Asymmetry in Class II subdivision malocclusion: Assessment based on 3D surface models.

INTRODUCTION: There is currently no consensus in the literature whether the aetiology of a Class II subdivision is dental, skeletal or both. The aim of this study was to identify and quantify skeletal and dental asymmetries in Class II subdivision malocclusions. METHODS: CBCTs from 33 Class II subdivision malocclusion patients were used to construct 3D volumetric label maps. Eighteen landmarks were identified. The original scan and associated 3D volumetric label map were mirrored. Registration of the original and mirrored images relative to the anterior cranial base, maxilla and mandible were performed. Surface models were generated, and 3D differences were quantified. Statistical analysis was performed. RESULTS: Anterior cranial base registration showed significant differences for fossa vertical difference, fossa roll, mandibular yaw, mandibular lateral displacement and lower midline displacement. Regional registrations showed significant differences for antero-posterior (A-P) mandibular length, maxillary roll, A-P maxillary first molar position, maxillary first molar yaw and maxillary first molar roll. Class II subdivision patients also show an asymmetric mandibular length as well as an asymmetric gonial angle. Moderate correlations were found between the A-P molar relationship and fossa A-P difference, mandibular first molar A-P difference, maxillary first molar A-P difference and maxillary first molar yaw. CONCLUSIONS: This study suggests that Class II subdivisions can result from both significant skeletal and dental factors. Skeletal factors include a shorter mandible as well as posterior and higher displacement of the fossa on the Class II side, resulting in mandibular yaw. Dental factors include maxillary and mandibular first molar antero-posterior asymmetry.

Facilitating Direct Bonding for Lingual Retainers.

Directly bonded lingual retainers are not always easy because the available techniques do not keep the wire totally stable in position and there is risk of moist contamination. Indirect methods help to keep a moist-free environment and reduce chair time but have other drawbacks, such as lack of control over the composite placement leading to adhesive-tooth failure or undesirable flow of adhesive to gingival embrasures. The purpose of this report is to show a direct bonding method, helped by a laboratory made acrylic guide, which has benefits of direct and indirect techniques.

Prediction of 3-dimensional pharyngeal airway changes after orthognathic surgery: a preliminary study.

INTRODUCTION: Recent studies have shown some contradictory results when evaluating the consequences of orthodontic-surgical treatments on the pharyngeal airway. Therefore, the purpose of this study was to correlate the amount of jaw displacement with the volume variation and the minimal cross-sectional area of the pharyngeal airway. A comparison was made between the correlations with the percentage and the absolute values of the measurement variations. METHODS: Forty-two patients were divided into 2 groups according to the kind of orthognathic surgery that they had undergone. Group 1 had 22 subjects who had undergone maxillary advancement associated with mandibular setback, and group 2 had 20 patients who had undergone maxillomandibular advancement. The pharyngeal airway was divided into the upper segment and the lower segment, and the sum of these volumetric measures resulted in the total volume. The maxillary and mandibular displacements were assessed using closest point iteration after a voxel-wise cone-beam computed tomography superimposition. Hence, jaw displacements were correlated, using Pearson's correlation and linear regression analysis, to the volume variations of the pharyngeal airway (first time separately and then both groups together) and to the minimal cross-sectional area variation. RESULTS: The strongest correlation found was between maxillary displacement and the upper segment in group 2 (r = 0.898, R(2) = 0.888; P ≤0.001). With the groups' data combined, the variables mandibular displacement and the lower segment showed a linear correlation (r = 0.921, R(2) = 0.914; P ≤0.001). Maxillary displacement showed a strong positive correlation with the minimal cross-sectional area variation in group 2 (r = 0.710, R(2) = 0.604; P ≤0.01). CONCLUSIONS: Correlations with the percentage values were substantially stronger than the correlations with the absolute values. Stronger positive correlations were found between the jaw's displacement and the volume variation of the volume segment that was closer to it in both kinds of surgeries. Only the maxillary displacement is a reliable predictor of the minimal cross-sectional area variation after maxillomandibular advancement.

