The Effect of Build Angle and Artificial Aging on the Accuracy of SLA- and DLP-Printed Occlusal Devices.

The aim of this study is to investigate the influence of printing material, build angle, and artificial aging on the accuracy of SLA- and DLP-printed occlusal devices in comparison to each other and to subtractively manufactured devices. A total of 192 occlusal devices were manufactured by one SLA-printing and two DLP-printing methods in 5 different build angles as well as milling. The specimens were scanned and superimposed to their initial CAD data and each other to obtain trueness and precision data values. A second series of scans were performed after the specimens underwent an artificial aging simulation by thermocycling. Again, trueness and precision were investigated, and pre- and post-aging values were compared. A statistically significant influence was found for all main effects: manufacturing method, build angle, and thermocycling, confirmed by two-way ANOVA. Regarding trueness, overall tendency indicated that subtractively manufactured splints were more accurate than the 3D-printed, with mean deviation values around ±0.15 mm, followed by the DLP1 group, with ±0.25 mm at 0 degree build angle. Within the additive manufacturing methods, DLP splints had significantly higher trueness for all build angles compared to SLA, which had the highest mean deviation values, with ±0.32 mm being the truest to the original CAD file. Regarding precision, subtractive manufacturing showed better accuracy than additive manufacturing. The artificial aging demonstrated a significant influence on the dimensional accuracy of only SLA-printed splints.

Effect of surface treatment strategies on bond strength of additively and subtractively manufactured hybrid materials for permanent crowns.

OBJECTIVES: The purpose of this study is to evaluate the bond strength of different computer-aided design / computer-aided manufacturing (CAD/CAM) hybrid ceramic materials following different pretreatments. METHODS: A total of 306 CAD/CAM hybrid material specimens were manufactured, n = 102 for each material (VarseoSmile Crownplus [VSCP] by 3D-printing; Vita Enamic [VE] and Grandio Blocs [GB] by milling). Each material was randomly divided into six groups regarding different pretreatment strategies: control, silane, sandblasting (50 µm aluminum oxide particles), sandblasting + silane, etching (9% hydrofluorics acid), etching + silane. Subsequently, surface roughness (Ra) values, surface free energy (SFE) were measured. Each specimen was bonded with a dual-cured adhesive composite. Half of the specimens were subjected to thermocycling (5000 cycles, 5-55 °C). The shear bond strength (SBS) test was performed. Data were analyzed by using a two-way analysis of variance, independent t-test, and Mann-Whitney-U-test (α = 0.05). RESULTS: Material type (p = 0.001), pretreatment strategy (p < 0.001), and the interaction (p < 0.001) all had significant effects on Ra value. However, only etching on VSCP and VE surface increased SFE value significantly. Regarding SBS value, no significant difference was found among the three materials (p = 0.937), while the pretreatment strategy significantly influenced SBS (p < 0.05). Etching on VSCP specimens showed the lowest mean value among all groups, while sandblasting and silane result in higher SBS for all test materials. CONCLUSIONS: The bond strength of CAD/CAM hybrid ceramic materials for milling and 3D-printing was comparable. Sandblasting and silane coupling were suitable for both millable and printable materials, while hydrofluoric etching should not be recommended for CAD/CAM hybrid ceramic materials. CLINICAL RELEVANCE: Since comparable evidence between 3D-printable and millable CAD/CAM dental hybrid materials is scarce, the present study gives clear guidance for pretreatment planning on different materials.

Occlusal changes on implant-supported single crowns with one year follow-up after loading: A systematic review and meta-analysis.

