Thin-plate spline analysis of the cranial base in African, Asian and European populations and its relationship with different malocclusions.

OBJECTIVES: To test the hypothesis that midline basicranial orientation and posterior cranial base length are discriminating factors between adults of different populations and its potential maxillo/mandibular disharmonies. DESIGN: Twenty-nine 2D landmarks of the midline cranial base, the face and the mandible of dry skull X-rays from three major populations (45 Asians, 34 Africans, 64 Europeans) were digitized and analysed by geometric morphometrics. We used, first, MANOVA to test for mean shape differences between populations; then, principal components analysis (PCA) to assess the overall variation in the sample and finally, canonical variate analysis (CVA) with jack-knife validations (N=1000) to analyse the anatomical features that best distinguished among populations. RESULTS: Significant mean shapes differences were shown between populations (P<0.001). CVA revealed two significant axes of discrimination (P<0.001). Jack-knife validation correctly identified 92% of 15,000 unknowns. In Africans the whole cranial base is rotated into a forward-downward position, while in Asians it is rotated in the opposite way. The Europeans occupied an intermediate position. African and Asian samples showed a maxillo/mandibular prognathism. African prognathism was produced by an anterior positioned maxilla, Asian prognathism by retruded anterior cranial base and increase of the posterior cranial base length. Europeans showed a trend towards retracted mandibles with relatively shorter posterior cranial bases. CONCLUSIONS: The results supported the hypothesis that basicranial orientation and posterior cranial base length are valid factors to distinguish between geographic groups. The whole craniofacial configuration underlying a particular maxillo-facial disharmony must be considered in diagnosis, growth predictions and resulting treatment planning.

Human craniofacial sphericity: a simultaneous analysis of frontal and lateral cephalograms of a Japanese population using geometric morphometrics and partial least squares analysis.

OBJECTIVES: The aim of this paper was to test Enlows morphological predictions of the "balloon model" of cranial head form patterns. This model predicts specific suites of morphological features in relation to basicranial flexure and skull globularity. DESIGN: 2D geometric morphometrics and partial least squares analysis (PLS) were used for simultaneous analysis of lateral and frontal X-rays of 41 adult males and females of a Japanese population with geometric morphometrics and partial least squares analysis. RESULTS: Reduction of the relative distance between basion and the posterior face, either because of basicranial flexure or overall basicranial re-orientation, was significantly related to increase of relative upper facial and dental arcade widths and a forward shift of the mandibular symphysis. These changes were unrelated to facial variations in height. CONCLUSIONS: In this population some aspects of Enlow's balloon model are supported while others should be modified, which challenges the balloon model of overall integration and cranial sphericity. This study suggests that variation in the posterior part of the cranium including the petrosals is unrelated to variation in facial and anterior basicranial regions. Partial least squares analysis is a useful tool for investigating craniofacial problems that require combining different X-ray views of the same individuals.

Low-intensity pulsed ultrasound (LIPUS) induces RANKL, MCP-1, and MIP-1beta expression in osteoblasts through the angiotensin II type 1 receptor.

Constant mechanical stress is essential for the maintenance of bone mass and strength, which is achieved through the cooperative functions of osteoblasts and osteoclasts. However, it has not been fully elucidated how these cell types mediate mechanical signals. Low-intensity pulsed ultrasound (LIPUS) therapy is a recently developed method for application of mechanical stress, and is used clinically to promote bone fracture healing. In the present study, we applied LIPUS to osteoblasts at different stages of maturation and analyzed their chemokine and cytokine expression. In comparison with their immature counterparts, mature osteoblasts expressed significantly higher levels of mRNAs for the receptor activator of nuclear factor kappa B ligand (RANKL), monocyte chemoattractant protein (MCP)-1, and macrophage-inflammatory protein (MIP)-1beta after a few hours of LIPUS treatment. Intriguingly, protein and mRNA expression of angiotensin II type 1 receptor (AT1), a known mechanoreceptor in cardiomyocytes, was detected in osteoblasts, and the level of expression increased significantly during cell maturation. Furthermore, LIPUS-induced extracellular signal-regulated kinase (ERK) phosphorylation and RANKL/chemokine expression was abrogated by a specific AT1 inhibitor. Thus, AT1 may play one of the essential roles in bone metabolism as a mechanoreceptor of osteoblasts.

Surgical repositioning of a developing maxillary permanent central incisor in a horizontal position: spontaneous eruption and root formation.

