Analyzing the occlusion with digital methods: Looking at teeth and jaw movements in a new light

Digital methods are revolutionizing dentistry. They are offering dental professionals new ways of analyzing dental occlusion, for example, by visualizing jaw movements in real time. Furthermore, digital technologies are bringing together fields that had little to do with each other in the past. Consequently, dentistry has become an interesting field for mathematicians and computer scientists such as Dr Sebastian Ruge from Greifswald (Germany). Read his story.

Dr Sebastian Ruge never dreamt of entering the field of dentistry. He has always had a great passion for mathematics and computers – two subjects, which he studied in Greifswald in northeastern Germany. Dr Ruge was introduced to dentistry during his studies. “Professor Bernd Kordass, a specialist in dental occlusion and a pioneer of digital diagnostics in dentistry, was looking for someone well-versed in computer graphics and visualization” recounts Dr Ruge. This was in 2006. “The scanning of study models was completely new and the main concern at that time was about the accuracy of the scans.”

Setting scans in motion

Professor Kordass was ahead of his time: “He wanted to see the scanned images in motion. This was a completely new scene for me. My task involved developing a suitable procedure using computer engineering principles. It had little to do with classical dentistry.”

Not the first computer scientist in dentistry

Dr Ruge was not the first computer scientist to work for Professor Kordass. When he first joined the team, he just watched the others work with the jaw models and carry out the tests. “Slowly, I was introduced to the subject matter. Fortunately, there was a lot of room for new ideas and suggestions. I was welcome to contribute my knowledge and skills.”

“Dental Computer Science” department

Suddenly, everything went very quickly. Sebastian Ruge did an additional practical course in dentistry. His thesis dealt with visual articulators – the specialist topic of his boss. Then one day, the young student found himself in the midst of the dental world and immersed in the subject of occlusion. “Dental Computer Science” is the name of the university department in which he works.

Inspiring mathematicians to become dental professionals 

“Mathematicians have a tendency to analyze and logically structure everything” says Dr Ruge. This is the main strength of his trade. Today, it is his goal to interest other colleagues in teeth and dentistry – even though Dr Ruge admits that this combination sounds rather unusual. At first glance, it is easier to connect my qualifications with other fields, for example, the automotive industry. You would not really think of dentistry. 

Occlusion and the digital world

What does Dr Ruge’s work involve? His doctoral thesis was dedicated to developing software which shows the movements of the lower jaw in real time. For this purpose a special coupling device equipped with a sensor is used. It depicts all the movements and loads in the jaw in real time; the occlusal interface is optimally shown. The observer can see where the contacts are located and which areas are exposed to high loads. Digital methods are thus considerably enhancing the study of occlusion. 

Computer games: exercises for the lower jaw

In addition, Dr Ruge has developed computer games with which the coordination of the jaws can be trained. He admits that initially these games were considered to be simple by-products. Nevertheless, he decided to take their development seriously. In the process, he designed a table tennis game, which can be played at different speeds and difficulty levels. The game is not controlled by a joystick, but rather by the movements of the lower jaw. The objective is to playfully train and extend jaw movements in patients with the aim of relieving tension and resolving jaw disorders and restricted movements and other occlusal disorders. The jaw movements are streamlined, which improves occlusion. Training the lower jaw makes this body part more flexible: It’s a little bit like yoga explains Dr Ruge. An additional advantage: The games measure all the movements and therefore allow the results to be documented and quantified.

Taking advantage of other information resources

A lot of improvements are still needed. According to Dr Ruge, virtual articulators cannot compare with their mechanical equivalents, since they cannot simulate all of the required movements. Nevertheless, this is bound to change in the future. The study of electromyography (EMG) has seen incredible developments over the past few years: This field of study analyzes muscle activity. Moreover, efforts are underway to one day find a means of looking “into” teeth and observing their structure during chewing and biting. “We would like to take advantage of as many information resources as possible in order to analyze and understand the occlusion of the lower jaws and teeth as accurately as possible”, says Dr Ruge.

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Entertaining live demonstrations

The aim of the presentations and lectures of Dr Ruge and Professor Kordass is to show how to measure and analyze dental occlusion in an entertaining way. Initially, it looks quite intimidating when they attach the facebow and the lower part of the specially developed lower jaw sensor called JawMotion Analyzer from Zebris (Germany) to their face. Ultrasound measures the position of the jaw in the same way that a GPS system measures your position on the earth. Signals record the position of the lower jaw at a specific moment in time. The measured data is sent to a computer and converted into a visual image in real time. The scanned data of the upper and lower jaw is also used. If desired, a virtual food – for example a gum candy – can be added in order to make the situation more realistic. The main objective is to obtain a highly accurate picture and answer the following questions: How do the teeth interact? How does the lower jaw work? How do the muscles work? “We develop and present prototypes that respond to these questions and we try to interest manufacturers and partners in them” says Dr Ruge.

Digital vision

Dr Ruge has high hopes and a clear vision for the future: “Dentistry and dental lab technology will see substantial changes with the introduction of digital methods. The number of standardized procedures will increase substantially.” According to him, this is associated with considerable advantages for dentists and dental technicians alike. “Both parties – the dentist and the dental technician – will have to work more closely together. Dental technicians will be given more opportunities to understand their patients, for example, by means of facial scans. The importance of an interdisciplinary team composed of dentists and dental technicians will increase in order to help suitably customize the treatment measures. This will enhance patient satisfaction even further. Digital possibilities will help to reconcile the requirements of esthetics and function more effectively.”

Pioneers in digital dentistry and digital lab technology

The University of Greifswald is considered to be a pioneer in digital dentistry and dental lab technology. The university offers courses on CAD/CAM for dentists. Dental graduates can enroll in a part-time master’s program entitled Clinical Dental CAD/CAM. Dental technicians have the possibility of obtaining a Master of Science (M.Sc.) degree in Digital Dental Laboratory Technology.

Another must-read by Prof. Dr Kordass can be found in the latest Reflect issue entitled "Digital Dentistry: How virtual jaw measurements make prosthetics more efficient".