Premolars are typically single or double rooted, although more than two roots do occur, especially on third premolars. Premolar roots are much wider in the buccal-lingual direction than in the mesial-distal direction. Each premolar bears a lingual and buccal cusp. The lingual and buccal cups are separated by a central mesial-distally oriented groove. Premolars are distinguished from canines and incisors because premolars possess multiple cusps. Molars have more cusps than premolars, are larger, and bear multiple roots.
More teeth specimens can be found in the digital teaching collection. See also the incisors, canines, and molars.
It can be difficult to distinguish between P3 and P4. The root of P3 is commonly composed of two lobes, or splits into two roots at the tip of the root, whereas P4 is usually single rooted. Furthermore, the lingual cusp of P3 is small compared to its buccal cusp, while the cusps are more equal in size in P4.
It is somewhat easier to distinguish between P3 and P4. As noted above, the lingual cusp on the mandibular premolars is reduced compared to its size in the upper premolars. However, this reduction is dramatically more apparent on P3 than on P4. Furthermore, the P3 usually lacks almost entirely a central groove dividing the cusps.
Siding Premolars
To side premolars, note that the lingual cusp is always smaller and usually more worn than the buccal cusp. The lingual cusp is offset slightly mesially with respect to the position of the buccal cusp. The long axis of the root is usually oriented slightly distally, although it is not uncommon for a tooth to have a relatively straight root axis. Siding P3 can be extremely difficult because the lingual cusp can be so inconspicuous as to be virtually useless in siding.
It can be difficult to distinguish between P3 and P4. The root of P3 is commonly composed of two lobes, or splits into two roots at the tip of the root, whereas P4 is usually single rooted. Furthermore, the lingual cusp of P3 is small compared to its buccal cusp, while the cusps are more equal in size in P4.
It is somewhat easier to distinguish between P3 and P4. As noted above, the lingual cusp on the mandibular premolars is reduced compared to its size in the upper premolars. However, this reduction is dramatically more apparent on P3 than on P4. Furthermore, the P3 usually lacks almost entirely a central groove dividing the cusps.
Siding Premolars
To side premolars, note that the lingual cusp is always smaller and usually more worn than the buccal cusp. The lingual cusp is offset slightly mesially with respect to the position of the buccal cusp. The long axis of the root is usually oriented slightly distally, although it is not uncommon for a tooth to have a relatively straight root axis. Siding P3 can be extremely difficult because the lingual cusp can be so inconspicuous as to be virtually useless in siding.
It can be difficult to distinguish between P3 and P4. The root of P3 is commonly composed of two lobes, or splits into two roots at the tip of the root, whereas P4 is usually single rooted. Furthermore, the lingual cusp of P3 is small compared to its buccal cusp, while the cusps are more equal in size in P4.
It is somewhat easier to distinguish between P3 and P4. As noted above, the lingual cusp on the mandibular premolars is reduced compared to its size in the upper premolars. However, this reduction is dramatically more apparent on P3 than on P4. Furthermore, the P3 usually lacks almost entirely a central groove dividing the cusps.
Siding Premolars
To side premolars, note that the lingual cusp is always smaller and usually more worn than the buccal cusp. The lingual cusp is offset slightly mesially with respect to the position of the buccal cusp. The long axis of the root is usually oriented slightly distally, although it is not uncommon for a tooth to have a relatively straight root axis. Siding P3 can be extremely difficult because the lingual cusp can be so inconspicuous as to be virtually useless in siding.
It can be difficult to distinguish between P3 and P4. The root of P3 is commonly composed of two lobes, or splits into two roots at the tip of the root, whereas P4 is usually single rooted. Furthermore, the lingual cusp of P3 is small compared to its buccal cusp, while the cusps are more equal in size in P4.
It is somewhat easier to distinguish between P3 and P4. As noted above, the lingual cusp on the mandibular premolars is reduced compared to its size in the upper premolars. However, this reduction is dramatically more apparent on P3 than on P4. Furthermore, the P3 usually lacks almost entirely a central groove dividing the cusps.
Siding Premolars
To side premolars, note that the lingual cusp is always smaller and usually more worn than the buccal cusp. The lingual cusp is offset slightly mesially with respect to the position of the buccal cusp. The long axis of the root is usually oriented slightly distally, although it is not uncommon for a tooth to have a relatively straight root axis. Siding P3 can be extremely difficult because the lingual cusp can be so inconspicuous as to be virtually useless in siding.