Vitamin D and skeletal tissues

It is now accepted that vitamin D is an integral part of a complex endocrine system, one with far-reaching implications in mineral metabolism. Reviews of the sources, functions and metabolism of vitamin D, as currently understood, are presented as a prelude to discussions of the role of vitamin D in calcium and phosphorous homeostatis and possible specific roles for vitamin D in mineralized tissues. Data describing a possible regulatory function for vitamin D in bone and bone protein metabolism are presented. Some of the controversy which presently exists regarding the biochemical mechanism of the action of this vitamin is discussed. Finally, the possible relationship of vitamin D and disorders of skeletal tissues is described.     

A longitudinal evaluation of the skeletal profile of treated and untreated skeletal Class II individuals

This study evaluated the changes in the skeletal profile of Class II subjects submitted to orthodontic treatment. The experimental group comprised the lateral cephalograms of 30 Brazilian subjects (17 female and 13 male subjects) obtained between the mean ages of 11.1 years (initial) and 15.1 years (final) and treated with cervical headgear and edgewise appliance. The control group comprised the lateral cephalograms of 30 Canadian individuals (13 females and 17 male individuals) at the ages of 6, 9, 12, 14, and 16 years from the Burlington Growth Study University of Toronto, Canada, who did not receive any kind of orthodontic treatment. The results demonstrated a reduction in the convexity of the skeletal profile of both groups. However, this change was only significant for the Canadian sample of 6- to 9-year olds (P < .01), whereas reduction was greater for the Brazilian group and was significant between the initial and final ages (P < .01). In the Canadian control group, the maxilla presented a tendency toward a forward displacement (P < .01), which was not observed in the experimental group (P < .01). The mandible presented a forward displacement in both groups; yet, only the Canadian group demonstrated a significant difference, which occurred between 9 and 16 years (P < or = .01).     

Comparison of skeletal anchored facemask and tooth-borne facemask according to vertical skeletal pattern and growth stage

Objective:To compare the treatment effects between skeletal anchored facemask (SAFM) and tooth-borne facemask (TBFM) on different maturation stages and vertical skeletal patterns.Materials and Methods:In this retrospective study, 28 patients who were treated with TBFM treatment and 19 patients who were treated with SAFM were reviewed. Cephalograms at the beginning and end of facemask application were obtained and assessed. Each treatment group was divided according to skeletal maturity and facial angle type. Nonparametric Mann-Whitney U-test was used for comparisons of maturity stage and vertical skeletal type between the treatment groups.Results:SAFM produced a significant increase in the anterior-posterior position of orbitale (SNOr) and A point (N. per. to A). The high mandibular plane angle group of SAFM revealed greater anterior movement than that of TBFM without opening of the mandibular plane. In the SAFM group, the angulation of the maxillary incisors was retroclined at CVM3 compared to CVM4. In the younger group (CVM3), SAFM showed greater changes in the variables of orbitale (2.909°) and maxillary length (5.818 mm), compared to TBFM.Conclusions:Compared with the TBFM group, the findings suggest significant advantages for the SAFM group for relative skeletal maturity and vertical skeletal pattern.     

Vitamin D and skeletal tissues

It is now accepted that vitamin D is an integral part of a complex endocrine system, one with far-reaching implications in mineral metabolism. Reviews of the sources, functions and metabolism of vitamin D, as currently understood, are presented as a prelude to discussions of the role of vitamin D in calcium and phosphorous homeostatis and possible specific roles for vitamin D in mineralized tissues. Data describing a possible regulatory function for vitamin D in bone and bone protein metabolism are presented. Some of the controversy which presently exists regarding the biochemical mechanism of the action of this vitamin is discussed. Finally, the possible relationship of vitamin D and disorders of skeletal tissues is described.     

Physiology and pathophysiology of skeletal muscle contractions

An overview is presented of the physiology and pathophysiology of dynamic skeletal muscle contractions in the intact living organism. Dynamic muscle activities are divided into concentric contractions with shortening of muscle fibres and the production of positive work, and eccentric contractions with lengthening of muscle fibres and the production of negative work. In positive work, muscle tension overcomes external forces. In negative work, external forces overcome muscle tension. The latter phenomenon, with relatively few active motor units, explains the injuries induced by eccentric contractions. Both the contractile and non-contractile elements are involved in the muscle injuries and, clinically, they are referred to as myofibrositis.     

正畸治疗中磨牙的拔除和保留（四十五）——牙槽外正畸支抗钉种植的部位及应用

目的：分析微螺钉作为骨性之抗在牙槽外区域种植的部位及其临床应用。方法：总结近3年内100例应用骨性支抗辅助治疗的正畸病例的支抗钉应用情况。结果：作为骨性支抗,微螺钉植入部位主要在上颌颧牙槽嵴和下颌颊棚区。结论：骨性支抗实现了真正意义上的绝对支抗。     

Physiology and pathophysiology of skeletal muscle contractions

An overview is presented of the physiology and so-called pathophysiology of static muscle contractions in the intact living organism. Static muscle activity produces no external mechanophysical work, but is used for fixation. Contingent upon the levels of the generated forces, and the duration of the isometric contractions, static activities give rise to fatigue and pains. The discomforts are viewed as somatic responses that are normally within physiological limits. That is, upon cessation of isometric contractions there is usually rapid recovery from the discomforts, and they do not normally induce chronic lesions.     

