Conventional Impression Research Articles

Evaluation of Removable Partial Denture Metal Frameworks Produced by Digital Methods—A Systematic Review

(1) Introduction: This review aimed to synthesize the significant literature addressing digital techniques for producing removable partial denture (RPD) metal frameworks, focusing on oral fit outcomes. (2) Material and Methods: A systematic review of the Web of Science and Pubmed databases was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. The selection was for original articles in English containing relevant data on RPD metal frameworks produced with digital techniques, including study characteristics, digital techniques, and fit assessment methods and outcomes. (3) Results: From the 967 search studies, 405 were duplications, and 521 were excluded after screening against set criteria. A manual search included 21 studies resulting in 62 papers for review. Extra-oral was more frequently used than intra-oral scanning. The computer-assisted design was the most applied digital technique. Additive manufacturing was preferred to milling for direct and indirect fabrication of frameworks. Fit assessments were based on qualitative measures, but quantitative evaluation showed acceptable clinical fit for RPDs made by digital protocols. (4) Conclusions: The combination of direct metal additive manufacturing with conventional impression was the most used protocol and included better qualitative and quantitative fit outcomes than the other digital protocols.

Perks of intraoral scanner to prosthodontist: A review

Intraoral scanners (IOS) have been boon to dentistry since 1980 as it has variety of applications such as impression making, use in prosthodontics and orthodontics appliances, retainers. Digital impressions have many benefits over conventional impressions. The chief advantage is that reduced patient discomfort. Many patient factors such as anxiety and gag reflex are reduced with the help of intra oral scanners. Whereas the drawbacks of optical impressions are inability to detect deep areas of teeth such as in bleeding. High cost and its maintenance.

Comparative evaluation of accuracy, time and patient acceptance between intraoral scanner and conventional alginate impression technique – An invivo study

Orthodontists use various dental records such as dental models or casts for diagnosis and treatment planning which includes making of dental impressions and study casts. Conventional alginate impressions are challenging for the patients with extreme gag reflex, irritation & discomfort. Recently 3D technology has led to development of scanning and digital models, but one major concern has been the accuracy. So this study was done to compare the accuracy, time and patient acceptance between intraoral scanner and conventional alginate impression technique. 15 patients were selected. Alginate impressions were made using zhermack neocolloid. The patients were subjected to digital scanning with Medit i500 intraoral scanner. Procedures were timed. After the impressions, each patient was asked to complete survey. Tooth width measurements were made using digital vernier caliper from stone models. In the second method digital images were measured using medit link software. Anterior and overall Bolton ratio was calculated to determine accuracy. Digital impressions are accurate and comparable to conventional impressions as tooth width measurements did not differ significantly. Conventional impression consumed more time. Patients preferred digital impressions.Intraoral scanners are accepted by patients and they have comparable accuracy and time efficient compared to conventional impression.

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

To evaluate accuracy, scanning time, and patient satisfaction of photogrammetry (PG) systems for recording the 3D position of dental implants. 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. 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 49μm and precision ranged from 5 to 65μm. For the iCam4D system, trueness ranged from 24 to 77μm and the precision value ranged from 2 to 203μm. 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.

Accuracy of Computerized Optical Impression Making in Fabrication of Removable Dentures for Partially Edentulous Jaws: An In Vivo Feasibility Study.

The use of computerized optical impression making (COIM) for the fabrication of removable dentures for partially edentulous jaws is a rising trend in dental prosthetics. However, the accuracy of this method compared with that of traditional impression-making techniques remains uncertain. We therefore decided to evaluate the accuracy of COIM in the context of partially edentulous jaws in an in vivo setting. Twelve partially edentulous patients with different Kennedy classes underwent both a conventional impression (CI) and a computerized optical impression (COI) procedure. The CI was then digitized and compared with the COI data using 3D analysis software. Four different comparison situations were assessed: Whole Jaw (WJ), Mucosa with Residual Teeth (M_RT), Isolated Mucosa (IM), and Isolated Abutment Teeth (AT). Statistical analyses were conducted to evaluate group differences by quantifying the deviation values between the CIs and COIs. The mean deviations between the COIs and CIs varied significantly across the different comparison situations, with mucosal areas showing higher deviations than dental hard tissue. However, no statistically significant difference was found between the maxilla and mandible. Although COIM offers a no-pressure impression method that captures surfaces without irritation, it was found to capture mucosa less accurately than dental hard tissue. This discrepancy can likely be attributed to software algorithms that automatically filter out mobile tissues. Clinically, these findings suggest that caution is required when using COIM for prosthetics involving mucosal tissues as deviations could compromise the fit and longevity of the prosthetic appliance. Further research is warranted to assess the clinical relevance of these deviations.

