Reconstruction of Segmental Mandibular Defects Restored by Prosthesis with Support and Porous Structure: A Biomechanical Study / 医用生物力学

Objective To design a personalized titanium mandibular prosthesis with porous and support structure, and analyze its stress distribution characteristics through finite element analysis, so as to evaluate clinical value and prospect of the prosthesis. Methods The fourth mandibular premolar and molar from the right mandible of Beagle dogs were removed. The spiral CT was taken after three-month healing, and the three-dimensional (3D) model of the mandible was established. Resection of 3 cm mandible with simulated surgical procedure and reconstruction with personalized restoration were conducted. The prosthesis consisted of abutment, pillar, solid unit, porous unit and retention unit. A personalized titanium mandibular prosthesis finite element model A was established, to analyze the prosthesis stress under loading, and further study was proceeded when the maximum stress of each part constituting the prosthesis was smaller than yield strength of its material. The finite element model B with the assembly of the prosthesis, mandible and screw was constructed and loaded with the mastication force, and the stress, strain and displacement distributions of the mandible were recorded. Results When the abutment was under 100 N vertical loading, the peak stress of the prosthesis with solid structure and porous structure was 147.03 and 75.36 MPa, respectively, which was smaller than yield strength of its material; the peak stress of the cortical bone and cancellous bone was 53.713, 4.216 7 MPa, and the strain was 3.753 6, 3.562 5, respectively; the maximum displacement of the restoration was 338.3 μm. ConclusionsTaking the canine mandible as an example, the personalized prosthesis with porous and support structure shows the uniform stress distribution and good mechanical properties through finite element analysis. The results provide a new method for the design of prosthesis for repairing mandibular defects.

The Influence of different nutrition treatment approaches in the fibula muscle flap reconstruction of the mandibular defect postoperative patients / 肠外与肠内营养

Objective:NRS 2002 nutritoanl risk assessment and PG-SGA scale were used to evaluate the effect of different nutritional treatments on fibula myocutaneous flap reconstruction of mandibular defect postoperative patients,and to find the appropriate timing and method of nutritional support for this kind of patients.Methods:50 cases of fibula myocutaneous flap reconstruction of mandibular defect postoperative patients were divided into two groups according to the nutritional risk assessment and the opinions of the research team including the mixed nutrition support treatment group (SPNS + EN) and the conventional nutrition support treatment group (TEN).The indexes of the patients on the day before surgery and 1,7,13 postoperative days were monitored,including lymphocyte count (LYM),serum albumin (ALB),hemoglobin (HB),potassium (K),sodium (NA),chloride (CL) and nutritional risk screening score (NRS) and other indicators to evaluate therapeutic effect of two groups.Results:The indicators showed no significant differences in the two groups before operation.For K and Na,the levels of the SPN + EN group was higher than that of the TEN group.Hemoglobin (HB) and NRS score on the 13rd day after surgery were statistically different between the two groups (P ＜ 0.05).Besides,Lymphocyte count (LYM) and chloride (CL) on the 1st and 7th after operation showed significant different,too(P ＜ 0.05).Conclusion:By nutritional risk assessment in patients with NRS 2002 before operation,PG-SGA after operation,we corrected the electrolyte and acid-base imbalance,improved stress state of postoperative patients with adjustment of nutritional therapy and intervention to timely and effectively provide plenty of energy and protein.

Retrospective study on the materials used in the reconstructoin of mandibular defects / 实用口腔医学杂志

objective: To evaluate the clinical effect of various materials used in the reconstruction of mandibular defects retrospectively. Methods: 467 patients with mandibular defects were treated with various implantation materials during last 30 years and 395 of them were followed up.Results: 217 were satisfied with their mouth opening, occlusion and maxillofacial contour after sugery, 189 of them had bone transplanation and 28 had non biomateria transplantaion; 91 were partly satisfied, 72 of them had bone trasplantation and 19 had non biomateria; 87 were not satisfied, 11 of them had bone trasplantation and 76 had non biomaterial. Conclusion: Bone especially auto bone transplantation is more effective than non biomaterial in the reconstruction of mandibular deffects.

The effect of basic fibroblast growth factor on new bone formation in the repairment of mandibular defects / 实用口腔医学杂志

Objective: To study the effects of basic fibroblast growth factor(bFGF) on promoting new bone formation in repairing mandibular defects.Methods: 15 mm?6 mm bilateral mandibular periosteum bone defects were made surgically in 18 adult New Zealand rabbits, the right defects were repaired with natural non organic bone (NNB) combined with bFGF at 40 ng/mm 3, the left defects were repaired with NNB. Specimens were obtained 3, 6, 12 weeks after operation respectively. The effects were evaluated with toluidine blue stain observation, tetracycline fluorescent microscopic examination and computerized quantity analysis. Results: More chondrocytes were observed in the right defects 3 weeks after operation. 3, 6, 12 weeks after operation the new bone formation (?m 2) in the right defects was 66.092?6.379, 130.198?13.213 and 235.374?16.773 respectively; that in the left defects 21.844? 7.731 , 62.694?10.389 and 160.184?14.793 respectively( P