OBJECTIVE: This systematic review evaluated the occlusal changes after loading with implant-supported single crowns. SOURCES: An electronic literature search was conducted in PubMed, Embase and Cochrane library for randomized (RCTs) or non-randomized controlled clinical trials (CCTs), with a minimum of 10 patients. STUDY SELECTION: Studies reporting the occlusal force changes on implant-supported single crowns - with natural teeth as antagonist - measured at baseline and after loading periods were included. 4 CCTs including 133 ISCs in posterior sites were included for meta-analysis. All analyzed ISCs had no contact at a light bite and a light contact at a heavy bite in MIP at loading (baseline). DATA: The relative occlusal forces (ROFs) of each implant-supported single crown (ISC) or control tooth (CT) were extracted. ROFs were defined as percentage of the total occlusal force of the entire dentition at maximum intercuspal position (MIP). A meta-analysis was conducted to compare the ROF changes at different follow-up periods and the weighted mean differences in ROF between ISCs and CTs were pooled and analyzed. The amount of change in ROF was significantly lower in 6 to 12 months after loading comparing the follow-up period between baseline and 6 month (p < 0.05). At baseline and 3-month follow-up, CTs presented significant higher ROF than ISCs (p < 0.05), while no significant difference was found after half year following. CONCLUSIONS: This study showed that the ROF changes significantly over time after loading of ISCs. It might prove that the occlusal concept defined at the time of prosthetic delivery changes or adapts naturally over time. CLINICAL SIGNIFICANCE: The function of specific implant occlusal concept (no contact at a light bite and a light contact at a heavy bite in MIP) is limited over time and careful monitoring and occlusal adjustments should be recommendable during the first-year follow-up.

Microstructural investigation of hybrid CAD/CAM restorative dental materials by micro-CT and SEM.

OBJECTIVES: An increasing number of CAD/CAM (computer-aided design/computer-aided manufacturing) hybrid materials have been introduced to the dental market in recent years. In addition, CAD/CAM hybrid materials for additive manufacturing (AM) are becoming more attractive in digital dentistry. Studies on material microstructures using micro-computed tomography (µ-CT) combined with scanning electron microscopy (SEM) have only been available to a limited extent so far. METHODS: One CAD/CAM three-dimensional- (3D-) printable hybrid material (VarseoSmile Crown plus) and two CAD/CAM millable hybrid materials (Vita Enamic; Voco Grandio), as well as one direct composite material (Ceram.x duo), were included in the present study. Cylindrical samples with a diameter of 2 mm were produced from each material and investigated by means of synchrotron radiation µ-CT at a voxel size of 0.65 µm. Different samples from the same materials, obtained by cutting and polishing, were investigated by SEM. RESULTS: The 3D-printed hybrid material showed some agglomerations and a more irregular distribution of fillers, as well as a visible layered macrostructure and a few spherical pores due to the printing process. The CAD/CAM millable hybrid materials revealed a more homogenous distribution of ceramic particles. The direct composite material showed multiple air bubbles and microstructural irregularities based on manual processing. SIGNIFICANCE: The µ-CT and SEM analysis of the materials revealed different microstructures even though they belong to the same class of materials. It could be shown that µ-CT and SEM imaging are valuable tools to understand microstructure and related mechanical properties of materials.

Accuracy of the intaglio surface of 3D-printed hybrid resin-ceramic crowns, veneers and table-tops: An in vitro study.

