The effect of whitening toothpastes on polyurethane and silicone orthodontic clear ligatures: A clinical study.

BACKGROUND: This study aimed to verify the effects of bleaching toothpaste on colour stability, elastic properties, surface topography between aesthetic polyurethane and silicone elastomeric ligatures from different brands. METHODS: Elastomeric ligatures tested were: 1-Mini Single Case Ligature Stick (RMO-polyurethane); 2-Ligature "S" Shaped Dispenser (RMO-Silicone); 3-Sany-tie (GAC-translucent polyurethane); and 4-Sili-tie (GAC-translucent silicone). The ligatures were randomly assigned from the brackets of canines and lower incisors of 40 patients. The study had two phases of 30 days in which a different toothpaste was used, followed by a washout period of 30 days. After each phase, ligatures were submitted to colour checking, tensile strength, and SEM. RESULTS: The average of the ultimate tensile strength (m = 2.59; DP = 0.014) was higher in the control ligatures if compared to the tested ones (m = 2.24; DP = 0.014). There were no statistically significant differences between toothpastes regarding the type of ligature. Also, no interaction was observed between toothpastes in ligature's ultimate tensile strength and strain. The type of toothpaste did not minimize colour changes. CONCLUSION: In conclusion, there was no difference in colour stability and elastic properties between polyurethane or silicone aesthetic elastomeric modules. Whitening toothpastes had no impact on ligatures performance after 30 days in the oral cavity.

Evaluation of photobiomodulation therapy to accelerate bone formation in the mid palatal suture after rapid palatal expansion: a randomized clinical trial.

To evaluate the efficiency of photobiomodulation therapy (PBMT) in the midpalatal suture (MPS) and pain sensation in patients undergoing rapid palatal expansion (RPE). Thirty-four individuals with the diagnosis of skeletal maxillary hypoplasia were divided in two groups: laser (n = 18) and control (n = 16). Treatment plan consisted of the use of the Hyrax expander in all patients. Subjects in the laser group were irradiated with diode laser (980 nm, 0.3 W) in six spots bilaterally distributed along the MPS for 10 s during the active phase of treatment and after overcorrection (passive phase of RPE). Control group received sham irradiations with the laser in standby mode to characterize the placebo effect. Digital occlusal radiographs were performed at different time-points for bone formation evaluation in both groups. The effects of laser irradiation on pain were assessed by the visual analog scale (Wong-Baker Faces Pain Scale). Bone formation between groups was not significantly different (p = 0.2273). At 3 months, bone formation was not yet complete in both groups. Pain sensation was similar between groups (p = 0.3940). However, pain was significantly higher for the first 7 days of treatment compared with the 14th day. PBMT did not accelerate bone regeneration in the MPS and pain sensation was similar.

Periodontal ligament repair after active splinting of replanted dogs' teeth.

BACKGROUND/AIM: The high rate of root resorption resulting from tooth replantation represents a serious clinical problem. In order to prevent ankylosis and replacement resorption, the contemporary literature highlights the importance of using a flexible stabilization for traumatized teeth. For this purpose, orthodontic devices may be promising for obtaining a better prognosis and periodontal repair. The aim of this study was to evaluate the effect of an active splinting protocol with controlled force in dog's teeth following replantation. MATERIAL AND METHODS: Sixty premolar roots from three dogs were used. They were submitted to endodontic treatment, hemisected, atraumatically extracted and subsequently replanted. They were divided into four groups: Passive Stabilization (n = 20)-after 20 min in a dry medium; Active Stabilization (n = 20)-after 20 min in a dry medium; Negative control (n = 10)-immediate replantation and passive Stabilization; and Positive control (n = 10)-90 min of extra-alveolar time and passive Stabilization. The samples were collected and submitted to histologic processing. They were then evaluated for the count of inflammatory cells, expression of neurotrophin 4, osteoclasts, apoptotic cells and collagen fibres. The results were submitted to ANOVA or Kruskal-Wallis statistical tests followed by Tukey or Dunn post-tests (α = 5%). RESULTS: Passive Stabilization with orthodontic brackets without traction used after replantation had the highest number of inflammatory cells (p = .0122), osteoclasts (p = .0013) and percentage of collagen fibres in the periodontal ligament (p < .0001) when compared to Active Stabilization with orthodontic brackets applying amild tensile force. Neurotrophin 4 had no statistically significant difference (p = .05), regardless of the treatment. The apoptotic cells count revealed statistical differences (p < .0001) between Active Stabilization (189.70 ± 47.99) and Positive Control (198.90 ± 88.92) when compared to Passive Stabilization (21.19 ± 32.94). CONCLUSION: The active splinting protocol using orthodontic appliances generating a light and controlled force favoured periodontal ligament repair of replanted teeth.

