Objective:To compare the marginal and internal fit of selective laser melting(SLM)titanium crowns with lost-wax cast (LW)titanium crowns.Methods:Titanium crowns of 10 subjects were fabricated by SLM and conventional LW respectively(n =10).The marginal and internal gaps of the crowns were recorded with silicon film using a replica technique.Each silicon film was cut into 2 parts and the thickness of silicon layer was measured at ×100 magnification using a stereomicroscope,the data of marginal gap (MG)and internal gap(IG)were statistically analysed by ANOVA and SPSS statistical package version 17.0.Results:The MG (μm)of the titanium crowns of SLMgroup and LMgroup were 90.67 ±14.7 and 94.77 ±21.9(P <0.05),IG were 213.73 ±90.4 and 217.00 ±97.7(P >0.05),respectively.Conclusion:The marginal fit of the SLMcrowns is better than that of the LW ones,and is significantly smaller than 120 μm of the clinical generally accepted standards.

Objective:To compare the adaption of cobalt-chromium prostheses fabricated by selective laser melting(SLM)and conven-tional lost wax technique(LW)method.Methods:Cobalt-chromium crowns and three-unit fixed dental prostheses(FDPs)were fabrica-ted by selective laser melting(SLM)or by conventional lost wax technique(LW)respectively(n =5).Marginal fit and internal fit were examined using a light-body silicone.After setting,each silicon film was cut into 2 parts and the thickness of silicon layer was measured at 1 00 ×magnification using a digital microscope,the data of marginal gap(MG)and internal gap(IG)were statistically analysed by ANOVA and SPSS statistical package version 1 7.0.Results:The MG and IG(μm)of cobalt-chromium alloy crowns in EOS M270 group were 42.28 ±1 1 .58 and 1 25.75 ±47.67,in EOS M280 group 46.54 ±8.4 and 1 28.22 ±54.1 8,in LW group 48.66 ±1 2.08 and 1 35.37 ±46.89.The MG and IG(μm)of three-unit FDPs in EOS M270 group were 40.55 ±1 0.04 and 1 33.09 ±39.80,in EOS M280 group 45.36 ±1 0 and 1 38.94 ±50.61 ,in LW group 54.24 ±1 2.04 and 1 51 .87 ±61 .94(P <0.05),respectively.Conclu-sion:The marginal fit of the SLMgroup is superior to that of the LW group and significantly smaller than 1 20 μm of clinical generally accepted standards.SLMsystem can satisfy the clinical requirements.

The Guarding field theory is a unique theoretical system of traditional Chinese medicine for the treatment of surgical diseases such as scabies, sores and gangrene. The hooping in place is the best performance of Guarding field theory. This paperreviews the research progress of Guarding field theory from the aspects of theoretical research, basic research, clinical research in recent years, which shows the connotation of this theory has been expanded. and the generalized concept of Guarding field theory refers to human's healthy Qi, and the field theory has been widely used in treating diseases likemalignant tumor, postoperative anorectal infection, refractory wound to guide clinical treatment.