Biomechanical analysis of total arch maxillary distalization using infrazygomatic crest miniscrews: a finite element analysis study.

AIM: To evaluate the maxillary incisors and canine's immediate movement tendency using three different power arms (PA) height levels during total arch maxillary distalization supported on infrazygomatic crest (IZC) miniscrews according to finite element analysis (FEA). METHODS: Three finite element models of the maxilla were developed based on CBCT imaging of a teenage male patient presenting a Class II Division 1 malocclusion in the early permanent dentition. Maxillary complex, periodontium, orthodontic accessories, IZC miniscrews and an orthodontic wire were digitally created. The PAs were placed between canines and lateral incisors and projected at 4, 7, and 10 mm height distances. After that, distalization forces were simulated between PA and IZC miniscrews. RESULTS: The anterior teeth deformation produced in the FEA models was assessed according to a Von Mises equivalent. The stress was measured, revealing tendencies of initial maxillary teeth movement. No differences were found between the right and left sides. However, there was a significant difference among models in the under-stress areas, especially the apical and cervical root areas of the maxillary anterior teeth. More significant extrusion and lingual tipping of incisors were observed with the 4 mm power arm compared to the 7 mm and 10 mm ones. The 10 mm power arm did not show any tendency for extrusion of maxillary central incisors but a tendency for buccal tipping and intrusion of lateral incisors. CONCLUSION: The maxillary incisors and canines have different immediate movement tendencies according to the height of the anterior point of the en-masse distalization force application. Based on the PA height increase, a change from lingual to buccal tipping and less extrusion tendency was observed for the incisors, while the lingual tipping and extrusion trend for canines increased.

Current status of the biomechanics of extra-alveolar miniscrews.

Temporary skeletal anchorage devices such as miniscrews are frequently used nowadays. Compared to miniplates, miniscrews are much less expensive and technically easier to place and remove; they are popular and can be easily placed by an orthodontist. Extra-alveolar miniscrews offer benefits compared to inter-radicular miniscrews, such as reduced risk of root damage and the lack of interference with the mesiodistal tooth movement. They are particularly useful for addressing anchorage loss issues and enabling specific tooth movements such as total arch maxillary and mandibular retraction, posterior distalization, molar protraction, molar intrusion, occlusal plane control, and midline correction. The present paper discusses the current biomechanics principles related to the use of extra-alveolar miniscrews placed in the infrazygomatic and mandibular buccal shelf.

Dental arch changes comparison between Expander with Differential Opening, Hyrax-type and Haas-type expanders: A prospective clinical study.

OBJECTIVE: Compare changes in arch form after RME achieved by Expander with Differential Opening (EDO), Hyrax-type and Haas-type expanders. MATERIALS AND METHODS: Dental models were obtained from 61 patients aged 7-11 years before expansion (T1) and 6 months after the active phase when the appliances were removed (T2). The groups were formed according to the expander used: EDO (n = 18, mean age: 9.46 ± 0.82 years), Hyrax-type (n = 22, mean age: 9.62 ± 1.57 years) and Haas-type (n = 21, mean age: 9.29 ± 1.05 years). The expander`s activation protocol consisted of 7 mm, except for EDO`s anterior screw, which was 9 mm. The measurements of upper and lower intercanine distance, inter-first permanent molar, arch perimeter and length, maxillary canine and first-permanent molar inclination, and palatal depth were performed using the OrthoAnalyzer 3D software. Intergroup comparisons of T1 and between changes (T2-T1) were performed using ANOVA followed by Tukey. RESULTS: In the upper intercanine distance EDO provided a greater increase than Haas-type. In the distance between upper fist permanent molars EDO showed higher values than Haas-type and Hyrax-type. In the lower intercanine distance and maxillary arch length, Haas-type promoted higher increase than EDO. CONCLUSIONS: The EDO promoted greater transverse changes in anterior region than Haas-type and greater transverse changes in posterior region of the maxilla than both conventional expanders. The appliance used for RME influences dental arch changes after treatment; therefore, it is recommended to individualize the choice of expander depending on the clinical necessity of each case.

Total arch maxillary distalization using infrazygomatic crest miniscrews in the treatment of Class II malocclusion: a prospective study.

