The accuracy of single implant scans with a healing abutment-scanpeg system compared with the scans of a scanbody and conventional impressions: An in vitro study

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.

Scan accuracy and time efficiency of different implant-supported fixed partial denture situations depending on the intraoral scanner and scanned area: An in vitro study

STATEMENT OF PROBLEM

The type of intraoral scanner (IOS), region of the implant, and extent of the scanned area have been reported to affect scan accuracy. However, knowledge of the accuracy of IOSs is scarce when digitizing different partially edentulous situations either with complete or partial arch scans.

PURPOSE

The purpose of this in vitro study was to investigate the scan accuracy and time efficiency of complete and partial arch scans of different partially edentulous situations with 2 implants and 2 different IOSs.

MATERIAL AND METHODS

Three maxillary models with implant spaces at the lateral incisor sites (anterior 4-unit), right first premolar and right first molar sites (posterior 3-unit), or right canine and right first molar sites (posterior 4-unit) were fabricated. After placing implants (Straumann S RN) and scan bodies (CARES Mono Scanbody), models were digitized by using an optical scanner (ATOS Capsule 200MV120) to generate reference standard tessellation language (STL) files. Complete or partial arch scans (test scans) of each model were then performed by using 2 IOSs (Primescan [PS] and TRIOS 3 [T3]) (n=14). The duration of the scans and the time needed to postprocess the STL file until the design could be started were also recorded. A metrology-grade analysis software program (GOM Inspect 2018) was used to superimpose test scan STLs over the reference STL to calculate 3D distance, interimplant distance, and angular (mesiodistal and buccopalatal) deviations. Nonparametric 2-way analysis of variance followed by Mann-Whitney tests with Holm correction were used for trueness, precision, and time efficiency analyses (α=.05).

RESULTS

The interaction between IOSs and scanned area only affected the precision of the scans when angular deviation data were considered (P≤.002). Trueness of the scans was affected by IOSs when 3D distance, interimplant distance, and mesiodistal angular deviations were considered. The scanned area affected only 3D distance deviations (P≤.006). IOSs and scanned area significantly affected the precision of scans when 3D distance, interimplant distance, and mesiodistal angular deviations were considered, while only IOSs significantly affected buccopalatal angular deviations (P≤.040). Scans from PS had higher accuracy when 3D distance deviations were considered for the anterior 4-unit and posterior 3-unit models (P≤.030), when interimplant distance deviations were considered for complete arch scans of the posterior 3-unit model (P≤.048), and when mesiodistal angular deviations were considered in the posterior 3-unit model (P≤.050). Partial arch scans had higher accuracy when 3D distance deviations of the posterior 3-unit model were considered (P≤.002). PS had higher time efficiency regardless of the model and scanned area (P≤.010), while partial arch scans had higher time efficiency when scanning the posterior 3-unit and posterior 4-unit models with PS and the posterior 3-unit model with T3 (P≤.050).

CONCLUSIONS

Partial arch scans with PS had similar or better accuracy and time efficiency than other tested scanned area-scanner pairs in tested partial edentulism situations.

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.

Effect of scan pattern on the scan accuracy of a combined healing abutment scan body system

STATEMENT OF PROBLEM

A recently introduced scan body combined with a contoured healing abutment enables digital scans of the implant while its healing abutment shapes the soft tissue for an appropriate emergence profile. However, information on the effect of different scan patterns on the scan accuracy of this new system is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of scan pattern on the accuracy of digital implant scans by using a combined healing abutment-scan body system.

MATERIAL AND METHODS

A combined healing abutment-scan body system was secured on a single implant at the right first molar site in a dentate mandibular model. A master reference model was generated by scanning the model with an industrial light scanner. The model was then scanned with 4 different scan patterns (SP-A, SP-B, SP-C, and SP-D) by using an intraoral scanner (TRIOS 3). Test scans (n=8) were superimposed over the master reference model by using a metrology software, and distance and angular deviations were calculated. Distance and angular deviation data were analyzed with a multivariate analysis of variance and the Tukey honestly significant difference tests for trueness and precision (α=.05).

