Effect of chlorhexidine mouthwashes on periodontal parameters and extrinsic tooth staining in orthodontic patients.

INTRODUCTION: Periodontal health and biofilm control are primordial to success in orthodontic treatment. This study aimed to evaluate the effect of chlorhexidine (CHX) mouthwashes on periodontal status and extrinsic tooth staining in orthodontic patients. METHODS: Thirty-three patients of both sexes, aged 11-33 years, under orthodontic treatment with fixed appliances at <16 months, were randomly distributed into 2 groups. In the control group, patients received mechanical hygiene instruction, and in the experimental group, patients also used CHX wash twice a week for 60 days. The effectivity of the protocols was evaluated using the plaque, gingival, gingival bleeding, and discoloration indexes before the hygiene protocol was applied, 15, 30, and 60 days after protocol implementation. RESULTS: In the experimental group, there was a decrease in the plaque, gingival, and gingival bleeding indexes at the different evaluation periods (P <0.05). In addition, there was a significant difference in the discoloration index at 60 days compared with initial time points after implementing hygiene protocols in the experimental group (P <0.05). In contrast, there were no significant differences in plaque, gingival, gingival bleeding, and discoloration indexes in the control group at any time (P >0.05). CONCLUSIONS: CHX mouthwash administered 30 days, twice a week, significantly improved the periodontal status with mild brown staining. After this period, expressive extrinsic tooth staining was observed.

Transverse maxillary deficiency: treatment alternatives in face of early skeletal maturation.

Transverse deficiencies should be a priority in orthodontic treatment, and should be corrected as soon as diagnosed, to restore the correct transverse relationship between maxilla and mandible and, consequently, normal maxillary growth. Corrections may be performed at the skeletal level, by opening the midpalatal suture, or by dentoalveolar expansion. The choice of a treatment alternative depends on certain factors, such as age, sex, degree of maxillary hypoplasia and maturation of the midpalatal suture. Thus, the present study discusses different treatment approaches to correct maxillary hypoplasia in patients with advanced skeletal maturation.

Transverse maxillary deficiency: treatment alternatives in face of early skeletal maturation

ABSTRACT Transverse deficiencies should be a priority in orthodontic treatment, and should be corrected as soon as diagnosed, to restore the correct transverse relationship between maxilla and mandible and, consequently, normal maxillary growth. Corrections may be performed at the skeletal level, by opening the midpalatal suture, or by dentoalveolar expansion. The choice of a treatment alternative depends on certain factors, such as age, sex, degree of maxillary hypoplasia and maturation of the midpalatal suture. Thus, the present study discusses different treatment approaches to correct maxillary hypoplasia in patients with advanced skeletal maturation.

RESUMO Os problemas transversais devem ser priorizados no tratamento ortodôntico e corrigidos assim que diagnosticados, para restituir a correta relação transversal entre maxila e mandíbula e, consequentemente, restabelecer o crescimento maxilar normal. A correção pode ser realizada em nível esquelético, por meio da abertura da sutura palatina mediana (SPM), ou por expansão dentoalveolar. A opção de tratamento depende de alguns fatores como idade, sexo, grau de hipoplasia da maxila e a maturação da SPM. Assim, o objetivo do presente trabalho foi discutir as diferentes abordagens terapêuticas para correção da hipoplasia maxilar em pacientes com maturação esquelética avançada.

Quantification of pro-inflammatory cytokines and osteoclastogenesis markers in successful and failed orthodontic mini-implants.

OBJECTIVES: Miniscrew has been frequently used, considering that anchorage control is a critical point in orthodontic treatment, and its failure, the main adverse problem. Using two groups of stable (successful) and unstable (failed) mini-implants, this in vivo study aimed to quantify proinflammatory cytokines IL-1 α, IL-6, IL-17, and TNF-α and osteoclastogenesis marker RANK, RANKL, and OPG in gingival tissue, using the real-time polymerase chain reaction technique. METHODOLOGY: Thirteen patients of both sexes (11-49 years old) under orthodontic treatment were selected, obtaining 11 successful and 7 failed mini-implants. The mini-implants were placed and removed by the same surgeon, in both jaws. The mean time of permanence in the mouth was 29.4 months for successful and 7.6 months for failed mini-implants. At removal time, peri-mini-implant gingival tissue samples were collected and processed for quantification of the proinflammatory cytokines and osteoclastogenesis markers. Nonparametric Wilcoxon rank-sum test considering the clusters and Kruskal-Wallis test were used for statistical analysis (α=0.05). RESULTS: No significant difference (p>0.05) was observed between the groups for either quantification of cytokines or osteoclastogenesis markers, except for IL-6 (p<0.05). CONCLUSIONS: It may be concluded that the expression of IL-1α, IL-17, TNF-α, RANK, RANKL, and OPG in peri-implant gingival tissue were not determinant for mini-implant stability loss, but the higher IL-6 expression could be associated with mini-implant failure.

