Impression Scanning Research Articles

Accuracy of digital tooth preparations recorded using the plaster model scanning technique and two silicone impression scanning techniques

Accuracy of digital tooth preparations recorded using the plaster model scanning technique and two silicone impression scanning techniques

Trueness of Extraoral Digital Impressions for Full-Arch Implant Impressions-In Vitro Study.

Direct scanning of silicone impressions is a valid technique. However, studies in implant-supported rehabilitations are lacking. This in vitro study aims to compare the trueness of impressions obtained with two types of silicone and their corresponding stone casts, using two laboratory scanners in a full-arch implant rehabilitation. A master cast with six dental implants was scanned with a 12-megapixel scanner to obtain a digital master cast. Ten implant impressions were made using two silicones (Zhermack and Coltene) with the open-tray technique. The impressions and stone casts were scanned by two extraoral scanners (Identica T500, Medit; and S600 ARTI, Zirkonzhan). Trueness was assessed by comparing linear and angular distances in digital casts with the master cast. A p < 0.05 significance level was considered. The results showed that for the linear measurements, 72% were higher than the master cast measurements, and no consistent pattern was observed in the angular measurements. The greatest deviations were detected between the most posterior implants, with mean values ranging between 173 and 314 µm. No significant differences were found between scanners. However, differences were observed in the distances between silicones (46.7%) and between impressions and stone casts (73.3%). This work demonstrates that the direct scanning of silicone impressions yields results comparable to those obtained from scanning gypsum casts in full-arch implant-supported rehabilitation.

Accuracy of impression scan bodies for complete arch fixed implant-supported restorations

Statement of problemDespite the extensive studies on and comparisons of different implant impression techniques for completely edentulous patients, studies on novel techniques that combine conventional impression making with digital scanning are lacking. PurposeThe primary aim of this study was to compare the accuracy of the impression scan body technique with conventional impression making and digital scanning for a completely edentulous mandibular arch. The secondary aim was to assess the relationship between different implant angulations and interimplant distances in relation to the recording accuracy. Material and methodsAn edentulous mandibular definitive cast (control) was designed with 5 implants placed at different angles and interimplant distances. Three recording techniques were tested: a conventional impression with splinted copings (conventional) (n=15), an impression scan body technique where impression scan bodies were attached to the splinted impression copings in a conventional elastomeric impression and then digitally scanned with an extraoral scanner (n=15), and an intraoral digital scanning technique (digital) (n=15). For comparison, the definitive cast and the conventional impression stone casts were digitized into standard tessellation language (STL) datasets using the extraoral scanner. The 3-dimensional (3D) deviations between the 3 test groups and the control were calculated by superimposing the STL datasets. The 3D deviations from the control were compared by using the Kruskal-Wallis test followed by the Dunn post hoc test (α=.05). The Mann-Whitney test was used to investigate the effect of implant angulation and interimplant distance on impression accuracy (α=.05). ResultsThe conventional splinted-coping impression technique showed a mean 3D deviation of 0.408 mm. The impression scan body and intraoral digital scan showed similar mean 3D deviations, 0.219 mm and 0.257 mm, respectively (P=.334). Both techniques showed significantly lower 3D deviations than the conventional technique (P<.001). Implants at an angle of 5 degrees and 10 degrees showed a statistically significant difference (P=.010) with mean 3D deviations of 0.340 mm and 0.396 mm, respectively. Implants with 5-mm and 10-mm interimplant distance showed a significant difference (P<.001) with mean 3D deviations of 0.301 mm and 0.423 mm, respectively. ConclusionsThe impression scan body technique is comparable with intraoral digital scanning for a completely edentulous arch. Increased implant angulation and increased interimplant distance significantly reduced the accuracy of implant impression making or scanning.

