The patient-dentist relationship and the future of dentistry.

The patient-dentist relationship is a delicate partnership that forms the core of dentistry. The attack on this partnership by the General Dental Council has led to gross miscarriages of justice and the emergence of defensive dentistry. This essay considers the role of a governing body, the misconduct of the GDC and the response of the profession to the injustices perpetrated. The system of NHS general dental practice is considered in terms of quality and humanity and found to be failing in quality and lacking in humanity. The paper concludes that the General Dental Council must go and that NHS general dental practice needs to be terminated. The GDC is apparently not accountable to anyone but the practice of dentistry is accountable to the dentists. The profession will need to be courageous and take action to bring about radical change. A new governing body consisting of young dentists and older more experienced dentists will establish a proper system of professional standards and care for patients. A new, dentist-controlled private system of subsidised general dental practice will be introduced using government financial support for dentistry. The patient-dentist partnership will thus be able to move into a new era of quality and humanity.

Comparison of multiple thawing techniques on thaw time and stability of hemostatic proteins in canine plasma products.

OBJECTIVES: To compare thawing times of fresh frozen canine plasma between a 37 °C warm water bath, running water bath and dry plasma thawer and compare haemostatic protein stability after thawing in a warm water bath or dry plasma thawer. MATERIALS AND METHODS: To measure thawing times, a 240-mL bag of frozen plasma was thawed in warm water bath, running water bath or dry plasma thawer-10 times for each method. To evaluate stability of haemostatic proteins, fresh canine donor plasma samples were split into 120-mL bags and 3-mL control aliquots before freezing. Bags were thawed by warm water bath or dry plasma thawer and aliquots equilibrated to room temperature. Concentrations of haemostatic proteins, albumin, D-dimers, prothrombin time and partial thromboplastin time were obtained. RESULTS: The running water bath had the shortest thaw time: median thaw time of 15 minutes versus 18 minutes for both the dry plasma thawer and warm water bath. Statistically significant differences in partial thromboplastin time, factor VII, factor X, von Willebrand factor, and von Willebrand factor collagen binding assay were detected among groups but were unlikely to be clinically relevant. CLINICAL SIGNIFICANCE: A traditional running water bath provided the fastest thawing time but the dry plasma thawer resulted in the most stable haemostatic proteins.

Biochemical evaluation of storage lesion in canine packed erythrocytes.

OBJECTIVES: To describe the biochemical changes - also known as the storage lesion - that occur in canine packed red blood cells during ex vivo storage. MATERIALS AND METHODS: Ten 125-mL units of non-leuco-reduced packed red blood cells in citrate phosphate dextrose adenine were obtained from a commercial blood bank within 24 hours of donation. Samples were aseptically collected on days 1, 4, 7, 14, 28, 35 and 42 for measurement of sodium, potassium, chloride, lactate, glucose, pH and ammonia concentrations. All units were cultured on day 42. Friedman's repeated measures test with Dunn's multiple comparison test was used for non-parametric data. A repeated-measures analysis of variance with Tukey's multiple comparison test was used for parametric data. Alpha was set to 0·05. RESULTS: All analytes changed significantly during storage. The mean ammonia on day 1 (58·14 g/dL) was significantly lower (P<0·05) than those on days 28 (1266 g/dL), 35 (1668 g/dL) and 42 (1860 g/dL). A significant increase in median lactate concentration over time was also observed, with day 1 (4·385 mmol/L) being significantly less (P<0·05) than days 14 (19·82 mmol/L), 21 (22·81 mmol/L), 35 (20·31 mmol/L) and 42 (20·81 mmol/L). Median pH was significantly decreased after day 7. All bacterial cultures were negative. CLINICAL SIGNIFICANCE: Many biochemical alterations occur in stored canine packed red blood cells, although further studies are required to determine their clinical importance.

Dietary management of presumptive protein-losing enteropathy in Yorkshire terriers.

