Monographs in Oral Science最新文献

The systemic administration of antibiotics in conjunction with mechanical biofilm disruption results in reduced numbers of subgingival periodontal pathogens and improved clinical outcomes. Penicillins, tetracyclines, macrolides, quinolones, and nitroimidazoles were used in laboratory and clinical studies. The current literature was reviewed and studies investigating the effect of antibiotics on periodontal pathogens in biofilm models or in clinical trials were analyzed. While there is only a limited number of in vitro studies, numerous clinical studies reported microbiological outcomes. The combination of amoxicillin and metronidazole seems to provide superior antimicrobial effects when used in biofilm models or in clinical trials. In vitro studies using biofilm models showed that antibiotics alone have only limited effects on the bacterial load in biofilms but might be effective in reducing specific species. These results imply that mechanical biofilm disruption is indicated to allow antibiotics to be effective. Clinical trials also demonstrated that the combination therapy of amoxicillin and metronidazole might result in more superior microbiological effects than amoxicillin or metronidazole alone. The results of clinical studies investigating azithromycin are contrary. While it seems to be appropriate to use in chronic periodontitis (comparable to the new classification: stage 3 or 4, grade B generalized periodontitis), there was no superior effect observed in aggressive periodontitis (comparable to the new classification: stage 3 or 4, grade C generalized periodontitis). Doxycycline cannot be recommended for chronic periodontitis (stage 3 or 4, grade B) patients. Antibiotics as drugs come with side effects. Common adverse effects of antibiotics are opportunistic yeast infection and gastrointestinal complications (e.g., nausea, diarrhea, and colitis). The development of resistance suggests a role for microbiological analysis and antibiotic susceptibility testing in the selection of systemic periodontal antibiotic therapy.

The intraoral biofilm requires mechanical removal due to its physical properties. When exposed to the biofilm, interdental areas need special devices to be used. The most effective ones and the first choice are interdental brushes. However, they may not be adequate in the case of very narrow interdental spaces. Despite the difficulties in handling, dental floss may have some advantage in subgingival cleaning. Data are present for gingivitis and periodontitis, but almost no information has been published on gingivally healthy individuals. With respect to interdental caries there is evidence that floss only has a protective value when used professionally and without sufficient fluoridation. There are no such data available on interdental brushes.

The pH value of a biofilm influences the pathogenesis and therapy of oral diseases such as caries and periodontitis. This study aimed to investigate the influence of different initial pH values on the microbial composition, bacterial counts, metabolic activity, and quantity of three defined biofilms representing oral health, caries, and periodontal disease. Respective bacterial suspensions in the nutrient broth were initially adjusted to pH values between 5 and 8. Then biofilms were cultured on polystyrene surfaces coated with a proteinaceous solution for 2 h ("healthy" biofilm), 6 h ("healthy," and "cariogenic" biofilms), 24 h ("cariogenic," and "periodontitis" biofilms), and 48 h ("periodontitis" biofilm). In all biofilms, total bacterial counts were lower at an initial pH of 5 or 5.5 than at higher pH values. In the biofilm representing caries, the percentage of cariogenic bacteria (Streptococcus mutans, S. sobrinus, Lactobacillus acidophilus) was higher at a low pH, the metabolic activity was highest at pH 6-6.5, and biofilm mass was greatest at pH 7-7.5. In the biofilm representing periodontitis, the percentage of Porphyromonas gingivalis increased with the pH. Also, the metabolic activity was highest at pH 8, whereas mass had the highest value at pH 7. In conclusion, the initial pH value influences biofilm formation. In particular, metabolic activity and the amount of bacteria associated with disease correlated with the respective pH known to be of importance in the development of caries (relatively low pH) and periodontitis (higher pH). Modifying the pH level in oral biofilms might be an alternative concept in (primary) prevention and treatment, not only of caries but also of periodontitis.

Caries is a complex microbial disease characterized by a multifactorial etiology. The disease is driven by cariogenic microbiota that metabolize dietary carbohydrates into acids, creating prolonged periods of low pH on the biofilm surrounding the teeth, which will result in loss of calcium from the teeth leading to carious lesions. Caries remains a major public health problem globally, ranking first for the decay of permanent teeth (2.3 billion people) and 12th for deciduous teeth (560 million children) according to the Global Burden of Disease study by the WHO in 2015. Different factors play a role in the development of the disease: (i) individual factors such as tooth morphology, saliva, and the oral microbiome, (ii) behavioral factors such as frequency and amount of fermentable carbohydrates in the host's diet and overall oral hygiene, and (iii) socioeconomic status and host genetics as well as modifying factors such as fluoride. Various models exist which explain the transition from a health-compatible oral microbiota to a cariogenic microbiota. Longitudinal studies may increase our knowledge of the oral microbial compositions in different age groups by analyzing the temporal sequence leading to carious lesions. Understanding the factors which control microbial colonization early in life as well as the keystone species that should be present or absent may provide us with strategies for the acquisition and maintenance of a health-promoting oral microbiome. Thus, the importance lies in understanding caries etiology to improve strategies for diagnosis, risk assessment, prevention, and (operative) treatment.