Immediate Loading of Zygomatic Implants Using a Dual Scan Technique

The immediate loading protocol has become increasingly popular due to the progressive growth in demand for a reduction in treatment times. The possibility of applying this protocol would depend on certain important factors. The application of the digital workflow mentioned in the protocol guarantees rapidity, precision, and esthetics. This report aims to describe a fully digital workflow using a dual scan impression technique to fabricate immediate fixed complete dentures (FCDs) for zygomatic and standard implants. A 58-year-old female patient requested treatment for her severely atrophic maxilla, and four unrehabilitated implants in the mandible. After proper diagnosis and planification, four zygomatic implants and two standard implants were placed. During the surgery, transmucosal abutments were placed on all implants. After suturing, the positions of the implants were recorded using a stereophotogrammetric technique, creating a standard tessellation (STL) file. In the lower arch, the second phase of the surgery was carried out: the transmucosal abutments were placed, and then the implant positions were recorded in the same way. The soft tissues were rescanned after suturing with an intraoral scanner (IOS), and all STL files were aligned to obtain the virtual final models. The pre-design after virtual modifications was aligned with the definitive models. The provisional prostheses were milled and placed after six hours after the surgery, and the definitive prostheses were placed six months after the surgery. The dual scan technique used obtained a precise fit for both the provisional and definitive FCDs. This technique might be an effective and reliable alternative for the fabrication of immediate and definitive screw-retained FCDs in a completely digital workflow. The time taken for scanning and fabrication was reduced, and the clinician’s and patient’s satisfaction were improved.

INTRAORAL SCANNING AND CONVENTIONAL IMPRESSION MAY HAVE SIMILAR TIME EFFICIENCY FOR COMPLETE COVERAGE CROWNS AND THREE-UNIT FIXED TOOTH-SUPPORTED PROSTHESES.

Bandiaky ON, Le Bars P, Gaudin A, Hardouin JB, Cheraud-Carpentier M, Mbodj EB, Soueidan A. Comparative assessment of complete-coverage, fixed tooth-supported prostheses fabricated from digital scans or conventional impressions: A systematic review and meta-analysis. J Prosthet Dent. 2022 Jan;127(1):71-79. doi: 10.1016/j.prosdent.2020.09.017. Epub 2020 Nov 2. PMID: 33,143,901. Information not available TYPE OF STUDY/DESIGN: Systematic review with meta-analysis of data.

Evaluation of custom posts and cores fabricated by two digital technologies in core and post space dimensions.

To evaluate the adaptability between posts and post spaces and the rationality of cores fabricated by two digital custom post-and-core processes. Titanium post-and-cores were fabricated by digital scanning impression technology or digital scanning wax-pattern technology on tooth defect molds of incisors, premolars, and molars, with traditional lost-wax casts of these teeth as the controls. Micro-CT and a laboratory scanner were used to determine intervals between post wall and root canal wall of the root apex, middle, and cervix of each sample in cross-, sagittal, and coronal sections; intervals between the end of post and tooth; diameters of cervical, middle, and incisal part at cross-, sagittal, and coronal sections of each sample, as well as shoulder widths. The three fabrication processes showed significant differences in intervals between post-and-core prostheses and root canal walls, diameters of all parts of cores, and shoulder widths. Scanning impressions showed significant advantages in the main part of post-and-cores in incisors and premolars, while the scanning wax-pattern process showed obvious inferiorities in premolars and molars. As to core spatial size, values of measured sites in the scanning impression process were closer to the standard than those of the traditional process, while differences between the measured value of the scanning wax-pattern process were much more obvious than in the traditional process. The use of digital custom post-and-core scanning impressions improved the rationality and precision of post-and-core dimensions compared with two other processes.

Effectiveness of creating digital twins with different digital dentition models and cone-beam computed tomography

Distortion of dentition may occur in cone-beam computed tomography (CBCT) scans due to artifacts, and further imaging is frequently required to produce digital twins. The use of a plaster model is common; however, it has certain drawbacks. This study aimed to assess the feasibility of different digital dentition models over that of plaster casts. Plaster models, alginate impressions, intraoral scan (IOS) images, and CBCT images of 20 patients were obtained. The desktop model scanner was used to scan the alginate impression twice, five minutes and two hours after impression-making. Using an IOS, the full arch was scanned in segments using CS 3600 and simultaneously with i700 wireless. The digital twins obtained from the alginate impression and IOS were superimposed with those obtained from the plaster cast. The differences and distances at each reference point were measured. Scans of alginate impressions after two hours showed the greatest discrepancies, but these were all less than the CBCT voxel size of 0.39 mm. Alginate impression scans and IOS are suitable supplements to CBCT compared to the plaster model. Accuracy can be improved by scanning the alginate impression within five minutes or by intraoral scanning of the entire arch with segmentation.

