Relationship between Occlusal Findings and Orofacial Myofunctional Status in Primary and Mixed Dentition

AIM: The aim of this study was to provide basic data on the prevalence of orofacial dysfunctions in primary and early mixed dentition and to examine occlusal relationships in their functional context, and to analyze the need for and potential of orthodontic prevention and early treatment. SUBJECTS AND METHODS: We assessed the occlusal relationships and myofunctional status of 3,041 children. The presence of dynamic and static myofunctional disorders and any oral habits were documented during functional analysis. RESULTS: The frequency of myofunctional disorders was statistically significantly higher in children with increased maxillary overjet, frontal open bite, lateral crossbite and mandibular prognathism, and there was a statistically significant increase in the prevalence of orofacial dysfunctions and oral habits from primary to mixed dentitions. CONCLUSIONS: Habitual open mouth posture (expressing hypotonia in the perioral muscles) and a visceral swallowing pattern become established during the primary dentition and are increasingly carried over into the mixed dentition period. Both criteria, along with assessment of occlusal relationships, are appropriate parameters with which to identify "children at risk for orthodontic treatment".     

Relationship between Occlusal Findings and Orofacial Myofunctional Status in Primary and Mixed Dentition

AIM: The aim of this study is to provide basic data on the prevalence of malocclusions and orofacial dysfunctions in the primary and early mixed dentition, to examine occlusal relationships in their functional context, and to analyze the need for and potential of orthodontic prevention. SUBJECTS AND METHODS: Occlusal relationships and myofunctional status were evaluated in 766 children in the primary dentition and in 2,275 children in the early mixed dentition. Orthodontic findings in single jaws and intermaxillary occlusal relationships were clinically analyzed in all three dimensions. RESULTS: Normal occlusal relationships were found in 25.3% of children in the primary dentition. Frequency of children with normal dentitions fell significantly in the mixed dentition (7.3%). Prevalence of bilateral distoclusion increased significantly from the primary to the mixed dentition. Increased maxillary overjet was diagnosed in 49.3% and 59.0% of the children in the primary and mixed dentition, respectively. Prevalence of lateral crossbites increased significantly from primary to mixed dentition (7.2% vs. 12.0%). Deep bites and edge-to-edge bites were found significantly more often in the early mixed dentition. CONCLUSIONS: The significant increase in the prevalence of malocclusions between the primary and mixed dentition--distoclusion and lateral crossbite, and the impairment of vertical occlusal relationships in the mixed dentition in particular--reveal the need for orthodontic prevention. They highlight the absence of applied interceptive and early treatment measures in orthodontics. The indication system in current use for early orthodontic treatment here in Germany fails to fulfill the requirements for prevention-oriented dental care.     

Relationship between occlusal findings and orofacial myofunctional status in primary and mixed dentition

Aim

The aim of this study was to provide basic representative data on the prevalence of malocclusions involving space deficiency in both primary and early mixed dentition and to examine the relationship between these malocclusions and orofacial dysfunctions. The results should be viewed from an orthodontic prevention and early treatment perspective.

Subjects and methods

Orthodontic findings in the maxilla and mandible as well as the myofunctional status of 766 children in primary dentition and 2,209 children in mixed dentition were examined clinically in a cross-sectional study. The following parameters from each jaw were subjected to orthodontic analysis: crowding in the anterior and posterior regions of the maxilla and mandible in primary and mixed dentitions, deviations from normal maxillary arch forms in the primary dentition, deviations from normal anterior maxillary arch width in mixed dentition and maxillary apical base morphology in mixed dentition. Static and dynamic orofacial dysfunctions were documented with reference to specific parameters and clinical tests.

Results

Crowding was observed in every tenth child in primary dentition (10.8%) and in every second child in mixed dentition (49.7%). Habitual open mouth posture, visceral swallowing, articulation disorders and oral habits were statistically significantly more frequent in children in primary dentition presenting a narrow maxillary arch. Reduced anterior maxillary arch width (compression) was statistically more frequent in children in early mixed dentitions with habitual open mouth posture. A narrow maxillary apical base correlated positively with all the orofacial dysfunctions analyzed.

