Digitally Designed Surgical Guides for Placing Extraoral Implants in the Mastoid Area

Purpose: When planning implant therapy, knowledge of the bone volume in the implant area is needed to plan and place implants in the most appropriate locations from the prosthetic and surgical perspectives. Commercial software for digital planning of implants in the craniofacial region is not yet available. This article describes a method that enables digital planning of extraoral implants in the mastoid region utilizing commercially available computer-aided design (CAD) software and rapid-prototyping techniques to manufacture a corresponding surgical guide. Materials and Methods: With the aid of CAD software designed for reverse engineering and three-dimensional animation, digital implant planning based on cone beam computed tomography (CBCT) scanning was performed. On the basis of this planning, surgical guides were digitally designed to facilitate the placement of dental implants in the mastoid area. The guides were fabricated using rapid prototyping. The appropriateness of the digitally designed surgical guides for placing extraoral implants was tested on six human cadaver heads with simulated bilateral ear defects. After implant placement, a second CBCT scan was performed to compare preoperative planning with the actual postoperative implant positions. Results: Twenty-four implants were placed. The surgical guide helped the surgeon to place the implants at the preoperatively planned positions. Comparison of the CBCT scans revealed that adequate accuracy of implant placement was achieved, both for deviation of the neck (1.56 +/- 0.56 mm) and the tip (1.40 +/- 0.53 mm) of the implant, and for deviation of the angulation of the implant (0.97 +/- 2.33 deg). Conclusion: The presented method for digitally planning extraoral implants in the mastoid area and designing surgical guides allows for placement of implants in the mastoid area in close proximity to the preoperatively planned implant position. The actual implant positions were satisfactory both surgically and prosthetically. INT J ORAL MAXILLOFAC IMPLANTS 2012;27:703-707

Validity, reliability, and reproducibility of linear measurements on digital models obtained from intraoral and cone-beam computed tomography scans of alginate impressions

<p>Introduction: Digital 3-dimensional models are widely used for orthodontic diagnosis. The aim of this study was to assess the validity, reliability, and reproducibility of digital models obtained from the Lava Chairside Oral scanner (3M ESPE, Seefeld, Germany) and cone-beam computed tomography scans of alginate impressions for tooth-width measurements and the Bolton analysis. Methods: A digital model, an intraoral scan, and a plaster model were made for each of 22 subjects. Tooth-width measurements on the digital model and the intraoral scan were compared with those on the corresponding plaster models (gold standard). Intraclass correlation coefficients were calculated to determine the interexaminer reliability of the measurements of each method. The anterior and overall Bolton ratios were calculated for each participant and for each method. The paired t test was used to determine the validity. The scanning time for the intraoral scanner was registered and analyzed. Results: Tooth-width measurements of each tooth on the digital models and the intraoral scans did not differ significantly from those on the plaster models (P >0.05). The overall and anterior Bolton ratios from the 2 types of digital models differed significantly from the gold standard (P</p>

Digitally Designed Surgical Guides for Placing Implants in the Nasal Floor of Dentate Patients:A Series of Three Cases

Purpose: Insight into the bone volume and position of natural teeth is essential when placing implants to retain nasal prostheses. This paper describes a series of three cases in which a new method was applied for implant placement in the nasal floor of dentate patients using digital planning techniques. Materials and Methods: With the aid of computer software, digital planning of implants in the nasal floor based on cone beam computed tomography was performed. Next, surgical guides for implant placement were digitally designed and fabricated using rapid prototyping. Results: In all three patients, implants could be placed and nasal prostheses could be manufactured as planned. All anterior teeth remained vital. Analysis of planning and post-implant placement cone beam computed tomography scans revealed high accuracy of implant placement. Conclusion: The applied method allows for reliable implant placement in close proximity to the preoperatively planned implant position. lot J Prosthodont 2012;25:245-251