Can cone-beam computed tomography superimposition help orthodontists better understand relapse in surgical patients?

This case report describes the interdisciplinary treatment of a 19-year-old Brazilian man with a Class I malocclusion, a hyperdivergent profile, an anterior open bite, and signs of temporomandibular joint internal derangement. The treatment plan included evaluation with a temporomandibular joint specialist and a rheumatologist, orthodontic appliances, and maxillomandibular surgical advancement with counterclockwise rotation. Cone-beam computed tomography images were taken before and after surgery at different times and superimposed at the cranial base to assess the changes after orthognathic surgery and to monitor quantitatively the internal derangement of the temporomandibular joints and surgical relapse. Our protocol can improve the orthodontist's understanding of surgical instability, demonstrate the clinical value of cone-beam computed tomography analysis beyond the multiplanar reconstruction, and guide patient management for the best outcome possible.

Prevalence of malocclusion in public school students in the mixed dentition phase and its association with early loss of deciduous teeth.

OBJECTIVE: To determine the prevalence of malocclusion and its association with the early loss of deciduous teeth and other factors in children in the mixed dentition phase, aged six to eight years, enrolled in public schools in southern Brazil. METHODS: A cross-sectional study was conducted with a representative sample of 528 children from municipal public schools in 2009. Data collection involved a clinical examination for the determination of early tooth loss, dental caries, tongue pressure and malocclusion (outcome), as well as the administration of a questionnaire. Poisson regression analysis with robust variance was used to model the association between malocclusion and the independent variables. RESULTS: The prevalence of malocclusion and early tooth loss was 69.1% and 21.8%, respectively. In the raw data analysis, malocclusion was associated with age, early tooth loss, dental caries and tongue pressure. After the adjustment, the likelihood of malocclusion was greater among children older than eight years, those who exerted tongue pressure on the teeth and those with early tooth loss. The likelihood of malocclusion was 24% greater among children with early tooth loss, compared to those without tooth loss. CONCLUSION: The early loss of deciduous teeth was associated with the occurrence of malocclusion in the children studied.

Amblyomma sculptum Salivary Protease Inhibitors as Potential Anti-Tick Vaccines.

Amblyomma sculptum is the main tick associated with human bites in Brazil and the main vector of Rickettsia rickettsii, the causative agent of the most severe form of Brazilian spotted fever. Molecules produced in the salivary glands are directly related to feeding success and vector competence. In the present study, we identified sequences of A. sculptum salivary proteins that may be involved in hematophagy and selected three proteins that underwent functional characterization and evaluation as vaccine antigens. Among the three proteins selected, one contained a Kunitz_bovine pancreatic trypsin inhibitor domain (named AsKunitz) and the other two belonged to the 8.9 kDa and basic tail families of tick salivary proteins (named As8.9kDa and AsBasicTail). Expression of the messenger RNA (mRNA) encoding all three proteins was detected in the larvae, nymphs, and females at basal levels in unfed ticks and the expression levels increased after the start of feeding. Recombinant proteins rAs8.9kDa and rAsBasicTail inhibited the enzymatic activity of factor Xa, thrombin, and trypsin, whereas rAsKunitz inhibited only thrombin activity. All three recombinant proteins inhibited the hemolysis of both the classical and alternative pathways; this is the first description of tick members of the Kunitz and 8.9kDa families being inhibitors of the classical complement pathway. Mice immunization with recombinant proteins caused efficacies against A. sculptum females from 59.4% with rAsBasicTail immunization to more than 85% by immunization with rAsKunitz and rAs8.9kDa. The mortality of nymphs fed on immunized mice reached 70-100%. Therefore, all three proteins are potential antigens with the possibility of becoming a new tool in the control of A. sculptum.

Three-dimensional stability analysis of maxillomandibular advancement surgery with and without articular disc repositioning.

