Distinct alterations in probabilistic reversal learning across at-risk mental state, first episode psychosis and persistent schizophrenia.

We used a probabilistic reversal learning task to examine prediction error-driven belief updating in three clinical groups with psychosis or psychosis-like symptoms. Study 1 compared people with at-risk mental state and first episode psychosis (FEP) to matched controls. Study 2 compared people diagnosed with treatment-resistant schizophrenia (TRS) to matched controls. The design replicated our previous work showing ketamine-related perturbations in how meta-level confidence maintained behavioural policy. We applied the same computational modelling analysis here, in order to compare the pharmacological model to three groups at different stages of psychosis. Accuracy was reduced in FEP, reflecting increased tendencies to shift strategy following probabilistic errors. The TRS group also showed a greater tendency to shift choice strategies though accuracy levels were not significantly reduced. Applying the previously-used computational modelling approach, we observed that only the TRS group showed altered confidence-based modulation of responding, previously observed under ketamine administration. Overall, our behavioural findings demonstrated resemblance between clinical groups (FEP and TRS) and ketamine in terms of a reduction in stabilisation of responding in a noisy environment. The computational analysis suggested that TRS, but not FEP, replicates ketamine effects but we consider the computational findings preliminary given limitations in performance of the model.

Jean Talairach (1911-2007). An untold story of the pioneer of stereotactic and functional neurosurgery.

CONTEXT: The Department of neurosurgery of the Sainte-Anne Hospital hosted Jean Talairach who created and developed stereotactic neurosurgery in France. Despite numerous neurosurgical and neuroscientific achievements, little is known about the life of Jean Talairach. METHODS: Systematic screening of Sainte-Anne Hospital Museum, Henry Ey Library, and Bibliothèque Inter-Universitaire de Santé funds, and medical databases using the term "Jean Talairach". RESULTS: Jean Talairach started his medical career at the Sainte-Anne Hospital in 1942 as a psychiatrist and became a neurosurgeon due to his interest in stereotactic neurosurgery. During World War II, Jean Talairach joined the French Resistance in Paris, then the French First Army. Jean Talairach created an original and specific stereotactic methodology with appropriate stereotactic frame and tools and performed one of the first human stereotactic surgeries in 1948. He described the reference lines passing by the anterior and posterior commissures in 1952 and developed a tridimensional co-planar stereotactic atlas of the human brain. With the collaboration of Jean Bancaud, he created stereo-electroencephalography to investigate patients suffering from drug-resistant epilepsy. The "Sainte-Anne school" trained French and foreign stereotactic and functional neurosurgeons ensuring the spread of Jean Talairach's innovative ideas. Jean Talairach retired in 1980. CONCLUSION: Jean Talairach's achievements encapsulate the evolution of neurosurgery in France during the 20th century. He developed an original stereotactic methodology including a tridimensional stereotactic atlas of the human brain and a stereotactic frame. He created stereo-electroencephalography, which remains the gold-standard to investigate patients suffering from drug-resistant epilepsy.

[The next psychoactive drugs: From imipramine to ketamine]. / Psychotropes du futur : de l'imipramine à la kétamine.

Since the 1950s, the therapeutic arsenal against depression has grown considerably. From the discovery of monoamine oxidase inhibitors (MAOI) to the antidepressant effect of ketamine, these pharmacological breakthroughs made the history of psychiatry. They also guided the research about the pathophysiology of depression, one of the most devasting diseases, which affects between 10 and 20 % of general population. In this article, we offer a short historical review of the various therapeutic options developed over the past century and the consequences of these innovations. We then review the most recent one, ketamine (and its enantiomer S, esketamine). Ketamine's effects are spectacular both in terms of their very short onset time, and because they are observed even in treatment-resistant depression. Just as MAOIs and tricyclic antidepressants allowed the "monoaminergic hypothesis of depression" to emerge, to unravel the mechanisms of ketamine's antidepressant effects should allow the understanding of the role of glutamatergic system, or that of neuro-inflammation, in the neurobiology of depression. Ketamine might also help to refine our understanding of the cognitive pathophysiology of depression, or even to deeply transform the clinical representations about what depression is.

