جستجوی مقالات مرتبط با کلیدواژه « calcium sulfate » در نشریات گروه « پزشکی »

Accurate duplication of casts is necessary to fabricate a proper prosthetic appliance with good adaptation. Alginate is an inexpensive impression material and is available in most dental offices. The aim of the present study was to evaluate the accuracy of the casts duplicated using alginate impression mold.

In this in vitro study, at first, a metallic tray and condensational silicone impression material were used to prepare 60 master impressions of a maxillary dental model. The impressions were poured using stone gypsum, and their dimensions were measured via a digital Vernier caliper with accuracy of 0.01 mm. Then, the casts were fixed on the floor of a flask filled with alginate with two folds volume of cold water recommended by the manufacturer. The resulting impressions were immediately poured, and the measurements were repeated. The data were analyzed with SPSS 26 using MANOVA and ICC index (p<0.05).

Statistical analyses showed that dimensional changes of the duplicated casts were not significant relative to the master casts (P=0.90). In addition, insignificantly, the duplicate casts were smaller than the master casts and the dimensional changes in the transverse dimension were more than those in the anteroposterior dimension.  

The results indicated that alginate duplicate impressions taken using the alginate molding technique had good dimensional accuracy when they were poured immediately. Since alginate is inexpensive, this technique can be used in the dental office by saving time to decrease laboratory costs and avoid using expensive impression materials.

Medical grade calcium sulfate hemihydrate (MGCSH) is used as a bone graft material for socket preservation. This study aimed to evaluate the changes in bone width and height after tooth extraction and socket preservation with MGCSH using cone-beam computed tomography (CBCT).

This study evaluated 17 systemically healthy patients over a 1-year period. The patients were selected among those presenting to an outpatient department. CBCT was taken with a radiographic stent and extraction was performed; socket dimensions were measured. Socket preservation was performed using MGCSH. After 3 months, another CBCT was taken, and socket dimensions were measured. The change in socket dimensions was quantified by com-paring the preoperative and postoperative radiographs. Comparisons were made by paired t test.

At 3 mm from the initial ridge crest, the mean bone width was 6.24 ± 1.73 be-fore and 4.74 ± 1.91 mm after 3 months; this difference was statistically significant (P<0.001). At 6 mm, the mean bone width was 7.05 ± 1.50 before and 5.49 ± 1.82 mm after 3 months; this difference was also statistically significant (P< 0.001). At 9 mm, the mean bone width was 7.46 ± 2.16 mm before and 5.71 ± 1.75 mm after 3 months; this difference was statistically significant (P<0.001). The initial mean height was 12.16 ± 2.21mm, which changed to 12.99 ± 2.69 mm at 3 months, with no signifi-cant difference (P=0.22).

Socket preservation with MGCSH caused a significant change in ridge width, but not in ridge height.

The inhibitory effect of selenium nanoparticles (SeNPs) on cancer cells has been reported in many studies. In this study,  the purpose was to compare the in vitro effects of SeNPs and calcium sulfate coated selenium nanoparticles (CaSO4@ SeNPs) on breast cancer cells.

CaSO4@SeNPs and SeNPs were chemically synthesized and characterized with Field Emission Scanning Electron Microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDX). By applying MTT assay, the cytotoxicity effect of both nanomaterials on the 4T1 cancer cells was investigated.

While LD50 of SeNPs on 4T1 cancer cells was 80 µg, the LD50 of CaSO4@SeNPs was reported to be only 15 µg. The difference between the inhibition rates obtained for SeNPs and CaSO4@SeNPs was statistically significant (p=0.05). In addition, at higher concentrations (50 µg) of CaSO4@SeNPs, the cytotoxicity was 100% more than SeNPs alone. 

According to the result of the present work, it can be concluded that decoration of SeNPs with calcium sulfate leads to an increase in potency by decreasing the effective dose. This effect can be attributed to activation of intrinsic apoptosis signaling and/or pH regulatory properties of CaSO4@SeNPs. However, further studies are still needed to determine the exact corresponding mechanisms of this synergistic effect.