OBJECTIVE: This study describes the quality of Thiel soft-embalmed cadavers as training model for endoscopic sinus surgery in terms of color and consistency of the tissues and similarity of performing the surgical steps to live surgery.

METHODS: This is a cross-sectional descriptive study. Six Thiel soft-embalmed cadavers from the University of the Philippines, College of Medicine, Department of Anatomy were used as training models. The Thiel-preserved cadavers utilized the soft embalming protocol being employed at the Virginia State Anatomical Program in Richmond, Virginia, USA. Ten otorhinolaryngologists were recruited to evaluate the cadavers using a questionnaire with three parts. The first two parts utilize a 10-point Likert scale with 1 as the least similar to live patient while 10 as simulating the live patient. The third part is an open-ended question regarding the suitability of Thiel soft-embalmed cadavers in the training for endoscopic sinus surgery.

RESULTS: Endoscopic sinus surgery was successfully performed in all cadavers. The Thiel soft-embalmed cadaver closely replicates the color and consistency of the anatomic structures important in endoscopic sinus surgery. All the surgical steps were performed with ease simulating live surgery.

CONCLUSION: Thiel soft-embalmed cadaver is a suitable model for training in endoscopic sinus surgery.

Models, Anatomic

With the progresses of the research on "Digital Human", more and more information has been needed for the setting up of the three-dimensional digital models of human organs. In the present paper, based on the method of block mapping with a normal-style bump mapping method, we normalized the vector of the surface of the models, computed offset of the texture coordinates and added to them. The projection of the coordinates to the tangential space complemented the disturbance to the vector of models' surface. The method was proposed with bump texture mapping on the surface of the biological models of organs to improve the impression of the visualization of the organ models and to enhance the sense of reality of the models.
Humans ; Models, Anatomic ; Models, Biological

OBJECTIVETo analyze stress distribution in alveolar bone around implants of implant supported overdentures (ISO) with linear occlusion and with anatomic occlusion at lateral mandibular position, and to justify the possibility of decreased injurious force around implants in ISO with linear occlusion.

METHODSComputerized tomography scan and finite element analysis (FEA) were used to set up two 3-D FEA models of maxillae and mandible with severe residual ridge resorption. The mucosa, linear and anatomic occlusal ISO with bar attachments, and two implants inserted between mandibular foramina were also established in the models. With the condition of imitating the loading of masseter muscles, these models were loaded to simulate the stress distributions in alveolar bone around implants under ISO at lateral occlusion position.

RESULTSAt lateral occlusion, the stress distributions in alveolar bone around implants under ISO with anatomic occlusion were mainly on the lingual and distal sides of the working side implants. However, stress distributions under ISO with linear occlusion were on the distal sides of bilateral implants. Both the stress peaks of ISOs with linear occlusion and with the anatomic one appeared in the working side. In anatomic occlusion model, sigma(z): -6.47 MPa and 6.81 MPa, sigma(1): -4.20 MPa and 7.20 MPa (negative value: compressive stress, positive value: tensile stress); in linear occlusion model, sigma(z): -4.86 MPa and 3.04 MPa, sigma(1): -3.48 MPa and 5.33 MPa.

CONCLUSIONSAt lateral occlusion, when comparing the ISO with two different occlusion schemes, stress peak in alveolar bone around implants in the linear occlusion model was lower than that in the anatomic occlusion model at equal loading situation. Stress in the alveolar bone under ISO with linear occlusion distributed more evenly than that under ISO with anatomic occlusion.