Conclusions

Deviations from a regular arch form become apparent very early during dentition development and coexist with specific orofacial dysfunctions. They are thus important indicators for the early detection of functional abnormalities, causing deviations from normal dentition development. In children with orofacial dysfunctions the development of a narrow maxillary dental arch should be prevented by myofunctional therapy and by educating the parents. Interceptive orthodontic measures to treat a narrow maxillary arch in primary and early mixed dentition should also focus on eliminating functional disturbing factors, such as orofacial dysfunctions. Interdisciplinary cooperation with specialists in other fields of medicine, e.g. otorhinolaryngology and speech therapy, is essential to achieve this goal.     

Indication for and Frequency of Early Orthodontic Therapy or Interceptive Measures

The early treatment of nonskeletal and skeletal orthodontic anomalies in the deciduous and early mixed dentition is intended to prevent the development of pronounced anomalies in the late mixed and permanent dentition with the ultimate aim of reducing or even eliminating the need for later orthodontic treatment. There is a general consensus in the international literature that early therapy is indicated in cases of anterior and lateral crossbite and Class III malocclusion, and possibly for extreme forms of mandibular retrognathism (overjet > or =10 mm) and of open bite. However, evidence of the efficiency of early orthodontic measures is just as rare as studies providing serviceable information on the incidence of tooth malalignments and malocclusions in the deciduous and early mixed dentition, some of whose findings are in any case highly divergent. This makes it substantially more difficult to draw conclusions on the extent to which early orthodontic therapy may be indicated. In order to obtain information on the incidence of nonskeletal and skeletal orthodontic problems constituting a treatment need, 2326 first-year schoolchildren aged between 6 and 7 years were examined in Frankfurt am Main and in the Rural District of Offenbach. In only 14.7% of the children were no relevant orthodontic findings recorded. 77.2% displayed mild to severe dysgnathic symptoms, though without early orthodontic therapy being considered indicated. Treatment with orthodontic appliances was considered urgent for 187 of the children (8.04%). With 8.3% and 7.9% respectively, lateral and anterior crossbite were top of the list of anomalies with an urgent treatment need. Among the patients with lateral crossbite, the prognostically less favorable unilateral form was recorded approximately four times more often than the bilateral form. Markedly increased sagittal overjet > or =10 mm) was registered in only 1.4% of the children, and negative overjet (Class III) (with the exception of edge-to-edge bite) in 1.9%. Extreme anterior open bite > or =6 mm) was recorded in only two children (0.09%). In 19.6% of the children, a supporting zone was reduced in at least one quadrant, necessitating interceptive measures such as the insertion of a space maintainer or later orthodontic treatment (space opening or extraction therapy).     

Effects of nonnutritive sucking habits on occlusal characteristics in the mixed dentition

PURPOSE: Little is known about the extent to which nonnutritive sucking habits contribute to malocclusion in the mixed dentition. The purpose of this study was to report on the relationship between certain occlusal traits in the mixed dentition and longitudinal sucking behaviors. METHODS: Dental examinations were conducted on 630 children in the mixed dentition who participated in a large, ongoing longitudinal study. Five hundred eighty consented to impressions, and 524 adequate study models were obtained. Of these, 444 also had adequate longitudinal nonnutritive sucking data obtained via mailed questionnaires to parents at 3- to 6-month intervals from birth to 8 years. Sucking behaviors were grouped by predominant type and duration. Study models were hand articulated using wax bites to evaluate the occlusion for the presence of open bite, crossbite, molar relationship, and excessive overjet. Bivariate statistical analyses related presence of these malocclusions to sucking duration and type. RESULTS: Fifty-five percent of the children had malocclusions (anterior open bite, posterior crossbite, bilateral Class II molar relationship, or overjet >4 mm). Class II molar relationship was most common (30%). Overall, anterior open bite and posterior crossbite was associated with habits of 36 months or more. Sustained pacifier habits, including those of 24 to 47 months, were associated with anterior open bite and Class II molar relationships, while digit habits were associated with anterior open bite when sustained for 60 months or longer. CONCLUSIONS: Malocclusions are quite prevalent in the mixed dentition, and anterior open bite and posterior crossbite may be preventable by modifying nonnutritive sucking behaviors.     

