Influence of Repeated Cut-off and Rescanning on the Trueness of the Intraoral Digital Scans.

OBJECTIVES: To evaluate the effects of repeated cut-off and rescan procedures on the trueness of three intraoral scanners (IOS). METHODS: A tooth model (#16) with a standard class II cavity was prepared, and the complete-arch was scanned using a laboratory scanner (D2000, 3Shape A/S) to obtain a reference scan. Then the typodont was scanned with three IOSs (3Shape TRIOS 3, CEREC Omnicam, and Medit i500) under two rescanning strategies (full-cut and partial-cut), with varying numbers of repeated cut-off and rescanning procedures (0, 1, 3, 5, 7, or 10). The trueness discrepancy between the reference and experimental digital scan was estimated using root mean square (RMS) calculations. Three regions of interest were selected to represent the rescanning, identification, and non-rescan area. And the discrepancies were analyzed using a linear mixed model (α=.05). RESULTS: Cut-off and rescanning procedures significantly decreased the trueness of digital scans in all test conditions compared to the reference. However, no progressive increase in discrepancy was observed under any rescan conditions. Significant influences on trueness were found based on the IOS used, with the 3Shape system exhibiting lower RMS values. The partial-cut strategy showed lower RMS values compared to the full-cut strategy, albeit without statistical significance. CONCLUSIONS: While repeated cut-off and rescanning procedures led to a decline in the quality of digital impressions, they did not result in discrepancy accumulation with repeated rescanning. CLINICAL SIGNIFICANCE: To ensure high scanning accuracy in dental practice, it is advisable to minimize the rescanning area when correcting imperfections in digital scans. Additionally, selecting an appropriate scanner can help mitigate the negative effects of the rescanning technique.

Evaluation of the Stability of Open-Tray Impression Coping Using Two Different Impression Materials at Three Different Subgingival Implant Placement Depths.

Objective To evaluate and compare the stability of the open tray impression coping within the set impression while attaching the lab analog when polyether (PE) heavy body and polyvinyl siloxane (PVS) putty impression materials were used and the implant platform was placed sub-gingivally at three different depths. Methods Two impression materials, PE and PVS, and custom-made plexiglass models with embedded single implants to simulate implant positioning depths of 0 mm, 2 mm, and 4 mm, sub-gingivally, were used in the study. Open tray impressions were made after attaching impression coping to the implant embedded in the model. Implant lab analog was attached to the impression coping in the set impression, and its stability was measured using a universal testing machine. Forty-two open tray impressions were made in six groups, with seven impressions in each group. Descriptive statistics such as mean and standard deviation were calculated. A comparison of the mean stability between the two impression materials at each depth was done using an independent t-test. Comparison of the mean stability between the three different subgingival implant depths in each material was done by one-way ANOVA with the Scheffe multiple comparison test (post-hoc analysis). The level of significance was set at p<0.05. Results The stability of the impression coping was measured as the force in Newtons required for the displacement of the analog attached to the impression coping embedded in the set impression. PE with the embedded impression coping at a depth of 0 mm gave the highest mean stability value (4.37+/-0.41), and the least mean stability was offered by PVS with the embedded impression coping at 4 mm depth (1.88+/-0.37). When an independent t-test was done to compare the mean stability values of PE and PVS, there was a statistically significant difference at 0 mm, 2 mm, and 4 mm. On doing one-way ANOVA to compare the mean stability between the different depth groups, there was a statistically significant difference between the three depth groups in PE and PVS. Scheffe multiple comparison tests (post-hoc analysis) revealed a statistically significant difference between 0 mm, 2 mm, and 4 mm subgingival depths of the impression coping placement in both PE and PVS. Conclusion The accuracy of the master cast is an important determinant for the precise fit and long life of the final prosthesis. In the case of maxillary anterior implant placements where deep subgingival placement of the implant platform is needed for aesthetic and functional reasons, the impression material should be selected carefully to ensure the stability of the impression coping. Among the materials included in the present study, the PE impression material offered the maximum stability for impression coping compared to PVS.

Evaluation of the effect of different core substrates on the accuracy of intraoral scanners.

