National Dental Examining Board of Canada (NDEB) Practice Exam

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Master your National Dental Examining Board of Canada (NDEB) exams with our comprehensive practice guide. Achieve excellence in your dental certification with expertly crafted questions and detailed explanations.

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The pulpal floor of a class II cavity is cut perpendicular to the long axis of the tooth EXCEPT in which tooth?

Maxillary 1st molar
Mandibular 1st premolar
Maxillary 2nd premolar
Mandibular 2nd molar

The correct answer is: Mandibular 1st premolar

The pulpal floor of a class II cavity is typically cut perpendicular to the long axis of the tooth to ensure proper retention and resistance form. However, in the case of the mandibular 1st premolar, this approach is not recommended. This is because the pulp chamber of mandibular 1st premolars is notoriously short and wide, making it difficult to achieve ideal retention and resistance form. Therefore, a slight bevel should be created in the pulpal floor of a class II cavity for a mandibular 1st premolar to maintain proper anatomy and avoid pulp exposure. Option A, the maxillary 1st molar, usually requires a similar approach to other class II cavities, cutting perpendicular to the long axis of the tooth. Similarly, option C, the maxillary 2nd premolar, can also be treated with the typical perpendicular cut.