État bucco-dentaire des enfants d'âge scolaire consommant une eau riche en fluor à Boguedia, Côte d'Ivoire, en 2019 / Oral status of school children consuming fluoride-rich water in Boguedia, ivory coast, in 2019

National d'Hygiène Publique a noté des concentrations en fluorures dans l'eau de consommation supérieures à 1,5 mg/l, valeur guide indiquée par l'OMS. La présence de fluor dans l'eau peut influencer l'état bucco-dentaire des populations. Le risque majeur est la fluorose dentaire. L'objectif de ce travail était d'évaluer l'état bucco-dentaire des enfants d'âge scolaire de la ville de Boguédia. Méthodes : Il s'est agi d'une enquête transversale à visée descriptive qui s'est déroulée à Boguédia dans le département d'Issia région du haut Sassandra. L'évaluation a concerné l'état bucco-dentaire des enfants d'âge scolaire. Les deux sexes étaient représentés à des pourcentages sensiblement proches ; 49,4% de filles et 50,4% de garçons. Presque tous les sujets examinés (98,5%) n'avaient jamais eu recours aux soins bucco-dentaires. La majorité n'avait jamais eu mal aux dents. La qualité du brossage était mauvaise chez tous les élèves (91,3%). La moitié des élèves avaient une hygiène buccodentaire insuffisante (49,9%). La majorité 78,5% présentait une gingivite. La prévalence de la carie était faible (27,6%). La prévalence de fluorose dentaire a été estimée à 41,8% avec en moyenne 4 dents atteintes. Conclusion : Les résultats obtenus ont montré une prévalence élevée de la fluorose dentaire. Ceci a pour conséquence des modifications de l'état de l'émail dentaire. Si, par le passé, en odontologie l'accent était mis sur la douleur, de nos jours, l'esthétique constitue une préoccupation majeure des populations. Cette étude jette les bases d'une recherche plus poussée sur la problématique de la fluorose en Côte d'Ivoire.

Introduction: In the city of Boguedia, the National Institute of Public Hygiene has noted fluoride concentrations in drinking water above 1.5 mg/l, the guide value indicated by the WHO. The presence of fluoride in water can influence the oral condition of populations. The major risk is dental fluorosis. The objective of this study was to evaluate the oral status of school children in the city of Boguedia. Methods: This is a descriptive cross-sectional survey that took place in Boguédia in the department of Issia, Upper Sassandra region. The evaluation concerned the oral status of school children. Both sexes were represented in similar percentages: 49.4% of girls and 50.4% of boys. Almost all of the subjects examined (98.5%) had never used oral health care. The majority had never had a toothache. The quality of brushing was poor in all students (91.3%). Half of the students had poor oral hygiene (49.9%). The majority 78.5% had gingivitis. The prevalence of caries was low (27.6%). The prevalence of dental fluorosis was estimated at 41.8% with an average of 4 affected teeth. Conclusion: The results obtained showed a high prevalence of dental fluorosis. This results in changes in the condition of the dental enamel. If in the past, in dentistry, the emphasis was put on pain, nowadays, aesthetics constitutes a major concern of the populations. This study lays the foundation for further research on the problem of fluorosis in Côte d'Ivoire

Application of the Kvaal method with cone beam for the determination of a local formula for the age estimation of adult African melanoderma subject, Côte d'Ivoire.

