Influence of the Utilization Time of Different Manual Toothbrushes on Oral Hygiene Assessed During a 6‐Month Observation Period: A Randomized Clinical Trial

Background: The aim of this randomized clinical trial (RCT) was to investigate whether 6‐month continuous use of different manual toothbrushes (TBs) influences plaque removal and the degree of gingival inflammation compared to short utilization periods of 4 weeks each. Methods: In total, 96 participants were randomly allocated into two groups: continuous use during 6 months (non‐renewal group) or a change in TB every 4 weeks during 6 months (renewal group). Each group was subdivided into four subgroups (groups A to H; n = 12 each) according to the head size (normal or short) and bristle hardness (medium or soft) of the TB used. The modified Quigley–Hein plaque index (QHI), papilla bleeding index (PBI), and gingival index (GI) were recorded at baseline and 2, 8, 12, 16, and 24 weeks after baseline. After 24 weeks, each participant received a new TB, and at week 26, the final QHI, PBI, and GI were determined. The statistical evaluation consisted of analysis of covariance (P <0.05). Results: With time, QHI, PBI, and GI were significantly different between the renewal and the non‐renewal groups (QHI: P = 0.02; PBI: P = 0.04; GI: P <0.01), independent of subgroup. In the renewal group, QHI showed a significant decrease between baseline and each follow‐up visit (P <0.01). In the non‐renewal group, there was a significant decrease compared to baseline up to and including week 16 (P <0.01). PBI in the renewal group showed no significant differences between baseline and each follow‐up visit (P >0.05). In the non‐renewal group, only the normal head/soft subgroup exhibited a significant increase at week 24 (P = 0.02). The GI in the renewal group showed no difference between baseline and all follow‐up visits, whereas in the non‐renewal group, there was a significant decrease up to and including week 12 (P <0.05). Conclusions: Six‐month continuous use reduced the effectiveness of the TB with respect to plaque removal, and gingival inflammation appeared to increase.