Felipe de Assis Ribeiro Carvalho

Soft tissue response to mandibular advancement using 3D CBCT scanning

This prospective longitudinal study assessed the 3D soft tissue changes following mandibular advancement surgery. Cranial base registration was performed for superimposition of virtual models built from cone beam computed tomography (CBCT) volumes. Displacements at the soft and hard tissue chin (n = 20), lower incisors and lower lip (n = 21) were computed for presurgery to splint removal (4-6-week surgical outcome), presurgery to 1 year postsurgery (1-year surgical outcome), and splint removal to 1 year postsurgery (postsurgical adaptation). Qualitative evaluations of color maps illustrated the surgical changes and postsurgical adaptations, but only the lower lip showed statistically significant postsurgical adaptations. Soft and hard tissue chin changes were significantly correlated for each of the intervals evaluated: presurgery to splint removal (r = 0.92), presurgery to 1 year postsurgery (r = 0.86), and splint removal to 1 year postsurgery (r = 0.77). A statistically significant correlation between lower incisor and lower lip was found only between presurgery and 1 year postsurgery (r = 0.55). At 1 year after surgery, 31% of the lower lip changes were explained by changes in the lower incisor position while 73% of the soft tissue chin changes were explained by the hard chin. This study suggests that 3D soft tissue response to mandibular advancement surgery is markedly variable.

Three-dimensional assessment of mandibular advancement 1 year after surgery

INTRODUCTION This prospective observational study evaluated changes in the 3-dimensional position and remodeling of the mandibular rami, condyles, and chin at splint removal and 1 year after mandibular advancement surgery. METHODS Presurgery, splint removal (4-6 weeks postsurgery), and 1-year postsurgery cone-beam computed tomography scans of 27 subjects were used. Superimposition on the cranial base was used to assess positional or remodeling changes in the anatomic regions of interest. Surface distance displacements were visually displayed and quantified by 3-dimensional color maps. A 1-sample t test was used to assess the average postsurgical changes of each region of interest. The level of significance was set at 0.05. RESULTS After antero-inferior chin displacement with surgery (mean, 6.81 +/- 3.2 mm at splint removal), the average 1-year postsurgery displacement was not statistically significant (P = 0.44). Postsurgical adaptations greater than 2 mm were observed in 48% of the patients: 16% with an additional anterior-inferior displacement of the chin of 2 to 4 mm, and 4% with >or= 4 mm; 20% had postero-superior movement of 2 to 4 mm, and 8% had postero-superior movement of >or= 4 mm. The condyles tended to move, on average, <or= 2 mm supero-posteriorly with surgery, and this small positional displacement was maintained 1 year postsurgery (right condyle, P = 0.58; left, P = 0.88). The rami exhibited outward (lateral) movements with surgery, with greater displacement of the inferior part of the rami (2 mm in 65% of the subjects). This torque of the ramus with surgery was stable 1 year postsurgery. CONCLUSIONS Three-dimensional assessment of skeletal changes with mandibular advancement surgery shows that nearly half of the patients have >2 mm change in chin position from splint removal to the 1-year follow-up, with approximately equal chances of anterior and posterior movement. Torque of the rami usually occurs with mandibular advancement surgery.

Three-dimensional regional displacements after mandibular advancement surgery: one year of follow-up.

PURPOSE To evaluate the association of 3-dimensional changes in the position of the condyles, rami, and chin at splint removal and 1 year after mandibular advancement surgery. PATIENTS AND METHODS This prospective observational study used preoperative and postoperative scans of 27 subjects presenting with a skeletal Class II jaw relationship with a normal or deep overbite. An automatic technique of cranial base superimposition was used to assess the positional and/or remodeling changes in the anatomic regions of interest. The displacements were visually displayed and quantified using 3-dimensional color maps. The positive and negative values of surface distances in the color maps indicated the direction of the displacements. Pearson correlation coefficients and a linear model for correlated data were used to evaluate the association between the regional displacements. RESULTS The postoperative adaptations in the chin position between splint removal and 1 year after surgery were significantly negatively correlated with changes in the borders of the posterior ramus (left, r = -0.73, P ≤ .0001; and right, r = -0.68, P = .00) and the condyles (left, r = -0.53, P = .01; and right, r = -0.46, P = .02), indicating that these structures tended to be displaced in the same direction. Even though the mean condylar displacement with surgery was less than 1 mm, individual displacements greater than 2 mm with surgery were observed for 24% of the condyles. The condylar displacements were maintained at 1 year after surgery for 17% of the condyles. CONCLUSIONS The surface distance displacements indicated that the postoperative adaptations at different anatomic regions were significantly related.