BACKGROUND: The aim of this study was to determine if different types of core substrates have any effect on the trueness and precision of digital intraoral impressions. MATERIAL AND METHODS: A customized typodont with four similar cores of natural dentine, composite, metal (Ni-Cr), and zirconia in the position of premolars was fabricated. The study model was scanned five times with two types of intraoral scanners (Carestream 3600 and 3Shape Trios 3), and a reference standard scan was obtained using a laboratory scanner (3shape D1000). A metrology software (Geomagic X) was used to align the data of experimental scans and the reference scan to determine deviation values (trueness). Precision values were calculated with random superimposition in each intraoral scanner group. The Kruskal-Wallis test was used to compare differences between different substrates, and the Mann-Whitney test was used to compare the average values between the two scanners. RESULTS: Trios 3 was found to be significantly truer and more precise than Carestream 3600 (p value = .005, <0.001). There were no significant differences in the trueness of different substrates when they were scanned by Trios 3, while different materials showed significantly different trueness values in the Carestream 3600 group (p value = .003). Dentin showed the best trueness, and zirconia performed worse than other substrates. Regarding the precision of the scanners, neither of the scanners was affected by the type of scanning substrate. CONCLUSION: For Carestream 3600, substrate type did impact the trueness of intraoral scans, with dentin and zirconia showing the highest and lowest accuracy, respectively, while Trios 3 was similarly accurate across all substrates. Trios 3 had both higher trueness and precision than Carestream 3600.

Adjacent Implant Influence on Tooth Restoration in a Gastro-Esophageal Reflux Disease (GERD) Patient Using Monoblock Post-Fused Crown: A Case Report.

This case report explores how the presence of an adjacent implant influenced the restoration of a tooth with pulpitis in a gastro-esophageal reflux disease (GERD) patient. A patient with GERD requires a tooth-colored crown not only for aesthetics but also to address potential galvanic concerns arising from an adjacent implant. GERD, a condition causing non-cavity erosion, weakens tooth structure over time, presenting significant challenges in treatment. It resulted in bite relapse and insufficient occlusal clarity over time. A comprehensive treatment approach was needed to restore both function and appearance. This involved managing galvanism using non-metallic materials to ensure optimal occlusal clarity, as well as meticulously reinforcing and restoring tooth structure. Monoblock post-fused crowns were chosen for their superior durability, stability, and comfort. The ceramic layering not only effectively prevented galvanic issues by insulating the tooth structure but also significantly improved the natural appearance of teeth, thereby promoting long-term oral health and successfully managing complex dental concerns. The dental team successfully restored the damaged tooth by considering specific factors that influenced the treatment plan, including achieving optimal aesthetic outcomes.

Effect of different fabrication workflows on the passive fit of screw-retained bar splinting two interforaminal implants: a parallel blinded randomised clinical trial.

BACKGROUND: To clinically compare the effect of the conventional and the digital workflows on the passive fit of a screw retained bar splinting two inter-foraminal implants. METHODS: The current study was designed to be a parallel triple blinded randomised clinical trial. Thirty six completely edentulous patients were selected and simply randomized into two groups; conventional group (CG) and digital group (DG). The participants, investigator and outcome assessor were blinded. In the group (CG), the bar was constructed following a conventional workflow in which an open top splinted impression and a lost wax casting technology were used. However, in group (DG), a digital workflow including a digital impression and a digital bar milling technology was adopted. Passive fit of each bar was then evaluated clinically by applying the screw resistance test using the "flag" technique in the passive and non passive situations. The screw resistance test parameter was also calculated. Unpaired t-test was used for intergroup comparison. P-value < 0.05 was the statistical significance level. The study protocol was reviewed by the Research Ethics Committee in the author's university (Rec IM051811). Registration of the clinical trial was made on clinical trials.gov ID NCT05770011. An informed consent was obtained from all participants. RESULTS: Non statistically significant difference was denoted between both groups in all situations. In the passive situation, the mean ± standard deviation values were 1789.8° ± 20.7 and1786.1° ± 30.7 for the groups (CG) and (DG) respectively. In the non passive situation, they were 1572.8° ± 54.2 and 1609.2° ± 96.9. Regarding the screw resistance test parameter, they were 217° ± 55.3 and 176° ± 98.8. CONCLUSION: Conventional and digital fabrication workflows had clinically comparable effect on the passive fit of screw retained bar attachments supported by two dental implants.

Clinician- and Patient-Centred Outcomes of Digital Impressions in Infants with Cleft Lip and Palate: A Systematic Review.

