Comparisons of soft tissue changes after Herbst appliance treatment in three different growth phases.

BACKGROUND: This study aimed to compare the soft tissue effects of Herbst appliance in Class II malocclusion patients treated in three different craniofacial growth phases: prepubertal (PRE), circumpubertal (CIR), and postpubertal (POS). METHODS: In total, 95 patients with Class II Division 1 malocclusion previously treated with a Herbst appliance were analyzed. Through the cervical vertebral maturation stages method, patients were allocated into three groups depending on the growth craniofacial phase at the beginning of treatment: PRE, CIR, and POS. Seventeen cephalometric measures were evaluated from each lateral radiograph before and after Herbst therapy using the Radiocef 2 software (Radio Memory, Belo Horizonte). Intragroup and intergroup treatment changes were compared statistically using a paired t test and MANOVA test, respectively. RESULTS: Soft tissue thickness changes were related only to mandible; all three mandibular measurements (L1_LL, B_B', and Pog_Pog') showed thickening for the PRE group ranging from 0.92 mm (Pog_Pog') to 2.02 mm (B_B'), and only lower lip thickened overtime for the POS group (L1_LL = 0.99 mm). Soft and hard tissue pogonion displaced anteriorly, but only the soft tissue showed differences among groups; PRE group presented more anterior displacement than POS group (3.61 mm and 1.39 mm, respectively). Hard and soft tissue facial convexity decreased more in the PRE and CIR groups than in the POS group. Mentolabial sulcus depth reduced more in the PRE (1.07 mm) and CIR (1.29 mm) groups than in the POS (0.55 mm) group. Horizontal movement of the skeletal and soft pogonion presented a moderate-high positive correlation (r = 0.783), and hard and soft facial convexity showed a moderate-low positive correlation (r = 0.403). CONCLUSIONS: Herbst appliance therapy produces soft tissue improvements in the three phases of craniofacial growth, being greater in patients in the PRE and CIR phases.

Midsagittal Plane First: Building a Strong Facial Reference Frame for Computer-Aided Surgical Simulation.

PURPOSE: A facial reference frame is a 3-dimensional Cartesian coordinate system that includes 3 perpendicular planes: midsagittal, axial, and coronal. The order in which one defines the planes matters. The purposes of this study are to determine the following: 1) what sequence (axial-midsagittal-coronal vs midsagittal-axial-coronal) produced more appropriate reference frames and 2) whether orbital or auricular dystopia influenced the outcomes. METHODS: This study is an ambispective cross-sectional study. Fifty-four subjects with facial asymmetry were included. The facial reference frames of each subject (outcome variable) were constructed using 2 methods (independent variable): axial plane first and midsagittal plane first. Two board-certified orthodontists together blindly evaluated the results using a 3-point categorical scale based on their careful inspection and expert intuition. The covariant for stratification was the existence of orbital or auricular dystopia. Finally, Wilcoxon signed rank tests were performed. RESULTS: The facial reference frames defined by the midsagittal plane first method was statistically significantly different from ones defined by the axial plane first method (P = .001). Using the midsagittal plane first method, the reference frames were more appropriately defined in 22 (40.7%) subjects, equivalent in 26 (48.1%) and less appropriately defined in 6 (11.1%). After stratified by orbital or auricular dystopia, the results also showed that the reference frame computed using midsagittal plane first method was statistically significantly more appropriate in both subject groups regardless of the existence of orbital or auricular dystopia (27 with orbital or auricular dystopia and 27 without, both P < .05). CONCLUSIONS: The midsagittal plane first sequence improves the facial reference frames compared with the traditional axial plane first approach. However, regardless of the sequence used, clinicians need to judge the correctness of the reference frame before diagnosis or surgical planning.

Effects of stress relaxation in beta-titanium cantilevers used in orthodontic mechanics.

OBJECTIVE: This study evaluated the force decay and design shape changes caused by stress relaxation in two different orthodontic cantilever configurations. METHODS: Eighty cantilevers made of 0.017 x 0.025-in beta-titanium wires were standardized in a passive position, using real scale templates, and randomly divided into two groups (n = 40): Type 1 and Type 2. Each group received a different design (Type 1 with three bends, and Type 2 with two bends), and both were divided in four subgroups (n = 10) according to the evaluation periods: G1 = 24h, G2 = 1 week, G3 = 4 weeks, and G4 = 8 weeks. Mechanical tests were performed immediately after preactivation and at the end of each period, to evaluate force decay. The cantilevers were also scanned and the angles of the bends were measured to assess shape changes. RESULTS: Cantilever forces decayed over time. Type 1 - G1 showed less force decay than Type 2 (10.83 cN vs 17.87 cN). Type 1 cantilevers showed significant force decay only when G4 was compared to G1 (9.05 cN), G2 (11.73 cN), and G3 (9.78 cN). Type 2 cantilevers presented differences when G1 was compared to G2 (9.57 cN) and G3 (7.89 cN). Regarding to the cantilever angle closest to the bracket insertion, Type 1 cantilevers showed significant decrease for G2 (1.58°) and G4 (1.52°). CONCLUSIONS: Cantilevers' design and proximity of the bends influenced force decay pattern overtime. Type 1 cantilevers presented more stable design at the first weeks than Type 2.

