Microbial adhesion on different types of orthodontic brackets and wires: An in vitro study

Abstract

Objective

The objective of this study was to compare the microbial adhesion of different oral pathogens on different wires used in orthodontic treatment and to evaluate the potential of these pathogens to form biofilms on different types of orthodontic wires and brackets.

Methods

In this in vitro investigation, we calculated that the sample size for each group (i.e., those with brackets [metal braces, ceramic braces, and self-ligating braces] and wires [nickel titanium, titanium molybdenum, and stainless steel]) should be 15 individuals. Five types of microbes (Streptococcus mutans, Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, and Candida albicans) were used. Three types of brackets and three types of wires were used with five types of bacteria, and the process was repeated three times to collect the average.

Results

No significant differences were observed in the mean concentrations of bacteria in the different brackets (p > 0.05) or in the mean concentrations in the different orthodontic materials used in these brackets. In contrast, there were considerable differences between the concentrations of bacteria in the wires and those in the brackets (p < 0.05).

Conclusion

Different wires and brackets have different associations with bacterial adhesion and concentration. The wires exhibited more substantial biofilm absorbance and concentrations than the brackets. The adhesion of biofilm may be a decisive factor when choosing a type of orthodontic wire, particularly for individuals at high risk of developing bacterial oral diseases, such as periodontal diseases and dental caries.

1. Introduction

Aesthetic brackets have become more common since improved orthodontic therapy was developed. This makes it necessary to address issues such as microbial adherence and biofilm growth. Traditional orthodontic patients were once considered to be at low risk, and orthodontic procedures were minimally invasive. According to Lucas, however, the use of separators during orthodontic treatment may increase the risk of bacteremia (Lucas et al., 2002). Blood samples from patients who have used these tools have exhibited both aerobic and anaerobic bacteria (Lee et al., 2001). In addition, Candida albicans (C. albicans) has frequently been implicated in fungal infections of the buccal mucosa, where it acts as a reservoir for the spread of infection (Şen et al., 1997). However, more research is needed to better understand this yeast’s pathogenicity and dispersion mechanisms (Traore et al., 2002). Streptococcus mutans (S. mutans), which has a well-established involvement in the etiology of caries ((Sansone et al., 1993), was investigated in the present study. Although C. albicans and S. mutans have been shown to survive on detachable orthopedic appliances, it is not known whether they can survive on fixed orthodontic appliances (Arendorf and Addy 1985).

Both cavity control and oral hygiene are essential for successful orthodontic treatment. Brackets and wires used in orthodontic appliances can accumulate plaque, and plaque in fixed appliances often contains S. mutans (Lee et al., 2011). Organic acids formed by mutans streptococci, including Streptococcus sobrinus and S. mutans, lead to enamel demineralization (Lee et al., 2009). The properties of biomaterials, especially their surface roughness and surface free energy (SFE), impact in vitro microbial attachment. In theory, rougher surfaces, which increase SFE and adhesion areas and prevent bacterial colonies from being dislodged, enhance bacterial attachment (Mei et al., 2011). Furthermore, the biofilm profiles of implants in orthodontic patients may be negatively affected, with simultaneous increases and decreases in microbial quality (Feres et al., 2021).

Different orthodontic appliances have different effects, inducing acidic pH, enhanced bacterial adhesion (S. mutans), and biofilm development. Brackets’ clinical qualities and physical characteristics differ widely, directly impacting plaque adhesion and causing gingivitis in certain cases. Salivary secretions, as well as tooth and gingiva surface characteristics, can affect the quality and quantity of biofilm formation. The porosity of the bracket material creates an ideal ecological niche for microbial adhesion and biofilm formation (do Nascimento et al., 2013). Oral hygiene may be more problematic to maintain in patients with aesthetic brackets because of greater microbial adherence (Rammohan et al., 2012).

