Author: Duru Erkan Majors: Biology and French
Taking a quick picture break while analyzing the fissure angles of a sectioned tooth on Photoshop
Blurb: Duru Erkan is an honors fellow majoring in Biology and French and minoring in Psychology on a pre-med track. She conducts research in Dr. Peter Ungar’s Dental Topographic Analysis and Microwear Lab in order to create a new method for quantifying fissures to monitor cavity susceptibility. Duru has been doing research with Dr. Ungar since her freshman year and is going to begin her senior year in the fall.
Dental topography can tell us a lot about the way an animal lives or has lived. For example, if an organism’s teeth are relatively flat, one can assume that this organism uses its teeth to grind leafy greens and that it probably lives near or in trees. Whereas if an animal’s teeth have more relief, it is more likely to be an omnivore. However, dental topography is not only important for ecological purposes; it can also tell us about the types of diseases a dental patient might develop. People who have deep, angled pits and fissures in their teeth are more prone to developing cavities because these areas allow bacteria to thrive. This is why pediatric dentists recommend filling complex fissures with sealants. But to date, there is no quantitative protocol to objectively determine which fissures are complex enough to need sealants. As a result, sealants are overused at the patients’ expense.
My research project is to create a new system for quantifying fissure patterns using 3D analytic software and tools already available in dental clinics in order to monitor cavity susceptibility and sealant necessity. I started this project in the spring by receiving 384 sets of molars from de-identified patients in the orthodontic clinic at the Indiana University School of Dentistry. I then edited the scans by cropping the teeth at the cervix and aligning them on an xyz plane according to our lab protocol. Next came the method developing process: the most strenuous part of my research.
Dr. Ungar, his colleagues from Indiana University Drs. Hara and Soto, and I tried multiple techniques to quantify fissures before we finalized a method. First, we tried “filling in” the tooth scans in Geomagic—a 3D photogrammetry software—and calculating the change of the surface area of the teeth to find the area of the fissures. We decided that this process was not accurate enough and moved on. Next, Dr. Ungar and I came up with the idea of laying a color-coded topographic map onto teeth and finding the percent area of fissures by counting the number of pixels of each color on Creative Cloud Photoshop. Around this time, Dr. Hara found an article called “Morphometric Analysis of Occlusal Groove-fossa-system in Mandibular Third Molar” which explains that fissures can be quantified through the angles they make with the cusps upon manual bisection. So, we put together our attempts with the information from the article and confirmed our final method.
The four largest cusps of human molars can be thought of as the four corners of a rectangle. Two of these cusps are on the side of the tooth that faces the cheek—or on the buccal side—and the other two are on the side of the tongue—or the lingual side. To get the best view of the fissure on a tooth, a line can be drawn from the tip of the anterior buccal cusp (protoconid) to that of the anterior lingual cusp across from it (metaconid), and the tooth scan can be cropped at this line. The same can be done for the posterior cusps (hypoconid to entoconid). I came up with a process of cropping the teeth in this way on Geomagic by fitting each cusp into theoretical spheres, finding their centers, and connecting the centers of the spheres across from one another to draw a cropping line. After sectioning, screenshots of the cropped scans can be taken looking into the section. Then, these screenshots can be uploaded onto Photoshop to measure fissure angles by the method described in the article. This method consists of drawing guiding lines on the tooth sections and measuring angles with the help of those lines.
Now that our method is set in stone, I will be spending a lot of time in the lab carrying it out. There are four 1st molars for each of the 348 patients, and each molar can be cropped for two angle measurements. I have finished cropping and measuring the angles of the lower left first molars for all the patients. Over the summer and in the fall, I will continue to produce data for the rest of the scans. Once all the data is produced, we will analyze the results and see what numerical values can be correlated with the level of complexity of fissures.
The hardest part of this whole process was to come up with a brand-new protocol. It required creative thinking and a large amount of trial-and-error testing. We had to make sure that our method was repeatable, reliable, and accurate along the way. Dr. Ungar and his colleagues in Indiana were very helpful in guiding my process, answering my questions, and giving me feedback on ideas I was trying to morph into existence. I had always expected lab work to be something I got taught and then repeated, but Dr. Ungar has given me a lot of creative liberty to think outside of the box in order to conduct research. This is one of the reasons I joined his lab back in freshman year. When Dr. Ungar came to my Biology for Majors class as a guest lecturer, I was interested in his research because of the creative way in which he studies teeth as a marker for the impact of climate on evolution. Unfortunately, the toughest but also the most exciting part of my project is now done, and I will be doing weeks of repetitive work to generate data. I am excited to see our results once the next step is done, and I am looking forward to seeing our hard work pay off.