What is the difference between Class I and Class II outline forms?

• A. Class I is pits/fissures on posterior occlusal surfaces; Class II extends onto proximal surfaces with a proximal box.
• B. Class I is on anterior teeth only.
• C. Class II is only pits/fissures.
• D. There is no difference.

Answer: (A)

The key distinction is which surfaces are included in the preparation. Class I outlines are confined to pits and fissures on the occlusal (chewing) surfaces of posterior teeth (and sometimes buccal or lingual pits on those teeth), with no involvement of the proximal surfaces. Class II outlines, on the other hand, extend onto a proximal surface and include a proximal box to restore that side of the tooth and preserve the contact with the neighboring tooth.

So, the best answer captures that Class I is occlusal pit/fissure preparation, while Class II adds a proximal extension with a box. The other statements don’t fit because they misstate where Class I or Class II occur or imply there’s no difference between them.