“…However, Aas (1963) found no statistically significant relationship between IQ and level of oral hygiene, but reported a statistically significant correlation between severity of inflammation and severity of gum overgrowth, a finding corroborated by the present investigation. Glickman & Lewitus stated in 1941 that focal irritation is a secondary phenomenon; in the interim, well controlled experiments in tnan, in monkeys and in cats have demonstrated that in the absence of the frank irritation and ensuing inflammation caused by plaque, PHT induced gingival overgrowth can be minimized (Hall 1969, Nuki & Cooper 1972, King et al 1976, Staple & Reed 1976, Pihistrom et al 1980, Steinberg & Steinberg 1982. Furthermore, patients without teeth, and thus without gingival sulci which harbor plaque, almost never develop the lesions (Glickman & Lewitus 1941, Ziskin et al 1941, Aas 1963).…”