A Novel Method for Precise Guided Hole Fabrication of Dental Implant Surgical Guide Fabricated with 3D Printing Technology

A dental implant surgical guide fabricated by 3-dimensional (3D) printing technology is widely used in clinical practice due to its convenience and fast fabrication. However, the 3D printing technology produces an incorrect guide hole due to the shrinkage of the resin materials, and in order to solve this, the guide hole is adjusted using a trimmer or a metal sleeve is attached to the guide hole. These methods can lead to another inaccuracy. The present method reports a technique to compensate for a decreased guide hole caused by shrinkage that can occur when a computer-guided implant surgical guide is fabricated with a 3D printer. The present report describes a technique to adjust the size of the guide hole using a free software program to identify the optimized guide hole size that is fabricated with the 3D printer

Marginal and Internal Fit of Ceramic Prostheses Fabricated from Different Chairside CAD/CAM Systems: An In Vitro Study

The purpose of this in vitro study was to evaluate marginal and internal fits of ceramic crowns fabricated with chairside computer-aided design and manufacturing (CAD/CAM) systems. An experimental model based on ISO 12836:2015 was digitally scanned with different intraoral scanners (Omnicam (CEREC), EZIS PO (DDS), and CS3500 (Carestream)). Ceramic crowns were fabricated using the CAD/CAM process recommended by each system (CEREC, EZIS, and Carestream systems; N = 15). The 3-dimensional (3D) marginal and internal fit of each ceramic crown was measured using a 3D inspection software (Geomagic control X). Differences among the systems and various measurements were evaluated using the Kruskal–Wallis test. Statistically significant differences were validated using pairwise comparisons (α = 0.05). Occlusal gaps in the CEREC, EZIS, and Carestream groups were 113.0, 161.3, and 438.2 µm, respectively (p < 0.001). The axial gaps were 83.4, 78.0, and 107.9 µm, respectively. The marginal gaps were 77.8, 99.3, and 60.6 µm, respectively, and the whole gaps were 85.9, 107.3, and 214.0 µm, respectively. Significant differences were observed with the EZIS system compared with the other two systems in terms of the marginal gap sizes. The CEREC system showed no significant differences among the four measured regions. However, the EZIS and Carestream systems did show a statistically significant difference (p < 0.05). All three systems were judged to be capable of fabricating clinically acceptable prostheses, because the marginal gap, which is the most important factor in the marginal fit of prostheses, was recorded to be below 100 µm in all three systems

Effect of Tooth Types on the Accuracy of Dental 3D Scanners: An In Vitro Study

The purpose of this study was to evaluate the accuracy of dental three-dimensional (3D) scanners according to the types of teeth. A computer-aided design (CAD) reference model (CRM) was obtained by scanning the reference typodont model using a high-precision industrial scanner (Solutionix C500, MEDIT). In addition, a CAD test model (CTM) was obtained using seven types of dental 3D scanners (desktop scanners (E1 and DOF Freedom HD) and intraoral scanners (CS3500, CS3600, Trios2, Trios3, and i500)). The 3D inspection software (Geomagic control X, 3DSystems) was used to segment the CRM according to the types of teeth and to superimpose the CTM based on the segmented teeth. The 3D accuracy of the scanner was then analyzed according to the types of teeth. One-way analysis of variance (ANOVA) was used to compare the differences according to the types of teeth in statistical analysis, and the Tukey HSD test was used for post hoc testing (α = 0.05). Both desktop and intraoral scanners showed significant differences in accuracy according to the types of teeth (P < 0.001), and the accuracy of intraoral scanners tended to get worse from anterior to posterior. Therefore, when scanning a complete arch using an intraoral scanner, the clinician should consider the tendency for the accuracy to decrease from anterior to posterior

Marginal and Internal Fit of Ceramic Prostheses Fabricated from Different Chairside CAD/CAM Systems: An In Vitro Study

The purpose of this in vitro study was to evaluate marginal and internal fits of ceramic crowns fabricated with chairside computer-aided design and manufacturing (CAD/CAM) systems. An experimental model based on ISO 12836:2015 was digitally scanned with different intraoral scanners (Omnicam (CEREC), EZIS PO (DDS), and CS3500 (Carestream)). Ceramic crowns were fabricated using the CAD/CAM process recommended by each system (CEREC, EZIS, and Carestream systems; N = 15). The 3-dimensional (3D) marginal and internal fit of each ceramic crown was measured using a 3D inspection software (Geomagic control X). Differences among the systems and various measurements were evaluated using the Kruskal–Wallis test. Statistically significant differences were validated using pairwise comparisons (α = 0.05). Occlusal gaps in the CEREC, EZIS, and Carestream groups were 113.0, 161.3, and 438.2 µm, respectively (p p < 0.05). All three systems were judged to be capable of fabricating clinically acceptable prostheses, because the marginal gap, which is the most important factor in the marginal fit of prostheses, was recorded to be below 100 µm in all three systems

