Eneko Solaberrieta

Direct transfer of the position of digitized casts to a virtual articulator

This article describes a digital technique to transfer the location of digitized casts obtained directly from the patient to a virtual articulator (digital/virtual facebow transfer). The primary advantage of this technique is that it allows the dentist and the dental laboratory technician to work in a fully digital environment without having to mount stone casts on a physical articulator. This results in a significant time reduction and a higher degree of accuracy in the cast location.

Comparison of the accuracy of a 3-dimensional virtual method and the conventional method for transferring the maxillary cast to a virtual articulator

STATEMENT OF PROBLEM The currently available virtual articulators fail to locate the digitized maxillary cast at the exact position in the virtual environment. Some locate the casts on a mechanical articulator with a facebow, and this position is then digitized for the virtual environment. PURPOSE The purpose of this study was to compare the location of the maxillary cast on an articulator by using 2 different procedures: the conventional method and a virtual method. MATERIAL AND METHODS With the conventional procedure, the kinematic axis of the participant was determined with an axiograph. The location of the maxillary cast in reference to this axis was then physically transferred to a Panadent mechanical articulator. By a virtual procedure, the same kinematic axis and the maxillary cast were transferred directly from the participant to the Panadent virtual articulator by means of reverse engineering devices. The locations obtained with both procedures were compared in a virtual environment with an optical scanner. By calculating the deviation at every point of the occlusal surface, the results obtained with this procedure were then compared with those of the conventional method. RESULTS The mean deviation on the occlusal surface was 0.752 mm, and the standard deviation was 0.456 mm. CONCLUSIONS The deviation between the procedures was sufficiently small to allow the methodology for orthodontic purposes. However, the accuracy of the virtual procedure should be improved so as to extend its use to other fields, such as orthognathic surgery or dental restorations, in which the clinical technique requires an articulator.

Comparison of a conventional and virtual occlusal record

STATEMENT OF PROBLEM Conventional methods associated with many processes in dentistry are being replaced by methods that use digital technology. One of these processes is the making of occlusal records for the positioning of casts in a virtual articulator. Conventional interocclusal records and the articulator are being replaced by the virtual occlusal record and the virtual articulator. PURPOSE The purpose of this study was to validate a virtual procedure to locate the mandibular cast in a 3-dimensional (3D) spatial position and to verify the occlusal contact points in reference to the corresponding maxillary cast on a virtual articulator. MATERIAL AND METHODS The conventional procedure was carried out by locating 6 sets of casts in maximal intercuspal position without any interocclusal record. Then, the occlusal contacts were determined with articulating paper. Subsequently, the occlusal relationships and stone cast were digitized with a 3D scanner. The occlusal contacts were compared with photographs and by superimposing these on screenshots of the software. Finally, the deviation of discrete points on the mandibular cast was calculated, and all the points of the occlusal surface were compared point by point. RESULTS This study analyzed the main variables of the virtual occlusal record by using 3 current reverse engineering software packages. The results show a mean deviation of 0.069 mm from the virtual occlusion procedure and a mean standard deviation of 0.011 mm from all the points of the occlusal surface. CONCLUSIONS The main conclusion of this study was that the accuracy provided by a virtual occlusion procedure is greater than that of the traditional physical interocclusal record. Additionally, knowing the deviation of each alignment (best-fit operation or algorithm) is useful.

Improved digital transfer of the maxillary cast to a virtual articulator

The clinical procedure described provides a quantifiable, repeatable, and reliable method of transferring the location of the maxillary dental arch from the patient directly to a virtual articulator (virtual facebow transfer) by means of reverse engineering devices to design a customized dental restoration. This procedure allows the dentist and the dental laboratory technician to work in a fully digital environment without having to mount stone casts on a mechanical articulator. In addition, specific suggestions are provided for designing the transfer device to enhance patient comfort during the data transfer process and reduce deviation.

Intraoral Digital Impressions for Virtual Occlusal Records: Section Quantity and Dimensions

The purpose of this study was to locate the 3D spatial position mandibular cast and determine its occlusal contacts in a novel way by using an intraoral scanner as part of the virtual occlusal record procedure. This study also analyzes the requirements in quantity and dimensions of the intraoral virtual occlusal record. The results showed that the best section combination consists of 2 lateral and frontal sections, the width of this section being that of 2 teeth (24 mm × 15 mm). This study concluded that this procedure was accurate enough to locate the mandibular cast on a virtual articulator. However, at least 2 sections of the virtual occlusal records were necessary, and the best results were obtained when the distance between these sections was maximum.

Virtual facebow technique.

