Influence of scan body design on accuracy of the implant position as transferred to a virtual definitive implant cast

Effect of different surface locking patterns on the trueness of complete arch digital implant scans: An in vitro study

STATEMENT OF PROBLEM

The effect of different surface locking patterns on the trueness of a digital implant scan of a completely edentulous arch remains uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate whether locking surfaces with different patterns affected the trueness of complete arch implant digital scans.

MATERIAL AND METHODS

An edentulous maxillary cast with 4 implants (2 anterior implants parallel and 2 posterior implants tilted at 17 degrees) was fabricated. Four implant-level scan bodies were fixed onto the implants, and the cast was scanned with a desktop scanner to create the reference file. Four groups (L0, L1, L2, and L3) were formed, each with a distinct locking surface configuration, and all scans were made using the same intraoral scanner. L0 kept all 4 implant-level scan bodies during scanning. L1 involved removing the right first premolar (RPM) scan body, scanning the other 3 implant scan bodies, then reattaching the RPM's scan body, and continuing scanning. In L2, the RPM and right lateral incisor (RIC) scan bodies were removed, followed by scanning the left implants to create a locking surface, and scanning the right implants. In L3, only the left posterior molar's (LPM) scan body was retained and scanned; then a locking surface was generated, and then the remaining implants were scanned. A metrology software program (Geomagic Control X) was used for comparison. Statistical analyses were performed using the Kruskal-Wallis, the 1-way ANOVA, the Welch ANOVA, the Friedman test, the repeated-measures ANOVA, the Bonferroni post hoc test, and the Games-Howell post hoc test (α=.05).

RESULTS

Significant 3D surface deviations were observed in the coronal bevel (CB) region and in the entire scan bodies when assessing trueness in the L0, L1, L2, and L3 groups (P<.001). L2 exhibited the highest discrepancies in 3D surface deviation for CB (0.030 ±0.002 mm) and implant scan bodies (0.357 ±0.052 mm) and distance deviation, while the highest mean angular deviation values were found in L0 (0.924 ±0.131 degrees).

CONCLUSIONS

Locking half of the arch showed the highest trueness discrepancies when performing digital scans for complete arch implant-supported prostheses.

Intraoral scanners in implant prosthodontics. A narrative review

OBJECTIVES

To review the developments in intraoral scanner (IOS) technologies applied in implant prosthodontics, emphasizing their influence on the accuracy of digital impressions, occlusal registrations, and the fit of implant-supported restorations.

DATA

A collection of published articles related to implant prosthodontics, the accuracy of digital impressions, occlusal registration, and the fit of implant-supported fixed restorations.

SOURCES

Three search engines were selected: Medline/PubMed, EBSCO, and Cochrane. A manual search was also conducted.

STUDY SELECTION

A literature search screened relevant databases and journals for studies on IOS applications in digital implant prosthodontic workflows from Dec 2018 to Dec 2023. Inclusion criteria encompassed randomized control trials, clinical trials, case series, and in vitro research focused on the use of IOS in digital implant prosthodontics.

CONCLUSIONS

The increased utilization of digital dental technologies has led to significant integration of digital implant prosthodontic workflows into clinicians' clinical practice. Several variables affect the accuracy of digital impressions generated by IOS. Generally, the prevailing opinion in academic papers is that digital workflows are suitable for addressing short-span implant-supported restorations. However, when it comes to long-span defects, the accuracy of digital workflows is still a matter of debate. Digital bite registration is an integral part of the workflow. It depends mainly on the defect size and location, scan strategy, anatomical tooth variations, overbite and other factors. The overall fit of digitally prefabricated implant restorations comprises of proximal, occlusal contacts and how accurately the restoration connects with implants. Research methodologies need standardization for further validation.

CLINICAL SIGNIFICANCE

In clinical practice, it is essential to have a thorough and up-to-date comprehension of various factors that can affect the accuracy of digital impressions and the fit of the final prosthesis in implant prosthodontics.

Effect of implant scan body geometric modifications on the trueness and scanning time of complete arch intraoral implant digital scans: An in vitro study

STATEMENT OF PROBLEM

The effect of the surface geometry of implant scan bodies (ISBs) on the accuracy and scanning time of complete arch implant digital scans remains uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate whether geometric modifications on implant scan bodies (nonmodified, subtractively modified, and additively modified ISBs) affect the trueness and scanning time of complete arch intraoral implant digital scans.