This report describes the surgical repositioning of a developing maxillary permanent central incisor in a horizontal position, followed by spontaneous eruption and root formation without orthodontic traction. Surgical exposure of the right central incisor was achieved. A 7-year-old boy referred for orthodontic consultation. Radiographic examination showed the crown of a maxillary right central incisor to be positioned horizontally with root formation at the initial stage. The surgically repositioned incisor (by a close-eruption surgical flap technique) spontaneously erupted into correct alignment after 2 years 3 months. The erupted incisor remained vital and responded normally to percussion, mobility and sensitivity testing. The soft tissue, periodontal attachment, gingival contour and probing depths were normal. Follow-up radiographs confirmed the continued development of the root, with revascularization of the pulp and a normal appearance of the periodontal space and lamina dura. There was, however, shorter root formation and a narrower root cavity compared with the contralateral incisor. As a result, no orthodontic traction and alignment were required. This method of surgical repositioning is a viable alternative to the traditional approach of extraction or surgical exposure followed by orthodontic traction for a developing maxillary permanent central incisor in a horizontal position.

Variation in the cranial base orientation and facial skeleton in dry skulls sampled from three major populations.

The aim of this study was to analyse the effects of cranial base orientation on the morphology of the craniofacial system in human populations. Three geographically distant populations from Europe (72), Africa (48) and Asia (24) were chosen. Five angular and two linear variables from the cranial base component and six angular and six linear variables from the facial component based on two reference lines of the vertical posterior maxillary and Frankfort horizontal planes were measured. The European sample presented dolichofacial individuals with a larger face height and a smaller face depth derived from a raised cranial base and facial cranium orientation which tended to be similar to the Asian sample. The African sample presented brachyfacial individuals with a reduced face height and a larger face depth as a result of a lowered cranial base and facial cranium orientation. The Asian sample presented dolichofacial individuals with a larger face height and depth due to a raised cranial base and facial cranium orientation. The findings of this study suggest that cranial base orientation and posterior cranial base length appear to be valid discriminating factors between different human populations.

Petrosal orientation and mandibular ramus breadth: evidence for an integrated petroso-mandibular developmental unit.

The absolute and relative breadths of the mandibular ramus (MRB) display substantial variation in modern humans, and are of analytical value in paleoanthropology. According to Enlow et al. ([1969] Am. J. Orthod. 56:6-23), the ramus is the growth counterpart of the middle cranial fossa (MCF) and the pharynx. Such counterpart principles state that variation in ramus breadth is a frequent function of the horizontal alignment of the MCF, and both structures tend to covary within and between populations. These authors also suggested that lateral parts of the basicranium have a particular importance in the positioning of facial components. In the present study, this hypothesis is tested, and relationships between midline and lateral basicranial elements and ramus breadth variation are explored. Two-dimensional landmarks taken from lateral radiographs of adult crania representative of three modern human populations (Europeans, West Africans, and Japanese) were analyzed by geometric morphometry. Our results are consistent with previous counterpart analyses. Furthermore, our findings highlight the significance of the orientation of the petrous temporal to modern human mandibular ramus variation. Variation in the orientation of the petrosal bone appears to alter the spatial position of the mandible and influences MRB. Developmental integration of a petroso-mandibular unit may have important paleoanthropological implications.

A new method of inhalation anesthesia with nasopharyngeal insufflation in rat experiment.

We have established a new method of anesthesia with nasopharyngeal insufflation for intraoral procedure in rodents. Twelve male Wistar rats weighing 330-390 g were used in this study. Insertion of a feeding tube 1.0 mm in diameter coated with 2% xylocaine jelly was inserted into the nasal cavity approximately 25 mm from the naris, and anesthetization with mixed gas of 100% oxygen with 3-4% enflurane at 0.25-0.5 l/min flow rate was achieved. Using this anesthetic method, a chronic experiment comprising 1-h/day experimental procedure was carried out for 14 days. This method enabled, 1) simple and safe operation of the induction, emergence and anesthetic depth, 2) experimental procedures on the dental/oral region, 3) avoidance of the dyspnea and tachypnea, and 4) avoidance of cumulative effects in daily anesthesia.

Unilateral advancement of the maxillary minor segment by distraction osteogenesis in patients with repaired unilateral cleft lip and palate: report of two cases.

OBJECTIVE: Collapse of the maxillary minor segment with lateral crossbite is a common feature in patients with repaired unilateral cleft lip/palate because of maxillary alveolar bony defect and palatal scar tissue. Distraction osteogenesis (DOG) is an effective technique of lengthening and augmentation for bone and gingiva. This case report describes the effects of unilateral advancement of the maxillary minor segment by DOG in two patients with the repaired unilateral cleft lip/palate.