Morphological and functional characteristics of satellite glial cells in the peripheral nervous system.

Satellite glial cells are specialised cells that form a functional perineuronal sheath around sensory ganglion neurons. There are a large number of studies that reveal the morphological and functional characteristics of these cells. Satellite glial cells have been studied both in intact ganglions and in tissue cultures, using light and transmission electron microscopy, immunohistochemical and other methods. Satellite glial cells have polygonal form; they are mononuclear and have developed synthetic organelles, numerous receptors, adhesion molecules and ion channels, which enable them to interact with adjacent neurons, as well as transmit signals in the ganglions of the peripheral nervous system. Based on the literature data, satellite glial cells thanks to their characteristics can receive signals from other cells and react to changes in their surroundings. Previous studies have investigated the potential role of satellite glial cells in the formation of the blood-nervous tissue barrier of the peripheral nervous system, as well as in the neuropathic pain genesis. Some recent discoveries support the fact that satellite glial cells can participate in controlling of local viral infections and protecting pseudounipolar neurons from mentioned infections.

Arterial supply of the trigeminal ganglion, a micromorphological study.

BACKGROUND: In this study, we explored the specific microanatomical properties of the trigeminal ganglion (TG) blood supply and its close neurovascular relationships with the surrounding vessels. Possible clinical implications have been discussed. MATERIALS AND METHODS: The internal carotid and maxillary arteries of 25 adult and 4 foetal heads were injected with a 10% mixture of India ink and gelatin, and their TGs subsequently underwent microdissection, observation and morphometry under a stereoscopic microscope. RESULTS: The number of trigeminal arteries varied between 3 and 5 (mean 3.34), originating from 2 or 3 of the following sources: the inferolateral trunk (ILT) (100%), the meningohypophyseal trunk (MHT) (100%), and from the middle meningeal artery (MMA) (92%). In total, the mean diameter of the trigeminal branches was 0.222 mm. The trigeminal branch of the ILT supplied medial and middle parts of the TG, the branch of the MHT supplied the medial part of the TG, and the branch of the MMA supplied the lateral part of the TG. Additional arteries for the TG emerged from the dural vascular plexus and the vascular network of the plexal segment of the trigeminal nerve. Uniform and specific intraganglionicdense capillary network was observed for each sensory trigeminal neuron. CONCLUSIONS: The reported features of the TG vasculature could be implied in a safer setting for surgical approach to the skull base, in relation to the surrounding structures. The morphometric data on TG vasculature provide anatomical basis for better understanding the complex TG blood supply from the internal and external carotid arteries.

The superficial palmar branch of the radial artery: a corrosion cast study.

BACKGROUND: Surgical procedures such as thenar flaps and radial artery (RA) harvesting call for an elaborate anatomical study of the RA's superficial palmar branch (SPB). The aim of this study was to describe the branching pattern of this vessel related to the morphometric characteristics and variations of this artery. MATERIALS AND METHODS: Twenty 4% formalin solution-injected hands were dissected. For the morphometric study we used another group of 35 human hands of adult persons, injected with methyl methacrylate fluid into the ulnar and radial arteries. As soon as polymerisation was completed, a 40% solution of potassium hydroxide was applied for corrosion. The vascular arterial casts were examined under the stereoscopic microscope and precise drawings of each specimen were made. RESULTS: In the majority of cases (75%) SPB passed superficially, over the abductor pollicis brevis muscle. The mean diameter of the SPB, very variable depending on its length and field of supply, was 1.52 ± 0.49 mm, ranging from 0.8 to 2.7 mm. Developed SPB type, was present in 31.4% of hands, with the diameter of 1.7 mm and larger (mean 1.95 mm), continuing distally to become the radialis indicis artery, with an average calibre of 1.2 mm, and with important branches to the thumb. In most hands (68.6%), the hypoplastic SPB, was present, with a mean diameter of 1.17 mm, and the field of supply within the thenar area. CONCLUSIONS: Knowledge of the SPB dominance and existence of anastomotic vessels in its field of supply are of importance to avoid the risk of possible ischaemic sequelae in the hand associated with harvesting the RA.

Vascular anatomy of the thenar eminence: its relevance to a pedicled or free thenar flap.

