Figure 1: PRISMAdiagram selection component of the studies.

RESULT:

Table 1: Summarizes the descriptive component of the studies

No	Title	Author, Publisher	Objective	Method	Result
1	Ion Release from Orthodontic Brackets In 3 Mouthwashes: An In-Vitro Study	Danaeiet al. (2011)⁴ American Journal of Orthodontics	Knowing that the stainless steel orthodontic bracket can release metal ions into the saliva	One hundred and sixty stainless steel brackets (0.022-in, 3M Unitek, Monrovia, Calif) were randomly divided into 4 equal groups. Soaked in Oral B chlorhexidine and Persica, control Deionized water Mouthwash and distilled deionized water and incubated at 37 ° C for 45 days. The nickel, chromium, iron, copper and manganese released from the orthodontic bracket were measured by an inductively coupled plasma spectrometer. For statistical analysis: (ANOVA) and Duncan	Oral B Ni: 171.5 ± 18.4 Cr: 90.7 ± 8.9 Chlorhexidine Ni: 1198.3 ± 36.4 Cr: 484.8 ± 39.5 Persica Ni: 109.7 ± 4.4 Cr: 25.1 ± 2.3 Deionized water Ni: 2627.4 ± 151.0 Cr: 838.1 ± 32.9
2	Metal Release Profiles of Orthodontic Bands, Brackets, And Wires: An In Vitro Study Schwermetallfreisetzungsprofile Aus Kieferorthopa¨Dischen Ba¨Ndern Brackets Und Dra¨Hten: Eine In-Vitro-Untersuchung	Wendl et al. (2017)⁶ J Orofac Orthop	This study evaluated the temporary removal of Co Cr, Mn, and Ni from the components of a typical orthodontic appliance during simulated orthodontic treatment.	Several types of commercially available bands, brackets, and wires were exposed to an artificial saliva solution for at least 44 days. The metal released is measured periodically using an inductively coupled quadrupole plasma mass spectrometry. The corrosion products found in some of the products were investigated with a scanning electron microscope equipped with an energy dispersive X-ray (EDX) microanalyzer.	3 M Unitek 0.70 ± 0.05 Cr, 5.9 ± 0.2 (c)Ni Dentaurum 1.72 ± 0.08Cr, 3.5 ± 0.1Ni BR Ormco 5.3 ± 0.2 Cr, 30.5 ± 0.9 Ni
3	In Vitro Corrosion of Metallic Orthodontic Brackets: Influence Of Artificial Saliva With And Without Fluorides	Saporeti, et al. (2012)⁸ Dental Press Journal of Orthodontics	Verifies the corrosion resistance of metal brackets, evaluates aspects of electron microscopy (SEM) and residual components	The sample consists of 17 bracket sets of four metal alloys: Titanium, Cobalt-Chromium. Immersion in 50 ml of artificial saliva (ph 6.5) and four in saliva (ph 6.5) containing fluoride (2 g / l) Semquantitative evaluation of the chemical composition of surface residues by SEM-EDS and the number of ions released in saliva on the evaluation of atomic absorption spectrophotometry.	Semi-quantitative analysis (SEM-EDS) of residual surface chemical composition after 11 weeks of immersion in artificial saliva showed chromium (19.32%) from 26.01% of the material.
4	Nickel Release from New Conventional Stainless Steel, Recycled, And Nickel-Free Orthodontic Brackets: An In Vitro Study	Sfondrini et al. (2010)⁹ American Association of Orthodontists	This study aims to compare nickel released from 3 types of orthodontic brackets: new conventional stainless steel, recycled stainless steel, and nickel-free brackets.	This in vitro study was conducted using the classic batch procedure. Samples were immersed in artificial saliva at various levels of acidity (ph 4.2, 6.5, 7.6) for extended time intervals (0.25, 1, 24, 48, and 120 hours). The amount of nickel released is determined using an inductively coupled atomic absorption spectrophotometer and plasma atomic emission spectrometer.	The recycling bracket emits the most nickel (74.02 6 170.29 mg per gram); new stainless steel bracket released 7,14 6 20,83 mg per gram. The nickel free bracket releases the least amount of nickel (0.03 6 0.06 mg per gram).
5	Ion Release from Orthodontic Brackets in Three Different Mouthwashes and Artificial Saliva: An In Vitro Study.	Gajapurada et al. (2016)¹⁰ IOSR Journal of Dental and Medical Sciences	- Evaluate and compare the release of various metal ions released from the brackets in each solution.	Bracket orthodontic premolars into solution; (chlorhexidine, listerine, colgate plax and artificial saliva. Stored in an incubator at 37˚c for about 45 days. The amount of ion released is measured by the atomic absorption spectrophotometer.	The release was significantly higher than 3 mouthwashes. The average ion released in the artificial saliva group was 4.98, and nickel was 0.92
