Treatment planning tools (Digital Smile Design)

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Part 2. Treatment planning tools:

There are multiple tools that can aid in the treatment planning process. Among the most important ones are:

1. Digital Smile Design (DSD):

DSD is a relatively new approach. it works as a reference for the planned treatment, it's mainly used is to understand and visualize the treatment requirements and outcome that might otherwise be overlooked by the dentist, lab technician or patient. It is an excellent communication tool with the patient and lab technician [13].

After making the required clinical and radiographic examinations (restorative, periodontal and occlusal). The DSD process is started by taking multiple digital photographs like a full face at rest position, full face with a wide full smile with teeth apart and a retracted view of teeth apart. After that, it is possible to use specialized DSD applications or simply an image editing or presentation application (examples: Apple Keynote or Microsoft Powerpoint) to:

1. Align the full face picture with the horizontal plane by marking it with a line that is usually perpendicular to the inter-pupillary line. Additionally, mark a vertical line for the facial midline.
2. Notice any shifting or canting in the gingival or incisal planes. Next, note if facial midline corresponds to the maxillary and mandibular dental midline. In this case there is a 0.25 - 0.5 mm shift of the dental midline, and canting in the incisal plane.
   
   
3. Calibrate the digital ruler by measuring a specific area on the patient’s mouth or cast (like the length or width of the central incisor). Then, calibrate the digital ruler to give the same reading on the digital photograph. Now you can measure any area in the photo, remember that the measurements are perspective (such as the perceived width of the canine rather than the actual width) and are valid for the calibrated picture only.
   
   
4. Analyze the individual dental dimensions and RED proportions in the frame of the discussed esthetic principles like the location of the incisal edge and gingival zenith and RED proportions…etc. The red cells indicate unfavorable dimensions, affecting the smile esthetics.
   
   
5. Draw an outline of the desired dental morphology, dimensions and RED proportions. It is possible to draw the outline directly or use one’s own library of pre defined shapes of desired teeth morphology. Furthermore, it is possible to fill these outlines with teeth texture to improve the visualization.
6. Notice how the midline shift and the incisal plane canting as well as the individual teeth dimensions and RED proportions from the previous table are all favorable and the smile is designed accordingly.

If the chosen treatment is orthodontics (recommended): Discuss the expected results with the patient and show the pictures, keeping this smile analysis as a reference for the ongoing treatment goals. On the other hand, if the chosen treatment is prosthodontics: Discuss the results with the patient and lab technician. Once approved, the lab will transfer this 2D blueprint to the 3D dental casts. This should be a reference to the treatment, such as the amount of required gingivectomy or the dimensions of each tooth and their relation to each other [14, 15]

Another new and useful tool that can be used in conjunction with DSD is videotaping a short clip of the patient talking, smiling and at rest from different angles, this is used for evaluating teeth visibility and their relation with the lips, it is also useful a reference for the lab technician while fabricating the ceramic prosthesis and as a record for the patient [3].

2. Composite mock-up:

It is possible to directly place and shape composite. This is done on a dried tooth without bonding to facilitate removal. This method is excellent for communicating directly with the patient. However, it requires certain level of skills from the dentist and is not applicable in cases where heavy preparations are required to visualize the results. Lastly, an impression of the mock-up can be taken as reference [3].

3. Diagnostic wax up:

Diagnostic wax-ups on an articulator provide the closest depiction of the final results, with the ability to test the static and dynamic occlusion before fabricating the final prosthesis. Furthermore, They provide a great opportunity for the dentist, lab technician and patient to familiarize themselves with the case.

It is also possible to take an impression or make a suck down of the wax-up model and try it in-mouth. It is recommend to cut out the buccal part of the silicon index that covers the gingiva to facilitate the removal of the resin during its curing and gain optimal results (Figure 1) (Lazar, 2016). However, certain amount of reduction in some cases is required to fit the impression. Furthermore, it is possible to make modifications directly on the try-in resin followed by an impressions to record any desired modifications [16].

Lastly, it is very useful to use the temporary mock up as a guide for reduction. This is done after placing the approved temporary crowns/veneers on the teeth. Then, the teeth are marked for the depth of the required preparation by the required thickness depending on the treatment conditions, this method guarantees minimal preparation [3]. 

Modified impression of the wax mock up can be used to fabricate chair-side temporary restoration.

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References

1. MacKenzie, L. Tooth Morphology. [Lecture]. Smile-On Education Support Platform. 2015.
2. James L Fuller, Gerald E. Denehy, Thomas M. Schulein. Concise dental anatomy and morphology 4th edition. Year Book Medical Pub. 2001.
3. Gürel, G. The Science and Art of Porcelain Laminate Veneers. Quintessence publishing. 2003.
4. Kakar, A. Interdisciplinary Treatment- Periodontics [Lecture], Smile-on Education Support Platform. 2016.
5. Yu-Jen Wu, Yu-Kang, Shay-Min. The Influence of the Distance from the Contact Point to the Crest of Bone on the Presence of the Interproximal Dental Papilla. 2003.
6. Pascal Magne, PD, Dr Med Dent, German O. Gallucci, DMD and Urs C. Belser,.Anatomic crown width/length ratios of unworn and worn maxillary teeth in white subjects، 2003.
7. PRESTON, J. The Golden Proportion Revisited. Esthet Restor Dent, 5(6), pp. 247-251. 1993.
8. Levin,E. Dental Esthetics And The Golden Proportion. The journal of prosthetic dentistry 40 (3), St Louis, Mosby: Academy of Denture Prosthetics and other prosthetic dentistry societies. 1978. pp.244-252 
9. Hilton, T., Ferracane, J. and Broome, J. Summitt's fundamentals of operative dentistry. 2014. Ch 6, 16.
10. Vanini, L. Determination and communication of color using the five color dimensions of teeth. Practical Procedures and Aesthetic Dentistry. 2001
11. Brambilla, G. Advanced Anterior Composite Techniques. [Webinar] Smile-on Education Support Platform. 2015.
12. Ward, D, Proportional smile design using the recurring esthetic dental(Red) proportion. Dental clinics of North America pp.143-155, Philadelphia: Philadelphia, Pa. : Elsevier Health Sciences Division. 2001.
13. Coachman, C. Ricci, A. Calamita, M. A Digital Tool for Esthetic Evaluation, Team Communication and Patient Management. 2012.
14. Coachman C, Van Dooren E, Gürel G, Landsberg CJ, Calamita MA, Bichacho N. Smile Design: from digital treatment planning to clinical reality. In: Cohen, M. Interdisciplinary treatment planning, Vol. II: comprehensive case studies. 2011
15. Bob Mclelland Esthetic analysis, planning and communication.  [Seminar] Manchester university restorative and aesthetic masters program. 2nd Residential. 2015.
16. Bob Mclelland. Lab communication and prototype fabrication [Seminar] Manchester university restorative and aesthetic masters program. 2nd Residential. 2015.