Q: According to the image, the patient has which class of malocclusion (G.V. Black)?
(A). Class I
(B). Class II
(C). Class III
When evaluating occlusion, Angle’s Classification is often used. This classification is based on the relationship between the mesiobuccal cusp of the maxillary first molar and the buccal groove of the mandibular first molar.
- Class I: MB cusp of the max 1st molar fits in the buccal groove of the mandibular 1st
- Class II: MB cusp of the max 1st molar is in front of the buccal groove of the mandibular 1st
- Division I: Upper incisors are protruded (out).
- Division II: Upper incisors are retraced (in).
- Class III: MB cusp of the max 1st molar is behind the buccal groove of the mandibular 1st
Answer: (B). Class II
I need to emphasize that this topic is extremely important to remember. It serves us in the clinic (because we are always asked by our instructors what type of occlusion the patient has) and also for the dental hygiene board exams (NBDHE, NDHCE, CSCE, WREB, CRDTS). Questions about this topic might be asked in a case study with images or might also be descriptive.
Many students confuse the “upper mesiobuccal cusp” and the “lower mesiobuccal groove.” They sometimes do the reverse and see if the “lower cusp” fits into the “upper groove.” No, no! We want the top cusp fitting into the bottom groove for Class I.
Wake Up Memory Technique (WMT) for the dental hygiene boards
Memory tip: draw a shallow hole. Imagine you dug a little puddle in the soil. You can then pour a bucket of water into the hole. The hole corresponds to the buccal groove of the mandibular 1st molar and the water (being poured) corresponds to the upper mesiobuccal cusp. If you misposition the bucket and pour the water in front of the hole, that’s class II. If you misposition the bucket and pour the water behind the hole, that’s class III.
Here’s a link to an article I wrote for DentistryIQ that gives you a little more information about occlusions. I will probably make a YouTube video to explain this concept, and when it comes out, I will send another email with a link to it. Keep studying for the Dental Hygiene Board Exams (NBDHE, NDHCE, CSCE, WREB, CRDTS). You are getting closer and closer to the finish line!
(Disclaimer: StudentRDH is NOT affiliated with the NBDHE, NDHCE, CSCE, CDCA, WREB.)