The accuracy of three-dimensional model generation. What makes it accurate to be used for surgical planning?

Generation of virtual models for planning orthognathic surgery using a modified multimodal image fusion technique

“…Since then, various registration systems designed to integrate the 3D images of skeletal and dental datasets have been developed. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][18][19][20] The metal materials commonly used in dental treatment cause degradation of the CT images, which may disturb accurate Virtual models for planning orthognathic surgery 5 registration of the skeletal and dental images; this occurs as a result of streak artefacts caused by dental metals during CT scanning. In addition, non-metal materials, such as zirconia and composite resins containing rare earth elements, also cause metal artefacts.…”

“…Recent rapidly developing computer technology has provided us with a new powerful tool for diagnosing facial and jaw deformities (computer-assisted diagnosis), [1][2][3][4][5][6][7][8][9][10][11] and for planning [12][13][14][15][16][17] and guiding surgical interventions (computer-assisted surgery). [18][19][20] Although computed tomography (CT), from which virtual skull models with dentition are generated, is a fundamental procedure in computer-assisted diagnosis and surgery, it has several disadvantages: (1) limited spatial resolution and partial volume-averaging effects of CT cause image distortion, especially when small anatomical details such as the occlusal surface of teeth are scanned; (2) the threshold condition influences the morphology of the teeth and cranial bones; and (3) information about the occlusal surface is lost if the CT scan is performed with the teeth in occlusion.…”

“…[18][19][20] Although computed tomography (CT), from which virtual skull models with dentition are generated, is a fundamental procedure in computer-assisted diagnosis and surgery, it has several disadvantages: (1) limited spatial resolution and partial volume-averaging effects of CT cause image distortion, especially when small anatomical details such as the occlusal surface of teeth are scanned; (2) the threshold condition influences the morphology of the teeth and cranial bones; and (3) information about the occlusal surface is lost if the CT scan is performed with the teeth in occlusion. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][18][19][20] Therefore, the image quality obtained from CT scanning only is not sufficient to precisely represent tooth configuration and intercuspation, which is a definite disadvantage for predicting jaw position after orthognathic surgery. To overcome these problems, an image-fusion technique, [21][22][23] in which a virtual skull model obtained from CT scanning and a virtual dental model obtained from laser scanning of a dental cast or CT scanning of an impression, was introduced into threedimensional (3D) reconstruction methods to diagnose skeletal deformities.…”

“…To overcome these problems, an image-fusion technique, [21][22][23] in which a virtual skull model obtained from CT scanning and a virtual dental model obtained from laser scanning of a dental cast or CT scanning of an impression, was introduced into threedimensional (3D) reconstruction methods to diagnose skeletal deformities. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][18][19][20] In addition to the above-mentioned disadvantages of CT scanning, another significant problem is streak artefacts caused by strongly attenuating objects, i.e., metal artefacts. [24][25][26] The presence of metal restorations, prostheses, dental implants, and orthodontic appliances in the field of view of the CT scan causes the metal artefacts, which may drastically degrade the CT images and limit the application of CT. 2,3,13,[24][25][26] This problem cannot be resolved entirely, even using the imagefusion technique, if the multiple and extensive artefacts extend into the fiducial markers used for image integration, thereby disturbing precise image fusion.…”

Correction of a severe facial asymmetry with computerized planning and with the use of a rapid prototyped surgical template: a case report/technique article

“…The final product of virtual model surgery is a virtual splint that can be materialized by rapid prototyping. This technique relies on the accuracy of the virtual model and the production of the surgical splint to ensure a successful surgery [16]. The intermediate wafer was fabricated with the highest printing accuracy in our case and it proved to be the most reliable tool to transfer virtual surgery into the operating room.…”