A New Proposal for Three-Dimensional Positioning of the Chin Using a Single Computer-Aided Design/Computer-Aided Manufacturing Surgical Guide.

The workflow digital to aid the treatment of dentofacial deformities is a reality. Associated with the virtual planning, the creation of surgical guides assists the performance of osteotomies and bone positioning, increasing the accuracy of surgical outcomes. This study aims to present a new method of surgical guide for genioplasty based on the selected osteosynthesis plate.

Chin Wing Osteotomy for Improving Mandible Projection and Contour in Patients with Normal Occlusion: Case Reports.

Aim: To present a chin wing osteotomy in two patients who had undergone a virtual surgical planning workflow for surgical procedures and were followed up for 4 years. Case reports: Two retrognathic patients with normal occlusion were evaluated by means of dental and facial photographs, cone beam computed tomographs and digitization of dental arches. Virtual surgical planning was performed by using the Dolphin Imaging software to simulate the chin wing osteotomy. Next, three-dimensional models were imported into computer-aided design system (Rhino 6) for designing two hybrid (dental-bone supported) cutting and repositioning guides. Chin wing osteotomies were carried out by using the cutting guides and the osteotomized segments were placed by using L-shaped plates and screws assisted by the repositioning guides. Bone grafts were interposed in the mandibular angle region bilaterally. In both cases, the patients reported aesthetically and functionally favorable outcomes. Conclusion: Chin wing osteotomy is an appropriate treatment for retrognathic mandible in patients with normal occlusion and no additional discrepancies as the technique provided chin advancement and improvement in facial contour. The post-operative outcomes showed reliable workflow of virtual planning and surgical procedures, which could be adopted as an alternative in similar cases.

Different Modalities to Record and Transfer Natural Head Position to Virtual Planning in Orthognathic Surgery: Case Reports of Asymmetric Patients.

AIM: To describe different modalities to record and transfer natural head position (NHP) to 3D facial imaging by using the virtual surgical planning software in three facial asymmetry patients. CASE REPORTS: Three patients with facial asymmetries (A, B, and C) were evaluated by means of dental and facial analysis, photographs, cone-beam computed tomography (CBCT) and digitized dental arches. Before starting the VSP workflow with Dolphin Imaging, NHP was recorded by three modalities and transferred to three-dimensional (3D) facial images as follows: (a) facial photographs taken with digital camera and the estimated NHP was transferred to 3D images by comparing lines and planes from both images; (b) cross-line level laser was used to place radiopaque markers on the face skin for recording the estimated NHP, which was transferred to 3D images by alignment of planes and markers in the software; and (c) photographs of the face were processed to generate facial surface mesh by using the Agisoft PhotoScan software, which maintained the same position of the estimated NHP in 3D for aligning the images of the soft tissue with the facial surface mesh by using superimposition. All the three patients underwent bi-maxillary orthognathic surgery. CONCLUSION: There are different modalities using simple and available technologies in the clinical routine, but whose reproducibility, reliability and validation could not be assessed nor compared to each other. There was no trend for better predictability, feasibility and efficiency because the postoperative outcomes were adequate regarding the patients' satisfaction and facial symmetry.

Feasibility of iterative closest point algorithm for accuracy between virtual surgical planning and orthognathic surgery outcomes.

PURPOSE: To evaluate the feasibility of iterative closest point (ICP) algorithm for assessing the accuracy between virtual surgical planning (VSP) and outcomes in orthognathic surgery. MATERIALS AND METHODS: VSP and results of surface mesh (SM0 and SM1) from CBCT scans of 25 patients who had been undergone bi-maxillary orthognathic surgery were converted into STL-format files and then imported to Geomagic software for semi-automatic alignment. ICP algorithm was used to calculate mean deviations (MD) and root mean square (3D error) at different calibrations of ±2 mm (T1), ±5 mm (T2) and ±10 mm (T3), with workflow being performed by two evaluators. Colour maps were generated to assess the 3D congruence qualitatively. Linear regression analysis was used to estimate whether SM0 or SM1 could condition the ICP and t-tests were used to assess whether MD and 3D error values were ≤-2 mm and ≥2 mm. Descriptive statistics was used to assess the method's feasibility by comparing T2 to T1 and T3. RESULTS: High intra- and inter-rater correlations supported the workflow reproducibility with the software. SM0 conditioned the ICP algorithm regarding both evaluators, and t-tests demonstrated that MD and 3D error were >-2 mm and <2 mm. MD and 3D error at T3 were 30% higher than those at T1. CONCLUSIONS: ICP algorithm provided a reproducible method, but its feasibility was limited due to underestimation or overestimation of the results as they affect the validity of the actual deviations.

