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At least 19 recordsLinked to original sources
PubMed2005

A comparison of spreader penetration depth and load required during lateral condensation in teeth prepared using various root canal preparation techniques.

AIM: To compare the influence of various root canal preparation techniques on spreader penetration depth and load required during lateral condensation with gutta-percha and sealer. METHODOLOGY: Eighty extracted human teeth with single and straight canals were used. Twenty teeth were instrumented using one of four root canal preparation techniques. The four preparation techniques were: step-back technique without Gates-Glidden drills, step-back technique with Gates-Glidden drills, crown-down pressureless technique and hybrid technique (step-down/step-back). After root canal preparation had been completed a simulated periodontal ligament was fabricated from a uniform layer of silicone impression material. The roots were then mounted in an acrylic resin to simulate the physical condition found in tooth socket. A standardized stainless steel hand spreader of the same size as the master apical file was mounted in an Instron testing machine and lateral compaction with gutta-percha and sealer was performed. The load value was recorded from the Instron testing machine. The spreader penetration depths were measured with an endodontic ruler. The data obtained were analysed statistically using anova and Student's t-tests. RESULTS: No significant difference in initial spreader load needed to condense the master cone was found amongst the four canal preparation techniques (P > 0.05). The step-back technique with Gates-Glidden drills and the hybrid technique demonstrated the least difference between the initial spreader penetration and the working length (mean 1.925 and 2.25 mm, respectively). The step-back technique without Gates-Glidden drills and the crown-down pressureless technique had the greatest difference between initial spreader penetration and the working length (mean 4.425 and 4.75 mm, respectively). CONCLUSION: The flare created by canal preparation affected spreader penetration depth, but had no effect on the spreader load.

Dental Pulp Cavity↗
PubMed2002

Scanning electron microscopy study of the adhesion of Prevotella nigrescens to the dentin of prepared root canals.

The purpose of this study was to evaluate the effect of the presence or absence of amorphous, irregular smear layers on the adhesion of Prevotella nigrescens, to the dentin of the root canal by using scanning electron microscopy (SEM). Human incisors extracted within 7 days, with no cavities, no fractures, and no evidence of calcification of the canal, were selected. After cutting the crown portion at the CEJ, root canal preparation was undertaken by using a modified crown-down technique with Profile and Gates Glidden drills. Ten milliliters of physiologic saline solution (groups 1 and 4), 10 ml of 3.5% NaOCl (groups 2 and 5), or 10 ml of NaOCl and 10 ml of 0.5 M EDTA (groups 3 and 6) were used as irrigation solution while preparing the canal. After vertical sectioning and ethylene oxide gas sterilization, samples (groups 1, 2, and 3) were immersed in brain-heart infusion broth with yeast extract, hemin, and menadione, inoculated with P. nigrescens (ATCC 33563), and incubated for 3 h at 37 degrees C. All samples were prepared for and observed with SEM. The data were analyzed by using t test and one-way ANOVA. Smear layer was observed to cover the entire root canal surface after root canal preparation. Smear layer was removed and the entrances of dentinal tubules opened widely after applying 3.5% NaOCl and 0.5 M EDTA. A significantly greater number of bacteria were found to adhere to those teeth in which a smear layer was present (p < 0.05). Given that the smear layer produced during root canal preparation promoted adhesion and colonization of P. nigrescens to the dentin matrix, it might also increase the likelihood of canal reinfection.

Analysis of Variance↗
PubMed1995

[In vitro comparison of instruments for root canal preparation. III. Study of the instruments from the viewpoint of shaping asymmetry].

The shape of the prepared root canals is not consistent with the original anatomical shape in the majority of curved canals. The discrepancy is dependent of the type of instrument, the original anatomical form of the root canal and the location of the measurement. The original shape of the root canal has to be taken into consideration in the selection of preparatory instruments because their application is limited by the above mentioned factor. The sonic and ultrasonic preparatory instruments form an exception in this respect due to their non aggressive way of shaping. These instruments cannot be disregarded in the preparation of curved root canals.