RESULTS

Distance deviations (trueness [P=.461] and precision [P=.533] deviations) in the scans were not significantly affected by the scan pattern. Scan pattern affected the trueness (P=.001) and precision (P=.002) when angular deviations were considered. In terms of trueness, SP-D resulted in the highest angular deviations in scans (P≤.031), while the difference in deviations in scans obtained by using other scan patterns was not significant (P≥.378). When angular deviation data were considered, SP-D resulted in lower scan precision than SP-A (P=.014) and SP-B (P=.007). The precision of scans using SP-C was similar to the precision of the scans made by using other scan patterns (P≥.055) in terms of angular deviations.

CONCLUSIONS

The scan accuracy of a combined healing abutment-scan body system was affected by the scan pattern. The scans performed with SP-D presented the lowest accuracy considering the angular deviation data and, therefore, may be the least favored among the patterns tested for scanning a combined healing abutment-scan body system.

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.

Trueness and precision of combined healing abutment scan body system scans at different sites of maxilla after multiple repositioning of the scan body

OBJECTIVES

To evaluate the accuracy of the scans of the combined healing abutment-scan body (CHA-SB) system located at different sites of the maxilla when SBs are replaced in between each scan.

METHODS

Three SBs were seated into HAs located at the central incisor, first premolar, and first molar sites of a maxillary model inside a phantom head, and the model was scanned extraorally (CEREC Primescan SW 5.2). This procedure was repeated with new SBs until a total of 10 scans were performed. Standard tessellation language files of CHA-SBs at each implant location were isolated, transferred into analysis software (Geomagic Control X), and superimposed over the proprietary library files to analyze surface (root mean square), linear, and angular deviations. Trueness and precision were evaluated with one-way analysis of variance and Tukey tests. The correlation between surface and angular deviations was analyzed with Pearson's correlation (α=0.05).

RESULTS

Molar implant scans had the highest surface and angular deviations (P≤.006), while central incisor implant scans had higher precision (surface deviations) than premolar implant scans (P=.041). Premolar implant scans had higher accuracy than central incisor implant scans on the y-axis (P≤.029). Central incisor implant scans had the highest accuracy on the z-axis (P≤.018). A strong positive correlation was observed between surface and angular deviations (r = 0.864, P<.001).

CONCLUSION

Central incisor implant scans mostly had high accuracy and molar implant scans mostly had lower trueness. SBs were mostly positioned apically; however, the effect of SB replacement can be considered small as measured deviations were similar to those in previous studies and the precision of scans was high.

CLINICAL SIGNIFICANCE

Repositioning of scan bodies into healing abutments would be expected to result in similar single crown positioning regardless of the location of the implant, considering high scan precision with the healing abutment-scan body system. The duration of the chairside adjustments of crowns in the posterior maxilla may be longer than those in the anterior region.

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.

Effect of intraoral scanner and fixed partial denture situation on the scan accuracy of multiple implants: An in vitro study

BACKGROUND

Accuracy of intraoral implant scans may be affected by the region of the implant and the type of the intraoral scanner (IOSs). However, there is limited knowledge on the scan accuracy of multiple implants placed for an implant-supported fixed partial denture (FPD) in different partially edentulous situations when digitized by using different IOSs.

PURPOSE

To investigate the effect of IOS and FPD situation on the scan accuracy of two implants when partial-arch scans were performed.

