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Decision for precision! The first stage in creating an accurate, passively fitting prosthesis is to replicate the intraoral relationship of implants using impression methods. The technique and the impression material utilized are the key elements that influence the accuracy of the implant imprint. The goal of this study was to assess the accuracy of the described implant impression technique using various impression materials, as well as to look into the clinical aspects that influence implant impression accuracy. Two holes (4.3 mm × 10 mm) were drilled in a U-shaped study plastic model representing the partially edentulous maxilla, and the appropriate Nobel Biocare Replace select implants were implanted. Closed tray copings were placed for the relevant implants, and closed tray impressions were taken with several impression materials (PVS-1) Dentsply, medium-bodied, and 2) Regular setting-Zhermack Elite HD+). To assess passive fit accuracy, a jig trial and RVG IOPA were used. Stereomicroscopy was used to evaluate the precision of the implant and analog interface from two perspectives: buccal and lingual. On the buccal aspect, Group 1 had a mean value of 13703.29, whereas Group 2 had a mean value of 11395.58. On the lingual aspect, Group 1's mean value was 8415.61, whereas Group 2's was 9192.01. In the closed tray technique, no statistically significant differences between different imprint materials were found. There was no significant difference in the accuracy of closed tray implant impression techniques with different impression materials, according to the findings.

Decision for precision! The first stage in creating an accurate, passively fitting prosthesis is to replicate the intraoral relationship of implants using impression methods. The technique and the impression material utilized are the key elements that influence the accuracy of the implant imprint. The goal of this study was to assess the accuracy of the described implant impression technique using various impression materials, as well as to look into the clinical aspects that influence implant impression accuracy. Two holes (4.3 mm × 10 mm) were drilled in a U-shaped study plastic model representing the partially edentulous maxilla, and the appropriate Nobel Biocare Replace select implants were implanted. Closed tray copings were placed for the relevant implants, and closed tray impressions were taken with several impression materials (PVS-1) Dentsply, medium-bodied, and 2) Regular setting-Zhermack Elite HD+). To assess passive fit accuracy, a jig trial and RVG IOPA were used. Stereomicroscopy was used to evaluate the precision of the implant and analog interface from two perspectives: buccal and lingual. On the buccal aspect, Group 1 had a mean value of 13703.29, whereas Group 2 had a mean value of 11395.58. On the lingual aspect, Group 1's mean value was 8415.61, whereas Group 2's was 9192.01. In the closed tray technique, no statistically significant differences between different imprint materials were found. There was no significant difference in the accuracy of closed tray implant impression techniques with different impression materials, according to the findings. [ABSTRACT FROM AUTHOR]

Purpose: To compare the Encode impression protocol (Biomet 3i) with the conventional impression protocol in terms of treatment duration, clinical accuracy, and outcome up to the first postplacement review of singleimplant crowns. Materials and Methods: A total of 45 implants were included in this study. The implants were randomly allocated to the Encode group (23 implants) or the conventional group (22 implants). At the time of surgery, all implants received two-piece Encode healing abutments. The implants were restored 3 months after insertion. In the conventional protocol, open-tray implant-level impressions were taken and the implants were restored with prefabricated abutments and porcelain-fused-to-metal (PFM) crowns. For the implants in the Encode group, closed-tray impressions of the healing abutments were taken. The generated casts were sent to the Biomet 3i scanning/milling center for custom abutment manufacturing on which PFM crowns were fabricated. Treatment duration (laboratory and clinical), clinical accuracy of occlusal and proximal contacts, and outcome (esthetics, patient satisfaction, and crown contour) were evaluated with the aid of a series of questionnaires. Results: The Encode protocol required significantly less laboratory time (18 minutes) than the conventional protocol for adjustment of the abutments. The impression pour time, time for the laboratory to return the crown, time for crown insertion at the final appointment, and total clinical time for crown insertion did not differ significantly between the two protocols. Likewise, clinical accuracy, esthetics, and patient satisfaction were similar for the two protocols. Conclusion: The two protocols were clinically comparable. The Encode protocol is advantageous in reducing the laboratory time before crown fabrication. [ABSTRACT FROM AUTHOR]

