Biodegradation of an injectable treated dentin matrix hydrogel as a novel pulp capping agent for dentin regeneration

Abstract

Background A novel injectable mixture termed treated dentin matrix hydrogel (TDMH) has been introduced for restoring dentin defect in DPC. However, no study evaluated its physiological biodegradation. Therefore, the present study aimed to assess scaffold homogeneity, mechanical properties and biodegradability in vitro and in vivo and the regenerated dentin induced by TDMH as a novel pulp capping agent in human permanent teeth. Methods Three TDMH discs were weighted, and dry/wet ratios were calculated in four slices from each disc to evaluate homogeneity. Hydrogel discs were also analyzed in triplicate to measure the compressive strength using a universal testing machine. The in vitro degradation behavior of hydrogel in PBS at 37 °C for 2 months was also investigated by monitoring the percent weight change. Moreover, 20 intact fully erupted premolars were included for assessment of TDMH in vivo biodegradation when used as a novel injectable pulp capping agent. The capped teeth were divided into four equal groups according to extraction interval after 2-, 8-, 12- and 16-weeks, stained with hematoxylin–eosin for histological and histomorphometric evaluation. Statistical analysis was performed using F test (ANOVA) and post hoc test (p = 0.05). Results No statistical differences among hydrogel slices were detected with (p = 0.192) according to homogeneity. TDMH compression modulus was (30.45 ± 1.11 kPa). Hydrogel retained its shape well up to 4 weeks and after 8 weeks completely degraded. Histological analysis after 16 weeks showed a significant reduction in TDMH area and a simultaneous significant increase in the new dentin area. The mean values of TDMH were 58.8% ± 5.9 and 9.8% ± 3.3 at 2 and 16 weeks, while the new dentin occupied 9.5% ± 2.8 at 2 weeks and 82.9% ± 3.8 at 16 weeks. Conclusions TDMH was homogenous and exhibited significant stability and almost completely recovered after excessive compression. TDMH generally maintained their bulk geometry throughout 7 weeks. The in vivo response to TDMH was characterized by extensive degradation of the hydrogel and dentin matrix particles and abundant formation of new dentin. The degradation rate of TDMH matched the rate of new dentin formation. Trial registration: PACTR201901866476410: 30/1/2019.

Marginal adaptation, physicochemical and rheological properties of treated dentin matrix hydrogel as a novel injectable pulp capping material for dentin regeneration

“…Our previous studies [ 11 – 13 ] extensively focused on the dentinogenic properties and biodegradation of the innovative injectable treated dentin matrix hydrogel, which is a combination of alginate hydrogel as the matrix component and TDM powder. Sodium alginate (SA) is frequently involved in the gelation process that is triggered by the presence of divalent cations, (usually Ca 2+ ), forming structures known as hydrogels.…”

“…TDM was also confirmed to release dentinogenetic related proteins [ 43 ]. Consequently, TDMH induced a natural biological regeneration to reconstitute normal tissue continuum at the pulp-dentin border with degradation rate matched the rate of new dentin formation [ 11 – 13 ]. Additionally, TDMH demonstrated favorable biocompatibility over both short-term and extended periods with well-organized pulp tissue and almost no infiltration of inflammatory cells when used in direct pulp capping in human premolars [ 11 ].…”

“…Treated dentin matrix hydrogel was conducted as previously described by Holiel et al [ 11 – 13 ]. The formed hydrogel was loaded into a single syringe (5 mm chamber) to eliminate any excess solution and achieve a consistent mass of injectable hydrogel [ 11 – 13 ].…”

“…Recently, a novel injectable scaffold termed Treated Dentin Matrix Hydrogel has emerged, which combines alginate hydrogel as the matrix phase with TDM powder. This innovative material has shown significant potential for dentin regeneration and conservation of pulp vitality in direct pulp capping procedure [ 11 – 13 ].…”