6	Ion Release and Galvanic Corrosion Of Different Orthodontic Brackets And Wires In Artificial Saliva	Tahmasbi et al. (2017)¹¹ Journal of Contemporary Dental Practice	To investigate the galvanic corrosion of brackets manufactured by four different companies which were combined with stainless steel (SS) or nickel-titanium (nickel) wire in an artificial saliva solution.	A total of 24 mandibular central incisor brackets from four different factories. Corrosion rate (CR) is calculated, and measured with a spectrometer. Then, the samples with corrosion are assessed by electron microscopy and energy-dispersive X-ray spectroscopy.	Dentaurum, American Ortho, Shinye, ORJ Ni 37 ± 20/042; 45 ± 31; 293/123 ± 365/66; 44/66 ± 35/50 Cr 26 ± 6/92; 26 ± 6/92; 15/33 ± 4/61; 15/33 ± 4/61
7	Cytotoxic Effects of The Nickel Release From The Stainless Steel Brackets: An In Vitro Study	Pillai et al. (2013)¹² Journal of Pharmacy and Bioallied Sciences	To determine whether nickel released from stainless steel brackets has a cytotoxic effect on gingival fibroblasts.	Two complete sets of maintenance brackets for each manufacturer, consisting of 20 brackets in each set produced by; (3m gemini metal brackets, american orthodontics, morelli orthodontics brazil), each with 0.022 inches (0.56 mm). Salt solution samples processed for inductively coupled plasma atomic emission spectroscopy (icp - aes)	The results showed that the leached amount of nickel was able to damage fibroblasts. The study concluded that nickel solutions at a minimum concentration of 1.18 μg can damage human gingival fibroblasts and the released nickel.
8	Effects of Fixed Orthodontic Treatment Using Conventional Versus Metal-Injection Molding Brackets On Salivary Nickel And Chromium Levels: A Double-Blind Randomized Clinical Trial	Amini et al. (2015)¹³ European Journal of Orthodontics	The aim of this study was to measure the levels of ions in saliva during 1 year of orthodontic treatment.	Saliva samples were taken from 30 orthodontic patients who were divided randomly into two groups, namely conventional bracket and MIM bracket, before treatment and 2 months later. Nickel and chromium levels are determined using atomic absorption spectrophotometry. Data were analyzed using repeated measurement two-way covariance analysis, independent sample t-test, chi-square, Spearman and point-biserial correlation coefficients, Mann-Whitney test, and Wilcoxon (α = 0.05)	Nickel levels increased from 7.87 ± 8.14 to 12.57 ± 9.96 (2nd month) in the control group, and from 8.62 ± 9.85 to 8.86 ± 6.42 µg / l in the MIM group. The mean Cr level changed from 0.25 ± 0.56 (pretreatment) to 0.35 ± 0.62 and from 0.42 ± 0.48 to 0.26 ± 0.57 µg / l in the MIM group.
9	An In Vitro Comparison of Nickel And Chromium Release From Brackets	Haddad et al. (2009)¹⁴ Orthodontics Brazilian Oral Research	This study aims to compare the amount of nickel (Ni) and chromium (Cr) released from the brackets of various manufacturers in the simulated oral environment.	The 280 brackets are evenly divided into 7 groups according to the manufacturer. 6 bracket groups are stainless steel, and 1 bracket group is made of cobalt-chromium alloy with low Ni content (0.5%). The international standard ISO 10271/2001 is applied to provide a test method. Each bracket was immersed in 0.5 ml of synthetic saliva (SS) or artificial plaque solution (PF) for 28 days at 37 ° C. The solution was changed every 7 days. Analysis by spectrometry. The Kruskal-Wallis test was applied	The amount of Ni release in SS (stainless steel) (µg L 1 per week) varied between groups from "lower detection limits" to 694, and from 49 to 5,948.5 in PF. The amount of Cr detected in SS and in PF (µg L - 1 per week) was from 1 to 10.4 and from 50.5 to 8.225, respectively.
