Effect of quadrantwise versus full-mouth subgingival instrumentation on clinical and microbiological parameters in periodontitis patients: A randomized clinical trial

Aim: This study evaluated the efficacy of quadrantwise subgingival instrumentation (Q-SI) versus one-stage full-mouth subgingival instrumentation (FM-SI) on probing depth and periodontal pathogen reduction over a 6-month follow-up period, as well as whether baseline periodontal pathogens influenced the impact of periodontal treatment protocols on outcomes. Methods: Patients with periodontitis were randomized to receive Q-SI (n = 43) or FM-SI (n = 45). Patients were instructed and motivated to maintain optimal oral hygiene during the treatment sessions. Clinical (probing pocket depth [PPD], clinical attachment loss [CAL], and bleeding on probing [BOP]) and periodontal pathogens were assessed at baseline and after 30, 90, and 180 days. Total bacterial load and periodontal pathogens were analysed via real-time PCR. Results: At the 6-month follow-up, the median PPD decreased from 4.8 mm (interquartile range [IQR]: 4.3–5.2) to 2.6 mm (IQR: 2.3–2.9) in FM-SI patients and from 4.7 mm (IQR: 4.1–5.2) to 3.2 mm (IQR: 2.4–3.5) in Q-SI patients (p <.001). At 6 months, FM-SI was more effective at reducing the median proportions of Porphyromonas gingivalis (Pg), Aggregatibacter actinocomyctemcomitans, and Tannerella forsythia (Tf) (p <.001 for each value). Multilevel linear regression analysis demonstrated that high baseline PPD (p =.029), Pg (p =.014), and Tf (p <.001) levels and the FM-SI protocol (p <.001) were statistically significant predictors of PPD reduction at 6 months. Furthermore, PPD reduction was significantly greater in the FM-SI group when lower baseline Pg levels were detected. Conclusion: The FM-SI was more effective than the Q-SI in reducing the mean PPD and number of periodontal pathogens in periodontitis patients over a 6-month follow-up period. Higher baseline PPD and Pg levels had a negative impact on PPD reduction at 6 months after FM-SI.