OBJECTIVES: To describe the clinical outcome of dietary management of Yorkshire terriers with protein-losing enteropathy without immunosuppressive/anti-inflammatory medications. METHODS: Records were searched for Yorkshire terriers with hypoalbuminaemia and a clinical diagnosis of protein-losing enteropathy that were managed with diet and without immunosuppressive/anti-inflammatory medications. Serum albumin changes were compared using a one-way repeated measures ANOVA. Canine chronic enteropathy clinical activity index scores were compared using a Wilcoxon signed-rank test. RESULTS: Eleven cases were identified. Clinical signs were variable including: diarrhoea, respiratory signs, vomiting, lethargy and weight loss. Diets fed included home cooked (n=5); Royal Canin Gastrointestinal Low Fat (n=4); Hill's Prescription Diet i/d Low Fat (n=1); or Purina HA Hypoallergenic (n=1). Clinical signs resolved completely in eight dogs, partially resolved in two dogs and failed to respond in one dog. In dogs that responded, albumin significantly improved from baseline (mean 14·9 g/L, sd ±3·7), at 2 to 4 weeks (mean 24·2 g/L, sd ±5·5, P=0·01), and at 3 to 4 months (mean 27·0 g/dL, sd ±5·9, P=0·01). CLINICAL SIGNIFICANCE: These results indicate that dietary management of protein-losing enteropathy is a potential management strategy in Yorkshire terriers. Randomised clinical trials in Yorkshire terriers with protein-losing enteropathy are necessary to compare success rate, survival and quality of life with dietary management versus combined dietary and immunosuppressive/anti-inflammatory therapy.

Biochemical evaluation of the effects of storage on feline erythrocytes.

OBJECTIVE: To describe the biochemical changes that occur during storage of feline packed red blood cells. METHODS: Feline packed red blood cells were obtained from the manufacturer via overnight delivery immediately following collection. Bag spikes were placed using aseptic technique and samples were drawn on days 1, 4, 7, 14, 21, 28 and 35. Sodium, potassium, chloride, glucose, lactate, pH and ammonia were measured at each time point. Aerobic and anaerobic bacterial cultures were submitted following collection on day 35. RESULTS: There were statistically significant increases in the median concentrations of lactate and ammonia within the first 2 weeks of storage to a concentration of 12·38 mmol/L and 447·96 µmol/L, respectively. Glucose concentrations decreased significantly by day 28 to a mean of 1·86 mmol/L. Median sodium and chloride concentrations increased throughout the course of storage to a concentration of 158·20 and 131·00 mmol/L, respectively. Mean potassium concentrations decreased to a concentration of 2·40 mmol/L. CLINICAL SIGNIFICANCE: These results show that biochemical derangements within feline packed red blood cells are progressive, with some alterations, such as lactate and ammonia, occurring early within the storage periods, while others, including glucose and electrolytes, are slower to develop. Additional prospective research evaluating the clinical effects of these biochemical alterations is required.

On the pulpal nerve supply in primary human teeth: evidence for the innervation of primary dentine.

The presence of nerves in human tooth pulp has been recognized for over a hundred years, and the innervation of dentine for about 40 years. These observations have been made in permanent teeth. Very few studies have reported on the innervation of the primary pulp and dentine. The purpose of this study was to describe the innervation of the primary tooth pulp-dentine complex. Ten mature primary teeth (one incisor, six canines and three molars) were used. Immediately following extraction they were divided into three sections using a diamond disc and saline coolant. They were then immersion fixed in a solution of formaldehyde and picric acid dissolved in a phosphate buffer pH 7.4). The teeth were then demineralized for 1-3 weeks in formic acid. Following complete demineralization, 30 microns sections were cut on a freezing microtome. Neural tissue was stained using a specific antibody to calcitonin gene related peptide (CGRP). Sections were mounted on glass slides and examined using light microscopy. No individual nerve fibres were seen in the control sections, suggesting that the method used was specific for CGRP-containing nerve fibres. The primary teeth appeared to be well innervated. Myelinated and unmyelinated nerves were seen. There was a dense but variable subodontoblastic plexus of nerves (plexus of Raschkow) and nerve fibres were seen to leave this to travel towards the odontoblast layer. Most terminated here, but a few penetrated the odontoblast layer to enter predentine and the dentine tubules. The maximum penetration was 125 microns but most terminated within 30 microns of the dentinopulpal junction. The coronal region was more densely innervated than the root. Within the crown the cervical third was the most densely innervated region, followed by the pulp horn and the middle third. In conclusion, this study has demonstrated that mature primary tooth contains a pulp which is well innervated and has many nerve endings terminating in or near the odontoblast layer, with a small number penetrating into dentine.

