Dental pulp enhances dentin bonding durability: Evidence from a rat model.

OBJECTIVES

To develop a novel animal model for investigating dentin bonding and to examine how dental pulp vitality affects the long-term stability of dentin-resin bonds.

METHODS

1. A split-mouth design was employed in Sprague-Dawley rats. Mandibular first molars were assigned to the vital or nonvital group (n = 6). In vital teeth, 0.3 mm of the mesial surface was removed to expose the dentin, followed by the application of a self-etch adhesive and light-cured resin composite. For nonvital teeth, root canal treatment was performed before the same bonding procedure. Micro-CT analysis and hematoxylin-eosin staining were conducted for model validation. 2) A total of 116 rats were used for dentin bonding evaluation. The composite survival rates, microshear bond strength (μSBS), and interfacial structure were characterized at 0, 2, 4, and 6 weeks (with 29 rats sacrificed at each interval) via field emission scanning electron microscopy, atomic force microscopy, and confocal laser scanning microscopy. Additional biochemical analysis of bonded dentin (n = 3) was performed via data-independent acquisition mass spectrometry.

RESULTS

1. The animal model was validated successfully, with micro-CT and histology confirming that there were no pathological alterations in pulp or periapical tissues. 2) Vital teeth exhibited superior bonding durability, with significantly higher survival rates, stable μSBS values, and excellently characterized interface. Nonvital teeth exhibited decreased bond strength, microcracks, poor sealing, reduced mechanical properties, and increased matrix metalloproteinase (MMP) activity. Proteomic analysis suggested that pulp vitality regulates MMP expression, preserving interfacial stability.

CONCLUSIONS

Dental pulp vitality enhances bonding durability by maintaining interface integrity and modulating endogenous enzymes, particularly MMPs.

CLINICAL RELEVANCE

The protective role of dental pulp vitality in stabilizing the dentin-resin interface and suppressing MMP activity may lead to the development of novel dentin bonding strategies.