Yuki Abiko

Profiling of subgingival plaque biofilm microflora from periodontally healthy subjects and from subjects with periodontitis using quantitative real-time PCR

BACKGROUND AND OBJECTIVE Qualitative and quantitative changes of the subgingival plaque biofilm microflora in periodontal pockets are thought to be associated with the development and progression of periodontitis. The aims of the present study were to quantify the proportions of nine periodontitis-associated bacterial species and four Streptococcus species in subgingival plaque, and to evaluate their relationship with periodontitis quantitatively. MATERIAL AND METHODS Subgingival plaque samples were obtained from 12 periodontally healthy subjects and from 28 patients with periodontitis. The amounts of total and target bacteria were measured by quantitative real-time PCR using universal and species-specific primers, respectively. RESULTS The proportion of total obligate anaerobes was found to be higher in subjects with periodontitis than in periodontally healthy subjects (p < 0.05). Among obligate anaerobes, Tannerella forsythia (2.04 +/- 5.27%, p < 0.05), Porphyromonas gingivalis (0.54 +/- 1.41%) and Eubacterium saphenum (0.30 +/- 0.96%) were detected at high proportions in subjects with periodontitis, but not in periodontally healthy subjects. By contrast, the proportion of total streptococci was lower in subjects with periodontitis (p < 0.05). Specifically, the proportion of T. forsythia, P. gingivalis or E. saphenum increased (>or= 2.78%) and the proportion of Streptococcus species decreased to virtually undetectable levels, in subjects with periodontitis. CONCLUSION Obligate anaerobes, including T. forthysia, P. gingivalis and E. saphenum, were identified predominantly in microflora from subjects with periodontitis, whereas Streptococcus species were identified predominantly in microflora from periodontally healthy subjects, suggesting a change in the subgingival environment that resulted in conditions more suitable for the survival of obligate anaerobes. The proportion of these obligate anaerobes in the subgingival plaque of subjects with periodontitis appears to be associated with the status of human periodontitis.

Inhibitory effect of resin composite containing S-PRG filler on Streptococcus mutans glucose metabolism

OBJECTIVES Resin composites containing surface pre-reacted glass-ionomer (S-PRG) fillers have been reported to inhibit Streptococcus mutans growth on their surfaces, and their inhibitory effects were attributed to BO33- and F- ions. The aim of this study was to evaluate S. mutans acid production through glucose metabolism on resin composite containing S-PRG fillers and assess inhibitory effects of BO33- and F- on S. mutans metabolic activities. METHODS The pH change through S. mutans acid production on experimental resin composite was periodically measured after the addition of glucose. Inhibitory effects of BO33- or F- solutions on S. mutans metabolism were evaluated by XTT assays and measurement of the acid production rate. RESULTS The pH of experimental resin containing S-PRG fillers was significantly higher than that of control resin containing silica fillers (p < 0.05). OD450 values by XTT assays and S. mutans acid production rates significantly decreased in the presence of BO33- and F- compared with the absence of these ions (p < 0.05). CONCLUSIONS pH reduction by S. mutans acid production was inhibited on resin composite containing S-PRG fillers. Moreover, S. mutans glucose metabolism and acid production were inhibited in the presence of low concentrations of BO33- or F-. CLINICAL SIGNIFICANCE BO33- or F- released from resin composite containing S-PRG fillers exhibits inhibitory effects on S. mutans metabolism at concentrations lower than those which inhibit bacterial growth.

Formation of bioactive N-doped TiO2 on Ti with visible light-induced antibacterial activity using NaOH, hot water, and subsequent ammonia atmospheric heat treatment.

Titanium (Ti) treated with NaOH and hot water, and heated in an ammmonia (NH3) gas atmosphere for 1 or 3h exhibited in vitro apatite formation within 7days when soaked in simulated body fluid (SBF). Moreover, the treated Ti decomposed methylene blue and showed excellent bactericidal activity against Escherichia coli under visible light irradiation. The surface treatment resulted in the formation of a fine network of N-doped anatase-type titania (TiO2-xNx) on the Ti surface, which was responsible for both the apatite formation in SBF and the visible light-induced antibacterial activity. These preliminary results highlight the efficacy of our simple method for producing novel bioactive Ti with visible light-induced antibacterial activity, which could be applied to orthopaedic and dental implants without the risk of infection.

Oral Microbiota in Crevices Around Dental Implants: Profiling of Oral Biofilm

Large numbers of bacteria (>106/mm2) generally inhabit the surface of the oral cavity, particularly at the interface between teeth and gingiva, as an oral biofilm (microbiota). The establishment of anaerobic bacterial culture and molecular biological techniques has enabled us to isolate and detect various bacterial species from oral biofilm. It has been estimated that more than 600 bacterial species inhabit the oral cavity. Nevertheless, the oral cavity is considered healthy when the oral microbiota is composed of indigenous bacteria. Numerous environmental changes in the oral cavity may lead to accumulation of dental caries-associated or periodontitis-associated bacteria, resulting in the initiation of dental caries or periodontitis, respectively. The environment in crevices around dental implants is considered similar to that in subgingival sulcus, such as neutral pH, anaerobiosis and rich nutrition (e.g., amino acids and peptides). The environment may be supportive of anaerobic growth of the bacteria in microbiota in crevices around implants, particularly at the interface between histocompatible artificial material and mucosal epithelium. The microbiota may trigger inflammation in the tissue around the implants. In this article, the current topics on the profiling of oral microbiota in crevices around implants are reviewed.