This systematic review examines the effectiveness of digital impressions in infants with cleft lip and palate (CLP), focusing on accuracy, operator preferences, and parents' perceptions. The PICO-formulated focused questions assessed the accuracy and operator preference of digital impressions compared to conventional impressions in infants with cleft lip and palate, while also exploring parents' perceptions as patient-centred outcomes. Electronic and manual searches were conducted in five databases including PubMed, Scopus, Web of Science, Embase, and Cochrane Library; to acquire grey literature, Google Scholar was also consulted. Both experimental and observational studies that used digital impressions in the clinical care of infants with CLP were included. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess the quality of the included studies. Out of 503 records, 12 studies met the inclusion criteria. The accuracy assessment included surface discrepancy and intra-arch measurements. Surface discrepancy studies showed variations in the premaxillary segments, while intra-arch measurements revealed no significant differences. Operators preferred digital impressions, citing reduced stress and streamlined workflows. Parents expressed a clear preference for digital over conventional impressions. The conclusions drawn were substantiated by weak evidence due to the limited number and the high risk of bias of the included studies. Challenges remain here, warranting continued research to enhance accuracy and assess parents' preferences, ensuring optimal outcomes for infants with CLP.

Augmented-reality-assisted intraoral scanning: A proof-of-concept study.

PURPOSE: The aims of the present study were (a) to compare the scanning time and image count to complete optical scans of a typodont between augmented-reality-assisted intraoral scanning (ARIOS) and intraoral scanning (IOS); (b) to compare the accuracy of the digital casts derived from ARIOS and IOS; (c) to compare participant-related outcomes between ARIOS and IOS. MATERIALS AND METHODS: A multi-session within-subject experiment was conducted to compare ARIOS and IOS. Thirty-one dental students participated in the study. Following a trial session, each participant obtained optical scans under ARIOS and IOS conditions. The time required to complete the scan, and the number of images taken were recorded. Participant feedback was collected using entry, exit, and NASA-Task Load Index (TLX) surveys. The accuracy of the digital casts derived from the optical scans was measured in root mean square error (RMSE). RESULTS: The present study found a 6.8% increase in preference for ARIOS from entry to exit survey. Slightly more participants favored the ARIOS setup compared to IOS; 54.8% of participants favored ARIOS, 9.7% were indifferent, and 35.5% favored IOS. NASA-TLX subscale ratings were higher for IOS in general apart from mental demand. The accuracy of the digital casts between ARIOS and IOS was comparable in RMSE. CONCLUSION: ARIOS was advantageous compared to IOS in ergonomics, improved scanner tracking, and ease of scanner orientation. However additional trials, increased field of view, and better superimposition of scanning status to the target site were improvements desired by the study participants.

Accuracy of maxillary full-arch digital impressions of tooth and implant models made by two intraoral scanners.

OBJECTIVES: Limited studies are available on the accuracy of intraoral scanners (IOSs) for full-arch implant and tooth models. This study aimed to assess the accuracy of maxillary full-arch digital impressions of tooth and implant models made by two IOSs. MATERIALS AND METHODS: This in vitro, experimental study was conducted on two maxillary dentiform models: one with six prepared natural teeth and the other with six implants at the site of canine, first premolar, and first molar teeth, bilaterally. A highly accurate industrial scanner was used for actual measurements on the models that served as the reference scan. TS (Trios3) and CO (CEREC Omnicam) IOSs were then used to scan each model 10 times according to the manufacturer's instructions. All scans were saved in STL format. The GOM Inspect software was used according to the best-fit algorithm to compare the accuracy of measurements in the groups with the reference scan. The trueness and precision were calculated. Statistical analyses were carried out using SPSS by one-way analysis of variance and t-test (α = .05). RESULTS: TS showed a significantly higher trueness than CO for both tooth and implant models (p < .05). TS also revealed significantly higher precision than CO for the tooth model; however, the difference in precision for the implant model was not significant between the two IOSs (p > .05). CONCLUSIONS: TS showed higher accuracy than CO in both tooth and implant models.

Comparative Analysis of the Comfort of Children and Adolescents in Digital and Conventional Full-Arch Impression Methods: A Crossover Randomized Trial.

