Accuracy of a chairside fused deposition modeling 3D-printed single-tooth surgical template for implant placement: An in vitro comparison with a light cured template

Advancing accuracy in guided implant placement: A comprehensive meta-analysis: Meta-Analysis evaluation of the accuracy of available implant placement Methods

OBJECTIVES

This meta-analysis aimed to determine the accuracy of currently available computer-assisted implant surgery (CAIS) modalities under in vitro conditions and investigate whether these novel techniques can achieve clinically acceptable accuracy.

DATA

In vitro studies comparing the postoperative implant position with the preoperative plan were included. Risk of bias was assessed using the Quality Assessment Tool For In Vitro Studies (QUIN Tool) and a sensitivity analysis was conducted using funnel plots.

SOURCES

A systematic search was performed on April 18, 2023, using the following three databases: MEDLINE (via PubMed), EMBASE, and Cochrane Central Register of Controlled Trials. No filters or restrictions were applied during the search.

RESULTS

A total of 5,894 studies were included following study selection. Robotic- and static CAIS (sCAIS) had the most accurate and clinically acceptable outcomes. sCAIS was further divided according to the guidance level. Among the sCAIS groups, fully guided implant placement had the greatest accuracy. Augmented reality-based CAIS (AR-based CAIS) had clinically acceptable results for all the outcomes except for apical global deviation. Dynamic CAIS (dCAIS) demonstrated clinically safe results, except for horizontal apical deviation. Freehand implant placement was associated with the greatest number of errors.

CONCLUSIONS

Fully guided sCAIS demonstrated the most predictable outcomes, whereas freehand sCAIS demonstrated the lowest accuracy. AR-based and robotic CAIS may be promising alternatives.

CLINICAL SIGNIFICANCE

To our knowledge, this is the first meta-analysis to evaluate the accuracy of robotic CAIS and investigate the accuracy of various CAIS modalities.

A systematic review of the accuracy of digital surgical guides for dental implantation

PURPOSE

This review aimed to reveal the influence of implant guides on surgical accuracy with regard to supporting types, manufacturing methods and design (including fixation screws and sleeves).

METHODS

A literature search related to accuracy of surgical guides for dental implantation was performed in Web of Science and PubMed. Studies with in vivo or in vitro deviation data published in recent 5 years (2018-2022) were included and assessed by Newcastle-Ottawa Scale with regard to risk of bias and reliability degree of clinical studies. Accuracy-related deviation data were summarized as forest plots and normal distributions.

RESULTS

Forty-one articles were included with high degree of credibility. Data showed that implant surgery accuracy can be achieved with mean distance deviation < 2 mm (most < 1 mm) and angular deviation < 8° (most < 5°).

CONCLUSIONS

Bilateral tooth-supported guides exhibited highest in vitro accuracy and similar in vivo accuracy to unilateral tooth-supported guides; mucosa-supported guides exhibit lowest in vivo accuracy, while its in vitro data showed low credibility due to mechanical complexity of living mucosa tissue. Milling exhibited higher in vivo accuracy of guides than 3d-printing, though further data support was needed. Design of fixation screws and sleeves of implant guides affected the surgical accuracy and might remain a research focus in near future. However, lack of universal evaluation standards for implantation accuracy remained a major problem in this field. The influence of implant guides on surgical accuracy revealed in this review might shed light on future development of dental implantology.

Accuracy of static computer-aided implant surgery (S-CAIS) using CAD-CAM surgical templates fabricated from different additive manufacturing technologies

STATEMENT OF PROBLEM

Different 3D printers are available for guided implant surgery, but studies that evaluate their source of errors and their cost-effectiveness are lacking.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of different 3-dimensional (3D) printed surgical templates made using different additive manufacturing technologies and to evaluate the effect of implant location on the accuracy of fully guided implant placement.