Rapid Quantification of Bacteria in Infected Root Canals Using Fluorescence Reagents and a Membrane Filter: A Pilot Study on Its Clinical Application to the Evaluation of the Outcomes of Endodontic Treatment

Objective. The bacterial examination has been performed during the course of the root canal treatment. In the present pilot study, the new developed method, using fluorescence reagents and a membrane filter, was applied to the detection and quantification of bacteria in infected root canals, in order to evaluate the outcomes of the treatment. Methods. Six infected root canals with periapical lesions from 5 subjects were included. Informed consent was obtained from all subjects (age ranges, 23–79 years). Samples from infected root canals were collected at the beginning of the treatment (termed #25 First), the end of the first day of treatment (termed #55 First), and the next appointment day (termed #55 Second). Then, the bacterial count (CFU) was measured using fluorescence reagents (4′,6′-diamidino-2-phenylindole and propidium iodide) and the polycarbonate membrane filter by Bioplorer. Results. The mean ± SD of CFU in the sample of “#25 First” was (1.0 ± 1.4) × 105. As the root canal treatment progressed, the CFU decreased as 7.9 × 103 (#55 First) and 4.3 × 102 (#55 Second). Conclusion. In the present pilot study, rapid detection and quantification of bacteria in infected root canals were found to be successfully performed using fluorescence reagents and a membrane filter (Bioplorer analysis).

Subgingival Plaque Biofilm Microflora of Elderly Subjects

This study aimed to quantify Porphyromonas gingivalis (Pg) in subgingival plaque of periodontitis (P) and periodontally healthy (H) subjects in the elderly. Subsequently, fimA genotypes were determined, and compared between P and H sites in the same subjects. The proportion of Pg was higher in P than in H. The fimA genotypes of P were identified mainly as II and Ib, while those of H were as I–IV. In four out of five subjects in whom Pg was detected in H sites, the fimA genotype was identical between P and H sites, but the proportion of Pg was significantly higher in P sites than in H sites (P < 0.05). This study suggests that the increase of Pg and the specific fimA genotypes are associated with P in the elderly, and that Pg possibly transmits within the oral cavity.

Community Oral Health Promotion Program Fostering Self-Management for the Elderly

This study aimed to evaluate a health promotion program for the elderly to foster self-management of oral health. The results of the first district evaluated among four districts are reviewed. Subjects consisted of 31 people (average age, 73.1 ± 7.4 years). The intervention consisted of a group study and private consultations for 3 months. As a consequence, subjects cleaned their teeth more often than before (P < 0.05). Deposits of plaque and tartar were significantly lower after intervention (P < 0.01–0.001), while scores for oral function did not significantly improve. Scores for QOL and cognitive function improved significantly (P < 0.05). These results suggest that this program promotes not only oral self-care, resulting in good oral health conditions, but also improvement of cognitive function of the elderly.

Change in Infected Root Canal Microflora During the Course of Root Canal Therapy

The purpose of the present study was to profile the microflora in infected root canals, using anaerobic culture and molecular biological techniques for bacterial identification, before and after root canal treatment. The mean bacterial count in root canals before treatment was 106, and obligate anaerobes were predominant. The predominant isolates were Olsenella, Pseudoramibacter, Propionibacterium and Mogibacterium. On second and third visits, no bacteria were detected in the samples collected after treatment. These results suggest that the environment in root canals is anaerobic and therefore support the growth of anaerobes, and that adequate treatment changes the root canal environment drastically.

Porphyromonas gingivalis is widely distributed in subgingival plaque biofilm of elderly subjects

The frequency of periodontal diseases appears to increase with age. Porphyromonas gingivalis is widely regarded as major periodontal pathogens. This study aimed to quantify P. gingivalis in subgingival plaque biofilm of elderly subjects by real-time polymerase chain reaction (PCR). Subgingival plaque was obtained from 198 periodontally healthy (mean age, 70.3 years) and 176 subjects with periodontitis (70.6 years). Quantification of total bacteria and P. gingivalis was performed by real-time PCR using universal and P. gingivalis-specific primers based on 16S rRNA genes, respectively. Both the detection frequency and mean proportion of P. gingivalis were significantly higher in subjects with periodontitis than in periodontally healthy subjects (p < 0.0001). Nevertheless, P. gingivalis was detected frequently both from subjects with periodontitis and periodontally healthy subjects. These results suggest that P. gingivalis is widely distributed in subgingival plaque biofilm of elderly subjects.

Real-time PCR analysis of cariogenic bacteria in supragingival plaque biofilm microflora on caries lesions of children

The aim of this study was to quantify cariogenic bacteria, Streptococcus mutans, in supragingival plaque biofilm microflora on caries lesions of children. After informed consent was obtained from each subject, supragingival plaque on caries lesion was obtained from 10 children (3–10 years). Healthy supragingival plaque was also obtained from the same subject, as a control. Total bacteria and S. mutans were quantified by real-time PCR using universal and S. mutans-specific primers based on 16S ribosomal RNA genes, respectively, and the proportion of S. mutans in each sample was calculated. Total bacterial DNA levels in carious plaque and healthy plaque were found to be similar, though the proportion of S. mutans in carious plaque was higher than that in healthy plaque. The findings of this study suggest that amount of cariogenic bacteria in supragingival plaque biofilm may be associated with the status of dental caries.