ABSTRACT
BACKGROUND: The stress distribution is different between implants and natural teeth, and the biomechanical characters of implant-natural tooth supported fixed partial dentures need to be explored.OBJECTIVE: To analyze the distributions of stress and strain on the implant interface and natural tooth ligaments by loading a vertical force to a single implant crown, natural tooth crown and a implant-natural tooth supported fixed partial denture.METHODS: Two male healthy Beagle dogs were selected, and their right mandibular first molars were exacted under general anesthesia. Three months later, a 3.3 mm×10 mm RN ITI implant was implanted into the defect region of each dog. The dogs were killed under anesthesia after another 3 months to remove the mandible. One dog was restored by a single implant and natural tooth crown, and the other was restored by the implant-natural tooth supported fixed partial dentures. The specimens were fixed to the load device after embedded with self caring acrylic resin, and the strain gauges were pasted to the cortical bone around the implant and natural tooth neck. The vertical force was loaded to the implant, natural tooth and fixed denture with 40, 60, 80,120, and 160 N.RESULTS AND CONCLUSION: When the force was loaded to the implant of combined denture, the implant stress of combined denture was less than that of the single implant repair, and partial force was loaded on natural teeth; when the force was loaded to the natural tooth of combined denture, the stress to the natural tooth of combined denture was less than that of the single natural tooth repair. When the force was loaded to the natural tooth of combined denture, the stress was assumed by the whole prostheses. However, the stress was almost assumed by the implant when the force was loaded to the implant of combined denture. That is to say, it is feasible to use the implant-natural tooth supported fixed partial dentures.
ABSTRACT
<p><b>OBJECTIVE</b>To study abnormal changes of T lymphocyte and its activated subsets in severe acute respiratory syndrome (SARS) patients.</p><p><b>METHODS</b>Flow cytometer with multi-color flouroscence and hematology analyzer were used to detect the expression of T lymphocyte and its activated a subsets in 240 SARS patients including 50 cases of critical type and 190 cases of common type.</p><p><b>RESULTS</b>Statistical analysis by means of SAS software showed that there was significant decrease in absolute counts (AC) of T lymphocyte and its subsets in SARS patients when compared with normal people, while percentages (PC) of CD3+CD25+ and CD3+ HLA-DR+ subsets were increased markedly. Compared with common type, there was significant decrease in absolute counts of critical type of T lymphocyte, CD4+, CD25+CD3+, CD28+CD4+, and CD95+CD4+subsets. The ACs of T lymphocytes including CD4 and CD8 subsets in different phases were as below: III > II > I. The ACs of subsets involved in activation such as CD3+ HLA-DR+/lym, CD3+CD25+/lym, CD28+CD4+/CD4, CD28+CD8+/CD8, and CD38+CD4+/CD4 all were highest in group III. In addition, the AC and PC of CD95+CD4+/CD4 and CD95+CD8/CD8 subset in group III were highest while group I was lowest.</p><p><b>CONCLUSIONS</b>With depressing cellular immunity, the activation of T lymphocytes were suppressed obviously in SARS patients, especially for critical patients.</p>