Objective: A new polymer bur, a novel enzymatic approach to remove carious dentin and a chemomechanical caries treatment were compared using nanohardness profiles of tooth slices to compare the different treatment groups.

 

Methods: 9 carious molars with large cavities were used. The teeth were sectioned into 200 µm thick slices. The slices from each cavity were assigned, based on a latin-square, to the different treatment groups. The treatment groups were a prototype enzyme solution (SFC-III, 3M ESPE AG) which specifically cleaves denatured dentinal collagen and is applied with a polymer brush vs. the control group Carisolv II which non-specifically cleaves dentinal collagen and is combined with blunt steal hand excavators. In addition a novel polymer-based bur (Smartbur, SS White Burs) was used. Nanohardness profiles were measured in sound dentin and carious dentin from the pulp to the surface of the teeth with a Fischerscope H100C automatic hardness measuring device (Fischer, Sindelfingen, Ger). The distance between two measuring points was 29 µm. Descriptive statistics was complemented with ANOVA and the Tukey post-hoc-test.

 

Results: The mean hardness data based on the average of three measurement points below the carious dentin surface is summarized in the table. The total mean surface hardness of sound dentin at a comparable location was 65 (12) HV. Because of the high coefficient of variation no significant differences could be calculated.

Treatment	Mean (SD) [HV]	Percentage relative to sound dentin
SFC-III + polymer brush	26.0 (16.9)	40
Carisolv II + blunt steal instrument	27.4 (17.5)	42
Smartbur	37.6 (19.4)	58

Conclusions:

Based on the rank order relative to sound dentin the enzymatic and Carisolv II removal of carious dentin is less invasive compared to the Smartbur group. However, because of the large variation of carious dentin no significant differences could be found.