Journal of dentistry ·8 Nov 2026 ·Added 10 Nov 2026

Effects of different toothpaste formulations on surface microhardness and gelatinolytic activity in healthy and post-radiotherapy dentin: an in vitro study.

Marina Ciccone Giacomini, Hugo Bertoni Braga, Júlia Alcântara Martins, Camily Bocardo Rodrigues, Márcia Sirlene Zardin Graeff, Sérgio Kiyoshi Ishikiriama, Linda Wang

DOI ↗

Abstract

OBJECTIVES: Patients undergoing head-and-neck radiotherapy are at high risk of progressive damage to dental tissues, urging the need for preventive and therapeutic strategies. Distinct active ingredients have been incorporated into toothpastes to contribute to this goal. This in vitro study evaluated the effects of five toothpastes formulations on surface microhardness (SM) and gelatinolytic activity by in situ zymography (Z), and surface characteristics of healthy and post-radiotherapy human dentin. MATERIALS AND METHODS: 110 human molars were randomized according to dentin condition: healthy (H) or post-radiotherapy (PR - total dose of 70 Gy; 35 sessions/2 Gy/7 weeks). Specimens were further allocated according to toothpaste: Colgate Total 12 (CT), Clinpro 5000 (CP), Elmex Opti-Enamel (E), Biomin (B), and 5% S-PRG paste (S). A 1:3 slurry was actively applied (15 s), left undisturbed (45 s) and rinsed (5 s). SM tests (n=10; KHN; 10 g; 10 s) were performed before and after application. For Z (n=5), 0.1-mm-thick dentin slices were incubated with fluorescein-conjugated gelatin for 48 h at 37°C. Surface was characterized trough Confocal Laser Scanning Microscopy (CLSM/n=2) and Scanning Eletronic Microscopy/ (SEM)/ Energy dispersive X-Ray Spectroscopy (EDS/n=3). Data were analyzed using repeated-measures three-way ANOVA for SM and two-way ANOVA for Z. RESULTS: Radiotherapy reduced SM, while all toothpastes were able to partially recover the microhardness. Reduced gelatinolytic activity was observed for PR compared with H dentin. Distinct patterns of tubule obliteration were observed for both conditions. CONCLUSIONS: Radiotherapy alters the properties of dentin, and toothpastes may partially mitigate these effects. CLINICAL RELEVANCE: Toothpastes containing active compounds might represent an affordable preventive strategy to reduce dentin degradation in patients undergoing head-and-neck radiotherapy.