Author – Shalin Raj Shah, DMD, MS
A smile can say so much about a person’s unspoken thoughts: joy, happiness, pride, love, amusement, interest, care, and kindness to name a few. The composition of that smile can also reveal so much about the individual: confidence, meticulousness, compassionate, successful, empathetic. It is why we as architects of that lifelong smile have a great responsibility to ensure that our planning, treatment, and end results reflect what so many people share with the world. Everyone’s smile should reflect their greatness and beauty and be built upon a sound infrastructure. Today, we continue on with the #TheMelinaProject and discuss the finer elements that go into the beginnings of diagnosing space requirements, and we provide an introductory look into diagnosing Melina’s other two planes of space: sagittal and vertical.
Melina has completed a key change in her orthodontic treatment: the correction of the transverse. In previous discussions, we reviewed the diagnosis behind her transverse skeletal discrepancy and provided some insight into how the discrepancy was corrected by way of TAD-supported expansion. This change is important because it sets the foundation for so many things, including her bite and smile architecture in addition to stability and risk of relapse mitigation.
It is important to understand from our previous discussions that we do not expand for space requirements (I.e. crowding of teeth), but instead expansion is employed when a true maxillo-mandibular skeletal discrepancy exists. This being said, expansion does influence arch circumference available as the arch changes. Furthermore, that change must be well understood and in a quantifiable manner so it can appropriately be considered in the overall plan. Although our pre-treatment space analysis technique is more complex than what is shown below, the simplified table demonstrates the impact that skeletal and dental transverse changes have on the overall diagnosis and treatment plan. The other values in the table will be completed in future discussions.
You will note that we assessed the net transverse skeletal change at +7mm (increasing arch circumference available). Our total skeletal transverse correction for Melina resulted in a 7mm sutural change, which increases the arch perimeter 1:1. This is the reasoning behind the +7mm. Additionally, this pre-treatment workup demonstrates that we must have a reasonable understanding of what our orthopedics can accomplish at the different ages our patients present. Although it is preferred we see our patients at the age of 7 to influence these changes more predictably, it is not always the case.
Beyond the skeletal change, there is a dental transverse change that must be accounted for. The dentition will often naturally compensate for an underlying skeletal discrepancy and forecasting the correction of those inclined teeth plays a large role in space management. It is incumbent on all clinicians to have a predictable method to objectify and quantify the change of the inclination of the posterior teeth to their final, treated position. This forum is not ideal to present our dental transverse analysis, but what you can note is that our projected finish of the dental transverse changes resulted in an additional 2mm of crowding in the maxilla and 1.5mm of spacing in the mandible (see simplified space analysis table above). This will become important in our overall case workup.
Now that we have understood the implications of our transverse correction, we look at the management of the other two planes of space: sagittal and vertical. Both the skeletal and dental components of these planes of space require detailed attention just as our transverse dental and skeletal changes.
The beginning of any skeletal and dental change in the sagittal and vertical requires that we define what our initial treatment position is (as defined by the mandible). There are many discussions about mandibular positions, but our treatment plan is always formulated with a seated condylar position (SCP). Since the occlusion is always changing throughout treatment, we need a reliable, stable, healthy, and repeatable position to both diagnose and treat our case to. If we are to plan from a SCP, then how do we know what that position is and what sagittal and vertical considerations result from that new position?
Next time, we will discuss how to define and simulate the SCP, introduce the value of a growth prediction, and begin discussions on forecasting final outcomes. Eventually, this will lead to a comprehensive plan that can be communicated to the patient and team all the while naturally revealing the mechanics required to support execution of the plan. Today we leave you with the question of which Melina would you want to see when diagnosing her case and formulating a treatment plan?
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