Advanced imaging: Magnetic resonance imaging in implant dentistry

Accuracy of image-guided implantology

OBJECTIVES

The accuracy of two commercially available systems for image-guided dental implant insertion based on infrared tracking cameras was compared with manual implantation.

MATERIAL AND METHODS

Phantoms of partially edentulous mandibles were used. In a master phantom, pilot boreholes for dental implants were placed. These boreholes were reproduced in slave phantoms using either of the two image-guided systems and manual implantation. The resulting positions were determined using a coordinate measurement machine and compared with the master model.

RESULTS

In comparison with manual implantation, the difference of borehole positions to the master phantom was significantly lower using either of the systems for image-guided implant insertion.

CONCLUSION

Image-guided insertion of dental implants is significantly more accurate than manual insertion. However, the accuracy that can be achieved with manual implantation is sufficient for most clinical situations.

Geometric accuracy of magnetic resonance imaging of the mandibular nerve

OBJECTIVES

Magnetic resonance imaging (MRI) is not routinely used for dental implant planning. A prerequisite for dental implant planning is the accurate imaging of risk structures like the mandibular nerve. The geometric accuracy of the imaging of the mandibular nerve was investigated.

METHODS

Two human cadaver heads were scanned using MRI. Computed tomography (CT) scans of the same heads were used as a benchmark. Using a stereotactic frame, corresponding images of MRI and CT were superimposed and the concordance of the images of the mandibular nerve in MRI with those of the mandibular canal in CT was assessed.

RESULTS

The geometric accuracy of the mandibular nerve in MRI was as good as that of the mandibular canal in CT imaging.

CONCLUSIONS

MRI of the mandibular nerve is sufficiently accurate for the use of this imaging method in dental implant planning.

Radiological evaluation of sinus lift operation: what the general radiologist needs to know

This article provides an overview of the sinus lift operation, including radiographic evaluation of the procedure. Plain radiographs such as dental or panoramic radiographs have conventionally been used to measure the bone volume in the operation site, but full three-dimensional assessment of the region before and after the sinus lift operation is advisable both to allow planning of the lift and to see the results of it. The general radiologists sometimes misinterpret the graft material used in sinus lift cases as odontogenic tumour or some other pathology. The aim of this article is to put an end to this wrong interpretation and to familiarize the general radiologist with pre-operative and post-operative imaging of sinus lift cases.

Artefacts in magnetic resonance imaging caused by dental material

A common problem in computer tomography (CT) based imaging of the oral cavity is artefacts caused by dental restorations. The aim of this study was to investigate whether magnetic resonance imaging (MRI) of the oral cavity would be less affected than CT by artefacts caused by typical dental restorative alloys. In order to assess the extent of artefact generation, corresponding MRI scans of the same anatomic region with and without dental metal restorations were matched using a stereotactic frame. MRI imaging of the oral and maxillofacial region could be performed without reduction of the image quality by metallic dental restorations made from titanium, gold or amalgam. Dental restorations made from titanium, gold or amalgam did not reduce the image quality of the MRI sequence used in imaging of the oral and maxillofacial region for dental implant planning. In this respect MRI is superior to CT in implant planning.

A Comparative Study of Computed Tomography and Magnetic Resonance Imaging for the Detection of Mandibular Canals and Cross-Sectional Areas in Diagnosis prior to Dental Implant Treatment

BACKGROUND

Computed tomography (CT) is effective in the diagnosis of dental implants. However, it has the disadvantage of exposing patients to high doses of x-rays, and the mandibular canals cannot be detected by CT in some clinical cases.

PURPOSE

The purpose of this study was to examine the detectability of the anatomic morphology of the molar region in the lower jaw (where implantation is common) by CT and magnetic resonance imaging (MRI), to compare the data, and to determine the usefulness of MRI in diagnosis prior to dental implant treatments.

MATERIALS AND METHODS

Eleven female subjects (average age, 59 years) who had partially edentulous mandibles (total of 19 sites) were included in the study. CT and MRI were performed with the same subjects, and the degrees of identification of the mandibular canal in the first and second molar regions were compared. Dimensional accuracy in the second molar region was also compared.

RESULTS

With CT, the canals of the first molar regions were not identified in 11 of 19 sites; however, MRI identified the canals in all 19 sites. Using the kappa index, we found that the inter- and intraobserver identification reliabilities (0.84 and 0.87, respectively) were excellent, especially for MRI. Dimensional positioning of the canal in the second molar region was almost the same with MRI as with CT.

CONCLUSIONS

MRI is an alternative method in diagnosis prior to dental implant treatment in the mandibular molar region.