BACKGROUND: The aim of this study was to clarify the arterial supply of the skin covering the prominent part of the thenar eminence in order to describe the possibility and potential for harvesting a pedicled or a free flap from the thenar eminence. MATERIALS AND METHODS: The arteries were studied in 30 post-mortem specimens of human hands; 3 previously perfused with 4% formaldehyde solution, and injected with black India ink, and 27 injected with methyl-methacrylate and afterwards corroded in 40% potassium hydroxide solution. RESULTS: In all hands we found two little palmar arteries coming from the anatomical snuff-box portion of the radial artery. We labelled the first (proximal) branch as the middle thenar artery, because it supplies the middle third of the thenar eminence skin. Its diameter varied from 0.25 to 0.55 mm (mean 0.4 mm). The distal, more prominent branch of the radial artery, vascularised the lateral third of the thenar eminence skin, and was named the lateral thenar artery; its diameter ranged from 0.40 to 0.90 mm (mean 0.67 mm). The superficial palmar branch of the radial artery, always present, was classified as: hypoplastic, average or prominent, with a diameter ranging from 0.8 to 2.7 mm (mean 1.47 mm). CONCLUSIONS: Three individually developed branches of the radial artery supplied the skin of the thenar eminence. Cutaneous branches of these three arteries were interconnected via anastomotic vessels.

Vascularisation of the geniculate ganglion.

BACKGROUND: Lack of the relevant data in the literature and possible clinical significance of the geniculate ganglion vasculature inspired us to examine the vessels of this ganglion. MATERIALS AND METHODS: Twelve temporal bones were taken during autopsy and microdissected. Four geniculate ganglions were taken as well, serially sectioned and used for haematoxylin-eosin and trichrome staining, and for CD34 immunostaining. RESULTS: The geniculate ganglion was supplied by the petrosal artery, which averaged 1.1 in number, 0.44 mm in the outer diameter, 0.24 mm in the luminal diameter, and 17.1 mm in length. The artery approached the greater petrosal nerve, giving off 1-3 twigs to it with a mean diameter of 24 µm, and entered the nerve hiatus or a small bone opening close to the ganglion. Before the artery continued to the tympanic segment of the facial nerve, it gave rise to 1 (8.33%), 2 (75.00%) or 3 (16.67%) branches to the geniculate ganglion, which ranged in diameter between 18 µm and 56 µm (mean 29 µm). From the formed superficial network, several twigs penetrated the ganglion and built an intraganglionic plexus. The counting, performed in microscopic fields, each measuring 341.7 µm × 250.0 µm in size, contained between 20 and 38 (mean 28.1) ganglion cells, as well as from 87 to 143 microvessels (mean 99.8), so that the neuron/vessel ratio was 1:3.6. CONCLUSIONS: This is the first detailed examination of the geniculate ganglion vasculature. The obtained data could be of clinical importance, especially in relation to the Bell's palsy, ganglionitis, geniculate neuralgia, petrous bone imaging, and operations in the same region.

The influence of varying layer thicknesses on the color predictability of two different composite layering concepts.

OBJECTIVE: Optical properties of teeth are mimicked by composite layering techniques by combining a relatively opaque layer (dentin) with more translucent layers (enamel). However, the replacing material cannot always optically imitate the tooth when applied in the same thickness as that of the natural tissues. The natural layering composite system is available in 2 concepts: (1) dentin (D) and enamel (E) have the same shade but with different translucencies; (2) D and E have different shades where E is always the same high translucent shade. The objective was to evaluate the influence of varying thicknesses of E and D composites on the overall color and on the translucency for both concepts. METHODS: For each concept three composite brands were tested; Concept 1: Clearfil Photo Bright (Kuraray), Herculite XRV Ultra (Kerr), Venus Diamond (Heraeus Kulzer); Concept 2: Amaris (VOCO), CeramX Duo (DENTSPLY) and Point4 (Kerr). Two specimens of each shade (A1-A3) per composite were made of standardized thicknesses with a poly-acrylic mold and Teflon cover, making 36 specimens of wedge-like dimension. The L*a*b* values were measured three times against a white and black background (n=216). Student's t-tests revealed significant levels between the average ΔE* values of the 3 areas for each composite. RESULTS: Statistically significant differences (p<0.05) were found for all thicknesses and for all shades between the concepts. Concept 2 showed greater variations in ΔE* with increased thicknesses. SIGNIFICANCE: Concept 2 composites are more sensitive to layer thickness changes, which implicates less predictability in a daily clinical routine.

Data comparison between two dental spectrophotometers.

OBJECTIVES: The objective of this study was to clinically test whether the data from two different spectrophotometers, based on spot and surface measurements, can be compared. METHODS: Under standardized clinical conditions two devices (Vita Easyshade and Spectro Shade-Micro) were used to record the color of three areas (cervical, middle, and incisal) per tooth for three upper maxillary anterior teeth in 102 participants. Each position was measured three times to attain an average for the CIE L*a*b* coordinates and to attain the corresponding Vita Classical shade tab integrated in the software of both devices. Vita tabs were also described as L*a*b* values using earlier published translations so that color differences (ΔE) could be calculated between them. RESULTS: The regression analysis between the two devices showed that the independent correlation coefficients of the L*a*b* values are low. Yet when the suggested shade codes are compared with Vita colors instead of L*a*b*, 40% of the cases were equal and 51% were clinically acceptable. SIGNIFICANCE: According to this study the two devices do not give a comparable shade selection output, and thus the exchange of L*a*b* values between the two spectrophotometers cannot be recommended.