[Repurposing of chlorpromazine in COVID-19 treatment: the reCoVery study]. / Repositionnement de la chlorpromazine dans le traitement du COVID-19 : étude reCoVery.

OBJECTIVES: The ongoing COVID-19 pandemic comprises a total of more than 2,350,000 cases and 160,000 deaths. The interest in anti-coronavirus drug development has been limited so far and effective methods to prevent or treat coronavirus infections in humans are still lacking. Urgent action is needed to fight this fatal coronavirus infection by reducing the number of infected people along with the infection contagiousness and severity. Since the beginning of the COVID-19 outbreak several weeks ago, we observe in GHU PARIS Psychiatrie & Neurosciences (Sainte-Anne hospital, Paris, France) a lower prevalence of symptomatic and severe forms of COVID-19 infections in psychiatric patients (∼4%) compared to health care professionals (∼14%). Similar observations have been noted in other psychiatric units in France and abroad. Our hypothesis is that psychiatric patients could be protected from severe forms of COVID-19 by their psychotropic treatments. Chlorpromazine (CPZ) is a phenothiazine derivative widely used in clinical routine in the treatment of acute and chronic psychoses. This first antipsychotic medication has been discovered in 1952 by Jean Delay and Pierre Deniker at Sainte-Anne hospital. In addition, to its antipsychotic effects, several in vitro studies have also demonstrated a CPZ antiviral activity via the inhibition of clathrin-mediated endocytosis. Recently, independent studies revealed that CPZ is an anti-MERS-CoV and an anti-SARS-CoV-1 drug. In comparison to other antiviral drugs, the main advantages of CPZ lie in its biodistribution: (i) preclinical and clinical studies have reported a high CPZ concentration in the lungs (20-200 times higher than in plasma), which is critical because of the respiratory tropism of SARS-CoV-2; (ii) CPZ is highly concentrated in saliva (30-100 times higher than in plasma) and could therefore reduce the contagiousness of COVID-19; (iii) CPZ can cross the blood-brain barrier and could therefore prevent the neurological forms of COVID-19. METHODS: Our hypothesis is that CPZ could decrease the unfavorable evolution of COVID-19 infection in oxygen-requiring patients without the need for intensive care, but also reduce the contagiousness of SARS-CoV-2. At this end, we designed a pilot, phase III, multicenter, single blind, randomized controlled clinical trial. Efficacy of CPZ will be assessed according to clinical, biological and radiological criteria. The main objective is to demonstrate a shorter time to response (TTR) to treatment in the CPZ+standard-of-care (CPZ+SOC) group, compared to the SOC group. Response to treatment is defined by a reduction of at least one level of severity on the WHO-Ordinal Scale for Clinical Improvement (WHO-OSCI). The secondary objectives are to demonstrate in the CPZ+SOC group, compared to the SOC group: (A) superior clinical improvement; (B) a greater decrease in the biological markers of viral attack by SARS-CoV-2 (PCR, viral load); (C) a greater decrease in inflammatory markers (e.g. CRP and lymphopenia); (D) a greater decrease in parenchymal involvement (chest CT) on the seventh day post-randomization; (E) to define the optimal dosage of CPZ and its tolerance; (F) to evaluate the biological parameters of response to treatment, in particular the involvement of inflammatory cytokines. Patient recruitment along with the main and secondary objectives are in line with WHO 2020 COVID-19 guidelines. CONCLUSION: This repositioning of CPZ as an anti-SARS-CoV-2 drug offers an alternative and rapid strategy to alleviate the virus propagation and the infection severity and lethality. This CPZ repositioning strategy also avoids numerous developmental and experimental steps and can save precious time to rapidly establish an anti-COVID-19 therapy with well-known, limited and easy to manage side effects. Indeed, CPZ is an FDA-approved drug with an excellent tolerance profile, prescribed for around 70 years in psychiatry but also in clinical routine in nausea and vomiting of pregnancy, in advanced cancer and also to treat headaches in various neurological conditions. The broad spectrum of CPZ treatment - including antipsychotic, anxiolytic, antiemetic, antiviral, immunomodulatory effects along with inhibition of clathrin-mediated endocytosis and modulation of blood-brain barrier - is in line with the historical French commercial name for CPZ, i.e. LARGACTIL, chosen as a reference to its "LARGe ACTion" properties. The discovery of those CPZ properties, as for many other molecules in psychiatry, is both the result of serendipity and careful clinical observations. Using this approach, the field of mental illness could provide innovative therapeutic approaches to fight SARS-CoV-2.

