Objective To study the influence of different implant diameters on the implant-bone-interface stress distributions in zygomatic implant denture and illustrate the correlation between implant diameter and long-dated success rate of zygomatic implant denture.Methods Three-dimensional finite element model for maxilla and zygoma was established biomechanically in this study by spiral CT technique and finite element software technique,and zygomatic implant was simulated into the model in the first-maxillary-molar region.Zygomatic-implant-denture load cases concerning different implant diameters(3.5,4.0 and 5.0 mm) were designed and loaded vertically,obliquely.The implant-bone-interface stress distributions were analyzed by 3-D finite element method.Results The model could be observed from any angle,and had good geometric similarity compared with CT image.Stress peak values among these load cases with different diameters were compared,the load case with 3.5 mm diameter appeared the largest stress peak value,the load case with 4.0 mm diameter appeared the larger stress peak value and the load case with 5.0 mm diameter appeared the least stress peak value.As the implant diamater increased(3.5 mm→4.0 mm→5.0 mm),the compressive and tensive stress peak values of implant-bone interface in the maxillary alveolar ridge and the zygomatic area near maxillary sinus roof decreased gradually,the stress of implant-bone interface in the maxillary alveolar ridge was significantly larger than that of implant-bone interface in the zygoma area and compressive stress peak value was larger than tensive stress peak value.Conclusion The implant-bone-interface stress distributions tend towards uniformity as the implant diameter increases.Select wider-diameter implant as possible as the residual bone permitted clinically.

BACKGROUND:There is often space between implant and bone during immediate implantation.Whether biological membrane is needed to guide bone regeneration remains poorly understood.OBJECTIVE:To createdifferent sizes of space between femurand implantsindogs and to observe the effects of biological membrane on bone regeneration capacity of bone defects surrounding implants.DESIGN,TIME AND SETTING:A self-control animal experiment was performed at the Laboratory Animal Center,Norman Bethune College of Medicine,Jilin University and School of Stomatology,Jilin University between March and December 2005.MATERIALS:BLB hydroxyapatite-coated implant was provided by Beijing Leiden Biomaterial Co.,Ltd.,China;BME-10X collagen membrane was purchased from Fujian Better Biotechnology Co..Ltd.,China.METHODS:BLB implants were installed in the bilateral proximal femoral bone to create standard gradient bone defects with horizontal width 3 mm.vertical depth 5 mm,and horizontal lengths of 0,1,2,3,and 4 mm Bone defects on the left femur were sutured directly and those on the right femur were covered with biological membrane prior to suture.All animals were sacrificed at 3 months after surgery.Specimens containing implants were harvested to prepare tissue blocks for radiological observation.MAIN OUTCOME MEASURES:The quantity,color,and texture of newly formed bone surrounding implants were observed from the surface and profile levels.The implant-bone integration and new bone formation were also examined by soft X-ray photography.RESULTS:Grossobservation results revealed that when the horizontal length of bone defect was 3 mm or less,there was no significant differenee in bone density between the newly formed bone and the host bone no matter whether biological membrane existed or not;when the horizontal length of bone defect was 4 mm the bone density was better when biological membranes were used than not.Soft X-ray photography results revealed that when the horizontal length ofbone defect was 3 mm or less.no significant difference in bone density and bone trabecular morphology and orientating was found between newly formed bone and host bone no matter whether biological membrane was used or not;in the 4-mm-length bone defect areas.implants contacted with newly formed bone directly,but the calcified degree ofnewly formed bone was poor,bone trabecula was thin,and bone trabecular course was irregular,nevertheless,the calcified degree of newly formed bone was better under the condition of being with biological membrane than without biological membrane.CONCLUSION:Biological membrane exhibits strong capacity to promote the regeneration and repair of bone defect tissue with a horizontal length of 3 mm or less,and plays an important role in repatr of large sizes of bone detect

