A comparative evaluation of presurgical infant orthopedics of modified Grayson's technique with clear aligners incorporating a nasal elevator in patients with unilateral cleft lip and palate.

OBJECTIVE: To assess the differences between 2 methods of presurgical infant orthopedics: the modified Grayson's technique and a new technique using clear aligners in patients with complete unilateral cleft lip and palate. METHODS: For this prospective comparative cohort study, 30 patients were divided into 2 groups: group A (modified Grayson technique) and group B (clear aligner trays), with 15 patients each. Scanned cast measurements were taken before and after treatment and evaluated using an appropriate 3-dimensional software assessing treatment changes in the alveolus (eg, reduction of width between major and minor segment, angulation change of each respective segment [intragroup and intergroup, respectively]). This was supplemented with standardized anterioposterior, Worms-eye view, and profile photographs assessing changes in columellar angle, nostril width, height, nasolabial angle, and soft-tissue cleft gap. Furthermore, the number of visits for each patient group was also tabulated and assessed. The differences were compared using the independent t test and Mann-Whitney U test for the respective parameters. RESULTS: Groups A and B showed similar posttreatment changes, with no overt significant differences. However, there was a statistically significant difference in the number of visits (P <0.05), with group B having much lower visits to the center than group A. The posttreatment values matched previously established growth reference values. The analysis of photographic measurements showed improved nasal asymmetry in both groups without any significant difference. CONCLUSIONS: Because there was no difference in the treatment results between the 2 methods and a reduction in the number of required patient visits, presurgical infant orthopedics via clear aligners could pave the way for a more patient-efficient approach.

Evaluation of the three-dimensional (3D) position of cervical vertebrae in individuals with unilateral posterior crossbite.

OBJECTIVE: To evaluate the three-dimensional (3D) position of the cervical vertebrae of growing subjects with unilateral posterior crossbite (UPC). MATERIALS AND METHODS: In this cross-sectional study, cone beam computed tomography (CBCT) scans of 1455 patients were screened, and ultimately 58 scans (26 patients with UPC and 32 controls with normal occlusion) were included after imposing inclusion/exclusion criteria. Roll, yaw, and deviation of the geometric center of C1, C2, and C3 vertebrae were measured and compared between groups. A correlation between these parameters and different variables on mandibular positioning was also carried out. RESULTS: A statistically significant difference (p < 0.05) was observed between groups for the deviation of pogonium (Pog), mandibular plane roll, and C3 roll, and patients with UPC showed higher cant or deviation. A significant correlation was reported for the roll of C2 and C3 with the deviation of Pog, a roll of the occlusal plane, and roll of the mandibular plane (p < 0.05). The greater the deviation of the Pog to one side, the greater the roll of the vertebrae with this same side up. The same tendency was observed between the roll of the occlusal plane or the mandibular plane with the roll of these cervical vertebrae. CONCLUSIONS: There is a positive correlation between transverse occlusal changes and positional deviations of the cervical vertebrae, especially C2 and C3. CLINICAL RELEVANCE: The study results do not allow us to infer the clinical/functional consequences of these deviations, as well as if malocclusion's treatment would result in an improvement of intervertebral relationships.

The effects of corticotomy and piezocision in orthodontic canine retraction: a randomized controlled clinical trial.