Effect of print orientation on the dimensional accuracy of orthodontic aligners printed 3-dimensionally.

INTRODUCTION: Fabrication of orthodontic aligners directly via 3-dimensional (3D) printing presents the potential to increase the efficiency of aligner production relative to traditional workflows; however tunable aspects of the 3D-printing process might affect the dimensional fidelity of the fabricated appliances. This study aimed to investigate the effect of print orientation on the dimensional accuracy of orthodontic aligners printed directly with a 3D printer. METHODS: A digitally designed aligner of 500 µm thickness was printed in 3D in Grey V4 (Formlabs, Somerville, Mass) resin at 8 angulations at 45° intervals (n = 10 per angulation) using a stereolithography 3D printer. Each aligner was scanned with an optical scanner, and all but the intaglio surface of each scan was digitally removed. Each resultant scan file was superimposed onto the isolated intaglio of the designed master aligner file. The dimensional deviation was quantified with Geomagic Control software (3D Systems, Rock Hill, SC), and data were analyzed using R statistical software (version 2018; R Core Team, Vienna, Austria) (P <0.05). RESULTS: Print angle showed a statistically significant effect on standard deviation, average positive deviation, absolute average negative deviation, and percentage of points out of bounds (tolerance bounds defined as ±250 µm) (P <0.05). Qualitative analysis of the 3D surface deviation maps indicated that the 0° and 90° groups showed less deviation and appeared to be the most accurate in the anterior regions. Overall, the majority of the print angle groups studied were not printed within clinically acceptable tolerance ranges, with the major exception being the 90° group, which printed nominally within clinically acceptable tolerance ranges. CONCLUSIONS: With the workflow applied, print orientation significantly affects the dimensional accuracy of directly 3D-printed orthodontic aligners. Within the limitations of this study, printing at the 90° angulation would be advised as it is the group with the most accurate prints relative to the 7 other orientations investigated, although not all differences were statistically significant.

Potentialities and limitations of computer-aided design and manufacturing technology in the nonextraction treatment of Class I malocclusion.

INTRODUCTION: Computer-aided design and manufacturing (CAD-CAM) systems have assisted orthodontists to position brackets virtually. The purpose of this study was to evaluate if a CAD-CAM system could predict the orthodontic treatment outcome of patients with Angle Class I malocclusion with mild crowding or spacing and with no need for orthodontic extraction. METHODS: Using the American Board of Orthodontics Cast-Radiograph Evaluation (ABO-CRE) and color map superimposition, the treated occlusion was compared with the virtual final occlusion of 24 young adults with Class I occlusion. Using eXceed software (eXceed, Witten, Germany), we created the final occlusion prediction for each patient (virtual set up group). A digital model of the final occlusion of each patient was created (treated occlusion group). ABO-CRE score was used to compare groups. In addition, a color map was created for all subjects to access the mean and range values between the virtual set up model and treated occlusion model of each patient. Random and systematic errors were calculated. In addition, chi-square and t test were used. RESULTS: Comparisons between virtual set up occlusion and treated occlusion showed statistically significant differences in 3 out of 7 measurements: interproximal contact score was larger for treated than virtual occlusion (0.45 mm and 0.04 mm, respectively), and the treated occlusion showed larger values than the virtual occlusion for occlusal contacts (14.13 mm and 7.62 mm, respectively) and overjet (7.37 mm and 0.66 mm, respectively). Although the treated occlusion showed a larger score than the virtual occlusion (50.41 mm and 34.58 mm, respectively), there is no significant difference between both. Root angulation decreased (from 1.95 ± 1.29 to 0.65 ± 0.71) because of the treatment. CONCLUSIONS: ABO-CRE overall score presents no difference between groups. In addition, CAD-CAM setup occlusion closely predicts the final teeth alignment and leveling with interarch relationships showing less ABO-CRE score deduction.

Effects of transverse bodily movements of maxillary premolars on the surrounding hard tissue.

