Magister Public Health - MPH / Background: Dental canes and gingivitis are reported to affect 60-90% of school children in most countries (World Health Organization, 2003). Learners in the Swakopmund district of Namibia were examined and it was found that 73% and 89% of them were affected by dental caries and gingivitis respectively (Ministry of Health and Social Services, 2003). This district has implemented an oral health programme at primary schools with the aim of reducing the prevalence of dental caries and gingivitis. Aim: To compare knowledge, attitudes and behaviour of teachers and learners in response to the school-based oral health programme at four primary schools in Swakopmund district. Study Design: This study is a cross-sectional survey that compared the responses of learners from high participating schools to those from low participating schools. The total sample was 186 participants comprising of 159 learners and 27 teachers. Data Collection: Structured, self-administered questionnaires were used for the teachers whilst learners were interviewed by the researcher and research assistants using structured questionnaires. Data on knowledge of risk factors for dental caries and gingivitis as well as attitude and behaviour towards prevention of these diseases at school were collected. Data analysis: Data were captured in Microsoft Excel Programme and imported to CDC Epi Info 2002 version 3.3 for analysis. Prevalence ratio (PR) was used as a preferable measure of effect at 95% confidence interval. Chi-square test was used to assess statistical significance of the proportional differences between high and low participating schools and the cut off point for statistical significance was a p-value < 0.05. 111 Results: Learners from low participating schools were more knowledgeable than learners from high participating schools in most of the knowledge questions and the results were statistically significant. There were positive oral health practices and attitudes reported by the learners with minimal differences between high participating and low participating schools and consequently the results were not statistically significant. The results for the variables knowledge, behaviour and attitudes for the teachers were not statistically significant. Teachers from both high and low participating schools exhibited high levels of knowledge and positive oral health behaviours and attitudes. However, teachers reported some shortcomings in the programme which included lack of: toothbrushes, parental involvement, time for oral health activities, regular workshops and educational materials. Conclusion: The study revealed that learners and teachers from both high and low participating schools had positive oral health knowledge, attitudes and behaviour towards oral health. However, certain socio-environmental factors which are important determinants of oral health could explain the reasons for low participation in oral health programme by some schools. Therefore the Health Promoting Schools approach is a pragmatic way to promote oral health at schools in Swakopmund district because a Health Promoting School has a healthy public policy that creates a supportive environment for oral health, making healthy choices easier.

Tusentals människor tvingas fly sina hemländer på grund av bland annat krig, förföljelse och våld. Under 2015 migrerade 60 miljoner vuxna och barn och ungdomar under 18 år. Syfte: Att beskriva den orala hälsan hos flyktingbarn. Metod: Allmän litteraturstudie. Litteratursökningen utfördes i tre databaser: CINAHL, DOSS och MEDLINE. Totalt valdes 16 vetenskapliga artiklar som var publicerade mellan åren 2014–2023. Resultat: Resultatet visar att de mest förekommande orala sjukdomarna bland flyktingbarn är karies och gingivit. Riskfaktorer för den orala hälsan identifieras som tillgång till tandvård och munhygienartiklar, socioekonomisk status och kost. Barn på flykt under en längre tid anses vara mer benägna att ha högre antal kariesskador jämfört med de motsvarande barnen på flykt under en kortare tid. Slutsats: Karies och gingivit är de mest förekommande orala sjukdomarna hos flyktingbarn. Riskfaktorerna som svårigheter med tillgång till tandvård och munhygiensartiklar, kost och socioekonomisk status är vanligt förekommande vilket påverkar förekomsten av karies och gingivit. / Thousands of people are forced to flee their home countries because of war, persecution and violence. In 2015, 60 million adults, children and adolescents under the age of 18 emigrated. Aim: To describe the oral health of refugee children. Method: Literature review. The literature search was performed in three databases. 16 scientific articles were selected that were published between 2014-2023. Results: The results show that the most prevalent oral diseases among refugee children are caries and gingivitis. Risk factors for oral health are identified as access to dental care and oral hygiene items, socioeconomic status and diet. Children on the move for a longer period of time are considered to be more likely to have higher rates of dental caries compared to their counterparts on the move for a shorter period of time. Conclusion: Dental caries and gingivitis are the most common oral diseases in refugee children. Risk factors such as difficulties in accessing dental care and oral hygiene products, diet and socioeconomic status are common and influence the prevalence of caries and gingivitis.

