A comparison of conventional panoramic radiographs with volumetric computed tomography images in the preoperative assessment of impacted mandibular third molars.

PURPOSE In the present study, we evaluated the geometric, topographic, and anatomic reliability of volumetric computed tomography (VCT) images by comparing conventional panoramic radiographs with reconstructed VCT panoramic and paraxial images before performing third molar surgery. PATIENTS AND METHODS A total of 6 anatomic sites on 10 patients who showed a topographic relationship between the apices of the third molar root and the mandibular canal were preoperatively assessed by 5 oral surgeons using conventional panoramic radiographs; these were complemented and compared with secondary reconstructed paraxial and panoramic VCT images. RESULTS The position of the apices in relation to the mandibular canal could be revealed on 94% of VCT reconstructed paraxial images. Assessment of VCT paraxial images could be facilitated by using a toolbar marker in 70% of the paraxial images. In 90% of the paraxial images, it was possible to assess the relationship of the mandibular canal and its adjacent anatomy. The visual grading scores for conventional panoramic images were significantly better on all 7 assessed anatomic sites compared with the reconstructed VCT panoramic images. CONCLUSION The results showed that the VCT paraxial images gave a significantly clearer perception of the mandibular nerve than conventional panoramic radiographs. However, conventional panoramic radiographs were shown to be better than the VCT reconstructed panoramic images and were therefore an invaluable tool in the "expert-derived" assessment and posed the potential for identifying the need for further VCT diagnostic procedures.

[1]  A. C. Richardson,et al.  The accuracy of dental radiographic techniques used for evaluation of implant fixture placement. , 1995, The International journal of periodontics & restorative dentistry.

[2]  R. Kraut,et al.  Interactive CT Diagnostics, Planning and Preparation for Dental Implants , 1998, Implant dentistry.

[3]  A. Smith,et al.  Inferior alveolar nerve damage following removal of mandibular third molar teeth. A prospective study using panoramic radiography. , 1997, Australian dental journal.

[4]  Richards Ag.  Roentgenographic localization of the mandibular canal. , 1952 .

[5]  Lars Gunnar Månsson.  Evaluation of radiographic procedures : investigations related to chest imaging , 1994 .

[6]  E. Lam,et al.  Comparison of two-dimensional orthoradially reformatted computed tomography and panoramic radiography for dental implant treatment planning. , 1995, The Journal of prosthetic dentistry.

[7]  A. Farman,et al.  The OP 100 Digipan: evaluation of the image layer, magnification factors, and dosimetry. , 1997, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[8]  D. Laskin,et al.  Accuracy of radiographs in classification of impacted third molar teeth. , 1988, Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons.

[9]  K. Yoshiura,et al.  Computed tomographic features of calcifying odontogenic cysts. , 1998, Dento maxillo facial radiology.

[10]  T Suetsugu,et al.  Accurate presurgical determination for implant placement by using computerized tomography scan. , 1996, The Journal of prosthetic dentistry.

[11]  P. Mozzo,et al.  A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results , 1998, European Radiology.

[12]  E. Tammisalo,et al.  Stereographic assessment of mandibular canal in relation to the roots of impacted lower third molar using multiprojection narrow beam radiography. , 1992, International Journal of Oral & Maxillofacial Surgery.

[13]  J. Lambrecht,et al.  Dental implant treatment planning with reformatted computed tomography. , 1995, Dento maxillo facial radiology.

[14]  A. Delbalso.  An approach to the diagnostic imaging of jaw lesions, dental implants, and the temporomandibular joint. , 1998, Radiologic clinics of North America.

[15]  G P Schmuth,et al.  The application of computerized tomography (CT) in cases of impacted maxillary canines. , 1992, European journal of orthodontics.

[16]  S. Berger,et al.  Inflammatory disease of the jaw: appearance on reformatted CT scans. , 1998, AJR. American journal of roentgenology.

[17]  N Samman,et al.  Computer-assisted three-dimensional surgical planning and simulation: 3D color facial model generation. , 2000, International journal of oral and maxillofacial surgery.