INTRODUCTION: This experimental study was designed to (1) produce buccal translation of maxillary premolars and (2) evaluate the effects on the buccal alveolar bone. METHODS: A randomized split-mouth study was designed based on 7 adult male beagle dogs. The experimental side received a custom cantilever appliance fabricated to produce a translatory force through the maxillary second premolar's center of resistance. The contralateral second premolar received no appliance and served as the control. The premolars underwent 6-7 weeks of buccal translation, followed by 3 weeks of fixed retention. Biweekly tooth movements were evaluated using intraoral and radiographic measurements. Pretreatment and posttreatment models were measured to assess tipping. Three-dimensional microscopic tomography was used to quantify the amount and density of buccal bone. Bone formation and turnover were assessed using fluorescent labeling, hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, and bone sialoprotein immunostaining. RESULTS: The applied force (100 g of force) translated (1.4 mm) and minimally tipped (4°) the experimental teeth. Lateral translation produced dehiscences at the mesial and distal roots, with 2.0 mm and 2.2 mm loss of vertical bone height, respectively. Bone thickness decreased significantly (P < 0.05) at the apical (∼0.4 mm), midroot (∼0.4 mm), and coronal (∼0.2 mm) levels. Fluorescent imaging, hematoxylin and eosin staining, and immunostaining for bone sialoprotein all showed new bone formation extending along the entire periosteal surface of the second premolar's buccal plate. Tartrate-resistant acid phosphatase staining demonstrated greater osteoclastic activity on the experimental than that of control sections. CONCLUSIONS: New buccal bone forms on the periosteal surface during and after tooth translation, but the amount of bone that forms is less than the amount of bone loss, resulting in a net decrease in buccal bone thickness and a loss of crestal bone.

An automatic approach to establish clinically desired final dental occlusion for one-piece maxillary orthognathic surgery.

PURPOSE: One critical step in routine orthognathic surgery is to reestablish a desired final dental occlusion. Traditionally, the final occlusion is established by hand articulating stone dental models. To date, there are still no effective solutions to establish the final occlusion in computer-aided surgical simulation. In this study, we consider the most common one-piece maxillary orthognathic surgery and propose a three-stage approach to digitally and automatically establish the desired final dental occlusion. METHODS: The process includes three stages: (1) extraction of points of interest and teeth landmarks from a pair of upper and lower dental models; (2) establishment of Midline-Canine-Molar (M-C-M) relationship following the clinical criteria on these three regions; and (3) fine alignment of upper and lower teeth with maximum contacts without breaking the established M-C-M relationship. Our method has been quantitatively and qualitatively validated using 18 pairs of dental models. RESULTS: Qualitatively, experienced orthodontists assess the algorithm-articulated and hand-articulated occlusions while being blind to the methods used. They agreed that occlusion results of the two methods are equally good. Quantitatively, we measure and compare the distances between selected landmarks on upper and lower teeth for both algorithm-articulated and hand-articulated occlusions. The results showed that there was no statistically significant difference between the algorithm-articulated and hand-articulated occlusions. CONCLUSION: The proposed three-stage automatic dental articulation method is able to articulate the digital dental model to the clinically desired final occlusion accurately and efficiently. It allows doctors to completely eliminate the use of stone dental models in the future.

Clinical Evaluation of Digital Dental Articulation for One-Piece Maxillary Surgery.

PURPOSE: Methods for digital dental alignment are not readily available to automatically articulate the upper and lower jaw models. The purpose of the present study was to assess the accuracy of our newly developed 3-stage automatic digital articulation approach by comparing it with the reference standard of orthodontist-articulated occlusion. MATERIALS AND METHODS: Thirty pairs of stone dental models from double-jaw orthognathic surgery patients who had undergone 1-piece Le Fort I osteotomy were used. Two experienced orthodontists manually articulated the models to their perceived final occlusion for surgery. Each pair of models was then scanned twice-while in the orthodontist-determined occlusion and again with the upper and lower models separated and positioned randomly. The separately scanned models were automatically articulated to the final occlusion using our 3-stage algorithm, resulting in an algorithm-articulated occlusion (experimental group). The models scanned together represented the manually articulated occlusion (control group). A qualitative evaluation was completed using a 3-point categorical scale by the same orthodontists, who were unaware of the methods used to articulate the models. A quantitative evaluation was also completed to determine whether any differences were present in the midline, canine, and molar relationships between the algorithm-determined and manually articulated occlusions using repeated measures analysis of variance (ANOVA). Finally, the mean ± standard deviation values were computed to determine the differences between the 2 methods. RESULTS: The results of the qualitative evaluation revealed that all the algorithm-articulated occlusions were as good as the manually articulated ones. The results of the repeated measures ANOVA found no statistically significant differences between the 2 methods [F(1,28) = 0.03; P = .87]. The mean differences between the 2 methods were all within 0.2 mm. CONCLUSIONS: The results of our study have demonstrated that dental models can be accurately, reliably, and automatically articulated using our 3-stage algorithm approach, meeting the reference standard of orthodontist-articulated occlusion.

