BACKGROUND: Micro-implant screws as an absolute anchorage, instead of traditional anchorage that requires patient's high matching and affects beauty, has been paid more attention.OBJECTIVE: To compare the changes in 3 different places following implantation of micro-implant screws. DESIGN, TIME AND SETTING: The controlled study was performed at the Hospital of Stomatology Affiliated to Foshan College of Sciences and Technology from January 2004 to December 2007.PARTICIPANTS: A total of 45 patients who demand powerful anchorage during the orthodontic treatment were assigned to 3 groups: free gingiva group, mucogingival junction group, and mucosa group.METHODS: By using incomplete flap micro-implant screw implantation, micro-implant screws were implanted in the free gingiva, mucogingival junction and mucosa, with 30 screws in each area.MAIN OUTCOME MEASURES: Loosening and defluvium of micro-implant screws were measured. Pain duration and degree were determined in patients undergoing implantation of micro-implant screws 7 days following surgery. Soft tissue surrounding the micro-implant screws and bleeding rate during probing were detected 56 days following surgery.RESULTS: The number of screw loosening was greatest in the free gingiva group (9 screws), while lowest in the mucogingival junction group (2 screws). Patients suffered from severe flare and pain in the mucosa, and the reaction was mild in the free gingiva following implantation. The reaction was not obvious, but severe pain was found in the mucogingival junction following implantation compared with the free gingiva. Soft tissue surrounding the micro-implant screws and bleeding rate during probing were greater in the mucosa group than in the free gingiva group and mucogingival junction group (P<0.05).CONCLUSION: The incomplete flap micro-implant screws in the mucogingival junction contribute to the increase in success implantation rate and the decrease in inflammatory degree, and prevent the occurrence of potential risk.

Objective To investigate the variations in the pol region of HIV-1 strain in treatment failed patients in Yunnan province's Dehong prefecture and Kunming. Methods Blood samples were collected from 139 patients who experienced treatment failure ( HAART treatment ＞ 1 years and HIV-1 RNA Viral load ＞ 1 000 copies/ml). HIV-1 RNA was extracted from plasma, and nested-PCR was performed for amplification of PR and RT genes on the HIV-1 pol region. The PCR products were then sequenced and submitted to Stanford HIV Drug Resistance Database for comparison. The evolution tree was built up with MEGA 4. 1 system, combined with patients' demographics. Results The most prevalent mutation in Kunming patients were T215F/N/Y/I, M41L/M, and T69G/N/I/S/A/D, the mutation rates were 39%(24/62), 27% (17/62) and 27% (17/62) , respectively, which were higher than the corresponding mutations in the Dehong prefecture [16% ( 11/69), 13% (9/69) and 9% (6/69)]. The rate differences were statistically significant ( x2 = 8.646, 4.242 and 7. 909, all P ＜ 0.05 ). The most common HIV-1 pol region subtype in the Dehong patients were CRF01_AE subtype (32%, 22/69), followed by C subtype (25% ,17/69), and B subtype ( 19%, 13/69). Major subtypes in Kunming patients were 08_BC (60%,37/62 ), CRF01_AE subtype(21% , 13/62 ) and 07_BC ( 15% ,9/62). Conclusions Partial differences of the point mutations of the HIV-1 strain pol region and frequency of their occurrences exist among Dehong and Kunming patients, HIV-1 strains in Dehong prefecture for the NNRTIs mutations at the T215 Y/N/T, M41L and T69G/N/I/S/A/D are significantly higher than those in Kunming. Six isoforms are found respectively:CRF01_AE, B, C, BC, 08_BC and 07_BC from the epidemic strains of HIV-1 pol region subtype in Dehong and Kunming areas.