Effect of Different Ligature Ties on Microbial Flora and Periodontal Status in Orthodontic Patients

SL: Slide Ligature (Leone; Florence, Italy); TC: Teflon-Coated Ligatures; MOD: Elastomeric Modules; T0: Before Bonding; T1: One Week Bonding; T2: Five-Week Bonding

Fixed orthodontic appliances involve brackets, ligatures, and archwires that may predispose patients to increased plaque accumulation and gingival inflammation [1]. Among ligatures, stainless steel (SS) (Figure 1), elastomeric modules (MOD) (Figure 2), Teflon-coated ligatures (TC) (Figure 3), and slide ligatures (SL) (Figure 4) vary in plaque-retentive potential [2]. While MODs exert active force, SLs and TCs are designed for reduced friction and improved aesthetics. This study aims to compare the impact of these ligature types on periodontal indices and microbial colonization in orthodontic patients [3].

This randomized, single-blind clinical trial included 20 orthodontic patients aged 14–30 years. Patients were randomly assigned into four groups (n=5): MOD, SS, SL, and TC. Ethical clearance was obtained from SMBT University Ethics Committee (SMBT/DC/15/2014), and informed consent was taken. All participants had good oral hygiene and no systemic diseases.

 Figure 1. Stainless steel ligature wires

Figure 2. Elastomeric ligatures

Figure 3. Teflon coated stainless steel ligatures 

Figure 4. Slide Leone Ligature

Each patient received 0.014 NiTi archwire ligated with the assigned ligature type. Periodontal parameters—Plaque Index (PI), Gingival Index (GI), Pocket Depth (PD), and Bleeding Index (BI)—were recorded at baseline (T0), 1 week (T1), and 5 weeks (T2). Microbial samples were collected supra- and sub-gingivally and cultured on Brucella and blood agar under aerobic and anaerobic conditions. Bacteria analyzed included Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Eikenella corrodens.

Intragroup and intergroup comparisons were analyzed using Student’s t-test, ANOVA, and post hoc Bonferroni test. A p-value < 0.05 was considered significant using SPSS ver17.0.

This clinical study evaluated and compared the microbial colonization and periodontal outcomes of four orthodontic ligature types: Teflon-coated stainless steel (TC), Slide ligatures (SL), Stainless steel ligatures (SS), and Elastomeric modules (MOD), at three time intervals—T0 (baseline), T1 (1 week), and T2 (5 weeks).

This clinical study evaluated and compared the microbial colonization and periodontal outcomes of four orthodontic ligature types: Teflon-coated stainless steel (TC), Slide ligatures (SL), Stainless steel ligatures (SS), and Elastomeric modules (MOD), at three time intervals—T0 (baseline), T1 (1 week), and T2 (5 weeks).

1. Aerobic Bacterial Count

Intragroup comparisons

All four groups demonstrated statistically significant increases in aerobic bacterial counts from T0 to T1 and T1 to T2 (p < 0.001). This reflects a general trend of increasing microbial accumulation post-ligation.

Intergroup comparisons

• At T0, there was no significant difference among the four groups (p > 0.05), indicating similar baseline oral flora.
• At T1 and T2, statistically significant differences were observed between groups (p < 0.001), with TC showing the lowest aerobic counts and MOD the highest.

2. Anaerobic Bacterial Count

(Bacteria assessed: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Eikenella corrodens)

Intragroup comparisons

• All groups showed a significant increase in anaerobic counts over time.
• Notably, in the TC and SS groups, the increase between T0 and T2 was not statistically significant (p > 0.05), indicating a potential stabilization of microbial load.
• In contrast, SL and MOD groups demonstrated continued significant increases from T0 to T2 (p < 0.001).

Intergroup comparisons

• At T0, no significant differences were observed (p > 0.05).
• At T1 and T2, highly significant intergroup differences emerged (p < 0.001), with MOD showing the highest anaerobic counts, and TC the lowest.

3. Plaque Index Scores

Intragroup comparisons

• A significant increase in plaque index was noted from T0 to T1 and T0 to T2 in all groups (p < 0.001).
• However, from T1 to T2, there was no significant increase (p > 0.05), indicating that most plaque accumulation occurred during the first week post-ligation.

Intergroup comparisons

• Baseline (T0) values were comparable among groups (p > 0.05).
• At T1 and T2, significant differences were recorded (p < 0.001).

4. Gingival Index and Bleeding on Probing

Intragroup comparisons

• All groups showed increases in gingival index and bleeding scores over time, with MOD and SS groups experiencing the most pronounced changes (p < 0.001).
• The TC and SL groups showed more modest changes, and in some comparisons between T1 and T2, the differences were not statistically significant.

Intergroup comparisons

• At T0, gingival conditions were comparable.
• By T1 and T2, differences became statistically significant, with the TC ligatures showing the lowest gingival inflammation and bleeding, and MOD the highest.

5. Probing Pocket Depth (PPD)

Intragroup comparisons

• An increasing trend in PPD was observed in all groups over time.
• The increase was statistically significant in the MOD and SS groups (p < 0.001), suggesting progressive periodontal compromise.
• In contrast, TC and SL groups exhibited minimal changes, some of which were not statistically significant, indicating better preservation of periodontal health.

Intergroup comparisons

• Differences at T0 were non-significant.
• At T1 and T2, intergroup differences became significant (p < 0.001), with TC ligatures associated with the shallowest probing depths.

