Marking the Curves & Setting Up the Wax Rim
Selecting the next option “Mark Occlusal Curves” will open the editing screen seen below. This stage will instruct you to outline two occlusal arches that will be used to define and generate a strip of wax or a wax rim that will be used to establish the occlusion of the appliance.
A new menu in the top left corner (pictured above) will prompt you to draw these curves. The first will be a Maxillary curve. This curve should be drawn along the outer cusps of the maxillary teeth. If you prefer a thinner wax rim this line can be drawn slightly inside the cusps, however the goal is to ensure the active cusps of both arches will fall slightly inside the wax rim. A little extra wax on either side adds more occlusal surface and gives more room for the edge of the appliance to be smoothed down later on.
Clicking Mark Mandibular will change the view to the mandibular arch. This curve can be drawn along the lingual cusps of the lower teeth. This can also vary with preference, however be sure to mark the anterior teeth down by the roots. Doing this will help add a deeper rim that will be used to create the mandibular stop later on.
Do not worry about making the curves perfect on the first try. The third stage “Curves Only” is when you will be able to freely edit the initial curves. By clicking and dragging the points, the lines can be edited in the same way as when drawing the splint outline. After slightly smoothing the curves to a more uniform horseshoe, you will want to rotate the models so that you are viewing them from the side, as seen above. The initial marking of the curves will snap to the height of the tooth. From this view the lines can be smoothed out to ensure a uniform thickness all the way around. Note that the mandibular curve (pink) dips noticeably in the anterior. That ‘drop’ can be smoothed but keeping those anterior points so low is what is going to provide the extra wax for the mandibular stop.
The Menu on the top right of the window (pictured left) can be used to preview and alter the wax rim and curves designed at this stage. Clicking “Calculate Rim” will generate the rim based on the current curves. The rim will be semi transparent.
To adjust the transparency of the rim you can either click and drag in the Opacity bar listed at the top of Rim Options, or double click to type in a value.
One will be completely opaque while zero is entirely transparent.
The rims pictured below are set to an Opacity of 1.
The rim pictured above on the left is a rim based solely on the curves. This is not a bad rim, however there is a lot of unnecessary wax in front of the mandibular teeth. To save some sculpting and scraping later on we can use the option directly below the Opacity slider, the “Rim Flare” option. In this example the Rim Flare is set to 20. Setting the flare to -20 would have tilted the wax down in the anterior.
Once you are satisfied with the rim you will select “Commit” from the top left corner menu (pictured above, right). This will exit the curves mode and clicking “Join Wax Rim” just below the “Mark Occlusal Curves” option will fuse the rim to the shell, if it is not done automatically.