Find the front, then follow the curve
A dental arch is the upper or lower dental row. Crowding involves insufficient room, with teeth overlapping or turning. Spacing means gaps between teeth.
Both drawings below use an upper row viewed from above. Front and back stay in the same places. The curved guide helps you follow the row; it is a drawing aid, not a proposed final position.
Sources: AAO glossary; AAO bite guide
Worked reading A: follow the overlapping outlines
Drawing A: trace the individual outlines
The marked pair crosses at the front of this model.
A
Top view
Upper row
Back
Front
Follow these two outlines
Begin at the front marker. In drawing A, one central outline is turned and overlaps its neighbour. Following each separate outline explains why the dark shared area is two shapes crossing in the drawing, rather than one shape.
The useful reading is local and specific: "I can point to the overlapping pair at the front of this model." The label names that arrangement. It does not tell a story about why it happened or suggest which way anything should move.
Now look at the whole drawing. There is only one row. You cannot read a relationship to an opposite row that has not been drawn. Keep that second question for a paired view, as the next lesson demonstrates.
Worked reading B: keep the spaces separate from the shapes
Drawing B: follow the empty intervals
The marked spaces lie between separate front outlines.
B
Top view
Upper row
Back
Front
Follow these spaces
Drawing B keeps the same viewpoint and curve, with white intervals between front outlines. Trace one shape, cross an empty interval, then follow the next. Each gap belongs between neighbours, outside their outlines.
A complete reading would be: "The spaces I am describing are between neighbours in this upper row." That is more precise than saying the whole drawing looks different. It also identifies which view supplied the information.
A and B are separate fictional models. They are not before-and-after pictures, a treatment sequence or competing results. Compare the visible relationships, rather than choosing the drawing you think you should resemble.
Add the second row when the question changes
You have now followed an overlap and a gap, located each within a named row and kept the viewpoint consistent. The next chapter adds the opposite row and asks a different set of spatial questions.
If your own discussion is about an assessment or existing dental work, the adult assessment guide explains that wider conversation. This chapter stays with reading the model.