Internal and marginal adaptation of 3D printed interim fixed partial dentures with different layer thicknesses.

Abstract

Purpose: The aim of this study was to compare the marginal and internal adaptation of polymethyl methacrylate interim fixed partial denture (FPD) restorations fabricated by three-dimensional (3D) printing with different layer thicknesses.

Materials and methods: A standard typodont was scanned by a laboratory scanner. The maxillary left first premolar and first molar teeth received an all-ceramic full-coverage crown preparation, and the second premolar was removed to create a pontic space. The prepared teeth were then scanned, and metal dies were fabricated by a milling machine. Restorations were designed and fabricated in 3 groups (n = 12 in inch) with 25, 50 and 100 µm layer thicknesses. The marginal and internal gaps were measured by the replica technique. Data were analyzed by one-way ANOVA (α = 0.05).

Results: The mean gap size (MGS) in the cervical area of premolar restorations was significantly higher in 100 µm than in 50 and 25 µm thicknesses (P < .05). The MGS in the marginal area of premolar restorations was significantly higher in 100 µm thickness than in 50 µm thickness (P < .05), with no statistically significant difference with 25 µm thickness (P > .05). The MGS at the occlusal and cervical areas of the molar restorations was significantly higher in 100 µm thickness than in 50 µm thickness (P < .05), with no statistically significant difference with 25 µm thickness (P > .05).

Conclusion: Different thicknesses of additive layers in 3D printing affected the marginal and internal gaps. The smallest gap size was recorded in 50 µm layer thickness.