BACKGROUND: The aims of this study were to evaluate the efficacy of alveolar corticotomy (AC) and piezocision (PZ) in accelerating maxillary canine retraction, and their effects on multiple bone remodeling expression in gingival crevicular fluid (GCF). A split-mouth, randomized controlled clinical trial was performed at the Department of Orthodontics of Pontifical Catholic University of Minas Gerais, Brazil. Eligibility criteria included orthodontic need for first maxillary premolars extractions, followed by canine retraction. Fifty-one adult patients were recruited and randomly assigned to 3 groups (allocation ratio 1:1:1). Random allocation of surgical or control interventions to each side of the maxillary arch was also conducted: G1 - AC × Control, G2 - PZ × Control, and G3 - AC × PZ. Both the definition of the group and the decision of the experimental or control sides were randomized by the software. Intraoral digital scans were performed before, 7 and 14 days after the beginning of canine retraction, and subsequently, at every 14 days until a maximum period of 6 months. GCF samples were collected before, and 1, 2, 4, 8, and 12 weeks. The primary outcome consisted in the cumulative distal movement of the canines and was measured by digital model superimposition. The secondary outcome consisted in GCF bone remodeling samples that were quantified in a multiplex immunoassay. The measurements examinator was properly blinded. RESULTS: Forty-seven patients, 19 males and 28 females, were analyzed (mean age 20.72, SD = 6.66, range 15 to 38). Statistically significant differences in canine distal movement between AC and control in G1 were not observed (p > 0.05). In G2, PZ showed lower cumulative incisal and cervical measurements than control from the 2nd to the 24th week (p < 0.05). In G3, PZ showed a lower cumulative incisal and cervical measurements than AC from the16th to the 24th week (p < 0.05). In all groups, differences on biomarkers expression occurred at specific timepoints (p < 0.05), but a distinct pattern was not observed. CONCLUSIONS: AC and PZ were not effective to accelerate maxillary canine retraction and did not induce a distinct pattern of biomarker expression. TRIAL REGISTRATION: NCT03089996 . Registered 24 March 2017 - Registered.

Mini Hyrax vs Hyrax expanders in the rapid palatal expansion in adolescents with posterior crossbite: a randomized controlled clinical trial.

PURPOSE: The aim of this study was to compare the dental effects, impact on quality of life, and pain perception of adolescents wearing Mini Hyrax and Hyrax expanders in rapid palatal expansion. METHODS: Thirty-four adolescents aged 11 to 16 years, with maxillary transverse deficiency (unilateral or bilateral posterior crossbite), were randomly allocated into two groups, Mini Hyrax group and Hyrax group (1:1 ratio). Dental effects were evaluated by digitally superimposed pretreatment and postretention three-dimensional intraoral scans on the palatal rugaes using the software 3DSlicer. Impact on quality of life was assessed with the OHIP-14 questionnaire applied in the pretreatment, posttreatment and postretention. Visual analog scale was applied 24, 48, and 72 h and 7 days after the first activation of the expander. RESULTS: Thirty of the 34 adolescents recruited completed the study. There were no statistically significant differences in dentoalveolar effects between groups. OHIP-14 scores across time among Mini Hyrax wearers were similar to those of the Hyrax wearers. The inter-group comparisons showed no difference between groups with respect to the OHIP-14 scores in posttreatment and postretention (p > 0.05). There were no differences in pain perception between groups. Considering intra-group comparison, the reduction in pain perception among adolescents in the Mini Hyrax group was gradual. Among adolescents in the Hyrax group, a statistically significant reduction between 48 and 72 h was observed. CONCLUSION: There were no significant differences in dental effects, impact on quality of life and pain perception between adolescents wearing Mini Hyrax and Hyrax expanders in rapid palatal expansion.

Mandibular ramus height and condyle distance asymmetries in individuals with different facial growth patterns: a cone-beam computed tomography study.

