High and low brushing force in relation to efficacy and gingival abrasion

Does a high brushing force induce more gingival abrasion than a low (regular) brushing force? Furthermore, what is the effect of a low or high force on the efficacy?

Thirty-five non-dental students were selected. All received an appointment prior to which they abstained from oral hygiene for at least 48 h. At baseline the teeth and surrounding tissues were disclosed using Mira-2-Tone disclosing solution. Next, the examiner (PAV) evaluated the number of sites with gingival abrasion and the amount of dental plaque (Quigley & Hein) at 6 surfaces of each tooth. In the absence of this examiner, the subject's teeth were brushed by a hygienist (MP) using the Braun/Oral-B-D17 oscillating rotating toothbrush. Brushing was performed in two randomly selected contra-lateral quadrants for 60 s with either a low force (+/-1.5 N) or high force (+/-3.5 N) and in the opposing quadrants for 60 s with the alternative force. Visual feedback was given to control force. The brush was moved from the distal tooth to the central incisor perpendicular to the tooth surface with an angle of approximately 10-15 degrees towards the gingival margin. Next, the number of sites with abrasion and the remaining plaque were assessed again.

The overall baseline gingival abrasion scores were 3.1 and 3.2 sites for high and low force, respectively, and increased to 5.0 and 5.9 sites respectively after brushing. There was no significant difference with respect to incidence of abrasion. At baseline, 48 h. plaque levels were 2.2. The reduction in plaque scores with the low force was 60% and with the high force 56%. This difference was significant.

With the oscillating rotating power toothbrush (Braun/Oral-B D17) the use of high force (+/-3.5 N) is less efficacious as compared to a regular low force (+/-1.5 N) while the incidence of gingival abrasion sites was comparable.