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.

GHR and IGF2R genes may contribute to normal variations in craniofacial dimensions: Insights from an admixed population.

INTRODUCTION: This study aimed to determine whether single nucleotide polymorphisms in the growth hormone receptor (GHR) and insulin-like growth factor 2 receptor (IGF2R) genes are associated with different craniofacial phenotypes. METHODS: A total of 596 orthodontic and 98 orthognathic patients from 4 cities in Brazil were included for analyses. Angular and linear cephalometric measurements were obtained, and phenotype characterizations were performed. Genomic DNA was collected from buccal cells and single nucleotide polymorphisms in GHR (rs2910875, rs2973015, rs1509460) and IGF2R (rs2277071, rs6909681, rs6920141) were genotyped by polymerase chain reactions using TaqMan assay. Genotype-phenotype associations were assessed in the total sample (statistical significance was set at P <8.333 × 10-3) and by a meta-analytic approach implemented to calculate the single effect size measurement for the different cohorts. RESULTS: Rare homozygotes for the GHR rs2973015 showed increased measurements for the lower anterior facial height (ANS-Me) and mandibular sagittal lengths (Co-Gn and Go-Pg). In contrast, common homozygotes for the IGF2R rs6920141 presented reduced measurements for these dimensions (ANS-Me and Go-Pg). Furthermore, the less common homozygotes for IGF2R rs2277071 had reduced maxillary sagittal length (Ptm'-A'). The meta-analytical approach replicated the associations of rs2973015 with ANS-Me, rs2277071 with Ptm'-A', and rs6920141 with Go-Pg. CONCLUSIONS: Our results provide further evidence that GHR contributes to the determination of mandibular morphology. In addition, we report that IGF2R is a possible gene associated with variations in craniofacial dimensions. Applying meta-analytical approaches to genetic variation data originating from likely underpowered samples may provide additional insight regarding genotype and/or phenotype associations.

Genotoxic effects in oral mucosal cells caused by the use of orthodontic fixed appliances in patients after short and long periods of treatment.

OBJECTIVE: This study aimed to evaluate the genotoxic effects in the oral epithelial cells of patients undergoing fixed orthodontic treatment and to compare these to a control group without treatment. The null hypothesis to be tested is that corrective orthodontic treatment at different periods does not cause genotoxic effects in patients. MATERIAL AND METHODS: An observational cross-sectional study including 74 patients enrolled in corrective orthodontic treatment and 21 control patients, between 11 and 35 years of age, of both genders, participated in the research. Patients undergoing treatment were divided into four treatment groups differentiated by treatment periods: G1, n = 21 (1 month to 12 months); G2, n = 21 (13 to 24 months); G3, n = 23 (25 to 48 months); and G4, n = 9 (over 48 months). Cells were collected by scraping the internal side of the cheek and subsequently placed in tubes containing 0.9% sodium chloride solution. The sample underwent evaluation for genotoxic effects by means of the micronucleus test (MNT). Bivariate analyses were performed using parametric tests (t test or ANOVA) and nonparametric tests (Chi-square test, Kruskal-Wallis test, Dunn post-test). The adopted level of significance was 5%. RESULTS: Statistically significant differences for any of the genotoxic abnormalities (binucleated, trinucleated, karyolysis, piknosis, nuclear buds) were not found except for karyolysis, which was higher in the control group than in G4 (p < 0.05). CONCLUSIONS: This study did not demonstrate evidence of genotoxic effects even after long periods of corrective orthodontic treatment. CLINICAL RELEVANCE: This study explores genotoxic effects in fixed orthodontic patients.