Superimposition of 3D cone-beam CT models in orthognathic surgery

INTRODUCTION: Limitations of 2D quantitative and qualitative evaluation of surgical displacements can be overcome by CBCT and three-dimensional imaging tools. OBJECTIVES: The method described in this study allows the assessment of changes in the condyles, rami, chin, maxilla and dentition by the comparison of CBCT scans before and after orthognathic surgery. METHODS: 3D models are built and superimposed through a fully automated voxel-wise method using the pre-surgery cranial base as reference. It identifies and compares the grayscale of both three-dimensional structures, avoiding observer landmark identification. The distances between the anatomical surfaces pre and post-surgery are then computed for each pair of models in the same subject. The evaluation of displacement directions is visually done through color maps and semi-transparencies of the superimposed models. CONCLUSIONS: It can be concluded that this method, which uses free softwares and is mostly automated, shows advantages in the long-term evaluation of orthognathic patients when compared to conventional 2D methods. Accurate measurements can be acquired by images in real size and without anatomical superimpositions, and great 3D information is provided to clinicians and researchers.

Long-Term 3-Dimensional Stability of Mandibular Advancement Surgery

PURPOSE To evaluate 3-dimensional changes in the position of the condyles, rami, and chin from 1 to 3 years after mandibular advancement surgery. MATERIALS AND METHODS This prospective observational study used pre- and postoperative cone-beam computed tomograms of 27 subjects with skeletal Class II jaw relation and normal or deep overbite. An automatic technique of cranial base superimposition was used to assess positional and bone remodeling changes that were visually displayed and quantified using 3-dimensional color maps. Analysis of covariance with presence of genioplasty, age at time of surgery, and gender as explanatory variables was used to estimate and test adjusted mean changes for each region of interest. RESULTS The chin rotated downward and backward 1 to 3 years after surgery. Changes of at least 2 mm were observed in 17% of cases. Mandibular condyles presented with displacements or bone remodeling of at least 2 mm on the anterior surface (21% of cases on the left side and 13% on the right), superior surface (8% on right and left sides), and lateral poles (17% on left side and 4% on right). Posterior borders of the rami exhibited symmetric lateral or rotational displacements in 4% of cases. CONCLUSION In the hierarchy of surgical stability, mandibular advancement surgery is considered one of the most stable surgical procedures. However, 1 to 3 years after surgery, approximately 20% of patients had 2- to 4-mm changes in horizontal and vertical chin positions or changes in condylar position and adaptive bone remodeling.

Assessment of mandibular advancement surgery with 3D CBCT models superimposition

OBJECTIVES: To assess surgery and short-term post-surgery changes in the position of the condyles, rami and chin after mandibular advancement. METHODOLOGY: Pre-surgery (T1), 1 week post-surgery (T2), and 6 week post-surgery (T3) CBCT scans were acquired for 20 retrognathic patients with short or normal face height. 3D models were built and superimposed through a fully automated voxel-wise method using the cranial base of the pre-surgery scan as reference. Anatomic regions of interest were selected and analyzed separately. Within-subject surface distances between T1-T2, T2-T3, and T1-T3 were computed. Color-coded maps and semi-transparent display of overlaid structures allowed the evaluation of displacement directions. RESULTS: After an antero-inferior chin displacement with surgery in all cases (>4 mm in 87.5%), 25% of the patients showed some kind of posterior movement (< 3 mm), and 69% showed an antero-superior movement after splint removal. Comparing T1-T3, an antero-inferior (87.5% of the cases) or only inferior (12.5%) displacement was observed (>4 mm in 80%). Considering all directions of displacement, the surface distance differences for the condyles and rami were small: 77.5% of the condyles moved <2 mm with surgery (T1-T2), and 90% moved <2 mm in the short-term (T2-T3) and in the total evaluation (T1-T3), while the rami showed a <3 mm change with surgery in 72.5% of the cases, and a <2 mm change in 87.5% (T2-T3) and in 82% (T1-T3). CONCLUSIONS: Expected displacements with surgery were observed and post-surgery changes suggested a short-term adaptive response toward recovery of condyle and ramus displacements. The changes on the chin following splint removal suggested an acceptable adaptation, but with considerable individual variability.

Efficiency of light-emitting diode and halogen units in reducing residual monomers.

INTRODUCTION In this in-vitro study, we aimed to compare the residual monomers in composites beneath brackets bonded to enamel, using a light-emitting diode (LED) or a halogen unit, and to compare the residual monomers in the central to the peripheral areas of the composite. METHODS Twenty bovine teeth preserved in 0.1% thymol were used in this study. Ten teeth were used to standardize the thickness of the composite film, since different thicknesses would cause different absorbance of light. Brackets were bonded to 10 bovine incisors, with the halogen light (n = 5) and the LED (n = 5). The brackets were debonded, and the remaining composite on the enamel surface was sectioned in 2 regions: peripheral (0.8 mm) and central, resulting in 2 subgroups per group: central halogen (n = 5), peripheral halogen (n = 5), central LED (n = 5), and peripheral LED (n = 5). The spectrometric analysis in the infrared region was used to measure the free monomers with the attenuated total reflectance method. RESULTS Normal distribution was tested by using the Kolmogorov-Smirnov test. Data were compared by 2-way analysis of variance (ANOVA) at P <0.05. The LED group showed fewer residual monomers than did the halogen group (P = 0.014). No differences were found among the regions (P = 0.354), and there were no interactions between light type and region (P = 0.368). CONCLUSIONS LED leaves less residual monomer than does the halogen light, even with half of the irradiation time; there were no differences between the central and peripheral regions, and no interaction between light type and region.

