1. Splash
Digital orthodontics
Peter Søndergaard, 3Shape A/S

2. What is orthodontics (problems, brackets, aligners)
Traditional orho (gypsum scans, direct bonding, )
Digital ortho (scanning, aligners by moving teeth)
Simple vs realistic aligner construction
Osteoclas

3. Orthodontics: Definition
The first specialty created in the field of dentistry
The area is concerned with the diagnosis, prevention and correction of mal-positioned teeth and/or jaws
Derived from the Greek words orthos ("correct", "straight") and dontia ("teeth")

4. When do Patients typically need an Orthodontist?
Functional Problems (e.g. problems chewing the food properly)
Esthetic Problems (of all kinds)
Problems with the Temporomandibular Joint (TMJ)

5. Esthetic Problems: Examples
Missing
teeth
Crowding
Unwanted
profile
Spacing

6. Tooth Movements Crown tipping Root tipping Torquing Rotation
Translation
Extrusion
Intrusion

7. How does tooth movement work?

8. What kind of Treatments do an Orthodontist offer?
Metal Braces
Ceramic Braces
Removable Braces
Functional Appliances
Aligners
Lingual Braces
Retainers
Mouth Guards
And more !

9. How Braces work

10. How Braces work
Fundamental idea: The arch wire will return to its original shape, and apply enough force to move the tooth. 1 N of force can move a tooth sideways

11. How Aligners Work
Takes you from the current situation (malocclusion) – to the ideal setup (straight teeth)
Typically involve (slightly different) aligners in a set – which you exchange with an interval dictated by the doctor
Treatment typically takes between months

12. Simple digital workflow for making aligners
Step 1: Scan
Step 2: Segment
Step 3: Model individual teeth
Step 4 : Move teeth models
YouTube Virtual Setup
Step 5: Export to STL
Step 6: Print and press

13. Problems arise
Aligners are made of plastic, not metal, so they apply less force
The contact points of the aligner are not as well defined as for brackets
Results: Aligners treatments made using this method are sometimes ineffective

14. Solution
The problem is that the aligner is designed based on where we want the tooth to move
We should instead design the aligner to produce the force necessary to move the tooth to the correct position
For this, we need to know the correct force field to obtain a desired position
Solve the simpler problem first: Given a force field, how does the teeth move?

15. Modeling tooth movements
Tooth movements depends on:
Force vector applied
Area of bone/periodontal ligament
Thickness of bone around the tooth
Bone age of the patient (does s/he grow new bone)
Collisions of the crowns
Collisions of the roots
...

16. Which data does an orhodontist make his decision?
Physical impression of the patient
Medical history, also of the family
Facial photos
X-ray´s:
Sideways
Panoramic
CBCT (hard cases)
Intraoral scan

17. What data do we have to work with?
Surface scans
Panoramic 2D x-ray

18. CBCT
CBCT (Cone-beam computed tomography): 3D volumetric