This retrospective cohort study aimed to assess, three-dimensionally, mandible and maxilla changes following maxillomandibular advancement (MMA), with and without repositioning of TMJ articular discs. The sample comprised cone-beam computed tomography data from 32 subjects: group 1 (n = 12) without disc displacement and group 2 (n = 20) with bilateral disc repositioning. An automatic cranial base superimposition method was used to register the images at three time points: T1 (preoperative), T2 (postoperative), and T3 (at least 11 months follow-up). To assess surgical changes (T2-T1) and adaptive responses (T3-T2), the images were compared quantitatively and qualitatively using the shape correspondence method. The results showed that surgical displacements were similar in both groups for all the regions of interest except the condyles, which moved in opposite directions - group 1 to superior and posterior positions, and group 2 to inferior and anterior positions. For adaptive responses, we observed high individual variability, with lower variability in group 2. Sagittal relapse was similar in both groups. In conclusion, there were no significant differences in skeletal stability between the two groups. The maxillomandibular advancement surgeries, with rotation of the occlusal plane, had stable results for both groups immediately after surgery and at 1-year follow-up.

Inhibition of the complement system by saliva of Anopheles (Nyssorhynchus) aquasalis.

Anopheline mosquitoes are vectors of malaria parasites. Their saliva contains anti-hemostatic and immune-modulator molecules that favor blood feeding and parasite transmission. In this study, we describe the inhibition of the alternative pathway of the complement system (AP) by Anopheles aquasalis salivary gland extracts (SGE). According to our results, the inhibitor present in SGE acts on the initial step of the AP blocking deposition of C3b on the activation surfaces. Properdin, which is a positive regulatory molecule of the AP, binds to SGE. When SGE was treated with an excess of properdin, it was unable to inhibit the AP. Through SDS-PAGE analysis, A. aquasalis presented a salivary protein with the same molecular weight as recombinant complement inhibitors belonging to the SG7 family described in the saliva of other anopheline species. At least some SG7 proteins bind to properdin and are AP inhibitors. Searching for SG7 proteins in the A. aquasalis genome, we retrieved a salivary protein that shared an 85% identity with albicin, which is the salivary alternative pathway inhibitor from A. albimanus. This A. aquasalis sequence was also very similar (81% ID) to the SG7 protein from A. darlingi, which is also an AP inhibitor. Our results suggest that the salivary complement inhibitor from A. aquasalis is an SG7 protein that can inhibit the AP by binding to properdin and abrogating its stabilizing activity. Albicin, which is the SG7 from A. albimanus, can directly inhibit AP convertase. Given the high similarity of SG7 proteins, the SG7 from A. aquasalis may also directly inhibit AP convertase in the absence of properdin.

The effect of hard tissue surgical changes on soft tissue displacement: a pilot CBCT study.

INTRODUCTION: This pilot study had as main objective to test the reliability of a new method to evaluate orthognathic surgery outcomes and also, to understand the effect of hard tissue changes on soft tissue displacement. METHODS: The sample consisted of eight patients that underwent bimaxillary advancement and had CBCT at two time points (before surgery and 6-8 months follow-up). Voxel-based cranial base superimposition was used to register the scans. A different technique of iterative closest point (ICP) was used to measure and correlate the changes. The average displacement of 15 areas (4 hard tissue and 11 soft tissue) were measured twice. RESULTS: ICC was > 0.99 for all areas. Changes in the tip of the nose did not correlate with changes in any maxillary area, whereas soft tissue A point, A point and upper lips had correlation with several areas. The highest correlation for the maxilla was between the upper lip and the left/right supra cheilion (p< 0.001, r= 0.91 and p< 0.001, r= 0.93, respectively). In the mandible, the majority of the correlations involved soft tissue pogonion, pogonion and lower incisors, with the strongest one between pogonion and lower incisors (p< 0.001, r= 0.98). CONCLUSION: With the proper case selection, ICP is a reliable method that can be used to assess three-dimensional changes.

Rapid 3D mandibular superimposition for growing patients.

