Complete Denture Preclinical Training Program and Digital Tools: A Pilot Study.

PURPOSE: To determine whether digital training improves conceptual skills acquisition for custom tray fabrication and tooth arrangement in the preclinical curriculum for complete denture fabrication. MATERIALS AND METHODS: A crossover design study compared third-year student grades after conventional (manual) and digital training. Half the students were trained with conventional techniques prior to digital, while the other half were trained with digital techniques prior to conventional. The first part of the study (DP1) focused on custom tray fabrication and involved 154 students. The second part (DP2) focused on tooth arrangement with 204 students. The effect of preliminary digital training on conceptual skills was assessed by comparing the results of the students using a Student's t-test. Results were also analyzed by ranking on the students' Perceptual Ability Test (PAT) score. Finally, students' satisfaction with the training was investigated. RESULTS: Students who completed the initial digital session achieved better custom tray fabrication and tooth arrangement in the subsequent manual sessions. For manual laboratory work, the most dexterous students (PAT1 group) demonstrated the best performance. However, PAT2 students had the best performance during the digital sessions during DP1, and PAT1 and PAT2 students had the best performance during the digital sessions during DP2. Additionally, 40% of DP1 and 12% of DP2 students expressed satisfaction with digital sessions. CONCLUSION: With complementary manual and digital teaching, digital tools may be useful for enhanced student learning. Digital training has contributed to improve results in manual sessions but did not affect student satisfaction and remained a limited tool to detect learning difficulties.

Use of digital tools for preclinical training in complete denture: A pilot study.

INTRODUCTION: Advances in CAD-CAM complete dentures open up opportunities in preclinical laboratory education. A cross-over study was conducted to assess the benefit of digital training in custom tray fabrication. Hypotheses were that digital training improved conceptual skill acquisition and that assessment of digital work helps in the discrimination of students' difficulty. MATERIALS AND METHODS: Third-year students were allocated either into group A and took the manual practical classes before the digital ones, or into group B (N = 154). Prior to the sessions, a motor skill test was conducted. The influence on the learning process was evaluated by comparing the groups' results to the manual lab work with a Student's t-test. The effectiveness of the assessment in discriminating manual aptitude and conceptual skill was studied through Spearman's rank coefficient between digital and manual scores in conceptual skill and with a subgroup analysis according to the results of the motor skill test. The level of significance was set up at .05. Students' satisfaction was also assessed with a questionnaire. RESULTS: Students in group B achieved better scores. Spearman's rank coefficient test showed a weak correlation, R = .16. For manual lab work, the most manually skilled students did significantly better. In contrast, for the digital session, the medium manually skilled students did better. More than half of the students (55%) found the manual and digital sessions complementary, without identifying any difference depending on the learning sequence. CONCLUSION: Digital training improved the students' results in the conventional practical exercise. Assessments of the digital and conventional custom trays were complementary in order to distinguish conceptual and motor skills.

Opiorphin as a biomarker of orofacial conditions: a meta-analysis.

The aim of this meta-analysis was to answer the following question: "Are there any differences in opiorphin biomarker concentrations between different orofacial conditions and controls?". Two reviewers searched for observational studies that evaluated the levels of opiorphin in orofacial conditions, annotated in seven main databases and three that compile gray literature. Of the 443 articles obtained initially, 8 met the inclusion criteria for quantitative analyses. Relative percentages showed a mean 24.1% higher opiorphin concentration in chronic conditions (Burning Mouth Syndrome, Oral Potentially Malignant Diseases and Temporomandibular Disorder) compared to controls; 33.2% higher opiorphin in sustained pain (Symptomatic Irreversible Pulpitis, Symptomatic Apical Periodontitis, Painful Oral Soft-tissue conditions); and 21.7% higher opiorphin after stimuli (Corneal Foreign Body, Capsaicin). Meta-analysis revealed a standardized mean difference of 0.62 [0.02, 1.22] in the absolute concentration of opiorphin in saliva for the chronic group compared to the control. The analogous values for the sustained group and the stimulated group were 2.24 [0.34, 4.14] and 0.43 [0.00, 0.85], respectively. No differences in opiorphin levels were found for 'after Local Anesthesia before Tooth Extraction' or for apicoectomy. Based on the available evidence, in general, a statistically higher level of opiorphin is found in orofacial conditions. Salivary opiorphin levels are elevated in chronic, persisted and acute pain conditions, presumably reflecting a physiological homeostatic adaptative response to different conditions such as stress or pain. Salivary opiorphin might therefore be used as a valuable biomarker in several oral disorders.