Traditional techniques for fabricating interim, immediately loaded implant-supported fullarch prostheses are complex and time-consuming. The present study presents an efficient technique for fabricating interim prostheses with prefabricated multipurpose rigid connecting bars. This technique can minimise the misfit attributed to the polymerisation shrinkage of resin and expansion of the working cast, and simultaneously facilitate impression taking and occlusal records in one visit, thus reducing laboratory and chair time. Due to its ease of use and clinical efficiency, the present technique is considered particularly beneficial for immediate loading rehabilitation. [ABSTRACT FROM AUTHOR]

Prosthesis failures in cement-retained implant restorations can be managed by transforming the restorations into screw-retained prosthesis to meet the current implant treatment philosophies for large full-arch reconstructions. The challenges involved in this case report multiplied due to unavailability of components for older systems of implants and had to be managed with a framework which permits engagement of implant and abutment level connection simultaneously. The case report highlights the transition of failed cement-retained prosthesis to screw-retained prosthesis for predictable future retrievability and enhanced clinical performance.

The purpose of this study was to evaluate the accuracy of open tray dental implant impressions when the implants are placed with varying implant angulations and depths. Four partially edentulous models were fabricated using photopolymer resin, each having different angulation and depth of the implant analogs. A total of 40 open tray elastomeric impressions were made, which were poured in type IV die stone (n = 10). These casts were evaluated and compared for accurate reproduction of the spatial orientation of the implant analogs in the models using digitization in 3 dimensions. The results were analyzed using the independent T test. Statistically significant differences were observed when the casts were compared with their respective master models. These casts had the implant replicas placed deeper within the replicated soft tissue. Making accurate impressions in partially edentulous situations with dental implants placed with varying depth and angulation is critical and clinically demanding. There is a need for future in vivo research to identify methods and materials, exploring digital impression techniques as well, in order to make precise impressions. [ABSTRACT FROM AUTHOR]

Purpose: This is a cross‐sectional clinical study to evaluate crestal bone levels, mucosal margin position, probing depths, bleeding on probing, and plaque and bleeding indices of implants restored with an immediate impression workflow compared to implants restored with a delayed impression workflow. Materials and methods: Patients who had received a posterior single implant crown in the premolar and molar regions were identified and scheduled for a single‐visit study appointment. Outcome measurements included soft tissues peri‐implant indices, peri‐implant mucosal margin position, and crestal bone levels. Several systemic‐, local‐, and prosthesis‐related factors were recorded. Bitewing radiographs were used to assess crestal bone levels. Wilcoxon rank sum test was used to compare the medians of continuous measurements and Pearson chi‐square test (or Fisher's exact test) was used to compare the distributions of categorical variables between the two groups. Results: Twenty eight patients were included. Crestal bone levels, peri‐implant mucosal margin position and peri‐implant soft tissue parameters for the immediately impressed group were not statistically different from the delayed impressed group, except for probing depth for the immediately impressed buccal site, which was less than that of the delayed group. Mesial bone level for cement‐retained crowns was significantly more coronal than for screw‐retained ones. Conclusions: While an isolated statistical difference was found in probing depth, the current study suggests that there is no clinically significant difference between implants impressed with immediate and delayed implant workflows when considering crestal bone levels, peri‐implant mucosal margin position, and most peri‐implant indices. [ABSTRACT FROM AUTHOR]

Prosthesis failures in cement-retained implant restorations can be managed by transforming the restorations into screw-retained prosthesis to meet the current implant treatment philosophies for large full-arch reconstructions. The challenges involved in this case report multiplied due to unavailability of components for older systems of implants and had to be managed with a framework which permits engagement of implant and abutment level connection simultaneously. The case report highlights the transition of failed cement-retained prosthesis to screw-retained prosthesis for predictable future retrievability and enhanced clinical performance. [ABSTRACT FROM AUTHOR]