Orthodontic Findings in the Deciduous and Early Mixed Dentition—Inferences for a Preventive Strategy

AIM AND METHOD: The aim of the present epidemiologic study was to obtain representative basic data on the frequency, extent and age-dependence of malocclusions in the deciduous and early mixed dentition. The developmental tendencies of specific malocclusions were investigated from the aspect of orthodontic prevention. The collective comprised 8,864 preschool and school-aged children, of whom 1,225 were in the deciduous dentition (mean age 4.5 years) and 7,639 in the mixed dentition (mean age 8.9 years). The orthodontic data were clinically assessed as sagittal, transversal, or vertical single-arch and occlusal findings. In addition, the malocclusions were classified according to their primary symptoms. Early infantile habits, tongue dysfunctions, speech defects and incompetent lip closure were registered separately. RESULTS: 57% of the children were found to have malocclusions, with the frequency rising statistically significantly in dependence on age from the deciduous to the mixed dentition (p < or = 0.001). The mean extent of excessive overjet increased significantly from the deciduous to the mixed dentition. Crossbite with mandibular midline discrepancies were observed significantly more frequently in the deciduous dentition. Although the frequency of anterior open bite underwent a significant decline from the deciduous to the mixed dentition, open bite was the malocclusion most frequently associated with dysfunction in both groups. The significant increase in traumatic deep bite in the mixed dentition indicates an unfavorable developmental tendency in this anomaly until after the eruption of the permanent incisors. CONCLUSION: The need for preventive orthodontic therapy and for the intensified application of interceptive and early treatment measures is stressed in view of the high number of malalignments and malocclusions in the deciduous and mixed dentition and the tendency for some forms of malocclusion to deteriorate as the dentition develops.     

Influence of orthodontic treatment in the primary dentition upon development of the dentition and craniofacial growth

Thirty patients who underwent orthodontic treatment of the primary dentition were examined in this retrospective follow-up study. The mean age at the beginning of treatment was 4.4 (±1.1) years, and at follow-up 15.4 (±1.7) years. Different kinds of malocclusion were present.—Results: The early treatment lasted on average 12.3 (±7.2) months. Treatment time of Class III malocclusion and lateral crossbite was significantly shorter than that of Class II,1 malocclusion, functional Class II,2 malocclusion or anterior open bite (p<0.05). A Class I occlusion was achieved in 90% of the patients during treatment of the primary dentition. No patient treated successfully in the primary dentition showed any relapse to initial malocclusion.—Conclusion: These results suggest that changes in occlusion and mandibular position during treatment in the primary dentition are maintained in the mixed and permanent dentition. It can be concluded that a Class I occlusion following orthodontic treatment in the primary dentition serves as a basis for physiological development of the dentition and craniofacial growth.     

Prevalence of Defined Symptoms of Malocclusion among Probands Enrolled in the Study of Health in Pomerania (SHIP) in the Age Group from 20 to 49 Years