Microbial species associated with dental caries found in saliva and in situ after use of self-ligating and conventional brackets.

OBJECTIVES: Enamel demineralization is among the main topics of interest in the orthodontic field. Self-ligating brackets have been regarded as advantageous in this aspect. The aim of this study was to evaluate the break homeostasis in the oral environment and the levels of microorganisms associated with dental caries among the different types of brackets. MATERIAL AND METHODS: Twenty patients received two self-ligating brackets: In-Ovation®R, SmartClipTM, and one conventional GeminiTM. Saliva was collected before bonding (S0), 30 (S1) and 60 (S2) days after bonding. One sample of each bracket was removed at 30 and 60 days for the in situ analysis. Checkerboard DNA-DNA Hybridization was employed to evaluate the levels of microbial species as-sociated with dental caries. Data were evaluated by nonparametric Friedman and Wilcoxon tests at 5% significance level. RESULTS: The salivary levels of L. casei (p=0.033), S. sobrinus (p=0.011), and S. sanguinis (p=0.004) increased in S1. The in situ analyses showed alteration in S. mutans (p=0.047), whose highest levels were observed to the In-Ovation®R. CONCLUSIONS: The orthodontic appliances break the salivary homeostasis of microorganisms involved in dental caries. The contamination pattern was different between self-ligating and conventional brackets. The In-Ovation®R presented worse performance considering the levels of cariogenic bacterial species.

Quantification of pro-inflammatory cytokines and osteoclastogenesis markers in successful and failed orthodontic mini-implants

Abstract Objectives: Miniscrew has been frequently used, considering that anchorage control is a critical point in orthodontic treatment, and its failure, the main adverse problem. Using two groups of stable (successful) and unstable (failed) mini-implants, this in vivo study aimed to quantify proinflammatory cytokines IL-1 α, IL-6, IL-17, and TNF-α and osteoclastogenesis marker RANK, RANKL, and OPG in gingival tissue, using the real-time polymerase chain reaction technique. Methodology: Thirteen patients of both sexes (11-49 years old) under orthodontic treatment were selected, obtaining 11 successful and 7 failed mini-implants. The mini-implants were placed and removed by the same surgeon, in both jaws. The mean time of permanence in the mouth was 29.4 months for successful and 7.6 months for failed mini-implants. At removal time, peri-mini-implant gingival tissue samples were collected and processed for quantification of the proinflammatory cytokines and osteoclastogenesis markers. Nonparametric Wilcoxon rank-sum test considering the clusters and Kruskal-Wallis test were used for statistical analysis (α=0.05). Results: No significant difference (p>0.05) was observed between the groups for either quantification of cytokines or osteoclastogenesis markers, except for IL-6 (p<0.05). Conclusions: It may be concluded that the expression of IL-1α, IL-17, TNF-α, RANK, RANKL, and OPG in peri-implant gingival tissue were not determinant for mini-implant stability loss, but the higher IL-6 expression could be associated with mini-implant failure.

Microbial species associated with dental caries found in saliva and in situ after use of self-ligating and conventional brackets

Abstract Objectives Enamel demineralization is among the main topics of interest in the orthodontic field. Self-ligating brackets have been regarded as advantageous in this aspect. The aim of this study was to evaluate the break homeostasis in the oral environment and the levels of microorganisms associated with dental caries among the different types of brackets. Material and Methods Twenty patients received two self-ligating brackets: In-Ovation®R, SmartClipTM, and one conventional GeminiTM. Saliva was collected before bonding (S0), 30 (S1) and 60 (S2) days after bonding. One sample of each bracket was removed at 30 and 60 days for the in situ analysis. Checkerboard DNA-DNA Hybridization was employed to evaluate the levels of microbial species as-sociated with dental caries. Data were evaluated by nonparametric Friedman and Wilcoxon tests at 5% significance level. Results The salivary levels of L. casei (p=0.033), S. sobrinus (p=0.011), and S. sanguinis (p=0.004) increased in S1. The in situ analyses showed alteration in S. mutans (p=0.047), whose highest levels were observed to the In-Ovation®R. Conclusions The orthodontic appliances break the salivary homeostasis of microorganisms involved in dental caries. The contamination pattern was different between self-ligating and conventional brackets. The In-Ovation®R presented worse performance considering the levels of cariogenic bacterial species.

