Multiple firings degrade color stability of CAD/CAM ceramics, but not strength
Repeated firing cycles in CAD/CAM ceramic processing significantly compromise color stability, while mechanical properties like flexural strength and microhardness remain largely unaffected.
BMC Oral Health · 2025
Key Findings
- 01Color stability was significantly influenced by both the material type and the number of firing cycles.
- 02Increasing firing cycles led to a statistically significant increase in color instability for one material (LiSi CAD).
- 03There was no significant impact on biaxial flexural strength and microhardness from multiple firings.
- 04Material type significantly affected biaxial flexural strength and microhardness, with IPS e.max CAD showing the highest flexural strength and LiSi CAD showing the highest microhardness.
Application
Design takeaway
When designing products that undergo repeated thermal processing, focus on material selection and process control to mitigate aesthetic degradation, as structural integrity is less likely to be compromised.
How to apply
When specifying materials for CAD/CAM applications, consult data on color stability across multiple firing cycles, especially for visible components where aesthetics are paramount.
Project actions
- 01Consider the aesthetic requirements of your design and how repeated manufacturing steps might affect them.
- 02If your design involves multiple heat treatments, research materials known for their color stability under such conditions.
Method & Evidence
Variables
Strengths & Limitations
Strengths
- +Investigated multiple critical properties (mechanical and optical).
- +Used a statistically robust analysis (two-way ANOVA).
Limitations
The study was conducted in a lab setting, and real-world conditions might differ. Only specific types of ceramics were tested.
Reliability & validity
The study employed standardized testing methods and statistical analysis, enhancing reliability. Validity is supported by the investigation of multiple properties and the use of established measurement techniques.
Think critically
To what extent do the observed color changes in the lab translate to perceptible differences in real-world applications, and how might other environmental factors (e.g., saliva, food staining) interact with these changes?
Design Principles
"Prioritize aesthetic material stability over structural resilience when repeated thermal processing is a known factor in the product lifecycle."
This finding is crucial for designers and manufacturers working with CAD/CAM dental restorations. Understanding that aesthetic qualities are more susceptible to degradation than structural integrity allows for informed decisions regarding material selection, processing protocols, and client expectations.
What This Means for Your Design
Making the same ceramic piece multiple times in the oven can make its color change, but it won't make it weaker.
How to use in your project
- 1.Reference this study when discussing the impact of manufacturing processes on material properties, particularly color stability, in your design project's analysis or evaluation sections.
Add to My Project
Quick Cite
(2025). Effect of multiple firings on mechanical and optical properties of CAD/CAM lithium disilicate-based glass ceramics. BMC Oral Health. https://doi.org/10.1186/s12903-025-07253-y Retrieved from https://designdex.org/study/7815b89a-2d03-4fc0-941c-2553056a37a4/multiple-firings-degrade-color-stability-of-cad-cam-ceramics-but-not-strength
Paragraph starter
The study by Padunglappisit et al. (2025) highlights that while multiple firing cycles in CAD/CAM ceramic processing do not significantly compromise flexural strength or microhardness, they can lead to notable degradation in color stability, with variations observed across different material types. This suggests that for aesthetic-critical applications, material selection and process optimization to minimize firings are essential to maintain visual integrity.
Source
BMC Oral Health
Effect of multiple firings on mechanical and optical properties of CAD/CAM lithium disilicate-based glass ceramics
journal · 2025
View sourceQuestions about this research
- What does the research say about multiple firings degrade color stability of cad/cam ceramics, but not strength?
- When designing products that undergo repeated thermal processing, focus on material selection and process control to mitigate aesthetic degradation, as structural integrity is less likely to be compromised. Evidence: BMC Oral Health (2025).
- Why does "Multiple firings degrade color stability of CAD/CAM ceramics, but not strength" matter for design?
- This finding is crucial for designers and manufacturers working with CAD/CAM dental restorations. Understanding that aesthetic qualities are more susceptible to degradation than structural integrity allows for informed decisions regarding material selection, processing protocols, and client expectations.
- How can designers apply this research?
- When designing products that undergo repeated thermal processing, focus on material selection and process control to mitigate aesthetic degradation, as structural integrity is less likely to be compromised.
- What were the main findings?
- Color stability was significantly influenced by both the material type and the number of firing cycles.. Increasing firing cycles led to a statistically significant increase in color instability for one material (LiSi CAD).. There was no significant impact on biaxial flexural strength and microhardness from multiple firings.. Material type significantly affected biaxial flexural strength and microhardness, with IPS e.max CAD showing the highest flexural strength and LiSi CAD showing the highest microhardness.
- What research method was used?
- Experimental with 180 specimens per material (total 540 specimens).
- How strong is the evidence?
- Evidence strength is rated Strong effect, based on a 2025 journal from BMC Oral Health.
- What should I do differently in my next project?
- When specifying materials for CAD/CAM applications, consult data on color stability across multiple firing cycles, especially for visible components where aesthetics are paramount.
- What are the limitations?
- The study focused on specific types of lithium disilicate-based glass ceramics and may not be generalizable to all ceramic materials used in CAD/CAM. The in-vitro testing conditions may not fully replicate the complex oral environment.
- Is there evidence that cad cam affects design outcomes?
- While multiple firing processes in CAD/CAM ceramic production do not weaken the material's structural integrity, they can lead to noticeable changes in color over time, with some materials being more susceptible than others. This finding is crucial for designers and manufacturers working with CAD/CAM dental restoration Source: BMC Oral Health (2025).
- Where does this structural integrity research apply?
- Dental prosthetics and CAD/CAM manufacturing It sits within final production research on designdex.org.
Related research topics
cad cam design research · evidence on cad cam · does cad cam improve design outcomes · structural integrity studies for designers · cad cam and structural integrity findings · final production research evidence