Alvarado, 2022. Revista Científica Guatemalteca de Odontología, vol. 1 núm.1 pp. 01-14

Influcia d Cre d

Gde Ph  la Fractura de

Itrumtos Rotorios

Influce of the Gde Ph

Cer  the Fracture of

Rotary Itrum

Alvarado-Barrios, Carlos1 ;; Durán-Sindreu Terol, Fernando2 ; Roig Cayón, Miguel2 ; Alvarado-Cerezo, Carlos1

ABSTRACT

During endodontic procedures, the potential for

instrument fracture is present; Any attempt must be

made to avoid this complication, because its solution

is complex, requiring skill, equipment and time.

Aim: To evaluate the inﬂuence of manual glide path

caliber on the fracture frequency of mechanical

rotary instruments.

Methodology: Recently extracted mandibular

molars were selected, permeabilizing the canals with

K08 and 10 ﬁles, independent canals were included.

Radiographs with K10 inside, applying the Pruett

method, recording the maximum value for the angle

and the minimum value for the radius between the

two views (clinical and proximal). The teeth were

classiﬁed according to the angle and radius of

curvature and the initial apical caliber, using the

mesiobuccal canal with one group and the

mesiolingual canal with another. The sample was 60

canals. Groups were randomly assigned. The glide

path was performed, with a K ﬁle, balanced force

technique, irrigating between ﬁles. An inexperienced

operator mechanically instrumented according to the

manufacturer's sequence, the number of uses of

each instrument was controlled, each instrument

used was observed with a microscope, and the

fractures were conﬁrmed radiographically. The data

obtained were analyzed using Proportions Test and

One Way ANOVA Test. A p-value ≤ 0.05 was

established.

Results: 6 instruments were separated when the

glyde path was performed up to K10, 5 up to K15

and 1 up to K20.

Conclusions: The caliber of the manual glide path

inﬂuences the fracture frequency of mechanical

rotary instruments, when it is performed by

inexperienced operators.

KEYWORDS: manual pre-ﬂaring; mechanical

instrumentation; fracture of instruments; ProTaper;

rotary instruments.

RESUMEN

Durante la conformación endodóntica, la posibilidad

de fractura de instrumentos está presente; cualquier

intento debe hacerse para evitar dicha complicación,

porque su solución es compleja, requiere habilidad,

equipamiento y tiempo.

ISSN: 2957-8655

https://doi.org/10.56818/odontologia.v1i1.8

1DDS, MSc, PhDst Facultad de Odontología, Universidad de San

Carlos de Guatemala (USAC)

2DDS, MSc, PhD Facultad de Ciencias de la Salud, Universitat Internacional de

Catalunya (UIC)

Correspondencia al autor: Dr. Carlos Alvarado Barrios

Ciudad Universitaria zona 12, Edificio M4, of. 102, 01012, Ciudad de Guatemala,

Guatemala, Centro América.

Correo electrónico: [email protected]

Recibido: 10/08/2022

Aceptado: 04/11/2022

Revista Científica Guatemalteca de Odontología

Escuela de Estudios de Postgrado de la Facultad de Odontología de la Universidad

de San Carlos de Guatemala

ISSN 2957-8655

revistacientifica@postgradosodontologia.edu.gt

odontologiagt.org

Carlos Alvarado Cerezo, este es un artículo de acceso abierto, protegido bajo una

licencia internacional CC BY 4.0 y por la ley de derecho de autor de Guatemala,

decreto número 33-98 del Congreso de la República de Guatemala y por el artículo

451 del Código Civil de la República de Guatemala.

Objetivo: Evaluar la inﬂuencia del calibre del glide

path manual en la frecuencia de fractura de los

instrumentos rotatorios mecánicos.

Metodología: Se seleccionaron molares

mandibulares recientemente extraídos,

permeabilizando los conductos con limas K08 y 10,

se incluyeron los conductos independientes.

Radiografías con K10 en su interior, aplicando el

método de Pruett, registrándose el valor máximo

para el ángulo y el valor mínimo para el radio entre

las dos vistas (clínica y proximal). Se clasiﬁcaron los

dientes de acuerdo al ángulo y radio de curvatura y

al calibre apical inicial, utilizando el conducto

mesiovestibular con un grupo y el mesiolingual con

otro. La muestra fue 60 conductos. Se asignaron los

grupos aleatoriamente. Se realizó el glide path, con

lima K, técnica de fuerzas balanceadas, irrigando

entre limas. Un operador inexperto instrumentó

mecánicamente con secuencia del fabricante, se

controló el número de usos de cada instrumento, se

observó cada instrumento utilizado con microscopio,

conﬁrmándose las fracturas radiográﬁcamente. Los

datos obtenidos fueron analizados mediante Test de

Proporciones y Test One Way ANOVA. Se estableció

un p-valor ≤ 0.05.

