How is research publishing going to progress in the next 20 years? Transcription of session for editors, associate editors, publishers and others with an interest in scientific publishing held at IADR meeting in Seattle on Wednesday, 20 March 2013.

On March 20th 2013, a one-hour session for Editors, Associate Editors, Publishers and others with an interest in scientific publishing was held at the IADR International Session in Seattle. Organised by Kenneth Eaton and Chris Lynch (Chair and Secretary, respectively, of the British Dental Editors Forum), the meeting sought to bring together leading international experts in dental publishing, as well as authors, reviewers and students engaged in research. The meeting was an overwhelming success, with more than 100 attendees. A panel involving four leading dental editors led a discussion on anticipated developments in publishing dental research with much involvement and contribution from audience members. This was the third such meeting held at the IADR for Editors, Associate Editors, Publishers and others with an interest in scientific publishing. A follow up session will take place in Cape Town on 25 June 2014 as part of the annual IADR meeting. The transcript of the meeting is reproduced in this article. Where possible speakers are identified by name. At the first time of mention their role/ position is also stated, thereafter only their name appears. We are grateful to Stephen Hancocks Ltd for their generous sponsorship of this event. For those who were not able to attend the authors hope this article gives a flavour of the discussions and will encourage colleagues to attend future events. Involvement is open to Editors, Associate Editors, Publishers and others with an interest in scientific publishing. It is a very open group and all those with an interest will be welcome to join in.

Grand rounds for dental students: an exploration.

Grand Rounds are widely used in medicine for educating students comprehensively about clinical issues. The aim of this study was to explore the value of Grand Rounds for introducing first- (D1) and second-year (D2) dental students to an interdisciplinary approach to dental care. The objectives were to explore how interested students were in various topics, which topics they would like to see addressed in future sessions, which aspects they liked/disliked, how they evaluated the program components, and how they evaluated the outcomes. Data were collected from D1s at the end of the Year 1 fall term and from D1s and D2s at the beginning and end of the Year 1 winter term and at the end of Year 2. Response rates for most of the groups ranged from 88% to 100%, but response rates for surveys at the end of the study period fell to 40% and 32%. The results showed that the students were most interested in clinical topics that were presented in an interdisciplinary way. Their suggested topics ranged from specialty-specific issues to treatment-related topics such as implants and cosmetic dentistry. The open-ended responses showed that students liked learning differing perspectives on these topics, but disliked the course-related assignments and the preparation work in small groups. The closed-ended responses showed that the students appreciated the in-class presentations by experts and evaluated the course as helpful in informing them about the complexity of issues and the importance of the interplay between basic and clinical sciences. Educating future dentists in a way in which they embrace interdisciplinary approaches is challenging. Using the Grand Rounds concept could be one approach to increasing students' awareness of the importance of interdisciplinary work.

Different Brain Responses to Pain and Its Expectation in the Dental Chair.

A dental appointment commonly prompts fear of a painful experience, yet we have never fully understood how our brains react to the expectation of imminent tooth pain once in a dental chair. In our study, 21 patients with hypersensitive teeth were tested using nonpainful and painful stimuli in a clinical setting. Subjects were tested in a dental chair using functional near-infrared spectroscopy to measure cortical activity during a stepwise cold stimulation of a hypersensitive tooth, as well as nonpainful control stimulation on the same tooth. Patients' sensory-discriminative and emotional-cognitive cortical regions were studied through the transition of a neutral to a painful stimulation. In the putative somatosensory cortex contralateral to the stimulus, 2 well-defined hemodynamic peaks were detected in the homuncular orofacial region: the first peak during the nonpainful phase and a second peak after the pain threshold was reached. Moreover, in the upper-left and lower-right prefrontal cortices, there was a significant active hemodynamic response in only the first phase, before the pain. Subsequently, the same prefrontal cortical areas deactivated after a painful experience had been reached. Our study indicates for the first time that pain perception and expectation elicit different hemodynamic cortical responses in a dental clinical setting.

A quantitative analysis of the innervation of the pulp of the cat's canine tooth.

Although the cat's canine tooth has become the accepted model for the electrophysiological study of dental sensory mechanisms no examination of its innervation has been carried out at the electron-microscopical level. This study looked at the number and size distribution of both myelinated and non-myelinated fibers in the crown of the cat's canine. The material examined was prepared by routine methods and the measurements taken from electron-microscopical montages of pulpal cross-sections. The measurements were made using a Quantimet 720 image analysis system. In one complete cross-section 3,470 fibers were counted. Eighty-one percent of these were non-myelinated with a modal diameter of 0.35 micron. The modal diameter of the myelinated fibers was 2.5 micron. The relative preponderance of non-myelinated fibers increased from core to periphery. The largest myelinated fibers were concentrated in the core. The fiber size distribution was similar in the single complete and two partial sections examined. It is concluded that all the fibers in the crown of the cat's canine would be contained in the A-delta and C groups and that the strikingly large number of fibers present suggests that the peripheral pulp has a dense innervation, many of the cell processes found there being unsheathed axons.