BACKGROUND: Age estimation by invasive dental methods is a destructive, costly and time-consuming approach, whereas, age estimation methods using dental radiographs are simple, non-destructive and provide reliable information. Age estimation by the Kvaal radiographic method has proven to be a reliable method, but possible ethnic variations may limit its uses in other populations. The objective of this study was to reproduce the original Kvaal method with CBCT for the estimation of the age of the adult melano-African subject in Côte d'Ivoire, in order to propose an age estimation formula, specific to our study population, by taking into account the measurements of tooth and pulp ratios. METHODS: A cross-sectional study used 102 radiographic data from a CBCT Planmeca® examination in a private dental clinic in Abidjan. It was data from subjects of at least 18 years of age. Dental measurements in length and width of the entire tooth, root and pulp were performed on maxillary central incisors and the different ratios were calculated according to the Kvaal method. The correlation between age and ratios was also assessed. Age estimated using the Kvaal formula was compared to the chronological age. A linear regression equation was developed using ratios and age predictive factors to evaluate the accuracy of the Kvaal formula. RESULTS: In all, a total of 102 radiographs of 102 subjects, of whom 55 (53.9%) were females, were analyzed. The median age was 51 years (inter-quartile range [IQR] 41- 58). Using the Kvaal formula, the Standard error of the estimated age was higher in the African melanoderma population compared to the Kvaal population. The new formula derived from that of the Kvaal formula was developed and applied to our study population (Age = 84.7- 114.2 (M) - 29.4 (W - L) gave more than double the standard error of estimated age by Kvaal (26.03). CONCLUSION: Our study showed that the measurements made by Kvaal are reproducible with CBCT and there is a correlation between age and the dental parameters studied. However, the age estimation formula determined by Kvaal et al. is not valid for African melanoderma subjects living in Côte d'Ivoire.

Altered mapping of sound frequency to cochlear place in ears with endolymphatic hydrops provide insight into the pitch anomaly of diplacusis.

A fundamental property of mammalian hearing is the conversion of sound pressure into a frequency-specific place of maximum vibration along the cochlear length, thereby creating a tonotopic map. The tonotopic map makes possible systematic frequency tuning across auditory-nerve fibers, which enables the brain to use pitch to separate sounds from different environmental sources and process the speech and music that connects us to people and the world. Sometimes a tone has a different pitch in the left and right ears, a perceptual anomaly known as diplacusis. Diplacusis has been attributed to a change in the cochlear frequency-place map, but the hypothesized abnormal cochlear map has never been demonstrated. Here we assess cochlear frequency-place maps in guinea-pig ears with experimentally-induced endolymphatic hydrops, a hallmark of Ménière's disease. Our findings are consistent with the hypothesis that diplacusis is due to an altered cochlear map. Map changes can lead to altered pitch, but the size of the pitch change is also affected by neural synchrony. Our data show that the cochlear frequency-place map is not fixed but can be altered by endolymphatic hydrops. Map changes should be considered in assessing hearing pathologies and treatments.

Cochlear compound action potentials from high-level tone bursts originate from wide cochlear regions that are offset toward the most sensitive cochlear region.

Little is known about the spatial origins of auditory nerve (AN) compound action potentials (CAPs) evoked by moderate to intense sounds. We studied the spatial origins of AN CAPs evoked by 2- to 16-kHz tone bursts at several sound levels by slowly injecting kainic acid solution into the cochlear apex of anesthetized guinea pigs. As the solution flowed from apex to base, it sequentially reduced CAP responses from low- to high-frequency cochlear regions. The times at which CAPs were reduced, combined with the cochlear location traversed by the solution at that time, showed the cochlear origin of the removed CAP component. For low-level tone bursts, the CAP origin along the cochlea was centered at the characteristic frequency (CF). As sound level increased, the CAP center shifted basally for low-frequency tone bursts but apically for high-frequency tone bursts. The apical shift was surprising because it is opposite the shift expected from AN tuning curve and basilar membrane motion asymmetries. For almost all high-level tone bursts, CAP spatial origins extended over 2 octaves along the cochlea. Surprisingly, CAPs evoked by high-level low-frequency (including 2 kHz) tone bursts showed little CAP contribution from CF regions ≤ 2 kHz. Our results can be mostly explained by spectral splatter from the tone-burst rise times, excitation in AN tuning-curve "tails," and asynchronous AN responses to high-level energy ≤ 2 kHz. This is the first time CAP origins have been identified by a spatially specific technique. Our results show the need for revising the interpretation of the cochlear origins of high-level CAPs-ABR wave 1. NEW & NOTEWORTHY Cochlear compound action potentials (CAPs) and auditory brain stem responses (ABRs) are routinely used in laboratories and clinics. They are typically interpreted as arising from the cochlear region tuned to the stimulus frequency. However, as sound level is increased, the cochlear origins of CAPs from tone bursts of all frequencies become very wide and their centers shift toward the most sensitive cochlear region. The standard interpretation of CAPs and ABRs from moderate to intense stimuli needs revision.