Resultados: Se separaron 6 instrumentos cuando

el glyde path se realizó hasta K10, 5 hasta K15 y 1

hasta K20.

Conclusión: El calibre del glide path manual inﬂuye

en la frecuencia de fractura de los instrumentos

rotatorios mecánicos, cuando ésta es realizada por

operadores inexpertos.

PALABRAS CLAVE: Vía lisa y reproducible;

instrumentación mecánica; fractura de instrumentos;

ProTaper; instrumentos rotatorios.

INTRODUCTION

There are great differences of opinion regarding the

best methods of preparing root canals. Cases of

endodontic failures provide irrefutable evidence that

unresolved controversies perpetuate clinical failures

and decrease success rates.

Clinicians must continually try to discover the most

effective techniques , supported by independent

studies. This work focuses on the fundamental

concepts, strategies and techniques in practice that

can provide superior results in cleaning and shaping

root canals.

As it is, the establishment of a free and reproducible

path (glide path), prior to mechanical

instrumentation, in order to avoid fracture of the

instruments, which could compromise the success

of the endodontic treatment .

The main objective of Endodontics is to preserve the

dental organ1, and it achieves this through the

formation, disinfection and three-dimensional ﬁlling of

the root canal system.

Meeting objectives:

-Biological

-Radiographic

-Clinical2

Fig. 1 Root canal treatment

All of this must be achieved without creating

iatrogenic mishaps3, such as blockages, steps,

transportation, perforations, or fracture of

instruments.

The conformation of the canals is a critical aspect4, 5

because it inﬂuences the result of the

complementary phases, such as irrigation,

obturation, and therefore, the success of the

treatment itself.

This shaping is carried out mainly using manual and

motor-driven or mechanical instruments. The

instruments Mechanical elements can be made of

stainless steel, carbon steel or nickel - titanium.

Its properties include:

-Shape memory5, that is, the ability to return, in the

event of deformation, to its initial shape.

-Low elasticity or Young's modulus5, which is

deﬁned as the result of the ratio between the

tension applied to a body and the deformation it

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produces (it is a typical constant value for each

material).

-High elastic limit or resilience5, which is the

property of storing energy when the material

deforms.

-Corrosion resistance5.

All this made this alloy attractive to Andreasen and

collaborators, who in 1971 incorporated it into the

world of Dentistry, speciﬁcally in the ﬁeld of

orthodontics.

These phenomena are possible thanks to certain

structural transformations:

-Austenitic-Martensitic6, which consist of the

change of its crystalline structure from a primary

phase called austenitic in which the structure is

cubic, centered and stable, to a secondary or

martensitic phase, in which it becomes dense

hexagonal.

-Super Elasticity Transition Phase6: Between both

phases there is a change stage, which gives rise

to a third super elasticity transition phase, where

the best characteristics of the alloy are obtained.

Currently there are many mechanical instrumentation

systems, one of the most recognized and used

worldwide is the ProTaper® system (Dentsply-

Maillefer, Ballaigues, Switzerland), which was

presented during the American Association of

Endodontics (AAE) congress in the year 20017, 8, 9.

The main characteristics of the ProTaper® System

according to its manufacturer are:

-Multiple and progressive taper (2%-19%)10, which

makes possible the formation of speciﬁc sections

of the root canal, S1 is designed to prepare

mainly the coronal third, S2 the middle third and

F1, F2 and F3 the apical third.

-Convex triangular cross section8: The convex

triangular cross section (ﬁg. 4) results in a reduced

contact area between the dentin and the cutting

turns of the instrument, accentuating its cutting

efﬁciency, thus reducing stress torsional and

facilitating the widening of the root canal.

-Variable pitch (no. of turns per mm.)11: or variable

helical angle, which is the angle formed between

the cutting groove and the longitudinal axis of the

instrument, the balanced coils in the instrument

improve its cutting action, allowing better removal

of debris out of the canal and preventing the

instrument from becoming wedged in the walls of

the canal (screwing effect).

-Partially inactive tip12, 13

-Positive cutting angle10

-Short handle12

Fig. 2 a)Radial land F3; b)cross section; c)multiple taper

Shaping ﬁles (or S ﬁles) have multiple and

progressive taper:

SX: D0 = 0.19mm; 3,5% - 19% D1 a D9 y 2% D10

a D14

S1: D0 = 0.17mm; 2% - 11% D1 a D14 ≈ 4%

S2: D0 = 0.20mm; 4% - 11.5% D1 a D14 ≈ 4.5%

The Finishing ﬁles (or F ﬁles), have multiple and

decreasing taper, the decreasing taper ensures

continuous ﬂexibility of the ﬁle and avoids a large

diameter along the axis of the instrument:

F1: D0 = 0.20mm; 7% D1 - D3, disminuir hasta D14

≈ 5.5%

F2: D0 = 0.25mm; 8% D1 - D3, disminuir hasta D14

≈ 5.5%

F3: D0 = 0.30mm; 9% D1 - D3, disminuir hasta D14

≈ 5.5%

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With the introduction of NiTi rotary instruments, there

was an increase in the frequency of fractured

instruments14, 15, 16, not because the alloy fractures

more, in fact it is more resistant, but mainly due to

misuse of the nickel-titanium instruments.

