This in vitro study aimed to evaluate the fracture resistance of endodontically treated maxillary... more This in vitro study aimed to evaluate the fracture resistance of endodontically treated maxillary central incisors with different post systems. Methods: Fifty-six extracted intact maxillary permanent central incisors were used, treated endodontically (except for the control group), and distributed into the following seven test groups (n=8) depending on the post type: UHT (control group: root-filled teeth without endodontic post), ZRP (prefabricated zirconia post), GFP (prefabricated glass fiber post), CFP (prefabricated carbon fiber post), CPC (custom-made cast post and core), TIP (prefabricated titanium post), and MIP (prefabricated mixed post). The specimens were loaded in a universal testing machine until fracture occurrence. Failure loads were then analyzed with one-way analysis of variance (ANOVA), followed by multiple comparisons by using Tukey's honest significant difference test (α=0.05). Results: Mean (SD) failure loads for groups ranged from 524±73.2 N for CPC to 764.1±156 N for GFP. Oneway ANOVA showed significant differences in terms of fracture resistances among groups (P<0.001). Tukey's honest significant difference test showed significant differences in fracture resistance within groups (P≤0.05), whereas no difference was observed between the UHT (control group) and CFP and CPC groups (P≥0.05). Conclusion: Endodontically treated teeth restored with zirconia post, glass fiber post, titanium post, or mixed post were more resistant to fracture loads compared with those that were not restored (control group) or restored with either carbon fiber post or cast post and core.
In der heutigen Zeit werden Rekonstruktionen immer häufiger maschinell angefertigt. Die CAD/CAM-T... more In der heutigen Zeit werden Rekonstruktionen immer häufiger maschinell angefertigt. Die CAD/CAM-Technologie hat sich in der Zahnheilkunde, vor allem für die Verarbeitung von Zirkoniumdioxid etabliert. Mittlerweile werden industriell polymerisierte "Hochleistungskunststoffe" als CAD/CAM-Rohlinge angeboten. Daher können Provisorien nicht mehr länger nur nach den konventionellen Techniken, sondern auch maschinell hergestellt werden. Durch die industrielle Polymerisation unter hohem Druck, können die mechanischen Eigenschaften der Kunststoffe verbessert und optimiert werden. Auch die Ästhetik der CAD/CAM-gefertigten Provisorien ist mit der der manuell hergestellten Kunststoffprovisorien vergleichbar.
AimTo assess in vitro the workflow for alveolar ridge augmentation with customised 3D printed blo... more AimTo assess in vitro the workflow for alveolar ridge augmentation with customised 3D printed block grafts and simultaneous computer‐assisted implant planning and placement.MethodsTwenty resin mandible models with an edentulous area and horizontal ridge defect in the region 34–36 were scanned with cone beam computed tomography (CBCT). A block graft for horizontal ridge augmentation in the region 34–36 and an implant in the position 35 were digitally planned. Twenty block grafts were 3D printed out of resin and one template for guided implant placement were stereolithographically produced. The resin block grafts were positioned onto the ridge defects and stabilised with two fixation screws each. Subsequently, one implant was inserted in the position 35 through the corresponding template for guided implant placement. Optical scans of the study models together with the fixated block graft were performed prior to and after implant placement. The scans taken after block grafting were superimposed with the virtual block grafting plan through a best‐fit algorithm, and the linear deviation between the planned and the achieved block positions was calculated. The precision of the block fixation was obtained by superimposing the 20 scans taken after grafting and calculating the deviation between the corresponding resin blocks. The superimposition between the scans taken after and prior to implant placement was performed to measure a possible displacement in the block position induced by guided implant placement. The (98–2%)/2 percentile value was determined as a parameter for surface deviation.ResultsThe mean deviation in the position of the block graft compared to the virtual plan amounted to 0.79 ± 0.13 mm. The mean deviation between the positions of the 20 block grafts measured 0.47 ± 0.2 mm, indicating a clinically acceptable precision. Guided implant placement induced a mean shift of 0.16 ± 0.06 mm in the position of the block graft.ConclusionsWithin the limitations of this in vitro study, it can be concluded that customised block grafts fabricated through CBCT, computer‐assisted design and 3D printing allow alveolar ridge augmentation with clinically acceptable predictability and reproducibility. Computer‐assisted implant planning and placement can be performed simultaneously with computer‐assisted block grafting leading to clinically non‐relevant dislocation of block grafts.
International journal of computerized dentistry, 2017
STATEMENT OF PROBLEM Three-dimensional (3D) intraoral scanning systems allow for the simultaneous... more STATEMENT OF PROBLEM Three-dimensional (3D) intraoral scanning systems allow for the simultaneous acquisition of 3D information about tooth surfaces and a photorealistic view of the patient's tooth colors. AIM The goal of this study was the in vivo comparison of a new 3D scanner with a color acquisition mode and conventional visual and digital color measurements. MATERIALS AND METHODS The colors of 40 teeth of 20 patients were evaluated in seven ways: 1) By dentists using the Vita 3D-Master; 2) By dental technicians using the Vita 3D-Master; 3) With the 3Shape Trios device; 4) With the Vita Easyshade device; 5) With the Vita Easyshade Advance device; 6) With the SpectroShade device; and 7) With the SpectroShade Micro device. Digital measurements of Groups 3 to 7 were repeated three times for each tooth. For all groups, both the CIE Lab values and the Vita 3D-Master values were recorded. The repeatability and relative accuracy of the Vita 3D-Master values were analyzed statistically using Pearson's chi-squared test (α < 0.05). ΔE values were calculated from the CIE Lab values, which served as a basis for performing multidimensional scaling (MDS) and evaluating differences between the groups using the one-way ANOVA with post hoc Tamhane's test (α < 0.05). RESULTS The results of the ΔE values showed that clinically relevant differences between the evaluation by dentists, dental technicians, and the intraoral scanning device (3Shape) are negligible. The intraoral 3D scanning device (Group 3) and the digital systems (Groups 4 to 7) did not differ significantly in the repeatability of color shade management. The SpectroShade Micro (Group 7) had significantly better relative accuracy than the other devices. CONCLUSIONS The results demonstrate that intraoral scanning systems can be used to measure both tooth color and tooth surface in 3D. CLINICAL IMPLICATIONS Intraoral optical scanning devices allow for the acquisition of accurate 3D surface data. Tooth color can be evaluated simultaneously and can be used to determine the color of restorations without requiring additional conventional color-measurement methods.
