CAD/CAM vs. Traditional: Which Dental Framework Wins?
"A close look at marginal and internal fit in implant-supported frameworks."
For years, computer-aided design and manufacturing (CAD/CAM) systems have revolutionized dentistry, offering a seemingly faster and more precise way to create dental restorations. These systems, whether subtractive or additive, have been increasingly used for fabricating cobalt-chromium (Co-Cr) frameworks, especially for long-span restorations. However, a crucial question remains: how does the accuracy of these CAD/CAM frameworks compare to traditional methods?
Achieving a precise fit is paramount for the success and longevity of implant-supported restorations. Ill-fitting frameworks can lead to complications like screw loosening, cement washout, and even biological issues such as inflammation and bone loss. Therefore, understanding the marginal and internal fit of different manufacturing techniques is essential for clinicians.
This article delves into a recent study that compared the marginal and internal fit of implant-supported, cement-retained 5-unit Co-Cr metal frameworks. The frameworks were fabricated using three different techniques: lost wax (LW), CAD-CAM milling, and selective laser melting (SLM). By examining the findings of this research, we aim to provide clarity on which manufacturing technique offers the most accurate fit and ultimately, the best outcome for patients.
Marginal and Internal Fit: The Key to Long-Term Success
The study meticulously evaluated the marginal and internal fit of the frameworks. Researchers fabricated a total of 30 Co-Cr metal frameworks, designed for 5-unit implant-supported restorations. These frameworks were created using three different manufacturing techniques, ensuring a robust comparison between the methods. The chosen techniques represent a spectrum of approaches:
- Lost Wax (LW): A traditional technique involving creating a wax pattern, investing it in a mold, and then casting the metal framework.
- CAD-CAM Milling: A subtractive technique where the framework is milled from a solid block of material using computer-controlled machinery.
- Selective Laser Melting (SLM): An additive technique where the framework is built layer by layer by melting metal powder with a laser.
The Verdict: Which Technique Offers the Best Fit?
The results of the study revealed significant differences in marginal fit between the manufacturing techniques. CAD-CAM milling techniques exhibited the widest mean marginal discrepancy values (84 µm), indicating a less accurate marginal fit compared to the other methods. In contrast, the lost wax technique demonstrated the lowest mean marginal discrepancy values (36 µm), suggesting a superior marginal fit.
Interestingly, axial discrepancy values were similar for all manufacturing techniques, indicating that the techniques performed comparably in this aspect. However, the highest internal gap values were measured at the occlusal area, with the following values: LW (154 µm), CAD CAM milling (212 µm), and SLM (290 μm). These findings suggest that the internal fit at the occlusal area may be a critical factor to consider when selecting a manufacturing technique.
In conclusion, the study suggests that while CAD/CAM technology offers advantages in terms of speed and automation, it may not always provide the most accurate fit, particularly in the marginal area. The lost wax technique, despite being a more traditional method, demonstrated superior marginal fit in this study. Clinicians should carefully consider these findings when selecting a manufacturing technique for implant-supported frameworks, weighing the benefits of CAD/CAM technology against the potential for compromised fit. Further research and advancements in CAD/CAM technology are needed to improve the accuracy and predictability of these techniques.