We hypothesized that employing different biomaterials in tooth alignment would attract different oral pathogens, leading to bacterial adhesion and biofilm formation. Our objective was to identify the orthodontic wires and brackets with the least microbial adhesion and greatest effectiveness. We focused on comparing microbial adhesion across three bracket systems commonly employed in orthodontic treatment. We evaluated the bacterial adhesion on these orthodontic materials to determine the best type and quality of material to use for minimizing bacterial adhesion.

2. Materials and Methods

We conducted a lab-based experimental study over six months. Three different bracket systems (metal, ceramic, and self-ligating braces from Morelli®, Brazil), and three orthodontic wires (nickel titanium [NiTi], titanium molybdenum [Ti-mo], and stainless steel [SS] from Morelli®, Brazil) were used to study five microorganisms: Staphylococcus aureus (S. aureus), S. mutans, C. albicans, Escherichia coli (E. coli), and Enterococcus faecalis (E. faecalis).

To examine the efficacy of 3 types of brackets and wires in resisting 5 bacteria, 15 2-ml tubes and 15 small Petri dishes were prepared. Each tube and dish was filled with 1 ml of brain–heart infusion broth, and 3 samples of the same types of brackets and wires were placed in 5 tubes and 5 Petri dishes, respectively. Ten microliters of overnight microbial suspension were added to the appropriately labeled tubes and dishes. The tubes and dishes were then incubated at 37 °C for three days, with the cultures for S. mutans placed inside a candle jar before incubation. After incubation, the tubes and dishes were gently washed with saline to remove broth and nonadherent bacteria.

2.1. Testing for microbial Adhesion

Each bracket and wire was placed in a new tube and Petri dish, respectively, containing 1 ml of normal saline. Two-fold serial dilution was conducted for each sample. The Miles and Misra method was used to count bacteria. Squares were drawn on agar plates and labeled properly. We administered to each square a 10-μL drop of the appropriate dilution, which was left to spread spontaneously on the agar surface. The plates were incubated at 37⁰C for 1–2 days after being placed upright to dry. The S. mutans culture was placed in a candle jar before incubation. After incubation, each square was examined for growth, and the square with the most colonies was counted. The number of colony-forming units per milliliter (mL) was estimated by multiplying the average number of colonies by 100 and the dilution factor.

2.2. Testing for biofilm formation

The brackets and wires were incubated in new tubes and Petri dishes, respectively, containing 0.1 % crystal violet for half an hour, and they were then washed to remove excess stains. One ml of ethanol–acetone decolorizer was added to each for 15 min, and the tubes and dishes were vortexed for 1 min. At this point, 250 μL from each tube and dish was placed in a microtiter plate, and the absorbance was measured at 560 nm using an enzyme-linked immunosorbent assay machine.

2.3. Determination of sample size

Based on convenience sampling and our budget requirements, the sample size calculated for each group was 15 individuals (with brackets [n = 45] [metal, ceramic, and self-ligating] and wires [n = 45] [NiTi, Ti-mo, and SS]). Ninety samples for bacterial adhesion and 90 for biofilm formation (for a total of 180) were used. Three types of brackets and three types of wires were used with five types of bacteria, with the process repeated three times to determine the average value.

2.4. Data Analysis

SPSS version 26 was used to analyze the data. Descriptive and inferential statistics were used to describe the sample and to identify variations in bacteria and orthodontic material. Test statistics, p-values, and 95 % confidence intervals are provided, and the findings are displayed as frequencies and percentages, means and standard deviations, or both. Statistical significance is indicated by a p-value of 0.05 or less. Differences between the mean concentrations in the groups were detected using one-way analysis of variance (ANOVA), followed by a post-hoc test to compare each mean to every other mean.

3. Results

Beginning with the brackets, the highest bacterial concentration was found for C. albicans in the ceramic material (42,666). Similarly, E. coli exhibited a higher concentration in the ceramic group (4,778,666) than in the self-ligating and metal groups. Conversely, E. faecalis exhibited the highest concentration in metal (3,959,466), as did S. aureus (384,000). Finally, the highest concentration of S. mutans was found in the self-ligating brackets.