MATERIALS AND METHODS

Tissue level implants were placed in 3 maxillary models with implant spaces either at right first premolar and right first molar sites (Model 1, 3-unit FPD), at right canine and right first molar sites (Model 2, 4-unit FPD), or at lateral incisor sites (Model 3, 4-unit FPD). Reference standard tessellation language (STL) files of the models were generated by using an optical scanner (ATOS Capsule 200MV120). Two IOSs (CEREC Primescan [CP] and TRIOS 3 [TR]) were used to perform partial-arch scans (test-scans) of each model (n = 14), which were exported in STL format. A metrology-grade analysis software (GOM Inspect 2018) was used to superimpose test-scan STLs over the reference STL to calculate 3D distance, inter-implant distance, and angular (mesiodistal and buccopalatal) deviations. Trueness and precision analyses were performed by using bootstrap analysis of variance followed by Welch tests with Holm correction (α = 0.05).

RESULTS

Trueness of the scans was affected by IOS and FPD situation when 3D distance deviations were considered, while inter-implant distance, mesiodistal angular, and buccopalatal angular deviations were only affected by the FPD situation (p < 0.001). Scan precision was affected by the interaction between the IOSs and the FPD situation when 3D distance and buccopalatal angular deviations were concerned, while IOSs and FPD situation were effective when all deviations were concerned (p≤ 0.001). When 3D distance deviations were considered, CP scans had higher accuracy TR scans in Models 1 and 3 (p ≤ 0.002), and the Model 1 scans had the highest accuracy (p < 0.001). When inter-implant distance deviations were considered, Model 1 scans had the highest accuracy with CP and higher accuracy than Model 2 when TR was used (p ≤ 0.030). When mesiodistal angular deviations were considered, Model 1 scans had the highest accuracy (p ≤ 0.040). When buccopalatal angular deviations were considered, Model 1 scans had the highest accuracy among models when CP was used (p ≤ 0.020).

CONCLUSIONS

Posterior 3-unit fixed partial denture implant scans, CP scans, and combination of these two factors had accuracy either similar to or better than their tested counterparts.

In vitro scan accuracy and time efficiency in various implant-supported fixed partial denture situations

OBJECTIVES

To compare the accuracy and time efficiency of different digital workflows in 3 implant-supported fixed partial denture situations.

METHODS

Three partially edentulous maxillary models with 2 implants (Model 1: implants at lateral incisor sites; Model 2: implants at right canine and first molar sites; Model 3: implants at right first premolar and first molar sites) were digitized (ATOS Capsule 200MV120, n=1) for reference scans. Test scans were performed for direct (Primescan (DDW-P) and Trios 3 (DDW-T)) and indirect (IDW) digital workflows (n=14). For IDW, stone casts (type IV) were obtained from vinylsiloxanether impressions and digitized (S600 Arti). The scan/impression and post processing times were recorded. Reference and test scans were superimposed (GOM Inspect) to calculate 3D point, inter-implant distance, and angular deviations. Kruskal-Wallis and Mann-Whitney tests were used for trueness and precision analyses (α=.05).

RESULTS

Tested workflows affected trueness (P≤.030) and precision (P<.001) of scans (3D point, inter-implant distance, and angular deviations) within models. DDW-P had the highest accuracy (3D point deviations) for models 1 and 3 (P≤.046). IDW had the lowest accuracy for model 2 (P<.01). DDW-P had the highest accuracy (inter-implant distance deviations) for model 3 (P≤.048). Direct digital workflow mostly led to lower angular deviations (P≤.040), and higher precision for models 2 (mesiodistal direction) and 3 (P<.001). The time for direct digital workflow was shorter (P<.001), DDW-P being more efficient than DDW-T (P=.008).

CONCLUSION

Direct digital workflow was more accurate and efficient than indirect digital workflow in tested partial edentulism situations with 2 implants.

CLINICAL SIGNIFICANCE

Tested intraoral scanners can be recommended for accurate and efficient impressions of anterior and posterior 3- or 4-unit implant-supported fixed partial dentures.

Influence of digital implant analog design on the positional trueness of an analog in additively manufactured models: An in-vitro study

BACKGROUND

Limited evidence exists regarding the accuracy of implant analog position in printed models, particularly when implant analogs with varying designs are used.

