Caries Research

Các nghiên cứu trước đây sử dụng phương pháp miễn dịch huỳnh quang (IF) đã chỉ ra rằng <i>Streptococcus mutans</i> có thể ưu tiên bám vào các phân vị cụ thể trong mảng bám kẽ răng. Nghiên cứu này nhằm mở rộng những quan sát này tới các loại Streptococcus mutans khác và Lactobacilli trong mảng bám biên nướu. Hai trăm bảy mươi mẫu mảng bám kẽ răng được lấy từ 90 răng (3 mẫu từ mỗi răng) ở 64 trẻ em; ba phân vị biên nướu liên quan đến khu vực tiếp xúc: xa khỏi (A), bên cạnh (S) và dưới (B) khu vực tiếp xúc. Các mẫu được xử lý bằng IF gián tiếp sử dụng kháng huyết thanh đa giá hiệu suất cao chống lại <i>S. mutans</i> 'c', anti-<i>S. sobrinus</i> 'd', anti-<i>L. casei</i> và anti-<i>L. acidophilus</i>. Một mối liên kết tích cực tổng thể được tìm thấy giữa <i>S. mutans</i> 'c' và <i>S. sobrinus</i> 'd' (p < 0.001). Sự khác biệt có ý nghĩa (p < 0.1) được tìm thấy giữa tỷ lệ phần trăm tại mỗi phân vị cho <i>S. mutans</i> 'c': A = 39%, S = 51% và B = 70%, và cho <i>S. sobrinus</i> 'd' là 21, 33 và 49%. Streptococci mutans (MS) có xu hướng bám vào phân vị dưới khu vực tiếp xúc (B = 81%) so với phân vị A và S (48 và 62%, tương ứng). <i>S. mutans</i> 'c' và <i>S. sobrinus</i> 'd' được phát hiện cùng nhau tại các phân vị A = 12%, S = 22%, và B = 38%, với tỷ lệ phần trăm tại các vị trí B cao hơn các vị trí A (B > A, p < 0.01 và B > S, p < 0.05). Các loại <i>Lactobacillus</i> spp. hiếm khi bị cô lập, và thường được tìm thấy cùng với MS. Có mối quan hệ tích cực giữa sự hiện diện của Lactobacilli hoặc MS và sâu răng (chỉ tổn thương trắng), mặc dù các loài này thường có thể bị cô lập từ các vị trí không sâu răng. Sự hiện diện của cả <i>S. mutans</i> 'c' và <i>S. sobrinus</i> 'd' có mối tương quan mạnh mẽ với các tổn thương sâu răng sớm. Ngoài ra, nghiên cứu này còn xác nhận sự biến đổi của vi sinh vật tại các phân vị khác nhau trong mảng bám răng kẽ răng.

For an Organisation for Caries Research/European Federation of Conservative Dentistry consensus, this systematic review is aimed to assess the question of how to manage the caries process in the case of early childhood caries (ECC). Medline via PubMed was searched systematically regarding management of ECC. First priority was existing systematic reviews or randomized clinical trials otherwise cohort studies dealing with management of ECC, primarily with carious anterior teeth. After data extraction, the potential risk of bias was estimated depending on the study types, and the level of evidence was evaluated. Regarding management of ECC, results are presented for silver diamine fluoride (SDF, <i>n</i> = 5), nonoperative caries management (NOCM, <i>n</i> = 10), and restorative approaches (RA, <i>n</i> = 8) separately, as different kinds of studies with different levels of evidence were found for the different aspects in the management of ECC. The 5 systematic reviews on SDF showed a high potential for arrest of ECC on a high level of evidence. In NOCM, a low level of evidence for a moderate effect of fluoride varnish in arresting or remineralizing, especially non-cavitated lesions, was assessed. For RA in carious anterior upper primary teeth, a low level of evidence was found for higher failure rates of glass ionomer cement and composite fillings than composite strip crowns even if placed under general anaesthesia and especially compared to other crowns (stainless steel and zirconia). In conclusions, ECC may be managed successfully with nonoperative (SDF, regular fluoride application) and moderately well with operative approaches, but the decision is affected by many other variables such as pulpal involvement, the child’s cooperation, or a general anaesthesia setting.

