| 1. |
- 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. |
- Bergendal, Birgitta, 1947-
(författare)
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Oligodontia and ectodermal dysplasia : on signs, symptoms, genetics and outcomes of dental treatment
- 2010
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Ingår i: Swedish dental journal. Supplement. - Umeå : Umeå universitet. - 0348-6672. ; :205, s. 13-78
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim of this thesis was to broaden our knowledge of the signs and symptoms, genetics, and outcomes of dental implant treatment in individuals with oligodontia or ectodermal dysplasia. Article I is a population-based study in three Swedish counties of 162 individuals with oligodontia, which was a prevalence of 0.09%. The intent was to explore ways for dentists to assess symptoms from other ectodermal structures than teeth through a clinical interview and chair-side analyses. Thirty per cent had low salivary secretion rates while only 11% with no known syndrome reported symptoms from hair, nails, or sweat glands. These are, together with teeth, the ectodermal structures on which it is proposed that a clinical diagnosis of ectodermal dysplasia (ED) be based. Article II screened 93 probands with oligodontia for mutations in six genes known to cause oligodontia and hypohidrotic ED. Sequence alterations predicted to be damaging or potentially damaging were revealed in the AXIN2, MSX1, PAX9, and EDARADD genes in 14 (15%) of the probands. All mutations but one were novel. For the first time, EDARADD mutations were shown to cause isolated oligodontia. No individual who had reported ectodermal symptoms from hair, nails, or sweat glands had a mutation. Article III assessed orofacial function in individuals with different types of EDs using the Nordic Orofacial Test-Screening (NOT-S) protocol. Individuals with ED scored significantly higher in orofacial dysfunction than a healthy reference sample, especially in the Chewing and swallowing, Dryness of the mouth, and Speech domains. Article IV surveyed treatment outcome of dental implants in Swedish children up to age 16 years. In a 20-year period, only 26 patients were treated, 5 of whom had hypohidrotic ED and anodontia of the mandible. Individuals with ED had 64% failed implants compared to 6% among subjects with teeth missing due to trauma or agenesis. The main conclusions of this thesis were that (i) a check of whether one or more permanent incisors are missing will identify 65% of individuals with oligodontia and 84% of individuals missing nine teeth or more, (ii) evaluation of salivary secretion is indicated in children with oligodontia, (iii) a majority of individuals with oligodontia did not report other abnormal ectodermal organ function besides teeth, (iv) no clinical indicator discriminated between individuals with and without mutations in the tested genes, and more unidentified genes are involved in tooth morphogenesis, (v) EDARADD mutations are associated with isolated oligodontia, (vi) evaluation of orofacial function is indicated in individuals with ED, and many individuals with ED would benefit from orofacial skills training, (vii) dental implant placement is a rare treatment modality in children, (viii) individuals with hypohidrotic ED seem to present special challenges due to structural as well as direct effects of the mutations on bone, which seem to compromise osseointegration, (ix) central registers on signs and symptoms in individuals with rare disorders would help establish prevalences of various diagnoses and define treatment needs, and (x) quality registers for monitoring treatment outcomes of dental implants would promote early detection of risks and side-effects in individuals with rare disorders.
