Passive Fit Research Articles

Passive fit and time efficiency for prefabricated versus conventionally constructed cobalt chromium CAD\\CAM 3-unit implant supported frameworks in free end saddle models: a pilot invitro study

BackgroundThe passive fit of 3-unit implant supported prefabricated metal screw-retained prosthesis before implant placement might be difficult. Hence, we aim to evaluate the passive fit and time efficiency of CAD/CAM 3-unit implant supported fixed prostheses that were constructed based on virtual versus those based on actual implant positions in Kennedy Class I models.MethodsA sample of 5 Kennedy class I models with thin wiry ridges were restored by 20 frameworks bilaterally, 10 based on actual (group A) and 10 based on virtual (group V) implant positions. The models were imaged using cone beam computed tomography and scanned using an intraoral scanner. The STL (Standard Tessellation Language files) and the DICOM (Digital Imaging and Communications in Medicine) files were registered on a 3D planning software. A CAD/CAM surgical guide was planned, resin printed and used for installing 6 implants bilaterally. In group V, the framework was designed based on the virtual scan bodies and virtual multi-unit abutments, while in group A intra-oral scanning of the model after attaching the scan bodies was necessary. Frameworks of both groups were milled and tested for passive fit using 8 clinical tests. McNemar and Wilcoxon signed rank tests were used to study the effect of the group on passive fit and time efficiency, respectively. The significance level was set at P ≤ 0.05.ResultsNo statistically significant difference was found between group V and group A frameworks regarding passive fit (p-value = 1, OR = 0.5) and time efficiency (P = 0.179, Effect size = 0.948).ConclusionWithin the limitations of this study, it can be concluded that in free end saddle cases, prefabricated CAD\\CAM 3-unit implant-supported cobalt chromium screw retained prostheses can achieve an adequate passive fit. However, their fit might be negatively affected in thin ridges and they might require some adjustments.

Calibrated intraoral scan protocol (CISP) for full-arch implant impressions: An in vitro comparison to conventional impression, intraoral scan, and intraoral scan with scan-aid.

To assess a newly developed intraoral scan protocol in enhancing the accuracy of complete-arch implant impressions. Four impression approaches were applied to the same maxillary edentulous model with 6 implants: (1) intraoral scan (IOS), (2) intraoral scan with scan aid (IOS-SA), (3) calibrated intraoral scan protocol (CISP), and (4) conventional splinted open-tray impression (CONV). Each approach was repeated 10 times, and a direct scan of the model with a desktop scanner was used as a reference model. The alignment of scans and the reference model was conducted by two methods: (a) aligning all scan bodies to evaluate the overall fit, and (b) aligning the first and second scan bodies to simulate the Sheffield fit test for passive fitting of multiple implant-supported prostheses. Linear deviations from the reference model (trueness) and within each group (precision) were analyzed using Python scripts. When aligned by all scan bodies, the CISP group exhibited comparable mean trueness (38.33 μm) and precision (45.97 μm) to the CONV group (44.30 and 47.92 μm respectively), both of which significantly outperformed the IOS group (86.82 and 83.17 μm, respectively). Furthermore, in the virtual Sheffield fit test, the CISP group achieved the highest levels of mean trueness at the end span (121.7 μm), making a linear deviation reduction of 36.7%, 60%, and 41.4% when compared to the CONV, the IOS, and the IOS-SA groups, respectively. Moreover, the CISP group (104.3 μm) displayed a remarkable 65, 182, and 86 μm advantage in precision over the CONV, IOS, and IOS-SA groups, respectively. CISP demonstrated comparable accuracy to the gold standard, the conventional splinted open-tray impression. Furthermore, it excelledin the virtual passive fitting test.

A New Full Digital Workflow for Fixed Prosthetic Rehabilitation of Full-Arch Edentulism Using the All-on-4 Concept.