NiTi instruments can fracture for two main reasons:

$- Torsion

$- Cyclic fatigue6, 17, 18, 19, 20

When there is separation of the instrument, the

disinfection, conformation and obturation of the

canal system is compromised, and the prognosis

conditioned, because remnants of pulp tissue and

bacteria may remain, thus compromising the

success of the treatment.

Torsion fracture occurs when the tip or any other

part of the instrument becomes wedged in the walls

of the canal and becomes blocked, while the

handpiece and the rest of the instrument continue to

rotate; When this occurs, the elastic limit of the alloy

is exceeded, and leads to separation of the

instrument; This type of fracture is due to the

application of excessive force apically during

instrumentation.

Cyclic fatigue fracture occurs when a freely rotating

instrument, which has been previously weakened by

alloy fatigue, is placed under stress and various

other factors, these cause the alloy to go from the

austenitic phase to the martensitic phase. , and that

is when the fracture of the instrument occurs at the

point of maximum ﬂexion (maximum stress).

Among the different factors that inﬂuence the

separation of NiTi rotary instruments we have:

-Anatomy (mainly the angle and radius of

curvature)21

-Access22, 23

-Operator experience24

-Electric motors with torque and speed control6

-Instrument design10

-Inadequate work protocol10

-Dentin chips and gaps25

Among the main design variations, which took place

when moving from manual to mechanical

instruments, was the change from having an active

tip (cutting) to an inactive one (non-cutting).

This gives the instrument the ability to remain and

work more centered in the canal, thereby achieving

less deformation and transportation; In addition,

avoiding the creation of steps and perforations in the

walls of the canals.

This innovation becomes the main cause of fracture,

which the endodontist can control,26, 27, 28 because

when this non-cutting tip encounters a portion of the

canal that is narrower than its size, it cannot

penetrate and twists in such a way. portion, while the

rest of the instrument continues to rotate; When the

elastic limit of the alloy is exceeded, torsion fracture

occurs.

This is why the manufacturers of the various NiTi

mechanical instrumentation systems, and especially

the ProTaper® System, recommend the

establishment of a continuous, smooth and

reproducible path (Glide Path) prior to the use of

mechanical instrumentation.10

According to the manufacturer, the glide path should

be done with K-type hand ﬁles up to 15 gauge

(ISO)10, 12, 17, 18, 26

In the current literature there is a consensus that it is

important to perform manual instrumentation (glide

path), prior to mechanical instrumentation,10, 12, 17, 18,

26 but there is no consensus as to what caliber such

manual instrumentation should be performed.

It seems that there are very few studies to date that

evaluate the inﬂuence of glide path caliber on the

percentage of fracture or permanent deformation of

Ni-Ti instruments.

That is why the objective of this study is to determine

the inﬂuence of the glide caliber path, in the

instrument separation of the ProTaper® system.

MATERIAL AND METHODS

Recently extracted mandibular molars were

selected, with complete root development of the

mesial root, the teeth were stored in physiological

saline. With the help of a handpiece and a carbide

disc, the distal root was sectioned.

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Fig. 3 Initial photos and section of the distal root

An initial x-ray was taken (Kodak, Stuttgart,

Germany) both in the vestibulo-lingual (clinical view)

and mesio-distal (proximal view) direction.

Fig. 4 Initial radiographs

The access cavity was created, with a DG16

endodontic explorer (Hu-Friedy Inc., Chicago, Illinois)

the main canals (mesiobuccal, mesiolingual and

distal) were located. Occlusal wear was carried out

(cuspid reduction) to have a stable reference point

when determining the working length and

throughout the procedure. Once the canals were

located, they were catheterized and permeabilized

with 08 and 10 gauge type K manual ﬁles (Dentsply-

Maillefer, Ballaigues, Switzerland), impregnated with

glyde® (Dentsply-Maillefer, Ballaigues, Switzerland),

discarding any teeth that were not permeable.

Fig. 5 Access cavity

Once permeable, teeth in which their canals had the

same apical foramen were discarded. Only samples

that had independent canals (Vertucci type IV) under

magniﬁcation (Zeiss Opni Pico dental microscope,

Germany) at 25x were taken into account. At the

same time, the working length (LT) was determined

by subtracting 0.5mm from the length at which the

ﬁle emerges from the apical foramen.