SUBJECTS AND METHODS: SHIP is a complexly structured, population-based cross-sectional study of adults in the German region of Pomerania (age group covered: 20-79 years). Findings in a population subgroup (age group 20-49 years; n = 1777; 53.1% women; 46.9% men) were subjected to orthodontic evaluation. Graduated registration of anterior crowding, overjet, frontal overbite and sagittal intermaxillary relationship of the posterior teeth; registration of ectopic canines, posterior crowding, anterior and posterior crossbite, negative overjet, retroclination of the upper incisors, buccal nonocclusion, and lateral open bite. The prevalence of almost regular dentition and of symptoms of malocclusion as well as the frequency of orthodontic treatment (subjective patient data) undergone by men and women were recorded. The correlation between the registered symptoms of malocclusion was calculated. RESULTS: 92.2% of the subjects had symptoms of malocclusion varying in number and severity. An anatomically correct dentition was found in only 7.8% of cases, and an "almost regular dentition" (inclusion criteria defined) in 14.2%. 32.8% of the subjects had severe malocclusion (inclusion criteria defined). The most frequent symptoms were anterior crowding, increased overjet, and distoclusion. These symptoms were significantly more frequent in women, while spacing and edge-to-edge bite, excessive overbite and mesioclusion were more frequent in men. 26.7% of the probands (28.0% women, 25.3% men) reported having received orthodontic treatment. The prevalence of craniofacial malformations (cleft lip and palate, syndromes) was 0.09% in women and 0.2% in men. Increased overjet was most frequently correlated with other symptoms of malocclusion.     

Temporomandibular joint dysfunction and occlusion in the mixed and permanent dentition

The aim of this study was to investigate the relation between occlusal factors: Angle classification, overbite, overjet, openbite, anterior and posterior crossbite, scissors bite or buccal crossbite and lateral openbite--and the presence of mandibular dysfunction in a sample of 359 Turkish children with mixed and permanent dentition. Z Test was used to compare the results. It was found that, Class III malocclusion in the permanent dentition and openbite, overbite = 0, overjet = 0, anterior-posterior crossbite in the mixed dentition were related with TMD.     

Occlusal characteristics during different emergence stages of the permanent dentition in Tanzanian Bantu and finnish children

Occlusal characteristics and anomalies were studied among 869 (428 boys, 441 girls) Tanzanian Bantu children aged 3.5-16 years and 706 (319 boys, 387 girls) Finnish children aged 5-11 years during different emergence stages of the permanent dentition. Various occlusal variables were registered according to described criteria. Multiple linear regression, ANOVA, t-test, Chi-square and logistic regression models were used to test for various statistically significant differences between different subgroups. Significant differences between Tanzanians and Finns were found for malocclusion, neutral and distal molar occlusion, mean values for overjet and overbite, overjet greater than 5 mm, deep bite and anterior open bite (all P < 0.0001). The most prevalent anomalies among Tanzanians were anterior open bite (7-19 per cent), increased overjet (3-19 per cent) and distal molar occlusion (3-16 per cent). For the Finns, distal molar occlusion (18-38 per cent) was the most prevalent anomaly, followed by deep bite (4-22 per cent) and increased overjet (4-40 per cent). An anterior crossbite was rare and equally distributed among the two ethnic groups. Girls had a larger mean value for overbite (P = 0.003) and more often a deep bite (P < 0.01) than boys. Mandibular incisor crowding among children with neutral occlusion (Class I malocclusion) occurred significantly more often among Finnish than Tanzanian children. In conclusion, various developmental changes in occlusion were observed leading to variation in occlusal characteristics and anomalies according to the emergence stages of the permanent dentition. Most of the classic malocclusions occur among Tanzanian children, but the prevalence differs from that in other parts of the world.     

广州市荔湾区替牙期儿童龋齿及错畸形综合防治效果分析

目的探讨广州市荔湾区替牙期儿童窝沟封闭防龋、前牙反和开防治的效果及影响因素。方法对广州市荔湾区2009年至2013年全区适龄儿童实施窝沟封闭防龋项目;同时于2012年对荔湾区9-11岁儿童错畸形进行调查,并对前牙反和开进行干预性治疗,收集的相关数据进行统计分析。结果在广州市荔湾区,实施儿童第一恒磨牙窝沟封闭最佳对象是二年级学生（7-8岁）;荔湾区窝沟封闭项目进展相对顺利,影响项目的主要因素包括民众的认知度以及医护人员规范化操作和责任心;替牙期前牙反矫治成功率高,复发率低;前牙开矫治成功率高,但复发率也高;前牙反和开儿童就诊治疗率低。结论广州市荔湾区二年级学生（7-8岁）应尽早实施窝沟封闭;政府加强宣传教育有助于提高窝沟封闭的普及率。替牙期前牙反的早期矫治疗效显著,值得推广;前牙开早期治疗对形态功能的恢复及矫治后的稳定性有事半功倍的效果;政府可考虑加大力度推广替牙期错畸形的防治工作。     

