Marta Revilla Leon M.S.D.

Revilla-Leon, M., L. Raney, W. Piedra-Cascon, J. Barrington, A. Zandinejad and M. Ozcan (2020). “Digital workflow for an esthetic rehabilitation using a facial and intraoral scanner and an additive manufactured silicone index: A dental technique.” J Prosthet Dent 123(4): 564-570.

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The present article describes a digital workflow for planning an esthetic treatment by using a facial and intraoral scanner, the dental and open-source software design of a facially generated diagnostic waxing, and additive manufactured (AM) clear silicone indices. A virtual design was created to fabricate a unique 3-piece AM index composed of flexible, clear silicone at the labial and lingual aspects and a rigid clear custom tray. The 3-piece AM clear indexes provided advantages compared with conventional procedures, including accurate reproduction of the digital diagnostic waxing, control of index thickness, various insertion paths of the silicone indices, flexibility of the indices, and online storage of the designs.

Park, S. H., W. Piedra-Cascon, A. Zandinejad and M. Revilla-Leon (2020). “Digitally Created 3-Piece Additive Manufactured Index for Direct Esthetic Treatment.” J Prosthodont Mar 6. [Epub ahead of print].

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Facial and intraoral scanners as well as additive manufacturing (AM) technologies can be integrated to virtually plan restorative procedures. The present article describes a digital workflow protocol for treatment planning an esthetic rehabilitation using direct composite restorations. The combination of facial digitalization and intraoral scans allowed a facially driven diagnostic waxing, while additive manufacturing technologies facilitate the translation of the digital waxing into the patient s mouth through an AM 3-piece silicone index which was designed into a buccal and a lingual clear flexible silicone indices that were fitted into a clear and rigid custom tray. This procedure facilitated the treatment planning procedures as well as assisted the direct composite restoration procedures, providing several advantages compared with conventional procedures such as precise translation of the digital diagnostic waxing into the patient s mouth, horizontal path of insertion of the silicone index, and minimized time of the clinical intervention.

Methani, M. M., Revilla-Leon, M. and Zandinejad, A. (2020). “The potential of additive manufacturing technologies and their processing parameters for the fabrication of all-ceramic crowns: A review.” J Esthet Restor Dent 32(2): 182-192.

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OBJECTIVE: This article aims to provide a review of the additive manufacturing technologies and the processing parameters that have been investigated for the fabrication of all ceramic crowns. OVERVIEW: Additive manufacturing has crept its way into the field of dentistry for the fabrication of resin and metal prosthesis. To evaluate the current status of additive manufacturing for the fabrication of all ceramic crowns, literature review was targeted to include publications pertaining to the fabrication of dental ceramics and all ceramic crowns. With respect to the additive manufacturing of dental ceramics, five technologies have been investigated to date: stereolithography, material extrusion, powder based fusion, direct inkjet printing, and binder jetting. The processing parameters and experimental outcomes were collated and described for each of the aforementioned technologies. CONCLUSION: Additive manufacturing has demonstrated promising experimental outcomes and corroborated to the fabrication all ceramic crowns. However, the technology is yet to witness a commercial breakthrough within this domain. CLINICAL SIGNIFICANCE: Additive manufacturing mitigates raw material wastage and tooling stresses that are associated with milling of ceramics. Continued research and development can lead to its approbation as an alternate technology for manufacturing all ceramic restorations.

Revilla-Leon, M., Methani, M. M., Morton, D. and Zandinejad, A. (2020). “Internal and marginal discrepancies associated with stereolithography (SLA) additively manufactured zirconia crowns.” J Prosthet Dent Jan 21. [Epub ahead of print].