Genetic polymorphism in RANK is associated with mandibular size.

OBJECTIVE: The aim of this study was to evaluate the association between genetic polymorphisms in RANK, RANKL and OPG with maxillary and mandibular dimensions in humans. DESIGN: DNA extracted from saliva and the rs3826620, rs9594738 and rs2073618 polymorphisms in RANK, RANKL and OPG, respectively, were analysed by real-time PCR. Four linear measurements (Co-Gn, GoPg, Co-Go and PTM-A) from lateral cephalograms were examined for the evaluation of craniofacial measurements. ANOVA testing and a multivariate linear regression analysis, adjusted for age and gender, were used for statistical analysis, with an alpha of 5%. Hardy-Weinberg equilibrium was also evaluated using the chi-square test within each polymorphism. SETTING: School of Dentistry of Ribeirão Preto, University of São Paulo. PARTICIPANTS: A total of 100 unrelated non-syndromic Brazilian Caucasian subjects were included in this study. RESULTS: The polymorphism in RANK was associated with a higher Go-Pg measurement (p = .039). In the multivariate analysis, adjusted for age and gender, the polymorphism in RANK was associated with Go-Pg (p = .017) and Co-Gn (p = .043). CONCLUSION: The polymorphism rs3826620 in RANK is associated with the mandibular size.

Traction of impacted canines in a skeletal Class III malocclusion: A challenging orthodontic treatment.

This case report describes the successful traction of 2 severely impacted canines. The patient, a 7-year-old girl, had good general health, nasal breathing, crossbite of the lateral incisors and canines, and a Class I molar relationship. The panoramic radiograph showed that the permanent canines were positioned above the roots of the lateral incisors, with the right canine in an accentuated inclination. The cephalometric analysis showed a skeletal Class III malocclusion with a predominance of horizontal growth. The Haas appliance associated with maxillary protraction was used during the first stage of treatment for 14 months. The second stage included the extraction of the deciduous molars, distal movement of the permanent molars to create space, and traction of the canines, and was associated with complete orthodontic treatment. The patient showed good esthetic and functional results at the end of treatment, verified by the stability over a period of 8 years after retention.

Bisphenol A release from orthodontic adhesives measured in vitro and in vivo with gas chromatography.

INTRODUCTION: The objectives of this study were to quantify in vitro the Bisphenol A (BPA) release from 5 orthodontic composites and to assess in vivo the BPA level in patients' saliva and urine after bracket bonding with an orthodontic adhesive system. METHODS: For the in-vitro portion of this study, 5 orthodontic composites were evaluated: Eagle Spectrum (American Orthodontics, Sheboygan, Wis), Enlight (Ormco, Orange, Calif), Light Bond (Reliance Orthodontic Products, Itasca, Ill), Mono Lok II (Rocky Mountain Orthodontics, Denver, Colo), and Transbond XT (3M Unitek, Monrovia, Calif). Simulating intraoral conditions, the specimens were immersed in a water/ethanol solution, and the BPA (ng.g-1) liberation was measured after 30 minutes, 24 hours, 1 day, 1 week, and 1 month by the gas chromatography system coupled with mass spectrometry. Twenty patients indicated for fixed orthodontic treatment participated in the in-vivo study. Saliva samples were collected before bracket bonding and then 30 minutes, 24 hours, 1 day, 1 week, and 1 month after bonding the brackets. Urine samples were collected before bonding and then at 1 day, 1 week, and 1 month after bonding. The results were analyzed statistically using analysis of variance and Tukey posttest, with a significance level of 5%. RESULTS: All composites evaluated in vitro released small amounts of BPA. Enlight composite showed the greatest release, at 1 month. Regarding the in-vivo study, the mean BPA level in saliva increased significantly only at 30 minutes after bonding in comparison with measurements recorded before bonding. CONCLUSIONS: All orthodontic composites released BPA in vitro. Enlight and Light Bond had, respectively, the highest and lowest BPA releases in vitro. The in-vivo experiment showed that bracket bonding with the Transbond XT orthodontic adhesive system resulted in increased BPA levels in saliva and urine. The levels were significant but still lower than the reference dose for daily ingestion.

