Frequency of gingival lesions after standardized brushing as related to stiffness of toothbrush and abrasiveness of dentifrice.

The clinical trial was primarily designed to determine to what extent the stiffness of toothbrush bristles and the abrasiveness of dentifrices influence the degree of gingival erosion. Further, the plaque removing effectiveness of the toothbrushes and dentifrices tested was evaluated. 24 dental hygienist students with clinically healthy gingivae volunteered for the study. A "soft" toothbrush with a bristle thickness of 0.15 mm, a "hard" toothbrush with a bristle thickness of 0.23 mm and 2 dentifrices of different abrasiveness were used for the experiment. The 2 brushes were also used without a dentifrice. Prior to each examination the teeth of the test subjects were brushed by the same dental hygienist. Evident signs of laceration or.ulceration at any 1 of 4 gingival aspects of each tooth were recorded as brushing injuries. The teeth were then stained with basic fuchsin and the amount of remaining plaque was assessed according to the PLQ Index (Bay & Ainamo 1974). The use of the hard brush resulted in lower plaque scores and, at the same time, more gingival erosions than the use of the soft brush. With both brushes a significantly greater number of lesions was recorded after use of an abrasive powder than when no dentifrice was employed. The difference in the amount of erosions occurring when utilizing either brush, without a dentifrice or with a moderately abrasive toothpaste, was not, however, found to be statistically significant. When assessed separately for the 2 brushes, the slight tendency towards lower PLQ scores with increasing abrasiveness of the dentifrice was not considered statistically significant. The study showed that the modes decrease observed in mean PLQ scores with increasing stiffness of the toothbrush bristles and with increasing abrasiveness of the dentifrice is accompanied by increased damage caused to the soft gingival tissues.