Virtual planning and navigational technology in reconstructive surgery.

Reconstructive technologies have expanded to include the use of virtual surgical planning (VSP) and computer-aided design and manufacturing (CAD-CAM), and 3-Dimensional printing. The advantages of VSP over traditional techniques are highlighted in many scenarios: (a) delayed reconstruction, (b) maxillary reconstruction, (c) placement of dental implants, and (d) precision guided oncology. Microsurgery is undergoing a paradigm shift with virtual planning at its foreground. Herein, we describe the versatile uses for CAD-CAM and key operative steps.

Poor condyle position after mandibular reconstruction and a classification system for patients with "VSCU" based on computed tomography: a cross-sectional study with retrospective data collection.

Background: Although the application of vascularized free bone muscle flap to reconstruct the mandible has become a standardized approach for mandible reconstruction, the results of its reconstruction are not always satisfactory. The purpose of this study was to identify the types of mandibular and condylar defects by analyzing the unsatisfactory cases of mandibular reconstruction in clinical practice, and to provide some clinical experience of reconstruction. Methods: Our study retrospectively analyzed 364 patients who underwent mandibular resection and vascularized free bone flap reconstruction of the mandible and temporomandibular joint (TMJ). We innovatively proposed a "VSCU" classification system (V: vertical position, S: sagittal position, C: coronal position, U: condylar resection is not required) by analyzing computed tomography (CT) scans of mandibular branches and TMJs. Results: In all, 221 cases of free iliac muscle flap and 143 cases of fibula muscle flap were included in this study, of which 23 cases had unsatisfactory results after TMJ reconstruction. We classified 23 patients with unsatisfactory mandibular reconstruction according to the "VSCU" classification system. The most common type was U + V + SfC (n=8), followed by V - SfC + U + (n=4), V - s + C + U + (n=3), V - sbcou - (n=3), V - SBC + U + (n=2), V - s + C + U - (n=1). The most common classification was insufficient mandibular rami length, followed by condylar sagittal anteriorization. There was no significant change in the position of condyle on the healthy side during mandibular reconstruction involving condyle. P1 on the affected side was 52.28±4.17 mm before operation and 58.94±5.65 mm after operation, P<0.01; P2 was 12.83±3.49 mm before operation and 24.90±7.15 mm after operation. S2 was 4.54±2.84 mm before operation and 19.10±8.54 mm after operation. A2 was 11.46±3.35 mm before operation and 24.15±8.29 mm after operation. The P values were all less than 0.01, and the differences were statistically significant. Conclusions: We propose to use the "VSCU" classification system for accurate 3-dimensional (3D) analysis and positioning, and then obtain accurate models through computer-aided design and manufacturing (CAD/CAM), which can reduce the occurrence of poor reconstruction effect and unreasonable joint position, and is worthy of clinical promotion.

Realizing in-house algorithm-driven free fibula flap set up within 24 hours: a pilot study evaluating accuracy with open-source tools.

Objective: This study aims to critically evaluate the effectiveness and accuracy of a time safing and cost-efficient open-source algorithm for in-house planning of mandibular reconstructions using the free osteocutaneous fibula graft. The evaluation focuses on quantifying anatomical accuracy and assessing the impact on ischemia time. Methods: A pilot study was conducted, including patients who underwent in-house planned computer-aided design and manufacturing (CAD/CAM) of free fibula flaps between 2021 and 2023. Out of all patient cases, we included all with postoperative 3D imaging in the study. The study utilized open-source software tools for the planning step, and three-dimensional (3D) printing techniques. The Hausdorff distance and Dice coefficient metrics were used to evaluate the accuracy of the planning procedure. Results: The study assessed eight patients (five males and three females, mean age 61.75 ± 3.69 years) with different diagnoses such as osteoradionecrosis and oral squamous cell carcinoma. The average ischemia time was 68.38 ± 27.95 min. For the evaluation of preoperative planning vs. the postoperative outcome, the mean Hausdorff Distance was 1.22 ± 0.40. The Dice Coefficients yielded a mean of 0.77 ± 0.07, suggesting a satisfactory concordance between the planned and postoperative states. Dice Coefficient and Hausdorff Distance revealed significant correlations with ischemia time (Spearman's rho = -0.810, p = 0.015 and Spearman's rho = 0.762, p = 0.028, respectively). Linear regression models adjusting for disease type further substantiated these findings. Conclusions: The in-house planning algorithm not only achieved high anatomical accuracy, as reflected by the Dice Coefficients and Hausdorff Distance metrics, but this accuracy also exhibited a significant correlation with reduced ischemia time. This underlines the critical role of meticulous planning in surgical outcomes. Additionally, the algorithm's open-source nature renders it cost-efficient, easy to learn, and broadly applicable, offering promising avenues for enhancing both healthcare affordability and accessibility.

