Metal ion release from silver soldering and laser welding caused by different types of mouthwash

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.

The Impact of Commercially Available Dry Mouth Products on the Corrosion Resistance of Common Dental Alloys

Dental implants are thought to be implanted for life, but throughout their lifespan, they function in aggressive oral environment, resulting in corrosion of the material itself as well as possible inflammation of adjacent tissues. Therefore, materials and oral products for people with metallic intraoral appliances must be chosen carefully. The purpose of this study was to investigate the corrosion behavior of common titanium and cobalt-chromium alloys in interaction with various dry mouth products using electrochemical impedance spectroscopy (EIS). The study showed that different dry mouth products lead to different open circuit potentials, corrosion voltages, and currents. The corrosion potentials of Ti64 and CoCr ranged from -0.3 to 0 V and -0.67 to 0.7 V, respectively. In contrast to titanium, pitting corrosion was observed for the cobalt-chromium alloy, leading to the release of Co and Cr ions. Based on the results, it can be argued that the commercially available dry mouth remedies are more favorable for dental alloys in terms of corrosion compared to Fusayama Meyer's artificial saliva. Thus, to prevent undesirable interactions, the individual characteristics of not only the composition of each patient's tooth and jaw structure, but also the materials already used in their oral cavity and oral hygiene products, must be taken into account.

Minimization of Adverse Effects Associated with Dental Alloys

Metal alloys are one of the most popular materials used in current dental practice. In the oral cavity, metal structures are exposed to various mechanical and chemical factors. Consequently, metal ions are released into the oral fluid, which may negatively affect the surrounding tissues and even internal organs. Adverse effects associated with metallic oral appliances may have various local and systemic manifestations, such as mouth burning, potentially malignant oral lesions, and local or systemic hypersensitivity. However, clear diagnostic criteria and treatment guidelines for adverse effects associated with dental alloys have not been developed yet. The present comprehensive literature review aims (1) to summarize the current information related to possible side effects of metallic oral appliances; (2) to analyze the risk factors aggravating the negative effects of dental alloys; and (3) to develop recommendations for diagnosis, management, and prevention of pathological conditions associated with metallic oral appliances.

Nickel ion release from dental alloys in two different mouthwashes

Background . Mouthwashes are widely used as adjuncts to mechanical oral hygiene procedures. Nonetheless, there is little information regarding the effect of various mouthwashes on the amount of ions released from the nickel-chromium (Ni‒Cr) alloys used in the fabrication of fixed prostheses. Therefore, the present study was conducted to evaluate the effect of two types of mouthwash on the release of Ni ions from dental alloys. Methods . Forty-two disk-shaped specimens were prepared with a diameter of 10 mm and a height of 2 mm. Two mouthwashes were examined in this study: Oral B and Listerine. A control group was also considered using distilled water. Each Ni‒Cr disk was immersed in the mouthwashes and distilled water in polypropylene test tubes, and then incubated at 37°C to simulate the oral temperature. After 45 days of incubation, the samples were tested for Ni ions using inductively coupled plasma mass spectroscopy. Data were analyzed using ANOVA. Results . In the Halita group subjects exhibited 2.04±0.65 reduction in OLS. OLS reduction in the chlorhexidine group was 1.95±0.74. Statistical analysis showed no significant difference between the two groups (P>0.05). Conclusion . As the results indicated, the amount of ion release was within the safe limits in the two experimental groups. However, it is recommended that prescribe Listerine mouthwash should not be prescribed for the patients with a history of Ni allergy.

Evaluation of corrosion resistance and surface characteristics of orthodontic wires immersed in different mouthwashes

BACKGROUND

Patients use mouthwashes in addition to mechanical cleaning during orthodontic treatment. The effects of mouthwashes on the archwires have not been examined yet.

OBJECTIVE

To compare the corrosion resistance of four different arch wires and corrosion effects of different mouthwashes to formulate a biocompatible and mechanically useful arch wire and mouthwash combination.

METHODS

Each group comprised of 4 wire samples of 2 cm 0.016 × 0.022 inch. 1st group: ion implanted nickel titanium (INT), 2nd group: nickel titanium, without ion implantation (NT), 3rd group: micro layered esthetic nickel titanium (ENT), 4th group: stainless steel (SS) wires. They were immersed inside 2 ml of artificial saliva solutions (AS) for the control, or AS (9%) combined with 1 of the 3 mouthwashes (91%) for study groups, for 24 hours. These mouthwashes were essential oil (EO), chlorhexidine (CHX), sodium-fluoride (NaF). An electrochemical analyzer was used for electrochemical impedance spectroscopy measurements.

RESULTS

High corrosion resistance was obtained for ENT than the other wires. The corrosion potentials are 0.007, -0.042, 0.074 and -0.015 V (Ag/AgCl) for ENT, INT, SS and NT in the artificial salivary, respectively. In NaF containing mouthwash Rp value of ENT is significantly high in comparison to others. The impedance responses of all materials increased significantly in the presence of NaF mouthwash as well as in the CHX mouthwash. Low frequencies are seen at all materials in EO mouthwash. Diameters of loops are 22, 5.9, 5.9 and 3.7 MΩ at ENT, INT, SS and NT.

CONCLUSIONS

In this study, micro layered esthetic nickel titanium wires are found biocompatible among other wires and NaF and CHX mouthwashes can be recommend for their good corrosion resistance during fixed orthodontic therapy.