Dental Implantation ; Dental Occlusion ; Denture, Complete, Lower ; Finite Element Analysis ; Humans ; Mandible ; physiology ; Models, Anatomic ; Models, Biological ; Stress, Mechanical

PURPOSE: The aim of this study was to determine the influence of anatomical conditions on primary stability in the models simulating posterior maxilla. METHODS: Polyurethane blocks were designed to simulate monocortical (M) and bicortical (B) conditions. Each condition had four subgroups measuring 3 mm (M3, B3), 5 mm (M5, B5), 8 mm (M8, B8), and 12 mm (M12, B12) in residual bone height (RBH). After implant placement, the implant stability quotient (ISQ), Periotest value (PTV), insertion torque (IT), and reverse torque (RT) were measured. Two-factor ANOVA (two cortical conditions×four RBHs) and additional analyses for simple main effects were performed. RESULTS: A significant interaction between cortical condition and RBH was demonstrated for all methods measuring stability with two-factor ANOVA. In the analyses for simple main effects, ISQ and PTV were statistically higher in the bicortical groups than the corresponding monocortical groups, respectively. In the monocortical group, ISQ and PTV showed a statistically significant rise with increasing RBH. Measurements of IT and RT showed a similar tendency, measuring highest in the M3 group, followed by the M8, the M5, and the M12 groups. In the bicortical group, all variables showed a similar tendency, with different degrees of rise and decline. The B8 group showed the highest values, followed by the B12, the B5, and the B3 groups. The highest coefficient was demonstrated between ISQ and PTV. CONCLUSIONS: Primary stability was enhanced by the presence of bicortex and increased RBH, which may be better demonstrated by ISQ and PTV than by IT and RT.
Dental Implants ; In Vitro Techniques* ; Maxilla* ; Maxillary Sinus ; Models, Anatomic ; Polyurethanes ; Torque

PURPOSE: Sufficient area in the interforaminal region is required for dental implant placement, and the anterior loop of the mandibular canal is located within the limits of this area. The aim of this study was to evaluate the prevalence and extent of the anterior loop in a Brazilian sample population using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT images from 250 patients (500 hemimandibles) obtained for various clinical indications were randomly selected and evaluated to determine the presence and length of the anterior loop. The length of the anterior loop was then compared based on gender, age, and the side of the mandible. The data were analyzed using the Pearson chi-square test and linear regression analysis. RESULTS: An anterior loop was identified in 41.6% of the cases, and its length ranged from 0.25 mm to 4.00 mm (mean, 1.1±0.8 mm). The loop had a greater mean length and was significantly more prevalent in males (p=0.014). No significant differences were found between the right and left sides regarding length (p=0.696) or prevalence (p=0.650). CONCLUSION: In this study, a high prevalence of the anterior loop of the mandibular canal was found, and although its length varied greatly, in most cases it was less than 1 mm long. Although this is a prevalent anatomical variation, safety limits for the placement of implants in this region cannot be established before an accurate evaluation using imaging techniques in order to identify and preserve the neurovascular bundles.
Anatomic Variation ; Cone-Beam Computed Tomography* ; Dental Implants ; Humans ; Linear Models ; Male ; Mandible ; Prevalence

OBJECTIVETo look for the way of three-dimensional simulation of the craniofacial system.

METHODSA three-dimensional laser scanner was used for gypsum models digitization and computed tomography scans was employed for skull reconstruction, then the data of teeth and temporomandibular joint were picked up and integrated. The ARCUS sigma system was used to record spatial mandibular movements. The data of both digital reconstruction and spatial movements were transferred into one coordinate system. The software for three-dimensional simulation was programmed.

RESULTSThe preliminary program could be used to analyze static and dynamic occlusion and gnathic relations, to check the contact points and to show from various visual angles and slices. The occlusal plane, curves, and helical axis were initially defined and displayed.

CONCLUSIONSUsing available instruments and methods, we developed the primary edition for three-dimensional simulation of the craniofacial system. However, it is far from a mature system and there is still plenty of work to be done.

Dental Occlusion ; Humans ; Imaging, Three-Dimensional ; Mandible ; physiology ; Models, Anatomic ; Skull ; Temporomandibular Joint ; physiology ; Tooth

OBJECTIVETo develop a three-dimensional multimedia system for enhancing the efficiency of dental education and chairside communication.

METHODSA set of three-dimensional digital models of normal teeth and jaws related to dental education in prosthodontics were acquired or established under Microsoft Windows. The three-dimensional models were re-edited and rendered with texture attached, producing a large number of three-dimensional pictures and short animated pictures. A software platform was established for displaying all sorts of media, including the three-dimensional models. Finally, all media files produced or gathered before were integrated into the platform, similar to the textbook in chapter adopted in dental education at university.

