Canal master files: Scanning electron microscopic evaluation of new instruments and their wear with clinical usage

Zuolo, Mário Luis; Walton, Richard E.; Murgel, Carlos Alberto Ferreira

doi:10.1016/s0099-2399(06)80484-x

Cited by 16 publications

(6 citation statements)

References 14 publications

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“…During the study 8 out of 40 size 30-35 Flexogates fractured. This is a similar incidence to that reported for Canal Master instruments (9). Half of the fractures occurred on the instrument shaft just behind the cutting head and the other half at the predetermined breakage zone.…”

Section: Instrumentssupporting

confidence: 84%

Cutting pattern of Flexogate instruments in plastic blocks

Bedford-Roberts¹,

Curtis

Ford³

1997

Dental Traumatology

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Design modifications of endodontic instruments have been made to improve instrumentation in curved root canals. A new instrument, the Flexogate (Maillefer), has been introduced to overcome some of the problems associated with preparation of the apical part of the root canal. The purpose of this study was to investigate the cutting pattern of Flexogates in curved canals (45 degrees) in clear plastic blocks, prepared by four different operators. Image analysis was used to take accurate measurements of canal shape before and after instrumentation to calculate cutting patterns. The results showed that Flexogates did not remain centred in the canal of a plastic block during cutting; maximum transportation occurred in the apical third of the outer curve, with little or none in the middle and coronal thirds. The clinical implications of this study require further investigation of the effect of coronal preflaring, and experimentation in teeth.

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Section: Instrumentssupporting

confidence: 84%

Cutting pattern of Flexogate instruments in plastic blocks

Bedford-Roberts¹,

Curtis

Ford³

1997

Dental Traumatology

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“…This probably underpinned the formulation of the pertinent ISO/ANSI specification (6) that is based on a shear test. Wear and distortion of the flutes are precursors to breakage and signal the end of service of an instrument, and these signs are more often seen in manually operated stainless-steel files rather than nickel-titanium (NiTi) rotary instruments (7). There has been a perception that NiTi engine-files may fracture without any warning signs (8,9).…”

Section: Introductionmentioning

confidence: 99%

Instrument fracture: mechanisms, removal of fragments, and clinical outcomes

Cheung¹

2007

Endodontic Topics

169

161

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Instrument fracture can be an unpleasant mishap during non‐surgical root canal treatment. While most stainless‐steel instruments appear to fail by excessive amounts of torque, the combined action of torsional stress and cyclic loading (i.e. fatigue, as a result of rotational bending, or repeated torsion) is responsible for the breakage of NiTi rotary files in use. Factors affecting the incidence and mode of failures include the instrumentation technique, use of torque‐controlled motor, the dimension and surface condition of the instrument, rotation rate, radius (and, to a certain extent, angle) of canal curvature, and the presence of a straight‐line access and a ‘glide path’ to the apical portion of the canal. If breakage should occur clinically, the patient should be informed of the incident and consideration should be given as to whether or not to remove the fragment. Managed properly, the presence of a broken fragment per se may not adversely affect the outcome of root canal treatment. This review examines the various aspects (including mechanisms, contributing factors, prognosis and management) of instrument fracture. Emphasis is placed on the separation of nickel–titanium rotary files and ways to prevent this in the clinical situation.

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“…Amongst these instruments was the innovative Canal Master U (Brasseler, Savannah, GA, USA) described by Wildey & Senia (1989) and Wildey et al (1992). Subsequent studies reported both negative and positive findings for the Canal Master U technique (Zuolo et al 1992, Pertot et al 1995. Fractures of the stainless-steel Canal Master U instruments were related mainly to their poor flexibility and some clinicians may have underestimated the sensitivity of the preparation technique.…”

Section: Introductionmentioning

confidence: 99%

Preparation of the apical part of the root canal by the Lightspeed and step‐back techniques

1998

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This study measured in vitro the displacement of natural canal centres in 18 human teeth before and after shaping by the step-back or Lightspeed techniques. Experimental roots (n = 9 per group), embedded in clear plastic, were cross-sectioned using a 0.1-mm-thick band saw at distances 1.25 mm, 3.25 mm and 5.25 mm from the apices. A stereo microscope was used to take 35 mm slides of the cut surfaces of the sectioned roots and canals. The slides of the uninstrumented canals were scanned into a computer and saved. Each sectioned root was then reassembled and the canals shaped by the step-back or Lightspeed technique. File size 40 and instrument size 50 were selected as the master apical file and master apical rotary for the step-back and Lightspeed groups, respectively. The 18 prepared canals were photographed, and the 35 mm slides scanned and computer stored as previously. This allowed the positions of the pre- and postinstrumented roots to be electronically superimposed for subsequent analyses. Displacements of the root canal centres before and after preparation were assessed in relation to the cross-sectional diameter of the files or instruments used. In addition, increases in cross-sectional area of the root canals after preparation were evaluated in relation to the cross-sectional area of the files or instruments used. Engine-driven nickel-titanium Lightspeed instruments caused significantly less (P < 0.001) displacement of the canal centres, so roots in the Lightspeed group remained better centred than those in the step-back group. The mean cross-sectional area after preparation in the Lightspeed group was significantly less (P < 0.001) than that recorded in the step-back group. Clinically, this implies less apical transportation and less dentine destruction with the Lightspeed technique than with the step-back technique.

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Canal master files: Scanning electron microscopic evaluation of new instruments and their wear with clinical usage

Cited by 16 publications

References 14 publications

Cutting pattern of Flexogate instruments in plastic blocks

Cutting pattern of Flexogate instruments in plastic blocks

Instrument fracture: mechanisms, removal of fragments, and clinical outcomes

Preparation of the apical part of the root canal by the Lightspeed and step‐back techniques

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