Fig. 6 Vertucci type IV canals and determination of LT

For this conﬁrmation, and to analyze the angle and

radius of curvature of each canal, a radiography, with

K10 ﬁles inside, in vestibulo-lingual and mesio-distal

projection, applying the Pruett method, recording the

highest value for the angle and the minimum value

for the radius between the two views (view clinical

and proximal).

Fig. 7 Rx. To analyze the angle and radius of curvature

with the Pruett method

Samples that had canals with an initial caliber greater than

a K20 ﬁle were discarded.

To try to control the anatomical variable, the sample

was distributed in such a way that the mesiobuccal

canal was part of one group, while the mesiolingual

canal of the same tooth was part of another.

Fig. 8 Distribution of the different sample groups

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The teeth were classiﬁed according to the angle and

radius of curvature and the initial apical caliber. In

total, the ﬁnal sample was 30 teeth (60 canals)

divided into three groups (glide path with K10, K15

or K20), being classiﬁed as follows:

Tabla 1 Ángulo y radio de curvatura del grupo A

Tabla 2 Ángulo y radio de curvatura del grupo B

Tabla 3 Ángulo y radio de curvatura del grupo C

The groups were assigned randomly: A = glide path

K10; B = glide path K15 and C = glide path K20.

It was carried out the glide path, with the type K ﬁle

impregnated with Glyde® (Dentsply-Maillefer,

Ballaigues, Switzerland), with balanced force

technique, performing irrigation with 3 ml of 4.2%

sodium hypochlorite (Conejo, Henkel, Barcelona,

Spain) between ﬁles, using a 27 gauge syringe and

needle.

An inexperienced operator was then calibrated to

perform the mechanical instrumentation in the

sequence proposed by the manufacturer for short

canals, that is, S1, SX, S1, S2; applied with an

electric motor with torque and speed control ATR®

(Dentsply-Maillefer, Ballaigues, Switzerland).

Fig. 9 Files used in the study

During instrumentation, the time until reaching the

working length was recorded, as well as the

instrumentation time, without counting the irrigation

time or the change of ﬁles.

It is controlled the number of uses of each

instrument, discarding them every 5 teeth (10

canals). Each instrument used was observed under

a dental microscope (Zeiss Opni Pico, Germany) at

25x magniﬁcation to determine deformations or

fractures, conﬁrming radiographically.

Fig. 10 Deformed, normal and fractured instrument

The data obtained were analyzed using a

Proportions Test for the qualitative variables and the

One Way ANOVA non-parametric statistical test for

the continuous quantitative variables. A signiﬁcance

level of 95% was established, p-value ≤ 0.05.

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Diente Conducto LT Ángulo V-L Radio V-L Ángulo M-D Radio M-D Máx. Curvatura Mín. Radio LAI Grupo

3B ML 19.5 29 14 38 13 38 14 K10 A

1A MV 20 22 16 34 16 34 16 K10 A

20A MV 19 24 18 45 12 45 18 K10 A

20B ML 18.5 24 18 11 22 24 22 K10 A

5A MV 17.5 25 20 13 24 25 24 K10 A

29B ML 16.5 18 24 32 19 32 24 K10 A

8B ML 19 14 12 12 27 14 27 K10 A

18A MV 19.5 36 18 31 29 36 29 K10 A

7A MV 20.5 30 29 34 7 34 29 K10 A

30B ML 18.5 26 30 0 0 26 30 K10 A

9B ML 19 38 22 20 36 38 36 K10 A

19A MV 19.5 32 36 31 33 32 36 K10 A

6B ML 15.5 27 14 9 37 27 37 K10 A

2A MV 21 16 40 14 38 16 40 K10 A

2B ML 21 16 40 18 37 18 40 K10 A

12A MV 21 28 28 11 50 28 50 K10 A

23A MV 18.5 18 24 13 50 18 50 K10 A

23B ML 18 18 24 12 75 18 75 K10 A

6A MV 17 27 14 D D DD K10 A

9A MV 18.5 38 22 D D DD K10 A

Diente Conducto LT Ángulo V-L Radio V-L Ángulo M-D Radio M-D Máx. Curvatura Mín. Radio LAI Grupo

