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This technique allows performing necessary orthodontic 
analysis of mutual teeth location. An orthodontist can define 
perfect teeth arches mutual position and to plan a treatment (to 
design a set of wires). Also this technique allows controlling the 
process of orthodontic treatment. 
2. EXISTING TECHNIQUES 
Orthodontia is a science which determines the perfect position 
and orientation of teeth and develops techniques for moving 
teeth to this perfect position. Unfortunately it is an often case 
when teeth in a teeth arch are not located perfectly. So the task 
of orthodontia is to set teeth in a perfect position. 
Different techniques were developed to correct teeth position by 
applying given forces to teeth. For producing such forces wires 
and brackets or kappa are traditionally used. For successful 
treatment planning accurate data about teeth arch is needed. 
Traditional techniques use plaster mould of teeth arch for 
treatment planning. In most cases teeth dimensions needed for 
treatment planning are determined by a ruler and a size of 
working wire is chosen from a set of three or four standard 
types. Unfortunately it sometimes causes problems in treatment. 
To overcome these problems some groups develop individual 
brackets and kappa which are designed for determined person. 
So Align Technology Inc. proposes a set of invisible kappa 
produced using teeth arch 3D model. Every kappa is used.on a 
planned stage of treatment corresponding to the current position 
of teeth. 
3M Company develops Invisible Incognito™ Orthodontic 
Braces. A set of lingual individual brackets and wires are 
offered for a staged treatment. lindividual brackets are created 
using accurate 3D models of tooth surface. Such an approach 
provides better contact between a tooth and a bracket and 
therefore less probability of a bracket getting off the tooth. But 
in this technique manual stage exists on which plaster mould is 
physically divided into separated teeth (with the help of a saw) 
and then orthodontist places separate teeth to a perfect position 
manually using cement. 
These techniques use 3D teeth arch models for treatment 
support. But a lot of hand work still is to be done by an 
orthodontist. 
Most of existing techniques use standard wires and standard 
brackets for creating forces which are to move tooth in a correct 
position. The disadvantages of such a technique are complex 
procedure of accurate bracket positioning on a plaster mould of 
a teeth arch and then accurate translation this brackets from 
plaster mould to real teeth arch. 
The standard procedure of setting up a standard wire includes 
the next stages: 
e Producing plaster copy of teeth arch 
e Positioning standard brackets on the plaster copy of 
teeth arch (Fig. 1.) using special device (articulator) 
which provides required bracket position on a tooth for 
producing correct forces for required tooth movement 
e Making a silicon kappa containing installed brackets 
in required position 
565 
e Placing the brackets on a patient's teeth using this 
kappa which provide accurate brackets transfer to a given 
position for every tooth 
e Placing a standard wire into the brackets 
  
Figure 1. Plaster teeth arch copy with attached brackets 
The disadvantages of traditional technique are 
e The problems with installing standard wire in 
bracket’s slot because of complex teeth position and 
orientation. 
e Weak control on forces produced by standard wire 
sometimes resulting in tooth over shifting. 
The new image-based technique is developed for overcoming 
these problems. It improves the existing one by introducing 
photogrammetric techniques for accurate 3D model producing 
and designing individual wire. 
The proposed technique includes the next stages: 
e Producing plaster copy of a teeth arch 
e Positioning standard brackets on teeth using special 
device (articulator) which provides required bracket 
position on a tooth for producing correct forces for 
required tooth movement 
e Producing accurate 3D model of teeth arch plaster 
copy 
e Segmenting obtained 3D model into separate teeth 
and gum 3D models 
e Positioning teeth 3D models in a required (correct) 
position according orthodontics’ requirements 
e Determining slot position for every bracket using 
image-based technique for spatial slot position 
e Generating CAD model of an individual wire which 
accurately goes through the brackets slots 
e Making a silicon kappa containing installed brackets 
in required position using 3D model of teeth arch with 
brackets 
e Placing the brackets on a patient's teeth using this 
kappa which provide accurate brackets transfer to a given 
position for every tooth 
e Placing an individual wire into the brackets 
e Image-based monitoring of treatment process 
Below the detailed description of proposed technique is given.