Marginal and internal fit of provisional crowns fabricated using 3D printing technology

Abstract

BACKGROUND:

Clinicians routinely provide provisional crowns following teeth preparation. Three-dimensional (3D) printing technology could be used over conventional methods for better fit as lack of adequate fit would result in plaque accumulation, micro-leakage, teeth sensitivity, caries and periodontal diseases.

OBJECTIVE:

The aim of the study was to evaluate the marginal and internal fit of provisional crowns fabricated using 3D printing technology and to compare it with that of compression molding and milling methods.

METHODS:

Ninety study models were fabricated by duplicating metal master models of the maxillary first premolar molar with three different finish line chamfer, rounded shoulder and rounded shoulder with bevel. On each study model, provisional crowns were fabricated using compression molding (Mo. group, $n=$ 30 – by over impression technique), milling (Mi. group, $n=$ 30 – by 5-axis dental milling machine), and 3D printing method (3D-P. group, $n=$ 30 – by 3D printer). Marginal and internal fit of the samples were evaluated by measuring gap using a scanning electron microscope with a magnification of 27 $\times$ , at 7 zones A–G on different finish line models. The data were statistically analysed using one-way analysis of variance (ANOVA) at the 0.05 significance level. The $p$ -values were calculated using Dunnett’s test.

RESULTS:

The marginal gap was minimal for the 3D-P. group for each finish line with lowest for rounded shoulder with bevel at zone A 30.6 $\pm$ 5.3 and at zone G 32.8 $\pm$ 5.4. In axial area, i.e. zones B and F, the minimum gap was noticed for the Mo. group and in Occlusal area (cusp and fossa), for zones C–E maximum gap was determined in Mi. group followed by Mo. and 3D-P. groups.

CONCLUSIONS:

3D printed provisional crowns have better marginal and internal fit compared to milled and molded provisional crowns.