Dinámica relacionada con la edad de parámetros antropométricos craneofaciales y su asociación con el tipo de oclusión dental en seres humanos de ambos géneros de: 17 a 24 años / Age-related dynamics of craniofacial anthropometric parameters and their association with the type of dental occlusion in humans of both genders aged 17­24 years

El propósito del estudio fue analizar la dinámica de los cambios relacionados con la edad de las estructuras craneofaciales de acuerdo con los parámetros antropométricos en hombres y mujeres de 17 a 24 años, y determinar la correlación, definida por análisis antropométrico, entre las formas de morfología craneofacial y los tipos de anomalías dento-maxilares. Materiales y métodos: Se realizó un examen antropométrico de 851 individuos (418 hombres y 433 mujeres) de 17 a 24 años y la evaluación de 45 mediciones entre puntos de referencia de tejidos blandos. Además, se realizó una valoración odontológica general, que incluyó la clasificación de las anomalías dentomaxilares. Resultados: Se detectó que el ancho de la cabeza, el largo de la cabeza, así como el ancho de la mandíbula y el ancho morfológico facial en las hembras alcanzan valores máximos de crecimiento a la edad de 20 años. Además, se obtuvieron datos que indicaron la continuación del crecimiento de los parámetros antropométricos craneofaciales mencionados anteriormente en los hombres durante el período de transición de la adolescencia a la edad adulta. Conclusión: la mordida profunda distal es la anomalía dento-maxilar (DMAn) más común en hombres y mujeres bielorrusos de 17 a 24 años. Junto con esto, la frecuencia de ocurrencia de maloclusión de mordida profunda distal en individuos con morfología craneofacial dolicocefálica es mayor en hombres y mujeres en comparación con otras formas de morfología craneofacial. La mordida profunda distal se acompaña de la disminución de los parámetros antropométricos de la altura facial, en comparación con la mordida mesial y abierta en la que hay un aumento estadístico. Además, se observa una disminución estadística en el valor de la profundidad facial inferior en individuos diagnosticados con mordida distal, en comparación con individuos con mordida mesial y normal. Estos resultados obtenidos del análisis antropométrico podrían ser útiles en el diagnóstico de anomalías dentofaciales y dento-maxilares, y en la simulación de resultados de tratamiento estéticamente estables.

The purpose of the study was to analyze the dynamics of age-related changes of craniofacial structures according to anthropometric parameters in males and females aged 17­24 years, and to determine the correlation, defined by anthropometric analysis, between forms of craniofacial morphology and the type of dento-maxillary anomalies. Materials and Methods: An anthropometric examination of 851 individuals (418 males and 433 females) aged 17­24 years and the evaluation of 45 measurements between soft tissue landmarks was performed. In addition, general dental assessment was conducted, which included the classification of the dento-maxillary anomalies. Results: It was detected that the head width, head length, as well as the mandible width, and the morphological facial width in females reach growth peak values at the age of 20 years. Furthermore, data was obtained which indicated growth continuation of the stated above craniofacial anthropometric parameters in males during the transitional period from adolescence to adulthood. Conclusion: Distal deep bite is the most commonly prevailed dento-maxillary anomalies (DMAn) in Belarusian men and women aged 17­24 years. Along with this, the frequency of distal deep bite malocclusion occurrence in individuals with dolichocephalic craniofacial morphology is higher in men and women when compared to other forms of craniofacial morphology. Distal deep bite is accompanied by the decrease of facial height anthropometric parameters, when compared to mesial and open bite in which there is a statistical increase. Moreover, a statistical decrease in the value of the inferior facial depth is observed in individuals diagnosed with distal bite, when compared to individuals with mesial and normal bite. These obtained results from anthropometric analysis could be useful in diagnosis of dentofacial and dento-maxillary anomalies, and in the simulation of aesthetically stable treatment results

Anterior open bite due to temporomandibular joint osteoarthrosis with muscle dysfunction treated with temporary anchorage devices.

