Evaluation of Internal Fit in Custom-Made Posts and Cores Fabricated with Fully Digital Versus Conventional Techniques

Abstract

Objective: This study aimed to assess and compare the internal fit of custom-made posts and cores fabricated using digital impressions (DI) and conventional vinyl polysiloxane (VPS) impressions in restorative dentistry.

Materials and methods: A typodont tooth model, simulating the anatomy of the root canal of a central incisor, was utilized for the study. Two groups were formed, Group A and Group B, and each group provided a total of 18 impressions of two types: DIs and VPS impressions. In Group A, posts and cores (PCs) were fabricated using Selective Laser Melting (SLM) from the DIs. Meanwhile, in Group B, conventionally cast (CC) PCs were created from the VPS impressions. Silicone replicas of the internal surfaces were produced, and measurements were made at seven different points for each group. A statistical analysis was performed to assess the differences in internal fit between the two impression techniques.

Results: The results revealed a statistically significant difference in mean internal fit between Group A (DI and SLM) and Group B (VPS and CC), with Group A exhibiting a mean internal fit of 182.6 µm and Group B showing a mean of 205.9 µm. While both groups demonstrated considerable variability in internal fit measurements, the digital impression technique showed promise for achieving superior internal fit, with a significantly greater fit for measuring points on sides and the most apical part of the post for Group A. Variations were observed across different measuring points, emphasizing the impact of impression technique on specific regions within the tooth.

Conclusion: This study contributes to the growing body of knowledge in digital dentistry by highlighting the potential benefits of DIs in achieving a superior internal fit for custom-made PCs. Clinicians may consider the advantages of digital techniques to enhance the precision of their restorative procedures, although further research is warranted to evaluate the clinical impact of these findings.

Keywords: computer-aided design; dental fit; dental impression technique; digital dental technology; post-and-core technique; vinyl polysiloxane.

Figure 1

Showing the distribution of measuring points (1 is buccal and 7 is lingual in Table 1 and 1 is mesial and 7 is distal in Table 2).

Figure 2

A photograph of the master model and one of the post and core specimens has been included to visually represent the experimental setup and fabrication process.

Figure 3

(a) Showing internal gaps between Group A and B in bucco-lingual sectioned replicas. (b) Showing internal gaps between Group A and B in mesiodistally sectioned replicas. (c) Showing mean internal gaps for both buccolingual and mesiodistal values. (Statistically significant differences are marked *, p < 0.05).

Figure 3

(a) Showing internal gaps between Group A and B in bucco-lingual sectioned replicas. (b) Showing internal gaps between Group A and B in mesiodistally sectioned replicas. (c) Showing mean internal gaps for both buccolingual and mesiodistal values. (Statistically significant differences are marked *, p < 0.05).