An indirect method of verifying passive fit of complete arch implant-supported frameworks fabricated from photogrammetry scans

The passive fit of frameworks on multi-unit abutments has been considered crucial for the long-term success of complete arch, implant-supported, fixed prostheses. 1 Jokstad A. Shokati B. New 3D technologies applied to assess the long-term clinical effects of misfit of the full jaw fixed prosthesis on dental implants. Clin Oral Implants Res. 2015; 26: 1129-1134 Crossref PubMed Google Scholar Photogrammetry has demonstrated better accuracy than intraoral scanning and conventional impression techniques to record the position of implants. 2 Sallorenzo A. Gómez-Polo M. Comparative study of the accuracy of an implant intraoral scanner and that of a conventional intraoral scanner for complete-arch fixed dental prostheses. J Prosthet Dent. 2022; 128: 1009-1016 Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar However, errors introduced during fabrication may still compromise the passive fit of the definitive prosthesis, even with accurate scanning using the photogrammetry technique. 3 Al-Meraikhi H. Yilmaz B. McGlumphy E. Brantley W. Johnston W.M. In vitro fit of CAD-CAM complete arch screw-retained titanium and zirconia implant prostheses fabricated on 4 implants. J Prosthet Dent. 2018; 119: 409-416 Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar The current intraoral methods of verifying passive fit, including visual inspection, tactile sensation, radiography, disclosing materials, screw resistance test, and the Sheffield test, are subjective and not capable of detecting lingual or subgingival misfit. 4 Abduo J. Bennani V. Waddell N. Lyons K. Swain M. Assessing the fit of implant fixed prostheses: a critical review. Int J Oral Maxillofac Implants. 2010; 25: 506-515 PubMed Google Scholar In the conventional protocol, the definitive cast made from a custom tray elastomeric impression can be verified with a dental gypsum device. 5 Manzella C. Burello V. Bignardi C. Carossa S. Schierano G. A method to improve passive fit of frameworks on implant-supported prostheses: an in vivo study. Int J Prosthodont. 2013; 26: 577-579 Crossref PubMed Google Scholar However, since the frameworks made from photogrammetry are manufactured without a definitive cast, verifying the passive fit of the frameworks is challenging. 6 Rutkunas V. Larsson C. Vult von Steyern P. Mangano F. Gedrimiene A. Clinical and laboratory passive fit assessment of implant-supported zirconia restorations fabricated using conventional and digital workflow. Clin Implant Dent Relat Res. 2020; 22: 237-245 Crossref PubMed Scopus (11) Google Scholar In the treatment of the first patient, misfits were found between the frameworks and the 3-dimensional printed cast; therefore, the accuracy of the frameworks needed to be verified to determine whether the distortion was introduced during printing of the cast (Fig. 1A-C). An inexpensive and user-friendly method of verifying the passive fit of frameworks is described. Figure 1A, Intraoral view after removal of interim prosthesis. B, Impression scanning using photogrammetry technology. C, Misfits between framework and printed cast. D, Placement of abutment replicas. E, Fixture of replicas with dental gypsum. F, Evaluating fit of framework. View Large Image Figure Viewer Download Hi-res image

Effect of different intraoral scanners and post-space depths on the trueness of digital impressions.

The trueness of intraoral scanners (IOSs) has been evaluated in many clinical situations. However, the tests of their performance when scanning post-space preparations are still lacking. The aim of the present study was to compare the trueness of the digital impressions of post spaces with different depths, captured by means of different IOSs. Digital impressions of teeth (N = 16) with post spaces of depths of 8 mm and 10 mm were captured. Three IOSs were used, including Primescan AC, Medit i500 and CS 3600. The STL files were compared to the files obtained from the traditional impression scanning performed with an InEos X5 desktop scanner. Then, reverse engineering software measured the trueness values, which were analyzed using the two-way analysis of variance (ANOVA), followed by Tukey's post-hoc test. The significance level was set at p < 0.05. Significant differences were found between the scanners in terms of root mean square (RMS) values (p < 0.001). The highest RMS value was found for CS 3600 (0.30 ±0.11 mm), followed by Primescan AC (0.26 ±0.09 mm), while the lowest value was found for Medit i500 (0.18 ±0.05 mm). The 8-millimeter-deep post spaces had a significantly higher RMS value than the 10-millimeter-deep ones (0.28 ±0.10 mm and 0.21 ±0.09 mm, respectively) (p = 0.009). The Medit i500 scanner showed the highest post-space digital impression trueness as compared to Primescan AC and CS 3600. In the digital impressions captured with CS 3600, the 10 mm postspace depth had higher trueness than the 8 mm depth. Moreover, CS 3600 was less able to capture the full length of both the 8 mm and 10 mm post-space depths than Primescan AC and Medit i500.