OBJECTIVE: To evaluate the precision and reproducibility of a protocol to perform rapid voxel-based superimposition of the mandible in growing patients using CBCT. MATERIALS AND METHODS: The sample comprised two cone-beam computed tomography scans taken at least 1 year apart from each of 24 growing patients. Voxel-based superimposition was performed by two examiners independently. The internal part of the symphysis extending to the first molar was used as the reference. The superimposition process took approximately 5 minutes. Once the mandibles were superimposed, surface models were created and root mean square (RMS) changes were obtained by means of iterative closest point. To evaluate precision, differences in three areas were measured between time point 1 (T1) and time point 2 (T2) superimposed. To evaluate reproducibility between different examiners, the distances between T2 superimposed by each operator were measured in five different areas. Descriptive statistics were used to evaluate the precision of the superimposition and the interexaminer reproducibility measurements for each case were reported individually. RESULTS: The superimposition mean error between T1 and T2 for the right and left sides of the mandible and chin were 0.23 mm, 0.25 mm, and 0.33 mm, respectively. Interexaminer reproducibility error was ≤0.3 mm in 20 of 24 cases for measurements near the registration area. In the ramus area, two cases had errors >1 mm (1 mm-1.3 mm). CONCLUSION: The rapid superimposition was precise for assessing dentoalveolar changes and structures close to the registration area. However, evaluation of the condyles and ramus area had limitations and needs improvement.

Prevalence of malocclusion in public school students in the mixed dentition phase and its association with early loss of deciduous teeth

ABSTRACT Objective: To determine the prevalence of malocclusion and its association with the early loss of deciduous teeth and other factors in children in the mixed dentition phase, aged six to eight years, enrolled in public schools in southern Brazil. Methods: A cross-sectional study was conducted with a representative sample of 528 children from municipal public schools in 2009. Data collection involved a clinical examination for the determination of early tooth loss, dental caries, tongue pressure and malocclusion (outcome), as well as the administration of a questionnaire. Poisson regression analysis with robust variance was used to model the association between malocclusion and the independent variables. Results: The prevalence of malocclusion and early tooth loss was 69.1% and 21.8%, respectively. In the raw data analysis, malocclusion was associated with age, early tooth loss, dental caries and tongue pressure. After the adjustment, the likelihood of malocclusion was greater among children older than eight years, those who exerted tongue pressure on the teeth and those with early tooth loss. The likelihood of malocclusion was 24% greater among children with early tooth loss, compared to those without tooth loss. Conclusion: The early loss of deciduous teeth was associated with the occurrence of malocclusion in the children studied.

RESUMO Objetivo: Determinar a prevalência de má oclusão em crianças de seis a oito anos de idade no município de Florianópolis (Santa Catarina, Brasil), e a sua associação com a perda precoce de dentes decíduos. Métodos: Esse estudo transversal avaliou uma amostra representativa de 528 crianças de escolas públicas municipais de Florianópolis, no ano de 2009. Os dados foram coletados por meio de exame clínico (perda dentária precoce, cárie dentária, interposição lingual e má oclusão - que foi o desfecho do estudo) e de um questionário. A regressão de Poisson com variância robusta foi utilizada para modelar a associação entre má oclusão e as variáveis independentes. Resultados: A prevalência de má oclusão e de perda dentária precoce foi, respectivamente, de 66,7% e 21,8%. Na análise dos dados brutos, a má oclusão foi associada com a idade, perda dentária precoce e cárie dentária. Após ser feito o ajuste, crianças com mais de 7 anos, com interposição lingual e perda dentária precoce apresentaram maior probabilidade de ter má oclusão. Crianças com perda dentária precoce apresentaram probabilidade 24% maior de ter má oclusão do que aquelas sem perda dentária. Conclusões: A perda precoce de dentes decíduos foi associada à ocorrência de má oclusão nas crianças estudadas.

Use of shape correspondence analysis to quantify skeletal changes associated with bone-anchored Class III correction.

