Consideration of image quality as influencing factor in Volumetric Tomography

The purpose of this study was to compare image quality of bone implants using 4 modalities. Three types of bone blocks were assessed using Volumetric Tomography (VT). The modalities used were 5, 7, 9 or 11 reference images used to reconstruct the VT images. 

Method:

OP-200D VT machine (Instrumentarium Dental Co., Tuusula, Finland) and  ITI implants (3.8mm x15mm) were used. A 2:1 mixture of plaster of Paris and saw dust was used to make the bone blocks. One to three implants were implanted using three types of bone blocks. Single bone block implant was placed at the center, while multiple implant (two or three bone blocks) were placed 10mm away from, and parallel to, the center of each implant. Then, reference image for VT image was then created using 5, 7, 9 or 11 images. The quality of each image was analyzed by 5 oral radiologists using  5-point scale and the scores were recorded for each VT images. The area surrounding bone implant was assessed on the VT image and each evaluator rated how confidence they were with the number of bone implants they was on the same image as follows: 1 Not confident; 2 Somewhat not confident; 3 Indecisive; 4 Somewhat confident; or 5 Confident. The results of all bone blocks scores were analyzed using one-way analysis variance (ANOVA) for each implant in the area between each VT image modality.

Result:

The assessment of peri-implant anatomy using VT with a small number of reference images was sufficient to distinguish single bone block. However multiple implanted bone blocks tended to require more reference images compared single implant.

Conclusion:

In this study, VT produced variable images when fewer than 11 reference images were used, and suggested that VT has positive contribution to post-operative radiographic examination by using low irradiation dose.