Skeletal Class II high-angle open bite is often accompanied by osteoarthrosis of the temporomandibular joint (TMJ-OA). This type of malocclusion is challenging to correct, and it has been reported that patients with TMJ-OA treated with orthognathic surgery often experience skeletal relapse and a poor prognosis. This case report describes the treatment of a 25-year-old woman with retrognathia and TMJ-OA, whose masseter and temporal muscle activities were weak. Temporary anchorage devices were placed in the maxilla and the mandible, and the first molars were intruded. We used improved superelastic nickel-titanium alloy wires with tip-back bends for both arches, and intermaxillary elastics were used to upright the molars. After treatment, intrusion of the maxillary and mandibular first molars, counterclockwise rotation of the mandible, and improvement of occlusion and profile had been achieved. The patient's condyles were repositioned into ideal positions, and masticatory muscle activity was augmented and balanced. After 2 years of retention, the mandibular and condylar positions were stable, and acceptable occlusion was maintained without recurrence of TMJ symptoms; harmonious activity of the masticatory muscles was retained. The findings of this case report suggest that molar intrusion using temporary anchorage devices for a patient with severe anterior open bite and TMJ-OA may be useful for improving stomatognathic function, occlusion, and facial esthetics.

Masticatory evaluation of anterior open bite malocclusion using the colorimetric capsule method.

This pediatric study aimed to assess the masticatory function of patients with anterior open bite through a method that utilizes colorimetric capsules. The sample consisted of 106 patients aged 7-11 years, of whom 51 presented with anterior open bite (experimental group) and 55 presented with normal overbite (control group). The colorimetric capsules used in this evaluation contained basic fuchsin granules, which were used to produce a solution after they were ground during chewing. Each patient was asked to chew 1 capsule for 20 seconds. The absorbance of the obtained solutions was analyzed with a spectrophotometer. Greater masticatory efficiency is directly related to the greater light absorbance of a solution, since light absorbance increases with solution concentration. A nonparametric Wilcoxon test indicated that the solutions obtained from the control group presented significantly greater light absorbance than did those from the experimental group (P < 0.05). Therefore, children with an anterior open bite exhibited less masticatory efficiency than those with a normal overbite.

Evaluation of Long-term Stability of Vertical Control in Hyperdivergent Patients Treated with Temporary Anchorage Devices.

This study aims to evaluate the long-term stability of vertical control in hyperdivergent patients treated with temporary anchorage devices. The sample included 20 hyperdivergent patients without anterior open bite. The temporary anchorage devices were used to intrude the upper incisor and molars for vertical control. Lateral cephalograms were established prior to treatment, immediately after treatment, and during retention. The upper molars and incisors were intruded by 1.33 mm and 1.41 mm after treatment (P<0.05). U6-PP increased by 0.11 mm and 0.23 mm during the first and second stages of retention (P>0.05). U1-PP was found to possess a significant extrusion of 1.2 mm during the first stage (P<0.05), which increased by 0.68 mm during the second stage (P>0.05). The mandibular plane angle (MP-SN) decreased by 2.58 degrees following treatment, and underwent a relapse of 0.51 degree and 0.42 degree during the first and second stages of retention respectively (P>0.05). No significant soft tissue changes occurred, with the exception of increased upper lip length during the second stage (P<0.05). Maxillary anterior and posterior intrusions, counter clockwise rotation of the mandibular plane, and improved profiles can be successfully achieved following treatment with vertical control. During the first stage of retention (less than three years), intruded molars and incisors both exhibited some extrusion, and molars had better long-term stability than incisors. During the second stage of retention (three to six years), the therapeutic effects appeared stable, with the exception of some increase in upper lip length. Rotated mandibular plane remained stable during the entire retention period.

Lingual function in children with anterior open bite: A case-control study.

The position of the tongue during phonation and swallowing can modify the position of the teeth and even the growth of the jaws. OBJECTIVE: To determine the association between the position of the tongue and phonation among individuals with normal vertical overbite (NVO) and anterior open bite (AOB). MATERIALS AND METHODS: This was a case-control study of 132 students with AOB and 132 controls with NVO between the ages of 8 and 16 years old. The presence of AOB was determined during a clinical examination using a Boley gauge, phonation (speech) was assessed with an articulation test, which was analysed using a classification table of Spanish consonants spoken in Colombia, and tongue contact during swallowing was determined with the Payne test. Associations were determined between AOB and the position of the tongue upon swallowing and during speech (Chi2 test of independence, Fisher's exact test, and Mann-Whitey U test, P<0.005). Finally, a logistic regression model was performed, with AOB as the dependent variable. RESULTS: We found associations between AOB and the presence of lingual interposition, distortion, lingual thrust, protrusion of the tongue, contact with palatine rugae, and type of dentition (P<0.05). According to the logistic regression model, the presence of lingual thrust (odds ratio (OR): 0.067; 95% confidence interval (CI): 0.009-0.518) and contact with the palatine rugae (OR: 0.420; 0.216-0.818) behave as protective factors associated with the presence of AOB, and the presence of distortion was found to be a risk factor (OR: 10.751; 95%CI: 5.658-20.427). CONCLUSION: Lingual thrust, interposition, and protrusion are associated with AOB. Lingual thrust and contact of the tongue with the palatine rugae behave as protective factors, and the presence of distortion acts as a risk factor.

