?

BackgroundTerminology that comes from the anthropometric index, which is indicative of the form of the skullcap, is widely used to describe the face in orthodontics. Using this terminology assumes that the face and skull always follow the same pattern of morphology. The aim of this study was to test the hypothesis that the morphology of the face corresponds with the morphology of the skull. MethodsMeasures related to the cranial and facial indexes were taken randomly from 51 dry human skulls with neutral occlusion, selected from a larger collection. Skulls were classified, according to the cranial index, as dolichocephalic (<76.0), mesocephalic (76.0–<81.0), or brachycephalic (≥81.0) and according to the facial index as leptoprosopic (≥90.0), mesoprosopic (85.0–<90.0), or euryprosopic (<85.0). The McNemar-Bowker test and linear regression models were used to assess the relationship between the cranial and facial morphologies. ResultsThe correspondence values between the cephalic and facial index ratings in expected cephalofacial pairs (brachycephalic and euryprosopic, mesocephalic and mesoprosopic, and dolichocephalic and leptoprosopic) were observed to be only 3.9%, 7.8%, and 13.7%, respectively. Coefficients of linear regression confirmed a weak influence of facial measurements on the morphology of the skull. ConclusionsFacial morphology exerts little influence on skull shape and, therefore, does not support the widespread use of a terminology derived from the cranial index. The development of a standardized diagnostic terminology is timely given the increasing use of electronic records in health research and facilitating data sharing across different areas.

Jaw-motor effects of experimental jaw-muscle pain and stress in patients with deep bite and matched control subjects

ObjectiveThe effect of experimental jaw-muscle pain and stress on masticatory muscle activity in TMD-patients has been discussed. Furthermore, associations between TMD and deep bite patients have been studied. Accordingly in the present study, comparison of EMG responses at rest, maximal clenching, during evoked pain and stress between deep bite patients and controls was investigated. DesignIn 30 deep bite patients and in 30 sex-/age-matched controls with neutral occlusion EMG activity was recorded bilaterally from masseter and anterior temporalis muscles before and during evoked pain and before and during a stress task. Evoked pain was induced by injections of glutamate into the masseter (local pain) and brachioradialis (remote pain) muscles and resting EMG activity was recorded before and after 1, 2, 3, 4, 5 and 10min. A precision task was used to simulate a stressful condition and EMG activity was recorded twice during the task. Maximal EMG activity was recorded during maximal clenching. ResultsResting and maximal EMG activity were significantly different between groups and age with no gender differences. EMG activity during local pain and during the precision task were significantly different between groups, gender, age and time, whereas no time effect was found for the EMG activity during remote pain. ConclusionsPatients with deep bite have significantly different jaw motor responses to painful stimulation of the trigeminal region and manual precision tasks suggesting a differential integration of both somatosensory and behavioural stimuli.