The activity of mouthwash ingredients used in daily oral care (chlorhexidine digluconate, benzalkonium chloride, povidone iodine solution, tea tree oil) and of nystatin was evaluated not only on planktonic Candida albicans or C. glabrata, but also on the inhibition of biofilm formation. A microbroth dilution technique was used to determine the minimum inhibitory concentration of the substances against two laboratory strains and seven clinical isolates. Furthermore, a potential inhibition of biofilm formation of C. albicans or C. glabrata (single-species biofilm or mixed with two oral bacteria) was assessed. The results showed an activity of all tested substances against all C. albicans and C. glabratastrains. In the biofilm assays, a concentration-dependent effect of the substances was visible. However, a low concentration of povidone iodine solution and in particular of benzalkonium chloride seemed to increase the virulence of C. albicans. Most test substances affected both bacteria and yeasts in the mixed biofilms, only nystatin predominately reduced the yeasts. In conclusion, nystatin might be the drug of choice when exclusively preventing the colonization of Candida sp. in biofilms. The alternatives, benzalkonium chloride, povidone iodine solution, and tea tree oil, should be investigated further.

Behavioral change is one of the proposed interventions to address concerns regarding dental caries and erosive tooth wear. The impact of these interventions, however, is difficult to measure, and they are rarely considered in clinical studies. This chapter briefly discusses behavior having a genetic origin and describes several pathways that should be targeted for future studies.

Biofilm formation depends on many factors, one of them being the surface (substrate) on which the biofilm is formed, and dental restorative materials are such substrates. Biofilms play a crucial role for caries formation and inflammation of gingival, periodontal, or mucosal tissues next to restorations. Even general health problems such as systemic infections in immunocompromised patients may result from biofilms on dental materials (e.g., on dentures). Furthermore, biofilms may change material or surface properties. Biofilms on restorative materials have been investigated by several in vitro, in situ, and in vivo methods measuring a large number of different endpoints. Basically, datasets obtained from different methodological approaches are most suitable for final assessments. While surface properties like wettability or surface free energy (SFE) influence biofilm formation to a certain extent, the most relevant surface properties are material roughness followed by surface chemistry. The pellicle, which is formed rapidly on restorations after in vivo exposure, masks or levels off the influence of surface properties like wettability or SFE on biofilm formation. The prevention of biofilm formation is mainly based on general oral hygiene regimens. Furthermore, optimal polishing of restorative materials is instrumental. Several antimicrobial substances have been incorporated into restorative materials, which act by being released or as surface repellents. However, the optimal biofilm-preventive restorative material has not been found so far. New approaches in this context should aim at: (1) better understanding the role of the biofilm matrix (extracellular polymeric substance), and (2) implementing ecology-based approaches for the modification of dysbiotic disease-associated biofilms.

The field of genomics was launched when the mapping of DNA in humans and other species was accomplished. A new area began for the integrated study of all the genes in an organism, and in the case of humans, the understanding of the results of related biomedical interventions that can be tailored to benefit a particular individual. The market for direct-to-consumer genetic testing is growing, and the opportunity exists to add genetic variation relevant to oral health in general, and to dental caries and erosive tooth wear in particular, to these panels of variants that aim to inform the public regarding their own health risks.

Mutations in several genes can lead to amelogenesis imperfecta. These same genes and other members of their pathways quite possibly may also contribute to individual susceptibility to dental caries and/or erosive tooth wear. This chapter provides an analysis of the function of the genes which, when mutated, cause amelogenesis imperfecta and discusses how mechanisms involving hypomorphic alleles in one or more genes, methylation changes, and imprinting disorders could be underlying individual susceptibility to dental caries and/or erosive tooth wear.

In humans, traits and diseases are inherited primarily by complex or multifactorial modes. These imply that contributions come from more than one gene, and these can be influenced by the environment. They are the mechanisms that underlie inheritance of dental caries, erosive tooth wear, and amelogenesis. Major gene effects (monogenic or Mendelian inheritance) and chromosomal abnormalities explain the scenarios that do not fit well with complex or multifactorial inheritance. Furthermore, there are numerous non-traditional modes of inheritance. These are all exceptions of the most common complex modes of inheritance, and their understanding is important for a number of relatively rare scenarios in humans. In this chapter, these modes of inheritance are presented, and some rare conditions are explored to highlight the relevance of studying rare diseases for the understanding of more common diseases that affect populations, using dental caries as a model.