Caries Research最新文献

Introduction: Dental caries is a noncommunicable disease caused by dysbiosis of a dental biofilm. Streptococcus mutans is considered the major pathogen. The orphan response regulator GcrR negatively regulates exopolysaccharide (EPS) synthesis in S. mutans. We aimed to investigate the effect of GcrR on the cariogenicity of oral biofilms. A triple-species biofilm model was constructed, including S. mutans, Streptococcus sanguinis, and Streptococcus gordonii.

Methods: The morphology of triple-species biofilms was detected through scanning electron microscopy, and the structure was observed using confocal laser scanning microscopy. The microbial composition was measured by fluorescence in situ hybridization and qPCR. The expression of genes was detected by quantitative reverse transcription-PCR. A specific pathogen-free rat model was used to assess the cariogenicity of the triple-species biofilms.

Results: The architecture of the biofilm was significantly impaired when gcrR-overexpressed S. mutans were incubated with S. sanguinis and S. gordonii (SmugcrR++S.s+S.g). The biofilm exhibited a decrease in the production of water-insoluble glucans and water-soluble glucans, consistent with a decreased expression of EPS synthesis-related genes. The SmugcrR++S.s+S.g biofilm exhibited an increase in non-cariogenic species with lower lactic acid production. Furthermore, the SmugcrR++S.s+S.g biofilm exhibited reduced cariogenicity.

Conclusion: The biofilm cariogenicity could be shifted to a less cariogenic state by an increased expression of the GcrR regulator.

Introduction: This study evaluated the Toddler Oral Health Intervention (TOHI) for preventing early childhood caries (ECC) by 48 months. TOHI, an add-on to standard care in well-baby clinics (WBCs), aims to reduce ECC incidence and severity.

Methods: Dyads were randomized into TOHI (added to care as usual) or care as usual (CAU). The primary outcome was ECC (incidence and severity); secondary outcomes included plaque and pufa scores, and oral health behaviour changes. TOHI combined Non-Operative Caries Treatment and Prevention, Motivational Interviewing, and the Health Action Process Approach. Oral health coaches applied TOHI from enrolment (age 6-12 months) to 48 months. Data were collected at baseline, 24, and 48 months through questionnaires and clinical assessments. Blinding was maintained for clinical assessment and analysis. Intention-to-treat analysis used a Negative Binomial Hurdle Model with one-sided statistical testing.

Results: Of the 402 enrolled dyads, 353 (88%) completed the study (TOHI: 176/205, 86%; CAU: 177/197, 90%). At 48 months, 61% of TOHI toddlers and 54% of CAU toddlers remained free of any caries lesions (ICDAS ≥1). Among toddlers with caries, TOHI reduced dmfs scores by 40% (RR: 0.60; UL95% CI: 0.98, p = 0.04). For cavitated lesions (ICDAS ≥3), TOHI reduced dmfs scores by 53% (RR: 0.47; UL95% CI: 1.04, p = 0.06), and 84% of TOHI toddlers remained free of cavitated lesions versus 78% in CAU.

Conclusion: TOHI, added to usual care at WBCs, modestly reduced ECC incidence and severity at 48 months. Further research is needed to assess long-term impacts and cost-effectiveness.

Introduction: Children with early childhood caries (ECC) show different caries severities and susceptibility in different tooth types and location in the oral cavity. The study aimed to investigate differences in the oral microbiome in ECC subjects stratified according to the severity of caries and between more and less caries-prone teeth within the same subjects.

Methods: Supragingival plaque from the upper and lower anterior regions in the oral cavity of subjects were collected in 3 groups of increasing caries severity: G1 - molar (M) caries only; G2 - molar and upper anterior (UA) caries; and G3 - M + UA + lower anterior (LA) caries followed by microbiome analysis.

Results: Alpha-diversity analyses showed inter- but no intra-individual statistically significant differences between the UA and LA (p < 0.001, LA > UA) and a significant difference between the microbiome of the three caries groups (p < 0.001). There were significant beta-diversity differences between G1 and G2 (p < 0.05) and in the composition and diversity among the three groups (p < 0.001). Actinomyces, Saccharibacteria_genera_inserta_sedis, and Eikenella had increased differential abundance in G1 versus G3 and Fusobacterium was less abundant in G2 compared to the other groups.

Conclusions: There were clear distinct differences in tooth-site-specific and caries-severity microbiome diversity patterns and bacterial abundance profiles in S-ECC children.

Introduction: Caries lesions that are difficult to detect through visual inspection pose risks to dental health. To address this, we propose a detection method using the split-spectrum optical attenuation coefficient (OAC), capitalizing on the wavelength-dependent properties of carious dental structures.

Methods: The complete OCT spectrum is divided into four spectral segments, each independently reconstructed and analyzed for OAC. OAC values are then compared across segments to differentiate between healthy and carious tissue. Experiments were conducted on ex vivo human teeth, with carious areas marked by dental professionals. The accuracy of the proposed method was evaluated and compared with the full-spectrum OAC method.

Results: For healthy enamel, OAC values ranged from 0.2 to 0.4 mm-1, remaining consistent across spectral bands. In carious enamel, OAC increased significantly (0.5-2.5 mm-1), with a 60% rise in short-wave versus long-wave OAC. Healthy dentin showed OAC values from 0.3 to 0.7 mm-1, whereas carious dentin reached 0.8-1.2 mm-1, with a 50% increase in short-wave OAC compared to long wave. The average false-positive rate of the method proposed in this paper is 0.9%, significantly lower than the 1.8% of the traditional OAC method (t test, n = 16, p = 0.013). The average false-negative rates of both methods are around 1%, with no significant difference.

Conclusion: Findings indicate that the split-spectrum OAC method can effectively identify caries lesions, with higher accuracy and specificity compared to the traditional OAC method.

Introduction: Professional fluorides form reaction products on tooth substrates, which once dissolved, interfere with the caries process. However, the persistence of these reservoirs before the need of a new application is unknown. We investigated in situ the effect of various cariogenic challenges and exposure to fluoride toothpaste on the retention of enamel fluoride reservoirs.

Methods: In a blind, 4-period crossover study, 12 participants wore palatal devices containing human enamel slabs previously treated with one application of acidulated phosphate fluoride gel. No biofilm or biofilm accumulation and exposure to 20% sucrose 0, 2, or 8 times/day were tested. Participants used non-fluoridated or fluoridated toothpastes (1,100 mg F/kg) throughout the experimental periods. Slabs were collected after 2, 7, or 14 days to assess remaining alkali-soluble fluoride reservoir concentrations.

Results: The loss of the enamel fluoride reservoirs was accelerated either in the absence of biofilm or under biofilms exposed to sucrose 8 times/day (p < 0.05). The loss of these reservoirs was reduced by fluoride toothpaste use (p < 0.05).

Conclusion: The results support a personalized recommendation of the frequency of professional fluoride application based on patients' caries activity since the cariogenic challenge and exposure to fluoride influence the retention of fluoride reservoirs formed on enamel by professional fluoride application.