Periodontal Diseases in Children and Adolescents …
51
all age groups, while
T. forsythia
and
P. intermedia
were detected less frequently, and
P.
gingivalis
and
T. denticola
were rarely identified (Figure 19). These results suggest that the
colonization of many periodontal bacterial species occurs quite early in childhood without
clinical signs of periodontal disease. In contrast, there are several species exhibiting poor
colonization, such as
P. gingivalis
and
T. denticola
.
Next, in order to determine which species are inhabitants or are transient, the subjects
whose specimens were collected more than twice for more than 2 years were analyzed. Figure
20 shows one of the representative results.
C. ochracea
,
C. sputigena
,
A.
actinomycetemcomitans
,
P. nigrescens
,
C. rectus
, and
E. corrodens
were frequently detected
in multiple specimens
taken at different times, suggesting that these are the common members
of the oral flora of periodontally healthy children. In contrast,
P. gingivalis
,
T. denticola
, and
P. intermedia
were rarely detected which indicates that these species should be regarded as
transient species in children. These results suggest that there exist some species with early
colonization and that others are just transient species in children.
3) Longitudinal Studies of Periodontitis-Assocated
Bacteria
It is of interest to determine the distribution of the periodontal species in subjects over
time. The occurrence of periodontal bacterial species in 192 systemically healthy subjects (89
male and 103 female, 2–16 years old) was analyzed in 1999-2000, among which 26 subjects
continued to attend annual recall examinations until 2006–2007 [56]. Thus, a total of 26
children and adolescents from whom dental plaque and saliva specimens were obtained
during both the 1st (1999-2000) and 2nd (2006-2007) periods, were analyzed. The
periodontal condition of most of the subjects in the 2nd period wasrelatively good, which
reflected their continuous participation in our recall system, in which not only periodical
examinations were performed but also professional tooth cleaning as well as brushing
instructions were provided. On the other hand, there were several subjects with periodontal
pocket depths of 4-5 mm without attachment loss. The PCR method specified the presence of
10 periodontal bacterial species, which indicated a positive correlation of periodontal pocket
depth with the total number of detected species.
P. gingivalis
,
T. denticola
, and
T.
forsythia
comprise the ―red complex‖ (RC) group of species, a prototypical polybacterial
pathogenic consortium active in periodontitis [57, 58]. RC species are also known to be
correlated with gingival inflammation based on studies of Japanese teenagers [59, 60]. We
further analyzed the bacterial profiles in the first and second collections focusing on the
presence of RC species [56].
Subjects with RC species in saliva specimens obtained during the 2nd collection
possessed a significantly higher number of total bacterial species than those without these
organisms (Figure 21). The main reason for this result may be because
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