Conventional versus Digital Dental Impression Techniques: What Is the Future? An Umbrella Review

A prosthetic rehabilitation, whether supported by implants, teeth, or mucous membranes, must be functionally and aesthetically adequate, so it is essential that the oral structures are reproduced as accurately as possible. The purpose of this overview is to evaluate the accuracy, time of digital impressions, and patient preference compared to those of conventional high-precision in vivo impressions. This umbrella review was developed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement and was registered in the PROSPERO systematic review registry. The search method and study selection were based on the PEO (Population–Exposure–Outcome) model, a modified version of the PICO model. Systematic reviews regarding the dental impression technique made using an intraoral scanner versus the analog impression technique made with high-precision impression materials were searched electronically up to 1 February 2023 among articles published in English, through numerous registries and databases, such as PROSPERO e, Scopus, MEDLINE/ PubMed, BioMed Central, and Cochrane Library. The records screened totaled 2942, but only 23 systematic reviews were included in this umbrella review. The Assessing the Methodological Quality of Systematic Reviews (AMSTAR) 2 tool was used to evaluate the quality assessment of the systematic reviews included in this umbrella review. Accuracy, time, and patient preference for digital impressions were compared with those of high-precision conventional impressions. A total of 23 systematic reviews were included in this umbrella review. From the analysis of this umbrella review, the data on the accuracy between the two methods of taking the impression are conflicting, especially as regards full-arch rehabilitations. However, the digital impression seems to be preferred over the analog one as regards time and patient preference. However, there is limited high-quality evidence available for studying conventional and digital implant impressions. The results obtained are limited to the type of review performed, and the type of studies included was limited by the settings and study designs. Furthermore, another important limitation highlighted was that the digital scanners analyzed in the various studies are not the same, and the number of missing teeth or implants inserted is not the same. More in vivo clinical studies and RCTs are needed to increase the level of evidence for impression procedures.

A comparative evaluation of photogrammetry software programs and conventional impression techniques for the fabrication of nasal maxillofacial prostheses

The fabrication of facial prostheses is complicated and time-consuming because of the need for accurate impressions of the facial defects and surrounding tissues. Inaccuracies can arise from soft-tissue compression, involuntary patient movements, and insufficient support for the impression material. Various 3-dimensional (3D) imaging and scanning techniques, including photogrammetry, have been introduced, but their accuracy remains insufficiently evaluated. The purpose of this in vitro study was to evaluate and compare the accuracy of 3D digital casts generated by 4 photogrammetry software programs (Agisoft Metashape, 3DF Zephyr, Meshroom, and Polycam) and casts from 2 conventional impression materials (alginate and polyvinyl siloxane [PVS]) for the fabrication of nasal maxillofacial prostheses. A stone cast of a patient's nose was used as the basis for generating a reference digital 3D cast and another 54 test 3D casts. The reference cast was created by scanning the stone cast using a FARO Optor Lab 3D scanner. The 54 test 3D casts were generated and divided into 6 test groups as follows: Agisoft group: 9 3D casts generated using Agisoft Metashape, a commercial personal computer (PC) software program; 3DF Zephyr group: 9 3D casts generated using 3DF Zephyr, a commercial PC software program; Meshroom group: 9 3D casts generated using Meshroom, a free PC software program; Polycam group: 9 3D casts generated using the Polycam, a commercial Android cloud application; PVS group: 9 3D casts generated indirectly by 3D scanning a gypsum cast made from a polyvinyl siloxane (PVS) impression of the stone nose cast; and Alginate group: 9 3D casts generated indirectly by scanning a master cast made using alginate impressions of the stone nose cast. Deviation measurements of the produced specimens were analyzed using the Geomagic Control X software program, and statistical comparisons were performed employing the Kruskal-Wallis test (α=.05). The results showed that the 3DF Zephyr group had the smallest deviation measurements (median: 0.057mm ±0.012) among the 4 photogrammetry software programs, while the alginate impression group had the largest deviations (median: 0.151mm ±0.094) of the 2 conventional impression materials. Significant differences were observed among the 4 photogrammetry software programs and the 2 conventional impression materials (H=39.41, df=5, P<.001). The casts generated by Agisoft Metashape were significantly more accurate than those produced by Meshroom, Polycam or the conventional impression materials (P=.024, P=.045, P<.001, respectively). The casts produced by 3DF Zephyr were significantly more precise than those created by Meshroom and the conventional impression materials (P=.037, P<.001, respectively). No significant differences were observed between the Agisoft Metashape and 3DF Zephyr groups (P>.05). Photogrammetry software programs, specifically Agisoft Metashape and 3DF Zephyr, demonstrated better accuracy than conventional impression materials in creating nasal digital casts. Photogrammetry has the potential to improve workflow and reduce patient discomfort during the fabrication of maxillofacial prostheses. Further research is needed to validate these findings in clinical settings.

Device trueness in passivity and misfit of CAD-CAM frameworks: Conventional versus printed casts

Statement of problemObtaining a passive and well-adapted framework is challenging when intraoral scanning edentulous arches with multiple implants. The trueness of the printed casts is unclear. PurposeThe purpose of this clinical study was to evaluate the trueness of frameworks made from conventional and printed casts regarding clinical passivity and misfit. Material and methodsTen participants with complete mandibular fixed implant-supported interim prostheses retained by 4 implants were included. Each participant had a conventional impression and a digital scan made. The digital scan was made using an innovative device. Both conventional and digital casts were made, and the virtual images were used for milling the digital framework in cobalt chromium alloy. All frameworks were evaluated for passivity and marginal vertical misfit with the single screw test, with 4 attempts consisting of the tightened screw position, a test with all screws tightened, and an interspersed tightening test. The Kruskal-Wallis test was used to evaluate the trueness of the tested device for framework construction through the single screw test on vertical marginal misfit in the conventional and printed groups (α=.008). The Friedman test was used to assess the effect of test type (α=.05), and the Wilcoxon test was used to identify group-to-group differences (α=.017). ResultsThe absence of space between the framework and the abutments and interferences during its placement, as well as good stability, were observed clinically. In laboratory analysis, greater framework misfits were observed in the printed group compared with the conventional group when the single screw test was applied. Comparing the 3 tests used, the greatest misfits were observed when the framework was screwed onto the printed cast. ConclusionsThe innovative device tested for the intraoral scanning of multiple implants had clinically acceptable accuracy for the construction of passive and adapted frameworks. The conventional cast was more accurate than the printed cast, with lower misfit values, in all tests.

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 Intraoral Full-Arch Scan versus Conventional Preliminary Impression.

An accurate impression is vital during prosthodontic rehabilitation. Digital scanning has become an alternative to conventional impressions. This study compares conventional preliminary impression techniques with digital scanning, evaluating the efficiency, treatment comfort, and trueness. Impressions of 28 patients were taken using conventional and digital techniques. The efficiency of both impression techniques was evaluated by measuring the mean working time. A visual analog scale questionnaire (1-10) was used to appreciate the participants' perceptions of discomfort. Morphometric measurements, which were carried out to determine the differences between the casts, were made on the buccolingual cross sections of teeth 11 and 31 and the distolingual and mesiobuccal cusp tips of each first molar. The total treatment time was 75.5 min for conventional and 12 min for digital impressions. The patients scored a mean discomfort assessment of 6.66 for conventional and 9.03 for digital scanning. No significant differences existed between the examined areas (p < 0.05, Wilcoxon and Mann-Whitney tests) of the digital casts obtained by both techniques. The intraoral scan can be considered as an alternative to conventional preliminary impressions for performing study model analysis during orthodontic treatment planning. The digital impression is more comfortable and accepted by the patients than the conventional impression and has a shorter working time.

Comparative analysis of the trueness of linear measurements using direct and indirect scanning protocols compared to actual clinical measurements.

To assess the trueness of digital measurements using direct and indirect scanning approaches compared to the actual clinical measurements. The crown length, width, and width/length ratio were measured in 36 anterior maxillary teeth using three different methods. The first was clinically using a digital caliper, the second was by scanning the teeth using a digital scanner and the third was by making an impression of the teeth, constructing a stone cast in the lab, and scanning it to obtain digital measurements. Bland-Altman test and intraclass correlation were used to assess the data and make comparisons. Measurements taken using both approaches were highly reliable, with intraclass correlations ranging from 0.934 to 0.977 (p ≤ 0.000). Bland-Altman plot reflected a minimal mean difference between measurements especially in crown width measurements. Crown width/crown length measurement displayed the highest mean difference. Both direct and indirect optical surface scans showed similar high trueness in linear measurements of teeth. A higher discrepancy was detected in the crown width/length ratio. Digital dentistry is the new era in patient management. The use of conventional impression techniques and physical dental casts is associated with several disadvantages. Scanning dental casts to convert physical records into digital ones has multiple advantages. Optical surface scans (digital models) of the dentition are currently being more broadly used and advocated in the different dental disciplines including the construction of surgical guides for esthetic crown lengthening procedures. The trueness and reliability of linear measurements are of paramount importance to allow for proper fit and predictable outcomes. In this study, the trueness of these linear measurements obtained using direct and indirect methods was compared to the actual clinical measurements.

Effect of Ferrule Location on Fracture Resistance of Maxillary Premolars: An In Vitro Study.

The present study aimed to assess the effect of ferrule location on fracture resistance of maxillary premolars. A total of 72 extracted human maxillary premolars were selected and randomly assigned to six groups (n = 12 in each) considering ferrule location: circumferential ferrule (CF), without ferrule (WF), buccal ferrule (BF), lingual ferrule (LF), mesial ferrule (MF), and buccal-lingual ferrule (BLF). Cast posts were cemented into the prepared post spaces. Following conventional impression, Ni-Cr crowns were cemented to the specimens. After thermocycling (5,000 cycles, 5-55°C), the specimens were loaded at 45° in a universal testing machine until fracture. Data were analyzed with one-way ANOVA, Kolmogorov-Smirnov, and Tamhane tests. The maximum and minimum mean fracture resistance were related to the CF (1,143.84 N) and WF (514.89 N) groups, respectively, (P = 0.039). Fracture resistance in the BF (933.67 N) and BLF (874.01 N) groups was significantly higher than in the MF group (617.54 N) (P = 0.001). There was no significant difference between the MF, LF (722.89 N), and WF groups in terms of fracture resistance (P > 0.05). Teeth with CF showed maximum fracture resistance. The location of the ferrule effects on the fracture resistance of maxillary premolars and also the mode of failure.

Comparative evaluation of retention of record bases fabricated using conventional impression and modified digital scan for complete denture: An in vivo study

Background: In prosthetic dentistry, making an impression to replicate the oral health and tooth morphology is regarded as a crucial step. It is essential to ensure that the intraoral state is replicated as exactly as possible throughout this process, because any mistakes or inconsistencies could significantly impact the quality of the entire denture. In secondary impression, it’s crucial to capture the resilient oral mucosa (oral vestibule and soft palate) in order to acquire a satisfactory retention. As an alternative to conventional impression, digital scanning has been widely used in complete denture procedure. Although the digital scanning of edentulous ridges is feasible, scanning resilient oral tissues in complete denture still cannot be supported digitally. This study focuses on modifying the digital scan and comparison of retention of record bases fabricated from these modified digital scan to the record bases fabricated using conventional impression. Objectives: To compare the retention of record base prepared from conventional impression to the retention of record base from modified digital scan. Methodology: A total of 18 patients with edentulous maxillary arches will be recruited. A modified intraoral scan of the maxilla will be made on nine patients and on the remaining nine patients, a conventionally border moulded impression with a custom tray will be made. A record base with heat polymerized acrylic resin will be made on the definitive cast. Using the modified scanned image, the CAD-CAM bases will be milled. A dynamometer will be placed onto the record base; this will simulate the dislodging forces, thus clinically testing record base retention. Expected outcome: The record bases from modified digital scan will show equivalent or higher retention compared to record bases from conventional impression. Conclusions: By the end of the study, we will know whether resiliency of tissues can be recorded by modified digital scans.

Comparison of the accuracy between full-arch digital scans and scannable impression materials: an in vitro study.

In some clinical cases, full-arch impression could be difficult to take correctly with the digital way. Patients with high flow salivary rate or with difficulties in mouth opening can still benefit from a conventional impression with elastomer materials that can be directly or indirectly digitized. The aim of this study was to compare the accuracy and precision of two different intraoral scanners (IOSs) and an impression material with scannable properties, by means of three-dimensional analysis of a complete dental arch. An anatomical model of complete upper arch, modified with a Scan body placed in the retroincisive area, was used. It was firstly scanned by a desktop scanner to create a digital reference model. Then, 3 groups were created, each constituted by 5 samples. In the first group, 5 impressions were taken from the same master model with the scannable PVS material (Hydrorise Implant), 5 scans were taken using Trios4 (3Shape) and other 5 scans with iTero Element 5D (iTero). STL files obtained from IOSs, and scanned impressions were three-dimensionally superimposed on the STL file of the reference model using the Scan body geometry. The ANOVA Test (P<0.005) did not show any statistically significant difference between the accuracy and precision values of the groups. Each group shows clinically acceptable deviations from the reference model. Scannable polyvinylsiloxane impression materials are equally accurate and precise as the two IOSs tested in full-arch dentate impressions.

Clinical outcomes of implant-supported and tooth-supported fixed prostheses fabricated from digital versus analogue impression: a systematic review and meta-analysis.

To analyze the clinical outcomes of implant-supported prostheses and tooth-supported fixed prostheses, fabricated from digital and conventional impression. The literature search was carried out on two electronic databases (PubMed and Cochrane Library). Randomized controlled trials (RCT) published from January 2011 to September 2022 were included. The bias risk was evaluated using Cochrane Risk of Bias Tool 2.0. Further screening was done for meta-analysis according to modified Newcastle-Ottawa scoring criteria. Forest plot was generated using a statistical method of inverse variance of random effect with 95% confidence interval. A total of 8 randomized controlled trials were included for systematic review out of which four studies were based on tooth-supported fixed prosthesis and remaining four were based on implant-supported prosthesis. Further screening was conducted and three studies were eligible for meta-analysis. Tooth-supported fixed prosthesis fabricated from digital impression showed no significant difference in the marginal fit in any region measured, except for occlusal region where conventional impression showed more favorable marginal fit. Implant-supported prosthesis fabricated from digital impression showed survival rates ranging from 97.3 to 100% and there was no statistically significant difference in marginal bone loss (p = 0.14). Implant-supported prostheses fabricated from digital and conventional impressions show no significant differences in their clinical outcomes. Tooth-supported fixed prostheses fabricated from digital impression have shown favorable findings in terms of marginal fit. Despite that, there is still lack of clinical trials with larger sample size and longer follow-up periods. Future studies that fulfill these two criteria are deemed necessary.

Intraoral scanners in children: evaluation of the patient perception, reliability and reproducibility, and chairside time-A systematic review.

The aim of this systematic review is to evaluate the perception of the patient, the chairside time, and the reliability and/or reproducibility of intraoral scanners for full arch in pediatric patients. A data search was performed in four databases (Medline-Pubmed, Scopus, ProQuest and Web of Science) in accordance with the PRISMA 2020 statements. Studies were classified in three categories (patient perception, scanning or impression time and reliability and/or reproducibility). The resources, the data extraction and the quality assessment were carried out independently by two operators. The variables recorded were population characteristics, material and methods aspects and included country, study design and main conclusion. A quality assessment of the selected studies was performed with QUADAS-2 tool, and Kappa-Cohen Index was calculated to analyze examiner agreement. The initial search obtained 681 publications, and finally four studies matching inclusion criteria were selected. The distribution of the studies in the categories was three for the analysis of the patient's perception and scanning or impression time; and two items to assess the reliability and/or reproducibility of intraoral scans. All included studies have a repeated measures-transversal design. The sample size ranged between 26 and 59 children with a mean age. The intraoral scanners evaluated were Lava C.O.S, Cerec Omnicam, TRIOS Classic, TRIOS 3-Cart and TRIOS Ortho. The quality assessment of the studies using QUADAS-2 tool revealed a low risk of bias while evaluating patient perception, but an unclear risk of bias in the analysis of accuracy or chairside time. In relation to the applicability concerns, the patient selection was of high risk of bias. All studies agreed that the patient perception and comfort is better with intraoral scanners in comparison with the conventional method. The accuracy or reliability of the digital procedure is not clear, being clinically acceptable. In relation with the chairside time, it depends on the intraoral scanner, with contradictory data in the different analyzed studies. The use of intraoral scanners in children is a favorable option, finding a significantly higher patient perception and comfort with intraoral scanners compared to the conventional impression method. The evidence for reliability or reproducibility is not strong to date, however, the differences between the intraoral measurements and the digital models would be clinically acceptable.

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

What is the Impact of Impression Techniques on the Marginal Adaptation of Metal-Ceramic Crowns Fabricated by Direct Metal Laser-Sintering

Introduction: Studies on Marginal adaptation of restorations fabricated by direct metal laser-sintering DMLS are limited. This study to evaluate the effect of two impression techniques on the marginal adaptation of metal ceramic crowns fabricated by DMLS. Materials and Methods: Twenty intact maxillary premolars extracted for orthodontics reasons were received metal-ceramic crowns. After preparation according to the preparation guidelines for metal-ceramic crowns, the teeth were divided into two groups according to impression techniques (n=10): (1) group A IOS impression, (2) group B conventional impression. Group A specimens were scanned using IOS (I 500, MEDIT, Korea). Whereas, a custom-made tray used to make putty-wash impression to the specimens of group B. Group B casts were scanned using extraoral scanner (Identica T300, META, Korea). The metal coping designs were transferred to a direct metal laser-sintering (MYSINT100, SISMA, Italy), and they were made from Co-Cr blocks. The marginal adaptation was measured at labial, palatal, misael, and distal surfaces using microscope (Olympus, Japan). Student’s paired t test was used to assess the marginal adaptation between the groups. The cutoff value for statistical significance was set at α = 0.05. Results: A statistically significant differences in marginal adaptation was found between the impression techniques for all evaluations (labial, palatal, misael, and distal) (P&lt;0.05). The lowest values were recorded with IOS impression in all surfaces. Conclusions: the marginal adaptation values of IOS impression exhibited an acceptable marginal fit of less than 120 μm

Conventional and Digital Impressions for Fabrication of Complete Implant-Supported Bars: A Comparative In Vitro Study.

Obtaining accurate models and well-fitting prostheses during the fabrication of complete implant-supported prostheses has been a significant challenge. Conventional impression methods involve multiple clinical and laboratory steps that can lead to distortions, potentially resulting in inaccurate prostheses. In contrast, digital impressions may eliminate some of these steps, leading to better-fitting prostheses. Therefore, it is important to compare conventional and digital impressions for producing implant-supported prostheses. This study aimed to compare the quality of digital intraoral and conventional impressions by measuring the vertical misfit of implant-supported complete bars obtained using both types of techniques. Five digital impressions using an intraoral scanner and five impressions using elastomer were made in a four-implant master model. The plaster models produced with conventional impressions were scanned in a laboratory scanner to obtain virtual models. Screw-retained bars (n = five) were designed on the models and milled in zirconia. The bars fabricated using digital (DI) and conventional (CI) impressions were screwed to the master model, initially with one screw (DI1 and CI1) and later with four screws (DI4 and CI4), and were analyzed under a SEM to measure the misfit. ANOVA was used to compare the results (p < 0.05). There were no statistically significant differences in the misfit between the bars fabricated using digital and conventional impressions when screwed with one (DI1 = 94.45 µm vs. CI1 = 101.90 µm: F = 0.096; p = 0.761) or four screws (DI4 = 59.43 µm vs. CI4 = 75.62 µm: F = 2.655; p = 0.139). Further, there were no differences when the bars were compared within the same group screwed with one or four screws (DI1 = 94.45 µm vs. DI4 = 59.43 µm: F = 2.926; p = 0.123; CI1 = 101.90 µm vs. CI4 = 75.62 µm: F = 0.013; p = 0.907). It was concluded that both impression techniques produced bars with a satisfactory fit, regardless of whether they were screwed with one or four screws.

Accuracy of Conventional and Digital Impressions for Full-Arch Implant-Supported Prostheses: An In Vitro Study.

Both conventional and digital impressions aim to record the spatial position of implants in the dental arches. However, there is still a lack of data to justify the use of intraoral scanning over conventional impressions for full-arch implant-supported prostheses. The objective of the in vitro study was to compare the trueness and precision of conventional and digital impressions obtained with four intra-oral scanners: Trios 4 from 3Shape®, Primescan from Dentsply Sirona®, CS3600 from Carestream® and i500 from Medit®. This study focused on the impression of an edentulous maxilla in which five implants were placed for implant-supported complete prosthesis. The digital models were superimposed on a digital reference model using dimensional control and metrology software. Angular and distance deviations from the digital reference model were calculated to assess trueness. Dispersion of the values around their mean for each impression was also calculated for precision. The mean distance deviation in absolute value and the direction of the distance deviation were smaller for conventional impressions (p-value < 0.001). The I-500 had the best results regarding angular measurements, followed by Trios 4 and CS3600 (p < 0.001). The conventional and I-500 digital impressions showed the lowest dispersion of values around the mean (p-value < 0.001). Within the limitations of our study, our results revealed that the conventional impression was more accurate than the digital impression, but further clinical studies are needed to confirm these findings.