MATERIAL AND METHODS

A completely edentulous maxillary cast with 2 anterior parallel and two 17-degree posteriorly tilted implant abutment analogs was prepared. A digitized reference was created from this cast with polyetheretherketone (PEEK) (CARES Mono Scanbody for screw-retained abutment) ISBs by using a desktop scanner (E3). Three different groups were created: nonmodified (NM group), subtractively modified (SM group), and additively modified (AM group). For the NM group, no modifications were made to the ISBs. For the SM group, 4 round-shaped grooves were created on the buccal, lingual, mesial, and distal sides. For the AM group, PEEK beads were printed and cemented on the same areas of the ISB of the SM group. Fifteen consecutive scans were captured with an intraoral scanner (TRIOS 3) for each group, and the scanning time was recorded. By using a metrology software program, scans of each group were superimposed on the reference file to determine the 3D surface, linear, and angular position discrepancies of each ISB. Repeated-measures analyses of variance followed by univariate analysis and Bonferroni multiple comparison tests were performed to analyze the data (α=.05). To compare the mean time among groups, 1-way analysis of variance was performed followed by the Tukey post hoc tests.

RESULTS

Significant 3D surface, linear, and angular position discrepancies were found when measuring trueness among the NM, SM, and AM groups (P<.001). Discrepancies in 3D surface deviation were highest for the AM group (0.266 ±0.030 mm), and the lowest mean angular deviation values were for the SM group (0.993 ±0.062 degrees). However, the mean scanning time was not significantly different among the groups tested (P=.237).

CONCLUSIONS

For complete arch intraoral implant digital scans, subtractive modifications on ISBs enhanced scanning trueness, while additive modifications on ISBs decreased scanning trueness. However, implant scan body geometric modifications did not affect scanning time.

Single posterior implant-supported restorations fabricated using a scannable healing abutment versus a conventional scan body: A randomized controlled trial

STATEMENT OF PROBLEM

The use of a scannable healing abutment is a convenient option for fabricating implant-supported restorations (ISRs) with a digital workflow; however, clinical studies evaluating prosthetic efficacy are lacking.

PURPOSE

The purpose of this randomized controlled trial was to investigate the prosthetic efficacy of definitive posterior single ISRs fabricated after scanning using a scannable healing abutment-scan peg (SHA-SP) in comparison with a conventional scan body (CSB). The time for data acquisition, quality of proximal and occlusal contacts, and relative occlusal force of ISRs were measured.

MATERIAL AND METHODS

Twenty-four participants eligible for single ISRs to replace the mandibular first molar with adjacent and antagonist teeth present were randomly allocated to either a study group (n=12) receiving ISRs after intraoral scanning using an SHA-SP or a control group (n=12) receiving ISRs after intraoral scanning using CSB. During the surgical procedure, a prefabricated contoured scannable healing abutment was screwed to the implant in the SHA-SP group, while a custom-made healing abutment was used in the CSB group. After a healing period of 3 months, an intraoral scan was made, and the duration of data acquisition was recorded. The ISRs were milled from zirconia and evaluated for the quality of proximal and occlusal contacts using dental floss and shim stock, respectively. The relative occlusal forces of the ISRs and their contralateral natural teeth were measured using a digital occlusal analyzer. Statistical analysis was done using an independent sample t test for quantitative variables and a Pearson chi-squared test for qualitative variables between the tested groups (α=.05).

RESULTS

The direct digital workflow using SHA-SP was statistically less time consuming than the CSB (P<.001). The 2 groups were statistically similar regarding the quality of the proximal contacts (P=.281) or occlusal contacts (P=.307) and the relative occlusal forces of ISRs (P=.315). The relative occlusal forces of the ISRs in both groups were significantly lower than those of their contralateral natural teeth (P<.001).

CONCLUSIONS

Direct digital workflow using SHA-SP was more rapid, saving clinical chairside time, and produced proximal and occlusal contacts of comparable quality with those obtained with CSB. The relative occlusal forces of ISRs in both workflows were lower than their contralateral natural teeth.

