Subgingival microbial changes in Down Syndrome adults with periodontitis after chlorhexidine adjunct non-surgical therapy and monthly recalls–A 12-month case series study

Abstract

<h3>Objectives</h3><p>Down Syndrome (DS) adults are at risk for periodontitis. Previous reports indicated difficulties in periodontopathogen reduction or eradication in DS individuals after periodontal treatment. This case series follows the subgingival microbial changes in adult DS individuals with periodontitis who received chlorhexidine adjunct non-surgical therapy plus 12-month recalls.</p><h3>Methods</h3><p>Twenty periodontitis DS participants (7 females; 25.5 ± 5.6 years of age; 3 with generalized periodontitis) partook in a study involving non-surgical mechanical periodontal therapy, twice daily chlorhexidine gel toothbrushing, chlorhexidine mouthwash, and monthly recalls. The subgingival microbiota profile was followed at baseline, 6-, and 12-months post-operation.</p><h3>Results</h3><p><em>Desulfobulbus, Saccharibacteria</em> (TM7), <em>Tannerella</em>, and <em>Porphyromonas</em> were the major subgingival genera in this DS cohort. Favorable chlorhexidine adjunct non-surgical treatment outcomes were observed, with the relative abundance of <em>Desulfobulbus</em> sp. HMT 041, <em>Saccharibacteria</em> (TM7) [G-1] bacterium HMT 346 or 349, and <em>Tannerella forsythia</em> significantly reduced at the end of the study, but no significant reduction of <em>Porphyromonas gingivalis</em> or <em>Aggregatibacter actinomycetemcomitans</em> could be observed. Relative abundance of <em>Desulfobulbus</em> sp. HMT 041 and <em>T. forsythia</em> were also found to be significantly associated with plaque, bleeding on probing, and probing pocket depth (PPD, in mm) at a site level, while the relative abundance of <em>Halomonas pacifica</em> was negatively associated with PPD.</p><h3>Conclusions</h3><p>Successful chlorhexidine adjunct non-surgical treatment with hygiene care was accompanied by a subgingival microbial shift involving certain periodontopathogenic species, except <em>P. gingivalis</em> and <em>A. actinomycetemcomitans</em>. Further investigations are required to clarify the mechanism underpinning the unchanged relative abundance of the above two pathogens despite favorable clinical responses.</p><h3>Clinical Significance</h3><p>DS adults face challenges achieving optimal home care or hygiene for periodontal healing and disease prevention. Chemical adjunct mechanical periodontal therapy plus regular recalls appeared promising clinically and microbiologically, with subgingival periodontopathogenic species reduction. The persistence of <em>A. actinomycetemcomitans</em> and <em>P. gingivalis</em> in subgingival niches post-treatment warrants further investigation.</p>