Influence of Manufacturing Methods of Implant-Supported Crowns on External and Internal Marginal Fit: A Micro-CT Analysis

Abstract

Aim To evaluate the influence of different manufacturing methods of single implant-supported metallic crowns on the internal and external marginal fit through computed microtomography. Methods Forty external hexagon implants were divided into 4 groups (n = 8), according to the manufacturing method: GC, conventional casting; GI, induction casting; GP, plasma casting; and GCAD, CAD/CAM machining. The crowns were attached to the implants with insertion torque of 30 N·cm. The external (vertical and horizontal) marginal fit and internal fit were assessed through computed microtomography. Internal and external marginal fit data (μm) were submitted to a one-way ANOVA and Tukey's test (α = .05). Qualitative evaluation of the images was conducted by using micro-CT. Results The statistical analysis revealed no significant difference between the groups for vertical misfit (P = 0.721). There was no significant difference (P > 0.05) for the internal and horizontal marginal misfit in the groups GC, GI, and GP, but it was found for the group GCAD (P ≤ 0.05). Qualitative analysis revealed that most of the samples of cast groups exhibited crowns underextension while the group GCAD showed overextension. Conclusions The manufacturing method of the crowns influenced the accuracy of marginal fit between the prosthesis and implant. The best results were found for the crowns fabricated through CAD/CAM machining.

Adaptability Evaluation of Metal-Ceramic Crowns Obtained by Additive and Subtractive Technologies

“…Differences in the accuracy of fit between CAD/CAM and cast frameworks have been observed in studies with implant-supported prostheses [43], showing the superiority of CAD/CAM results. However, these studies compared different types of restorations obtained by CAD/CAM, over-casting, traditional casting without a consistency regarding the fabrication process, or research methodology [44][45][46].…”

Radiographic Assessment of Accuracy of Fit for Different Conical Connection Abutments on Tapered Implants

“…The early invented external hexagon connection resulted in great possibility of screw loosening problems due to high incidence of rotational misfit giving rise to improper microbial seal. (26,29,30) The shift towards the commonly used nowadays internal connection designs with alteration of the connection part inside the implant body and at a lower level to the implant coronal portion has given this design its unique advantage. (31,32) The internal implantabutment design resulted in better occlusal forces distribution and improved abutment stability in consequence of lowering of the rotational centre and protection of the retention screws, thus, resisting excessive lateral forces.…”

“…(1) Base-metal alloys have been always used as an alternative to noble-metal alloys in prosthodontics as they propose lower price than gold alloys in addition to reasonable biocompatibility and clinical performance. (26) However, base-metal alloys are considered more sensitive to casting fabrication process leading to compromised precise restoration. (27) Accordingly, a prefabricated Co-Cr base with plastic burnout sleeve was introduced in the market to obtain a cheap substitute for precious alloys.…”

The use of micro-computed tomography in dental applications

“…In a study that employed μCT to evaluate the effect on inner and outer marginal compatibility of different production methods of metal crown with single implant support, it was seen that the production method had a direct effect on marginal compatibility between prosthesis and implant. The best results were determined for crowns manufactured using CAD/CAM processes (70).…”