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BACKGROUND:Research on rough-surfaced implants has demonstrated similar survival rates for short and conventional-length implants. It is not clear whether ultrashort implant in limited alveolar bone of the posterior maxila can achieve good clinical results. OBJECTIVE:To evaluate the clinical effect of ultrashort implants in limited alveolar bone of the posterior maxila. METHODS:Eighteen patients with 21 ultrashort implants in limited alveolar bone of posterior maxila (the mean residual alveolar height=3.19 mm) were included in the study, including 10 males and 8 females, aged 25-68 years. At 12 months after restoration, the patients were detected with cone-beam CT to evaluate the osseointegration and marginal bone level around the implant. RESULTS AND CONCLUSION:Al the 18 patients completed the 12-month folow-up, and the 21 pieces of implants had good osseointegration. No soft tissue inflammation was found. At 12 months after restoration, the marginal bone height in the mesial and distal was (-0.21±0.78) mm and (-0.16±0.55) mm, respectively. Implant marginal bone changes in the mesial and distal had no statistical difference (P > 0.05). Ultrashort implants in limited alveolar bone of the posterior maxila can have good osseointegration, maintain the marginal bone mass around the implant, but stil need long-term clinical observation.
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BACKGROUND:Many experiments and clinical studies have reported that venous blood, absorbable colagen sponge and rich fibrin clot, without the use of bone graft material, can al promote new bone formation; therefore, whether only transplanting concentrated growth factor in the maxilary sinus lift could effectively promote bone regeneration? OBJECTIVE: To conduct the maxilary sinus lift with concentrated growth factor as the graft material, and to observe the peri-implant bone level change. METHODS: Totaly 26 patients were involved, including 14 males and 12 females, aged 35-73 years. Maxilary sinus lift was conducted and autologous concentrated growth factor was taken as the graft material. Astra Tech implants were implanted simultaneously. Patients were divided into 6-12 months, 13-18 months and > 18 months groups according to the folow-up time. Patients were divided into≤ 5 mm, 5-7 mm, and≥ 7 mm groups according to the preoperative alveolar bone height. Patients were divided into≤ 2 mm, 2.0-3.0 mm, and≥3 mm groups according to the postoperative maxilary sinus lift height. The survival rate of implants and marginal bone level changes were observed during the folow-up. RESULTS AND CONCLUSION: Totaly 44 implants were implanted, of which 43 implants were considered as successful repair during the 6-18 months of postoperative folow-up. The survival rate of implants was 98%. There were no significant differences in the changes of mesial, distal and middle marginal bone levels between different folow-up time groups. The maxilary sinus lift with transplantation of concentrated growth factor resulted in a good osseointegration within 6-18 months post-operation. In addition, no significant differences were found in the changes of mesial, distal and middle marginal bone levels between different residual alveolar bone height groups, as wel as between different maxilary sinus lift height groups. It showed that the residual alveolar bone height and maxilary sinus lifting height had no significant effect on the peri-implant bone formation. Briefly, these findings demonstrate that the maxilary sinus lift with concentrated growth factor transplantation can result in a high survival rate of implants that are simultaneous implanted, and the alveolar bone around the implant is stable. But the long-term effect needs further observation.
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AIM:Mesenchymal cells migrating towards fracture site and differentiating into chondrocytes and osteoblasts is the key process during fracture healing. This article is aimed to observe the changes of the expression of bone morphogenetic protein(BMP)-2 in the early stage of tibia fracture in osteoporotic rats so as to evaluate the reason of delayed fracture healing in osteoporotic rats. METHODS:The experiment was conducted at the Key Laboratory for Oral Biomedical Engineering of Ministry of Education from August 2005 to October 2006. ①Sixty-four 6-month-old female SD rats were randomly divided into ovariectomized(OVX) group and control group with 32 in each group. ②The rats in the OVX group underwent ovariectomy to establish type Ⅰ osteoporotic models. A small quantity of fat tissues was removed in the control group. Three months later,standardized tibia fracture was introduced. ③Eight rats were selected at days 7,14,21 and 28 after operation in the two groups. Some soft tissues around tibia and broken ends of fractured bone,bony callus,cortical bone and medullary canal were collected and treated with histological analysis,immunohistochemical staining,semi-quantitative reverse transcription-polymerase chain reaction(RT-PCR),respectively. RESULTS:①Histological analysis showed membrane bone formation and endochondral bone. A mass of chondrocytes appeared in bony callus of the OVX group at days 21 and 28 after operation. ②The results of immunohistochemical staining showed that mean absorbance(A) of BMP-2 was higher in the control group than the OVX group at days 7 and 14,but lower at day 21. ③The findings of RT-PCR revealed that BMP 2 level was higher in the control group than the OVX group at day 7,but lower at day 14. CONCLUSION:BMP-2 plays a key role in the early phase of bone callus formation during fracture healing. The declined and delayed expression of BMP-2 in osteoporotic rats may be an important reason for delayed fracture healing in osteoporotic rats.
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Objective To set up a neural network model and system to be applied in color selection of anterior porcelain prosthesis, and to improve its cosmetic effect. Methods The image was automatically captured by digtal camera, and pre processed. The values based on the three stimulation value were adopted for the colour selection and tooth colour matches from nine zone colors with 21 point smoothly transitional calculation. The three dimension view of the teeth was recovered. Tooth colors storage was set up and the characteristics for sample teeth and lost teeth were selected and retrieved to match the colour through artificial neural network automatically for personalized design of teeth colour. Results The method of anterior prosthesis for computerized color selection based on artificial neural network had a higher accuracy. By comparision, the satisfaction of patients, dentists and viewers was much higher than that without computer aided design, and patients' eveluation for the prosthesis was higher than that of dentists. Conclusion The design system for colour selection of the front tooth prosthesis has a great value in clinical application, and it has developed the theory of artificial neural network used in the field of stomatology.