MATERIAL AND METHODS

Fifty partially edentulous maxillary typodonts with edentulous sites in the right second premolar (SP), right lateral incisor (LI), left central incisor (CI), and left first molar (FM) locations were scanned and printed from the standard tessellation language (STL) datasets. The study compared 5 groups for the fabrication of implant surgical templates: Varseo S-Bego (Bego), Polyjet-Stratasys (Poly), Low Force Stereolithography-FormLabs (LFS), P30+-Straumann (P30), and M2-Carbon (M2). After fully guided implant placement, the typodont was scanned, and the 3D implant positions were compared with the master model by superimposing the STL files. Descriptive statistics were calculated for groups and subgroups, and comparisons among the groups and subgroups were conducted via 2-way mixed analysis of variance, Tukey honest significant difference, and post hoc Bonferroni tests (α=.05).

RESULTS

The results were site specific and not consistent within each group. For angle deviation, the within-group analysis for P30 demonstrated significantly lower values for implants positioned at site SP (1.4 ±0.8 degrees) than for sites LI (2.3 ±0.7 degrees; P=.001) and CI (2.3 ±0.8 degrees; P=.007). For 3D offset at base for implant CI, LFS was significantly higher than Bego (P=.002), Poly (P=.035), or M2 (P=.001); P30 was also significantly higher than Bego (P=.014) and M2 (P=.006). LFS had a significantly higher 3D offset at the tip than Bego (P=.001) and M2 (P=.022) for implant CI.

CONCLUSIONS

The choice of 3D printer seemed to influence fully guided implant surgery in terms of the final implant position compared with initial implant planning. However, although statistically significant differences were present across groups, all additive manufacturing technologies were within clinically acceptable values.

Influence of planning software and surgical template design on the accuracy of static computer assisted implant surgery performed using surgical guides fabricated with material extrusion technology: An in vitro study

OBJECTIVES

This in vitro study aimed to assess the influence of the planning software and design of the surgical template on both trueness and precision of static computer assisted implant surgery (sCAIS) performed using surgical guides fabricated using material extrusion (ME).

METHODS

Three-dimensional radiographic and surface scans of a typodont were aligned using two planning software (coDiagnostiX, CDX; ImplantStudio, IST) to virtually position the two adjacent oral implants. Thereafter, surgical guides were created with either an original (O) or modified (M) design with reduced occlusal support and were steam sterilized. Forty surgical guides were used to instal 80 implants equally distributed among four groups: CDX-O, CDX-M, IST-O, and IST-M. Thereafter, the scan bodies were adapted to the implants and digitised. Finally, inspection software was used to assess discrepancies between the planned and final positions at the implant shoulder and main axis level. Multilevel mixed-effects generalised linear models were used for statistical analyses (p = 0.05).

RESULTS

In terms of trueness, the largest average vertical deviations (0.29 ± 0.07 mm) could be assessed for CDX-M. Overall, vertical errors were significantly dependent on the design (O < M; p ≤ 0.001). Furthermore, in horizontal direction, the largest mean discrepancy was 0.32 ± 0.09 mm (IST-O) and 0.31 ± 0.13 mm (CDX-M). CDX-O was superior compared to IST-O (p = 0.003) regarding horizontal trueness. The average deviations regarding the main implant axis ranged between 1.36 ± 0.41 ° (CDX-O) and 2.63 ± 0.87 ° (CDX-M). In terms of precision, mean standard deviation intervals of ≤ 0.12 mm (IST-O and -M) and ≤ 1.09 ° (CDX-M) were calculated.

CONCLUSIONS

Implant installation with clinically acceptable deviations is possible with ME surgical guides. Both evaluated variables affected trueness and precision with negligible differences.

CLINICAL SIGNIFICANCE

The planning system and design influenced the accuracy of implant installation using ME-based surgical guides. Nevertheless, discrepancies were ≤ 0.32 mm and ≤ 2.63 °, which may be considered within the range of clinical acceptance. ME should be further investigated as an alternative to the more expensive and time-consuming 3D printing technologies.