Influence of implant angulation and clinical implant scan body height on the accuracy of complete arch intraoral digital scans

STATEMENT OF PROBLEM

The accuracy of digital implant scans can be affected by the implant angulation, implant depth, or interimplant distance. However, studies analyzing intraoral scanning accuracy with different implant angulations and different scan body heights are scarce.

PURPOSE

The purpose of this in vitro study was to determine the influence of the implant angulation and clinical implant scan body height on the accuracy of complete arch scans.

MATERIAL AND METHODS

Two definitive implant casts with 6 implant analogs (Zimmer Biomet) were obtained: 1 cast had all the implant analogs parallel (GP group), and 1 cast had the implant analogs with divergence of up to 30 degrees (GD group). A coordinate measurement machine (Global Evo 09.15.08) was used to measure the positions of the implant analogs. Each group was divided into 3 subgroups depending on the clinical implant scan body height: 10, 6, and 3 mm. An implant scan body (Elos Accurate Scan Body Brånemark system) was positioned on each implant analog. A total of 10 scans of each subgroup were recorded by using an intraoral scanner (TRIOS 3). Each STL file obtained was imported into a reverse engineering software program (Geomagic), and linear and angular Euclidean measurements were obtained. The Euclidean calculations between the implant analog positions of the definitive implant casts were used as a reference to calculate the discrepancies among the corresponding subgroups. The Kolmogorov-Smirnov test revealed that the lineal measurements were not normally distributed, so the Kruskal-Wallis and pairwise comparison Dunn tests were used (α=.05). The Kolmogorov-Smirnov test revealed that the angular measurements were normally distributed. Therefore, the 2-way ANOVA and pairwise comparison Tukey tests were used (α=.05).

RESULTS

The Kruskal-Wallis test revealed significant differences in the linear Euclidean medians between the GP and GD groups with different clinical implant scan body heights (H(5)=23.18, P<.001). Significant differences in the linear Euclidean medians were computed between the GP-6 and GD-10 subgroups (P=.009), GD-3 and GD-6 subgroups (P=.029), and GD-3 and GD-10 subgroups (P=.001). Two-way ANOVA revealed that the implant angulation (F(1, 3.3437)=28.93, P<.001) and clinical implant scan body height (F(2, 0.4358)=3.77, P=.029) were significant predictors of discrepancies in the angular measurement.

CONCLUSIONS

Implant angulation and clinical scan body height influenced scanning accuracy. The lowest clinical implant scan body height tested had the lowest accuracy in both parallel and angled implants, but statistically significant differences were found only in the angled group.

Influence of implant scan body design (height, diameter, geometry, material, and retention system) on intraoral scanning accuracy: A systematic review

PURPOSE

To evaluate the influence of implant scan body (ISB) design (height, diameter, geometry, material, and retention system) on the accuracy of digital implant scans.

MATERIAL AND METHODS

A literature search was completed in five databases: PubMed/Medline, Scopus, Embase, World of Science, and Cochrane. A manual search was also conducted. Studies reporting the evaluation of ISB design on the accuracy of digital scans obtained by using IOSs were included. Two investigators evaluated the studies independently by applying the Joanna Briggs Institute critical appraisal. A third examiner was consulted to resolve any lack of consensus. Articles were classified based on the ISB features of height, geometry, material, and retention system.

RESULTS

Twenty articles were included. Among the reviewed studies, 11 investigations analyzed the influence of different ISB geometries, 1 study assessed the impact of ISB diameter, 4 studies investigated the effect of ISB splinting, 2 articles evaluated ISB height, and 2 studies focused on the effect of ISB material on scan accuracy. In addition, 8 studies involved ISBs fabricated with different materials (1- and 2-piece polyetheretherketone and 1-piece titanium ISBs), and all of the reviewed articles tested screw-retained ISBs, except for 3 in vitro studies.

CONCLUSIONS

The findings did not enable concrete conclusions regarding the optimal ISB design, whether there is a relationship between IOS technology and a specific ISB design, or the clinical condition that maximizes intraoral scanning accuracy. Research efforts are needed to identify the optimal ISB design and its possible relationship with the IOS selected for acquiring intraoral digital implant scans.

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.