PURPOSE: This study aimed to quantify mandibular ramus height and condylar distances asymmetry indexes in adult patients with different vertical facial growth pattern using Cone Beam computed tomography (CBCT). METHODS: An observational cross-sectional study was conducted by using CBCT of 159 patients (mean age 26.36 ± 5.32 years). Vistadent 3D® software was used to determine the facial pattern in 3 groups (N = 53): hypodivergent, normodivergent and hyperdivergent-by Ricketts VERT index. Mandibular ramus height and the condylar linear distance in relation to the median sagittal plane were evaluated. The asymmetry index was calculated considering the right and left sides. Data were analyzed by generalized linear models and Tukey post-hoc test (α = 0.05). RESULTS: Significantly lower values were found for the left and right mandibular ramus height in the hyperdivergent skeletal pattern (P < 0.05). There was no statistically significant difference for condylar and intercondylar distances among the facial groups (P > 0.05). Asymmetry indexes (mandibular ramus height and condylar distance) were similar, and no statistically significant differences were found among the skeletal patterns. In most subjects, the severity of mandibular ramus height asymmetry varied from light to not clinically significant independently of the facial type. CONCLUSION: The findings suggest that vertical facial growth pattern not affected the asymmetry index of mandibular ramus height and the intercondylar distance. The results also demonstrated significantly shorter mandibular ramus height for the hyperdivergent skeletal pattern individuals.

Reproducibility of digital indirect bonding technique using three-dimensional (3D) models and 3D-printed transfer trays.

OBJECTIVE: To evaluate the reproducibility of digital tray transfer fit on digital indirect bonding by analyzing the differences in bracket positions. MATERIALS AND METHODS: Digital indirect bonding was performed by positioning brackets on digital models superimposed by tomography using Ortho Analyzer (3Shape) software. Thirty-three orthodontists performed indirect bonding on prototyped models of the same malocclusion using prototyped transfer trays for two types of brackets (MiniSprint Roth and BioQuick self-ligating). The models with brackets were scanned using an intraoral scanner (Trios, 3Shape). Superimpositions were made between the digital models obtained after indirect bonding and those from the original virtual setup. To analyze the differences in bracket positions, three planes were examined for each bracket: vertical, horizontal, and angulation. Three orthodontists repeated indirect bonding after 15 days, and Bland-Altman plots and intraclass correlation coefficients were used to evaluate inter- and intraevaluator reproducibility and reliability, respectively. Repeated-measures analysis of variance (ANOVA) was used to analyze the differences between bracket positions, and multivariate ANOVA was used to evaluate the influence of orthodontists' experience on the results. RESULTS: Differences between bracket positions were not statistically significant, except mesial-distal discrepancies in the BioQuick group (P = .016). However, differences were not clinically significant (horizontal varied from 0.04 to 0.13 mm; angulation, 0.45° to 2.03°). There was no significant influence of orthodontist experience and years of clinical practice on bracket positions (P = .314 and P = .158). The reproducibility among orthodontists was confirmed. CONCLUSIONS: The reproducibility of digital indirect bonding was confirmed in terms of bracket positions using three-dimensional printed transfer trays.

OrthoAligner "NAM": A Case Series of Presurgical Infant Orthopedics (PSIO) Using Clear Aligners.

Presurgical infant orthopedics (PSIO) is done to reduce the size of the cleft defect along with improving the arch alignment and nasolabial aesthetics in patients with cleft lip and palate, leading to an improvement of nasolabial aesthetics allowing for a tidier and more aesthetic reparative procedure and postsurgical scar. Since the 2000s, clear aligners have slowly and steadily treaded their way as an acceptable orthodontic modality, with their usage and acceptability increasing considerably over the past decade. Thus, from the knowledge gathered in its 10 years working with 3-dimensional (3-D) diagnosis, treatment planning, and 3-D Printing services, Compass 3D (Belo Horizonte, Brazil) developed the OrthoAligner NAM system. This case series highlights one of the world's first documented cases of PSIO treated with a series of clear aligners.

Comparison of the accuracy of virtual and direct bonding of orthodontic accessories.

