Marta Revilla Leon M.S.D.

Revilla-León, M., Morillo, J.A., Att, W. and Özcan, M. (2020). “Chemical Composition, Knoop Hardness, Surface Roughness, and Adhesion Aspects of Additively Manufactured Dental Interim Materials.” J Prosthodont Dec 8. [Epub ahead of print].

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PURPOSE: To measure the chemical composition, Knoop hardness, surface roughness, and composite bond strength of additive manufactured (AM) and conventional interim materials. MATERIAL AND METHODS: Disks were prepared using conventionally (CNV group) and additively manufactured (AM group) materials: CNV-1 (Protemp 4; 3M ESPE), CNV-2 (Anaxdent new outline dentin; Anaxdent), AM-1 (FreePrint temp; Detax), AM-2 (E-Dent 400 C&B MFH; Envisiontec), AM-3 (NextDent C&B MFH; 3D Systems), and AM-4 (Med620 VEROGlaze; Stratasys). Each group was subdivided into 3 subgroups (n = 20) for analyzing Knoop hardness (KHN), chemical composition, superficial roughness (Ra), and composite shear bond strength. The first subgroup was exposed to a microhardness test. Subsequently, EDAX analysis was selected to analyze the chemical composition. The second subgroup was selected to measure the superficial roughness (Ra) using a contact profilometer. The third subgroup was used to measured composite shear bond strength using a universal testing apparatus. A digital microscope was used to analyze the fracture mode. The Shapiro-Wilk test showed normally distributed data. One-way ANOVA and post hoc Sidak tests were selected (α = 0.05). RESULTS: Major variances in chemical composition were observed among the specimens. Significant differences in Knoop hardness (p < 0.001) and surface roughness (p < 0.001) were detected. The AM-4 (13.45 ± 2.93 KHN), the CNV-2 (13.35 ± 5.84 KHN), the AM-2 (13.03 ± 3.29 KHN), and the AM-1 (12.55 ± 2.93 KHN) groups obtained the highest Knoop hardness values, followed by the AM-3 and the CNV-1 groups (p < 0.05). The AM-1 group (1.88 ± 1.11 Ra) obtained the highest surface roughness values among the groups, followed by the AM-3 group (0.90 ± 0.14 Ra) (p < 0.05). However, no significant differences in shear bond strength values were found between the groups ranging from 23.18 ± 8.88 MPa to 33.29 ± 9.17 MPa (p = 0.061). All the groups showed a cohesive mode of failure. CONCLUSIONS: The AM interim materials tested had significant chemical composition variations compared to conventional materials. For the mechanical properties evaluated, the AM materials obtained appropriate mechanical properties for use as an interim dental restoration. However, further studies are required to evaluate more extensively its mechanical properties and verify their applicability in the oral cavity, clinical behavior, and biocompatibility.

Pérez-Giugovaz, M.G., Mosier, M. and Revilla-León, M. (2021). “An additively manufactured intraoral scan body for aiding complete-arch intraoral implant digital scans with guided integration of 3D virtual representation.” J Prosthet Dent Jan 4;S0022-3913(20)30712-5. [Epub ahead of print].

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This article describes a polymeric additively manufactured intraoral scan body that facilitates a complete-arch intraoral implant digital scan and guides the superimposition procedures between the facial and digital scans comprising the patient’s 3D virtual representation. Furthermore, this novel intraoral scan body can be modified for the patient’s specific arch dimensions, enhancing patient comfort and facilitating digitizing.

Piedra-Cascón, W., Fountain, J., Att, W. and Revilla-León, M. (2021). “2D and 3D patient’s representation of simulated restorative esthetic outcomes using different computer-aided design software programs: A systematic review.” J Esthet Restor Dent Jan 5. [Epub ahead of print].

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OBJECTIVE: To review the techniques and available 2D and 3D computer-aided design (CAD) software programs to perform a diagnostic waxing for restorative procedures when cone beam computed tomography is not indicated. OVERVIEW: An electronic review was performed in Medline, Embase, and Scopus search engines. A manual search was also conducted. The articles evaluating methods to obtain a 2D or 3D patient’s representation for restorative dental procedures were included. A total of 33 articles were included for full text review. CAD programs provide the capability to integrate facial features from 2D photographs or 3D facial scans and facilitate facially driven digital diagnostic waxing procedures. Diagnostic and design tools varied among the programs, and multiple technique descriptions were found. However, the literature evaluating the accuracy of virtual patients and the perception variations between the 2D and 3D dimensional representations is limited. CONCLUSIONS: The integration of digital technologies into treatment planning procedures introduce variation into the conventional interfaces; however, the concepts remain the same. Further studies are needed to evaluate the accuracy of the virtual representations and the influence of the type of dimensional representation on the esthetic perceptions among dental professionals. CLINICAL SIGNIFICANCE: The 2D and 3D CAD software programs facilitate the integration of facial features into digital diagnostic waxing procedures; however, the esthetic perception of the patient’s virtual representation might vary among the different systems.