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STATEMENT OF PROBLEM: Stereolithography (SLA) additive manufacturing (AM) technologies can be selected to fabricate zirconia crowns; however, the internal and marginal discrepancies associated with these new technologies remain unclear. PURPOSE: The purpose of this in vitro study was to measure and compare the marginal and internal discrepancies of milled and AM zirconia crowns by using the silicone replica technique. MATERIAL AND METHODS: An implant custom abutment was manufactured and scanned by using a laboratory scanner (CARES Software; Straumann). An anatomic contour crown was digitally designed, and the standard tessellation language (STLC) file was obtained. The STLC file was splinted into 2 pieces, simulating the parts of the crown that would replace the enamel (STLG1 file) and dentin (STLG2 file) structures. Three groups were determined: anatomic contour zirconia milled (CNC group), AM anatomic contour zirconia (AM group), and AM splinted zirconia (SAM group). For the CNC group, the STLC file was used to manufacture milled (CARES zirconium-dioxide crown; Straumann) zirconia specimens. For the AM group, the STLC file was used to additively fabricate (CERAMAKER 900; 3DCeram Co) the zirconia (3DMix ZrO2 paste; 3DCeram Co) specimens. For the SAM group, the STLG2 file was selected to AM (CERAMAKER 900; 3DCeram Co) the zirconia (3DMix ZrO2 paste; 3DCeram Co) specimens. Ten specimens per group were manufactured. The silicone replica technique was used to measure the marginal and internal discrepancies. The cement gap was measured on images captured by using a digital microscope at x100 magnification. For the internal gap, 50 measurements were made for each specimen, and for the marginal gap, 25 measurements were made for each specimen. The normality test, Shapiro-Wilk test, was conducted. The results indicated that the distributions were not normal; therefore, nonparametric Kruskal-Wallis H and pairwise Mann-Whitney U-tests were used to analyze the data. The Spearman correlation coefficient was used to determine the correlation between marginal and internal discrepancies in all 3 groups. RESULTS: Significant differences were found in marginal and internal discrepancies among the groups. The CNC group had the least marginal and internal discrepancies compared with the AM and SAM groups. The SAM group had significantly lower values for marginal and internal discrepancies than the AM group. The AM group showed the highest marginal and internal discrepancies. The CNC group had a weak correlation coefficient of 0.13 (P=.046), the AM group had a moderate correlation coefficient of 0.32 (P<.001), and the SAM group had a nonsignificant correlation coefficient of 0.12 (P=.051). CONCLUSIONS: CNC and SAM groups had clinically acceptable marginal and internal discrepancies, while the AM group had a clinically unacceptable marginal and internal crown discrepancies. Furthermore, a weak correlation was encountered between the marginal and internal discrepancies measured in all groups.

Revilla-Leon, M., Campbell, H. E., Meyer, M. J., Umorin, M., Sones, A. and Zandinejad, A. (2020). “Esthetic dental perception comparisons between 2D- and 3D-simulated dental discrepancies.” J Prosthet Dent Jan 22. [Epub ahead of print].

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STATEMENT OF PROBLEM: Intraoral scanners (IOSs), facial scanners (FSs), and computer-aided design (CAD) software programs have become powerful tools for treatment planning. However, discrepancies in perception regarding 2-dimensional (2D) or 3-dimensional (3D) simulations by dentists, dental students, and laypeople have not been analyzed. PURPOSE: The purpose of this observational study was to analyze the perceptions of laypersons, dental students, and dentists regarding disparities of the maxillary dental midline and the occlusal plane when analyzing the dental discrepancies on 2D- and 3D-clinical simulations. MATERIAL AND METHODS: A female model was digitized by using an FS, IOS, and a full-face smile photograph. Dental discrepancies were simulated by using a 2D photograph (2D group) and 3D scan (3D group) of the model. In both simulation groups, 2 subgroups were produced. The occlusal plane of the first subgroup was modified in 1-degree increments without changing the dental midline or the position of the maxillary dental incisors. In the second subgroup, the occlusal plane was modified by using the same increments, but the maxillary central incisors and dental midline were altered to match the inclination of the occlusal plane. A total of 300 participants (N=300) were asked to rate the 2D images (N=12) and 3D videos (N=12) on a 1-to-6 scale and answer a questionnaire. Ordinal logistic regression was used to analyze the ratings. RESULTS: The ratings decreased with the increased tilt of the occlusal plane, and the layperson group gave consistently higher ratings than the other 2 groups. For dentists, the odds of giving a higher versus lower rating decreased by almost a half for each degree of tilt. However, for students, that effect was diminished by a positive interaction term, and for laypersons, the effect was even less. Students gave similar ratings to dentists, but laypersons gave higher ratings. As the age of the participants increased, however, the ratings also increased. The use of 3D versus 2D images had a positive effect on the ratings, but the effect decreased for the student observers and decreased even further for laypersons. Furthermore, midline alteration led to higher ratings but also resulted in worsening of the odds ratio for the tilt. Seventy percent of the dentists, 57% of the dental students, and 52% of the laypersons preferred 2D simulations to 3D simulations. CONCLUSIONS: Dentists, dental students, and laypersons decreased their ratings with increased inclination of the occlusal plane; however, laypersons still graded all the 2D and 3D images as esthetically pleasant, giving consistently higher ratings than the dentists and dental students. Overall, 3D simulations obtained higher ratings than 2D images, but the positive effect decreased for the student observers and decreased even further for laypersons.