Accuracy, scanning time, and number of photograms of various scanning patterns for the extraoral digitalization of complete dentures by using an intraoral scanner

Effect of splinting scan bodies on the trueness of complete arch digital implant scans with 5 different intraoral scanners

STATEMENT OF PROBLEM

The absence of fixed reference points can affect the trueness of complete arch intraoral digital implant scans. The effect of splinting intraoral scan bodies (ISBs) or the inclusion of artificial landmarks (AL) on the trueness of complete arch digital implant scans is still unclear.

PURPOSE

The purpose of this study was to analyze the effect of splinting ISBs or the inclusion of AL on the trueness of complete arch digital implant scans with 5 intraoral scanners (IOSs).

MATERIAL AND METHODS

Six tissue-level dental implants (Straumann Tissue Level) were placed in an edentulous patient, and the correspondent definitive cast was digitized with a desktop scanner (IScan4D LS3i) to obtain the reference digital cast. Digital scans (n=10) were performed with 5 IOSs: TRIOS 4, Virtuo Vivo, Medit i700, iTero Element 5D, and Cerec Primescan. Three different scanning techniques were evaluated: conventional (cIOSs), splinted (sIOSs), and AL (AL-IOSs). The scan data obtained were imported into a metrology software program and superimposed to the reference digital cast by using a best-fit algorithm. The overall deviations of the positions of the ISBs were evaluated by using the root-mean-square (RMS) error (α=.05).

RESULTS

The mean ±standard deviation trueness values for the cIOSs, sIOSs, and AL-IOSs groups were 48 ±8 µm, 53 ±7 µm, and 49 ±11 µm, respectively, with no statistically significant differences (P=.06). Significant differences were found for the IOSs used with each technique (P<.001). Primescan (27 ±4 µm cIOSs; 28 ±3 µm sIOSs; 31 ±3 µm AL-IOSs) showed significantly higher trueness than iTero 5D (47 ±5 µm cIOSs; 47 ±4 µm sIOSs; 50 ±6 µm AL-IOSs) (P=.002) and TRIOS 4 (93 ±18 µm cIOSs; 76 ±18 µm sIOSs; 107 ±13 µm AL-IOSs) (P=.001) for all techniques. In addition, no significant differences were found between the techniques by using iTero 5D or Primescan (P=.348 and P=.059, respectively).

CONCLUSIONS

The cIOSs, sIOSs, and AL-IOSs techniques showed similar trueness. The IOS used influenced the trueness of complete arch digital implant scans.

An overview of artificial intelligence based applications for assisting digital data acquisition and implant planning procedures

OBJECTIVES

To provide an overview of the current artificial intelligence (AI) based applications for assisting digital data acquisition and implant planning procedures.

OVERVIEW

A review of the main AI-based applications integrated into digital data acquisitions technologies (facial scanners (FS), intraoral scanners (IOSs), cone beam computed tomography (CBCT) devices, and jaw trackers) and computer-aided static implant planning programs are provided.

CONCLUSIONS

The main AI-based application integrated in some FS's programs involves the automatic alignment of facial and intraoral scans for virtual patient integration. The AI-based applications integrated into IOSs programs include scan cleaning, assist scanning, and automatic alignment between the implant scan body with its corresponding CAD object while scanning. The more frequently AI-based applications integrated into the programs of CBCT units involve positioning assistant, noise and artifacts reduction, structures identification and segmentation, airway analysis, and alignment of facial, intraoral, and CBCT scans. Some computer-aided static implant planning programs include patient's digital files, identification, labeling, and segmentation of anatomical structures, mandibular nerve tracing, automatic implant placement, and surgical implant guide design.

Altered reverse impression method involving extraoral digitalization of a verification jig for the fabrication of implant-supported prosthesis by using a complete-digital workflow

The reverse impression method involves the extraoral digitalization of the interim implant-supported prostheses and intraoral digitalization of antagonist arch and maxillomandibular relationship. This technique allows the fabrication of implant-supported prostheses by using a complete-digital workflow. The scan analogs make the reverse impression method feasible. However, this method may not be recommended if the interim polymethyl methacrylate prosthesis does not have passive fit. The present manuscript describes an altered reverse impression technique that involves the extraoral digitalization of a conventional verification jig, which has attached scan analogs. With this technique modification, the implant positions captured using the verification jig are used to obtain the virtual definitive implant cast and fabricate the definitive implant-supported prosthesis.

