hydroxyethylcellulose and Dental-Caries

Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

Topics: Animals; Carboxymethylcellulose Sodium; Cariostatic Agents; Cattle; Cellulose; Dental Caries; Dental Enamel; Dentifrices; Gels; Methylcellulose; Microradiography; Minerals; Protective Agents; Random Allocation; Saliva, Artificial; Sodium Fluoride; Tooth Abrasion; Tooth Remineralization; Toothbrushing

Microhardness measurements with the indenter load perpendicular to the artificial carious enamel surfaces can be employed to investigate lesion depth in de- and remineralization of fluoridation studies in vitro or in vivo. In this study, microhardness and lesion depth studies were made on bovine enamel subjected to demineralizing solutions on a gelatin base at pH = 4.5 and 37 degrees C. The parameters studied were load, demineralization period and dialysis of the gelatin. All experimental data are compared with lesions formed in acidified 6% HEC solutions under identical conditions. The results show that lesion formation and mechanical properties of artificially carious enamel are comparable for nonchared HEC and charged gelatin based systems. Because of the higher sensitivity, lesions formed in HEC are to be preferred for lesion depth determinations by means of microhardness indentations. Both gelatin - and HEC based systems show a lesion depth proprotional to the square root of the demineralization period. If gelatin or HEC is dialyzed first, and subsequently used in the demineralizing buffers, the results show that no subsurface lesions are formed but "acid-softening" of the enamel takes place.

Topics: Animals; Cattle; Cellulose; Dental Caries; Dental Enamel; Dental Stress Analysis; Gels; Hardness; Hydrogen-Ion Concentration; Lactates