Endotoxin affinity for orthodontic brackets

Effect of Orthodontic Appliances on the Oral Environment and Microbiome

Orthodontic treatment is an appliance-intensive endeavor, where an array of mechanical devices is used to bring about tooth movement. By virtue of remaining in close proximity to the enamel, gingiva and periodontal ligament intra-orally over a prolonged period of time, orthodontic appliances have a significant impact on the paradental tissues, oral environment and oral microbiome. Orthodontic appliances by acting as anchors for biofilm and plaque formation, accumulate bacteria and other micro-organisms in amounts unfavorable for maintenance of healthy equilibrium. The resulting loss of balance in the oral microbiome causes dysbiosis which manifests clinically as increased enamel demineralization, dental caries and periodontal disease. Mechanical removal of the accumulated plaque by maintaining rigorous oral hygiene has been proven to be the single most important factor to mitigate the harmful effects of dysbiosis. This review investigates how each of the various components of the orthodontic appliances, different types of appliances and unique surface properties of biomaterials have contributory effects at the interface of orthodontic biomaterials and oral biology. The information thus obtained will be critical in instituting the best diagnostic and therapeutic measures at the clinical level. It will also be instrumental in devising improvements and providing new directions for future research in general and precision orthodontics in particular.

In vitro study of structural and mechanical properties of latex and non-latex intermaxillary orthodontic elastics

PURPOSE

We evaluated bacterial endotoxin adhesion, superficial micromorphology and mechanical properties of latex and non-latex intermaxillary orthodontic elastics.

METHODS

To quantify the adhered bacterial endotoxin, elastics were divided into 5 groups: experimental (n = 12) latex and non-latex elastics, previously contaminated by an endotoxin solution, negative control (n = 6) latex and non-latex elastics without contamination, and positive control (n = 6) stainless steel specimens (metallic replicas), contaminated by an endotoxin solution. In parallel, the structural micromorphology (n = 6) and surface roughness of latex and non-latex intermaxillary orthodontic elastics were assessed using confocal laser microscopy. Force degradation (g) and deformation of the internal diameter change (mm) were also evaluated. Structural micromorphology, surface roughness (µm), force degradation (g) and internal diameter (mm) change were evaluated at time 0 and after 24 and 72 h in a deformation test. Data were analyzed by the Shapiro-Wilk, Kruskal-Wallis, Dunn, ANOVA and Bonferroni tests (α = 5%).

RESULTS

Endotoxin adhered similarly to both types of elastics with scores of 3 (> 1.0 EU/mL). The surface microstructure of both types of elastics showed irregularities and porosities at all times. Initially, the latex elastics had a higher surface roughness (p < 0.001) than the non-latex ones. After 24 h loading, surface roughness of the latex elastics was significantly reduced (p < 0.001), while after 72 h, the values were similar for both types (p > 0.05). The non-latex elastics had significantly higher force generation values (p < 0.05) at 0, 24 and 72 h compared with the latex elastics, although there was a significant reduction (p < 0.001) in force over time for both elastics. Despite similar initial values, non-latex elastics had a significantly larger internal diameter (p < 0.001) after the loading periods of 24 and 72 h compared with the latex elastics.

CONCLUSION

Both elastics showed high affinity with endotoxin and microstructural irregularities of their surface. The non-latex elastics generated higher force values but demonstrated greater deformation of the internal diameter after loading.

Changes of Periodontal Tissues Because of Orthodontic Treatment: A Retrospective Study

Aim:

To evaluate the periodontal status before and after orthodontic treatment and to analyze the confounding factors associated with it.

Materials and Methods:

The present retrospective study analyzed pre- and posttreatment records of a total of 60 patients. Intraoral digital photographs before and after the orthodontic treatment were used to measure the following three periodontal variables: (a) width of the keratinized gingiva, (b) gingival recession, and (c) the status of interdental papilla. The ImageJ 46 software imaging program was used to perform the required measurements. The clinical data were then analyzed in an association with the participants’ demographic data, the type of orthodontic tooth movement, and other confounding factors. The data obtained were manually entered into the statistical package and analyzed using a significance level set at P < .05. Descriptive statistics, paired t-tests, and Pearson’s correlation analysis were used to identify differences among the studied variables.