Purpose: Because there is a paucity of clear-cut evidence regarding which materials and techniques are most accurate for complete-arch, multiple-implant impressions, the current study sought to analyze the data and draw useful conclusions based on the evidence for application in clinical practice. Materials and Methods: Relevant studies published between 1990 and December 2012 were included in the review. The articles were located through PubMed and manually through reviewing references in the literature. Papers examining implant impression accuracy in completely edentulous arches (three or more implants) were included. Clinical case reports, technique articles, abstracts, and review papers were excluded. Results: One of the 34 studies selected for evaluation was clinical; the remaining 33 were in vitro investigations. Ten studies compared polyvinyl siloxane (PVS) and polyether (PE); eight found that these were statistically equal in terms of impression accuracy. The splint effect was examined by 24 studies; 10 failed to observe any differences between splinted and nonsplinted impressions, whereas 7 (> 25%) showed that the splinted technique was better than the nonsplinted technique. Thirteen studies investigated the differences between pickup and transfer impression techniques; six favored pickup over transfer, and five found insignificant differences between the techniques. The effect of nonparallel implants on edentulous multiple-implant impression accuracy was examined by only two studies. Significant differences in accuracy were observed for 15 degrees of angulation. Conclusion: Most of the evidence supports PVS and PE as the most accurate impression materials for edentulous multiple-implant situations, with no clear advantage of either. Conflicting evidence exists regarding the most accurate impression technique (splinted/nonsplinted, pickup/transfer), and no clear recommendation can be made. Inadequate research exists regarding several other factors that might affect edentulous implant impression accuracy. There is a lack of clinical research to support in vitro findings. [ABSTRACT FROM AUTHOR]

Purpose: To compare the accuracy of digital and conventional impression techniques for partially and completely edentulous patients and to determine the effect of different variables on the accuracy outcomes. Materials and Methods: An electronic and manual search was conducted to identify studies reporting on the accuracy of implant impressions. Pooled data were descriptively analyzed. Factors affecting the accuracy were identified, and their impact on accuracy outcomes was assessed. Results: The 76 studies that fulfilled the inclusion criteria featured 4 clinical studies and 72 in vitro studies. Studies were grouped according to edentulism; 41 reported on completely edentulous and 35 on partially edentulous patients. For completely edentulous patients, most in vitro studies and all three clinical studies demonstrated better accuracy with the splinted vs the nonsplinted technique (15 studies, splint; 1, nonsplint; 9, no difference). One clinical study and half of the in vitro studies reported better accuracy with the open-tray vs the closed-tray technique (10 studies, open-tray; 1, closed-tray; 10, no difference). For partially edentulous patients, one clinical study and most in vitro studies showed better accuracy with the splinted vs the nonsplinted technique (8 studies, splint; 2, nonsplint; 3, no difference). The majority of in vitro studies showed better accuracy with the open-tray vs the closed-tray technique (10 studies, open-tray; 1, closed-tray; 7, no difference), but the only clinical study reported no difference. Conclusion: The splinted impression technique is more accurate for both partially and completely edentulous patients. The open-tray technique is more accurate than the closed-tray for completely edentulous patients, but for partially edentulous patients there seems to be no difference. The impression material (polyether or polyvinylsiloxane) has no effect on the accuracy. The implant angulation affects the accuracy of implant impressions, while there are insufficient studies for the effect of implant connection type. Further accuracy studies are needed regarding digital implant impressions. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the three-dimensional (3D) accuracy of the Encode Impression System (EN) in transferring the locations of two implants from master models to test models and compared this to the direct impression (DI) technique. The effect of interimplant angulation on the 3D accuracy of both impression techniques was also evaluated. Materials and Methods: Seven sectional polymethyl methacrylate mandibular arch master models were fabricated with implants in the first premolar and first molar positions. The implants were placed parallel to each other or angulated mesiodistally or buccolingually with total divergent angles of 10, 20, or 30 degrees. Each master model was secured onto an aluminum block containing a gauge block, which defined the local coordinate references. Encode healing abutments were attached to the implants before impressions were made for the EN test models; pickup impression copings were attached for the DI test models. For the seven test groups of each impression technique, a total of 70 test models were fabricated (n = 5). The EN test models were sent to Biomet 3i for implant analog placement. The centroid of each implant or implant analog and the angular orientation of the long axis relative to the x- and y-axes were measured with a coordinate measuring machine. Statistical analyses were performed. Results: Impression technique had a significant effect on y distortion, global linear distortion, and absolute xz and yz angular distortions. Interimplant angulation had significant effects on x and y distortions. However, neither impression technique nor interimplant angulation had a significant effect on z distortion. Conclusions: Distortions were observed with both impression techniques. However, the results suggest that EN was less accurate than DI. [ABSTRACT FROM AUTHOR]

