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- Hasslöf, Pamela, 1978-
(författare)
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Probiotic Lactobacilli in the context of dental caries as a biofilm-mediated disease
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The World Health Organization defines probiotics as ‘live microorganisms which, when administered in adequate amounts, confer a health benefit to the host’. Traditionally, probiotic microorganisms have been used to prevent or treat gastrointestinal tract diseases. In the last 15 years, there has been increasing interest of a possible probiotic impact on the oral microbiota and dental caries. Dental caries is a multifactorial disease, and the causative factor in the oral microbiota includes a shift from a balanced microflora to a microflora that includes more aciduric species such as mutans streptococci (MS), non-mutans streptococci, and Actinomyces. MS is considered an opportunistic pathogen although several other bacteria also contribute to the disease. Early acquisition of MS is associated with early development of caries; therefore a desirable complement to other prophylactic measures would be a MS colonization inhibitor.Objective: To better understand how selected strains of probiotic lactobacilli interact with MS in vitro and in vivo and to study the impact of probiotic lactobacilli on caries development during childhood. Material and methods: The in vitro properties of probiotic lactobacilli were studied with regard to (i) acid production from sugars and sugar alcohols, (ii) growth inhibition capacity on clinical isolates and reference strains of MS as well as Candida albicans and (iii) the capacity to co-aggregate with MS. A randomized controlled trial (RCT) tested the short-term effect of intervention with two Lactobacillus reuteri strains on MS, which was evaluated after treatment with chlorhexidine. The re-growth patterns of MS and 19 other selected strains were also evaluated. In the second clinical study we investigated the long-term effect on MS prevalence and dental caries after an intervention with Lactobacillus paracasei ssp. paracasei F19 (LF19) between 4 and 13 months of age.Results: The results from the in vitro testing showed that strains of probiotic lactobacilli differed in their fermentation patterns, inhibition capacity and their capacity to co-aggregate, which should be kept in mind in the translation to clinical research. The clinical study on short-term effects of two L. reuteri strains on MS and other oral strains showed no effect on re-growth patterns after intervention. The clinical study on long-term effects of LF19 showed no effect on the prevalence of MS. Furthermore, the clinical follow-up at 9 years of age showed no differences in either decayed, missing, and filled surface (dmfs) or DMFS between the probiotic and placebo groups. Evaluation of saliva samples showed no signs of oral colonization with LF19 in the study group.Conclusion: The in vitro testing showed potentials of the selected probiotic Lactobacillus strains for interference with MS and C. albicans. The results from the clinical studies showed no such effect on MS or dental caries. Evidence regarding the effectiveness of specific probiotic applications in the prevention of dental caries is limited and does not allow for conclusions concerning the use of probiotic bacteria as a preventive measure.
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| 2. |
- Engström, Kristina, 1963-
(författare)
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Fluoride concentration in plaque and saliva and its effects on oral ecology after intake of fluoridated milk
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- According to WHO, the addition of fluoride to milk could be considered as an alternative to water fluoridation for community-based caries prevention in childhood. School-based schemes in developing as well as industrial countries have demonstrated substantial benefits on oral health, but there are limited data available on the local events in the oral cavity after consumption of fluoridated milk. The general aim of the present investigations was to investigate the concentration of fluoride obtained in saliva and dental plaque after ingestion of Fmilk and to explore the possible effects on the oral ecology. A series of controlled studies were performed in vivo in which samples of saliva and dental plaque were collected and analysed with respect to fluoride content, microbial composition and acidogenicity. An in vitro study evaluated the effect on enamel lesion formation. In paper I, significantly increased concentrations of fluoride (p<0.05) were disclosed in saliva 15 minutes after drinking the fluoride-containing water or milk. In the plaque samples however, the F-increase remained significantly elevated still after 2 hours. The availability of fluoride from milk was generally somewhat lower than from water but the differences were not statistically significant in either plaque or saliva. In paper II, the fluoride concentration in plaque was further explored after a single intake or habitual consumption of fluoridated milk together with a regular meal. The results showed that cariesinhibiting levels of fluoride persisted up to 4 hours after intake. There were no significant differences between the single intakes when compared with repeated intakes. In paper III, the influence of fluoridated milk on the salivary microorganisms associated with dental caries was evaluated. No significant alterations of the microflora were found compared with baseline. There was a slight reduction in the proportion of mutans streptococci after 2 and 4 weeks during consumption with fluoridated milk but the difference failed to reach statistical significance. In paper IV it was demonstrated that fluoridated milk significantly (p<0.05) could counteract the lactic acid formation in dental plaque as initiated with sucrose. In paper V, laser fluorescence technique was used to monitor the effect of fluoridated milk on enamel lesion formation in an experimental caries model. The results reinforced previous research and showed a hampering effect of fluoridated milk. No side effects were reported in any of the investigations. The findings of this thesis substantiate that milk is a suitable vehicle for fluoride administration and contribute to the understanding and possible explanations for the anti-caries properties of fluoridated milk. The main conclusions were: a) intake of fluoridated milk resulted in significantly elevated fluoride levels in saliva within the first 15 minutes and up to 4 hours in dental plaque when fluoridate milk was consumed together with meal, b) no significant alteration of the salivary microflora was disclosed after habitual intake of fluoridated milk but a delayed carbohydrate-mediated lactic acid formation in suspensions of dental plaque could be demonstrated, c) the fluoride concentrations in plaque were not negatively influence by the food intake, and d) the in vitro findings advocated that fluoride added to milk reduced enamel lesion formation as assessed by laser fluorescence technique in an experimental caries model.According to WHO, the addition of fluoride to milk could be considered as an alternative to water fluoridation for community-based caries prevention in childhood. School-based schemes in developing as well as industrial countries have demonstrated substantial benefits on oral health, but there are limited data available on the local events in the oral cavity after consumption of fluoridated milk. The general aim of the present investigations was to investigate the concentration of fluoride obtained in saliva and dental plaque after ingestion of Fmilk and to explore the possible effects on the oral ecology. A series of controlled studies were performed in vivo in which samples of saliva and dental plaque were collected and analysed with respect to fluoride content, microbial composition and acidogenicity. An in vitro study evaluated the effect on enamel lesion formation. In paper I, significantly increased concentrations of fluoride (p<0.05) were disclosed in saliva 15 minutes after drinking the fluoride-containing water or milk. In the plaque samples however, the F-increase remained significantly elevated still after 2 hours. The availability of fluoride from milk was generally somewhat lower than from water but the differences were not statistically significant in either plaque or saliva. In paper II, the fluoride concentration in plaque was further explored after a single intake or habitual consumption of fluoridated milk together with a regular meal. The results showed that cariesinhibiting levels of fluoride persisted up to 4 hours after intake. There were no significant differences between the single intakes when compared with repeated intakes. In paper III, the influence of fluoridated milk on the salivary microorganisms associated with dental caries was evaluated. No significant alterations of the microflora were found compared with baseline. There was a slight reduction in the proportion of mutans streptococci after 2 and 4 weeks during consumption with fluoridated milk but the difference failed to reach statistical significance. In paper IV it was demonstrated that fluoridated milk significantly (p<0.05) could counteract the lactic acid formation in dental plaque as initiated with sucrose. In paper V, laser fluorescence technique was used to monitor the effect of fluoridated milk on enamel lesion formation in an experimental caries model. The results reinforced previous research and showed a hampering effect of fluoridated milk. No side effects were reported in any of the investigations. The findings of this thesis substantiate that milk is a suitable vehicle for fluoride administration and contribute to the understanding and possible explanations for the anti-caries properties of fluoridated milk. The main conclusions were: a) intake of fluoridated milk resulted in significantly elevated fluoride levels in saliva within the first 15 minutes and up to 4 hours in dental plaque when fluoridate milk was consumed together with meal, b) no significant alteration of the salivary microflora was disclosed after habitual intake of fluoridated milk but a delayed carbohydrate-mediated lactic acid formation in suspensions of dental plaque could be demonstrated, c) the fluoride concentrations in plaque were not negatively influence by the food intake, and d) the in vitro findings advocated that fluoride added to milk reduced enamel lesion formation as assessed by laser fluorescence technique in an experimental caries model.
