Occlusal anomalies in 45,X/46,XX- and 46,Xi(Xq)-women (Turner syndrome)

A total of 20 individuals with X-chromosome aberrations, 14 45,X/46,XX-women and six 46,Xi(Xq)-women, were examined for occlusal anomalies. The controls were first-degree woman relatives and population women. The results showed that the most common type of malocclusion in both study groups was lateral cross bite. Also distal molar occlusion, increased maxillary overjet and in 45,X/46,XX-women open bite was found. 45,X/46,XX-women's occlusion seems to be more affected than that of 46,Xi(Xq)-women. Compared to 45,X-women, the present study groups show milder expression of malocclusion. One might speculate that enamel genes of the X-chromosome are involved in occlusal development.     

Tooth crown size in 46, X, i (Xq) human females

Permanent tooth crown sizes of six Finnish females with a 46, X, i(Xq) chromosome constitution (isochromosome for the long arm of the X chromosome) were measured from dental casts and compared with those of normal women, first-degree female relatives and 45, X females. Crown diameters of the 46, X, i(Xq) females were not only smaller than in the normal women but even smaller than the 45, X females. These findings can be considered indirect evidence that X chromosome gene(s) for tooth crown growth are most probably located on the short arm.     

Use of the centroid method of occlusion for studying the vertical and horizontal relationship of the mandible and maxilla

The aim of the present study was to verify whether the centroid method of occlusion for studying mandibular and maxillary growth enables accurate determination of vertical occlusal patterns (open and deep bite). Lateral cephalograms were obtained of Japanese adult females aged over 18 years of age with a Class II malocclusion (61 open bite and 47 deep bite), or a Class III type open bite (70 subjects) or deep bite (21 subjects) malocclusion. One-way analysis of variance followed by a Bonferroni's t-test was used to compare the results among these four groups. The Deltaabc area, which comprised the palatal, Ar-Gn, and A-B planes, was shown to be significantly larger in the open bite than in the deep bite group for both Class II and Class III malocclusion types (P < 0.01). There was no difference in the Deltaabc area between the Class II and Class III open bite groups or between the Class II and Class III deep bite groups. These findings suggest that the centroid method of occlusion is a versatile diagnostic technique that can accurately differentiate between vertical occlusal patterns of Class II and III types of malocclusion limited to Japanese adult females. The analytical method is also unaffected by gnathostatic differences according to Angle classification.     

颞下颌关节紊乱病、错(牙合)患者及大学生咬合的比较研究

目的 探讨评价咬合的2项指标（近远中向的安氏错He分类及垂直向和唇（颊）舌向的覆He覆盖关系）在颞下颌关节紊乱病（temporomandibular disorders,TMD)组、大学生志愿者（US）组及错He患者（MAL）组间有无明显差别。方法 100例TMD、100例MAL、268名US，共468人，取研究模观察。结果 ①MAL组安氏I类的比例低于其他2组（P＜0.05)；②MAL组前牙反He和深覆盖比例明显高于其他2组（P＜0.05)；③覆He覆盖异常指数（后牙每1处积5分，前牙每1处积分积3分），MAL组明显高于US组（P＜0.05)，而TMD组与MAL组和US组差异均无显著性（P＞0.05)。结论 影响美观的前牙异常治疗需求高，而咬合异常与TMD未见显著相关关系。     

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.     

A study in 47,XYY men of the expression of sex-chromosome anomalies in dental occlusion.

Occlusal traits were determined for 47,XYY men and compared with previous determinations of occlusal morphology in other sex-chromosome anomalies and in normal women and men. The 47,XYY men, like 47,XXY men, tended to have a mesial molar occlusion and a mandibular overjet more often than did other groups, while 45,X women (Turner patients) clearly had the highest frequency of distal occlusion and large overjet. The 47,XXY men had the highest frequency of most occlusal anomalies. As a whole, these and earlier findings suggest that the number of X or Y chromosomes is associated negatively with distal occlusion and lateral crossbite, whereas a positive association was found with mesial molar occlusion and scissors bite.     