Evaluation and comparison of the accuracy of three intraoral scanners for replicating a complete denture

STATEMENT OF PROBLEM

Technological advances in digital acquisition tools have increased the scope of intraoral scanners (IOSs), including scanning a removable complete denture (RCD) to replicate it. However, studies assessing the accuracy of IOSs for replicating a maxillary or mandibular RCD are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy (trueness and precision) of 3 IOSs while replicating a maxillary and mandibular RCD.

MATERIAL AND METHODS

One maxillary and 1 mandibular RCD were scanned with a desktop scanner (D2000) to obtain the reference model. Two operators scanned each RCD 5 times with 3 different IOSs (TRIOS 4, Primescan, and IS3800), following a predefined acquisition protocol. The 60 study models obtained were compared with the reference model using the Geomagic software program. For each comparison, the mean and standard deviation of discrepancy were calculated. Distances were measured on both the reference and the study model, and differences were calculated to assess whether sagittal or transverse deformations were present. The tolerance percentage of the volume of the digital model compared with the volume of the reference model was determined (difference tolerance was set at 0.1 mm). A univariate analysis of variance followed by a post hoc analysis using the Student-Newman-Keuls (α=.05) test was performed to determine the truest and the most precise IOS.

RESULTS

The TRIOS 4 and Primescan IOSs had comparable trueness, with mean dimensional variations of 47 ±27 µm and 57 ±8 µm respectively compared with the reference model. The IS3800 had a lower trueness (98 ±35 µm). Primescan was significantly more precise with a mean standard deviation of 64 ±15 µm (P<.05). The TRIOS 4 (141 ±48 µm) and IS3800 (129 ±24 µm) had comparable precision. Primescan showed the least sagittal and transverse deformation.

CONCLUSIONS

This study determined that an RCD can be replicated using an IOS, although all IOSs did not have equal accuracy. An in vivo study needs to assess whether this procedure is clinically acceptable.

Effect of prefabricated auxiliary devices and scanning patterns on the accuracy of complete-arch implant digital impressions

OBJECTIVES

This study aimed to evaluate the impact of prefabricated auxiliary devices (PAD) and scanning patterns on the accuracy of complete-arch implant digital impressions.

METHODS

An edentulous maxillary model was inserted with four parallel implant analogs and four PAD. The model was scanned with D2000 dental laboratory scanner as the reference scans. Test scans were obtained by 8 different scanning patterns (SP), which including SPA, SPB, SPC, SPD, SPE, SPF, SPG and SPH, with (test group) or without (control group) using the PAD by an intraoral scanner (Aoralscan 3, 3DShining). SPA was the scanning pattern recommended by the manufacturer. Each scanning time was recorded. The related files were imported into inspection software for assessment. Aligned Ranks Transformation ANOVA, Kruskal-Wallis and Mann-Whitney tests were used to evaluate the values. The level of significance was set at α = 0.05.

RESULTS

The scanning patterns significantly influenced the linear accuracy in the test group and the scanning time for both groups. Lower linear trueness in the test group was found in SPF (p<0.05) and SPG (p<0.05). Longer scanning time was found in SPB and SPG for both groups. The test group demonstrated linear accuracy enhancement in all the scanning patterns; angular trueness enhancement was seen in SPA (p<0.05), SPC (p<0.01) and SPH (p<0.01). Significant longer scanning time was found in SPB (p<0.05), SPF (p<0.05), SPG (p<0.05) and SPH (p<0.05) when using PAD.

CONCLUSION

The scanning patterns impact the accuracy differently depending on the PAD's existence. The scanning time can be significantly influenced by the scanning patterns and the PAD.