OBJECTIVES: To evaluate treatment effects in Class II patients using infrazygomatic crest (IZC) miniscrews (MS). MATERIALS AND METHODS: A prospective sample of 25 adolescents (14 females and 11 males; mean age: 13.6 ± 1.5 years) who underwent maxillary dentition distalization treatment with IZC MSs were recruited. Lateral cephalograms and digital models at the beginning of treatment (T1) and after Class II molar correction (T2) were obtained. To compare cephalometric and digital model changes, paired t-test and Wilcoxon test were used. A significance level of 5% was used. RESULTS: All patients achieved Class II molar correction over a mean period of 7.7 ± 2.5 months. The IZC MS therapy provided 4 mm of distalization; there was 1.2 mm of intrusion of the first molar with 11.2° distal tipping. The maxillary incisors were retracted 4.7 mm and tipped lingually 13.4°. Overjet and overbite showed a reduction of 3.6 mm and 2.4 mm, respectively. The occlusal plane rotated clockwise 2.8°. The upper lip was retracted by 1 mm and the nasolabial angle increased 5.1°. There was an increase in the interpremolar and intermolar distances. CONCLUSIONS: Total arch distalization of the maxillary dentition using IZC MS was effective in the treatment of Class II malocclusions.

Effects of orthodontic treatment with aligners and fixed appliances on speech.

OBJECTIVES: To evaluate effects of orthodontic treatment with aligners and conventional fixed appliances on production of speech. MATERIALS AND METHODS: This was a parallel, randomized clinical trial. Patients with Angle Class I malocclusion, moderate crowding, and no speech impairment were randomly allocated to two groups: patients with orthodontic aligners (OAs; n = 20; mean age = 23.60 ± 5.65 years) and those with conventional fixed appliances (n = 20; mean age = 20.56 ± 4.51 years) and treated at the University of North Parana's clinic in Londrina, Brazil. Evaluation of speech production was performed semiobjectively by a speech therapist (myofunctional orofacial examination) and subjectively (self-assessment) at five time points: baseline, immediately after insertion of appliances, and subsequently at 3, 30, and 180 days after insertion. For intergroup comparison, independent t, χ2, Fisher exact, and Mann-Whitney tests were used; for intragroup comparison, the Friedman test was applied (α = 5%). RESULTS: In the semiobjective evaluation, patients with OAs exhibited a change in production of speech production, compared with patients with fixed appliances, immediately and 3 days after insertion of appliances (P < .001). Thirty days after insertion, the groups were similar (P = .487), an outcome that was unchanged at 180 days. However, in the self-assessments, patients in both groups reported significant speech difficulties immediately and 3 days after insertion of appliances, but such impairment was no longer perceived at 30 days or 180 days. CONCLUSIONS: Although the speech therapist identified changes in speech production at the start of treatment in the OA group only, patient self-assessments demonstrated that orthodontic treatment, regardless of the type of appliance used, interfered with their perception of speech.

Perceived pain during rapid maxillary expansion in children with different expanders.

OBJECTIVES: To evaluate and compare the intensity of pain caused by rapid maxillary expansion (RME) with two expanders: Hyrax and Haas type, in growing patients. MATERIALS AND METHODS: Thirty-nine patients (23 girls and 16 boys) with an average age of 9.3 years (SD = 1.39 years) were randomized into two groups and treated with Hyrax- and Haas-type expanders. In both groups, initial activation of the expander screw was one full turn on the first day followed by 2/4 of a turn two times a day (morning and night) for 7 days. Inclusion criteria were patients presenting with a posterior crossbite or maxillary atresia between 7 and 12 years old. To evaluate the intensity of pain during the active phase of the treatment, a combination of the Numerical Rating Scale and Wong-Baker Faces Pain Scale was used. Mann-Whitney test was used to compare the two treatment groups. RESULTS: There was significant inverse correlation between days following insertion and pain. During the expansion period, 100% of the children reported some pain. Hyrax expander subjects reported greater pain than those treated with the Haas-type expander only on the first day. The level of pain remained greater in girls throughout treatment. CONCLUSIONS: Pain was reported regardless of the type of expander and was higher in the Hyrax group only on the first day of activation.