Purpose: To compare two different impression techniques for implants in totally edentulous patients. Materials and methods: A total of 38 patients had impressions taken both using plaster and splinted vinyl polysiloxane (splinted-VPS). Two casts per patient were generated and allocated as test (plaster) and control (splinted-VPS) cast groups according to a randomised cross-over design. One of the two casts from each patient was randomly selected as master cast according to a parallel-group design and used to fabricate the definitive prosthesis. Outcome measures were implant and prosthetic success rates, complications, marginal bone level (MBL) changes, patient satisfaction, chair time required to take the impressions, inter-implant discrepancy between the casts, sulcus bleeding index (SBI) and plaque score (PS). Results: In total, 76 impressions were taken in 38 patients. Two plaster impressions failed. Furthermore, 38 computer-aided design/computer-assisted manufacturing screw-retained complete-arch prostheses were fabricated onto the master cast (18 from plaster and 20 from splinted-VPS impressions) and the patients were followed up for 3 years after loading. No drop-out occurred and no implants or prostheses failed, accounting for a cumulative implant and prosthesis survival rate of 100% over the 3-year post-loading period. Plaster impressions yielded significantly greater patient satisfaction and shorter chair time. The discrepancy between the casts was 0.055 ± 0.067 mm (P = 0.931). Mixed model analysis revealed a significant main effect from both the implant number and the inter-implant distance, while no difference was found with regard to implant angulation. Five chip-off fractures of the porcelain veneer occurred in 5 of the 38 patients (3 in restorations fabricated onto the plaster cast group and 2 in the splinted-VPS cast group) with no effect from the type of impression on the prosthetic success rate (P = 0.331). However, all of the patients were functionally and aesthetically satisfied with their prostheses. Furthermore, mean MBL, SBI and PS showed no significant differences (P > 0.05) between the groups. Conclusions: The clinical outcome of plaster impressions for completely edentulous patients was found to be the same as that for splinted-VPS impressions. The intraoral pre-scan resin framework try-in can be avoided. Plaster impressions may be less time consuming and thus more comfortable for the patient, but sometimes may have to be repeated due to fractures. [ABSTRACT FROM AUTHOR]

The Encode protocol for restoring single dental implants simplifies the implant impression technique by using a specially coded transmucosal healing abutment. It allows recording of the implant position without the removal of the healing abutment. This prospective randomized controlled clinical trial compares the 2-year clinical performance of the Encode and the conventional protocols for restoring single implants. A total of 47 implants were randomly allocated for restoration by the Encode (24 implants) and the conventional (23 implants) protocols. The implants were reviewed after 2 years to evaluate patient satisfaction, esthetics, prosthesis cleansability, mucosal health, bleeding on probing (BoP), metallic discoloration, probing pocket depth (PPD), marginal bone level (MBL), and quality of the proximal and occlusal contacts. In addition, all forms of complications were reported. Twenty Encode and 17 conventional implants were reviewed. The 2 protocols were comparable in all variables. A consistent increase of open proximal contacts was detected for the 2 protocols. Two Encode (10.0%) and 4 conventional (21.1%) crowns had screw loosening that was predominantly associated with cross-pins. This had led to the failure of 2 conventional crowns. Three Encode (15.0%) and 2 conventional (11.8%) crowns displayed ceramic chipping. The Encode and the conventional crowns had survival rates of 100.0% and 89.5%, respectively. From the biologic, prosthetic, and esthetic perspectives, the Encode and the conventional protocols provided a comparable clinical outcome over a 2-year duration. [ABSTRACT FROM AUTHOR]

Purpose: To compare the accuracy of implant master casts fabricated using Robocast Technology (Biomet 3i) with that of master casts fabricated using traditional transfer (closed-tray) and pick-up (open-tray) techniques. Materials and Methods: A stereolithographic replica of a Kennedy Class I human mandible was fabricated for use as the master model. Implants were placed into both posterior quadrants (both second premolars and second molars) and set parallel (P) on one side and divergent (nonparallel, NP) on the opposite side. Impressions were made of the master model (patient replica model) with Encode Healing Abutments, open-tray, and closed-tray impression copings. Identical metallic spheres were placed onto each implant analog in the stone master casts, and the casts/spheres were scanned using a digital scanner. Measurements were made between the center points of the spheres and compared to the master model. Data were divided into P, NP, and individual sites, and the differences were analyzed statistically (α = .05). Results: Encode master casts were less accurate than the open-tray casts in NP sites. Encode master casts were less accurate than the open-tray and closed-tray casts in P sites. NP sites demonstrated less accuracy than P sites within the Encode group. Encode master casts were less accurate than the open- and closed-tray casts at the mandibular right second premolar site. The mandibular left second premolar was less accurate than the mandibular right second molar in the Encode group. Conclusions: Within the limitations of this lab-based study and analysis, the Encode technique resulted in master casts that were less accurate than master casts made from traditional open- and closed-tray impression techniques. Further research is necessary before specific clinical judgments can be made. [ABSTRACT FROM AUTHOR]

