title: In vitro Induction of residual caries lesions in dentin: comparative mineral loss and nano-hardness analysis.
abstract: Artificially inducing dentinal lesions mimicking those remaining after selective excavation should allow to investigate the effects and limits of such selective excavation, for example regarding the mechanical properties of treated teeth or the remineralisation of sealed residual lesions. Such analyses might otherwise be limited by the variability of natural lesions or ethical and practical concerns. This study compared different demineralisation protocols for their suitability to induce lesions similar to natural residual caries. Twelve natural deep lesions were excavated until leathery dentin remained, and analysed for their mineral loss (ΔZ), lesion depth (LD), mineral loss ratio (R), the slope of the mineral gradient and their nano-hardness profile. Artificial lesions were induced using four different demineralisation protocols (acetic acid pH = 4.95; 0.1 M lactic acid gel pH = 5.0; 0.5 M ethylenediaminetetraacetic acid pH = 7.2; Streptococcus mutans biofilms) and their depths monitored over different demineralisation times. Lesions with depths most according to those of natural lesions were analysed using transversal microradiography. Lesions induced by acetic acid solution did not significantly differ with regards to LD, ΔZ, R and mineral profile. Seven dentin specimens were subsequently submitted to a moderately acidic (pH = 5.3) methylhydroxydiphosphonate-buffered acetate solution for 12 weeks. Natural and artificial residual lesions were similarly deep (mean ± SD: LD = 626 ± 212 and 563 ± 88 µm), demineralised (R = 19.5 ± 4.7 and 29.8 ± 4.1%), showed a flat and continuous mineral gradient (slope = 0.10 ± 0.05 and 0.13 ± 0.06 vol%/µm) and did not significantly differ regarding their nano-hardness profile. The described protocol induces lesions with mineral content and mechanical properties similar to natural residual lesions.
authors.affiliation: Department of Operative and Preventive Dentistry, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Schwendicke
authors.forename: Kerrin
authors.initials: K
authors.lastname: Eggers
authors.forename: Hendrik
authors.initials: H
authors.lastname: Meyer-Lueckel
authors.forename: Christof
authors.initials: C
authors.lastname: Dörfer
authors.forename: Alexander
authors.initials: A
authors.lastname: Kovalev
authors.forename: Stanislav
authors.initials: S
authors.lastname: Gorb
authors.forename: Sebastian
authors.initials: S
authors.lastname: Paris
mesh_terms: D019342:Acetic Acid / Q000009:adverse effects; D018441:Biofilms; D019343:Citric Acid / Q000009:adverse effects; D003731:Dental Caries / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D003804:Dentin / Q000737:chemistry / Q000473:pathology*; D004164:Diphosphonates / Q000009:adverse effects; D004492:Edetic Acid / Q000009:adverse effects; D055119:Elastic Modulus; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D019344:Lactic Acid / Q000009:adverse effects; D008852:Microradiography / Q000379:methods; D008903:Minerals / Q000032:analysis; D013295:Streptococcus mutans / Q000502:physiology; D013997:Time Factors; D017001:Tooth Demineralization / Q000378:metabolism / Q000382:microbiology / Q000473:pathology
chemical_list: D004164:Diphosphonates; D008903:Minerals; C029285:hydroxymethanediphosphonic acid; D019343:Citric Acid; D019344:Lactic Acid; D004492:Edetic Acid; D019342:Acetic Acid