The Effects of Distribution of Image Matched Fiducial Markers on Accuracy of Computer‐Guided Implant Surgery

Abstract

PurposeImage registration of the optical intraoral scan to computed tomography image is essential for computer‐guided implant surgery. The remaining teeth, which are considered to be congruent structures observed in the scan and radiographic images, are used to perform the image registration. The purpose of this study was to evaluate the effects of the distribution of matching fiducial points on the accuracy of the image registration.Materials and MethodsA partially edentulous model with three anterior remaining teeth was prepared. Two mini dental implants were inserted in the posterior edentulous areas on both sides, and computed tomography and surface scan data were obtained. Three groups were set according to the distribution of the image matching points used: localized distribution, unilateral distribution, and bilateral distribution. Fifteen graduate students performed the registration process in each group using the same image matching method. The accuracy of image registration was evaluated by measuring the geometric discrepancies between the radiographic and registered scan images in the anterior, middle, and posterior regions. One‐way and two‐way analysis of variance with the Tukey HSD post hoc test were used for statistical analysis (α = 0.05)ResultsIn general, the registration discrepancy was lowest in the bilateral distribution group, followed by the unilateral distribution and localized distribution groups (p< 0.001). In the regional analysis, the registration error tended to increase as the measurement region moved farther from the matching points. The distribution of the matching points and measurement regions had a statistical interaction in the accuracy of image registration.ConclusionThe accuracy of image registration of the surface scan to the computed tomography is affected by the matching point distribution that can be improved by placing artificial markers in the edentulous areas.

Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan

“…The surface-based matching uses the computer algorithm of iterative closest points (ICPs) that locates paired images in optimal positions by computing the 3D coordinates of the geometrical shape of 3D object surfaces to align images [17,22]. When the image surface point clouds that are used for matching are widely spread in the oral cavity, the matching condition is favorable, and the whole accuracy of image registration can be increased [15,33]. In the present study, a significant correlation was found between the threshold of gray value factor and the number of remaining teeth on the registration accuracy.…”

Repeatability of Freehand Implantations Supported with Universal Plastic Sleeves—In Vitro Study

“…Analysis of in vitro studies and systematic review, as well as multicenter clinical trials and randomized controlled trials, lead to the conclusion that using individual guides may be the best way to achieve elevated accuracy and remain in line with the treatment plan [7,8,[10][11][12][13][14]. However, limited surgical access especially in the distal area of the alveolar ridge with surgical guides intraorally, may be one of the most common challenges in using surgical guides [4,14].…”

“…A number of studies show that users of CAD/CAM (Computer-aided design/Computer-aided manufacturing) surgical guides may experience problems with accuracy and repeatability of dental implantation procedures [2][3][4][5][6][7][8]. In the literature we can also find descriptions of a few problems with clinical application of guides (e.g., the guide fixation, its stability and limited mouth opening) [9,10]. Hence several surgical kits were introduced to help clinicians with proper implant positioning when a digital guide is not available.…”

Considerations for predictable outcomes in static computer‐ aided implant surgery in the esthetic zone

“…Hence, a misalignment of the STL/OBJ/PLY and DICOM files will not influence the surgical template fitting nor the sleeve position, but the final implant position will be different from the one observed in the bone. 17,46 Incorrect alignment of the merged files usually occurs when the number of common reference areas is insufficient. A lack of reference areas can be observed when the CBCT is performed with upper and lower teeth in occlusion or if metal artifacts are present.…”