Results:

Among the 60 patients, the majority (66.7%) were females. Most cases of the treated malocclusion were Class II, and most patients underwent intrusion and retrusion movements. The width of keratinized gingiva increased for most sites of upper teeth. In contrast, the lower teeth showed a mix of improvement and compromised width of keratinized gingiva. As a measure of gingival recession, the difference of clinical crown height revealed the tendency toward a reduced clinical crown height for most sites. Upper left lateral incisors and canines showed significant values with regard to keratinized gingival width measurements and tooth movements such as extrusion and intrusion movements. Likewise, with regard to the clinical crown height, upper right central incisors showed significant differences when correlated with the interincisal angle, lower incisors to the mandibular plane, and upper incisors to the NA line. The upper lateral incisors also showed significant correlations to certain cephalometric measurements.

Conclusions:

The orthodontic treatment was found to exert a significantly positive impact on the surrounding periodontium, particularly in the upper canine areas. Likewise, various types of tooth movement were found to positively affect the periodontium.

Esthetic elastomeric ligatures: Quantification of bacterial endotoxin in vitro and in vivo

INTRODUCTION

The objective of this study was to evaluate in vitro and in vivo bacterial endotoxin (LPS) adhesion in polyurethane and silicone esthetic elastomeric orthodontic ligatures. The null hypotheses tested were: (1) there is no LPS adhesion in esthetic elastomeric orthodontic ligatures; and (2) there is no difference in the LPS adhesion between different brands of these ligatures.

METHODS

For the in vitro study, 4 types of esthetic elastomeric ligatures were used (Sani-Ties and Sili-Ties [Dentsply GAC, Islandia, NY;] and Mini Single Case Ligature Stick and Synergy low-friction ligatures [Rocky Mountain Orthodontics, Denver, Colo]), contaminated or not with endotoxin solution. Replicas of twisted wire and cast stainless steel ligatures were used as control. For the in vivo study, 10 male and 10 female patients, aged 15-30 years, received the same 4 types of ligatures, 1 of each inserted in the maxillary and mandibular canines, randomly. Twenty-one days later, the ligatures were removed, and endotoxin quantification was performed using the Limulus amebocyte lysate test. Data were analyzed (α = 0.05) using the Kruskal-Wallis test and Dunn's posttest or analysis of variance and Tukey's posttest.

RESULTS

GAC silicone group had the lowest median contamination (1.15 endotoxin units/mL; P <0.0001) in vitro. In the in vivo study, the GAC silicone group had the lowest mean contamination (0.577 endotoxin units/mL; P <0.001). In both studies, the other groups did not present a significant difference when compared with each other (P >0.05).

CONCLUSIONS

LPS exhibited an affinity for all the tested polyurethane and silicone elastomeric ligatures. GAC silicone ligatures presented with lower amounts of LPS attached to their surfaces. Thus, both null hypotheses were rejected.

Comparison of microbial adhesion and biofilm formation on orthodontic wax materials; an in vitro study

Background/purpose

Orthodontic wax materials are available on the dental market and are given by orthodontists due to pain, sores and irritation caused by treatment. The aim of the study was to compare biofilm formation and microbial adhesion at different time points on different protective materials used against orthodontic wounds in vitro.

Materials and methods

Microbial adhesion and biofilm formation were evaluated against Streptococcus mutans ATCC 25175 and Lactobacillus acidophilus ATCC 4356 standard strains on orthodontic wax materials at the 0, 24th, 48th, 72nd, 96th and 120th hour. The Kruskal Wallis test and Bonferroni test were used for statistical evaluations. Statistical significance was set at p < 0.05.

Results

It was observed that S. mutans formed statistically significantly more biofilm on OrthoDots®CLEAR (OrVance) than Ora-Aid (TBM Corporation) at the 48th hour (p < 0.05). Furthermore, L. acidophilus formed statistically significantly more biofilm on OrthoDots®CLEAR (OrVance) than Brace Gard®(Infa-Lab Inc.) at the 72nd, 96th and 120th hours (p < 0.05).

Conclusion

Significant differences were noted among the different orthodontic wax materials and both S. mutans and L. acidophilus created biofilm on all waxes at different time points in vitro. To prevent biofilm formation, these waxes need to be refreshed and should not be used for more than 24 h. According to our study, biofilm production performances of pathogens on Brace Gard®(Infa-Lab Inc.) are minimal and therefore it may be a better option to use in clinics. However, to our knowledge, this is the first study investigating biofilm formation on waxes and more studies are needed in this field.

