Influence of highly concentrated fluoride dentifrices on remineralization characteristics of enamel in vitro

R J Wierichs; S Westphal; J Lausch; H Meyer-Lueckel; M Esteves-Oliveira

doi:10.1007/s00784-018-2333-1

Influence of highly concentrated fluoride dentifrices on remineralization characteristics of enamel in vitro

Clin Oral Investig. 2018 Jul;22(6):2325-2334. doi: 10.1007/s00784-018-2333-1. Epub 2018 Jan 17.

Authors

R J Wierichs^{1

2}, S Westphal³, J Lausch³, H Meyer-Lueckel^{3

4}, M Esteves-Oliveira³

Affiliations

¹ Department of Operative Dentistry, Periodontology and Preventive Dentistry, RWTH Aachen University, Pauwelsstr. 30, 52074, Aachen, Germany. rwierichs@ukaachen.de.
² Department of Biohybrid & Medical Textiles, Institute of Applied Medical Engineering, RWTH Aachen University, Aachen, Germany. rwierichs@ukaachen.de.
³ Department of Operative Dentistry, Periodontology and Preventive Dentistry, RWTH Aachen University, Pauwelsstr. 30, 52074, Aachen, Germany.
⁴ Department of Restorative, Preventive and Pediatric Dentistry, zmk bern, University of Bern, Bern, Switzerland.

PMID: 29344804
DOI: 10.1007/s00784-018-2333-1

Abstract

Objectives: The aim of this in vitro study was to evaluate the role of highly fluoridated dentifrice on remineralization characteristics of lowly and highly pre-demineralized enamel artificial caries lesions.

Methods: Bovine enamel specimens were prepared (pH 4.95; 21 days) and discriminated in either lowly [L] or highly [H] pre-demineralized artificial caries lesions. Specimens with a mean ΔZ_baseline,L (95% CI) of 5120 (4995; 5245) vol.% × μm and a mean ΔZ_baseline,H of 8187 (8036; 8339) vol.% × μm were selected and randomly allocated to 12 groups (n = 20). Treatments during pH-cycling (28 days; 6 × 60 min demineralization/day) were brushing 2×/day with fluoride-free (0 ppm F^- [L₀/H₀]), 1100 ppm F^- [L₁₁₀₀/H₁₁₀₀], 2800 ppm F^- [L₂₈₀₀/H₂₈₀₀], 5000 ppm F^- [L₅₀₀₀/H₅₀₀₀], 5000 ppm F^- + glycerin [L_{5000 + glycerin}/H_{5000 + glycerin}], and 5000 ppm F^- + TCP [L_{5000 + TCP}/H_{5000 + TCP}] containing dentifrices. Dentifrice slurries were prepared with deionized water (1:3wt/wt). After cycling specimens presenting lesion surface loss were discarded and for the remaining 202 specimens, transversal microradiographic (TMR) analyses (ΔZ_pH-cycle/LD_pH-cycle) were performed again. Changes in mineral loss (ΔΔZ = ΔZ_baseline - ΔZ_pH-cycle) and lesion depth (ΔLD = LD_baseline - LD_pH-cycle) were calculated.

Results: Significant differences for ΔΔZ could be found between L₀, L₁₁₀₀, and L₅₀₀₀ as well as H₀, H₁₁₀₀, and H₂₈₀₀/H₅₀₀₀ (p ≤ 0.01; ANCOVA). Except for 0 ppm F^-, higher ΔΔZ could be found in highly compared with lowly demineralized specimens (p ≤ 0.004; ANCOVA). After pH-cycling, a second lesion front could only be observed in H₅₀₀₀ and H_{5000 + TCP}. The correlation between ΔΔZ and F^- was moderate for lowly and highly demineralized lesions (r_L = 0.591; p_L < 0.001; r_H = 0.746; p_H < 0.001), indicating a fluoride dose response for both.

Conclusion: For both baseline substrate conditions, a dose response for fluoride could be revealed.

Clinical significance: Remineralization characteristics of enamel directly depended on baseline mineral loss.

Keywords: Enamel caries; Fluoride; Non-cavitated caries lesions; Remineralization; Toothpastes; pH-cycling.

MeSH terms

Animals
Cattle
Dental Enamel / chemistry*
Dentifrices / chemistry*
Fluorides / chemistry*
Hydrogen-Ion Concentration
In Vitro Techniques
Random Allocation
Tooth Remineralization*

Substances

Dentifrices
Fluorides