فهرست مطالب alireza fathiazar

Nickel-titanium (NiTi) rotary files were introduced to optimize root canal instrumentation in endodontic treatment. However, despite the numerous advantages of NiTi instruments, they may unexpectedly break during clinical use, resulting in obstruction of the root canal system. This investigation aimed to assess the effect of cryotherapy on fracture resistance of Neoniti rotary files.

This in vitro, study was conducted on 20 Neoniti rotary files with #35 tip size and 6% taper in two groups with and without cryogenic treatment (N=10). For cryogenic treatment, the files were immersed in liquid nitrogen at -196°C for 24 hours. Next, the Neoniti files in both groups were subjected to cyclic fatigue testing in a hand-piece operating at 500 rpm with 20 N/cm torque. The files were rotated until fracture and the fracture time as well as the number of cycles to fracture were recorded for each file. The two groups were compared by independent t-test at 0.05 level of significance.

The number of cycles to fracture was 235700±50649.22 in the control and 280600±22979.21 in the cryotherapy group. The mean fracture time was 471.40±101.29 and 561.20±45.958 seconds in the control and cryotherapy groups, respectively. Significant differences in both variables were noted between the two groups (P<0.05).

Based on our findings, utilizing cryogenic treatment may enhance the fracture resistance of rotary instruments, making it a beneficial practice for dental clinicians to adopt. By using cryogenically treated rotary instruments, clinicians can potentially reduce the risk of file fracture during dental procedures.

Statement of the Problem: 

Subepithelial connective tissue graft (SCTG) is the gold standard treatment for root coverage procedure; however, this technique has limitations such as the need for a donor site and the difficulty of the harvesting procedure.  The potential benefits of Mucoderm®, a collagen matrix derived from porcine dermis, as an alternative treatment for root coverage can be investigated.

This study aimed to evaluate the efficacy of Mucoderm® for root coverage and compare its results with SCTG.

This double-blind split-mouth randomized clinical trial was conducted on seven patients with 12 bilateral gingival recessions (24 recession sites). Coronally advanced flap + Mucoderm® was applied on one side and coronally advanced flap + connective tissue graft (CTG) was applied on the contralateral side. We measured the periodontal pocket depth (PPD), clinical attachment level (CAL), recession depth (RD), keratinized tissue width (KTW) and gingival thickness (GT) with a surgical stent at baseline (preoperatively) and at 1, 3 and 6 months postoperatively. The Wilcoxon and Friedman tests were used to analyse the data.

The mean percentage of root coverage was 26% in the Mucoderm® group and 60% in the SCTG group at 6 months, compared with baseline. The mean percentage of root coverage was significantly different between the two groups (p Value<0.05). The results indicated that Mucoderm® did not increase the KTW, while CTG significantly increased the KTW (p Value< 0.05 at 1, 3 and 6 months).

The results of this study showed that Mucoderm® might not be an appropriate alternative for the CTG in root coverage procedures.

The aim of the study was to evaluate osteopromotive ability of human tooth powder and compare it to a bovine xenograft, a synthetic material and the DFDBA allograft.

This was an in vitro study. 30 teeth without caries, inflammation, infection, which have been extracted due to orthodontic reasons, have been gathered. The crowns were removed and they were treated with pulpectomy and then grinded to a powder with particles less than 500 microns. Osteoblast-like cells of MG-63 was cultured with tooth powder, Cerabone, DFDBA and Osteon II. Cell proliferation was assessed by MTT test in 24 and 72 hours. The Alizarin red test was done after 3 and 5 days. To assess the osteoblastic activity, amount of Alkaline Phosphatase was measured in 24, 48 and 72 hours. The results were analyzed by one-way ANOVO analysis.

According to the MTT test, all of the materials had a higher proliferation rate than the control group in 24 hours. In 72 hours, DFDBA with concentrations of 40 and 80 mg/ml had the lowest cell proliferation rate. DFDBA and the positive control group was able to create calcified nodules by Alizarin red test. In 48 and 72 hours, DFDBA with concentration of 40 mg/ml had the lowest alkaline phosphatase activity. In 72 hours, bovine xenograft had the highest alkaline phosphatase level and the synthetic material and tooth powder were after that.

Tooth powder was able to increase cell proliferation in comparison with the bovine xenograft, the synthetic graft and the DFDBA. However, its osteopromotive ability was less than the osteogenic materials.

Plaque-induced gingivitis is a common gingival disease. There are some limitations in mechanical methods to promote plaque control which is why chemical methods have been introduced. Chemical toothpastes have side effects like hypersensitivity and staining, so the tendency is growing towards herbal toothpastes. Our aim in this study was to evaluate the effectiveness of Aloevera tooth paste on gingivitis. This was a Single blind cross over clinical trial study which was conducted on 20 dental students ( 10 male, 10 female with the average of 24.5±4 years) who had gingivitis. Then, they were divided into 2 groups: The first group used the Aloevera toothpaste for 30 days and PI and GI was recorded. They had been washed out for 2 weeks and after that they used the Fluoride toothpaste for another 30 days. Again, PI and GI was recorded. In the second group the toothpastes were used in an opposite order. The Wilcoxon test was used to evaluate statistical analysis.the level of significance was set as 0.06. There was no significant difference in periodontal records between toothpastes after 30 days of administration. After 30 days, PI changed from 2.14±1.3 to 1.84±1.02(P<0.098) and GI changed from
0.74 ±0.62 to 0.25±0.46(P<0.068) and the P-value between the toothpastes was P<0.07 for PI and P<0.308 for GI. Aloevera toothpaste may have the same effect on PI and GI as the Fluoride tooth paste, So it can be concluded the this toothpaste could be used instead of conventional chemical toothpastes.