In terms of wires, the concentrations of C. albicans and E. faecalis were found to be higher in SS than in NiTi and Ti-mo (19,200 and 84,266, respectively). The concentrations of E. coli and S. aureus were higher in Ti-mo than in NiTi and SS (40,533 and 28,266, respectively). Surprisingly, S. mutans did not appear in Ti-mo and NiTi and was only found in SS, with a reading of 200 (Table 1).

Table 1.

Descriptive statistics of bacteria in wires and brackets.

Bacteria	BRACKETS			WIRES
	Self-ligating	Ceramic	Metal	SS	NiTi	Ti-mo
C. albicans	18,133	42,666	15,466	19,200	3,333	13,600
E. coli	512,000	4,778,666	110,933	6,666	3,466	40,533
E. faecalis	58,666	1,416,533	3,959,466	84,266	41,066	78,933
S. aureus	61,866	25,066	384,000	400	2,933	28,266
S. mutans	4,096,000	5,866	59,733	200	0	0

C.albicans (Candida albicans); E. faecalis (Enterococcus faecalis); E. coli (Escherichia coli); NiTi (nickel titanium); Ti-mo (Titanium molybdenum); SS (stainless steel); S. aureus (Staphylococcus aureus); S. mutans (streptococcus mutans)

Table 2 shows the rates of biofilm absorbance in the wires and brackets. The formula used to determine these levels was to subtract the bacterial readings from the constant (i.e., the “blank” state with no bacteria). Using this formula, the level of bacteria in Ti-mo was negative (by 0.109), while in NiTi and SS, the levels were negative by 0.119 and 0.097, respectively. The highest level was found in Ti-mo for S. aureus (0.185), and the lowest was found for S. mutans (−0.011). With the NiTi, the highest level was discovered in E. faecalis (0.004). Finally, S. mutans exhibited the highest level in SS.

Table 2.

Readings of biofilm absorbance in wires.

Bacteria		WIRES
		Ti-mo			NiTi					SS
Blank		0.109			0.119					0.097
C. albicans		0.140	0.031		0.092		−0.026			0.125			−0.028
E. coli		0.223	0.113		0.093		−0.025			0.094			0.003
E. faecalis		0.207	0.098		0.123		0.004			0.158			0.061
S. aureus		0.294	0.185		0.115		−0.003			0.122			0.025
S. mutans		0.097	−0.011		0.096		−0.022			0.279			0.182
Bacteria		BRACKETS
		Self-ligating				Ceramic						Metal
Blank		0.109				0.096						0.097
C. albicans		0.120	0.011			0.098		0.001				0.131			0.033
E. coli		0.122	0.013			0.096		0.0003				0.101			0.003
E. faecalis		0.14	0.030			0.106		0.010				0.094			−0.003
S. aureus		0.118	0.009			0.108		0.012				0.142			0.045
S. mutans		0.109	0.0003			0.093		−0.003				0.097			−0.0008
Descriptive statistics of readings of biofilm absorbance in both brackets and wires
			N	Range		Minimum			Maximum		Mean			Std. Deviation
	Ti-mo		5	0.197		−0.011			0.185		0.083			0.076
Wires	NiTi		5	0.030		−0.026			0.004		−0.014			0.014
	SS		5	0.185		−0.003			0.182		0.059			0.072
	Self-ligating		5	0.030		0.0003			0.030		0.012			0.011
Brackets	Ceramic		5	0.015		−0.003			0.012		0.004			0.006
	Metal		5	0.048		−0.003			0.045		0.015			0.022

C.albicans (Candida albicans); E. faecalis (Enterococcus faecalis); E. coli (Escherichia coli); NiTi (nickel titanium); Ti-mo (Titanium molybdenum); SS (stainless steel); S. aureus (Staphylococcus aureus); S. mutans (streptococcus mutans)

The levels of bacteria were negative in the self-ligating (0.109), ceramic (0.096), and metal materials (0.097). The highest levels in the self-ligating material were found for E. faecalis (0.030), and the lowest for S. mutans (0.0003). In the ceramic, the highest reading was found for S. aureus (0.012). Finally, S. aureus exhibited the highest level in the metal (0.045). A summary of the findings on biofilm absorbance in both the brackets and wires is shown in Table 2.

