Bone Abstracts

Tooth fracture is considered as a major problem in dentistry. As it is commonly observed in dental practice, one of the main factors that lead to increased tooth fragility is its devitalization. However, there is no definite mechanistic explanation for such phenomenon. We hypothesize that the possible response to this matter lies in the changes that occur in dentin due to altered microenvironment after endodontic procedure. Therefore, in this study we analyzed the structural and compositional differences between vital and devitalized dentine.

Atomic force microscopic imaging (AFM), and micro-Raman spectroscopy were performed on 16 dentine specimens, eight taken from vital teeth and eight taken from teeth that underwent root-canal treatment at least 2 years before extraction and had no infection in root canals. All teeth were upper premolars.

The mean size of mineral grains, showed by AFM topography images, was larger in devitalized than in healthy dentine in the same age category. AFM phase shifts in devitalized cases revealed altered mechanical characteristics and suggested differences in composition of material between devitalized teeth and healthy controls. Micro-Raman analyses showed that in devitalized teeth, apart from hydroxyapatite, dentine contained significant amounts of apatite phases with lower calcium content: octacalcium phosphate, dicalcium phosphate dihidrate and tricalcium phosphate.

Differences between vital and devitalized dentine bring new insight into basis of devitalized tooth fragility. Larger mineral grains could account for decreased mechanical strength in devitalized teeth. Moreover, calcium-phosphate phases with lower Ca content have lower material strength, and the presence of these phases in devitalized teeth may explain their increased fragility.