The relationship between occlusal factors and bruxism in permanent and mixed dentition in Turkish children

The aim of this study was to investigate the relationship between occlusal factors (overjet, overbite, Angle's Classification of molars and cuspids, the relationship of the primary molars, openbite, lateral openbite, scissorbite and crossbite) and bruxism in permanent and mixed dentition in Turkish children. For this reason 182 children with mixed dentition and 212 children with permanent dentition were included in this study. Occlusal conditions were examined clinically and bruxism was assessed by using interview and questionnaires. Z Test was used to compare the results. It was found that in both dentitions some occlusal factors related with bruxism (overjet > 6 mm, overbite > 5 mm, negative overjet, openbite in permanent dentition; overjet > 6 mm, overbite > 5 mm, scissorbite, anterior-posterior multiple teeth crossbite, Angle Class I occlusion in mixed dentition.     

Prevalence and Development of KIG-relevant Symptoms in Primary School Students from Frankfurt am Main*

OBJECTIVE: To determine the actual need for orthodontic treatment in the late mixed dentition according to the German KIG system (Kieferorthop?dische Indikationsgruppen = Orthodontic Indication Groups). By comparing the findings with those of the early mixed dentition, we aimed to evaluate whether a change in the spectrum of malocclusions would occur. SUBJECTS AND METHODS: Dental check-ups took place in schools in Frankfurt am Main, during which the orthodontically-relevant symptoms of 1251 schoolchildren (female 49.5%, male 50.5%) in grades 4 and 5 were recorded and compared with findings documented 4 years earlier in the same classes at the same schools. RESULTS: Of those orthodontic malocclusions in need of therapy and covered by the statutory health insurance, lateral crossbite and enlarged overjet (more than 6 mm) dominated by 9.2% and 8.7%, respectively, among the 9- to 11-year-old children. Of all the malocclusions recorded within the KIG-group showing a treatment need degree > or = 3, category D4 (overjet greater than 6 mm) at 17.4% was the most frequent, followed by K4 (unilateral crossbite) at 15.3%, and M4 (negative overjet up to -3 mm) at 14.9%. 41.4% of all the children examined presented a treatment indication according to statutory health insurance directives (KIG > or = 3). The 10% reduction in treatment cases financed by statutory health insurance has been achieved in any case [1], as mandated by health policy. CONCLUSIONS: Our comparison of results gathered from 2000 and 2004 showed that as the children grew older, the prevalence of already-enlarged overjets increased, as did the frequency of deep bite. We observed fewer frontal open bites and crossbites in late mixed dentition. Treatment need according to current statutory health insurance directives was clearly higher in the late mixed dentition (41.4%) than in the early mixed dentition (8%).     

上海市浦东新区青少年错牙合畸形调查分析

目的了解上海市浦东新区生长发育期青少年错牙合畸形的患病情况，重点了解牙列拥挤、前牙深覆合覆盖和前牙反牙合的患病率。方法按Ａｎｇｌｅ分类法进行分类，以个别正常牙合和错牙合分类为标准。结果错牙合畸形的患病率替牙期为４４．０２％，恒牙期为４８．７８％。牙列拥挤、前牙深覆合覆盖和前牙反牙合的患病率替牙期分别为２２．７４％、１７．１８％和４．４４％；恒牙期分别为３２．３６％、１１．０６％和４．０７％。结论上海市浦东新区生长发育期青少年错牙合畸形的患病率替牙期与恒牙期无明显差异。提示前牙深覆合覆盖和前牙反牙合的患者并伴有上下颌骨异常需尽早矫治，以改善牙合颌关系。     