A preliminary 3-D comparison of rapid and slow maxillary expansion in children: A randomized clinical trial.

BACKGROUND: This study compared the effects of rapid maxillary expansion (RME) and slow maxillary expansion (SME) using cone-beam computed tomography (CBCT). AIM: To evaluate the skeletal and dentoalveolar effects produced by two different maxillary expansion protocols. DESIGN: Eligibility criteria included maxillary transverse deficiencies in children (mean age, 8.18 years old), randomly assigned to either RME or SME. At the outcome analysis phase, a sample of 29 subjects were analysed (RME group, N = 16 and SME group, N = 13). CBCT scans taken before expansion and 6 months later were evaluated. Five posterior and 6 anterior transverse measurements were made at different vertical levels. Treatment changes were analysed using paired t tests; independent t tests were used to compare the two groups. RESULTS: There were statistically significant (P<.05) increases in maxillary width at the skeletal, alveolar, and dental levels for both groups, with significantly smaller increases at the more superior than inferior levels. The RME group exhibited statistically larger width increases than the SME group for all measures except interorbital width, anterior alveolar process width, and intercanine width. The group differences were greater for anterior than posterior apical base widths. CONCLUSIONS: Rapid maxillary expansion produced greater orthopaedic effects than slow maxillary expansion, with the greatest effects occurring in the anterior apical base.

An Automatic Approach to Reestablish Final Dental Occlusion for 1-Piece Maxillary Orthognathic Surgery.

Accurately establishing a desired final dental occlusion of the upper and lower teeth is a critical step in orthognathic surgical planning. Traditionally, the final occlusion is established by hand-articulating the stone dental models. However, this process is inappropriate to digitally plan the orthognathic surgery using computer-aided surgical simulation. To date, there is no effective method of digitally establishing final occlusion. We propose a 3-stage approach to digitally and automatically establish a desired final dental occlusion for 1-piece maxillary orthognathic surgery, including: 1) to automatically extract points of interest and four key teeth landmarks from the occlusal surfaces; 2) to align the upper and lower teeth to a clinically desired Midline-Canine-Molar relationship by minimization of sum of distances between them; and 3) to finely align the upper and lower teeth to a maximum contact with the constraints of collision and clinical criteria. The proposed method was evaluated qualitatively and quantitatively and proved to be effective and accurate.

Tooth movement rate and anchorage lost during canine retraction: A maxillary and mandibular comparison.

OBJECTIVES: To investigate the canine retraction rate and anchorage loss during canine retraction using self-ligating (SL) brackets and conventional (CV) brackets. Differences between maxillary and mandibular rates were computed. MATERIALS AND METHODS: Twenty-five subjects requiring four first premolar extractions were enrolled in this split-mouth, randomized clinical trial. Each patient had one upper canine and one lower canine bonded randomly with SL brackets and the other canines with CV brackets but never on the same side. NiTi retraction springs were used to retract canines (100 g force). Maxillary and mandibular superimpositions, using cephalometric 45° oblique radiographs at the beginning and at the end of canine retraction, were used to calculate the changes and rates during canine retraction. Paired t-tests were used to compare side and jaw effects. RESULTS: The SL and CV brackets did not show differences related to monthly canine movement in the maxilla (0.71 mm and 0.72 mm, respectively) or in the mandible (0.54 mm and 0.60 mm, respectively). Rates of anchorage loss in the maxilla and in the mandible also did not show differences between the SL and CV brackets. Maxillary canines showed greater amount of tooth movement per month than mandibular canines (0.71 mm and 0.57 mm, respectively). CONCLUSIONS: SL brackets did not show faster canine retraction compared with CV brackets nor less anchorage loss. The maxillary canines showed a greater rate of tooth movement than the mandibular canines; however, no difference in anchorage loss between the maxillary and mandibular posterior segments during canine retraction was found.

Silver diamine fluoride and bond strength to enamel in vitro: A pilot study.

PURPOSE: To evaluate if pre-treatment with silver diamine fluoride (SDF) adversely affects the bond strength of orthodontic brackets to enamel. METHODS: 30 extracted non-carious permanent molar teeth were embedded in acrylic resin cylinders with buccal surfaces exposed and randomly divided equally into two groups. The experimental enamel surfaces were treated with 38% SDF applied for 1 minute between phosphoric acid etch and metal orthodontic bracket bonding with Transbond XT Light Cure Adhesive. Control groups were treated with 37% phosphoric acid etch followed by bonding. All samples were subjected to 500 thermocycles between 5°C and 55°C prior to shear load testing. Mean values and standard deviations of shear bond strengths for each group were analyzed using a general linear model at P< 0.05. Characteristics of bond failure were also recorded via Adhesive Remnant Index (ARI) and analyzed using an ordinal logistic regression at P< 0.05. RESULTS: No significant difference in shear bond strength to enamel was observed between the control and experimental groups (P= 0.65). Comparison of ARI did demonstrate a significant difference between the groups (P= 0.013); SDF significantly altered the characteristic of bond failure, resulting in more adhesive remaining bonded to enamel after failure. No silver staining of treated surfaces was observed. CLINICAL SIGNIFICANCE: The application of SDF to etched non-carious enamel in vitro prior to orthodontic bracket bonding does not adversely affect bond strength.