Characteristics of intraoral scan bodies and their influence on impression accuracy: A systematic review

OBJECTIVE

The aim of this systematic review was to evaluate the influence of the characteristics of intraoral scan bodies (ISBs) on the accuracy of intraoral scanning.

MATERIALS AND METHODS

An electronic search was conducted through PubMed (MEDLINE), Scopus and Cochrane Library, up to March 2023. The literature search intended to retrieve all relevant clinical and in vitro studies about the effect that the various properties of ISBs may have on the accuracy (trueness and precision) of intraoral scanning. Only publications in English language were selected with animal studies, case reports, case series, technique presentation articles and expert opinions being excluded.

RESULTS

A total of 28 studies met the inclusion criteria and were included in this systematic review. They were published between 2019 and 2023 and were all in vitro studies. Among the parameters described, the scan body material, position, geometry, height, diameter, and fixation torque were evaluated. The most common materials used for ISBs were polyetheretherketone (PEEK) and titanium alloys. The diameter and position of ISBs seemed to affect the trueness of implant impressions. Subgingival implant position and decreased ISB height affected negatively the trueness of scanning. Geometrical characteristics of ISBs also affect the implant impression accuracy, especially the bevel location and the types of designing modifications.

CONCLUSIONS

The characteristics of the currently used ISBs vary widely and the available scientific evidence is not yet conclusive about the optimal design of ISB. The implant impression accuracy achieved by any of the studied parameters is encouraging. Clinical studies are however necessary for more concrete conclusions.

CLINICAL SIGNIFICANCE

ISBs play a vital role in the digital workflow and influence significantly the accuracy and fit of implant restorations. More clinical trials are needed in order to conclude to the optimal characteristics of ISBs which would further enhance the success of the restorations.

Fabrication of a reverse-engineered custom scan body as a digital solution for recording implant position: A dental technique

A technique for the reverse engineering of the implant-abutment connection to fabricate a custom scan body is described. The implant-abutment connection was designed using the exocad software program, the scan body with screw channel was designed with the Blender software program, and the file was either 3-dimensionally printed in definitive tooth-colored resin with ceramic filler material or milled in polyetheretherketone (PEEK). This technique offers an accurate, cost-effective digital solution for implant optical scanning that can replace prefabricated scan bodies that may not be available for all implants. (J Prosthet Dent xxxx;xxx:xxx-xxx).

Positional transfer accuracy of titanium base implant abutment provided by two different scan body designs: an invitro study

BACKGROUND

The variabilities in design and material of scan bodies have a major role in the positional transfer accuracy of implants. The purpose of this invitro study was to compare the 3D transfer accuracy (trueness and precision) of titanium base (TB) abutment position provided by 2 different scan bodies: one-piece scan body (SB) in comparison to two-piece healing abutment and scan peg (HA-SP).

METHODS

A maxillary model with a dummy implant in the 2nd premolar (Proactive Tapered Implant; Neoss) was 3D printed and TB (Ti Neolink Mono; Neoss) was tightened on the implant and scanned by using a laboratory scanner (inEos X5; Dentsply Sirona) (reference scan). An SB (Elos Medtech) and an HA-SP (Neoss) were subsequently connected to the implant and were scanned 10 times each by using the same scanner (test scans). All the scans were exported as STL files and imported into CAD software where the TBs were formed. Test scans were superimposed on reference scans for transfer accuracy analysis using 3D metrology software (GOM Inspect; GOM GmbH) in terms of angular deviation in vertical and horizontal directions, linear deviation in each XYZ axis of TBs and total linear deviation in all axes. Statistical analysis was done using independent sample t test. When Levene's test for equality of variances was significant, Welch's t-test was used. (P value < 0.05) RESULTS: Significant differences were found amongst the tested groups in both angular and linear deviation in terms of trueness with less deviation values for the SB group (P < 0.001). For the precision, significant differences were found amongst the tested groups in angular deviation in vertical direction with less deviation value for the SB group compared to HA-SP group (P < 0.001). However, no significant difference was found between the tested groups regarding the angular deviation in horizontal direction (P = 1.000). Moreover, significant differences were found amongst the tested groups in linear deviations with less linear deviations in XYZ axes for SB compared to HA-SP group (P = 0.020, < 0.001, = 0.010 respectively).

