Background: The aim was to investigate of structure of the mandibular condylar cartilage (MCC) after implantation of manganese (Mn) enhanced hydroxyapatite into the tibia.
Methods: The study involved 252 male rats with initial body weight of 135-145 grams. The 1st group comprised intact animals, the 2nd group comprised animals with a plain 2.2 mm defect in the tibia, and the groups 3 through 6 comprised the animals with the same 2.2 mm defects filled with biogenic hydroxylapatite enhanced with 0.1%, 0.25%, and 0.5% share of Mn. Upon expiration of observation terms, the frontal sections of the MCC were hematoxylin-eosin stained and put to light microscopy for measurements of MCC zones (V. Luzin, 2012).
Results: A plain defect in tibia had inhibiting effects on activities of MCC. Peak of alterations was registered by the 60th day when zones of proliferation (ZP) and osteogenesis (ZO) were narrower than controls by 9.55% and 12.38%. In the 3rd group, alterations in comparison with the 2nd group continued manifesting by the 7th and the 15th days. By the 30th day, restoration of MCC seemed to be faster and finally by the 60th day ZP and ZO were wider than those of the 2nd group by 4.17% and 5.28%. Implants with 0.1% of Mn share had nearly the same effect and few significant differences were revealed. With Mn concentration increase, restoration rate of MCC appeared to be higher starting from the 15th day. Maximum value gap between the 3rd and the 5th groups was observed by the 60th day: ZP and ZO were wider than those of the 3rd group by 5.87% and 7.16%. Mn share of 0.5% did not have positive effect on MCC restoration. What is more, from the 60th to the 180th day density of osteoblasts in ZO was lower than that of the 3rd group by 4.23%, 5.01%, and 5.91%. This can be explained as Mn intoxication.
Conclusions: The results obtained show that a plain 2.2 mm defect in the tibia has adverse effects on activities of MCC. Implantation of pure hydroxyapatite produces no visible effects in early observation terms (the 7th and the 15th days) and starting from the 30th day alterations reduce faster. Application of Mn enhanced implants significantly reduces negative effects of bone fracture on MCC. Implants with 0.25% share of Mn proved to be the most effective while implants with 0.5% share of Mn produced signs of Mn intoxication.
Disclosure: The authors declared no competing interests.