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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. |
- Rosén, Linda, 1979-
(författare)
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Dental caries and background factors in children with heart disease
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Congenital heart disease (CHD) is one of the most common congenital anomalies with an incidence of approximately 8–10 cases per 1000 live births. Technical development and continuing improvement in surgical methods have led to early interventions and an increased survival and consequently also a new group of patients in dentistry. The general aim of this thesis was to study the caries prevalence and some possible background factors in children with complex CHD.Paper I examined the caries prevalence in 41 children with complex CHD and 41 healthy age- and gender-matched controls. CHD children had higher dmfs-values 5.2 ± 7.0 vs. 2.2 ± 3.5 in the controls (p < 0.05). CHD children on digoxin medication had higher dmfs values 10.1 ± 8.5 vs. 3.7 ± 5.3 in the other CHD children (p < 0.05). CHD children had received more fluoride varnish treatments and fluoride tablets (p < 0.01).Paper II investigated attitudes and experiences of dental health information and advice, dental care, and service in 33 parents of children with complex CHD and 33 parents of age- and gender-matched controls. Differences were displayed in the professional group that provided the parents with dental health information and advice, attitudes to reception at the dental clinic, and experience of sedation before operative dental treatment (p < 0.05).Paper III examined 183 Swedish general dentists’ experiences of and attitudes to dental care for children with CHD. Eighteen % of the dentists had received special education or information to treat children with CHD, while almost half of the dentists had one or more patients with CHD and a majority of them stated that their CHD patients had a caries problem. The dentists had a different opinion regarding the provision of dental treatment for children with CHD compared to the current situation (p < 0.001).Paper IV studied salivary secretion, salivary buffering capacity, viable count of bacteria (TVC), mutans streptococci (MS) and lactobacilli (LBC), calcium, chloride, magnesium, potassium, sodium, and IgA in 24 children on heart failure medication and 24 healthy controls. Seven children (29 %) had stimulated secretions below 0.5 ml/min compared to no child among the controls (p < 0.01). TVC were 1.4 × 106 ± 1.2 × 107 in the cardiac group vs. 2.7 × 106 ± 2.9 × 107 in the control group (p < 0.05). MS ratio of TVC constituted 0.11 ± 0.35 % vs. 0.01 ± 0.02 % for the controls (p > 0.05).Paper V studied the endogenous pH and titratable acidity and dissolution of calcium and phosphate from dental hard tissues by 13 pharmaceutical preparations used in paediatric cardiology. Six of the preparations had an endogenous pH below the critical value for enamel dissolution.It is concluded that (i) children with complex CHD had a higher caries experience in the primary dentition than healthy matched controls, (ii) children on digoxin medication had a higher caries experience than other children with complex CHD, (iii) children with complex CHD had received more caries prevention than healthy controls, (iv) parents of children with complex CHD were less satisfied with the reception and care they received than parents of healthy children, (v) general dentists had a different opinion regarding the provision of dental treatment to children with CHD compared to the current situation (vi) children on heart failure medication can have a low saliva secretion, (vii) pharmaceutical preparations used on long-term basis in paediatric cardiology may pose a hazardous threat to dental hard tissues due to their acidity.
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| 5. |
- Stecksén-Blicks, Christina, 1949-
(författare)
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Epidemiological studies of dental caries in groups of Swedish children
- 1986
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In a cross-sectional study the extent and distribution of dental caries was studied in 817 children, 4, 8 and 13 years old in three areas inSweden. The importance of dietary habits, sugar intake, social conditions, professional dental care, oral hygiene and the use of fluorides on caries prevalence was analyzed. In a subsample, consisting of 88 8-year-olds and 91 13-year-olds the net caries increment during aone-year period was studied.In this longitudinal study, the salivary levels of lactobacllli and S. mutans were determined and correlated to sugar intake and caries increment.The cross-sectional study showed obvious differences in caries prevalence among the studied areas. These differences could mainly be explained by variations in the age from which children had received professional dental care, frequency of tooth-brushing and the use of topical fluorides. There were no differences in dietary habits or sugar intake that could explain the differences in caries prevalence among the areas studied.Examples are given of how changes in some determinants may affect the caries prevalence by means of path analysis.The longitudinal study showed that caries Increment was higher when sugar intake and meal frequency were high (> the mean value for the age group). The highest mean caries increment was found in children with high prevalence of lactobacllli and S. mutans in the saliva combined with a high sugar intake.Groups of children with high salivary levels of both Iactobac ì II i and S. mutans developed 3-4 times more caries than other children. This relation did not always exist in the Individual case.Children with a low caries Increment during one year (0-2 surfaces) brushed their teeth more often and rinsed their mouths more frequently with fluoride solution than children with a high caries increment (> 3 surfaces). The use of fluoridated toothpaste was somewhat more common, however, in the low carles increment group only in the.8-year-oIds.The gingival status was used as a measure of oral hygiene and gingivitis scores revealed statistically significant differences between groups with a low caries increment and a high carles increment (p < 0.01, p < 0.05) in the two age groups, respectively.With the variables frequency of meals, total sugar intake, salivary level of lactobacilli and S. mutans, oral hygiene and use of topical fluorides the net caries increment during one year could be correctly predicted in 79 % of the 8-year-olds and 81 % of the 13-year-olds when the children were divided Into two groups according to their net caries increment; 0-2 surfaces and > 3 surfaces.
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