In vivo and in vitro radiotherapy increased dentin enzymatic activity

Area of Science:

• Biochemistry
• Dental Research
• Radiology

Background:

• Endogenous enzymatic activity in dentin plays a role in its structural integrity.
• Radiotherapy can potentially affect biological tissues, including dental structures.

Purpose of the Study:

• To investigate the impact of in vitro and in vivo radiotherapy on endogenous enzymatic activity in human dentin.
• To compare the effects of different radiotherapy exposure methods on dentin's enzymatic profile.

Main Methods:

• Gelatin zymography was used to analyze protein extracts from non-irradiated (NRT), in vitro irradiated (VTRT), and in vivo irradiated (VIRT) human dentin.
• In-situ zymography with fluorescein-conjugated gelatin and confocal laser-scanning microscopy assessed enzymatic activity directly within dentin specimens.
• Densitometric and fluorescence intensity analyses quantified proteolytic activities, with statistical analysis using Kruskal-Wallis ANOVA and Dunn's test.

Main Results:

• No significant difference in enzymatic activity was observed between in vitro and in vivo radiotherapy treatments.
• Both VTRT and VIRT groups exhibited increased matrix metalloproteinase-9 (MMP-9) expression compared to the NRT group.
• Significant increases in gelatinolytic activity were noted: 26% for VTRT and 55% for VIRT, relative to NRT.

Conclusions:

• Radiotherapy demonstrably increases endogenous enzymatic activity in non-restored dentin.
• MMP-9 expression and gelatinolytic activity are elevated following both in vitro and in vivo radiotherapy exposure.
• These findings highlight the biochemical changes in dentin induced by radiotherapy.