Supporting career choices in dentistry.

The Cork University Dental School & Hospital, University College Cork, introduced an innovative programme in April 2011, which provided prospective dental students with an opportunity to participate in a one-day experiential workshop. The aim of the workshop was to provide students with an overview of the dental undergraduate programmes. Feedback on the workshop was exceptionally positive, and prospective students would recommend the workshop to a fellow student, as it helped to inform their decision about choosing dentistry as a first option.

Effect of pre-heating on the viscosity and microhardness of a resin composite.

The effect of pre-heating resin composite on pre-cured viscosity and post-cured surface hardness was evaluated. Groups of uncured specimens were heated to 60 degrees C and compared with control groups (24 degrees C) with respect to viscosity and surface hardness. Mean (SD) viscosities of the pre-heated specimens (n = 15) were in the range of 285 (13)-377 (11) (Pa) compared with 642 (35)-800 (23) (Pa) at ambient temperature. There was a statistically significant difference between the two groups (P < 0.001). Mean (SD) Vickers microhardness (VHN) of the pre-heated group (n = 15) was 68.6 (2.3) for the top surface and 68.7 (1.8) for the bottom surface measured at 24 h post curing (specimen thickness = 1.5 mm). The corresponding values for the room temperature group were 60.6 (1.4) and 59.0 (3.5). There was a statistically significant difference between corresponding measurements taken at the top and bottom for the pre-heated and room temperature groups (P < 0.001). There was no significant difference between top and bottom measurements within each group. Pre-heating resin composite reduces its pre-cured viscosity and enhances its subsequent surface hardness. These effects may translate as easier placement together with an increased degree of polymerization and depth-of-cure.

Local field potentials reveal a distinctive neural signature of cluster headache in the hypothalamus.

Cluster headache (CH) is a debilitating neurovascular condition characterized by severe unilateral periorbital head pain. Deep brain stimulation of the posterior hypothalamus has shown potential in alleviating CH in its most severe, chronic form. During surgical implantation of stimulating macroelectrodes for cluster head pain, one of our patients suffered a CH attack. During the attack local field potentials displayed a significant increase in power of approximately 20 Hz. To the authors' knowledge, this is the first recorded account of neuronal activity observed during a cluster attack. Our results both support and extend the current literature, which has long implicated hypothalamic activation as key to CH generation, predominantly through indirect haemodynamic neuroimaging techniques. Our findings reveal a potential locus in CH neurogenesis and a potential rationale for efficacious stimulator titration.

Abnormal thalamocortical dynamics may be altered by deep brain stimulation: using magnetoencephalography to study phantom limb pain.

Deep brain stimulation (DBS) is used to alleviate chronic pain. Using magnetoencephalography (MEG) to study the mechanisms of DBS for pain is difficult because of the artefact caused by the stimulator. We were able to record activity over the occipital lobe of a patient using DBS for phantom limb pain during presentation of a visual stimulus. This demonstrates that MEG can be used to study patients undergoing DBS provided control stimuli are used to check the reliability of the data. We then asked the patient to rate his pain during and off DBS. Correlations were found between these ratings and power in theta (6-9) and beta bands (12-30). Further, there was a tendency for frequencies under 25 Hz to correlate with each other after a period off stimulation compared with immediately after DBS. The results are interpreted as reflecting abnormal thalamocortical dynamics, previously implicated in painful syndromes.

Fluoride-containing restorative materials.

Dental practitioners are exposed to an increasing number of dental materials, which claim the benefits of fluoride release. The purpose of this paper is to critically review the literature of these materials. Glass ionomers, resin modified glass ionomers, compomers, resin composites, fissure sealants and amalgam are discussed. It is clear that a long-term measurable release of fluoride can be observed from certain restorative materials, in vitro, particularly glass ionomer cement, resin modified glass ionomer cement, fluoridated cements, fluoridated dental amalgam and certain fissure sealants. In general, the rate of fluoride release is not constant but exhibits a relatively rapid initial rate, which decreases with time. However, the fluoride release profiles may be dependent on specific formulation and on experimental design and sampling methods. These materials may feature greater longevity, a reduced incidence of marginal failure, an elevated concentration of fluoride in contingent plaque, together with an antibacterial action when compared with non-fluoride releasing materials. In addition, fluoride-releasing materials may perform better in caries inhibition in artificial caries model studies than non-fluoridated materials. While any, or all, of these anti-cariogenic effects may be associated with fluoride release, a direct relationship between fluoride release profiles and such effects has not been determined in vivo.

Yellow filters can improve magnocellular function: motion sensitivity, convergence, accommodation, and reading.

The magnocellular system plays an important role in visual motion processing, controlling vergence eye movements, and in reading. Yellow filters may boost magnocellular activity by eliminating inhibitory blue input to this pathway. It was found that wearing yellow filters increased motion sensitivity, convergence, and accommodation in many children with reading difficulties, both immediately and after three months using the filters. Motion sensitivity was not increased using control neutral density filters. Moreover, reading-impaired children showed significant gains in reading ability after three months wearing the filters compared with those who had used a placebo. It was concluded that yellow filters can improve magnocellular function permanently. Hence, they should be considered as an alternative to corrective lenses, prisms, or exercises for treating poor convergence and accommodation, and also as an aid for children with reading problems.

Morphine, but not sodium cromoglycate, modulates the release of substance P from capsaicin-sensitive neurones in the rat trachea in vitro.

