RESUMEN
Background/purpose: Type 2 diabetes mellitus (T2DM), characterized by hyperglycemia, is a systematic disease affecting structure and healing ability in various tissues. This study aimed to investigate whether T2DM could impair the dental pulp healing and cause underlying pathological changes in the dental pulp before an injury occurred. Materials and methods: Goto-Kakizaki rats were used as T2DM model animals and performed with direct pulp capping procedures on the first maxillary molars. The molars at 1, 2, 4 weeks after operation and non-injured molars were examined using hematoxylin and eosin staining, immunohistochemical staining, immunofluorescence staining, and Masson's trichrome staining. The fresh dental pulp of maxillary incisors was collected for transmission electron microscopy and glucose content evaluation. Results: The T2DM rats showed deficient reparative dentin formation compared with the healthy rats. Before the occurrence of an injury, underlying pathological changes of major components in the pulp tissue were observed in T2DM rats, including vasculopathy; collagen abnormalities; decreased proliferation, decreased odontogenetic differentiation and damaged ultrastructure of dental pulp cells. High glucose content and advanced glycation end products accumulation were further found in the pulp tissue in T2DM rats. Conclusion: T2DM can impede pulp healing process in rats, which is associated with underlying pathological changes in the non-injured pulp caused by the advanced glycation end products accumulation under high-glucose conditions.