Three-dimensional ultrasound evaluation of tongue posture and its impact on articulation disorders in preschool children with anterior open bite.

Background Tongue posture plays an important role in the etiology of anterior open bite (AOB) and articulation disorders, and is crucial for AOB treatment planning and posttreatment stability. Clinical assessment of tongue posture in children is unreliable due to anatomical limitations. The aim of the study was to present functional diagnostics using three-dimensional ultrasound (3DUS) assessment of resting tongue posture in comparison to clinical assessment, and the associations between the improper tongue posture, otorhinolaryngological characteristics, and articulation disorders in preschool children with AOB. Patients and methods A cross-sectional study included 446 children, aged 3-7 years, 236 boys and 210 girls, examined by an orthodontist to detect the prevalence of AOB. The AOB was present in 32 children. The control group consisted of 43 children randomly selected from the participants with normocclusion. An orthodontist, an ear, nose and throat (ENT) specialist and a speech therapist assessed orofacial and ENT conditions, oral habits, and articulation disorders in the AOB group and control group. Tongue posture was also assessed by an experienced radiologist, using 3DUS. The 3DUS assessment of tongue posture was compared to the clinical assessment of orthodontist and ENT specialist. Results The prevalence of AOB was 7.2%. The AOB group and the control group significantly differed regarding improper tongue posture (p < 0.001), and articulation disorders (p < 0.001). In children without articulation disorders from both groups, the improper tongue posture occured less frequently than in children with articulation disorders (p < 0.001). After age adjustment, a statistical regression model showed that the children with the improper tongue posture had higher odds ratios for the presence of AOB (OR 14.63; p < 0.001) than the others. When articulation disorders were included in the model, these odds ratios for the AOB became insignificant (p = 0.177). There was a strong association between the improper tongue posture and articulation disorders (p = 0.002). The 3DUS detected the highest number of children with improper resting tongue posture, though there was no significant difference between the 3DUS and clinical assessments done by orthodontist and ENT specialist. Conclusions The 3DUS has proved to be an objective, non-invasive, radiation free method for the assessment of tongue posture and could become an important tool in functional diagnostics and early rehabilitation in preschool children with speech irregularities and irregular tongue posture and malocclusion in order to enable optimal conditions for articulation development.

Airway increase after open bite closure with temporary anchorage devices for intrusion of the upper posteriors: Evidence from 2D cephalometric measurements and 3D magnetic resonance imaging.

OBJECTIVE: The aim of this study was to analyse morphological changes in the upper airways in patients with anterior open bite treated with temporary anchorage devices for intrusion of upper posterior teeth. MATERIALS AND METHODS: Twelve nonobese (body mass index: <25) anterior open bite patients between the ages of 19 and 44 years (mean age: 22.83 ± 8.19 years) were recruited for this study. Cephalometric radiographs and magnetic resonance imaging (MRI) scans before and after anterior bite closure without bracketing on anterior teeth were used to measure the upper airway, which was divided into retropalatal and retroglossal regions. RESULTS: The mandibular plane angle and lower facial height were significantly reduced by intrusion of the upper posteriors and autorotation of the mandible. The retroglossal airway width (AW2) and retroglossal area (RG area) measured on cephalometric radiographs both increased significantly after treatment. Retroglossal volume increased and the retroglossal width/length ratio decreased significantly in MRI analysis. All other measurements were not significantly changed. However, no statistically significant correlations were observed between all measurements in 2D and 3D images, with the exception of the AW2 linear measurement in 2D images correlating with the AP length in MRI axial view images (r = 0.56, P = 0.0430). CONCLUSION: Counterclockwise rotation of the mandible after anterior open bite closed using orthodontic treatment changed the airway morphology. Retroglossal volume significantly increased and the airway shape became less elliptical after bite closure.

