[Posterior composite restorations].
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Biomedical subjects
Publications and source records attributed to V G Behrens.
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An in vitro study showed that it is possible to alter the surface morphology of root canals with a Nd-YAG Laser. S.E.M. and dye penetration photographs showed these changes in the canal surface morphology. In our opinion when an energy level of 15 IPS/1,5 W is used, the resulting changes are useful and of benefit in root canal treatment.
This study showed no difference between the use of the "Piezon Master 400", using four different attachments as compared to the "Hu Friedy" Curettes as far the formation of grooves and scratch marks is concerned. Both root planing methods gave rise to a scalloped surface of the root cement. The ultrasonic root planing however showed a more discrete scalloped surface with very small tears and having a hammered appearance. Hand instrumentation showed much wider tears on the root surface structure.
The investigative results showed that preparation of root canals is more effective with ultrasonic as compared to hand instrumentation. Areas like diverticula, canal enlargements or side canals were seen to be extremely clean. This is probably due to the effect of cavitation, implosion of small bubbles, the acceleration of minute particles and the formation of ultra sonic waves. The REM investigation showed no residual bacteria. The hand instrumented canals showed pulp remainders in the canal.