Evaluation of the rapid and slow maxillary expansion using cone-beam computed tomography: a randomized clinical trial.

OBJECTIVE:: The aim of this randomized clinical trial was to evaluate the dental, dentoalveolar, and skeletal changes occurring right after the rapid maxillary expansion (RME) and slow maxillary expansion (SME) treatment using Haas-type expander. METHODS:: All subjects performed cone-beam computed tomography (CBCT) before installation of expanders (T1) and right after screw stabilization (T2). Patients who did not follow the research parameters were excluded. The final sample resulted in 21 patients in RME group (mean age of 8.43 years) and 16 patients in SME group (mean age of 8.70 years). Based on the skewness and kurtosis statistics, the variables were judged to be normally distributed and paired t-test and student t-test were performed at significance level of 5%. RESULTS:: Intermolar angle changed significantly due to treatment and RME showed greater buccal tipping than SME. RME showed significant changes in other four measurements due to treatment: maxilla moved forward and mandible showed backward rotation and, at transversal level both skeletal and dentoalveolar showed significant changes due to maxillary expansion. SME showed significant dentoalveolar changes due to maxillary expansion. CONCLUSIONS:: Only intermolar angle showed significant difference between the two modalities of maxillary expansion with greater buccal tipping for RME. Also, RME produced skeletal maxillary expansion and SME did not. Both maxillary expansion modalities were efficient to promote transversal gain at dentoalveolar level. Sagittal and vertical measurements did not show differences between groups, but RME promoted a forward movement of the maxilla and backward rotation of the mandible.

Evaluation of the rapid and slow maxillary expansion using cone-beam computed tomography: a randomized clinical trial

ABSTRACT OBJECTIVE: The aim of this randomized clinical trial was to evaluate the dental, dentoalveolar, and skeletal changes occurring right after the rapid maxillary expansion (RME) and slow maxillary expansion (SME) treatment using Haas-type expander. METHODS: All subjects performed cone-beam computed tomography (CBCT) before installation of expanders (T1) and right after screw stabilization (T2). Patients who did not follow the research parameters were excluded. The final sample resulted in 21 patients in RME group (mean age of 8.43 years) and 16 patients in SME group (mean age of 8.70 years). Based on the skewness and kurtosis statistics, the variables were judged to be normally distributed and paired t-test and student t-test were performed at significance level of 5%. RESULTS: Intermolar angle changed significantly due to treatment and RME showed greater buccal tipping than SME. RME showed significant changes in other four measurements due to treatment: maxilla moved forward and mandible showed backward rotation and, at transversal level both skeletal and dentoalveolar showed significant changes due to maxillary expansion. SME showed significant dentoalveolar changes due to maxillary expansion. CONCLUSIONS: Only intermolar angle showed significant difference between the two modalities of maxillary expansion with greater buccal tipping for RME. Also, RME produced skeletal maxillary expansion and SME did not. Both maxillary expansion modalities were efficient to promote transversal gain at dentoalveolar level. Sagittal and vertical measurements did not show differences between groups, but RME promoted a forward movement of the maxilla and backward rotation of the mandible.

RESUMO OBJETIVO: o objetivo do presente ensaio clínico randomizado foi avaliar as transformações dentárias, dentoalveolares e ósseas que ocorrem imediatamente após o tratamento com expansão rápida da maxila (ERM) e lenta (ELM) usando expansores do tipo Haas. MÉTODOS: todos os indivíduos foram submetidos a tomografias computadorizadas de feixe cônico (TCFC) antes da colocação dos expansores (T1) e imediatamente após a estabilização do parafuso (T2). Os pacientes que não seguiram os parâmetros da pesquisa foram excluídos. A amostra final constou de 21 pacientes no grupo ERM (idade média de 8,43 anos) e 16 no grupo ELM (idade média de 8,7 anos). Com base em estatística de assimetria e curtose, as variáveis foram consideradas de distribuição normal, e os testes t pareado e t de Student foram realizados, com nível de significância de 5%. RESULTADOS: o ângulo intermolares mudou significativamente devido ao tratamento, e o grupo ERM apresentou maior inclinação vestibular do que o grupo ELM. O grupo ERM mostrou alterações significativas em outras quatro medidas devido ao tratamento: a maxila apresentou deslocamento anterior e a mandíbula, rotação posterior; no nível transversal, houve tanto alterações ósseas quanto dentoalveolares significativas, devido à expansão maxilar. O grupo ELM apresentou alterações significativas devido à expansão maxilar. CONCLUSÕES: apenas o ângulo intermolares apresentou diferença significativa entre as duas modalidades de expansão maxilar, com maior inclinação vestibular no grupo ERM. A ERM resultou, também, em expansão maxilar óssea, ao contrário da ELM. As duas modalidades de expansão maxilar promoveram, de forma eficiente, um ganho transversal em nível dentoalveolar. As medidas sagitais e verticais não apresentaram diferenças entre os grupos, mas a ERM promoveu o deslocamento anterior da maxila e a rotação posterior da mandíbula.