Effect of mechanical removal of the pulp upon the retention of odontoblasts around the pulp chamber of human third molars.

The pulp chambers of 11 freshly extracted human third molars were exposed by cutting off the roots apical to the cervical margin and the pulps were either removed with forceps and discarded or left in situ. The teeth were fixed, demineralized, divided longitudinally, embedded in resin and 2-micron sections stained with toluidine blue were examined by light microscopy. In pulp-removed specimens the percentage retention of the odontoblast layer with the predentine varied near the longitudinal division but when sectioned deeper all six specimens displayed 100% retention. The intactness of the retained odontoblast layer was mostly good as judged by the mutual close apposition of the distal ends of the cell bodies and their relation to the predentine. The retention of the odontoblast layer with the predentine may be due to the distribution of fibronectin, which others have shown is present between odontoblasts, and between odontoblasts and predentine, but lacking beneath the odontoblast layer.

An immunohistochemical study of the pulpal nerve supply in primary human teeth: evidence for the innervation of deciduous dentine.

The innervation of pulp and dentine was studied in fully formed human deciduous teeth using antibodies to calcitonin gene related peptide (CGRP). Freshly extracted healthy teeth were divided, fixed, demineralised, cryosectioned and treated with antibodies to human CGRP which was then labelled with horseradish peroxidase. Bundles of nerve fibres passed from the apex of the root to the coronal region where a subodontoblast plexus was formed. In the cervical half of the root some nerve fibres branched away from the main bundles to supply both the odontoblast layer and the dentine. Branches from the coronal subodontoblast plexus also reached the odontoblast layer and the dentine. Most of the nerve fibres terminated in the odontoblast layer. In some areas a marginal plexus of nerves was observed between the odontoblasts and the predentine; intratubular nerve fibres arose either from this plexus or directly from the pulp. The dentine of the crown was more densely innervated than that of the root. In the crown the cervical one third had the most densely innervated dentine followed by the pulp horn and the middle third. The most densely innervated areas occurred in regions where the marginal plexus was present. Although many tubules contained a single nerve filament more complex patterns of termination were also observed. The maximum penetration of a nerve fibre into the dentine was 125 microns. The pattern of the deciduous innervation shows some similarities to the permanent dentition but among the differences is the high density of dentinal innervation in the cervical region. The latter point correlates with the clinical impression of greater sensitivity experienced by patients during invasive procedures performed without anaesthetic in the cervical area.

Is rabbit dentine innervated? A fine-structural study of the pulpal innervation in the cheek teeth of the rabbit.

The pulpal innervation of rabbit premolars and molars has been studied in transverse sections of perfusion-fixed, demineralised specimens using light microscopy and transmission electron microscopy. A mixed population of small myelinated and unmyelinated axons enters the apical foramen to supply the mesial and distal laminae of these continuously growing teeth. The nerve fibres are remote from the preodontoblasts and odontoblasts near the apical end, but in their passage to the occlusal end the pulp becomes progressively narrower and nerve fibres come to lie subjacent to the odontoblasts and postodontoblasts. Counts of myelinated fibres near the apical end and in the occlusal pulp suggested that the myelin is shed near the occlusal end. Most of the dentine in these teeth is tubular and migrates occlusally with supporting odontoblasts. Near the occlusal end, postodontoblasts deposit an atubular tissue which closes the pulpal ends of the tubules. Nearer the occlusal tip the pulpal contents degenerate and become embedded in the forming atubular tissue. Evidence of axon profiles was found near the occlusal end in the pulp, passing through the odontoblast layer and in the dentine tubules adjacent to odontoblast processes. However, many of the tubules contained an odontoblast process only and the atubular tissue was not innervated. Since innervated tubules eventually become closed by atubular tissue it is assumed that the nerve fibres retract from the tubules before their closure. In common with other teeth the function of the pulpal nerve supply is likely to be mostly nociceptive.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of platelet activating factor (PAF) on the migration of human lymphocytes.