Evaluation of pain intensity in patients treated with aligners and conventional fixed appliances: Randomized clinical trial.

OBJECTIVE: This randomized clinical trial aimed to compare the pain intensity in patients treated with orthodontic aligners and conventional fixed appliances. SETTING AND SAMPLE POPULATION: This study was a randomized clinical trial. The sample comprised 39 patients randomly allocated into 2 groups: OA (orthodontic aligners, n = 20) and FA (Fixed Appliance, n = 19). MATERIAL AND METHODS: The pain intensity was measured by the visual analogue scale (VAS) in the following periods: T0 (baseline), T1 (seven days after appliance placement) and seven days after each return on the first (T2), third (T3) and sixth (T4) months. The following variables were also investigated in the baseline: conditioned pain modulation, anxiety levels, hypervigilance and catastrophizing. The VAS measurements between groups were compared by the Mann-Whitney test. Comparisons between periods within each group were performed by the Friedman test. Data regarding catastrophizing and hypervigilance were compared by the t test. All tests were applied at a significance level of 5%, with 95% confidence interval. RESULTS: Both groups presented similar levels of anxiety, hypervigilance, catastrophizing and conditioned pain modulation. Both groups did not differ concerning the pain intensity in all periods. The intragroup evaluation revealed statistical differences between days in the FA group at all moments evaluated, for the OA group, similar findings between days were found for the T1 evaluation; however, at the 6-month period (T4), the pain levels varied over these days without statistical difference. Higher levels of pain were observed in the first seven days after appliance placement. CONCLUSION: The pain intensity, usually mild, was not influenced by the appliance design, although different patterns of reported pain seem to occur between groups.

A prospective clinical trial of the effects produced by the Connecticut intrusion arch on the maxillary dental arch.

OBJECTIVE: To assess and compare the effects produced in the maxillary dental arch by means of Connecticut intrusion arch (CIA) with or without a cinch back on the distal end of the tube of the first molars. MATERIALS AND METHODS: This study included 44 patients with a mean age of 13.1 ± 1.8 years treated for deep bite with a CIA randomly divided into two groups: group 1 (G1), 22 patients with initial mean age of 12.72 ± 1.74 years treated with the CIA in the upper arch without a cinch back on the distal surface of the tube of the first molars, and group 2 (G2), 22 patients with an initial mean age of 13.67 ± 2.03 years treated with the CIA with a cinch back. Lateral cephalograms were available before treatment (T1) and after intrusion of maxillary incisors (T2). The mean treatment period was 5.5 ± 1.45 months. Intragroup and intergroup changes in the maxillary incisor and molar positions were analyzed by paired and independent t-tests associated with the Holm-Bonferroni correction method for multiple comparisons (P < .05). RESULTS: There were significant differences between groups in terms of maxillary incisor displacement. The maxillary incisors flared labially (2.17°) and proclined (1.68 mm) in group 1, whereas a palatal inclination (-1.99°) and retroclination (-1.13 mm) was observed in group 2. No significant differences were found for the molar positions between the groups. CONCLUSIONS: The presence or absence of a distal bend in CIA affects incisor tipping and proclination during intrusion mechanics.

Self-perception of facial esthetics by patients with different profiles compared with assessments of orthodontists and lay people.

