Assessment of condylar changes after orthognathic surgery using computed tomography regional superimposition.

This study aimed to investigate the effects of bimaxillary advancement orthognathic surgery on the condylar remodeling of the temporomandibular joint (TMJ) using voxel-based regional superimposition of cone-beam computed tomography (CBCT). In this retrospective study, the sample comprised 56 condyles from 28 healthy patients (aged from 16 to 50years) with mandibular retrognathism treated with bimaxillary advancement. CBCT scans were taken preoperatively and at 14.3±4.2months postoperatively. The scans at the two time points were superimposed using regional voxel-based registration to assess condylar changes in the follow-up period. The linear alterations were measured in six different areas of each condyle to determine the pattern of condylar remodeling. Although no significant correlation was observed between changes in condylar surfaces, bone resorption occurred predominantly in the posterior and superior regions, while bone formation was predominantly on the anterior surface. Medial and lateral surfaces presented fewer bone changes. The overall bone changes were smaller than 1mm bilaterally in 21 patients (75%) and, considering each condyle individually, were smaller than 1mm in 48 condyles (85.7%). The results suggested that mild condylar remodeling in healthy patients is a common finding after orthognathic surgery. Future studies may clarify the mechanisms involved in the remodeling and help to understand the reasons for the remodeling pattern.

Three-dimensional maxillary and mandibular regional superimposition using cone beam computed tomography: a validation study.

This study aimed to validate a novel method for fast regional superimposition of cone beam computed tomography (CBCT) scans. The method can be used with smaller field of view scans, thereby allowing for a lower radiation dose. This retrospective study used two dry skulls and secondary data from 15 patients who had more than one scan taken using the same machine. Two observers tested two types of regional voxel-based superimposition: maxillary and mandibular. The registration took 10-15s. Three-dimensional surface models of the maxillas and mandibles were generated via standardized threshold segmentation, and the accuracy and reproducibility of the superimpositions were assessed using the iterative closest point technique to measure the root mean square (RMS) distance between the images. Five areas were measured and a RMS≤0.25 was considered successful. Descriptive statistics and the intra-class correlation coefficient (ICC) were used to compare the intra-observer measurement reproducibility. The ICC was ≥0.980 for all of the variables and the highest RMS found was 0.241. The inter-observer reproducibility was assessed case by case and was perfect (RMS 0) for 68% (23 out of 34) of the superimpositions done and not clinically significant (RMS≤0.25) for the other 32%. The method is fast, accurate, and reproducible and is an alternative to cranial base superimposition.

Fast three-dimensional superimposition of cone beam computed tomography for orthopaedics and orthognathic surgery evaluation.

The aim of this study was to validate a method for fast three-dimensional (3D) superimposition of cone beam computed tomography (CBCT) in growing patients and adults (surgical cases). The sample consisted of CBCT scans of 18 patients. For 10 patients, as the gold standard, the spatial position of the pretreatment CBCT was reoriented, saved as a reoriented volume, and then superimposed on the original image. For eight patients, four non-growing and four growing, the pre- and post-treatment scans were superimposed. Fast voxel-based superimposition was performed, with registration at the anterior cranial base. This superimposition process took 10-15s. The fit of the cranial base superimposition was verified by qualitative visualization of the semi-transparent axial, sagittal, and coronal cross-sectional slices of all corresponding anatomical structures. Virtual 3D surface models of the skull were generated via threshold segmentation, and superimposition errors in the reoriented models and the results of treatment for the treated cases were evaluated by 3D surface distances on colour-coded maps. The superimposition error of the spatial reorientation and for growing and non-growing patients was <0.5mm, which is acceptable and clinically insignificant. The voxel-based superimposition method evaluated was reproducible in different clinical conditions, rapid, and applicable for research and clinical practice.

Transcultural adaptation of the filial responsibility interview schedule for Brazil.

BACKGROUND: In developed countries, filial responsibility in relation to caring for elderly parents has been systematically studied. In Brazil and other developing countries, however, it is a relatively new topic and has not yet been included in the research agenda on ageing. OBJECTIVE: To describe the process of cross-cultural adaptation of the qualitative phase of the filial responsibility interview schedule into Brazilian Portuguese. METHODS: An expert committee of six team members participated in the study. In addition, individual interviews were held with 11 caregivers of older persons to evaluate the quality of the final Portuguese version of the schedule. The process included examining conceptual, item, semantic and operational equivalencies. Conceptual and item equivalencies were based on a literature review and on discussions with the expert committee. Semantic equivalence was attained through translation, back-translation, expert committee evaluation and pre-testing. The final version was pre-tested in caregivers of older persons enrolled in the home care programme of a primary health care service in Southern Brazil. RESULTS: Conceptual, item, semantic and operational equivalencies were attained. Through the interviews, responses to the open-ended questions concerning filial responsibility in the care for elderly parents pertained to the following categories: possibility of institutionalization of elderly parents, caregiver expectations, difficulties in being a child caregiver and responsibility as a natural process. CONCLUSION: The Portuguese version presented good semantic equivalence and the results showed that the concepts and items are applicable to the Brazilian context.