Chairside sintering might be a suitable procedure to produce zirconia restorations with clinicall... more Chairside sintering might be a suitable procedure to produce zirconia restorations with clinically adequate fracture loading values for specific restoration thicknesses.
STATEMENT OF PROBLEM The use of computer-aided design and computer-aided manufacturing (CAD-CAM) ... more STATEMENT OF PROBLEM The use of computer-aided design and computer-aided manufacturing (CAD-CAM) technologies is widely established, with single restorations or short fixed partial dentures having similar accuracy when generated from digital scans or conventional impressions. However, research on complete-arch scanning of edentulous jaws is sparse. PURPOSE The purpose of this pilot in vitro study was to compare the accuracy of a digital scan with the conventional method in a workflow generating implant-supported complete-arch prostheses and to establish whether interference from flexible soft tissue segments affects accuracy. MATERIAL AND METHODS An edentulous maxillary master cast containing 6 angled implant analogs was used and digitized with mounted scan bodies by using a high-precision laboratory scanner. The master cast was then scanned 10 times with 4 different intraoral scanners: TRIOS 3 with a complete-arch scanning strategy (TRI1) or implant-scanning strategy (TRI2), TRIOS Color (TRC), CEREC Omnicam (CER), and CEREC Primescan (PS). The same procedure was repeated with 4 different levels of free gingiva (G0-G3). Ten conventional impressions were obtained. Differences in implant position and direction were evaluated at the implant shoulder as mean values for trueness and interquartile range (IQR) for precision. Statistical analysis was performed by using the Kruskal-Wallis and post hoc Conover tests (α=.05). RESULTS At G0, position deviations ranged from 34.8 μm (IQR 23.0 μm) (TRC) to 68.3 μm (12.2 μm) (CER). Direction deviations ranged from 0.34 degrees (IQR 0.18 degrees) (conventional) to 0.57 degrees (IQR 0.37 degrees) (TRI2). For digital systems, the position deviation ranged from 48.4 μm (IQR 5.9 μm) (PS) to 76.6 μm (IQR 8.1 μm) (TRC) at G1, from 36.3 μm (IQR 9.3 μm) (PS) to 79.9 μm (IQR 36.1 μm) (TRI1) at G2, and from 51.8 μm (IQR 14.3 μm) (PS) to 257.5 μm (IQR 106.3 μm) (TRC) at G3. The direction deviation ranged from 0.45 degrees (IQR 0.15 degrees) (CER) to 0.64 degrees (IQR 0.20 degrees) (TRC) at G1, from 0.38 degrees (IQR 0.05 degrees) (PS) to 0.925 degrees (IQR 0.09 degrees) (TRI) at G2, and from 0.44 degrees (IQR 0.07 degrees) (PS) to 1.634 degrees (IQR 1.08 degrees) (TRI) at G3. Statistical analysis revealed significant differences among the test groups for position (G0: P<.
International journal of computerized dentistry, 2013
Die digitale intraorale Abformung spielt eine zentrale Rolle in der modernen CAD/CAM-gestützten Z... more Die digitale intraorale Abformung spielt eine zentrale Rolle in der modernen CAD/CAM-gestützten Zahnmedizin. Sie ermöglicht neue Behandlungsoptionen für den Patienten und beschleunigt den Workflow bei der Restaurationsherstellung. Die wichtigste Aufgabenstellung bei einem intraoralen Scansystem besteht heutzutage darin, insbesondere in größeren Scanbereichen genauer zu arbeiten und die klinische Handhabung für den Zahnarzt zu vereinfachen. Ziel dieser Studie ist es, unterschiedliche Scanstrategien in vitro auf ihre Genauigkeit bei Scans des gesamten Zahnbogens zu untersuchen. Für die digitale Abformung mit den Systemen Lava COS, Cerec Bluecam und Cadent iTero wurde ein Referenzmeistermodell verwendet. Bei jedem Scanprotokoll wurden Richtigkeit und Präzision bestimmt. Lava COS lieferte dabei mit dem vom Hersteller empfohlenen Scanprotokoll eine Richtigkeit von 45,8 μm. Mit einem anderen Scanprotokoll ergab sich eine signifikant niedrigere Genauigkeit (Richtigkeit ± 90,2 μm). Auch bei Cerec Bluecam erweist sich ein optimales Scanprotokoll mit einer Richtigkeit von ± 23,3 μm im Vergleich zu ± 52,5 μm mit einem Standardprotokoll als vorteilhaft. Das puderfreie Cadent iTero Scansystem konnte den kompletten Zahnbogen mit einer Richtigkeit von ± 35,0 μm und einer Präzision
International journal of computerized dentistry, 2011
The digital intraoral impression has become a central part of the CAD/CAM technique. The objectiv... more The digital intraoral impression has become a central part of the CAD/CAM technique. The objective of the present study was to compare the accuracy (trueness and precision) of digital impressions of the full arch with that of conventional impressions on the in-vitro model. For this purpose, a master model was acquired with a new reference scanning process, the measuring trueness of which was +/- 4.1 microm and the precision +/- 2.5 microm. On the one hand, conventional impressions and then plaster models (n = 5) were produced from this master model, and on the other hand, digital impressions were made with the Cerec AC Bluecam and the Lava COS system (each n = 5). The plaster models were also scanned with the reference scanner. The available data records were superimposed and the differences determined. The deviation from the master model defines the trueness of the impression method. The deviations of the models among one another demonstrate the precision of the method. The trueness of the impressions was 55 +/- 21.8 microm in the conventional impression group, for digital impressions with Cerec Bluecam it was 49 +/- 14.2 microm and for digital impressions with Lava COS 40.3 +/- 14.1 microm. The precision was 61.3 +/- 17.9 microm for conventional impression with Impregum, 30.9 +/- 7.1 microm for digital impression with the Cerec Bluecam and 60.1 +/- 31.3 microm for digital impression with Lava COS. These in-vitro results show that accuracy of the digital impression is similar to that of the conventional impression. These results will have to be confirmed in further clinical studies.
