Root Cementum Surface Conditioning: Physicochemical and Morphological Alterations—An In Vitro Pilot Study

Resin infiltration of root cementum requires optimal surface preparation; however, traditional protocols using hydrochloric acid raise some concerns about potential cementum degradation. In this in vitro study the physicochemical and morphological impact of 36% H3PO4 on root cementum compared to natural demineralisation was evaluated to establish a candidate tissue-preserving conditioning agent. Twelve extracted teeth—incisors with exposed cementum over gum recession level and fully impacted third molars were analysed using scanning electron microscopy (SEM) and Energy Dispersive Spectrometry (EDS) in etched and not-etched specimens. Orthophosphoric acid significantly reduced calcium and phosphorus content across all specimens while maintaining overall morphological integrity. Notably, the elemental response varied based on tooth exposure history. Incisors exhibited a statistically significant reduction in the Ca/P atomic ratio, indicating complex stoichiometric shifts and preferential calcium loss. Conversely, impacted third molars maintained a stable Ca/P ratio, suggesting proportional mineral dissolution in unexposed cementum. These findings indicate that natural demineralisation is insufficient for adequate surface modification and that orthophosphoric acid demineralizes root cementum without compromising its structural integrity. The magnitude and pattern of this response depend on the tissue’s prior exposure to the oral environment; thus, structural heterogeneity of cementum, though tailored protocols, are necessary.