(1) Background: Recent digital workflows are being developed for full-arch rehabilitations supported by implants with immediate function. The purpose of this case series is to describe a new digital workflow for the All-on-4 concept. (2) Methods: The patients were rehabilitated using the All-on-4 concept with a digital workflow including computerized tomography scanning, intra-oral scanning, and CAD-CAM production of the temporary prosthesis, with the 3D printing of stackable guides (base guide, implant guide, and prosthetic guide). The passive fit of the prostheses and the time to perform the rehabilitations were evaluated. (3) Results: The digital workflow allowed for predictable bone reduction, the insertion of implants with immediate function, and the connection of an implant-supported prosthesis with immediate loading. The time registered to perform the full-arch rehabilitations (implant insertion, abutment connection, prosthesis connection) was below 2 hours and 30 min. No passive fit issues were noted. (4) Conclusions: within the limitation of this case series, the digital workflow applied to the All-on-4 concept using stackable base-, implant-, and prosthetic guides constitutes a potential alternative with decreased time for the procedure without prejudice of the outcome.

Effect of different fabrication workflows on the passive fit of screw-retained bar splinting two interforaminal implants: a parallel blinded randomised clinical trial

BackgroundTo clinically compare the effect of the conventional and the digital workflows on the passive fit of a screw retained bar splinting two inter-foraminal implants.MethodsThe current study was designed to be a parallel triple blinded randomised clinical trial. Thirty six completely edentulous patients were selected and simply randomized into two groups; conventional group (CG) and digital group (DG). The participants, investigator and outcome assessor were blinded. In the group (CG), the bar was constructed following a conventional workflow in which an open top splinted impression and a lost wax casting technology were used. However, in group (DG), a digital workflow including a digital impression and a digital bar milling technology was adopted. Passive fit of each bar was then evaluated clinically by applying the screw resistance test using the “flag” technique in the passive and non passive situations. The screw resistance test parameter was also calculated. Unpaired t-test was used for intergroup comparison. P-value < 0.05 was the statistical significance level. The study protocol was reviewed by the Research Ethics Committee in the author’s university (Rec IM051811). Registration of the clinical trial was made on clinical trials.gov ID NCT05770011. An informed consent was obtained from all participants.ResultsNon statistically significant difference was denoted between both groups in all situations. In the passive situation, the mean ± standard deviation values were 1789.8° ± 20.7 and1786.1° ± 30.7 for the groups (CG) and (DG) respectively. In the non passive situation, they were 1572.8° ± 54.2 and 1609.2° ± 96.9. Regarding the screw resistance test parameter, they were 217° ± 55.3 and 176° ± 98.8.ConclusionConventional and digital fabrication workflows had clinically comparable effect on the passive fit of screw retained bar attachments supported by two dental implants.

Novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit

ObjectivesThis article presents a novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit for implant-supported fixed complete dental prostheses (IFCDPs). Material and MethodsThe novel system presents a 3-unit toolset comprising intraoral scan bodies (ISBs), lateral pillar attachments (LPAs) and occlusal pillar attachments (OPAs). A 2-stage single visit workflow by an intraoral scanner (Trios 5) was introduced. The first stage “Screw-Scan-Done” was used to describe complete-arch intraoral implant scanning using LPAs. The second stage “Screw-Occlude-Done” involved virtual occlusal recording using OPAs. Two patients with one single edentulous arch were selected for this study. In the first patient, 6 bone level implants (Bone Level Tapered, Straumann) were placed in the edentulous maxilla at positions 12, 14, 16, 22, 24 and 26. In the second patient, 4 bone level implants (NobelActive CC, Nobel Biocare) were placed in the edentulous mandible at positions 32, 35, 42 and 45. A CAD-CAM procedure was initiated with the acquired IOS data to fabricate an interim IFCDP at the same day. Periapical radiographs were obtained of the implant-prosthetic connection of the definitive IFCDPs to verify the passive fit. Metrology software (Geomagic Qualify, 3D Systems – Matlab, Mathworks) was used to assess the implant analogs position in the 3D-printed casts used for fabricating the definitive IFCDPs. A quantitative occlusal relationship analysis was performed with IOS. ResultsRadiographic examination revealed no gaps at implant-prosthetic connection of the definitive IFCDPs. The 3D-printed casts showed an overall average distance deviation within the clinically acceptable range of errors of 150 µm. Quantitative occlusal relationship analysis with IOS showed well-distributed contacts. ConclusionWithin the limitations of this study, the following conclusions can be drawn:(1) A 3-unit toolset with ISBs, LPAs and OPAs allows to register the implant position and maxillomandibular relationship in one single visit;(2) the 2-stage clinical workflow with the CAPS system facilitates the IOS data acquisition for fabrication of an interim IFCDP at the same day;(3) a passive fit was demonstrated for the interim and the definitive IFCDPs. Clinical significanceThe CAPS system can help clinicians to register the implant position and the maxillomandibular relationship in one single visit for the fabrication of an IFCDP.

