Purpose:
Compare ultrasonic and bur root end cavity preparations with regard to retention, cleanliness, and root canal parallelism.
Materials/Methods:
- 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.
Results:
- 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.
Clinical Significance:
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.