Influence of scan extension and starting quadrant on the accuracy of four intraoral scanners for fabricating tooth-supported crowns.

STATEMENT OF PROBLEM: Multiple factors can influence the accuracy of intraoral scanners (IOSs). However, the impact of scan extension and starting quadrant on the accuracy of IOSs for fabricating tooth-supported crowns remains uncertain. PURPOSE: The purpose of the present in vitro study was to measure the influence of scan extension (half or complete arch scan) and the starting quadrant (same quadrant or contralateral quadrant of the location of the crown preparation) on the accuracy of four IOSs. MATERIAL AND METHODS: A typodont with a crown preparation on the left first molar was digitized (T710) to obtain a reference scan. Four scanner groups were created: TRIOS 5, PrimeScan, i700, and iTero. Then, 3 subgroups were defined based on the scan extension and starting quadrant: half arch (HA subgroup), complete arch scan starting on the left quadrant (CA-same subgroup), and complete arch scan starting on the right quadrant (CA-contralateral subgroup), (n=15). The reference scan was used as a control to measure the root mean square (RMS) error discrepancies with each experimental scan on the tooth preparation, margin of the tooth preparation, and adjacent tooth areas. Two-way ANOVA and pairwise multiple comparisons were used to analyze trueness (α=.05). The Levene and pairwise comparisons using the Wilcoxon Rank sum tests were used to analyze precision (α=.05). RESULTS: For the tooth preparation analysis, significant trueness and precision differences were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.002). The iTero and TRIOS5 groups obtained better trueness than the PrimeScan and i700 groups (P<.001). Moreover, half arch scans obtained the best trueness, while the CA-contralateral scans obtained the worst trueness (P<.001). The iTero group showed the worst precision among the IOSs tested. For the margin of the tooth preparation evaluation, significant trueness and precision differences were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.005). The iTero group obtained best trueness (P<.001), but the worst precision (P<.001) among the IOSs tested. Half arch scans obtained the best trueness and precision values. For the adjacent tooth analysis, trueness and precision differences were found among the groups (P<.001) and subgroups tested (P<.001), with a significant interaction group×subgroup (P=.005). The TRIOS 5 obtained the best trueness and precision. Half arch scans obtained the best accuracy. CONCLUSIONS: Scan extension and the starting quadrant impacted the scanning trueness and precision of the IOSs tested. Additionally, the IOSs showed varying scanning discrepancies depending on the scanning area assessed. Half arch scans presented the highest trueness and precision, and the complete arch scans in which the scan started in the contralateral quadrant of where the crown preparation was obtained the worst trueness and precision.

Influence of the ambient color lighting on the accuracy of complete arch implant scans recorded by using two intraoral scanners.

STATEMENT OF PROBLEM: The influence of different ambient factors including lighting has been previously studied. However, the influence of ambient color lighting settings on intraoral scanning accuracy remains uncertain. PURPOSE: The purpose of this in vitro study was to assess the influence of ambient color lighting on the accuracy of complete arch implant scans recorded by using 2 intraoral scanners (IOSs). MATERIAL AND METHODS: An edentulous maxillary cast with 6 implant scan bodies was digitized by using a laboratory scanner (DW-7-140) to obtain a reference file. Two groups were created based on the IOS tested: TRIOS 4 (IOS-1) and i700 (IOS-2). Seven subgroups were developed depending on the ambient color lighting (red, green, blue, yellow, cyan, magenta, and white) (n=15). Scanning accuracy was analyzed by using a metrology software program (Geomagic Control X). The Kruskal-Wallis, 1-way ANOVA, and pairwise comparisons were used to analyze the data (α=.05). RESULTS: Significant trueness and precision values were found across the groups (P<.05) and subgroups (P<.05). For IOS-1, blue ambient lighting obtained the best trueness (19.8 ±1.8 µm) (P<.05); in precision, white light (20.8 ±7.3 µm) and blue light (22.1 ±13.5) showed the best results (P<.05). For IOS-2, white light showed the best trueness (51.9 ±16.7 µm); the best precision was obtained under magenta (38.6 ±10.4 µm) and yellow light (52.6 ±24.0 µm) (P<.05). CONCLUSIONS: The optimal ambient color lighting varied between the IOSs assessed. As the best condition for maximizing accuracy was not found, ambient color lighting must be individualized for the IOS system used.

Accuracy of an artificial intelligence-based program for locating the maxillomandibular relationship of scans acquired by using intraoral scanners.

