Periodontal tissue responses following vertical root fracture repair with 4-META/MMA-TBB resin mixed with nano-hydroxyapatite.

PURPOSE: Vertical root fracture (VRF) repair remains clinically challenging because of poor periodontal regenerative capacity, often leading to persistent deep periodontal pockets and impaired healing. This study aimed to evaluate periodontal tissue responses after VRF repair using 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate tri-n-butylborane (4-META/MMA-TBB) resin cement (Super-Bond, SB) and nano-hydroxyapatite (naHAp)-incorporated SB (naHAp/SB) in a rat model.

METHODS

VRFs were induced in both maxillary first molars of Sprague-Dawley rats. Each fracture was repaired with one of the two materials, followed by tooth replantation. Periodontal tissue responses were assessed using electron probe microanalysis (EPMA), histological analysis, and immunohistochemistry targeting osterix (OSX), osteocalcin (OCN), and periostin (POSTN) markers at 2, 4, and 6 weeks post-replantation.

RESULTS

EPMA showed strong calcium and phosphorus deposition near the material-tissue interface in the naHAp/SB group. Conversely, only weak calcium and phosphorus signals were observed in the SB group. Histological analysis showed that the naHAp/SB group consistently exhibited minimal inflammatory responses throughout the study period. The SB group exhibited early mild-to-moderate inflammation, which gradually subsided over time. Compared with SB, the naHAp/SB group showed significantly higher expression of OSX at all time points (P < 0.01), OCN at 6 weeks (P < 0.01), and POSTN at 4 weeks (P < 0.01).

CONCLUSIONS

Incorporating naHAp significantly enhanced osteogenic responses and created a more favorable environment for periodontal healing after VRF repair in vivo.