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Properly Developing Line Angles

Precision in line angle development enhances both the aesthetics and functionality of dental restorations

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Figure 1. One of the great secrets of Smile Design is understanding the shapes of
teeth and how the reflective zone of the tooth is defined by the facial line angles.

Line angles refer to the meeting points between two surfaces on a tooth restoration. Properly developed line angles contribute to the overall aesthetics and function of the restoration, ensuring it blends with the surrounding dentition. Achieving well-defined line angles is crucial to the success of dental restorations and key to American Academy of Cosmetic Dentistry (AACD) Accreditation Exam Criteria #43 (“Have the line angles been properly developed?”).

Tips for Developing Line Angles

Following are AACD-recommended strategies to create accurate line angles:

  1. Preparation is key. Before delving into line angle development, ensure you have established the correct outline form and shapes of the restoration. This initial step, especially in terms of contralateral symmetry, sets the foundation for the subsequent line angle work.
  2. Communicate with the ceramist for case types 1, 2, and 3. For certain cases that involve a ceramist, effective communication is essential. Clearly convey your expectations for the line angles, ensuring he or she understands the desired outcomes. Collaborating with the ceramist helps ensure seamless integration between the clinical and laboratory stages of the restoration.
  3. Pencil technique for contour highlighting. Use a pencil or other suitable marking tool to highlight the contours of the restoration. This approach provides a clear visual aid, enabling adjustments and modifications as you contour the restoration. Pay close attention to detail during this phase.
  4. Pay attention to the facially directed and occlusal views. While the facially directed view can demonstrate the line angles effectively, the occlusal view is equally crucial. Capturing a portion of the labial anatomy in the occlusal view provides essential information during evaluation. Regularly assess the labial anatomy from this angle as you progress through contouring and finishing.
  5. Avoid rushing to polishing phase. Ensure that line angles are developed before moving on to the polishing phase. Taking the time to refine the line angles will lead to a more accurate and aesthetically pleasing restoration.
Figure 2. The best way to evaluate the adequate development of these contours is from the occlusal view and the demarcation of the facial line angles and the contact zone that create a triangular facial embrasure. Photos courtesy of Scott Finlay, DDS, FAACD

Properly developing line angles is critical to achieving excellence in dental restorations. It requires meticulous attention to detail, effective communication, and a focus on both facially directed and occlusal views during the evaluation process. By incorporating these tips, dental professionals can confidently meet the #43 criterion and deliver exceptional results in their clinical examinations.


 Examiner Tip

The occlusal view is the go-to shot. The ideal result from well-developed line angles is the subsequent development of distinctive facial embrasures. We want to see the “arrowheads” from tooth to tooth. When working with case types 4 and 5, I like to have a 3D image to see how I am progressing. A scan can provide valuable feedback.

— Bradley Olson, DDS, FAACD


American Academy of Cosmetic Dentistry

aacd.com

800-543-9220

From Decisions in Dentistry. September 2023; 1(8):13.

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