The aim was to test whether or not soft tissue augmentation with a newly developed collagen matri... more The aim was to test whether or not soft tissue augmentation with a newly developed collagen matrix (CM) leads to volume gain in chronic ridge defects similar to those obtained by an autogenous subepithelial connective tissue graft (SCTG). MATERIAL AND METHODS: In six dogs, soft tissue volume augmentation was performed by randomly allocating three treatment modalities to chronic ridge defects (CM, SCTG, sham-operated control). Impressions were taken before augmentation (baseline), at 28, and 84 days. The obtained casts were optically scanned and the images were digitally analysed. A defined region of interest was measured in all sites and the volume differences between the time points were calculated. RESULTS: The mean volume differences per area between baseline and 28 days amounted to a gain of 1.6 mm (CM; SD+/-0.9), 1.5 mm (SCTG; +/-0.1), and a loss of 0.003 mm (control; +/-0.3). At 84 days, the mean volume differences per area to baseline measured a gain of 1.4 mm (CM; +/-1.1), 1.4 mm (SCTG; +/-0.4), and a loss of 0.3 mm (control; +/-0.3). The differences between CM and SCTG were statistically significant compared with control at 28 and 84 days (p<0.001). CONCLUSION: Within the limits of this animal study, the CM may serve as a replacement for autogenous connective tissue.
Journal of The Mechanical Behavior of Biomedical Materials, Jul 1, 2019
OBJECTIVES To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybri... more OBJECTIVES To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybrid materials bonded to dentin does differ from those of porcelain-fused-to metal or lithium disilicate glass ceramic crowns. MATERIAL AND METHODS In 80 human molars, occlusal tooth substance was removed so that the defects extended into dentin, simulating defects caused by attrition/erosion. Restorations at a standardized thickness of either 0.5 mm or 1.0 mm were digitally designed. For both thicknesses, 4 test groups (n = 10 per group) were defined, each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava Ultimate). Consecutively, the specimens were thermo-mechanically aged and then loaded until fracture. The load-bearing capacities (F) between the groups were statistically compared using the Kruskal-Wallis test (p < 0.05) and pairwise group comparison applying the Dunn's method. In addition, the results were compared to those of conventional lithium-disilicate ceramic crowns ("CLD") and to porcelain-fused to metal crowns ("PFM"). RESULTS The median F values for the 0.5 mm thin restorations were 1'350 N for 0.5-ZIR, 850 N for 0.5-LDC, 1'100 N for 0.5-HYC and 1'950 N for 0.5-COC. With CLD as the control, a significant difference was found between the groups 0.5-COC and 0.5-LDC (KW: p = 0.0124). With PFM as the control, the comparisons between PFM and 0.5-LDC as well as between 0.5-COC and 0.5-LDC were significant (KW: p = 0.0026). Median F values of 2'493 N in the group 0.5-ZIR, 1'165 in the group 0.5-LDC, 2'275 N in the group 0.5-HYC and 2'265 N in the group 0.5-COC were found. The medians of the F values for the 1.0 thick restorations amounted of 2'100 N in 1.0-ZIR, 1'750 N in 1.0-LDC, 2'000 N in 1.0-HYC and 2'300 N in 1.0-COC. Testing the multiple comparisons with Dunn's method no significant differences were found (p > 0.05). The median F values of the 1.0 mm thick restorations were: 2'489 N in the group 1.0-ZIR, 1'864 N in the group 1.0-LDC, 2'485 N in the group 1.0-HYC and 2'479 N in the group 1.0-COC. With CLD as the control group, a significant difference between zirconia and lithium-disilicate was found for the 0.5 (p = 0.0017) and 1.0 mm (p = 0.0320) thick specimens. Comparing the 0.5 mm thick specimens with CLD as the control, a significant difference was found between 0.5-HYC and 0.5-LDC (p = 0.0017). With PFM as the control, the comparison of lithium disilicate and zirconia was statistically significant for both thicknesses (p = 0.0009 for the 0.5 mm thick specimens; p = 0.0074 for the 1.0 mm thick specimens). In addition, with PFM as control group, significant differences were seen between 0.5-LDC and all other groups with restorations in 0.5 mm thickness (p = 0.0017). CONCLUSIONS Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic, hybrid materials or polymeric materials can be applied to correct occlusal tooth wear with exposed dentin and thus replace conventional crown restorations in cases of normally expected intraoral bite forces.
OBJECTIVES: Indirect CAD/CAM restorations can be fabricated using both subtractive and additive C... more OBJECTIVES: Indirect CAD/CAM restorations can be fabricated using both subtractive and additive CAD/CAM technology. This study investigated the fracture load of crowns fabricated from three particle-filled composite CAD/CAM materials and one 3D-printed composite material. MATERIALS AND METHODS: Lava Ultimate, Cerasmart and Brilliant Crios were used as particle-filled composite CAD/CAM material and els-3D Harz as 3D-printed composite material. For each group, crowns with three different material thicknesses (0.5/1.0/1.5 mm) were fabricated. Control group was composed of ceramic-based CAD/CAM materials e.max CAD and Enamic. Totally, n = 180 crowns were fabricated and adhesively seated on SLA fabricated dies. Thermomechanical loading and fracture testing were performed. The data for fracture loading force were statistically analyzed by two-way ANOVA followed with multiple comparisons by post hoc Tukey's test (= 0.05). RESULTS: In contrast to ceramics, all particle-filled composite crowns with 0.5-mm thickness survived fatigue testing. Forces varied statistically significantly. Brilliant Crios showed highest maximum loading force with 1580.4 ± 521.0 N (1.5 mm). Two-way ANOVA indicated that both the material and the thickness affected the fracture load (p < 0.05). CONCLUSIONS: Particle-filled composite resin CAD/CAM materials may have advantageous material characteristics compared to ceramic CAD/CAM materials for minimal restoration thicknesses. CLINICAL RELEVANCE: Composite-based CAD/CAM materials may offer new possibilities in minimally invasive restorative treatment concepts.
