I found these notes from when I was a DS1. Maybe they help.
if worst comes to worst and you cant tell right from left (i.e. mesial from distal), remember that all root tips will point distally most of the time.
Also remember that you can look at the wear on the tooth to help determine if its max or mand.
MOLARS:
1) Maxillary Vs Mandible
3 roots = Maxillary
2 roots = Mandibular
2) Mandible:
a. 1st vs 2nd molar:
-1st molar has 5 cusps
-2nd molar has 4 cusps
b. Right vs Left
- For the 1st molar, there are 3 buccal cusps (instead of 2 on the lingual) and the Mesio-Buccal cusp is the largest.
- On the 2nd molar, you can differentiate b/w buccal and lingual b/c the lingual side is very straight, whereas the buccal is more curved. The Mesio-Buccal cusp is also the largest.
c. Right Mandibular molars= #30, #31
Left Mandibular molars= #18, #19
3) Maxilla:
a. 1st vs 2nd molar:
-1st molar can have a cusp of carebelli and the 3 roots diverge widely
-2nd molar never has a cusp of carebelli and the 3 roots are more tapered
b. Right vs Left for both 1st & 2nd molars:
-There will be 2 roots on one side and 1 root on the other side. Pick up the single root and hold it up so that the single root is closer to you and the double root is farther. The single root = palatal root, so therefore the lingual side of the tooth is closer to you. The Mesio-Lingual cusp should be the larger cusp. Therefore, if the ML cusp is on the left, it will be a left maxillary molar. If the ML cusp is on the right, it will be a right maxillary molar.
c. Right Max molars = #2, #3
Left Max molars = #14, #15
PREMOLARS
1) Maxillary vs. Mandibular:
-Maxillary = both the lingual and buccal cusps are very close in size
-Mandible = the buccal cusp is normal size and the lingual cusp is much smaller. Also, only mandibular premolars can have 3 cusps.
2) Mandible:
a. 1st vs 2nd premolar:
-1st premolar = wedge-shaped looks more like an incisor than a molar
-2nd premolar = only premolar with 3 cusps
b. Right vs Left:
-1st premolar: Mesiolingual groove, and the mesial side appears to be narrowed
-2nd premolar: the mesiolingual cusp is larger than the mesiobuccal cusp
c. Right mandibular premolar = #28,#29
Left mandibular premolars = ##20,#21
3) Maxilla:
a. 1st vs 2nd premolar:
-1st premolar has 2 roots (60% of time)
-2nd premolar has 1 root
b. Right vs. Left:
-1st premolar = has a mesio-marginal groove that looks like a bend. Also the distal cusp arm is shorter than the mesial so that the cusp will point distally.
-2nd premolar = the mesial cusp arm is shorter than the distal so that the lingual cusp points mesially (slightly)
c. Right Maxillary premolar: #4, #5
Left Maxillary premolar: #12,#13