Morpho 106 Copy

Maxillary Molars

• Maxillary molars are usually the first permanent teeth to erupt into the maxillary arch.
• Each maxillary molar usually has four major cusps, with two on the buccal portion of the occlusal table and two on the lingual.
• Each maxillary molar has three well-separated and well-developed roots.
• A tooth with three roots is said to be trifurcated, which means “divided into thirds.”

Maxillary First Molars

• The maxillary first molars (No. 3 and No. 14) are the first permanent teeth to erupt into the maxillary arch. 
• They erupt distal to the primary maxillary second molars and are therefore nonsuccedaneous.  
• The maxillary first molar is the largest tooth in the maxillary arch and also has the largest crown in the permanent dentition. 
• This molar is composed of five developmental lobes, two buccal and three lingual.
• The fifth cusp is called the cusp of Carabelli. 

Maxillary first molar. B, Mandibular first molar. (From Bath-Balogh MB, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, Philadelphia, 2005, Saunders.)

Various views of a permanent maxillary right first molar. (From Bath-Balogh MB, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, Philadelphia, 2005, Saunders.)

Maxillary Second Molars

• The crown of the maxillary second molar is somewhat shorter than that of the first molar, and it usually has four cusps. 
• No fifth cusp is present.
• There are three roots.
• The roots of the secondary molars are smaller than those of the first molars. The lingual root is still the largest and longest.
• The buccal groove is located farther distally on the buccal surface of the second maxillary molar than on the first maxillary molar. 
• The mesiobuccal cusp of the second maxillary molar is longer and has a more blunt cusp tip than the distobuccal cusp.

Various views of a permanent maxillary right second molar. (From Bath-Balogh MB, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, Philadelphia, 2005, Saunders.)

Maxillary Third Molars

• The maxillary third molars (No. 1 and No. 16) differ considerably in size and contour.
• The crown of the maxillary third molar is smaller and the roots are usually shorter.
• The roots of the maxillary third molar tend to fuse, and the result is a single tapered root.
• People sometimes refer to the maxillary third molars as the “wisdom” teeth because they erupt last.

Clinical Considerations with Maxillary Molars

• The roots of the maxillary molars may penetrate the maxillary sinus as a result of accidental trauma or during an extraction. 
• The roots of the maxillary molars are close to the sinuses. Some patients confuse the pain caused by a sinus infection with pain related to their maxillary teeth, and vice versa.
• The permanent maxillary third molars may fail to erupt and may remain impacted within the alveolar bone. 
• If the maxillary first molar is lost, the second molar can tip and drift into the open space, causing difficulty in chewing and furthering periodontal disease.

Buccal views of maxillary right molars. A, First molar. B, Second molar. C, Third molar. Notice how the roots tend to be closer together when the molars are farther distally. Third molar roots are often fused. (Modified from Brand RW, Isselhard DE: Anatomy of orofacial structures, ed 7, St Louis, 2003, Mosby.)

Various views of permanent maxillary right third molars. (From Bath-Balogh MB, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, Philadelphia, 2005, Saunders.)