Ex vivo investigation on internal tunnel approach/internal resin infiltration and external nanosilver-modified resin infiltration of proximal caries exceeding into dentin

Abstract

This ex vivo proof-of-concept study aimed to investigate the effect of nanosilver particles (AgNP) added to a conventional infiltrant resin (Icon) on external penetration into natural proximal enamel caries exceeding into dentin after internal tunnel preparation and internal infiltration. Carious lesions (ICDAS codes 2/3) of extracted human (pre-)molars revealing proximal caries radiographically exceeding into dentin (E2/D1 lesions) were preselected. Then, 48 of those specimens showing demineralized areas transcending the enamel-dentin border as assessed by means of near-infrared light transillumination (DIAGNOcam) were deproteinized (NaOCl, 5%). Using an internal tunnel approach, occlusal cavities central to the marginal ridge were prepared. Excavation of carious dentin, total etch procedure (H 3 PO 4 , 40%), and internal resin infiltration (FITC-labeled) followed, along with final restorations (flowable composite resin). Outer lesion surfaces were etched (HCl, 15%) prior to external infiltration (RITC-labeled). Group 1 (control; n = 24) used non-modified infiltrant, while an infiltrant/ AgNP mixture (20 nm; 5.5 wt%) was used with experimental Group 2 (n = 24). Non-infiltrated pores of cut lesions were stained (Berberine), and specimens were analyzed using confocal laser scanning microscopy. Compared to the non-filled infiltrant, incorporation of AgNP had no effect on the resin's external penetration. Between the groups, no significant differences regarding internal or external infiltration could be detected, and non-infiltrated lesion areas did not differ significantly (p>0.109; t-test). The internal tunnel preparation in combination with both an internal resin infiltration and an additional external infiltration approach using a nanosilver-modified infiltrant resin leads to increased infiltrated lesion areas, thus occluding and adhesively stabilizing the porous volume of the demineralized enamel. While exerting antimicrobial effects by the nanosilver particles, this approach should have the potential as a viable treatment alternative for proximal lesions extending into dentin, thus avoiding the sacrifice of sound enamel, postponing the frequently inevitable restoration/re-restoration cycle of conventional proximal caries treatment, and improving dental health.

3D imaging of proximal caries in posterior teeth using optical coherence tomography

“…Despite all the caries used in this study were natural caries on smooth tooth surface, it should be noted that many of the cases were located near or under the proximal contacts. It is probably because between the contact point and the top of the free gingival margin is the high risk for caries at smooth enamel surface 7,56,57 . While root caries at interproximal surface was not included in this study, different scanning protocol appears necessary for the imaging of root caries.…”

“…In the early stages, the demineralization process can be reversed in the presence of bioavailable calcium, phosphate and fluoride ions in the oral environment 6 . For the surface enamel lesions, infiltration of low-viscosity resin can also be an option as a micro-invasive approach to inhibit further demineralization and to arrest lesion progress 4 , 7 .…”

Ionic liquid-loaded microcapsules doped into dental resin infiltrants

“…Antimicrobial agents have been added to resin infiltrants to improve their biological properties and increase their protective effect. Previous studies incorporated silver nanoparticles (AgNP) [ 15 ], quaternary ammonium methacrylate [ 16 ], cationic molecules [ 17 ], and chlorhexidine into resin infiltrants formulation. AgNP were incorporated into a commercial infiltrant at 5.5 wt% and tested regarding enamel's penetrability [ 15 ].…”

“…Previous studies incorporated silver nanoparticles (AgNP) [ 15 ], quaternary ammonium methacrylate [ 16 ], cationic molecules [ 17 ], and chlorhexidine into resin infiltrants formulation. AgNP were incorporated into a commercial infiltrant at 5.5 wt% and tested regarding enamel's penetrability [ 15 ]. In this ex vivo study, AgNP did not alter the infiltration on proximal enamel caries [ 15 ].…”

“…AgNP were incorporated into a commercial infiltrant at 5.5 wt% and tested regarding enamel's penetrability [ 15 ]. In this ex vivo study, AgNP did not alter the infiltration on proximal enamel caries [ 15 ]. Cationic molecules such as dimethylaminododecyl methacrylate (DMADDM) [ 16 ], guanidine hydrochloride [ 17 ], and chlorhexidine [ 18 ] were tested regarding antibacterial activity and showed promising results.…”