Comparison of pericranium and eggshell as space fillers used in combination with guided bone regeneration: An experimental study

Purpose: The purpose of the study was to determine the potential adjunctive role of 2 space fillers, used in combination with guided tissue regeneration, on bone regeneration in rat skull defects. Materials and Methods: The study was conducted on 45 adult Wistar rats. A bilateral 6-mm-wide full-thickness skull defect was created in the parietal region of each animal. The right defect was chosen as the experiment site, and the left defect was left empty as a control. Each experiment sire was covered by an inner and outer polytetrafluoroethylene membrane. The 45 rats were divided into 3 groups; no space filler between the 2 membranes was used in group I (n = 15), a free pericranial autograft was used as a space filler between the 2 membranes in group II (n = IS), and purified eggshell powder was used as space filler between the 2 membranes in group III (n = 15). Five animals in each group were killed at 15, 30, and 90 days. The harvested specimens were subjected to contact radiography and standard microscopic examination, and the rates of osteogenesis were assessed by a semiquantitative method. Results: No evidence of bone regeneration was seen in any animals of the three groups at IS days. At 30 days, bone regeneration only appeared in group I (P >.05). Ar 90 days, complete bone regeneration was observed in the group I In 3 of 5 animals (P <.05). In group II, the pericranial graft showed no osteogenic properties. In group III, the eggshell powder showed no resorption, but no osteoconduction was noticed. Conclusions: Although the osteogenic mechanism of guided tissue regeneration is not clear, this study suggests that the physical properties of the membrane are more important than the use of an adjunctive space filler.