Tesis por compendio / [ES] Se ha estimado que obtenemos más de las tres cuartas partes del nitrato que ingerimos de la fruta y la verdura. Los vegetales ricos en nitratos incluyen verduras de hoja verde y ciertos tubérculos (p. ej., remolachas y rábanos). Las glándulas salivales concentran activamente el nitrato plasmático, lo que da lugar a concentraciones elevadas de nitrato en la saliva (5 a 8 mM) después de una comida rica en nitratos. El nitrato es un factor ecológico que puede inducir cambios rápidos en la estructura y función de las comunidades polimicrobianas. Sin embargo, los efectos sobre la microbiota oral no se han estudiado en detalle, mientras que un número limitado de estudios previos a esta tesis indican que es probable que el nitrato sea beneficioso para la salud bucal. El objetivo de esta tesis es, por tanto, estudiar los cambios microbiológicos inducidos por nitratos e identificar posibles mecanismos de homeostasis generados por este compuesto, con el fin de determinar si el nitrato puede considerarse un prebiótico para la salud bucal. Un segundo objetivo fue aislar cepas reductoras de nitrato y probar su potencial probiótico in vitro. En el capítulo 1, se realizó un estudio in vitro para testar el efecto del nitrato 6,5 mM en comunidades orales cultivadas a partir de la saliva de 12 individuos sanos. En el capítulo 2, se obtuvieron 53 aislados de bacterias reductoras de nitrato y se probó el efecto de seis candidatos a probióticos en comunidades orales sanas cultivadas a partir de saliva de diferentes donantes con o sin nitrato 6,5 mM. En el capítulo 3, se estudió el efecto de un extracto de remolacha rico en nitrato sobre la acidificación oral después de un enjuague con azúcar en 24 individuos sin caries activas. Se tomaron sobrenadantes (capítulos 1 y 2) o muestras de saliva (capítulo 3) para mediciones de nitrato, nitrito, amonio, lactato y pH. Además, la composición bacteriana de la biopelícula in vitro y del pellet salivar se determinó usando secuenciación Illumina del rRNA 16S y/o qPCR del género nitratorreductor Rothia. Los datos demuestran que el nitrato estimula el crecimiento de los géneros beneficiosos Rothia y Neisseria en nuestro modelo in vitro, mientras que potencialmente disminuye las bacterias asociadas a la caries, la halitosis y la enfermedad periodontal. Además, los datos in vitro e in vivo presentados en esta tesis indican que el nitrato puede limitar o prevenir caídas de pH cuando los azúcares son fermentados por la microbiota oral, un mecanismo de resiliencia que podría ser estimulado por el consumo de extractos vegetales ricos en nitratos. Los principales mecanismos de amortiguación del pH por parte del nitrato son el uso de acido láctico durante la desnitrificación (observado tanto in vivo como in vitro) y durante la reducción de nitrito a amonio, así como la producción potencial de amoníaco (observado in vitro). En esta tesis, los efectos del nitrato se observaron después de períodos cortos, es decir, después de 5-9 h de incubación in vitro y 1-4 horas después de la ingesta del suplemento de nitrato in vivo. Los estudios futuros deberían centrarse en los efectos longitudinales de la ingesta diaria de nitratos. En el capítulo 2, se aislaron bacterias reductoras de nitrato pertenecientes a los géneros Rothia y Actinomyces. Una selección de aislados de Rothia aumentó el uso de lactato y la capacidad de reducción de nitratos de las comunidades bucales, lo que potencialmente beneficiaría la salud dental y la salud sistémica, respectivamente. Los datos in vitro e in vivo presentados en esta tesis sugieren que el nitrato puede modular la microbiota oral en aspectos que son beneficiosas para el huésped y, por lo tanto, podría considerarse una sustancia prebiótica para la microbiota oral. Además, los aislados reductores de nitratos pueden estimular los efectos beneficiosos del metabolismo del nitrato, sobre todo en personas con bajos niveles de estas bacterias. / [CA] S'ha estimat que obtenim més de les tres quartes parts del nitrat que ingerim de la fruita i la verdura. Els vegetals rics en nitrats inclouen verdures de fulla verda i uns certs tubercles (p. ex., remolatxes i raves). Les glàndules salivals concentren activament el nitrat plasmàtic, la qual cosa dona lloc a concentracions elevades de nitrat a la saliva (5 a 8 