Cephalometric evaluation of the anterior open bite treatment

The present study was aimed at evaluating the treatment changes of anterior open bite malocclusion cases treated by means of the Multiloop Edgewise Arch Wire technique, which is considered one of the more effective treatment modalities for anterior open bite malocclusions. The open bite sample was composed of 16 young adults, 4 males and 12 females. The normal occlusion sample, as a controlled sample was composed of 58 young adults who had pleasing facial profiles and normal occlusions with no experience of orthodontic or prosthodontic treatment. The normal sample was subdivided by the cephalometric vertical facial relationships. Forty adults with cephalometric vertical facial relationships within the normal range of Korean standards were classified as Normal Occlusion Group 1. Eighteen adults with an increased vertical facial relationship but with normal occlusion, were classified as Normal Occlusion Group 2. Thirty-nine reference points were digitized on each film, and the computerized cephalometric analysis was obtained with 8 skeletal, 10 dentoalveolar, 17 teeth angulations, and 4 occlusal plane measurements. Treatment changes were determined by the paired t test, and the structural differences between the four groups were tabulated by the Student’s t test. The treatment changes were observed mainly in the dentoalveolar region in the upper and the lower occlusal planes, accompanied by the uprighting of the posterior teeth to the occlusal plane through the distal tipping movement of the entire dentition. After the treatment, there was a tendency for the structural feature of the open bite group to approximate those of the normal occlusion group 2. This ascertains that the treatment changes of open bite malocclusion produced by means of the multiloop edgewise arch wire technique are similar to those found in the natural dentoalveolar compensatory mechanism. (Am J Orthod Dentofacial Orthop 1999;115:29-38)     

减数正畸治疗的咬合接触特征分析

目的:了解不同人群ICP咬合接触特征的差异以及正畸治疗对咬合的影响。方法:选取20名个别正常牙合者(A组)、20名错牙合畸形者(B组)、30名正畸治疗结束者(C组),通过Tee-test咬合分析系统对全牙列总接触面积(Total contact area,TCA)、全牙列咬合总力值(Total occlusion Force, TOF)、单位面积力值、咬合力中心点位置(Centre of Force, COF)、牙合不对称指数(Asymmetry index of occlusal force, AOF)、全牙列牙合力分布等数据进行分析比较。结果:A组TCA、TOF显著大于B、C组(P<0.05);C组的单位面积力值略小于A组,COF、AOF略大于A组,其组间差异无统计学意义,B组与A、C组间差异有统计学意义(P<0.05);A、B组的最大咬合力分布在第二磨牙区,C组的最大咬合力分布在第一磨牙区(P<0.05);不同性别间3组咬合测量项目差异均无统计学意义。结论:通过正畸治疗,咬合接触明显改善,咬合均衡性好,但未达到个别正常牙合的理想状态,提示正畸治疗后期的精细调整很重要。     

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.     

Effect of 45,X/46,XX mosaicism on root morphology of mandibular premolars.

The effect of X chromosome mosaicism on root morphology of mandibular premolars was studied in 14 females with 45,X/46,XX chromosome constitution. Occurrences of two-rooted premolars and the morphology of the roots were examined from orthopantomograms. Six (43%) of the 45,X/46,XX mosaics had two-rooted mandibular premolars. Two-rooted first premolars were found in four (29%) and second premolars in three (21%); in one, all four mandibular premolars were two-rooted. The results indicate that the frequency of two-rooted mandibular premolars was similar in 45,X/46,XX mosaics and in 45,X females, and in both groups significantly higher than in normal 46,XX females. Compared with 45,X females, the 45,X/46,XX mosaics showed a slight tendency toward more simplified root morphology in the first premolars. The findings suggest that the presence of normal 46,XX cells among the defective 45,X cells does not affect the development of the mandibular premolar roots. Furthermore, the results do not support the earlier proposal that the presence of normal 46,XX cells in 45,X/46,XX mosaic individuals would be reflected in gradual normalization of dental development.     

