Esterases affect the physical properties of materials used to seal the endodontic space.

Materials used to seal the endodontic space are subjected to enzymatic degradative activities of body fluids and bacteria. OBJECTIVES: To assess effects of simulated human salivary, blood and bacterial esterases (SHSE) on physical properties of typical restorative material and root canal sealers. METHODS: Specimens of set methacrylate-based resin composite (BisfilTM2B; RC), calcium-silicate sealer (EndoSequence®; BC) or epoxy-resin sealer (AH-Plus®; ER) were tested after up to 28Days exposure to phosphate buffered saline (PBS) or SHSE, using ANSI/ADA-57:2000 and ISO-6876:2012. RESULTS: Regardless of media, microhardness increased with time for BC remained unchanged for ER and decreased for RC (p < 0.05). SHSE moderated the increase for BC compared to PBS (28.0 ± 4.8 vs. 38.1 ± 7.9 KHN) at 7Days, and enhanced the decrease for RC at 7Days (55.6 ± 7.1 vs. 66.3 ± 6.5 KHN) and 28Days (52.3 ± 9.2 vs. 62.6 ± 8.5 KHN). Compressive strength was enhanced only for BC by either media. BC expanded with time for both incubation conditions; SHSE moderated the expansion compared to PBS at 7Days (0.026 ± 0.01% vs. 0.049 ± 0.007%). Shrinkage of ER was similar for both incubation media and was lower than that for RC (p < 0.05). Shrinkage of RC was enhanced by SHSE compared to PBS at 7Days (0.5 ± 0.07% vs. 0.38 ± 0.08%). Weight loss was lowest for ER and highest for BC (p < 0.05). It was enhanced by SHSE compared to PBS for BC at 28Days (2.40 ± 0.2 vs. 2.96 ± 0.19 W L%), and for RC at 7Days (0.54 ± 0.09 vs. 0.80 ± 0.1 W L%). SIGNIFICANCE: Simulated body fluids and bacterial esterases affected the physical properties of test materials, suggesting potential impacts on sealing ability and resistance to bacterial ingress, and tooth strength ultimately affecting their clinical performance.

Endodontic pathogens possess collagenolytic properties that degrade human dentine collagen matrix.

AIM: To measure collagenolytic protease activity from Enterococcus faecalis and Micrococcus luteus and their ability to degrade human dentinal collagen. METHODOLOGY: Proteases activity of E. faecalis ATCC 29212, ATCC 47077 and M. luteus towards generic and specific human matrix metalloproteinase (MMP) substrates was measured using a fluorimetric assay. The ability of the bacteria to degrade dentinal collagen was tested by quantifying the amount of hydroxyproline released into the media following incubation of the bacteria or heat-inactivated bacteria (HIN) with demineralized human dentine samples for 24 h and by scanning electron microscopy (SEM). Multifactorial anova and Tukey's post hoc test were used to analyse the data (P < 0.05). RESULTS: All strains had MMP-like activities, but with different substrate affinity; E. faecalis ATCC 29212, ATCC 47077 and M. luteus had the greatest affinity towards MMP-8 (7.75 ± 0.88 µmol L-1 /3 × 106 CFU), MMP-9 (33.86 ± 5.16 µmol L-1 /3 × 106 CFU) and generic MMP (26.08 ± 4.48 µmol L-1 /3 × 106  CFU), respectively. The amount of hydroxyproline released from demineralized dentine was similar (P > 0.05) for the three strains (range 1.8 ± 0.17 to 2.38 ± 0.39 µg 50 µL-1 ) and was significantly higher (P < 0.001) compared to their HIN counterparts (0.61 ± 0.22 µg 50 µL-1 ). SEM revealed increased collagen network degradation after incubation with bacteria versus HIN. CONCLUSIONS: Endodontic pathogens possess collagenolytic protease properties that enable them to degrade dentinal collagen, potentially compromising the restoration-tooth and sealer-tooth interfaces. These collagenolytic protease properties could facilitate the migration of pathogenic bacteria into the root canal system and explain in part their role in root canal infections.