In the present retrospective study, the autogenous tooth bone graft which is made by the extracted tooth chairside were successful used in the immediate implant placement in the fresh socket with facial bone defect. The protocol of the immediate implant placement using different bone graft material had been well evaluated in some systematic reviews[2, 14]. And the protocol of immediate implant placement in fresh extraction socket may help to maintain the bone and soft tissue stable, enhancing the survival of the implant, shorten the treatment time and achieve patients’satisfaction.
But in many cases, there was a defect in the facial bone of the compromised teeth in the esthetic zone, and the bone graft is needed after implant placement. In the present study, a total of 30 implant had been inserted into fresh socket with facial defect, half of it using autogenous tooth bone graft material and the rest of it using xenogenic bone (Bio-Oss). None of the implant nor the graft material fail to reach the success criteria. The result consistent with other clinic studies. As patricia et al reviewed that the mean implant survival rate was 97.7% while using the autogenous tooth bone as a graft material with a limited number of cases. Also in other recent systematic review the implant survival rate using bone graft material were higher than 90% (range from 90% to 100%)[16, 17]. Meanwhile, many studies had shown that Autogenous tooth bone graft materials have been applied for lateral sinus floor elevation, guided bone regeneration, alveolar bone preservation and other bone augmentation surgery, and show high bone formation activity and excellent biocompatibility. The chemical composition of the teeth, especially dentin, closely approximates bone tissue. Dentin is rich in bone morphogenetic protein ( BMP) promoting bone marrow mesenchymal stem cell differentiation and accelerating osteogenesis. The dentin consists of low crystalline hydroxyapatite similar to bone tissue, compared to the high crystalline enamel of hydroxyapatite structure. Meanwhile, previous studies also showed that the enamel could not be easily degraded by osteoclasts because of its highly mineralized calcium phosphate crystals, resulting in the difficulty of osteogenesis factors release such as BMPs and the delay of BMSCs migration, adhesion and differentiation on the material surface. Hence, the osteoinductivity and osteoconductivity of the enamel and dentin make the autogenous tooth bone a perfect bone graft material and high success rate.
We measured the different level of the implant buccal bone width at different follow-up time to observed the stability of the horizontal bone. As we can see from the Fig.4–6 about the change of the horizontal bone, there is no statistic difference between the two bone graft material in the three different measured level at the 6 months and 12 months follow-up period, and there is no statistic difference between the first and latter 6 months follow-up at the two different bone graft material in the three different measured level. These results indicated that the horizontal bone loss in the autogenous tooth bone group is almost the same with the xenogenic bone in the three measured level at the 12 months following up and the horizontal bone loss at the first and latter 6 months is also the same. But the horizontal bone loss at the level of 6mm is much than the level of 0mm and 3mm at the different follow-up time and different bone graft material, while the level of 0mm is the same with the level of 3mm. We can drive from the result that the apical bone may be more stable than the marginal bone. All this percent of the horizontal bone loss is accepted, and is consensus with other reresearch. Francesco etc reported that the volumetric tissue changes after immediate extraction placement in the esthetic area can be minimized by a provisional restoration and bone graft inserted simultaneously with implant placement. And Fabio’s research proved that the protocol of flap approach or not would not affected the bone volume changes in the immediate implant placement, and the reduction of bone width is almost 10% in the first 6 month.
Marginal bone is significant important for the facial gingiva of an implant, and it is also an important clinical parameter for the implant long term success. Overall, the marginal bone loss in the two groups ranging from 0.02 to 0.59 which is accepted by the clinical. And the marginal bone loss in the immediate implant placement using autogenous tooth bone and xenogenic bone were almost the same, which means the marginal bone level or the gingiva level is stable in the two bone graft material. Many other clinical studies also showed that the implant placement in the fresh socket with GBR had an acceptable marginal bone loss. The Eugenio etc indicated that the mean marginal bone loss was 0.67 mm ± 0.40 mm (ranging from 0 mm to 1.6 mm) in the immediate implant placement with the follow-up of 4 years.
In the present study, the results of the questionnaire about the pain and swelling seems better in the group of the autogenous tooth bone graft material. This indicated that GBR with the autogenous tooth bone may cause less inflammatory reactive. Because the xenogenic bone grafted in the bone defect can be regard as a foreign substance insert into body, which can generate an immune and inflammatory reaction and it can be referred to as “osteoimmunology”[25, 26]. After the bone graft material inserted in the bone defect, the immune cell like macrophage will secrete pro-inflammatory cytokines as TNF-a, IF–1, which caused a transient abnormal enlargement of the operative region. Autogenous tooth bone is consisted of demineralized dentin matrix (DDM) largely which is demineralized from dentin, a mainly structure of teeth. The DDM which is the internal stuff may arouse less auto-immunity, therefore the less swelling and pain happened. This is the hypothesis based on the osteoimmunology, the underlying reason still need to be exposed by molecular mechanism research. Also the auto-suggestion of the patients about the graft bone is part of themselves may ben benefit the postoperative reactions.
The limitations of this study: the clinical observation period is 12 months which is not long enough to observe the long term stability of the grafted bone, also the cases is thirty which is not much enough. Thought the measurement is done by one dentist, the subjective bias inevitable.