Yared G. Canal preparation using only one Ni-Ti rotary instrument: preliminary observations. International Endodontic Journal. Aim To describe a novel canal preparation technique using only one Ni-Ti rotary instrument. Summary In this novel technique, the canal is negotiated to the working length with a size 08 hand file. Then, the canal preparation is completed with an F2 ProTaper instrument used in a reciprocating movement. In larger canals, the use of additional hand files may be required to complete the apical enlargement. Key learning points • A novel canal preparation technique is introduced using only one Ni-Ti rotary instrument in a reciprocating movement. • The advantages of the technique include a reduced number of instruments, lower cost, a reduced instrument fatigue and the elimination of possible prion cross-contamination associated with the single use of endodontic instruments.

https://www.endoexperience.com/documents/Oneinstrumenttechnqiue-Yared.pdf

Canal preparation using only one Ni-Ti rotary instrument: preliminary observations

Burklein S, Hinschitza K, Dammaschke T, Schafer E. Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper. Interna- tional Endodontic Journal. Aim To compare shaping ability and cleaning effec- tiveness of two reciprocating single-file systems with Mtwo and ProTaper rotary instruments during the preparation of curved root canals in extracted teeth. Methodology A total of 80 root canals with curva- tures ranging between 25� and 39� were divided into four groups of 20 canals. Based on radiographs taken prior to instrumentation, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared to the following apical sizes: Mtwo: size 35 using the single-length technique; ProTaper: F3, instruments were used in a modified crown-down manner; Reciproc and WaveOne: size 25. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Preparation time and instrument failures were also recorded. These data were analysed statistically using anova and Student-Newman-Keuls test. The amounts of debris and smear layer were quantified on the basis of a numerical evaluation scale and were analysed statisti- cally using the Kruskal-Wallis test. Results During preparation no file fractured. All instruments maintained the original canal curvature well with no significant differences between the differ- ent files (P = 0.382). Instrumentation with Reciproc was significantly faster than with all other instruments (P 0.05), while ProTaper showed significantly more residual debris (P 0.05). Conclusions Under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. The use of Mtwo and Reciproc instruments resulted in better canal cleanli- ness in the apical part compared with ProTaper and WaveOne.

Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper.

The expanded use of nickel-titanium (NiTi) rotary instruments in root canal procedures has led to the development of a wide variety of shapes, designs and applications. Root canal anatomy has not changed, however, and the same challenges exist in both initial treatment and the revision of unacceptable treatment. These challenges include application with high levels of achievement and low to no levels of adverse effects, such as instrument fracture, root canal wall ledging, dentine wall perforation and so forth. To that end, many manufacturers have been seeking ways to alter the presently available and wide range of root canal instrument designs, with a focus on altering the surface of the alloy or altering the alloy microstructure with post-machining or post-twisting heat treatment. This focused review will address the impact that these modifications have had on instrument flexibility, resistance to cyclic fatigue and cutting efficiency.

Alteration in the inherent metallic and surface properties of nickel-titanium root canal instruments to enhance performance, durability and safety: a focused review.

http://www.repositorio.ufc.br/bitstream/riufc/6368/1/2012_art_gtmcandeiro.pdf

Resistance to Flexural Fatigue of Reciproc R25 Files under Continuous Rotation and Reciprocating Movement

Aim To investigate instrumentation time, working safety and the shaping ability of two rotary nickel–titanium (NiTi) systems (Alpha System and ProTaper Universal) in comparison to stainless steel hand instruments.

Methodology  A total of 45 mesial root canals of extracted human mandibular molars were selected. On the basis of the degree of curvature the matched teeth were allocated randomly into three groups of 15 teeth each. In group 1 root canals were prepared to size 30 using a standardized manual preparation technique; in group 2 and 3 rotary NiTi instruments were used following the manufacturers’ instructions. Instrumentation time and procedural errors were recorded. With the aid of pre- and postoperative radiographs, apical straightening of the canal curvature was determined. Photographs of the coronal, middle and apical cross-sections of the pre- and postoperative canals were taken, and superimposed using a standard software. Based on these composite images the portion of uninstrumented canal walls was evaluated.

Results  Active instrumentation time of the Alpha System was significantly reduced compared with ProTaper Universal and hand instrumentation (P < 0.05; anova). No instrument fractures occurred in any of the groups. The Alpha System revealed significantly less apical straightening compared with the other instruments (P < 0.05; Mann–Whitney U test). In the apical cross-sections Alpha System resulted in significantly less uninstrumented canal walls compared with stainless steel files (P < 0.05; chi-squared test).

Conclusion  Despite the demonstrated differences between the systems, an apical straightening effect could not be prevented; areas of uninstrumented root canal wall were left in all regions using the various systems.

Ex vivo study on root canal instrumentation of two rotary nickel–titanium systems in comparison to stainless steel hand instruments

Effect of prion decontamination protocols on nickel-titanium rotary surfaces

The aim of this paper was to examine the result of rotary root canal preparation with the nickel-titanium (NiTi) systems K3, ProTaper and Mtwo. One hundred and fifty curved artificial root canals and 60 mesial canals of human mandibular molars were selected. In the group of curved artificial canals, all canals were prepared to size 35/0.04 taper with the three systems. In the group of human mandibular molars, the teeth with mature root canals were radiographed with silver points inserted in bucco-lingual and in mesio-distal positions. In the artificial root group, one K3 instrument separated. Mtwo (20%) showed significantly (P = 0.003) less zips than K3 (46.9%) or ProTaper (50%). There were no significant differences in ledge and elbow formation. K3 and Mtwo had the lowest percentage of canal transportation. There was no significant difference regarding the preparation length or the condition of the apical foramina following the preparation. Canals prepared with K3 (26.5%) were significantly (P < 0.001) less tapered than ProTaper (62%) and Mtwo (82%). In the human mandibular molar group, one Mtwo and one ProTaper instrument separated. No significant differences were found in the preparation length, transportation or taper. The three systems tested, K3, Mtwo and ProTaper, achieved good preparation results.