Como os padrões esqueléticos horizontal e vertical influenciam na espessura do tecido mole facial - um estudo longitudinal em adolescentes / How the horizontal and vertical skeletal patterns affect the facial soft tissue thickness: a longitudinal study with adolescents

Introdução: Esse estudo teve como objetivo avaliar as alterações e desenvolvimento do perfil mole (espessuras labiais superior e inferior) no período entre 10 e 15 anos de idade. Material e método: Uma amostra homogênea Franco-Canadense de 185 indivíduos não tratados ortodonticamente (106 meninas e 79 meninos) foi selecionada. Seis medidas de espessura de tecido mole (ENA', ponto A', lábios superior e inferior, ponto B' e pogônio) foram avaliadas. Indivíduos Classe I (ANB entre 0º a 4º) e Classe II (ANB ≥ 4º) foram comparados, bem como indivíduos classificados como hipodivergentes (MPA = 31.8º ± 2.4º) e hiperdivergentes (MPA = 40.9º ± 2.6º). O dimorfismo sexual também foi avaliado. Resultados: Embora a espessura do tecido mole tenha aumentado entre os 10 e 15 anos de idade, não houve diferenças significativas entre indivíduos Classe I e Classe II, bem como entre hipodivergentes e hiperdivergentes. As diferenças encontradas entre os indivíduos Classe I e Classe II se limitaram ao ponto A' e L1' (10 anos de idade) e L1' e ponto B' (15 anos de idade). Quando os grupos hipo- e hiperdivergentes foram comparados, as mudanças foram em relação ao U1', ponto B', e Pog'(10 e 15 anos de idade). Embora adolescentes masculinos apresentassem tecidos moles mais espessos em quatro (10 anos de idade) e em todas as seis (15 anos de idade) das espessuras avaliadas, apenas a parte do tecido mole maxilar apresentou um maior desenvolvimento entre os cinco anos de avaliação, quando comparados com as adolescentes femininas. Conclusão: O tecido mole torna-se mais espesso durante a adolescência com um padrão semelhante aos indivíduos Classe I, quando comparados com Classe II e também quando indivíduos hipodivergentes são comparados com hiperdivergentes. Adolescentes masculinos apresentaram tecido mole facial mais espesso que o das adolescentes femininas precoce (10 anos de idade) e tardiamente (15 anos de idade), mas apenas em relação aos tecidos maxilares apresentaram um espessamento durante o crescimento (dos 10 aos 15 anos de idade). (AU)

Introduction: The purpose of this study was to identify changes and growth of the soft tissue (upper and lower lip thicknesses) evaluating subjects from 10 to 15 years old. Material and Methods: A homogeneous French-Canadian sample of 185 orthodontically untreated subjects (106 girls and 79 boys) was selected. Six measurements of soft tissue thickness (ENA', point A´, upper and lower lips, point B´ and pogonion) were evaluated. Class I subjects (0º < ANB < 4º) and Class II (ANB ≥ 4º) were compared, as well as subjects classified as hypodivergents (MPA = 31.8º ± 2.4º) and hyperdivergents (MPA = 40.9º ± 2.6º). Sexual dimorphism was also evaluated. Results: Although the soft tissue thickness increased between 10 and 15 years of age, there were no significant differences between Class I and Class II subjects, as well as between hypodivergents and hyperdivergents. The differences between Class I and Class II subjects were related to point A' and L1' (10 year old) and L1' and point B' (15 year old). When hypodivergent and hyperdivergent groups were compared, the changes were restricted to U1', point B' and Pog' (10 and 15 year old). Although male teenagers showed thicker soft tissue than girls in four measurements (10 year old) and in all six measurements (15 year old) of the thickness assessed, only the maxillary soft tissue showed greater growth, between the five years of assessment for boys compared to girls. Conclusion: The soft tissue becomes thicker during the adolescence and this development is similar in subjects Class I, when compared to Class II subjects and also when subjects classified as hypodivergent and hyperdivergent are compared. Male teenagers showed thicker soft tissue than female teenagers precociously (10 year old) and late (15 year old), but only in relation to the maxilla tissue they presented tickening during their growth (from 10 to 15 year of age). (AU)