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提要：对临床不同骨性偏颌畸形进行分析，介绍诊断要点与治疗方法。骨性偏颌畸形主要表现为水平向与垂直向不对称；可以发生在上颌骨和（或）下颌骨，以下颌骨骨性不对称更为多见。咬合平面倾斜是骨性偏颌畸形的主要特征；骨性偏颌畸形的牙齿代偿具有左右侧、上下颌的不一致性；双侧下颌骨髁状突发育不对称是导致骨性偏颌畸形的主要原因；骨性偏颌畸形应从水平与垂直方向进行综合评估。正畸-正颌联合治疗是治疗骨性偏颌畸形的最佳方法；倾斜牙合平面的纠正是骨性偏颌畸形治疗的关键。     

Relationship of skeletal pattern and nasal form

This article investigates the relationship of skeletal facial pattern and soft-tissue nasal form. The case sample comprises 123 white female subjects, aged 11.0 to 20.6 years, with no histories of pathology, trauma, surgical intervention, or orthodontic treatment. Measurements were made from cephalometric radiographs, posteroanterior radiographs, and the physioprint photographs. Skeletal classifications were based on the relationship of the maxilla to the mandible; the three classifications were straight profile, retrusive chin profile, and prognathic profile. Pearson product--moment correlation coefficients were used to test intercorrelations of all quantitative variables (including age) with each other. Correlations were highly significant for age, the three profile measurements, and two of the frontal measurements. Hence, noses and skeletal structures showed, as expected, increases with age. Also, profile measurements were highly significantly correlated; larger noses were larger in all profile dimensions. A stepwise discriminant analysis was used to study nonquantitative categories of nasal shape (straight, convex, and concave). This analysis indicated that more than 86% of patients in the sample of 123 demonstrated a correlation of nasal shapes with specific skeletal groupings. Patients with straight profiles tended to have straight noses; convex profiles accompanied convex nasal shapes; and concave profiles were found with concave nasal shapes. The clinical significance of this research is to emphasize the importance of total facial harmony (especially nasal shape) during orthodontic diagnosis and treatment planning.     

Comparisons between dental and skeletal ages

Data from 694 untreated children seen in a private orthodontic practice were used to analyze associations between dental and skeletal maturity. Dental ages were obtained by comparison with Bolton Standards; skeletal ages were assessed using the Greulich-Pyle atlas. In some children the difference between the dental and skeletal ages was as large as 36 months; the difference was less than 6 months in fewer than 40% of the children. Regression analyses showed only moderate associations between these measures. One measure of maturity cannot be inferred from the other.     

Mandibular shape and skeletal divergency.

Pre-treatment lateral cephalograms of 41 skeletal Class I girls aged 11 to 15 were divided according to MP-SN angle: lower than 28 degrees (hypodivergent, 10 girls), between 31 and 34 degrees (normodivergent, 18 girls), or larger than 37 degrees (hyperdivergent, 13 girls). The mandibular outlines were traced and digitized, and differences in shape were quantified using the elliptic Fourier series. Size differences were measured from the areas enclosed by the mandibular outlines. Shape differences were assessed by calculating a morphological distance (MD) between the size-independent mean mathematical reconstructions of the mandibular outlines of the three divergency classes. Mandibular shape was different in the three classes: large variations were found in hyperdivergent girls versus normodivergent girls (MD = 4.61), while smaller differences were observed in hypodivergent girls (MD versus normodivergent 2.91). Mean size-independent mandibular shapes were superimposed on an axis passing through the centres of gravity of the condyle and of the chin. Normodivergent and hyperdivergent mandibles differed mostly at gonion, the coronoid process, sigmoid notch, alveolar process, posterior border of the ramus, and along the mandibular plane. A significant size effect was also found, with smaller mandibles in the hyperdivergent girls.     

颅骨发育生物学

对于艺术家,面貌是灵魂的镜子;对于生物学家,面貌反映了显著的结构多样性——试想一下斗牛犬或猎犬与加拉帕戈斯云雀间的区别。面部骨骼形态的巨大差异是如何产生的?它的发育机制与身体其他部位的骨骼发育机制相同吗?答案就在于产生神经嵴细胞、控制其迁移并指导其向软骨和骨分化的分子机制。“面貌究竟是什么?是相片?是妆容?抑或是这个或那个画家绘制的肖像?…难道每个人不是以自己特别的方式看自己的吗?其实,畸形是不存在的。”PabloPicasso[1]语。