Newly developed hardness testing system, “Cariotester”: Measurement principles and development of a program for measuring Knoop hardness of carious dentin

Abstract

We previously discovered that when a cone-shaped indenter coated with paint was pressed into an object, the paint disappeared in accordance with the depth of the indentation. Based on this fact, we developed the Cariotester, a portable system for measuring the Knoop hardness (KHN) of carious dentin. The Cariotester is composed of a handpiece with an indenter, a microscope, and a computer. In this system, the painted indenter is forced into the material with a 150-gf load, and the indentation depth (CT depth) is obtained from the paint disappearance. The CT depth by the Cariotester and the KHN by a microhardness tester were determined at 14 dentin regions. From the data, a program was created to convert the CT depth of the carious dentin into the KHN. As a result, if the CT depth is measured with this system, the KHN of carious dentin can be displayed in real time.

A comparative study of the susceptibility of cut and uncut enamel to erosive demineralization

“…Recently, a newly developed hardness system to measure Knoop hardness has been introduced with the advantage that it is simple, quick and can be used to measure an unpolished surface 26) . In this study, this device was used to measure KHN of non-eroded and eroded surfaces of cut and uncut enamel samples.…”

Measurement of surface hardness of primary carious lesions in extracted human enamel —Measurement of Knoop hardness using Cariotester—

“…In any case, both of these methods have precluded the use of a microhardness tester to measure white spot surface hardness. The Cariotester, on the other hand, uses a novel method in which the indentation depth is determined by measuring the width of lost paint from the indenter 4) , thus enabling measurement of hardness on the outermost surface of the white spot.…”

Evaluation of a new hardness tester (Cariotester): Comparison with transverse microradiography for assessing the inhibitory effect of fluoride application on bovine root dentin demineralization

“…The hardness is calculated from the depth to which the indenter presses into the tooth surface. It also has the other advantages that one measurement only takes around 10 s to perform 12) , it can be used to measure hardness on non-flat tooth surfaces, and can be used intra-orally. The Cariotester is the world's first hardness tester that can be used at the chairside 12) .…”

“…It also has the other advantages that one measurement only takes around 10 s to perform 12) , it can be used to measure hardness on non-flat tooth surfaces, and can be used intra-orally. The Cariotester is the world's first hardness tester that can be used at the chairside 12) . Featherstone et al reported that there is a linear relationship between the square root of the Knoop hardness of demineralized dentin and mineral density measured by transverse microradiography (TMR), which is regarded as the gold standard [15][16][17] .…”

“…ECM provides good inter-examiner reproducibility, but similar to the DIAGNOdent, the correlation between ECM values and root caries progression is not strong enough 10) . In 2009, Shimizu et al 12) developed the Cariotester (SUK-971, SaneiME, Yokohama, Japan) as a hardness tester for the tooth structure, and it was used in studies Evaluation of a new hardness tester (Cariotester): Comparison with transverse microradiography for assessing the inhibitory effect of fluoride application on bovine root dentin demineralization by Utaka et al 13) and Iwami et al 14) . The Cariotester system is a small, portable device that uses a simple measurement principle and is easy to operate.…”