Microbial profile in different orthodontic appliances by checkerboard DNA-DNA hybridization: An in-vivo study

INTRODUCTION

The design of the orthodontic bracket or appliance is 1 of the most important factors for creating retentive areas for biofilm formation. In orthodontics, this would be the first study to compare the microbial level changes in 3 different types of orthodontic appliances using checkerboard DNA-DNA hybridization technique. The purpose of this study was to evaluate and compare the extent of appearance of orange and red microbial complexes in patients undergoing orthodontic treatment using aligners, conventional metallic fixed labial appliances, and lingual fixed appliances.

METHODS

A total of 60 patients, of which 20 patients were undergoing treatment with aligners, 20 patients with labial fixed appliances, and 20 patients with lingual fixed appliances, were included in our study. After 30 days, debonded brackets and rinsed aligners were stored and processed for analysis with checkerboard DNA-DNA hybridization.

RESULTS

Most bacterial species showed moderate counts, with the exception of Treponema denticola, which showed a higher count in all 3 types of appliances. Fusobacterium nucleatum, Porphyromonas gingivalis, and T denticola were present in a higher percentage in the lingual appliance. Fusobacterium periodontium and Prevotella intermedia were present in a higher percentage in the labial fixed appliance. Campylobacter rectus, Tannerella forsythia, and Prevotella melaninogenica counts were moderate in all 3 appliances, with the first 2 microbes showing slightly higher counts in aligners. The association between all the microorganisms were statistically insignificant, with the exception of F nucleatum, which showed a strong statistically significant association in all 3 types of appliances.

CONCLUSIONS

The microbial contamination in metallic brackets was higher than that of aligners, when used for a month. Lingual fixed appliances showed more microbial contamination than labial fixed appliances followed by aligners.

Polyphenols Inhibit Candida albicans and Streptococcus mutans Biofilm Formation

Background:Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) are two major contributors to dental caries. They have a symbiotic relationship, allowing them to create an enhanced biofilm. Our goal was to examine whether two natural polyphenols (Padma hepaten (PH) and a polyphenol extraction from green tea (PPFGT)) could inhibit the caries-inducing properties of S. mutans and C. albicans. Methods: Co-species biofilms of S. mutans and C. albicans were grown in the presence of PH and PPFGT. Biofilm formation was tested spectrophotometrically. Exopolysaccharides (EPS) secretion was quantified using confocal scanning laser microscopy. Biofilm development was also tested on orthodontic surfaces (Essix) to assess biofilm inhibition ability on such an orthodontic appliance. Results: PPFGT and PH dose-dependently inhibited biofilm formation without affecting the planktonic growth. We found a significant reduction in biofilm total biomass using 0.625 mg/mL PPFGT and 0.16 mg/mL PH. A concentration of 0.31 mg/mL PPFGT and 0.16 mg/mL PH inhibited the total cell growth by 54% and EPS secretion by 81%. A reduction in biofilm formation and EPS secretion was also observed on orthodontic PVC surfaces. Conclusions: The polyphenolic extractions PPFGT and PH have an inhibitory effect on S. mutans and C. albicans biofilm formation and EPS secretion.

Successful and failed mini-implants: microbiological evaluation and quantification of bacterial endotoxin

Objectives

Using two groups of mini-implants (successful and failed) the objectives of this in vivo study were: to evaluate the microbial contamination by the checkerboard DNA-DNA hybridization technique and to quantify the bacterial endotoxin by the limulus amebocyte lysate assay.

Material and Methods

The 15 successful and 10 failed mini-implants (1.6 mm diameter × 7.0 or 9.0 mm long), placed in the maxilla and/or mandible, were obtained from 15 patients undergoing orthodontic treatment. Data were analyzed statistically by the Wilcoxon rank-sum test using the SAS software (a=0.05).

Results

All 40 microbial species were detected in both groups of mini-implants, with different frequencies. No differences were observed between the groups with respect to microbial complexes (blue, purple, yellow, green, orange, red and other species) and endotoxin quantification (p>0.05).

Conclusion

Neither microbial contamination nor endotoxin quantification was determinant for the early loss of stability of the mini-implants.

