Effect of Milling Speed on Surface Roughness and Marginal Adaptation of Zirconia Restorations
Abstract
Limited research has been published evaluating the effect of milling speed on the properties of zirconia restorations. Objective: The purpose of this study was to evaluate the effect of different milling speeds (super-fast, fine, extra-fine settings) of a milling unit (Primemill, Dentsply/Sirona) on the surface roughness (Sa), marginal gap, marginal gap volume, and marginal offset of zirconia restorations. Methods: A mandibular molar #30 typodont tooth (Kilgore) was digitally scanned (Primescan, Dentsply/Sirona) and an ideal crown preparation for a zirconia restoration was digitally created (exocad GmbH). A single master model die of the crown preparation was milled out of a layered fiberglass and resin material (Trinia, Bicon) using a five-axis milling unit (I-Mes, iCore). The master die was scanned (Primescan) and a final restoration was designed using the bio-copy feature of the typodont tooth. Ten restorations (Katana STML, Kuraray) were milled (Primemill) per each of the three milling speeds and sintered. The restorations and master die were loaded in a custom mounting jig. Surface roughness, marginal gap, marginal gap volume per 500-micron length, and marginal offset were measured using a non-contact profilometer (Confocal Profilometer, Keyence) separately at all four restoration surfaces (mesial, distal, facial, lingual). A mean of the combined four surface values were determined per property (n=40). Data were analyzed with one-way ANOVA and Tukey's post hoc tests per property (alpha=0.05). Results: Super-fast milling speed resulted in restorations with significantly greater surface roughness and marginal gap volume compared to fine and extra-fine milling speeds. No significant difference in marginal gap or marginal offset were found based on milling speed. Conclusions: Zirconia restorations milled at slower speeds may result in better properties compared to super-fast speed.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 22, 2023
- Accession Number
- AD1222427
Entities
People
- Adam J. Wallum
Organizations
- Uniformed Services University of the Health Sciences