Guided Access Cavity Preparation Using Cost-Effective 3D Printers.

INTRODUCTION: The purpose of this in vitro study was to evaluate the accuracy and precision of desktop 3D printers when fabricating stents for guided endodontics. METHODS: A stent was designed using planning software for guided endodontic access on a typodont model. Four different 3D printers were used to fabricate an identical stent, one per printer. Each stent was then used to gain access to the artificial endodontic canal on a typodont tooth and was repeated 10 times per stent by the same operator. Each of the accessed typodont teeth were scanned by a reference scanner and then imported into the inspection software. Inspection software used a best-fit alignment to automatically calculate absolute deviation at the base and tip of the bur. RESULTS: The mean distances between the planned and actual positions of the bur were low, ranging from 0.31 to 0.68 mm. Statistically significant differences were found among the 4 groups (F3,36 = 10.67, P < .05). Post hoc comparison revealed that Group Form2 significantly varied from Groups Form3 and Carbon (P < .05 and P < .05, respectively). Group Form3 obtained the most accurate and most precise axial deviations both coronally and apically. CONCLUSIONS: All of the printers tested produced stents for guided access that allowed for a high level of accuracy in obtaining access to the artificial endodontic canal, which would justify the trial of cost-effective 3D printers for guided endodontic access and necessitates further clinical research on teeth with pulp canal obliteration.

Surgical Template Fabrication Using Cost-Effective 3D Printers.

PURPOSE: This in vitro study aimed to evaluate the accuracy of surgical templates fabricated using three different 3D printing technologies. MATERIALS AND METHODS: Ten identical surgical templates were printed using four 3D printers (two of an identical make and model). Each of the surgical templates was scanned by a reference scanner and then imported into the inspection software. Inspection software utilized a best-fit alignment to automatically calculate the 3D variation at all points. RESULTS: Statistically significant differences were found among the three groups (χ2[2] = 12.880, P = .0016). Mean 3D deviation was also significantly different between the two printers of an identical make and model (χ2[1] = 8.251, P = .0041). CONCLUSION: All of the tested printers had a high level of accuracy in the fabrication of surgical templates, which would justify the trial of cost-effective printers for clinical fabrication of surgical implant templates.

Dimensional accuracy of cone beam CT with varying angulation of the jaw to the X-ray beam.

OBJECTIVES: Cone beam CT (CBCT) machines do not always allow for patients to be scanned in the ideal position for image acquisition. This study aimed to investigate the influence of the position/angulation of the mandible relative to the X-ray beam of a CBCT machine. METHODS: Five sequential CBCT scans were captured of a human mandible at each angulation of 10°, 20°, 30°, and 40° using a coronal and sagittal positioning. Inspection software utilized a best-fit alignment to automatically calculate the three-dimensional variation at 15 standardized points of interest. RESULTS: Statistically significant differences were found between the dimensional accuracy of CBCT scans taken at 10° (26.3 µm) of coronal angulation, as well as those taken at 20° (-17.3 mm) and 30° (35.2 mm) of sagittal angulations (p < 0.001, 0.016, and <0.001, respectively). The largest deviations in accuracy included an overall maximum deviation of 490 mm. CONCLUSIONS: The position of the mandible with respect to the X-ray beam has a clinically insignificant effect on dimensional accuracy, up to the maximum angle of 40° assessed.

Online Teaching Tool for Sinus Surgery: Trends toward Mobile and Global Education.

OBJECTIVE: Online resources may provide an ideal forum for expert presentation of surgical techniques. The purpose of this study was to investigate utilization patterns of a sinus surgery website, SinusVideos.com, to gain insight into the needs of viewers. STUDY DESIGN: Retrospective analysis. SETTING: Surgical teaching website. SUBJECTS AND METHODS: The website's anonymized analytic database was queried from 2009 to 2014. Quantified data included user demographics, geographic location, viewing device, page visits, and time spent on the website. RESULTS: A total of 428,691 website pages were viewed during the study period. Growth in viewership was observed each successive year since the site was launched. The mean time spent viewing webpages was 96.1 seconds for desktop computer users, 98.0 for tablet users, and 103.8 for mobile users. The percentage of mobile devices used to view the site increased significantly between 2009 and 2014 (2.1% vs 25.4%, respectively; P < .0001). The website's viewership expanded globally, with a significant increase in site views from outside North America over this same period (18.4% vs 51.7%, P < .0001). CONCLUSION: The observed increase in global participation and mobile device usage may reflect new areas of growth for surgical education.

Accuracy in the digital workflow: From data acquisition to the digitally milled cast.

STATEMENT OF PROBLEM: The accuracy of digital impressions and the milling of implant crowns greatly influence the clinical outcome of implant restorations. PURPOSE: The purpose of this in vitro study was to calculate the propagation of error in the process of milling an implant crown. MATERIAL AND METHODS: Thirty digitally milled casts made directly from a reference model were prepared. The casts were scanned with a laboratory scanner, and 30 standard tesselation language (STL) datasets from each group were imported to inspection software. In each analysis, STL datasets were aligned by a repeated best fit algorithm, and 18 specified contact locations of interest were measured in mean volumetric deviations. The master reference dataset was aligned 30 times to the master reference dataset to determine the software variation. The reference datasets were aligned to the master reference dataset to determine the scanner variation. The milled cast datasets were aligned to the master reference dataset to determine the milling variation. The 18 specified contact locations of interest were pooled by cusps, occlusal ridge/fossae, interproximal contacts, facial/lingual aspect, and implant position. The pooled areas were statistically analyzed by comparing each group with the reference model to investigate the mean volumetric deviations accounting for accuracy and standard deviations for precision. RESULTS: Software and scanner variation were negligible. Variations in the milled models resulting from software and scanner error exhibited statistical significance (P<.001). Software, scanner, and milling error were shown to propagate through the digital workflow to the milled model. CONCLUSIONS: The pooled locations may describe the reliability of the milling process as it applies to specific anatomic locations on the tooth.