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.

Cytokine profile changes in gingival crevicular fluid after placement different brackets types.

OBJECTIVE: The aim of this study was to examine the relationship between bracket design and ratio of five proinflammatory cytokine, in gingival crevicular fluid (GCF), and bacterial adhesion without tooth movement influence. DESIGN: The sample was comprised of 20 participants, aged 11 to 15 years old (mean age: 13.3 years±1.03). A conventional Gemini™ metallic bracket and two self-ligating brackets, In-Ovation®R and SmartClip™, were bonded to the maxillary incisors and canines. GCF was collected using a standard filter paper strip before and 60days after bonding. The cytokine levels (IL-12, IL-1α, IL-1ß, IL-6 and TNF-α) were performed by the LUMINEX assay. The levels of the red and orange bacterial complexes were analyzed by the Checkerboard DNA-DNA hybridization. The data of cytokine and bacterial complexes were carried out using the non-parametric tests at 5% of significance level. RESULTS: Increased cytokine levels were observed. However, only the SmartClip™ group showed a significantly increased level of TNF-α (p=0.046). The SmartClip™ brackets group presented higher levels of red complex bacteria. CONCLUSIONS: The bracket design affected cytokine levels and bacterial adhesion since it was observed that the proinflammatory cytokines released in GCF to the SmartClip™ group showed an increase in the TNF-α levels associated with higher bacterial levels, which possibly represents greater inflammatory potential. Thereby, the bracket design should be considered in patients with risk of periodontal disease and root resorption.

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

Abstract 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.

Influence of resin-modified glass ionomer and topical fluoride on levels of Streptococcus mutans in saliva and biofilm adjacent to metallic brackets.

Decalcification of enamel during fixed orthodontic appliance treatment remains a problem. White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. The use of fluoride-containing orthodontic materials has shown inconclusive results on their ability to reduce decalcification. The aims of this investigation were to compare the levels of Streptococcus mutans (SM) in saliva and biofilm adjacent to orthodontic brackets retained with a resin-modified glass ionomer cement (RMGIC) (Fuji ORTHO LC) and a light cured composite resin (Transbond XT), and to analyze the influence of topical application of the 1.23% acidulated phosphate fluoride (APF) on SM counts. In a parallel study design, two groups (n=14/15) were used with random allocation and high salivary SM counts before treatment. Biofilm was collected from areas adjacent to the brackets on teeth 13, 22, 33, and 41. Both saliva and biofilm were collected on the 7th, 21st, 35th, and 49th days after appliance placement. Topical fluoride application was carried out on the 35th day. Bonding with RMGIC did not alter SM counts in saliva or biofilm adjacent to the brackets. On the other hand, the biofilm adjacent to brackets retained with composite resin showed a significant increase in SM counts along the trial period. Topical application of 1.23% APF did not reduce salivary or biofilm SM counts regardless of the bonding material. In conclusion, fluoride topical application did not show efficacy in reducing SM. The use of RMGIC as bonding materials allowed a better control of SM cfu counts in dental biofilm hindering the significant increase of these microorganisms along the trial period, which was observed in the biofilm adjacent to the composite material.

Influence of resin-modified glass ionomer and topical fluoride on levels of Streptococcus mutans in saliva and biofilm adjacent to metallic brackets

Abstract Decalcification of enamel during fixed orthodontic appliance treatment remains a problem. White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. The use of fluoride-containing orthodontic materials has shown inconclusive results on their ability to reduce decalcification. The aims of this investigation were to compare the levels of Streptococcus mutans (SM) in saliva and biofilm adjacent to orthodontic brackets retained with a resin-modified glass ionomer cement (RMGIC) (Fuji ORTHO LC) and a light cured composite resin (Transbond XT), and to analyze the influence of topical application of the 1.23% acidulated phosphate fluoride (APF) on SM counts. In a parallel study design, two groups (n=14/15) were used with random allocation and high salivary SM counts before treatment. Biofilm was collected from areas adjacent to the brackets on teeth 13, 22, 33, and 41. Both saliva and biofilm were collected on the 7th, 21st, 35th, and 49th days after appliance placement. Topical fluoride application was carried out on the 35th day. Bonding with RMGIC did not alter SM counts in saliva or biofilm adjacent to the brackets. On the other hand, the biofilm adjacent to brackets retained with composite resin showed a significant increase in SM counts along the trial period. Topical application of 1.23% APF did not reduce salivary or biofilm SM counts regardless of the bonding material. In conclusion, fluoride topical application did not show efficacy in reducing SM. The use of RMGIC as bonding materials allowed a better control of SM cfu counts in dental biofilm hindering the significant increase of these microorganisms along the trial period, which was observed in the biofilm adjacent to the composite material.