International journal of computerized dentistry, 2013
The digital intraoral impression is a central part in today's CAD/CAM dentistry. With its pos... more The digital intraoral impression is a central part in today's CAD/CAM dentistry. With its possibilities, new treatment options for the patient is provided and the prosthetic workflow is accelerated. Nowadays, the major issue with intraoral scanning systems is to gain more accuracy especially for larger scan areas and to simplify clinical handling for the dentist. The aim of this study was to investigate different scanning strategies regardingtheir accuracy with full arch scans in an in-vitro study design. A reference master model was used for the digital impressions with the Lava COS, the Cerec Bluecam and a powderfree intraoral scanning system, Cadent iTero. The trueness and precision of each scanning protocol was measured. Lava COS provides the a trueness of 45.8 microm with the scanning protocol recommended from the manufacturer. A different scanning protocol shows significantly lower accuracy (trueness +/- 90.2 microm). Cerec Bluecam also benefits from an optimal scanning pr...
SUMMARY Clinical Relevance: Accurate reproduction of the jaw relationship is important in many fi... more SUMMARY Clinical Relevance: Accurate reproduction of the jaw relationship is important in many fields of dentistry. Maximum intercuspation can be registered with digital buccal scan procedures implemented in the workflow of many intraoral scanning systems. Objective: The aim of this study was to investigate the accuracy of buccal scan procedures with intraoral scanning devices for the registration of habitual intercuspation in vivo. The hypothesis was that there is no statistically significant difference for buccal scan procedures compared to registration methods with poured model casts. Methods and Materials: Ten individuals (full dentition, no dental rehabilitations) were subjects for five different habitual intercuspation registration methods: (CI) poured model casts, manual hand registration, buccal scan with inEOS X5; (BC) intraoral scan, buccal scan with CEREC Bluecam; (OC4.2) intraoral scan, buccal scan with CEREC Omnicam software version 4.2; (OC4.5β) intraoral scan, buccal ...
To evaluate the influence of cementation on fracture load of anterior crowns made of CAD/CAM-resi... more To evaluate the influence of cementation on fracture load of anterior crowns made of CAD/CAM-resin-blocks (ART), leucite-reinforced glass-ceramics (LRG), lithium disilicate ceramics (LIT), veneered zirconia (ZRO) and veneered alloy (DEG). Each crown group (n=15/ subgroup) was cemented on the metal abutment as follows: i. using glass ionomer, ii. using self-adhesive resin cement, and iii. not cemented. Crowns were tested and analyzed with 2-way and 1-way ANOVA (Scheffé test), and Weibull statistics (p<0.05). Within LRG, self-adhesive cemented subgroup showed higher fracture load compared to other groups (p<0.001). Among DEG, lower results were measured for non-cemented crowns than for cemented (p<0.001). For ART, LIT and ZRO no influence of cementation was observed. For fracture load test methodology, metal ceramic crowns should be generally cemented. Glass-ceramic crowns should be cemented using adhesive cement. Cementation and cement type did not have an influence on the fracture load results for resin, zirconia or lithium disilicate crowns.
In-vitro evaluation of the accuracy of conventional and digital methods of obtaining full-arch de... more In-vitro evaluation of the accuracy of conventional and digital methods of obtaining full-arch dental impressions
International journal of computerized dentistry, 2020
AIM Granuloma gravidarum (GG) is a benign lesion of the soft tissue. The aim of this technical no... more AIM Granuloma gravidarum (GG) is a benign lesion of the soft tissue. The aim of this technical note is the volumetric assessment and follow-up 3D measurement of a GG in the anterior maxilla. MATERIALS AND METHODS A 35-year-old female patient who was 7 months pregnant was referred due to a soft tissue tumor in the papilla of tooth 21. A biopsy verified a pyogenic granuloma gravidarum. Initial and consecutive volumeatric measurements were made with an intraoral scanner during the patient's pregnancy and until 16 months postpartum. RESULTS The volumetric assessment showed a continuous growth of the tumor and a consecutive volume reduction 16 months postpartum. In comparison with the level of the papilla of the contralateral incisor, there was an almost complete remission at the last follow-up. CONCLUSION Intraoral scans can serve for the volumetric assessment of soft tissue tumors of the alveolar crest. Image superimposition enables the quantification of changes in morphology. This...
The purpose of this in vitro study was to compare the time efficiency of digital chairside and la... more The purpose of this in vitro study was to compare the time efficiency of digital chairside and labside workflows with a conventional workflow for single-unit restorations. The time efficiency in this specific sense was defined as the time, which has to be spent in a dental office by a dental professional performing the relevant steps. A model with interchangeable teeth on position 36 was created. These teeth were differently prepared, responding to several clinical situations to perform single-unit restorations. Different manufacturing techniques were used: For the digital workflows, CEREC Omnicam (CER) and Trios 3 (TN/TI) were used. The conventional workflow, using a dual-arch tray impression technique, served as the control group. For the labside workflow (_L) and the conventional impression procedure (CO), the time necessary for the impressions and temporary restorations was recorded and served as operating time. The chairside workflow time was divided by the time for the entire ...
Objetivos: evaluar la resistencia a la fractura y los tipos de fracasos que surgen de las prepara... more Objetivos: evaluar la resistencia a la fractura y los tipos de fracasos que surgen de las preparaciones intrarradiculares cortas con un diseno en H modificado para la retencion de las restauraciones CAD/CAM (diseno asistido por ordenador/fabricacion asistida por ordenador), en los casos en los que no hay ferrule. Materiales y metodos: se realizo un analisis combinado de elementos finitos y una prueba in vitro. Se seleccionaron y se prepararon 40 premolares unirradiculares extraidos y se dividieron en los cuatro grupos siguientes (n = 10 por grupo): Grupo A, preparacion para el poste en forma de H restaurado con coronas de ceramica vitrea; Grupo B, preparacion para el poste en forma de H restaurado con coronas de disilicato de litio; Grupo C, endocrowns (grupo de control negativo) y Grupo D, preparacion de un ferrule de 2 mm y restauracion con postes de fibra (control positivo). Tras la cementacion, las muestras se cargaron en una maquina de pruebas universal hasta la fractura (1 mm/...