Odontologia digital contemporânea - scanners intraorais digitais / Contemporary digital dentistry - intraoral digital scanners

Objetivo: O uso de scanners intraorais em Odontologia, visando à reprodutibilidade de dentes e arcadas dentárias, tem sido uma nova tendência na última década. As imagens obtidas são utilizadas principalmente em diagnóstico e planejamento de casos clínicos, mas podem também ser impressas, materializando-se em modelos e troqueis de acordo com a necessidade específica. Materiais e métodos: uma revisão de literatura foi conduzida, via PubMed e Google Acadêmico. Os artigos mais relevantes nas áreas relacionadas foram identificados. Dessa seleção, 30 artigos foram revisados e discutidos. Resultados: técnicas, equipamentos e marcas comerciais, com suas relativas vantagens e desvantagens, são apresentados à comunidade odontológica. Sob o ponto de vista técnico-científico, a acuidade e a precisão dos processos de escaneamento e impressão são as principais demandas e devem ser cuidadosamente testadas. Sob o ponto de vista clínico, a facilidade de cada operação, os requisitos necessários para que se realizem (por exemplo, uso de contraste), o tamanho e peso dos equipamentos (em especial da câmera intraoral), o processo de esterilização, o tempo de escaneamento e o conforto do paciente são os fatores mais relevantes. Do ponto de vista comercial, a disponibilidade dos equipamentos, seu preço e sua assistência técnica são as principais condições a serem consideradas pelos profissionais que pretendem aplicar o método de "moldagem virtual". Conclusão: os equipamentos avaliados apresentam claras vantagens e desvantagens, que precisam ser consideradas pelos compradores em potencial dessa tecnologia. Relevância clínica: este artigo visa informar profissionais da área de Odontologia sobre as principais características e limitações do escaneamento intraoral nas áreas de Ortodontia, Prótese, Implantodontia e Cirurgia Ortognática.(AU)

Introduction: the use of intraoral scanners for teeth and dental arches reproduction in dentistry has become a new trend in the last decade. The images acquired are used in diagnosis and treatment planning of clinical cases, but they can also be printed, materialized in dental casts and dies, depending on the specific needs. Materials and Methods: a review of the literature was conducted using PubMed and Google Scholars. Thirty articles were found to be the most relevant and selected to be included in this literature review. Results: techniques, equipment, and commercial brands, including their advantages and disadvantages, have been introduced to the dental community. From the technical-scientific point of view, the accuracy and precision of scanning and printing processes are the main demands, and must be carefully tested. From the clinical standpoint, easiness of operation, need of contrast agent (i.e, titanium dioxide powder), the size and weight of equipment wand, infection control, scanning time, and patient comfort are the most relevant factors. From the commercial point of view, equipment availability, price and available assistance are the main conditions to be considered by the professionals interested in the "virtual impression" method. Conclusion: apparatus es described in this literature review present clear advantages and disadvantages, which need to be taken into consideration by potential buyers of this technology. Clinical relevance: the article intents to inform dental professionals about the main features and limitations of the intraoral scanning in Orthodontics, Prosthodontics, Implantodontics and Oral Maxillofacial Surgery..(AU)

Extrações ortodônticas de pré-molares e seus efeitos nas vias aéreas respiratórias superiores ­ revisão da literatura / Orthodontic premolar extractions and their effects on oropharyngeal airway ­ literature review

Extrações de pré-molares por indicação ortodôntica e seus efeitos nas vias aéreas respiratórias superiores (VARS) têm sido objeto de constante investigação e controvérsia nos últimos anos. O objetivo deste estudo é identificar, através de uma busca literária, as referências mais relevantes sobre o assunto. Utilizando as bases de dados PubMed (http://www.ncbi.nlm.nih.gov/pubmed), de Janeiro de 1966 a Junho e 2016, e Google Acadêmico (http://scholar.google.com), foi conduzida uma revisão de literatura. Seis indexadores (airway, pharynx, bicuspid, premolar, incisor retraction, e sleep apnea) foram utilizados. Somente os estudos clínicos em seres humanos que não apresentavam nenhum tipo de síndrome ou deficiência física foram incluídos. Uma pesquisa manual sobre a lista de referência bibliográfica de cada artigo selecionado foi adicionada. Potencialmente, vinte e oito artigos foram identificados e somente nove artigos atingiram os critérios propostos. Quatro artigos selecionados avaliaram as alterações em imagens 2D e cinco artigos em imagens 3D. Nenhum estudo clínico selecionado utilizou randomização. A quantidade de retração dos incisivos, bem como o tipo de avaliação (2D ou 3D), tiveram influências diferentes sobre as VARS. Pouca retração dos incisivos apresenta pouca ou nenhuma influência nas VARS. Concluiu-se que a extração de pré-molares não afeta as dimensões das VARS quando pequena retração dos incisivos é realizada. A falta de estudos clínicos randomizados e de avaliação da função respiratória como indicador de apneia obstrutiva do sono ­ AOS - (por exemplo, polissonografia) justificam inconsistências da literatura sobre possível relação entre extrações ortodônticas de pré-molares e VARS/AOS.(AU)