RESULTSThe prosthodontic three-dimensional multimedia system was successfully developed. The system covered basic information within the current textbook of prosthodontics, three-dimensional pictures, animated pictures, and virtual three-dimensional scenes. The system might serve as an assistant tool in dental education and chairside communication.

CONCLUSIONSIt is technically feasible to establish the prosthodontic three-dimensional multimedia system, according to experiences in this study. The success also anticipates the possibility and feasibility of developing similar systems in other disciplines of dentistry.

Education, Dental ; methods ; Humans ; Models, Anatomic ; Multimedia ; Prosthodontics ; education ; Software Design

PURPOSE: This study aimed to evaluate the effects of i) the extent of peri-implant bone defects and ii) the application of bone cement on implant stability with respect to the measurement direction. METHODS: In 10 bovine rib bones, 4 implant osteotomies with peri-implant bone defects of various widths were prepared: i) no defect (D0), ii) a 2-mm-wide defect (D2), iii) a 4-mm-wide defect (D4), and iv) a 8-mm-wide defect (D8). The height of all defects was 10 mm. Implant stability quotient (ISQ) values and Periotest values (PTVs) were measured after implant placement and bone cement application. RESULTS: With increasing defect width, decreased ISQs and increased PTVs were observed. Statistically significant differences were found between groups D0 and D8, D0 and D4, and D2 and D8. Prior to bone cement application, inconsistent PTVs were found in group D8 depending on the measurement direction. Bone cement increased the implant stability. CONCLUSION: Peri-implant bone deficits measuring around 50% of the implant surface compromised implant stability. Clinically, PTVs should be cautiously interpreted in implants with large peri-implant defects due to inconsistent recordings with respect to the measurement direction.
Alveolar Bone Loss ; Bone Transplantation ; Dental Implants ; In Vitro Techniques ; Models, Anatomic ; Osteotomy ; Ribs

In plastic and reconstructive craniomaxillofacial surgery, careful preoperative planning is essential to get a successful outcome. Many craniomaxillofacial surgeons have used imaging modalities like conventional radiographs, computed tomography(CT) and magnetic resonance imaging(MRI) for supporting the planning process. But, there are a lot of limitations in the comprehension of the surgical anatomy with these modalities. Medical models made with rapid prototyping (RP) technique represent a new approach for preoperative planning and simulation surgery. With rapid prototyping models, surgical procedures can be simulated and performed interactively so that surgeon can get a realistic impression of complex structures before surgical intervention. The great advantage of rapid prototyping technique is the precise reproduction of objects from a 3-dimensional reconstruction image as a physical model. Craniomaxillofacial surgeon can establish treatment strategy through preoperative simulation surgery and predict the postoperative result.
Comprehension ; Models, Anatomic ; Plastics ; Reproduction

OBJECTIVETo establish anisotropic mandible model with dental implants and to investigate the effect of anisotropy material on stress and strain distribution of implant-bone interface.

METHODSThree-dimensional finite element models of whole mandible with anisotropic and equivalent isotropic material were created by CT scanning and universal surgical integration system (USIS) software developed by the authors. Two ITI threaded implants were implanted in the posterior teeth area. The values of principal stress and principal strain on the bone around dental implants were calculated in two different finite element models with buccolingual load.

RESULTSIn the anisotropic mandible model, nearly all values of the principal stress and principal strain on cortical and cancellous bone increased compared with the equivalent isotropy model, 2.1%-74.1% for principal stress and 4.7%-57.3% for principal strain, but 10. 3%-71.4% for principal stress and 19.5%-63.4% for principal strain on cancellous bone.

CONCLUSIONSIn the three-dimensional finite element analysis, anisotropic mandible model with dental implants has an apparent effect on the stress and strains of the implant-bone interface. Anisotropic mechanical properties of mandible should be emphasized in biomechanical study.

Dental Implantation, Endosseous ; methods ; Dental Implants ; Dental Prosthesis Design ; Dental Stress Analysis ; Finite Element Analysis ; Mandible ; Models, Anatomic ; Stress, Mechanical