Primary dental care, especially for orthodontic patients, is essential to keeping healthy teeth^. It is well known that orthodontic equipment typically interferes with excellent oral hygiene, and the appliance's component can change the oral microflora by lowering pH, increasing bacterial affinities for metallic surfaces, and creating regions where germs might accumulate. According to the research, fixed orthodontic equipment increases plaque buildup, bacterial colonization, and enamel decalcification^. Although in the literature, there is no evidence of any previous study to compare the effect of Teflon-coated stainless steel ligatures, stainless steel ligature wires, slide ligatures and elastomeric ligatures on microbial flora and periodontal status simultaneously in orthodontic patients.

It is recommended to avoid using elastomeric ligature rings in patients with poor oral hygiene, as elastomeric rings absorb saliva and serve as sites for plaque accumulation, resulting in iatrogenic effects. Similar results were observed in our study [4]. Turkkahraman [5] evaluated microbial colonization in 20 patients. The donor location was determined to be the second upper premolar. Three separate time intervals were used to collect samples. They discovered no discernible difference in the levels of microbial contamination between the two materials.

These results were in contrast to our study results. Similar findings were discovered in our study when evaluated at various time intervals, supporting the findings of another study by Shruti, R. Varshney [6]. That the teeth ligated with elastomeric rings displayed a more significant number of aerobic as well as anaerobic microbes. This result follows the study of [4]. In research by [7]. Only aerobic and anaerobic bacteria were enumerated and expressed in colony-forming units. It was found that the counts of aerobic and anaerobic bacteria in the standard elastomeric and the Slide ligature groups did not vary substantially before treatment. Still, significant changes were seen in bacterial counts at different intervals.

A similar increase in bacterial counts with all four ligature materials in our study was observed at different intervals [8].evaluated the periodontal and microbiologic alterations using steel ligatures and elastomeric rings as orthodontic arch wire ligation techniques. According to their findings, elastomeric rings harmed gingivae and favoured periodontal infections. Our study showed similar results as statistically significant results suggested periodontal and microbiologic changes on comparison between Teflon-coated ligature, Stainless steel Ligature and elastomeric modules at different intervals. In contrast to the findings of our work, [9] used scanning electron microscopy to analyze bacterial plaque close to orthodontic brackets. The ligation material did not affect bacterial colonization. [10] Examined changes in microbial flora and periodontal health using standard and non-traditional elastomeric modules. According to their findings, the unconventional elastomeric modules were linked to higher plaque, bleeding, and bonded bracket plaque index scores and higher levels of microbial colonies.

Nevertheless, in our study, statistically significant differences between conventional and non-conventional elastomeric as well as Teflon-coated ligatures were evident in the plaque index scores, gingival bleeding index values, gingival index value, periodontal index value and microbial colonies at one week and five weeks interval with elastomeric modules being the site of maximum values as compare to Teflon coated ligature, stainless steel ligature & slide ligature [11]. Tested the metal self-ligating Damon (Ormco) and Speed (Speed, Canada) brackets, as well as the traditional Victory series (3M Unitek) and Microloc brackets (GAC). According to the author's findings, there was no statistically significant difference regarding bacterial counts between the metallic bracket groups of self-ligating brackets and traditional brackets.

This confirms research findings that metal surfaces are less susceptible to plaque build-up. In S. Pradeep's [12] study, teeth ligated with elastomeric rings contained higher amounts of aerobic and anaerobic microorganisms, and the difference was considered statistically significant, similar to [7] and our study.

Chandresh [13] studied 60 patients scheduled for orthodontic treatment. Plaque samples were collected to determine the colonization of S. mutans & candida after bracket placement, 2^nd & 3rd-month intervals of time. The study concluded that over time, the use of orthodontic equipment dramatically increases the colonization of S. mutants and Candida albicans in the oral cavity.

Orthodontics continues to evolve and introduce orthodontic materials with modified properties designed to control bacterial biofilms on surfaces effectively.

A newer version of an elastomeric ligature, a slide ligature (Leone; Florence, Italy), which the manufacturer claims reduce bacterial attachment, as compared with other ligation methods: stainless steel ligatures, Teflon-coated ligatures, and elastomeric modules. Effect on the periodontium. Our study reported a significant increase in bacteria in the biofilm around the elastomeric modules and slide ligatures.

Scientific research supporting its prudent usage of microbial colonization and its consequent impact on dental health is still anticipated. Regarding microbial adhesion, biofilm development, and these ligatures' subsequent propensity to degrade and develop periodontal diseases. To redesign traditional and modified elastomeric rings as orthodontic ligation accessories and determine their clinical usefulness, it is further necessary to investigate the microbial biofilm development on orthodontic ligatures based on their surface chemistries. To create effective orthodontic ligatures safe for oral health, it is also necessary to investigate and implement the necessary adjustments for impeding microbial biofilms on ligatures.

The study's main limitation is the small number of patients recruited.

• On comparing the effect of various ligatures concerning supragingival and subgingival microflora among all the ligature methods stainless steel ligation method showed minor plaque accumulation, followed by Teflon-coated ligature and slide ligatures. In contrast, the conventional elastomeric module is shown higher plaque accumulation.
• Slide ligatures, which affect periodontal health, oral hygiene, and standard elastomeric ligatures, are popular among non-traditional ligatures due to their benefits, including patient comfort and quicker treatment timeframes.

Ethics approval and consent to participate

This article does not contain any studies with human participants or animals performed by any of the authors. The patient gave her consent for publication of this case report and accompanying images.

Consent for publication

Not applicable.

Availability of data and materials

Under request to the Dr. Saurabh R. Nagar

Competing interest

The authors declare they have no competing interest.

Funding

The authors declare that they have not received funding. 

Acknowledgements

We would like to appreciate Dr. Ankit Patel (MDS, Conservative Dentistry & Endodontics) for his effort and help during this work.

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