Reinnervation of the canine tooth pulp after section of the inferior alveolar nerve in the cat.

The apices of lower canine teeth have been examined 9 weeks after unilateral section of the inferior alveolar nerve. The teeth were extensively reinnervated although there was considerable variation in the number of axons present. The myelinated axons were smaller than normal with thinner myelin sheaths. There were fewer axons per non-myelinated fibre (Remak bundle). The proportions of myelinated and non-myelinated fibres were normal.

Neural changes in periapical lesions after systemic steroids in the ferret.

This study was intended to clarify the relationship between the neural changes which occur around the apex of the ferret canine after pulpectomy and the inflammatory process induced by the procedure. In 12 young adult ferrets, under general anesthesia, the pulps in the mandibular canine teeth were removed and replaced with gutta percha and Grossman's sealer. Six of the animals were treated with dexamethasone to reduce the inflammatory response. Three months later, the animals, again under general anesthesia, were perfused with a fixative mixture. Three unoperated animals that had not been treated with dexamethasone were also perfused. The mandibular canine teeth and their supporting tissues were removed, processed, and serially sectioned. Three-dimensional reconstructions of the periapical lesions in each animal were assembled and their volumes measured. The density of innervation in the periapical region was estimated. The mean lesion volume in the pulpectomized animals not treated with dexamethasone was 3.54 (+/- 2.27) mm3 and in the dexamethasone-treated animals 1.33 (+/- 1.31) mm3. The differences were statistically significant when tested by the Mann-Whitney U test (p < 0.01). Bacteria were not seen within any of the lesions. The innervation density beneath the canines in the pulpectomized animals not treated with dexamethasone was 164 units per mm2 (+/- 80) and in the steroid-treated animals 151 +/- 68 units per mm2. In the control, untreated animals, the innervation density was 22 +/- 10 units per mm2. The difference between the steroid-treated pulpectomized animals and the untreated pulpectomized animals was not statistically significant (p > 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Periapical innervation of the ferret canine one year after pulpectomy.

Previous studies have shown that, following removal of the dental pulp and its replacement with a filling material, the nerves in the periapical region proliferate within an area of chronic inflammation. This study examined these responses in the ferret in more detail, both quantitatively and in three dimensions, 12 months after pulpectomy which was followed by obturation with gutta percha and zinc oxide and eugenol sealer. The results were compared with the responses after three months. The basic patterns, in terms of both inflammation and neural proliferation, were similar at the two time periods. Both the sizes of the inflammatory lesions and the degree of neural proliferation were lower at 12 months than at three, although the differences were not significantly different in the small number of specimens examined. Bacterial stains failed to show bacteria either in the apical root canal delta or in the periapical area. It is possible that the persistent inflammation was due to the irritant nature of the obturating materials used but not due to the original tissue damage, since extraction sites, by comparison, healed very quickly. Apparently, following endodontic treatment, chronic periapical inflammation and concomitant neural proliferation can continue for long periods.

Axon populations in cat lingual and chorda tympani nerves.

The lingual and chorda tympani nerves from five cats were examined so that normal axonal populations could be determined. After perfusion fixation, the chorda tympani and lingual nerves were removed and processed, and sections were taken from individual and combined nerves for both light and electron microscopy. The chorda tympani remained as a distinct group of smaller axons for at least 4 mm distal to its junction with the lingual nerve. The mean number +/- S.D. of myelinated axons in the chorda tympani central to the junction was 1322 (+/- 268) and in the lingual nerve central to the junction, 3227 (+/- 510). The counts were not significantly different distal to the junction, and there were no side-to-side differences. Mean myelinated axon circumferences were significantly smaller in the chorda tympani (12.86 +/- 0.87) than in the lingual nerve (22.79 +/- 1.99; p less than 0.01). The mean size of axons in the chorda tympani was slightly but consistently larger on the left (13.1 +/- 0.73) than on the right side (12.61 +/- 1.01; p less than 0.05). Distal to the junction, the average proportion of non-myelinated axons was 44% in both chorda tympani and lingual nerves.

The reinnervation of healing extraction sockets in the ferret.