16B ML 18 30 11 40 12 40 12 K15 B

8A MV 19.5 14 12 27 9 27 12 K15 B

14A MV 16 17 15 46 9 46 15 K15 B

15A MV 18.5 21 17 12 19 21 19 K15 B

13A MV 19.5 32 22 22 18 32 22 K15 B

26B ML 17.5 23 22 25 16 25 22 K15 B

1B ML 18.5 22 16 25 23 25 23 K15 B

14B ML 15 17 15 15 23 17 23 K15 B

24A MV 18.5 47 23 31 18 47 23 K15 B

28B ML 16.5 20 28 31 19 31 28 K15 B

22A MV 18 60 22 21 29 60 29 K15 B

10B ML 20 32 927 29 32 29 K10 B

5B ML 17.5 25 20 22 31 25 31 K15 B

4A MV 17.5 36 15 19 35 36 35 K15 B

15B ML 17.5 21 17 13 40 21 40 K15 B

17B ML 18.5 25 40 13 29 25 40 K10 B

12B ML 21 28 28 7 90 28 90 K15 B

19B ML 19 32 36 0 0 32 36 K15 B

7B ML 20.5 30 29 D D DD K10 B

21A MV 18.5 34 23 D D DD K15 B

Diente Conducto LT Ángulo V-L Radio V-L Ángulo M-D Radio M-D Máx. Curvatura Mín. Radio LAI Grupo

10A MV 20 32 920 14 32 14 K15 C

4B ML 16.5 36 15 14 11 36 15 K15 C

11B ML 19.5 47 15 22 18 47 18 K15 C

16A MV 19 30 11 20 19 30 19 K15 C

22B ML 17 60 22 45 18 60 22 K15 C

26A MV 16.5 23 22 0 0 23 22 K20 C

13B ML 18.5 32 22 27 23 32 23 K15 C

21B ML 18.5 34 23 22 22 34 23 K15 C

24B ML 18.5 47 23 29 22 47 23 K15 C

11A MV 19 47 15 29 27 47 27 K20 C

28A MV 16.5 20 28 17 29 20 29 K15 C

30A MV 19 26 30 30 15 30 30 K10 C

18B ML 19.5 36 18 16 31 36 31 K15 C

27A MV 11.5 21 40 0 0 21 40 K20 C

27B ML 11.5 21 40 0 0 21 40 K20 C

17A MV 18.5 25 40 18 38 25 40 K15 C

25A MV 19 16 47 19 34 19 47 K20 C

25B ML 18 16 47 0 0 16 47 K20 C

3A MV 19.5 29 14 D D DD K10 C

29A MV 16.5 18 24 D D DD K15 C

RESULTS

Tabla 4 Number of separated or despirated instruments

Finding that there are no statistically signiﬁcant

differences between Group A (glide path K10) and

Group B (glide path K15) with a p-value = 0.723255.

Among Group B (glide path K15) and Group C (glide

path K20), there are differences but not statistically

signiﬁcant with a p-value = 0.0765221.

While among group A (glide path K10) and group C

(glide path K20) there are statistically signiﬁcant

differences p-value = 0.0374679.

Tabla 5$Short sequence = S1, S2

$Normal sequence = S1, SX, S1, S2

$Long sequence = S1, SX, S1, SX, S1, S2

Finding that there are no statistically signiﬁcant

differences between the different groups p-value =

0.1087.

Tabla 6 Time in seconds to reach LT (net instrument. time)

Finding that there are statistically signiﬁcant

differences between the different groups, the glide

path group being faster K20 p-value = 0.0086.

Tabla 7 Time in seconds of mechanical instrumentation

(net instrumentation time)

Finding that there are no statistically signiﬁcant

differences between the different groups p-value =

0.0506.

Tabla 8 Time in seconds of total manual + mechanical

instrumentation (net instrumentation time)

There are no statistically signiﬁcant differences

between the different groups p-value = 0.7852.

DISCUSSION

Human teeth29, 30, 31, 32 were selected to maximally

reproduce the different physical and chemical

properties inherent to dentin, as well as the anatomy

of each tooth, since it has been demonstrated by

Kartal and Hale32, that humans teeth can present

various curvatures in the different views (clinical and

proximal) while acrylic blocks present standard

curvatures and only in one view.

Lower molars were selected32 due to the radius and

degree of curvature that they present, and because

the conﬁguration of the mesial canals of lower

molars creates greater technical difﬁculties for

dentists during chemical-mechanical preparation.

The population or race variable, not recorded in the

Group

Separate or despirated

instruments

A Glide Path K10

B Glide Path K15

C Glide Path K20

Group

Short

sequence

Normal

sequence

Long

sequence

Total

A Glide

Path K10

B Glide

Path K15

C Glide

Path K20

Group

Time LT

A Glide Path K10

27.32

B Glide Path K15

25.12

C Glide Path K20

14.9

Group

Total Time Mechanical

A Glide Path K10

31.89

B Glide Path K15

28.06

C Glide Path K20

19.55

Group

Total Time

A Glide Path K10

31.89

B Glide Path K15

33.06

C Glide Path K20

29.55

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study, may be important since different populations

may present characteristic anatomical features.