This in vitro study aimed to evaluate the fracture resistance of endodontically treated maxillary... more This in vitro study aimed to evaluate the fracture resistance of endodontically treated maxillary central incisors with different post systems. Methods: Fifty-six extracted intact maxillary permanent central incisors were used, treated endodontically (except for the control group), and distributed into the following seven test groups (n=8) depending on the post type: UHT (control group: root-filled teeth without endodontic post), ZRP (prefabricated zirconia post), GFP (prefabricated glass fiber post), CFP (prefabricated carbon fiber post), CPC (custom-made cast post and core), TIP (prefabricated titanium post), and MIP (prefabricated mixed post). The specimens were loaded in a universal testing machine until fracture occurrence. Failure loads were then analyzed with one-way analysis of variance (ANOVA), followed by multiple comparisons by using Tukey's honest significant difference test (α=0.05). Results: Mean (SD) failure loads for groups ranged from 524±73.2 N for CPC to 764.1±156 N for GFP. Oneway ANOVA showed significant differences in terms of fracture resistances among groups (P<0.001). Tukey's honest significant difference test showed significant differences in fracture resistance within groups (P≤0.05), whereas no difference was observed between the UHT (control group) and CFP and CPC groups (P≥0.05). Conclusion: Endodontically treated teeth restored with zirconia post, glass fiber post, titanium post, or mixed post were more resistant to fracture loads compared with those that were not restored (control group) or restored with either carbon fiber post or cast post and core.
In der heutigen Zeit werden Rekonstruktionen immer häufiger maschinell angefertigt. Die CAD/CAM-T... more In der heutigen Zeit werden Rekonstruktionen immer häufiger maschinell angefertigt. Die CAD/CAM-Technologie hat sich in der Zahnheilkunde, vor allem für die Verarbeitung von Zirkoniumdioxid etabliert. Mittlerweile werden industriell polymerisierte "Hochleistungskunststoffe" als CAD/CAM-Rohlinge angeboten. Daher können Provisorien nicht mehr länger nur nach den konventionellen Techniken, sondern auch maschinell hergestellt werden. Durch die industrielle Polymerisation unter hohem Druck, können die mechanischen Eigenschaften der Kunststoffe verbessert und optimiert werden. Auch die Ästhetik der CAD/CAM-gefertigten Provisorien ist mit der der manuell hergestellten Kunststoffprovisorien vergleichbar.
AimTo assess in vitro the workflow for alveolar ridge augmentation with customised 3D printed blo... more AimTo assess in vitro the workflow for alveolar ridge augmentation with customised 3D printed block grafts and simultaneous computer‐assisted implant planning and placement.MethodsTwenty resin mandible models with an edentulous area and horizontal ridge defect in the region 34–36 were scanned with cone beam computed tomography (CBCT). A block graft for horizontal ridge augmentation in the region 34–36 and an implant in the position 35 were digitally planned. Twenty block grafts were 3D printed out of resin and one template for guided implant placement were stereolithographically produced. The resin block grafts were positioned onto the ridge defects and stabilised with two fixation screws each. Subsequently, one implant was inserted in the position 35 through the corresponding template for guided implant placement. Optical scans of the study models together with the fixated block graft were performed prior to and after implant placement. The scans taken after block grafting were superimposed with the virtual block grafting plan through a best‐fit algorithm, and the linear deviation between the planned and the achieved block positions was calculated. The precision of the block fixation was obtained by superimposing the 20 scans taken after grafting and calculating the deviation between the corresponding resin blocks. The superimposition between the scans taken after and prior to implant placement was performed to measure a possible displacement in the block position induced by guided implant placement. The (98–2%)/2 percentile value was determined as a parameter for surface deviation.ResultsThe mean deviation in the position of the block graft compared to the virtual plan amounted to 0.79 ± 0.13 mm. The mean deviation between the positions of the 20 block grafts measured 0.47 ± 0.2 mm, indicating a clinically acceptable precision. Guided implant placement induced a mean shift of 0.16 ± 0.06 mm in the position of the block graft.ConclusionsWithin the limitations of this in vitro study, it can be concluded that customised block grafts fabricated through CBCT, computer‐assisted design and 3D printing allow alveolar ridge augmentation with clinically acceptable predictability and reproducibility. Computer‐assisted implant planning and placement can be performed simultaneously with computer‐assisted block grafting leading to clinically non‐relevant dislocation of block grafts.
International journal of computerized dentistry, 2017
STATEMENT OF PROBLEM Three-dimensional (3D) intraoral scanning systems allow for the simultaneous... more STATEMENT OF PROBLEM Three-dimensional (3D) intraoral scanning systems allow for the simultaneous acquisition of 3D information about tooth surfaces and a photorealistic view of the patient's tooth colors. AIM The goal of this study was the in vivo comparison of a new 3D scanner with a color acquisition mode and conventional visual and digital color measurements. MATERIALS AND METHODS The colors of 40 teeth of 20 patients were evaluated in seven ways: 1) By dentists using the Vita 3D-Master; 2) By dental technicians using the Vita 3D-Master; 3) With the 3Shape Trios device; 4) With the Vita Easyshade device; 5) With the Vita Easyshade Advance device; 6) With the SpectroShade device; and 7) With the SpectroShade Micro device. Digital measurements of Groups 3 to 7 were repeated three times for each tooth. For all groups, both the CIE Lab values and the Vita 3D-Master values were recorded. The repeatability and relative accuracy of the Vita 3D-Master values were analyzed statistically using Pearson's chi-squared test (α < 0.05). ΔE values were calculated from the CIE Lab values, which served as a basis for performing multidimensional scaling (MDS) and evaluating differences between the groups using the one-way ANOVA with post hoc Tamhane's test (α < 0.05). RESULTS The results of the ΔE values showed that clinically relevant differences between the evaluation by dentists, dental technicians, and the intraoral scanning device (3Shape) are negligible. The intraoral 3D scanning device (Group 3) and the digital systems (Groups 4 to 7) did not differ significantly in the repeatability of color shade management. The SpectroShade Micro (Group 7) had significantly better relative accuracy than the other devices. CONCLUSIONS The results demonstrate that intraoral scanning systems can be used to measure both tooth color and tooth surface in 3D. CLINICAL IMPLICATIONS Intraoral optical scanning devices allow for the acquisition of accurate 3D surface data. Tooth color can be evaluated simultaneously and can be used to determine the color of restorations without requiring additional conventional color-measurement methods.