STATEMENT OF PROBLEM: An artificial-intelligence (AI) based program can be used to articulate scans in maximum intercuspal position (MIP) or correct occlusal collisions of articulated scans at MIP; however, the accuracy of the AI program determining the MIP relationship is unknown. PURPOSE: The purpose of the present clinical study was to assess the influence of intraoral scanner (IOS) (TRIOS 5 or i700) and program (IOS or AI-based program) on the accuracy of the MIP relationship. MATERIAL AND METHODS: Casts of a participant mounted on an articulator were digitized (T710). A maxillary and a mandibular scan of the participant were recorded by using 2 IOSs: TRIOS 5 and i700. The scans were duplicated 15 times. Then, each duplicated pair of scans was articulated in MIP using a bilateral occlusal record. Articulated scans were duplicated and allocated into 2 groups based on the automatic occlusal collisions' correction completed by using the corresponding IOS program: IOS-corrected and IOS-noncorrected group. Three subgroups were created based on the AI-based program (Bite Finder) method: AI-articulated, AI-IOS-corrected, and AI-IOS-noncorrected (n=15). In the AI-articulated subgroup, the nonarticulated scans were imported and articulated. In the AI-IOS-corrected subgroup, the articulated scans obtained in the IOS-corrected group were imported, and the occlusal collisions were corrected. In the AI-IOS-corrected subgroup, the articulated scans obtained in the IOS-noncorrected subgroup were imported, and the occlusal collisions were corrected. A total of 36 interlandmark measurements were calculated on each articulated scan (Geomagic Wrap). The distances computed on the reference scan were used as a reference to calculate the discrepancies with each experimental scan. Nonparametric 2-way ANOVA and pairwise multiple comparison Dwass-Steel-Critchlow-Fligner tests were used to analyze trueness. The general linear model procedure was used to analyze precision (α=.05). RESULTS: Significant maxillomandibular trueness (P=.003) and precision (P<.001) differences were found among the subgroups. The IOS-corrected and IOS-noncorrected (P<.001) and AI-articulated and IOS-noncorrected subgroups (P=.011) were significantly different from each other. The IOS-corrected and AI-articulated subgroups obtained significantly better maxillomandibular trueness and precision than the IOS-noncorrected subgroups. CONCLUSIONS: The IOSs tested obtained similar MIP accuracy; however, the program used to articulate or correct occlusal collusions impacted the accuracy of the MIP relationship.

Impact of scanning distance on the accuracy of a photogrammetry system.

PURPOSE: To measure the impact of the scanning distance on the accuracy of complete-arch implant scans acquired by using a photogrammetry (PG) system. MATERIAL AND METHODS: An edentulous cast with 6 implant abutment analogs was obtained. A brand new implant scan body was positioned on each implant abutment and digitized using an extraoral scanner (T710; Medit) and the reference file was obtained. Three groups were created based on the scanning distance used to acquire complete-arch implant scans by using a PG (PIC System; PIC Dental): 20 (20 group), 30 (30 group), and 35 cm (35 group). An optical marker (PIC Transfer, HC MUA Metal; PIC Dental) was placed on each implant abutment and a total of thirty scans per group were acquired. Euclidean linear and angular measurements were obtained on the reference file was obtained and used to compare the discrepancies with the same measurements obtained on each experimental scan. One-way ANOVA and Tukey tests were used to analyze trueness. The Levene test was used to analyze the precision values (α = 0.05). RESULTS: Significant linear (P < .001) and angular trueness (P < .001) discrepancies were found among the groups. For linear trueness, Tukey test showed that the 20 and 30 groups (P < .001) and 30 and 35 groups were different (P < .001). For angular trueness, the Tukey test revealed that 20 and 30 groups (P = .003), 20 and 35 (P < .001), and 30 and 35 groups were different (P < .001) The Levene test showed no significant linear precision (P = .197) and angular discrepancies (P = .229) among the groups. CONCLUSIONS: The scanning distance influenced the trueness of complete-arch implant scans obtained with the PG method tested. The maximum linear trueness mean discrepancy among the groups tested was 10 µm and the maximum angular trueness mean discrepancy among the groups tested was 0.02 .

Influence of implant reference on the scanning accuracy of complete arch implant scans captured by using a photogrammetry system.