The aim of this study was to evaluate the comfort of children and adolescents with conventional full-arch dental impression methods compared to two intraoral scanners (iTeroTM and PrimescanTM). METHODS: A monocentric, analytical, controlled crossover study was designed to compare conventional impression and digital impression with two intraoral scanners (iTeroTM and PrimescanTM) in children and teenagers. Patient comfort was evaluated using a 100 mm VAS scale adapted to Spanish and for children. A descriptive and analytical statistical method was conducted with a confidence level of 95% (p ≤ 0.05) and asymptotic or bilateral significance. RESULTS: A total of 51 subjects were enrolled in the study (mean age = 12.35 years). Although the group of 10-14-year-olds was the most numerous, gender was equally distributed among the age groups. None of the variables on the VAS scale showed differences between the gender categories (p > 0.05). There were differences (p < 0.05) with respect to the age categories, as the middle adolescent group showed the worst general perception and total comfort during the conventional impression. Statistically significant differences were found between all VAS scale items and the three impression methods (p < 0.05). CONCLUSIONS: The digital impression technique is superior in terms of total comfort to the conventional alginate impression in children and adolescents.

Digital Impressions Versus Conventional Impressions in Prosthodontics: A Systematic Review.

The accuracy of definitive impressions has a significant impact on the quality of the final prosthesis. Elastic impression materials are commonly used in the traditional approach to replicate anatomical structures while indirectly fabricating prostheses. Digital impression has gained increasing popularity due to its various advantages, including three-dimensional previsualization, cost-effectiveness, and reduced time consumption. The objective of this study is to evaluate existing studies to provide an overview of the comparative advantages of digital impression techniques over conventional techniques. The review will focus on evaluating the accuracy, patient acceptability, operator preference, and time effectiveness of digital impression techniques in comparison to conventional techniques. The Population, Intervention, Comparison, and Outcome framework served as the basis for this study's search strategy. We conducted a comprehensive literature review by electronically searching articles published between 2000 and 2023 in PubMed, Medline, Cochrane, and the Web of Science. Furthermore, additional manual searches were conducted. The study examined the differences between optical impressions and traditional impressions in terms of accuracy, patient outcomes, and operator outcomes. It included both clinical and preclinical studies as well as randomized controlled trials. In conclusion, this review provides a short summary indicating that digital impressions exhibit comparable accuracy to conventional impressions without any statistically significant difference. This conclusion is based on an evaluation of accuracy, patient preference, and operator preference.

Use of the universal scan template to achieve a predictable optical impression: Preliminary data of a case series study in complete edentulous patients.

BACKGROUND: Full-arch IOS scan of edentulous areas rehabilitated with dental implants is nowadays still described as an unpredictable procedure. To improve the accuracy, a universal scan template (UST®) is proposed in this article. The clinician can easily assemble the template with a mechanical coupling, by matching the scan bodies with objects of known dimension characterized by specific markers. The UST® facilitates the scanning of an entire arch on scan bodies, reducing the learning curve, simplifying acquisition movements, shortening the scanning time, and drastically reducing the risk of distortions and aberrations of the scans. MATERIALS AND METHODS: In a case series study on 12 patients, the improvement in the accuracy of the scans with UST® was validated by comparing the STL files derived from scans with and without the guide in place. A titanium bar was produced from each optical impression. RESULTS: The bars obtained from the optical impressions taken without UST® were found to be nonpassive in the mouth in the majority of the cases. On the contrary with the use of UST® we obtained 12 passive prosthetic rehabilitations. CONCLUSIONS: The proposed solution may represent a valid method to improve the predictability of full arch optical impressions on implants.

An integration protocol for aligning intraoral scans to facial scans using the nasal geometry reference in a fully dentate patient.

Advanced digital technologies have rapidly been integrated into prosthodontics to improve the digital workflow for prosthetic rehabilitation. The integration of 3D datasets acquired from various imaging sources such as intraoral scanners and facial optical scanners allows the creation of virtual patients to perform presurgical simulation and prosthetic rehabilitation. The presented technique introduced a straightforward protocol for aligning intraoral scans (Trios 4, 3Shape) to optical face scans (Face Hunter, Zirkonzahn) using a global best-fit algorithm of 3D evaluation software (GOM Inspect). Nasal geometry data were used as the matching reference to produce virtual dental patients. This integration protocol ensured that the intraoral scanner (Trios 4, 3Shape) was used not only to scan dental arches but also used effectively to scan the nose. These scans along with professional facial scans can be successfully aligned to produce virtual dental patients. As only a single fully dentate patient case with an alignment deviation of 243.6 µm was used, further research to evaluate the accuracy of this protocol is needed.

