The teaching of prosthodontic care for older people: a non-rote philosophy

This essay complements that de Baat et al¹ in the last issue with emphasis on the importance of the variability between individual older people. The consequent need for an open minded approach towards planning Prosthodontics is discussed, based on each patient's motivation for aesthetics, function, comfort and self esteem. Both functional expectations and motivation to learn effective health behaviour vary widely, and evaluation of both is essential for realistic planning because further tooth loss and the need for partial dentures occur so frequently. The consequent variation in plans raises the question – which are the strategic teeth to maintain a stable dental occlusion or a future tooth stabilised denture? For undergraduates this demands a non-rote approach to learning.     

Osteologic development of the viscerocranial skeleton in sea bream: alternative ossification strategies in teleost fish

The ontogeny of the viscerocranial skeleton of sea bream Sparus aurata larvae was studied from 1 to 90 days post-hatching. In the smallest specimens analysed at 2·7 mm L _N no cephalic elements were present and at 3·1 mm L _N the following cartilaginous structures were visible: trabecula cranii, auditory capsule, Meckel's cartilage, quadrate, hyosymplectic cartilage, sclerotic, hypohyal, ceratohyal epihyal cartilage, interhyal, hypobranchial 1 and ceratobranchial 1. The only structure ossified at this size is the maxillary and the next ossified structures to appear are the preopercle and opercle at about 3·7 mm L _N. The last bones to appear are infraorbital 2 and 6 at 15·1 mm L _S. The first cartilaginous elements and structures to ossify in S. aurata appear to be related with functional requirements, so that structures involved directly in feeding and breathing generally appear and ossify before those that are not. The ontogeny of different regional structures revealed that generally the dermal bones ossify before the cartilage replacement bones. Comparison of S. aurata viscerocranial skeleton ontogeny with that of phylogenetically distant fish demonstrates that different ossification strategies exist in higher and lower teleost fish.     

Socio-medical condition and oral functional status in an older institutionalised population

Objectives: To investigate the association between the general medical condition, the socio-economic status, and some factors related to the functional status of the stomatognathic system. Design: A survey in an elderly population. Subjects: 257 older adults, with a mean age of 83.7 years. Setting: Residential homes for the elderly. Intervention: Examination of the medical records on the overall health and the drugs consumed, a structured interview on the socio-economic status, the complaints for xerostomia, the subjective chewing difficulties, and a clinical evaluation of the number of natural teeth and the number of posterior occluding pairs of teeth contacts (premolars and molars). Results: Multiple pathology and polypharmacy were recorded. 25% of the residents had no occluding posterior tooth contact (natural or prosthetic) and 62% were edentulous. 43% of the residents reported complaints for xerostomia, and 46% for chewing difficulties when eating specific food types. Xerostomic feelings and chewing problems were not related to age. Chewing difficulties were not related to the number of natural teeth, but to the number of posterior occluding teeth contacts, natural or prosthetic (less than two). From all medical conditions examined, only the psychiatric disorders were significantly related to dental status (p<0.05). Moreover, the number of remaining natural teeth was related to socio-economic status, while the number of posterior occluding teeth contacts was also inversely related to the duration of institutionalisation (p<0.05). Conclusions: Psychiatric disorders, low socio-economic status and increased duration of institutionalisation were most closely related to poor dental status. The presence of more than two posterior occluding teeth contacts, natural or prosthetic, benefit the very old patient in terms of reduced subjective chewing difficulty. A formal oral care delivery system for the institutionalised elderly, and particularly for those suffering from psychiatric disorders, is imperative.     

