Experimental Study Of Bone Regeneration Of Undemineralized Dentin Particles Promoted By PRF And BMC

Objective:Different forms of allogenic dentin have been studied for their potential used as bone substitutes,these include freeze-dried dentin,demineralized dentin,and particulate dentin(tooth ash).However,the osteogenic effects of these materials were reduced by the the preparation process.After the procedures of boiling,defatting,smash and disinfection,the available prepared undemineralized dentin particles is more convenient for clinical use.PRF(platelet-rich fibrin)containing large amount of growth factors,and BMC(bone marrow concentrate)containing large number of seed cells,are capable of promotion bone formation.In this animal study,a sinus elevation grafting model was created and the human undemineralized dentin particles mixed with the PRF and BMC of dogs were then grafted into the maxillary sinus.Our purpose is to observe the bone regeneration effects of implanted materials in maxillary sinus.The feasibility of the protocol of the undemineralized dentin particles prepared by boiling as bone graft materials was evaluated.At the same time,the effects of PRF and BMC on bone regeneration was also analyzed.Materials and methods: 1.Prepartion of dentin particles: Extracted wisdom teeth were collected from patient in clinic.Fibrous connective tissue,enamel,cementum and pulp were removed with dental handpiece,smashed dentin pieces were boiled for 2 hours,then defated with isopropanol for 2 hours and finally ground into particles with sizes between 0.25-0.5 mm.The dentin particles were sterilized before use.2.Prepartion of PRF/BMC: Six male healthy dogs,1 years old,weight of 15 kg,were selected.Under general anesthesia 5ml venous blood was drawn to produce PRF and 5ml bone marrow was aspirated to make BMC.Dentin particles mixed with PRF or BMC at a ratio of 1:1 before grafting.3.Animal surgery: Palatal flap was raised and the palatal bone plate close to 1st molar was removed round bur,and the sinus membrane was elevated carefully to created space to accommodate the grafting materials.12 models of sinus grafting were separated into 3 groups randomly,group A: dentin particles only;group B: mixture of dentin particles and PRF;group C: mixture of dentin particles and BMC.4.Outcome analysis: The animals were sacrificed after 3 mouths.Gross observation and X-ray examination were carried on and the specimens were processed into paraffin section stained with Hemato-Eosin.Following the histological observation,statistical analysis of new bone percentage was performed.Results: 1.Gross and X-ray observation: There is no death of experimental dogs,3 days after the surgery,the diet and life-habit recover to normal,no wound inflammation.All grafting regions of 3 groups heal well,but there were depressions at grafting sites of group A.The border of the depression and the normal bone tissue around is apparent,but the bone-defect regions of group B and C were flat,and there were no obvious interface between grafting sites and surrounding bone tissue.X-ray results did not reveal significant differences.2.Histologic examination: Most dentin particles in group A remain intact with less resorption,and only a small number of multinucleated giant cells were seen around the dentin particles.The thin strips of new bone formed to contact the dentin particles.The dentin particles in group B were apparently absorbed with the irregular scalloped appearance,and there are large amount of new bone formation bridging the particles,the trabecular bone arrangement appears regular.The worm-eating appearance of dentin particles in group C looks more obvious and the new bone formation around the particles is denser and surrounded by large numbers of osteoblasts.3.Statistical analysis: After 3 months' healing,the new bone formation rate is 16.7±2.4%(group A),21.2±4.1%(group B),23.3±3.4%(group C),respectively.Statistical analysis reveal that there are significant statistical differences of new bone formation rate between group A and Group B/C(p<0.05).No significant differences were found between group C and B(p>0.05).Conclusions: 1.The dentin is abundant in resources clinically with advantages of simple production,good biocompatibility,bone-conduction effect,but the potential of bone regeneration is limited if used solely.2.Both PRF and BMC can effectively promote the new bone regeneration when used in combination with undemineralized dentin particle.But compared with BMC,the methods to make PRF are more simple and PRF is also more acceptable clinically.