Purpose: The effect of different implant impression techniques on the accuracy of casts has been investigated mostly in vitro, and clinically relevant evidence is scarce. The purpose of this study was to investigate the effect of implant impression techniques-specifically, splinted versus nonsplinted-on the accuracy of fit of fixed implant prostheses in edentulous patients. Materials and Methods: This clinical study included 12 edentulous patients (13 edentulous arches). All patients had undergone computer-guided, prosthetically driven implant surgery. Splinted (with acrylic resin) and nonsplinted pickup implant impression techniques were used to generate two different casts. Intraoral verification jigs were made to fabricate a third index cast (prosthesis fabrication cast); these made up a control group. All patients were definitively rehabilitated with one-piece zirconia prostheses. The accuracy of fit of each prosthesis was evaluated indirectly by examining them clinically and radiographically while they were fit on the generated casts. Results: Of the 13 splinted casts, 12 presented with accurate clinical fit when the zirconia prosthesis was seated on its respective cast. Only 6 of the 13 nonsplinted casts showed accurate clinical fit. The zirconia prostheses fit accurately on all respective casts of the control group (prosthesis fabrication cast) as well as intraorally. The differences between the test groups and between the nonsplinted and control groups were statistically significant. No statistically significant differences were found between the splinted and control groups. Conclusion: There is clinical evidence that the splinted impression technique generates more accurate implant impressions and master casts than the nonsplinted technique for complete-arch, one-piece fixed prostheses. Int J Oral Maxillofac Implants 2011;26:1267-1272 [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this in vitro study was to evaluate the dimensional accuracy, trueness, and precision of vinyl siloxane ether (VSXE) and polyvinylsiloxane (PVS) impression materials using different impression techniques., Material and Methods: A three-dimensional (3D) printed mandibular model with implants and metal rods served as the reference model. Impressions were taken in custom trays, resulting in four groups: PVS-closed-tray, VSXE-closed-tray, PVS-open-tray, and VSXE-open-tray. The reference model and impressions were scanned and analyzed using 3D analysis software to assess the trueness and precision within each group., Results: There was significant difference in trueness between the groups, with PVS closed tray showing a higher deviation than VSXE-closed-tray and PVS-open-tray. VSXE-open-tray had the lowest deviation, which was statistically significant. In terms of precision, PVS-closed-tray showed the highest deviation, while no significant differences were found among the other groups., Conclusions: VSXE impression material with an open tray technique consistently demonstrated the highest levels of accuracy and precision. Conversely, PVS impression material with a closed tray technique yielded less favorable results., Clinical Relevance: Better understanding of trueness and precision of new impression materials with new impression techniques will increase their clinical effectiveness., (Copyright© 2024 Dennis Barber Ltd.)