Aesthetic and functional outcomes using a multiloop edgewise archwire for camouflage orthodontic treatment of a severe Class III open bite malocclusion.

Occasionally, orthodontists will be challenged to treat malocclusions and skeletal disharmonies, which by their complexity one might think that the only treatment alternative is the surgical-orthodontic approach. A male patient, aged 17 years old, was diagnosed with a skeletal Class III malocclusion, anterior open bite and negative overjet. An unpleasant profile was the patient's 'chief complaint' showing interest in facial aesthetics improvement. Nevertheless, the patient and his parents strongly preferred a non-surgical treatment approach. He was treated with a multiloop edgewise archwire to facilitate uprighting and distal en-masse movement of lower teeth, correct the Class III open bite malocclusion, change the inclination of the occlusal plane and obtain the consequent morphological-functional adaptation of the mandible. The Class III malocclusion was corrected and satisfactory changes in the patient's profile were obtained. Active treatment was completed in 2 years, and facial result remained stable at 2 years 6 months after debonding.

CO2 laser as auxiliary in the debonding of ceramic brackets.

This study evaluated the temperature in the bonding composite and in the pulp chamber, the shear bond strength after the irradiation of CO2 lasers, and the Adhesive Remnant Index (ARI) after debonding of ceramic bracket. A hundred and five premolars were used: 30 to evaluate the temperature and 75 to test the resistance to shear and the ARI. To assess the temperature, different irradiation times (3 and 5 s), pulse duration (0.001 and 0.003 s), and output power (5, 8, and 10 W) were tested (total of 12 groups). During all the irradiation, specimens were immersed in thermal bath water at 37 °C. In the test and ARI evaluation, premolars were divided into five groups (n = 15) and were submitted to the following regimens of CO2 laser irradiation: I (5 W, pulse duration = 0.01 s, application time = 3 s), II (5 W, 0.03 s, 3 s), III (8 W, 0.01 s, 3 s), and IV (1 0 W, 0.01 s, 3 s). Group C (control) was not subjected to irradiation. ARI was measured after debonding of the bracket. Following irradiation of the lasers, the pulpal temperature was not higher than 5.5 °C in four of the study groups. Results were submitted to the ANOVA and Duncan's test. CO2 laser irradiation regimen IV was one in which the strength of debonding is 7.33 MPa. Therefore, CO2 laser may aid removal of ceramic brackets; it decreased the bond strength without increasing the excessive temperature excessively.

Physical and adhesive properties of dental enamel after radiotherapy and bonding of metal and ceramic brackets.

INTRODUCTION: The increasing success rates for cancer patients treated with radiotherapy and the frequent occurrence of tooth loss during treatment have led to an increased demand for orthodontic treatment after radiotherapy. The aim of this study was to evaluate tooth enamel of irradiated teeth after the bonding and debonding of metal and ceramic brackets. METHODS: Ten permanent molars were cut into enamel fragments measuring 1 mm(2) and divided into an irradiated group (total dose of 60 Gy) and a nonirradiated group. The fragments were subjected to microshear testing to evaluate whether radiotherapy altered the strength of the enamel. Furthermore, 90 prepared premolars were divided into 6 groups and subgroups (n = 15): group 1, nonirradiated and nonaged; group 2, nonirradiated and aged (thermal cycled); group 3, irradiated and aged; each group was divided into 2 subgroups: metallic and ceramic brackets. After thermal cycling and radiotherapy, the brackets were bonded onto the specimens with Transbond XT (3M Unitek, Monrovia, Calif). After 24 hours, the specimens were subjected to the shear tests. Images of the enamel surfaces were classified using the adhesive remnant index. The composite resin-enamel interface was also evaluated. RESULTS: Enamel fragments subjected to radiation had lower strength than did the nonirradiated samples (P <0.05). The groups and subgroups submitted to radiation and bonded ceramic brackets had the lowest strength values. Groups 1 and 2 with metallic brackets had less adhesive on the surface, whereas groups 1 and 2 with ceramic brackets and group 3 with both metallic and ceramic brackets had more adhesive on the surfaces. On the images of the composite resin-enamel interface, resin tags were more extensive on irradiated tooth enamel. CONCLUSIONS: Radiation decreased tooth enamel strength, and the specimens treated with radiotherapy had higher frequencies of adhesive failure between the bracket and the composite resin as well as more extensive tags.