STATEMENT OF PROBLEM: Photogrammetry has been reported to be a reliable digital alternative for recording implant positions; however, the factors that may impact the accuracy of photogrammetry techniques remain unknown. PURPOSE: The purpose of this in vitro study was to assess the influence of the implant reference on the accuracy of complete arch implant scans acquired by using a photogrammetry system. MATERIAL AND METHODS: An edentulous cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was obtained and digitized by using a laboratory scanner (T710; Medit). A photogrammetry system (PIC System) was selected to obtain complete arch implant scans. An optical marker (PIC Transfer, HC MUA Metal; PIC Dental) was positioned on each implant abutment of the reference cast. Each optical marker code and position was determined in the photogrammetry software program. Three groups were created based on the implant reference selected before acquiring the photogrammetry scans: right first molar (IPR-3 group), left canine (IPR-11 group), and left first molar (IPR-14 group) (n=30). Euclidean linear and angular measurements were obtained on the digitized reference cast and used to compare the discrepancies with the same measurements obtained on each experimental scan. One-way ANOVA and the Tukey tests were used to analyze the trueness data. The Levene test was used to analyze the precision values (α=.05 for all tests). RESULTS: One-way ANOVA revealed significant linear (P=.003) and angular (P=.009) trueness differences among the groups tested. Additionally, the Tukey test showed that the IPR-11 and IPR-14 groups had significantly different linear (P<.001) and angular trueness (P<.001). The Levene test showed no significant precision linear (P=.197) and angular (P=.235) discrepancies among the groups tested. The IPR-3 group obtained the highest trueness (P<.001) and precision (P<.001) values among the groups tested. CONCLUSIONS: Implant reference impacted the accuracy of complete arch implant scans obtained by using the photogrammetry system tested. However, a trueness ±precision linear discrepancy of 6 ±3 µm and an angular discrepancy of 0.01 ±0.01 degrees were measured among the groups tested; therefore, the impact of the discrepancy measured should not be clinically significant.

A biologically oriented preparation technique (BOPT) for immediate posterior implant placement, immediate provisionalization, and definitive implant crown fabrication: A complete digital workflow.

OBJECTIVE: Immediate implants and immediate alveolar sealing have been a widely utilized treatment with high predictability and biological advantages. The improvement in technology has made it possible to simplify clinical processes. The aim of the present report was to describe the complete digital workflow of the Biologically oriented preparation technique for immediate posterior implant, immediate provisionalization and fabrication of definitive implant crowns. CLINICAL CONSIDERATIONS: The surgical process and prosthetic management to preserve the gingival contours of the extracted natural tooth during immediate implant placement and provisionalization are described. Additionally, during the same clinical intervention, the definitive intraoral digital implant scans for capturing the implant position, peri-implant tissue contours, adjacent and antagonist dentition, and profile emergence of the interim implant crown are captured for the fabrication of the definitive crown. CONCLUSIONS: Based on the technique described, the immediate implant placement and provisionalization in the posterior area provides biological and clinical advantages, reducing the number of abutment-implant disconnections and the number of clinical appointments, as well as increases patient comfort. CLINICAL SIGNIFICANCE: The present article describes a technique for an immediate implant placement and provisionalization in the posterior region for maintaining the gingival architecture of the extracted tooth. During the same appointment, the implant position, peri-implant tissue contours, and adjacent and antagonist dentition, and profile emergence of the interim implant crown are captured by using an intraoral scanner and used for the fabrication of the definitive crown. This technique aims to reduce the number of abutment-implant disconnections and clinical appointments.

Comparison of surface roughness of additively manufactured implant-supported interim crowns fabricated with different print orientations.

PURPOSE: To assess the influence of print orientation on the surface roughness of implant-supported interim crowns manufactured by using digital light processing (DLP) 3D printing procedures. MATERIALS AND METHODS: An implant-supported maxillary right premolar full-contour crown was obtained. The interim restoration design was used to fabricate 30 specimens with 3 print orientations (0, 45, and 90 degrees) using an interim resin material (GC Temp PRINT) and a DLP printer (Asiga MAX UV) (n = 10). The specimens were manufactured, and each was cemented to an implant abutment with autopolymerizing composite resin cement (Multilink Hybrid Abutment). Surface roughness was assessed on the buccal surface of the premolar specimen by using an optical measurement system (InfiniteFocusG5 plus). The data were analyzed with a Shapiro-Wilk test, resulting in a normal distribution. One-way ANOVA and the Tukey HSD tests were selected (α = 0.05). RESULTS: Statistically significant discrepancies were found in the surface roughness mean values among the groups tested (p < 0.001). The lowest mean ± standard deviation surface roughness was found with the 90-degree group (1.2 ± 0.36 µm), followed by the 0-degree orientation (2.23 ± 0.18 µm) and the 45-degree group (3.18 ± 0.31 µm). CONCLUSIONS: Print orientation parameter significantly impacted the surface roughness of the implant-supported interim crowns manufactured by using the additive procedures tested.