Microbial complexes levels in conventional and self-ligating brackets.

OBJECTIVES: The aims were to evaluate the levels of bacterial species in saliva and in situ and to assess whether the design of brackets influences the risk of developing periodontal disease. MATERIALS AND METHODS: Twenty patients (13.3 mean age) were bonded with self-ligating brackets and a conventional bracket. Saliva was collected before bonding and 30 and 60 days after bonding. One sample of each bracket was removed 30 and 60 days after bonding. The analysis was determined by checkerboard DNA-DNA hybridization. The data was evaluated by the non-parametric test. RESULTS: A significant increase in the levels of bacterial species in the saliva occurred in 15 of the 22 analyzed species. The self-ligating brackets presented the highest incidence percentages for the orange and red complexes 60 days after bonding. In situ analyses showed different patterns according to the bracket design. The levels of Campylobacter rectus showed significant differences (p = 0.011) 60 days after bonding among the three brackets; the highest values were observed in the In-Ovation®R bracket. CONCLUSIONS: The bracket design seems to influence the levels of bacterial species involved in periodontal disease. Considering the wide variety of bacterial species, additional studies are needed to aid in the establishment of effective protocols to prevent the development of periodontal disease during orthodontic treatment. CLINICAL RELEVANCE: A dynamic alteration in the oral microbiota may lead to inflammatory reactions in the supporting soft and hard tissues. The different types of brackets interfere with bacterial adherence. Bracket design should be considered in orthodontic treatment.

Biofilm formation in Haas palatal expanders with and without use of an antimicrobial agent: an in situ study.

Orthodontic appliances causes specific alterations in oral environment, including reduction of pH, increase of dental biofilm and elevation of salivary microbial levels, causing an increased risk for dental caries. This study evaluated, using microbial culture and scanning electron microscopy (SEM), the in situ contamination by mutans streptococci (MS) of different surfaces of Haas palatal expanders with and without use of chlorhexidine gluconate mouthrinses (CHX). Thirty-four patients were randomly assigned to two groups (n = 17/group), using placebo (Group I) and 0.12% CHX (Group II-Periogard® ) mouthrinses twice a week. After 4 months, appliances were submitted to microbiological processing and after fragments were analyzed by SEM. Mann-Whitney U test (α = 5%) was used to assess differences between groups on the appliances' different surfaces and to compare the contamination on the free and nonfree surfaces of these components. There was no difference (p = 0.999) between groups regarding the number of MS colonies/biofilms on the nonfree surfaces, which showed intense contamination. However, free surfaces of Group II presented less contamination (p < 0.001) than those of Group I in all appliances' components. Results of the microbial culture were confirmed by SEM. Use of 0.12% CHX was effective in reducing the formation of MS colonies/biofilms on free surfaces of Haas expanders, in situ.

Bacterial biofilm on successful and failed orthodontic mini-implants--a scanning electron microscopy study.

Mini-implants have been extensively used in Orthodontics as temporary bone anchorage devices. However, early failure of mini-implants due to mobility might occur and the colonization of their surfaces by pathogenic bacteria has been referred to as one of the contributing factors. In this study, scanning electron microscopy (SEM) was used to assess the presence of microorganisms adhered to the surface of mini-implants that failed due to loss of stability. Twelve self-drilling titanium mini-implants (1.6 mm diameter × 9.0 mm long) were collected from 12 patients undergoing orthodontic treatment-7 successful and 5 failed mini-implants. The mean time of permanence in the mouth was 15.8 and 2.4 months for successful and failed mini-implants, respectively. The devices were placed in the maxilla and/or mandible and removed by the same surgeon and were processed for SEM analysis of the presence of microorganisms on their surfaces (head, transmucosal profile, and body). Extensive bacterial colonization on mini-implant head and transmucosal profile was observed in all successful and failed mini-implants. None of the failed mini-implants exhibited bacteria on its body and only one mini-implant belonging to the successful (stable) group exhibited bacteria on its body. The results did not suggest a relationship between failure and presence of bacterial colonies on mini-implant surfaces.