Medial olivocochlear efferent reflex inhibition of human cochlear nerve responses.

Inhibition of cochlear amplifier gain by the medial olivocochlear (MOC) efferent system has several putative roles: aiding listening in noise, protection against damage from acoustic overexposure, and slowing age-induced hearing loss. The human MOC reflex has been studied almost exclusively by measuring changes in otoacoustic emissions. However, to help understand how the MOC system influences what we hear, it is important to have measurements of the MOC effect on the total output of the organ of Corti, i.e., on cochlear nerve responses that couple sounds to the brain. In this work we measured the inhibition produced by the MOC reflex on the amplitude of cochlear nerve compound action potentials (CAPs) in response to moderate level (52-60 dB peSPL) clicks from five, young, normal hearing, awake, alert, human adults. MOC activity was elicited by 65 dB SPL, contralateral broadband noise (CAS). Using tympanic membrane electrodes, approximately 10 h of data collection were needed from each subject to yield reliable measurements of the MOC reflex inhibition on CAP amplitudes from one click level. The CAS produced a 16% reduction of CAP amplitude, equivalent to a 1.98 dB effective attenuation (averaged over five subjects). Based on previous reports of efferent effects as functions of level and frequency, it is possible that much larger effective attenuations would be observed at lower sound levels or with clicks of higher frequency content. For a preliminary comparison, we also measured MOC reflex inhibition of DPOAEs evoked from the same ears with f2's near 4 kHz. The resulting effective attenuations on DPOAEs were, on average, less than half the effective attenuations on CAPs.

Parental behavior correlates to baseline corticosterone of mates and offspring in nesting eastern bluebirds (Sialia sialis).

Raising nestlings in a biparental species involves a complex and dynamic interaction of physiology and behavior among a group of organisms. Parents may be predicted to vary their behaviors based not only upon their own state, but also in relation to the states of both offspring and the other parent. In this study we explore the relationships between parental feeding behaviors and family member condition in eastern bluebirds, with a special emphasis on baseline corticosterone, a hormone associated with energy mediation and stress. We found that the overall number of feeding trips made by both male and female parents were positively correlated to the corticosterone levels of nestlings. Maternal, but not paternal, baseline corticosterone levels were positively correlated to nestling baseline corticosterone levels. Additionally, adult males' feeding behavior was positively correlated to adult females' baseline corticosterone levels. These findings suggest a complex interplay between parental behavior and physiological state not only within a given organism, but also across organisms operating within a family unit. In addition, these results provide evidence that paternal and maternal efforts are influenced by related but distinct pressures, and that male and female parenting may be governed differentially even in species with relatively equitable biparental care.

The auditory nerve overlapped waveform (ANOW) originates in the cochlear apex.

Measurements of cochlear function with compound action potentials (CAPs), auditory brainstem responses, and otoacoustic emissions work well with high-frequency sounds but are problematic at low frequencies. We have recently shown that the auditory nerve overlapped waveform (ANOW) can objectively quantify low-frequency (<1 kHz) auditory sensitivity, as thresholds for ANOW at low frequencies and for CAP at high frequencies relate similarly to single auditory nerve fiber thresholds. This favorable relationship, however, does not necessarily mean that ANOW originates from auditory nerve fibers innervating low-frequency regions of the cochlear apex. In the present study, we recorded the cochlear response to tone bursts of low frequency (353, 500, and 707 Hz) and high frequency (2 to 16 kHz) during administration of tetrodotoxin (TTX) to block neural function. TTX was injected using a novel method of slow administration from a pipette sealed into the cochlear apex, allowing real-time measurements of systematic neural blocking from apex to base. The amplitude of phase-locked (ANOW) and onset (CAP) neural firing to moderate-level, low-frequency sounds were markedly suppressed before thresholds and responses to moderate-level, high-frequency sounds were affected. These results demonstrate that the ANOW originates from responses of auditory nerve fibers innervating cochlear apex, confirming that ANOW provides a valid physiological measure of low-frequency auditory nerve function.