3.1. Bacterial counts in the brackets

The ANOVA results indicated no statistical differences in the mean concentrations of microorganisms (p < 0.05). Additionally, post-hoc analyses were used to determine the precise mean differences between the bacteria groups (Table 3). ANOVA was used to identify any significant differences between the groups in the mean concentrations in the brackets. For the brackets, we found only insignificant differences in the mean concentrations in the different orthodontic materials. Moreover, post-hoc analyses were used to determine the exact mean differences between the bacterial groups (Table 4).

Table 3.

Analysis of variance (ANOVA) result, descriptive statistics and Post-Hoc of bacteria in brackets.

ANOVA
	Sum of Squares		df		Mean Square				F		Sig.
Between groups	9358061.073		4		2339515.268				0.724		0.595
Within groups	32313377.025		10		3231337.703
Total	41671438.099		14
Descriptive statistics
	N	Mean	Std. Deviation	Std. Error			95 % Confidence Interval				Minimum		Maximum
							Lower Bound		Upper Bound
C. albicans	3	17.24	1.539	0.889			13.418		21.069		15.47		18.13
E. coli	3	1800.533	2586.923	1493.560			−4625.740		8226.806		110.93		4778.67
E. faecalis	3	1811.444	1980.322	1143.339			−3107.948		6730.836		58.33		3959.47
S. aureus	3	157.175	197.268	113.892			–332.866		647.217		25.66		384.00
S. mutans	3	1387.199	2346.044	1354.489			−4440.698		7215.097		5.87		4096.00
Total	15	1034.719	1725.262	445.460			79.300		1990.137		5.87		4778.67
Post-Hoc
(I) Bacteria1	(J) Bacteria1		Mean Difference (I-J)			Std. Error		Sig.		95 % Confidence Interval
										Lower Bound		Upper Bound
C. albicans	E. coli		−1783.289			1467.727		0.744		−6613.702		3047.124
	E. faecalis		−1794.200			1467.727		0.740		−6624.613		3036.213
	S. aureus		−139.931			1467.727		1.000		−4970.344		4690.481
	S. mutans		−1369.955			1467.727		0.878		−6200.368		3460.457
E. coli	C. albicans		1783.289			1467.727		0.744		−3047.124		6613.702
	E. faecalis		−10.911			1467.727		1.000		−4841.324		4819.502
	S. aureus		1643.357			1467.727		0.793		−3187.055		6473.770
	S. mutans		413.333			1467.727		0.998		−4417.079		5243.746
E. faecalis	C. albicans		1794.200			1467.727		0.740		−3036.213		6624.613
	E. coli		10.911			1467.727		1.000		−4819.502		4841.324
	S. aureus		1654.268			1467.727		0.789		−3176.144		6484.681
	S. mutans		424.244			1467.727		0.998		−4406.168		5254.657
S. aureus	C. albicans		139.931			1467.727		1.000		−4690.481		4970.344
	E. coli		−1643.357			1467.727		0.793		−6473.770		3187.055
	E. faecalis		−1654.268			1467.727		0.789		−6484.681		3176.144
	S. mutans		−1230.024			1467.727		0.913		−6060.437		3600.388
S. mutans	C. albicans		1369.955			1467.727		0.878		−3460.457		6200.368
	E. coli		−413.333			1467.727		0.998		−5243.746		4417.079
	E. faecalis		−424.244			1467.727		0.998		−5254.657		4406.168
	S. aureus		1230.024			1467.727		0.913		−3600.388		6060.437

C.albicans (Candida albicans); E. faecalis (Enterococcus faecalis); E. coli (Escherichia coli); S. aureus (Staphylococcus aureus); S. mutans (streptococcus mutans)

Table 4.

Analysis of variance (ANOVA) result, descriptive statistics and post-Hoc of orthodontics material of brackets.

