The Anatomical Society's Core Anatomy Syllabus for Dental Undergraduates.

The Anatomical Society has developed a series of learning outcomes in consultation with dentists, dental educators and anatomists delivering anatomical content to undergraduate dental students. A modified Delphi methodology was adopted to select experts within the field that would recommend core anatomical content in undergraduate dental programmes throughout the UK. Utilising the extensive learning outcomes from two UK Dental Schools, and neuroanatomy learning outcomes that remained outside the Anatomical Society's Core Gross Anatomy Syllabus for Medical Students, a modified Delphi technique was utilised to develop dental anatomical learning outcomes relevant to dental graduates. The Delphi panel consisted of 62 individuals (n = 62) from a wide pool of educators associated with the majority of undergraduate dental schools in the UK, representing a broad spectrum of UK Higher Education Institutions. The output from this study was 147 anatomical learning outcomes deemed to be applicable to all dental undergraduate programmes in the UK. The new recommended core anatomy syllabus for dental undergraduates, grouped into body regions, offers a comprehensive anatomical framework with which to scaffold clinical practice. The syllabus, presented as a set of learning outcomes, may be used in a variety of pedagogic situations, including where anatomy teaching exists within an integrated dental curriculum (both horizontally in the basic sciences part of the curriculum and vertically within the clinical years).

Parental exposures and risk of nonsyndromic orofacial clefts in offspring: a case-control study in Greece.

OBJECTIVE: To investigate the association between cleft lip and/or palate and nongenetic factors in Greece. METHODS: We designed a case-control study including 35 patients with nonsyndromic cleft lip and/or palate, retrospectively selected, and 35 control patients matched for prefecture of residence, prospectively selected from pediatric population hospitalized for abdominal pain or injury. Parents were interviewed about drug uptake, diseases, habits, non-occupational exposure to pollutants, and occupation. Questions covered the period from one year before until three months after conception. RESULTS: High-risk paternal occupations (mostly farmers) were significantly more frequent in cleft lip and/or palate than in controls (p=0.039) and increased significantly the cleft lip and/or palate risk in offspring (OR: 3.00; 95% CI: 1.03-8.70). Maternal occupation did not correlate with cleft lip and/or palate. Parental disease, drugs uptake, hazardous habits, maternal folate supplementation and non-occupational exposure to pollutants did not correlate with cleft lip and/or palate. There was a suggestion of increased risk with maternal passive exposure to tobacco (OR: 1.81; 95% CI: 0.69-4.74) and with residential proximity to industries (OR: 1.70; 95% CI: 0.61-4.74). CONCLUSIONS: Paternal high-risk occupations probably exert a teratogenic effect on spermatogenesis or result in maternal contamination, and deserve specific preventive policies. The relation of smoking and residential proximity to industries with occurrence of cleft lip and/or palate deserves further study.

The relationships between learning outcomes and methods of teaching anatomy as perceived by professional anatomists.

Changes in the teaching of gross anatomy have often involved decreasing student contact time alongside the use of new methods for teaching. However, there remains controversy over teaching methods and about whether cadaveric dissection by students should remain the preferred method. Furthermore, decisions concerning changes to curricula are more likely to be taken by choosing a method of teaching rather than by proper evaluation of what are the desired learning outcomes for a course in anatomy. The purpose of this study was to ascertain the attitudes of anatomists in Europe towards the methods of teaching best fitting a series of learning outcomes for anatomy and secondarily to test the hypothesis that, from evaluation of learning outcomes, anatomy is best taught by cadaveric dissection by the students. About 113 completed questionnaires were received from anatomists who are employed at higher education institutions that use various teaching methods. Most anatomists (69%) favored the use of cadaveric dissection above other teaching methods when considering the whole series of learning comes, this method seeming to achieve a range of different course aims/objectives, P < 0.001; Kruskal-Wallis). Consequently, these findings are consistent with our initial hypothesis. However, when individual learning outcomes were considered, the relationship was not so clear cut and, for example, little difference was discernible between teaching methods when considering learning outcomes related to the acquisition of anatomical knowledge. The use of human cadaveric dissection gained more approval when the skills-base was considered rather than just the content(knowledge)-base of an anatomical course.

Upper lip blanching and diplopia associated with local anaesthesia of the inferior alveolar nerve.

A case of transient left lateral rectus nerve palsy, following an inferior alveolar nerve block to enable the surgical removal of a permanent mandibular left third molar tooth, is reported. The anatomy related to this case is considered together with suggestions for management of such patients.

Perception of medical students towards the clinical relevance of anatomy.

Recent developments worldwide in medical curricula have often led to major cuts in the teaching of human anatomy. Indeed, it is perceived by some that gross (topographical) anatomy has an exaggerated importance in the initial training of doctors. The value of anatomy consequently has frequently been considerably diminished within medical curricula that have reduced factual content. To date, however, there have been no objective studies into the perceived relevance of anatomy to clinical medicine that have aimed to quantify the attitudes of medical students. On the basis of responses to an attitude analysis questionnaire devised according to the precepts of Thurstone and Chave (The Measurement of Attitude: A Psychophysical Method and Some Experiments with a Scale for Measuring Attitude Toward the Church. Chicago, IL: University of Chicago Press, 1951), we investigated the perception of medical students at Cardiff and Paris towards the importance of gross anatomy to clinical medicine. This was undertaken during the early stages of their studies (when they were newly-admitted to university and were about to commence anatomy courses), immediately after finishing their anatomy courses, and later in the final year of medical studies. The results suggest that, even where there might be geopolitical and cultural backgrounds, students at all stages of their medical course share with professional anatomists the view that anatomy is a very important subject for their clinical studies. Thus, contrary to the unquantified beliefs of those who are sceptical about the purpose and value of anatomy in an undergraduate medical curriculum, the students themselves do not appear to share such beliefs.

Attitudes of professional anatomists to curricular change.

Throughout the world, recent developments in medical curricula have led to marked changes in the teaching of gross anatomy. This change has involved decreasing curricular student contact time and the use of new methods for anatomical teaching. Some "modern" anatomists have welcomed the arrival of these novel methods while other, more "traditional," anatomists have fought to maintain the use of cadaveric dissection. Consequently, controversy over teaching methods has developed to the point that "modernist" and "traditionalist" views within the community of professional anatomists seem to have diverged such that the importance of gross anatomy in the medical curriculum is disputed and that cadaveric dissection by students is no longer the preferred method of teaching. This study tests this hypothesis using Thurstone and Chave attitude analyses to assess attitudes to educational change and the importance of anatomy in medicine and a matrix questionnaire that required professional anatomists to relate course aims to different teaching methods. In total, 112 completed questionnaires were received from anatomists who are employed at higher education institutions that use various teaching methods and who span the academic hierarchy. The results suggest that over 90% of anatomists favor educational change and approximately 98% of professional anatomists believe that gross anatomy has an important role to play in clinical medicine. A clear majority of the anatomists (69%) favored the use of human cadaveric dissection over other teaching methods (this method seeming to achieve a range of different course aims/objectives) (P < 0.001; Kruskal-Wallis). Using Kruskal-Wallis statistical tests, the order-of-preference for teaching methods was found to be as follows: 1. Practical lessons using cadaveric dissection by students. 2. Practical lessons using prosection. 3. Tuition based upon living and radiological anatomy. 4. Electronic tuition using computer aided learning (CAL). 5. Didactic teaching alone (e.g. lectures/class room-based tuition). 6. Use of models. The preference for the use of human cadaveric dissection was evident in all groups of anatomists, whether "traditionalist" or "modernist" (P = 0.002, Chi-squared). These findings are therefore not consistent with our initial hypothesis.

Ultrastructural characterization of the mesenchyme of the facial processes during development of the rat intermaxillary segment.

This study quantifies ultrastructural changes within the mesenchyme of the maxillary and medial/lateral nasal processes before and after formation of the intermaxillary segment. At both day 11 and day 13 of development, 4 fetal rat heads were fixed with 3% glutaraldehyde and processed for electron microscopy. Differences between cells within the facial processes were discerned at day 11 of gestation. Significantly more rough endoplasmic reticulum was present in the cells of the maxillary processes than in the lateral nasal processes (p < .05), and a greater number of cell projections was found in the maxillary processes than in the medial nasal processes (p < .05). At day 13, no significant differences were found in the facial processes. Of particular note, a consistent increase in the number of cell projections within all the facial processes was found on day 13 when compared with day 11 (p < .05). This change may be related to intercellular signaling between the mesenchymal cells at the time of onset of major histogenic changes.

Apoptosis in the connective tissues of the periodontal ligament and gingivae of rat incisor and molar teeth at various stages of development.

Apoptosis in the periodontal connective tissues was studied using the TUNEL technique, supported by electron microscopy. For 16 rats (aged 3, 8, or 104 weeks), nuclear fragmentation was assessed using the TUNEL technique (for 4 of the animals aged 8 weeks, incisor eruption was experimentally increased by trimming of teeth to the gingival margin--unimpeded eruption). A further 8 rats (aged 8 and 104 weeks) were employed for electron microscopy. For the incisor, prior to aging, and regardless of eruptive behavior (i.e., for both impeded and unimpeded incisors), there was little evidence of apoptosis in the periodontal ligament or gingival connective tissues. For the molar, apoptosis was also not usually detected when the teeth were erupting or in the mature, erupted state. In the aged animals, however, there was a marked increase in apoptosis (as assessed by the TUNEL technique) within the periodontal ligament and gingivae of both the molars and incisors (where eruption rates also increased). Nevertheless, electron microscopy indicated that significant numbers of apoptotic cells were only in the incisor periodontium. These findings are not consistent with the view that the periodontal fibroblasts provide a component of the force(s) responsible for eruption.

The effects of aging on the eruptive behavior of the mandibular incisor in male rats.

Several studies have highlighted the lack of age changes in the extracellular matrix of the periodontal ligament, but more needs to be known about cellular and functional changes (including the effects upon eruption). For this study, impeded and unimpeded eruption rates were measured over a 2-week period for the mandibular incisors of a group of 24-month-old rats. The technique used for measuring eruption was similar to that described by Bryer [15]. Both impeded and unimpeded eruption rates were found to be significantly increased (p < .01) compared with those obtained from a group of rats aged 8 weeks. These changes might be related to changes in the mechanism(s) responsible for the generation of the eruptive force(s) or to changes in the resistance of the tissues to such forces.

An in vitro approach for the study of dentinogenesis by organ culture of the dentine-pulp complex from rat incisor teeth.

Culture of the developing dental tissues has contributed to understanding of developmental processes during early odontogenesis. However, to understand fully the mechanisms involved during dentinogenesis and tissue repair there is a need to develop culture models for the dentine-pulp complex from more mature dental tissues. This study describes the development of a system for the organ culture of mature rodent teeth. Slices of incisors from 28-day-old rats were embedded in a semisolid, agar-based medium and cultured on floating Millipore filters at the liquid-gas interface for up to 14 days. Preservation of cell and tissue morphology was observed throughout the entire dentine-pulp complex after each culture period and autoradiographic studies showed that the odontoblasts were actively synthesizing and secreting extracellular matrix during culture. Transmission electron microscopy confirmed that the phenotypic morphology of the odontoblasts had been maintained during culture. These results demonstrate that the dentine-pulp complex from mature rodent tissues can be cultured successfully for substantial periods of time and will provide a useful model for the study of dentinogenesis and tissue repair.

Immunolocalisation of collagens in the developing rat molar tooth.

This study identifies different types of collagens during tooth development, maturation and ageing. Tissues from the rat first molar (from animals ranging in age from E14 to 104 wk postnatally) were immunostained using a panel of mono- and polyclonal antibodies against types I, II, III, IV, VI, IX and X collagen, fibronectin and laminin. During tooth development, types I and III collagens were expressed in the dental papilla at all stages but were also unexpectedly observed in the stellate reticulum of the enamel organ. Transient expression of type II collagen was also observed in the stellate reticulum during the late bell stage. Types IV and VI collagens, with laminin and fibronectin, were located within the basement membranes of the tooth germ. Collagen types I and III were observed within the developing follicle/periodontal ligament, type III predominating where collagen fibres were inserting into the alveolar bone and cementum. The pattern of types I and III collagen labelling within the periodontal ligament and the dental pulp did not change with age. Thus, some unusual collagen localisations were observed in the tooth germ, particularly within the stellate reticulum.

Changes in the cytoskeleton of cells within the periodontal ligament and dental pulp of the rat first molar tooth during ageing.

The periodontal ligament and dental pulp connective tissues are foetal-like, and their process of ageing may therefore differ from other tissues of mesenchymal origin. Several studies have already highlighted the lack of age changes in the extracellular matrix (ECM), but more needs to be known about cellular changes. For this study, tissues from the first molar teeth of Wistar rats aged 12 wk and 104 wk were compared by immunolocalisation of cytoskeletal components. Tissues from the first molar were immunostained, employing a panel of 16 monoclonal antibodies against cytokeratins, vimentin, F-actin and tubulin. Within the pulp, labelling for vimentin in both odontoblasts and pulpal fibroblasts and F-actin in the cell processes of odontoblasts was detected at both ages but with marked reduction in labelling in the older tissue. Within the periodontal ligament, vimentin labelling was weaker in the aged tissue, especially nearer the cementum. More significantly, the fibroblasts of the aged periodontal ligament expressed cytokeratin 19. In contrast to reports of little age change to the ECM, the cells of the pulp, and particularly the periodontal ligament, show marked changes to their cytoskeletal components.

Glycosaminoglycan biosynthesis during 5-fluoro-2-deoxyuridine-induced palatal clefts in the rat.

The biosynthesis and hydration of glycosaminoglycans (GAG) has been implicated in the generation of palatal shelf-elevating force(s) in mammals, although the nature of the palatal shelf extracellular matrices during cleft palate formation remains poorly understood. This study quantifies the GAG composition in the palatal shelves of Wistar rat fetuses at various periods of palatogenesis where clefts were induced experimentally using 5-fluoro-2-deoxyuridine (FUDR). For both normal and cleft palatal shelves, hyaluronan, heparan sulphate and chondroitin-4-sulphate were detected but not dermatan sulphate or chondroitin-6-sulphate. Throughout the period of cleft development studied, the total amount of GAG was significantly decreased (by approx. 30%) compared with normal development, this decrease being particularly marked at a time equivalent to post-elevation during normal development (approx. 75%). Furthermore, and unlike normal palatogenesis, no significant differences were recorded between the anterior and posterior parts of the palatal shelves during cleft formation. As for normal palatogenesis, however, the percentages of each GAG were not altered at any stage. The findings are consistent with the view that suppression of GAG biosynthesis is related to the development of cleft palate in FUDR-treated rat fetuses and can therefore be interpreted as providing evidence of a role for the mesenchymal glycoconjugates in shelf elevation during normal palatogenesis.

Mesenchymal cell activity during 5-fluoro-2-deoxyuridine-induced cleft palate formation in the rat.

Biosynthetic activity of the mesenchymal cells within the palatal shelves was determined during cleft palate formation induced by 5-fluoro-2-deoxyuridine (FUDR). The palatal shelves of 30 fetal rat heads with palatal clefts were surveyed at stages corresponding to normal palatogenesis, nucleolar organizer region (NOR) staining being employed to determine cell activity. Comparing cellular activity during normal and cleft palatogenesis, significantly lower counts were recorded for most stages of cleft formation. When anterior or posterior regions were compared, significant changes in NOR counts cell were found at a time corresponding to the pre-elevation stage of normal palatogenesis. At a time equivalent to normal fusion, the shelves in the anterior region showed signs of recovery, but posteriorly significantly lower activity occurred throughout all stages of palate dysmorphogenesis. The depressed level of cellular activity found after treatment with FUDR may be directly or indirectly related to the abolition of an intrinsic shelf-elevation force and, subsequently, cleft palate formation.

Changing expression of intermediate filaments in fibroblasts and cementoblasts of the developing periodontal ligament of the rat molar tooth.

The distributing of vimentin and cytokeratin intermediate filaments within the cells of the dental follicle and developing periodontal ligament is described during eruption of the rat 1st molar tooth. Alcohol-fixed tissues from animals ranging from neonates to 12 wk old were cryosectioned, immunolabelled with monoclonal antibodies against vimentin and a range of cytokeratins and examined by indirect immunofluorescence. Vimentin was observed in follicular and periodontal ligament fibroblasts in all animals and at all stages of eruption. It was also observed in cementoblasts after disruption of the epithelial root sheath (of Hertwig) which is responsible for determining the shape of the developing root. Prior to eruption, cytokeratins were restricted to epithelial components of the developing tooth, including the root sheath. However, they were seen in cementoblasts on disruption of the root sheath at 2 wk and in periodontal ligament fibroblasts at 3 wk after birth, when the tooth was erupting but had not reached occlusion. On occlusion (at 4 wk), fibroblasts no longer labelled for cytokeratins but cementoblasts associated with acellular cementum formation continued to express them. These results demonstrate temporal and spatial changes within the cells of the developing periodontal connective tissues and suggest that the appearance of cytokeratins in periodontal fibroblasts and cementoblasts may be related to mechanical changes during tooth eruption. Further, the results suggest different origins for cementoblasts associated with cellular and acellular cementum formation.

Cytoskeleton of the mesenchymal cells of the rat dental papilla and dental pulp.

This study describes the immunolocalization of actin, cytokeratins and vimentin during differentiation of the dental papilla in the rat. Incisors and first molars were sectioned from mandibles of Wistar rats from embryonic day (E)-14 to (E)-21 and weeks 1, 2, 3, 12 and 104 after birth, fixed in 90% alcohol, decalcified in EDTA, infiltrated with 5% sucrose, frozen in dry ice, and cryosectioned at 10 microns. The sections were immunolabelled using indirect immunofluorescence with a panel of monoclonal antibodies and FITC-phalloidin for F-actin localization. F-actin was present in follicular mesenchyme and odontoblast processes. Vimentin labelled dental papilla fibroblasts, differentiating, functional (secretory) and aged odontoblasts. Vimentin was uniformly localized in the cytoplasm of pre-odontoblasts but was redistributed to the apical pole of these cells during polarization. Of the cytokeratins, only cytokeratin 19 was found in differentiating odontoblasts. It was not present in dental papilla fibroblasts, functional or aged odontoblasts. These results suggest that actin and the redistribution of vimentin may be involved in odontoblast differentiation and odontoblast process formation/support and that these events may be preceded by the expression of cytokeratin 19.

The effects of aging upon the connective tissues of the periodontal ligament.

The ultrastructural features of the cells and of the oxytalan fibers within the periodontal ligaments of aged rats (2 year old) were quantified and compared with data for tissues obtained from younger animals (8 week old). Sections of the mid-root regions of the mandibular first molars were prepared for examination by TEM. The fibroblasts of the aged rats were found to differ in 3 respects: the areas occupied by endoplasmic reticulum were significantly less, the areas occupied by intracellular collagen profiles were also less, and both the numbers and sizes of intercellular contacts were significantly different (p < 0.05). For the oxytalan fibers, no differences were observed between the periodontal ligaments of the aged and control animals both in terms of numbers of fibers per 50 microns and in terms of area of tissue occupied. Thus, in contrast to the apparent lack of age changes so far determined for the extracellular matrix of the periodontal ligament (collagen fibrils and oxytalan), the periodontal fibroblasts exhibit some age changes as perceived at the ultrastructural level.

Changes in the composition of glycosaminoglycans during normal palatogenesis in the rat.

The synthesis and hydration of glycosaminoglycans (GAG) has been implicated in the generation of a palatal shelf-elevating force in mammals. This study quantifies the GAG composition in the palatal shelves of Wistar rat fetuses at various stages of palatogenesis. Hyaluronan, heparin sulphate and chondroitin-4-sulphate were detected but not dermatan sulphate or chondroitin-6-sulphate. The distribution of the GAG differed in the anterior and posterior regions (i.e. the presumptive hard and soft palates) and with the stage of development. At the time of palatal-shelf reorientation, there were no significant differences for either the total amount of GAG or for the percentages of specific GAG types between anterior and posterior regions. Indeed, the most marked differences were detected at the stages of histogenesis after shelf elevation. Nevertheless, the results support the view that hyaluronan is involved in palatal-shelf reorientation, its percentage being initially high and decreasing after shelf elevation. No changes were detected for the other (sulphated) GAG during the time of elevation. The findings point to the need to correlate the events during histogenesis with changes in the ground substance of palatal-shelf mesenchyme and indicate that there are different developmental mechanisms within the presumptive hard and soft palates.

The effect of rate of eruption on periodontal ligament glycosylaminoglycan content and enamel formation in the rat incisor.

The rate of eruption of rat mandibular incisors was either increased by cutting one tooth out of occlusion or eliminated by means of pinning. The effects of such changes in eruption rate on the sulphated glycosylaminoglycan content of the periodontal ligaments was analysed. The length of the enamel secretory zone and the composition of the developing enamel matrix protein was also compared. Sulphated glycosylaminoglycan content of the periodontal ligament increased fourfold (P < 0.001) during accelerated eruption but decreased to a corresponding extent (P < 0.001) in the absence of eruption, when compared with controls. The length of the enamel secretory zone was also significantly reduced in the immobilised teeth, although the protein content was similar compared with controls. The results demonstrate the differential response to varied eruption rates of the periodontal ligament and enamel, particularly in respect of the extracellular matrix. The data are consistent with the view that the ground substance of the periodontal ligament plays a role in the generation of the eruptive force.

Cellular activity in the developing palate of the rat assessed by the staining of nucleolar organiser regions.

To provide information concerning biosynthetic activities within the mesenchymal cells of rat palatal shelves, the numbers of nucleolar organiser regions (NORs) were detected using an Ag-NOR staining technique within tissues obtained from coronal sections of 30 fetal heads prepared for light microscopy. The study involved comparisons between stages of palatogenesis and between location along the palatal shelves, anterior and posterior regions being analysed to correspond to the presumptive hard and soft palates. For both anterior and posterior regions, the mean Ag-NOR count/cell was initially high (approximately 3.4 anteriorly and approximately 3.0 posteriorly). The count/cell decreased significantly immediately after elevation but increased again after shelf reorientation and complete fusion. When comparisons were made between anterior and posterior regions of the palatal shelves, no differences were discerned at a stage prior to elevation (day 15) and a stage after the shelves had elevated and completely fused (day 17). Immediately post-elevation (day 16.5), however, the mean count/cell was significantly higher anteriorly. Thus the degree of mesenchymal cell activity, as expressed in terms of protein biosynthesis, can change in the developing palate according to both site and stage of development.