[Dental students' opinions on education in fabricating single-tooth fixed prostheses and multi-teeth fixed prostheses]. / De mening van tandheelkundestu- denten over het onderwijs in kronen en bruggen.

Education in fabricating single-tooth fixed prostheses and multi-teeth fixed prostheses is an important component of the dental curriculum. To explore the opinion of dental students on this component of the curriculum, a web-based survey was carried out among the students of the 3 dental schools in the Netherlands. The 389 completed questionnaires revealed that the education in fabricating single-tooth fixed prostheses and multi-teeth fixed prostheses started in different years of study at the 3 dental schools. Another striking difference is that the methods of preparation and the choice of materials for single-tooth fixed prostheses and multi-teeth fixed prostheses in the pre-clinical practicum in the programmes was not the same. The students of the 3 dental schools seemed to have a reasonably positive opinion of their preclinical training preparation for treating patients. The opinions of the Nijmegen Dental School students were significantly more positive than the opinions of the students at the 2 other dental schools.

A photographic method to measure the colour characteristics of healthy gingiva.

BACKGROUND: Colour of healthy gingiva is mostly determined by subjective visual observation. The introduction of digital imaging and diagnostic tools to evaluate colour makes it feasible to measure gingival colour more objectively. METHODS: A study was designed to obtain reproducible photographs of anterior maxillary gingiva of a study group of 26 dental hygienist students with a professional attitude for healthy gingiva. Gingival health was evaluated clinically by probing marginal portions of gingiva. No bleeding on probing was considered the gold standard for health. For the colour measurements on the photographs adobe photoshop software was used and colour was expressed in the Cie L*a*b* colour system. Gingival selections were extracted from the photographs and brightness (L*), redness (a*) and yellowness (b*) were calculated. RESULTS: The L* colour characteristic varied from 72 to 78 (average 76), The a* characteristic from 12 to 23 (average 20) and the b* characteristic from 13 to 21 (average 16). CONCLUSION: The findings of this study suggest that the colour characteristics of normal gingiva can vary considerably and still be healthy. Objective digital measurements of gingival colour characteristics may become a valuable, reproducible and practicable evaluation method of gingival health. This photographic study has explored measurement procedures towards this aim.

Marginal fit and short-term clinical performance of porcelain-veneered CICERO, CEREC, and Procera onlays.

STATEMENT OF PROBLEM: Onlay preparations are very complex surfaces for computer surface digitization, CAD, and CAM of all-ceramic onlay cores. PURPOSE: This study tested the hypothesis that onlays can be fabricated with CICERO, CEREC, and Procera core technologies. MATERIAL AND METHODS: Fifteen mandibular and 10 maxillary molars were prepared for onlays in 17 patients (11 women and 6 men). The onlay design was experimental. Molars were prepared with deep gingival chamfers in the proximal boxes and around the functional cusps. The nonfunctional cusps were prepared with broad bevels. Eight stone dies of preparations were measured with a laser beam (CICERO), 10 dies with a light beam (CEREC), and 7 dies with a contact probe (Procera). Two onlay cores were produced for the same stone die. One core was used to analyze fit on the stone die, and the other core was porcelain veneered for optimizing anatomy, esthetics, and fit of the onlay and cemented. The fit of the onlay core on the stone die and the cement width on a stone cast were measured by a microscopic digital imaging system. The onlays were evaluated for function every 6 months for 2 years. RESULTS: Measurements of the margins by the CICERO system were (1) precise (error <4%) and (2) accurate with an SD of less than 9 microm. The proposed onlay preparation design met the requirement that all points of the surface be visible from a single point of view for optical 3-dimensional mapping by the CEREC system. For the surface measurements by the Procera contact probe, the orientation of the sapphire tip toward the preparation surface was critical, and it was necessary to apply wax to smooth internal edges. The marginal gaps of the CICERO, CEREC, and Procera cores on the stone dies were 74 microm (SD 15), 85 microm (SD 40), and 68 microm (SD 53), respectively. The cement width was 81 microm (SD 64). No fractures occurred. CONCLUSION: Marginal gaps for the onlay cores were no more than 85 microm. The cement width of the semicomputer-produced onlays of 81 microm was a favorable measurement value for a clinically acceptable, strong all-ceramic onlay. However, this value as well as anatomy and esthetics of the onlay depended on the craftsmanship of the porcelain veneering by the dental technician.