[Traditional practices and exploitation of medicinal plants in odontostomatology in Ivory Coast]. / Pratiques traditionnelles et valorisation des plantes médicinales en odonto-stomatologie en Côte d'Ivoire.

Traditional medicine of which is a part traditional odontology occupies an important place within the African societies. It often constitutes the first appeal (80 % of the population) because of the high cost of the care, the incapacity of the human and material resources but also the faiths of the populations. This reality makes valuation of the traditional odontology a necessity. This study comes within this framework. It's a contribution for a better knowledge of practices and plants used in traditional odontology in Ivory Coast. So, after a presentation of some traditional knowledge's and their fields of application, the authors review studies made on the efficiency of plants in the prevention of tooth decay and the treatment of some oral diseases. The objective of these researches is to elaborate effective and financially affordable traditional improved drugs.

[Survey of general dental practitioners in Abidjan on the use of the operatory field in dentistry]. / Enquête auprès des omnipraticiens d'Abidjan sur l'utilisation du champ opératoire en dentisterie.

Rubber dam is a standard operatory field in operative dentistry and endodontics. It is undoubtedly the most certain way to insure the success of therapeutics acts. Its use by Abidjan practitioners has been the subject of our study which aim is to underline the place of rubber dam in daily practice. Our investigations show that rubber dam is totally absent from practitioners acts. Generally cotton rolls constitute the most frequent mean used by practitioners to isolate the tooth in operative dentistry and endodontics. Only 23.9% of them associate saliva sucking up. Some cases of aspiration and swallowing file by accident by patients have been highlighted. Those results lead us to recommend the systematic use of rubber dam as the mean of efficiency and security which cannot be ignored in our practice.

Efferent-mediated control of basilar membrane motion.

Medial olivocochlear efferent (MOCE) neurones innervate the outer hair cells (OHCs) of the mammalian cochlea, and convey signals that are capable of controlling the sensitivity of the peripheral auditory system in a frequency-specific manner. Recent methodological developments have allowed the effects of the MOCE system to be observed in vivo at the level of the basilar membrane (BM). These observations have confirmed earlier theories that at least some of the MOCE's effects are mediated via the cochlea's mechanics, with the OHCs acting as the mechanical effectors. However, the new observations have also provided some unexpected twists: apparently, the MOCEs can enhance the BM's responses to some sounds while inhibiting its responses to others, and they can alter the BM's response to a single sound using at least two separate mechanisms. Such observations put new constraints on the way in which the cochlea's mechanics, and the OHCs in particular, are thought to operate.

[Preoperative diet and complete dentures in Ivory Coast]. / Diététique préopératoire et prothèse adjointe totale en Côte d'Ivoire.

The toothless patients of developing country are a real problem of nutrition. The practitioners are in the habit of doing the prostheses restoration wit hoof thinking of alimentation. In this work, authors show the energetic and protein malnutrition of the toothless patients of Cote d'lvoire and propose a hyperprotein diet with their alimentation habit in order to prepare the psychic and physic site who must receive complete prostheses.

Otoacoustic emissions without somatic motility: can stereocilia mechanics drive the mammalian cochlea?

Distortion product otoacoustic emissions (DPOAEs) evoked by low-level tones are a sensitive indicator of outer hair cell (OHC) function. High-level DPOAEs are less vulnerable to cochlear insult, and their dependence on the OHC function is more controversial. Here, the mechanism underlying high-level DPOAE generation is addressed using a mutant mouse line lacking prestin, the molecular motor driving OHC somatic motility, required for cochlear amplification. With prestin deletion, attenuated DPOAEs were measurable at high sound levels. DPOAE thresholds were shifted by approximately 50 dB, matching the loss of cochlear amplifier gain measured in compound action potentials. In contrast, at high sound levels, distortion products in the cochlear microphonic (CM) of mutants were not decreased re wildtypes (expressed re CM at the primaries). Distortion products in both CM and otoacoustic emissions disappeared rapidly after death. The results show that OHC somatic motility is not necessary for the production of DPOAEs at high SPLs. They also suggest that the small, physiologically vulnerable DPOAE that remains without prestin-based motility is due directly to the mechanical nonlinearity associated with stereociliary transduction, and that this stereocilia mechanical nonlinearity is robustly coupled to the motion of the cochlear partition to the extent that it can drive the middle ear.

