Abstract
The present study was a retrospective evaluation, from the clinical and microbiological perspectives,of the treatment response approximately one year after systemic antibiotic (SA) administration combined with scaling and root planing (SRP) in patients with severe periodontitis. The relationships between the treatment response and related factors were also evaluated using multilevel multiple regression analysis, in order to clarify the indications for SA administration in periodontal cause-related therapy. Clinical and microbiological assessments were conducted at the baseline, at follow-up after SRP combined with SA therapy (Exam 1), and at follow-up after further SRP combined with SA therapy as necessary, or after periodontal surgery (Exam 2). The diagnostic criteria for therapy-resistant periodontitis (TRP) comprised a post-treatment probing pocket depth (PD) reduction of＞2 mm in less than 70% of sites, with a baseline PD of＞6 mm. The following results were obtained. 1) The improvements in the PD, bleeding on probing (BOP) and suppression of periodontal pathogens in cases of non-surgical periodontal treatment combined with SA between Exam 1 and 2 were equivalent to those noted in the patients treated by periodontal surgery. 2) The rate of TRP occurrence after Exam 1 was 29%, and the post-treatment decrease of the BOP and bacterial risk improvement were insufficient in the TRP patients. 3) Comparison of the findings at the baseline and at Exam 1 revealed that the higher the pre-treatment PD, the greater the post-treatment reduction in the PD. In cases with a favorable treatment response, comparison of the tooth and site-level variables showed that the relative contribution to the total variance was greater for patient-related variables. Significant clinical and microbiological effects were obtained when systemic antibiotics were administered in combination with SRP in the treatment of severe periodontitis. In addition, these findings suggest that patient-related factors influencing the treatment response should also be evaluated in addition to the conventional classification of periodontal disease in patients in whom SA therapy is indicated. Nihon Shishubyo Gakkai Kaishi (J Jpn Soc Periodontol) 55(2)：156-169, 2013.
