Eroded enamel lesion remineralization by saliva as a possible factor in the site-specificity of human dental erosion

The composition and flow of saliva, which determine its functions, vary within intraoral sites and among individuals. Also, the susceptibility to tooth erosion reportedly varies among individuals and within the dental arches. A possible effect of saliva on early-eroded lesions may be a contributory factor. The aims here were firstly to determine the remineralization of eroded enamel lesions by saliva, and secondly to investigate any variation of this remineralization within the dental arches and among individuals. Early enamel erosion was produced on human premolars using orange juice. Control sections and two test slabs were cut from each tooth. The two slabs from the same lesion were bonded with composite resins to the palatal surface of upper right lateral incisor teeth and the lingual surface of the lower right lateral incisor teeth of volunteers, who then chewed a sugar-free gum four times daily. After 28-day intraoral exposure, mineral loss (ΔZ) and lesion depth (ld) were quantified using microradiography and the data analysed by paired t-test (n = 10, α = 0.05). Mean ΔZ was significantly lower in the group of slabs positioned palatally (P < 0.001) and lingually (P < 0.001) when compared with the control group, and in the lingually placed group when compared with the palatally positioned (P < 0.01). A significantly lower ld was observed in the group of slabs positioned palatally (P < 0.05) and lingually (P < 0.001) when compared with the control group, and in the lingually positioned group when compared with the palatally placed (P < 0.05). It was concluded that saliva can remineralize early enamel erosion, and that the degree of remineralization varies within intraoral sites and may be responsible for the differing susceptibility to erosion within the dental arches.