Mostafavi, D., Methani, M.M., Piedra-Cascón, W., Zandinejad, A. and Revilla-León, M. (2020). “Influence of the Rinsing Post-Processing Procedures on the Manufacturing Accuracy of Vat-Polymerized Dental Model Material.” J Prosthodont Nov 17. [Epub ahead of print.].

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PURPOSE: To evaluate the influence of rinsing solvents namely isopropyl alcohol (IPA) and tripropylene glycol monomethyl ether (TPM) and rinsing times (5-, 7-, 9-, and 11-minutes) of the post-processing procedures on the manufacturing accuracy of an additively manufactured dental model resin material. MATERIAL AND METHODS: The standard tessellation language (STL file) of the digital design of a bar (15×4×3 mm) was obtained. A resin dental material (E-Model Light; Envisiontec, Dearborn, Michigan) and a 3D printer (VIDA HD; Envisiontec, Dearborn, Michigan) were selected to manufacture all the specimens using the STL file following the recommended printing parameters at a room temperature of 23 °C. Two groups were generated based on the rinsing solvent used on the post-processing procedures namely isopropyl alcohol (IPA-group) and tripropylene glycol monomethyl ether (TPM-group). Each group was further divided in 4 subgroups (IPA-1 to IPA-4 and TPM-1 to TPM-4) depending on the rinsing time performed (5-, 7-, 9-, and 11-minutes). Twenty specimens per subgroup were fabricated. The dimensions (length, width, and height) of all the specimens were measured using a low force digital caliper (Absolute Low Force Caliper Series 573; Mitutoyo, Takatsu-ku, Kawasaki, Kanagawa). Each measurement was performed 3 times and the mean value determined. The volume of each specimen was calculated using the formula V=l×w×h. Shapiro-Wilk test revealed that the data were not normally distributed. Data were analyzed using Kruskal-Wallis (α = .05), followed by pairwise Mann-Whitney U tests (α = .0018). RESULTS: The IPA groups obtained significantly lower trueness and precision values compared with TPM groups (P<0.0018). Among the IPA groups, IPA-1 subgroup obtained the highest trueness and precision values compared to the rest of IPA subgroups. The TPM-1 and TPM-2 subgroups obtained the highest trueness and prevision values among the TPM group and among all the groups tested. No significant difference was found between the TMP-1 and TPM-2 subgroups (P>0.0018). CONCLUSIONS: None of the manufacturing workflows tested was able to manufacture a perfect match of the bar virtual design dimensions. TPM solvent group obtained higher trueness and precision values compared to the IPA solvent group. The IPA-1 subgroup that replicated the manufacturer´s recommendations obtained the highest manufacturing accuracy among the IPA subgroup. TPM solvent used in a rinsing ultrasonic bath between 4 and 3 minutes followed by a second ultrasonic clean bath between 3 and 2 minutes of the just printed vat polymerized dental model specimens obtained the highest manufacturing accuracy values.

Revilla-León, M., Subramanian, S.G., Att, W. and Krishnamurthy, V.R. (2020). “Analysis of Different Illuminance of the Room Lighting Condition on the Accuracy (Trueness and Precision) of An Intraoral Scanner.” J Prosthodont. Oct 23. [Epub ahead of print.].

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PURPOSE: To measure the influence of illuminance of the ambient light between 1000 lux (room light) and 10 000 lux (chair light) on the accuracy of an intraoral scanner (IOS). MATERIAL AND METHODS: A typodont was digitized using an extraoral scanner to obtain a reference standard tessellation language (STL) file. Ten groups were created based on the different illuminance of the ambient light conditions tested starting from 1000 lux (no chair light) to 10000 lux (chair light) in increments of 1000 lux by increasing the distance between the chair light and the mannequin, with the room light turned on. Ten digital scans per group were obtained (n = 10) using an IOS (Trios 3; 3Shape). The accuracy of the digital scans was evaluated with respect to the reference mesh of the typodont using a 3D mesh processing software. Kruskal-Wallis and pair-wise comparison tests were used to analyze the data (α = 0.05). RESULTS: Significant difference for trueness and precision values were found among the groups (p < 0.001). The 1000-lux group exhibited the lowest discrepancy values with a median of 26.33 μm and an interquartile range (IQR) of 40.04 μm (11.97-52.00) (p < 0.001); while the 5000-lux group obtained the highest discrepancy values with a median of 46.38 μm and an IQR of 99.94 μm (19.05-118.98) (p < 0.001). The pair-wise multi-comparison showed no difference between the 8000- and 4000-lux groups (p = 0.287). In all groups, the IQR was higher than the mean errors from the control mesh, suggesting that the relative precision was low. CONCLUSIONS: A 1000-lux illumination lighting condition is recommended to maximize the scanning accuracy of the IOS tested; the chair light should be avoided. Furthermore, the scanning accuracy response under the illuminance range tested presented a lack of monotonicity.