Curva de Spee: causas y tratamiento de su descompensación / Spee curve: causes and treatment of its discompensation

En el presente artículo se analiza y pasa revista a la bibliográfica acerca de la Curva de Spee: su etiología, los diferentes factores que pueden descompensarla, y los posibles tratamientos para corregirla en caso deestar alterada. Una mordida abierta esqueletal o dentaria, o una mordida profunda esqueletal o dentaria pueden modificarla, pudiendo utilizarse varios recursos y técnicas para tratar estos desórdenes, y así nivelar la curva.

In the present paper, the literature is analysed and reviewed the Curve of Spee: its aetiology, the different factors that can decompensate it, and the possible treatments to correct it in case of beingaltered. An open skeletal or dental bite, or a deep skeletal ordental bite can modify it, being able to use several resources and techniques to treat these disorders, and thus to level the curve.

Effect of a thin-neck pacifier on primary dentition: a randomized controlled trial.

OBJECTIVES: To evaluate changes in occlusal characteristics in the primary dentition that occur after introducing a thin-neck pacifier (TNP) to children with previously diagnosed pacifier-associated anterior open bite (AOB) and increased overjet. SETTING AND SAMPLE POPULATION: Department of Preventive and Pediatric Dentistry, Jena University Hospital, Germany. Subjects were 86 children (mean age 20.3 months) with a pacifier-associated open bite or overjet ≥2 mm. MATERIAL & METHODS: Randomized controlled trial. Subjects were randomly assigned: group I (n = 28), intervention group using a TNP; group II (n = 30), control group, using a conventional or physiological pacifier; and group III (n = 28), intervention group, Gold standard, weaned off pacifier. Participants were re-examined after 3, 6, 9 and 12 months by an operator, blinded for the treatment. RESULTS: After 12 months data for 63 children (mean age 33.1 months) were analyzed (I: n = 24; II: n = 22; III: n = 17). There was a significant difference between the groups regarding mean overjet (group I: 2.7 ± 0.5 mm, group II: 3.2 ± 0.7 mm, group III: 2.4 ± 0.5 mm, Kruskal-Wallis, p = 0.002) and AOB (group I: -1.2 ± 0.3 mm, group II: -2.2 ± 0.3 mm, group III: -0.8 ± 0.8 mm, Kruskal-Wallis, p < 0.001). The differences between group I and II regarding increased overjet (3.1 ± 0.2 mm vs. 3.6 ± 0.3 mm, Mann-Whitney, p < 0.001) and extent of AOB (-1.2 ± 0.3 mm vs. -2.2 ± 0.3 mm, Mann-Whitney, p < 0.001) were statistically significant. CONCLUSION: Use of TNP resulted in better clinical measurements for in overjet and overbite compared with the continuing use of conventional or physiological pacifiers.

Effect of malocclusion severity on oral health-related quality of life and food intake ability in a Korean population.

INTRODUCTION: The aim of this study was to evaluate the effect of malocclusion severity on oral health-related quality of life and food intake ability in adult patients, controlling for sex, age, and the type of dental clinic visited. METHODS: The sample consisted of 472 Korean patients (156 male, 316 female) with a mean age of 21.1 (SD, 8.6) years in a dental hospital and a private clinic. The correlations between the Korean version of the Oral Health Impact Profile-14 (OHIP-14K), subjective food intake ability (FIA) for 5 key foods, and Index of Orthodontic Treatment Need-Dental Health Component (IOTN-DHC) were investigated. RESULTS: The mean IOTN-DHC and OHIP-14K scores were significantly higher for the dental hospital patients than for the private clinic patients (IOTN-DHC, P <0.001; OHIP-14K, P <0.05). Malocclusion severity was significantly higher in male than in female subjects (P <0.001). Older patients perceived their oral health-related quality of life more negatively than did the teens (P <0.001). As the severity of the malocclusion increased, oral health-related quality of life and masticatory function worsened (OHIP-14K, P <0.001; FIA, P <0.05). CONCLUSIONS: As the severity of the malocclusion and the age of the patients increased, oral health-related quality of life and masticatory function relatively deteriorated. This finding provides evidence that severe malocclusions are associated with lower quality of life and less masticatory efficiency in older patients.

The effect of orofacial myofunctional treatment in children with anterior open bite and tongue dysfunction: a pilot study.