Aim: This systematic review and meta‐analysis were conducted to assess and compare the accuracy of conventional and digital implant impressions. The review was registered on the PROSPERO register (registration number: CRD42016050730). Material and Methods: A systematic literature search was conducted adhering to PRISMA guidelines to identify studies on implant impressions published between 2012 and 2017. Experimental and clinical studies at all levels of evidence published in peer‐reviewed journals were included, excluding expert opinions. Data extraction was performed along defined parameters for studied specimens, digital and conventional impression specifications and outcome assessment. Results: Seventy‐nine studies were included for the systematic review, thereof 77 experimental studies, one RCT and one retrospective study. The study setting was in vitro for most of the included studies (75 studies) and in vivo for four studies. Accuracy of conventional impressions was examined in 59 studies, whereas digital impressions were examined in 11 studies. Nine studies compared the accuracy of conventional and digital implant impressions. Reported measurements for the accuracy include the following: (a) linear and angular deviations between reference models and test models fabricated with each impression technique; (b) three‐dimensional deviations between impression posts and scan bodies respectively; and (c) fit of implant‐supported frameworks, assessed by measuring marginal discrepancy along implant abutments.) Meta‐analysis was performed of 62 studies. The results of conventional and digital implant impressions exhibited high values for heterogeneity. Conclusions: The available data for accuracy of digital and conventional implant impressions have a low evidence level and do not include sufficient data on in vivo application to derive clinical recommendations. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The aim of this in vitro study was to compare the accuracy of printed implant casts from digital impressions with two intra‐oral scanners (IOS) to stone casts from conventional impressions. The hypothesis was that printed casts would be more accurate than stone casts from conventional impressions. Materials and methods: A mandibular stone cast with Kennedy class II edentulism was fabricated using two internal connection tissue‐level implants at 30 degrees to each other (Replace Select RP, Nobel Biocare) to serve as master. Digital impressions (n = 10) were made with the white light (WL) and Active Wavefront Sampling technology (AWST) IOS. The resultant standard tessellation language (STL) datasets were used to print implant casts through stereolithography (SLA) prototyping. The conventional casts (n = 10) were produced with splinted open tray impression technique and polyether material in type IV stone. The master cast and all groups were digitized with lab reference scanner. The test groups STL datasets were superimposed to master cast STL in inspection software (Geomagic control 2015) to calculate root‐mean‐square error. Results: The conventional, WL IOS and AWST IOS groups had mean values of 53.49 μm (SD 9.47), 108.09 μm (SD 9.59) and 120.39 μm (SD 5.91), respectively. The Shapiro–Wilk test showed no evidence of nonnormality (p = 0.131) and Levene's test showed no evidence of heterogeneity of variance (p = 0.518). The one‐way ANOVA demonstrated a statistically significant difference (p < 0.001). Tukey's honest significant difference (HSD) showed statistically significant differences between all groups: for the comparison of AWST IOS and WL IOS, the p‐value was 0.009, and the p‐values of the other post hoc tests were <0.001. Conclusion: Printed casts generated from digital impressions for partially edentulous posterior mandibular arches had inferior accuracy to conventional stone casts fabricated from splinted open tray impressions. The printed casts from WL IOS had better accuracy compared to AWST IOS. [ABSTRACT FROM AUTHOR]

Implant impression is the first and most important step in the fabrication of a fixed or removable dental prosthesis as accurate impressions are a prerequisite for an accurately fitting passive prosthesis. There are a number of variables that affect accuracy of implant impressions and it is important to control these factors in clinical practice. [ABSTRACT FROM AUTHOR]

Objectives To evaluate the adjustment of structures designed from a digital impression of implants obtained by cone-beam computerized tomography ( CBCT). Materials and methods Thirty implants were placed in five edentulous mandibles of fresh cadaver heads, six per mandible. Special scan bodies were screwed in the implants and a CBCT was taken. DICOM images were converted to STL and digitally processed to obtain a digital model of the implants. A Cr-Co structure was designed and milled for each mandible, and the adjustment was assessed as in a real clinical situation: passivity while screwing, radiographic fitting, optical fitting, and probing. Results Good adjustment was found in three of the structures, and only slight discrepancies were found in the other two. Conclusion Cone-beam computerized tomography might be a valid impression-taking method in full-mouth rehabilitations with implants. Further evaluations are needed with more implant and CBCT systems. The radiation dose might be considered when deciding to use this impression system. The types of patients appropriate for this treatment option should also be determined to fulfill the principles of the ALARA law. [ABSTRACT FROM AUTHOR]