Is burning mouth syndrome associated with stress? A meta-analysis.

BACKGROUND: Some studies have shown burning mouth syndrome (BMS) as comorbid psychosocial and psychiatric disorders, and as well, pointed at stress as a major risk factor. OBJECTIVE: The aim of this meta-analysis was to answer the following question: 'Is there an association between BMS and stress, compared to healthy controls?' METHODS: Two reviewers searched for the effect of stress in BMS and published on five main databases and three from the grey literature. Various questionnaires and biomarkers were analysed. Of the 2489 selected articles, 30 met the inclusion criteria. Studies englobed questionnaires, such as Perceived Stress Questionnaire, Lipp Stress Symptoms Inventory, Holmes-Rahe scale, Depression, Anxiety, and Stress Scale (DASS-21), Recent Experience Test; and various biomarkers, such as cortisol, opiorphin, IgA, α-amylase and interleukins. RESULTS: In all studies with questionnaires, stress was significantly increased in the BMS group vs. control. Patients with BMS presented 25.73% higher cortisol levels, 28.17% higher IgA levels and 40.62% higher α-amylase levels than controls. Meta-analysis found that BMS subjects presented 3.01 nmoL/L [0.53; 5.50] higher cortisol levels, 84.35 kU/L [15.00; 153.71] higher α-amylase levels, 29.25 mg/mL [9.86; 48.64] higher IgA levels and 258.59 pg/mL [59.24; 457.94] higher IL-8 levels than control. No differences were found for opiorphin concentration in ng/mL [-0.96; 2.53]. For interleukins, no differences were founded for IL-1 ß, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α. CONCLUSION: Based on the available evidence, this meta-analysis suggests more stress factors in questionnaire-based studies, and higher levels of cortisol, α-amylase, IgA and IL-8 biomarkers in BMS subjects than controls.

Implementation of game-based training in oral rehabilitation of edentulous patients in an undergraduate dental course.

BACKGROUND: Coronavirus disease-19 dramatically changed the learning conditions of dental students, with restricted access to training sessions and clinical practice. The "Playdent" project proposed the integration of serious games (SGs) in the third-year curriculum, based on tailor-made scenarios questioning the first dental visit of edentulous patients, and examined whether training with the games would advance students' learning outcomes. MATERIALS AND METHODS: Test scores of 89 students, allocated either to a "test" group that accessed SGs during a 4-week test period in addition to conventional lectures or to a "control" group that benefited solely from conventional lectures, were measured before and immediately after the test period. The subsequent satisfaction of students was assessed in the "test" group. RESULTS: Scores obtained after the 4-week period significantly increased within the "test" group (11.1% ± 24.9%, p = 0.04, degree of freedom [df] = 30) while they did not change within the "control" group (p = 0.21, df = 57). Qualitative feedback expressed by students who played SGs during the 4-week period demonstrated that 71% of them rated the SGs as satisfactory and 91% of them judged the consistency of SGs content with lectures to be satisfactory. CONCLUSION: Game-based learning showed a positive impact on the learning outcomes of third-year students. Qualitative assessments provide insights into the pertinence of SGs offered in addition to traditional lectures of third-year complete denture courses. SGs may consolidate skills in oral rehabilitation acquired through traditional passive learning formats proposed in preclinical courses.