An in vitro study using confocal laser scanning microscopy to evaluate the marginal misfits of different implant-supported frameworks.

This study aimed to develop and evaluate a simple, non-destructive method for assessing the misfit and passivity of implant-retained prostheses frameworks. To simulate the rehabilitation of a mandible posterior partially edentulous area using 3-unit screw-retained frameworks supported by two implants were fabricated and divided into the following five groups (n = 10 in each group): OP = one-piece framework cast in Co-Cr with the conventional method (control-group); Co-Cr frameworks sectioned and welded by laser (=LAS) or tungsten inert gas (=TIG); Co-Cr CAD-CAM = milled Co-Cr framework; Zir CAD-CAM = milled zirconia framework. The horizontal |X| and vertical |Y| misfits were measured using confocal laser scanning microscopy with one or both screws tightened. Data were analyzed by a two-way ANOVA with repeated measures and Bonferroni correction (α = 0.05). The greatest |X| misfit was observed in the OP group with both screws tightened (290µm) and one screw tightened (388 and 340µm). The conventional casting groups sectioned and welded by laser or TIG had lower mean values (235.35µm, both screws tightened; and 275µm, one screw tightened) than the OP framework. However, these values still exceeded those of the milled Co-Cr and zirconia frameworks (190 and 216µm with both screws tightened). Across all reading conditions, every framework subjected to testing consistently maintained vertical |Y| misfit levels below the threshold of 53µm; however, the milled frameworks exhibited higher vertical misfits than the frameworks obtained by the conventional cast method. The frameworks, whether cast and sectioned with laser welding or milled from Co-Cr, exhibit improved marginal misfit and enhanced passive fit when compared to other fabrication methods. Additionally, the use of confocal laser scanning microscopy is highly effective for passivity and misfit analysis.

Implementation of triple-scan protocol to evaluate the fit of complete-arch implant-supported fixed prostheses.

Passive fit is essential for multiple-unit implant-supported prostheses. Conventional methods to assess the passivity of complete-arch implant-supported prostheses do not allow 3-dimensional (3D) visualization and quantification of misfit. This report describes the marginal and internal fit evaluation of a complete-arch implant-supported prosthesis by using the triple-scan protocol involving a scanner and a 3D analysis freeware. This technique allows researchers, clinicians, or dental technicians to detect and quantify 3D prosthetic misfit, which may facilitate the preparation for dental appointments and objective measurement of misfit for research studies.

Customized Subperiosteal Implants for the Rehabilitation of Atrophic Jaws: A Consensus Report and Literature Review.

(1) Background: The aim was to perform a literature review on customized subperiosteal implants (CSIs) and provide clinical guidelines based on the results of an expert consensus meeting held in 2023. (2) Methods: A literature search was performed in Pubmed (MEDLINE) in July 2023, including case series and cohort studies with a minimum follow-up of 6 months that analyzed totally or partially edentulous patients treated with CSIs. Previously, an expert consensus meeting had been held in May 2023 to establish the most relevant clinical guidelines. (3) Results: Six papers (four case series and two retrospective cohort studies) were finally included in the review. Biological and mechanical complication rates ranged from 5.7% to 43.8% and from 6.3% to 20%, respectively. Thorough digital planning to ensure the passive fit of the CSI is mandatory to avoid implant failure. (4) Conclusions: CSIs are a promising treatment option for rehabilitating edentulous patients with atrophic jaws; they seem to have an excellent short-term survival rate, a low incidence of major complications, and less morbidity in comparison with complex bone grafting procedures. As the available data on the use of CSIs are very scarce, it is not possible to establish clinical recommendations based on scientific evidence.

