Radiation-related caries is a unique form of rampant decay and is a complication of head and neck radiotherapy that frequently causes generalized dental destruction and impairs quality of life in cancer patients. The aim of this study was to investigate the patterns of demineralization of caries in irradiated patients and to establish whether direct radiogenic damage to the dentition might be important in the progression of radiation-related caries. Teeth from patients who had concluded radiotherapy were examined histologically by polarized light microscopy, and the ultrastructure was examined by scanning backscattered electron microscopy. Cervical caries and incisal caries, a very unusual sort of lesion, were widely detected. Additionally, diffuse brown discoloration of the smooth surface of enamel was frequently observed. Polarized light microscopy suggested that these areas were incipient caries. Evidence of normal odontoblast function was observed in the detection of reactionary dentin and intratubular dentin deposition. In conclusion, radiation-related caries seems to have the same morphological and demineralization pattern as ordinary caries, with the presence of demineralized dentin, a translucent zone, dentin dead tracts, reactionary dentin and intratubular dentin deposition. Based on these findings, direct radiogenic destruction of the teeth seems to be not essential to the microscopic progression of radiation-related caries.

Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties of tissue for potential preventive or reparative/regenerative therapies. The objectives of the study were to systematically characterize dentin matrices biomodified by proanthocyanidin-rich grape seed extract (GSE) and glutaraldehyde (GD). Changes to the biochemistry and biomechanical properties were assessed by several assays to investigate the degree of interactions, biodegradation rates, proteoglycans interaction, and effect of collagen fibril orientation and environmental conditions on the tensile properties. The highest degree of agent-dentin interaction was observed with GSE which exhibited the highest denaturation temperature, regardless of the agent concentration. Biodegradation rates remarkably decreased following biomodification of dentin matrices after 24hs collagenase digestion. A significant decreased in the proteoglycans content of GSE treated samples was observed using a micro-assay for glycosaminoglycans and histological electron microscopy, while no changes were observed for GD and control. Tensile strength properties of GD biomodified dentin matrices were affected by dentin tubule orientation, most likely due to the orientation of the collagen fibrils. Higher and/or increased stability of the tensile properties of GD and GSE-treated samples were observed following exposure to collagenase and 8 month water storage. Biomodification of dentin matrices using chemical agents not only affects the collagen biochemistry; it also involves interaction with proteoglycans. Tissue biomodifiers interact differently with dentin matrices and may provide the tissue with enhanced preventive and restorative/reparative abilities.

Purpose. This study investigated the long-term resin-dentin bond strength of dentin biomodified by proanthocyanidin-rich (PA) agents. Materials and Methods. Forty molars had their coronal dentin exposed, etched, and treated for 10 minutes with 6.5% grape seed extract (GSE), 6.5% cocoa seed extract ethanol-water (CSE-ET), 6.5% cocoa seed extract acetone-water (CSE-AC), and distilled water (CO). Samples were restored either with One-Step Plus (OS) or Adper Single-Bond Plus (SB). Bond strength test was performed immediately or after 3, 6, and 12 months. Results. Higher μTBS were observed for GSE immediately (SB- 62.9 MPa; OS- 51.9 MPa) when compared to CSE-ET (SB- 56.95 MPa; OS- 60.28 MPa), CSE-AC (SB- 49.97 MPa; OS- 54.44 MPa), and CO (SB- 52.0 MPa; OS- 44.0 MPa) (P < 0.05). CSE outcomes were adhesive system and solvent dependant. After 12 months storage SB results showed no difference among treatment types (GSE- 57.15 MPa; CSE/ET- 54.04 MPa; CSE/AC- 48.22 MPa; CO- 51.68 MPa; P = 0.347),while OS results where treatment dependent (GSE- 42.62 MPa; CSE/ET- 44.06 MPa; CSE/AC- 41.30 MPa; CO- 36.85 MPa; P = 0.036). Conclusions. GSE and CSE-ET agents provided enhanced immediate adhesion and stabilization to demineralized dentin after long-term storage, depending on adhesive system.

Head and neck radiotherapy did not affect dentin bond strength for the adhesive materials tested in this study.