ANOVA
			Sum of Squares			df	Mean Square				F		Sig.
Between groups			348978.044			2	174489.022				0.051		0.951
Within groups			41322460.054			12	3443538.338
Total			41671438.099			14
Descriptive statistics
	N		Mean		Std. Deviation	Std. Error	95 % Confidence Interval				Minimum		Maximum
							Lower Bound		Upper Bound
Self-ligating	5		949.266		1770.690	791.877	−1249.336		3147.869		18.133		4096.000
Ceramic	5		1248.971		2064.193	923.135	−1314.063		3812.006		5.866		4778.666
Metal	5		905.919		1713.000	766.077	−1221.051		3032.891		15.466		3959.466
Total	15		1034.719		1725.262	445.460	79.300		1990.137		5.866		4778.666
Post-Hoc
(I) Brackets		(J) Brackets		Mean Difference (I-J)		Std. Error		Sig.		95 % Confidence Interval
										Lower Bound		Upper Bound
Self-ligating		Ceramic		−299.705		1173.633		0.965		−3430.799		2831.388
		Metal		43.346		1173.633		0.999		−3087.747		3174.440
Ceramic		Self-ligating		299.705		1173.633		0.965		−2831.388		3430.799
		Metal		343.052		1173.633		0.954		−2788.041		3474.145
Metal		Self-ligating		−43.346		1173.633		0.999		−3174.440		3087.747
		Ceramic		−343.052		1173.633		0.954		−3474.145		2788.041

3.2. Bacterial counts in the wires

The bacterial concentrations in the wires were significantly different than those in the brackets (p < 0.05). The descriptive statistics for orthodontic material in the wires were as follows: SS (154.026 ± 152.719), NiTi (16.159 ± 16.159), and Ti-mo (32.266 ± 30.214). Post-hoc analyses were used to determine the exact mean differences between the wires. The mean difference between NiTi and SS was 137.866 (p < 0.05). The other wires, however, did not differ from one another by a statistically significant degree (Table 5).

Table 5.

Analysis of variance (ANOVA) result, descriptive statistics and post-Hoc of orthodontics material in wire.

ANOVA
	Sum of Squares		df			Mean Square						F			Sig.
Between groups	56820.302		2			28410.151						3.463			0.045
Within groups	98457.219		12			8204.768
Total	155277.521		14
Descriptive statistics
		N	Mean	Std. Deviation		Std. Error	95 % Confidence Interval						Minimum		Maximum
							Lower Bound		Upper Bound
SS		5	154.026	152.719		68.298	−35.600		343.652				19.200		400.000
Ni-Ti		5	16.159	19.445		8.696	−7.984		40.303				0.000		41.066
Ti-mo		5	32.266	30.214		13.512	−5.249		69.782				0.000		78.933
Total		15	67.484	105.315		27.192	9.162		125.805				0.000		400.000
Post-Hoc
(I) Bacteria Count		(J) Bacteria Count			Mean Difference (I-J)			Std. Error		Sig.	95 % Confidence Interval
											Lower Bound			Upper Bound
SS		Ni-Ti			137.866			57.287		0.039	−14.969			290.703
		Ti-mo			121.760			57.287		0.126	−31.076			274.596
Ni-Ti		SS			−137.866			57.287		0.039	−290.703			14.969
		Ti-mo			−16.106			57.287		0.958	−168.943			136.729
Ti-mo		SS			−121.760			57.287		0.126	−274.596			31.076
		Ni-Ti			16.106			57.287		0.958	−136.729			168.943

NiTi (nickel titanium); SS (stainless steel); Ti-mo (titanium molybdenum)

Similarly, ANOVA revealed significant differences in bacterial concentrations between the brackets and wires (p < 0.05). Post-hoc analysis was used to find the exact mean differences between the bacteria in the wires. A significant difference between E. coli and S. aureus was discovered (Table 6).

Table 6.

Analysis of variance (ANOVA) result, descriptive statistics and post-Hoc of bacteria in wires.

