Resumão dos Molares | Anatomia Dental

Summary

This video provides an in-depth overview of molar anatomy, focusing on the differentiation between upper and lower molars. It explores the number and shape of cusps, with the first upper molar typically featuring four or five cusps and a tubercle of Carabelli, while the second may have fewer. Lower molars, such as the first lower molar, often exhibit a distinctive 'W'-shaped groove, while the second lower molar has a more proportional and cruciform groove pattern. The video also covers key traits like occlusal surface shapes, groove patterns, and root structures, offering valuable insights for dental students and professionals.

Takeaways

• 😀 Upper first molars always have 4 cusps, while upper second molars can have either 3 or 4 cusps.
• 😀 Lower first molars usually have 5 cusps, but may also have 4, while lower second molars commonly have 4 cusps.
• 😀 Upper molars have a longer vestibular-lingual length compared to lower molars, which have a greater distal length.
• 😀 The first molar is always larger than the second molar, and the second molar is larger than the third molar, irrespective of the jaw (upper or lower).
• 😀 The vestibular surface of molars is trapezoidal, with the base wider at the occlusal end, while the lingual surface is more prominent in upper molars.
• 😀 A distinguishing feature of upper first molars is the Carabelli tubercle, located on the mesiolingual cusp.
• 😀 Upper second molars, when tricuspidated, lack the lingual sulcus and have a more pentagonal shape.
• 😀 Lower first molars are characterized by a W-shaped sulcus, formed by their five cusps.
• 😀 Lower second molars have a quadrangular occlusal surface and a cruciform sulcus.
• 😀 Upper molars have three roots (two buccal and one palatal), while lower molars have two roots (mesial and distal).

Q & A

What is the main way to differentiate molars based on cusp count?

Molars can be differentiated by the number of cusps they have. The first upper molar always has four cusps, while the second upper molar may have three or four cusps. Lower molars can have four or five cusps, with the first lower molar typically having five, and the second having four.

How does the occlusal surface of the first upper molar differ from the second?

The first upper molar has a rhomboid or irregular trapezoidal occlusal surface, with a characteristic enamel bridge between the mesiolingual and distobuccal cusps. The second upper molar also has a trapezoidal occlusal surface but lacks the tubercle of Carabelli and may have a distally displaced distolingual cusp.

What is the tubercle of Carabelli and where is it typically found?

The tubercle of Carabelli is a small, extra cusp found on the mesiolingual cusp of the first upper molar. It is not always present and can vary in size, ranging from small to prominent.

What distinguishes the first lower molar from the second lower molar?

The first lower molar typically has five cusps and a W-shaped sulcus on its occlusal surface, while the second lower molar has four cusps and a more quadrangular occlusal surface with a cruciform sulcus pattern.

How do the mesial and distal cusps of molars differ in size?

In general, the mesial cusps are larger than the distal cusps. This holds true for both upper and lower molars, with the mesial cusps providing a greater volume compared to the distal ones.

What is the shape of the occlusal surface of lower molars?

The occlusal surface of lower molars is typically trapezoidal, with the lower molars having a greater mesial-distal dimension than the vestibular-lingual dimension, distinguishing them from upper molars.

How can the first and second upper molars be differentiated in terms of cusp patterns?

The first upper molar usually has four cusps, while the second upper molar may have three or four. When the second molar has three cusps, the occlusal surface appears simpler with just two vestibular cusps and one lingual cusp.

What feature of the first lower molar makes its sulcus pattern unique?

The first lower molar has a unique W-shaped sulcus on its occlusal surface, which is formed by its five cusps. This sulcus is distinct because it curves and forms the letter 'W', unlike the more linear sulcus seen in other molars.

What is the characteristic sulcus pattern of the second upper molar?

The second upper molar typically has a sulcus pattern that is similar to the first molar but with a more distally displaced distolingual cusp. This creates a less complex occlusal pattern compared to the first molar.

How are the roots of upper and lower molars different?

Upper molars typically have three roots: two buccal (vestibular) and one lingual. Lower molars, on the other hand, usually have two roots: one mesial and one distal.