Cytotoxicity, genotoxicity, and cellular metal accumulation caused by professionally applied fluoride products in patients with fixed orthodontic appliances: A randomized clinical trial

DNA fragmentation of lymphocytes and sperm cells induced by nickel released from orthodontic archwires: A preliminary study

Orthodontic brackets and archwires placed intraorally are subject to corrosion, leading to the release of cytotoxic metal ions. The aim of this study was to determine whether the use of orthodontic NiTi archwires increases systemic Ni levels and cause alterations on the DNA of cells unrelated to the oral environment such as lymphocytes and sperm cells. Human urine, semen and blood samples were collected before (baseline) sham placement of orthodontic archwires and 15 and 30 days after placement. Lymphocytes and sperm cells cells were evaluated by comet assay. Ni concentration levels in urine increased significantly between baseline and 15 days (p<0.01) and 15 and 30 days of exposure (p<0.01). Progressive decrease in sperm viability and motility was observed between the sampling periods. Lymphocytes and sperm cells showed DNA fragmentation. The increase in systemic concentration of nickel induced structural damage in the DNA of lymphocytes and human sperm cells.

Long-term changes in thickness, live/dead bacterial ratio, and mineral content in biofilm on ceramic and stainless steel orthodontic attachments

PURPOSE

Fixed orthodontic appliances induce biofilm deposition, which harbors a microbial population harmful to the periodontal health of the individual. The present study evaluated the changes in thickness, live/dead bacterial ratio, and mineral content in dental biofilm over 6 months in patients with either stainless steel or ceramic orthodontic attachments.

METHODS

Eighty patients who require fixed orthodontic appliance treatment with first premolar extraction for correcting their malocclusion were selected and bonded with either stainless steel or ceramic orthodontic attachments on the buccal side. The attached buttons were retrieved at different periods-1 week, 1 month, 3 months, and 6 months. They were stained and visualized through confocal microscopy to detect biofilm thickness and the ratio of live/dead bacteria. X‑ray diffraction was used to identify the presence of calcium and phosphorous.

RESULTS

Ceramic attachments showed a greater increase in biofilm thickness in comparison to stainless steel attachments except in the initial 1‑week evaluation. A higher live/dead bacterial ratio was observed in stainless steel attachments than in their ceramic counterparts at all four evaluation periods. Both stainless steel and ceramic surfaces exhibited the presence of mineral deposition (calcium and phosphorous) at all periods.

CONCLUSIONS

More biofilm adhesion was observed over ceramic surfaces than over stainless steel orthodontic attachments. Stainless steel attachments exhibited biofilm with a higher live/dead bacterial ratio than their ceramic counterparts at all evaluation periods. The presence of calcium and phosphorous in the adhered biofilm, pointing toward its calcification process, was identified.

Clinical Prospective Assessment of Genotoxic and Cytotoxic Effects of Fluoride Toothpaste and Mouthwash in Buccal Mucosal Cells

Background: Fluorides are an essential component of oral hygiene products used to prevent dental decay. Therefore, a question arises about the potential harms of joint use of fluoridated toothpaste and mouthwashes regarding the increased amount of fluoride in the oral mucosa. Methods: This prospective, double-blinded parallel randomized clinical trial was conducted using a buccal micronucleus cytome assay (BMCyt assay). Forty-one participants were randomly assigned to the two groups. All participants used the same kinds of toothpaste for 12 weeks, designed explicitly for this study (non-fluoride, 1050 ppm F, and 1450 ppm F each for 4 weeks). Simultaneously, during the 3 months of the research, one group used mouthwash with fluoride (450 ppm) and another without fluoride. The buccal mucosal sampling was taken before using the tested products and after 4, 8, and 12 weeks of their use. Results: The frequency of micronuclei and the majority of other scored endpoints from the BMCyt assay showed no statistically significant differences within and between the studied groups. Comparing two groups, only statistically significant increases in the number of cells with nuclear buds (p = 0.048) and karyorrhexis (p = 0.020) at four weeks of usage were observed in the group that used mouthwash with fluoride. Conclusion: On the basis of the results, it can be concluded that simultaneous application of fluoridated toothpaste and fluoride mouthwash does not lead to cytogenetic damage in buccal mucosal cells.