Additive manufacturing technologies in the oral implant clinic: A review of current applications and progress

Additive manufacturing (AM) technologies can enable the direct fabrication of customized physical objects with complex shapes, based on computer-aided design models. This technology is changing the digital manufacturing industry and has become a subject of considerable interest in digital implant dentistry. Personalized dentistry implant treatments for individual patients can be achieved through Additive manufacturing. Herein, we review the applications of Additive manufacturing technologies in oral implantology, including implant surgery, and implant and restoration products, such as surgical guides for implantation, custom titanium meshes for bone augmentation, personalized or non-personalized dental implants, custom trays, implant casts, and implant-support frameworks, among others. In addition, this review also focuses on Additive manufacturing technologies commonly used in oral implantology. Stereolithography, digital light processing, and fused deposition modeling are often used to construct surgical guides and implant casts, whereas direct metal laser sintering, selective laser melting, and electron beam melting can be applied to fabricate dental implants, personalized titanium meshes, and denture frameworks. Moreover, it is sometimes required to combine Additive manufacturing technology with milling and other cutting and finishing techniques to ensure that the product is suitable for its final application.

An In Vitro Evaluation of the Effect of 3D Printing Orientation on the Accuracy of Implant Surgical Templates Fabricated By Desktop Printer

PURPOSE

To evaluate the effect of different 3D printing orientations on internal and seating accuracy of implant surgical templates fabricated by a digital light processing (DLP) printer.

MATERIALS AND METHODS

A single maxillary model with a missing central incisor was used to design a surgical template for single implant placement. According to the printing orientation, three surgical template groups were included in the study: horizontal (H), angled (A) and vertical (V) (n = 10). For the H group, the templates were produced parallel to the printing platform, while for the V group, the templates were perpendicular to the platform. The A group templates had a 45° angle orientation to the platform. Each template was scanned at the fitting surface and after seating on the master model. The internal accuracy involved measuring the trueness and precision of the internal surface, while for the seating accuracy, the vertical discrepancy after seating the template was measured. To determine the difference among the groups, ANOVA test was applied followed by Tukey post hoc tests (α = 0.05).

RESULTS

The H group had the lowest internal surface inaccuracy (trueness = 100.7 μm; precision = 69.1 μm) followed by A (trueness = 114.0 μm; precision = 77.3 μm) and V (trueness = 120.3 μm; precision = 82.4 μm) groups, respectively (p < 0.001). Similarly, the H group had the most superior seating accuracy (543.8 μm) followed by A group (1006.0 μm) and V group (1278.0 μm), respectively (p < 0.001).

CONCLUSIONS

The orientation of 3D printing of implant surgical templates fabricated by the DLP desktop printer influenced the accuracy of the templates. The horizontally printed templates consistently exhibited superior accuracy. To reduce deviation of implant placement, it is recommended to print the surgical templates with their largest dimension parallel to the printing platform.

Review on 3D printing in dentistry: conventional to personalized dental care

The CAD (Computer-aided design) and CAM (computer-aided manufacturing) have most applications in the manufacturing of fully automated, personalized dental devices and tailor-made treatment plans. 3D printing is one of the most rapidly expanding and new methods of manufacturing different things because of its on-demand and high productivity within the cost-effective manner which have a variety of applications in healthcare, pharmaceuticals, orthopaedics, engineered tissue models, medical devices, defence industries, automotive and aerospace sectors. Due to its emerging applications in the various sectors, the healthcare, Industries, and academic sectors are attracted towards the 3D printed materials. This review talks about the dental implants, polymers that are employed in concocting dental implants, critical parameters, and challenges which are to be considered while preparing these implants, advantages of 3D printing in the field of dentistry and the current trends. it discusses the variety of applications of 3D printed materials in the field of dentistry. Along with their method of fabrication, their critical process parameters (CPPs) are also discussed.

Biopsies of osseous jaw lesions using 3D-printed surgical guides: a clinical study

Background

Bone biopsies are often necessary to make a diagnosis in the case of irregular bone structures of the jaw. A 3D-printed surgical guide may be a helpful tool for enhancing the accuracy of the biopsy and for ensuring that the tissue of interest is precisely removed for examination. This study was conducted to compare the accuracy of biopsies performed with 3D-printed surgical guides to that of free-handed biopsies.