PURPOSE

To evaluate the effect of digital implant analog (DIA) design on the trueness of their position in additively manufactured digital implant models (DIMs) and to compare with that of a conventional implant analog in a stone cast.

MATERIALS AND METHODS

A dentate maxillary model with a conventional implant analog (Nobel Biocare Implant Replica 4.3 mm CC RP) at left second premolar site was digitized by using a laboratory scanner (3Shape D2000) and a (SB) scan body to generate the master standard tessellation language (STL) file (M0). 12 custom trays were fabricated on M0 file and conventional polyvinylsiloxane impressions of the model were made. All impressions were poured after inserting conventional implant analogs (Nobel RP Implant Replica) (Group A). Model was then digitized with an intraoral scanner (TRIOS 3) and the same SB, and DIMs with three different DIA designs (Nobel Biocare [Group B], Elos [Group C], and NT-trading [Group D]) were generated (Dental System-Model Builder). 12 DIMs of each design were additively manufactured and corresponding DIAs were inserted. All models were digitized by using the same laboratory scanner and SB, and these STLs were transferred to a 3D analysis software (Geomagic Control X), where the STL files of the models were superimposed over M0. Linear and 3D deviations at three selected points on SB (implant-abutment connection, most cervical point on SB, and most coronal point on SB) as well as angular deviations on two planes (buccolingual and mesiodistal) were calculated. Analysis of variance (ANOVA) and Bonferroni corrected t-tests were used to analyze the trueness of implant analog positions (α = 0.05).

RESULTS

The interaction of main effects significantly affected linear (p < 0.001) and angular deviations (p = 0.020). At point 1, group D had higher deviations than groups A and B (p ≤ 0.015). In addition, groups A and D had higher deviations than group B at point 4 (p < 0.001). While group C had similar linear deviations to those of other groups at point 1 and point 4 (p ≥ 0.192), the differences among test groups at point 2 were nonsignificant (p ≥ 0.276). Group B had lower angular deviations than groups C (p = 0.039) and D (p = 0.006) on buccolingual plane.

CONCLUSIONS

Analog design affected the trueness of analog position as proprietary, pressure/friction fit DIA (group B) had higher linear trueness than screw-retained DIA (Group D) and conventional implant analog (group A). In addition, pressure/friction fit DIA had the highest angular trueness among tested DIAs.

Comparison of different artificial landmarks and scanning patterns on the complete-arch implant intraoral digital scans

OBJECTIVES

The purpose of this study was to compare the effects of four types of artificial landmarks and three different scanning patterns on the accuracy of complete-arch implant intraoral digital scans.

METHODS

An edentulous mandibular model with 4 dental implants (Osstem) was prepared as the master reference model (MRM) and scanned with laboratory scanner (E4 Lab Scanner®). Then, the model was modified with four artificial landmarks: (i) CON- unmodified MRM, (ii) PIP- pressure-indicating paste brushed over the edentulous ridge, (iii) LD- liquid dam markers placed on the edentulous ridge, and (iv) FL- floss tied with pattern resin between the scan bodies. In each group, the modified model was scanned with three different scanning patterns: (i) LB- linguo-buccal pattern, (ii) SS- s-shaped pattern, and (iii) QU- quadrant pattern (n = 10/subgroup) using an intraoral scanner (Trios®4). Scans in STL format were exported and superimposed with MRM file using an inspection software (Geomagic Control X). Accuracy (trueness and precision) was evaluated by calculating the deviation, root mean square (RMS). Results were analyzed using two-way ANOVA, one-way ANOVA and Games-Howell (α = 0.05).

RESULTS

Significant differences in accuracy values were found across different artificial landmarks and scanning patterns as the LD artificial landmark with QU pattern showed the highest accuracy. The lowest accuracy was recorded in CON with LB pattern, PIP artificial landmark with LB pattern, and FL artificial landmark with SS pattern.