[Oral health care practices in Abidjan]. / Itinéraire thérapeutique en Odonto-Stomatologie à Abidjan.

Abidjan, the economical capital of Ivory Coast has a CAO of 2.7 with index O practically nil. The professional density is one surgeon for 12.000 inhabitants. Abidjan population, despite the requirements in increasing care has not recourse to the dental surgeons for their assumption of responsibility. The general objective of our study is to describe the therapeutic itinerary in odonto-stomatology of the Abidjan population. We have realised a questionnaire survey beside of population sample. The results show that 25 per cent of our population gives up care despite the presence of pain or embarrassment. Our study has allowed highlighting all the other recourses to the care. Indeed, the people who give up the care have much other recourse which has be identified in order of importance: the modern and traditional self-medication. Let us note in our study, that the choice of dental surgeon knows a constant evolution from the first to the third recourse. The lack of financial means constitutes however the first obstacle at the accessibility to the oral care in Ivory Coast.

Responses of medial olivocochlear neurons. Specifying the central pathways of the medial olivocochlear reflex.

Medial olivocochlear (MOC) neurons project to outer hair cells (OHC), forming the efferent arm of a reflex that affects sound processing and offers protection from acoustic overstimulation. The central pathways that trigger the MOC reflex in response to sound are poorly understood. Insight into these pathways can be obtained by examining the responses of single MOC neurons recorded from anesthetized guinea pigs. Response latencies of MOC neurons are as short as 5 ms. This latency is consistent with the idea that type I, but not type II, auditory-nerve fibers provide the major inputs to the reflex interneurons in the cochlear nucleus. This short latency also implies that the cochlear-nucleus interneurons have rapidly conducting axons. In the cochlear nucleus, lesions of the posteroventral subdivision (PVCN), but not the anteroventral (AVCN) or dorsal (DCN) subdivisions, produce permanent disruption of the MOC reflex, based on a metric of adaptation of the distortion-product otoacoustic emission (DPOAE). This finding supports earlier anatomical results demonstrating that some PVCN neurons project to MOC neurons. Within the PVCN, there are two general types of units when classified according to poststimulus time histograms: onset units and chopper units. The MOC response is sustained and cannot be produced solely by inputs having an onset pattern. The MOC reflex interneurons are thus likely to be chopper units of PVCN. Also supporting this conclusion, chopper units and MOC neurons both have sharp frequency tuning. Thus, the most likely pathway for the sound-evoked MOC reflex begins with the responses of hair cells, proceeds with type I auditory-nerve fibers, PVCN chopper units, and MOC neurons, and ends with the MOC terminations on OHC.

Separate mechanical processes underlie fast and slow effects of medial olivocochlear efferent activity.

Sound-evoked vibrations of the basilar membrane (BM) in anaesthetised guinea-pigs are shown to be affected over two distinct time scales by electrical stimulation of the medial olivocochlear efferent system: one is fast (10-100 ms), the other much slower (10-100 s). For low and moderate level tones near the BM's characteristic frequency, both fast and slow effects inhibited BM motion. However, fast inhibition was accompanied by phase leads, while slow inhibition was accompanied by phase lags. These findings are consistent with a hypothesis that both fast and slow effects decrease sound amplification in the cochlea. However, the opposing directions of the phase changes indicate that separate mechanical processes must underlie fast and slow effects. One plausible interpretation of these findings is that efferent slow effects are caused by outer-hair-cell stiffness decreases, while efferent fast effects are caused by reductions in 'negative damping'.