BACKGROUND: There is growing evidence to suggest the importance of the lymphocyte in the pathogenesis of asthma, particularly in the late phase reactions and ongoing bronchial hyperreactivity. Platelet activating factor (PAF) has also been identified as a potentially important mediator in asthma. METHODS: The migration of human peripheral blood lymphocytes obtained from normal volunteers in response to PAF and the effect of PAF antagonists was studied in a well standardised in vitro assay using nitrocellulose micropore filters in a microchemotaxis chamber. RESULTS: PAF is a potent stimulus to in vitro human lymphocyte migration; at an optimal concentration of 1 nM it augmented lymphocyte chemokinesis to 310% (SE 33%) of control values. The response to PAF appears to be specific since lyso-PAF and other related membrane phospholipids had no effect. PAF-induced migration could be abrogated by specific PAF receptor antagonists such as WEB 2086 (100 nM), and was partially blocked by the cyclooxygenase inhibitor flurbiprofen at a concentration of 1 microM. CONCLUSIONS: PAF stimulates the in vitro migration of human lymphocytes through a specific PAF receptor. Part of the response may be due to the generation of cyclooxygenase products. PAF may play a part in the recruitment of lymphocytes to asthmatic airways.

Hematozoa from passeriform birds in Louisiana.

Blood smears were examined from 935 individuals of 19 migrant and resident bird species collected in Louisiana. Of these, 320 (34.2%) harbored hematozoa. The prevalences of parasites were as follows: Haemoproteus spp. 22.8%, Trypanosoma spp. 6.9%, unidentified microfilariae 5.0%, Plasmodium spp. 3.4%, and Leucocytozoon spp. 1.3%. These data are consistent with other reports from the region. Infections were observed in 33% of the individuals in the 13 migrant species sampled and 33% of the individuals in the 6 resident species.

A permeability barrier to lanthanum and the presence of collagen between odontoblasts in pig molars.

Previous experiments in rat incisors indicate that the odontoblasts form an impermeable barrier which prevents fluid movement between pulp and dentine. The permeability of the odontoblast layer has now been investigated in pig molars which are more analogous to human teeth. The heads and necks of anesthetised piglets were perfused intra-arterially with lanthanum nitrate in Ringer's solution or with Ringer's solution alone. Molar tooth germs were removed, sliced, fixed by immersion and embedded in resin. Ultrathin sections including pulp and dentine were examined by transmission electron microscopy. Fenestrated capillaries were permeable to the electron dense lanthanum which thus entered the extracellular space between the odontoblast cell bodies. The lanthanum was excluded from predentine indicating that a barrier to permeability is present. In the above specimens and in others from 2 animals which were fixed by perfusion fixation, longitudinally oriented bundles of collagen fibrils were found passing from dentine through predentine into the odontoblast layer. Longitudinal collagen was also present between odontoblast cell bodies and entering the pulp at their basal ends. This suggests that classical von Korff fibres are present during primary circumpulpal dentinogenesis. In some sections longitudinally oriented collagen was absent. The junctions showed features of classical tight junctions but open tight junctions containing longitudinal collagen were also observed, suggesting that the junctions may modulate. Despite a trace of evidence that lanthanum can leak through adjacent to longitudinally penetrating collagen we concluded that the biological permeability barrier is maintained. The presence of the barrier indicates that other than the longitudinal collagen fibrils of which the source is unknown, all molecules incorporated into dentine are deposited there by the odontoblasts. An advantage of the barrier may be that it provides a closed environment for the orderly process of matrix deposition and mineralisation of dentine.

Extracellular fluid movement in the pulp; the pulp/dentin permeability barrier.