Bite force and temporomandibular disorder in juvenile chronic arthritis

summary The aim of this study was to investigate the functional condition of the stomatognathic system in children suffering from juvenile chronic arthritis, with respect to bite force and temporomandibular disorder in relation to radiographic abnormalities of the mandibular condyle, occlusal factors and systemic disease parameters. Thirty-five children with juvenile chronic arthritis were compared to 89 healthy children with an Angle Class I occlusion and 62 children with an Angle Class II malocclusion. Subjective symptoms and clinical signs of temporomandibular disorder and radiographic mandibular condylar changes were more common in children with juvenile chronic arthritis than in the two comparison groups. Maximal molar and incisal bite forces and maximal molar bite force endurance times were also significantly reduced in children with juvenile chronic arthritis. It is concluded that the differences between the groups are caused mainly by the systemic inflammatory disease itself, but a functional influence of weakened masticatory muscles cannot be excluded.     

Relationship among malocclusion, number of occlusal pairs and mastication

This study evaluated the relationship among malocclusion, number of occlusal pairs, masticatory performance, masticatory time and masticatory ability in completely dentate subjects. Eighty healthy subjects (mean age = 19.40 ± 4.14 years) were grouped according to malocclusion diagnosis (n = 16): Class I, Class Class II-2, Class III and Normocclusion (control). Number of occlusal pairs was determined clinically. Masticatory performance was evaluated by the sieving method, and the time used for the comminute test food was registered as the masticatory time. Masticatory ability was measured by a dichotomic self-perception questionnaire. Statistical analysis was done by one-way ANOVA, ANOVA on ranks, Chi-Square and Spearman tests. Class II-1 and III malocclusion groups presented a smaller number of occlusal pairs than Normocclusion (p < 0.0001), Class I (p < 0.001) and II-2 (p < 0.0001) malocclusion groups. Class I, and III malocclusion groups showed lower masticatory performance values compared to Normocclusion (p < 0.05) and Class II-2 (p < 0.05) malocclusion groups. There were no differences in masticatory time (p = 0.156) and ability (χ2 = 3.58/p= 0.465) among groups. Occlusal pairs were associated with malocclusion (rho = 0.444/p < 0.0001) and masticatory performance (rho = 0.393/p < 0.0001), but malocclusion was not correlated with masticatory performance (rho = 0.116/p= 0.306). In conclusion, masticatory performance and ability were not related to malocclusion, and subjects with Class I, II-1 and III malocclusions presented lower masticatory performance because of their smaller number of occlusal pairs.     

T-scan咬合力计在咬合板调(牙合)中的应用

目的用T-scan咬合力计评价咬合纸对咬合板调(牙合)的效果。方法收集20例咬合不协调所致的咀嚼肌疼痛患者,佩戴咬合板后,先用咬合纸对其进行调(牙合),达到咬合纸调(牙合)标准后再用T-scan检查调(牙合)效果,如有早接触点或(牙合)干扰点,继续调(牙合),直至无早接触及(牙合)干扰点,观察T-scan指导调(牙合)前后的咬合时间、咬合分离时间、左右侧牙弓咬合力百分比差值有无差异。结果 T-scan指导调(牙合)后的咬合时间、前伸咬合分离时间、左侧牙弓咬合分离时间、右侧牙弓咬合分离时间、左右侧牙弓咬合力百分比差值均小于T-scan指导调(牙合)前。其中,T-scan指导调(牙合)后的咬合分离时间、左右侧牙弓咬合力百分比差值相较于T-scan指导调(牙合)前具有统计学差异(P<0.05)。结论 (1)咬合纸检查咬合时,对于动态早接触点及(牙合)干扰点存在不足,在临床上可采取相应措施来改善。(2)T-scan咬合力计相较于咬合纸,能准确定位异常咬合接触点,指导咬合纸对咬合板调(牙合)后,患者的咬合明显改善。     

