The effect of different salivary calcium concentrations on the erosion protection conferred by the salivary pellicle

T Baumann,A Lussi,T S Carvalho,R Bereiter

doi:10.1038/s41598-017-13367-3

Abstract

Different proportions of mineral ions in saliva can influence the protective effect the salivary pellicle provides against dental erosion. To investigate the effect of different calcium concentrations in human saliva on the protection against enamel erosion, enamel specimens were divided into 8 treatment groups: humid chamber (Ctrl); whole mouth stimulated human saliva (HS); artificial saliva containing different calcium concentrations (ASlow, ASmedium, AShigh); and dialysed human saliva containing different calcium concentrations (DSlow, DSmedium, DShigh). The specimens underwent 4 cycles of incubation in the treatment group followed by an erosive challenge. Surface hardness and calcium release were measured during the cycling process. All DS groups exhibited significantly higher enamel surface softening than HS and the corresponding AS groups. Among the DS groups, the surface softening was significantly higher in DSlow than in DShigh. No significant differences were found within the AS or DS groups regarding calcium release. The results of this study indicated that erosion protection conferred by saliva depends on an interplay between salivary proteins and ions. While both proteins and ions have a positive effect on their own, the combination of the two can lead to different degrees of protection or even negative effects, depending on the relative concentrations.

Highlights

Erosive tooth wear (ETW) is described as the chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria[1]
The results show that each dialysed saliva group is significantly different from the artificial saliva with which it was dialysed (p < 0.02), in that the enamel specimens incubated with the different kinds of dialysed saliva had generally lower surface hardness (SH) values the specimens incubated in the corresponding artificial saliva (Fig. 2)
The erosion protection conferred by salivary pellicles depends on an interplay between salivary proteins and salivary ions

Summary

Introduction

Erosive tooth wear (ETW) is described as the chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria[1]. In addition to the ions, saliva protects from acidic challenges by forming a salivary pellicle on the tooth surface. The calcium-binding peptides present in the basal pellicle layer can bind free calcium ions from the surrounding saliva and act as a calcium reservoir in the salivary pellicle, allowing mineral homeostasis on the enamel surface[6]. Lussi et al showed that, in contrast to healthy individuals, patients with erosive demineralisation present a lower pH drop after an erosive attack and a reduced ability to reach initial pH conditions[9]. This could be related to the lower Correspondence and requests for materials should be addressed to T.B. (email: tommy.baumann@ zmk.unibe.ch) www.nature.com/scientificreports/

Methods

Results

Discussion

Conclusion