Cunningham and Senia33, as well as Kartal and

Hale32 found varying degrees of curvature in both

views (B-L and M-D). For this reason, radiographs

were taken in clinical and proximal views in order to

determine the degree and radius of curvature21, 34 of

both views and, thus, be able to determine the

maximum curvature and the smallest radius of each

canal, as described by Pruett21, and in this way

distribute the sample more homogeneously between

the different groups.

Radiographs were taken with the parallelism

technique35, using a long cone, both in the

buccolingual and mesiodistal directions, in order to

minimize radiographic distortion.

Endodontic access36 in standard form37, allowing as

direct access as possible to the apical third. For the

initial calibration of the canal, some authors such as

Tan et al.38 have recommended performing apical

calibration with lightspeed ﬁles, because these have

a small active part, an inactive tip and the stem is

without taper, which allows them to slide better

along the canal, thus avoiding any possible coronal

interference. In our study we do it with K ﬁles since it

reproduces what we generally use in daily practice,

what interests us most in this study is the glide path

or manual preﬂaring that is performed along the

entire canal with manual ﬁles.

To try to control the anatomical variable, the sample

was distributed so that the canals of the same tooth

were included in different groups, that is, the

mesiobuccal canal was instrumented with a certain

caliber of glide path, and the mesiolingual canal with

another glide path, alternating the groups in the

different teeth, thus, as far as possible, having two

similar canals, as done by Ankrum et. al.39 in his

studio.

The glide path of each group was carried out with

type K ﬁles, as in the article published by Elio

Berutti17 and also because they are sold worldwide,

impregnated in Glyde®, using the balanced force

technique (Roane technique), performing copious

irrigation with 3 ml of 4.2% sodium hypochlorite

between each ﬁle using a 27-gauge syringe and

needle.

An inexperienced operator was calibrated33 for

instrumentation with mechanical ﬁles, because if an

emerging technique or technology improves the

result of the work of an inexperienced operator, this

will be of equal beneﬁt, in hands with more

experience; but not the other way around.

For mechanical instrumentation, the electric motor

with torque and speed control ATR® was used12,

the instrumentation sequence was recommended by

the manufacturer for short canals and with brushing

movements as recommended by Blum et . al.10 for

ProTaper® Shaping Series9, 12.

Only the “shaping” series was used8, 9, 12, 38, 41 why

the glide path inﬂuences only these instruments and

not those of the “ﬁnishing” series, since the S1 is

designed to work mainly the coronal and middle

portion and the S2 the middle portion of the canal;

conclude that, different studies such as that of Tan38

and that of Roland41, the apical portion, by nature, is

normally larger in size than a 20 ﬁle; It is also

documented by Tan et al.38 that with prior preﬂaring,

the apical gauge increases by 2 or 3 sizes to the

initial apical gauge.

The number of uses of each instrument was

controlled, discarding these every 5 uses (5

instrumented teeth or 10 canals), because as

determined by Berutti et. al.17 in their study, an

average of 9.9 canals could be instrumented without

the ProTaper® system instruments suffering

permanent deformation or fracture, and they also

commented that the ProTaper® S series instruments

(shaping ﬁles) could be used more times than the F

series instruments (ﬁnishing ﬁles), since, according to

this study, the life expectancy of the F1 is 60% less

than that of S1, and that of F2 80% less than S1.

After use, the instrument was inspected under a

microscope at 25x magniﬁcation42.

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Máx. Curvatura Promedio Curvatura

Tomando en cuanta la vista clínica

(V-L) y la vista proximal (M-D)

Distribución de grupos por grado de curvatura

Glide Path K10

Glide Path K15

Glide Path K20

Graph 1 Analysis of the distribution of the groups with

respect to the angle of curvature

Finding that there are no statistically signiﬁcant

differences between the different sample groups

(maximum curvature and average curvature).

Graph 2 Analysis of the distribution of the groups with

respect to the radius of curvature

There are also no statistically signiﬁcant differences

between the different sample groups in terms of

radius.

The previous graphs show us that the distribution of

the groups was homogeneous in terms of the angle

and radius of curvature, so it had no impact on the

deformation or fracture of the rotary mechanical

instruments.

Graph 3 Instrument separation frequency

Finding that there are no statistically signiﬁcant

differences between Group A (glide path K10) and

Group B (glide path K15) with a p-value = 0.723255.

Among Group B (glide path K15) and Group C (glide

path K20), there are differences but not statistically

signiﬁcant with a p-value = 0.0765221.

While among group A (glide path K10) and group C

(glide path K20) there are statistically signiﬁcant

differences p-value = 0.0374679.

In this statistical analysis we can observe how a

trend is marked, and it shows us that by increasing

the caliber of manual instrumentation prior to rotary

mechanical instrumentation (glide path), statistically

signiﬁcant differences are obtained as the caliber of

the preparation increases, resulting in a reduction in

the possibility of fracture of the mechanical

instruments.