10	In Vitro - Evaluation of Biodegradation of Different Metallic Orthodontic Brackets	Hussain et al. (2012)¹⁵ Journal of International Dental and Medical Research	This study aims to evaluate the chemical changes and structure of metal orthodontic brackets by in vitro biodegradation process in artificial saliva.	A total of 240 metal orthodontic brackets from two different manufacturers were used, orthodontics (LG Stainless-Steel (AISI 316L), USA) and Dentaurum (equilibirium @ mini, stainlesssteel, Germany) The control group was immersed in distilled water and the experimental group was immersed in artificial saliva for 28 days at 37 ° C mechanically. The release of ion concentration was determined using plasma mass spectrometry	Dentaurum Ni: -0.12 Cr: 0.005 American Ortho Ni: 0.01 Cr: 0.006
11	Comparative Evaluation Of Nickel Discharge From Brackets In Artificial Saliva At Different Time Intervals	Jithesh et al. (2015)¹⁶ Journal of Pharmacy And Bioallied Sciences	To determine and compare the difference in nickel release potential of three different orthodontic brackets, at different artificial pHs, in different time intervals.	Twenty-seven samples from three different orthodontic brackets were selected and classified as 1, 2, and 3. Each group was divided into three subgroups depending on the orthodontic bracket type, salivary pH and time interval. Nickel release from each subgroup was analyzed using an inductively coupled model of the Plasma-Atomic Emission Spectrophotometer (Perkin Elmer, Optima 2100 DV, USA). The quantitative analysis of nickel is carried out three times,	In this study, nickel release from recycled stainless steel brackets had the highest value at all pH 4.2 at 1.2 ppm
12	Nickel Release from Stainless Steel and Nickel Titanium Archwires – An In Vitro Study	Hussain, et al. (2016)¹⁷ Journal of Oral Biology and Craniofacial Research	This study was conducted to evaluate and compare the release of nickel from stainless steel wire and nickel titanium wire in artificial saliva for three months using simulated fixed orthodontic appliances.	Five groups (Group A, stainless steel bracket control group without archwires. Groups B and C contain stainless steel archwires from American Orthodontics and Dentaurum (Remanium, Ispringen, Germany). Groups D and E contain stainless steel archwires from American Orthodontics and grade copper from American Orthodontics. Ormco (Glendora, CA)). Each. The amount of nickel released from the device into artificial saliva was measured after 1 day, 7 days, 1 month, 2 months and 3 months. The average release was calculated by Kruskal-Wallis and Mann-Whitney U test.	Control Group A (without archwire);Ni: 13.75 ppb ppb
13	In Vitro Evaluation of Corrosion and Cytotoxicity Of Orthodontic Brackets	Costa, et al. (2007)¹⁸ International and American Associations for Dental Research	To give insights into corrosion resistance brackets AISI 304 (AISI 304 SS) and manganese (lownickel SS) stainless steel in artificial saliva	The two types of orthodontic brackets tested were: (i) 0.022 AISI 304 SS slot (Roth Light®, Morelli-Brazil), and (ii) 0.022 SS manganese slot (Monobloc® nickel free, Morelli-Brazil). The compositional elements were analyzed by energy dispersive spectroscopy (EDS, model XL-30; EDAX, Philips) (Appendix Table). The brackets were maintained in immersion and stored at 37 ° C in stationary conditions for 21, 42, and 63 days. Atomic absorption spectroscopic analysis	304 AISI stainless steel Ni: 21 Day; 0.47 ± 0.07 42 Day; 4.46 ± 0.68 63 Day; 2.98 ± 0.73
14	Chromium Release from New Stainless Steel, Recycled and Nickel-Free Orthodontic Brackets	Sfondrini et al. (2008)¹⁹ American Journal of Orthodontics and Dentofacial Orthopedics	To test the hypothesis that there is no difference in the amount of chromium released from the new stainless steel bracket, the recycled stainless steel bracket, and the nickel-free (Ni-free) orthodontic bracket.	This in vitro study was conducted using the classic batch procedure The amount of chromium released is determined using an inductively coupled atomic absorption spectrophotometer and a plasma atomic emission spectrometer.	The amount of chromium new stainless steel bracket (0.52 1.083 g / g), the recycled bracket releases 0.27 0.38 g / g. Ni-free bracket (0.21 0.51 g / g).