Despite widespread use of various concentrations of fluoride for the prevention of dental caries, the relationship between fluoride concentration and activity against cariogenic biofilms has not been much studied. Herein we investigated the relationship between fluoride concentration and activity against virulence factors and viability of <i>Streptococcus mutans</i> biofilms. <i>S. mutans</i> biofilms were formed on saliva-coated hydroxyapatite discs. The 70-hour-old biofilms were exposed to 0, 1, 3, 10, 30, 100, 300, 1,000 or 2,000 ppm F^-. The changes of virulence factors and viability of the biofilms were analyzed using biochemical methods and laser scanning confocal fluorescence microscopy. At 1-2,000 ppm F^-, the activity of fluoride against acid production, acid tolerance, and extracellular polysaccharide formation of <i>S. mutans</i> biofilms accurately followed a sigmoidal pattern of concentration dependence (R² = 0.94-0.99), with EC₅₀ values ranging from 3.07 to 24.7 ppm F^-. Generally, the activity of fluoride against the virulence factors was concentration-dependently augmented in 10-100 ppm F^- and did not increase further at concentrations higher than 100 ppm F^-. However, fluoride did not alter glucosyltransferase activity and viability of <i>S. mutans</i> biofilm cells in all concentrations tested. These results can provide a basis for the selection of appropriate fluoride concentrations that reduce the physiological ability of cariogenic biofilms.

Secondary caries can develop at the tooth-restoration interface, depending on the presence of a gap and its size, but this process could be inhibited by fluoride. The aim of this study was to assess the relationship between gap size and dentine secondary caries adjacent to composite resin (CR) or glass ionomer (GI) restorations, using a microcosm biofilm model in a constant depth film fermentor (CDFF). Dentine discs restored with CR (Z250) or GI (Vitremer) with gap sizes of 0, 50, 100, 180 or 250 μm were mounted on the CDFF. Microcosm biofilms were formed on the restored discs and daily subjected to 8 pulses of 10% sucrose solution. On the 18th day, dentine mineral loss and lesion depth around the restorations were determined by transverse microradiography.The effect of gap size was overall not statistically significant either with regard to mineral loss (p = 0.449) or lesion depth (p = 0.328), but greater mineral loss and lesion depth were found adjacent to CR than to GI (p < 0.001). However, Spearman correlation showed that mineral loss and lesion depth increased with gap size for CR (p < 0.001) but not for GI (p > 0.05). The findings support the conclusion that fluoride released from GI inhibits dentine demineralization adjacent to restorations, irrespective of gap width.

<i>Background/Aims:</i> The antimicrobial resistance of microorganisms in biofilms and the polymicrobial interactions in these biofilms that modulate resistance require novel strategies to evaluate the efficacy of caries-preventive compounds. The current study aimed to evaluate the effects of a caries-preventive agent in <i>Streptococcus mutans</i> and polymicrobial biofilms. <i>Methods:</i> We developed a novel high-throughput active attachment model. The model consisted of a custom-designed lid containing glass discs that fit on top of standard 24-well plates. Biofilms were formed using either <i>S. mutans</i> C180-2 or saliva. At the end of biofilm formation (up to 96 h) the biofilms were treated with amine fluoride (AmF) solutions. The viability of the biofilms was determined by CFU counts, and metabolic activity was measured via lactate production. <i>Results:</i> The effect of AmF on the viability of the polymicrobial biofilms was significantly less than that on the <i>S. mutans</i> biofilms, indicating a higher resistance in the complex biofilms. Both types of biofilms became more resistant to AmF with age. The higher resistance of the polymicrobial biofilms was not reflected in metabolic activity; in dose-response experiments AmF reduced lactate production in both types of biofilms to the same extent. Moreover, the age-induced increased resistance in the polymicrobial biofilms was less pronounced in terms of the inhibition of metabolic activity. <i>Conclusions:</i> This study clearly shows that when evaluating the efficacy of caries-preventive compounds it is essential to use appropriate polymicrobial biofilm models, and more importantly that efficacy needs to be judged based on the reduction of acid formation (i.e. cariogenic potential) as well as on bacterial viability.