Hidetake Fujinaka

Relationship of periodontal clinical parameters with bacterial composition in human dental plaque

More than 600 bacterial species have been identified in the oral cavity, but only a limited number of species show a strong association with periodontitis. The purpose of the present study was to provide a comprehensive outline of the microbiota in dental plaque related to periodontal status. Dental plaque from 90 subjects was sampled, and the subjects were clustered based on bacterial composition using the terminal restriction fragment length polymorphism of 16S rRNA genes. Here, we evaluated (1) periodontal clinical parameters between clusters; (2) the correlation of subgingival bacterial composition with supragingival bacterial composition; and (3) the association between bacterial interspecies in dental plaque using a graphical Gaussian model. Cluster 1 (C1) having high prevalence of pathogenic bacteria in subgingival plaque showed increasing values of the parameters. The values of the parameters in Cluster 2a (C2a) having high prevalence of non-pathogenic bacteria were markedly lower than those in C1. A cluster having low prevalence of non-pathogenic bacteria in supragingival plaque showed increasing values of the parameters. The bacterial patterns between subgingival plaque and supragingival plaque were significantly correlated. Chief pathogens, such as Porphyromonas gingivalis, formed a network with other pathogenic species in C1, whereas a network of non-pathogenic species, such as Rothia sp. and Lautropia sp., tended to compete with a network of pathogenic species in C2a. Periodontal status relates to non-pathogenic species as well as to pathogenic species, suggesting that the bacterial interspecies connection affects dental plaque virulence.

Age-related changes in gingival blood flow parameters measured using laser speckle flowmetry

Previous studies have suggested a possible relationship between age-related changes to human gingival hemodynamics and periodontal disease. However, firmly establishing this has been difficult because of a lack of suitable tools. Our study investigated whether a non-invasive laser speckle flowgraphy (LSFG)-based 2-dimensional technique could be used to assess maxillary anterior gingival blood flow under resting conditions. In total, 124 healthy male volunteers aged between 22 and 69 years were included in the study and delineated into young (Y; 22-37 years, n = 45), middle-aged (M; 38-53 years, n = 43), and elderly groups (E; 54-69 years, n = 36). The differences in gingival hemodynamics were compared among age groups and pulse waveform analysis performed to calculate blood flow indices, mean blur rate (MBR), gingival vascular conductance (MBR/mean blood pressure [MBP]), and three pulse waveform parameters (acceleration time index [ATI], falling rate, and blowout time [BOT]). Although no statistically significant differences were observed in the MBR of the three age groups, vascular conductance (MBR/MBP) was lower in groups M and E compared to group Y and correlated negatively with age. ATI and falling rates were also significantly higher in group E relative to group Y, whereas average BOT was significantly lower. All of the assessed parameters correlated with age. These data suggest that there are age-related decreases in the ability to maintain blood flow in the human maxillary anterior gingiva under resting conditions which may impact the likelihood of periodontal disease.