Application of a new scan body for face-driven fixed prosthetics.

OBJECTIVE: The current method of digitally designing dental prostheses mainly focuses on intra-oral soft and hard tissues, although the harmony of the facial soft tissue and the prosthesis is crucial, especially for esthetics. Here, we introduce a new method of digitally designing dental prostheses using a new device that generates a virtual patient and incorporates facial features into the prosthetic design. MATERIALS AND METHODS: A new extra-oral scan body for facial scanning was designed and developed. A definitive edentulous maxilla implant cast with four extra-oral scan bodies (regions: maxillary left and right lateral incisors, maxillary left and right premolars) was placed in the mouth of a dental mannequin. The dental mannequin was scanned with and without the extra-oral scan bodies. For reference data, an impression of the maxilla was taken and scanned with a laboratory scanner. By superimposing each acquired data, a virtual patient was generated, and the spatial location of the abutments relative to the face was clarified. Identifying the accurate location of the abutments enabled to design face-driven dental prosthesis. RESULTS: Based on the color-coded deviation map created by the data acquired from conventional and extra-oral scan bodies, the divergence of the two data was mostly within 0.1 mm, which proves that the extra-oral scan bodies were as accurate as conventional scan bodies. Therefore, the facial scan data and the scan data of the oral cavity were successfully superimposed, which allowed to generate a virtual patient to design face-driven prosthesis. CONCLUSION: The new method is effective for designing high-quality face-driven prostheses, especially when treating a patient with a full-arch implant-fixed prosthesis.

Custom-made titanium devices as membranes for bone augmentation in implant treatment: Clinical application and the comparison with conventional titanium mesh.

OBJECTIVE: Development of new custom-made devices to reconstruct alveolar bone for implantation, and comparison with conventional methods were the goals of this study. MATERIALS AND METHODS: Using a computer-aided design technique, three-dimensional images were constructed. From these data, custom-made devices were produced by a selective laser melting method with pure titanium. Clinical trials also have been conducted with 26 participants who needed bone reconstruction before implantation; they were divided into 2 groups with 13 patients each. The first group uses custom-made devices; the other uses commercial titanium meshes that need to bend during operation. Some clinical aspects are evaluated after the trial. RESULTS: The custom-made devices can be produced closely by following the data precisely. Devices are fit for bone defect site. Moreover, the operation time of the custom-made group (75.4 ± 11.6 min) was significantly shorter than that of the conventional group (111.9 ± 17.8 min) (p < 0.01). Mucosal rupture occurs, without significant difference (p = 0.27), in a patient in the custom-made without severe infection (7.7%), and 3 in conventional (23.1%), respectively. The retaining screw is significantly fewer in the custom-made group than commercial mesh group (p < 0.01). CONCLUSION: These results indicate that our novel protocol could be simple and safe for providing powerful support for guided bone regeneration.

A Clinical Investigation of Oral Sarcomas at Multi-institutions Over the Past 30 Years.

BACKGROUND/AIM: Sarcoma of the oral cavity is rare accounting for around 1% of all malignant oral tumors. The purpose of this study was to find important prognostic factors for patients with oral sarcoma. PATIENTS AND METHODS: The study included 1,643 patients examined from April 1980 to March 2010 at the Departments of oral and maxillofacial surgery at multi-institutions who had a histopathological diagnosis of malignant oral tumors. RESULTS: Sarcoma accounted for 19 of 1,643 cases (1.16%) in malignant oral tumors. Histologically, osteosarcoma was most common in 6 of the 19 patients, followed by 3 cases each of leiomyosarcoma and malignant fibrous histiocytoma, 2 of rhabdomyosarcoma and 1 each of angiosarcoma, Ewing's sarcoma, malignant schwannoma, malignant rhabdoid tumor and undifferentiated sarcoma. Irrespective of the histological type, tumor diameter on initial examination was >50 mm in 8 patients, 7 of whom died. Tumor diameter was <50 mm in 11 patients, 6 of whom survived. Distant metastasis was present in 11 patients, 10 of whom died. The local control rate was 42.1% and 5-year survival rate was 36.8%. CONCLUSION: Treatment of patients with tumors over 50-mm long in diameter and distant metastasis is extremely difficult. The incidence of oral sarcoma is very low. However, tumor diameter and presence of distant metastasis are important prognostic factors for oral sarcoma according to this multi-institutional study.

Custom-made titanium devices as membranes for bone augmentation in implant treatment: Modeling accuracy of titanium products constructed with selective laser melting.

OBJECTIVE: The purpose of this study was to verify the modeling accuracy of various products, and to produce custom-made devices for bone augmentation in individual patients requiring implantation. MATERIALS AND METHODS: Two-(2D) and three-dimensional (3D) specimens and custom-made devices that were designed as membranes for guided bone regeneration (GBR) were produced using a computer-aided design (CAD) and rapid prototyping (RP) method. The CAD design was produced using a 3D printing machine and selective laser melting (SLM) with pure titanium (Ti) powder. The modeling accuracy was evaluated with regard to: the dimensional accuracy of the 2D and 3D specimens; the accuracy of pore structure of the 2D specimens; the accuracy of porosity of the 3D specimens; and the error between CAD design and the scanned real product by overlapped images. RESULTS: The accuracy of the 2D and 3D specimens indicated precise results in various parameters, which were tolerant in ISO 2768-1. The error of overlapped images between the CAD and scanned data indicated that accuracy was sufficient for GBR. In integrating area of all devices, the maximum and average error were 292 and 139 µm, respectively. CONCLUSIONS: High modeling accuracy can be achieved in various products using the CAD/RP-SLM method. These results suggest the possibility of clinical applications.