Effect of a new support design on the marginal and internal gap of additively manufactured interim crowns using direct light deposition technology

Authors

Leila Nasiry Khanlar, Department of Comprehensive Dentistry, College of Dentistry, Texas A&M University, Dallas, Texas, USA.
Claire Francis, Department of Comprehensive Dentistry, College of Dentistry, Texas A&M University, Dallas, Texas, USA.
Abdul Basir Barmak, Department of Comprehensive Dentistry, EIOH Medical Center, University of Rochester, Rochester, New York, USA.
Alma L. Salazar Rios, Department of Prosthodontics, College of Dentistry, Texas A&M University, Dallas, Texas, USA.
Reza Eftekhar Ashtiani, Department of Prosthodontics, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Amirali Zandinejad, Department of Comprehensive Dentistry, College of Dentistry, Texas A&M University, Dallas, Texas, USA.

Document Type

Article

Abstract

Abstract

Purpose: To investigate the design and location of supporting structures on the marginal and internal gap of interim restorations.

Materials and methods: A mandibular right first molar resin tooth was prepared for a full coverage crown and scanned using a laboratory scanner (3Shape D900). The scanned data were converted into standard tessellation language (STL) format and an indirect prosthesis was designed using computer-aided design (CAD) software (exocad DentalCAD). The STL file was used to fabricate a total of 60 crowns with a 3D printer (EnvisionTEC Vida HD). The crowns were printed using E-Dent C&B MH resin and divided into 4 groups based on four different support structure designs, including supports on the occlusal (0° group), buccal and occlusal (45° group), buccal (90° group), and a new design consisting of horizontal bars placed on all surfaces and line angles (Bar) (n = 15). The silicone replica technique was used to determine the gap discrepancy. Fifty measurements were obtained for each specimen to examine the marginal and internal gaps by using a digital microscope (Olympus SZX16) at ×70 magnification. Additionally, the marginal discrepancy at different locations of the tested crowns, including buccal (B), lingual (L), mesial (M), and distal (D), as well as the maximum and minimum marginal gap intervals among groups, were analyzed. The collected data were analyzed using factorial ANOVA, followed by the Tukey HSD test for multiple comparisons (a = 0.05).

Results: There was a significant difference in marginal and internal gaps among the groups (p < 0.001). The buccal placement supports (90° group) had the least marginal and internal discrepancies (p < 0.001). The new design group showed the highest marginal and internal gap. The marginal discrepancy in different locations of the tested crowns (B, L, M, D) was found to be significantly different among the groups (p < 0.001). The mesial margin of the Bar group had the largest marginal gap, whereas the buccal margin of the 90° group had the lowest marginal gap. The new design had a significantly smaller difference between the maximum and minimum marginal gap intervals than other groups (p < 0.001).

Conclusion: The location and design of the supporting structures affected the marginal and internal gaps of an interim crown. The buccal placement of supporting bars (90° printing orientation) showed the smallest mean internal and marginal discrepancies.

First Page

188

Last Page

194

DOI

10.1111/jopr.13668

Publication Date

2-2024

Comments

Khanlar, L. N., Francis, C., Basir Barmak, A., Rios, A. L. S., Ashtiani, R. E., & Zandinejad, A. (2024). Effect of a new support design on the marginal and internal gap of additively manufactured interim crowns using direct light deposition technology. Journal of prosthodontics: official journal of the American College of Prosthodontists, 33(2), 188–194.

https://doi.org/10.1111/jopr.13668

Accepted Version

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Recommended Citation

Khanlar, L. N., Francis, C., Basir Barmak, A., Rios, A. L. S., Ashtiani, R. E., & Zandinejad, A. (2024). Effect of a new support design on the marginal and internal gap of additively manufactured interim crowns using direct light deposition technology. Journal of prosthodontics: official journal of the American College of Prosthodontists, 33(2), 188–194.