INTRODUCTION: Conventional direct and indirect bonding techniques fail to obtain the ideal bracket position. OBJECTIVE: To compare the accuracy of virtual and conventional direct bonding of orthodontic accessories. METHODS: A single virtual configuration (dental mannequin with Class I malocclusion) served as basis for generating the reference model (treated virtually) and the intervention models (10 digital models and 10 solid models, obtained by means of prototyping). A total of 560 teeth were then equally distributed between a group of orthodontists (Group I, direct bonding; and Group II, virtual bonding), working in two different time intervals. The individual positions of the accessories were measured after three-dimensional superimposition with customized software. The Student's-t test for paired samples, and Chi-square tests were used for statistical analysis, both at the level of significance of 5%. RESULTS: In comparison of the errors in raw values, there were significant differences only in the vertical (p< 0.001) and horizontal dimensions (p< 0.001). Considering the groups of ranges by clinical limits of the deviations, these differences were significant in the three dimensions, vertical (p< 0.001), horizontal (p= 0.044) and angular (p= 0.044). CONCLUSION: Virtual bonding made it possible to obtain more precise/accurate positioning of the orthodontic accessories. The potential accuracy of this method brings new perspectives to refining the indirect bonding protocols.

Comparison of maxillomandibular asymmetries in adult patients presenting different sagittal jaw relationships.

OBJECTIVE: The present study aims at using cone beam computed tomography (CBCT) to analyze the maxillomandibular characteristics present in adults with mandibular asymmetries and different sagittal jaw relationships. METHODS: 360 patients were selected and divided into three groups (Class I, Class II, and Class III), with 120 individuals per group. The groups were then subdivided according to the intensity of lateral deviation of the gnathion point, into: 1) relative symmetry, 2) moderate asymmetry, and 3) severe asymmetry. Three planes of reference were established in the CBCT images and several measurements were taken to compare the bilateral skeletal differences between the intensities of asymmetry for the different sagittal jaw relationships. RESULTS: When the groups were compared by the intensity of asymmetry, significant differences among patients with relative symmetry and moderate to severe asymmetry were found. This was especially noticed for severe asymmetry, suggesting that the deviation of the chin did not constitute the only morphological alteration for these patients, especially because a series of measurements showed significant bilateral differences. When comparing sagittal jaw relationships, the only significant finding was the vertical positioning of the gonion between Class II and III patients with severe asymmetry. CONCLUSIONS: When comparing the three sagittal jaw relationships with the same intensity of asymmetry, most maxillofacial aspects were quite similar. The only difference was found for patients with severe asymmetry, as the individuals with Class II showed greater bilateral difference in the vertical positioning of the gonion, when compared to patients with Class III.

Comparison of maxillomandibular asymmetries in adult patients presenting different sagittal jaw relationships

ABSTRACT Objective: The present study aims at using cone beam computed tomography (CBCT) to analyze the maxillomandibular characteristics present in adults with mandibular asymmetries and different sagittal jaw relationships. Methods: 360 patients were selected and divided into three groups (Class I, Class II, and Class III), with 120 individuals per group. The groups were then subdivided according to the intensity of lateral deviation of the gnathion point, into: 1) relative symmetry, 2) moderate asymmetry, and 3) severe asymmetry. Three planes of reference were established in the CBCT images and several measurements were taken to compare the bilateral skeletal differences between the intensities of asymmetry for the different sagittal jaw relationships. Results: When the groups were compared by the intensity of asymmetry, significant differences among patients with relative symmetry and moderate to severe asymmetry were found. This was especially noticed for severe asymmetry, suggesting that the deviation of the chin did not constitute the only morphological alteration for these patients, especially because a series of measurements showed significant bilateral differences. When comparing sagittal jaw relationships, the only significant finding was the vertical positioning of the gonion between Class II and III patients with severe asymmetry. Conclusions: When comparing the three sagittal jaw relationships with the same intensity of asymmetry, most maxillofacial aspects were quite similar. The only difference was found for patients with severe asymmetry, as the individuals with Class II showed greater bilateral difference in the vertical positioning of the gonion, when compared to patients with Class III.