Aparelho de avanço mandibular aumenta o volume da via aérea superior de pacientes com apneia do sono

Introduction: Diagnosis, treatment and monitoring of patients with obstructive sleep apnea syndrome (OSAS) are crucial because this disorder can cause systemic changes. The effectiveness of OSAS treatment with intraoral devices has been demonstrated through cephalometric studies. Objective: The purpose of this study was to evaluate the effect of a mandibular advancement device (Twin Block, TB) on the volume of the upper airways by means of ConeBeam Computed Tomography (CBCT). Sixteen patients (6 men and 10 women) with mild to moderate OSAS, mean age 47.06 years, wore a mandibular advancement device and were followed up for seven months on average. Methods: Two CBCT scans were obtained: one with and one without the device in place. Upper airway volumes were segmented and obtained using Student’s paired t-tests for statistical analysis with 5% significance level. Results: TB use increased the volume of the upper airways when compared with the volume attained without TB (p<0.05). Conclusion: It can be concluded that this increased upper airway volume is associated with the use of the TB mandibular advancement device.

Comparação entre a radiografia de cavum e a cefalométrica de perfil na avaliação da nasofaringe e das adenoides por otorrinolaringologistas

INTRODUCAO: tanto a radiografia cefalometrica de perfil quanto a de cavum permitem a avaliacao do espaco aereo nasofaringeo (EAN). Nao e rara a solicitacao dos otorrinolaringologistas de radiografia de cavum, mesmo o paciente possuindo uma cefalometrica. OBJETIVOS: objetivou-se (a) conhecer quais exames os otorrinolaringologistas solicitam para avaliar o EAN; (b) verificar o conhecimento da cefalometrica por otorrinolaringologistas; (c) comparar a avaliacao de otorrinolaringologistas nas duas tecnicas radiograficas para a medicao e a visualizacao do EAN e da adenoide; (d) correlacionar os resultados do metodo de inspecao visual com os da medicao de Schulhof. METODOS: foram obtidas, no mesmo dia, radiografias cefalometricas e de cavum de 15 pacientes respiradores bucais. Essas foram cobertas com papel cartao, deixando visivel apenas o EAN e adenoides e foram avaliadas por 12 otorrinolaringologistas. Estes respondiam sobre sua familiaridade com a cefalometrica, quais exames solicitam para visualizar EAN e adenoides e se utilizam algum metodo de medicao do grau de obstrucao. Avaliavam qual das radiografias apresentava a melhor visualizacao da adenoide e do EAN, e classificavam o tamanho dos mesmos em pequeno, medio ou grande, atraves de metodo visual. RESULTADOS: os resultados demonstraram que todos os otorrinolaringologistas costumam solicitar a radiografia de cavum. Apenas um solicita a cefalometrica, dois estao familiarizados com essa tecnica e um utiliza algum metodo de medicao do EAN. A cefalometrica foi preferida por 49,4% dos otorrinolaringologistas, a de cavum por 22,8%, enquanto 27,8% nao observaram diferenca entre ambas. Foi encontrada baixa correlacao entre o metodo de medicao visual e o de Schulhof.

Three-dimensional surface models of the facial soft tissues acquired with a low-cost scanner

Although there has been an increase in three-dimensional (3D) scanning methods available on the market, they are generally expensive. The DI3D system is considered a good scanner for the acquisition of soft tissue surface images. The Microsoft Kinect scanner is a much more affordable alternative for acquiring 3D models. The aim of this study was to determine whether the precision and accuracy of Kinect are similar to those of DI3D. To verify the accuracy, 10 patients were scanned with both methods The models of each patient acquired from the two scanners were superimposed using a surface-to-surface registration technique, and the distances between the models were recorded for 10 different anatomical regions of interest. For the evaluation of precision, one patient was scanned 11 different times with the Kinect scanner, and these models were compared using the same superimposition method. It was found that the average difference between the two methods was 0.3±2.03mm. The assessment of reproducibility showed an average difference between the images taken with Kinect of 0.1±0.6mm (P<0.05, one-sample t-test). Thus, Kinect showed good precision and reasonable accuracy, and appears to be an interesting and promising resource for facial analysis.