Relationship between fractured or despirated

instruments and the angle and radius of curvature:

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Means and 95.0 Percent LSD Intervals

Grupos

grados

1 2 3

Means and 95.0 Percent LSD Intervals

Grupos

grados

1 2 3

p-value = 0.4514

p-value = 0.7997

Means and 95.0 Percent LSD Intervals

Grupos

mm. x 10

1 2 3

Means and 95.0 Percent LSD Intervals

Grupos

mm. x 10

1 2 3

0.5

1.5

2.5

3.5

Mín. Radio Promedio Radio

Tomando en cuenta la vista clínica

(V-L) y la vista proximal (M-D)

Distribución de grupos por radio

Glide Path K10

Glide Path K15

Glide Path K20

p-valor = 0.5780

p-valor = 0.4178

Glide Path

K10

Glide Path

K15

Glide Path

K20

Grupos

Frecuencia de Separación o Desespiramiento de los

Instrumentos

Instrumento Separado o

Desespirado

Power Curve

alpha = 0.05, mean proportion = 0.275

True Difference Between Proportions

Power

-0.6-0.4-0.2 0 0.2 0.4 0.6

0.2

0.4

0.6

0.8

Power Curve

alpha = 0.05, mean proportion = 0.15

True Difference Between Proportions

Power

-0.46-0.26-0.060.140.340.54

0.2

0.4

0.6

0.8

Power Curve

alpha = 0.05, mean proportion = 0.175

True Difference Between Proportions

Power

-0.49-0.29-0.090.110.310.51

0.2

0.4

0.6

0.8

p-valor = 0.72325

p-valor = 0.07652

p-valor = 0.03746

Diente No. Conducto Máx. Curvatura Mín. Radio Cuantificación Instrumento Sepa. o Desesp.**

20A MV 45 18 1 (S2 D1)

8B ML 14 27 1 (S1 D8)

19A MV 32 36 1 (S2 D3)

2A MV 16 40 1 (S2 D5)

6A MV D D 1 (S1 R6)

9A MV D D 1 (S1 D4)

14B ML 17 23 1 (S1 R3)

10B ML 32 29 1 (S2 D1)

12B ML 28 90 1 (S1 R2)

19B ML 32 36 1 (S1 R1)

21A MV D D 1 (S2 D3)

18B ML 36 31 1 (S2 D9)

Relación entre Instrumentos F o D y el

radio de curvatura

100

1 2 3 4 5 6 7 8 9 10 11 12

Instrumentos Fracturados o Desespirados

milímetros

Mín. Radio

Relación entre Instrumentos F o D y el

ángulo de curvatura

1 3 5 7 9 11

Instrumentos Fracturados

o Desespirados

Grados

Máx. Curvatura

Graphs 4 and 5 Distribution of the angles and radii of

curvature of the teeth where instruments were separated

When analyzing them, it was found that there are no

statistically signiﬁcant differences between the

different groups.

From what we can determine that the despirated or

fractured instruments were not due to a radius or

degree of curvature, the sample was homogeneous.

Relationship between fractured or despirated

instruments and the number of uses:

Graph 6 Relationship between fractured instruments and

the number of uses thereof.

There are no statistically signiﬁcant differences

between the different groups.

It is important to note that 8 of the 12 instruments

that were separated did so during the ﬁrst and

second use of the ﬁle, which shows that the

separation of instruments was not linked to the

number of uses, thus validating what was found by

Berutti et. al.17 in terms of the number of uses of

ProTaper® instruments.

It is important to mention that when a glide path is

made to a K20 ﬁle, rotary ﬁles reach working length

more quickly, we found statistically signiﬁcant

differences in this data, although this analysis was

not the main objective of the study, it was an

interesting ﬁnding, which demonstrates how this

glide path caliber makes the work of the ﬁrst rotary

ﬁles easier.

Finally, it is important to remember that the data

obtained in this study were achieved through

mechanical instrumentation by an inexperienced

operator; these data could vary for endodontists with

experience and better tactile sensation regarding the

use of rotary instruments.

CONCLUSIONS

-Manual glide path caliber inﬂuences the frequency

of fracture or permanent deformation of the

mechanical rotary instruments of the ProTaper®

system, when this is performed by inexperienced

operators.

-The glide path performed with a K10 ﬁle does not

inﬂuence the frequency of fracture or permanent

deformation of the ProTaper® system instruments,

when it is performed by inexperienced operators.

-The glide path performed with a K15 ﬁle does not

inﬂuence the frequency of fracture or permanent

deformation of the ProTaper® system instruments,

when it is performed by inexperienced operators.