CONCLUSIONS

The artificial landmarks and scanning patterns had a significant effect on the accuracy of the complete-arch implant intraoral digital scans.

CLINICAL SIGNIFICANCE

When performing complete-arch digital scans with four dental implants, clinicians should select proper artificial landmark and scanning pattern, as the artificial landmark and scanning pattern significantly affect the accuracy of the scan when using an intraoral scanner. ®.

Trueness and precision of combined healing abutment-scan body system depending on the scan pattern and implant location: an in-vitro study

OBJECTIVE

To test the effect of scan pattern and the location of the implant on the trueness and precision of implant scans when the combined healing abutment-scan body (CHA-SB) system is used.

MATERIAL AND METHODS

A partially edentulous maxillary model with CHA-SBs secured on implants at 3 different sites in the left quadrant (central incisor, first premolar, and first molar) was fabricated. The model was scanned with an industrial light scanner to generate a master reference model (MRM) file. An intraoral scanner (TRIOS 3) was used to perform the test scans (n=8) with 4 different scan patterns (SP1, SP2, SP3, and SP4) with an intraoral scanner. The test scans were superimposed over the MRM file with a metrology software to calculate the distance deviations of the CHA-SB system. Data were analyzed with a 2-way analysis of variance and Tukey's honestly significant difference tests for accuracy (α=.05).

RESULTS

Trueness (P=.001) and precision (P=.018) were significantly affected by the interaction between the scan pattern and implant location. The implant located at the central incisor site (56.7 ±35.9, 36.2 ±18.6) had higher trueness than that of located at the premolar site (94.1 ±20.4, 100.3 ±20) when SP2 (P=.037) and SP4 (P=.002) were used. The implant at the molar site (71.9 ±25.7, 147.2 ±49.7) had trueness either similar to (when SP2 was used, P≥.276) or lower than (when SP4 was used, P≤.024) those of others. Scans of the central incisor and premolar implants had the lowest trueness when scanned with SP1 (P≤.009), while the scans of molar implant showed higher trueness when performed by using SP2 and SP3 when compared with SP4 (P≤.005). When SP4 was used, the implant at the molar site had lower precision (43 ±18.9) than the implants located at the central incisor (14.1 ±11) and premolar sites (15.4 ±11.3) (P=.002). Scan patterns affected the scan precision of central incisor implant (P=.009), as SP4 (14.1 ±11) led to a higher precision than SP1 (47.7 ±27) (P=.006).

CONCLUSIONS

The scan accuracy of combined healing abutment-scan body system was affected by scan pattern and implant location. SP1, which involved palatal and rotational scans resulted in the lowest trueness for central incisor and premolar implants, while the scans of the central incisor implant showed the highest trueness among different sites when SP4 was used. However, the scan pattern and implant site had a minor effect on precision. Scan precision at different implant sites only differed when SP4 was used, which resulted in the lowest precision for molar implant.

Accuracy of Digital Dental Implants Impression Taking with Intraoral Scanners Compared with Conventional Impression Techniques: A Systematic Review of In Vitro Studies

The aim of this systematic review was to evaluate the in vitro accuracy of dental implants impressions taken with intraoral scanner compared with impressions taken with conventional techniques. Two independent reviewers conducted a systematic electronic search in the PubMed, Web of Science and Scopus databases. Some of the employed key terms, combined with the help of Boolean operators, were: "dental implants", "impression accuracy", "digital impression" and "conventional impression". Publication dates ranged from the earliest article available until 31 July 2021. A total of 26 articles fulfilled the inclusion criteria: 14 studies simulated complete edentation (CE), nine partial edentation (PE) and only two simulated a single implant (SI); One study simulated both CE and SI. In cases of PE and SI, most of the studies analyzed found greater accuracy with conventional impression (CI), although digital impression (DI) was also considered adequate. For CE the findings were inconclusive as six studies found greater accuracy with DI, five found better accuracy with CI and four found no differences. According to the results of this systematic review, DI is a valid alternative to CI for implants in PE and SI, although CI appear to be more accurate. For CE the findings were inconclusive, so more studies are needed before DI can be recommended for all implant-supported restorations.

