A New pH-Cycling Dental Erosion Model Demonstrates Fluoride Effect

Laboratory models examining enamel erosion have generally used only acid challenge without incorporating a remineralization phase.  Objective: To evaluate the ability of a new dental erosion model, that incorporated a remineralization phase, to assess the capability of fluoride (F) dentifrice to inhibit erosion.  Methods: Crowns of human molars (6/group) were subjected to alternating erosive acid buffer (4 x 30 min daily), mineralizing solution (4 x 30 min daily) and remineralization nightly (18 hr, pH 7, Ca/P), with or without F-dentifrice treatment (1:3 slurry in DDW, 4 x daily for 1 min.) for a total of 5 days. Erosive buffers were citrate pH=3.5, citrate pH=3.9, phosphoric acid pH=2.4, and grapefruit juice pH=3.4.  Dentifrices were NaF (1100 ppm F) with/without sodium tripolyphosphate (STPP). Erosion depths were assessed on thin sections under polarized light.  Results: Mean ± SD depths (micrometers) were:

Statistically citrate(3.5)>[citrate(3.5)+NaF]=[citrate(3.5)+NaF/STPP] and citrate(3.9)>[citrate(3.9)+NaF]=[citrate(3.9)+NaF/STPP] (p<0.05 ANOVA/Newman-Keuls) with the F dentifrices producing approximately 50% inhibition of erosion against citrate. Conclusions: This new pH cycling enamel erosion model produces erosion comparable to grapefruit juice and shows a marked fluoride effect. Supported by a grant from GlaxoSmithKline.