In vivo wear determination of novel CAD/CAM ceramic crowns by using 3D alignment.

PURPOSE: To determine wear amount of single molar crowns, made from four different restoratives, and opposing natural teeth through computerized fabrication techniques using 3D image alignment. MATERIALS AND METHODS: A total of 24 single crowns (N = 24 patients, age range: 18 - 50) were made from lithium disilicate (IPS E-max CAD), lithium silicate and zirconia based (Vita Suprinity CAD), resin matrix ceramic material (Cerasmart, GC), and dual matrix (Vita Enamic CAD) blocks. After digital impressions (Cerec 3D Bluecam, DentsplySirona), the crowns were designed and manufactured (Cerec 3, DentsplySirona). A dual-curing resin cement was used for cementation (Variolink Esthetic DC, Ivoclar). Then, measurement and recording of crowns and the opposing enamel surfaces with the intraoral scanner were made as well as at the third and sixth month follow-ups. All measurements were superimposed with a software (David-Laserscanner, V3.10.4). Volume loss due to wear was calculated from baseline to follow-up periods with Siemens Unigraphics NX 10 software. Statistical analysis was accomplished by Repeated Measures for ANOVA (SPSS 21) at = .05 significance level. RESULTS: After 6 months, insignificant differences of the glass matrix and resin matrix materials for restoration/enamel wear were observed (P>.05). While there were no significant differences between the glass matrix groups (P>.05), significant differences between the resin matrix group materials (P<.05) were obtained. Although Cerasmart and Enamic were both resin matrix based, they exhibited different wear characteristics. CONCLUSION: Glass matrix materials showed less wear both on their own and opposing enamel surfaces than resin matrix ceramic materials.

CAD/CAM for scalable nanomanufacturing: A network-based system for hybrid 3D printing.

Micro- and nano-structuring have been highlighted over several decades in both science and engineering fields. In addition to continuous efforts in fabrication techniques, investigations in scalable nanomanufacturing have been pursued to achieve reduced feature size, fewer constraints in terms of materials and dimensional complexity, as well as improved process throughput. In this study, based on recent micro-/nanoscale fabrication processes, characteristics and key requirements for computer-aided design and manufacturing (CAD/CAM) systems for scalable nanomanufacturing were investigated. Requirements include a process knowledge database, standardized processing, active communication, adaptive interpolation, a consistent coordinate system, and management of peripheral devices. For scalable nanomanufacturing, it is important to consider the flexibility and expandability of each process, because hybrid and bridging processes represent effective ways to expand process capabilities. As an example, we describe a novel CAD/CAM system for hybrid three-dimensional (3D) printing at the nanoscale. This novel hybrid process was developed by bridging aerodynamically focused nanoparticle printing, focused ion beam milling, micromachining, and spin-coating processes. The system developed can print a full 3D structure using various inorganic materials, with a minimum process scale of 50 nm. The most obvious difference versus CAD/CAM at 'conventional' scales is that our system was developed based on a network to promote communication between users and process operators. With the network-based system, it is also possible to narrow the gap among different processes/resources. We anticipate that this approach can contribute to the development of CAD/CAM for scalable nanomanufacturing and a wide range of hybrid processes.