Axel Ruprecht

Comparison of two-dimensional orthoradially reformatted computed tomography and panoramic radiography for dental implant treatment planning

The widespread use of dental implants in partially and completely edentulous patients has brought about a need to preoperatively depict and quantify accurate bone height and contour. A number of conventional intraoral and extraoral radiographic techniques have been used, including the relatively new modality of two-dimensional orthoradially reformatted computed tomography. Despite rapid advances in imaging technology, many clinicians continue to rely on techniques such as panoramic radiography that produce images that distort the jaws nonuniformly. This study compared bone height measurements of jaws made with these two imaging modalities. Nineteen sites in 10 patients were imaged with both techniques and mean bone height was determined for each imaging technique and site. Significant differences were found between mean bone heights measured with the two imaging modalities (p < 0.0005). Situations in which the use of dental implants would be particularly advantageous demonstrated the largest discrepancies, that is, when bone height measurements were less than 15 mm.

2-D and 3-D reconstructions of spiral computed tomography in localization of the inferior alveolar canal for dental implants ☆ ☆☆ ★

OBJECTIVE The purpose of this study was to compare and validate the accuracy of measurements on 2-dimensional and 3-dimensional reconstructions from spiral computed tomography in localization of the inferior alveolar canal. STUDY DESIGN Four edentulous human cadaver heads with intact mandibles were imaged in a spiral computed tomography scanner. The data were transferred to a networked computer workstation to generate 2-dimensional orthoradially reformatted and 3-dimensional volumetric images. Linear measurements of the images were made from the superior border of the inferior alveolar canal to the alveolar crest. The specimens were then dissected at corresponding locations, and physical measurements were made. RESULTS There were no statistically significant differences between the 2-dimensional computed tomography measurements and the physical measurements or between the 3-dimensional computed tomography measurements and the physical measurements. However, we did find a statistically significant difference between the 2-dimensional and 3-dimensional computed tomography measurements. CONCLUSIONS 2-dimensional and 3-dimensional computed tomography images allow accurate measurements for localization of the inferior alveolar canal.

The incidence of taurodontism in dental patients

The incidence of taurodontism was investigated in a dental school patient population. Radiographic examinations of 1,581 patients were evaluated; of this population, 179 patients (11.3%) exhibited taurodontism. Thirty-eight patients had taurodonts as well as another dental anomaly of some type.

Magnetic resonance imaging used to assess patients with trigeminal neuralgia.

To assess the value of magnetic resonance imaging in the evaluation of trigeminal neuralgia, 51 patients were studied by magnetic resonance imaging after a trigeminal protocol. Clinical and magnetic resonance imaging results were correlated. Seventeen (33%) nonvascular abnormalities and 27 (53%) vascular contacts or compressions of the trigeminal nerve were demonstrated. Of the patients younger than of 29 and 39 years of age, 100% and 45%, respectively, had a tumor or multiple sclerosis compared with 20% and 18% of those older than 40 and 60 years of age, respectively. One third of the patients with pain in more than one branch of the trigeminal nerve had tumors. On the basis of this study, magnetic resonance imaging may be useful in discovering underlying pathoses associated with trigeminal neuralgia if patients have failed to respond to an initial conservative treatment. The patients most likely to exhibit significant magnetic imaging resonance findings are young and with pain in more than one trigeminal branch.

Accuracy of linear measurement in the Galileos cone beam computed tomography under simulated clinical conditions

OBJECTIVES The aim of this study was to determine the geometric accuracy of cone beam CT (CBCT)-based linear measurements of bone height obtained with the Galileos CBCT (Sirona Dental Systems Inc., Bensheim, Hessen, Germany) in the presence of soft tissues. METHODS Six embalmed cadaver heads were imaged with the Galileos CBCT unit subsequent to placement of radiopaque fiduciary markers over the buccal and lingual cortical plates. Electronic linear measurements of bone height were obtained using the Sirona software. Physical measurements were obtained with digital calipers at the same location. This distance was compared on all six specimens bilaterally to determine accuracy of the image measurements. RESULTS The findings showed no statistically significant difference between the imaging and physical measurements (P > 0.05) as determined by a paired sample t-test. The intraclass correlation was used to measure the intrarater reliability of repeated measures and there was no statistically significant difference between measurements performed at the same location (P > 0.05). CONCLUSIONS The Galileos CBCT image-based linear measurement between anatomical structures within the mandible in the presence of soft tissues is sufficiently accurate for clinical use.

