J Korean Acad Prosthodont.  2010 Oct;48(4):294-300. 10.4047/jkap.2010.48.4.294.

Accuracy of 5-axis precision milling for guided surgical template

• Park JM
• Yi TK
• Jung JK
• Kim Y
• Park EJ
• Han CH
• Koak JY
• Kim SK
• Heo SJ

• KMID: 2195548
• DOI: http://doi.org/10.4047/jkap.2010.48.4.294

Abstract

PURPOSE
The template-guided implant surgery offers several advantages over the traditional approach. The purpose of this study was to evaluate the accuracy of coordinate synchronization procedure with 5-axis milling machine for surgical template fabrication by means of reverse engineering through universal CAD software.
MATERIALS AND METHODS
The study was performed on ten edentulous models with imbedded gutta percha stoppings which were hidden under silicon gingival form. The platform for synchordination was formed on the bottom side of models and these casts were imaged in Cone beam CT. Vectors of stoppings were extracted and transferred to those of planned implant on virtual planning software. Depth of milling process was set to the level of one half of stoppings and the coordinate of the data was synchronized to the model image. Synchronization of milling coordinate was done by the conversion process for the platform for the synchordination located on the bottom of the model. The models were fixed on the synchordination plate of 5-axis milling machine and drilling was done as the planned vector and depth based on the synchronized data with twist drill of the same diameter as GP stopping. For the 3D rendering and image merging, the impression tray was set on the conbeam CT and pre- and post-CT acquiring was done with the model fixed on the impression body. The accuracy analysis was done with Solidworks (Dassault systems, Concord, USA) by measuring vector of stopping's top and bottom centers of experimental model through merging and reverse engineering the planned and post-drilling CT image. Correlations among the parameters were tested by means of Pearson correlation coefficient and calculated with SPSS (release 14.0, SPSS Inc. Chicago, USA) (alpha = 0.05).
RESULTS
Due to the declination, GP remnant on upper half of stoppings was observed for every drilled bores. The deviation between planned image and drilled bore that was reverse engineered was 0.31 (0.15 - 0.42) mm at the entrance, 0.36 (0.24 - 0.51) mm at the apex, and angular deviation was 1.62 (0.54 - 2.27)degrees. There was positive correlation between the deviation at the entrance and that at the apex (Pearson Correlation Coefficient = 0.904, P = .013).
CONCLUSION
The coordinate synchronization 5-axis milling procedure has adequate accuracy for the production of the guided surgical template.

Keyword

Computer-guided surgery; Implant surgical template; Milling machine; Reverse engineering

MeSH Terms

Chicago
Collodion
Cone-Beam Computed Tomography
Gutta-Percha
Mandrillus
Models, Theoretical
Silicones
Collodion
Gutta-Percha
Silicones

Figure

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  Fig. 1. 3D images of gutta percha stoppings rendered on implant planning software. A: GP cylinders without master cast layer, B: master cast with virtual planning for guided template.

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  Fig. 2. 5-axis milling machine used in this study. A: Description of 5-axis path, B: Enlarged view of 5-axis milling machine. ① Experimental model, ② Platform for synchordination, ③ Synchordination plate.

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  Fig. 3. Overview of milling procedure. A: hidden dental stopping, B: milling with 3.28 mm drill, C: remaining stopping, D: merging and comparative analysis.

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  Fig. 4. Reverse engineering procedure for determining center points of upper and lower part of the objects. A: Virtually planned object, B: Actual drilled bore.

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  Fig. 5. Merged image on image analysis program.

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  Fig. 6. Mean deviation between planned object and actual object (n = 100).

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