RESUMO Objetivo: o presente estudo teve como objetivo analisar, por meio de tomografia computadorizada de feixe cônico (TCFC), as características esqueléticas maxilomandibulares presentes em adultos com diferentes graus de assimetria mandibular e diferentes relações esqueléticas sagitais. Métodos: foram selecionados 360 pacientes, os quais foram divididos em três grupos, com 120 indivíduos cada (Classe I, Classe II e Classe III). Cada grupo foi, ainda, subdividido de acordo com a intensidade do desvio lateral do mento: 1) simetria relativa; 2) assimetria moderada; e 3) assimetria severa. Três planos de referência foram estabelecidos nas imagens de TCFC e várias medidas foram realizadas, sendo comparadas as diferenças esqueléticas bilaterais existentes entre os graus de assimetria em cada grupo, nas diferentes relações esqueléticas sagitais. Resultados: quando comparados os grupos pelos graus de assimetria, existiram diferenças significativas entre pacientes com simetria relativa e pacientes assimétricos, especialmente para a assimetria severa, sugerindo que o desvio do mento não constitui a única alteração morfológica para esses pacientes, especialmente porque uma série de medidas apresentou diferenças bilaterais significativas. Quando comparadas as relações sagitais entre si, não foram encontradas diferenças significativas, exceto para o posicionamento vertical do gônio entre as Classe II e III na assimetria severa. Conclusão: ao comparar a mesma intensidade de assimetria entre as diferentes relações esqueléticas sagitais, pouca diferença pôde ser observada. A única diferença encontrada foi em pacientes com assimetria severa, na qual os indivíduos com Classe II apresentaram maior diferença bilateral no posicionamento vertical do gônio, quando comparados àqueles com Classe III.

Comparison of the accuracy of virtual and direct bonding of orthodontic accessories

ABSTRACT Introduction: Conventional direct and indirect bonding techniques fail to obtain the ideal bracket position. Objective: To compare the accuracy of virtual and conventional direct bonding of orthodontic accessories. Methods: A single virtual configuration (dental mannequin with Class I malocclusion) served as basis for generating the reference model (treated virtually) and the intervention models (10 digital models and 10 solid models, obtained by means of prototyping). A total of 560 teeth were then equally distributed between a group of orthodontists (Group I, direct bonding; and Group II, virtual bonding), working in two different time intervals. The individual positions of the accessories were measured after three-dimensional superimposition with customized software. The Student's-t test for paired samples, and Chi-square tests were used for statistical analysis, both at the level of significance of 5%. Results: In comparison of the errors in raw values, there were significant differences only in the vertical (p< 0.001) and horizontal dimensions (p< 0.001). Considering the groups of ranges by clinical limits of the deviations, these differences were significant in the three dimensions, vertical (p< 0.001), horizontal (p= 0.044) and angular (p= 0.044). Conclusion: Virtual bonding made it possible to obtain more precise/accurate positioning of the orthodontic accessories. The potential accuracy of this method brings new perspectives to refining the indirect bonding protocols.

RESUMO Introdução: técnicas convencionais, diretas ou indiretas, de colagem de acessórios ortodônticos falham em obter a posição ideal desses. Objetivo: comparar a acurácia da colagem virtual e da colagem direta de acessórios ortodônticos por vestibular. Métodos: uma configuração virtual única (modelo de manequim com Classe I dentária) serviu como base para a geração do modelo de referência (tratado virtualmente) e dos modelos de intervenção (10 modelos digitais e 10 modelos sólidos, obtidos por prototipagem). Quinhentos e sessenta dentes foram, então, igualmente distribuídos, em dois tempos distintos, entre um grupo de ortodontistas (Grupo I: colagem direta; Grupo II: colagem virtual). As posições individuais dos acessórios foram aferidas após a sobreposição tridimensional de modelos, em software customizado. O testet de Student para amostras pareadas e o teste Qui-quadrado foram usados para a análise estatística, ambos com nível de significância de 5%. Resultados: na comparação dos erros, em valores brutos, houve diferenças significativas apenas nas dimensões vertical (p< 0,001) e horizontal (p < 0,001). Considerando-se o agrupamento de faixas por limites clínicos dos desvios, essas diferenças foram significativas nas três dimensões: vertical (p < 0,001), horizontal (p = 0,044) e angular (p = 0,044). Conclusão: a colagem virtual possibilitou um posicionamento mais preciso dos acessórios ortodônticos. Seu potencial de precisão traz novas perspectivas ao refinamento dos protocolos indiretos.

