Open Access Research
Effect of cooling protocol on the surface hardness of IPS e.max ceram
Abdul Kareem J Al-Azzawi1
, Lateef Essa Alwan2, Duha Gany3,*
1College of Dentistry, University of Alturath, Baghdad, Iraq
2Middle Technical University, Institute of Medical Technology, Baghdad, Iraq
3Diyala Directorate of Health, Ministry of Health, Baghdad, Iraq
*Corresponding author: Duha Gany, Diyala Directorate of Health, Ministry of Health, Baghdad, Iraq; e-mail: duhagany@gmail.com
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Published: 2026 ; https://doi.org/10.61873/
Abstract
Background: Dental ceramics, particularly fluorapatite-based veneering porcelains such as IPS e.max Ceram, require precise thermal processing and controlled cooling cycles to maintain optimal mechanical integrity and surface performance. Aim: To assess the effect of different cooling cycles after second firing procedures on the surface hardness (Vickers hardness, VHN) of IPS e.max Ceram. Methodology: A total of 30 conventional IPS e.max Ceram discs (10 mm in diameter and 2 mm in thickness) were fabricated and randomly divided into three groups (n = 10 per group) based on the applied cooling protocol. Group 1 served as the control group (standard manufacturer’s cooling parameters). Group 2 underwent fast cooling from 750°C to 600°C with a 25% muffle opening for 5 minutes. Group 3 underwent slow cooling from 750°C to 400°C with a 25% muffle opening for 5 minutes. Surface hardness was measured using a Vickers hardness tester under a 9.8 N load for 15 seconds. Statistical analysis was performed using one-way ANOVA and Tukey’s post-hoc test (p < 0.05). Results: The control group exhibited the highest mean surface hardness (753.99 ± 66.98 VHN), followed by the slow cooling group (698.36 ±42.27 VHN), while the fast cooling group recorded the lowest mean surface hardness (644.13 ±63.52 VHN). One-way ANOVA revealed a statistically significant difference among the groups (p = 0.001). Conclusion: The manufacturer’s standard cooling protocol yields the highest surface hardness and remains optimal for IPS e.max Ceram. However, if modified cooling protocols are implemented, slow cooling is significantly superior to rapid cooling, and fast cooling should be avoided to prevent severe mechanical degradation.
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Please cite as: Al-Azzawi A. K. J., Alwan L. E., Gany D.: Effect of cooling protocol on the surface hardness of IPS e.max ceram. Epitheorese Klin. Farmakol. Farmakokinet. xx(xx): xx-xx (2026). DOI: 10.61873/XXXXXXX
pISSN 1011-6575 • eISSN 2945-1914