Repurposing chlorpromazine to treat COVID-19: The reCoVery study.

OBJECTIVES: The ongoing COVID-19 pandemic has caused approximately 2,350,000 infections worldwide and killed more than 160,000 individuals. In Sainte-Anne Hospital (GHU PARIS Psychiatrie & Neuroscience, Paris, France) we have observed a lower incidence of symptomatic forms of COVID-19 among patients than among our clinical staff. This observation led us to hypothesize that psychotropic drugs could have a prophylactic action against SARS-CoV-2 and protect patients from the symptomatic and virulent forms of this infection, since several of these psychotropic drugs have documented antiviral properties. Chlorpromazine (CPZ), a phenothiazine derivative, is also known for its antiviral activity via the inhibition of clathrin-mediated endocytosis. Recentin vitro studies have reported that CPZ exhibits anti-MERS-CoV and anti-SARS-CoV-1 activity. METHODS: In this context, the ReCoVery study aims to repurpose CPZ, a molecule with an excellent tolerance profile and a very high biodistribution in the saliva, lungs and brain. We hypothesize that CPZ could reduce the unfavorable course of COVID-19 infection among patients requiring respiratory support without the need for ICU care, and that it could also reduce the contagiousness of SARS-CoV-2. For this purpose, we plan a pilot, multicenter, randomized, single blind, controlled, phase III therapeutic trial (standard treatment vs. CPZ+standard treatment). CONCLUSION: This repurposing of CPZ for its anti-SARS-CoV-2 activity could offer an alternative, rapid strategy to alleviate infection severity. This repurposing strategy also avoids numerous developmental and experimental steps, and could save precious time to rapidly establish an anti-COVID-19 therapy with well-known, limited and easily managed side effects.

Subdural hematoma and electroconvulsive therapy: A case report and review of the literature.

BACKGROUND AND CASE PRESENTATION: Electroconvulsive therapy (ECT) is a common therapeutic procedure in psychiatry associated with a low rate of complications. We report a rare case of subdural hematoma (SDH) associated with ECT. CLINICAL PRESENTATION: a 64 year old woman, with a medical history of persistent depression which required ECT six years previously, underwent ECT following a new acute episode. After four ECT sessions, a left hemiparesis occurred. Brain CT scan revealed a right SDH. The patient underwent surgery and fully recovered three months after the drainage of the hematoma. We conducted a review of all cases in which SDH was associated to ECT. CONCLUSION: Early stage brain imaging is indispensable prior to starting ECT. Moreover, a previous medical history of SDH may not be a contraindication to ECT. In these situations, a clinical and radiological follow-up by both the psychiatrist and the neurosurgeon during all the ECT sessions is highly recommended.

Anhedonia predicts poor psychosocial functioning: Results from a large cohort of patients treated for major depressive disorder by general practitioners.