Purpose The aim of this study was to assess the effect of connection type and impression technique on the accuracy of fit of implant-supported fixed complete-arch dental prostheses ( IFCDPs). Materials and Methods An edentulous mandibular cast with five implants was fabricated to serve as master cast (control) for both implant- and abutment-level baselines. A titanium one-piece framework for an IFCDP was milled at abutment level and used for accuracy of fit measurements. Polyether impressions were made using a splinted and non-splinted technique at the implant and abutment level leading to four test groups, n = 10 each. Hence, four groups of test casts were generated. The impression accuracy was evaluated indirectly by assessing the fit of the IFCDP framework on the generated casts of the test groups, clinically and radiographically. Additionally, the control and all test casts were digitized with a high-resolution reference scanner (IScan D103i, Imetric, Courgenay, Switzerland) and standard tessellation language datasets were generated and superimposed. Potential correlations between the clinical accuracy of fit data and the data from the digital scanning were investigated. To compare the accuracy of casts of the test groups versus the control at the implant and abutment level, Fisher's exact test was used. Results Of the 10 casts of test group I (implant-level splint), all 10 presented with accurate clinical fit when the framework was seated on its respective cast, while only five of 10 casts of test group II (implant-level non-splint) showed adequate fit. All casts of group III (abutment-level splint) presented with accurate fit, whereas nine of 10 of the casts of test group IV (abutment-level non-splint) were accurate. Significant 3D deviations ( P < 0.05) were found between group II and the control. No statistically significant differences were found between groups I, III, and IV compared with the control. Implant connection type (implant level vs. abutment level) and impression technique did affect the 3D accuracy of implant impressions only with the non-splint technique ( P < 0.05). Conclusion For one-piece IFCDPs, the implant-level splinted impression technique showed to be more accurate than the non-splinted approach, whereas at the abutment-level, no difference in the accuracy was found. [ABSTRACT FROM AUTHOR]

Purpose To compare the accuracy of digital and conventional impression techniques for completely edentulous patients and to determine the effect of different variables on the accuracy outcomes. Materials and methods A stone cast of an edentulous mandible with five implants was fabricated to serve as master cast (control) for both implant- and abutment-level impressions. Digital impressions ( n = 10) were taken with an intraoral optical scanner ( TRIOS, 3shape, Denmark) after connecting polymer scan bodies. For the conventional polyether impressions of the master cast, a splinted and a non-splinted technique were used for implant-level and abutment-level impressions (4 cast groups, n = 10 each). Master casts and conventional impression casts were digitized with an extraoral high-resolution scanner ( IScan D103i, Imetric, Courgenay, Switzerland) to obtain digital volumes. Standard tessellation language ( STL) datasets from the five groups of digital and conventional impressions were superimposed with the STL dataset from the master cast to assess the 3D (global) deviations. To compare the master cast with digital and conventional impressions at the implant level, analysis of variance ( ANOVA) and Scheffe's post hoc test was used, while Wilcoxon's rank-sum test was used for testing the difference between abutment-level conventional impressions. Results Significant 3D deviations ( P < 0.001) were found between Group II (non-splinted, implant level) and control. No significant differences were found between Groups I (splinted, implant level), III (digital, implant level), IV (splinted, abutment level), and V (non-splinted, abutment level) compared with the control. Implant angulation up to 15° did not affect the 3D accuracy of implant impressions ( P > 0.001). Conclusion Digital implant impressions are as accurate as conventional implant impressions. The splinted, implant-level impression technique is more accurate than the non-splinted one for completely edentulous patients, whereas there was no difference in the accuracy at the abutment level. The implant angulation up to 15° did not affect the accuracy of implant impressions. [ABSTRACT FROM AUTHOR]

Background: The accuracy of implant casts generated with various impression techniques was mainly investigated in vitro resulting in limited clinical data. Purpose: (1) To compare the three-dimensional (3-D) accuracy of splinted and non-splinted impression techniques to the control casts (verification jigs) that had been used for actual patient treatment; and (2) to determine the maximum level of clinically undetectable misfit. The null hypothesis was that there would be no significant difference in the accuracy of casts generated with different impression techniques. Materials and methods: The implant casts used for the prosthetic rehabilitation of 12 edentulous jaws with CAD/CAM zirconia, implant-fixed complete dental prosthesis (IFCDP) were included in this study. Intraoral acrylic jigs were used to fabricate index casts. Splinted and non-splinted, open-tray techniques were used to generate two casts. Optical scanning acquisition of the x-coordinates, y-coordinates and z-coordinates of the implant positions for each individual cast was performed. The 'best fit' algorithm was used with computer software to superimpose the scanning datasets. Group I ( n=12) included casts from the splinted impression technique vs. acrylic jig casts, and group II ( n=12) included casts from non-splinted technique vs. jig casts. Results: The paired t-test and Wilcoxon's signed ranks test were used to compare the 3-D discrepancies within and between groups I (splinted vs. jig) and II (non-splinted vs. jig), respectively. Significant difference was found at the x-axis, y-axis and 3-D between groups I and II ( P<0.05), but not in the vertical z-axis ( P>0.05). Within subject, global 3-D discrepancies between groups I and II were significantly different ( P<0.05), corroborated by in vivo observations of clinical fit. Implant position in the arch affected the 3-D accuracy of casts for both anterior and posterior implants ( P<0.05). Conclusion: The splinted technique generated more accurate master casts than the non-splinted technique for one-piece IFCDPs in edentulous jaws and the null hypothesis was rejected. These clinical implications demonstrate improved accuracy of splinted impression techniques compared with the non-splinted technique. For the external connection, the implant system used in this study, a 3-D misfit ranging from 59 to 72 μm, may be considered the maximum discrepancy resulting in an acceptable clinical fit with one-piece IFCDPs. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim: The performance of three elastomeric materials for the open monophase implant impressions technique was tested under the following clinical conditions: polyether (IM) and vinylsiloxanether without (ID) and with additional simultaneous splinting of the implant impression copings with a higher shore hardness A-silicone (IDF). Materials and Methods: The three test groups, IM, ID, and IDF, were randomly allocated 10 test subjects with three to five implants each. The impressions were analyzed regarding the subjective clinical assessments with 11-point rating scales by the dentist, the patient, and the dental technician, as well as to the comparison of these assessments with the objectified clinical fit of the manufactured crowns based on standard clinical evaluation criteria. The three groups were statistically analyzed on the basis of the hypothesis of non-inferiority of ID versus IM and IDF versus IM (alpha < 0.05). Results: The results of the study showed the objective clinical fit of the dental prostheses made using ID being comparable to the results obtained with IM. Compared with ID and IM, the precision of fit attained with IDF was reduced, although the subjective dentist assessments of IDF were in parts significantly better than those of IM and ID ( p = .015). A statistically significant superiority of ID in comparison with IM could be determined with regard to the subjective ratings of the taste by the test subject ( p < .01), of the handling ( p < .001) and of the precision details of impression ( p = .012) by the dentist, and of removing the plaster model from the mold by the dental technician ( p = .017). Conclusions: The overall results of the vinylsiloxanether material in terms of the patients', dentists', and dental technicians' assessments proved to be equivalent or superior to those of the polyether material. The IDF technique cannot be recommended for this application. [ABSTRACT FROM AUTHOR]

Traditional techniques for fabricating interim, immediately loaded implant-supported full-arch prostheses are complex and time-consuming. The present study presents an efficient technique for fabricating interim prostheses with prefabricated multipurpose rigid connecting bars. This technique can minimise the misfit attributed to the polymerisation shrinkage of resin and expansion of the working cast, and simultaneously facilitate impression taking and occlusal records in one visit, thus reducing laboratory and chair time. Due to its ease of use and clinical efficiency, the present technique is considered particularly beneficial for immediate loading rehabilitation.

Aim: To analyze the impact of implant angulation and implant number on the dimensional accuracy of definitive casts., Materials and Methods: Seven definitive casts with implant analogs placed in a triangular pattern were made from dental stone. The groups were as follows: group 1 (control group) all implant analogs perpendicular to the plane of the cast; the center implant analog (implant 2) being at 90° to the plane of the cast in all groups and implant analogs number 1 and 3 arranged in 5°, 10°, or 15° divergence from or convergence to the center implant (implant number 2). Three open-tray impressions of definitive casts were made in each group. Impressions were poured in type IV dental stone. Coordinates in the three planes were measured at the implant analog top surface and the base of the cast using a fine tip measuring stylus. The data were aligned and the angular differences between implant analog vectors from definitive and duplicate casts were calculated in degrees., Results: The impact of implant number on the dimensional accuracy of definitive casts was significant whereas for implant angulation it was nonsignificant. The correlation of angulation and the number of the implant did not show an interpretable pattern. The precision of duplicate casts (compared to definitive casts) is not affected by the combined interaction of implant number and implant angulation., Conclusion: The close proximity of implant angulation toward a right-angled direction results in higher precision of implant. In the impression, there is direct picking from the impression copings which decreases the discrepancies in implant angulation on impression and master cast. The interaction of implant angulation and the number shows a noninterpretable pattern., Clinical Significance: Dimensionally accurate implant impressions can be made by using an open tray technique for three implants angled up to 15°.