OBJECTIVES: The present study aims to examine the influence of the build angle on the accuracy (trueness and precision) of 3D printed crowns, table-tops and veneers with a hybrid resin-ceramic material. METHODS: One crown, on table-top and one veneer were printed in five different build angles (0°, 30°, 45°, 60°, 90°) (n = 50) with the digital light processing (DLP) system (Varseo XS, Bego) using hybrid resin (Varseo Smile Crownplus A3, Bego). All printed restorations were scanned using the laboratory scanner (D2000, 3Shape) and matched onto the initial reference design in metrology software (Geomagic Control X, 3D Systems). The root mean square error (RMSE) was calculated between the scanned and reference data. The data was statistically analyzed using the Tukey multiple comparison test and Wilcoxon multiple comparison test. RESULTS: The crown group showed higher trueness at 30° (0.021 ± 0.002) and 45° (0.020 ± 0.002), and table-tops at 0° (0.015 ± 0.001) and 30° (0.014 ± 0.001) (p < 0.0001). Veneers demonstrated higher trueness at 30° (0.016 ± 0.002) (p < 0.0001). All three restoration types demonstrated the lowest trueness at a 90° build angle and portrayed deviations along the z axis. The veneer and table-top groups showed the lowest precision at 90° (veneers: 0.021 ± 0.008; table-tops: 0.013 ± 0.003). The crown group portrayed the lowest precision at 45° (0.017 ± 0.005) (p < 0.0001). CONCLUSION: The build angle of DLP-printed hybrid resin-ceramic restorations influences their accuracy. CLINICAL SIGNIFICANCE: Considering the build angle is important to achieve a better accuracy of 3D-printed resin-ceramic hybrid restorations. This may help predict or avoid the interference points between a restoration and a die and minimize the clinical adjustments.

Evaluation of the accuracy of fully guided implant placement by undergraduate students and postgraduate dentists: a comparative prospective clinical study.

PURPOSE: This study aimed to assess the accuracy of implant placement through three-dimensional planning and fully guided insertion, comparing outcomes between undergraduate and postgraduate surgeons. METHODS: Thirty-eight patients requiring 42 implants in posterior single-tooth gaps were enrolled from the University Clinic for Prosthodontics at the Martin Luther University Halle Wittenberg and the Department of Prosthodontics, Geriatric Dentistry, and Craniomandibular Disorders of Charité University Medicine, Berlin. Twenty-two implants were placed by undergraduate students (n = 18), while 20 implants were placed by trainee postgraduate dentists (n = 5). Pre-operative intraoral scans and cone beam computed tomography images were performed for implant planning and surgical template fabrication. Postoperative intraoral scans were superimposed onto the original scans to analyze implant accuracy in terms of apical, coronal, and angular deviations, as well as vertical discrepancies. RESULTS: In the student group, two implant insertions were performed by the assistant dentist because of intraoperative complications and, thus, were excluded from further analysis. For the remaining implants, no statistically significant differences were observed between the dentist and student groups in terms of apical (p = 0.245), coronal (p = 0.745), or angular (p = 0.185) implant deviations, as well as vertical discrepancies (p = 0.433). CONCLUSIONS: This study confirms the viability of fully guided implant placement by undergraduate students, with comparable accuracy to postgraduate dentists. Integration into dental education can prepare students for implant procedures, expanding access and potentially reducing costs in clinical practice. Collaboration is essential for safe implementation, and future research should explore long-term outcomes and patient perspectives, contributing to the advancement of dental education and practice. TRIAL REGISTRATION: DRKS, DRKS00023024, Registered 8 September 2020-Retrospectively registered, https://drks.de/search/de/trial/DRKS00023024 .

Wear resistance and flexural properties of low force SLA- and DLP-printed splint materials in different printing orientations: An in vitro study.

