The use of tomography for dental implant planning.

OBJECTIVES To examine the use of tomography for dental implant planning. METHODS A questionnaire was sent to oral radiology clinics in Sweden and to implantology clinics in different parts of the world with questions on selection criteria and techniques for, and frequency of, pre-implant tomography. Differences between mean values were assessed by t-test. A new method developed by the Swedish Radiation Protection Institute was used to assess radiation absorbed dose from CT. RESULTS Tomography was used by 93.4% of the clinics, but there was marked variation both between and within different clinical situations. It was performed in all cases by 21% and the majority used it for the evaluation of the maxilla, the posterior mandible and in single implant cases. Small clinics (< 100 patients per year) used tomography frequently and clinics in Sweden significantly more often than those in other countries. The majority had changed their policy recently, using tomography more often. CT was used by 73% of respondents, mainly the small clinics. The majority of the large clinics (> 500 patients per year) used conventional tomography. The mean absorbed dose for CT scanning protocols was 65 mGy. The variation within and between different makes of CT was considerable. CONCLUSIONS There are large variations in frequency of use of both conventional and computed tomography for dental implant planning by different clinics who also vary in the indications for their choice. A substantial factor influencing the technique chosen was its availability rather than clinical need.