Accuracy of computer-guided surgery for dental implant placement in fully edentulous patients: A systematic review.

Assess clinical studies regarding accuracy between virtual planning of computer-guided surgery and actual outcomes of dental implant placements in total edentulous alveolar ridges. A PubMed search was performed to identify only clinical studies published between 2011 and 2016, searching the following combinations of keywords: "Accuracy AND Computer-Assisted Surgery AND Dental Implants." Study designs were identified using the terms: Case Reports, Clinical study, Randomized Controlled Trial, Systematic Reviews, Meta-Analysis, humans. Level of agreement between the authors in the study selection process was substantial (k = 0.767), and the study eligibility was considered excellent (k = 0.863). Seven articles were included in this review. They describe the use of bone and muco-supported guides, demonstrating angular deviations cervically and apically ranging from (minimum and maximum means), respectively, 1.85-8.4 (°), 0.17-2.17 (mm), and 0.77-2.86 (mm). Angular deviations obtained most inaccuracy in maxila. For cervical and apical deviations, accuracy was preponderantly lower in maxilla. Despite the similar deviations measurement approaches described, clinical relevance of this study may be useful to warn the surgeon that safety margins in clinical situations.

Hemartrocentese: tratamento adjunto para luxação crônica da ATM / Hemartrocentesis: adjunct treatment for TMJ chronic dislocation

Os deslocamentos condilares da Articulação Temporomandibular (ATM) correspondem à perda de contato parcial ou total entre as duas superfícies ósseas articulares, na qual se refere o côndilo ultrapassa anteriormente a eminência articular. Entretanto, quando este se mantém à frente da eminência, necessitando de redução clínica, corresponde ao quadro clínico de luxação. O deslocamento geralmente é ocasionado por trauma ou hipermobilidade mandibular, assim como fatores agravantes: anatomia articular desfavorável, espasmos musculares, flacidez nos ligamentos articulares, desordens psicogênicas, síndromes, abertura bucal excessiva ao bocejar, rir, comer e em tratamentos odontológicos prolongados. Este trabalho apresenta dois casos clínicos em pacientes com histórico de luxação recidivante e crônico da ATM, em que o tratamento proposto de forma inicial utilizou a injeção de sangue autógeno (hemartrocentese) por representar uma forma menos invasiva. Dessa forma, visamos expor a aplicabilidade dessa modalidade de tratamento que se mostra como uma alternativa eficaz e conservadora para luxação recidivante crônica da ATM... (AU)

Condylar displacement of Temporomandibular Joint (TMJ) corresponds to the loss of partial or total contact between the two articular bone surfaces, in which the condyle surpasses the articular eminence. However, when the condyle remains ahead of the eminence, requiring clinical reduction, it corresponds to the clinical scenario of dislocation. TMJ dislocation is usually caused by trauma or mandibular hypermobility, as well as aggravating factors: unfavorable joint anatomy, muscle spasms, sagging of joint ligaments, psychogenic disorders, syndromes, excessive mouth opening while yawning, laughing, eating, and prolonged dental treatments. This paper presents two clinical cases of patients with history of recurrent and chronic TMJ dislocation, where the initial treatment was the injection of autogenous blood (hemartrocentesis) because it represented a less invasive modality. Thus, we aim to expose the applicability of this technique that is shown to be an effective and conservative alternative for chronic TMJ dislocation... (AU)