BACKGROUND: Anhedonia is a core symptom of major depression and a key prognostic factor that is often poorly explored in clinical trials of major depressive disorder (MDD). Beyond symptomatic remission, psychosocial functioning also reveals difficulty in achieving remission in patients with MDD. The main objective of this study was to explore the interrelationships between social functioning and anhedonia on a longitudinal basis. METHODS: In total, 1570 outpatients treated for MDD with agomelatine were included. Severity of depression and levels of anhedonia and of psychosocial functioning were assessed at inclusion and at 10-14 weeks, with specific standardized scales (MADRS, QFS, SHAPS, CGI). Multivariate regression and mediation analyses were performed. RESULTS: Using multivariate regression, we showed that improvement of anhedonia was the strongest predictor of improvement in psychosocial functioning (odds ratio=7.3 [4.3-12.1] P<0.0001). In addition, mediation tests confirmed that the association between improvement of depressive symptoms and improvement of social functioning was significantly underpinned by the improvement of anhedonia over time. Finally, we explored the determinants of the dissociation of the response, i.e., the persistence of psychosocial dysfunctioning despite a symptomatic response to antidepressant treatment, which remains a widespread situation in clinical practice. We showed that this dissociation was strongly predicted by persistence of anhedonia. CONCLUSION: Our results suggest that anhedonia is one of the strongest predictors of psychosocial functioning, along with symptomatic remission, and should be carefully assessed by health professionals, in order to optimize pharmacological as well as non-pharmacological management of depression.

Confidence and psychosis: a neuro-computational account of contingency learning disruption by NMDA blockade.

A state of pathological uncertainty about environmental regularities might represent a key step in the pathway to psychotic illness. Early psychosis can be investigated in healthy volunteers under ketamine, an NMDA receptor antagonist. Here, we explored the effects of ketamine on contingency learning using a placebo-controlled, double-blind, crossover design. During functional magnetic resonance imaging, participants performed an instrumental learning task, in which cue-outcome contingencies were probabilistic and reversed between blocks. Bayesian model comparison indicated that in such an unstable environment, reinforcement learning parameters are downregulated depending on confidence level, an adaptive mechanism that was specifically disrupted by ketamine administration. Drug effects were underpinned by altered neural activity in a fronto-parietal network, which reflected the confidence-based shift to exploitation of learned contingencies. Our findings suggest that an early characteristic of psychosis lies in a persistent doubt that undermines the stabilization of behavioral policy resulting in a failure to exploit regularities in the environment.

Caries experience and related factors in 4-6 year-olds attending dental clinics in Kinshasa, DR of Congo.

OBJECTIVES: The aim of this study was to examine the prevalence and severity of caries experience (CE) in 4-6 year-olds attending dental clinics in Kinshasa, DR Congo, and to explore possible associations with reported behavioural and socio-demographic factors. METHODS: A convenience sample of children attending five dental clinics was recruited. Carers, usually parents, completed a questionnaire consisting of socio-demographic information, oral health and tobacco consumption profile of parents, socio-economic family situation and oral health habits of the child. Children were clinically examined using WHO criteria by trained dentist-examiners. To investigate factors associated with CE, multivariate logistic regression was applied with the significance level set at 0.05. RESULTS: Some 158 children with mean age 5.3 (sd 0.7) years were recruited; 80% presented with clinical signs of CE. Between-meal snacking and drinking was reported by 78% and 65%; 35% had sugar-containing drinks. Most (81%) brushed once a day and 82% brushed in the morning. Prevalence of CE was associated with gender, frequency of meals, consumption of drinks during meals and consumption of sugar-containing drinks; severity with type of infant feeding and sugar-content of the last meal at night. CONCLUSION: The present study shows that both prevalence and severity of caries experience were associated with reported dietary habits, confirming the importance of preventive interventions dealing with these habits in young children living in a developing country.

Accuracy and surgical feasibility of a CBCT-based stereolithographic surgical guide aiding autotransplantation of teeth: in vitro validation.