髁颈及髁颈下骨折术后非骨源性咬合关系紊乱因素探讨

目的 总结髁颈及髁颈下骨折解剖复位、坚强内固定术后影响咬合关系的非骨源性因素。方法 分析23例髁颈及髁颈下骨折经解剖复位、小型接骨板坚强内固定术后出现咬合紊乱的原因，并提出相应的处理措施。结果 23例术后咬合紊乱者均经曲面断层片及瓦氏位片复查，未发现小型接骨板变形、断裂以及骨折片再移位，但伴其他并发症(一过性面瘫2例；一过性下颌缘支损伤3例；感染2例；关节区疼痛2例；关节弹响及杂音1例)。结论 髁颈及髁颈下骨折虽经解剖复位、小型接骨板坚强内固定，且术后并无导致咬合紊乱的骨源性因素，仍有发生咬合紊乱的可能性。其原因为肌源性和关节源性。这时，不需再次手术复位，只需颌间弹性牵引及功能锻炼，个别情况下调He治疗即可恢复正常咬合关系。     

Effects of bite raising and occlusal awareness on tongue thrust in untreated children.

The purpose of this study was to determine the influence of conscious bite (occlusal awareness), with or without immediate bite raising, on tongue thrust during swallowing and speech. A total of 110 untreated children (age range, 7-12 years; mean, 9 years 8 months) were examined with various extraoral and intraoral observation tests. Subjects were divided according to sex and score on the labiolingual dysfunction index (LLDI) into high (LLDI-H) and weak (LLDI-W) dysfunction groups. A special, previously tested chocolate paste was used to map tongue and tooth contacts during task performance, including conscious bite (occlusal awareness) with and without bite raising. The bite was raised with an overlay or provisional occlusal plane placed unilaterally on the maxillary right molar. The results did not show any difference between boys and girls, but other findings were related to the LLDI score. Habitual mouth closure and swallowing without the provisional occlusal plane produced less pronounced bite contact in the LLDI-H group. Swallowing with conscious bite increased the bite contact in both groups but predominantly in the LLDI-H group. Tongue thrust reacted inversely to bite contacts: it was reduced when occlusion was perceived with and without bite raise but somewhat more with the provisional occlusal plane. The LLDI-W group was less affected. Tongue thrust was inhibited in both groups during speaking with bite raising and occlusal awareness. These results indicate that conscious bite helps to control the tongue. Slight raising of the bite increases occlusal awareness and its inhibiting effect on tongue thrust. A provisional occlusal plane or a similar overlay might be a useful adjunct in training the tongue to retrude in subjects with oral dysfunction.     

To Determine the Prevalence Rate of Malocclusion among 12 to 14-Year-Old Schoolchildren of Urban Indian Population (Bagalkot)

Aim: To determine the prevalence rates of different occlusal characteristics of permanent dentition in 12 to 14 years old children in Bagalkot city and to determine the differences in occlusal characteristics in the same children by age and sex. Materials and methods: A total of 1000 school going children between the age group of 12 to 14 years were selected in the study from Bagalkot city of India. All the occlusal parameters, such as molar relation, canine relation, overjet, overbite and crowding and spacing were recorded in a record sheet. The gender and sex difference was evaluated using Chi-square test. Results: According to the classification of Angle, the prevalence of class I, II and III malocclusions was 17.8, 30.1 and 1.6%, respectively. Ideal occlusion was 3.2% where as normal occlusion was 46.8%. An overjet of at least 4 mm or more was present in 15.2 and 7.2% had a reverse overjet. A total of 9.2 had an increased overbite and 10.6% had open bite. Conclusion: Highly significant (p < 0.001) age differences were found for overjet, overbite and highly significant (p < 0.001) gender differences were found for crowding and spacing. Clinical significance: The study gives the prevalence of malocclusion amongst 12 to 14 years old in urban Indian population. The data can be used for may research projects and gives us a better understanding of malocclusion in urban Indian population. Keywords: Malocclusion, Ethnic group, Occlusion epidemiology, Occlusal variation. How to cite this article: Phaphe S, Kallur R, Vaz A, Gajapurada J, Sugaraddy, Mattigatti S. To Determine the Prevalence Rate of Malocclusion among 12 to 14-Year-Old Schoolchildren of Urban Indian Population (Bagalkot). J Contemp Dent Pract 2012;13(3):316-321. Source of support: Nil Conflict of interest: None declared.     