mm) després d'un menjar ric en nitrats. El nitrat és un factor ecològic que pot induir canvis ràpids en l'estructura i funció de les comunitats polimicrobianes. No obstant això, els efectes sobre la microbiota oral no s'han estudiat detalladament, mentre que un nombre limitat d'estudis previs a aquesta tesi indiquen que és probable que el nitrat siga beneficiós per a la salut bucal. L'objectiu d'aquesta tesi és, per tant, estudiar els canvis microbiològics induïts per nitrats i identificar possibles mecanismes d'homeòstasi generats per aquest compost, amb la finalitat de determinar si el nitrat pot considerar-se un prebiòtic per a la salut bucal. Un segon objectiu va ser aïllar soques reductores de nitrat i provar el seu potencial probiòtic in vitro. En el capítol 1, es va realitzar un estudi in vitro per a testar l'efecte del nitrat 6,5 mm en comunitats orals cultivades a partir de la saliva de 12 individus sans. En el capítol 2, es van obtindre 53 aïllats de bacteris reductors de nitrat i es va provar l'efecte de sis candidats a probiòtics en comunitats orals sanes cultivades a partir de saliva de diferents donants amb o sense nitrat 6,5 mm. En el capítol 3, es va estudiar l'efecte d'un extracte de remolatxa ric en nitrat sobre l'acidificació oral després d'un glopeig amb sucre en 24 individus sense càries actives. Es van prendre sobrenadants (capítols 1 i 2) o mostres de saliva (capítol 3) per a mesuraments de nitrat, nitrit, amoni, lactat i pH. A més, la composició bacteriana de la biopel·lícula in vitro i del pèl·let salivar es va determinar usant seqüenciació Illumina del RNAr 16S i/o qPCR del gènere nitratorreductor Rothia. Les dades demostren que el nitrat estimula el creixement dels gèneres beneficiosos Rothia i Neisseria en el nostre model in vitro, mentre que potencialment disminueix els bacteris associats a la càries, l'halitosi i la malaltia periodontal. A més a més, les dades in vitro i in vivo presentades en aquesta tesi indiquen que el nitrat pot limitar o previndre caigudes de pH quan els sucres són fermentats per la microbiota oral, un mecanisme de resiliència que podria ser estimulat pel consum d'extractes vegetals rics en nitrats. Els principals mecanismes d'amortiment del pH per part del nitrat són l'ús de àcid làctic durant la desnitrificació (observat tant in vivo com in vitro) i durant la reducció de nitrit a amoni, així com la producció potencial d'amoníac (observat in vitro). En aquesta tesi, els efectes del nitrat es van observar després de períodes curts, és a dir, després de 5-9 h d'incubació in vitro i 1-4 hores després de la ingesta del suplement de nitrat in vivo. Els estudis futurs haurien de centrar-se en els efectes longitudinals de la ingesta diària de nitrats. En aquesta tesi es van aïllar bacteris reductors de nitrat pertanyents als gèneres Rothia i Actinomyces. Una selecció d'aïllats de Rothia va augmentar l'ús de lactat i la capacitat de reducció de nitrats de les comunitats bucals, la qual cosa potencialment beneficiaria la salut dental i la salut sistèmica, respectivament. Les dades in vitro i in vivo presentats en aquesta tesi suggereixen que el nitrat pot modular la microbiota oral en aspectes que són beneficiosos per a l'hoste i, per tant, podria considerar-se una substància prebiòtica per a la microbiota oral. A més, els aïllats reductors de nitrats poden estimular els efectes beneficiosos del metabolisme del nitrat, sobretot en persones amb baixos nivells d'aquests bacteris. El nitrat i els bacteris reductors de nitrat són, per tant, components prometedors per a futurs productes de salut oral. / [EN] It has been estimated that we obtain over three quarters of dietary nitrate from vegetables and fruits. Nitrate-rich vegetable types include leafy greens and certain root vegetables (e.g., beetroots and radishes). The salivary glands actively concentrate plasma nitrate, leading to high salivary nitrate concentrations (5-8 mM) after a nitrate-rich meal. Nitrate is an ecological factor that can induce rapid changes in structure and function of polymicrobial communities. However, the effects on the oral microbiota have not been clarified, whilst a limited number of previous studies did indicate that nitrate is likely to be beneficial for oral health. The aim of this thesis was therefore to study nitrate-induced microbiome changes