Abstract:

Abstract:Objective To investigate the internal fixation effects of poly(L-lactide) (PLLA) miniplates on the mandibular fracture in dogs.Methods A total of 12 dogs were involved in the study.After mandibular fracture models were created on both sides,one side of the mandibular was fixed with PLLA miniplates and the other side was fixed with titanium plates as control.The dogs were sacrificed separately at 1,3,6,12 months after operation,three animals at each time.Gross observation,radiography and histopathological examination were performed.Results All of the dogs were alive and fracture fixation of both sides was excellent after the operation.Gross observation:in 1 month group,the fracture line and some bony callus could be seen on both sides;in 3 months group,both sides had become into bone union;in 6 months group,both sides had become into bone union completely;in 12 months group,the fracture lines on both sides were difficult to be seen.Radiography examination:in 1 month group,the fracture lines and the screw holes could be seen on both sides;in 3 months group,the fracture lines turned ambiguity;in 6 months group,the line on the experimental side was difficult to be seen but the line on the control side disappeared;in 12 months group,the fracture lines on both sides disappeared.Histopathology examination:in 1 month group,there were lots of collagen fibers and a little bone trabecula on both sides;in 3 months group,the trabecula on the experimental side were much more than the other side;in 6 months group,the bone trabecula on both sides looked  like the normal bone tissue;in 12 months group,the bone trabecula became into nomal tissue.Conclusion The effect of PLLA miniplates for internal fixation of mandibular fracture is safety,the PLLA miniplate can maintain the stability of the bone fracture during the healing process.

Key words: poly-L-lactide, biodegradable miniplate, internal fixation