Is there an asymmetry of the condylar and coronoid processes of the mandible in individuals with unilateral crossbite?

OBJECTIVES: To evaluate if there is a true skeletal asymmetry of the condylar and coronoid processes of the mandible in growing individuals with unilateral posterior crossbite (UPC) either functional or not. MATERIALS AND METHODS: This cross-sectional study screened a total of 1120 cone beam computed tomography (CBCT) scans based on inclusion and exclusion criteria. The final sample comprised 20 CBCT images of individuals with UPC and 19 CBCT images of individuals without transverse malocclusion. The lengths of the condylar and coronoid processes were measured to evaluate asymmetry, as well as the magnitude of the mandibular lateral deviation in the UPC group. RESULTS: There was a significant difference between the lengths of the affected and nonaffected sides of the coronoid processes in the UPC group (P < .01). The same was not observed in the condyle in the UPC group (P > .05). There were no significant differences between the groups (P > .05). CONCLUSIONS: Although no differences in the condyle were observed, the coronoid process was asymmetric in individuals with UPC. However, this asymmetry was not considered to be clinically significant.

Three-dimensional evaluation of craniofacial characteristics related to mandibular asymmetries in skeletal Class I patients.

INTRODUCTION: Our objective was to analyze the characteristics that affect skeletal Class I adults with mandibular asymmetries using cone-beam computerized tomography. METHODS: The sample included cone-beam computerized tomography images of 120 subjects. Asymmetry was determined by the deviation of gnathion from the midsagittal plane and classified as relative symmetry, moderate asymmetry, or severe asymmetry. Maxillary and mandibular measurements were made, and the differences between the contralateral side and the deviated side were evaluated, as well as the differences between the categories of asymmetry. RESULTS: For patients with moderate asymmetry, there were significant differences between the contralateral and deviated sides for some measuments in the transverse and vertical planes. For those with severe asymmetry, statistically significant differences were found between the sides for all measurements, except for the measuments that evaluated the position of the mandibular condyle in the transverse and sagittal directions. Furthermore, a strong correlation was found in patients with severe asymmetry, between the deviation of the mandibular dental midline and the lateral displacement of gnathion. CONCLUSIONS: Patients with relative symmetry had a bilateral balance, whereas those with moderate and severe asymmetries showed several skeletal imbalances. A great deviation of the mandibular dental midline may indicate severe skeletal asymmetry in Class I adults.

Prevalence and Associated Factors of Mandibular Asymmetry in an Adult Population.

BACKGROUND: This study aimed to estimate the prevalence of mandibular asymmetry and investigate some associated factors. METHODS: Tomographic images of 952 individuals aged from 18 to 75 years old were analyzed. The investigated outcome was mandibular asymmetry. The explanatory variables included gender, age, absence of posterior teeth, and sagittal jaw relationship of the individuals. Statistical analyses included the chi-squared and the Poisson regression with robust variance. RESULTS: Mandibular asymmetry was present in 17.4% of the sample (95% confidence interval 15.2-20.0). In the bivariate analysis, there was an association between the variables age and sagittal jaw relationship with mandibular asymmetry (P = 0.026 and P = 0.018, respectively). However, in the adjusted regression model, the association with age was not maintained, occurring only an association between sagittal jaw relationship and mandibular asymmetry (P = 0.045), with significant difference between individuals with skeletal Class II and skeletal Class III (P = 0.013). CONCLUSION: Mandibular asymmetry was not independently associated with sex, age, or absence of posterior teeth. The only verified independent association was between mandibular asymmetry and sagittal jaw relationship.