INTRODUCTION: This study evaluated the perception of facial esthetics of patients with different profiles as assessed by orthodontists, lay people, and patients. METHODS: The sample comprised 120 patients (81 females, 39 males; mean age, 26.3 years) selected from private practices at the onset of orthodontic treatment. The patients were divided into 3 groups of 40 according to the type of facial profile. The groups were composed of straight, concave, and convex profiles, on the basis of the facial convexity angle (G.Sn.Pog') measured on the initial cephalometric tracings. Patients analyzed only their frontal (smiling and at rest) and profile facial photographs and evaluated the pleasantness of these images on a 5-point Likert scale. A group of 30 orthodontists and 30 lay people also evaluated the patients' facial pleasantness, using the same scale. Factorial analysis of variance (convexity and sex) was used to evaluate the differences between the convexities, and analysis of variance mixed model (type of evaluator and sex) to compare the 3 categories of evaluators, using the aligned rank transform technique. The correlation between the convexity angle and facial pleasantness was assessed by the Spearman correlation coefficient. RESULTS: Patients and lay people assigned higher pleasantness scores than orthodontists, with statistically significant differences for all evaluations, except for the frontal analysis of the convex group. The correlation coefficients regarding profile convexity and facial pleasantness were negative, indicating a tendency that more convex or concave facial profiles received lower pleasantness scores; however, this correlation was only significant in the evaluation of profile photographs by orthodontists. CONCLUSIONS: Patients with different profiles were scored with acceptable faces by lay people and patients themselves. Orthodontists' perceptions were different; they attributed lower pleasantness scores. Discrepant profiles affect facial esthetics in the profile view when judged by orthodontists.

Bone dehiscence formation during orthodontic tooth movement through atrophic alveolar ridges.

OBJECTIVES: To test the null hypothesis that there is no difference in bone dehiscence formation before and after orthodontic tooth movement through an atrophic alveolar ridge. MATERIAL AND METHODS: This longitudinal retrospective study evaluated pretreatment and posttreatment cone-beam computed tomography imaging of 15 adult patients. Twenty-five teeth were moved through the atrophic alveolar bone, whereas 25 teeth not subjected to translational movement were considered controls. The distances between the cementoenamel junction and the alveolar bone crest were assessed at the mesial, distal, buccal, and lingual surfaces of all of these teeth. Data were compared using the Wilcoxon test. The Spearman correlation test and multivariate linear regression analysis were also performed. RESULTS: In general, crestal bone height was reduced around 0.5 mm in all groups in every direction. Median buccal dehiscence increased significantly (+2.25 mm) (P < .05) in teeth moved through the atrophic ridge. Control teeth also had buccal crest loss (+0.83 mm), but this was not statistically different from that of the experimental teeth. Lingual dehiscence increased significantly for the experimental (+0.17 mm) and control (+0.65 mm) groups. Mesial bone height decreased more in the control group (-0.44mm) than in the experimental group (-0.14mm). There was moderate correlation between amount of tooth movement and alveolar bone loss. CONCLUSIONS: The null hypothesis was rejected as dehiscence increased after tooth movement through an atrophic alveolar ridge, mainly in the buccal plate.

Tomographic evaluation of dentoskeletal effects of rapid maxillary expansion using Haas and Hyrax palatal expanders in children: A randomized clinical trial.

BACKGROUND: Rapid maxillary expansion (RME) is a usual procedure for correcting the transversal maxillary deficiency. Among the most used appliances are the Haas type (tooth-tissue-borne) and Hyrax (tooth-borne) whose main difference is the design. This study aimed to evaluate the dentoskeletal effects of RME using two different expanders in children. MATERIAL AND METHODS: The sample was composed of 42 children of both gender presenting unilateral or bilateral posterior crossbite with mean age 9.49 (SD± 1.35). Patients were randomized into two groups according to the type of expander: Hyrax (n= 21, 9 boys and 12 girls) and Haas (n= 21, 11 boys and 10 girls). Multiplanar coronal and axial slices obtained from cone-beam computed tomography images (i-Cat, Hartsfield, PA, USA) were used at pretreatment (T1) and after 6 months when the expander was removed (T2). Measurements were performed on Dolphin Imaging Systems 11.7 software (Chatsworth, California, USA). The following variables were evaluated: inclinations of the posterior teeth, transverse skeletal widths, length of maxillary dental arch, buccal bone thickness and level of buccal alveolar crest. Statistical analysis performed using chi-squared test to compare the sex ratios between groups and independent t test with the Bonferroni correction for multiple tests. RESULTS: RME increased all maxillary transverse dimensions, regardless of the type of expanders used. Subjects in the Hyrax group experienced significantly increase in the lingual bone thickness (0.94 mm) compare to Haas group (0.21 mm). CONCLUSIONS: The Hyrax-type expander produced greater increase in the lingual bone thickness than did the Haas-type expander, but this effect might not be clinically significant. Both appliances presented similar transversal gain and tended to produce similar orthopedic and orthodontic effects. Key words:Cone-beam computed tomography, palatal expansion technique, palate.