The precision of two alternative indirect workflows for digital model production: an illusion or a possibility?

ObjectiveDespite the clear drive from both research and clinical dentistry toward digital transformation, there are limitations to implementing intra-oral scanning (IOS) into daily dental practice. This study aimed to compare the precision of digital models obtained from two alternative indirect workflows to direct IOS.Material and methodsTwo indirect digital workflows were evaluated in this study. In the IOS group (direct), IOS directly obtained digital impressions of participants’ upper and lower dental arches, while in the Scan Impression (Scan Imp) group (indirect), a desktop scanner scanned silicone-based impressions of upper and lower whole arches that were taken with plastic trays. In the cone-beam computed tomography impression (CBCT Imp) group (indirect), a CBCT machine scanned the silicone-based impressions. Then, the precision of the entire arch and individual teeth for all digital impressions was virtually quantified. Following superimposition, differences between standard tessellation language (STL) files obtained from both—direct and indirect—methods were evaluated by color-mapping and measuring the surface distance between superimposed STL files. Furthermore, 18 linear measurements were taken from each digital model. ANOVA with repeated measures, Pearson coefficient, and intraclass correlation coefficient were used for intergroup comparisons.ResultsThe digital models obtained from the two indirect workflows differed from the IOS in some dental and intra-arch measurements but were considered clinically acceptable. Ranked against IOS, CBCT Imp models had greater precision, followed by Scan Imp.ConclusionDigital models obtained from two indirect, alternative workflows, desktop, and CBCT scanning of impression, have clinically acceptable accuracy and reliability of tooth size and intra-arch measurements, providing the use of proper methodologies.Clinical relevanceThere are some limitations to implementing IOS in daily clinical practice. However, several alternative digital model production techniques might provide an affordable solution. Although they may insignificantly differ in accuracy, all can be applied clinically.

Influence of Direct and Indirect Digital Data Capturing Techniques on Marginal Accuracy and Internal Fit of CAD/CAM Fabricated PEEK and Zirconia Crowns

Purpose: The aim of this study was to evaluate the marginal and internal fitness of PEEK and Zirconia crowns fabricated by three different impression techniques. Materials and methods: Thirty standardized acrylic die models were prepared. Dies were divided into two main groups (n= 15): Group 1: CAD/CAM fabricated zirconia crowns. Group 2: CAD/CAM fabricated PEEK crowns. Each group was subdivided into three subgroups (n= 5), according to the impression technique using for data acquisition: Sub-group (A): direct digital scans of the model used intraoral digital scanner. Sub-group (B): indirect digital scans of the silicon impressions using extraoral scanner. Sub-group (C): indirect digital scans of the stone casts obtained from silicon impressions using extraoral scanner. Crowns were then designed and fabricated. Marginal and internal gaps were measured using silicone replica technique and field digital microscope. Results: Independent t-test was used for comparison between groups. Comparisons between subgroups were performed by one-way analysis of variance (ANOVA) test, followed by Bonferroni’s post hoc test. In Zirconia group, the highest mean value was recorded in stone cast scan group, followed by intraoral scan, with the least value recorded in impression scan subgroup. In PEEK group, the highest mean value was recorded in stone cast group, followed by impression scan, with the least value recorded in intraoral scan subgroup. Conclusions: All tested crowns showed marginal gap distance values within the clinically acceptable levels. PEEK crowns had lower vertical marginal gap distance than zirconia crowns with different scanning techniques.

Influence of Direct and Indirect Digital Data Capturing Techniques on Marginal Accuracy and Internal Fit of CAD/CAM Fabricated PEEK and Zirconia Crowns

Purpose: The aim of this study was to evaluate the marginal and internal fitness of PEEK and Zirconia crowns fabricated by three different impression techniques. Materials and methods: Thirty standardized acrylic die models were prepared. Dies were divided into two main groups (n= 15): Group 1: CAD/CAM fabricated zirconia crowns. Group 2: CAD/CAM fabricated PEEK crowns. Each group was subdivided into three subgroups (n= 5), according to the impression technique using for data acquisition: Sub-group (A): direct digital scans of the model used intraoral digital scanner. Sub-group (B): indirect digital scans of the silicon impressions using extraoral scanner. Sub-group (C): indirect digital scans of the stone casts obtained from silicon impressions using extraoral scanner. Crowns were then designed and fabricated. Marginal and internal gaps were measured using silicone replica technique and field digital microscope. Results: Independent t-test was used for comparison between groups. Comparisons between subgroups were performed by one-way analysis of variance (ANOVA) test, followed by Bonferroni’s post hoc test. In Zirconia group, the highest mean value was recorded in stone cast scan group, followed by intraoral scan, with the least value recorded in impression scan subgroup. In PEEK group, the highest mean value was recorded in stone cast group, followed by impression scan, with the least value recorded in intraoral scan subgroup. Conclusions: All tested crowns showed marginal gap distance values within the clinically acceptable levels. PEEK crowns had lower vertical marginal gap distance than zirconia crowns with different scanning techniques.

Interobserver Agreement Rates on C-X-C Motif Chemokine Receptor 4-Directed Molecular Imaging and Therapy.

We aimed to evaluate the interobserver agreement rates in patients scanned with C-X-C motif chemokine receptor 4 (CXCR4)-directed PET/CT, including the rate of patients eligible for CXCR4-targeted radioligand therapy (RLT) based on scan results. Four independent observers reviewed 50 CXCR4-targeted [ 68 Ga]pentixafor PET/CT of patients with various solid cancers. On a visual level, the following items were assessed by each reader: overall scan impression, number of organ and lymph node (LN) metastases and number of affected organs and LN regions. For a quantitative investigation, readers had to choose a maximum of 3 target lesions, defined as largest in size and/or most intense uptake per organ compartment. Reference tissues were also quantified, including unaffected hepatic parenchyma and blood pool. Last, all observers had to decide whether patients were eligible for CXCR4-targeted RLT. Concordance rates were tested using intraclass correlation coefficients (ICCs). For interpretation, we applied the definition of Cicchetti (with 0.4-0.59 indicating fair; 0.6-0.74, good; 0.75-1, excellent agreement). On a visual level, fair agreement was achieved for an overall scan impression (ICC, 0.58; 95% confidence interval, 0.45-0.71). Organ and LN involvement (ICC, ≥0.4) demonstrated fair, whereas CXCR4 density and number of LN and organ metastases showed good agreement rates (ICC, ≥0.65). Number of affected organs and affected LN areas, however, showed excellent concordance (ICC, ≥0.76). Quantification in LN and organ lesions also provided excellent agreement rates (ICC, ≥0.92), whereas quantified uptake in reference organs provided fair concordance (ICC, ≥0.54). Again, excellent agreement rates were observed when deciding on patients eligible for CXCR4-RLT (ICC, 0.91; 95% confidence interval, 0.85-0.95). In patients scanned with CXCR4-targeted PET/CT, we observed fair to excellent agreement rates for both molecular imaging and therapy parameters, thereby favoring a more widespread adoption of [ 68 Ga]pentixafor in the clinic.

Marginal Gap and Internal Fit of Fixed Dental Prostheses Fabricated Using Intraoral vs Extraoral Scanning: A Systematic Review and Meta-analysis.

To compare the marginal gap and internal fit of fixed dental prostheses (FDPs) fabricated using intraoral vs extraoral scanning methods. MEDLINE/PubMed and the Cochrane database were searched. The focused PICO question was: For the fabrication of FDPs, does an intraoral scanning technique result in a different marginal gap than an extraoral scanning technique? The secondary outcome assessed was internal fit. Studies were selected based on the inclusion criteria, and a meta-analysis was performed. A total of 14 studies (10 in vitro and 4 in vivo) were included in the meta-analysis. Marginal gap in single crowns was evaluated in 5 studies, copings for single crowns in 5 studies, three-unit FDPs in 3 studies, and both single-crown and three-unit FDPs in 1 study. Significantly lower marginal gap was found with intraoral scanning compared to impression scanning (P < .001) and cast scanning (P < .001), and for impression scanning compared to cast scanning (P = .037). Internal fit was superior with intraoral scanning compared to impression scanning, and this difference was significant (P < .001). No significant differences were found in internal fit with cast scanning compared to intraoral or impression scanning. The mean marginal gap/internal fit was 188.3 μm/146.2 μm with intraoral scanning, 116.29 μm/168.2 μm with impression scanning, and 195.1 μm/229.1 μm with cast scanning. Marginal gap was lower with intraoral scanning than with impression scanning and cast scanning. Impression scanning showed less marginal gap than cast scanning. Internal fit with intraoral scanning was superior to impression scanning, but when compared to cast scanning, no difference was found.

Accuracy of Conventional and Digital Methods of Obtaining Full-Arch Dental Impression (In Vitro Study)

IntroductionThe current gold standard is a conventional impression made with various impression materials and trays and results in a gypsum cast. With the development of milling and printing materials in dentistry, especially zirconia, a digital model has become increasingly important.ObjectivesTo compare the accuracy of the conventional impression scan (CIS), gypsum cast scan (GCS), and digital impression scan (DIS) to obtain a full-arch digital model.Materials and methodsA resin reference cast was fabricated. It was scanned by an extra-oral scanner to measure its accuracy as a reference scanner. Eight conventional impressions of the reference cast were taken by polyvinyl siloxane and scanned. After that, they were poured with type IV dental stones and scanned too. The reference cast was scanned by an intraoral scanner eight separate times. Digital models within each group were superimposed individually to measure precision. In addition, each model from each group was superimposed on one model from the reference scanner precision group to measure trueness.ResultsThe reference scanner showed the highest accuracy among groups with a precision of 1.5±0.8 µm and a trueness of 5.5±1.9 µm (P<0.006), while precision values of gypsum cast were 8.1±1.7 µm and trueness values were 9.3±2.6 µm (P<0.012). Conventional impressions showed a precision of 14.06±2.01 µm and a trueness of 16.15±2.07 µm (P<0.012). Digital impressions were the least accurate among the groups, as precision values were 38.22±15.23 μm and trueness values were 35.19±8.7 μm (P<0.006).ConclusionThe gypsum cast scans showed the highest accuracy, followed by the conventional impression scans, and finally the digital impression scans, with no clinical significance.

Comparison of the dimensional and morphological accuracy of three-dimensional digital dental casts digitized using different methods.

The purpose of this study was to compare the accuracy of digital dental casts from plaster cast scanning (PCS), impression scanning (IPS), intraoral scanning (IOS), and cone-beam computed tomography (CBCT) scanning (CCS) methods. The maxillary and mandibular dental casts of 15 patients who needed CBCT scans for oral examination or treatment were digitized via four methods. 12 linear distance measurements of all digital dental casts were selected and acquired with software and compared to those of the reference plaster cast to evaluate the dimensional accuracy. Three-dimensional deviation analysis of the IPS, IOS and CCS groups with respect to the reference PCS group was performed to evaluate the morphological accuracy. The discrepancy in linear distances between the digital dental casts and reference plaster casts was statistically significant (p < 0.01). The dimensional accuracies of the PCS (0.06 ± 0.12mm) and IPS (0.03 ± 0.05mm) casts were better than those of the IOS (0.37 ± 0.30mm) and CCS (0.54 ± 0.40mm) casts. The one-sample t test showed that there were statistically significant differences between the discrepancies in 8 of the linear distances for the PCS group and 9 of the linear distances for the IPS group between the digital dental casts and reference plaster casts, with an ideal error of 0.00 (p < 0.05). The sequence of morphological accuracy from good to poor was maxillary and mandibular IPS, mandibular IOS; maxillary IOS; and maxillary and mandibular CCS. The accuracy of the digital dental casts from the PCS and IPS methods was greater than that of IOS and CCS methods. Although accuracy of the digital dental cast from IOS was low, it satisfied the clinical requirements for fixed restorations in small units. The accuracy of the digital dental cast from CCS was poorest and could only be used for procedures with lower accuracy requirements.

“One day visit”: a predictable clinical procedure.

The present clinical case aims to introduce a cluster of techniques based on a digital and biological basis, to be used at intrasurgical time, in order to achieve a predictable clinical outcome. In fact, the possibility of merging data could allow a single-step procedure, introducing concepts like ‘one day visit’ with Socket shield (SS), implant and provisional crown, same-day delivery. This procedure is well accepted by the patient as reducing surgery sessions and prosthetic time. A CBCT and a digital impression were used for initial diagnosis, obtaining data about tooth anatomy, bone quality, and bundle bone extension. Surgical planning and relative stent, allowed a careful position of implant inter-radicularly to achieve best primary stability, required for an immediate load on the mandibular molar area. It was first performed an SS on molar #46, with a seagull wing configuration (i.e., maintaining a small septum area between vestibular roots laminae. The implant was positioned in the inter-radicular area using a safe surgical stent: IT, IT curve and the implant stability quotient (ISQ (>70) were measured establishing criteria for immediate loading. An intra surgical impression scan was taken using a T-Base system allowing the planning of an immediate digital provisional crown in 40 minutes. Meanwhile, the SS shoulder was reduced, root spaces were filled with bone chips mixed with Fibrin glue and covered with platelet-rich-fibrin (PRF) A large healing cap was inserted on waiting time. The provisional crown fit was excellent requiring minor adjustment, and was immediately positioned. Seven months later a digital crown copy on disilicate was inserted. SS proved to maintain marginal gingiva and bundle bone. A novel intrasurgical action allows the implant stability measurement and immediate digital impression, picking high-quality prosthetic data.(time 0 concept. Follow-up shows crown stability and maintenance of both soft and hard tissue volume over 3 years. This is a proof of principle clinical case. Hardware & Software technologies were used to improve the predictability of outcome and stability over time of soft and hard tissue. Several activities were done at intra-surgical time and allowed to achieve unique data for prosthetic planning. The SS typically used on an anterior maxillary area was here used on posterior region and it is a fundamental step on ‘single day visit’ approach. The technique is operator sensitive and may not be applicable in any single case. More studies and clinical confirmation are therefore required.

Interobserver Agreement Rates on Fibroblast Activation Protein Inhibitor-Directed Molecular Imaging and Therapy.

ObjectivesFibroblast activation protein (FAP) has emerged as a novel target for FAP inhibitor (FAPI)–directed molecular imaging and endoradiotherapy (ERT). We aimed to assess the interobserver agreement rates for interpretation of 68Ga-FAPI-4 PET/CT and decision for ERT.Patients and MethodsA random order of 68Ga-FAPI-4 PET/CTs from 49 oncology patients were independently interpreted by 4 blinded readers. Per scan, visual assessment was performed, including overall scan impression, number of organ/lymph node (LN) metastases, and number of affected organs/LN regions. Moreover, a maximum of 3 target lesions, defined as largest in size and/or most intense, per organ compartment were identified, which allowed for an additional quantitative interobserver assessment of LN and organ lesions. To investigate potential reference tissues, quantification also included unaffected liver parenchyma and blood pool. Readers also had to indicate whether FAPI-directed ERT should be considered (based on intensity of uptake and widespread disease). Interobserver agreement rates were evaluated using intraclass correlation coefficients (ICCs) and interpreted according to Cicchetti (with 0.4–0.59 indicating fair, and 0.6–0.74 good, agreement).ResultsOn a visual basis, the agreement rate for an overall scan impression was fair (ICC, 0.42; 95% confidence interval [CI], 0.27–0.57). The concordance rate for number of affected LN areas was also fair (ICC, 0.59; 95% CI, 0.45–0.72), whereas the number of LN metastases, number of affected organs, and number of organ metastases achieved good agreement rates (ICC, ≥0.63). In a quantitative analysis, concordance rates for LN were good (ICC, 0.70; 0.48–0.88), but only fair for organ lesions (ICC, 0.43; 0.26–0.60). In regards to background tissues, ICCs were good for unaffected liver parenchyma (0.68; 0.54–0.79) and fair for blood pool (0.43; 0.29–0.58). When readers should decide on ERT, concordance rates were also fair (ICC, 0.59; 95% CI, 0.46–0.73).ConclusionsFor FAPI-directed molecular imaging and therapy, a fair to good interobserver agreement rate was achieved, supporting the adoption of this radiotracer for clinical routine and multicenter trials.

Positional trueness of abutments by using a digital die-merging protocol compared with complete arch direct digital scans and conventional dental impressions

Statement of problemComplex prosthodontic treatments frequently require capturing an accurate impression of abutment teeth throughout the dental arch. Intraoral digital scanning has been reported to be accurate within single dental quadrants; however, the positional trueness of complete arch intraoral digital scans is not well understood. PurposeThe purpose of this in vitro study was to compare the positional trueness of a complete arch digital scan generated by digitally merging portions of a direct digital scan from an intraoral scanner (IOS) with a digitized polyvinyl siloxane (PVS) complete arch impression. Material and methodsA 3D printed reference cast was scanned with a desktop scanner, and reference standard tessellation language (STL) data sets were obtained. The reference cast was used to generate 4 nonmerged (NM) groups and 2 die-merged (DM) groups. In the NM groups (n=10), a direct digital scan of the reference cast was made with an IOS (NM-IOS), the PVS impression of the reference cast was digitized by using a cone beam computed tomography (CBCT) scanner (NM-PVS-CBCT) or a desktop scanner (NM-PVS-DESK), and the gypsum cast made from the PVS impression was digitized by using a desktop scanner (NM-STONE). In the DM groups (n=10), individual dies were cropped from the complete arch digital scan from the NM-IOS group and merged with the digital scans from the NM-PVS-DESK and NM-PVS-CBCT groups to generate the DM-PVS-DESK and DM-PVS-CBCT groups, respectively. Deviation was measured as the absolute value of the distance from a reference position on the reference cast. The Kruskal-Wallis and Dunn pairwise comparison tests were used to compare the difference in deviation between the groups (α=.05). ResultsThe NM-STONE and NM-PVS-DESK groups demonstrated the highest positional trueness, with global deviations of 19.6 and 17.7 μm, respectively, with no statistically significant difference (P>.999). However, both the NM-IOS and NM-PVS-CBCT groups differed significantly from the NM-STONE group (P<.001 and P=.003, respectively) and the NM-PVS-DESK group (P<.001 and P=.004, respectively). In the DM groups, the DM-PVS-CBCT group presented a higher deviation than the DM-PVS-DESK group. ConclusionsComplete arch digital scans of PVS impressions digitized with a desktop scanner exhibited less positional deviation than those digitized with a CBCT scanner or complete arch digital scans generated with an IOS. Complete arch digital scans generated with an IOS and CBCT scanner result in more deviations in the posterior regions, and their positional trueness may not be sufficient to construct an accurate digital scan. Generating a complete arch digital scan by digitally merging portions of a direct digital scan from an IOS with a digitized PVS complete arch impression is a suitable alternative to the contemporary workflow of digitizing a stone cast with a desktop scanner.

Accuracy comparison of intraoral versus laboratory scanners used in the contemporary dental practice

The aim of this in vitro study was to compare the quality of the data obtained by intraoral and by laboratory 3D scanners. An artificial jaw with an acrylic tooth prepared for a full metal ceramic crown was used as a master model of the prosthetic field. A reference model was created by scanning this field by a coordinate measuring machine (CCM). The acrylic master model was scanned by four scanners using three different methods and six digital models were obtained. They were divided in three groups - direct intraoral scanning (DIS), laboratory stone scanning (LSS) and laboratory conventional impression scanning (LCIS). Each scan was saved in the STL file format. Using a computer program, each of the six digital models were compared with the reference model created by the CCM and the results were displayed as color maps. The minimal acceptable deviation was defined as the deviation from the digital standard within the ± 0.02 mm limits. Thus, the LSS group exhibited an average of 13.5% points within these limits, followed by the LCIS group with 17.25%. The result for the DIS group was 44.75%.