ANOVA
	Sum of Squares						df	Mean Square				F		Sig.
Between groups	26447.404						4	6611.851				0.513		0.028
Within groups	128830.117						10	12883.012
Total	155277.521						14
Descriptive statistics
	N		Mean	Std. Deviation		Std. Error	95 % Confidence Interval					Minimum		Maximum
							Lower Bound			Upper Bound
C. albicans	3		22.044	10.169		5.871	−3.217			47.306		13.600		33.333
E. coli	3		36.888	31.757		18.335	−42.001			115.777		3.466		66.666
E. faecalis	3		68.088	23.553		13.598	9.578			126.598		41.066		84.266
S. aureus	3		143.733	222.294		128.342	−408.478			695.944		2.933		400.000
S. mutans	3		66.666	115.470		66.666	−220.176			353.510		0.000		200.000
Total	15		67.484	105.315		27.192	9.162			125.805		0.000		400.000
Post-Hoc
(I) Bacteria1		(J) Bacteria1			Mean Difference (I-J)		Std. Error		Sig.		95 % Confidence Interval
											Lower Bound		Upper Bound
C. albicans		E. coli			−14.844		92.675		1.000		−319.845		290.157
		E. faecalis			−46.044		92.675		0.986		−351.045		258.957
		S. aureus			−121.688		92.675		0.690		−426.690		183.312
		S. mutans			−44.622		92.675		0.987		−349.623		260.379
E. coli		C. albicans			14.844		92.675		1.000		−290.157		319.845
		E. faecalis			−31.200		92.675		0.997		−336.201		273.801
		S. aureus			−106.844		92.675		0.046		−411.846		198.156
		S. mutans			−29.778		92.675		0.997		−334.779		275.223
E. faecalis		C. albicans			46.044		92.675		0.986		−258.957		351.045
		E. coli			31.200		92.675		0.997		−273.801		336.201
		S. aureus			−75.644		92.675		0.920		−380.646		229.356
		S. mutans			1.421		92.675		1.000		−303.579		306.423
S. aureus		C. albicans			121.688		92.675		0.690		−183.312		426.690
		E. coli			106.844		92.675		0.046		−198.156		411.846
		E. faecalis			75.644		92.675		0.920		−229.356		380.646
		S. mutans			77.066		92.675		0.915		−227.935		382.067
S. mutans		C. albicans			44.622		92.675		0.987		−260.379		349.623
		E. coli			29.778		92.675		0.997		−275.223		334.779
		E. faecalis			−1.421		92.675		1.000		−306.423		303.579
		S. aureus			−77.066		92.675		0.915		−382.067		227.935

4. Discussion

The purpose of this study was to evaluate the microbial adhesion of oral bacteria to different types of wires and brackets commonly used in orthodontics. Our findings revealed varying concentrations of bacteria depending on the materials used. Notably, S. mutans displayed the highest concentration in self-ligating brackets, while E. faecalis was most prevalent in SS wires. Wires and brackets can make it challenging to maintain good oral hygiene, increasing the risk of disease for users due to plaque buildup and microbial adhesion (Polke et al., 2021). Bacterial etiological agents, such as C. albicans, E. coli, E. faecalis, and S. aureus, can exacerbate periodontal disorders and demineralization in the oral microbiota, which are composed of various bacterial species (Cantekin et al., 2011).

A prior study found that S. mutans has the greatest ability to form biofilms and attach to orthodontic materials after orthodontic treatment, which can lead to enamel demineralization. This is due to the increase in the concentrations of S. mutans and L. acidophilus in the saliva (Bozkurt et al., 2020).

Compared to other microbes, E. coli had the highest concentration in, and adherence to, the ceramic brackets. A prior study compared the capacity for biofilm growth and the total bacterial counts of seven distinct types of brackets. E. coli demonstrated the strongest microbial adhesion (Gastel et al., 2009). Other scholars, however, did not observe a substantial difference between brackets made of various materials (Baboni et al., 2010). One study analyzed salivary film properties on raw orthodontic brackets using contact angle measurements. The results showed that ceramic brackets had higher adhesion than metal brackets, contrary to previous research (Saloom et al., 2013).

