Experimental Study Of Dentin Particle Boiling Processed As Bone Graft Material

Objective: The bone mass has always been the main problem faced by the oral clinic,especially in the oral implantation practice.The sufficient bone volume does not only provide sufficient biological support for implant,but also provide security for esthetic reconstruction of soft tissue at later period.Many kinds of bone grafting materials have been applied to cases with bone defect clinically,and the dentin is one kind of calcified tissue similar to the bone.Compared with other bone grafting substitutes,the dentin matrix does not only contain hydroxyapatite,but also include 20% of organic matrix;this point is very similar to that of bone tissue.The research shows that the demineralized dentin matrix can be used as the bone grafting substitute,but its preparation method is complex with expensive expense.The boiling processed dentin does not only remove the antigen,but also reserve the mineral substance.However,it's the bone-regeneration performance remains unknown.This experimental study aims at comparing bone-regeneration performance of boiled dentin particle and demineralized dentin matrix by means of an animal model so as to provide a new bone grafting substitute for clinical application.Methods: 1.The boiling processing and demineralization processing are carried out respectively for the extracted third molar of human.Boiling processing: remove the tooth enamel,dental pulp and periodontal soft tissue;boil them in distilled water for 2 hours after grinding them;degrease with isopropyl alcohol for 2 hours;grind them into 250um-1000 um particles after washing and drying.Demineralization processing: remove the tooth enamel,dental pulp and periodontal soft tissue;demineralize with 0.6 N of hydrochloric acid for one week;degrease with chloroform for 24 hours after washing them clean with plenty of running water;freezethem dry after washing,and grind them into 250um-1000 um particles.2.6 adult beagles are selected.The second premolars and third premolars of lower jaws at both sides are pulled out respectively.Contrast group: the demineralized dentin matrixes are implanted into teeth extraction sockets of second premolars.Experimental group: the boiled dentin particles are implanted into teeth extraction sockets of third premolars.As premolars of dogs are two-root teeth,there are 24 cases for experimental group and contrast group respectively.3.All dogs are put to death after being raised for 16 weeks.The bone blocks at tooth extraction site are cut and taken out with trimming drill.The gross observation and X ray examination are carried out.The healing state of tooth extraction is evaluated.After the decalcification,dehydration,embedding,paraffin section and HE dyeing,the histological observation is carried out against specimen to observe the healing state of new bone.The statistical analysis is carried out against the regeneration rate of new bone.Result: 1.Gross observation The postoperative wound healing is uneventful.The tooth extraction site is full of new bone.After 16 weeks,no redness or swelling of gingiva;no secretion of inflammatory substance is seen;the bone surface of tooth extraction site is completely covered by gingiva;it is very difficult to distinguish sites for implanting dentin matrixes of experimental group and contrast group after stripping gingiva.Comparing with the normal and smooth bone surface,there is particle-type structure on bone surface at the site implanting dentin matrix.2.X-ray observation The disordered bone trabecula arrangement can be seen at the bone graft site.The transmission image is surrounded by grainy structures,which prompts that the dentin particles have been absorbed completely to build up its own bone tissue.No large-sized transmission shadow or obvious bone resorption is seen.3.Histologic examination The new woven bone formation can be seen in contrast group and experimental group.No lymphocytic infiltration is seen.No rejection reaction.The dentin is decomposed into small particles.The dentin particles are surrounded by new bones,and many osteoblasts can be seen embedded in new bones.4.Statistical analysis The generation rates of new bone in experimental group and contrast group are 31.60±5.31% and 34.32±4.29% respectively.There is no statistical difference for generation rate of new bone(P > 0.05).Conclusion: Test results show: 1.Both the demineralized dentin matrix and boiled dentin particle can guide the new bone formation without rejection reaction.2.The bone-regeneration performances of boiling processed dentin particle and demineralized dentin matrix are same.3.As the boiling processed dentin particle is of better biocompatibility,easier operation and lower cost,it is suitable for clinical application.