Repositioning accuracy of the implant- and abutment-level prosthetic components used in conventional and digital workflows

ObjectivesTo evaluate the repositioning accuracy of the implant- and abutment-level impression components (impression abutments and implant scan bodies) and implant abutments (with and without anti-rotational hex index); also, to estimate the tightening torque influence on the positional stability of abutments. MethodsSeven types of prosthetic components (n = 7) [impression pick-up copings (PC), implant scan bodies (ISB), non‑hex and hex titanium base implant abutments (TB H and TB NH), multi-unit impression copings (MU PC), multi-unit implant scan bodies (MU ISB), and multi-unit caps (MU C) (Medentika GmbH)] were tested. For repositioning accuracy tests a coordinate measuring machine (CMM) was used. During assembly 15 Ncm torque for all components was applied. After measurement, only hex and non‑hex abutments were torqued to 25 Ncm and their coordinates were again recorded to assess torque influence. The procedure was repeated 7 times for each component. Linear and 3D deviations, angulation to the vertical axis, and axial rotation were calculated. The Kruskal-Wallis test was used to compare the measurements between the groups. A post-hoc test (Mann–Whitney U test) was used for pairwise comparison to determine the influence of the torque (α=0.05). ResultsImplant- and abutment-level components used for digital scans showed different positional discrepancies compared to ones used for conventional impressions and ranged from 10 to 37 µm. Hex abutments demonstrated statistically significantly lower 3D deviations (4.4 ± 7.1 µm) compared to non‑hex abutments (8.7 ± 6.1 µm). Torque influence was significantly lower for hex abutments than for non‑hex abutments. ConclusionsRepositioning inaccuracies were found in all implant- and abutment-level impression components (impression abutments and implant scan bodies) and all abutments (with and without anti-rotational hex index) tested. Final tightening of the components could cause further positional discrepancies. Clinical significanceThe misfit of the prosthetic components used in conventional and digital workflows stays in the clinically acceptable range. Even when multiple connections and disconnections on the track of the laboratory preparation is needed, it should not have a negative influence for single teeth reconstructions. However, in the complex cases with multiple implants, repetitive repositioning of the prosthetic components may lead to the accumulation of vertical, horizontal and rotational errors leading to the clinical problems with the passive fit of the final framework.

Prosthetic Requirements for Full Arch Implant-Supported Fixed Prostheses: A Review

The objective of this work is to review the prosthetic particularities of complete implant-supported rehabilitation. Indeed, conical internal connection abutments are the reference abutments for totally edentulous patients. They allow the masticatory forces to be disturbed and reduce the micro-movements generated at the interfaces with the implants. An accurate impression provides a passive fit that is essential for successful treatment. The choice of the direct open pick-up technique is specific to totally edentulous patients. The splinting connection of the transfers provides a higher degree of precision, particularly if the implants have divergent axes. It is recommended to design the complete arch bridge in segments of three or four elements to ensure the passivity of the framework. At the anterior level, it is essential that the implant axis be compatible with the prosthetic axis to obtain the appropriate emergence profile. The main objective is to obtain a passive adaptation of each abutment on each corresponding implant.

Effect of primary versus secondary splinting impression techniques on the passive fit of screw-retained implant prosthesis: a randomized clinical trial

BackgroundThe utilization of splinting techniques for impression copings is commonly advised for complex implant-supported prostheses, as it can enhance the fit of these prostheses. However, there is limited understanding regarding the impact of the secondary splinting of implant analogues, on the passive fit of the prostheses. Limited data are available on the secondary splinting of implant analogues before pouring the impression and its comparison with the primary technique of intraoral splinting of impression copings prior to impression making.ObjectivesThis study's objective was to determine the impact of the primary versus secondary impression splinting techniques using resin on the passive fit of screw-retained prosthesis.Material and methodsThis randomized clinical trial (RCT) involved two parallel groups consisting of 14 completely edentulous patients, with seven patients in each group. Each patient received a total of eight implants, four implants per arch, resulting in a total of 28 screw-retained prostheses. Two different impression splinting techniques were employed. Group (1) utilized the primary splinting technique, where the impression copings were splinted before taking the impression. In contrast, Group (2) utilized the secondary splinting technique, where the implant analogues were splinted before pouring the impression material. To evaluate the passivity of the screw-retained prostheses in both groups, a single-screw test (one-screw test) was used. Additionally, supplementary methods, including the screw resistance test, were employed.ResultsThe findings of this RCT revealed higher passivity scores for secondary splinting impression pouring technique with a statistically significant difference (P = 0.082). There was a 2.2-fold greater frequency of non-passivity in the primary splinted method. In group (2), the likelihood of non-passivity was four times higher for upper arches prostheses, while there was no significant difference (P = 0.5) observed in both groups for lower arches prostheses.ConclusionsThe study found that using the secondary splinting impression pouring technique resulted in greater passivity of the implant prostheses compared to the primary splinting impression technique.