Temporal restriction of migratory and lineage potential in rhombomere 1 and 2 neural crest

Migratory cranial neural crest cells differentiate into a wide range of cell types, such as ectomesenchymal tissue (bone and connective tissues) ventrally in the branchial arches and neural tissue (neurons and glia) dorsally. We investigated spatial and temporal changes of migration and differentiation potential in neural crest populations derived from caudal midbrain and rhombomeres 1 and 2 by back-transplanting cells destined for the first branchial arch and trigeminal ganglion from HH8-HH19 quail into HH7-HH11 chicks. Branchial arch cells differentiated down ectomesenchymal lineages but largely lost both the ability to localize to the trigeminal position and neurogenic differentiation capacity by HH12-HH13, even before the arch is visible, and lost long distance migratory ability around HH17. In contrast, neural crest-derived cells from trigeminal ganglia lost ectomesechymal differentiation potential by HH17. Despite this, they retain the ability to migrate into the branchial arches until at least HH19. However, many of the neural crest-derived trigeminal ganglia cells in the branchial arch localized to the non-neural crest core of the arch from HH13 and older donors. These results suggest that long distance migration ability, finer scale localization, and lineage restriction may not be coordinately regulated in the cranial neural crest population.     

Constitutive expression of preproendothelin in the cardiac neural crest selectively promotes expansion of the adventitia of the great vessels in vivo

Cardiac neural crest cells are essential for normal development of the great vessels and the heart, giving rise to a range of cell types, including both neuronal and non-neuronal adventitial cells and smooth muscle. Endothelin (ET) signaling plays an important role in the development of cardiac neural crest cell lineages, yet the underlying mechanisms that act to control their migration, differentiation, and proliferation remain largely unclear. We examined the expression patterns of the receptor, ET(A), and the ET-specific converting enzyme, ECE-1, in the pharyngeal arches and great vessels of the developing chick embryo. In situ hybridization analysis revealed that, while ET(A) is expressed in the pharyngeal arch mesenchyme, populated by cardiac neural crest cells, ECE-1 expression is localized to the outermost ectodermal cells of the arches and then to the innermost endothelial cells of the great vessels. This dynamic pattern of expression suggests that only a subpopulation of neural crest cells in these regions is responsive to ET signaling at particular developmental time points. To test this, retroviral gene delivery was used to constitutively express preproET-1, a precursor of mature ET-1 ligand, in the cardiac neural crest. This resulted in a selective expansion of the outermost, adventitial cell population in the great vessels. In contrast, neither differentiation nor proliferation of neural crest-derived smooth muscle cells was significantly affected. These results suggest that constitutive expression of exogenous preproET-1 in the cardiac neural crest results in expansion restricted to an adventitial cell population of the developing great vessels.     

A tale of two cities: The genetic mechanisms governing calvarial bone development

The skull bones must grow in a coordinated, three‐dimensional manner to coalesce and form the head and face. Mammalian skull bones have a dual embryonic origin from cranial neural crest cells (CNCC) and paraxial mesoderm (PM) and ossify through intramembranous ossification. The calvarial bones, the bones of the cranium which cover the brain, are derived from the supraorbital arch (SOA) region mesenchyme. The SOA is the site of frontal and parietal bone morphogenesis and primary center of ossification. The objective of this review is to frame our current in vivo understanding of the morphogenesis of the calvarial bones and the gene networks regulating calvarial bone initiation in the SOA mesenchyme.     

Platelet-derived growth factor C plays a role in the branchial arch malformations induced by retinoic acid

BACKGROUND: All-trans-retinoic acid (RA) can produce branchial arch abnormalities in postimplantation rodent embryos cultured in vitro. Platelet-derived growth factor C (PDGF-C) was recently identified as a member of the PDGF ligand family. Many members of the PDGF family are essential for branchial arch morphogenesis and can be regulated by RA. The roles of PDGF-C in branchial arch malformations induced by RA and possible mechanisms were investigated. METHODS: In whole embryo culture (WEC), mouse embryos were exposed to RA at 0, 0.1, 0.4, 1.0, or 10.0 microM, PDGF-C at 25, 50, or 75 ng/mL, or PDGF-C at 25, 50, or 75 ng/mL containing 0.4 microM RA. After 48 h of culture, mouse embryos were examined for dysmorphogenesis, and whole-mount immunohistochemistry was applied to PDGF-C. In explant cultures, explants were exposed to the same doses of RA and PDGF-C as WEC. Semiquantitative RT-PCR, zymography, and reverse zymography were used to evaluate the expressions and activities of matrix metalloproteinase (MMP)-2, MMP-14, and tissue inhibitor of metalloproteinase (TIMP)-2. RESULTS: PDGF-C was reduced by RA, and exogenous PDGF-C rescued the branchial arch malformations induced by RA. Moreover, PDGF-C prevented RA-induced inhibition of the migratory ability of mesenchymal cells in the first branchial arch, by regulating the expressions of MMP-2, MMP-14, and TIPM-2. CONCLUSIONS: Our results suggest that RA exposure reduces the expression of PDGF-C. The branchial arch malformations resulting from fetal RA exposure are caused at least partially by loss of PDGF-C and subsequent misregulations of the expressions of MMP-2, MMP-14, and TIMP-2.     

对比分析不同矫治方法对青少年正畸患者唾液趋化因子、龈沟液炎症因子表达及牙周健康的影响

摘要 目的：对比分析不同矫治方法对青少年正畸患者唾液趋化因子、龈沟液炎症因子表达及牙周健康的影响。方法：选取我院2020年1月到2023年1月收治的100例正畸治疗的青少年患者,应用随机数字表法将其进行回顾性分析,其中30例患者采取Twin-Block矫治器进行治疗,将其分为Twin-Block组,30例患者采取直丝弓矫治器治疗,将其分为直丝弓组,40例患者采取无托槽隐性矫治器治疗,将其分为无托槽组。对比三组患者的矫正满意度,治疗前后唾液趋化因子、龈沟液炎症因子及牙周健康指标水平变化。结果：无托槽组咀嚼功能、美观程度、舒适性、方便程度满意度评分高于Twin-Block组和直丝弓组（P＜0.05）;矫治半年后,无托槽组CXCL13、CXCL11、CXCL10、CXCL8相关唾液趋化因子水平低于直丝弓组和Twin-Block组,Twin-Block组低于直丝弓组（P＜0.05）;三组患者矫治半年后,无托槽组IL-1β、TNF-α表达水平低于直丝弓组和Twin-Block组,Twin-Block组低于直丝弓组（P＜0.05）;矫治半年后,无托槽组CAL、PD、BI、PLI水平低于直丝弓组和Twin-Block组,Twin-Block组低于直丝弓组（P＜0.05）。结论：无托槽隐性矫治器在青少年正畸治疗患者满意度优于Twin-Block矫治器和直丝弓矫治器,但无托槽隐性矫治器治疗过程中对患者唾液趋化因子、牙龈雅正反应及牙周健康水平影响较小,临床可依照患者经济情况及对美观程度的要求综合选择。     

Gill‐arch musculature of the quillback carpiodes cyprinus (cypriniformes: catostomidae) with a comparison to cyprinids

Although the gill‐arch osteology of Cypriniformes has been well studied, comparable works on gill‐arch musculature are scarce. The focus of previous studies has been on Cyprinidae while other families have received little or no attention. Consequently, generalizations for Cypriniformes have been made from the musculature of cyprinid gill‐arches. This study describes the gill‐arch musculature of a catostomid, the quillback Carpiodes cyprinus, and demonstrates that there are striking differences in the overall gill‐arch musculature of catostomids in comparison to cyprinids, especially in the dorsal gill‐arch region. Of the 23 muscles found in the dorsal gill‐arch region of cyprinids, only 13 were present in C. cyprinus. Muscles that are absent include adductores 1–5, levator internus 4, levator ceratobranchialis 5 accessorius, retractor ceratobranchialis 5 externus, retractor ceratobranchialis 5 internus, and the retractor ceratobranchialis 5 transversus. In the ventral gill‐arch region, the rectus communis is absent. The derived scrolling shape of the dorsal gill‐arch skeleton associated with food processing is likely related to the change in musculature. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.