CONCLUSIONS

SB showed less angular and linear deviation values in the 3D positional transfer of TB than HA-SP indicating higher degree of accuracy of SB.

A guide for maximizing the accuracy of intraoral digital scans: Part 2-Patient factors

OBJECTIVES

To describe the factors related to patient intraoral conditions that impact the scanning accuracy of intraoral scanners (IOSs). A new classification for these influencing factors is proposed to facilitate dental professionals' decision-making and maximize the accuracy and reliability of intraoral digital scans.

OVERVIEW

Variables related to intraoral conditions of the patient that can influence the scanning accuracy of IOSs include tooth type, presence of interdental spaces, arch width variations, palate characteristics, wetness, existing restorations, characteristics of the surface being digitized, edentulous areas, interimplant distance, position, angulation, and depth of existing implants, and implant scan body selection.

CONCLUSIONS

The knowledge and understanding of the patient's intraoral conditions that can impact the scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs.

CLINICAL SIGNIFICANCE

The patient's intraoral conditions, or patient factors, can significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing patient factors to maximize the accuracy of IOSs.

Full digital workflow to resolve angled adjacent dental implants: A dental technique

The digital acquisition, fabrication process, and delivery of computer-aided design and computer-aided manufacture (CAD-CAM) implant-supported restorations on angled adjacent implants are described. The proximal surface of a scan post was modified for correct adaptation, permitting an accurate digital scan of adjacent implants in 1 step. Definitive screw-retained splinted implant-supported restorations were designed and milled in a zirconia material and delivered with a combined extraoral and intraoral cementation protocol.

Fully Digital versus Conventional Workflows for Fabricating Posterior Three-Unit Implant-Supported Reconstructions: A Prospective Crossover Clinical Trial

This study assessed the clinical variables influencing the success of three-unit implant-supported fixed dental prostheses (ISFDPs) fabricated using either fully digital or conventional workflows. The clinical trial evaluated 10 patients requiring three-unit ISFDPs in the posterior mandible. Maxillomandibular relation records, and digital and conventional impressions were obtained from each patient using an intraoral scanner (IoS) and polyvinylsiloxane (PVS), and the frameworks were fabricated using zirconia and cobalt-chromium, respectively. A 2 µm accuracy scanner scanned the conventional master casts and standard reference models. The stereolithography (STL) files of the digital and conventional impressions were superimposed on the standard model file, and the accuracy was calculated with the best-fit algorithm. The framework adaptation and passivity were assessed using the one-screw and screw resistance tests. The time required for occlusal adjustment of both types of reconstructions, including the duration of the whole treatment, was recorded. The aesthetic appearance of ISFDPs was rated by each patient and clinician using a self-administered visual analogue scale questionnaire and the FDI World Dental Federation aesthetic parameters, respectively. The sample size was based on the power calculation, and alpha was set at 0.05 for the statistical analyses. The impression accuracy, framework adaptation and passivity, and reconstructions aesthetics did not significantly differ between the digital and conventional approaches. The total fabrication time was significantly shorter using the digital workflow. Within the limitations of this clinical study, the fully digital workflow can be used for the fabrication of ISFDPs with a clinical outcome comparable to that of the conventional workflow.

Influence of Implant Scanbody Wear on the Accuracy of Digital Impression for Complete-Arch: A Randomized In Vitro Trial

The aim of this study was to evaluate the influence of implant scanbody (ISB) wear on the accuracy of digital impression for complete-arch. A polymethylmethacrylate (PMMA) edentulous mandibular model with four internal hexagonal interlocking conical connections was scanned with an extraoral optical scanner to achieve a reference file. Four cylindrical polyetheretherketone (PEEK) ISBs were scanned 30 times with IOS, and the test files were aligned to the reference file with a best-fit algorithm. For each analog linear (ΔX, ΔY and ΔZ-axis) and angular deviations (ΔANGLE) were assessed. Euclidean distance (ΔEUC) was calculated from the linear deviation, reporting a mean of 82 µm (SD 61) ranging from 8 to 347 µm. ΔANGLE error mean was 0.33° (SD 0.20), ranging from 0.02 to 0.92°. From a multivariate analysis, when ΔEUC was considered as a response variable, a significant influence of ISB wear by scan number in interaction to position for implant 3.6 was identified (p < 0.0001); when ΔANGLE was considered as a response variable, a significant effect of position 3.6 was recorded ((p < 0.0001). The obtained results showed that the ISB wear negatively influenced the accuracy of IOS, suggesting that ISB base wear could be detrimental for the seating of ISBs on angulated implants.

Trueness of digital implant impressions based on implant angulation and scan body materials

Effects of implant angulation on digital implant impression accuracy remain controversial. Therefore, this in vitro study aimed to compare the digital implant impression trueness among models with different implant angulations and scan body materials. Six partially edentulous mandibular models with dental implants on the right second premolar and second molar areas were categorized according to the implant angulation of the distal implant (parallel, or 15° mesially or lingually tilted compared to the mesial implant) and scan body materials (polyetheretherketone or titanium). After scanning each model with intraoral scanners, the root mean square and within-tolerance values were calculated with respect to the reference, and nonparametric statistical tests were performed (α = .05). Scan data from models with the mesially tilted distal implant showed better trueness than the corresponding parallel and lingually tilted groups in terms of root mean square values (p < .017). The root mean square value in the titanium scan body group was lower than that in the polyetheretherketone scan body group (p < .001). However, the percentage within a tolerance of ± .1 mm was higher in the polyetheretherketone scan body group than in the titanium scan body group (p = .001). Intraoral scan data of models where the terminal implant was mesially tilted showed better trueness.

Techniques to improve the accuracy of complete-arch implant intraoral digital scans: A systematic review

STATEMENT OF PROBLEM

The best method of optimizing the accuracy of complete-arch intraoral digital scans is still unclear. For instance, the location of the scan bodies can be significantly distorted with respect to their actual positions, which would lead to a nonpassive fit of the definitive prosthesis.

PURPOSE

The purpose of this systematic review was to analyze available techniques for improving the accuracy of digital scans in implant-supported complete-arch fixed prostheses.

MATERIAL AND METHODS

Three databases (Medline, Embase, and Google Scholar) were searched, and the results obtained were supplemented by a hand search. Specific descriptors identified techniques whose objective were to increase the accuracy of digital scans in implant-supported complete-arch fixed prostheses. Titles and abstracts were screened by 2 independent reviewers, and unclear results were discussed with a third independent reviewer. A qualitative analysis based on procedural parameters was used. The interexaminer agreements of both were assessed by the Cohen kappa statistic, and the Risk of Bias Tool was used to assess the risk of bias across the studies.

RESULTS

A total of 17 techniques matching the inclusion criteria were evaluated. Higher accuracy but also differences regarding the need for supplementary devices, number of intraoral scans, and time consumption of clinical and software program steps were observed compared with the conventional digital scanning protocol. The use of a splinting device was common to most of the studies. The outcome variables for the evaluation of the effectiveness of these protocols were heterogeneous.

CONCLUSIONS

The use of additional techniques during intraoral scanning can improve accuracy in implant-supported complete-arch fixed prostheses. However, higher complexity for those procedures should be expected.

Trueness of ten intraoral scanners in determining the positions of simulated implant scan bodies

Few investigations have evaluated the 3-dimensional (3D) accuracy of digital implant scans. The aim of this study was to evaluate the performance of 10 intraoral scanners (IOSs) (CEREC Omnicam, CEREC Primescan, CS 3600, DWIO, i500, iTero Element, PlanScan, Trios 2, Trios 3, and True Definition) in obtaining the accurate positions of 6 cylinders simulating implant scan bodies. Digital scans of each IOS were compared with the reference dataset obtained by means of a coordinate measuring machine. Deviation from the actual positions of the 6 cylinders along the XYZ axes and the overall 3D deviation of the digital scan were calculated. The type of IOSs and position of simulated cylindrical scan bodies affected the magnitude and direction of deviations on trueness. The lowest amount of deviation was found at the cylinder next to the reference origin, while the highest deviation was evident at the contralateral side for all IOSs (p < 0.001). Among the tested IOSs, the CEREC Primescan and Trios 3 had the highest trueness followed by i500, Trios 2, and iTero Element, albeit not statistically significant (p > 0.05), and the DWIO and PlasScan had the lowest trueness in partially edentulous mandible digital implant scans (p < 0.001).