ABSTRACT
OBJECTIVE: To study the stress distribution under dynamic loading in the presence or absence of an abutment buffer layer by using three-dimensional finite element analysis. METHODS: A three-dimensional solid geometric model of an implant in a human mandible was established on the basis of CT scan data. A buffer-free abutment prosthesis and a buffer-abutment abutment prosthesis were installed above the implant. The buffer layer was made of high-density polyethylene. A vertical load of 200 N and a horizontal load of 100 N (45°) were concentrated on the centers of the implant restorations of the two groups. Stresses on the implant neck and body, abutment neck and body, central bolt neck and body, and bone interface were compared via three-dimensional finite element analysis. RESULTS: Stresses on the implant neck and body, abutment neck and body, central bolt neck and body, and bone interface on the abutment with a buffer layer were significantly lower than those on the abutment without a buffer layer. CONCLUSIONS: The increase in the buffer layer of the abutment neck significantly reduced stress on the implant neck, abutment, central bolt neck, and bone interface.
Subject(s)
Dental Abutments , Dental Implants , Dental Stress Analysis , Finite Element Analysis , Humans , Stress, MechanicalABSTRACT
PURPOSE: To observe the effects of fluid shear stress on carbonic anhydrase II in rat osteoclasts. METHODS: Osteoclasts were subject to fluid shear stress for 0,15,30,60 and 120 minutes respectively, which was 2.9dyne/cm(2). mRNA level of carbonic anhydrase II was detected through real-time fluorescent quantitation PCR. The data were analyzed with SPSS 12.0 software package. RESULTS: mRNA level of carbonic anhydrase II in control group, 15 minutes,30 minutes,60 minutes and 120 minutes group was 7.88+/-0.09, 11.14+/-0.12, 15.83+/-0.18, 1.94+/-0.02, and 1.37+/-0.01(E+5 copy number), respectively. There was significant difference between any two groups (P<0.05). CONCLUSIONS: In this present study, mRNA level of carbonic anhydrase II has an increasing tendency with various action times of fluid shear stress, it reaches to a peak value at 30 minutes. We speculated that there might be a certain time-effect relation between fluid shear stress and mRNA level of carbonic anhydrase II, but this mechanism need be further studied.
Subject(s)
Carbonic Anhydrases , Osteoclasts , Animals , Bismuth , Cells, Cultured , Organometallic Compounds , RNA, Messenger , Rats , Salicylates , Stress, MechanicalABSTRACT
OBJECTIVE: To observe effects of fluid shear stress strength on mRNA expression of ATP6V1a1 in rat polarized osteoclasts. METHODS: Rat polarized osteoclasts suffered 0.0 (control group), 0.9, 2.9, 8.7 and 26.3 dynes/cm2 fluid shear stress for 30 min. mRNA expression of ATP6V1a1 was detected by Real-Time fluorescent quantitation PCR. RESULTS: mRNA expression of ATP6V1a1 in 0.0 (control group), 0.9, 2.9, 8.7 and 26.3 dynes/cm2 groups was (1.14 +/- 0.06) x 10(6), (1.62 +/- 0.09) x 10(6), (2.28 +/- 0.13) x 10(6), (3.24 +/- 0.18) x 10(6), (9.16 +/- 0.53) x 10(6) copy numbers, respectively (P < 0.05). CONCLUSION: In the present study, polarized osteoclasts are sensitive to fluid shear stress. mRNA expression of ATP6V1a1 has increscent tendency along with increasing of fluid shear stress strength.
Subject(s)
Osteoclasts , Shear Strength , Animals , RNA, Messenger , Rats , Stress, MechanicalABSTRACT
OBJECTIVE: To study the spatial distribution of free Ca2+ in osteoclast-like cells cultured on glass. METHODS: To detect the free Ca2+ in osteoclast-like cells, the images were analyzed with image software, using the laser scanning confocal microscope and fluorescent probe. RESULTS: At 37 degrees C the free Ca2+ in osteoclast-like cells could be labelled effectively with 10 micromol/L Fluo-3/AM, the intensity of Ca2+ fluorescent signal in the central part was greater than that in the peripheral part and in the same section the signal was not distributed evenly. CONCLUSION: The intensity of Ca2+ fluorescent signal is different among various organellae in osteoclast-like cell, which suggests the osteoclast-like cell modulate its own function through the spatial difference of free Ca2+ concentration.