The objective of this study was to describe the pattern of healing of pulpal and periodontal nerve fibers following tooth extraction. The mandibular canine teeth were, under general anesthesia, removed from one side of nine young ferrets. One week (two animals), one month (four animals), and three months (three animals) later, again under general anesthesia, the animals were perfused with fixative. The mandibles were decalcified, paraffin-embedded, and serially sectioned. Sample sections were stained with hematoxylin and eosin, the remainder with a silver stain for nerves. Serial reconstructions were made of the innervation in control teeth and in the extraction sockets. A grid sampling technique was used for the estimation of the innervation density in different regions at various levels in the healing socket. One week after extraction, although osteoid material was beginning to fill the socket, the pattern of innervation remained similar to that of controls in being restricted to the former location of the periodontal ligament and being densest in the apical third of the socket. One month after extraction, the innervation consisted of many fine axons or small bundles distributed throughout the healing osteoid tissue though still most dense in the periphery of the socket. The overall innervation density increased between one week and one month post-extraction. At three months, as the margins of the socket were becoming obscured, the innervation consisted largely of one or two organized nerve trunks running from the apical to the coronal aspect in either the central or lateral aspects of the socket. At no time was there evidence of neuroma formation.

A quantitative morphological comparison of cat lingual nerve repair using epineurial sutures or entubulation.

Since lingual nerves may be transected during a variety of oral surgical procedures, including third molar removal, we have investigated two possible methods of repair. Quantitative morphological observations were made on feline chorda tympani and lingual nerves proximal and distal to transection injuries repaired either by epineurial suturing or by insertion of the cut ends into a perforated silicon tube. Proximal to the repair, the most prominent difference was an increase in the number of myelinated axons in the lingual nerve following epineurial suturing but not entubulation. Proximal to the repair site, the number of nonmyelinated axons increased in comparison with controls in both chorda tympani and lingual nerves after both procedures, though the difference was statistically significant only in the lingual nerve proximal to entubulation. Distal to the injury, both types of repair showed a reduction in the number, size, and sheath thickness of myelinated axons in comparison with unoperated controls, but the difference in numbers was statistically signIficant only distal to repair by entubulation. The number of non-myelinated axons distal to the repair sites was much higher than that in controls, the difference being greater distal to entubulation repair. There were more axons per Remak bundle distal to entubulation repair than to epineurial suturing, suggesting, perhaps, that fewer axons would ultimately become myelinated. Though the morphological differences between the two repair techniques are not as striking as the parallel electrophysiological differences reported previously (Smith and Robinson, 1995a,b), they are consistent with them and support the conclusion that, for transected lingual and chorda tympani nerves, epineurial suturing is the preferred approach.

Steroids reduce the periapical inflammatory and neural changes after pulpectomy.

Root canal treatment, including obturation with gutta-percha and a zinc oxide and eugenol sealer, was conducted, under general anesthesia, on the canine teeth of 12 young ferrets. Six of the ferrets were given 0.5 mg/kg dexamethasone daily. Three months after the root canal treatment, under general anesthesia, the animals were perfused with fixative and the canine periapical tissues prepared for histological examination. The extent of periapical inflammation was measured and the degree of neural sprouting in the periodontal and subapical regions estimated. Periapical lesions in steroid-treated animals were 30% of the size of those in untreated animals. Innervation density in the subapical region of the steroid-treated animals was lower than that in the animals who did not receive steroids and not significantly different from controls. Reduction in periapical inflammation induced by systemic steroids is accompanied by a reduction in neural sprouting.

Periapical changes after orthodontic movement of root-filled ferret canines.

The effectiveness of orthodontic forces in moving root-filled teeth and the degree of apical resorption it causes have been observed in an animal model. Under general anesthesia, root canal therapy was performed on the mandibular canines on one side of 12 young male ferrets. Bilateral movement of the canines was induced with an orthodontic spring (150 to 175 g). Procion red dye was injected 1 wk presurgically to mark bone and cementum deposition. Three months later, tooth movement was assessed from pre- and posttreatment mandibular casts and by fluorescence microscopy from labeled bone deposition. Vital and nonvital teeth moved similar distances when subjected to the same forces. Root-filled teeth showed greater loss of cementum after tooth movement than vital teeth (p < 0.05), but without significant differences in radiographic root length.

The effect of pulpectomy on the longitudinal distribution of nerve fibres in the periodontal ligament of the ferret.

The innervation density of the periodontal ligament was measured at a series of levels around the mandibular canines of 6 ferrets, in 5 of the which the pulp of one of each of these pairs of teeth had been removed 3 months earlier. In control (unoperated) teeth the density of innervation was greatest in the apical third and lowest in the coronal third. The pattern around the pulpectomized teeth was similar. There was no statistically significant difference between density values for control and operated teeth. Pulpectomy thus does not affect the incidence or distribution pattern of nerves in the periodontal ligament.

A histological comparison of periapical inflammatory and neural responses to two endodontic sealers in the ferret.

Previous studies have shown that there is a proliferation of nerves beneath the apices of pulpectomized teeth. This may be due to the inflammation induced after the procedure, resulting, perhaps, from the irritant nature of the materials used to fill the root canal. The experiment reported here was conducted to determine whether this inflammation was induced by the sealer rather than arising as a result of tissue damage and whether, if inflammation is eliminated or reduced, the neural changes are also reduced. In 12 young adult ferrets under general anaesthesia the pulps of the lower canine teeth were removed and replaced with gutta percha and sealer. A sealer of Grossman's formulation with eugenol as the liquid phase was used on one side and a calcium hydroxide sealer that contained no eugenol on the other. Three months later the animals were, again under general anaesthesia, perfused with a fixative mixture. The mandibles were removed and the presence and size of any periapical inflammatory lesions and the density of periapical innervation determined histologically. All 12 teeth sealed with the Grossman's sealer had inflammatory lesions at their apices. Three of the 12 teeth treated with the calcium hydroxide sealer showed similar lesions. In all the teeth with inflammatory lesions the normal arrangement of nerves in a periodontal 'plexus' was disrupted but there was no statistically significant difference between the overall innervation density in inflamed and non-inflamed periapical areas nor between areas beneath teeth sealed with Grossman's sealer and with calcium hydroxide. The incidence of periapical inflammation is related to the nature of endodontic sealer used.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological features of dentine and pulp related to dentine sensitivity.

This review considers those structural features of the pulp and dentine relevant to an understanding of dentine sensitivity. It does not discuss innervation, or microvasculature, which are covered in other contributions. The sensitivity of dentine is directly related to the size and patency of the dentinal tubules. Tubular occlusion by peritubular dentine deposition or the formation of other intratubular material would reduce the flow of fluid and diffusion of molecules through dentine. Irregular (reparative) secondary dentine would, because its tubules are not continuous with those of primary dentine, be expected to reduce permeability and fluid flow and decrease sensitivity. Regular secondary dentine would have little or no effect other than by increasing diffusion distances. The odontoblast layer is of limited permeability and could restrict the access of materials diffusing through the dentinal tubules to pulpal axons. Odontoblasts are not involved in the sensory process as special sensory receptors but may, by modifying the local ionic environment, alter the threshold of intradentinal nerves.

Pulp re-innervation in re-implanted canine teeth of the cat.

This was investigated 24 weeks post-operatively by light and electron microscopy. The number of axons in the pulp at the root apex ranged from 7.5 to 76.2 per cent of the number in the contralateral control tooth. The myelinated fibres were smaller and did not penetrate as far as the coronal pulp.

The distribution and morphological characteristics of axons innervating the periodontal ligament of reimplanted teeth in cats.

Twelve weeks after reimplanting lower canines the distribution and characteristics of myelinated and non-myelinated axons within the periodontal ligament were investigated by light and electron microscopy. The ligament was examined at 2-mm intervals along the length of the root of four reimplanted teeth and of the contralateral canines, which served as controls. In each case the periodontal ligament was reinnervated. In two of the teeth, which showed extensive apical resorption, the innervation was much less than in control teeth. In two teeth showing minimal or no apical resorption the degree of innervation at the most apical level did not differ significantly from controls.

Reinnervation of teeth after segmental osteotomy.

The reinnervation of 8 canine teeth denervated by segmental osteotomy has been investigated in cats by using electron microscopy. 12 weeks after osteotomy, the mean total number of axons at the canine apices was 36% of that found in normal animals. The myelinated axons were smaller than normal with thinner myelin sheaths. In non-myelinated fibres, there were fewer axons per fibre (Remak bundle) and more fibres containing only one axon. The proportions of myelinated and non-myelinated fibres were normal.

Periapical neural changes after pulpectomy.

Pulpectomy and pulpal necrosis result in severance of the nerves that supply the pulp as well as loss of their target organ. Inflammatory changes commonly extend into the periapical region to involve those nerves. The neural response to pulpal loss combined with periapical inflammation is a derangement of the periodontal plexus normally located in the center of the periodontal space around the apical third of the root; the result is the formation of a disorganized group of sprouting and branching axons that have some features in common with neuromas. The inflammatory and neural responses continue for at least a year even when pulpectomy is followed by canal debridement and obturation. Then the responses are reduced but not eliminated by steroids. Root canal therapy with techniques that do not leave residual inflammation still results in increased periapical innervation; the increase seems to be an organized addition to the normal periradicular plexus.