OBJECTIVES: To investigate the influence of material and printing orientation on wear resistance and flexural properties of one low force SLA- and two DLP-printed splint materials and to compare these 3D-printed splints to a subtractively manufactured splint material. METHODS: Two DLP-printed (V-Print splint, LuxaPrint Ortho Plus) and one low force SLA-printed (Dental LT Clear) material, where specimens were printed in three printing orientations (0°, 45°, 90°), were investigated. In addition, one milled splint material (Zirlux Splint Transparent) was examined. A total of 160 specimens were produced for both test series. The two-body wear test was performed in a chewing simulator (80'000 cycles at 50 N with 5-55 °C thermocycling). Steatite balls were used as antagonists. The wear pattern was analyzed with a 3D digital microscope in terms of maximum vertical intrusion depth (mm) and total volume loss (mm³). The flexural properties were investigated by three-point bending in accordance with ISO 20795-1: 2013 (denture base polymers). The flexural strength (MPa) and the flexural modulus (MPa) were measured. Two-way ANOVA was performed to investigate the effects of the two independent variables material and printing orientation for the three 3D-printed materials. The comparison of the printing orientations within one material was carried out with one-way ANOVA with post-hoc Tukey tests. RESULTS: Two-way ANOVA revealed that wear and flexural properties are highly dependent on the 3D-printed material (p < 0.001). Across groups, a significant effect was observed for wear depth (p = 0.031) and wear volume (p = 0.044) with regard to printing orientation but this was not found for flexural strength (p = 0.080) and flexural modulus (p = 0.136). One-way ANOVA showed that both DLP-printed groups showed no significant differences within the printing orientations in terms of wear and flexural properties. Dental LT Clear showed that 90° oriented specimens had higher flexural strength than 0° oriented ones (p < 0.001) and 45° oriented specimens also showed higher values than 0° ones (p = 0.038). No significant differences were observed within the printing orientations for flexural modulus and wear behaviour within this group. T-tests showed that the milled splints exhibited statistically higher wear resistance and flexural properties compared to all three 3D-printed splint materials (p < 0.001) and that highly significant differences were found between the 3D-printed splint materials for both test series. CONCLUSION: Within the limitations of this in vitro study, it can be stated that wear behaviour and flexural properties are highly dependent on the 3D-printed material itself. Currently, milled splints exhibit higher wear resistance and flexural properties compared to 3D-printed splint materials. The printing orientation has a minor influence on the properties investigated. Nevertheless, two-way ANOVA also showed a significant influence of printing orientation in the wear test across groups and one-way ANOVA detected significant effects for SLA material in terms of flexural strength, with printing in 90° showing the highest flexural strength. Therefore, anisotropy was found in SLA material, but it can be limited with the employed printing parameters. Both DLP-printed materials showed no significant difference within the printing orientation.

Antagonist enamel tooth wear produced by different dental ceramic systems: A systematic review and network meta-analysis of controlled clinical trials.

OBJECTIVES: The aim of this study was to evaluate the amount of enamel tooth wear induced by different antagonistic ceramic crown materials in the posterior area within a follow-up period up to 24 months in function. A network meta-analysis was performed to assess the effect of the materials on the mean vertical loss (MVL) of the antagonist enamel tooth surface. DATA: Main search terms used in combination: ceramic, dental materials, metal ceramic, tooth wear and dental enamel. SOURCES: An electronic search was conducted in PubMed/Medline, Embase, and Cochrane CENTRAL plus hand-searching. STUDY SELECTION: Eligibility criteria included clinical studies reporting on MVL on antagonist's tooth up to 24 months following the permanent crown placement. From a total of 5697 articles, 7 studies reporting on 261 crowns for 177 subjects with 3 ceramic materials (Lithium disilicate, metal-ceramic, monolithic zirconia) were included. Among all, metal-ceramic and zirconia caused significantly higher enamel tooth wear on antagonist teeth, representing 82.5 µm [54.4; 110.6]) and 40.1 µm [22.2; 58.0]) more MVL than natural teeth group. In contrast, lithium disilicate showed only 5.0 µm [-48.2; 58.1]) more MVL than occurs on opposing natural teeth. CONCLUSIONS: This systematic review demonstrated that prosthodontic ceramic materials produced significantly more antagonist enamel tooth wear than opposing natural enamel tooth wear, and ceramic material type was correlated to the degree of enamel tooth wear. Additional well-conducted, randomized controlled trials with homogeneous specimens are required due to inadequate sample size and number of the clinical studies included in the analyses. CLINICAL SIGNIFICANCE: The amount of wear caused by different restorative materials has a high influence on the antagonistic natural teeth and should therefore be evaluated intensively by the dentist.

Segmentation of process-related contaminations on two-piece abutments using pixel-based machine learning: a new quantification approach?