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| 3. |
- Lif Holgerson, Pernilla, 1972-
(författare)
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Xylitol and its effect on oral ecology : clinical studies in children and adolescents
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Xylitol, classified as a natural sugar substitute, has for about 35 years been known as an agent that may act against caries. The mechanism of action; how it inhibits mutans streptococci (MS) and the clinical dose-response relationship are not however fully investigated. The general aim of the investigations was to evaluate the effect of xylitol on oral ecology in children and adolescents. A series of experimental and controlled clinical trials were performed in which samples of saliva and plaque was collected and analysed with respect to xylitol content, pH, microbial composition and lactic acid production. In paper I, significantly reduced proportions of xylitol-sensitive MS in saliva were demonstrated after 18 weeks of regular use of two dose regimens of xylitol-containing tablets (1.7g and 3.4g xylitol/day) but the acidogenicity in dental plaque was not affected. In paper II, the effect on interdental plaque-pH of two different single dose intakes (2.0g and 6.0g) of xylitol was evaluated. The higher xylitol dose counteracted the pH-drop significantly (p<0.05) when the chewing was followed by a sucrose rinse while the lower dose did not differ from the control. In paper III, the xylitol concentrations in saliva after use of different common xylitol-containing products (0.1g-1.3g) were investigated. Statistically significant elevations of salivary xylitol levels were demonstrated for all products during the first 8-16 min when compared with baseline (p<0.05) but the individual variation was considerable. In samples of supragingival dental plaque, a high dose rinse (6.0g) increased the xylitol concentrations for a longer period (>30 min) than a low dose rinse (2.0g). In paper IV, it was demonstrated that 6.0g of xylitol in chewing gums, every day in 4 weeks, gave significantly less visible plaque and a significantly reduced sucrose-induced lactic acid formation (p<0.05) in saliva. Furthermore, the proportion of MS decreased significantly (p<0.05) compared to baseline. In paper V, the salivary uptake of [14C]-xylitol was compared with a specific assay determining xylitol-sensitive MS and a fair positive correlation (p<0.05) between the two assays was found. In a controlled trial, the proportions of MS and the salivary xylitol uptake decreased significantly (p<0.05) in the xylitol gum test group after 4 weeks compared to baseline which was in contrast to the control gum group. No serious adverse effects were reported in any of the investigations. The main conclusions from this thesis were: a) various xylitol-containing products increased the xylitol levels in saliva and plaque, b) 6.0g of xylitol could counteract the interdental pH-drop after sugar consumption and reduce lactic acid formation in saliva c) a daily dose of 6.0g xylitol reduced the amount of visible plaque and altered the salivary microbial composition, d) a transient shift of MS strains in saliva was demonstrated during periods of regular intake of xylitol products but no long-term impact was found after its termination. The relatively high amount of xylitol needed for a beneficial effect on the oral ecology calls for a further development of effective and safe routes for administration.
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| 4. |
- Sundell, Anna Lena, 1970-
(författare)
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Children with orofacial clefts : dental caries and health-related quality of life
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background. The current understanding on caries and enamel developmental defects prevalence and frequency, caries risk, health-related quality life (HRQoL) and stress response in young children with cleft lip and/or palate (CL/P) are sparse. In this thesis these aspects were investigated in 5- and 10- year-old children with CL/P in comparison to non-cleft children in the same ages.Design. The studies in this thesis have a cross-sectional case-control design. Participants. The study group consisted of 139 children with CL/P (80 children aged 5 years and 59 aged 10 years) and 313 non-cleft controls (144 children aged 5 years and 169 aged 10 years).Method. Caries was scored according to International Caries Detection and Assessment System (ICDAS II) and developmental enamel defects were measured as presence and frequency of hypoplasia and hypomineralization. Oral hygiene was assessed using Quigley-Hein plaque index. Stimulated saliva samples were analyzed for mutans streptococci, lactobacilli, buffering capacity and secretion rates. Information regarding children’s oral hygiene routines, dietary habits and fluoride exposure were collected with questionnaires. Caries risk was evaluated with algorithm-based software, Cariogram while HRQoL was perceived with KIDSCREEN-52. Stress response was analyzed with cortisol concentration in saliva at three different time points using a commercial competitive radioimmunoassay.Results. Caries prevalence (36% versus 18%) and caries frequency (1.2 dmfs versus 0.9 dmfs) was significantly higher in 5-year-old children with CL/P in comparison to non-cleft controls. In 10-yearolds no significant difference was found between children with CL/P and non-cleft controls in caries prevalence (47% versus 38%) or in caries frequency (0.7 DMFS versus 0.5 DMFS). Children with CL/P had significantly higher prevalence of enamel defects, higher counts of salivary lactobacilli and less good oral hygiene. The odds of being categorized with high caries risk were elevated in children with CL/P. Children with CL/P had similar HRQoL and salivary cortisol concentrations as non-cleft controls. However, 10-year-old boys with CL/P had significantly higher cortisol concentrations in the evening than non-cleft boys.Conclusions. Preschool children with CL/P seem to have more caries in the primary dentition than non-cleft controls. Children with CL/P had increased odds of being categorized as high caries risk individuals compared to controls. Some of the contributing factors seem to be higher prevalence of enamel defects, impaired oral hygiene and elevated salivary lactobacilli. Furthermore, as measured with the help of cortisol concentrations in saliva, children with CL/P were not more stressed than noncleft controls and their HRQoL was comparable to a European norm population. It appears that regular comprehensive preventive oral care in children with CL/P is effective in preventing caries development in permanent teeth. However, children with CL/P are at risk of caries development and preventive oral care should be implemented and started earlier than today.
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