MRI and dental implantology: Two which do not exclude each other

What is it about?

The authors investigated the healing process of dental implants that were manufactured from the polymer polyetheretherketone (PEEK). To enhance the bone formation the dental PEEK implants were coated by a thin Titanium layer. The study must be considered as a proof of concept. Complying the principles of animal testing only three animals (minipigs) were used. The polymer PEEK is a high-performance thermoplastic and turned out as a promising candidate for use in dentistry. Among its chemical, thermal and radiation stability PEEK is compatible to medical imaging. That is why the authors used dental PEEK implants to evaluate the suitability of Magnetic Resonance Imaging (MRI) to assess their ingrowth into bone. Currently, MRI is not a standard imaging technique in the field of biomaterial science and especially in dentistry. The vast majority of studies used histological techniques to analyze the implant-tissue-interactions. Within the research paper three issues have been evaluated: (1) How far is (nonclinical) micro-MRI able to complement the information obtained by histology? - The authors found comparable results for the quantification of the newly formed bone. The dental PEEK implants could be depicted with high resolution. (2) Which additional information is accessible by use of MRI and histology in parallel? - MRI has been suitable to differ between soft tissue, fatty tissue and mineralized bone. With histology the so-called osteoid tissue (which is a pre-stage to bone) could be identified. (3) Do dental implants made from PEEK show a suffienct ingrowth into bone? - The authors were able to demonstrate that the PEEK implants showed a satisfactory integration into the mature bone. Within the observed time period the animals showed an uneventful healing.

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Why is it important?

Two issues are important to the scientific community: (I) The polymer PEEK might be a suitable material for replacing metal components. Today, PEEK has the highest clinical impact for spinal applications and for treatment of large bone defects of the skull (the so-called cranioplasty). Up to now, there is a controversial scientific discussion in the field of implant dentistry to use the polymer as an alternative material. (II) MRI is an imaging technique without ionising radiation that offers an excellent soft tissue contrast. Furthermore, MRI is a non-destructive, high-resolution imaging modality. However, in the field of biomaterial science MRI is not common to study implant-tissue-interactions. Up-to-now, histological techniques are used to evaluate the ingrowth of biomaterials in its host tissue. It would be advantageous to use non-destructive imaging more frequently, because histology is destructive and time-consuming and do not offer the possibility to investigate the healing process repeatedly with living animals.

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