The aims of this study were to determine the accuracy of a 3D computer model and stereolithographic (STL) replica when compared to the real tooth and to develop a cone beam computed tomography (CBCT)-based planning technique including surgical guide fabrication. A STL surgical guide and a tooth replica were fabricated using SimPlant Pro 12.1. To validate this process, tooth segmentation and replica design were prepared for comparison to an optical scan of the corresponding tooth. For surgical intervention, a dry dentate mandible was scanned using a Scanora CBCT and the donor tooth was segmented. The donor tooth was repositioned, and two guides were designed. These tooth replica and guides were used in socket preparation of the dry mandible. The 3D computer model of the segmented teeth and related STL models showed satisfactory results with an acceptable accuracy. The surfaces were within 0·25mm distance, but in some areas up to 2·5mm deviation were seen. The results showed that 79% of the points was between 0·25 and -0·25mm, 3% was overestimated (>0·25mm) and 18% was underestimated (<-0·25mm). The computer-based repositioning of the donor tooth and construction of tooth replica and guide allowed socket preparation before donor tooth extraction and optimization of the STL procedure for in vivo planning of CBCT-based autotransplantation.

[The combination of a fused tooth and a supernumerary central incisor: a possible treatment plan]. / Het samen voorkomen van een dubbeltand en een boventallig gebitselement. Een mogelijke behandeling.

An 8-year old boy was referred to the orthodontic department because of a fused tooth. The clinical and radiological examination showed that - besides the double tooth at the region of the 21 - there was a normal tooth 22 in eruption as well. Moreover a still impacted supernumerary tooth was present in the right upper front region. The treatment included the extraction of the fused tooth and an autotransplantation of the supernumerary tooth to the extraction site of the fused tooth. During the follow-up period the pulp showed a progressive obliteration starting at the crown level with a conservation of the vitality. Apexification of the root of the transplanted tooth proceeded successfully. Furthermore a review of the literature is given in this article on the aetiology and treatment of fused teeth and on the application of autotransplantation.

Tooth transplantations: a descriptive retrospective study.

The aim of the present study was to perform a retrospective study of autogeneously transplanted teeth in order to examine the influence of clinical criteria such as the type of the donor tooth, the root length at the time of transplantation, donor eruption stage and others on the overall success rate of the transplantation. The material of this study consisted of 194 patients in whom 273 teeth were transplanted. The mean age at the time of autotransplantation was 18.1 years with a standard deviation of 7.5 years. Transplantations were performed in two hospitals. The follow-up period varied from 15 days to 11 years, and the mean follow-up time was 3.8 years. 58/273 teeth showed one or other form of resorption, 37/273 teeth showed ankylosis, 30/273 showed no important changes in pulp chamber size, 104/273 showed major discoloration after transplantation, 92/273 teeth showed positive results for cold test after transplantation and 26/273 teeth showed clinically unacceptable pocket depth. Clinical and radiological evaluations were performed. An association was found between successful transplantation and donor tooth type (P<0.01), root length at the time of transplantation (P<0.0001) and recipient tooth site (P=0.03). There was a borderline association between successful transplantation and donor eruption stage (P=0.05). In conclusion, autotransplantation of teeth performed with a careful surgical procedure at the stage of 1/2-3/4 of their intended or expected root length can render a very useful service to patients.

Comprehensive dental care for children with rampant caries under general anaesthesia.

OBJECTIVE: Critical reflection on treatment strategy for dental rehabilitation of young children with rampant caries using day-stay general anaesthesia at a university dental clinic. DESIGN: Cross-sectional analysis of 98 cases. SETTING: The study was undertaken at the university paediatric dental clinic of Leuven, Belgium. SAMPLE AND METHODS: The sample consisted of 98 healthy patients referred for dental treatment under general anaesthesia with a mean age of 4.8 (+/- 1.1) years and mean dmft-score of 9.3 (+/- 3.0). Data were obtained by history taking, clinical examination, questionnaires (filled in by parents) and standardized data records (filled in by dentists and nurses in the recovery area and day-stay clinic). RESULTS: Most patients were referred by their private dentist (74.5%) because of a need for extensive dental treatment in an uncooperative child. Induction of anaesthesia was upsetting in a significant number of cases (68% of children). The mean duration of the whole procedure was 80.9 (+/- 24.7) minutes. A mean number of 7.2 (+/- 2.9) primary teeth were filled and 1.8 (+/- 2.0) extracted per patient. Post-operative problems (nausea/vomiting, temperature rise) were seen in only 8.2% of the patients. CONCLUSIONS: The technique used at this centre allows for extensive dental treatment of young children with a high level of acceptability and minimal morbidity, using day-stay general anaesthesia. Based on this review, it became clear that less upsetting methods for the induction of anaesthesia need to be explored. Criteria for the administration of antibiotics need to be defined more clearly and the use of stainless steel crowns should be envisaged for restorations on primary molars. The global outcome of this treatment provision in children at high caries risk should be evaluated over a longer period, including an evaluation of oral health status, restorative treatment (conservation vs. extraction) and behavioural aspects.

[What is the cause of failure of local anesthesia?]. / Que faire en cas d'échec de l'anesthésie locale?

Local anesthesia fails in 10% of cases of inferior alveolar nerve block and 7% of all cases of local anesthesia in general practice. Possible causes of failure are infection, wrong selection of local anesthetic solution, technical mistakes, anatomical variations with accessory innervation and anxiety of the patient. In this publication we discuss reasons for frequent failure in case of infection and in inferior alveolar nerve block. Understanding the mechanism of failure in local anesthesia, makes it possible to formulate guidelines to guarantee success. These measures are discussed in detail.

[Local anesthesia in children]. / Anesthésie locale chez l'enfant.

Local analgesia in children necessitates a correct approach. Sufficient explanation about the procedure and preparation of the child are important. Because of differences in anatomy, the technique of anesthesia needs adaptation. The different techniques are reviewed and discussed. The children are at greater risk of overdose when local anesthetics are administered. Calculation of the maximum permitted dose is necessary and with good precautions accidents can be prevented.

Oral hygiene in 12-year-old disabled children in Flanders, Belgium, related to manual dexterity.

As part of a larger epidemiological survey of a stratified sample of 12-year-old handicapped children in Flanders, Belgium, the present study describes gingival health, gingival hypertrophy, oral cleanliness and the presence of calculus. Statistical analysis was performed with motor skills, brushing help, the use of chemical agents, the use of anti-epileptic drugs, the knowledge of parents and educators (or caregivers) and their opinion of the oral hygiene of their children/ pupils as response variables. From this study, it became clear that mildly mentally retarded and learning-impaired children had significantly better manual dexterity skills than moderately and severely mentally retarded and physically impaired children. However, this was not reflected in improved oral hygiene. The use of chemical plaque controlling agents was found to be extremely low and, with the exception of children with gingival hyperplasia, the users of these agents did not have better oral hygiene. No difference was found between subtypes in the opinion of parents and educators on oral status. There was, however, a difference between their assessment and the clinical picture. It was concluded that there was a need for in-service training programmes in oral health care for educators as well as for parents.

Caries pattern and oral health habits in 2- to 6-year-old children exhibiting differing levels of caries.

The aim of the present study was to describe in detail the distribution of caries lesions among tooth types and surfaces in the primary dentition of young children with different levels of disease. A total of 125 children (between 2 and 6 years old) attending the pediatric dental clinic of the University Hospital of Leuven was allocated to three groups based on their caries experience: dmft = 1-5 formed the low caries experience group (LC, n = 27), dmft = 6-9 the moderate caries experience group (MC, n = 61) and those with dmft > = 10 the high caries experience group (HC, n = 37). Caries experience (at patient level, tooth and tooth surface level) and oral hygiene were evaluated. Oral health habits were recorded using a questionnaire (completed by parents). Caries lesions were not evenly distributed among different tooth types. Teeth most frequently affected were lower (first and second) primary molars. Primary incisors were rarely found to be carious. The distribution of the lesions followed a comparable pattern, irrespective of the disease level of the child. Decay on primary canines and buccal/lingual surfaces of primary molars was strongly indicative of a high caries experience. There was a clear link with reported oral hygiene habits and the use of a pacifier and baby bottle with sugared content.

The effect of periodontal therapy on the number of cariogenic bacteria in different intra-oral niches.

Several publications have reported an increased susceptibility for root caries after periodontal therapy. It has been suggested that newly exposed roots were less resistant to cariogenic species. This study examined the hypothesis that the increased susceptibility could also be related to an intra-oral microbial shift during the initial phase of the periodontal therapy from a perio-pathogenic to a more cariogenic flora. 10 patients with severe periodontitis were followed for 8 months after thorough scaling and root planing in combination with optimal plaque control. At baseline and after 4 and 8 months, samples were taken from the saliva, the tongue dorsum and the supragingival interdental spaces. These samples were cultured both aerobically and anaerobically in order to determine the total number of colony forming units (CFU) per sample as well as the number of CFU of Streptococcus mutans and Lactobacillus species. Oral hygiene parameters were recorded at the same visits. Finally, at baseline and at the 8 months follow-up, changes in caries activity and periodontal health were registered. Although the total number of aerobic and anaerobic CFU in samples from the tongue and the saliva remained nearly constant over the entire observation period (variations within 0.5 log), significant (p< or =0.05) increases in the number of S. mutans could be detected, especially at month 8. The significant decrease in the total number of anaerobic CFU in samples from the teeth was not associated with a reduction in the number of S. mutans, so that also for this niche the relative proportion of the latter increased. The number of lactobacilli species for the different niches showed only negligible changes (within 0.5 log values), except for samples from the teeth for which a small (1 log), but statistically significant (p<0.01), reduction could be detected. The periodontal conditions improved for all patients, but the caries activity could not be arrested. These findings seem to indicate that the increased caries susceptibility after periodontal therapy might partially be explained by a significant increase in the number of S. mutans due to ecological changes within the oral cavity. The clinical consequence of this observation would be to advocate a more strict caries preventive program during initial periodontal therapy.

Oral health status in Belgian 3- to 5-year-old children.

The aim of this study was to determine the need for oral health care in young Belgian children in the municipality of Leuven, Belgium. The sample consisted of 750 boys and girls (3 years = 200, 4 years = 200 and 5 years = 350). Clinical examination was carried out by one examiner and duplicate recordings were made on 10% of the sample. The clinical examination included recording of: (1) plaque index; (2) gingival index; (3) caries index; and (4) fluorosis index. Plaque and gingival indices were recorded at six sites of smooth surfaces on selected teeth. Occlusal plaque was also registered. Before the clinical examination for caries and fluorosis, the children had their teeth professionally cleaned with toothbrushes and dental floss and dried by means of gauze bandages. In all age groups, the percentage of plaque-free sites was of the order of 60% and sound gingiva was identified at 83% of the recorded sites. The percentages of caries-free children were 69% (3 years), 57% (4 years) and 52% (5 years). The mean deft scores (standard error) were 1.37 (+/- 0.21), 1.76 (+/- 0.21) and 2.03 (+/- 0.17). The corresponding mean defs scores were 2.04 (+/- 0.44), 2.46 (+/- 0.35) and 3.75 (+/- 0.42). Non-cavitated active lesions, included in the defs scores, represented about 50% of all caries lesions. Early signs of dental fluorosis were identified in 19% (3 years), 17% (4 years) and 9% (5 years) of children. The need for oral health care in the population studied is mainly related to non-operative treatment procedures aimed at controlling the progression of disease.