15	Comparison of Ion Release From New And Recycled Orthodontic Brackets	Huang et al. (2001)²⁰ American Journal of Orthodontics and Dentofacial Orthopedics	The aim of the study was to compare the release of metal ions from the new and recycled brackets in artificial saliva and buffers with different ph values over a 12 week immersion period.	The brackets are divided into 2 groups: new and recycled. The recycled bracket base is coated with adhesive and the bracket is heat treated. Nickel, chromium, iron, and manganese ions are detected by atomic absorption. The surface characteristics of the bracket were examined by energy dispersive radiographic analysis	- Dentaurum; Unitek; Tomy; Ormco Ni: 31.37 ± 1.39, 203.9 ± 10.33; 12.67 ± 0.75, 61.45 ± 4.88; 7.99 ± 0.29, 140.51 ± 4.05; 9.30 ± 1.37, 335.08 ± 14.04 - Cr: 2.46 ± 0.10, 3.91 ± 0.41; 2.15 ± 0.11, 3.54 ± 0.24; 1.88 ± 0.04, 3.33 ± 0.03; 1.79 ± 0.09, 3.09 ± 0.26;
16	Nickel Ion Release from Stainless Steel Brackets in Chlorhexidine And Piper Betle Linn Mouthwash	Deriaty et al (2018)²¹ Dental Journal (Majalah Kedokteran Gigi)	This study aims to measure the release of nickel ion stainless steel bracket immersed in chlorhexidine mouthwash and Piper betle Linn.	Thirty-six stainless steel brackets soaked in artificial saliva, chlorhexidine and Piper betle Linn mouthwash. All brackets were stored in the incubator for 1, 3, 5, and 7 weeks. The release of nickel ions is measured by Atomic Absorption Spectrophotometry (AAS)	Uji Kruskal-Wallis ion nikel yang dilepaskan dalam saliva buatan, dalam 1, 3, 5, 7 minggu ; 0.0073 ± 0.00577, 0.0103 ± 0.00577, 0.0113 ± 0.00577, 0.0133 ± 0.00577
17	Evaluation of Determinants For The Nickel Release By The Standard Orthodontic Brackets	Soni et al. (2018)²² International Orthodontics	This study aims to assess the effect of differences in pH and duration of immersion on the amount of nickel released from the orthodontic appliance simulation by the company Unitek 3 M.	Nickel ion release was evaluated after inserting the bracket into the simulated artificial mouth environment. In this study, 90 stainless steel brackets of the Unitek Company 3 M were tested By soaking it in artificial saliva ph 4.2, ph 6.5 and ph 7.6 Time intervals of 1 hour, 1 week and 1 month (T1 - 1 hour, T2). - 7 days, T3 - 30 days) each. One-way ANOVA and post-hoc test data for statistical comparisons.	For pH 4.2 at time intervals of 1 hour, 7 days and 1 month, respectively; 2.99 ± 0.77, 9.53 ± 4.26 and 12.65 ± 2.52 ppb (parts per billion volume) of nickel were released. For pH 6.5 with intervals of 1 hour, 7 days and 1 month, respectively; 5.37 ± 2.26, 10.94 ± 1.51 and 16.92 ± 1.69 ppb nickel were released. Mean 2.13 ± 0.92.
18	Uji Pelepasan Logam Kromium (Cr) Dan Nikel (Ni) Beberapa Merek Braket Stainless Steel Dalam Cairan Saliva Artifisial	Siwy et al. (2015)²³ Jurnal e-GiGi	Determine the amount of chromium and nickel metal released from the stainless steel bracket in artificial saliva	Experimental laboratory with the type of pre-experimental research and research design nonequivalent control group design. Samples were tested using uv-vis spectrophotometry The sample consists of 4 kinds of bracket brands immersed in artificial saliva solution	Each sample has a chromium release of 0.025; 0.002; 0.008; 0.027 ppm and nickel 0.689; 1,012; 1,130; 1,176 ppm.
19	Metal Ion Release from New and Recycled Stainless Steel Brackets.	Huang et al. (2004)²⁴ European Journal of Orthodontics	The aim of this study was to compare the release of metal ions from new and recycled brackets immersed in buffers with different ph values over a 48 week period.	Stainless steel brackets are divided into two groups: new and recycled. The latter is coated with adhesive and the bracket is heat treated soaked in the test solution for 48 weeks. The ion release was analyzed by atomic absorption spectrophotometry.	the submerged Ormco metal bracket group produced the greatest nickel concentration of all metal bracket groups tested (260.5 ± 17.9 μg / ml)

