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RS 40 Structural changes in roots following sonic and ultrasonic root-end preparation
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Evaluation of Cracks Associated with Ultrasonic RootEnd Preparation. C.A.Layton*, J.G. Marshall, L.A. Morgan, J.C. Baumgartner Oregon Health Sciences University, Portland OR Ultrasonic instruments have been recommended for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched extracted human teeth for cracks both before and after root-end preparations with ultrasonic tips. A preliminary study demonstrated that cracks could be produced with ultrasonic root-end preparation and effectively detected with a stereomicroscope. The root canals of the teeth used in this study had not been instrumented or filled prior to the root-end preparation. Thirty bilaterally matched pairs of single rooted human teeth had three millimeter root-end resections using a low-speed diamond saw. The root-end resections were examined for cracks. The matched pairs of teeth were divided into two experimental groups with one member of each pair being placed in each group. In Group 1, root-end preparations were made with an ultrasonic tip on the lowest frequency setting while root-end preparations in Group 2 were done on the highest power setting. The root-end preparations were made using a light back and forth motion with water spray. Two examiners evaluated the resected root-ends using a stereomicroscope at 20X - 63X. Three types of cracks were observed and defined: canal cracks, intradentin cracks, and cemental cracks. All types of cracks were observed after both root-end resection and after ultrasonic root-end preparation. There were significantly more canal cracks after ultrasonic rootend preparation than after root-end resection. Using the ultrasonic tip on the high frequency setting during root-end preparation resulted in significantly more canal cracks per root than when the ultrasonic tip was used on the low power setting. Further research is needed to evaluate the depth of the cracks and their imoact on success-failure.
391
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R.~j Structural Changes in Roots Following Sonic and Ultrasonic Root-End Preparation. J.C. MARDEROSIAN* and G.N. GLICKMAN The University of Michigan, Ann Arbor Recent studies have suggested that ultrasonics may precipitate root-end fracture. The purpose of this study was to assess cavity preps created by ultrasonic, sonic, and conventional methods. In Part I, resected root-ends of 40 obturated single canaled roots were divided into 4 groups. Standardized root-end preps were made with ENAC diamond tip, MM 1500 sonic retrotip, EIE smooth tip, and microcontrangle 1/2 round bur. With liquid N2, fractures were generated for positive controls. Teeth were centrifuged in India ink for 10 minutes. Roots were sectioned at 1 ram, 2.5 mm, and 4 ram; sections were evaluated for cracks via stereomicroscopy @ 20X. In Part II, root-end preps were made in 20 teeth; 4 teeth were prepared by each of methods used in Part I and 4 were prepared with the ENAC smooth tip. Teeth were split and prepared for the SEM. All micrographs were evaluated for debris, smear, and tubule visibility. In Part I. 1 or 2 small cracks were visible in 7 out of 120 soecimens: statistical analvsis (ANOVA. p=.08} indigo, ted no sianificant diffe~:ence amona the techniaues used. In Part I1. the MM 1500 sonic retrotip produced the cleanest cavity with most tubule visibility: exceDt for the microcontranale arouo. which created-the most debris, there was no-sianificant
difference in d~lpris removal and tubule visibility betwQen the other techniaues (Kruskal-Wallis. o=.19~. The results suggest that no 0.ooarent structural ~ f e c t s occur followina sonic and ultrasoni• root-end cavity oreoaration. This study was supported by a grant from the R&E Foundation. a~
Effects of Ultrasonic Root-end Cavity Preparation on the Root Apex HR Abedi*, BL Van Mierlo, P Wilder-Smith, M Torabinejad. Loma Linda University, Loma Linda, California. Ultrasonic tips are being increasingly used as an alternative to burs to prepare root-end cavities. This allows cleaner, deeper and more parallel root-end cavity preparations. Despite its advantages, there has been concern regarding the effect of ultrasonics, running at 30-40,000 Hz on the root apex. The purpose of this study was to dctemfine the effect of ultrasonic and bur preparation on the root apex, using a resin replica technique under light and scanning electron microscopes (SEM). Forty-seven freshly extracted formalin-fixed single rooted teeth were cleaned and shaped using the Passive Stepback technique and filled with gutta-percha and sealer. The roots were then individually mounted in customized jigs and standardized apical resections were made with a low speed diamond saw. The root-ends were photographed at X30 magnification and resin replicas were also made for examination under the SEM. The teeth were lhen randomly divided into two groups. In one group the root-end cavity preparations were carried out with a #170L fissure bur and in the other group with an ultrasonic tip attached to one of two different ultrasonic units. Post-operative photographs and resin replicas were then also examined for development of cracks following root-end cavity preparations. Data was analysed by Two-way ANOVA and the Independent T test. Our results showed a significantly higher formation of cracks in the ultrasonic groups, (P<0.05) with the majority of cracks occurring on the thinnest dentinal wall. If these cracks prove to be deleterious, then present techniques for root-end cavity preparation with ultrasonics should be re-evaluated.