CLINICAL SIGNIFICANCE

In daily clinical practice, selecting a suitable scanning pattern is significant in achieving accurate digital impressions. The PAD demonstrated effective linear accuracy enhancement in all the scanning patterns tested.

Intraoral digital implant scans: Parameters to improve accuracy

PURPOSE

To report the means to maximize the predictability and accuracy of intraoral digital implant scans through the evaluation of operator and patient-related factors.

MATERIALS AND METHODS

A search of published articles related to factors that can decrease the scanning accuracy of intraoral digital implant scans was completed in four data sources:MEDLINE, EMBASE, EBSCO, and Web of Science. All studies related to variables that can influence the accuracy of intraoral digital implant scans obtained by using intraoral scanners (IOSs) were considered. These variables included ambient lighting, scanning pattern, implant scan body (ISB) design, techniques for splinting ISBs, arch location, implant position, and inter-implant distance.

RESULTS

Among operator-related factors, ambient lighting conditions, scanning pattern, and ISB design (material, geometry, and retention design) can impact the accuracy of intraoral digital implant scans. The optimal ISB for maximizing IOS accuracy is unclear; however, polymer ISB can wear with multiple reuse and sterilization methods. Among patient-related factors, additional variables should be considered, namely arch (maxillary vs. mandibular arch), implant position in the arch, inter-implant distance, implant depth, and angulation.

CONCLUSIONS

Ambient lighting conditions should be established based on the IOS selected to optimize the accuracy of intraoral digital implant scans. The optimal scanning pattern may vary based on the IOS, clinical situation, and the number of implants. The optimal ISB design may vary depending on the IOS used. Metallic implant scan bodies are preferred over polymer ISB designs to minimize wear due to multiple use and sterilization distortion. Among patient-related factors, additional variables should be considered namely the arch scanned, implant position in the arch, inter-implant distance, implant depth, and angulation. The impact of these factors may vary depending on the IOS selected.

Influence of interdental spaces and the palate on the accuracy of maxillary scans acquired using different intraoral scanners

PURPOSE

To assess the influence of interdental spaces and scanning the palate on the accuracy of maxillary scans acquired using three intraoral scanners (IOSs).

MATERIALS AND METHODS

A virtual completely dentate maxillary cast without interdental spaces was obtained and modified to create 1, 2, and 3 mm of interdental spacing between the anterior teeth. These three files (reference standard tessellation language files) were used to print three reference casts. The reference casts were scanned using three IOSs: TRIOS4, iTero Element 5D, and Aoralscan2. Three groups were created based on the interdental spaces: 0, 1, 2, and 3 mm (n = 10). The groups were subdivided into two subgroups: no palate (NP subgroup) and palate (P subgroup). The reference STL files were used to measure the discrepancy with the experimental scans by calculating the root mean square (RMS) error. Three-way analysis of variance (ANOVA) and post hoc Tukey pairwise comparison tests were used to analyze trueness. The Levene test was used to analyze precision (α = 0.05).

RESULTS

Trueness ranged from 91 to 139 μm and precision ranged from 5 to 23 μm among the subgroups tested. A significant correlation was found between IOS*group (p<0.001) and IOS*subgroup ( p<0.001). Tukey test showed significant trueness differences among the interdental spaces tested (p<0.001). The 1- and 2-mm groups obtained better trueness than the 0- and 3-mm groups (p<0.001). An 11 μm mean trueness discrepancy was measured among the different interdental space groups tested. The P subgroups demonstrated significantly higher trueness when compared to the NP subgroups (p<0.001). The discrepancy between the maxillary scans with and without the palate was 4 μm. Significant precision discrepancies were found (p = 0.008), with the iTero group showing the lowest precision.

CONCLUSION

Interdental spaces and incorporation of the palate on maxillary intraoral scans influenced trueness and precision of the three IOSs tested. However, the scanning discrepancy measured may be of no clinical relevance.

Comparison accuracy of digital and analog method using milled occlusal splints

OBJECTIVE

This clinical trial aims to compare the accuracy of interocclusal registration in centric relation taken with polyvinyl siloxane and intraoral scanner (IOS) with the fabrication of occlusal devices.

