Available online 9 April 2019
Abstract
Statement of problem
Conventional
radiographic methods are widely used to evaluate the clinical accuracy of implant position. However, such methods require a second
computerized tomography (CT) scan and manual registration between presurgical and postsurgical CT data. The alignment errors cannot be calculated.
Purpose
The
purpose of this clinical study was to introduce a completely digital
registration method to evaluate the clinical accuracy of implant
position. The digital registration method was then compared with the
radiographic method in evaluating accuracy. Some of the alignment errors
produced in the digital registration procedures were recorded.
Material and methods
A total of 32 implants from 19 patients with sufficient
bone volume were enrolled in the study, and all implant surgeries were conducted by one experienced practitioner. Before the surgery, a
cone beam computerized tomography
(CBCT) scan was made for each patient along with a diagnostic
impression to design the ideal implant position using the Simplant
software. After the surgery, the postsurgical implant position was
determined using an optical scan of the
dentition
cast and a series of custom registration models (the digital
registration method). A simulated cylinder was designed using the
Geomagic Studio software to represent the implant, and the deviation of
the ideal and postsurgical implant position was calculated. The accuracy
evaluated by the 2 methods was also compared. The parameters of the
entrance point, apical point, and axis were recorded for each implant. A
part of the alignment errors in the digital registration was calculated
automatically and recorded. One sample
t test and paired
t test were conducted by using a statistical software program.
Results
The
mean deviation between the ideal and postsurgical implant positions
evaluated using the digital registration method was 0.84 ±0.57 mm for
the entrance point, 1.03 ±0.78 mm for the apical point, and 4.52 ±2.37
degrees for the angulation. No significant difference was found between
the accuracy evaluated by the digital registration method and the
radiographic method (P>.05). In the digital registration
procedure, the alignment error was 0.03 mm for the registration model
and 0.29 mm for the dentition. Significant differences were found in the
alignment procedure of the impression cylinder (P<.001) and dentition (P<.001).
The average positive and negative errors were +0.09 and −0.19 mm for
the simulated cylinder of the ideal implant and +0.08 and −0.15 mm for
the simulated cylinder of the postsurgical implant.
Conclusions
The
precision of the digital registration method could be accepted in
clinical applications. No significant difference was found between the
digital registration method and the radiographic method in evaluating
the clinical accuracy of the implant position. The digital registration
method was able to control and minimize the alignment errors produced
during data processing.
Comments