Dental Instruments↗
PubMed2005

Morphological study of the Er,Cr:YSGG laser for root canal preparation in mandibular incisors with curved root canals.

OBJECTIVE: The objectives of this study were to observe morphological changes of root canal walls and to evaluate the capability of Er,Cr:YSGG laser for preparation of curved mandibular incisor root canals in vitro. BACKGROUND DATA: There are no published reports on the use of Er,Cr:YSGG laser for curved root canal preparation. METHODS: Twenty curved mandibular incisor root canals (10 and 15 degrees) were prepared sequentially by laser irradiation at 20 Hz, 2 Wusing two different sizes of fine fiber tips (200 and 320 microm in diameters). After laser irradiation, the teeth were bisected longitudinally, and the specimens were observed by stereoscope and scanning electron microscope (SEM). RESULTS: Root canal walls of the irradiated areas showed step-like appearances and openings of dentinal tubules, and root canal preparation, having curvatures of less than 10 degrees, could be carried out by this laser irradiation. CONCLUSIONS: Er,Cr:YSGG laser irradiation is capable of preparing root canals having curvatures of less than 10 degrees.

Chromium↗
PubMed2006

An assessment following root canal preparation by Er,Cr: YSGG laser irradiation in straight and curved roots, in vitro.

In the present study, the effectiveness of Er,Cr:YSGG laser in straight and curved root canal preparation was compared with that of the conventional canal preparation technique, in vitro. The degree of root curvature of 40 root canals was determined, and then 20 canals were prepared by an Er,Cr:YSGG laser of 2 W by using the crown-down technique, while the other 20 canals were shaped by K-file (control). The achievement degree of root canal preparation and debris score was investigated morphologically. The results indicated that straight root canals could be successfully prepared by Er,Cr:YSGG laser irradiation; a significant decrease of smear layer or debris was also recognized (P<0.01). However, canal preparation by laser device in curve root often leads to a ledge or zipped formation, perforation or over-instrumentation. The results demonstrated that further development in laser device and technique are required to ensure its success in root canal preparation, especially in curve root.

Dental Pulp Cavity↗
PubMed2003

Root canal preparation with FlexMaster: asessment of torque and force in relation to canal anatomy.

AIM: To investigate physical parameters of FlexMaster nickel-titanium instruments while preparing curved canals in maxillary molars in vitro. METHODOLOGY: A torque-testing platform was used to prepare root canals in 11 extracted human maxillary molars with FlexMaster rotary instruments. Peak torque and force was registered along with numbers of rotations required to shape the canals. Canals were divided into 'wide' and 'constricted' groups depending on canal volumes assessed by microcomputed tomography. Resistance to cyclic fatigue was also tested. Mean scores for each instrument type were calculated and statistically compared using anova and Scheffé post hoc tests. RESULTS: Mean torque varied between 0.1 +/- 0.1 and 0.8 +/- 0.5 N cm while mean force ranged from 4.2 +/- 2.0 to 7.3 +/- 3.5 N. Mean numbers of rotations totalled up to 18. All three variables registered showed weak correlations to preoperative canal volumes (P < 0.01) and differed significantly between 'wide' and 'constricted' canals (P < 0.001). Numbers of rotations to fracture in a cyclic fatigue test were between 348 and 1362. CONCLUSION: FlexMaster instruments generated low torque scores and were highly resistant to cyclic fatigue, whilst three instruments fractured in extremely narrow canals. Consequently, more research is required to limit fracture incidence and to optimize instrumentation guidelines.

Analysis of Variance↗
PubMed2003

ProTaper rotary root canal preparation: assessment of torque and force in relation to canal anatomy.

AIM: To investigate physical parameters for ProTaper nickel-titanium (NiTi) rotary instruments whilst preparing curved canals in maxillary molars in vitro. METHODOLOGY: A novel torque-testing platform was used to prepare root canals in 15 extracted human maxillary molars with ProTaper rotary instruments. Peak torque and force was registered along with numbers of rotations required to shape the canals. Canals were divided into 'wide' and 'constricted' groups depending on canal volumes assessed by micro computed tomography. Mean scores for each instrument type were calculated and statistically compared using anova and Scheffé posthoc tests. RESULTS: Mean torque varied between 0.8 +/- 0.5 and 2.2 +/- 1.4 N cm whilst mean force ranged from 4.6 +/- 2.6 to 6.2 +/- 2.7 N. Mean numbers of rotations totalled up to 21. All three variables registered were significantly correlated to preoperative canal volumes (P < 0.001) and differed significantly between 'wide' and 'constricted' canals (P < 0.001). CONCLUSIONS: Whilst high forces were used in some cases, no ProTaper instrument fractured when a patent glide path was present. There were significant positive correlations between canal geometry and physical parameters during shaping.

Analysis of Variance↗
PubMed2000

The effect of root canal preparation on microleakage within endodontically treated teeth: an in vitro study.

AIM: The purpose of this study was to evaluate the effects of smear layer and canal instrumentation on leakage in root-filled teeth. METHODOLOGY: Six groups (n = 12) of freshly extracted human canines and premolars with closed apices and single roots were used. Groups A, B, C, and D were instrumented with engine-driven rotary nickel-titanium MCXIM files and Groups E and F were instrumented with conventional stainless steel hand files. Groups A, C, and E were flushed with 3.0 mL of 17.0% REDTA to remove the smear layer prior to obturation. All teeth were flushed with 5.25% NaOCl, then obturated with AH-26 sealer and either the lateral condensation (Groups C-E) or thermomechanical compaction technique (Groups A and B). Copper wire was placed coronally in contact with the gutta-percha in each tooth and, after immersion in 0.9% NaCl solution, a 10 volt dc voltage was connected between each tooth and a stainless steel electrode. The current flow in the circuit was observed for 45 days. One way ANOVA and Duncan's Multiple Range Test were used to compare Groups A-F at time intervals of 10, 20, 30 and 45 days and identify statistically significant differences. RESULTS: Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine-driven NiTi files exhibited less leakage than hand-instrumented canals irrespective of obturation method. CONCLUSIONS: Smear layer removal is beneficial to root canal sealing. Obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals.

Analysis of Variance↗
PubMed2004

The effectiveness of syringe irrigation and ultrasonics to remove debris from simulated irregularities within prepared root canal walls.

AIM: To compare the ability of syringe irrigation and ultrasonic irrigation to remove artificially placed dentine debris from simulated canal irregularities within prepared root canals. METHODOLOGY: After canal enlargement, twelve canines were split longitudinally into two halves. On the wall of one half of each root canal a standard groove of 4 mm in length, 0.2 mm in width and 0.5 mm in depth was cut, 2-6 mm from the apex, to simulate uninstrumented canal extensions. On the wall of the other half, three standard saucer-shaped depressions of 0.3 mm in diameter and 0.5 mm in depth were cut at 2, 4 and 6 mm from the apex to simulate uninstrumented canal irregularities. Each groove and depression were filled with dentine debris mixed with 2% NaOCl to simulate a situation when dentine debris accumulates in uninstrumented canal extensions and irregularities during canal preparation. Each tooth was re-assembled by reconnecting the two halves, using wire and an impression putty material. Two per cent NaOCl was then delivered into each canal either using syringe irrigation (n = 8) or using ultrasonic irrigation (n = 8). Before and after irrigation, images of the two halves of the canal wall were taken, using a microscope and a digital camera, after which they were scanned into a PC as TIFF images. The amount of remaining dentine debris in the grooves and depressions was evaluated by using a scoring system between 0-3: the higher the score, the more the debris. The data were analysed by means of the Mann-Whitney U-test. RESULTS: Both forms of irrigation reduced the debris score significantly. The debris score was statistically significantly lower after ultrasonic irrigation than after syringe irrigation (P = 0.002 for grooves, P = 0.047 for depressions). CONCLUSION: Ultrasonic irrigation ex vivo is more effective than syringe irrigation in removing artificially created dentine debris placed in simulated uninstrumented extensions and irregularities in straight, wide root canals.

Cuspid↗
PubMed2005

Root canal preparation with Endo-Eze AET: changes in root canal shape assessed by micro-computed tomography.

AIM: To evaluate the relative performance of Endo-Eze Anatomic Endodontic Technology (AET) stainless steel instruments when shaping maxillary molar root canals in vitro. Methodology Extracted human maxillary molars were scanned, before and after root canal shaping with Endo-Eze AET, employing micro-computed tomography (muCT) at an isotropic resolution of 34 microm. Three-dimensional root canal models were reconstructed and evaluated for volume, surface area, 'thickness' (diameter), canal transportation and prepared surface. Preparation errors such as apical zips, perforations and fractured instruments were visually determined from those models. Means were contrasted using anova and Scheffé post-hoc tests. RESULTS: Volume and surface area increased significantly and similarly in mesiobuccal (mb), distobuccal (db) and palatal (p) canals and gross preparation errors (n = 17) were found. Mean root canal diameters, 5 mm coronal to the apex, increased from 0.31 to 0.52, 0.35 to 0.50 and 0.50 to 0.70 mm for mb, db and p canals, respectively. Mean canal transportation ranged from 0.15 to 0.29, 0.15 to 0.27 and 0.21 to 0.33 mm for apical, middle and coronal root canal levels, respectively, with highest values found for mb canals (P < 0.003). Root canals were significantly straightened during preparation (P < 0.002). CONCLUSIONS: In summary, Endo-Eze AET instruments shaped root canals in maxillary molars with substantial canal transportation, particularly in mesiobuccal root canals. Preparation with this instrument removed high volumes of dentine, even though apical preparation was size 30. Based on the current results, Endo-Eze AET cannot be recommended for the preparation of teeth with curved root canals.

Analysis of Variance↗
PubMed1997

Effect of tip design of nickel-titanium and stainless steel files on root canal preparation.

The purpose of this study was to evaluate the effect of modified and non-modified tip designs of both stainless steel and nickel-titanium endodontic hand files on root canal preparation. Root canals of mesial roots of extracted mandibular molars were prepared using a quarter-turn-pull technique. The experimental design permitted comparison of the effects of nickel-titanium alloy construction or file tip modification alone, with effects when these two factors were incorporated into a single file design. Transportation, centering ratio, and dentin removal were evaluated using a modified Bramante technique. Nickel-titanium files, regardless of tip design, remained significantly more centered and demonstrated less apical transportation than stainless steel files at size 25. When instrumentation was continued to size 40 apically with step-back, there were no significant differences in transportation in the apical or coronal sections. However, during instrumentation to size 40 with step-back, the combination of modified tip and nickel-titanium alloy produced significantly more transportation and dentin removal, as well as greater deviation from the center at the mid-root level than did other file designs. Thus, of the file design parameters evaluated in this study, construction from nickel-titanium was most important in defining canal configuration at small file sizes in the apical region. Although the combination of nickel-titanium and modified tip design resulted in more transportation at larger file sizes in the midroot region, such alterations in canal configuration may be of little importance clinically. Nonetheless, it is suggested that other factors, such as tactile sensation and instrumentation technique, should be considered as important as the type of alloy or tip design.

Analysis of Variance↗
PubMed1996

[In vitro comparative study of instruments for root canal preparation. IV. Correlations between the original shape of the root canal and the asymmetry resulting from the preparation].

Certain asymmetry of root canal preparation can be observed in the straight root canal group, as well. The modification of original root canal shape in this group usually is not substantial. Using hand instruments for shaping curved canals special tecniques are required to minimize the asymmetry. Though tendencies of different shaping characteristics can be observed on the mesiodistal and oro-vestibular views there are no statistically significant differences between the asymmetries measured on the oro-vestibular and mesio-distal views. The three dimensional form of canals usually exclude the possibility of forming the same asymmetry on both projections, but the difference between the two views is not striking, therefore the conventional clinical radiographs usually do not give complete information about the asymmetry of preparation.

Dental Instruments↗
PubMed2006

The importance of apical patency and cleaning of the apical foramen on root canal preparation.

The apical limit of root canal instrumentation has always been a matter of great controversy. Despite the large number of published studies on this subject, a consensus has not yet been reached. In fact, the recent discussion on apical patency and cleaning of the apical foramen, as well as the incorporation of these procedures to the endodontic treatment, seem to have raised even more polemics. It is likely that all this polemics has its roots in the lack of interrelation between the theoretical knowledge of pulp stump and periapical tissues and the real clinical practice. By addressing the most important aspects of this theme, this paper aims to present news concepts about the importance of apical patency and cleaning of the apical foramen during root canal preparation.

Humans↗
PubMed2003

Comparison of procedural errors resulting during root canal preparations completed by junior dental students in patients using an '8-step method' versus 'serial step-back technique.'.

AIM: To compare procedural errors occurring during preparation of root canals by junior dental students in patients using a new '8-step method' versus traditional 'serial step-back technique. METHODOLOGY: Junior dental students treated 291 root canals of maxillary and mandibular teeth in patients. A new '8-step method' was used to prepare 149 canals, whilst the traditional 'serial step-back technique' was used for 142 root canals. Instrumentation was carried out in both techniques using standardized stainless steel K-files and coronal flaring with Gates-Glidden reamers. In the apical one-third, a filing motion was used in the traditional technique: with the '8-step method,' reaming or filing motions were used in sizes up to 25 and only reaming in sizes larger than 25. All root canals were obturated with gutta-percha points and AH26 using a lateral condensation technique. Pre- and postoperative radiographs were made of each tooth. Procedural errors were recorded and statistically analysed using a binomic test for comparison of proportion. RESULTS: Significantly (P < (1.0001) more root canals maintained their original shape with no deviation (91%) with the'8-step method' compared to the traditional 'serial step-back technique' (61%). The procedural errors detected with the'8-step method' consisted of 10 canals with transportation (5%) and five with root perforations (2%); there were no canal obstructions. With the 'serial step-back technique: significantly (P < 0.0001) more errors occurred: 28 canals were transported (17%), 10 had root perforations (7%), and 16 canals were obstructed (6%). The differences in maintaining the original root canal shape between the two methods were significantly greater in molar versus anterior teeth. CONCLUSIONS: The new '8-step method' resulted in fewer procedural errors than the traditional 'serial step-back technique' when junior students prepared root canals in patients.

Dental Pulp Cavity↗
PubMed2005

[Root canal preparation: shaping and cleaning of the root canal].

Primary shaping is of paramount importance for a succesfull root canal treatment. In this article the basis principles of apical terminus location, shape, size and diameter are discussed. The use of NiTi instruments and crown-down preparation techniques are explained.

Dental Instruments↗
PubMed2004

[Effect of ultrasonic in instrumentation on curved and obstructed root canal preparation].

PURPOSE: To investigate and evaluate the effect of ultrasonic instrumentation on curved and obstructed root canal preparation. METHODS: Ultrasonic preparation was used on 117 root canals of 92 teeth due to resinifying therapy, pulp mummification and aging which could not be reopened and treated with traditional methods. RESULTS: 108 canals were successfully reopened with a successful rate of 92.3%. Failure occurred in 9 cases. 2 of them were lateral perforation. 2 were obstructed on curving position. 2 of them were due to pulp calcification in older patients. 3 were failing after resinifying therapy. CONCLUSION: The ultrasonic treatment of root canal was an effective and safe method. It was still limited in a cases with pulp calcification and some fine root canals treated by resinifying therapy.

Adult↗