Root canal preparation with the NiTi systems K3, Mtwo and ProTaper

The aim of this paper is to present a new method based on numeric calculus to provide data on any type of root canal curvature at any point of the long axis of the canal. Twenty severely curved, simulated root canals were prepared with rotary FlexMaster and Profile instruments in the crown-down technique and manually in the step-back technique. The inner and outer curvatures were registered in a system of coordinates before and after preparation in increments of 0.5 mm. Using an equalising function, the curvatures were first represented in graphic and algebraic form. The maximum and the mean curvature as well as the length of the arc from the apical foramen to the point of maximum curvature were determined mathematically. An increase in maximum curvature was registered for all four shaping systems investigated. The radius of the inner curvature decreased by 0.5-1.2 mm in the manual systems as a result of the preparation. The Profile system displayed the smallest changes in radius (-0.9 mm) even with the outer curvature, and manual preparation with stainless steel files the most pronounced change (-1.8 mm). The point of maximum curvature at the inner curvature was displaced by 1.6 mm to the apical foramen through manual preparation with Ni-Ti files. At the outer curvature, the maximum displacement (1.8 mm) recorded was also the result of preparation with Ni-Ti hand files, while a displacement of only 0.3 mm to the apical foramen was recorded with the other systems. The method offers a means of determining curvatures precisely without random specification of reference points. The method is also capable of registering only minor changes in curvature in the two-dimensional long axis of the canal.

/pdf/determination-of-root-canal-curvatures-before-and-after-141wya0v70.pdf

Determination of root canal curvatures before and after canal preparation (part II): A method based on numeric calculus

The continuing development of methods and materials for root canal preparation is resulting in enhanced preparation techniques with only minor alterations to the canal morphology. Improved evaluation methods are required for differentiated assessment of these innovations. One criterion for assessment of the preparation quality of curved root canals is preparation-induced straightening of the canal.

The first canal curvature measurements served to divide teeth into different curvature classes. However, their actual execution represented mere angular measurement rather than root curvature assessment. This purely graphic method lacked precision, nor could it be readily applied to all tooth groups. Further developments of that method resulted in it being applicable to molars and to canals with multiple curvatures.

Some years ago, the graphically determined curvature radius was added as a further parameter to measurement of the canal deviation angle, thus permitting a curvature to be correctly described for the first time in geometric and analytic terms. The first mathematically accurate description was presented by Dobo-Nagy et al. (20), who correctly described the mean canal curvature in a two-dimensional image in concrete terms by means of fourth-degree polynomial functions.

Recent developments in the application of microcomputed tomography of extracted teeth permit non-destructive three-dimensional assessment of root canal configurations. It remains to be seen whether this resource-intensive form of in vitro examination can assert itself.

Determination Of Root Canal Curvatures Before And After Canal Preparation (Part 1): A Literature Review

Objectives The aim of this study was to determine radiographic and microscopic appearances of root canal fillings performed by undergraduate students using vertical and lateral compaction techniques. Study design Thirty dental students were instructed how to fill curved simulated canals with gutta-percha and sealer using lateral and vertical compaction. Digital radiographs were taken in buccolingual and mesio-distal projections; radiographs were evaluated for homogeneity and root canal wall contact. Plastic blocks with simulated canals were sectioned and cross sections were assessed under a light microscope for voids. Probabilities were expressed as odds ratios (OR) with 95% confidence intervals (CI). Results Radiographs showed that the chances of obtaining a homogeneous root canal filling by using a vertical compaction technique were 3 times higher in the coronal canal third (OR 3.2; CI: 1.9, 5.3), the same in the middle third, and 2 times higher in the apical third (CI: 1.1, 2.4) than when using lateral compaction. Microscopic evaluation of the same canals revealed that the chances of obtaining a homogeneous root canal filling by vertical compaction were 3 times higher in the coronal canal third (CI: 1.6, 5.8), almost 3 times higher in the middle canal third (CI: 1.6, 4.7), and about 10 times higher in the apical canal third (OR 9.8; CI: 2.2, 43.4) than by lateral compaction. The chances of transporting filling material beyond the apex were almost 5 times higher (OR 4.6; CI: 2.8, 7.6) when using vertical rather than lateral compaction. Conclusion Inexperienced students obtained more homogeneous root canal fillings with the vertical compaction method; however, the probability of overextruding filling material with this method was high.

David Sonntag

Papers

Effect of prion decontamination protocols on nickel-titanium rotary surfaces

Root canal preparation with the NiTi systems K3, Mtwo and ProTaper

Determination of root canal curvatures before and after canal preparation (part II): A method based on numeric calculus

Determination Of Root Canal Curvatures Before And After Canal Preparation (Part 1): A Literature Review

Homogeneity of root canal fillings performed by undergraduate students with warm vertical and cold lateral techniques.