Maxillofacial Features Related to Mandibular Asymmetries in Skeletal Class III Patients.

PURPOSE: To analyze components related to different degrees of mandibular asymmetry in adults with skeletal Class III using cone-beam computed tomographic (CBCT) images. MATERIALS AND METHODS: CBCT images from 138 patients were analyzed. Asymmetry was determined by the deviation of the gnathion point in relation to the midsagittal plane and classified as relative symmetry, moderate mandibular asymmetry, or severe mandibular asymmetry. Several maxillary and mandibular measurements were used to compare different degrees of mandibular asymmetry and the difference between measurements of the contralateral and deviated sides. RESULTS: For patients with moderate and severe mandibular asymmetry, there were statistically relevant differences between bilateral measurements of the sagittal position of the condylar heads, the transverse and sagittal positioning of the gonion, ramus height, and mandibular body length, the transverse and vertical positioning of the jugale point, including a vertical positioning of the gonion only for severe asymmetry. In patients with severe mandibular asymmetry, there was a highly relevant correlation of gnathion lateral displacement with lower dental midline displacement and with the difference in height of the mandibular rami between the deviated and contralateral sides. CONCLUSION: In patients with skeletal Class III, not only lateral displacement of the menton but also a series of morphologic changes differed markedly for each degree of mandibular asymmetry.

Correlation of Crown Angulation and Inclination Based on Occlusal, Camper's, and Frankfurt Planes Using Digital Models.

This study provided the measures of crown angulations and inclinations which were evaluated using 3D cephalometry. This study was conducted to demonstrate the relationship between the main planes : Camper's, Frankfurt, and occlusalplanes for guiding the positioning ofthe skull and orthodontic planning.

Is there an association between skeletal asymmetry and tooth absence?

INTRODUCTION: Facial skeletal asymmetry is commonly found in humans and its main characteristic is menton deviation. The literature suggests that occlusal and masticatory problems arising from tooth absence could be related to the development of such asymmetries. OBJECTIVE: The aim of this cross-sectional study was to estimate the prevalence of mandibular skeletal asymmetries and to investigate its association with posterior tooth absences. METHODS: Tomographic images of 952 individuals aged from 18 to 75 years old were used. Asymmetry was the analyzed outcome, and it was categorized into three groups according to gnathion displacement in relation to the midsagittal plane (relative symmetry, moderate asymmetry, and severe asymmetry). Patients were sorted by the presence of all posterior teeth, unilateral posterior tooth absence, or bilateral posterior tooth absence. Chi-square test with a significance level of 5% was used to verify the association between posterior tooth absence and asymmetry. RESULTS: Results show relative symmetry present in 55.3% of the sample, as well as the prevalence of 27.3% for moderate mandibular asymmetry and 17.4% for severe asymmetry. Moderate and severe mandibular asymmetries occurred in a higher proportion in patients with unilateral posterior tooth absence. However, there was no statistically significant difference between the analyzed groups (p = 0.691). CONCLUSIONS: In this study, mandibular asymmetries did not present any association with the absence of teeth on the posterior area of the arch.

Is there an association between skeletal asymmetry and tooth absence?