Methods

Computed tomography scans were performed on patients with bony lesions of the lower jaw. Surgical guides were planned via computer-aided design and manufactured by a 3D-printer. Biopsies were performed with the surgical guides. Bone models of the lower jaw with geometries identical to the patients’ lower jaws were produced using a 3D-printer. The jaw models were fitted into a phantom head model and free-handed biopsies were taken as controls. The accuracy of the biopsies was evaluated by comparing the parameters for the axis, angle and depth of the biopsies to the planned parameters.

Results

Eight patients were included. The mean deviation between the biopsy axes was significantly lower in guided procedures than in free-handed biopsies (1.4 mm ± 0.9 mm; 3.6 mm ± 1.0 mm; p = 0.0005). The mean biopsy angle deviation was also significantly lower in guided biopsies than in free-handed biopsies (6.8° ± 4.0; 15.4° ± 3.6; p = 0.0005). The biopsy depth showed no significant difference between the guided and the free-handed biopsies.

Conclusions

Computer-guided biopsies allow significantly higher accuracy than free-handed procedures.

Material Extrusion Based Fabrication of Surgical Implant Template and Accuracy Analysis

An implant template with great precision is significantly critical for clinical application. Currently, the application of an immediate implant remains limited by the deviations between the planned and actual achieved positions and long periods required for preparation of implant templates. Material Extrusion (MEX), as one kind of 3D printing method, is well known for its low cost and easy operation. However, the accuracy of the implant template printed by MEX has not been fully researched. To investigate the accuracy and feasibility of in vitro computer-guided surgery assisted with a MEX printed template, unidentified plaster samples missing a maxillary molar are digitalized. Mimics software (Materialise, Leuven, Belgium) is used for preoperative design. Surgical templates are fabricated by a MEX 3D printer (Lingtong III, Beijing SHINO, Beijing, China). Postoperative CBCT data are obtained after surgical template placement. The differences in positions of X, Y, Z, and dXYZ as well as angulations between the placed and the designed template are measured on labiolingual and mesiodistal planes. The deviations of the planned and the actual outcome in each dimension are observed and analyzed. Data from different samples indicate that the mean deviation of the angle measures approximately 3.640°. For position deviation, the maximum deviation is found in the z-direction and the mean deviation is about 0.365 ± 0.136 mm. The mean deviation of space Euclidean distance dXYZ is approximately 0.537 ± 0.123 mm. Implant templates fabricated by MEX present a relatively high accuracy for tooth-supported guide implantation.

[Independent innovation research, development and transformation of precise bionic repair technology for oral prosthesis]

According to the fourth national oral health epidemiological survey report (2018), billions of teeth are lost or missing in China, inducing chewing dysfunction, which is necessary to build physiological function using restorations. Digital technology improves the efficiency and accuracy of oral restoration, with the application of three-dimensional scans, computer-aided design (CAD), computer-aided manufacturing (CAM), bionic material design and so on. However, the basic research and product development of digital technology in China lack international competitiveness, with related products basically relying on imports, including denture 3D design software, 3D oral printers, and digitally processed materials. To overcome these difficulties, from 2001, Yuchun Sun's team, from Peking University School and Hospital of Stomatology, developed a series of studies in artificial intelligence design and precision bionics manufacturing of complex oral prostheses. The research included artificial intelligence design technology for complex oral prostheses, 3D printing systems for oral medicine, biomimetic laminated zirconia materials and innovative application of digital prosthetics in clinical practice. The research from 2001 to 2007 was completed under the guidance of Prof. Peijun Lv and Prof. Yong Wang. Under the support of the National Natural Science Foundation of China, the National Science and Technology Support Program, National High-Tech R & D Program (863 Program) and Beijing Training Project for the Leading Talents in S & T, Yuchun Sun's team published over 200 papers in the relevant field, authorized 49 national invention patents and 1 U.S. invention patent and issued 2 national standards. It also developed 8 kinds of core technology products in digital oral prostheses and 3 kinds of clinical diagnosis and treatment programs, which significantly improved the design efficiency of complex oral prostheses, the fabrication accuracy of metal prostheses and the bionic performance of ceramic materials. Compared with similar international technologies, the program doubled the efficiency of bionic design and manufacturing accuracy and reduced the difficulty of diagnosis and cost of treatment and application by 50%, with the key indicators of those products reaching the international leading level. This program not only helped to realize precision, intelligence and efficiency during prostheses but also provided functional and aesthetic matches for patients after prostheses. The program was rewarded with the First Technical Innovation Prize of the Beijing Science and Technology Awards (2020), Gold Medal of Medical Research Group in the First Medical Science and Technology Innovation Competition of National Health Commission of the People's Republic of China (2020) and Best Creative Award in the First Translational Medical Innovation Competition of Capital (2017). This paper is a review of the current situation of artificial intelligence design and precision bionics manufacturing of complex oral prosthesis.

