BACKGROUND:Recent research has shown that the proper concentration of aspirin can increase the proliferation and osteogenic ability of MG-63 cells.OBJECTIVE:To explore the effects of different concentrations of aspirin on osteoblast proliferation on the implant-cell interface under fluid shear stress.METHODS:(1) MG-63 cells were cultured in low-glucose DMEM containing 10％ fetal bovine serum and different concentrations of aspirin (0,0.023,0.046,0.0625,0.125,0.25,0.5,1.0,2.0,4.0 mmol/L) for 1-7 days.Then cell proliferation was detected using MTS method.(2) MG-63 cells were cultured on three different surfaces:glass slide,PT titanium surface and SLA titanium surface.After 3 days of culture with aspirin at a concentration of 0 or 0.5 mmol/L,the cells were subjected to fluid shear stress.MTS test was applied to estimate the proliferation of MG-63 cells at 0,0.5,1,2,4 hours after stress application.RESULTS AND CONCLUSION:(1) After 1-3 days of culture,0.023,0.046,0.5 mmol/L aspirin promoted the proliferation of MG-63 cells,while after 1-7 days of culture,1,2,4 mmol/L aspirin inhibited the proliferation of MG-63 cells.(2) Under the fluid shear stress,aspirin showed significant effects on the cell proliferation as confirmed by one-way analysis of variance (F=8.349,P=0.004),and 0.5 mmol/L aspirin inhibited the cellular proliferation of MG-63 cells.However,surface modification and stress loading time showed no significant effects on the cell proliferation (F=2.826,P=0.064;F=0.893,P=0.406).(3) Under the fluid shear stress,surface modification showed no significant effect on the cell proliferation of MG-63 cells cultured with 0.5 mmol/L aspirin (F=1.803,P=-0.171).Under the fluid shear stress,0.5 mmol/L aspirin significantly inhibited the proliferation of MG-63 cells on the glass slide (P=-0.003),while PT and SLA titanium surfaces showed on inhibitory effect on the cell proliferation (P=0.891,P=0.051).The present results demonstrate that the cell proliferation of MG-63 is related with aspirin in a concentration-dependent manner.In addition,different titanium surfaces may decrease the sensitivity of MG-63 cell proliferation to aspirin.

Objective: To analyze the spatial relationship between the roots of maxillary anterior premolars and the maxillary sinus, thus providing an anatomical basis for timing, planning, surgical approaches, and implant selection at this site. Methods: Cone beam CT (CBCT) images were collected from 264 patients (aged 20-65 years) who visited the Ruihua Dental Clinic between January 2017 and March 2023. The minimum distance from the apex of the maxillary anterior premolar roots to the lower wall of the maxillary sinus was measured on the coronal plane. The classification of the vertical relationship between the tooth root and the lower wall of the maxillary sinus was performed, and comparisons were made bilaterally, between genders, and among different age groups. Results: The minimum distance (Q50) from the apex of the first maxillary premolar root to the lower wall of the maxillary sinus was 7.34 mm for the single-root type, 7.80 mm for the buccal root of the double-root type, and 7.36 mm for the palatal root. For the second maxillary premolar, the median distance was 2.56 mm for the single root type, 1.73 mm for the buccal root type, and 1.23 mm for the palatal root type. There was a significant difference in the shortest distance from the apex of the right second maxillary premolar single root to the lower wall of the maxillary sinus among the different age groups (P<0.05), with the 20-29-year-old group having the smallest median distance (1.52 mm) and the ≥ 40-year-old group having the largest (4.44 mm). There was no significant difference in the effect of sex or laterality on distance (P>0.05). The most common vertical relationship between the apex of the maxillary anterior premolar roots and the lower wall of the maxillary sinus was noncontact. There was no significant difference in the vertical relationship classification between the single-root and double-root types (P>0.05). Conclusion Most maxillary first premolar roots can provide sufficient bone height, which makes it easy to achieve immediate implantation. The maxillary second premolar root frequently involves insufficient bone, which is necessary to make full use of the bone wall of the extraction socket or the sinus floor cortical bone to achieve initial stability. The vertical relationship between the premolar root and maxillary sinus was influenced by age and dental position. Younger age groups often exhibit inadequate bone height, and the indication for immediate implantation should be carefully considered. The number of roots does not significantly affect the relationship between the sinus and root; however, double-rooted premolars offer more support for immediate implantation and socket healing due to the small root diameter and bony separation between the roots.