Trueness of intraoral scanners according to subgingival depth of abutment for fixed prosthesis

Abstract This study aimed to compare the trueness of intraoral scanners (IOSs) according to the subgingival finish line depth of tooth preparation for fixed prostheses. The prepared maxillary right first molar was fabricated by using ceramic material. A computer-aided design (CAD) reference model (CRM) of the abutment was obtained by using a contact scanner. The subgingival finish line was located according to the depth at 0-mm, 0.25-mm, 0.5-mm, 0.75-mm, and 1-mm. CAD test models (CTMs) were obtained by using 2 IOSs (i500 and CS3600). CRM and CTM were superimposed and analyzed (Geomagic control X). The one-way analysis of variance (ANOVA) was used to compare the trueness according to the subgingival finish line depth. The paired t test was used to compare the trueness of IOSs with and without gingival retraction (α = .05). When the gingival displacement code was not used, it was observed that the trueness of both IOSs decreased significantly as the depth of the subgingival finish line increased (P < 0.001). When the subgingival finish line was positioned deeper than 0.5-mm, the trueness of both IOSs exceeded 100 µm in the marginal region. When the gingival displacement cord was used, the trueness of both IOSs did not exceed 100 µm regardless of the subgingival finish line depth. When gingival cord was used, it showed significantly higher trueness than when not used (P < 0.001). When the gingival displacement cord was not used, the trueness of IOSs decreased as the subgingival finish line depth increased. But the use of the gingival displacement cord improved the scanning trueness by 90%. Thus, it is necessary to use the gingival displacement cord according to the clinical situation to improve scan trueness at the subgingival finish line

Accuracy of Proximal and Occlusal Contacts of Single Implant Crowns Fabricated Using Different Digital Scan Methods: An In Vitro Study

The purpose of this in vitro study was to compare the accuracy of the proximal and occlusal contacts of single implant crowns fabricated with four data capture methods. The resin models were mounted on an articulator, digitized using a laboratory scanner, and saved as a standard tessellation language (STL) file to serve as the master reference model (MRM). Two different intraoral scan body (ISB) systems were evaluated: polyetheretherketone (PEEK) short scan body (SSB) and PEEK long scan body (LSB) (n = 12). The digital impressions (SSB and LSB) were acquired using an intraoral scanner with ISB. Two different conventional techniques were also evaluated: PEEK short scan body with coping plastic cap (CPC) and pick-up coping (PUC) (n = 12). The implant impressions (CPC and PUC) were recorded using a conventional impression technique. The crown and abutment were fabricated with a milling machine and then placed on the resin model and scanned using a laboratory scanner. The scanned files were saved as STL files to serve as test datasets. The MRM and test datasets were superimposed, and the mesial, distal, and occlusal distances were calculated using a 3D inspection software and statistically analyzed using the Kruskal–Wallis H test (α = 0.05). The direct data capture group had more accurate contact points on the three surfaces, with mesial contact of 64.7 (12.8) µm followed by distal contact of 65.4 (15) µm and occlusal contact of 147 (35.8) µm in the SSB group, and mesial contact of 84.9 (22.6) µm followed by distal contact of 69.5 (19.2) µm and occlusal contact of 115.9 (27.7) µm in the LSB group (p &lt; 0.001). The direct data capture groups are closer to the ideal proximal and occlusal contacts for single implant crowns than the indirect data capture groups. There was no difference in the accuracy between the two types of scan body (SSB and LSB)

Effects of Trueness and Surface Microhardness on the Fitness of Ceramic Crowns

This study aims to evaluate the fitness, surface microhardness, and trueness of crowns fabricated from three types of dental ceramic blocks (HASS Rosetta, IPS e.max CAD, and VITA Suprinity) and analyze the correlations between them. A crown was first designed in computer-aided design (CAD) software. To create a crown designed model (CDM), the design file was extracted from the CAD software, and a lithium disilicate block was processed from the file with a milling machine. To create a crown scanned model (CSM), the inside of the fabricated crown was digitized using a contact scanner. Using three-dimensional (3D) inspection software (Geomagic Control X; 3D Systems), the CDM and CSM were then superimposed, and their 3D trueness was analyzed. To measure the surface microhardness of the blocks, the specimens were polished and subjected to the Vickers hardness test. The fitness of the fabricated crowns was evaluated by applying a modified silicone replica technique. Pearson correlation analysis was performed to assess the correlations between trueness, surface microhardness, and fitness. In addition, the significance of differences between the three types of dental ceramic blocks was analyzed using one-way analysis of variance (ANOVA). Significant differences in the trueness, surface microhardness, and marginal fit were observed between ceramic blocks of different types. There were also positive correlations between trueness, surface microhardness, marginal fit, and internal fit. While the marginal fit of crowns fabricated from each of the three types of ceramic blocks was in the clinically permitted range (&lt;120 &micro;m), there were differences in the trueness and surface microhardness, depending on the type of block. However, crowns fabricated from each of the three materials have surface microhardness that is clinically applicable