上海市浦东新区青少年错He畸形调查分析

目的 了解上海市浦东新区生长发育期青少年错Ｈｅ畸形的患病情况,重点了解牙列拥挤、前牙深覆合覆盖和前牙反Ｈｅ的患病率。方法 按Ａｎｇｌｅ分类法进行分类,以个别正常Ｈｅ和错Ｈｅ分类为标准。结果 错Ｈｅ畸形的患病率替牙期为４４．０２％,恒牙期为４８．７８％。牙列拥挤、前牙深覆合覆盖和前牙反Ｈｅ的患病率替牙期分别为２２．７４％、１７．１８％和４．４４％;恒牙期分别为３２．３６％、１１．０６％和４．０７％。     

Prevalence of temporomandibular dysfunction and its association with malocclusion in children and adolescents: an epidemiologic study related to specified stages of dental development

A sample of 4724 children (2353 girls and 2371 boys) (5-17 years old) were grouped not only by chronological age but also by stage of dental development (deciduous, early mixed, late mixed, and permanent dentition). The registrations included functional occlusion (anterior and lateral sliding, interferences), dental wear, mandibular mobility (maximal opening, deflection), and temporomandibular joint and muscular pain recorded by palpation. Headache was the only symptom of temporomandibular dysfunction (TMD) reported by the children. The results showed that one or more clinical signs were recorded in 25% of the subjects, most of them being mild in character. The prevalences increased during the developmental stages. Girls were in general more affected than boys. Significant associations were found between different signs, and TMD was associated with posterior crossbite, anterior open bite, Angle Class III malocclusion, and extreme maxillary overjet.     

Prevalence of malocclusions in the early mixed dentition and orthodontic treatment need

Early interceptive treatment for the elimination of factors inhibiting dental arch development and mandibular and maxillary growth is applied varyingly by orthodontists, possibly because there is little scientific evidence that such interventions are of actual benefit. The aim of this study was to determine specific factors for treatment need in the early mixed dentition period in order to obtain basic data to support early intervention. The study was part of a larger survey of 8768 children aged between 6 and 17 years. From this sample, 1975 children aged between 6 and 8 years were used to estimate the prevalence of malocclusions using the Index of Orthodontic Treatment Need (IOTN) during the early mixed dentition period. The results showed that deep overbite and overjet, both more than 3.5 mm, were the most frequent discrepancies, affecting 46.2 and 37.5 per cent of patients, respectively. An anterior open bite was registered in 17.7 per cent, crossbite in 8.2 per cent, and a reverse overjet in 3.2 per cent. A tooth width to arch length discrepancy was recorded in 12 per cent of teeth in the upper arch and in 14.3 per cent in the lower arch. The proportion of children estimated using the Dental Health Component of the IOTN to have a great or very great treatment need (grades 4 and 5) was 26.2 per cent. The higher values of treatment need during the mixed dentition period may account for temporary changes in the dentition and for the discrepancy in overjet and overbite. These discrepancies will be compensated in part during mandibular growth and development of the dental arch. Nevertheless, the findings indicate the early development of progressive malocclusion symptoms which are evidenced in the IOTN and concur with the acronym 'MOCDO' hierarchy (missing, overjet, crossbite, displacement, overbite). This early formation of progressive symptoms inhibiting or disturbing mandibular or maxillary growth or the development of the normal dental arch, i.e. crossbite, reverse overjet and increased overjet with myofunctional disorders, should be treated at an early stage.     

Facial dimensions, bite force and masticatory muscle thickness in preschool children with functional posterior crossbite

