(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 molar.
- Class II: MB cusp of the max 1st molar is in front of the buccal groove of the mandibular 1st molar.
- Division I: upper incisors are protruded (out).
- Division II: upper incisors are retruded (in).
- Class III: MB cusp of the max 1st molar is behind the buccal groove of the mandibular 1st molar.
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). The questions could be asked in a case study with images or can 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. I hope this makes sense! Please look at the image created for today’s post and try to draw it yourself.
I would like to link 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, so when it comes out, I will send another email. Keep studying for the dental hygiene board exams (NBDHE, NDHCE, CSCE, WREB, CRDTS). You are getting closer and closer to the finish line!
Mini Boards Reviews for the National + Local Anesthesia Dental Hygiene Boards. Weekly Sample Questions at www.StudentRDH.com. Find COMPLETE review courses too. “I wish I did not spend money on other review courses!” – Bethany, Bergen CC, March 2016