Tooth preparation is a fundamental procedure in prosthetic dentistry,
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with improper tooth preparation leading to treatment failure.1
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Conventionally, an elastomeric putty index has been used to evaluate the quality of preparation.1
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An index is obtained before tooth preparation, after which it is cut cross-sectionally and seated on the prepared tooth. The amount and quality of tooth preparation are then evaluated. However, this method is limited in that only a small number of sections can be obtained, and sectioning is irreversible.With the development of digital devices in dentistry, metrology software programs have been used to assess differences.
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However, until recently, the scanned data files needed to be exported from the intraoral scanner software program and imported into the metrology software program as the 2 programs were not compatible. A digital approach, which provides visual insights and evaluation of differences and enables an accurate measurement of the amount and quality of a tooth preparation with an intraoral scanner and its built-in superimposition and a metrology software program is described. The method saves time and can be easily done at the chairside as it uses internal software tools and eliminates the need to extract the scanned data files. The evaluation of a rest preparation is shown as a representative example of an intracoronal preparation, and the assessment of a complete crown preparation is shown as an example of an extracoronal preparation.Technique
- 1.Scan the teeth before and after tooth preparation by using an intraoral scanner (TRIOS 3; 3Shape A/S) (Fig. 1)
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Figure 1Scanning teeth with intraoral scanner. A, Before rest preparation. B, After rest preparation. C, Before complete crown preparation. D, After complete crown preparation. - 2.Apply the TRIOS Patient Monitoring tool to verify the accuracy of tooth segmentation and approve the segmented outcomes if accurate.
- 3.Apply the “tooth comparison” function and adjust the range of the scale bar (Fig. 2). The amount of preparation can be measured by placing the mouse cursor on the area of interest. Additionally, draw a line around the prepared tooth to obtain a cross-sectional view. The amount of preparation can be measured by selecting 2 points on the cross-sectional view.
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Figure 2Evaluation of quality and amount of preparation. A, Application of “tooth comparison” function by using built-in software program of intraoral scanner for rest preparation case. Scale bar adjusted as needed. B, Cross-sectional view of superimposed scan data for rest preparation. C, Cross-sectional view of superimposed scan data for complete crown preparation.
References
- Mosby. Contemporary fixed prosthodontics.5th edition. Elsevier, St. Louis, MI2015: 169-208
- Preparing teeth to receive a removable partial denture.J Prosthet Dent. 1999; 82: 536-549
- McCracken's removable partial prosthodontics.13th edition. Elsevier, St. Louis, MI2016: 56-66
- An in vitro assessment of tooth preparation for porcelain veneer restorations.J Dent. 1995; 23: 165-170
- Tooth preparation techniques for porcelain laminate veneers.Br Dent J. 2000; 189: 260-262
- Full arch scans: conventional versus digital impressions–an in-vitro study.Int J Comput Dent. 2011; 14: 11-21
- Influence of abutment tooth geometry on the accuracy of conventional and digital methods of obtaining dental impressions.J Prosthet Dent. 2017; 118: 392-399
- Evaluation of the accuracy of 7 digital scanners: An in vitro analysis based on 3-dimensional comparisons.J Prosthet Dent. 2017; 118: 36-42
- Effect of scan pattern on complete-arch scans with 4 digital scanners.J Prosthet Dent. 2020; 123: 85-95
Article info
Publication history
Published online: May 10, 2020
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© 2020 by the Editorial Council for The Journal of Prosthetic Dentistry.
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