Persistent, neuropathic-like trigeminal pain after dental implant loading.

BACKGROUND: Painful post-traumatic trigeminal neuropathy (PTTN) is a known complication of dental implant therapy. Besides cases resulting of nerve damage during surgery or implant placement, some patients report delayed neuropathic-like symptoms only after implant loading i.e. crown placement. The present retrospective study aimed at describing the clinical features of pain experienced by these patients. MATERIAL AND METHODS: The cohort of patients consulting for chronic orofacial pain at the Groupe Hospitalier Pitié-Salpêtrière (Paris, France) between 2015 and 2020 (ABCD study, IRB # TPS 1106180), was screened for patients with history of dental implant placement and persistent pain. Patients with no pain after surgery for 6 months and pain resulting from the loading of the implant, were included. RESULTS: Among 675 files of patients screened, 5 fulfilled inclusion criteria. All patients were women, mean age 62.4 ± 9.8 y.o, and reported trigeminal neuropathic-like persistent pain. Intensity of pain was described as moderate to severe, with pin and needles, burning and tingling, and electric shocks as main symptoms. CONCLUSIONS: These results suggest that implant loading can trigger trigeminal neuropathy, in a previously sensitized nerve. Putative neurophysiological basis of the phenomenon is discussed. Key words:Neuropathic pain, trigeminal nerve, lesion, dental implant, implant loading, allodynia.

Food-related oral discomfort: A cross-sectional survey assessing the sensory dimension of oral discomfort in French independently living adults.

BACKGROUND: Discomfort encountered during oral processing may cause food avoidance and increase the risk of malnutrition in older adults. The aim of the present survey was to explore the relationships between oral health and the oral discomfort experienced while eating in senior people. MATERIALS AND METHODS: In a cross-sectional study, oral discomfort was assessed in a sample of 119 independently living participants aged between 35 and 81 years. Statistical analyses were used to identify categorical variables associated with food-related oral discomfort, including age, oral health-related quality of life (OHQoL), saliva secretion, occluding support, oral diseases and denture use. RESULTS: Food-related oral discomfort concerned 28.5% of the participants. Within the sample study, the risk of experiencing food-related oral discomfort was increased for participants perceiving average (OR = 7.968, CI 95% = 2.603-24.381, p = .000) or poor OHQoL (OR = 17.109, CI 95% = 4.398-66.552, p = .000) and presenting strictly fewer than 7 occlusal functional units (OFUs) (OR = 3.396, CI 95% = 1.206-9.561, p = .020). Textured foods including fibrous (66.6%), heterogenous (60.6%) and grainy foods (42.4%) were mostly cited as food-related oral discomfort trigger factors. Within the 66-80 years group, participants having 0-6 OFUs were four times more likely to experience oral discomfort related to fibrous foods than participants having more than 7 OFUs (OR = 4.812, CI 95% = 1.192-19.415, p = .024). Within this group, participants having their teeth replaced by denture were also four times more likely to develop oral discomfort related to foods with heterogeneous textures (OR = 4.714, CI 95% = 1.030-21.562, p = .045) and grainy foods (OR = 7.285, CI 95% = 1.308-40.568, p = .023) than non-denture wearers. CONCLUSION: Poor oral health conditions may generate oral discomfort with foods in the elderly especially with fibrous, heterogenous and grainy textures, and thus affect mealtime experience.

Training in Implantology and Decision-Making Practices Regarding Edentulism: An Internet-Based Survey.

PURPOSE: To evaluate the first-choice treatment options proposed to edentulous patients and the rationale behind them using an internet-based survey conducted among a sample of French dental clinicians. MATERIALS AND METHODS: From July to December 2018, an internet-based survey was conducted among a sample of 2,000 dental practitioners in order to assess first-choice treatment options proposed to edentulous patients. A total of 349 responses were received, and 310 questionnaires were included for analysis. RESULTS: The majority of clinicians proposed a maxillary complete denture (CD) (59.7%) and mandibular implant overdenture (45.2%) for edentulous patients. Almost 30% of practitioners proposed a CD as the first-choice option for mandibular edentulous patients. Binary logistic regression showed that the likelihood of proposing implant therapy in the maxilla was significantly increased for male practitioners (OR = 2.041, 95% CI = 1.231 to 3.385, P < .05) and for clinicians who had further training in implantology (OR = 2.301, 95% CI = 1.354 to 3.917, P < .05). In the mandible, the likelihood was significantly increased for clinicians who graduated 10 to 19 years ago (OR = 5.312, 95% CI = 1.331 to 21.208, P < .05), had further training in implantology (OR = 2.246, 95% CI = 1.121 to 4.500, P < .05), had expectations of comfort and stability (OR = 11.810, 95% CI =5.289 to 26.372, P < .001), and proposed the treatment according to national and international recommendations (OR = 3.252, 95% CI = 1.208 to 8.755, P < .05). CONCLUSION: The research results suggest that proposing either a CD or implant restorations for treatment of edentulous patients depends on training and specific skills in implantology.

Taste disorder's management: a systematic review.

BACKGROUND: Taste disorder is a frequent drug-induced or disease-related oral trouble. Various pharmacological, surgical, or physical treatments have previously been proposed for taste function recovery. OBJECTIVES: The aim of the present systematic review was to assess the effects of palliative and curative interventions on taste recovery in light of recent literature. MATERIALS AND METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, a search of the literature published up to June 2019 was conducted using MEDLINE via PubMed, EMBASE, and The US National Institutes of Health Trials Register (PROSPERO registration reference: CRD 42019139315). The methodological quality of the included trials was rated with the "Delphi list For Quality Assessment of Randomized Clinical Trials" and the Newcastle-Ottawa scale. RESULTS: From the 1842 titles first identified, 28 articles met the inclusion criteria. Interventions included zinc (aspartate, sulfate, gluconate, acetate, picolinate, and Polaprezinc®), esomeprazole, L-thyroxin, bethanechol, oral glutamine, delta-9-tetrahydrocannabinol, alpha-lipoic acid, Ginkgo biloba, artificial saliva, pilocarpine, local anesthesia, and improved oral hygiene. The quality of evidence ranged from poor to high. CONCLUSION: Improving oral hygiene may promote taste ability. Zinc may prevent and alleviate taste disorder in patients undergoing head and neck radiotherapy. CLINICAL RELEVANCE: The systematic review provided evidence about the clinical efficacy of oral procedures, zinc supplementation, and palliative cares in dysgeusic patients. Further research is needed to find effective treatments with low adverse effects.

Oral health-related food selectivity among French independently living elders.

Impaired oral conditions are described as influencing food intake behaviour and contributing to poor nutritional status in elderly persons. In order to evaluate the influence of age and oral factors on food choice among independently living elderly, we investigated food selectivity and oral health status in elders (aged over 65 years) and in younger people (aged between 35 and 64 years). Food selective behaviour was appraised by using a food selectivity questionnaire based on traditional French dishes. A stepwise binary logistic regression analysis was done to sequentially identify age and oral conditions associated with oral discomfort-related food avoidance. Occlusal status and oral health-related quality of life contributed to food choice. Risk of oral discomfort-related food avoidance was significantly increased in people with fewer than seven occlusal functional units (OFUs) and with Geriatric Oral Health Assessment Index summary scores (GOHAI-ADD) indicating poor and average oral health-related quality of life (P < .05). Age was never a significant factor of food selective behaviour. The present data support the impact of occlusal status and oral health-related quality of life on food behaviour. Specific attention should be given in maintaining or restoring good oral conditions throughout the lifespan, especially occluding teeth.

Intra-oral trigeminal-mediated sensations influencing taste perception: A systematic review.

Food perception is a multimodal sensation which implies cross-modal interplays. Tactile, thermal, painful and kinaesthetic stimuli arising from food intake may impact on flavour perception, especially taste perception. The influence of oral somatosensory signals on food taste perception remains unclear. The aim of the present systematic review was to appraise the effects of oral mechanical, thermal, chemical and pain sensations on taste perception. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, a search of the literature from 1968 to 2018 was conducted using MEDLINE via PubMed, EMBASE and clinical trials (PROSPERO registration reference: CRD42018100176). A total of 105 articles were included for analysis. The results from this review suggest that taste abilities and taste perception are frequently modified by food textural and chemical properties. Furthermore, saliva features, dental and prosthetic status and oral pain can also modulate taste perception. Biological and physiological phenomena underlying these results may be involved such as tastant release, tastant detection, taste transduction and central trigemino-gustatory interplays.

How oral health and food sensory properties impact oral comfort during consumption of apples: A comparative approach in seniors and young adults.

Difficulties encountered during oral processing may cause food avoidance and increase the risk of malnutrition in older adults. The present survey aimed at comparing oral comfort experienced during consumption of apples in elderly and younger people. To do this, 122 participants divided into a senior group (65-83 years) and a control group (35-64 years) rated three varieties of apples (Gala, Granny Smith, Honey Crunch) using a "food comfortability" questionnaire related to general comfort, bolus formation, pain, texture, and taste sensations, and were assessed for their oral conditions. Each score of the "food comfortability" questionnaire was then submitted to a global principal component analysis and an analysis of variance. Apple variety was a significant factor for all items of the questionnaire. Age significantly affected dental pain, crunchiness, and melting sensation, with increased scores for pain and melting perception, and decreased scores for crunchiness when aging. Global comfort experienced while eating apple was also impacted by dental status and resting saliva flow rate. Bolus moistening was related to stimulated saliva flow rate, and its fragmentation was dependant on denture use. Painful sensations depended on self-reported oral quality of life and sweet taste perception was influenced by the presence of oral mucosal disease. Apple variety is a good predictor of oral comfort experienced while eating. Altough age has a little effect on pain and texture perception, oral conditions such as missing teeth or denture use also contribute to oral comfort when consuming apples.

Development and Validation of the French Version of the Orofacial Esthetic Scale.

PURPOSE: The aims of this study were to develop a French version of the Orofacial Esthetic Scale (OES) and to investigate its psychometric properties among French-speaking dental patients. MATERIALS AND METHODS: The OES is an eight-item instrument initially developed to assess self-reported orofacial esthetics in patients with prosthodontic concerns. The first seven items refer to direct esthetic impact and give a summary score, and the remaining item is a global assessment item. The original English version of the OES questionnaire was translated and cross-culturally adapted to develop a French version (OES-F). The reliability (internal consistency and test-retest reliability) and validity (convergent and discriminative) of the OES-F were then tested in a sample of 140 patients awaiting dental treatment. RESULTS: Cronbach's alpha coefficients of the OES-F ranged from 0.885 to 0.913. The corrected item-total correlation coefficients ranged from 0.523 to 0.872. Intraclass correlation coefficient values were 0.94 (95% confidence interval [CI] 0.89 to 0.97) for the summary score and ranged between 0.85 (95% CI 0.73 to 0.92) and 0.90 (95% CI 0.81 to 0.94) for the items. OES-F summary scores assessed by patients were significantly correlated with experts' ratings (r = 0.51; P < .05). OES-F summary scores discriminated patients with esthetic concerns from those without esthetic concerns (P < .05). CONCLUSION: The OES-F questionnaire showed excellent psychometric properties and may be a suitable scale for assessing orofacial esthetics among French patients awaiting dental treatment.

Opiorphin levels in fluids of burning mouth syndrome patients: a case-control study.

OBJECTIVES: Idiopathic Burning mouth syndrome (iBMS) is a poorly understood affection characterized by persistent pain in the oral cavity without any clinical or biological abnormality. Opiorphin is a natural inhibitor of enkephalin-inactivating ectopeptidases, mainly produced by salivary glands, that has demonstrated analgesic properties. The objective of the present case-control study was to test the hypothesis of a decrease in opiorphin levels in iBMS patients. MATERIALS AND METHODS: Twenty-one iBMS patients and 21 matched controls subjects were included between 2011 and 2013. Submandibular and sublingual salivary, blood, and urinary opiorphin levels of iBMS patients were compared to controls. RESULTS: Results are expressed as mean values ± SD and compared using the Wilcoxon Signed Rank test. Correlations were analyzed with Spearman coefficient. The level of significance was fixed at p < 0.05. Opiorphin levels in iBMS and controls were respectively (in ng/ml) in basal saliva: 37.8 ± 42.5 and 67.6 ± 188.9 (p = NS); stimulated saliva: 28.8 ± 25.3 and 31.1 ± 29.1 (p = NS); blood: 4.6 ± 5.4 and 1.9 ± 1.4 (p < 0.05); and urines: 68.5 ± 259.8 and 8.9 ± 6.2 (p = NS). CLINICAL RELEVANCE: In conclusion, the lack of significative difference in salivary opiorphin levels between iBMS and controls does not favor a direct local role for opiorphin in the etiopathogeny of iBMS. However, higher blood opiorphin levels may reflect a systemic dysregulation in iBMS. Trial registration NCT02686359 https://clinicaltrials.gov/ct2/show/NCT02686359.

The relationship between the clinical features of idiopathic burning mouth syndrome and self-perceived quality of life.

In this descriptive study, we investigated the relationship between the clinical characteristics of idiopathic burning mouth syndrome (iBMS) and the quality of life. Eighteen iBMS patients were interviewed about their experience with pain, oral-associated complaints, cognitive status, and self-perceived quality of life using the French versions of the Hospital Anxiety and Depression Scale (HADS) and the Global Oral Health Assessment Index (GOHAI). The Spearman coefficient was used to analyze correlations. The level of significance was fixed at P < 0.05. The majority of patients described the association of oral burning sensations with other oral complaints, including dry mouth (77.8%), tactile abnormalities (66.7%), thermal abnormalities (44.5%), and taste disturbances (38.9%). HAD-anxiety scores were higher than 10 in 38.8% of iBMS patients and HAD-depression scores were higher than 10 in 33.3% of patients. A significant correlation was found between the number of associated complaints and HAD-depression scores. The mean GOHAI-add score was 37.9 ± 9.6 (mean ± SD), and 94.5% of iBMS patients had a score lower than 50. GOHAI-add scores strongly correlated with pain intensity, which was calculated using a visual analog scale and duration of pain. Our findings indicate a strong correlation between iBMS-related pain and self-perceived oral health-related quality of life. In addition, a correlation was observed between iBMS-associated oral complaints and cognitive status.(J Oral Sci 58, 475-481, 2016).

Characteristics of pain assessed with visual analog scale and questionnaire in burning mouth syndrome patients: a pilot study.

AIMS: To test the validity of the use of the Douleur Neuropathique en 4 Questions (DN4) questionnaire for burning mouth syndrome (BMS) patients, and to differentiate patients by measuring the time course of the pain in BMS patients over a period of 7 days with a visual analog scale (VAS). METHODS: Patients completed the DN4 questionnaire and a VAS every hour for 7 days. The data were expressed as mean ± SEM. Correlations were searched using the Spearman correlation test with a significance level at P < .05. RESULTS: Data were fully analyzed for the 22 patients (21 females, 1 male, mean [± SEM] age 62.7 ± 2.3 years) for the DN4 and 17 patients for the VAS. DN4 scores ranged from 2 to 7 (mean score: 3.9 ± 0.3), and 59% of the patients had a DN4 score ≥ 4. Burning was found in all the patients, followed by pricking pain (pins and needles) and allodynia (pain on brushing) (both 68%), tingling (45%), numbness (32%), itching (27%), and electrical discharges (23%). Monitoring the hourly time-course of the pain led to the identification of two groups with intermittent or constant pain. In the latter, averaging the VAS for 7 days enabled plotting a curve, the slope of which could be calculated. The range of the slopes was 0.00 to 0.59, and a regular increase of pain during the day was seen for the majority of the patients. CONCLUSION: The findings support the use of DN4 as a tool for screening BMS and reinforce the view that BMS is a clinical manifestation of a neuropathic disease. The methodology of this study can be used for a better description of the patients and the identification of subgroups.

