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RS 70 A prototype of root canal instrument for the preparation of curved root canals
AAE Abstracts of Papers
Vol. 20, No. 4, April 1994 Digital Comparison of Three Instrumentation Techniques in Curved Root Canals. S.K. Bentkover* and C.H. Wenckus. Univ. of IL at Chicago College of Dentistry. The purpose of this investigation was to compare the degree of canal transportation, percentage of dentin removed, and time taken to instrument curved canals employing three different instrumentation techniques: I) circumferential step-back technique (CF); 2) balanced force step-back technique (BF), or 3) NT preparation system (NT). Mesial roots hemisected from 64 extracted mandibular first molars possessing curvatures between 30 ° and 60 ° were used. Utilizing a stainless steel muffle-model, each root was embedded into an acrylic resin block and sectioned at two levels. The canal outline on the coronal surface of the two sections were then digitizedl and the pre-instrumentation canal space area and center' of gravity were calculated at each level. Following instrumentation, the new canal outline was digitized ~nd compared with the pre-instrumentation outline to Jetermine the amount of canal transportation and per:entage of dentin removed at each level. Total time required to instrument each root was also recorded. Results indicated that NT and BF maintained canal position significantly better than CF, however, CF enlargec the canal significantly greater than NT or BF. Additionally, NT was significantly faster than either CF ol BF.
R6•8
Comparison c;F Hand, Hand/Sonic, and Hand]Mechamcal Instrumentation Methods.KL ZAKARIASEN*, K.A ZAKARIASEN, (Marquette University, Milwaukee, Wl) Research indicates that hand, hand/sonic, and hand/mechanical enlargement can properly shape canals. This research is designed to compare canals shaped by step-back and hand/sonic filing with those shaped by a hand/mechanical technique using both traditional Hedstroem (TH) and Safety Hedstroem (SH) files. The Sonic Air 1500 and EndoLift devices were used for sonic and mechanical instrumentation. The 7 groups studied were A) StepBack TH, B) Step-Back Stt, C) TH/Sonic, D) SH/Sonic, E) TH/rH EndoLift, F) SluTH EndoLift, G) SLUSH EndoLift. One hundred and forty #101 Endo-vu blocks were accessed, randomized into 7 groups and preflared to 20mm with the assigned techniques. Apical preparations were completed to #25 at 23mm. Canal flaring was continued with step-back, sonic or EndoLift filing until a D l l T spreader would freely penetrate 22mm. Instrumentation times were recorded. Canal preparations were randomly evaluated blind for these errors: apical transportation, ledge formation, and hour-glass canal shaping. The mean preparation times ranged from 8.25 to 9.84 min. with hand filing being significantly slower (p=.026). Errors were few and no dif. (p=.05) were observed between the 7 groups for definitive errors. A comparison of TH vs. SH files showed fewer apical transportations for the SH (p=0.007), although the total number of errors was small. The results indicate t h a t sten-back, hand/sonic, and hand/EndoLift technioues can all nrovide satisfactory canal Dreoarations with minimal ]eduinm apical transportation or hourglass shaning of the canal space. In addition, the results indicate that the Safety Hedstroems may have some advantage relative to Ol~ical transnortation and t h a t hand/sonic-EndoLift assisted instrumentation is somewhat more raoid.
This study was supported by the Research and Education Foundation of the American Association of Endodontists and the Charles G. Maurice Endodontic Research Foundation.
R6~9
A Comparison of Excalibur and Hand Instrumentation in Curved Canals *G.SP CHEUNG and AW.K. CHAN (Faculty. of Dentistry.'.The University of Hong Kong) Fe~ reports concerned the Excalibur handpicce (W&H. Austria). one of the many automated dcvices marketed to facilitate root canal preparation The present studx was aimed to compare the result of preparation using Excalibur and hand instrumentation on the final shape of curved root canals. A total of 24 canals of standardised length and size, and with similar degree of curvature in the mesial roots of extracted lower first molars ~ere randomly divided into two groups. Group A (Excalibur) ~as prepared according to the manufacturer's instructions. Group B ~as prepared manually using the Step D o ~ Technique and stainless steel K-files. Cross-sectional shapes of each canal at 3ram from thc root tip. apex of curvature and near the canal orifice were captured using an image analysis computer soft~'are before and after instrumentation Parameters evaluated were the area of dentine removed and the minimum remaining canal wall thickness. T-test was used to anah'se the data at a significance level of p=0.05 The results showed that there was no significant difference between the groups both in the amount (area) of dentine removed and in thc minimum canal wall thickness left at all levels although this thickness tended to be consistently thinner in thc Excalibur group. Thcre wcrc three canals perforated at the coronal section and one at the mid-root level: all occurred in the Excalibur group at the furcal aspect. Hence we concluded that although the two groups removed similar amount of dentine and were not significantly different in the thinnest canal wall produced, there was an increased risk of strip perforation when using Excalibur. This study was supported by a research grant, uo.334/252/0001, from The University' of Hong Kong.