PURPOSE: A reference method for quantifying contaminations on two-piece abutments manufactured using CAD/CAM has not yet been established. In the present in vitro study, a pixel--based machine learning (ML) method for detecting contamination on customized two-piece abutments was investigated and embedded in a semiautomated quantification pipeline. MATERIALS AND METHODS: Forty-nine CAD/CAM zirconia abutments were fabricated and bonded to a prefabricated titanium base. All samples were analyzed for contamination by scanning electron microscopy (SEM) imaging followed by pixel--based ML and thresholding (SW) for contamination detection; quantification was performed in the postprocessing pipeline. Wilcoxon signed-rank test and Bland-Altmann plot were applied to compare both methods. The contaminated area fraction was recorded as a percentage. RESULTS: There was no statistically significant difference between the percentages of contamination areas (median = 0.004) measured with ML (median = 0.008) and with SW (median = 0.012), asymptotic Wilcoxon test: P = 0.22. The Bland-Altmann plot demonstrated a mean difference of -0.006% (95% confidence interval [CI] from -0.011% to 0.0001%) with increased values from a contamination area fraction of > 0.03% for ML. CONCLUSION: Both segmentation methods showed comparable results in evaluating surface cleanliness; pixel-based ML is a promising assessment tool for detecting external contaminations on zirconia abutments. Further studies are required to investigate the clinical performance of this tool.

Mechanical properties of 3D-printed and milled composite resins for definitive restorations: An in vitro comparison of initial strength and fatigue behavior.

OBJECTIVE: To evaluate the flexural strength and fatigue behavior of a novel 3D-printed composite resin for definitive restorations. MATERIALS AND METHODS: Fifty disc-shaped specimens were manufactured from each of a nanohybrid composite resin (NHC), polymer-infiltrated ceramic network (PICN), and 3D-printed composite resin (3D) with CAD-CAM technology. Biaxial flexural strength (σin ) (n = 30 per group) and biaxial flexural fatigue strength (σff ) (n = 20 per group) were measured using piston-on-three-balls method, employing a staircase approach of 105 cycles. Weibull statistics, relative-strength degradation calculations, and fractography were performed. The results were analyzed with 1-way ANOVA and Games-Howell post hoc test (α = 0.05). RESULTS: Significant differences in σin and σff among the groups (p < 0.001) were detected. The NHC group provided the highest mean ± standard deviation σin and σff (237.3 ± 31.6 MPa and 141.3 ± 3.8 MPa), followed by the PICN (140.3 ± 12.9 MPa and 73.5 ± 9.9 MPa) and the 3D (83.6 ± 18.5 MPa and 37.4 ± 23.8 MPa) groups. The 3D group exhibited significantly lower Weibull modulus (m = 4.7) and up to 15% higher relative strength degradation with areas of nonhomogeneous microstructure as possible fracture origins. CONCLUSIONS: The 3D-printed composite resin exhibited the lowest mechanical properties, where areas of nonhomogeneous microstructure developed during the mixing procedure served as potential fracture origins. CLINICAL SIGNIFICANCE: The clinical indications of the investigated novel 3D-printed composite resin should be limited to long-term provisional restorations. A cautious procedure for mixing the components is crucial before the 3D-printing process, since nonhomogeneous areas developed during the mixing could act as fracture origins.

Evaluating the prospective crown-root ratio after extrusion and crown lengthening procedures in vitro.