and identify potential mechanisms for nitrate-induced homeostasis, in order to determine if nitrate can be considered a prebiotic compound for oral health. A second aim was to isolate nitrate-reducing isolates and test their probiotic potential in vitro. In chapter 1, an in vitro study was set up testing the effect of 6.5 mM nitrate on oral communities grown from saliva of 12 healthy individuals. In chapter 2, fifty-three nitrate-reducing isolates were obtained and the effect of six probiotic candidates was tested on healthy oral communities grown from saliva of different donors with or without 6.5 mM nitrate. In chapter 3, the effects of nitrate-rich beetroot extracts on oral acidification after sugar rinsing was tested in 24 individuals without active caries. Supernatants (chapters 1 and 2) or saliva samples (chapter 3) were taken for nitrate, nitrite, ammonium, lactate and pH measurements. Additionally, the bacterial composition of in vitro biofilms and salivary pellets were determined using 16S rRNA gene Illumina sequencing and/or qPCR of the nitrate-reducing genus Rothia. We showed that nitrate stimulates the growth of the beneficial genera Rothia and Neisseria in our in vitro model, while potentially decreasing caries-, halitosis- and periodontal disease-associated bacteria. Additionally, the in vitro and in vivo data presented in this thesis indicate that nitrate can limit or prevent pH drops when sugars are fermented by the oral microbiota - a mechanism of resilience that could be stimulated by the consumption of nitrate-rich vegetable extracts. The main pH buffering mechanisms of nitrate were lactic acid usage during denitrification (observed both in vivo and in vitro) and during the reduction of nitrite to ammonium, as well as the potential production of ammonia (observed in vitro). In this thesis, the effects of nitrate were observed after short periods, i.e., after 5-9 h incubation in vitro and/or after 1-4 hours after nitrate supplement intake in vivo. Future studies should focus on the longitudinal effects of daily nitrate intake. In chapter 2, nitrate-reducing species belonging to the genera Rothia and Actinomyces were isolated. A selection of Rothia isolates increased lactate usage and nitrate reduction capacities of oral communities, potentially benefitting dental health and systemic health, respectively. The in vitro and in vivo data presented in the current thesis suggest that nitrate can modulate the oral microbiota in ways that are beneficial for the host and could thus be considered a prebiotic substance for the oral microbiota. Additionally, nitrate-reducing isolates can stimulate certain beneficial effects of nitrate metabolism. Nitrate and nitrate-reducing bacteria are thus promising components for future oral care products to prevent or treat oral diseases and this should be further investigated. / Rosier, BT. (2022). Nitrate as a Prebiotic and Nitrate-Reducing Bacteria as Probiotics for Oral Health [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181578 / TESIS / Compendio

Magister Chirurgiae Dentium - MChD / Purpose: To assess the oral health status of 4-15-year-old schoolchildren in the Western Region of the Eastern Cape Province, by determining the prevalence of dental caries, periodontal disease, dental fluorosis, malocclusion and oral mucosal lesions and to create baseline data for planning oral health services in this region. Materials and Methods: The prevalent analytic survey was undertaken on 822 schoolchildren between the ages of 4-15 years in 27 different schools. The sample size selected for this region by the Department of Statistics, University of Pretoria, for the National Oral Health Survey of 1999/2000 was used. The data on 209, 210, 209 and 194 scholars in the 4-5, 6, 12 and 15-year-old age groups respectively were collected. The World Health Organization's (1997) criteria were used to determine the prevalence of caries, periodontal treatment needs, the dental fluorosis, malocclusion and prevalence of oral mucosal lesions. Six calibrated and trained examiners recorded the data on a survey form. The WHO survey forms were used for data collection. The data were analysed and processed by the author on Microsoft Excel 2000. Results: The sample size consisted of 1.35 % Asian, 51.89 % Black, 26.07 % Coloured and 20.06 % White