Molecular detection of Aggregatibacter actinomycetemcomitans on metallic brackets by the checkerboard DNA-DNA hybridization technique.

INTRODUCTION: The purpose of this randomized clinical study was to evaluate the presence of the periodontal pathogen Aggregatibacter actinomycetemcomitans on metallic brackets and the effectiveness of a 0.12% chlorhexidine digluconate mouthwash in inhibiting this microorganism. METHODS: The study involved 35 patients of both sexes having orthodontic treatment with fixed appliances between the ages of 14 and 22 years, randomized into 2 groups: experimental (n = 17) and control (n = 18). Two new metallic brackets were placed on the patients' premolars, and the subjects rinsed with a solution of 0.12% chlorhexidine digluconate or a placebo solution twice a week for 30 days. After that, the brackets were removed and underwent microbiologic analysis with the checkerboard DNA-DNA hybridization technique. Data were analyzed by using the Student t, Fisher exact, and Mann-Whitney tests at the significance level of 5%. RESULTS: The results showed that A actinomycetemcomitans was present in all brackets from the subjects in the control group vs 83% of the subjects who rinsed with chlorhexidine digluconate (P <0.0001). There were also significantly lower levels of this species in the chlorhexidine digluconate group compared with the control group (P = 0.0003). CONCLUSIONS: We concluded that 0.12% chlorhexidine digluconate rinsing, twice a week for 30 days during orthodontic treatment, is effective in reducing the presence and levels of A actinomycetemcomitans on metallic brackets.

Molecular detection of in-vivo microbial contamination of metallic orthodontic brackets by checkerboard DNA-DNA hybridization.

INTRODUCTION: Knowing the microbiota that colonizes orthodontic appliances is important for planning strategies and implementing specific preventive measures during treatment. The purpose of this clinical trial was to evaluate in vivo the contamination of metallic orthodontic brackets with 40 DNA probes for different bacterial species by using the checkerboard DNA-DNA hybridization (CDDH) technique. METHODS: Eighteen patients, 11 to 29 years of age having fixed orthodontic treatment, were enrolled in the study. Each subject had 2 new metallic brackets bonded to different premolars in a randomized manner. After 30 days, the brackets were removed and processed for analysis by CDDH. Data on bacterial contamination were analyzed descriptively and with the Kruskal-Wallis and Dunn post tests (α = 0.05). Forty microbial species (cariogenic microorganisms, bacteria of the purple, yellow, green, orange complexes, "red complex +Treponema socranskii," and the cluster of Actinomyces) were assessed. RESULTS: Most bacterial species were present in all subjects, except for Streptococcus constellatus, Campylobacter rectus, Tannerella forsythia, T socranskii, and Lactobacillus acidophillus (94.4%), Propionibacterium acnes I and Eubacterium nodatum (88.9%), and Treponema denticola (77.8%). Among the cariogenic microorganisms, Streptococcus mutans and Streptococcus sobrinus were found in larger numbers than L acidophillus and Lactobacillus casei (P <0.001). The periodontal pathogens of the orange complex were detected in larger numbers than those of the "red complex +T socranskii" (P <0.0001). Among the bacteria not associated with specific pathologies, Veillonella parvula (purple complex) was the most frequently detected strain (P <0.0001). The numbers of yellow and green complex bacteria and the cluster of Actinomyces were similar (P >0.05). CONCLUSIONS: Metallic brackets in use for 1 month were multi-colonized by several bacterial species, including cariogenic microorganisms and periodontal pathogens, reinforcing the need for meticulous oral hygiene and additional preventive measures to maintain oral health in orthodontic patients.

Gram-negative periodontal pathogens and bacterial endotoxin in metallic orthodontic brackets with or without an antimicrobial agent: an in-vivo study.