Digital repair for a patient with limited mouth opening: a case report and literature review / 口腔疾病防治

Objective@#To explore an accurate method to obtain an intraoral model of patients with specific limited mouth opening (microstomia) due to systemic scleroderma.@*Methods@#This study followed medical ethics, and informed consent has been obtained from patients. A case of Ken's Type I mandibular dentition defect scleroderma with limited mouth opening was addressed with digital technology as the leading method combined with the traditional impression method of segmental impression. Individual trays were made based on the patient's left and right mandibular dentition, and segmented molds were obtained. Simultaneously, intraoral scanning was performed to obtain the morphological data of both the soft and hard tissues of the upper and lower mandibles. After each part of the model was obtained, the mandibular model was scanned and digitally aligned to form the final denture model, and the final removable partial denture was designed and made by computer aided design/computer aided manufacturing (CAD/CAM) technology. At the same time, combined with the literature, the diagnosis and treatment of removable partial denture in patients with limited mouth opening were retrospectively analyzed.@*Results@#The denture was well retained and achieved a good repair effect. The patients expressed satisfaction with the mastication efficiency and other functions of the denture. The findings of the literature review show that the integration of digital technology with the traditional impression method, along with computer fitting, can accurately obtain the patient's oral model and facilitate successful follow-up repairs. However, when the anterior mandibular dentition of the patient is absent, the margin of error is increased in this procedure, which deserves further exploration.@*Conclusion@#Utilizing digital technology as the leading method, combined with the traditional impression method of segmental impression, for the repair of dental defects in patients with limited mouth opening, has proven to be effective. Thus, patients report a positive medical experience with high satisfaction, indicating that this approach is worthy of clinical promotion.

Chairside 3-D printed impression trays: a new approach to increase the accuracy of conventional implant impression taking? An in vitro study.

PURPOSE: A high transfer accuracy of the intraoral implant position to a model is required, to manufacture implant-supported restorations. However, clinically relevant deviations persist between the intraoral implant position and the model obtained, even for the benchmark conventional custom implant impressions with polyether. Thus, new approaches using 3-D printed impression trays may increase the transfer accuracy of implant impressions. The ability to adjust parameters such as the thickness of the layers and the influence of the openings in the impression tray could potentially affect accuracy. METHODS: Four different types of impression trays (n = 10 for each group) for the conventional impression technique were investigated: conventional custom impression tray, customized foil tray, chairside 3-D printed impression tray with the SHERA system, and the Primeprint system using an implant master model with four implants in the posterior region and a reference cube. After plaster model casting, all models were measured using a coordinate measuring machine, and the deviation from the reference dataset was determined. A statistical ANOVA analysis was performed (p < 0.05). RESULTS: Chairside 3-D printed impression trays showed the best results, followed by conventional custom impression trays. Implant impressions obtained using a customized foil tray exhibited the lowest accuracy. Statistically significant differences were observed between 3-D printed impression trays and conventional custom impression and customized foil trays (p < 0.05). Whereas, the implant position did not have any significant influence on accuracy (p > 0.05). CONCLUSIONS: Chairside 3-D printed impression trays significantly increase the transfer accuracy for implant impression taking.

Complete Denture - Border Molding Technique Using a Laboratory Condensation Silicone Putty: Review.

During the fabrication of a complete denture, functional impression is taken. Literature studies show that polydimethylsiloxane (condensation silicone) has not been reported by United States dental schools to perform border molding. Thus, the purpose of this article is to review the functional impression technique when border molding is performed with a laboratory condensation silicone putty.

Removable Partial Denture - Functional Impression Techniques: Review.

The objective of this article is to concisely review the main clinical techniques used to make the functional impression to manufacture a removable partial denture. Through this review, the dentist can develop his clinical knowledge.

Evaluating the impact of scan body angulation and geometric attachments on the accuracy of complete-arch digital implant impressions: A comparison of two intraoral scanners.

