Imaging techniques in dentistry

Radiography is the most significant paraclinical diagnostic method employed in connection with dental
treatment. Radiographic examinations are used to diagnose pathological conditions in the jaw bone
and those parts of the teeth that are not visible in the oral cavity.

Radiography is used before, during, andafter treatment, for instance to diagnosecaries lesions before treatment of periodontaldisease; before the removal of wisdomteeth; before and after the insertion of dental implants; and before, during, and after root-canal treatment of a tooth. Moreover, orthodontic specialists use radiography to decide on a course of treatment and to assess the results achieved.

Thermogram of patient following removal of a wisdom tooth. White colour indicates warmest skin area.Most of the research done in imaging techniquesis clinical, and therefore relevant todental practice. Digital radiographic techniques have been gaining ground in general dental practice, not only to examine teeth, but also to carry out extensive examinations of the jaws, the temporomandibular joint (TMJ), and the skull. We are conducting intensive research to clarify the diagnostic accuracy and image quality obtained with digital receptors, and in recent years dental CT scanning has taken a high priority as a research field. CT scanning is often used prior to the removal of wisdom teeth in the lower jaw in order to assess tooth position and avoid nerve damage during the procedure. Also, when analysing results after orthodontic and surgical treatment of skeletal deviations, we combine information from CT images and from 3D virtual tooth models. We also stay abreast of new imaging techniques that are not based on ionizing radiation. One technique we are currently working on is thermography, which measures the temperature of a surface and displays a thermogram (see below) where each colour represents a temperature. With measuring of the facial skin, this method can be used to assess the effect of medication administered to reduce swelling or infection after the removal of wisdom teeth.

We also study patient discomfort and the working processes associated with the introduction of new technology. One way of doing this is to conduct a Medical Technology Assessment (MTA), and such projects notably concern equipment involving high radiation doses to the patient (as CT scanners do). The objective of an MTA can be to compare, on the one hand, the efficacy of the new diagnostic method on patient treatment and, on the other, the increased costs and other socio-economic aspects of the method, and the radiation exposure it entails for the population. The underlying costbenefit analyses are carried out in cooperationwith health economists.

Moreover, as a research method for in vitro studies we use micro-CT scanning for volumetric analyses of animal and human bone and tooth specimens. The volumetric data thus obtained forms the basis of finiteelement analyses, which in turn are used to assess modelling and remodelling of bone at a cellular level, and also to perform experimental studies of caries lesions and the quality of root-canal fillings.

Projects

1. Assessing the diagnostic value of various imaging methods (their sensitivity, specificity, and so on):

  • The value of radiological methods prior to removing wisdom teeth
  • The value of radiological methods in assessing bone prior to inserting tooth implants
  • The correctness of digital receptors in assessing caries lesions, root fractures, and the quality of root-canal fillings
  • The value of tomography in assessing the TMJ, and its effect on the treatment plan

2. Clinical longitudinal studies:

  • Using thermography to assess inflammation after removal of wisdom teeth
  • The effect of CT image quality following patient movement during examination
  • CT scanning to assess the effect of treatment of the TMJ: a) in juvenile arthritis patients; and b) when applying various ortho-surgical principles

3. Randomized clinical trials with longterm follow-up:

  • Assessment of various tissue-regeneration methods, including bone transplants, in connection with implant treatment
  • Assessment of nerve damage following removal of wisdom teeth, investigated pre-operatively using various radiographic methods
  • The success of implant treatment, assessed pre-operatively using various radiographic methods
  • Comparison of various treatment principles used for dento-alveolar bone modelling

4. MTA studies:

  • Socio-economic aspects of using high-technology, dose-intensive CT methods instead of conventional radiographic examination for dental diagnostic tasks

Milestones

The Department of Dentistry at AU was the first dental school in the world to replace conventional radiographic film methods with digital receptors in its clinical education programmes.

Our dental school was also the first dental clinic in Denmark to implement advanced 3D techniques such as dental CT scanning.

We initially did so when treating orthodontic patients with special needs, such as juvenile idiopathic arthritis.

The influence of computerized information technologies on image quality in dental radiographs
(Wenzel A. Dr. odont. thesis. Danish Dental Journal. 1991;95:527–59)

Radiography for the detection of dental caries lesions
(Hintze H. Dr. odont. thesis. Royal Dental College. University of Aarhus, 2004)

Synchrotron radiation-based microtomography of alveolar support tissues
(Dalstra M. Orthod Craniofacial Res. 2006;9:199–205)

Cross-sectional tomography and temporomandibular joint disorders
(Wiese M. PhD thesis. School of Dentistry. University of Aarhus, 2008)

Work-flow with intraoral digital radiography: A systematic review
(Wenzel A. Acta Odontol Scand. 2010;68:106–14)

Methods

  • Assessing the diagnostic accuracy of new techniques
  • Longitudinal clinical studies
  • Randomized clinical studies
  • Clinical cross-over experiments
  • MTA studies.

Sections and departments working within the research area

Contacts

Ann Wenzel
Professor

Phone: +4587168121
Email:

Paolo Cattaneo
Associate professor

Phone: +4587167459
Email:


Michel Dalstra
Associate professor

Phone: +4587168131
Email:


Erik Gotfredsen
Systems Planner

Phone: +4587168146
Email:


Louise Hauge Matzen
Associate professor

Phone: +4587167457
Email:


Lars Schropp
Associate professor

Phone: +4587168087
Email:


Rubens Spin-Neto
Associate professor

Email: