The combined approach to evaluation of mechanical behavior of tooth enamel in artificially induced caries lesions

Abstract

Improved knowledge of caries initiation and progression on the base of modern mechanobiology could facilitate effective preventing and therapeutic strategies. Not all of previously developed experimental models of artificial caries comply with required standards. The aim of the study was to investigate microstructural and mechanical properties of 12 artificial caries lesions, induced on human intact premolars according to original protocol. The tooth specimens were subjected to imaging by X-ray CT system Nikon Metrology XT H 225, with further morphometric analysis of lesion geometry, depth, surface layer thickness and mineral density in the areas of interest. Mechanical characteristics (penetration depth, microhardness, elastic modulus) in enamel lesion, perifocal intact enamel and remote zones were obtained using Micro CombiTester system. Clinically all lesions fully corresponded to ICDAS – 2 code. According to µCT data, LDµCT of the lesions ranged from 346.4 to 531 µm, mineral density range from 2.03±0.15 g/cm3 in transparent zone to 1.05±0.08 g/cm3 in the surface zone of the lesion. Microhardness of demineralized enamel lesion more than 5 times reduced in comparison with perifocal and remote intact enamel. Nanoindentation and µCT data are corresponds to those presenting on the base of other classical protocols of artificial caries formation and close to the typical mechanical characteristics of enamel caries in vivo.