Olufemi Ogundipe; Vaughan Perry; Nhlanhla Lucky Japhta; Diana Pillay & Robert Ndou

Diabetic complications arise primarily from chronic hyperglycemia, a hallmark of the disease that is becoming increasingly prevalent worldwide. Among these complications, skeletal involvement remains one of the least studied. This study aimed to evaluate the impact of sustained hyperglycemia and therapeutic interventions with zinc and insulin on mandibular bone strength and microarchitecture using an alloxan-induced rabbit model. Fifty male rabbits were randomly assigned to five groups: untreated control (UN), hyperglycemic untreated (HG), hyperglycemic zinc-treated (HG+Zn), hyperglycemic insulin-treated (HG+Ins), and hyperglycemic zinc- plus-insulin-treated (HG+Zn+Ins). Diabetes was induced with alloxan, and treatments were administered for 12 weeks. The right hemimandible was analysed using high-resolution micro-computed tomography (Micro-CT) and biomechanical testing. Morphometric parameters (BV/TV, TbTh, TbN, TbSp, CtTh) and mechanical strength properties were compared across groups. Hyperglycemia significantly reduced bone volume fraction and cortical thickness, confirming mandibular vulnerability to diabetic osteopathy. Maximum force did not differ significantly among groups. Yield point analysis revealed increased stiffness and brittleness in HG and HG+Zn groups, while insulin therapy normalized yield point values. Zinc monotherapy failed to prevent microarchitectural deterioration, and combined zinc-insulin therapy unexpectedly impaired trabecular integrity, suggesting a negative pharmacological interaction. Persistent cortical thinning across all hyperglycemic groups indicates irreversible structural deficits despite treatment. Insulin is essential for preserving trabecular bone and restoring material properties compromised by hyperglycemia, whereas zinc alone offers no protective effect. The lack of synergy between zinc and insulin shows the need for optimization of combined therapies. Early and stringent glycemic control remains critical to prevent irreversible skeletal damage.

KEY WORDS: Diabetes mellitus; Hyperglycemia; Mandible; Zinc; Insulin; Bone.

OGUNDIPE, O.; PERRY, V.; JAPHTA, N.L.; PILLAY, D. & NDOU, R. Mandibular strength and trabecular morphology in hyperglycemic rabbits under zinc and insulin therapy. Int. J. Morphol., 44(3):756-765, 2026.