Abstract
Success of dental implant treatment is related to accurate placement, such as implant location and/or direction. To determine optimal placement of implants, computed tomography(CT)with a diagnostic stent is used. Then, a surgical template is made with modifications of the location and angle for implants in the CT images.
The purpose of this study was to evaluate the validity of imaging diagnosis using CT in implant design. Differences between the planned placements of the implants, based on measurements of distances and angles before and after CT imaging,were evaluated.
Subjects included 24 patients, with a mean age of 53.8 years. The total number of mandibular implants was 87, classified into anterior and molar regions based on the site of the mental foramen.Thirty-four of 36 anterior implants were treated with overdentures, and the other two implants received a crown prosthesis. All 51 molar implants were placed on the crown prosthesis.
In 18 implants(50.0%) of the anterior implants,the distance was modified a mean of 2.1mm;10(19.6%) of the posterior implants were modified a mean of 1.9mm. Although the rate of modification was significantly different between anterior and posterior implants, the means were not.In the designed angulation,83.3% (n=30) of the anterior implants were modified, with a mean of 10.9 degrees;54.9%(n=28) of posterior implants with the mean of 5.9 degrees. The difference between anterior and posterior implants was significant for both rate and angle of modification.
In conclusion, we found that presurgical design using a working model had its limitations, and CT was essential to determining the optimum positions and angulations of implants in the mandibular anterior region.