DISCUSSION:

The nickel content in stainless steel has advantages and disadvantages. The most common drawback is an allergic reaction. The prevalence of nickel hypersensitivity has increased steadily, for male patients (38%) while more than 30% for women. However, nickel rarely causes allergic reactions in the oral cavity. Apart from nickel, the stainless-steel bracket also contains chromium. Chromium is an additional component in stainless steel orthodontic wire which serves to increase corrosion resistance²¹. Chromium on metal surfaces reacts with oxygen and forms chromium oxide to resist corrosion².

The corrosion rate is affected by the increase in ambient temperature. In every 10^o Celsius increase, the corrosion rate constant increases 2-50 times. The corrosion rate constant increases by 1.1-1.6 times at a reaction temperature of 600 degrees Celsius. The degree of acidity also affects the corrosion process because pH shows the concentration of H + ions in water and results in the release of electrons by the metal in anodic reactions. Saliva contains chloride elements which tend to prevent the formation of a protective oxide layer on the surface of the bracket, thereby accelerating corrosion²⁵.

The oral environment is ideal for metal biodegradation, so that corrosion and ionization can occur in orthodontic equipment. The release of nickel and chromium ions has potential carcinogenic, mutagenic and allergenic effects. This study evaluated the corrosion of titanium and cobalt-chromium alloys immersed in artificial saliva having a pH of 6.5 with and without fluoride over a period of 7, 9 and 11 weeks and with 2g/l NaF for 11 weeks at a temperature constant of 37°C under static conditions, and evaluates the superficial aspects in scanning electron microscopy and residual components, so that it can be used as an alternative to nickel hypersensitive patient stainless steel. Cobalt-chromium alloys showed the greatest corrosion rates, while pure titanium alloys and steel alloys with low nickel concentrations were the most corrosion resistant. The presence of fluoride causes a greater release in all tested alloys⁸.

Post-immersion measurements in artificial saliva for 30 days with a pH of 6.8 and a temperature of 37⁰C, showing that the release of chromium metal was less than that of nickel metal. This can be due to the composition of the stainless-steel bracket sample containing less chromium metal than nickel metal. Excessive release of chromium and nickel metals can cause changes in the dimensions of the bracket shape which results in the brittleness of the bracket and can affect body health because it is a heavy metal group that can cause type IV hypersensitivity reactions²³. Many parameters influence metal ions in the salivary environment, including pH level, oxygen content, temperature, and immersion duration¹⁹. The increased rate of metal ion release could be attributed to its corrosiveness and subsequently to chlorhexidine mouthwash. Chlorhexidine mouthwash releases more metal ions (except manganese) than Listerine and Colgate plax mouthwashes¹⁰. The galvanic corrosion on brackets manufactured by four different companies that were combined with stainless steel (SS) or nickel-titanium (nickel) wire in an artificial saliva solution. The rate and speed of galvanic corrosion also depends on the surface area ratio of the two different alloys in contact¹¹.

The cytotoxic effect of nickel ions released from stainless steel brackets was investigated. Allergic reactions can occur in those who are sensitive, even though the amount of nickel and chromium released from the orthodontic appliance is below the average dietary intake of nickel and chromium. Group comparisons indicated that very low cell counts were reported at a concentration of 1.18µg in comparison with other specimens. This contrasts with previous study stated. Mild DNA damage was observed in only 1.18µg of human gingiva exposed to fibroblast samples after 72 hours of treatment. This shows that a high concentration is capable of producing damage, because the tool will be at least in the mouth for 18 months¹². Nickel and chromium can corrode through a variety of mechanisms. Nickel may increase after 2 months, regardless of the type of bracket used, however the pattern of increase depends on the type of bracket. Despite the higher rate of increase in the conventional bracket, after 2 months the increase in nickel ion at different rates may not end up in a sizeable amount of difference. Overall, ionic changes were of little clinical significance¹³. During orthodontic treatment, the oral environment also affected the level of nickel and chromium ion release in stainless steel brackets. As a result, the orthodontic bracket released the most ions occurred in mouthwashes with chlorhexidine content. The peak rate of metal release from fixed orthodontic appliances occurred on day 7, and all releases were completed in 4 weeks with the daily amount of chromium and nickel intake in food being 5 to 100μg and 300 to 500μg, The nickel concentration in drinking water generally measures below 20μg per liter, and the average chromium content in drinking water is 0.43μg per liter.⁴ Proper oral hygiene can minimize corrosion rates. Artificial plaque fluid causes significantly higher levels of Ni and Cr release than artificial saliva. This finding is in accordance with the findings of other studies.¹⁴

