Age-related changes in ac-impedance spectroscopy studies of normal human dentine: further investigations

Abstract

One of the age-related changes occurring in dentine structure is the formation of peritubular dentine on the inner walls of dentinal tubules leading to complete closure of tubules. Ac-impedance is safe, fast and non-invasive technique. In the last decade, the popularity of the technique has increased in dental research. Several investigators have used the technique to detect tooth cracks and caries. The results of in vitro studies showed that ac-impedance technique was more advanced for caries detection than visual and radiographic methods. However, other studies demonstrated that the accuracy of impedance measurements can be affected by many factors such as remineralization after tooth eruption. A study has been published on effect of age on impedance measurements by the authors for two age groups by employing ac-impedance spectroscopy. Therefore, the aim of this study was to demonstrate the importance of this technique by conducting further investigations on dentine samples of wider age groups. Dentine samples were prepared from extracted sound third molars of known patient age. The ac-impedance measurements were carried out over a wide range of frequency. After performing all electrical measurements, dentine samples were examined under SEM to correlate the electrical measurements with their structure. Impedance measurements showed that there were differences in impedance between young and old dentine. One-way ANOVA of the means of resistance and capacitance for all age groups (20, 25, 30, 40 and 50 years old dentine) revealed a significant difference (ANOVA, P < 0.0001) as a function of age. Applying Tukey's post hoc test, to the same data showed that this difference was due to the 50 years old dentine for resistance and was due to the 40 and 50 years old dentine for capacitance which were statistically different to all other groups. SEM investigation of dentine samples showed that young dentine is characterized by open dentinal tubules distributed all over the sample while in old dentine most dentinal tubules were occluded by peritubular dentine. It is believed that this peritubular deposition is responsible for differences in impedance measurements. In spite of increasing use of electrical techniques to understand electrical properties of teeth, it is clear from this study that local structural variations have a marked influence.

Chemical and Ultramorphologic Effects of Ethylenediaminetetraacetic Acid and Sodium Hypochlorite in Young and Old Root Canal Dentin

“…Age-related physicochemical changes of dentin are characterized by continuous deposition of peritubular dentin, consequent narrowing of the dentinal tubules, and a decrease in the number of dentinal tubules (3)(4)(5)(6). Several studies have shown that the number and diameter of dentinal tubules play an important role in the effectiveness of irrigation solutions and adhesion of root canal sealers as well as on the depth of bacterial invasion (4,7,8).…”

In-Vivo Performance of the CarieScan Pro Device for Detection of Occlusal Dentine Lesions

“…Especially when using ACIST, for instance, the age of the patients is of decisive importance to the interpretation of the results of measurement: the diameter of the dentinal tubuli decreases significantly with age through the apposition of peritubular dentine. The dentine therefore contains fewer electrically conductive electrolytes, resulting in an overall higher resistance [26,27]. Among young patients, on the other hand, the post eruptive enamel maturation represents a measurable independent variable [8,28,29].…”

Influence of different irrigation protocols on microhardness and flexural strength values of young and aged crown dentin

“…Dentin is a complex hard tissue that comprises the bulk of the tooth and covers the dental pulp . Microtubules filled with dentinal fluid, odontoblastic process, mineralised intertubular dentin and highly mineralised peritubular dentin constitute the microstructure of dentin . With ageing, the thickness of the peritubular linings increase and reduction in the tubule lumen diameter begins .…”