OBJECTIVE: To evaluate the three-dimensional (3D) skeletal changes in the mandibles of Class III patients treated with bone-anchored maxillary protraction using shape correspondence analysis. MATERIAL AND METHOD: Twenty-five consecutive patients with skeletal Class III who were between the ages of 9 and 13 years (mean age, 11.10 ± 1.1 years) were treated using Class III intermaxillary elastics and bilateral miniplates (two in the infrazygomatic crests of the maxilla and two in the anterior mandible). Cone-beam computed tomography (CBCT) was performed for each patient before initial loading (T1) and at 1 year out (T2). From the CBCT scans, 3D models were generated, registered on the anterior cranial base, and analyzed using 3D linear distances and vectors between corresponding point-based surfaces. RESULTS: Bone-anchored traction produced anteroposterior and vertical skeletal changes in the mandible. The novel application of Shape correspondence analysis showed vectors of mean (± standard deviation) distal displacement of the posterior ramus of 3.6 ± 1.4 mm, while the chin displaced backward by 0.5 ± 3.92 mm. The lower border of the mandible at the menton region was displaced downward by 2.6 ± 1.2 mm, and the lower border at the gonial region moved downward by 3.6 ± 1.4 mm. There was a downward and backward displacement around the gonial region with a mean closure of the gonial angle by 2.1°. The condyles were displaced distally by a mean of 2.6 ± 1.5 mm, and there were three distinct patterns for displacement: 44% backward, 40% backward and downward, and 16% backward and upward. CONCLUSION: This treatment approach induces favorable control of the mandibular growth pattern and can be used to treat patients with components of mandibular prognathism.

Reliability of CBCT in the diagnosis of dental asymmetry.

OBJECTIVE: The aim of this study was to validate a method used to assess dental asymmetry, in relation to the skeletal midline, by means of CBCT. METHODS: Ten patients who had CBCT scans taken were randomly selected for this study. Five different observers repeated 10 landmarks (x, y and z variables for each) and 12 linear measurements within 10 days. Measurements were taken in both arches to evaluate symmetry of first molars, canines and dental midline in relation to the skeletal midline. Intraclass correlation coefficient (ICC) was carried out to assess intra- and interobserver reliability for landmarks and distances. Average mean difference was also assessed to check measurement errors between observers. RESULTS: ICC for the landmarks was, respectively, ≥ 0.9 for 27 (90%) and 25 (83%) variables for intra- and interobserver; ICC for distances was ≥ 0.9 for 7 (58%) and 5 (42%), respectively. All ICC landmarks for distances were >0.75 for both intra- and interobserver. The mean difference between observers was ≤ 0.6 mm for all the distances. CONCLUSION: The method used to assess dental asymmetry by means of CBCT is valid. Measurements of molars, canines and dental midline symmetry with the skeletal midline are reproducible and reliable when taken by means of CBCT and by different operators.

The effect of hard tissue surgical changes on soft tissue displacement: a pilot CBCT study

ABSTRACT Introduction: This pilot study had as main objective to test the reliability of a new method to evaluate orthognathic surgery outcomes and also, to understand the effect of hard tissue changes on soft tissue displacement. Methods: The sample consisted of eight patients that underwent bimaxillary advancement and had CBCT at two time points (before surgery and 6-8 months follow-up). Voxel-based cranial base superimposition was used to register the scans. A different technique of iterative closest point (ICP) was used to measure and correlate the changes. The average displacement of 15 areas (4 hard tissue and 11 soft tissue) were measured twice. Results: ICC was > 0.99 for all areas. Changes in the tip of the nose did not correlate with changes in any maxillary area, whereas soft tissue A point, A point and upper lips had correlation with several areas. The highest correlation for the maxilla was between the upper lip and the left/right supra cheilion (p< 0.001, r= 0.91 and p< 0.001, r= 0.93, respectively). In the mandible, the majority of the correlations involved soft tissue pogonion, pogonion and lower incisors, with the strongest one between pogonion and lower incisors (p< 0.001, r= 0.98). Conclusion: With the proper case selection, ICP is a reliable method that can be used to assess three-dimensional changes.

