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. 2021 Apr 30;7(4):e06896.
doi: 10.1016/j.heliyon.2021.e06896. eCollection 2021 Apr.

Evaluating the effect of repeated use of milling burs on surface roughness and adaptation of digitally fabricated ceramic veneers

Leila Payaminia  1 , Naeime Moslemian  2 , Shima Younespour  3 , Soudabeh Koulivand  4 , Marzieh Alikhasi  1
Affiliations

Evaluating the effect of repeated use of milling burs on surface roughness and adaptation of digitally fabricated ceramic veneers

Leila Payaminia et al. Heliyon. .

Abstract

Objectives: This study aimed to evaluate how repeated use of milling diamond burs with different coarseness affects surface roughness, and marginal and internal adaptation of CAD/CAM veneers.

Methods: Forty leucite-reinforced glass-ceramic veneers were milled in 2 groups based on the milling mode (with fine or extra-fine bur sets). In each group, every 10 veneers were milled with a new bur set. All veneers were cemented to bovine teeth and then polished. Labial surface roughness was measured before cementation, and after polishing. Marginal and internal discrepancies were measured using a field emission scanning electron microscope. Three-way and two-way mixed repeated measures ANOVA were applied to assess changes in surface roughness values of veneers and discrepancy values, respectively. The Bonferroni correction was applied for multiple comparisons.

Results: Repeated use of a milling diamond bur set had a significant effect on surface roughness of the veneers (P < .001). Mean surface roughness of the fine milling mode was significantly higher in comparison to that of extra-fine mode before (P = .002) and after (P = .01) polishing. After polishing a significant decrease in surface roughness occurred in fine (P = .02), but not in extra-fine milling mode (P = .99). Repeated use of milling burs significantly affected marginal and internal adaptation between some repeated uses.

Conclusions: Marginal and internal adaptation were significantly affected by repeated use of milling diamond burs up to 10 times between some repeated uses. However, no specific pattern could be established.

Clinical significance: Repeated use of milling burs could affect surface roughness, surface microcracks, critical defects, and adaptation of CAD/CAM restorations. Therefore, it plays a major role in clinical success of the restorations.

Keywords: CAD/CAM; Dentistry; Marginal adaptation; Prosthodontics; Repeated milling; Surface roughness; Veneer.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flowchart of study design. A, fine group. B, extra-fine group.
Figure 2
Figure 2
Field emission scanning electron microscope image analysis of a sectioned specimen at ×200 magnification.
Figure 3
Figure 3
A schematic picture showing AMD, MD and ID.
Figure 4
Figure 4
Mean surface roughness and standard error values (μm) before and after polishing in both milling modes during repeated use of the burs. A, fine group. B, extra-fine group.
Figure 5
Figure 5
Mean surface roughness and standard error values (μm) before and after polishing in both milling modes.
Figure 6
Figure 6
Discrepancy values (μ) in both milling modes during repeated use of the burs. A, cervical vertical discrepancy. B, cervical absolute discrepancy. C, internal discrepancy. D, incisal vertical discrepancy.
See this image and copyright information in PMC

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