Congruence between the meshes of a combined healing abutment-scan body system acquired with four different intraoral scanners and the corresponding library file: an in vitro analysis

OBJECTIVES

To investigate the congruence between the meshes of a combined healing abutment-scan body (CHA-SB) system acquired with four different intraoral scanners and the corresponding library file.

MATERIAL AND METHODS

A CHA-SB was fixed to an implant at the right first molar position in a dentate mandibular model and digitized by using 4 different intraoral scanners (IOSs) [TRIOS 3 (T3), Omnicam (OC), Primescan (PS), and Virtuo Vivo (VV)] (n=8) and an industrial grade optical scanner (ATOS Core 80) (n=1) to generate standard tessellation language (STL) files of the test scans (CHA-SB-STLs) and the master reference model scan (MRM-STL). A reverse engineering software (Studio Geomagic X) was used to superimpose the proprietary library file of the CHASB over the generated STL files. Root mean square (RMS) values representing the deviations between the library file and the superimposed STL files were statistically analyzed by using 1-way ANOVA (α=.05). Qualitative analysis of the deviations was performed by visual inspection.

RESULTS

Differences between the congruence of the library file and the CHA-SB scans among different IOSs were nonsignificant (F=1.619, df= 3, P = .207). The single best result was 29 ±28.9 µm for OC, 30.8 ±29.6 µm for VV, 35.6 ±35.5 µm for T3, and 39.5 ±39.2 µm for PS, which were all above the deviation value of the scan performed by using the industrial-grade scanner (23.2 ±23.2 µm).

CONCLUSION

The dimensional congruence between the library file and the standard tessellation language file of the combined healing abutment-scan body system scans was similar when intraoral scanners with different acquisition technologies were used to scan a model with an implant.

CLINICAL SIGNIFICANCE

Scans of the tested intraoral scanners may result in crowns with similar positional accuracy, given the similarities in congruence of their scans with the library file.

Comparison of the virtual techniques in registering single implant position with a universal-coordinate system: An in vitro study

OBJECTIVES

The aim of this in-vitro study was to compare the virtual techniques for registering single-implant position to the physical gold standard using a universal-coordinate system.

MATERIALS AND METHODS

Thirty dentate maxillary resin models with a dental implant inserted in the incisor region were prepared. On each model, a tooth-supported acrylic stent with a 1 cm x 1 cm x 1 cm cubic-corner (CC) was prepared. The Cartesian x,y,z-coordinate of the implant neck and apex were measured physically by a coordinate-measuring machine (CMM) with reference to this CC and served as the gold-standard. The resin models were scanned by a benchtop scanner (Group BS), cone-beam computed tomography (Group CBCT), and intraoral scanner (Group IOS). Stone casts, poured from open-tray polyether impression of the resin models, were scanned by the benchtop scanner (Group BS-cast). The implant neck and apex coordinates with reference to the CC were measured and the differences in the coordinates (∆x, ∆y, ∆z) and distance r from the gold standard were calculated. The data were analyzed by one-sample t-test and one-way ANOVA/Kruskal-Wallis test with the level of significance set at 0.05.

RESULTS

The implant neck and apex positions of Group BS were statistically different from that of the CMM, r>0 (p<0.001). Group IOS showed a significant less ∆z and r at the implant neck than Group BS-cast (p = 0.006). No significant difference was found in the coordinates and distance at implant apex among Groups BS, CBCT, IOS and BS-cast.

CONCLUSIONS

The physical measurements could be adopted as the gold standard in assessing the single-implant positions. The IOS was more accurate in registering the single-implant neck positions than scanning of the cast.

CLINICAL SIGNIFICANCE

A universal-coordinate system defined by the cubic-corner allows comparing the virtual techniques in registering single-implant positions to the physical gold standard.