Implementation of Fused Filament Fabrication in Dentistry

Additive manufacturing is becoming an increasingly important technique for the production of dental restorations and assistive devices. The most commonly used systems are based on vat polymerization, e.g., stereolithography (SLA) and digital light processing (DLP). In contrast, fused filament fabrication (FFF), also known under the brand name fused deposition modeling (FDM), is rarely applied in the dental field. This might be due to the reduced accuracy and resolution of FFF compared to vat polymerization. However, the use of FFF in the dental sector seems very promising for in-house production since it presents a cost-effective and straight forward method. The manufacturing of nearly ready-to-use parts with only minimal post-processing can be considered highly advantageous. Therefore, the objective was to implement FFF in a digital dental workflow. The present report demonstrates the production of surgical guides for implant insertion by FFF. Furthermore, a novel approach using a temperature-sensitive filament for bite registration plates holds great promise for a simplified workflow. In combination with a medical-grade filament, a multi-material impression tray was printed for optimized impression taking of edentulous patients. Compared to the conventional way, the printed thermoplastic material is pleasant to model and can allow clean and fast work on the patient.

Time Efficiency of Digitally and Conventionally Produced Single-Unit Restorations

The purpose of this in vitro study was to compare the time efficiency of digital chairside and labside workflows with a conventional workflow for single-unit restorations. The time efficiency in this specific sense was defined as the time, which has to be spent in a dental office by a dental professional performing the relevant steps. A model with interchangeable teeth on position 36 was created. These teeth were differently prepared, responding to several clinical situations to perform single-unit restorations. Different manufacturing techniques were used: For the digital workflows, CEREC Omnicam (CER) and Trios 3 (TN/TI) were used. The conventional workflow, using a dual-arch tray impression technique, served as the control group. For the labside workflow (_L) and the conventional impression procedure (CO), the time necessary for the impressions and temporary restorations was recorded and served as operating time. The chairside workflow time was divided by the time for the entire workflow (_C) including scan, design, milling and finishing the milled restoration, and in the actual working time (_CW) leaving out the chairside milling of the restoration. Labside workflow time ranged from 9 min 27 s (CER_L) to 12 min 41 s (TI_L). Entire chairside time ranged from 43 min 35 s (CER_C) to 58 min 43 s (TI_C). Pure chairside working time ranged from 15 min 21 s (CER_CW) to 23 min 17 s (TI_CW). Conventional workflow time was 10 min 39 s (CO) on average. The digital labside workflow and the conventional workflow require a similar amount of time. The digital chairside workflow is more time consuming.

In-house 3D-printed surgical guides for osseous lesions of the lower jaw: an experimental study

Background

The accuracy of computer-assisted biopsies at the lower jaw was compared to the accuracy of freehand biopsies.