OBJECTIVES: Insufficient attention is given in the literature to the early treatment of anterior open bite (AOB) subjects receiving orofacial myofunctional therapy (OMT), which aims to harmonize the orofacial functions. This prospective pilot study investigates the effects of OMT on tongue behaviour in children with AOB and a visceral swallowing pattern. MATERIALS AND METHODS: The study comprised of 22 children (11 boys, 11 girls; age range: 7.1-10.6 years). They were randomly assigned into OMT and non-OMT subjects. The randomization was stratified on the presence of a transversal crossbite. At baseline (T0), at the end of treatment (T1) and at 6 months after T1 (T2) maximum tongue elevation strength was measured with the IOPI system (IOPI MEDICAL LLC, Redmond, Washington, USA). Functional characteristics such as tongue posture at rest, swallowing pattern and articulation and the presence of an AOB were observed. RESULTS: OMT did significantly change tongue elevation strength, tongue posture at rest, and tongue position during swallowing of solid food. At T2 more OMT subjects had contact between the lower central incisors and their antagonists or palate (P = 0.036). More OMT subjects performed a physiological pattern of water swallowing than non-OMT children at T1 and T2, although the differences were not significant. Articulation of /s,l,n,d,t/ was not improved by OMT. No interaction between OMT and expansion was found for any of the parameters. CONCLUSION: OMT can positively influence tongue behaviour. However, further research is recommended to clarify the success of OMT as an adjunct to orthodontic treatment and to identify possible factors influencing the outcome.

[Frequency of signs and symptoms of temporomandibular joint disorders, vertical orthodontic anomalies and their relationships based on screening of a large population]. / Temporomandibuláris ízületi és vertikális ortodonciai rendellenességek elofordulási gyakorisága, valamint azok összefüggései nagyszámú populáció szurovizsgálata alapján.

Altogether 4606 volunteers (2923 vomen, 1683 men) participated in the representative national epidemiological study to screen the alterations of temporomandibular joint (TMJ). The characteristic clinical signs and subjective complaints according to TMJ were evaluated by medical history taking and physical examination. Regarding the orthodontic anomalies, the vertical abnormalities (deep bite and open bite) were specifically noted. Clinical signs showing functional problems of TMJ were found in 45.19% of the screened population, mainly in the group of 35-44 year olds. The frequency of clicking and crepitation of TMJ was significantly higher in women compared to men (p < 0.05). The highest rate of clinical signs of TMJ disorders was found in the South-Transdanubian region, the lowest rate in the Middle-Transdanubian region, between these regions it was a significant difference regarding the frequency of deviation/deflexion (p < 0.05). Of the vertical abnormalities, deep bite occured most frequently in the 35-44 ys old age group. The prevalence of deep bite was higher among males than females in the whole screened population, but the difference was not statistically significant. Significant relationship was detected between deep bite and TMJ pain, deep bite and noises in the joint in the majority of the population. The most frequent anomaly in the South-Transdanubian region was deep bite, while the open bite occured most frequently in south middle part of Hungary. Conclusion: the Hungarian population needs well organized specific programs to improve the oral health including TMJ and orthodontic aspects.

Association between anterior open bite and impact on quality of life of preschool children.

The aim of this study was to evaluate the association between different types of malocclusion and the impact on quality of life among preschoolers and their families. A cross-sectional study was carried out involving 451 children 3-5 years of age. A clinical exam was performed to evaluate the malocclusions according to criteria proposed by Foster and Hamilton. This examination was conducted by a calibrated dentist. Parents/caregivers answered the Early Childhood Oral Health Impact Scale (ECOHIS) for the assessment of Oral Health-Related Quality of Life (OHRQoL) and the questionnaire on socioeconomic and demographic characteristics. Data analysis involved descriptive statistics, chi-square, Mann-Whitney and hierarchically adjusted Poisson regression. The prevalence of malocclusion was 28.4%. The most frequent conditions were posterior crossbite (20.4%), anterior open bite (9.5%) and increased overjet (8.4%). A significant association was found between anterior open bite and OHRQoL (p < 0.001). The adjusted analysis confirmed the association between anterior open bite and a negative impact on quality of life (PR = 2.55; 95%CI: 1.87 to 3.47; p < 0.001). Anterior open bite was associated with a negative impact on the quality of life of preschoolers.