Bacterial endotoxin adhesion to different types of orthodontic adhesives

Objective

The aim of this study was to assess whether LPS adheres to orthodontic adhesive systems, comparing two commercial brands.

Material and Methods

Forty specimens were fabricated from Transbond XT and Light Bond composite and bonding agent components (n=10/component), then contaminated by immersion in a bacterial endotoxin solution. Contaminated and non-contaminated acrylic resin samples were used as positive and negative control groups, respectively. LPS quantification was performed by the Limulus Amebocyte Lysate QCL-1000™ test. Data obtained were scored and subjected to the Chi-square test using a significance level of 5%.

Results

There was endotoxin adhesion to all materials (p<0.05). No statistically significant difference was found between composites/bonding agents and acrylic resin (p>0.05). There was no significant difference (p>0.05) among commercial brands. Affinity of endotoxin was significantly greater for the bonding agents (p=0.0025).

Conclusions

LPS adhered to both orthodontic adhesive systems. Regardless of the brand, the endotoxin had higher affinity for the bonding agents than for the composites. There is no previous study assessing the affinity of LPS for orthodontic adhesive systems. This study revealed that LPS adheres to orthodontic adhesive systems. Therefore, additional care is recommended to orthodontic applications of these materials.

Comparative three-dimensional analysis of initial biofilm formation on three orthodontic bracket materials

INTRODUCTION

The purpose of the present study was to investigate and compare early biofilm formation on biomaterials, which are being used in contemporary fixed orthodontic treatment.

METHODS

This study comprised 10 healthy volunteers (5 females and 5 males) with a mean age of 27.3 +-3.7 years. Three slabs of different orthodontic materials (stainless steel, gold and ceramic) were placed in randomized order on a splint in the mandibular molar region. Splints were inserted intraorally for 48 h. Then the slabs were removed from the splints and the biofilms were stained with a two color fluorescence assay for bacterial viability (LIVE/DEAD BacLight-Bacterial Viability Kit 7012, Invitrogen, Mount Waverley, Australia). The quantitative biofilm formation was analyzed by using confocal laser scanning microscopy (CLSM).

RESULTS

The biofilm coverage was 32.7 ± 37.7% on stainless steel surfaces, 59.5 ± 40.0% on gold surfaces and 56.8 ± 43.6% on ceramic surfaces. Statistical analysis showed significant differences in biofilm coverage between the tested materials (p=0.033). The Wilcoxon test demonstrated significantly lower biofilm coverage on steel compared to gold (p=0.011). Biofilm height on stainless steel surfaces was 4.0 ± 7.3 μm, on gold surfaces 6.0 ± 6.6 μm and on ceramic 6.5 ± 6.0 μm. The Friedman test revealed no significant differences between the tested materials (p=0.150). Pairwise comparison demonstrated significant differences between stainless steel and gold (p=0.047).

CONCLUSION

Our results indicate that initial biofilm formation seemed to be less on stainless steel surfaces compared with other traditional materials in a short-term observation. Future studies should examine whether there is a difference in long-term biofilm accumulation between stainless steel, gold and ceramic brackets.

Microstructural and mechanical characterization of contemporary lingual orthodontic brackets

OBJECTIVES

To investigate the composition and the microstructural and mechanical characterization of three different types of lingual brackets.

MATERIALS AND METHODS

Incognito™ (3M Unitek), In-Ovation L (DENTSPLY GAC) and STb™ (Light Lingual System, ORMCO) lingual brackets were studied under the scanning electron microscope employing backscattered electron imaging and their elemental composition was analysed by energy-dispersive X-ray microanalysis. Additionally, Vickers hardness was assessed using a universal hardness-testing machine, and the indentation modulus was measured according to instrumented indentation test. Two-way analysis of variance was conducted employing bracket type and location (base and wing) as discriminating variable. Significant differences among groups were allocated by post hoc Student-Newman-Keuls multiple comparison analysis at 95% level of significance.

RESULTS

Three different phases were identified for Incognito and In-Ovation L bracket based on mean atomic number contrast. On the contrary, STb did not show mean atomic contrast areas and thus it is recognized as a single phase. Incognito is a one-piece bracket with the same structure in wing and base regions. Incognito consists mainly of noble metals while In-Ovation L and STb show similar formulations of ferrous alloys in wing and base regions. No significant differences were found between ferrous brackets in hardness and modulus values, but there were significant differences between wing and base regions. Incognito illustrated intermediate values with significant differences from base and wing values of ferrous brackets.