205
R~IR7,~I ---1
A prototype of root canal instrument for the preparauon of curved root canals. B. M. Brisefio* University of Mainz, School of Dentistry, Germany. Success in endodontic therapy depends largely on the form of the root canal preparation and on total removal of debris from the root canal. Undesirable shaping effects such as straightening, elbowing etc. can be reduced with conventional and hybrid instruments. Still, complete elusion of the aforementioned effects, in curved root canals, has not yet been possible. A prototype of a root canal instrument for the preparation of curved root canals was developed. The instrument resembles a Flexogate file in its passive portion. The active sector of the instrument is 5 mm long showing a flat non-cutting area along 180 °. The remaining 180 ° area revokes a hedstrom-type fide. The cutting attributes of the prototype-instrument were investigated with specially manufactured simulated root canals in clear casting resin blocks and with a computer-supported device. The enlarging device was programed with a combination of the step-down technique for the straight portion of the canal and with a modified the step-back technique for the enlargement of the curved part of the root canal. A total of 30 canals were enlarged in this manner and evaluated at four different levels ( 1, 3, 4 and 7 mm from apical). The results were compared with a theoretically ideally shaped canal means a photographic double exposure method. The results showed that the original canal axis was not significantly transported from its original position at the apical third. Thus enabling a proportional removal of material at the concave and convex side of the canal. The enlargement of curved root canals with this instrument and the technique developed for this purpose appears to be recommendable.
Vol. 20, No. 4, April 1994 Digital Comparison of Three Instrumentation Techniques in Curved Root Canals. S.K. Bentkover* and C.H. Wenckus. Univ. of IL at Chicago College of Dentistry. The purpose of this investigation was to compare the degree of canal transportation, percentage of dentin removed, and time taken to instrument curved canals employing three different instrumentation techniques: I) circumferential step-back technique (CF); 2) balanced force step-back technique (BF), or 3) NT preparation system (NT). Mesial roots hemisected from 64 extracted mandibular first molars possessing curvatures between 30 ° and 60 ° were used. Utilizing a stainless steel muffle-model, each root was embedded into an acrylic resin block and sectioned at two levels. The canal outline on the coronal surface of the two sections were then digitizedl and the pre-instrumentation canal space area and center' of gravity were calculated at each level. Following instrumentation, the new canal outline was digitized ~nd compared with the pre-instrumentation outline to Jetermine the amount of canal transportation and per:entage of dentin removed at each level. Total time required to instrument each root was also recorded. Results indicated that NT and BF maintained canal position significantly better than CF, however, CF enlargec the canal significantly greater than NT or BF. Additionally, NT was significantly faster than either CF ol BF.
