The theory we discussed with the lower cavity preparation applies to all teeth. Here we’ll go over things unique to the upper molar.

Occlusal View

Because of the presence of the oblique ridge, the outline form of the occlusal segment is unique. In an ideal preparation, the occlusal segment is divided into two separate preparations: Mesial and Distolingual segments. This means that we must somehow preserve the integrity of the oblique ridge.

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Lingual View

Just go along the distolingual groove keeping your bur more towards the distal. Think of it as removing the groove with the most mesial part of your bur, and the rest of the reduction will be done from the distal.

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Mesial View

Here the linguogingival line angle is acute, and the buccogingival line angle is 90 degrees.

This is opposite from the lower first molar, where the buccogingival line angle is acute, and the linguogingival line angle is 90 degrees or slightly less.

This is because the upper molar is slightly buccally inclined. When working on the occlusal segment, this is almost negligible, but must be taken into consideration in the mesial box.

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