Microbial contamination profile on esthetic elastomeric ligatures through the checkerboard DNA-DNA hybridization technique : A randomized split-mouth study.

OBJECTIVE: The aim of this study is to assess the microbial contamination of three different brands of esthetic elastomeric ligatures. MATERIALS AND METHODS: Different brands of esthetic ligatures (Unistick Pearl [American Orthodontics, Sheboygan, WI, USA], Power Sticks Pearl [Ortho Technology, Tampa, FL, USA], and Ease [Obscure, 3M Unitek, Monrovia, CA, USA]) were randomly assigned to permanent canines of 25 patients (aged 11-18 years) undergoing corrective orthodontic treatment. After 30 days, the ligatures were removed, processed, and the biofilm composition was analyzed by checkerboard DNA-DNA hybridization for 40 bacterial species. The microbiological data were analyzed using a nonparametric mixed model. RESULTS: The ligatures presented intense microbial contamination after 30 days, but no statistically significant differences were observed among the three groups (p > 0.05). The levels of the evaluated individual species and proportions of the microbial complexes showed no statistically significant differences among the ligature groups (p > 0.05). CONCLUSIONS: Esthetic elastomeric ligatures became multicolonized by several bacterial species after 30 days of exposure to the oral cavity. However, no relevant differences were observed among the biofilm composition formed on the different ligature brands.

Mandibular and dental measurements for sex determination using machine learning.

The present study tested the combination of mandibular and dental dimensions for sex determination using machine learning. Lateral cephalograms and dental casts were used to obtain mandibular and mesio-distal permanent teeth dimensions, respectively. Univariate statistics was used for variables selection for the supervised machine learning model (alpha = 0.05). The following algorithms were trained: logistic regression, gradient boosting classifier, k-nearest neighbors, support vector machine, multilayer perceptron classifier, decision tree, and random forest classifier. A threefold cross-validation approach was adopted to validate each model. The areas under the curve (AUC) were computed, and ROC curves were constructed. Three mandibular-related measurements and eight dental size-related dimensions were used to train the machine learning models using data from 108 individuals. The mandibular ramus height and the lower first molar mesio-distal size exhibited the greatest predictive capability in most of the evaluated models. The accuracy of the models varied from 0.64 to 0.74 in the cross-validation stage, and from 0.58 to 0.79 when testing the data. The logistic regression model exhibited the highest performance (AUC = 0.84). Despite the limitations of this study, the results seem to show that the integration of mandibular and dental dimensions for sex prediction would be a promising approach, emphasizing the potential of machine learning techniques as valuable tools for this purpose.

Insertion torque, flexural strength and surface alterations of stainless steel and titanium alloy orthodontic mini-implants: an in vitro study.