-The glide path performed with a K20 ﬁle

inﬂuences reducing the frequency of fracture or

permanent deformation of the mechanical rotary

instruments of the ProTaper® system, when this is

performed by inexperienced operators.

-Manual glide path caliber to a K20 ﬁle, inﬂuences

decreasing the time in which the ﬁrst mechanical

rotary instrument of the ProTaper® system

reaches the working length.

ISSN: 2957-8655

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Means and 95.0 Percent LSD Intervals

Col_1

Col_2

14161718192021232425262728303132343638404546475060

-0.6

-0.2

0.2

0.6

1.4

1.8

Means and 95.0 Percent LSD Intervals

Col_1

Col_2

101214151618192223 2427 282930313536374047 507590

-0.6

-0.2

0.2

0.6

1.4

1.8

p-valor = 0.1986

p-valor = 0.5506

Grupo 1 uso 2 uso 3 uso 4 uso 5 uso Total

Glide Path K10 12 2 10 6

Glide Path K15 32 0 00 5

Glide Path K20 00 0 01 1

Total 44 2 11 12

0.5

1.5

2.5

3.5

Cantidad

Primero Segundo Tercero Cuarto Quinto

No. de Usos

Relación entre Instrumentos F o D y el

número de usos

Instrumentos Fracturados o

Desespirados

1 2 3

Means and 95.0 Percent LSD Intervals

Col_11

-0.6

-0.1

0.4

0.9

1.4

1.9

2.4

Col_10

p-valor = 0.6025

FUTURE PERSPECTIVES

Study the inﬂuence of glide path caliber in the

frequency of fracture or permanent deformation of

mechanical rotary instrumentation in general.

Furthermore, the inﬂuence of coronal widening

(preﬂaring) on mechanical rotary instrumentation

must be determined.

The inﬂuence of the glide path on the vertical and

torque forces exerted during mechanical rotary

instrumentation (for example through endograms)

must be assessed, as well as on the cyclic fatigue of

mechanical rotary instruments.

Finally, it must be determined whether the glide path

caliber inﬂuences the frequency of fracture or

permanent deformation of mechanical rotary

instrumentation, when said instrumentation is

performed by expert operators (endodontists).

ACKNOWLEDGMENTS

To the Faculty of Dentistry of the University of San

Carlos of Guatemala and the International University

of Catalonia for their training and support in carrying

out this research.

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FUNDING INFORMATION

This research was completely funded by the authors

within the participating universities and did not have

any participation from any commercial house or

outside entity or person.

CONFLICT OF INTEREST DECLARATION

The authors declare that there is no conﬂict of

interest related to this study.

DATA AVAILABILITY DECLARATION

Data available on request.

AUTHOR CONTRIBUTIONS

CAB performed experiments, analyzed data and

wrote the manuscript, FDT, MRC analyzed data and

revised the manuscript. CAC reviewed, validated the

manuscript and contributed to the concept.

How to cite this article:

AMA: Alvarado-Barrios C, Durán-Sindreu F, Roig M.

Inﬂuencia del calibre del glide path en la fractura de

instrumentos rotatorios. Revista Cientíﬁca Guatemalteca

de Odontología. 2022;1(1):1-14. doi:10.56818/

odontologia.v1i1.8

APA: Alvarado-Barrios, C., Durán-Sindreu, F., Roig, M.

(2022). Inﬂuencia del calibre del glide path en la fractura

de instrumentos rotatorios. Revista Cientíﬁca

Guatemalteca de Odontología, 1(1), 1-14. https://doi.org/

10.56818/odontologia.v1i1.8

ISSN: 2957-8655

https://doi.org/10.56818/odontologia.v1i1.8

About the authors

Carlos Guillermo Alvarado Barrios

Postgraduate Director of Dentistry (USAC), publications in

indexed journals, editor of the SEP Scientiﬁc Journal

(USAC), former president of FOCAP and the Dental

Society of Guatemala, national and international speaker,

main line of research: Endodontics.

Fernando Salvador Durán-Sindreu Terol

Director of the Master of Endodontics (UIC), more than 50

publications in indexed journals, international speaker,

main research line: Endodontics.

Miguel Roig Cayón

Director of the Master of Restorative Dentistry (UIC),

former president of ESE, former president of SEPES,

more than 100 publications in indexed journals,

international speaker, main line of research: Restorative

and Endodontics.

Carlos Guillermo Alvarado Cerezo

Secretary general of the CSUCA, president of the CC-

SICA, former rector of the University of San Carlos of

Guatemala, former secretary general of the USAC, former

dean of the USAC Faculty of Dentistry, former president of

the Dental Society of Guatemala, national and

international speaker.

Fernando Salvador Durán-Sindreu Terol, Miguel Roig

Cayón y Carlos Guillermo Alvarado Cerezo.

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ISSN: 2957-8655

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