A guide for selecting the intraoral scan extension when fabricating tooth- and implant-supported fixed dental prostheses.

OBJECTIVES: To describe a new classification for intraoral scans based on the scan extension and to introduce a decision guideline to choose the scan extension for fabricating tooth- and implant-supported fixed dental prostheses (FDPs). OVERVIEW: Multiple operator- and patient-related factors have been identified that can decrease the scanning accuracy of intraoral scanners (IOSs), including scan extension. However, the decision criteria for selecting scan extension for fabricating tooth- and implant-supported restorations is unclear. Based on the extension of the intraoral digital scans, three types of scans can be defined: half-arch (anterior or posterior), extended half-arch, and complete-arch scan. Variables to consider when choosing the scan extension include the number and location of units being restored, as well as the extension and location of edentulous areas. Additionally, the accuracy of the virtual definitive cast and the accuracy of the maxillomandibular relationship captured by using IOSs should be differentiated. CONCLUSIONS: A decision tree for selecting the scan extension is presented. The decision is based on the number and location of units being restored, and the extension and location of edentulous areas. Intraoral scans with reduced scan extension are indicated when fabricating tooth- and implant-supported crowns or short-span fixed prostheses, when the patient does not have more than one missing tooth in the area of the dental arch included in the scan. For the remaining clinical conditions, complete-arch intraoral scans are recommended. CLINICAL SIGNIFICANCE: Scan extension is a clinician's decision that should be based on the number and location of units being restored and the extension and location of edentulous areas. Intraoral scans with a reduced scan extension is recommended, when possible.

In Vitro Analysis of the Removability of Fractured Prosthetic Screws within Endosseous Implants Using Conventional and Mechanical Techniques.

STATEMENT OF PROBLEM: The extraction of fractured abutment screws can be a difficult challenge to overcome. PURPOSE: To compare the removal capacity, dental implant connection damage, and time required to remove the fractured abutment screws between three drilling techniques and a conventional method. MATERIALS AND METHODS: A total of 180 prefabricated screw-retained abutments were intentionally fractured in internal connection dental implants after being subjected to a cyclic load and a static compression load. Afterwards, three operators randomly removed the fractured abutment screws with the following drilling techniques and a conventional method: A: a conventional technique using an exploration probe and ultrasonic appliance (n = 45), Rhein83® (n = 45); B: Sanhigia® (n = 45); C: Phibo® (n = 45). Two-way ANOVA models were estimated to evaluate the mean time according to the method and operator used. RESULTS: The probability of removal of the screws with mobility was twelve times higher than that of the screws without mobility (OR = 12.4; p < 0.001). The success rate according to the operators did not show statistically significant differences (p = 0.371). The location of the fractured screw did not affect removal success (p = 0.530). The internal thread of the implant was affected after the removal process in 9.8% of the cases. The mean extraction time was 3.17 ± 2.52 min. The Rhein83® method showed a success rate of 84.4%, followed by the Phibo® and conventional methods (71.1%) and the Sanhigia® method (46.7%). CONCLUSIONS: The Rhein83® drilling technique increases the removal probability of fractured abutment screws. The initial mobility of the fragment is also a significant factor in the removal success.

Comparison of the Surface Roughness of CAD/CAM Metal-Free Materials Used for Complete-Arch Implant-Supported Prostheses: An In Vitro Study.

The roughness of the intra-oral surfaces significantly influences the initial adhesion and the retention of microorganisms. The aim of this study was to analyze the surface texture of four different CAD-CAM materials (two high-performance polymers and two fifth-generation zirconia) used for complete-arch implant-supported prostheses (CAISPs), and to investigate the effect of artificial aging on their roughness. A total of 40 milled prostheses were divided into 4 groups (n = 10) according to their framework material, bio.HPP (B), bio.HPP Plus (BP), zirconia Luxor Z Frame (ZF), and Luxor Z True Nature (ZM). The areal surface roughness "Sa" and the maximum height "Sz" of each specimen was measured on the same site after laboratory fabrication (lab as-received specimen) and after thermocycling (5-55 °C, 10,000 cycles) by using a noncontact optical profilometer. Data were analyzed using SPSS version 28.0.1. One-way ANOVA with multiple comparison tests (p = 0.05) and repeated measures ANOVA were used. After thermocycling, all materials maintained "Sa" values at the laboratory as-received specimen level (p = 0.24). "Sz" increased only for the zirconia groups (p = 0.01). B-BP exhibited results equal/slightly better than ZM-ZF. This study provides more realistic surface texture values of new metal-free materials used in real anatomical CAISPs after the manufacturing and aging processes and establishes a detailed and reproducible measurement workflow.

Impact of color temperature and illuminance of ambient light conditions on the accuracy of complete-arch digital implant scans.

OBJECTIVE: The purpose of the present study was to assess the influence of color temperature and illuminance of ambient light on the accuracy of different intraoral scanners (IOSs) in complete-arch implant scans. METHODS: An edentulous model with six implants and scan bodies was digitized by using a laboratory scanner (DW-7-140; Dental Wings) to obtain a reference mesh. Fifteen scans were performed employing two intraoral scanners (Trios 4;3Shape A/S and i700; Medit Co) at two illuminances (500 and 1000 lux) and three color temperatures (3200, 4400, and 5600 K). Scanning accuracy was measured by using a 3D metrology software program (Geomagic Control X). Kruskal-Wallis, one-way ANOVA, and pairwise comparison tests were used to analyze the data (α = .05). RESULTS: Significant differences in trueness and precision values were found among the different IOSs under the same ambient lighting condition and among the different lighting conditions for a given IOS (p < .05) except for trueness in i700 groups (p > .05). CONCLUSIONS: The influence on the accuracy of color temperature and illuminance varied depending on the intraoral scanner. An optimal ambient scanning light condition was not found; this should be adjusted based on the specific IOS system used. 3200 K of ambient light influences the precision of i700 when performed at 1000 lux, decreasing the accuracy. The variation of color temperature at the same illuminance does not affect the scanning accuracy of TRIOS 4, which obtained better accuracy in all scans at 1000 lux.

Degree of Standardisation in Ceramic Gingival Systems.

No gingival shade guide exists that can be used as a 'gold standard' in gingival shade selection. This research, therefore, aimed to determine whether comparable results in subjective gingival shade selection can be achieved using basic gingival colours produced by distinct manufacturers. It also aimed to explore how coverage of the colour space is affected by mixing these basic colours to create additional shades. To achieve these objectives, the basic gingival colours of three ceramic systems (Heraceram, Kulzer, Madrid, Spain; Vita VM9, Vita Zahnfabrik, Bad Säckingen, Germany; IPS Style, Ivoclar, Schaan, Liechtenstein) were analysed. The colour systems were expanded by creating porcelain gingival samples, whose colours were obtained by mixing the basic colours, altering each mixture by increments of 10%, and respecting the numerical order used by manufacturers to identify the colours. The colour coordinates of the basic and additional colours were recorded using spectrophotometry, and the intra- and inter-system colour differences were calculated using the Euclidean (ΔEab) and CIEDE2000 (ΔE00) formulae. None of the basic colours in the three systems, despite their similar nomenclature, were found to be interchangeable (the colour differences exceeded the gingival acceptability threshold: ΔE00 2.9 units). The expanded gingival colour systems, with mixtures altered by 10% increments, notably increased the gingival colour space covered by the original systems. The authors concluded that there are clear differences between the basic gingival colours produced by distinct manufacturers using the same nomenclature. Ceramic samples produced by mixing basic gingival colours are a resource with the potential to improve subjective gingival shade matching.

Discrepancies in the occlusal devices designed by an experienced dental laboratory technician and by 2 artificial intelligence-based automatic programs.

STATEMENT OF PROBLEM: Artificial intelligence (AI) models have been developed for different applications, including the automatic design of occlusal devices; however, the design discrepancies of an experienced dental laboratory technician and these AI automatic programs remain unknown. PURPOSE: The purpose of this in vitro study was to compare the overall, intaglio, and occlusal surface discrepancies of the occlusal device designs completed by an experienced dental laboratory technician and two AI automatic design programs. MATERIAL AND METHODS: Virtually articulated maxillary and mandibular diagnostic casts were obtained in a standard tessellation language (STL) file format. Three groups were created depending on the operator or program used to design the occlusal devices: an experienced dental laboratory technician (control group) and two AI programs, namely Medit Splints from Medit (Medit group) and Automate from 3Shape A/S (3Shape group) (n=10). To minimize the discrepancies in the parameter designs among the groups tested, the same printing material and design parameters were selected. In the control group, the dental laboratory technician imported the articulated scans into a dental design program (DentalCAD) and designed a maxillary occlusal device. The occlusal device designs were exported in STL format. In the Medit and 3Shape groups, the diagnostic casts were imported into the respective AI programs. The AI programs automatically designed the occlusal device without any further operator intervention. The occlusal device designs were exported in STL format. Among the 10 occlusal designs of the control group, a random design (shuffle deck of cards) was used as a reference file to calculate the overall, intaglio, and occlusal discrepancies in the specimens of the AI groups by using a program (Medit Design). The root mean square (RMS) error was calculated. Kruskal-Wallis, and post hoc Dwass-Steel-Critchlow-Fligner pairwise comparison tests were used to analyze the trueness of the data. The Levene test was used to assess the precision data (α=.05). RESULTS: Significant overall (P<.001), intaglio (P<.001), and occlusal RMS median value (P<.001) discrepancies were found among the groups. Significant overall RMS median discrepancies were observed between the control and the Medit groups (P<.001) and the control and 3Shape groups (P<.001). Additionally, significant intaglio RMS median discrepancies were found between the control and the Medit groups (P<.001), the Medit and 3Shape groups (P<.001), and the control and 3Shape groups (P=.008). Lastly, significant occlusal RMS median discrepancies were found between the control and the 3Shape groups (P<.001) and the Medit and 3Shape groups (P<.001). The AI-based software programs tested were able to automatically design occlusal devices with less than a 100-µm trueness discrepancy compared with the dental laboratory technician. The Levene test revealed significant overall (P<.001), intaglio (P<.001), and occlusal (P<.001) precision among the groups tested. CONCLUSIONS: The use of a dental laboratory technique influenced the overall, intaglio, and occlusal trueness of the occlusal device designs obtained. No differences were observed in the precision of occlusal device designs acquired among the groups tested.

Coverage error and shade-match accuracy in three ceramic gingival systems.

STATEMENT OF PROBLEM: Research into the coverage error (CE) of gingival systems that have been expanded by using ceramic specimens created by mixing basic colors is lacking. PURPOSE: The purpose of this in vitro study was to compare the CEs of 3 ceramic gingival color systems that have been expanded with basic-color mixtures from a sample of 360 White participants and to classify the participants according to the accuracy of the shade match achieved with each system. MATERIAL AND METHODS: L*a*b* color coordinates were recorded in 3 zones of attached gingiva for 360 White participants with healthy gingival tissue (187 men and 173 women). The CEs were calculated for 3 ceramic gingival systems that had been expanded with specimens obtained by mixing the basic colors in consecutive order, the color percentages in each mixture having been altered by 10% increments. The systems were Heraceram (Kulzer GmbH) (n=51); Vita VM9 (Vita-Zahnfabrik) (n=41); and IPS Style (Ivoclar AG) (n=41). The participants were classified into 3 groups according to how well the selected shade matched their gingival color (excellent, acceptable, or poor). The data were analyzed using a 1-way ANOVA with a randomized block design and the homogeneity of proportions test (α=.05). RESULTS: Statistically significant differences were found between the CEs of the 3 expanded gingival systems in the 3 zones where gingival color was measured (P<.001). The expanded Heraceram system had the smallest CE (ΔE00: minimum 2.66 in the middle zone and maximum 2.95 at the mucogingival line). In the 3 gingival zones, the expanded IPS Style system produced the largest percentage of participants with a poor shade match (ΔE00: minimum 71.4% at the mucogingival line and maximum 75.8% at the free gingival margin), while the expanded Heraceram system had the lowest percentage of participants with a poor shade match (ΔE00: minimum 33.3% in the middle zone and maximum 41.7% at the mucogingival line). CONCLUSIONS: The CEs calculated for the expanded Vita VM9 and IPS Style ceramic gingival color systems exceeded the clinical acceptability thresholds in the 3 zones examined. According to the ΔE00 formula, the gingival color of at least 33% of participants matched poorly with the expanded systems studied.

Influence of the Use of Transepithelial Abutments vs. Titanium Base Abutments on Microgap Formation at the Dental Implant-Abutment Interface: An In Vitro Study.

This in vitro study aimed to assess the presence of microgaps at the implant-abutment interface in monolithic zirconia partial implant-supported fixed prostheses on transepithelial abutments versus Ti-base abutments. METHODS: Sixty conical connection dental implants were divided into two groups (n = 30). The control group consisted of three-unit bridge monolithic zirconia connected to two implants by a transepithelial abutment. The test group consisted of monolithic zirconia three-unit restoration connected to two implants directly by a titanium base (Ti-base) abutment. The sample was subjected to thermocycling (10,000 cycles at 5 °C to 55 °C, dwelling time 50 s) and chewing simulation (300,000 cycles, under 200 N at frequencies of 2 Hz, at a 30° angle). The microgap was evaluated at six points (mesiobuccal, buccal, distobuccal, mesiolingual, lingual, and distolingual) of each implant-abutment interface by using a scanning electron microscope (SEM). The data were analyzed using the Mann-Whitney U tests (p > 0.05). RESULTS: The SEM analysis showed a smaller microgap at the implant-abutment interface in the control group (0.270 µm) than in the test group (3.902 µm). Statistically significant differences were observed between both groups (p < 0.05). CONCLUSIONS: The use or not of transepithelial abutments affects the microgap size. The transepithelial abutments group presented lower microgap values at the interface with the implant than the Ti-base group in monolithic zirconia partial implant-supported fixed prostheses. However, both groups had microgap values within the clinically acceptable range.

Factors that influence the accuracy of maxillomandibular relationship at maximum intercuspation acquired by using intraoral scanners: A systematic review.

OBJECTIVE: To review the factors that influence the accuracy of the maxillomandibular relationship at maximum intercuspation (MIP) acquired by using intraoral scanners (IOSs). MATERIAL AND METHODS: A systematic search was performed using five databases: MEDLINE/PubMed, Cochrane, Embase, World of Science, and Scopus. A manual search was also completed. Studies assessing the factors that influence the MIP acquired by using IOSs were included and organized based on the analyzed factor. Studies were evaluated by applying the Joanna Briggs Institute Critical Appraisal Checklist. RESULTS: Twenty-nine articles were included. Seven factors have been identified: IOS system, scan extension, edentulous areas, number, location, and extension of occlusal records, occlusal force, tooth mobility, and alignment methods. Nine studies evaluated the influence of IOS system. Four studies assessed the influence of the extension of the arch scan. Three studies evaluated the effect of edentulous spaces. Four studies agreed on the impact of the number, location, and extension of the occlusal records on the MIP accuracy. One study assessed the influence of the occlusal force, showing a smaller average interocclusal space with increased occlusal force. One study evaluated the influence of tooth mobility. Seven studies analyzed the influence of the alignment method on the MIP accuracy. CONCLUSIONS: Most of the studies reported no difference on the MIP accuracy between half- and complete-arch scans. Areas with 2 or more missing teeth reduce the MIP accuracy. A bilateral and frontal record including 2 teeth or a bilateral posterior occlusal including at least 4-teeth is indicated for maximizing the MIP accuracy. CLINICAL IMPLICATIONS: When a complete-arch intraoral scans is obtained, a bilateral and frontal record including 2 teeth or a bilateral posterior occlusal record including at least 4-teeth is recommended for maximizing the accuracy of the MIP. When a half-arch intraoral scan is acquired, a posterior occlusal record including at least 4-teeth is indicated for optimizing the accuracy of the MIP.

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.

Influence of Implant Scanbody Material and Intraoral Scanner on the Accuracy of Complete-Arch Digital Implant Impressions.

PURPOSE: To evaluate the accuracy of complete-arch digital implant impressions using different intraoral scan body (ISB) materials and intraoral scanners (IOSs). MATERIALS AND METHODS: The mandibular dental cast of an edentulous patient with six tissue-level dental implants was used as master cast. Two types of ISBs, polyether-ether-ketone (PEEK) and plasma-coated medical titanium, were used with five IOSs: TRIOS 4 (T4), Virtuo Vivo (VV), Medit i700 (Mi700), iTero5D (i5D), and Primescan (PS). To assess accuracy, digital impressions (n=10) with each IOS and ISB were compared to two reference models obtained by digitizing the master cast with each ISB type using a desktop scanner (IScan4D LS3i) and importing the scan data into metrology software (Geomagic Control X). Root-mean-square (RMS) error was employed to evaluate overall deviation values (trueness), while precision was determined using the standard deviation (SD) of RMS values. Statistical significance was set at P < 0.05. The Kruskal-Wallis test was used, followed by the pairwise comparison method with Bonferroni correction (α=.05). RESULTS: An interaction between ISB material and IOS was found (P=0.001). Plasma-coated medical titanium ISBs demonstrated significantly higher trueness and precision compared to PEEK ISBs with T4 (P=0.001), Mi700 (P=0.001; P=0.004), and i5D (P=0.001). Conversely, VV exhibited higher trueness and precision values with PEEK ISBs (P=0.005; P=0.003). PS provided the highest trueness and precision regardless of the ISB material (P=0.912). T4 showed the lowest accuracy for PEEK ISBs, and VV for plasma-coated medical titanium ISBs. CONCLUSION: Except for PS, all IOSs showed significant differences between ISB materials. PS demonstrated the highest accuracy with both ISB materials, whereas T4 had the lowest accuracy for PEEK ISBs, and VV showed the lowest accuracy for plasma-coated medical titanium ISBs.

Influence of the dental arch and number of cutting-off and rescanning mesh holes on the accuracy of implant scans in partially edentulous situations.

OBJECTIVES: To evaluate the influence of the dental arch and cutting-off and rescanning procedures on the accuracy of complete-arch implant scans in partially edentulous arches. MATERIAL AND METHODS: A maxillary and a mandibular partially edentulous typodont with implant abutment analogs placed in the right and left first molar and right central incisor sites were digitized to create reference models by using an industrial optical scanner (7 Series Desktop Scanner; Dentalwings). Two experimental groups were scanned using an intraoral scanner (IOS) (TRIOS 4; 3Shape A/S): the Maxillary group (Mx) and the Mandibular group (Mb). Four subgroups were generated depending on the number of rescanned mesh holes: No holes (Mx-G0, Mb-G0), 1 hole (Mx-G1, Mb-G1), 2 holes (Mx-G2, Mb-G2) and 3 holes (Mx-G3, Mb-G3). A 3-dimensional metrology software (Geomagic Control X; 3D Systems) was used to measure the difference between the reference and the experimental scans computing the root mean square (RMS) error calculation. Two-way ANOVA and a post-hoc Tukey test were used to analyze the trueness data (α=0.05). Levene test was used to evaluate the prevision (α=0.05). RESULTS: The Mx group obtained a trueness mean value of 54 ± 17 µm and a mean precision value of 54 ± 17 µm, while the Mb group presented a trueness mean value of 67 ± 23 µm and a mean precision value of 66 ± 22 µm. The Mx group demonstrated significantly better trueness than the Mb group (P<.001). The G0 and G1 subgroups had the highest trueness values among the subgroups tested. No significant difference was observed between G0 and G1, G1 and G2, and G2 and G3 subgroups in trueness and precision. However, the G0 had significantly better trueness and precision values compared to G2 and G3 subgroups. In addition, the G1 had significantly better trueness values than the G3 subgroup. However, the Levene test revealed no difference in the precision mean values among the subgroups tested. CONCLUSIONS: Implant scanning trueness was affected by the dental arch and the number of rescanned mesh holes using the IOS tested. A higher number of rescanned mesh holes decreased the scanning trueness. The stitching algorithm of the IOS software tested after the mesh hole scan demonstrated a significant error, especially when multiples mesh holes are involved in the same arch. CLINICAL SIGNIFICANCE: Given that cutting-off and rescanning techniques can reduce trueness, clinicians should consider whether these techniques are necessary in complete digital workflows. This is particularly important when fabricating multiple single implant-supported restorations in the same arch.

Accuracy, scanning time, and patient satisfaction of stereophotogrammetry systems for acquiring 3D dental implant positions: A systematic review.

PURPOSE: To evaluate accuracy, scanning time, and patient satisfaction of photogrammetry (PG) systems for recording the 3D position of dental implants. 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 use of commercially available PG systems 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. RESULTS: A total of 14 articles were included: 3 in vivo, 6 in vitro, and 6 case report manuscripts. One clinical study evaluated trueness, another one tested precision, and the third one assessed impression time and patient and operator satisfaction. All the in vitro studies evaluated the trueness and precision of a PG system. Additionally, all the reviewed studies investigated completely edentulous conditions with multiple implants. The number of placed implants per arch among the reviewed clinical studies varied from 4 to 8 implants, while the number of implants placed on the reference casts included 4, 5, 6, or 8 implants. Not all the studies compared the accuracy of PG systems with conventional impression methods, using intraoral scanners as additional experimental groups. For the PIC system, trueness ranged from 10 to 49 µm and precision ranged from 5 to 65 µm. For the iCam4D system, trueness ranged from 24 to 77 µm and the precision value ranged from 2 to 203 µm. CONCLUSIONS: PG systems may provide a reliable alternative for acquiring the 3D position of dental implants. However, this conclusion should be interpreted carefully, as one study reported a mean precision value of one PG system higher than the clinically acceptable discrepancy. Lower scanning time and higher patient and operator satisfaction have been reported when compared with conventional techniques. Further studies are needed to increase the evidence regarding the accuracy, scanning time, and patient and operator satisfaction of the commercially available PG systems.