Qualitative and Semi-Quantitative Assessment of Processing-Related Surface Contamination of One- and Two-Piece CAD/CAM Abutments before and after Ultrasonic Cleaning

Abstract

Manufacturing processes of custom implant abutments may contaminate their surfaces with micro wear deposits and generic pollutants. Such particulate debris, if not removed, might be detrimental and provoke inflammatory reactions in peri-implant tissues. Although regulatory guidelines for adequate cleaning, disinfection, or sterilization exist, there does not appear to be a consistent application and data on the amount and extent of such contaminants is lacking. The aim of the present in vitro study was to evaluate the quality and quantity of processing-related surface contamination of computer-aided design/computer-aided manufacturing (CAD/CAM) abutments in the state of delivery and after ultrasonic cleaning. A total of 28 CAD/CAM monotype and hybrid abutments were cleaned and disinfected applying a three-stage ultrasonic protocol (Finevo protocol). Before and after cleaning, the chemical composition and the contamination of the abutments were assessed using scanning electron microscopy (SEM), dispersive X-ray spectroscopy (EDX), and computer-aided planimetric measurement (CAPM). In the delivery condition, monotype abutments showed a significantly higher amount of debris compared to hybrid abutments (4.86 ± 6.10% vs. 0.03 ± 0.03%, p < 0.001). The polishing process applied in the laboratory after bonding the hybrid abutment components reduces the surface roughness and thus contributes substantially to their purity. The extent of contamination caused by computer-aided manufacturing of custom abutments can be substantially minimized using a three-stage ultrasonic protocol.

Microbiological cleaning and disinfection efficacy of a three-stage ultrasonic processing protocol for CAD-CAM implant abutments

“…Recent in vitro studies have detected contaminants on the surfaces of titanium and zirconia CAD-CAM customized implant abutments from various manufacturers. 8 9 10 All tested specimens exhibited process-related roughening, micro wear deposits, and organic and inorganic debris upon delivery. These contaminants can be caused by machining residues, coolant or chemical washing protocols after industrial milling as a remnant of surface processing in centralized production.…”

“…The laboratory procedures for sample production have been described in detail in a previous publication. 10 Briefly summarized, a total of 32 CAD-CAM implant abutments were virtually constructed (Implant Studio; 3Shape, Copenhagen, Denmark) and fabricated (CADAbut F and CADAbut D; BEGO Implant Systems GmbH & Co. KG, Bremen, Germany). The master cast of a clinical case involving the replacement of the right maxillary central incisor with an implant (Semados SCX D 4.1/L 11.5; BEGO Implant Systems GmbH & Co. KG, Bremen, Germany) served as the basis for the digital abutment design.…”

“… 8 9 Analysis revealed contamination on their outer and inner surfaces following laboratory procedures. 10 11 The presence of these micro-residues at the critical abutment-tissue junction may provoke inflammatory responses of the peri-implant tissues and mechanically compromise the stability of the implant-abutment junction. 12 Cleaning and subsequent disinfection of the abutment surface is therefore mandatory.…”

“… 9 19 The abutments are cleaned in three successive ultrasonic baths, one with an antibacterial cleaning solution, the other with 80% ethyl alcohol and finally with medically pure water (Cleaning System; Bredent GmbH & Co. KG, Senden, Germany) at 30℃ for 5 min each, yielding a reduction in deposit particles and organic and inorganic contaminants. 10 While qualitative and semi-quantitative effectiveness in removing these contaminants from CAD-CAM-fabricated surfaces has been demonstrated by microscopic and chemical analyses, 9 10 data on the disinfection efficacy of the three-step ultrasonic procedure are lacking. Therefore, the aim of the present study was to evaluate its potential for ultrasonic disinfection to reduce the microbial load of CAD-CAM implant abutments.…”

Laboratory Fracture Resilience of Hybrid Abutments Used in Oral Rehabilitation: A Systematic Review

“…Currently, there is a wide range of CAD/CAM ceramic abutments with different geometries for connecting the abutment to the implant. The hybrid abutments provide many potential advantages: convenient mechanical features, simplicity, and efficiency [ 7 ]. These new systems have attracted remarkable interest due to their high resistance to fractures, pleasant aesthetics, accurate measures with the implant, and biocompatibility [ 8 ].…”