effect of combined calcium hydroxide and accelerated portland cement on bone formation and soft tissue healing in dog bone lesions

statement of problem: recent literatures show that accelerated portland cement (apc) and calcium hydroxide ca (oh) 2 may have the potential to promote the bone regeneration. however, certain clinical studies reveal consistency of ca (oh) 2, as one of the practical drawbacks of the material when used alone. to overcome such inconvenience, the combination of the ca (oh) 2 with a bone replacement material could offer a convenient solution. objectives: to evaluate the soft tissue healing and bone regeneration in the periodontal intrabony osseous defects using accelerated portland cement (apc) in combination with calcium hydroxide ca (oh) 2 , as a filling material. materials and methods : five healthy adult mongrel dogs aged 2-3 years old (approximately 20 kg in weight) with intact dentition and healthy periodontium were selected for this study. two one-wall defects in both mesial and distal aspects of the 3rd premolars of both sides of the mandible were created. therefore, four defects were prepared in each dog. three defects in each dog were randomly filled with one of the following materials: apc alone, apc mixed with ca (oh) 2 , and ca (oh) 2 alone. the fourth defect was left empty (control). upon clinical examination of the sutured sites, the amount of dehiscence from the adjacent tooth was measured after two and eight weeks, using a periodontal probe mesiodistally. for histometric analysis, the degree of new bone formation was estimated at the end of the eighth postoperative week, by a differential point-counting method. the percentage of the defect volume occupied by new osteoid or trabecular bone was recorded. results: measurement of wound dehiscence during the second week revealed that all five apcs had an exposure of 1-2 mm and at the end of the study all samples showed 3-4 mm exposure across the surface of the graft material, whereas the ca (oh) 2, control, and apc + ca (oh) 2 groups did not show any exposure at the end of the eighth week of the study. the most amount of bone formation was observed in apc group which was significantly different with all other groups ( p < 0.05). conclusions: despite acceptable soft tissue response of ca (oh) 2 , this additive material could not be suggested because of negative effects on bone formation results.