CONCLUSIONS/IMPLICATIONS

Significant differences exist in microstructure, elemental composition, and mechanical properties among the brackets tested; these might have a series of clinical implications during mechanotherapy.

Co-regulation of LPS and tensile strain downregulating osteogenicity via c-fos expression

AIMS

Orthodontic forces are known to aggravate inflammation-induced destruction of the periodontium, but the underlying mechanism has not been elucidated. The present study investigates how inflammation and forces co-regulate periodontium damage.

MAIN METHODS

Cultures of MC3T3-E1 osteoblasts were pre-treated with conditioned medium from RAW264.7 macrophages exposed to 100ng/ml Porphyromonas gingivalis (Pg)-LPS. Conditioned medium was analyzed by ELISA for interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Osteoblasts were then subjected to tensile strain (0.5Hz; 1000μ or 3000μ) for 0min, 5min, 15min, 30min, 1h, 3h, and 6h. The cultures were analyzed for mRNA and protein levels of c-fos. Cells were also analyzed for alkaline phosphatase (ALP) activity.

KEY FINDINGS

(Pg)-LPS stimulated the secretion of all three cytokines from RAW264.7 cells in a dose- and time-dependent manner. Medium from (Pg)-LPS stimulated cells induced a 10-fold increase in c-fos expression, which decreased to a 4-fold plateau after 3h. In contrast, ALP activity of control osteoblasts decreased during the first 60min, then recovered over the next 4h. Pretreatment with conditioned medium generated the same initial decrease during tensile strain but prevented the recovery.

SIGNIFICANCE

Our study showed, for the first time, that the inhibitory effect of inflammation and tensile strain on osteogenicity is associated with the upregulation in c-fos expression. In addition, inflammation may reduce the ability of osteoblasts to restore their osteogenic capacity during sustained tensile stress and contribute to periodontium damage.

Long-term periodontal response to orthodontic treatment of palatally impacted maxillary canines

One of the most important aspects to take into consideration when evaluating the outcome of treatment of impacted maxillary canines is the final periodontal status. The aim of the present study was to evaluate the long-term periodontal response of palatally impacted maxillary canines aligned using a codified procedure and the 'Easy Cuspid' compared with contralateral spontaneously erupted teeth. The periodontal conditions of the adjacent teeth were also considered. From an initial sample of 124 patients, 33 patients (24 females and 9 males) were selected. All patients who had undergone surgical orthodontic treatment conducted in accordance with a standardized protocol were recalled for follow-up at an average of 4.6 years after the end of treatment. The average treatment time was 29 months and the mean eruption time of the previously impacted tooth was 3.1 months. The average probing depth values showed no significant clinical differences. Probing depths recorded at the vestibular surface of the lateral incisor (P < 0.05) and at the midpalatal/midlingual aspect of the first premolar were statistically significant in comparison with the control elements. Student's t-test was used to compare the test and control group values. Coefficient of reliability was set at P < 0.05. The use of a closed-flap surgical technique in association with a codified orthodontic traction system (Easy Cuspid) allowed alignment of palatally impacted canines without damage to the periodontium.

Adhesion of Porphyromonas gingivalis and Biofilm Formation on Different Types of Orthodontic Brackets

Objectives. To examine the interaction between Porphyromonas gingivalis and 3 different orthodontic brackets in vitro, focusing on the effect of an early salivary pellicle and other bacteria on the formation of biofilms. Material and Methods. Mono- and multi-species P. gingivalis biofilms were allowed to form in vitro, on 3 different bracket types (stainless steel, ceramic and plastic) with and without an early salivary pellicle. The brackets were anaerobically incubated for 3 days in Brain Heart Infusion Broth to form biofilms. Bacteria were quantified by trypsin treatment and enumeration of the total viable counts of bacteria recovered. Results. Saliva was found to significantly affect (P < 0.001) adhesion and biofilm formation of P. gingivalis, with higher numbers for the coated brackets. No significant effect was detected for the impact of the type of biofilm, although on stainless steel and plastic brackets there was a tendency for higher numbers of the pathogen in multi-species biofilms. Bracket material alone was not found to affect the number of bacteria. Conclusions. The salivary pellicle seems to facilitate the adhesion of P. gingivalis and biofilm formation on orthodontic brackets, while the material comprising the brackets does not significantly impact on the number of bacteria.