Glutamate control of pulpal blood flow in the incisor dental pulp of the rat.

Glutamate is present in primary sensory afferents innervating the dental pulp and is known to exert vasoactive effects. The aims of this study were (i) to assess pulpal blood flow (PBF) after glutamate infusion in the dental pulp and (ii) to observe the distribution of glutamatergic nerve fibers expressing the vesicular transporters of glutamate (VGluT). The PBF was monitored with laser Doppler flowmetry before and after glutamate (0.5 M) infusion in the dental pulp vs. saline infusion. Immunochemistry for VGluT1, 2, and 3 was performed in addition to immunochemistry for the vascular and neuronal markers smooth-muscle actin (SMA), isolectin B4 (IB4), and calcitonin gene-related peptide (CGRP). Glutamate infusion resulted in a PBF increase that lasted for 60 s. Positive immunolabeling was observed for the three glutamate transporters, but was more pronounced for VGluT3. Moreover, VGluT3 immunoreactivity was observed within nerve fibers entering the dental pulp and terminating at the periphery and at the vicinity of odontoblasts. Also, VGluT3 was colocalized with the vascular marker SMA, and in some nerve fibers with IB4, but not with CGRP. This study provides support for a control of dental pulp microcirculation by neurons expressing VGluT3.

Vesicular glutamate transporters localization in the rat lingual papillae.

Vesicular glutamate transporters (VGluts) are widely expressed in neurons of the central nervous system, where they fulfil numerous functions during glutamatergic neurotransmission. This study examines their peripheral distribution in papillae of the tongue using immunohistochemical methods. VGlut 1 was detected in basal layers of the nontaste epithelium, and in intragemmal and perigemmal zones in taste papillae. Neither VGlut 2 nor VGlut 3 was detected in the lingual epithelium and taste papillae. These findings show the specific lingual pattern of distribution for VGluts and suggest that only VGlut 1 takes part in glutamatergic regulation of epithelial and taste cells within the tongue in physiological conditions.

Trigeminal projections on gustatory neurons of the nucleus of the solitary tract: a double-label strategy using electrical stimulation of the chorda tympani and tracer injection in the lingual nerve.

Taste and sensory information are closely associated and our electrophysiological studies showed a trigeminal modulation of gustatory neurons in the nucleus of the solitary tract (NST). Chorda tympani (CT) and lingual nerves (LN) converge centrally in the rostral subdivision of the NST in hamsters and rats. However, no study has yet revealed the details of this overlap on a same section. We therefore used a double-label strategy to visualize neurons in the NST that receive both trigeminal and gustatory inputs. An anterograde tracer (BDA, Biotinylated Dextran Amine) was applied unilaterally to the cut central end of the LN in male Sprague-Dawley rats. One week later, the ipsilateral CT was electrically stimulated, after which animals were perfused and brainstem sections double-labelled for Fos immunoreactivity of activated NST neurons and BDA labelling of LN afferents. Our results permitted to circumscribe the regional overlap of the trigeminal and CT afferents mainly in the rostral central (RC) subdivision of the gustatory NST. Fos-immunoreactive neurons were observed to be closely apposed by BDA-labelled fibres and terminal boutons. Such varicosities mainly "en passant" were especially present in the RC zone of the nucleus. These observations provide an anatomical substrate for trigemino-gustatory interactions.