Osteoprotegerin expression in the peri-implant sulcus fluid after mechanical stimulations at different angles

Fang Ming; Wang Zhi-ying; Yu Jin; Li Min; Jin Ding

doi:10.3969/j.issn.2095-4344

Abstract：BACKGROUND:Because of the limitation of local anatomical structure, 15° to 30° angled abutments are commonly used for implant restoration. Under the condition of oversized angle mechanical force, the ability of the dental implant to resist invasion of patho-microorganism is poorer than natural teeth, which is decided by the structural characteristics of peri-implant tissue interface. OBJECTIVE:To study concentration changes of osteoprotegerin and receptor activator of nuclear factor-kappa B ligand (RANKL) from peri-implant sulcus fluid of cranine mandibular implants under 100 N forces at 0° and 30° angle. METHODS:Six dogs (18 dental implants) were randomly divided into three groups: group A, 100 N 0° group, group B, 100 N 30° group, and group C, non-mechanical stimulation group (control group). The second premolars of the bilateral mandible were extracted, and two dental implants per side were implanted. Cobalt-chromium PFM ful crown was used for tooth restoration 3 months later. After 1 week of ful crown restoration, under general <br> anesthesia of 5% odium pentobarbital, 100 N was given verticaly (0° angle) and at 30° angle, and once worked for 5 seconds on implants, totaly 10 minutes. After 24 hours, 72 hours and 1 week of mechanical force, samples of groups A, B and C were colected from the peri-implant sulcus fluid, and ELISA method was used to detect RANKL and osteoprotegerin levels. RESULTS AND CONCLUSION:After application of 100 N mechanical force verticaly, the RANKL level in the peri-implant sulcus fluid increased obviously at 24 hours, increased continuously at 72 hours, and decreased slightly at 1 week, and there was statisticaly significance compared to the non-mechanical stimulation group (P < 0.05). After dental implant was given 100 N at 30° angle, RANKL level in the peri-implant sulcus fluid raised significantly compared to 100 N 0° angle group, and there was remarkable significance compared to the non-mechanical stimulation group (P < 0.01). The osteoprotegerin level in the peri-implant sulcus fluid decreased after 24 hours of mechanical stimulation at 0° angle, continued to decline at 72 hours, and returned to 24-hour level after 1 week mechanical force application, and there was no statistical difference compared to non-mechanical stimulation group (P > 0.05). The osteoprotegerin level in the peri-implant sulcus fluid declined gradualy over time after 100 N mechanical stimulation at 30° angle, and there was statisticaly significance compared to the non-mechanical stimulation group (P < 0.05). The results indicate that there are increased bone destructive activities from the peri-implant sulcus fluid under 100 N mechanical stimulation at 30° angle, and it is recommended that the occlusion force works along the direction of dental implant axis clinicaly.