INTRODUCTION: Bone is a unique tissue that undergoes frequent remodeling. An imbalance between bone formation and resorption results in osteoporosis. Glucocorticoids (GCs) are widely used clinically as anti-inflammatory and immunomodulatory. However, their prolonged use may induce osteoporosis. Currently, evidences revealed that also the alveolar processes are subject to osteoporosis. Bisphosphonates, such as Alendronate, Risedronate and Zoledronate, are recommended by several international guidelines as the first-line therapy for the prevention and treatment of generalized glucocorticoids induced osteoporosis (GIOP). OBJECTIVES: To evaluate the effect of bisphosphonates (Risedronate) on the alveolar bone of rats with glucocorticoids induced osteoporosis. MATERIALS AND METHODS: Thirty female albino rats were divided into 3 equal groups (10 rats each) as follows: Group I: control group. Group II: glucocorticoids group (Dexamethasone 0.6mg/kg twice/week subcutaneously). Group III: Risedronate treated group; rats were given Dexamethasone (0.6mg/kg twice/week subcutaneously) and Risedronate (1mg/kg/day orally). After 12 weeks, rats were euthanized, and the mandibular alveolar bone was evaluated histologically by light microscope and ultra-structurally by scanning electron microscopy and energy dispersive X-ray (EDX) microanalysis. RESULTS: Group II showed deterioration of the alveolar bone in comparison to the control group I. The alveolar bone structure in Group III rats, treated by bisphosphonates (Risedronate), showed remarkable improvement both histologically and ultrastructurally in comparison to group II. Moreover, EDX analysis revealed a significant decrease of calcium levels in group II in comparison to group I. However, in group III calcium levels were restored to normal levels comparable to the control group I. CONCLUSIONS: Glucocorticoids intake induces loss of the alveolar bone; which, could be counterbalanced by bisphosphonates.

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INTRODUCTION:Diabetic osteopenia is the sixth classic complication of Diabetes mellitus. High glucose level is capable of triggering increased oxidative stress which induce osteoblast apoptosis. Quercetin, a powerful natural antioxidant, can protect many organs against oxidative damage, including bone. OBJECTIVES: The present study is designed to investigate the effect of quercetin administration on the alveolar bone in rats with induced diabetes. MATERIALS AND METHODS: Twenty-four adult male rats were divided into three equal groups (8 rats each) as follows: Group I: Control group, Group II: diabetic group (with no treatment), Group III: quercetin treated group (induction of diabetes with oral administration of quercetin dose 100mg/ kg/ day for 12 weeks). Diabetes was induced in group II and group III by a single intraperitoneal injection of Streptozotocin (STZ). After 12 weeks all rats were sacrificed and the mandibles were dissected out and prepared for histological analysis using scanning electron microscope (SEM), and energy dispersive x-ray microanalysis (EDX). RESULTS: In diabetic group, there was significant increase in blood sugar level. Bone surface revealed irregular surface with multiple resorptive pits. Moreover, there was significant decrease in calcium level and increase in phosphorous level while in quercetin group. Both blood sugar level and alveolar bone surface relatively returned back to normal. Also there was slight decrease in calcium and increase in phosphorous in comparison to control group. CONCLUSIONS: Quercetin exerts protective effects on STZ-induced oxidative stress in diabetic rats restoring the architecture of bone.

INTRODUCTION: Comminuted fractures of the mandible are an important traumatism, in which the mandibular bone is splintered or crushed. Treatment of these types of fractures had always been a challenge to surgeons, considering both the severity of the trauma and the presence of discontinuity defects which require replacement and augmentation in order to treat the bone loss. Titanium mesh was proved to be particularly useful for reconstruction of mandibular discontinuity defects also it can be used as a scaffold for bone grafts. Electrophoretic deposition (EPD) is a coating technique used to increase the osseointegration and increases bone regeneration. OBJECTIVES: To histologically evaluate the effect of titanium mesh coated with hydroxyapatite nanocrystals using electrophoretic deposition on bone osseointegration and healing following comminuted mandibular fractures. MATERIALS AND METHODS: A controlled induced comminuted fracture on the inferior border of the mandible extending from the 2 nd premolar to the 2 nd molar was performed on 12 mongrel dogs. Six dogs were treated using titanium mesh coated with hydroxyapatite nanocrystals (study group) and the other six using uncoated titanium mesh (control group). The dogs were sacrificed at 2, 4 and 6 weeks and the specimens were dissected to be histologically and radiographically evaluated for new bone formation. RESULTS: The histological outcome showed superior bone healing in the bony defects in the resembling comminuted fracture in the study group than the control group. CONCLUSIONS: The nano-hydroxyapatite coated titanium mesh is a suitable method for reconstruction of comminuted fractures with bony defects.

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