In dentistry, one of the determining factors for biocompatibility is the alloy used and the resistance to corrosion. The austenitic stainless steel in the orthodontic bracket has a high stiffness and malleability metal containing chromium, carbon, and nickel. Chromium helps the brackets to be more resistant to corrosion by forming a passive coating on the surface metal, but this film can be damaged by the attack of aggressive ions such as fluoride and chloride. The same is true for the orthodontic nickel-type titanium metal bracket, which forms a passive titanium-oxide layer that provides protection against corrosion but makes this 1% lactate solution insufficient to reduce dissolution of metal ions¹⁷. Another important factor according to previous study in relation to metal corrosion is the salivary flow rate. The highest nickel was released in experiments with a pH of 4.2 from a recycled stainless-steel bracket and the least nickel in a pH of 6.5 and a pH of 7.6¹⁶. Metal shedding occurred for a minimum of 44 days and, in some cases, nearly 2 months. The nickel release rate from the bracket was constant for 58 days of investigation, most of the Ni release occurred during the first 9 days, then flattened and progressively increased, the Cr release was stable after 35days. The pH level affects the amount of nickel and chromium ions released. Hydrolysis of ester bonds causes the formation of free carboxylic acid groups which can reduce the pH in the polymer matrix. Hydrogen ions replace metal ions in the filler particles causing the release of metal ions from the filler. The increase in pH acidity causes the release of nickel ions which is more than the release of ions at normal pH, this will cause faster corrosion of the brackets immersed at acidic pH⁶. The highest nickel concentration was detected from the release of AISI 304 SS bracket ion after a 42-day immersion period (4.46± 0.68g), and the lowest nickel SS bracket release was (0.07±0.01). g/mL) after 63 days. Under micro-electron scanning, the surface of the SS bracket showed slight irregularity, which increased after saliva exposure. The stainless-steel bracket exhibits surface roughness indicating increased corrosion attack with increasing saliva exposure. In contrast, the low nickel bracket did not show changes in surface morphology with increased exposure to saliva, which indicates higher corrosion resistance¹⁸. The highest nickel release was recorded in 2 experiments conducted at pH 4.2; it is lower at pH 6.5 and 7.6. The effect of recycling depends on the reconditioning process, the type of bracket steel, whether the bracket is ground or cast, and the passive layer of the bracket. The effect of recycling on the physical properties of the bracket suggests that reconditioning can lead to decreased corrosion resistance. Metal bracket heat treatment can change the alloy surface protection. When steel is heated to high temperatures, chromium carbide deposits are formed which makes it susceptible to intragranular corrosion leading to general structural weakening. This is the reason, in general the recycled bracket releases a higher amount of ions than the new one⁹.

The recycled bracket releases more ions than the new bracket. A greater number of nickel, iron and manganese ions were released in artificial saliva than in other buffers tested. The ion release from the bracket in a pH 4 buffer was greater than that observed in a pH 7 or a pH 10 buffer.²⁶ An increase in nickel ions occurred in the first week to the 7th week with a final value of 1.333 ± 0.00667ppm. The increased release of metal ions can occur under dynamic conditions not only due to salivary fluidity and pH but also abrasion by toothbrushes and chewing mechanisms. The release of large amounts of metal ions after using an oral function simulator to describe the dynamic conditions of the oral environment.²¹ Brackets immersed in a pH 4 solution released more ions than those immersed in a pH 7 solution, and the total number of ions released increased over time over a 48-week period.²⁴In addition, as the pH of the solution increases, nickel release decreases. According to the literature the acidic conditions provide a reducing environment in which the oxide film of stainless steel, which is required for corrosion resistance, is less stable. It was also reported that changing the pH towards the acid value would result in up to 100 times more nickel release²³.

CONCLUSION:

Based on this review, the release of nickel and chromium ions in stainless steel orthodontic brackets has an optimum rate, at a certain pH and time. The amount of Cr and Ni ions released in the use of stainless steel brackets in saliva is influenced by the bracket raw material and the mixture of the saliva solution caused by the condition of the mouth and the artificial saliva mixture.

ACKNOWLEDGEMENT:

The authors especially grateful to Faculty of Dental Medicine, Airlangga Univesity for warm support, inspiration, and thoughtful guidance.

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

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Received on 06.05.2021 Modified on 25.10.2022

Research J. Pharm. and Tech 2023; 16(10):4935-4942.

DOI: 10.52711/0974-360X.2023.00800

MATERIAL AND METHODS

CONCLUSION:

REFERENCES: