Pharyngeal airway subdivisions in 3-dimensional analysis: Differences between anterior and posterior anatomic boundaries.

INTRODUCTION: This study aimed to evaluate if there were differences between anterior and posterior anatomic boundaries used for the 3-dimensional determination of pharyngeal airway. METHODS: The sample included 150 cone-beam computed tomography scans from healthy patients divided according to (1) age: 6-11, 12-16, and ≥16 years; (2) sex: female and male; (3) anteroposterior skeletal pattern: Class I, II, and III; (4) vertical pattern: brachyfacial, mesofacial, and dolichofacial; and (5) craniocervical inclination (CCI): natural head posture, head flexion, and head extension. Anatomic regions were created to determine the correspondences between structures anteriorly and posteriorly to the pharyngeal airway. RESULTS: The location of the epiglottis, vallecula, hyoid, C2, and C3 were statistically different according to the CCI, and the location of vallecula, C3, and C4 were different according to sex. However, no statistically significant differences were observed between the frequencies of anterior and posterior anatomic region locations among age and different anteroposterior and vertical skeletal patterns. Posterior landmarks tend to be located below the anterior ones; consequently, the anatomic subregion they define will also be located below. CONCLUSIONS: Anterior and posterior structures and vertical and anteroposterior skeletal patterns may determine upper airway limits regardless of age. However, the studies must be paired according to sex, and CCI must be standardized.

Deformation of the circummaxillary sutures during acute micro-implant assisted rapid palatal expansion and tooth-supported expansion: An ex vivo study.

INTRODUCTION: This study aimed to assess and compare the deformation that develops in the circummaxillary sutures during activation of micro-implant assisted rapid palatal expander (MARPE) and tooth-supported expander (Hyrax) s, in the rapid maxillary expansion. SETTINGS AND SAMPLE: 7 pigs Sus Scrofa received custom-made MARPE (n = 3) and Hyrax (n = 4) appliances. MATERIAL AND METHODS: The devices were activated 25 times with strain readings captured by strain gauges attached to the following regions: posterior midpalatal suture (MPS), maxilla-premaxilla suture (MPM), maxilla-zygomatic suture (MZ) and maxilla pterygoid-process suture (MPP). The intermolar distance and suture width were measured immediately before activation and at the 20th and 25th activation. ANOVA and Kruskal-Wallis test was applied. RESULTS: The MARPE group presented greater MPS displacement in all measured regions, and one of the devices produced a significant opening (1.7 mm) in the posterior region. The accumulated tension in the MPS was higher compared to the other sutures (P < .05). A MARPE animal presented higher median tension in the MPS region (294.77µÎµ) compared to all other animals except one Hyrax animal (P < .05). Regarding the median tensions of the different activation intervals, the median tension measured during the 16th to 25th activation interval in the Hyrax group was lower than that measured during the first 8 activations, in both the MPS and MZ (P < .05). CONCLUSIONS: MARPE expanders developed more constant tensions during all activations (MPS and MZ), while Hyrax showed lower tension in the 16th to 25th activation.

Skeletal Stability and Airway Changes After Maxillary Advancement Using a Rigid External Distraction System in Non-Growing Cleft Patients.

ABSTRACT: Distraction osteogenesis (DO) is a highly effective technique for correction of severe maxillary hypoplasia, especially in patients with orofacial clefts and craniofacial syndromes. The purpose of this retrospective, longitudinal study was to assess long-term airway alterations after maxillary advancement using a rigid external distraction system (RED) in non growing cleft patients. Fifteen cleft patients (8 males and 7 females) aged from 14 to 25 years were included in this study. All of them were treated with a rigid external distraction system for maxillary advancement after a high Le Fort I osteotomy. To analyse airway changes lateral cephalograms were obteined before distraction (T0), immediately after distraction (T1) and 1 to 3 years and 3 months after distraction (T2). All the measurements were describled by means of median, minimum and maximum. In order to evaluate differences between each time interval, a Wilcoxon test associated to a Delta Cliff test was used to evaluate the effect size (level of significance adopted was 5%). A significant maxillary advancement and increased upper airway antero-posterior dimensions were observed after the distraction osteogeness process, as demonstrated by the difference between T1 and T0. No significant relapse at T2 was found. Lower airway and the airway at tip of uvula region did not display significant alterations. A significant maxillary advancement and increased antero-posterior upper airway dimension was measured immediately after maxillary distraction with rigid external distraction in non growing cleft patients. The findings were stable three years after distraction.

Is the buccal alveolar bone less affected by mini-implant assisted rapid palatal expansion than by conventional rapid palatal expansion?-A systematic review and meta-analysis.

OBJECTIVE: To systematically review the existing literature comparing mini-implant assisted rapid palatal expansion (MARPE) and conventional rapid palatal expansion (RPE) regarding the effect on the buccal alveolar bone thickness (BT) and marginal bone level (BL). METHODS: PubMed/MEDLINE, Scopus, Web of Science, The Cochrane Library, Virtual Health Library, Embase, Ovid, LIVIVO, CINAHL, the Portal de Periódicos da CAPES, Google Scholar and SIGLE were searched up to January 2020. Risk of bias (RoB) assessments were performed using the Cochrane Collaboration and ROBINS-I tools. Fixed-effects meta-analysis of standardized mean differences (SMD) was implemented to assess the pooled estimates for the BT outcome. The analyses were performed adopting a significance level of 5%. A narrative synthesis was performed to summarize the results on the BL. The GRADE tool was used to assess the quality of the evidence. RESULTS: Three randomized clinical trials and one retrospective study were included. Only one study was rated as with low RoB, while the others were scored as with moderate to serious RoB. Limited evidence indicated that patients using conventional RPE had a greater loss of the BT compared to patients using MARPE (SMD = 0.55; 95% CI: 0.29-0.80; P < .0001). Subgroup analyses showed that differences were significant in both premolars' regions, right (SMD = 0.75; 95% CI: 0.24-1.25; P = .004) and left (SMD = 1.05; 95% CI: 0.52-1.57; P < .0001), and these were not significant for the molars' regions (P > .05) (Low quality of evidence). LIMITATIONS: Limited amount of selected papers, methodological issues that could lead to bias and high clinical heterogeneity among the studies. Due to the statistical model applied for the quantitative synthesis of the results, no generalization to any other population is recommended. CONCLUSIONS: Limited evidence suggests that MARPE could decrease the loss of the buccal alveolar bone when compared to conventional RPE.

Influence of bone architecture on the primary stability of different mini-implant designs.

INTRODUCTION: Mechanical interlocking between a mini-implant (MI) and the bone substrate reflects directly on the primary stability achieved. The purposes of this study were to evaluate MI design performance in distinct bone substrates and correlate geometric characteristics with insertion site quality. METHODS: Two types of self-drilling MIs (1.6 × 8 mm) were allocated to 2 groups according to their geometric designs: Tomas system (Dentaurum, Ispringen, Germany) and Dual-Top (Rocky Mountain Orthodontics, Denver, Colo). Forty sections (8 × 10 mm) were taken from bovine pelvic ilium and pubic bone. Geometric design characteristics were evaluated using scanning electron microscope imaging and Image-Pro Insight software (Media Cybernetics, Rockville, Md). Bone quality parameters were assessed with a microcomputed tomography system, and primary stability was evaluated by insertion torque and pull-out strength. Intergroup comparisons were performed with analysis of variance and Tukey tests, and the Pearson correlation test was carried out (P <0.05). RESULTS: No significant difference was observed in the comparisons of the groups (Tomas: insertion torque, 12.87 N·cm; pull-out strength, 181 N; and Dual-Top: insertion torque, 9.95 N·cm; pull-out strength, 172.5 N) in the ilium. However, the Tomas group had a marked increase in insertion torque (25.08 N·cm; P <0.05) in the pubic bone. CONCLUSIONS: MI mechanical performance differed according to bone quality parameters, indicating that certain geometric parameters may be set depending on the insertion substrate.

Combined maxillary and mandibular distraction osteogenesis in patients with hemifacial microsomia.

INTRODUCTION: Hemifacial microsomia is a deformity of variable expressivity with unilateral hypoplasia of the mandible and the ear. In this study, we evaluated skeletal soft tissue changes after bimaxillary unilateral vertical distraction. METHODS: Eight patients (4 preadolescents 4 adolescents) each with a grade II mandibular deformity underwent a LeFort I osteotomy and an ipsilateral horizontal mandibular ramus osteotomy. A semiburied distraction device was placed over the ramus, and intermaxillary fixation was applied. Anteroposterior cephalometric and frontal photographic analyses were conducted before and after distraction. Statistics were used to analyze the preoperative and postoperative changes. RESULTS: Cephalometrically, the nasal floor and the occlusal and gonial plane angles decreased. The ratios of affected-unaffected ramus and gonial angle heights improved by 15% and 20%, respectively. The position of menton moved toward the midline. The photographic analysis showed a decrease of the nasal and commissure plane angles, and the chin moved to the unaffected side. The parallelism between the horizontal skeletal and soft tissue planes improved, with an increase in the affected side ramus height and correction of the chin point toward the midline. CONCLUSIONS: Simultaneous maxillary and mandibular distraction improved facial balance and symmetry. Patients in the permanent dentition with fixed orthodontic appliances and well-aligned dental arches responded well to this intervention.

Reliability of upper airway linear, area, and volumetric measurements in cone-beam computed tomography.

INTRODUCTION: Our objective was to assess the intraexaminer and interexaminer reliabilities of upper airway linear, area, and volumetric measurements in cone-beam computed tomography. METHODS: Cone-beam computed tomography scans of 12 subjects were randomly selected from a pool of 132 orthodontic patients. An undergraduate student, an orthodontist, and a dental radiologist independently made linear, area, and volumetric measurements. Linear anteroposterior and transversal measurements, cross-sectional area, sagittal area, minimum axial area, and volume measurements were made. The intraclass correlation coefficient (ICC) was used to assess intraexaminer and interexaminer reliabilities, and measurement errors were assessed. Agreement was further assessed with the Bland-Altman method and 95% limits of agreement. RESULTS: Overall, the ICC values indicated good reliability for the measurements assessed. The ICC values were greater than 0.9 (excellent) for 93% of intraexaminer and 73% of interexaminer assessments. Transversal width measurements and cross-sectional area at the level of the vallecula, however, had only moderate reliability (minimum ICC, 0.63), large 95% limits of agreement, and the greatest mean measurement errors (as high as 16% and 13% of the mean measurements, respectively). Linear anteroposterior measurements; cross-sectional areas at the levels of the palatal plane, soft palate, and tongue; and sagittal area and volume were reliable measurements, with a minimum ICC of 0.93 and more restricted limits of agreement. CONCLUSIONS: Based on these results, airway assessments by examiners with different backgrounds might have reliable anteroposterior linear measurements; cross-sectional areas at the levels of the palatal plane, soft palate, and tongue; and sagittal area and volume. The unreliable measurements were linear width, cross-sectional area at the level of the vallecula, and minimum axial area.

Assessment of exogenous pigmentation in colourless elastic ligatures.

INTRODUCTION: The aim of this study was to evaluate colour alteration of transparent elastic ligatures submitted to exogenous pigmentation. METHODS: Forty test specimens were divided into eight groups corresponding to one commercial brand with five test specimens in each group. The test specimens were immersed into coffee and black tea solutions with the purpose of assessing colour alteration using a portable digital spectrophotometer (Vita Easyshade Compact). The surfaces of the ligatures under scanning electron microscope (SEM) at ×30, ×150 and ×20,000 magnification were evaluated with the purpose of observing the differences in porosity of the ligatures. The Kolmogorov-Smirnov test for normality was applied followed by the one-way analysis of variance (one-way ANOVA) and the level of significance adopted was 95%. RESULTS: All the groups showed modified initial colour that was perceptible to the human eye. The brand that showed greater colour alteration, in comparison with its initial colour, was the American® pearl elastic ligature and the ligatures that presented the smallest colour variation were the Ortho-Organizer®. The surface evaluations of the ligatures showed differences with regard to the topography evidencing more porosity in the ligatures that showed greater staining. CONCLUSION: The group that changed colour significantly was the one that presented the highest porosity, and the brand that was the least altered was the one that showed the lowest porosity.

Laser versus ultrasound on bone density recuperation after distraction osteogenesis-a cone-beam computer tomographic analysis.

PURPOSE: To assess the effects of low-level laser versus ultrasound irradiation on bone mineral density after distraction osteogenesis using cone-beam computed tomographic analysis in an experimental study. MATERIALS AND METHODS: Distraction osteogenesis was performed with rapid maxillary expansion devices (Hyrax-Morelli, Sorocaba-São Paulo-Brazil). After a 2-day latency period, the distraction devices were activated for 10 days at a rate of 1 mm/day. Four groups of 6 animals were distributed as follows: 1) control, 2) laser irradiation on the right side, 3) ultrasound irradiation on the right side, and 4) laser irradiation on the right side and ultrasound on the left side. Cone-beam computed tomography was used to determine bone mineral density by measuring the recovery (percentage). Analysis of variance and the Tukey test (P = .05) were used for statistical analyses. RESULTS: The influences of low-intensity laser and ultrasound irradiation on bone mineral density were statistically significant. The analyses showed greater bone mineral density recuperation in the mandibular side with the ultrasound application. CONCLUSIONS: The results of this study suggest an acceleration of bone mineral density after laser and ultrasound irradiation. Ultrasound irradiation showed the greatest effects and the laser power positively influenced the recuperation of the bone density on the side opposite its application, causing a cross reaction or even exacerbating the inherent action of ultrasound irradiation.

Pharyngeal airway characterization in adolescents related to facial skeletal pattern: a preliminary study.

INTRODUCTION: The objective of this study was to characterize the volume and the morphology of the pharyngeal airway in adolescent subjects, relating them to their facial skeletal pattern. METHODS: Fifty-four subjects who had cone-beam computed tomography were divided into 3 groups-skeletal Class I, Class II, and Class III-according to their ANB angles. The volumes of the upper pharyngeal portion and nasopharynx, and the volume and morphology of the lower pharyngeal portion and its subdivisions (velopharynx, oropharynx, and hypopharynx) were assessed with software (version 11.5; Dolphin Imaging & Management Solutions, Chatsworth, Calif). The results were compared with the Kruskal-Wallis and the Dunn multiple comparison tests to identify intergroup differences. Correlations between variables assessed were tested by the Spearman correlation coefficient. Correlations between the logarithms of airway volumes and the ANB angle values were tested as continuous variables with linear regression, considering the sexes as subgroups. RESULTS: The minimum areas in the Class II group (112.9 ± 42.9, 126.9 ± 45.9, and 142.1 ± 83.5 mm(2)) were significantly smaller than in Class III group (186.62 ± 83.2, 234.5 ± 104.9, and 231.1 ± 111.4 mm(2)) for the lower pharyngeal portion, the velopharynx, and the oropharynx, respectively, and significantly smaller than the Class I group for the velopharynx (201.8 ± 94.7 mm(2)). The Class II group had a statistically significant different morphology than did the Class I and Class III groups in the velopharynx. There was a tendency to decreased airway volume with increased ANB angle in the lower pharyngeal portion, velopharynx, and oropharynx. In the upper pharyngeal portion, nasopharynx, and hypopharynx, there seemed to be no association between the airway volume and the skeletal pattern. CONCLUSIONS: The Class II subjects had smaller minimum and mean areas (lower pharyngeal portion, velopharynx, and oropharynx) than did the Class III group and significantly less uniform velopharynx morphology than did the Class I and Class III groups. A negative correlation was observed between the ANB value and airway volume in the lower pharyngeal portion and the velopharynx (both sexes) and in the oropharynx (just in male subjects).

Cross-section dimensions and mechanical properties of esthetic orthodontic coated archwires.

INTRODUCTION: There has been continuing interest in the development and use of esthetic and effective orthodontic archwires. The aims of this study were to evaluate the inner alloy core dimensions of 4 brands of as-received esthetic coated wires and their mechanical properties before and after 21 days of oral exposure, compared with conventional stainless steel and nickel titanium wires. METHODS: Four groups (Ortho Organizers, Carlsbad, Calif; TP Orthodontics, LaPorte, Ind; Orthometric, Beijing, China; and Trianeiro, Rio Claro, São Paulo, Brazil) of orthodontic archwires were tested. Five properties were evaluated: inner wire dimensions, modulus of elasticity, modulus of resilience, maximum deflection force, and load deflection curve characteristics. Images of the transverse sections from the specimens were made with a stereoscope. The inner alloy core dimensions of each wire were measured by using Image Pro Plus software (version 4.5; Media Cybernetics, Silver Spring, Md). All specimens were tested in a universal testing machine in a 3-point bending test. RESULTS: Coated wires of the Ortho Organizers and Trianeiro groups showed greater reductions in their inner alloy core dimensions and produced lower loading and unloading forces and lower modulus of elasticity, modulus of resilience, and maximum deflection force values than did their control wires. Inner alloy core dimensions and the mechanical behavior of coated wires practically did not differ from the control wires in the TP Orthodontics and Orthometric groups. CONCLUSIONS: The reduction on the inner alloy core dimensions to compensate for the coating thickness seems to be the variable responsible for greater changes in the mechanical properties of esthetic coated wires.

Impacted incisors associated with supernumerary teeth treated with a modified Haas appliance.

Tooth impaction involves factors such as lack of space in the alveolar process, trauma, ankylosis, and mechanical barriers such as abnormal frenum, supernumerary teeth, tumors, and local cysts. When impaction occurs in the anterior region, esthetics are compromised. This report describes the successful approach to treatment for a young boy who had 2 supernumerary teeth associated with impaction of the left central and lateral permanent incisors. Treatment consisted of extracting the supernumerary teeth and performing maxillary expansion with a modified Haas appliance to guide the left central incisor into its appropriate position. The teeth erupted spontaneously after maxillary expansion and an increase in space. A fixed edgewise appliance was placed incrementally to correct the maxillary anterior tooth positions and finish the treatment. Adequate esthetics and function were achieved.

Characteristics of patients seeking orthodontic retreatment.

BACKGROUND: The aim of this cross-sectional study was to investigate patients' experiences with previous orthodontic treatment for those seeking retreatment, and their expectations and motivation for doing so. METHODS: A total of 72 patients were invited to answer an anonymous questionnaire. Of these, 36 (13 men and 23 women, mean age 26.3 ± 5.8 years) were seeking retreatment (study group), and 36 (13 men and 23 women, mean age 25.5 ± 6.8 years) were seeking treatment for the first time (control group). Casts from both groups were assessed with the index of complexity, outcome, and need (ICON) score, to objectively determine the treatment need and complexity. Student`s t test for independent samples, and paired Student`s t test, were performed for comparisons between the retreatment and control groups, and between retreatment and previous treatment, respectively. RESULTS: There was no statistically significant difference between retreatment patients` motivation for the previous treatment and motivation for the retreatment. However, the mean visual analog scale (VAS) scores for motivation differed significantly between the retreatment and control groups (73.8 ± 23.9 and 87.5 ± 14.5, respectively). The mean ICON score of the retreatment group was lower than that for the control group (25 ± 14 and 31 ± 16, respectively). CONCLUSIONS: Patients seeking retreatment were less motivated for treatment, and tooth irregularity was the chief reason for seeking treatment in both groups. Although an objective treatment need was not observed in the 2 groups, all of them had some occlusal traits that clinically justified the orthodontic treatment.

Mini-implant assisted rapid palatal expansion (MARPE) effects on adult obstructive sleep apnea (OSA) and quality of life: a multi-center prospective controlled trial.

INTRODUCTION: Transverse maxillary deficiency is a high prevalent growth disorder within the adult population that may lead to serious health issues, such as detrimental malocclusions and higher risk of developing obstructive sleep apnea (OSA). Mini-implant assisted rapid palatal expansion (MARPE), as it expands the mid-face and augment the nasal and oral cavities dimensions, may reduce the airflow resistance and thus play an important role on OSA therapy in some patients. The main objective of the present trial is to assess MARPE effects on the sleep and quality of life of non-obese adult OSA patients with transverse maxillary deficiency. METHODS: A total of 32 participants were divided into intervention and control groups. They underwent physical evaluation, Epworth Sleepiness Scale (EES) and Quebec Sleep Questionnaire (QSQ), cone-beam computed tomography (CBCT) and home sleep testing (HST) for OSA before MARPE (T1) and 6 months after the intervention (T2). RESULTS: Questionnaires EES (daytime sleepiness) and QSQ (OSA-related quality of life) presented significant statistical differences between the groups. We also found clinical and statistical (p < 0.01) differences between the groups regarding the apnea/hypopnea index (AHI), as well as others HST parameters (mean oxygen saturation and snoring duration). CONCLUSION: In our sample, MARPE (without any auxiliary osteotomy) showed a good success rate (85%) and promoted important occlusal and respiratory benefits. We observed important daytime sleepiness and OSA-related quality of life improvement, as well as the AHI (65.3%), oxygen saturation and snoring duration.

Clinical parameters in soft tissue adjunctive periodontal procedures for orthodontic patients: surgical laser vs scalpel.

OBJECTIVES: To systematically review existing literature regarding clinical parameters comparing surgical laser and conventional surgery with scalpel for soft tissue adjunctive periodontal procedures in orthodontic patients. METHODS AND MATERIALS: MEDLINE, Scopus, Web of Science, The Cochrane Library, LILACS, Bibliografia Brasileira de Odontologia (Brazilian Dental Literature - BBO), Embase, Open Grey, Portal de Periódicos da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Coordination for the Improvement of Higher Education Personnel - CAPES), and Google Scholar were searched up to December 2020 without language restriction. Clinical trials comparing clinical parameters from surgical laser and conventional surgery with scalpel for soft tissue adjunctive periodontal procedures in orthodontic patients were selected. Risk of bias (RoB) assessments were performed using the Cochrane RoB2 tool. Narrative syntheses were performed, and the certainty of evidence was determined using the GRADE tool. RESULTS: Five randomized clinical trials were included. One study was rated as low RoB, whereas others presented some concerns or high RoB. The studies were highly heterogeneous in relation to the procedure performed, laser protocol, outcomes evaluated, and follow-up periods. In general, regardless of the procedure and laser protocol used, the studies did not show significant differences between laser and scalpel for the outcomes of probing pocket depth, clinical crown length, gingival index, and relapse rate. Pain and bleeding were significantly lower with the use of laser compared with the scalpel. The certainty of evidence ranged from moderate to very low. CONCLUSIONS: The existing literature on the subject is scarce and very heterogeneous and has methodological limitations. Based on the available evidence, it is not possible to draw definitive conclusions about the beneficial effect of laser use in orthodontic patients.

Effect of autoclaving on the fracture torque of mini-implants used for orthodontic anchorage.

OBJECTIVE: To evaluate the influence of autoclave sterilization on the fracture torque of five commercially available mini-implants used for orthodontic anchorage. DESIGN: In vitro laboratory study. MATERIALS AND METHODS: Ten mini-implants from each of five different manufacturers were submitted to one cycle of autoclave sterilization and tested, compared to their control groups - consisting of 10 as-received mini-implants each - to assess their fracture torque values. The mini-implants, connected to a digital torque gauge perpendicularly positioned to the bone surface, were inserted into swine femoral cortical bone segments until their fracture. OUTCOME MEASURES: Maximum torque values. STATISTICAL ANALYSIS: A two-way ANOVA to detect differences between implant products and the allocation group and one-way ANOVA with the Tukey's honestly significant difference (HSD) post hoc test among autoclaved groups and among control groups separately to detect differences between manufacturers. RESULTS: The effect of the autoclaving process was not significant (P = 0·411). The manufacturer factor, however, was significant (P < 0·001). The one-way ANOVA with the Tukey's HSD post hoc test results showed statistically significant differences between control groups. CONCLUSION: The autoclave sterilization of the mini-implants tested in this study did not affect their resistance to fracture; however, the mini-implants from different manufacturers presented with statistically significant differences in their resistance to fracture.

Does the exposure to cigarette smoke influence the colour stability and mechanical properties of different orthodontic elastic ligatures? - in vitro study.

OBJECTIVE: The aim of this study was to evaluate the colour stability and mechanical resistance of orthodontic elastic ligature exposed to cigarette smoke. METHODS: Four commercial brands were used: Aditek® (GA), Eurodonto® (GE), Morelli® (GM) and Orthometric® (GO). Eight elastic ligature rings (for mechanical analysis) and eight 5×5mm fragments of the material (for colour stability analysis) were separated from each commercial brand for the control group (C) (n=64) and experimental group (E) (n=64). The control group was not exposed to cigarette smoke. Colourimetric status (CIEL*a*b* System) and light transmittance (% transmitted light) were evaluated using Vita Easyshade Compact and CM2600 spectrophotometers, respectively. The mechanical resistance was evaluated using a universal testing machine (EMIC DL), performing tensile testing (speed 5mm/min). The analyses occurred at the following times: T0, before exposure to the smoke; T1, after the 1st exposure; and T2, after the 2nd exposure to cigarette smoke. Comparison between the groups and evaluation of the time effect were performed with the ANOVA/Tukey (a=0.05) and ANOVA-MR tests with Bonferroni correction (α=0.016). RESULTS: Significant differences were only observed for colour stability in the GA-E (NBS T2: 15.94±1.88) and GM-E (NBS T2: 16.11±4.54) groups (P<0.05); transmittance in the GA-E group (T2-T0: -9.07±5.01) (P<0.016) and mechanical resistance in the GA-C group (T2-T0: -0.95±0.61N) (P<0.016). CONCLUSION: The orthodontic elastic ligatures were sensitive to the cigarette smoke exposure regarding to loss of mechanical strength properties and change in colour stability.

Chromatic analysis of orthodontic resin bonding agents exposed to different antiseptic mouthrinses.

OBJECTIVE: To assess the color of different orthodontic resin bonding agents exposed to three antiseptic mouthrinses for a prolonged time interval (10-year aging simulation). METHODS: 160 specimens were distributed into four groups, according to the orthodontic resin bond agent (Concise, Transbond XT, Transbond Plus Color Change, and Natural Ortho). Each group was exposed to different antiseptic mouthrinses: alcohol-based (Listerine®), alcohol-free (Oral-B®), chlorhexidine (Periogard®) and distilled water as the control. Specimens were submitted to two cycles of staining and artificial aging. Color was evaluated by means of a digital spectrophotometer at the beginning of the experiment and after every cycle. The system used to assess color changes was the CIE L*a*b*. Data was analyzed using the ANOVA and Tukey post-hoc test. RESULTS: After simulation of 10 years of aging, Transbond XT and Natural Ortho composites presented no statistically significant differences in ∆E when exposed to different mouthrinses. The Concise composite specimens exposed to alcohol-free mouthrinse presented a significant difference when compared with specimens from the same group exposed to other antiseptic mouthrinses. Transbond Plus Color Change specimens exposed to chlorhexidine mouthrinse and to alcohol-containing mouthrinse presented a significant difference when compared with the specimens from the group exposed to water and alcohol-free antiseptic. CONCLUSION: All orthodontic resin bonding agents tested presented clinically perceptible color changes when exposed to at least one of the mouthrinses, except for the Natural Ortho composite. The Concise composite exposed to the alcohol-free solution was the resin that presented the highest color change values.