INTRODUCTION: High levels of periodontal pathogens can cause periodontal alterations. The presence of endotoxin might be responsible for the occurrence and progression of tissue inflammation and bone resorption. The aims of this study were to use checkerboard DNA-DNA hybridization and limulus amebocyte lysate assay to evaluate in metallic orthodontic brackets (1) the presence of 16 gram-negative periodontal pathogenic microorganisms of the orange complex and red complex +Treponema socranskii, (2) the amount of bacterial endotoxin, and (3) the efficacy of 0.12% chlorhexidine gluconate mouthwash in reducing bacterial contamination and endotoxin amount. METHODS: Thirty-three patients (ages, 11-33 years) under orthodontic treatment with fixed appliances had 3 new metallic brackets bonded to 3 different premolars. Sixteen patients used a 0.12% chlorhexidine gluconate mouthwash (Periogard, Colgate-Palmolive, São Bernardo do Campo, São Paulo, Brazil) (experimental group), and 17 patients used a placebo mouthwash (control group) twice a week. After 30 days, the brackets were removed, and the samples were obtained. The data were analyzed statistically by Mann-Whitney, Kruskal-Wallis, and Dunn tests (α = 0.05). RESULTS: The 0.12% chlorhexidine gluconate group accumulated significantly lower levels of microorganisms than did the placebo group (P = 0.01). When each microbial complex was analyzed separately, a statistically significant difference between the experimental and control groups was found for the orange complex (P = 0.04). A greater amount of bacterial endotoxin was detected in the 0.12% chlorhexidine gluconate group than in the control group (P = 0.02). CONCLUSIONS: The 0.12% chlorhexidine gluconate oral rinses can be useful to reduce the levels of gram-negative periodontal pathogenic microorganisms in patients with fixed orthodontic appliances. Considering the increased amount of bacterial endotoxin after chlorhexidine gluconate use, further research is necessary to develop clinical procedures or antimicrobial agents with action against bacterial endotoxin adhering to metallic brackets.

Corrosion in Haas expanders with and without use of an antimicrobial agent: an in situ study

OBJECTIVES: The purpose of this study was to evaluate in situ the occurrence of corrosion in the soldering point areas between the wire, silver brazing and band in Haas expanders. MATERIAL AND METHODS: Thirty-four 7-12-year-old patients who needed maxillary expansion with a Haas expander were randomly assigned to two groups of 17 individuals each, according to the oral hygiene protocol adopted during the orthodontic treatment: Group I (control), toothbrushing with a fluoride dentifrice and Group II (experimental), toothbrushing with the same dentifrice plus 0.12 percent chlorhexidine gluconate (Periogard®) mouthrinses twice a week. The appliances were removed after approximately 4 months. Fragments of the appliances containing a metallic band with a soldered wire were sectioned at random for examination by stereomicroscopy, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Data were analyzed statistically by Fisher's test at 5 percent significance level. RESULTS: The analysis by optical microscopy revealed areas with color change suggestive of corrosion in the soldering point areas joining the band and the wire in all specimens of both groups, with no statistically significant difference between the groups (p=1). The peaks of chemical elements (Ni, Fe, Cr, O, C and P) revealed by EDS were also similar in both groups. CONCLUSION: Color changes and peaks of chemical elements suggestive of corrosion were observed in the soldering point areas between the wire, silver brazing and band in both control and experimental groups, which indicate that the 0.12 percent chlorhexidine gluconate mouthrinses did not influence the occurrence of corrosion in situ.

Use of the checkerboard DNA-DNA hybridisation technique for in vivo detection of cariogenic microorganisms on metallic brackets, with or without use of an antimicrobial agent.

OBJECTIVE: Using checkerboard DNA-DNA hybridisation (CDDH) assay, this randomised clinical study evaluated the contamination of metallic brackets by four cariogenic bacterial strains (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei and Lactobacillus acidophilus) and the efficacy of 0.12% chlorhexidine gluconate (CHX) mouthwashes in reducing bacterial contamination. METHODS: Thirty-nine 11-33-year-old patients under treatment with fixed orthodontic appliances were enrolled in the study and had 2 new metallic brackets bonded to premolars. Nineteen patients used a 0.12% CHX mouthwash (Periogard) and 20 patients used a placebo mouthwash (control) twice a week. After 30 days, the brackets were removed and samples were obtained for analysis by CDDH. Data were analysed statistically by the Kruskal-Wallis test (α=0.05) using the SAS software. RESULTS: S. mutans, S. sobrinus, L. casei and L. acidophilus were detected in 100% of the samples from both groups. However, brackets of the control group were more heavily contaminated by S. mutans and S. sobrinus (P<0.01). In the experimental group, although all counts decreased after rinsing with the chlorhexidine solution, there was significant difference only for S. mutans (P=0.03). CONCLUSIONS: The use of 0.12% chlorhexidine gluconate mouthwashes can be useful in clinical practice to reduce the levels of cariogenic microorganisms in patients under treatment with fixed orthodontic appliances.