R6•8
Comparison c;F Hand, Hand/Sonic, and Hand]Mechamcal Instrumentation Methods.KL ZAKARIASEN*, K.A ZAKARIASEN, (Marquette University, Milwaukee, Wl) Research indicates that hand, hand/sonic, and hand/mechanical enlargement can properly shape canals. This research is designed to compare canals shaped by step-back and hand/sonic filing with those shaped by a hand/mechanical technique using both traditional Hedstroem (TH) and Safety Hedstroem (SH) files. The Sonic Air 1500 and EndoLift devices were used for sonic and mechanical instrumentation. The 7 groups studied were A) StepBack TH, B) Step-Back Stt, C) TH/Sonic, D) SH/Sonic, E) TH/rH EndoLift, F) SluTH EndoLift, G) SLUSH EndoLift. One hundred and forty #101 Endo-vu blocks were accessed, randomized into 7 groups and preflared to 20mm with the assigned techniques. Apical preparations were completed to #25 at 23mm. Canal flaring was continued with step-back, sonic or EndoLift filing until a D l l T spreader would freely penetrate 22mm. Instrumentation times were recorded. Canal preparations were randomly evaluated blind for these errors: apical transportation, ledge formation, and hour-glass canal shaping. The mean preparation times ranged from 8.25 to 9.84 min. with hand filing being significantly slower (p=.026). Errors were few and no dif. (p=.05) were observed between the 7 groups for definitive errors. A comparison of TH vs. SH files showed fewer apical transportations for the SH (p=0.007), although the total number of errors was small. The results indicate t h a t sten-back, hand/sonic, and hand/EndoLift technioues can all nrovide satisfactory canal Dreoarations with minimal ]eduinm apical transportation or hourglass shaning of the canal space. In addition, the results indicate that the Safety Hedstroems may have some advantage relative to Ol~ical transnortation and t h a t hand/sonic-EndoLift assisted instrumentation is somewhat more raoid.
This study was supported by the Research and Education Foundation of the American Association of Endodontists and the Charles G. Maurice Endodontic Research Foundation.
R6~9
A Comparison of Excalibur and Hand Instrumentation in Curved Canals *G.SP CHEUNG and AW.K. CHAN (Faculty. of Dentistry.'.The University of Hong Kong) Fe~ reports concerned the Excalibur handpicce (W&H. Austria). one of the many automated dcvices marketed to facilitate root canal preparation The present studx was aimed to compare the result of preparation using Excalibur and hand instrumentation on the final shape of curved root canals. A total of 24 canals of standardised length and size, and with similar degree of curvature in the mesial roots of extracted lower first molars ~ere randomly divided into two groups. Group A (Excalibur) ~as prepared according to the manufacturer's instructions. Group B ~as prepared manually using the Step D o ~ Technique and stainless steel K-files. Cross-sectional shapes of each canal at 3ram from thc root tip. apex of curvature and near the canal orifice were captured using an image analysis computer soft~'are before and after instrumentation Parameters evaluated were the area of dentine removed and the minimum remaining canal wall thickness. T-test was used to anah'se the data at a significance level of p=0.05 The results showed that there was no significant difference between the groups both in the amount (area) of dentine removed and in thc minimum canal wall thickness left at all levels although this thickness tended to be consistently thinner in thc Excalibur group. Thcre wcrc three canals perforated at the coronal section and one at the mid-root level: all occurred in the Excalibur group at the furcal aspect. Hence we concluded that although the two groups removed similar amount of dentine and were not significantly different in the thinnest canal wall produced, there was an increased risk of strip perforation when using Excalibur. This study was supported by a research grant, uo.334/252/0001, from The University' of Hong Kong.
205
R~IR7,~I ---1
A prototype of root canal instrument for the preparauon of curved root canals. B. M. Brisefio* University of Mainz, School of Dentistry, Germany. Success in endodontic therapy depends largely on the form of the root canal preparation and on total removal of debris from the root canal. Undesirable shaping effects such as straightening, elbowing etc. can be reduced with conventional and hybrid instruments. Still, complete elusion of the aforementioned effects, in curved root canals, has not yet been possible. A prototype of a root canal instrument for the preparation of curved root canals was developed. The instrument resembles a Flexogate file in its passive portion. The active sector of the instrument is 5 mm long showing a flat non-cutting area along 180 °. The remaining 180 ° area revokes a hedstrom-type fide. The cutting attributes of the prototype-instrument were investigated with specially manufactured simulated root canals in clear casting resin blocks and with a computer-supported device. The enlarging device was programed with a combination of the step-down technique for the straight portion of the canal and with a modified the step-back technique for the enlargement of the curved part of the root canal. A total of 30 canals were enlarged in this manner and evaluated at four different levels ( 1, 3, 4 and 7 mm from apical). The results were compared with a theoretically ideally shaped canal means a photographic double exposure method. The results showed that the original canal axis was not significantly transported from its original position at the apical third. Thus enabling a proportional removal of material at the concave and convex side of the canal. The enlargement of curved root canals with this instrument and the technique developed for this purpose appears to be recommendable.