A prospective clinical trial of the effects produced by the extrusion arch in the treatment of anterior open bite.

AIM: To evaluate the maxillary dentition effects of the extrusion arch for anterior open bite (AOB) correction in mixed dentition patients. MATERIALS AND METHODS: Fourteen subjects with an initial mean age of 9.17 ± 1.03 years presenting with dentoalveolar AOB (mean - 1.28 ± 1.46 mm) and normal facial pattern (FMA = 25.76°) were treated with an extrusion arch. The mean treatment period was 7.79 ± 2.58 months. Lateral cephalograms and dental models were taken before (T0) and after the correction of AOB (T1). Data were analyzed using paired t test to evaluate differences between T0 and T1. For all tests, a significance level of P < .05 was used. RESULTS: All patients achieved positive overbite at T1, with a mean increase of 3.07 mm. The maxillary incisors extruded 1.94 mm. Retroclination of the maxillary incisors (- 6.15°) and an increase in the interincisal angle (5.57°) were observed. There was a significant decrease in the distance between the incisal edge of the maxillary incisors and the molars (- 2.21 mm). There was significant mesial tipping of the maxillary molar (- 11.49°). Significant reductions of overjet (- 1.65 mm), arch perimeter (- 3.02 mm), and arch length (- 2.23 mm) were noted. The transverse maxillary intermolar distance did not change significantly. CONCLUSIONS: The use of a maxillary extrusion arch was effective in the treatment of AOB. Overbite increased due to incisor extrusion, as well as retroinclination and overjet reduction. However, side effects, such as mesial molar tipping and decreases in arch perimeter and length might occur.

A comparative study of the effect of the intrusion arch and straight wire mechanics on incisor root resorption: A randomized, controlled trial.

OBJECTIVE: To analyze and compare external apical root resorption (EARR) of maxillary incisors treated by intrusion arch or continuous archwire mechanics. MATERIALS AND METHODS: This cone-beam computed tomography (CBCT) study analyzed 28 deep bite patients in the permanent dentition who were randomly divided into two groups: Group 1, 12 patients with initial mean age of 15.1 ± 1.6 years and mean overbite of 4.6 ± 1.2 mm treated with the Connecticut intrusion arch (CIA) in the upper arch (Ortho Organizers, Carlsbad, Calif) for a mean period of 5.8 ± 1.27 months. Group 2, 16 patients with initial mean age of 22.1 ± 5.7 years and mean overbite of 4.1 ± 1.1 mm treated with conventional leveling and alignment using continuous archwire mechanics for 6.1 ± 0.81 months. The degree of EARR was detected in 112 maxillary incisors by using CBCT scans and a three-dimensional program (Dolphin 11.7, Dolphin Imaging & Management Solutions, Chatsworth, Calif). The CBCT scans were obtained before (T1) and 6 months after initiation of treatment (T2). Differences between and within groups were assessed by nonpaired and paired t-tests, respectively, with a 5% significance level. RESULTS: Significant differences were found for both groups between T1 and T2 ( P < .05) indicating that EARR occurred in both groups. However, there were no significant differences when EARR was compared between group 1 (-0.76 mm) and group 2 (-0.59 mm). CONCLUSIONS: The Connecticut intrusion arch did not lead to greater EARR of maxillary incisors when compared with conventional orthodontic mechanics.

Effectiveness of open bite correction when managing deleterious oral habits in growing children and adolescents: a systematic review and meta-analysis.

