The Whitening Effect and Histological Safety of Nonthermal Atmospheric Plasma Inducing Tooth Bleaching

Various light sources have been applied to enhance the bleaching effect. This study was to identify the histological evaluation in oral soft tissues, as well as tooth color change after tooth bleaching by nonthermal atmospheric pressure plasma (NAPP). Nine New Zealand adult female rabbits were randomly divided into three groups (n = 3): group 1 received no treatment; group 2 was treated with NAPP and 15% carbamide peroxide (CP), which contains 5.4% H₂O₂, and group 3 was treated with 15% CP without NAPP. Color change (ΔE) was measured using the Shade Eye NCC colorimeter. Animals were euthanized one day later to analyze the histological responses occurring in oral soft tissues, including pulp, gingiva, tongue, buccal mucosa, and hard and soft palates. Changes in all samples were analyzed by hematoxylin and eosin staining and Masson's trichrome. Teeth treated with plasma showed higher ΔE than that obtained with bleaching agents alone. Overall, the histological characteristics observed no appreciable changes. The combinational treatment of plasma had not indicated inflammatory responses as well as thermal damages. NAPP did not cause histological damage in oral soft tissues during tooth bleaching. We suggest that NAPP could be a novel alternative energy source to conventional light sources for tooth bleaching.

A Review of External Cervical Resorption

External cervical resorption (ECR) is a relatively uncommon yet aggressive form of dental hard tissue destruction. It is initiated at the cervical aspect of the root surface and extends apicocoronally and circumferentially inside the dentin. Despite the large number of case reports and clinical studies that have investigated ECR, its etiology remains unclear. Recent advancements in clinical assessment measures, such as the use of cone-beam computed tomographic imaging, have provided additional insights into the nature of this lesion. This has facilitated the continued development and improvement of treatment methods for this condition. In this article, we provide an overview of the latest research pertaining to the etiology, histopathology, predisposing factors, diagnosis, classification, and treatment of ECR. Furthermore, we provide a summary of the different classification schemes for ECR and highlight the relevant therapeutic principles.