A 5‐Year Longitudinal Study of Tannerella forsythia prtH Genotype: Association With Loss of Attachment

BACKGROUND: Tannerella forsythia (previously T. forsythensis) in subgingival plaque has been recognized as a defined periodontal pathogen, but its mere presence may be insufficient for disease initiation and/or progression. The organism may produce a cysteine protease, encoded by the prtH gene, which may play a role in the transition from commensal organism to opportunistic pathogen. This study aimed to relate changes in the level of T. forsythia prtH genotype over a 5-year period to a concomitant loss of attachment. METHODS: Real-time polymerase chain reaction was used to quantify the level of the prtH gene in plaque samples from subjects with and without attachment loss (> or =2 mm in at least two sites) over a 5-year period. Clinical measures and subgingival plaque samples were obtained at yearly intervals. RESULTS: Baseline levels of the prtH genotype were significantly lower in the subjects without loss of attachment compared to those who lost attachment over 1, 2, 4, or 5 years. In the subjects with loss of attachment, the higher prtH levels at baseline were not maintained until the end of the observation period. CONCLUSION: Higher levels of the prtH genotype were associated significantly with future attachment loss.