The influence of an experimentally-induced malocclusion on vertebral alignment in rats: a controlled pilot study

There is a growing interest in the relationship between occlusion and posture because of a greater incidence of neck and trunk pain in patients with occlusal dysfunction. The study was designed to verify whether an alteration of the spinal column alignment may be experimentally induced in rats as a consequence of altering dental occlusion and also to investigate whether the spinal column underwent any further changes when normal occlusion was then restored. Thirty rats were divided into two groups. Fifteen (15) rats (test group) wore an occlusal bite pad made of composite resin on the maxillary right first molar for a week (T1). The same rats wore a second composite bite pad for another week on the left first molar in order to rebalance dental occlusion (T2). Fifteen rats were included in an untreated control group. All the rats underwent total body radiographs at T0 (before the occlusal pad was placed), at T1 (one week after application of a resin occlusal bite pad on the maxillary left first molar) and at T2 (one week after application of a second resin occlusal bite pad on the maxillary right first molar). A scoliotic curve developed in all the test rats at T1. There were no alterations of spinal position observed in any of the control rats. Additionally, the spinal column returned to normal condition in 83% of the test rats when the balance in occlusal function was restored. The alignment of the spinal column seemed to be influenced by the dental occlusion.     

Minimally Invasive Treatment of an Adult with Severe Pseudo Class III Malocclusion

Pseudo class III malocclusion is reverse anterior occlusion or anterior cross‐bite with first molars and canines in a class I relationship. It is very important to diagnose the pseudo class III from true skeletal class III. The combination of anterior displacement of the mandible, tooth wear, and loss of occlusal vertical dimension (OVD) in adults may result anterior cross‐bite. The key factor in diagnosis of this malocclusion is an interdisciplinary approach with an orthodontist. Cephalometric images are essential for diagnosis of pseudo class III mal‐occlusion. Most relevant publications on correcting this condition have recommended either full‐coverage restorations or extraction and placement of implants to correct this malocclusion. Advances of material and technology may help dental practitioners to restore tooth wear and OVD with a conservative approach without removing more tooth structures. This clinical report shows the treatment of pseudo class III with minimally invasive treatment using partial coverage restorations fabricated with lithium disilicate.     

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目的比较Ⅰ、Ⅱ、Ⅲ类错验及正畸治疗后患者与个别正常验的咬合力差异,为正畸临床诊断和术后稳定性评价提供参考。方法于2006年1月至2008年12月选择来大连大学附属口腔医院正畸科就诊的无正畸治疗史的Ⅰ、Ⅱ、Ⅲ类错铪患者110例及正畸治疗后患者42例,另选择个别正常矜志愿者28名。采用T-ScanⅡ咬合力分析系统,对其[牙合]力总值进行比较分析。结果Ⅰ、Ⅱ、Ⅲ类错[牙合]的验力总值均低于个别正常[牙合]（P〈0．05）;正畸治疗后患者虽获得良好的咬合关系,[牙合]力总值增加,但与个别正常[牙合]比较,差异仍有统计学意义（P〈0．05）。结论正畸治疗可改善咬合关系,增加[牙合]力总值,但与个别正常[牙合]的[牙合]力总值仍有差异,推断牙齿在建立良好的咬合关系后,仍需要一定时间的咬合面磨合、神经肌肉的改建,才能更好地发挥咬合功能。