METHODS

Thirty-one participants were included in the trial registered at ClinicalTrials.gov (NCT05317182) receiving two different occlusal devices from two different workflows. One workflow was performed using polyvinyl siloxane impression material and the other with IOS. Every splint was scanned before and after the occlusal adjustments to compare the volumetric changes using the Root Mean Square deviation (RMS). Furthermore, three evaluators assessed the 3D comparison using color maps in a Visual Analog Scale (VAS).

RESULTS

The average values of RMS were higher for the analog approach (0.01 ± 0.067) than the digital approach (0.065 ± 0.035). However, the differences were not statistically significant (p < 0.063) between the two impression techniques. For the semiquantitative analysis performed by blinded evaluators, differences in VAS values between the impression for the digital (2.08 ± 2.4) and analog (3.80 ± 3.3) technique were statistically significant. The three evaluators agreed in more than 90% of the qualitative dichotomous evaluation.

CONCLUSION

Digital impressions did not show inferior accuracy compared to conventional impressions when assessed using quantitative measurements.

CLINICAL SIGNIFICANCE

This clinical trial provided evidence on registering interocclusal relationship at increased vertical dimension with fully digital workflow for complete arch prosthesis.

Influence of arch location and scanning pattern on the scanning accuracy, scanning time, and number of photograms of complete-arch intraoral digital implant scans

OBJECTIVES

To measure the influence of arch location and scanning pattern on the accuracy, scanning time, and number of photograms of complete-arch implant scans acquired using an intraoral scanner (IOS).

MATERIALS AND METHODS

A maxillary (maxillary group) and mandibular (mandibular group) model with 6 implant abutments on each cast was digitized using a desktop scanner (control scans). Six subgroups were created based on the scanning pattern used to acquire the scans using an IOS (Trios 4): occluso-buccal-lingual (OBL subgroup), occluso-linguo-buccal (OLB subgroup), bucco-linguo-occlusal (BLO subgroup), linguo-buccal-occlusal (LBO subgroup), zigzag (ZZ subgroup), and circumferential (C subgroup). The control scans were used as a reference to measure the discrepancy with the experimental scans calculating the root mean square error. Two-way ANOVA and the pairwise comparison Tukey tests were used to analyze the data (α = .05).

RESULTS

Significant discrepancies in trueness (p < .001), precision (p < .001), scanning time (p < .001), and number of photograms (p < .001) were found. The maxillary group obtained poorer trueness and precision values, higher scanning times, and a larger number of photograms than the mandibular group. The C subgroup obtained the best trueness and precision values, but was not significantly different from the OLB, BLO, and LBO subgroups. The ZZ subgroup obtained the worst trueness and precision values (p < .05). The C subgroup obtained the lowest scanning time and number of photograms (p < .05).

CONCLUSIONS

Arch location and scanning pattern influenced scanning accuracy, scanning time, and number of photograms of complete-arch implant scans.

Scanning accuracy and scanning area discrepancies of intraoral digital scans acquired at varying scanning distances and angulations among 4 different intraoral scanners

STATEMENT OF PROBLEM

The accuracy of intraoral scanners (IOSs) can be affected by operator handling; however, the scanning area and accuracy discrepancies acquired at different scanning distances and angulations among IOSs remain uncertain.

PURPOSE

The objective of this in vitro study was to compare the scanning area and scanning accuracy of the intraoral digital scans obtained at 3 scanning distances with 4 different scanning angulations among 4 different IOSs.

