Abstract
Tongue coat samples were collected from 292 subjects consisting of 85-year-old individuals, periodontally healthy young adults in their 20^s and middle aged patients who received a regular dental check up for maintenance after periodontal treatment. Four species of periodontopathogens and two species of mutans streptococci were detected from the tongue coat samples using species-specific polymerase chain reaction. Dental plaque samples were also collected from periodontally healthy young adults, and six species were detected similarly. The results were follows: 1. The rate of bacterial detection from dentulous elders was highest in all subjects, on the other hand, that from edentulous elders was lowest in all subjects. 2. There was a significant relationship in that the bacterial species found in the tongue coat were the same as those in the dental plaque. Concerning periodontopathogens except for Treponema denticola, the detection rates from the tongue coat samples were higher than those from the plaque samples. Furthermore, when certain bacterial species were detected from either sample, they were detected from the tongue coat samples in most cases. 3. The detection rate of Streptococcus mutans from the tongue coat samples showed no significant difference. Concerning Streptococcus sobrinus, the detection rate from denture wearing subjects was higher than subjects without dentures. 4. In periodontally healthy young adults, the detection of T. forsythensis, P. intermedia, and S. sobrinus was associated with the amount of tongue coat, which had a strong relationship with a smoking habit From these results, it was suggested that the tongue coat interacted with other niches in the oral cavity, acting as a possible reservoir or receiver, and consequently, it could influence total oral microflora.