Establishment of integral biomechanical balance in the correction of tongue source skeletal dentomaxillofacial open bite deformities.

The objective of this clinical paper is to demonstrate an effective process to achieve relative long-term functional and aesthetic stability after the treatment of skeletal tongue source open bites. This therapy consisted of applying Delaire's architectural analysis as the cephalometry to make treatment plan corresponding to the patients' own craniomaxillofacial integral architectural structure to achieve the optimal skeletal anteroposterior and vertical position. In addition, glossoplasty and transverse matching of upper and lower arches must be under consideration in the goal of achieving integral biomechanical functional balance and aesthetic harmony. Little relapse of both skeleton and occlusion was found more than 3 years posttreatment. The effect of pararthria correction coursed by lingual functional impediment is also attained.

Pacifier-sucking habit duration and frequency on occlusal and myofunctional alterations in preschool children.

The objective of this study was to evaluate the association of pacifier-sucking habit with occlusal and oral myofunctional alterations in preschool children. Eighty-four 2- to 5-year-old children participated in the study. Data on duration and frequency of pacifier use were collected from parents or guardians. Occlusal and oral myofunctional characteristics were examined by a dentist and a speech therapist, respectively. Chi-square tests and Poisson regression were used to analyze the data. The occlusal characteristics that were significantly associated with a pacifier-sucking habit were anterior open bite, altered canine relation, posterior crossbite, increased overjet, and malocclusion. The oral myofunctional characteristics that were significantly associated with a pacifier-sucking habit were resting lip position, resting tongue position, shape of the hard palate, and swallowing pattern. The strongest associations were for anterior open bite (prevalence ratio [PR] = 11.33), malocclusion ( PR = 2 .33), altered shape of the hard palate ( PR = 1.29), and altered swallowing pattern (PR = 1.27). Both duration and frequency of pacifier-sucking habit were associated with occlusal and oral myofunctional alterations. These results emphasize the need for pediatric dentists to advise parents and caregivers about the risks of prolonged pacifier use and refer children to professionals for multidisciplinary assistance to minimize these risks whenever necessary.

Pacifier-sucking habit duration and frequency on occlusal and myofunctional alterations in preschool children

The objective of this study was to evaluate the association of pacifier-sucking habit with occlusal and oral myofunctional alterations in preschool children. Eighty-four 2- to 5-year-old children participated in the study. Data on duration and frequency of pacifier use were collected from parents or guardians. Occlusal and oral myofunctional characteristics were examined by a dentist and a speech therapist, respectively. Chi-square tests and Poisson regression were used to analyze the data. The occlusal characteristics that were significantly associated with a pacifier-sucking habit were anterior open bite, altered canine relation, posterior crossbite, increased overjet, and malocclusion. The oral myofunctional characteristics that were significantly associated with a pacifier-sucking habit were resting lip position, resting tongue position, shape of the hard palate, and swallowing pattern. The strongest associations were for anterior open bite (prevalence ratio [PR] = 11.33), malocclusion (PR = 2.33), altered shape of the hard palate (PR = 1.29), and altered swallowing pattern (PR = 1.27). Both duration and frequency of pacifier-sucking habit were associated with occlusal and oral myofunctional alterations. These results emphasize the need for pediatric dentists to advise parents and caregivers about the risks of prolonged pacifier use and refer children to professionals for multidisciplinary assistance to minimize these risks whenever necessary.

Association between anterior open bite and impact on quality of life of preschool children

The aim of this study was to evaluate the association between different types of malocclusion and the impact on quality of life among preschoolers and their families. A cross-sectional study was carried out involving 451 children 3-5 years of age. A clinical exam was performed to evaluate the malocclusions according to criteria proposed by Foster and Hamilton. This examination was conducted by a calibrated dentist. Parents/caregivers answered the Early Childhood Oral Health Impact Scale (ECOHIS) for the assessment of Oral Health-Related Quality of Life (OHRQoL) and the questionnaire on socioeconomic and demographic characteristics. Data analysis involved descriptive statistics, chi-square, Mann-Whitney and hierarchically adjusted Poisson regression. The prevalence of malocclusion was 28.4%. The most frequent conditions were posterior crossbite (20.4%), anterior open bite (9.5%) and increased overjet (8.4%). A significant association was found between anterior open bite and OHRQoL (p< 0.001). The adjusted analysis confirmed the association between anterior open bite and a negative impact on quality of life (PR = 2.55; 95%CI: 1.87 to 3.47; p< 0.001). Anterior open bite was associated with a negative impact on the quality of life of preschoolers.