Methods

Patients with a bony lesion of the lower jaw with an indication for biopsy were prospectively enrolled. Two customized bone models per patient were produced using a 3D printer. The models of the lower jaw were fitted into a phantom head model to simulate operation room conditions. Biopsies for the study group were taken by means of surgical guides and freehand biopsies were performed for the control group.

Results

The deviation of the biopsy axes from the planning was significantly less when using templates. It turned out to be 1.3 ± 0.6 mm for the biopsies with a surgical guide and 3.9 ± 1.1 mm for the freehand biopsies.

Conclusions

Surgical guides allow significantly higher accuracy of biopsies. The preliminary results are promising, but clinical evaluation is necessary.

A real time image-guided reposition system for the loosed bone graft in orthognathic surgery

In traditional orthognathic surgery, the dental splint technique is typically used to assist surgeons to reposition the maxilla or mandible. However, the design and manufacturing of dental splints is time-consuming and labor-intensive, and the templates may not applicable for some complicated cases due to the anatomic intricacies in the maxillofacial region. During recent years, computer-aided navigation technology has been widely used in oral and maxillofacial surgery. However, due to the limitation of current calibration and registration methods, it has been rarely reported for the motion tracking of intraoperative reposition for the loosed bone graft. In this study, a novel surgical navigation system was developed. With the use of this system, not only the surgical saw can be tracked in real-time, but also the loosed bone graft can be navigated under the guidance of the interactive 2D and 3D views until it is aligned with the preoperatively planned position. The phantom experiments validated the feasibility of our surgical navigation system, and the mean error of image-guided reposition was 1.03 ± 0.10 mm, which was significantly more accurate than the mean error of 5.57 ± 1.40 mm based on the non-navigated methods.

In Vitro Comparison of Surgical Implant Placement Accuracy Using Guides Fabricated by Three Different Additive Technologies

Various three-dimensional (3D) printing technologies are commercially available on the market, but the influence of different technologies on the accuracy of implant-guided surgery is unclear. Thus, three printing technologies: Stereolithographic (SLA), Digital light processing (DLP), and Polyjet were evaluated in this study. An entire 30 polyurethane models replicated the clinical situation. Ten surgical guides were printed by SLA, DLP, and PolyJet. Then, implant-guided surgery was performed, and their accuracy outcomes were measured concerning angular deviation, 3D deviation at the entry point, and apex. On top of that, the total processing time was also compared. For the angular deviation, the mean deviation was not statistically significant among all technologies. For the 3D deviation, PolyJet was statistically more accurate than DLP (p = 0.002) and SLA (p = 0.017) at the entry point. PolyJet was also statistically more accurate than DLP (p = 0.007) in regards to 3D deviation at the apex. Within the limitation of this study, the deviations from the experiment showed that PolyJet had the best outcome regarding the 3D deviations at the entry point and at the apex, meanwhile, the DLP printer had the shortest processing time.

Multi-colour extrusion fused deposition modelling: a low-cost 3D printing method for anatomical prostate cancer models

Three-dimensional (3D) printed prostate cancer models are an emerging adjunct for urological surgical planning and patient education, however published methods are costly which limits their translation into clinical practice. Multi-colour extrusion fused deposition modelling (FDM) can be used to create 3D prostate cancer models of a quality comparable to more expensive techniques at a fraction of the cost. Three different 3D printing methods were used to create the same 3D prostate model: FDM, colour jet printing (CJP) and material jetting (MJ), with a calculated cost per model of USD 20, USD 200 and USD 250 respectively. When taking into account the cost, the FDM prostate models are the most preferred 3D printing method by surgeons. This method could be used to manufacture low-cost 3D printed models across other medical disciplines.

Comparison of the accuracy of implants placed with CAD-CAM surgical templates manufactured with various 3D printers: An in vitro study

STATEMENT OF PROBLEM

The fit of a 3D printed surgical template will directly influence the accuracy of guided implant surgery. Various 3D printing technologies are currently available with different levels of resolution and printing accuracy; however, how the different systems affect accuracy is unclear.

