A large part of successful outcomes with the Invisalign system comes from understanding the force features and implementing them appropriately. In many cases, multiple tooth movements could use different optimized force features. The treatment design software has a set of rules that prioritize the recommended optimized force features. When we understand these hierarchy rules, we can better design the appliance to deliver the desired movement’s best force systems.
SmartForce Feature Hierarchy
When we move teeth, we need proper force systems to allow the movement to be appropriate and predictable. Movement thresholds trigger optimized features and force systems to deliver an effective appliance. In multi-directional movements, treatment software must decide what force features to add to the treatment plan. The competing features that have met their thresholds go through a decision tree in which the optimized force feature takes priority. These hierarchy rules are behind the aligner forming elements and optimized attachments in the customized digital treatment plan.
The high-level hierarchy in the Invisalign System first prioritizes multi-tooth force features, which include the G6 first bicuspid extraction features and the multi-tooth extrusion movements. The second priority goes to root movements in the mesial-distal direction. Third, is single tooth vertical and rotation. The hierarchy’s fourth priority is Anchorage for intrusion and the support provided to adjacent teeth. The power ridge feature for lingual root torque receives the fifth and lowest priority in the hierarchy rules.
The software and technician select these priorities to prepare the initial ClinCheck a doctor will review. In the past, when a treatment plan has competing features, we would request changes to the technician in writing. With the launch of ClinCheck LiveUpdate, we can easily change the selected force feature.
ClinCheck Update
The latest update in the ClinCheck planning software now allows removing attachments and selecting from a drop-down menu the desired force feature. You can click on the hexagonal attachment and drag it into a tooth that has met a threshold movement that can implement an optimized feature. Or, you can select a currently optimized attachment and request a change to another feature that has met the threshold in the final tooth position.
Here is an example of an upper left central incisor that meets two force thresholds and the hierarchy rules allow the root control attachment to change to an extrusion design.
In the same patient, we can change the upper left lateral incisor force feature from an optimized extrusion design to either optimized retention or root control. With the optimized root control attachment, we can also select a single regular size or a single largest that fits.