Chairside sintering might be a suitable procedure to produce zirconia restorations with clinicall... more Chairside sintering might be a suitable procedure to produce zirconia restorations with clinically adequate fracture loading values for specific restoration thicknesses.
STATEMENT OF PROBLEM The use of computer-aided design and computer-aided manufacturing (CAD-CAM) ... more STATEMENT OF PROBLEM The use of computer-aided design and computer-aided manufacturing (CAD-CAM) technologies is widely established, with single restorations or short fixed partial dentures having similar accuracy when generated from digital scans or conventional impressions. However, research on complete-arch scanning of edentulous jaws is sparse. PURPOSE The purpose of this pilot in vitro study was to compare the accuracy of a digital scan with the conventional method in a workflow generating implant-supported complete-arch prostheses and to establish whether interference from flexible soft tissue segments affects accuracy. MATERIAL AND METHODS An edentulous maxillary master cast containing 6 angled implant analogs was used and digitized with mounted scan bodies by using a high-precision laboratory scanner. The master cast was then scanned 10 times with 4 different intraoral scanners: TRIOS 3 with a complete-arch scanning strategy (TRI1) or implant-scanning strategy (TRI2), TRIOS Color (TRC), CEREC Omnicam (CER), and CEREC Primescan (PS). The same procedure was repeated with 4 different levels of free gingiva (G0-G3). Ten conventional impressions were obtained. Differences in implant position and direction were evaluated at the implant shoulder as mean values for trueness and interquartile range (IQR) for precision. Statistical analysis was performed by using the Kruskal-Wallis and post hoc Conover tests (α=.05). RESULTS At G0, position deviations ranged from 34.8 μm (IQR 23.0 μm) (TRC) to 68.3 μm (12.2 μm) (CER). Direction deviations ranged from 0.34 degrees (IQR 0.18 degrees) (conventional) to 0.57 degrees (IQR 0.37 degrees) (TRI2). For digital systems, the position deviation ranged from 48.4 μm (IQR 5.9 μm) (PS) to 76.6 μm (IQR 8.1 μm) (TRC) at G1, from 36.3 μm (IQR 9.3 μm) (PS) to 79.9 μm (IQR 36.1 μm) (TRI1) at G2, and from 51.8 μm (IQR 14.3 μm) (PS) to 257.5 μm (IQR 106.3 μm) (TRC) at G3. The direction deviation ranged from 0.45 degrees (IQR 0.15 degrees) (CER) to 0.64 degrees (IQR 0.20 degrees) (TRC) at G1, from 0.38 degrees (IQR 0.05 degrees) (PS) to 0.925 degrees (IQR 0.09 degrees) (TRI) at G2, and from 0.44 degrees (IQR 0.07 degrees) (PS) to 1.634 degrees (IQR 1.08 degrees) (TRI) at G3. Statistical analysis revealed significant differences among the test groups for position (G0: P<.
International journal of computerized dentistry, 2013
Die digitale intraorale Abformung spielt eine zentrale Rolle in der modernen CAD/CAM-gestützten Z... more Die digitale intraorale Abformung spielt eine zentrale Rolle in der modernen CAD/CAM-gestützten Zahnmedizin. Sie ermöglicht neue Behandlungsoptionen für den Patienten und beschleunigt den Workflow bei der Restaurationsherstellung. Die wichtigste Aufgabenstellung bei einem intraoralen Scansystem besteht heutzutage darin, insbesondere in größeren Scanbereichen genauer zu arbeiten und die klinische Handhabung für den Zahnarzt zu vereinfachen. Ziel dieser Studie ist es, unterschiedliche Scanstrategien in vitro auf ihre Genauigkeit bei Scans des gesamten Zahnbogens zu untersuchen. Für die digitale Abformung mit den Systemen Lava COS, Cerec Bluecam und Cadent iTero wurde ein Referenzmeistermodell verwendet. Bei jedem Scanprotokoll wurden Richtigkeit und Präzision bestimmt. Lava COS lieferte dabei mit dem vom Hersteller empfohlenen Scanprotokoll eine Richtigkeit von 45,8 μm. Mit einem anderen Scanprotokoll ergab sich eine signifikant niedrigere Genauigkeit (Richtigkeit ± 90,2 μm). Auch bei Cerec Bluecam erweist sich ein optimales Scanprotokoll mit einer Richtigkeit von ± 23,3 μm im Vergleich zu ± 52,5 μm mit einem Standardprotokoll als vorteilhaft. Das puderfreie Cadent iTero Scansystem konnte den kompletten Zahnbogen mit einer Richtigkeit von ± 35,0 μm und einer Präzision
International journal of computerized dentistry, 2011
The digital intraoral impression has become a central part of the CAD/CAM technique. The objectiv... more The digital intraoral impression has become a central part of the CAD/CAM technique. The objective of the present study was to compare the accuracy (trueness and precision) of digital impressions of the full arch with that of conventional impressions on the in-vitro model. For this purpose, a master model was acquired with a new reference scanning process, the measuring trueness of which was +/- 4.1 microm and the precision +/- 2.5 microm. On the one hand, conventional impressions and then plaster models (n = 5) were produced from this master model, and on the other hand, digital impressions were made with the Cerec AC Bluecam and the Lava COS system (each n = 5). The plaster models were also scanned with the reference scanner. The available data records were superimposed and the differences determined. The deviation from the master model defines the trueness of the impression method. The deviations of the models among one another demonstrate the precision of the method. The trueness of the impressions was 55 +/- 21.8 microm in the conventional impression group, for digital impressions with Cerec Bluecam it was 49 +/- 14.2 microm and for digital impressions with Lava COS 40.3 +/- 14.1 microm. The precision was 61.3 +/- 17.9 microm for conventional impression with Impregum, 30.9 +/- 7.1 microm for digital impression with the Cerec Bluecam and 60.1 +/- 31.3 microm for digital impression with Lava COS. These in-vitro results show that accuracy of the digital impression is similar to that of the conventional impression. These results will have to be confirmed in further clinical studies.