For restoration of extensively damaged teeth preprosthetic treatment measures are necessary. Crown lengthening and extrusion affect the prospective crown-root ratio (CRR). The subject of this in vitro study was to compute CRRs for both treatment approaches. 120 human maxillary central extracted incisors were measured. Measurements were calculated for five treatment groups: C (control), E-2 mm (extrusion of 2 mm), E-4 mm (extrusion of 4 mm), CL-2 mm (crown lengthening of 2 mm), and CL-4 mm (crown lengthening of 4 mm). Tooth (TL), root (RL), and crown lengths (CL) were measured from mesial (m) and facial (f) cemento-enamel junction (CEJ), and respective anatomic (CRR) and effective crown-root ratios (eCRR) were calculated. Following CRR values were computed for C: CRR-m = 0.4 ± 0.1, CRR-f = 0.7 ± 0.1. All crown-root ratios were lower (more favourable) for extrusion compared to crown lengthening (p < 0.001). ECRRs were higher than anatomic CRRs. CRR at mesial CEJ was significantly lower than CRR with facial CEJ as reference (p < 0.001). Mesial measurement-based calculations of CRR typically based on radiographic images should be interpreted with caution as they underestimate the eCRR. CRR can be expected as lower, i.e. more favourable, when teeth are extruded than crown lengthened.

Survival and complications of 3D-printed, non-invasive restorations for prosthetic rehabilitations: A 12-month preliminary observational study.

AIM: The adjustment and transfer of a stable occlusion can be a major challenge in prosthetic rehabilitations. The aim of this study was to assess a non-invasive treatment option for complex prosthetic rehabilitations and occlusal analyses using 3D-printed restorations clinically. MATERIALS AND METHODS: Eleven patients received a partial or complete rehabilitation with the aid of 3D-printed restorations (n=171). After 12 months of clinical service, all restorations were analyzed using the United States Public Health Service (USPHS) criteria. RESULTS: The 12-month clinical data revealed that 3D-printed restorations showed a survival rate of 84.4%. Complications occurred mostly regarding the anatomical form (7%) or marginal integrity (6AC%) and were consequently rated "Charlie" or "Delta." Color stability and color match of 3D-printed restorations were rated "Alpha" in 83% and 73%, respectively, of all restorations. Marginal inflammation was rated "Alpha" in 89% of all restorations. An excellent surface texture and no secondary caries or postoperative sensitivities (100%) were observed. CONCLUSIONS: 3D-printed restorations might be an alternative treatment option for initiating complex prosthetic rehabilitations. Technical complications rarely occurred. Biological complications did not occur at all. The color stability showed promising results after 12 months of clinical service. However, the results should be interpreted with caution. Long-term results with a high number of restorations should be awaited.

Microleakage along the implant-abutment interface: a systematic review and meta-analysis of in vitro studies.

PURPOSE: This systematic review aimed to evaluate the incidence of microleakage events (IME) and to identify the potential factors influencing the sealing ability of the implant-abutment interface (IAI) under in vitro investigation. MATERIAL AND METHODS: An electronic search of MEDLINE (PubMed), EMBASE, and Web of Science databases, combined with a manual literature search was conducted up to September 2022. In vitro studies that reported the degree of microleakage at IAI under dynamic loading conditions were included. A meta-analysis was performed to calculate the mean values of the incidence of microleakage events. Subgroup analysis and meta-regression were conducted to further investigate the effect of different variables. RESULTS: 675 studies were identified following the search process and 17 in vitro studies were selected according to the eligibility criteria. The weighted mean incidence of microleakage events was 47% (95% confidence interval: [0.33, 0.60]), indicating that contamination was observed in nearly half of the samples. Concerning possible factors that may influence microleakage (e.g., loading condition, assessment method, implant-abutment connection design, types of abutment material, the use of sealing agents), loading condition (p = 0.016) was the only variable that significantly influenced IME in the meta-regression analysis. CONCLUSIONS: The results demonstrated that dynamic loading significantly increases the potential of bacterial penetration at the implant-abutment junction. The results should be interpreted carefully due to the data heterogeneity and further well-conducted in vitro studies with homogeneous samples are needed to standardize the methodologies.

Forced Orthodontic Extrusion to Restore the Unrestorable: A Proof of Concept.

