[Expression of quorum-sensing related genes during Enterococcus faecalis biofilm formation].

OBJECTIVE: To investigate the relationship between the expression of the quorum-sensing related genes during Enterococcus faecalis(Ef) biofilm formation. METHODS: Ef biofilms model was established in vitro and film formation process was observed by confocal laser scanning microscope at 6, 12, 24 and 48 hours respectively.Quantification of biofilms was achieved by staining with crystal violet.Real-time fluorescence quantitative PCR method was used to detect the expression of fsrB, gelE and sprE genes in the process of Ef biofilm formation. RESULTS: A lot of live and dead bacteria unevenly distributed in Ef biofilm. The quantity of biofilms increased with time within 24 hours and was 0 h:0.00 ± 0.00, 6 h:1.09 ± 0.13, 12 h:2.10 ± 0.79, 24 h:3.30 ± 0.13, which was significantly different among the 4 time period(P < 0.05). The quantity of biofilm at 48 h(3.51 ± 0.01) increased slightly compared with 24 h(3.30 ± 0.13) , but did not show significant difference.Quantitative real-time PCR showed that the expression of quorum-sensing related fsrB increased with time within 24 hours and was 0 h:9.98 ± 0.46, 6 h:23.45 ± 1.13, 12 h:47.30 ± 2.49, 24 h: 331.30 ± 2.18, which was significantly different among the 4 time period(P < 0.05). The expression of gelE was 0 h: 6.54 ± 0.73, 6 h: 14.26 ± 1.24, 12 h: 37.47 ± 2.35, 24 h:264.80 ± 5.10(P < 0.05). The expression of sprE was 0 h: 7.72 ± 0.74, 6 h: 21.15 ± 0.96, 12 h:49.87 ± 3.18, 24 h:441.89 ± 7.74, which was significantly different among the 4 time period(P < 0.05). CONCLUSIONS: The fsrB, gelE and sprE genes are closely related to the biofilm formation in Ef.

[The activity of osteoclast in peri-implant tissues in Beagle dogs].

PURPOSE: To observe the quantity and activity of osteoclast in peri-implant tissues dynamically. METHODS: An animal model of dental implants was established in 6 male Beagle dogs of 1-2 years old. Bone remodeling was tested at 3-, 7-,15-,30-,60- and 90-day after placement of implants. The mandibular bones were taken out and the morphological changes were observed under X-ray examination.Bone tissue samples underwent HE staining. The data were analyzed with SPSS13.0 software package. RESULTS: The most prominent period of osteoclasts occurred at 7-day after placement of implants. After 7 days of implantation, the activity of osteoclast gradually decreased. CONCLUSIONS: The active stage for bone remodelling in peri-implant tissues during unloading period is about 7 days after implantation.

[Expression of receptor activator of NF-κB ligand and osteoprotegerin in peri-implant tissues during unloading period].

OBJECTIVE: To observe the expression of receptor activator of NF-κB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG) during unloading period of dental implants. METHODS: An animal model of dental implants was established in Beagle dogs. Bone remodeling was tested at 3, 7, 15, 30, 60 and 90 days after the placement of implants. RANKL and OPG mRNA expression were quantified by real-time PCR. Then mandibular bones were resected and some sections were observed. RESULTS: The most prominent period of bone remodeling occurred at 7 day after the placement of implants (OPG/RANKL mRNA, 2.15 ± 0.1). The expression of RANKL and OPG increased in a time-dependent manner in both soft and hard tissue. After 7 days they gradually decreased. CONCLUSIONS: Both OPG and RANKL were expressed in peri-implant tissues, and the changing tendency of RANKL and OPGmRNA was consistent with the change of bone remodeling. The active stage for bone remodelling in peri-implant tissues during unloading period is about 7 days after implantation.

[Clinical study of osteotome sinus floor elevation without grafting and with simultaneous implants placement].

OBJECTIVE: To investigate the clinical results of osteotome sinus floor elevation (OSFE) without grafting combined with simultaneous implant placement. METHODS: A total of 65 patients underwent maxillary sinus floor elevation from alveolus without any bone grafting from January 2000 to December 2008 and 96 implants were placed in the maxillary posterior edentulous region simultaneously. Clinical and radiography examinations were performed. The residual bone height ranged from 5 to 8 mm and the mean bone height was (6.78 ± 1.04) mm. The mean following period was 33.4 months. Statistical analysis was performed by chi square test. RESULTS: Ninety-five of 96 implants were clinically stable and functioned without any pain and other complaints. One implant was extracted 15 days after operation because of mobility and the other implants obtained osseointegration. The mean implant protrusion length was 2.6 mm, ranging from 1 to 5 mm. Different degree of new bone formation was observed in 51 (54%) of implants. New maxillary sinus floor outline was observed in 33 (35%) of implants and there was no obvious new bone in 11 (12%) of implants. There was no significant deference between the implant protrusion length and sinus floor remodeling. CONCLUSIONS: Under strict indications, the clinical results of OSFE without bone grafting combined with simultaneous implant placement were predictable in short term. The new sinus floor formation was not related to the implant protrusion length.

[Clinical study of immediate placement and early loading of dental implants].

OBJECTIVE: To evaluate the clinical results of immediate placement and early loading of dental implants. METHODS: Sixty-four dental implants were inserted into the edentulous section of 37 patients immediately after the teeth were extracted. 36 implants were inserted by one-stage operation procedure, of which 17 implants were loaded immediately in 3 edentulous jaws by temporary mandibular overdenture. Fixed crown restoration were completed on 14 implants in 1 - 2 months and on 22 implants in 3 - 4 months. The two-stage operation for another 28 implants were performed after 3 - 6 months and then were restored by routine methods. RESULTS: All implants were inserted successfully and stable. There was no peri-implantitis and X-ray films indicated that no remarkable bone resorption occurred. There were no significant differences in the peri-implant depths of gingival pocket between early loading implants and routine restoration. CONCLUSIONS: Dental immediate implant and early loading after implantation can shorten the treatment period of implant-supported prosthesis. The short-term clinical performance was not different from the routine method.