Premolar extractions, due to orthodontic treatment, and their effect on airways have been investigated frequently in the last few years and have shown inconsistencies. The current literature review aimed to show the best articles about the topic intending to clarify such inconsistencies. Two data base, PubMed (http://www.ncbi.nlm.nih.gov/pubmed), from January of 1966 to June of 2016, and Google Scholar (http://scholar.google.com) were used to access the literature. Six key words (airway, pharynx, bicuspid, premolar, incisor retraction, and sleep apnea) were used. Only clinical studies were selected. Studies with subjects presenting syndromes or physical deficiency were excluded. Checking the references from the potential studies also targeted to find articles of interest. Initially, 28 articles were selected but only nine met the stablished criteria. Four articles evaluated the changes using 2D images and five used 3D images. None of the studies was randomized. The amount of incisor retraction and the type of evaluation (2D or 3D) showed different influences on airway. Small retraction of the incisors had none or minor influence on airway. It was concluded that premolar extractions do not cause changes on airway dimensions when the incisors were slightly retracted. Lack of randomized clinical trials and the evaluation of breathing function as indicator of obstructive sleep apnea (i.e. polysomnography) justify inconsistencies in the literature relating orthodontic premolar extractions and airway. (AU)

Understanding the basis of space closure in Orthodontics for a more efficient orthodontic treatment.

INTRODUCTION: Space closure is one of the most challenging processes in Orthodontics and requires a solid comprehension of biomechanics in order to avoid undesirable side effects. Understanding the biomechanical basis of space closure better enables clinicians to determine anchorage and treatment options. In spite of the variety of appliance designs, space closure can be performed by means of friction or frictionless mechanics, and each technique has its advantages and disadvantages. Friction mechanics or sliding mechanics is attractive because of its simplicity; the space site is closed by means of elastics or coil springs to provide force, and the brackets slide on the orthodontic archwire. On the other hand, frictionless mechanics uses loop bends to generate force to close the space site, allowing differential moments in the active and reactive units, leading to a less or more anchorage control, depending on the situation. OBJECTIVE: This article will discuss various theoretical aspects and methods of space closure based on biomechanical concepts.

Understanding the basis of space closure in Orthodontics for a more efficient orthodontic treatment

ABSTRACT Introduction: Space closure is one of the most challenging processes in Orthodontics and requires a solid comprehension of biomechanics in order to avoid undesirable side effects. Understanding the biomechanical basis of space closure better enables clinicians to determine anchorage and treatment options. In spite of the variety of appliance designs, space closure can be performed by means of friction or frictionless mechanics, and each technique has its advantages and disadvantages. Friction mechanics or sliding mechanics is attractive because of its simplicity; the space site is closed by means of elastics or coil springs to provide force, and the brackets slide on the orthodontic archwire. On the other hand, frictionless mechanics uses loop bends to generate force to close the space site, allowing differential moments in the active and reactive units, leading to a less or more anchorage control, depending on the situation. Objective: This article will discuss various theoretical aspects and methods of space closure based on biomechanical concepts.

RESUMO Introdução: O fechamento de espaços é um dos processos mais desafiadores na Ortodontia e requer uma compreensão sólida de conceitos biomecânicos, a fim de se evitar efeitos colaterais indesejáveis. Compreender o fundamento biomecânico do fechamento de espaços possibilita uma melhor definição das opções de ancoragem e tratamento, por parte dos clínicos. Apesar de haver uma variedade de desenhos de aparelhos ortodônticos, o fechamento de espaços pode ser realizado por meio da mecânica com atrito ou sem atrito, e cada técnica apresenta vantagens e desvantagens. A mecânica com atrito, ou mecânica de deslizamento, é atraente em virtude de sua facilidade, o espaço é fechado por meio do uso de elásticos ou molas helicoidais, que produzem força, fazendo com que os braquetes deslizem no arco ortodôntico. Por outro lado, a mecânica sem atrito se utiliza de dobras em alças para gerar força para fechar o espaço, possibilitando momentos diferenciais nas unidades ativa e reativa, induzindo a uma ancoragem mais ou menos controlada, dependendo da situação. Objetivo: o presente artigo discutirá vários aspectos teóricos e métodos de fechamento de espaços, baseando-se em conceitos biomecânicos.