Posterior crossbite may affect craniofacial growth and development. Thus, this study aimed to associate facial dimensions (by standardized frontal photographs) to masseter and anterior portion of the temporal muscle thickness (by ultrasonography) and maximal bilateral bite force in 49 children with deciduous and early mixed dentitions. They were distributed in four groups: deciduous-normal occlusion (DNO, n = 15), deciduous-crossbite (DCB, n = 10), mixed-normal occlusion (MNO, n = 13) and mixed-crossbite (MCB, n = 11). Anterior facial height (AFH), bizygomatic width (FWB), and intergonial width (FWI) were determined and associated with muscle thickness and bite force, applying Pearsons coefficients and multiple logistic regression, with age, gender, body weight and height as the covariates. FWB and FWI were correlated positively with the masseter thickness, whereas AFH/FWB and AFH/FWI ratios had negative correlation, except in the DNO group. The correlation between AFH/FWB and bite force in the MCB group was significantly negative. A higher AFH/FWB in MNO and MCB led to a significantly higher probability for functional crossbite development. In the studied sample, it was observed that children in the early mixed dentition with a long-face trend showed lower bite force and higher probability to present functional posterior crossbite, without significant influence of the covariates.     

Prevalence of malocclusion and orthodontic treatment need in children and adolescents in Bogota, Colombia. An epidemiological study related to different stages of dental development

The aim of the study was to assess the prevalence of malocclusion in a population of Bogotanian children and adolescents in terms of different degrees of severity in relation to sex and specific stages of dental development, in order to evaluate the need for orthodontic treatment in this part of Colombia. A sample of 4724 children (5-17 years of age) was randomly selected from a population that attended the Dental Health Service; none had been orthodontically treated. Based on their dental stages the subjects were grouped into deciduous, early mixed, late mixed and permanent dentition. The registrations were performed according to a method by Bj?rk et al. (1964). The need for orthodontic treatment was evaluated according to an index used by the Swedish National Board of Health. The results showed that 88 per cent of the subjects had some type of anomaly, from mild to severe, half of them recorded as occlusal anomalies, one-third as space discrepancies, and one-fifth as dental anomalies. No clear sex differences were noted, except for maxillary overjet, spacing, tooth size (all more frequent in boys), and crowding (more frequent in girls). Occlusal anomalies and space discrepancies varied in the different dental developmental periods, as did tipped and rotated teeth. Little need for orthodontic treatment was found in 35 per cent and moderate need in 30 per cent. A great need was estimated in 20 per cent, comprising children with prenormal occlusion, maxillary overjet, or overbite (> 6 mm), posterior unilateral crossbite with midline deviation (> 2 mm), severe crowding or spacing, congenitally missing maxillary incisors, impacted maxillary canines or anterior open bite (> 3 mm in the permanent dentition). Urgent need for treatment was estimated to be 3 per cent, comprising subjects with extreme post- and pre-normal occlusion, impacted maxillary incisors or extensive aplasia.     

Masticatory muscle thickness, bite force, and occlusal contacts in young children with unilateral posterior crossbite

Few investigations have evaluated the characteristics of functional and structural malocclusion in young children. Thus, the aim of this study was to assess the ultrasonographic thickness of the masseter and anterior portion of the temporalis muscles, the maximum bite force, and the number of occlusal contacts in children with normal occlusion and unilateral crossbite, in the primary and early mixed dentition. Forty-nine children (26 males and 23 females) was divided into four groups: primary-normal occlusion (PNO), mean (PNO) age 58.67 months; primary-crossbite (PCB), mean age 60.50 months; mixed-normal occlusion (MNO), mean age 72.85 months; and mixed-crossbite (MCB), mean age 71.91 months. Thickness was evaluated with the muscles at rest and during maximal clenching, and comparison was made between the right and left side (normal occlusion), and between the normal and crossbite side (crossbite). The results were analysed using Pearson's correlation, paired and unpaired t-test, and Mann-Whitney ranked sum test. The anterior temporalis thickness at rest was statistically thicker for the crossbite side than the normal side in the MCB group (P = 0.0106). A statistical difference in bite force and the number of occlusal contacts was observed between the MNO and MCB groups, with greater values for the MNO subjects (P < 0.05). Masseter muscle thickness showed a positive correlation with bite force, but the anterior temporalis thickness in the PCB and MCB groups was not related to bite force. Masticatory muscle thickness and bite force did not present a significant correlation with occlusal contacts, weight, or height. It was concluded that functional and anatomical variables differ in the early mixed dentition in the presence of a malocclusion and early diagnosis and treatment planning should be considered.