Personal Computer-Based Three-Dimensional Computed Tomographic Images of the Teeth for Evaluating Supernumerary or Ectopically Impacted Teeth

This study describes the use of personal computer (PC)-based three-dimensional computed tomographic (3D CT) images in the evaluation of supernumerary and ectopically impacted teeth. Three selected cases were presented as examples of the more complex cases in which 3D CT imaging added information not readily available from periapical, occlusal, or panoramic radiographs. Patients were CT scanned from the occlusal plane to the periapical region of the impacted teeth. Digital Image and Communications in Medicine CT data were transferred to a personal laptop computer using a network line. 3D volume rendering was performed using PC-based volumetric analysis software. 3D CT-reformatted imaging of the teeth is a useful way to investigate and localize supernumerary or impacted teeth. Newer software that enables this investigation using a PC provides a relatively inexpensive way to carry out such investigations, making it easier for dental practitioners to request such investigations and to view the results in real time in their own offices.

Incidental Findings on Cone Beam Computed Tomography Images

Background. Cone beam computed tomography (CBCT) has gained widespread acceptance in dentistry for a variety of applications. Most dentists who are not radiologists/trained in radiology are generally not familiar with interpretation of anatomical structures and/or pathosis outside their area of primary interest, as often this was not within the scope of their training. Objectives. To assess that the number of incidental findings on a CBCT scan is high both within and outside of the primary area of interest, thereby emphasizing the importance of interpretation of all areas visualized on the scan. Materials and Methods. An oral and maxillofacial radiologist reviewed 1000 CBCT scans (382 males and 618 females) for findings both in- and outside the area of interest. Results. Of the 1000 subjects that were reviewed, 943 scans showed findings in the primary regions of interest and/or outside the regions of interest, and 76 different conditions were visualized in these scans both in and outside the areas of interest. Conclusion. From the wide scope of findings noted on these scans, it can be concluded that it is essential that a person trained in advanced interpretation techniques in radiology interprets cone beam computed tomography scans.

Transcranial radiography and linear tomography: A comparative study

There is continual controversy concerning the use of radiographs to determine the position of the mandibular condyle within the glenoid fossa for the diagnosis and treatment of temporomandibular disorders. This study compared joint space measurements from transcranial radiographs and linear tomographs with the anatomic joint space to determine whether condylar position could be accurately recorded radiographically. Anterior, superior, and posterior joint space dimensions were measured from projected radiographs with a sonic digitizer, whereas anatomic joint space dimensions were recorded from the thickness of polyether impressions of the joint space. Posterior/anterior joint space ratios were used to classify relative condylar position as anterior, concentric, or posterior. The Pearson correlations (alpha = 0.05) were calculated to determine the consistency between radiographic and anatomic joint space ratios. The corrected and standard transcranial projections did not accurately reproduce the anatomic joint spaces or the relative condylar positions. Only the corrected tomographic projection accurately reflected the condyle-fossa relationships.

Radiologic interpretation of bone striae: An experimental study in vitro ☆ ☆☆ ★

OBJECTIVE The purpose of this study was to determine whether the mandibular alveolar striae patterns seen in radiographs represent trabecular bone. STUDY DESIGN Segments of human cadaver mandible were obtained. Two identical radiographs were made of each segment initially, after removal of trabecular bone, after slight smoothing of the endosteal surface, and after aggressive smoothing of the endosteal surface. The radiographs were projected in random pairs for each sample. Six dentists judged whether a difference in the amount of trabecular bone could be detected. RESULTS Chi-square test analysis revealed no significant difference in the amount of trabecular bone judged initially and after removal of trabecular bone. A significant difference appeared to exist on radiographs made initially and after slight smoothing. A significant difference was judged to exist on radiographs made after slight removal of the endosteal surface and after aggressive removal of the endosteal surface. CONCLUSIONS Mandibular radiographic striae patterns, interpreted as arising from trabecular bone, actually result from bone patterns on the endosteal surface.

Osteopetrosis: Report of a case and discussion of the differential diagnosis

A case of autosomal dominantly inherited osteopetrosis is presented, together with a discussion of the features of this disease and the major diseases to be considered in the differential diagnosis.