Effect of implant location and operator on the accuracy of implant scans using a combined healing abutment-scan body system

OBJECTIVES

To investigate the effect of implant location and operator on the accuracy of implant scans conducted with a combined healing abutment-scan body (CHA-SB) system.

MATERIAL AND METHODS

A CHA-SB system was fixed on implants at left central incisor, first premolar, and first molar sites in a dentate maxillary model. An industrial optical scanner (ATOS Core 80) was utilized to scan and generate a reference model (RM). The model was scanned by three operators (n = 8) using an intraoral scanner (TRIOS 3). A software (GOM Inspect) was used to superimpose IOS test scans over RM and calculations (distance and angular deviations) were carried out to evaluate the accuracy of the scans. Data were compared with a 2-way ANOVA and Tukey HSD tests were employed to resolve significant interactions for trueness and precision (α = .05).

RESULTS

Implant location affected the trueness (P ≤ .001) and the precision (P ≤ .020) (distance and angular deviations). The scans of the implant at the central incisor site had the highest trueness (distance and angular deviations) (P ≤ .016). The scans of the implant at molar site had the lowest precision (distance deviation data) (P ≤ .012). The scans of the implant at premolar site had lower precision (angular deviation data) than the scans of the implant at central incisor site (P = .016). Operators' effect on the accuracy of scans was not significant (P ≥  .051).

CONCLUSION

Implant location affected the scan accuracy of the combined healing abutment-scan body system. The scans of the implant at central incisor site had high trueness. The posterior the implant location, the lower was the precision of the scans. The accuracy of scans of different operators was similar.

CLINICAL SIGNIFICANCE

Higher deviations found in scans of posterior maxilla compared with those in the anterior region may require increased chairside adjustments when crowns are to be fabricated using the scans of the tested healing abutment-scan body system. However, clinical studies are necessary to corroborate the findings.

Accuracy of single implant scans with a combined healing abutment-scan body system and different intraoral scanners: AAn in vitro study

OBJECTIVE

The aim of the present study was to evaluate the accuracy of single implant scans with a combined healing abutment-scan body (CHA-SB) system using different intraoral scanners.

METHODS

A partially edentulous model with an implant was fabricated, and a CHA-SB system was secured on the implant. The model was scanned using an industrial-grade blue light scanner (ATOS Core 80) and a master reference model was generated (MRM). The model was also scanned with 4 different intraoral scanners (IOSs) [(Virtuo Vivo (VV), TRIOS 3 (T3), Omnicam (CO), and Primescan (PS)]. Test scans (n = 8) were superimposed over the MRM using the best fit algorithm (GOM Inspect 2018; GOM GmbH). After superimpositions, distance and angular deviations at selected areas on CHA-SB system were calculated. The data were analyzed with a 1-way ANOVA and Tukey HSD tests for trueness and precision (α=0.05).

RESULTS

The differences in trueness (distance deviations) among tested IOSs were nonsignificant (P=.652). VV presented the highest angular deviations (P ≤.031), and the angular deviations in other IOS scans were not found different (P ≥.378). The precision of distance deviation data was not significantly different among scanners (P=.052). For the precision of angular deviation data, significant differences were found among IOSs (P=.002). Compared with PS (P=.007) and T3 (P=.014), VV had significantly lower precision, which was not significantly different than that of CO (P=.815).

CONCLUSIONS

The accuracy (angular deviation) of scans of a combined healing abutment-scan body system on a single implant varied depending on the IOS. VirtuoVivo scans had the lowest accuracy in terms of angular deviations. When the distance deviation data were considered, scan accuracy of scanners was similar.

CLINICAL SIGNIFICANCE

A recently introduced combined healing abutment-scan body system combines the acquisition of both the implant and the soft tissue. When different intraoral scanners scan the combined healing abutment-scan body system, the scan accuracy may vary.