ABSTRACT Introduction: Facial skeletal asymmetry is commonly found in humans and its main characteristic is menton deviation. The literature suggests that occlusal and masticatory problems arising from tooth absence could be related to the development of such asymmetries. Objective: The aim of this cross-sectional study was to estimate the prevalence of mandibular skeletal asymmetries and to investigate its association with posterior tooth absences. Methods: Tomographic images of 952 individuals aged from 18 to 75 years old were used. Asymmetry was the analyzed outcome, and it was categorized into three groups according to gnathion displacement in relation to the midsagittal plane (relative symmetry, moderate asymmetry, and severe asymmetry). Patients were sorted by the presence of all posterior teeth, unilateral posterior tooth absence, or bilateral posterior tooth absence. Chi-square test with a significance level of 5% was used to verify the association between posterior tooth absence and asymmetry. Results: Results show relative symmetry present in 55.3% of the sample, as well as the prevalence of 27.3% for moderate mandibular asymmetry and 17.4% for severe asymmetry. Moderate and severe mandibular asymmetries occurred in a higher proportion in patients with unilateral posterior tooth absence. However, there was no statistically significant difference between the analyzed groups (p = 0.691). Conclusions: In this study, mandibular asymmetries did not present any association with the absence of teeth on the posterior area of the arch.

RESUMO Introdução: a assimetria esquelética facial é comum em humanos, sendo o desvio do mento sua principal característica. É sugerido, na literatura, que problemas oclusais e mastigatórios advindos das ausências dentárias teriam relação com o desenvolvimento dessas assimetrias. Objetivo: o objetivo deste estudo transversal foi estimar a prevalência de assimetrias esqueléticas mandibulares e investigar sua associação com as ausências dentárias posteriores. Métodos: foram utilizadas imagens tomográficas de 952 indivíduos, com idade entre 18 e 75 anos. A assimetria foi o desfecho analisado, sendo categorizada em três grupos, de acordo com o desvio do gnátio em relação ao plano sagital mediano: simetria relativa, assimetria moderada e assimetria severa. Os indivíduos foram agrupados segundo a presença de todos os dentes posteriores, ausência dentária posterior unilateral ou ausência dentária posterior bilateral. Para verificar a associação entre a ausência dentária posterior e a assimetria, foi utilizado o teste Χ2, ao nível de significância de 5%. Resultados: os resultados mostraram que a simetria relativa esteve presente em 55,3% da amostra, bem como uma prevalência de 27,3% para a assimetria mandibular moderada e 17,4% para assimetria severa. As assimetrias mandibulares moderada e severa ocorreram em maior proporção nos indivíduos com ausência dentária posterior unilateral; entretanto, não houve diferença estatisticamente significativa entre os grupos (p = 0,691). Conclusões: nesse estudo, as assimetrias mandibulares em adultos não apresentaram associação com a ausência de dentes na região posterior da arcada dentária.

Analysis of the maxillary dental arch after rapid maxillary expansion in patients with unilateral complete cleft lip and palate.

INTRODUCTION: Although rapid maxillary expansion has been extensively studied in noncleft patients, scarce evidence of maxillary effects is found for patients with oral clefts. Our objective was to evaluate the dentoalveolar effects of rapid maxillary expansion in children with unilateral complete cleft lip and palate compared with noncleft patients. METHODS: The experimental group included 25 patients with unilateral complete cleft lip and palate and posterior crossbite (9 girls, 16 boys; mean age, 10.6 years). The control group comprised 27 noncleft patients with posterior crossbite (14 boys, 13 girls; mean age, 9.1 years). The experimental group had lip and palate repairs at 3 and 12 months of age, respectively, and maxillary expansion was indicated before a secondary alveolar bone graft. Digital dental models were obtained immediately before expansion and 6 months after expansion with a laser scanner. Canine and posterior tooth inclinations, transversal widths, arch perimeters, arch lengths, palatal depths, and palatal volumes were digitally measured. The paired t test was used for interphase comparisons, and the independent t test was used for intergroup comparisons (P <0.05). RESULTS: In the experimental group, expansion produced buccal tipping of the canines and posterior teeth and significant increases of all maxillary transverse measurements, arch perimeter, palatal volumes, and palatal depths; only arch lengths decreased. No differences were observed between the groups for any measurement, except for intermolar distance. CONCLUSIONS: Rapid maxillary expansion produced similar changes in the patients with unilateral complete cleft lip and palate compared with the noncleft patients except for arch length and palatal depth that decreased after expansion in the children with oral clefts.