Digital Workflow in Full Mouth Rehabilitation with Immediate Loading, Intraoral Welding and 3D-Printed Reconstructions in a Periodontal Patient: A Case Report

Background: Complex implant reconstructions in patients with residual dentition due to periodontitis is a challenging task in many aspects. Methods: This study shows a full digital workflow combining 3D printing, guided implant placement, intraoral scanning and welding with immediate loading and digital smile design. An analog impression was taken to validate the passive fit of final restorations. The whole treatment plan was divided into three stages. The first stage included an intraoral scan of baseline dentition, and then the extraction of all teeth was performed, implanting four temporary implants and providing the patient with removable temporary prosthesis. The second stage was to scan the removable temporaries, implanting 10 implants and multi-unit abutments (MUA), and create a rigid construction via the intraoral welding of titanium bar and by fixing it to the 3D-printed temporary reconstructions (designed with DSD) as a form of immediate loading. The third stage included the scanning of screw-retained temporary reconstructions, then scanning from the MUA level and creating final reconstruction. Results: The presented workflow enabled the delivery of some sort of restoration to the patient at every moment of the treatment and to sustain the required esthetic effect with decent comfort of use even in the early stages. Conclusions: A full digital workflow is a reliable treatment method even in complex cases.

Altered reverse impression method involving extraoral digitalization of a verification jig for the fabrication of implant-supported prosthesis by using a complete-digital workflow.

The reverse impression method involves the extraoral digitalization of the interim implant-supported prostheses and intraoral digitalization of antagonist arch and maxillomandibular relationship. This technique allows the fabrication of implant-supported prostheses by using a complete-digital workflow. The scan analogs make the reverse impression method feasible. However, this method may not be recommended if the interim polymethyl methacrylate prosthesis does not have passive fit. The present manuscript describes an altered reverse impression technique that involves the extraoral digitalization of a conventional verification jig, which has attached scan analogs. With this technique modification, the implant positions captured using the verification jig are used to obtain the virtual definitive implant cast and fabricate the definitive implant-supported prosthesis.

Recommendations for successful virtual patient-assisted esthetic implant rehabilitation: A guide for optimal function and clinical efficiency.

Complete arch implant rehabilitation necessitates meticulous treatment planning and high-level collaboration between surgical and prosthetic dental teams. Emerging virtual technologies hold considerable promise in streamlining this process. The aim of this article is to extend recommendations to clinicians venturing into the virtual patient-assisted esthetic implant rehabilitation workflow. This article summarizes recommendations for virtual patient-assisted esthetic implant rehabilitation in the following five aspects: three-dimensional data handling and superimposition, occlusion and virtual articulator integration in creating virtual patients, streamlined face- and prosthetic-driven surgical planning, reuse of presurgical data ("Copy & Paste"), and final impression for passive fitting of final restoration. To illustrate these principles, a case with complete-mouth implant rehabilitation completed within six visits using this virtual patient workflow is presented. The virtual patient workflow serves as an invaluable tool to perform treatment planning, enhance efficiency, and ensure predictable outcomes in esthetic complete arch implant rehabilitation. Virtual workflows are increasingly prevalent in esthetic implant rehabilitation. Nevertheless, these workflows necessitate a distinct set of knowledge and tools divergent from conventional dentistry practices. This article offers guidelines and recommendations for dental clinicians who are new to this field.