The aim was to test whether or not soft tissue augmentation with a newly developed collagen matri... more The aim was to test whether or not soft tissue augmentation with a newly developed collagen matrix (CM) leads to volume gain in chronic ridge defects similar to those obtained by an autogenous subepithelial connective tissue graft (SCTG). MATERIAL AND METHODS: In six dogs, soft tissue volume augmentation was performed by randomly allocating three treatment modalities to chronic ridge defects (CM, SCTG, sham-operated control). Impressions were taken before augmentation (baseline), at 28, and 84 days. The obtained casts were optically scanned and the images were digitally analysed. A defined region of interest was measured in all sites and the volume differences between the time points were calculated. RESULTS: The mean volume differences per area between baseline and 28 days amounted to a gain of 1.6 mm (CM; SD+/-0.9), 1.5 mm (SCTG; +/-0.1), and a loss of 0.003 mm (control; +/-0.3). At 84 days, the mean volume differences per area to baseline measured a gain of 1.4 mm (CM; +/-1.1), 1.4 mm (SCTG; +/-0.4), and a loss of 0.3 mm (control; +/-0.3). The differences between CM and SCTG were statistically significant compared with control at 28 and 84 days (p<0.001). CONCLUSION: Within the limits of this animal study, the CM may serve as a replacement for autogenous connective tissue.
Journal of The Mechanical Behavior of Biomedical Materials, Jul 1, 2019
OBJECTIVES To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybri... more OBJECTIVES To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybrid materials bonded to dentin does differ from those of porcelain-fused-to metal or lithium disilicate glass ceramic crowns. MATERIAL AND METHODS In 80 human molars, occlusal tooth substance was removed so that the defects extended into dentin, simulating defects caused by attrition/erosion. Restorations at a standardized thickness of either 0.5 mm or 1.0 mm were digitally designed. For both thicknesses, 4 test groups (n = 10 per group) were defined, each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava Ultimate). Consecutively, the specimens were thermo-mechanically aged and then loaded until fracture. The load-bearing capacities (F) between the groups were statistically compared using the Kruskal-Wallis test (p < 0.05) and pairwise group comparison applying the Dunn's method. In addition, the results were compared to those of conventional lithium-disilicate ceramic crowns ("CLD") and to porcelain-fused to metal crowns ("PFM"). RESULTS The median F values for the 0.5 mm thin restorations were 1'350 N for 0.5-ZIR, 850 N for 0.5-LDC, 1'100 N for 0.5-HYC and 1'950 N for 0.5-COC. With CLD as the control, a significant difference was found between the groups 0.5-COC and 0.5-LDC (KW: p = 0.0124). With PFM as the control, the comparisons between PFM and 0.5-LDC as well as between 0.5-COC and 0.5-LDC were significant (KW: p = 0.0026). Median F values of 2'493 N in the group 0.5-ZIR, 1'165 in the group 0.5-LDC, 2'275 N in the group 0.5-HYC and 2'265 N in the group 0.5-COC were found. The medians of the F values for the 1.0 thick restorations amounted of 2'100 N in 1.0-ZIR, 1'750 N in 1.0-LDC, 2'000 N in 1.0-HYC and 2'300 N in 1.0-COC. Testing the multiple comparisons with Dunn's method no significant differences were found (p > 0.05). The median F values of the 1.0 mm thick restorations were: 2'489 N in the group 1.0-ZIR, 1'864 N in the group 1.0-LDC, 2'485 N in the group 1.0-HYC and 2'479 N in the group 1.0-COC. With CLD as the control group, a significant difference between zirconia and lithium-disilicate was found for the 0.5 (p = 0.0017) and 1.0 mm (p = 0.0320) thick specimens. Comparing the 0.5 mm thick specimens with CLD as the control, a significant difference was found between 0.5-HYC and 0.5-LDC (p = 0.0017). With PFM as the control, the comparison of lithium disilicate and zirconia was statistically significant for both thicknesses (p = 0.0009 for the 0.5 mm thick specimens; p = 0.0074 for the 1.0 mm thick specimens). In addition, with PFM as control group, significant differences were seen between 0.5-LDC and all other groups with restorations in 0.5 mm thickness (p = 0.0017). CONCLUSIONS Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic, hybrid materials or polymeric materials can be applied to correct occlusal tooth wear with exposed dentin and thus replace conventional crown restorations in cases of normally expected intraoral bite forces.
OBJECTIVES: Indirect CAD/CAM restorations can be fabricated using both subtractive and additive C... more OBJECTIVES: Indirect CAD/CAM restorations can be fabricated using both subtractive and additive CAD/CAM technology. This study investigated the fracture load of crowns fabricated from three particle-filled composite CAD/CAM materials and one 3D-printed composite material. MATERIALS AND METHODS: Lava Ultimate, Cerasmart and Brilliant Crios were used as particle-filled composite CAD/CAM material and els-3D Harz as 3D-printed composite material. For each group, crowns with three different material thicknesses (0.5/1.0/1.5 mm) were fabricated. Control group was composed of ceramic-based CAD/CAM materials e.max CAD and Enamic. Totally, n = 180 crowns were fabricated and adhesively seated on SLA fabricated dies. Thermomechanical loading and fracture testing were performed. The data for fracture loading force were statistically analyzed by two-way ANOVA followed with multiple comparisons by post hoc Tukey's test (= 0.05). RESULTS: In contrast to ceramics, all particle-filled composite crowns with 0.5-mm thickness survived fatigue testing. Forces varied statistically significantly. Brilliant Crios showed highest maximum loading force with 1580.4 ± 521.0 N (1.5 mm). Two-way ANOVA indicated that both the material and the thickness affected the fracture load (p < 0.05). CONCLUSIONS: Particle-filled composite resin CAD/CAM materials may have advantageous material characteristics compared to ceramic CAD/CAM materials for minimal restoration thicknesses. CLINICAL RELEVANCE: Composite-based CAD/CAM materials may offer new possibilities in minimally invasive restorative treatment concepts.