I~gJ _7_2_J
J
c o m p a r a t i v e Bacterial A s s a y of M i c r o l e a k a g e of Three Retrograde Filling Materials. A. DHARANANIDHIKUL*, R. NOGHREIAN*, P.A. ROSENBERG, R.J. BOYLAN; New York University, College of Dentistry, New York, N.Y.
Objective: An in vitro model using a bacterial assay was used to compare the apical seals created by frequently used retrograde materials. Materials and Methods: Fifty extracted single rooted teeth were randomly separated into five groups. Groups included amalgam, Super EBA, composite resin, a positive, and a negative control. Teeth were instrumented and obturated with gutta percha using lateral condensation and Roth's sealer. Simulated apicoectomies were performed and retrograde filling materials were placed. A reservoir for bacterial suspension was prepared in the coronal portion of the canal and nail polish was applied to the external root surface excluding the p r e p a r e d root end to p r e v e n t lateral microleakage. The teeth were p l a c e d in c u l t u r e c h a m b e r s and sterilized with C e s i u m radiation. Culture medium (BHI) w i t h phenol red i n d i c a t o r w a s p l a c e d into culture chambers to a level 4-5 m m a b o v e the p r e p a r e d apex of the tooth. The coronal r e s e r v o i r was inoculated every s e v e n t y - t w o h o u r s w i t h 0.01 ml of a suspension of S t r e p t o c o c c u s s a l i v a r i u s ( 108 CFU/ml BHI broth). C u l t u r e m e d i a w e r e o b s e r v e d for color change every t w e n t y - f o u r hours, indicating bacterial growth in the c u l t u r e chamber. Media d e m o n s t r a t i n g colo@ change w e r e c u l t u r e d and the growth was inspected for S. salivarius. Conclusion: Throughout the forty-five day study, there was a siqnificant difference observed in microleakaqe between all qroups and the neqative control (P<0.001). The composite resin qroup, statistically, had the least microleakaqe amongst all qroups.
225
Evaluation of Cracks Associated with Ultrasonic RootEnd Preparation. C.A.Layton*, J.G. Marshall, L.A. Morgan, J.C. Baumgartner Oregon Health Sciences University, Portland OR Ultrasonic instruments have been recommended for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched extracted human teeth for cracks both before and after root-end preparations with ultrasonic tips. A preliminary study demonstrated that cracks could be produced with ultrasonic root-end preparation and effectively detected with a stereomicroscope. The root canals of the teeth used in this study had not been instrumented or filled prior to the root-end preparation. Thirty bilaterally matched pairs of single rooted human teeth had three millimeter root-end resections using a low-speed diamond saw. The root-end resections were examined for cracks. The matched pairs of teeth were divided into two experimental groups with one member of each pair being placed in each group. In Group 1, root-end preparations were made with an ultrasonic tip on the lowest frequency setting while root-end preparations in Group 2 were done on the highest power setting. The root-end preparations were made using a light back and forth motion with water spray. Two examiners evaluated the resected root-ends using a stereomicroscope at 20X - 63X. Three types of cracks were observed and defined: canal cracks, intradentin cracks, and cemental cracks. All types of cracks were observed after both root-end resection and after ultrasonic root-end preparation. There were significantly more canal cracks after ultrasonic rootend preparation than after root-end resection. Using the ultrasonic tip on the high frequency setting during root-end preparation resulted in significantly more canal cracks per root than when the ultrasonic tip was used on the low power setting. Further research is needed to evaluate the depth of the cracks and their imoact on success-failure.