PURPOSE: To investigate the effects of scan body (SB) angulation and geometric attachments (GAs) on the deviations of complete-arch digital implant impressions obtained using intraoral scanners (IOSs), in relation to the gold-standard desktop scanner. MATERIAL AND METHODS: Two IOSs (iTero and Omnicam), two SB angulations (0 degrees and 30 degrees), and GAs for the SBs were investigated. SBs were attached to an edentulous maxillary cast with the following implant analogs: parallel 0-degree at positions #13, #23, and #26, and 30-degree posteriorly tilted at position #16. The cast was digitized using a reference desktop scanner, followed by ten consecutive digital scans using each IOS (five scans with GAs and five without GAs, n = 20). Meshes obtained from the IOS scans were superimposed on the master reference mesh. Linear distance and 3D surface deviations from the reference mesh were calculated. A three-way multivariate analysis of variance (MANOVA) was employed to assess the effects of angulation, IOS type, and GAs on the combined dependent variables (α = 0.05). RESULTS: No significant three-way interaction was observed between IOS type, SB angulation, and GAs for combined deviations from the reference scan (p = 0.56). Simple main effect analysis revealed that iTero exhibited significantly lower mean 3D surface and linear deviations than Omnicam (p < 0.05). Additionally, the use of GAs significantly reduced deviations (p < 0.001), with mean deviation reductions for both scanners ranging from 26-33 micrometers (µm) for 3D deviations and 15-21 µm for linear distance deviations. No differences were found between angled and parallel SBs regarding 3D surface and linear distance deviations (p ≥ 0.05). CONCLUSIONS: ITero demonstrated significantly smaller deviations, and the use of GAs led to significantly reduced distance and 3D surface deviations. SB angulations did not impact scan deviations.

Prosthetic rehabilitation of an edentulous patient with microstomia using digital and conventional methods: A case report.

This study describes prosthetic rehabilitation an edentulous patient with microstomia. Maxillary preliminary and definitive impression were made by intraoral scanning and custom 2-piece impression tray respectively to fabricate conventional denture.

Could various angulated implant depths affect the positional accuracy of digital impressions? An in vitro study.

PURPOSE: The purpose of this in vitro investigation was to assess how implant depth could affect the three-dimensional positional accuracy of digital impressions made from angulated implants. MATERIALS AND METHODS: Four modified maxillary models were printed and divided into four study groups. In each model, two angulated implant analogs were placed at the sites of the first premolar and first molar at four different depths of 1 (G1), 2 (G2), 3 (G3), and 4 (G4) mm from the models' edentate area. Scan bodies were connected to the analogs, and one operator made 10 full-arch scans for each master model using an intraoral scanner. Afterward, the marginal gingival part of all models was removed, and digital scans were performed for each model using a laboratory scanner to achieve a reference STL file as the control group. One-way ANOVA and Leven's tests were used to measure and compare the 3D distance deviations across research groups after the superimposing test and control scans. RESULTS: A significant difference between research groups was revealed by trueness and precision analysis (p < 0.001). The trueness and precision results obtained for G1 and G4 were significantly better than those for G2 and G3 (p < 0.05). CONCLUSION: This study demonstrated that implant depth could affect the digital implant impressions' 3D positional accuracy.

Accuracy of intraoral scan with prefabricated aids and stereophotogrammetry compared with open tray impressions for complete-arch implant-supported prosthesis: A clinical study.

OBJECTIVES: The aim of this clinical study was to compare the accuracy of intraoral scan system (IOS) with prefabricated aids and stereophotogrammetry (SPG) compared with open tray implant impression (OI) for complete-arch implant-supported fixed dental prostheses (CIFDP). MATERIALS AND METHODS: Patients needing CIFDP were enrolled in this study. OI, reference standard, IOS with prefabricated aids, and SPG were performed for each patient. Distance and angle deviations between all pairs of abutment analogs, root mean square (RMS) errors between the aligned test and reference model, and chairside time were measured. The effect of inter-abutment distance, jaw (maxilla or mandible), number of implants, and arch length on deviations was analyzed. The mixed effect model was applied to analyze deviations and RMS errors. RESULTS: Fifteen consecutive individuals (6 females and 9 males, 47-77 years old) with 22 arches (9 upper and 13 lower jaws) and 115 implants were included. There was no significant difference in distance deviation comparing SPG and IOS with OI (p > .05). IOS showed a significantly greater angle deviation and RMS errors than SPG (median 0.40° vs. 0.31°, 69 µm vs. 45 µm, p < .01). The inter-abutment distance was negatively correlated with the accuracy of SPG and IOS (p < .05). The chairside time for IOS, SPG, and OI was 10.49 ± 3.50, 14.71 ± 2.86, and 20.20 ± 3.01 min, respectively (p < .01). CONCLUSIONS: The accuracy of SPG and IOS with prefabricated aids was comparable. IOS was the most efficient workflow.