Fluid movement in the pulp depends largely upon the physiology of the blood vessels; normally there is a net efflux of fluid and proteins from the capillaries into the extracellular environment. Most pulp capillaries lie close to the odontoblast layer and in order to see whether fluid can pass between the odontoblasts into the predentin we have perfused the vessels of molar tooth germs in anesthetized piglets with the electron dense tracer lanthanum. The results show that the tracer permeates the capillaries but encounters a barrier to permeability at the apical (predentinal) ends of the odontoblasts. The completeness of the barrier to the tracer lanthanum is discussed together with structural evidence of tight junctions between odontoblasts in both pigs and humans and the presence of collagen fibers through the tight junctional zone. It is concluded that there is little or no evidence that pulp fluid is normally confluent with predentin. An advantage of this arrangement may be that by maintaining an enclosed microenvironment it permits regulation of the orderly process of matrix deposition and mineralization of predentin to dentin. In order to maintain constant vascular and extracellular fluid pressures the capillary efflux has to be balanced by fluid removal; recent work in cats has shown that lymphatic vessels are available to transport fluid out of the pulp. In this paper the differences in the intrapulpal distribution of these vessels have been extrapolated to human teeth in an attempt to explain certain variations in the symptoms and progress of pulpal inflammatory conditions.

Interodontoblastic collagen (von Korff fibers) and circumpulpal dentin formation: an ultrathin serial section study in the cat.

The collagenous fibers of von Korff pass from the dentin matrix between the odontoblasts into the dental pulp. Although collagen fibrils are known to be present between odontoblasts, the existence of von Korff fibers has remained controversial. This may be because their continuity between the dentin matrix and the pulp has not been demonstrated ultrastructurally. In this study we have examined the odontoblast layer in the middle to apical regions of perfusion-fixed permanent canine teeth of cats by using transmission electron microscopy. Ultrathin sections of demineralized specimens revealed frequent bundles of collagen fibrils 1) entering the odontoblast layer from the predentin, 2) present between odontoblast cell bodies, and 3) passing from between the odontoblasts into the pulp. The question of continuity of these bundles from the predentin, across the odontoblast layer into the pulp was examined in ultrathin serial sections. Unbroken continuity of a collagen bundle from the predentin between the odontoblasts into the pulp was established in a reconstruction of one series of 22 serial sections and was very strongly suggested by a number of other series in which the numbers of available sections restricted their full visibility. This investigation has shown, therefore, that classical von Korff fibers are present and that these fibers are present in fully erupted teeth with closed apices, i.e., at a time when secondary circumpulpal dentinogenesis is in progress. The findings call for a reexamination of the question of von Korff fibers during mantle dentinogenesis and primary circumpulpal dentinogenesis. Resolution of their existence at the earlier stages of dentinogenesis should be possible by using the ultrathin serial-sectioning technique.

An investigation of lymphatic vessels in the feline dental pulp.

The existence of lymphatic vessels in the dental pulp has been a matter of continuing controversy. We have now used light microscopy to examine semithin transverse sections of perfusion-fixed incisors and canines in cats. Lymphatics were found in all the teeth studied. In most teeth they were present in the coronal, middle, and apical regions of the pulp; but in a few they were lacking coronally and in the middle. Within individual teeth, lymphatics were found in the subodontoblastic zone or more centrally in the pulp; but none were found in the odontoblast layer or in the pulp horns. Vessels located by light microscopy were subsequently examined by transmission electron microscopy. Their ultrastructural features were typical of lymphatics and included irregular, attenuated endothelium with adjacent cells joined in different ways. Occasional gaps connected the extracellular spaces with their lumens, and abluminal endothelial projections appeared to form open end bulbs. There was very little basement membrane, but anchoring filaments were found near the abluminal surface of the endothelium and near collagen fibrils. The total cross-sectional area of lymphatic vessels was measured in semithin sections and, with pulp area, increased from the coronal region to the middle. However, both areas decreased from the middle to the apical region suggesting either that lymph flows faster as it reaches the foramens of the apical delta or that some vessels leave the tooth through lateral root canals. Using the methods of light and transmission electron microscopy, therefore, we have shown that pulp lymphatic vessels exist. Questions remain, however, about their distribution within teeth, variations between teeth, and routes of exit from teeth.

Influence of blood parasites on the body mass of passeriform birds.

Body masses of 3,739 birds representing immature and adult males and females of 15 species of passeriforms (both uninfected and infected with Haemoproteus spp. and Leucocytozoon spp.) were compared. There was some interaction among year, month and area of capture for several host species, but there was no discernible effect of either parasite genus on body mass. There were no effects due to high intensity parasitemia for eight host species examined. Either parasitism does not cause loss of body mass, or the techniques used were too insensitive to separate effects of parasitism from other natural causes.