Human Treated Dentin Matrix Hydrogel as a Drug Delivery Scaffold for Regenerative Endodontics

Abstract

Introduction: The objective of the current study was to develop a human treated dentin matrix (hTDM) hydrogel for use as a scaffold to allow the controlled release of an antimicrobial agent for regenerative endodontics.

Materials and methods: Human extracted teeth were treated via chemical demineralization using ethylene diamine tetra-acetic acid solution to produce hTDM powder. Fourier transform infrared spectroscopy (FTIR) was conducted to determine the functional groups of hTDM, scanning electron microscopy (SEM) was used to define the morphology/particle size of hTDM, and energy dispersive X-ray analysis was performed to identify the superficial apatite groups. Prepared hTDM powder was added to the amoxicillin-clavulanate mixture with a mass ratio of 1:1. Then, the combination was dripped into a 5% (w/v) calcium chloride solution. Antibiotic release profiles were evaluated for 14 days via high performance liquid chromatography (HPLC). Hydrogel degradation properties were studied for 14 days using 10 mL of phosphate buffered saline (PBS). Encapsulation efficiency was determined by HPLC, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of amoxicillin-clavulanate were determined against Enterococcus faecalis (E. faecalis). The antibacterial activity of amoxicillin-clavulanate against E. faecalis was investigated for 14 days via agar diffusion test. Statistical analysis was performed with the Shapiro-Wilk test (P=0.05).

Results: hTDM showed statistically a significant difference for percentage weight change (P=0.1). The encapsulation efficiencies for hTDM hydrogel with antibiotic and hydrogel with antibiotic was 96.08%±0.02 and 94.62%±0.11, respectively. MIC and MBC values of amoxicillin-clavulanate against E. faecalis were 2.4 µg/mL and 9.6 µg/mL, respectively. The antibacterial activity of antibiotic loaded hTDM hydrogels was significantly greater than loaded hydrogels alone by 31% after 4 days and 100% at 14 days, respectively (P≤0.001).

Conclusions: This in vitro study showed antibiotic-loaded injectable hTDM hydrogel could be an alternative system to transfer antibiotic-based intracanal medicaments for use in regenerative endodontics.

Keywords: Demineralized Dentin Matrix; Drug Delivery Systems; Hydrogels; Regenerative Endodontics.

Figure 1

The different groups of prepared hydrogels, A) SA/ hTDM hydrogel loaded with AmC (A1); B) SA hydrogel loaded with AmC (B1); C) Injectable SA/hTDM hydrogel loaded with AmC; (SA; sodium alginate, hTDM; human treated dentin matrix, AmC: amoxicillin-clavulanate mixture)

Figure 2

A) Scanning electron microscopic characterization of hTDM showing dentinal tubules sufficiently exposed and loosened fiber bundles of intertubular and peritubular dentin after specific EDTA treatment at X10.000; B) Particle size range of prepared hTDM powder (120µm -180µm); C) The dense morphology of SA/hTDM hydrogels; (hTDM; human treated dentin matrix, EDTA; Ethylenediaminetetraacetic acid SA; sodium alginate)

Figure 3

Energy Dispersive X-ray analysis results, EDX showed the total percentage of calcium at 55.8% and phosphorus at 40.7%; (EDX; Energy dispersive X-ray)

Figure 4

Fourier transform infrared spectroscopy analysis of hTDM. FTIR absorptions at1030 cm^-1 belonged to phosphate functional groups (PO₄)³. The peaks present at 1638 cm^-1 represented carbonate (CO₃) and C–N and N–H bands. Small peaks around 2346 cm^-1 corresponded to the CO₃ compound. The peak seen in the region of 3429.95 cm^-1 can be attributed to the presence of hydroxyapatite, as well as amide N–H; (FTIR; Fourier transform infrared spectroscopy)

Figure 5

Comparison between the two studied groups A2 and B2 according to the percentage of weight change

Figure 6

A) The mean concentration of released antibiotic as functions of release time of A1 and B1; B) The diameters of inhibition zones of A1 and B1