The purpose of this clinical study was to assess the feasibility of forced orthodontic extrusion with the Tissue Master Concept to retain subgingivally fractured teeth as abutments for which extraction and replacement would be equal treatment opportunities. Participants were recruited from a group of consecutive patients in need of prosthodontic rehabilitation. In total, 36 deeply destroyed teeth in 31 patients underwent forced orthodontic extrusion with forces exceeding 50 g to reestablish biologic width and ensure a 2-mm dentin-ferrule design prior to single-crown restoration. The primary endpoint was the success of the extrusion in terms of the ability to restore the respective abutment tooth. Information about overall treatment time, frequency, and reasons for failure were collected. Four patients dropped out of the treatment. For the remaining 27 participants, data were fully collected. The amount of extrusion ranged between 2 and 6 mm (3.5 ± 0.9 mm), and the mean duration until retention was 20 ± 12 days. On average, patients returned three (± 3) times for control visits after extrusion. Adhesive failure (n = 6) and orthodontic relapse (n = 2) were the most frequent complication types. Forced orthodontic extrusion may be a useful tool to restore teeth evaluated as nonrestorable.

Esthetic and functional rehabilitation of a patient with a bilateral cleft of lip, alveolar process, and palate with anterior all-ceramic cantilever resin-bonded fixed dental prostheses.

OBJECTIVES: Addressing a single-tooth gap in the anterior region, resulting from aplasia or trauma, poses both esthetic and functional challenges. This case report presents the restoration of a young adult with a cleft, exhibiting anterior hypoplasia and aplasia in the canine and incisor regions, using all-ceramic cantilever resin-bonded fixed dental prostheses. METHOD AND MATERIALS: After verification of esthetic and functional considerations through a diagnostic wax-up and an intraoral mock-up, three anterior all-ceramic cantilever resin-bonded fixed dental prostheses made of veneered zirconium dioxide were planned in the region of the maxillary right lateral incisor and maxillary left canine. The impression was made with an intraoral scanner. The framework fit was evaluated. Glaze firing and full adhesive cementation under rubber dam followed. RESULTS: The final restoration met the patients' expectations and restored facial esthetics and function. CONCLUSIONS: All-ceramic cantilever resin-bonded fixed dental prostheses offer a promising minimally invasive therapeutic option for cleft patients.

Influence of exposure of customized dental implant abutments to different cleaning procedures: an in vitro study using AI-assisted SEM/EDS analysis.

PURPOSE: Dental implant abutments are defined as medical devices by their intended use. Surfaces of custom-made CAD/CAM two-piece abutments may become contaminated during the manufacturing process in the dental lab. Inadequate reprocessing prior to patient care may contribute to implant-associated complications. Risk-adapted hygiene management is required to meet the requirements for medical devices. METHODS: A total of 49 CAD/CAM-manufactured zirconia copings were bonded to prefabricated titanium bases. One group was bonded, polished, and cleaned separately in dental laboratories throughout Germany (LA). Another group was left untreated (NC). Five groups received the following hygiene regimen: three-stage ultrasonic cleaning (CP and FP), steam (SC), argon-oxygen plasma (PL), and simple ultrasonic cleaning (UD). Contaminants were detected using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) and segmented and quantified using interactive machine learning (ML) and thresholding (SW). The data were statistically analysed using non-parametric tests (Kruskal-Wallis test, Dunn's test). RESULTS: Significant differences in contamination levels with the different cleaning procedures were found (p ≤ 0.01). The FP-NC/LA groups showed the most significant difference in contamination levels for both measurement methods (ML, SW), followed by CP-LA/NC and UD-LA/NC for SW and CP-LA/NC and PL-LA/NC for ML (p ≤ 0.05). EDS revealed organic contamination in all specimens; traces of aluminum, silicon, and calcium were detected. CONCLUSIONS: Chemothermal cleaning methods based on ultrasound and argon-oxygen plasma effectively removed process-related contamination from zirconia surfaces. Machine learning is a promising assessment tool for quantifying and monitoring external contamination on zirconia abutments.