New bone formation in bone defects after melatonin and porcine bone grafts: experimental study in rabbits.

Objective: The aim of this study was to evaluate the effect of the topical application of melatonin compared with collagenized porcine bone grafts to accelerate bone formation 2 months after their insertion in tibiae rabbits.

Material And Methods: Twenty New Zealand rabbits weighing 3,900-4,500 g were used. Twenty collagenized porcine bone (MP3) grafts, twenty melatonin-impregnated bone grafts, and twenty control areas were placed in the proximal metaphyseal area of both rear tibias. Four groups were formed according to the moment in which animal killing was carried out: Group I (15 days), Group II (30 days), Group III (45 days) and Group IV (60 days). Cortical width and cortical length of bone formation was measured. Following implantation, an anteroposterior and lateral radiological study was carried out. Samples were sectioned at 5 μm and stained using hematoxylin-Eeosin, Masson's trichromic, and Gordon-Switt reticulin stains.

Results: After 60 days of treatment period, melatonin increased the length of cortical bone formation 99.03 ± 0.61% like control 98.90 ± 3.82% compared with porcine bone 92.73 ± 1.08%. Related to perimeter of cortical bone of the tibiae melatonin new bone was 98.35 ± 1.14% like control 98.0 ± 1.43% more than porcine bone 92.05 ± 1.03%. Histomorphometric values related to porcine bone were connective tissue 49.16 ± 2.4%, graft material (MP3) 23.52 ± 2.3%, and new bone formation 27.32 ± 1.4% compared with test group with melatonin 24.5 ± 1.2%, connective tissue 45.1 ± 1.2%, and new bone formation of 30.4 ± 1.0%.

Conclusion: Melatonin has proven to regenerate the width and length of cortical bone in tibiae rabbits more quickly than collagenized porcine bone. Melatonin acts as a bone stimulator compared with porcine bone and control sites.