Objective; To evaluate the reliability and reasonability of maxillofacial skin color match using the digital camera. Methods; The stability of the experimental light source was evaluated before establishing the color measurement. 122 volunteers aged from 22 to 32 years were recorded by a Canon EOS 20D digital camera in studio environment when the light source was stable. Photographs were taken under a set exposure parameters(f/4.5,1/25 s,custom white balance,ISO 800) and saved as JPEG format. The CIE L~* a~* b~* color values were obtained from the digital images using Adobe Photoshop7.0 after color correction. All data were analyzed using SPSS 10. 0. Results;The experimental light source was stable in 21 to 70 minutes. It was suitable for color measurement during this period. The color parameters of all tested maxillofacial skin were:L~*49～66,a~*7 - 18,b~*5 -22. Conclusion;The assessment of maxillofacial skin color depend on method of measurement and instrument. The method of maxillofacial skin color matching by digital camera seems reliable.

0.05).The elongation at break of SY-1 was stronger than that of MDX4-4210 (P

Objective: To evaluate the effect of roughness on adhesive properties of polymethyl methacrylate and SY-1 silicone elastomer.Methods:5 specimens of polymethyl methacrylate were polished by sand paper of different standards and the roughness of polymethyl methacrylate surfaces were measured by roughmeter. The tension strength between polymethyl methacrylate with different degrees of roughness and SY-1 silicone elastomer were tested according to national standards. Results: After the surfaces of polymethyl methacrylate were respectively polished by sand paper of the standard 160,320 and 800, the sufrace roughness decreased, but the tension strength between polymethy1 and SY-1 silicone elastomer was increased(P

0.05) respectively. Conclusion: The SY 1 silicon elastomer have suitable physical, mechanical and anti ozone aging properties.

Objective: To study the anatomic structure of the nasopalatine duct and the neighboring bone,provide reference for implant surgery in the incisor region. Methods: Manual quantitative measurement of the nasopalatine duct were performed in 73 maxilla specimens (38 from male and 35 from female). Results: The angle between the anterior wall of nasopalatine duct and the nasal floor was 114.80??11.00?, the angle between the cortical plate of anterior maxilla and the nasal floor 107.28??10.75?, the length of the nasopalatine duct was (15.63?2.18) mm in male, and ( 14.59 ?1.96) mm in female, the width of nasal opening of the duct was ( 4.92 ?1.46) mm in male, and (5.73?1.50) mm in female, the width of oral opening of the duct was (3.23?0.60) mm in male and (3.83?0.92) mm in female, at the level of nasal floor, the distance between the anterior wall of the duct and cortical plate of anterior maxilla was (6.15?1.90) mm. Conclusion: In front of nasopalatine duct, implants should be implanted parallel to nasopalatine duct,with an angle about 115? between the implant direction and nasal floor. The bone in front of nasopalatine duct was thin,the diameter of implants applied here should be less than 4 mm.

Objective: To develop titanium posted keeper removable magnetic attachment and to decrease its influence on magnetic resonance imaging(MRI). Methods: Pre fabricated soft magnetic alloy pin cap keeper(PSAPK), casting non precious alloycoping keeper(CNPAK), casting precious alloy coping keeper(CPACK), titanium post keeper(TPK) and titanium post(TP) were prepared and applied on the maxilla of a volunteer, MRI was taken and measured. Results: ①The attachments producing artifacts in MRI from the biggest to the smallest were listed in following rank: PSAPK, CNPAK, CPACK, TPK and TP. ②After removing the keeper from titanium post keeper, the post had no artifact on MRI. ③The artifact was the smallest taken with SE sequence. Conclusion: Titanium post keeper is an effective way to solve the artifact problem and will bring benefits to the patients who need MRI examination of head.

objective: To study the properties of keepers treated with different methods. Methods: Eighteen Z 3 magnetic attachments were divided into three groups at random. Cobalt chromium alloy was used for root cap. The keepers in the first group were cast to the caps, those in the second group were welded to the caps by Nd:YAG laser welding apparatus. Keepers in the third group were untreated. Universal testing machine was adopted to measure the breakaway retention of the attachments. The roughness of keeper surfaces was measured by roughness tester. Results: No statistical difference was observed as to the breakaway retention between magnetic attachments and laser welded coping keeper or between those and cast coping keepers. But retention of the keepers in the two groups was slightly lower than that of untreated keepers. Defects of pits were found on the surfaces of the cast coping keepers. The surface smoothness of the cast coping keepers was inferior to that of the laser welded coping keepers. Conclusion: Laser welded keepers and cast coping keepers can meet clinical demands for the use of magnetic attachments.

Objective: To study the property of galvanic corrosion of soft magnetic alloy and 4 kinds of dental alloys in simulated oral environment. Methods: 6 samples of Ni Cr, TA 2, Ti75 and 30 of Fe 16Cr 2Mo in the size of d 15 mm?3 mm were prepared and put into artificial saliva. An electrochemical method was used in the measurement of electric potential of corrosion (Ecorr), potential dynamic polarization and galvanic current density of different galvanic couple, the anticorrosive property of four galvanic couples was analyzed statistically. Results: The ecorr value(mV) of Ti75, TA 2, Co Cr,Fe 16Cr 2Mo and Ni Cr was -138.31?2.89, -150.35?1.04, -186.21?3.79, -218.35?0.84 and -240.49?1.73 respectively ( P

0.05);the elongation (%) 470?9.5,560?8.2 and 470?5.8 (SY-1 versus SY-2 or MDX-4-4210,P

Objective: To find out the infinity optical thickness of SY-1 silicone elastomers when color difference(△E) is equal to 1.5 . Methods: Silicone elastomer samples with thickness from 0.5 mm to 10 mm of SY-1 silicone elastomer were measured by CIE-1976-L *a *b * relative to CIE source against a white and a black background by using Minolta colorimeter . Color difference was calculated as △E=[(△L *) 2+( △a *) 2+(△b *) 2] 1/2 . The infinity optical thickness of SY-1 silicone elastomer when △E=1.5 was calculated by regression formulation. Result: When △E was equal to 1.5, the infinity optical thickness of SY-1 silicone elastomer was 7.60 mm. Conclusion: In order to get ideal effect the supports should be treated with colorant when the thickness of silicone elastomer covering the surface of supports in maxillofacial prostheses is thinner than 7.60 mm.