MATERIAL AND METHODS

A reference device (reference file) was designed with 4 inclinations (0, 15, 30, and 45 degrees) and printed. Four groups were created based on the IOS: i700, TRIOS4, CS 3800, and iTero scanners. Four subgroups were generated depending on the scanning angulation (0, 15, 30, and 45 degrees). Each subgroup was divided into 3 subgroups based on the scanning distance: 0, 2, and 4 mm (N=720, n=15). The reference devices were positioned in a z-axis calibrated platform for standardizing the scanning distance. In the i700-0-0 subgroup, the 0-degree reference device was positioned in the calibrated platform. The wand of the IOS was positioned in a supporting framework with a 0-mm scanning distance, and the scans were acquired. In the i700-0-2 subgroup, the platform was lowered for a 2-mm scanning distance followed by the specimen acquisition. In the i700-0-4 subgroup, the platform was further lowered for a 4-mm scanning distance, and the scans were obtained. For the i700-15, i700-30, and i700-45 subgroups, the same procedures were carried out as in the i700-0 subgroups respectively, but with the 10-, 15-, 30-, or 45-degree reference device. Similarly, the same procedures were completed for all the groups with the corresponding IOS. The area of each scan was measured. The reference file was used to measure the discrepancy with the experimental scans by using the root mean square (RMS) error. Three-way ANOVA and post hoc Tukey pairwise comparison tests were used to analyze the scanning area data. Kruskal-Wallis and multiple pairwise comparison tests were used to analyze the RMS data (α=.05).

RESULTS

IOS (P<.001), scanning distance (P<.001), and scanning angle (P<.001) were significant factors of the scanning area measured among the subgroups tested. A significant group×subgroup interaction was found (P<.001). The iTero and the TRIOS4 groups obtained higher scanning area mean values than the i700 and CS 3800 groups. The CS 3800 obtained the lowest scanning area among the IOS groups tested. The 0-mm subgroups obtained a significantly lower scanning area than the 2- and 4-mm subgroups (P<.001). The 0- and 30-degree subgroups obtained a significantly lower scanning area than the 15- and 45-degree subgroups (P<.001). The Kruskal-Wallis test revealed significant median RMS discrepancies (P<.001). All the IOS groups were significantly different from each other (P<.001), except for the CS 3800 and TRIOS4 groups (P>.999). All the scanning distance groups were different from each other (P<.001).

CONCLUSIONS

Scanning area and scanning accuracy were influenced by the IOS, scanning distance, and scanning angle selected to acquire the digital scans.

Prevention of peri-implant disease in edentulous patients with fixed implant rehabilitations

OBJECTIVES

To provide an overview about the current approaches to prevent peri-implant diseases in edentulous patients with complete-arch implant-supported prostheses, and to review the clinical applications of the latest digital technologies for implant prosthodontics.

METHODS

A review of the guidelines to prevent peri-implant diseases in patient's receiving complete-arch implant-supported prostheses including facially driven treatment planning procedures using either conventional or digital methods, computer-aided implant planning procedures, and prosthodontic design variables including the optimal number and distribution of dental implants, implant to abutment connection type, implant or abutment level design, screw- or cement-retained alternatives, prostheses contours, and material selection is provided. Furthermore, an outline of the current therapeutic management approaches to address peri-implant diseases is reviewed.

CONCLUSIONS

Clinicians should understand and know different planning and design-related variables that can affect biological and mechanical complication rates of complete-arch implant-supported prostheses. Maintenance protocols are fundamental for minimizing biological and mechanical complications.

A guide for maximizing the accuracy of intraoral digital scans. Part 1: Operator factors

OBJECTIVES

To describe the factors related to the operator skills and decisions that influence the scanning accuracy of intraoral scanners (IOSs). A new classification for these factors is proposed to facilitate dental professionals' decision making when using IOSs and maximize the accuracy and reliability of intraoral digital scans.

OVERVIEW

Each IOS system is limited by the hardware and software characteristics of the selected device. The operator decisions that can influence the accuracy of IOSs include the scanning technology and system selection, scanning head size, calibration, scanning distance, exposure of the IOS to ambient temperature changes, ambient humidity, ambient lighting conditions, operator experience, scanning pattern, extension of the scan, cutting off, rescanning, and overlapping procedures.

CONCLUSIONS

The knowledge and understanding of the operator factors that impact scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs and for successfully integrating IOSs in daily practices.

CLINICAL SIGNIFICANCE

Operator skills and clinical decisions significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing operator factors for maximizing the accuracy of IOSs.