# Assessing the Color and Surface Characteristics of Additively Fabricated Denture Base Resins Containing Nanoparticles

## TL;DR

This study examines how adding nanoparticles affects the color and surface properties of 3D-printed denture materials after thermal stress.

## Contribution

The study introduces a novel analysis of nanoparticle effects on color stability and surface properties in additively manufactured denture resins.

## Key findings

- Nanodiamonds increased color change in NextDent resins compared to silicon dioxide nanoparticles.
- NextDent with 0.5% silicon dioxide nanoparticles showed the highest hardness and lowest surface roughness.
- Material type and nanoparticle type significantly influenced surface properties and color stability.

## Abstract

Objective: To investigate and compare the impact of different nanoparticles (NPs) on the color stability and surface properties of additively fabricated (AF) denture base resins after thermal cycling.

Materials and Methods: Two hundred specimens (n = 10) were AF from NextDent and ASIGA denture base resins. Specimens were divided into four groups according to the added NP's type and concentration: nanodiamond (ND; 0.25% and 0.5%), silicon dioxide NPs (NS; 0.25% and 0.5%), and a control group of pure resin of each material. The color change (∆ELab), surface roughness, and hardness were tested after thermal cycling (5000 cycles). Data were analyzed using ANOVA and post hoc Tukey's tests (α = 0.05).

Results: The ∆ELab was affected by the NP type and material type, while the NPs concentration showed no effect. ND showed higher ∆ELab with NextDent in all groups (p  < 0.05) in comparison to NS. Color change of ASIGA with ND and NS was higher than that of NextDent, ∆ELab values of all tested groups were below 3.7 NBS. For NextDent, 0.5% NS showed significantly the highest hardness values (25.9 ± 4.6 VHN) followed by 0.5% ND (18.7 ± 2.4 VHN). For hardness, NextDent 0.5% NS showed significant increase when compared with ASIGA (p  < 0.001). For roughness, NextDent 0.5% NS showed significantly less Ra than other groups. In term of materials comparison per NP type, significant differences in Ra between ASIGA and NextDent was detected.

Conclusions: The effect of NP on the tested properties is concentration dependent and material dependent therefore, NP type, NP concentrations, and material type selection should be considered for AF nanocomposite denture base fabrication.