Vitamins K2 and D3 enhance guided bone regeneration in rat calvarial bone defects

BackgroundVitamins K2 and D3 exhibit anabolic effects on bone metabolism, but their effectiveness in guided bone regeneration (GBR) is unclear. The present study aimed to investigate the impacts of vitamins K2 and D3 administration on GBR of calvarial critical‐size defect (CCSD) in rats.MethodsA total of 48 defects were obtained by creating two bilateral 5 mm CCSDs in each of 24 rats: the right‐side defect was treated using a collagen‐based resorbable membrane and a bovine bone graft (GM defect), the left side remained empty (empty defect). The rats were assigned to four groups and administered distilled water (Control), vitamin K2 (K), vitamins K2 and D3 (KD), or vitamin D3 (D) for 8 weeks. Rats were sacrificed after 8 weeks. Histomorphometric and immunohistochemical analyses were performed.ResultsThe new bone area was greater in GM defects versus empty defects of all groups (p < 0.05), higher in vitamin groups than the control group in both defects (p < 0.05). Osteocalcin levels were elevated in GM defects than empty defects (p < 0.0001). Within GM defects, levels were higher in the vitamin groups compared with the control group (p < 0.05). Runx2 expression was increased in GM defects compared with empty defects and in vitamin groups compared with the control group (p < 0.05). IL‐1β levels were greater in empty defects compared with GM defects in vitamin groups (p < 0.05).ConclusionThe administration of vitamins K2 and D3 in GBR enhanced bone healing in CCSD of rats, indicating that the adjunctive use of these vitamins may represent a promising therapeutic strategy for bone regeneration.Plain Language SummaryVitamin K2 and vitamin D3 are known to play important roles in bone metabolism. Previous research revealed that vitamins K2 and D3 supplements might be effective as a therapeutic approach to bone regeneration. Although there are several methods of bone regeneration, each has limits. Thus, we aimed to investigate the effects of administering vitamins K2 and D3 alone or in combination to restore bone defects. In this study, each rat had two critical‐size cranial bone defects (defined as the smallest bone defect that cannot restore naturally throughout life); one was filled with bone grafts and barrier membranes, while the other was left empty. Then rats were divided into groups administered either distilled water, vitamin K2, vitamin D3 or both. More bone was found in the regenerated bone defects compared with those left empty and vitamin‐administered rats had more bone in defects than vitamin‐unadministered rats. Moreover, the highest amount of bone was observed in regenerated bone defects of rats that received combined vitamins K2 and D3. Therefore, we conclude that administration of vitamins K2 and D3 improves bone healing in critical‐size cranial bone defects in rats. The use of vitamins K2 and D3 as adjuncts to guided bone regeneration may be beneficial in clinical applicability. This approach may serve as a promising foundation for future research on clinical relevance.