Effect of Different Software Programs on the Accuracy of Dental Scanner Using Three-Dimensional Analysis

This in vitro study aimed to evaluate the 3D analysis for complete arch, half arch, and tooth preparation region by using four analysis software programs. The CAD reference model (CRM; N = 1 per region) and CAD test models (CTMs; N = 20 per software) of complete arch, half arch, and tooth preparation were obtained by using scanners. For both CRM and CTMs, mesh data other than the same area were deleted. For 3D analysis, four analysis software programs (Geomagic control X, GOM Inspect, Cloudcompare, and Materialise 3-matic) were used in the alignment of CRM and CTMs as well as in the 3D comparison. Root mean square (RMS) was regarded as the result of the 3D comparison. One-way analysis of variance and Tukey honestly significant difference tests were performed for statistical comparison of four analysis software programs (α = 0.05). In half-arch and tooth preparation region, the four analysis software programs showed a significant difference in RMS values (p &lt; 0.001), but in complete-arch region, no significant difference was found among the four software programs (p = 0.139). As the area of the virtual cast for 3D analysis becomes smaller, variable results are obtained depending on the software program used, and the difference in results among software programs are not considered in the 3D analysis for complete-arch region

Satisfaction Factors with a Dental Unit Chair System in South Korea: A Dentist’s Perspective

This study aimed to survey users’ satisfaction with a dental unit chair in order to highlight the elements affecting the dentist’s satisfaction. The questionnaire items were drawn up with seven components that constitute a dental unit chair, including the light, patient seat, foot controller, water fountain and cuspidor, monitor, bracket table and controller, and dentist chair. With these questionnaire elements, a pilot experiment was conducted to test the reliability, and reliability analysis was conducted. The scale reliability was checked using Cronbach’s alpha coefficient. Bartlett’s test of sphericity, the Kaiser-Meyer-Olkin (KMO) measure, and factor analysis were performed to test whether the items would constitute appropriate questionnaire items for the survey. The survey was conducted with 26 dentists with more than three years of clinical experience. A correlation analysis was conducted using Pearson’s correlation coefficient (PCC) (α = 0.05) to analyze the impact of the factors on the overall satisfaction with the dental unit chair. The items that were strongly correlated with the overall satisfaction score of the dental unit chair were the design and appearance quality of the dental unit chair (PCC = 0.781), its maintenance (PCC = 0.784), and the overall satisfaction with the water fountain and cuspidor (PCC = 0.703) (p < 0.05). Most of the questionnaire items could affect the overall satisfaction with the dental unit chair. Additionally, because the design and appearance quality, maintenance, and overall satisfaction with the water fountain and cuspidor may have the greatest impact on the overall satisfaction with the dental unit chair, the improvement of these elements may bring about the enhancement of the overall satisfaction

Comparison of Intaglio Surface Trueness of Interim Dental Crowns Fabricated with SLA 3D Printing, DLP 3D Printing, and Milling Technologies

This study aimed to evaluate the intaglio surface trueness of interim dental crowns fabricated with three 3-dimensional (3D) printing and milling technologies. Dental crown was designated and assigned as a computer-aided design (CAD) reference model (CRM). Interim dental crowns were fabricated based on CRM using two types of 3D printer technologies (stereolithography apparatus and digital light processing) and one type of milling machine (n = 15 per technology). The fabricated interim dental crowns were obtained via 3D modeling of the intaglio surface using a laboratory scanner and designated as CAD test models (CTMs). The alignment and 3D comparison of CRM and CTM were performed based on the intaglio surface using a 3D inspection software program (Geomagic Control X). Statistical analysis was validated using one-way analysis of variance and Tukey HSD test (α = 0.05). There were significant differences in intaglio surface trueness between the three different fabrication technologies, and high trueness values were observed in the milling group (p &lt; 0.05). In the milling group, there was a significant difference in trueness according to the location of the intaglio surface (p &lt; 0.001). In the manufacturing process of interim dental crowns, 3D printing technologies showed superior and uniform manufacturing accuracy than milling technology