Biomechanical analysis of fractures in the mandibular neck (collum mandibulae).

After treatment of fractures in the neck of the mandible by means of immobilization of the dentition, often more or less severe manifestations of malocclusion remain. It was hypothesized that this is caused by an altered articulation in the jaw joint on the affected side. Furthermore, it was hypothesized that an anteriorly displaced condyle, as observed frequently as a side effect of the treatment, is caused by pull of the lateral pterygoid muscle, despite maxillomandibular fixation. Intervention experiments were performed in silico to test these hypotheses. With a biomechanical model of the human masticatory system alterations were applied mimicking a fractured mandibular neck and configurations that had been observed after healing. It was predicted that the altered articulation in the jaw joint caused asymmetrical jaw movements despite symmetrical muscle activation. The jaw was predicted to close with an open bite similar to clinical observations. The predicted laterodeviations, however, were not in accordance with clinical observations. Despite maxillo-mandibular fixation the lateral pterygoid muscle was able to pull the mandibular condyle out of its fossa in anterior direction. Consequently, despite some methodological limitations, in general the predictions corroborated the hypotheses.

Electromyographic evaluation of masticatory muscles at rest and maximal intercuspal positions of the mandible in children with sleep bruxism.

UNLABELLED: In adults, sleep bruxism (SB) may be related to reports of pain or fatigue in the muscles of mastication, resulting from multiple muscle contractions that occur during the night. In children, little is known about the consequences of this parafunction. PURPOSE: The objective was to compare the electromyographic activity (EMG) of the masseter and anterior portion of the temporalis muscles in children with and without SB; acquisitions were made at rest (RE) and in maximal intercuspal (MI) positions of the mandible. METHODS: Twenty children with signs and symptoms of SB (mean age 7.20 years ± 0.52) and 20 controls without signs or symptoms of SB (mean age 7.40 years ± 0.50) were selected. The controls were matched to the type of occlusal morphology evaluated according to Björk et al. (Acta Odontol Scand 22:27-40, 1964). Muscle activity was measured with the mandible at RE, MI and maximal clenching with cotton roll (MC), on the left and right sides. Data from the RE and MI (mV) were normalized by calculating them as % MC. The results were analyzed by descriptive statistics, Shapiro-Wilk test, Wilcoxon and Mann-Whitney tests. RESULTS: The subjects' age did not differ significantly between groups. EMG of temporalis muscle at RE differed between the right and left sides in both groups. There was no significant difference in EMG of masseter and temporalis muscles between groups. CONCLUSION: Children with SB showed no significant difference in EMG of masticatory muscles at RE and in MI positions of the mandible when compared with the control group.

Jaw clenching effects in relation to two extreme occlusal features: patterns of diagnoses in a TMD patient population.

OBJECTIVE: The aim of this investigation was to compare the pattern of temporomandibular disorder (TMD) diagnoses in clenching patients with different occlusal features, the null hypothesis being that no between-group differences exist. MATERIALS AND METHODS: Two groups of subjects receiving a jaw clenching diagnosis and having large overjet or anterior open bite (Group A; N=45, 75.5% females, mean age: 38.1 +/- 15.9 years) or normal occlusion (Group B; N=69, 71% females, mean age: 34.6 +/- 13.8 years) were recruited among a TMD patient population and were given Research Diagnostic Criteria for TMD (RDC/TMD) axis I diagnoses, namely, group I muscle disorders, group II disc displacements, and group III arthralgia/osteoarthritis/osteoarthrosis. MAJOR FINDINGS: The distribution of RDC/TMD single and combined group diagnoses was significantly different between the two groups (P<0.05), with Group A subjects showing a higher prevalence of multiple diagnoses (60% versus 43.3%), as well as a higher prevalence of combined RDC/TMD axis I group II and III diagnoses (37.8% versus 20.2%). All TMD signs and symptoms were more frequent in the patients with large overjet or anterior open bite with respect to the patients with normal occlusion. CONCLUSION: In a TMD patient population, jaw clenching may have different consequences in subjects with large overjet or anterior open bite with respect to subjects featuring normal occlusion.