Compare ultrasonic and bur root end cavity preparations with regard to retention, cleanliness, and root canal parallelism.
- N= 20 anterior teeth from 2 cadavers
- Teeth were instrumented and obturated with gutta percha and sealer. A flap was raised and root end preparations were performed on each root. Retropreps were done with 45 degree bevel.
- Teeth were separated into 2 groups:
- Group 1 – (10) retroprep w/ inverted cone bur.
- Group 2 – (10) retroprep w/ Ultrasonic (Carr tip).
- The teeth were extracted, sectioned longitudinally, and examined with SEM for cleanliness of cavities and the direction of preparations in relationship to the canal.
- Ultrasonic preps had more parallel walls, walls that followed the canals more and deeper depths for retention. The minimum depth was 2.5 mm.
- Bur preps averaged 1 mm depth and were oblique to long axis of tooth.
- Dentinal walls of preps with ultrasonics showed more open dentinal tubules and minimal debris layer compared to bur group.
Ultrasonics allow for deeper, more parallel, and cleaner root end preparations that follow the canal system more accurately when compared to root end preparations with burs.