scholars. Nearly equal amounts of males (48.3 %) and females (51.7%) were examined. The dental caries prevalence in the primary dentition of 4-5-year-olds with an average age of 4.43 years was 40.67%, with a mean dmft of 3,56. The dental caries prevalence in the permanent dentition of6-, 12- and 15-year-oldage groups was 67.62%, 46.05% and 67.92% respectively. The mean DMFT for 6-, 12- and 15 year olds were 0.05, 1.19 and 2.02 respectively. Gender differences and differences in prevalence of dental caries between the populations groups were recorded. The Coloured children experienced the highest dental caries prevalence. In the 4-5- and 15-year-old groups the males were affected more than the females by dental caries. Prevalent differences were recorded between rural and urban areas in the same population group. The prevalence of periodontal disease in 373, 12-15-year-olds was 79.09%. Only 4.02 % were in need of dental hygiene instructions and polishing. Dental education, dental hygiene instructions, dental scaling and polishing were needed by 75.07% of the children. Dental fluorosis prevalence in 450, 6-15-year-olds was 13.03%. Dental fluorosis did not affect 86.97% of the scholars; 10.63% had mild fluorosis and 2.05% was severely affected. The mean fluoride concentration in the drinking water in this region were 1.07 mgIL, ranging between 0.3-3 mgIL. Definite malocclusion was recorded in only 0.48% of the 12-year-old group, whom needed elective treatment. In the 12-year-olds, 99.52% needed no or slight treatment for no or minor malocclusions. The majority of children had no oral mucosal lesions (91.55%). The prevalence of oral mucosal lesions was 8.5% in this survey. The most frequent conditions were traumatic lesions (1.96%), dento-alveolar abscess (1.22%) and herpes labialis (1.22%). The intra-examiner reliability for caries, dental fluorosis, periodontal treatment needs and prevalence of malocclusions was 97.66%, 100%, 88.89% and 86.67% respectively. The inter-examiner reliability was 98.75%, 98.34%, 100%, 100% and 100% respectively for the five examiners. Conclusion: This survey indicated a higher prevalence of dental caries in the primary dentition (63.48%), than the permanent dentition (41.3%). The mean dmft was 3.65 and the DMFT 1.2, which indicated a low mean caries experience for these children. The WHO goal for the year 2000 for the 6-year-olds of 50% being caries free has not reached for only 32.56% were caries free. The mean DMFT of 1.2 for 12-year-olds in this survey is below the WHO goal of a mean DMFT of 1.5 or less. The lack of available preventative service provision, were ) indicated by the low percentage of fissure sealants (2.8%). The need for dental treatment was highlighted by the need mostly for one-surface restorations. Preventative treatment, two-surface fillings and extractions were also needed. Periodontal disease was a major public oral health concern for this region for a prevalence of 79.09% was recorded for the 12-15-year-olds. The majority of the children affected by periodontal disease (75.07%) were in need of professional cleaning and calculus removal. The prevalence of dental fluorosis was 8.2%, 19.87% and 13.05% for 6-, 12- and IS-year age groups respectively. The prevalence of malocclusion was 0.48% for the 12-year-old group. The prevalence of oral mucosa lesions was 8.5% for 4-15-year-old schoolchildren. Therefore, the conclusion can be made that dental fluorosis; malocclusions and oral mucosal lesions were no public concern in this region. The major public oral health concerns were dental caries in the primary dentition and periodontal disease in all age groups. Recommendations: Dental services in this region should be directed towards prevention of dental caries in the primary dentition and periodontal disease in all age groups. The focus of dental services should be primarily on preventative programs and treatments. The public dental treatments needs indicated in this survey, namely scaling and polishing, restorations and extractions, consists of the primary health care package delivery. Currently, no evaluation tool exists to monitor the efficiency of oral health programs, no baseline data for the Province exists. Therefore, the urgent need for dental research and oral health service planning and delivery are recommended.