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Stereolithography (SLA) additive manufacturing (AM) technique has enabled the production of inconspicuous and aesthetically pleasing orthodontics that are also hygienic. However, the staircase effect poses a challenge to the application of invisible orthodontics in the dental industry. The purpose of this study is to implement chemical postprocessing technique by using isopropyl alcohol as a solvent to overcome this challenge.

Fifteen experiments were conducted using a D-optimal design to investigate the effect of different concentrations and postprocessing times on the surface roughness, material removal rate (MRR), hardness and cost of SLA dental parts required for creating a clear customized aligner, and a container was constructed for chemical treatment of these parts made from photocurable resin.

The study revealed that the chemical postprocessing technique can significantly improve the surface roughness of dental SLA parts, but improper selection of concentration and time can lead to poor surface roughness. The optimal surface roughness was achieved with a concentration of 90 and a time of 37.5. Moreover, the dental part with the lowest concentration and time (60% and 15 min, respectively) had the lowest MRR and the highest hardness. The part with the highest concentration and time required the greatest budget allocation. Finally, the results of the multiobjective optimization analysis aligned with the experimental data.

This paper sheds light on a previously underestimated aspect, which is the pivotal role of chemical postprocessing in mitigating the adverse impact of stair case effect. This nuanced perspective contributes to the broader discourse on AM methodologies, establishing a novel pathway for advancing the capabilities of SLA in dental application.

Parts created with fused deposition modelling (FDM) have poor surface quality and dimensional accuracy, which limits their applicability in a variety of applications. Therefore, post process of FDM parts seems to be essential to tackle these problems. The purpose of this study is to study the influence of lapping parameters (time, weight and angular velocity) on the surface roughness, material removal rate (MRR) and flexural strength of acrylonitrile butadiene styrene (ABS) parts manufactured by FDM were post processed with the aid of lapping operation.

After printing the specimens, parts were lapped according to the Taguchi design of experiments. The surface roughness of the lapped parts was then evaluated by using laser profilometry, and the results were compared to study how lapping parameters affected surface roughness. A digital microscope was used to examine the surface damage of components that were being lapped. After that, the flexural strength of lapped parts was compared with the untreated part to study the effect of lapping process on the flexural strength. Finally, the influence of lapping parameters was investigated on the thickness change and MRR.

The results showed that while by increasing lapping time the surface roughness would improve; angular velocity and weight have an optimal value. The results also illustrated that not only the surface roughness of all ABS samples improve significantly but also the antistrophic behaviour of additively manufactured parts is turned to isotropic behaviour without decreasing flexural strength of specimens. MRR is also proportional to these parameters and by rising the value of them, MRR will increase.

The previous techniques of improving surface roughness whether chemical treatment or mechanical treatment had some disadvantages such as reducing mechanical properties, cost, long time of the process and so forth. As a result, finding a new approach such as lapping process to overcome the problems of previous methods seems to be necessary.