Does proper flossing performance translate into effective plaque removal?

Objectives: Interdental hygiene plays a crucial role in maintaining oral health, yet the effectiveness of dental floss remains a subject of debate. Thus, this study aimed to assess whether improved flossing technique relates to improved cleaning efficacy.

Materials and methods: A total of 37 adults (23.1 ± 3.2 years) participated. After habitual toothbrushing, plaque was disclosed and an intraoral scan was performed; afterwards, habitual flossing was videotaped, followed by a second intraoral scan of disclosed plaque. Participants then watched an instruction video. After one week of practice, flossing was again videotaped and intraoral scans were taken before and after flossing. On defined regions on images obtained from the four scans, plaque coverage was assessed with a three-level score (0: none, 1: <50%, 3: ≥50%). Proximal Surface Plaque Index (PSPI) was calculated as mean from all scores. A flossing performance score (FPS) was generated from the percentage of interdental spaces that were correctly flossed (interdental space reached, floss correctly applied and vertical movements; 0: totally imperfect, 3: perfect flossing). Ramfjord teeth (16, 21, 24, 36, 41, 44) were analysed, values are given as median [95% CI].

Results: FPS improved distinctly after instruction (2.0 [1.48;2.54] vs. 2.83 [2.45;2.95]; (p < .001), but not plaque removal (difference PSPI before/after: 0.17 [0.04;0.25] vs. 0.21 [0.13;0.25]; p = .112). Plaque removal was not correlated with PSPI.

Conclusion: These findings suggest that even with correct technique, flossing may not substantially reduce plaque levels.

Clinical relevance: The results align with previous studies questioning the efficacy of flossing and highlight the need for further investigation into interdental cleaning approaches.