RESUMO Objetivo: o objetivo deste estudo piloto foi testar a confiabilidade de um novo método para avaliar os resultados da cirurgia ortognática e entender o efeito das alterações dos tecidos duros no deslocamento dos tecidos moles. Métodos: a amostra selecionada consistiu de oito pacientes submetidos a avanço bimaxilar que possuíam TCFC em dois períodos de tempo (antes da cirurgia e de 6 a 8 meses após a cirurgia). A sobreposição da base do crânio pelo método voxel-based foi utilizada para registrar as varreduras, enquanto uma técnica diferente, de ponto iterativo mais próximo (ICP), foi usada para medir e correlacionar as mudanças. O deslocamento médio de 15 áreas (4 em tecidos duros e 11 em tecidos moles) foi mensurado duas vezes. Resultados: o ICC foi > 0,99 para todas as áreas. As alterações da ponta do nariz não se correlacionaram com alterações em qualquer área da maxila, enquanto o ponto A em tecido mole, o ponto A e os lábios superiores apresentaram correlação com várias áreas. A maior correlação para a maxila foi entre o lábio superior e a supracomissura esquerda/direita (p< 0,001, r = 0,91 e p< 0,001, r = 0,93, respectivamente). Na mandíbula, a maioria das correlações envolveu o pogônio em tecido mole, pogônio e incisivos inferiores, sendo a maior entre pogônio e incisivos inferiores (p< 0,001, r= 0,98). Conclusão: com a seleção adequada do caso, o ICP é um método confiável que pode ser utilizado para avaliar mudanças tridimensionais.

Reliability of CBCT in the diagnosis of dental asymmetry

Objective: The aim of this study was to validate a method used to assess dental asymmetry, in relation to the skeletal midline, by means of CBCT. Methods: Ten patients who had CBCT scans taken were randomly selected for this study. Five different observers repeated 10 landmarks (x, y and z variables for each) and 12 linear measurements within 10 days. Measurements were taken in both arches to evaluate symmetry of first molars, canines and dental midline in relation to the skeletal midline. Intraclass correlation coefficient (ICC) was carried out to assess intra- and interobserver reliability for landmarks and distances. Average mean difference was also assessed to check measurement errors between observers. Results: ICC landmarks was ≥ 0.9 for 27 (90%) and 25 (83%) variables for intra- and interobserver, respectively. ICC for distances was ≥ 0.9 for 7 (58%) and 5 (42%), respectively. All ICC landmarks for distances were >0.75 for both intra- and interobserver. The mean difference between observers was ≤ 0.6 mm for all the distances. Conclusion: The method used to assess dental asymmetry by means of CBCT is valid. Measurements of molars, canines and dental midline symmetry with the skeletal midline are reproducible and reliable when taken by means of CBCT and by different operators. .

Objetivo: validar um método para avaliar assimetria dentária, em relação à linha média esquelética, usando TCFC. Métodos: dez pacientes que realizaram TCFC foram selecionados aleatoriamente para esse estudo. Cinco diferentes observadores repetiram 10 pontos de referência (com variáveis x, y e z, para cada ponto) e 12 medidas lineares em um intervalo de 10 dias. As medições foram realizadas em ambas as arcadas, para avaliar a simetria de primeiros molares, caninos e linha média dentária, em relação à linha média esquelética. Índice de correlação intraclasse (ICC) foi realizado para verificar a confiabilidade intraobservador e interobservadores para os pontos de referência e distâncias. A diferença média também foi avaliada, para checar os erros de mensuração entre os observadores. Resultados: ICC para os pontos de referência foram ≥ 0,9 para 27 (90%) e 25 (83%) das variáveis para intra- e interobservadores respectivamente. ICC para distâncias foi ≥ 0,9 para 7 (58%) e 5 (42%), respectivamente. Todas as medidas de ICC para distâncias foram > 0,75 para intraobservador e interobservadores. A diferença média entre observadores foi ≤ 0,6mm para todas as distâncias. Conclusão: o método de verificação de assimetria dentária utilizando TCFC é válido. Medições de molares, caninos e linha média dentária com a linha média esquelética são reproduzíveis e confiáveis quando feitas utilizando TCFC, mesmo que por diferentes operadores. .