Evaluation Of Splinting Scan Bodies on The Accuracy of Complete-Arch Digital Implant Scans with Different Scanners

When a person loses all their teeth, the jawbone that once held them begins to shrink and change shape, much like a landscape eroding after a river dries up. To replace these missing teeth with a fixed bridge or a full set of new teeth, dentists often use titanium posts screwed directly into the bone. For these new teeth to fit perfectly and feel natural, the dentist must capture an exact three-dimensional map of where those posts are sitting. In the past, this meant taking messy, uncomfortable impressions with putty-like materials. Today, many dentists use handheld cameras that take thousands of pictures to build a digital model of the mouth. However, when a patient has no teeth left, the mouth lacks the unique bumps and valleys that help the camera's software stitch the pictures together. This makes it difficult to get a precise map of the implant posts, which can lead to a final set of teeth that does not fit quite right.

To solve this problem, many dentists have adopted a technique called splinting. Imagine trying to photograph a group of people standing far apart; if they move even slightly between shots, the final picture will be blurry. To prevent this, dentists sometimes tie the small markers placed on the implant posts together with a rigid bar or a wire and resin, creating a single, solid unit that cannot wiggle. The idea is that by locking these markers in place, the camera will capture a more accurate picture of their positions. But does this extra step actually help, or does it introduce new problems? A team of researchers at Pharos University in Alexandria set out to test this question using a laboratory model of a toothless upper jaw with six implants, comparing the results of two different digital scanners to see if tying the markers together truly improves the accuracy of the final digital map.

The researchers built a clear, hard model of a human upper jaw and placed six metal implants into it at specific locations. They attached small scanning markers to the tops of these implants. Then, they divided their work into three distinct scenarios. In the first scenario, they left the markers alone, completely separate from one another. In the second, they connected the markers using a thin orthodontic wire covered in a hard, pink dental resin. In the third, they used a custom-made metal bar to link the markers together. For each of these three setups, they used two different handheld scanners, the Medit i900 and the Panda P3, to scan the model eight times each. They also used a highly precise laboratory scanner to create a perfect reference map of the model, which served as the gold standard for comparison. By comparing the digital scans from the handheld cameras against this perfect reference, they could measure exactly how close the handheld scans came to the truth.

The results were surprising to those who believed that tying the markers together was always the best approach. The study found that the setup where the markers were left alone, without any wire or bar connecting them, actually produced the most accurate digital maps. When the markers were tied together with either the wire and resin or the metal bar, the scans became slightly less accurate. The researchers measured the difference in position, known as trueness, and found that the separate markers had the smallest errors. For example, the separate markers showed an average error of about 0.039 millimeters with one scanner and 0.043 millimeters with the other. In contrast, when the markers were connected, the errors grew larger, reaching up to 0.052 millimeters. This suggests that the act of adding the connecting material might actually distort the shape of the markers or interfere with the camera's ability to see them clearly, rather than helping to stabilize them.

The study also looked at precision, which measures how consistent the scanner is when it takes the same picture multiple times. Here, the type of scanner mattered more than the method of connecting the markers. One scanner, the Medit i900, consistently produced more repeatable results than the Panda P3, meaning it was better at capturing the same image over and over again without variation. However, neither scanner benefited from the markers being tied together. Whether the markers were separate or connected, the Medit i900 remained the more consistent device. The researchers also checked if the two scanners reacted differently to the connecting bars, but they found that both machines performed worse when the markers were tied, regardless of which machine was doing the scanning.

Ultimately, this research challenges a common practice in dental laboratories. The findings indicate that for a full set of implants in a toothless jaw, tying the scanning markers together with wires or metal bars does not improve the accuracy of the digital scan. In fact, leaving the markers separate allowed both scanners to capture a truer and more precise picture of the implant positions. While the metal bar and the wire-resin combination were intended to prevent movement, they appear to have introduced their own small errors, perhaps by slightly changing the shape of the markers or confusing the software that stitches the images together. For dentists relying on digital technology to build new teeth, this study suggests that the simplest approach—scanning the markers as they are, without extra connections—may actually be the most reliable way to ensure a perfect fit.