According to Pederson difficulty index, what is the difficulty level of an impacted tooth
which is lying horizontally, at Level III and position C?: (A) Minimum difficulty, (B) Moderate difficulty, (C) Very difficult, (D) Not impacted
Answer is C. Pederson difficulty index based on Pell and Gregory classification:
(A) Spatial relationship:
Mesioangular = 1
Horizontal = 2
Vertical = 3
Distoangular = 4
(B) Depth:
Position A (highest portion of crown of 8 is above occlusal line of 2nd molar) =1
Position B (higher portion of crown of 8 is above CEJ of 2nd molar) = 2
Position C (highest portion of crown of 8 is below CEJ of 2nd molar) = 3
(C) Relation with ascending ramus:
Level 1 (mesiodistal width between 7 and ascending ramus is sufficient to accommodate mesiodistal width of 8) = 1
Level 2 (space slightly short to accomodate the entire mesiodistal width of 8) = 2
Level 3 (space very less to accomodate the entire mesiodistal width of 8 – tooth almost within ascending ramus ) = 3
Difficulty score = A+B+C
Score 3-4 = minimum difficulty
Score 5-7 = moderate difficulty
Score 8-10 = very difficult.
Other difficulty indices are: WHARFE Score, Parant and Modified Parant scale and using WAR lines.