This article describes a virtual technique for transferring the location of a digitized cast from the patient to a virtual articulator (virtual facebow transfer). Using a virtual procedure, the maxillary digital cast is transferred to a virtual articulator by means of reverse engineering devices. The following devices necessary to carry out this protocol are available in many contemporary practices: an intraoral scanner, a digital camera, and specific software. Results prove the viability of integrating different tools and software and of completely integrating this procedure into a dental digital workflow.

Determining the requirements, section quantity, and dimension of the virtual occlusal record

STATEMENT OF PROBLEM Conventional methods associated with many processes in dentistry are being replaced by methods that use digital technology. One of these processes is the making of occlusal records for the positioning of casts in a virtual articulator. Conventional interocclusal records and the articulator are currently being replaced by the intraoral virtual occlusal record and the virtual articulator. PURPOSE The purpose of this study was to determine the requirements, quantity, and dimensions of the virtual occlusal record procedure in order to locate the mandibular casts 3-dimensional (3D) spatial position in reference to its corresponding maxillary cast on a virtual articulator. MATERIAL AND METHODS For the conventional procedure, 6 sets of casts were located in maximal intercuspal position without any interocclusal record. Then, using articulating paper, the occlusal contacts were determined. Afterward, the occlusal relationships and stone cast were digitized with a 3D scanner. To locate the maxillary cast, the occlusal contacts were compared by taking different sections as the virtual occlusal record. Finally, the optimum dimension of the virtual occlusal record was determined. RESULTS This study determines the requirements, quantity, and dimensions of the virtual occlusal record using current reverse engineering tools. The combinations of the sections were first determined as follows: 3 sections (2 lateral and 1 frontal) and 2 lateral sections proved to be the most accurate. Then, the predictive values (PV) for dimension determination for the left-right lateral combination were calculated. CONCLUSIONS The main conclusion of this study was that the combination of left and right lateral occlusal records was the most convenient. Additionally, the minimum optimum dimension for a virtual occlusal record was 12×15 mm.

Computer-aided dental prostheses construction using reverse engineering.

The implementation of computer-aided design/computer-aided manufacturing (CAD/CAM) systems with virtual articulators, which take into account the kinematics, constitutes a breakthrough in the construction of customised dental prostheses. This paper presents a multidisciplinary protocol involving CAM techniques to produce dental prostheses. This protocol includes a step-by-step procedure using innovative reverse engineering technologies to transform completely virtual design processes into customised prostheses. A special emphasis is placed on a novel method that permits a virtual location of the models. The complete workflow includes the optical scanning of the patient, the use of reverse engineering software and, if necessary, the use of rapid prototyping to produce CAD temporary prostheses.

Fracture Resistance of Monolithic High Translucency Zirconia Implant-Supported Crowns.

Aim:To evaluate the resistance to axial forces of screw-retained monolithic high translucency zirconia (mHTZr) crowns compared with high translucency zirconia + feldspathic ceramic (HTZrC) crowns, low translucency zirconia + feldspathic ceramic (LTZrC) crowns, and metal-ceramic (MC) crowns, and also to observe the different fracture patterns between all groups. Methods:Twenty-four crowns were fabricated (6 of each group) and loaded until failure, using a testing machine with a 5.0-kN load cell. Results:Mean fracture results varied between 1092.7 N (LTZrC group) and 3439.7 N (mHTZr group). No statistically significant differences were found between the HTZrC, LTZrC, and MC groups. However, statistically significant differences (P < 0.05) were found between mHTZr and the other 3 groups. In the MC group, only chipping of the ceramic veneering occurred. In the mHTZr group, when fracturing occurred, it was of the whole structure. Finally, the LTZrC and HTZrC groups suffered both chipping and core fractures. Conclusion:High translucency monolithic zirconia implant–supported crowns proved to be the toughest group studied when an axial force was applied. Fracture patterns varied between different materials, chipping being the most common occurrence.

Customized procedure to display T-Scan occlusal contacts

The virtual technique described in this article integrates reverse engineering and mandibular dynamics into dental computer-aided design and computer-aided manufacturing (CAD-CAM) systems. This technique aims to provide more objective information to the dental technician for the diagnosis, planning, and treatment phases. In order to carry out this protocol, the following devices, currently available in many practices, are necessary: an intraoral scanner, a T-Scan system, and some specific open reverse engineering software. By means of a virtual procedure, the T-Scan system detects the occlusal contacts, and the occlusal surfaces are obtained using an intraoral scanner. Once the alignment between the 3-dimensional occlusal surface and the T-Scan registration is carried out, the resulting contacts are projected onto the patients occlusal surfaces; in this way, occlusal forces are obtained over time. The results obtained with this procedure demonstrate the feasibility of integrating different tools and software and the full integration of this procedure into a dental digital workflow.