OBJECTIVE: This study aimed to compare the insertion torque (IT), flexural strength (FS) and surface alterations between stainless steel (SS-MIs) and titanium alloy (Ti-MIs) orthodontic mini-implants. METHODS: Twenty-four MIs (2 x 10 mm; SS-MIs, n = 12; Ti-MIs, n = 12) were inserted on artificial bone blocks of 20 lb/ft3 (20 PCF) and 40 lb/ft3 (40 PCF) density. The maximum IT was recorded using a digital torque meter. FS was evaluated at 2, 3 and 4 mm-deflection. Surface topography and chemical composition of MIs were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). General linear and mixed models were used to assess the effect of the MI type, bone density and deflection on the evaluated outcomes. RESULTS: The IT of Ti-MIs was 1.1 Ncm greater than that obtained for the SS-MIs (p= 0.018). The IT for MIs inserted in 40 PCF test blocks was 5.4 Ncm greater than that for those inserted in 20 PCF test blocks (p < 0.001). SS-MIs inserted in higher density bone (40 PCF) had significantly higher flexural strength than the other groups, at 2 mm (98.7 ± 5.1 Ncm), 3 mm (112.0 ± 3.9 Ncm) and 4 mm (120.0 ± 3.4 Ncm) of deflection (p< 0.001). SEM evidenced fractures in the Ti-MIs. EDS revealed incorporation of 18% of C and 2.06% of O in the loaded SS-MIs, and 3.91% of C in the loaded Ti-MIs. CONCLUSIONS: Based on the findings of this in vitro study, it seems that SS-MIs offer sufficient stability and exhibit greater mechanical strength, compared to Ti-MIs when inserted into higher density bone.

Single Nucleotide Polymorphisms in RUNX2 and BMP2 contributes to different vertical facial profile.

The vertical facial profile is a crucial factor for facial harmony with significant implications for both aesthetic satisfaction and orthodontic treatment planning. However, the role of single nucleotide polymorphisms (SNPs) in the development of vertical facial proportions is still poorly understood. This study aimed to investigate the potential impact of some SNPs in genes associated with craniofacial bone development on the establishment of different vertical facial profiles. Vertical facial profiles were assessed by two senior orthodontists through pre-treatment digital lateral cephalograms. The vertical facial profile type was determined by recommended measurement according to the American Board of Orthodontics. Healthy orthodontic patients were divided into the following groups: "Normodivergent" (control group), "Hyperdivergent" and "Hypodivergent". Patients with a history of orthodontic or facial surgical intervention were excluded. Genomic DNA extracted from saliva samples was used for the genotyping of 7 SNPs in RUNX2, BMP2, BMP4 and SMAD6 genes using real-time polymerase chain reactions (PCR). The genotype distribution between groups was evaluated by uni- and multivariate analysis adjusted by age (alpha = 5%). A total of 272 patients were included, 158 (58.1%) were "Normodivergent", 68 (25.0%) were "Hyperdivergent", and 46 (16.9%) were "Hypodivergent". The SNPs rs1200425 (RUNX2) and rs1005464 (BMP2) were associated with a hyperdivergent vertical profile in uni- and multivariate analysis (p-value < 0.05). Synergistic effect was observed when evaluating both SNPs rs1200425- rs1005464 simultaneously (Prevalence Ratio = 4.0; 95% Confidence Interval = 1.2-13.4; p-value = 0.022). In conclusion, this study supports a link between genetic factors and the establishment of vertical facial profiles. SNPs in RUNX2 and BMP2 genes were identified as potential contributors to hyperdivergent facial profiles.

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.

Maxillary alveolar bone evaluation following dentoalveolar expansion with clear aligners in adults: A cone-beam computed tomography study.

Objective: To investigate the effects of maxillary orthodontic expansion on the alveolar bone tissue in adult patients treated with aligners by using cone-beam computed tomography. Methods: Thirty patients (22 females and 8 males; mean age: 36.3 years) were treated with Invisalign® aligners. Cone-beam computed tomography and digital models were obtained before (T0) and after (T1) upper arch expansion. The bone thicknesses in the cervical, middle, and apical areas of the incisors, canines, premolar, and first molars were buccally and palatally measured, totaling 96 areas and 2,880 measurements. The buccolingual inclinations and transverse measurements of the teeth were obtained from digital models to correlate them with the bone changes. The statistical tests used were Student's t-test, analysis of variance, and Pearson's correlation tests (p < 0.05). Results: From the 96 areas evaluated, 84 revealed an increase or stability in the alveolar bone thickness and twelve displayed significant bone loss. Bone changes did not correlate with the tooth inclination and transverse measurements. Conclusions: Within the limitation of the present study, mild levels of upper arch expansion obtained with Invisalign® aligners in adult patients did not result in any clinically significant loss of alveolar bone thickness.

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.