Marginal fit and fracture resistance of polyetheretherketone, zirconia, and titanium implant-supported prosthesis frameworks for a partially edentulous arch after thermomechanical aging

Although polyetheretherketone (PEEK) and zirconia (Zir) have been used as implant-supported prosthesis (ISP) frameworks, the long-term effects of thermomechanical aging on the marginal fit and fracture resistance of PEEK and Zir ISP frameworks with titanium (Ti) bases for patients with a partially edentulous arch are not clear. The purpose of this in vitro study was to determine the marginal fit and fracture resistance of PEEK and Zir ISP frameworks with Ti bases and Ti ISP frameworks for partially edentulous arches after aging. A total of 30 ISP epoxy resin casts were obtained from a typodont with 1 straight implant (Nobel Biocare) in the mandibular right canine region and 1 implant with a 30-degree distal tilt in the mandibular right first molar region. All frameworks (n=10) were fabricated on their own epoxy resin cast with multiunit abutment replicas by using a computer-aided design and computer-aided manufacturing system (exocad-Yenadent). The PEEK and Zir frameworks were fabricated with Ti-bases. Primer (MKZ) and resin cement (DTK adhesive) were used to cement the frameworks to the Ti-bases under a static load of 10N. After thermomechanical aging (1.2×106 cycles, 120N, 5°C-55°C), marginal gaps between the Ti-bases and cemented frameworks and vertical and passive fits between the Ti-bases and framework and multi-unit abutments were measured by using a stereomicroscope (Euromex) at ×100 magnification. Fracture resistances and types were then determined by using a universal test machine and a stereomicroscope at ×40 magnification. Data were analyzed by using 1-way analysis of variance (ANOVA) and the Tukey HSD and Fisher-Freeman-Halton tests (α=.05). The marginal gaps of the PEEK and Zir frameworks were respectively 83.5 ±27.1 and 81.8 ±17.8µm. PEEK (23.7 ±4.6) and Zir (32.9 ±8.7) had a better vertical fit (µm) than Ti (52.5 ±10.6) (P<.001). Zir (49.3 ±16.2) (P<.001) and PEEK (70.9 ±19.6) (P>.05) frameworks had better passive fit (µm) than Ti (91.3 ±24.2). Ti had the highest mean fracture resistance (N) (14800.2 ±3442.3) followed by Zir (7318.7 ±1385.1) and PEEK (3448.9 ±486.6) (P<.001). Fracture types were different in different groups (P<.001). The PEEK and Zir frameworks with Ti baseshad better vertical and passive fit than the Ti frameworks. All ISP frameworks represented mean marginal fit below 92µm and withstood physiologic occlusal forces after thermomechanical aging.

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

Evaluation of the passive fit and definitive marginal fit of prefabricated and conventional CAD-CAM milled titanium bars with a fully guided surgical protocol: An in vitro study

Statement of problemComputer-aided design and computer-aided manufacturing (CAD-CAM) milled titanium bars have shown good clinically acceptable passive fit and definitive marginal fit; however, investigations into the passive fit and definitive marginal fit of prefabricated CAD-CAM milled titanium bars are lacking. PurposeThe purpose of this in vitro study was to compare and evaluate the passive fit and definitive marginal fit of prefabricated and conventional CAD-CAM milled titanium bars. Material and methodsA total of 10 polyurethane radiopaque anatomic completely edentulous mandibular models had implants (Biohorizons) placed in the left and right canine and second premolar positions using a 3-dimensionally printed fully guided surgical guide. For the conventional bars, impressions were made, and casts were scanned and exported to a software program (exocad 3.0). For the prefabricated bars, the surgical plans were exported from the software program directly. The Sheffield test was used to evaluate the passive fit of the bars, and marginal fit was evaluated with a scanning electron microscope at ×50 magnification. The Shapiro-Wilk test was used to determine that the data were normally distributed; the data are presented using mean and standard deviation. Group comparisons were made with the independent t test (α=.05). ResultsThe passive and marginal fit of the conventional bars was better than that of the prefabricated bars. The mean ±standard deviation values for passive fit were 75.2 ±13.7 μm for conventional bars and 94.7 ±16.0 μm for prefabricated bars (P<.001). A statistically significant difference (P<.001) was also found between the marginal fit of the conventional bars 18.7 ±6.1 μm and the prefabricated bars 56.3 ±13.0 μm. ConclusionsConventional CAD-CAM milled titanium bars had a better passive and marginal fit than prefabricated CAD-CAM milled titanium bars; however, both had clinically acceptable passive fit ranging from 75.2 to 94.7 μm and definitive marginal fit ranging from 18.7 to 56.3 μm.