BACKGROUND/OBJECTIVES: Oral habits are common etiological factors for anterior open bites (AOBs) in growing children and adolescents. The objective of this review was to provide a literature synthesis evaluating the effectiveness of open bite correction in growing individuals with the use of habit-interception appliances. SEARCH METHODS: Electronic searches were conducted on PubMed, Embase, Cochrane Library, Web of Sciences, Scopus, Google Scholar, Scielo, and Lilacs databases. Trials registries were consulted for ongoing trials, and a partial grey literature search was also conducted. SELECTION CRITERIA: The selection criteria included controlled clinical trials enrolling growing subjects who underwent habit-interception orthodontic treatment to correct dental and/or skeletal AOB. DATA COLLECTION ANALYSIS: Data was grouped and analysed descriptively. A meta-analysis was only possible regarding crib therapy effectiveness. Qualitative appraisal was performed according to Cochrane Risk of Bias tool for randomized clinical trials (RCTs) and the MINORS tool for non-randomized clinical trials (nRCTs). RESULTS: Two RCTs and nine nRCTs were identified. Most of them presented relevant limitations. Crib therapy demonstrated to be effective (+3.1mm overbite correction). However, most of the dental effects are seemingly lost with time; and the skeletal effects are still controversial. Other habit-interception appliances, such as spurs, were not sufficiently investigated. CONCLUSIONS: Crib therapy appears to be effective on a short time basis. As for other habit-interception appliances, insufficient evidence could not provide reliable conclusions.

Dimensional changes of dental arches produced by fixed and removable palatal cribs: A prospective, randomized, controlled study.

OBJECTIVE: To evaluate the dimensional changes of dental arches on digital models of open bite treatment with fixed and removable palatal cribs. MATERIALS AND METHODS: The sample comprised 41 patients of both sexes who were white, aged 7-10 years, and who had mixed dentition, Angle Class I molar relationship, and a negative overbite of at least 1 mm. The sample was randomly divided into two groups: G1, fixed palatal crib; and G2, removable palatal crib. Cast models, obtained initially (T1) and after 1 year of treatment (T2), were scanned by a three-dimensional (3D) scanner, 3Shape R700, producing a 3D image. Measurements were performed by a calibrated examiner using OrthoAnalyzer™ 3D software. RESULTS: At T2-T1, differences were observed between the groups regarding vertical dentoalveolar development and overjet. There was more mandibular incisor extrusion for G1 (-1.66 mm) than for G2 (-0.54 mm). An overjet increase was observed in G1 (0.56 mm), in contrast to a reduction in G2 (-0.40 mm). There was a similar overbite increase for both groups (3.51 mm for fixed palatal crib and 3.88 mm for removable palatal crib). CONCLUSIONS: Both the treatment protocols are similarly effective for anterior open bite correction, providing an overbite increase with dentoalveolar arch changes, especially in the anterior region.

Dentoskeletal effects produced by removable palatal crib, bonded spurs, and chincup therapy in growing children with anterior open bite.

OBJECTIVE: To evaluate the dentoskeletal effects of different anterior open bite treatment modalities in children. MATERIALS AND METHODS: This cephalometric study assessed changes resulting from different treatment approaches on 77 growing children with anterior open bite. A control group (n = 30) was used for comparison. Lateral cephalograms were available before treatment and after 12 months. The sample was divided into four groups: removable palatal crib associated with a chincup (G1), bonded spurs associated with a chincup (G2), chincup (G3), and nontreated control (G4). Statistical comparisons among the four groups were performed on T1 and the treatment changes using analysis of variance with Tukey's post hoc tests. RESULTS: No statistically significant changes in skeletal variables were found among the groups, except for lower anterior face height (LAFH) increase in G1. Overall, effects in all of the treated groups were exclusively dentoalveolar. A larger overbite (OB) increase was observed in G1 and G2 when compared with G3 and G4. The maxillary incisors in G1 showed increased palatal tipping, retrusion, and more vertical dentoalveolar development as well as increased lingual tipping among mandibular incisors. There was less vertical development of maxillary and mandibular molars in G3. CONCLUSIONS: A removable palatal crib provided an improvement in OB (97.5%), followed by the bonded spurs (84.5%). Conversely, the chincup-only group did not have positive OB effects.

Can bone thickness and inter-radicular space affect miniscrew placement in posterior mandibular sites?