Comparative analysis of long-term biofilm formation on metal and ceramic brackets

OBJECTIVE

To test the null hypothesis that stainless steel and ceramic brackets show no differences in biofilm adhesion.

MATERIALS AND METHODS

Twenty adolescents (6 boys, 14 girls) who had received fixed orthodontic therapy for 18.9 ± 3.2 months were divided into a metal and a ceramic bracket group. Thirty brackets per group were taken from central incisors, canines, and second premolars and quantitatively analyzed for biofilm coverage with the Rutherford backscattering detection method. Five micrographs were obtained per bracket with views from the buccal, mesial, distal, gingival, and occlusal aspects, resulting in a total of 300 images. Biofilm formation between groups was compared using the Mann-Whitney U-test (α = .05).

RESULTS

Total biofilm formation was 12.5% ± 5.7% (3.3 ± 1.6 mm(2)) of the surface on metal and 5.6% ± 2.4% (1.5 ± 0.6 mm(2)) on ceramic brackets. Differences between groups were statistically significant (P < .05). A pairwise comparison of biofilm formation revealed significantly lower biofilm formation on ceramic brackets with respect to intraoral location (central incisor, canine, second premolar) and bracket surface (buccal, mesial, distal).

CONCLUSIONS

The hypothesis was rejected. The results indicate that ceramic brackets exhibit less long-term biofilm accumulation than metal brackets.

Influence of Different Orthodontic Brackets on Adherence of Microorganisms In Vitro

OBJECTIVE

To define the capacity of different bracket materials to modify the growth and adherence of microorganisms.

METHODS

Three types of brackets from the right upper central incisor were used: metallic, ceramic, and composite. Streptococcus mutans and Candida albicans were studied. The association of both species was also evaluated. The brackets were placed in flat-bottomed vials containing basal medium with 20% sucrose added; the flasks were inoculated with each of the microbial suspensions. The samples were incubated at 37 degrees C for 48 hours, after which the brackets were removed. The supernatant was removed from the flasks, the cells adhering to the glass were counted, and the brackets were studied with electron microscopy.

RESULTS

The adherence of Streptococcus mutans was not modified by the different brackets. The adherence of Candida albicans was increased by the composite bracket, whereas the use of metallic brackets decreased the number of colony-forming units (CFUs). By electron microscopy we demonstrated that the adherence of Streptococcus mutans plus Candida albicans together varied according to the bracket materials with composite > ceramic > metallic.

CONCLUSIONS

Orthodontic appliances serve as different impact zones and modify microbial adherence and colonization, acting as foreign reserves and possible sources of infection.

Effect of 0.4% stannous fluoride gel on Streptococci mutans in relation to elastomeric rings and steel ligatures in orthodontic patients

BACKGROUND

Patients with fixed orthodontic appliances often experience an absolute increase in the number of Streptococci mutans colony-forming units (cfu). The aim of this investigation was to study the development of biofilm and S. mutans cfu in connection with stainless steel ligatures and elastomeric rings in orthodontic patients treated with and without 0.4% stannous fluoride gel (SFG).

MATERIAL

Forty-seven patients were divided into 2 groups: those treated with 0.4% SFG for 4 minutes (experimental) and those without 0.4% SFG (control). In each patient, elastomeric rings were used for ligation on 1 side of the dental arch midline, and stainless steel ligatures were used on the opposite side. Saliva samples were collected before and after appliance placement. At 15 and 30 days after appliance placement, biofilm samples from the stainless steel ligatures and the elastomeric rings were collected and subjected to microbiologic procedures and scanning electron microscopy (SEM) analysis.

RESULTS

The numbers of S. mutans cfu in the saliva and biofilm were not statistically different between the teeth fitted with elastomeric rings and stainless steel ligatures, or between the experimental and control groups. SEM analysis showed biofilm formation on both ligature ties.

CONCLUSIONS

Topical application of 0.4% SFG in orthodontic patients with elastomeric rings or stainless steel ligatures does not cause a significant decrease in S. mutans cfu in the saliva and biofilm.