Comparative evaluation of linear dimensional accuracy of impressions made with different elastomeric impression materials (Polyether and Polyvinyl siloxane) in angulated and parallel implants-An invitro study

To date no technique has been proven to guarantee a completely passive fit of implant supported prosthesis framework. Several clinical variables such as angulation of implants, impression material and technique used may affect the precision of impressions. Hence, this study is designed to evaluate and compare the dimensional accuracy of the resultant casts made from open tray implant level impressions with two different impression materials (polyvinyl siloxane and polyether) in parallel and angulated implants. The study consisted of two control groups; master model –1with parallel implants and master model –2 with angulated implants. From master model 1and master model 2, total 40 implant level open tray impressions were made using PVS and polyether impression material and impressions were poured to obtain 40 study casts. The resultant casts were divided into 4 groups (10 casts in each group), according to the impression material used (PVS or Polyether) and implant’s orientation (parallel or angulated) in the casts. All casts were evaluated for the positional accuracy of the implant by using four reference distances with the help of a profile projector. These measurements were compared to the measurements calculated on the master model, which served as a control. The variations of the mean distance values with respective control values within a group were analyzed with one samples’ t’ test at 0.05 significance level. Further the mean distance variations between the groups were analyzed with independent samples ‘t’ test to evaluate group mean variations.The impressions made in the presence of angulated implants were significantly less accurate than the ones made with parallel implants. Regarding impression material the tested polyether resulted advantageous over polivinylsiloxane impression material in terms of recording positional accuracy of implants.

Accuracy of multiple implant impressions using different combinations of impression materials using closed tray technique: An in vitro study.

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.

Accuracy of the Different Materials Used to Fabricate a Verification Jig of Implant-Supported Fixed Complete Dental Prostheses: An In Vitro Study

Introduction The passive fit of a full arch implant-supported prosthesis is one of the elements influencing implant success. Achieving the passive fit of a prosthesis requires verification of the master cast before the fabrication of the framework. A verification jig is a common way to verify the implant master cast and ensure the accuracy of the implant impression and produced cast. Different materials can be used to fabricate verification jigs, and each material exhibits different dimensional changes. In this study, we compared the accuracies of verification jig materials by 3D assessment. Materials and methods A type IV stone cast with four implant analogs was constructed and used as a control. Verification jigs were constructed from five different materials, and test casts were made from these jigs and poured using low expansion stone (type IV), resulting in five groups (n=5). All test casts and the control cast were scanned using a lab scanner. The scans of test casts were superimposed on that of the control cast for 3D accuracy assessment. The distortion of the implant analogs was recorded using Geomagic Design X and GeomagicControlX software (3D Systems, Rock Hill, South Carolina, USA). Statistical differences in the 3D accuracies between the five groups were analyzed using the Kruskal-Wallis test. Result The photopolymerizable resin group had a mean value of 23.16 (± 0.88) µm; the composite group had a mean value of 46.72 (± 2.122) µm; the GC pattern group had a mean of 23.51 (± 0.736) µm; the type III stone group had a mean of 19.84 (± 1.017) µm; the type IV stone group had a mean of 18.72 (± 0.819) µm. The Kruskal-Wallis test indicated that there were statistically significant differences between groups 2 (composite), 4 (type III stone), and 5 (type IV stone). Conclusion The most accurate cast was produced by type IV stone, followed by type III stone, photopolymerizable resin, GC pattern, and composite in order of decreasing accuracy. Within the limitations of the study, a material with low distortion and high accuracy is recommended when fabricating verification jigs of implant-supported complete dental prostheses.