391
R.A~.. j
R.~j Structural Changes in Roots Following Sonic and Ultrasonic Root-End Preparation. J.C. MARDEROSIAN* and G.N. GLICKMAN The University of Michigan, Ann Arbor Recent studies have suggested that ultrasonics may precipitate root-end fracture. The purpose of this study was to assess cavity preps created by ultrasonic, sonic, and conventional methods. In Part I, resected root-ends of 40 obturated single canaled roots were divided into 4 groups. Standardized root-end preps were made with ENAC diamond tip, MM 1500 sonic retrotip, EIE smooth tip, and microcontrangle 1/2 round bur. With liquid N2, fractures were generated for positive controls. Teeth were centrifuged in India ink for 10 minutes. Roots were sectioned at 1 ram, 2.5 mm, and 4 ram; sections were evaluated for cracks via stereomicroscopy @ 20X. In Part II, root-end preps were made in 20 teeth; 4 teeth were prepared by each of methods used in Part I and 4 were prepared with the ENAC smooth tip. Teeth were split and prepared for the SEM. All micrographs were evaluated for debris, smear, and tubule visibility. In Part I. 1 or 2 small cracks were visible in 7 out of 120 soecimens: statistical analvsis (ANOVA. p=.08} indigo, ted no sianificant diffe~:ence amona the techniaues used. In Part I1. the MM 1500 sonic retrotip produced the cleanest cavity with most tubule visibility: exceDt for the microcontranale arouo. which created-the most debris, there was no-sianificant
difference in d~lpris removal and tubule visibility betwQen the other techniaues (Kruskal-Wallis. o=.19~. The results suggest that no 0.ooarent structural ~ f e c t s occur followina sonic and ultrasoni• root-end cavity oreoaration. This study was supported by a grant from the R&E Foundation. a~
Effects of Ultrasonic Root-end Cavity Preparation on the Root Apex HR Abedi*, BL Van Mierlo, P Wilder-Smith, M Torabinejad. Loma Linda University, Loma Linda, California. Ultrasonic tips are being increasingly used as an alternative to burs to prepare root-end cavities. This allows cleaner, deeper and more parallel root-end cavity preparations. Despite its advantages, there has been concern regarding the effect of ultrasonics, running at 30-40,000 Hz on the root apex. The purpose of this study was to dctemfine the effect of ultrasonic and bur preparation on the root apex, using a resin replica technique under light and scanning electron microscopes (SEM). Forty-seven freshly extracted formalin-fixed single rooted teeth were cleaned and shaped using the Passive Stepback technique and filled with gutta-percha and sealer. The roots were then individually mounted in customized jigs and standardized apical resections were made with a low speed diamond saw. The root-ends were photographed at X30 magnification and resin replicas were also made for examination under the SEM. The teeth were lhen randomly divided into two groups. In one group the root-end cavity preparations were carried out with a #170L fissure bur and in the other group with an ultrasonic tip attached to one of two different ultrasonic units. Post-operative photographs and resin replicas were then also examined for development of cracks following root-end cavity preparations. Data was analysed by Two-way ANOVA and the Independent T test. Our results showed a significantly higher formation of cracks in the ultrasonic groups, (P<0.05) with the majority of cracks occurring on the thinnest dentinal wall. If these cracks prove to be deleterious, then present techniques for root-end cavity preparation with ultrasonics should be re-evaluated.
I~gJ _7_2_J
J
c o m p a r a t i v e Bacterial A s s a y of M i c r o l e a k a g e of Three Retrograde Filling Materials. A. DHARANANIDHIKUL*, R. NOGHREIAN*, P.A. ROSENBERG, R.J. BOYLAN; New York University, College of Dentistry, New York, N.Y.
Objective: An in vitro model using a bacterial assay was used to compare the apical seals created by frequently used retrograde materials. Materials and Methods: Fifty extracted single rooted teeth were randomly separated into five groups. Groups included amalgam, Super EBA, composite resin, a positive, and a negative control. Teeth were instrumented and obturated with gutta percha using lateral condensation and Roth's sealer. Simulated apicoectomies were performed and retrograde filling materials were placed. A reservoir for bacterial suspension was prepared in the coronal portion of the canal and nail polish was applied to the external root surface excluding the p r e p a r e d root end to p r e v e n t lateral microleakage. The teeth were p l a c e d in c u l t u r e c h a m b e r s and sterilized with C e s i u m radiation. Culture medium (BHI) w i t h phenol red i n d i c a t o r w a s p l a c e d into culture chambers to a level 4-5 m m a b o v e the p r e p a r e d apex of the tooth. The coronal r e s e r v o i r was inoculated every s e v e n t y - t w o h o u r s w i t h 0.01 ml of a suspension of S t r e p t o c o c c u s s a l i v a r i u s ( 108 CFU/ml BHI broth). C u l t u r e m e d i a w e r e o b s e r v e d for color change every t w e n t y - f o u r hours, indicating bacterial growth in the c u l t u r e chamber. Media d e m o n s t r a t i n g colo@ change w e r e c u l t u r e d and the growth was inspected for S. salivarius. Conclusion: Throughout the forty-five day study, there was a siqnificant difference observed in microleakaqe between all qroups and the neqative control (P<0.001). The composite resin qroup, statistically, had the least microleakaqe amongst all qroups.
225