Objective:To observe the bone regeneration capacity of bone defects around BLB implants covered with or without membranes.Methods:Implants were installed into femoral bone of grown-up dogs.Near implants,3 mm horizontal width,5 mm vertical depth and 1,2,3,4 mm horizontal length(along the macroaxis of femoral bone) standard gradient bone defects were made.On one side,the incisions were directly sutured by lamination,and on the other side the incisions were sutured by lamination after using collagen membrane to cover on the defects.Three months after the operation the specimens were observed by stereomicroscopy.Results:In the groups with 1,2 and 3 mm defects,the defect areas had been filled completely with new bone which was mainly compact cortex.In the group with 4 mm defects,the defect areas were filled with new bone which was mainly trabecular bone.Bigger lacunes could be observed in the groups without membranes.Conclusion:If the defect is less than 3 mm,whether bioresorbable collagen membrane is used or not,osseointegration is well in the implant-bone interface.Improving bone regeneration should be done when the bone defect extension is bigger.

BACKGROUND:Poly(butylene succinate) (PBS) and polypropylenecarbonate (PPC) are new medical materials developed in recent years, characterized as good biocompatibility, biodegradability and the low price. OBJECTIVE:To prepare the PBS/PPC biofilm by electrostatic spinning method and evaluate its physical and chemical properties, degradation performance and effect on cel proliferationin vitro. METHODS:The PBS/PPC biofilm was prepared using electrostatic spinning method: 0.9 g PBS and 0.9 g PPC were dissolved in 10 mL of trichloromethane at room temperature and stirred magneticaly until they were fulydissolved. Then, the spinning solution was added into a spinning tube with a distance of about 15 cm and at a voltage of 18 kV. The surface morphology was observed by scanning electron microscopy. The intensity, contact angle and water absorption, pH value and weight loss in the process ofin vitro degradation were measured. MG63 cels were co-cultured with the biofilm for 7 days and cel proliferation was detected by cel counting kit-8. RESULTS AND CONCLUSION: The PBS/PPC biofilm showed a porous structure with interconnected pores. The fiber diameter was about 0.88 μm, the average aperture was about 5.68 μm, the porosity was 78.3%, the fracture intensity was 2.31 MPa, the elongation rate at break was 23.48%, the average value of contact angle was 87°, and the water absorption rate was 68.54%. During the biofilm degradation, the pH value decreased gradualy andreduced to 6.76 at 12 weeks; meanwhile, the biofilm degraded equaly and gradualy, and the weight loss rate was 6.04% at the end of the 12th week. The results of cel counting kit-8 showed that the PBS/PPC biofilm could promote cel proliferation. Overal, the PBS/PPC biofilm has good physical and chemical properties, good space-making feature, wettability and degradability, which can provide sufficient time for bone tissue regeneration.

With the growing maturity of implant technology, implant overdenture has gradually become a conventional repair method for edentulous patients to restore beauty and function, which improves the quality of life of edentulous patients. This paper reviews the effects of implant factors, attachment factors, occlusal factors and patients' own factors on residual alveolar ridge. Existing studies suggest that when designing denture, doctors first need to consider the oral mucosa and jaw conditions of patients before operation, and select the appropriate size of implant to ensure that sufficient bone remains around the implant; Secondly, when choosing the type of attachment, the number, location and A-P distance of implants should be fully considered, and the inclination of cusp should be properly reduced to avoid the harm of excessive lateral force to alveolar ridge; Finally, regular reexamination should be carried out after operation to maintain longer service time of denture and more sufficient bone mass of edentulous patients. However, there are many factors affecting jaw absorption. In the future, we should further explore many factors, such as patients' habit and frequency of wearing dentures, oral health and nutritional status, systemic diseases and medication.

A case with horizontal and vertical bone deficiency at the maxillary esthetic area is reported.A titanium disk was applied to maintain the space for guided bone regeneration,and ridge splitting and bone compressing technique were used to prepare the site.Finally,the restoration of implant tooth with favorable esthetic outcome was obtained.