International journal of computerized dentistry, 2013
The digital intraoral impression is a central part in today's CAD/CAM dentistry. With its pos... more The digital intraoral impression is a central part in today's CAD/CAM dentistry. With its possibilities, new treatment options for the patient is provided and the prosthetic workflow is accelerated. Nowadays, the major issue with intraoral scanning systems is to gain more accuracy especially for larger scan areas and to simplify clinical handling for the dentist. The aim of this study was to investigate different scanning strategies regardingtheir accuracy with full arch scans in an in-vitro study design. A reference master model was used for the digital impressions with the Lava COS, the Cerec Bluecam and a powderfree intraoral scanning system, Cadent iTero. The trueness and precision of each scanning protocol was measured. Lava COS provides the a trueness of 45.8 microm with the scanning protocol recommended from the manufacturer. A different scanning protocol shows significantly lower accuracy (trueness +/- 90.2 microm). Cerec Bluecam also benefits from an optimal scanning pr...
SUMMARY Clinical Relevance: Accurate reproduction of the jaw relationship is important in many fi... more SUMMARY Clinical Relevance: Accurate reproduction of the jaw relationship is important in many fields of dentistry. Maximum intercuspation can be registered with digital buccal scan procedures implemented in the workflow of many intraoral scanning systems. Objective: The aim of this study was to investigate the accuracy of buccal scan procedures with intraoral scanning devices for the registration of habitual intercuspation in vivo. The hypothesis was that there is no statistically significant difference for buccal scan procedures compared to registration methods with poured model casts. Methods and Materials: Ten individuals (full dentition, no dental rehabilitations) were subjects for five different habitual intercuspation registration methods: (CI) poured model casts, manual hand registration, buccal scan with inEOS X5; (BC) intraoral scan, buccal scan with CEREC Bluecam; (OC4.2) intraoral scan, buccal scan with CEREC Omnicam software version 4.2; (OC4.5β) intraoral scan, buccal ...
To evaluate the influence of cementation on fracture load of anterior crowns made of CAD/CAM-resi... more To evaluate the influence of cementation on fracture load of anterior crowns made of CAD/CAM-resin-blocks (ART), leucite-reinforced glass-ceramics (LRG), lithium disilicate ceramics (LIT), veneered zirconia (ZRO) and veneered alloy (DEG). Each crown group (n=15/ subgroup) was cemented on the metal abutment as follows: i. using glass ionomer, ii. using self-adhesive resin cement, and iii. not cemented. Crowns were tested and analyzed with 2-way and 1-way ANOVA (Scheffé test), and Weibull statistics (p<0.05). Within LRG, self-adhesive cemented subgroup showed higher fracture load compared to other groups (p<0.001). Among DEG, lower results were measured for non-cemented crowns than for cemented (p<0.001). For ART, LIT and ZRO no influence of cementation was observed. For fracture load test methodology, metal ceramic crowns should be generally cemented. Glass-ceramic crowns should be cemented using adhesive cement. Cementation and cement type did not have an influence on the fracture load results for resin, zirconia or lithium disilicate crowns.
In-vitro evaluation of the accuracy of conventional and digital methods of obtaining full-arch de... more In-vitro evaluation of the accuracy of conventional and digital methods of obtaining full-arch dental impressions
International journal of computerized dentistry, 2020
AIM Granuloma gravidarum (GG) is a benign lesion of the soft tissue. The aim of this technical no... more AIM Granuloma gravidarum (GG) is a benign lesion of the soft tissue. The aim of this technical note is the volumetric assessment and follow-up 3D measurement of a GG in the anterior maxilla. MATERIALS AND METHODS A 35-year-old female patient who was 7 months pregnant was referred due to a soft tissue tumor in the papilla of tooth 21. A biopsy verified a pyogenic granuloma gravidarum. Initial and consecutive volumeatric measurements were made with an intraoral scanner during the patient's pregnancy and until 16 months postpartum. RESULTS The volumetric assessment showed a continuous growth of the tumor and a consecutive volume reduction 16 months postpartum. In comparison with the level of the papilla of the contralateral incisor, there was an almost complete remission at the last follow-up. CONCLUSION Intraoral scans can serve for the volumetric assessment of soft tissue tumors of the alveolar crest. Image superimposition enables the quantification of changes in morphology. This...
The purpose of this in vitro study was to compare the time efficiency of digital chairside and la... more The purpose of this in vitro study was to compare the time efficiency of digital chairside and labside workflows with a conventional workflow for single-unit restorations. The time efficiency in this specific sense was defined as the time, which has to be spent in a dental office by a dental professional performing the relevant steps. A model with interchangeable teeth on position 36 was created. These teeth were differently prepared, responding to several clinical situations to perform single-unit restorations. Different manufacturing techniques were used: For the digital workflows, CEREC Omnicam (CER) and Trios 3 (TN/TI) were used. The conventional workflow, using a dual-arch tray impression technique, served as the control group. For the labside workflow (_L) and the conventional impression procedure (CO), the time necessary for the impressions and temporary restorations was recorded and served as operating time. The chairside workflow time was divided by the time for the entire ...
Objetivos: evaluar la resistencia a la fractura y los tipos de fracasos que surgen de las prepara... more Objetivos: evaluar la resistencia a la fractura y los tipos de fracasos que surgen de las preparaciones intrarradiculares cortas con un diseno en H modificado para la retencion de las restauraciones CAD/CAM (diseno asistido por ordenador/fabricacion asistida por ordenador), en los casos en los que no hay ferrule. Materiales y metodos: se realizo un analisis combinado de elementos finitos y una prueba in vitro. Se seleccionaron y se prepararon 40 premolares unirradiculares extraidos y se dividieron en los cuatro grupos siguientes (n = 10 por grupo): Grupo A, preparacion para el poste en forma de H restaurado con coronas de ceramica vitrea; Grupo B, preparacion para el poste en forma de H restaurado con coronas de disilicato de litio; Grupo C, endocrowns (grupo de control negativo) y Grupo D, preparacion de un ferrule de 2 mm y restauracion con postes de fibra (control positivo). Tras la cementacion, las muestras se cargaron en una maquina de pruebas universal hasta la fractura (1 mm/...
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