PURPOSE: The proper angle of miniscrew insertion is important for cortical anchorage, patient safety, and biomechanical control. The purposes of this study are to report the alveolar process thickness and inter-radicular space in the posterior region of the mandible, to assess the impact of different miniscrew insertion angle protocols, and to identify differences between the genders or types of malocclusion. MATERIALS AND METHODS: In this retrospective study, 100 individuals were selected for orthodontic treatment at a radiology clinic. Cone-beam computed tomography data were imported into 3-dimensional software. The predictor variable was the location in the mandible and insertion angle. The demographic variables collected included age, gender, and malocclusion (Angle Classes I and II). The primary outcome variables were bone thickness and inter-radicular space. The inter-radicular spaces were evaluated 5 mm from the cement-enamel junction. The bone thicknesses were taken at 45°, 60°, and 90° in relation to the alveolar ridge, simulating a miniscrew insertion. These factors were evaluated for sexual dimorphism and malocclusion (Angle Classes I and II). Sexual dimorphism and malocclusion were evaluated with t tests. To compare the inter-radicular space and the thickness of bone between areas, an analysis of variance for repeated measures was used. RESULTS: The sample was composed of 100 patients with a mean age of 17.4 ± 6.74 years. There were 61 female and 39 male patients and 60 Class I and 40 Class II molar relationships. The inter-radicular space ranged from 2.46 to 3.31 mm, and alveolar bone thickness ranged from 8.01 to 13.77 mm. The thickness tended to decrease with the increase in insertion angle from 45° to 90°. No significant differences between the genders or types of malocclusion were found. CONCLUSIONS: The results of this study suggest that the safest areas for the placement of miniscrews are between the first and second premolars and between the first and second molars, regardless of the angle of insertion.

Comparison of mechanical properties of beta-titanium wires between leveled and unleveled brackets: an in vitro study.

BACKGROUND: The objective of this study is to evaluate the force-deflection behavior of beta-titanium alloy wires between two leveled and unleveled bracket alignment scenarios using a three-point bending test. METHODS: Six groups of ten beta-titanium alloy wire segments (0.017 × 0.025-in. diameter) of different manufacturers (Orthometric, Ortho Organizers, GAC, Morelli, and Ormco) were used. Both brackets were bonded to an acrylic jig with a 10-mm interbracket distance. A 1-mm deflection test in two hypothetical conditions (with aligned brackets and by simulating a 2-mm horizontal displacement of the brackets) was explored. Forces of activation and deactivation of the wires during both tests were compared by an analysis of variance (ANOVA) tests followed by a Tukey test. RESULTS: A statistically significant difference was found in the force-deflection behavior between some of the wires in both simulated in vitro conditions. For the leveled-type alignment scenario, the differences between wires were up to 70 g (range 110 to 179 g). For the unleveled-type alignment scenario, these differences were up to 65 g (range 111 to 175 g). CONCLUSIONS: The study showed some significant differences in forces generated during activation and deactivation among the five types of beta-titanium wires tested. In comparing leveled and unleveled brackets during activation, only Orthometric Beta Flexy and Ormco Beta-titanium were different between them.

Three-dimensional upper-airway assessment in patients with bronchial asthma.

OBJECTIVE: To assess the upper airway (UAW) total volume (TV), the nasopharyngeal narrowest area (NNA), and the oropharyngeal narrowest area (ONA) in patients with bronchial asthma. MATERIALS AND METHODS: The sample consisted of 52 patients divided into two groups: the control group (n  =  26; mean age  =  14.85 years), which consisted of patients not suffering from bronchial asthma; and the asthmatic group (n  =  26; mean age  =  16.65 years), which consisted of patients with bronchial asthma. To assess UAW-related variables (TV, NNA, and ONA), cone-beam computed tomography scans of the patients were evaluated by means of the Dolphin Imaging software 11.5. All measurements were repeated after 30 days, and the results were submitted to reliability tests by means of the intraclass correlation coefficient and the Bland-Altman agreement test. The values obtained for TV, NNA, and ONA for each group were compared by using Student's t-test for independent samples (5% level of significance). RESULTS: The results showed that the groups were matched concerning gender, cephalometric characteristics, and type of malocclusion. The asthmatic group had significantly lower TV (P  =  .01) and ONA (P  =  .007) than the control group. However, no significant difference was observed for NNA between the groups (P  =  .54). CONCLUSIONS: Bronchial asthma may be a determining factor for the reduction of UAW dimensions, as patients with asthma showed significant reductions in TV and ONA dimensions.