PURPOSE

The purpose of this in vitro study was to assess the effect of using various 3D printers for the fabrication of implant surgical templates and its effect on the definitive implant position compared with the planned implant position.

MATERIAL AND METHODS

A cone beam computed tomography scan from a partially edentulous patient and an extraoral digital scan of a dental cast obtained from the same patient were used. The digital imaging and communications in medicine and standard tessellation language (STL) files were imported to an implant planning software program and merged, and an implant was digitally positioned in the mandibular right first molar region. A surgical template was designed and exported as an STL file. Ten surgical templates were printed for each of the following groups: stereolithography (SLA) printing, PolyJet, and MultiJet. The region where the implant was planned was cut away from the cast onto which the surgical templates were seated, allowing a passive positioning of the implant through the template, which was held in place with polyvinyl siloxane material. A scan body was inserted in the implant, and the cast was scanned with a laboratory scanner. The STL files obtained from the definitive implant position were imported into an implant planning software program and registered with the planned implant position, allowing for a comparison between the planned and actual implant position. Mean deviations were measured for angle deviation, entry point offset, and apex offset. Data normality was tested by using the Shapiro-Wilk test. The Kruskal-Wallis test was used to determine whether the outcomes of angle deviation, apex offset, and entry offset were statistically different between groups (α=.05).

RESULTS

The median and interquartile range for the angle deviation (degrees) were 1.30 (0.62) for SLA; 1.15 (1.23) for Polyjet; and 1.10 (0.65) for Multijet. No statistically significant differences were found in the angular deviation among groups (χ2(2)=3.08, P=.21). The median and interquartile range for the entry offset and apex offset (mm) were 0.19 (0.16) and 0.36 (0.16) for SLA, respectively; 0.20 (0.13) and 0.34 (0.26) for Polyjet, respectively; and 0.23 (0.10) and 0.32 (0.08) for Multijet, respectively. Similarly, nonsignificant differences were found for entry point offset (χ2(2)=0.13, P=.94) and apex offset (χ2(2)=1.08, P=.58).

CONCLUSIONS

The different types of 3D printing technology used in this study did not appear to have a significant effect on the accuracy of guided implant surgery.

Dimensional accuracy of extrusion- and photopolymerization-based 3D printers: In vitro study comparing printed casts

STATEMENT OF PROBLEM

Reliable studies comparing the accuracy of complete-arch casts from 3D printers are scarce.

PURPOSE

The purpose of this in vitro study was to investigate the accuracy of casts printed by using various extrusion- and photopolymerization-based printers.

MATERIAL AND METHODS

A master file was sent to 5 printer manufacturers and distributors to print 37 identical casts. This file consisted of a standardized data set of a maxillary cast in standard tessellation language (STL) format comprising 5 reference points for the measurement of 3 distances that served as reference for all measurements: intermolar width (IMW), intercanine width (ICW), and dental arch length (AL). The digital measurement of the master file obtained by using a surveying software program (Convince Premium 2012) was used as the control. Two extrusion-based (M2 and Ultimaker 2+) and 3 photopolymerization-based printers (Form 2, Asiga MAX UV, and myrev140) were compared. The casts were measured by using a multisensory coordinate measuring machine (O-Inspect 422). The values were then compared with those of the master file. The Mann-Whitney U test and Levene tests were used to determine significant differences in the trueness and precision (accuracy) of the measured distances.

RESULTS

The deviations from the master file at all 3 distances for the included printers ranged between 12 μm and 240 μm (trueness), with an interquartile range (IQR) between 17 μm and 388 μm (precision). Asiga MAX UV displayed the highest accuracy, considering all the distances, and Ultimaker 2+ demonstrated comparable accuracy for shorter distances (IMW and ICW). Although myrev140 operated with high precision, it displayed high deviations from the master file. Similarly, although Form 2 exhibited high IQR, it did not deviate significantly from the master file in the longest range (AL). M2 performed consistently.

CONCLUSIONS

Both extrusion-based and photopolymerization-based printers were accurate. In general, inexpensive printers were no less accurate than more expensive ones.