Korean J Dent Mater.  2019 Sep;46(3):153-164. 10.14815/kjdm.2019.46.3.153.

Comparison of marginal and internal discrepancies of zirconia crowns fabricated by various digital scan methods

Affiliations
  • 1Department of Prosthodontics, School of Dentistry, Wonkwang University, Iksan, Korea. pro11@wku.ac.kr
  • 2Central Dental Laboratory, Wonkwang University Dental Hospital, Iksan, Korea.

Abstract

In this study, marginal and internal discrepancies of zirconia crowns fabricated with the CAD/CAM (computer aided design - computer aided manufacturing) system were compared. Digital impressions were obtained using model scan (MS), impression scan (IS), oral scan (OS) and dental CT scan (CT). The left mandibular first molar resin tooth was prepared as occlusal 2 mm, axial 1 mm reduction with convergence angle of 6 degree and shoulder margin. After fifteen scan procedures per group, each fifteen zirconia crowns were fabricated. The marginal and internal discrepancies of the crowns were measured using a silicone replica technique with a light body silicone impression material. The replica specimens were sectioned buccolingually and mesiodistally and then examined using a microscope ×160 magnification. The data were statistically analyzed with one-way ANOVA and post-hoc was Duncan's multiple test (α=0.05). Mean marginal discrepancies of zirconia crowns were significantly lower in OS group and MS group than in IS group and CT group. Mean cervical discrepancies were a statistically significant difference (p<0.05) in the OS group compared to the other groups (p<0.05). The CT group and the MS group did not show any significant difference (p>0.05). The IS group showed the lowest axial discrepancies and the MS group showed the greatest statistically significant difference (p<0.05). There was no significant difference between the OS group and the CT group (p>0.05). The occlusal discrepancies were the lowest in OS group and the largest in CT group, indicating a significant difference (p<0.05). The MS group showed no statistically significant difference from the OS group and the IS group. The marginal discrepancies and cervical discrepancies of the zirconia crowns were lowest in the OS group and the axial discrepancies were lowest in the IS group. All groups except the CT group were within the clinically acceptable range.

Keyword

Dental CT; Internal discrepancies; Marginal discrepancies; Model scanner; Oral scanner; Zirconia crown

MeSH Terms

Crowns*
Methods*
Molar
Replica Techniques
Shoulder
Silicon
Silicones
Tomography, X-Ray Computed
Tooth
Silicon
Silicones
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