1. Opioids have been shown to inhibit substance P (SP) release from primary afferent neurones (PAN). In addition, opioid receptors have been identified on PAN of the vagus nerves. Sodium cromoglycate (SCG) decreases the excitability of C-fibres in the lung of the dog in vivo. We have utilised a multi-superfusion system to investigate the effect of opioids and SCG on the release of SP from the rat trachea in vitro. 2. Pretreatment of newborn rats with capsaicin (50 mg kg-1 s.c. at day 1 and 2 of life) resulted in a 93.2 +/- 6.3% reduction in tracheal substance P-like immunoreactivity (SP-LI) content when determined by radioimmunoassay in the adult. 3. Exposure to isotonically elevated potassium concentrations (37-90 mM), capsaicin (100 nM-10 microM), and bradykinin (BK; 10nm-1 microM) but not des-Arg9-BK (1 microM) stimulated SP-LI release by a calcium-dependent mechanism. 4. SCG (1 microM and 100 microM) did not affect spontaneous, potassium (60 mM)- or BK (1 microM)-stimulated SP-LI release. 5. Morphine (0.1-100 microM) caused dose-related inhibition of potassium (60 mM)-stimulated SP-LI release with the greatest inhibition of 60.4 +/- 13.7% at 100 microM. The effect of morphine was not mimicked by the kappa-opioid receptor agonist, U50,488H (10 microM) or the delta-opioid receptor agonist, Tyr-(D-Pen)-Gly-Phe-(D-Pen) (DPDPE). 6. The effect of morphine was totally abolished by prior and concomitant exposure to naloxone (100 nM) which had no effect on control release values. 7. We conclude that opioid receptors, predominantly of the MM-opioid receptor subtype, inhibit SP-LI release from PAN in the rat trachea and suggest that centrally inactive MM-opioid receptor agonists may have therapeutic potential in the treatment of asthma.

GABAB receptor modulation of the release of substance P from capsaicin-sensitive neurones in the rat trachea in vitro.

1. The role of gamma-aminobutyric acid (GABA) as an inhibitory transmitter in the central nervous system is well documented. Recently, GABAA and GABAB receptors have been identified in the peripheral nervous system, notably on primary afferent neurones (PAN). We have utilised a multi-superfusion system to investigate the effect of selective GABA receptor agonists and antagonists on the release of substance P (SP) from the rat trachea in vitro. 2. GABA (1-100 microM) did not affect spontaneous release of SP-like immunoreactivity (LI) but caused dose-related inhibition of calcium-dependent potassium (60 mM)-stimulated SP-LI release. The greatest inhibition of 77.7 +/- 18.8% was observed at 100 microM. 3. The inhibitory effect of GABA was mimicked by the GABAB receptor agonist, (+/-)-baclofen (1-100 microM), but not the GABAA receptor agonist, 3-amino-1-propane-sulphonic acid (3-APS, 1-100 microM). Baclofen (100 microM) had no effect on SP-LI release stimulated by capsaicin (1 microM). 4. The inhibitory effect of baclofen (30 microM) was significantly reduced by prior and concomitant exposure to the GABAB receptor antagonist, phacolofen (100 microM) but not the GABAA receptor antagonist, bicuculline (10 microM). Neither antagonist, alone, affected spontaneous or potassium-stimulated SP-LI release. 5. We conclude that activation of pre-synaptic GABAB receptors on the peripheral termini of PANs in the rat trachea inhibits SP-LI release and suggest that GABAB receptor agonists may be of value in the therapeutic treatment of asthma.

Updates in dental materials--Part 2: Resin cements.

Recent years have seen a number of innovations and developments with respect to dental materials and their applications in clinical dentistry. This series of short articles considers the more important aspects of these developments under the general term 'Updates in Dental Materials'. Dental composite systems and bonding to tooth material were discussed in Part I. Resin cements are treated in this article. Part 3 presents dental amalgams and Part 4 deals with advances in ceramic materials.

Updates in dental materials--Part 4. Ceramic materials.

Recent years have seen a number of innovations and developments with respect to dental materials and their applications in clinical dentistry. This series of short articles considers the more important aspects of these developments under the general term 'Updates in Dental Materials'. Dental composite systems and bonding to tooth material were discussed in Part I. Resin cements were treated in Part 2 and dental amalgams in Part 3. Part 4 deals with advances in ceramic materials.

Updates in dental materials--Part 1: Dental composites.

Recent years have seen a number of innovations and developments with respect to dental materials and their applications in clinical dentistry. This series of short articles considers the more important aspects of these developments under the general term 'Updates in Dental Materials'. Dental composite systems and bonding to tooth material are discussed in Part 1. Resin cements are treated in Part 2. Part 3 presents dental amalgams and Part 4 advances in ceramic materials.

Updates in dental materials--Part 3: Dental amalgams.

Recent years have seen a number of innovations and developments with respect to dental materials and their applications in clinical dentistry. This series of short articles considers the more important aspects of these developments under the general term 'Updates in Dental Materials'. Dental composite systems and bonding to tooth material are discussed in Part 1. Resin cements are treated in Part 2. Part 3 presents dental amalgams and Part 4 advances in ceramic materials.

A survey of dental composites used in Ireland.

This paper presents the findings of a survey, conducted in February 1989, to investigate the relative popularity of dental composite brands among practitioners on the Irish Dental Register. Data on the reported incidence of staining are also presented as is the relative popularity of surface finishing techniques.