Removal of caries dentin by various dental cutting burs

Objectives: To avoid over-excavation of caries dentin, polymer bur and stainless burs have been developed. We developed new caries detecting agent composed of poly-propylene glycol not to stain the sclerotic dentin. The purpose of this study was to evaluate cutting ability of various burs by examining the characteristics of dentin surface after removal of the caries dentin.

Methods: A tungsten carbide bur (GmbH & Co KG, Germany), polymer bur (Smart Prep, SS White, USA), experimental stainless burs (hexagonal or octagonal bur with and without blade) (MANI Inc, JAPAN) were employed. Sixty extracted human teeth with dentin caries were used. The teeth were longitudinally sectioned through the center of the caries and the Micro-Vickers Hardness (MVH) was measured from the pulpal wall to caries cavity every 200µm. After removal of caries dentin by using the various burs, the dentin hardness of the cavity wall was reconfirmed by observing MVH indentations and DIAGNOdent (Kavo, Germany) value (D-value) was measured. For the control, the caries dentin was removed by steel bur according to the Caries Check (Nishika, Japan) staining. The results obtained were analyzed statistically by Kruskal-Wallis Test (p<0.05).

Results: The MVH and D-value of the dentin cavity wall after cutting the caries dentin by using the polymer bur and octagonal stainless bur without blade were significantly lower than control group. The MVH of the hexagonal stainless bur without blade, stainless burs with blade and tungsten carbide bur groups were insignificantly different with that of the control. However, D-values of these groups were significantly lower than that of the control.

Conclusion: It should be recommended to remove the caries dentin according to the caries detecting agent staining to avoid over-excavating the dentin when the stainless bur with blade and tungsten carbide bur were clinically used.