Impact of different post-curing conditions on the marginal fit of 3D printed temporary crowns

OBJECTIVES: Marginal integrity is one of the most important factors in assessing whether a preliminary restoration is successful. A leak in the margin can cause problems of sensitivity, food lodgement and secondary caries which possibly lead to discomfort and/or destruction of the tooth structure under the restoration. Conventional methods of producing temporary restorations may subject the affected tooth to chemical and thermal risks. 3D printing technology provides an alternative for making temporary restorations. Expanding the marginal gap due to polymerization shrinkage is a prevalent issue with 3D printed resins. The quantity of polymerization shrinkage in 3D printed resins may change if the post-curing conditions are changed. This study aimed to evaluate how various post-curing parameters of temperature and time affect the marginal fit of temporary crowns made with 3D printed resins.

MATERIALS AND METHODS: The study was approved by the Institutional Human Ethical Committee of Saveetha Dental College (Ref No. IHEC/SDC/PROSTHO- 2005/21/015; approved on 15 February 2021). The committee follows the New Drugs and Clinical Trials Rules 2019 and adheres to ICH-GCP guidelines. A typical crown was created for a typodont right mandibular tooth. The examples were 3D printed using a stereolithography 3D printer. After that, the samples were put through three distinct post-curing scenarios. Eight distinct sites on each sample – the buccal, lingual, medial, distal, mesiobuccal, mesiolingual, distobuccal, and distolingual surfaces – were used to assess the marginal fit of the provisional crowns.

RESULTS: Overall, the mean marginal gap in the three groups under study were in the range of 106.25 μm to 185.00 μm. There was no significant difference amongst the three groups in the measurements recorded on the buccal, lingual, distal, mesiobuccal, mesiolingual, distobuccal, and distolingual surfaces (p >0.05). The findings were significant only on the mesial surface (p <0.05). The least marginal gap on the medial side of 106.25 μm was seen in group B, while the largest marginal gap of 170 μm was seen in group A.

CONCLUSIONS: The post curing conditions do not have a significant effect on the marginal fit of the provisional crowns fabricated by 3D printing. However, there is a need for studies with a larger sample size to confirm the findings.

CLINICAL SIGNIFICANCE: Post-curing conditions do not substantially affect the marginal fit of 3D-printed provisional crowns. This suggests that moderate variations in time and temperature during post-curing may be clinically acceptable. Nevertheless, standardization of protocols and further evidence are necessary to optimize clinical outcomes.

Per continuare la lettura gli abbonati possono scaricare l’allegato