In the current investigation, quantitative measurements were used to assess the capacity of various aesthetic wires to preserve oral biofilms. Surface-related variations in Ti-mo, NiTi, and SS showed no differences (p > 0.05). SS significantly outperformed NiTi (p < 0.05). The formation of microbial biofilms is aided at the sites where the bacteria that are first to adhere are safe from removal pressures (Polke et al., 2021). Orthodontic wires offer a favorable environment for oral microbes to develop, leading to tooth disorders such as periodontal diseases and dental caries (Mirjalili et al., 2013). The most frequent problem arising from orthodontic treatment, biofilm accumulation, affects roughly 60 % of individuals (Bergamo et al., 2019). The uneven surfaces of orthodontic appliances constitute additional retaining sites (Ong et al., 2010) and may make it difficult to maintain good oral hygiene, leading to an increased bacterial load and favoring certain pathogenic species, such as S. Mutans (Lucchese et al., 2018). Additionally, brackets can compromise the physiological cleaning process carried out by the saliva, cheeks, and tongue (Moolya et al., 2014).

Our study identified biofilm formation on various types of wires and brackets, with differing levels of attachment. While differences in biofilm absorbance and concentration were observed between different wire types (p ≤ 0.05), no significant variations were noted in different bracket types. The wires exhibited the strongest biofilm attachment. In terms of bacterial concentration, S. aureus had the highest levels and C. albicans the lowest. These findings align with a prior study that explored six types of wires and assessed surface roughness and SFE using profilometry and dynamic contact angle analysis, respectively (Kim et al., 2014).

In contrast, S. mutans adhered substantially more to NiTi alloy wires than to SS wires. Thus, in terms of lowering S. mutans adherence, SS wires may be preferable to NiTi wires. It was previously discovered that coating metallic wires is effective at reducing S. mutans adherence, and that dental plaque accumulates significantly less on NiTi orthodontic wires coated with resin or epoxy than on bare NiTi wires (Raji et al., 2014). This is because the uncoated NiTi wires have greater surface energy and rougher surfaces than coated wires. The mean biofilm absorbance and concentration rates for each of the three sets of wires were compared using ANOVA. In every metric, there was a significant difference between the SS and NiTi wires.

These results corroborate those of a prior study that discovered that, during intraoral usage at all time intervals, the surface roughness of and biofilm adhesion to aesthetic-coated wires were enhanced, with positive links between the adhesion and surface roughness of C. albicans, S. mutans, and S. aureus. This prior study focused on three brands of aesthetically coated NiTi archwires (Taha et al., 2016). In our study, no significant differences were found in group three and those with the brackets (p > 0.05). These results concur with the prior finding that C. albicans in brackets had the weakest adhesion to E. faecalis and the strongest adhesion to ceramic and self-ligating coated brackets (Al-Lami and Al-Sheakli 2014).

The limitations of the present study include the limited sample size and the fact that biofilm production was only produced in a university lab, limiting the study’s ability to generalize its findings. Another drawback was that the assays used to measure the biofilms might not have been precise enough to measure the minute changes in biofilm formation seen on short bits of wire.

5. Conclusion

The concentrations of bacteria vary in different types of wires and brackets. While not significant in brackets, biofilm absorbance and concentrations were significant in the wires we studied. The orthodontic biomaterials in the wires displayed the highest affinity for, and concentration in, SS and NiTi. S. aureus exhibited the highest concentration, and C. albicans displayed the lowest concentration. When selecting an orthodontic wire, biofilm adherence may be a critical consideration. On this topic, more research with larger sample sizes and longer durations is needed.

CRediT authorship contribution statement

Huda Abutayyem: Conceptualization, Methodology. Mahra Abdullatif Alshehhi: Data curation, Writing – original draft. Maha Alameri: Visualization. Muhammad Sohail Zafar: Supervision, Writing – review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A. Supplementary data

The following are the Supplementary data to this article: