Taschieri Root End Tip Design

8/3/2019 Taschieri Root End Tip Design

1/8

Effects of ultrasonic root end preparation on resected root surfaces:

SEM evaluation

Silvio Taschieri, MD, DDS,a Tiziano Testori, MD, DDS,b Luca Francetti, MD, DDS,c and Massimo Del

Fabbro, PhD, BsC,

d

Milan, ItalyUNIVERSITY OF MILAN

Objective. The purpose of this study was to investigate the in vitro effect of ultrasonic retrotips on root end surfaces.Study design. Root end resection was performed on 45 single-root teeth endodontically treated after extraction. Settingthe ultrasonic device at full power, a retrograde cavity was made by a stainless steel tip in 9 specimens (SS-FP). In another9 samples a diamond tip was used (D-FP). Setting the intensity of the ultrasonic device at half power, 9 specimens weretreated using stainless steel tips (SS-HP) and 9 using diamond tip (D-HP). Nine teeth were only apically resected and usedas controls. Histologic serial sections were examined by scanning electron microsope to assess the number of root-facecracking, the marginal quality, and the crack type.Results. No significant difference between diamond and stainless steel groups was found at a given power setting.Significant differences were found between SS-FPand SS-HP group for both the number of cracks and the marginal quality.(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;98:611-8)

The aim of root end preparation techniques during

endodontic surgery is to create a well-shaped cavity to be

filled, in order to seal the apical terminus of the root canal

system.1

The ultrasonic retrotip has demonstrated many ad-

vantages over the traditional hand-piece used in surgical

endodontics.2 They enable the long axis of the tooth to be

followed, while preserving the morphology of the canal.3

Apical cavities may be shaped easily, safely, and with

greater precision if compared to those obtained using

conventional hand-pieces.1,4-6 In addition, the cutting bevelobtained on the resectedroot end can be quite perpendicular

to the canal long axis. This might be beneficial, because it

decreases the number of exposed dentinal tubules at the

resected root surface, minimising apical leakage.7-9

A better shaped root end cavity, which is more

centrally placed and smaller than that produced by mi-

crohandpieces and burs, may also reduce the risk of root

perforation in deeply fluted roots.10

Several studies concerning ultrasonic retrotips have

also documented improved cleaning of cavity walls

when compared to conventional instruments, and a de-

creased volume of the smear layer following root canal

preparation.5,11-12

Only a limited number of clinical studies have been

published on periradicular surgery using microsurgical

retrotips.13-17 All these studies reported high success

rates for periradicular healing with follow-up periods

ranging from 6 to 14 months.

Despite the excellent results obtained by usingultrasonic tips, Saunders et al demonstrated that this tech-

nique was not free from contraindications.18 Subsequent

studies demonstrated the occurrence of cracks on the

surface of resected root ends after retrograde preparation

with ultrasonic tips.19-33

All these in vitro studies showed limitations. It is

difficult to transfer the results obtained from extracted

teeth to the clinical situation. The periodontal ligament

may act as a dampening and absorbing factor preventingthe propagation of cracks caused by vibratory root end

preparation with sonic or ultrasonic units.34

Layton et al reported that high-frequency ultrasonicroot end preparation using a stainless steel tip produced

significantly more cracks per root than low-frequency

preparation.22

Frank et al examined the effect of an ultrasonic device

at medium and high power settings using stainless steel

tips.21 The authors found the highest number of in-

fractions when using an ultrasonic device with a high

power setting. In addition, biconcave roots were more

susceptible to infractions than oblong or round root ends

were. However, no statistically significant difference

aHead, Section of Endodontics, Department of Odontology, Galeazzi

Institute, University of Milano, Milan, Italy.bVisiting Professor, Head of Section of Implant Dentistry and Oral

Rehabilitation, Department of Odontology, Galeazzi Institute, Uni-

versity of Milano.cResearcher, Head of Section of Periodontology, Department of

Odontology, Galeazzi Institute, University of Milano.dResearcher, Head of Section of Oral Physiology, Department of

Odontology, Galeazzi Institute, University of Milano.

Received for publication Oct 6, 2003; returned for revision Mar 8,

2004; accepted for publication Apr 12, 2004.

1079-2104/$ - see front matter

2004 Elsevier Inc. All rights reserved.

doi:10.1016/j.tripleo.2004.04.004

611


2/8

was found for the occurrence of infractions as related to

root tip morphology.

Waplington et al reportedan increase in chipping of root

endpreparations related to theuse of an ultrasonic stainless

steel tip.35 Chipping was observed more frequently when

power intensity was increased. However the authors found

no evidence of cracks on the root end surface using theentire spectrum of possible power settings.

Min et al examined serial histological sections of root

ends prepared at the lowest power setting of an ultrasonic

device and at an intensity level midway between the

lowest and highest power settings, using stainless steel

tips.24 No differences were found in the crack length or

depth between the 2 groups.

Lin et al didnt observe cracks on any resected surface

of roots after root end cavities preparation using a

stainless steel tip with an ultrasonic device at the lowest

power setting.27

Gray et al showed that varying power settings of an

ultrasonic device between its lowest and highest in-

tensity did not significantly alter the occurrence of cracks

and chipping using stainless steel retrotips.29

Peters et al, in a scanning electron microscope (SEM),

study compared ultrasonic diamond-coated and stainless

steel retrotips using an ultrasonic device at a medium

power setting.30 The authors showed no significant

difference between the 2 groups. The time required to

prepare the root end cavities was also evaluated.

Navarre and Steiman didnt find root end fractures

produced by either stainless steel or zirconium nitridee

coated retrotips using an ultrasonic device at full

power.31 The time that the ultrasonic tips were in contactwith tooth structure was recorded.

Ishikawa et al evaluated and compared the efficiency

of root end preparations using ultrasonic retrotips coated

with diamond and zirconium nitride and a stainless steel

tip, setting an ultrasonic device only at maximum

power.32 No significant differences in the number of

microcracks were found. The time required to prepare

the root end cavity was recorded.

The purpose of the present study was to investigate

the effect of ultrasonic retrotips on root end surfaces and

on retrograde cavities. We aimed at comparing samples

that were prepared using 2 different retrotip designs (adiamond-coated tip and a stainless steel tip) and 2

different power levels of the ultrasonic device. We alsoevaluated the influence of the different tip designs on the

time required to prepare the cavities.

We tested the null hypothesis of equivalence in the

outcomes between the different techniques.

MATERIAL AND METHODSForty-five human teeth with single straight roots and

single canals were used in this study. All the teeth were

vital and extracted for orthodontic and/or periodontal

reasons, from subjects aged between 18 and 45 years.

Only specimens without restorations, with intact roots

and mature apexes free of defects and visible fractures

were selected. Following extraction, soft tissue and

debris were removed from the surfaces of the roots by

hand scaling. The teeth were then thoroughly cleanedand placed in 5% sodium hypochlorite solution for 30

minutes. They were washed twice in PBS (Sigma

Chemicals, St. Louis, Mo) for 2 minutes and immedi-

ately stored in 5% buffered formalin36 (Sigma

Chemicals) for 24 hours.

The pulp chambers were accessed and the working

length of the root canal determined by observing a size

10 K-file at the foramen and withdrawing it for 0.5 mm.

All teeth had a proximal radiograph taken with the file in

situ to ensure straightness of the canal and to exclude

canals with an unusual anatomy. Root canals were then

cleaned and shaped using a crown-down technique. The

prepared working width was #30 for all the specimens.

All canals were then filled by vertical compaction of

gutta-percha points.All 45 roots were resected at a 908 angle in respect to

their longitudinal axis, 3 mm from the apex. To ensure

that the section was made exactly as planned, a wax base

with the section line already drawn was used. Each

section was made using a tungsten-carbide straight

fissure bur (Maillefer Zerkya; Dentsply-Maillefer Instru-

ments, Ballaigues, Switzerland) used under constant

water spray irrigation. All the teeth were held with

saline-soaked gauzes to maintain root moisture while all

procedures were accomplished.31

The 45 teeth were then assigned to one of 5 groups

(each consisting of 9 specimens) according to a 1:1

computer-generated randomized table (Really Random

Numbers; 2003 Sunny Beach Technology, Minneapolis,

Minn). One group was used as a control (control group).

The other 4 groups were treated as follows. Setting the

ultrasonic device power at the maximum position (full

power, FP) a retrograde cavity was made with a stain-

less steel ultrasonic retrotip (DS-017; EMS, Nyon,

Switzerland) in 9 specimens (SS-FP group) and with

a diamond-coated retrotip (EMS) in another 9 samples

(D-FP group). In the other 2 experimental groups theintensity of the ultrasonic device was set at half power

(HP). Nine specimens were treated with a stainless tip(SS-HP group) and the other 9 with a diamond-coated tip

(D-HP group).

All the 4 test groups had apical cavities prepared as

follows. A 3-mm-deep root end preparation was made.

Water spray irrigation was used to avoid overheating.

The time required to prepare the root end cavities with

both retrotips was recorded. The retropreparations were

made using new tips for each specimen, to avoid a

OOOOE

612 Taschieri et al November 2004


3/8

different cutting ability. A single operator, with over

10 years of experience in endodontic surgery, carried out

all the preparations. Then a 3 mm section was cut

perpendicular to the long axis, in a horizontal plane, with

a precision saw (Isomet Low Speed Saw; Buehler, Lake

Bluff, Ill). This was done also in the teeth belonging to

the control group (that were not apically instrumented)that were assessed to test if the bur cut on the bevel

surface might itself produce root cracking.

The sectioned samples were washed 3 times for 10

seconds with 17% EDTA solution buffered at pH 7.5

(Ogna, Milan, Italy) to remove the smear layer.

Each sample was then briefly examined under

stereomicroscope with fiber optic transilluminating light

source, at 243-723 magnification, for a preliminary

analysis regarding the presence and type of dentin

fractures. Each sample was photographed under different

angulation, for our records. We did not use the results of

optical observation for the statistical analysis. Specimens

were then prepared for SEM analysis according to the

method proposed by Janda37 for SEM investigation of

human teeth. This method was designed to minimize theoccurrence of artifacts related to the sample processing

for SEM analysis. Briefly, specimens were first de-

hydrated in a water/ethanol mixture with increasing

content of ethanol (70%, 80%, 96%, and 100% for 24

hours each), followed by mixtures of ethanol and acetone

(increasing acetone content: 80%, 96%, and 100% for 24

hours each). Then they were dried for 24 hours in

a dessiccator under vacuum with a glass filter pump. In

this way critical-point drying may be avoided.

Finally, the specimens were mounted on a single stub,and sputter coated with gold (SEM coating unit E 5100;

Polaron Equipment, Whatford, UK). The SEM evalua-

tion was performed with a Jeol 840A (Jeol, Tokyo,

Japan). Specimens were coded for blind evaluation. Each

specimen was photographed at magnification of 483

and independently scored by 2 blind examiners. Any

disagreement between the 2 observers was resolved

jointly by re-evaluating the sample under greater mag-

nification (up to 15503) until a consensus was reached.

The examiners assessed:

The number and type of root surface cracking

produced by the ultrasonic retrotip.

The marginal integrity of the apical cavities.

The number and the location of the cracks were scored

for each tooth. Each item was scored in accordance with

the cracks number in the following scale: A, absence of

cracks; B, 1 to 3 cracks; C, 4 to 6 cracks; D, 7 or more

cracks. The type of cracks was then classified as:

complete, incomplete, and intradentinal, similar to

Beling et al.23 Complete canal cracks extended from

the canal space to the external root surface. Incomplete

canal cracks extended from the canal space to a variable

distance into the dentin but ended short of the external

root surface. Intradentinal cracks were confined to dentin

and appeared to run in a facial-lingual direction either

mesial or distal to the canal.

The quality of root end cavity margins produced by

ultrasonic retrotips was scored according to the degree ofdefects:

The ideal preparation (0 defects).

A single, visible defect produced by the contact

between the angle of the tip and the cavity margin.

Chipped, ragged cavity margin.

Chipped, ragged cavity margin plus some defects due

to the tips bouncing off the root face during root end

preparation.

Statistical analysis was carried out to evaluate the

difference between groups using a software package

(Statistica; Statsoft, Tulsa, Okla). Fisher exact test and

Pearsons chi-squared were used to compare the effects

of treatment between the experimental groups. Com-

parisons were made by means of 2 by 2, 2 by 3, or 2 by4 crosstables, as appropriate. ANOVA and unpaired

Students t-test were used to compare preparation times

between groups. A value of probability P = .05 was

considered as the significance level.

RESULTSTable I summarizes the results of the evaluation of the

different parameters.

Root face cracks numberNo cracks were observed in root bevel surfaces

belonging to the control group.

In the SS-FP group there was 1 specimen classified C

and one D, whereas in the other groups all the samples

were classified no worse than B.

No statistically significant differences could be found

between diamond-coated and stainless steel retrotips, for

both power settings, regarding the cracking number.

Within roots treated using stainless steel retrotips we

found that the FP group showed a significantly higher

number of cracks when compared to the HP group (P =

.02). We also found a significant difference betweenthe D-FP and SS-HP groups (P = .03). No correlation

was found between preparation times and the incidence

of cracks (P[ .05).

Types of cracksFigure 1 is an SEM microphotograph showing an

example of an incomplete dentinal crack of a sample

belonging to the SS-FP group. The distribution of the

types of cracks among groups is shown in Table I. Only

the SS-HP group had no samples with complete or

OOOOE

Volume 98, Number 5 Taschieri et al 613


4/8

incomplete canal cracks. Two complete cracks were

observed in the D-HP (one of them is showed in Fig 2), 1

in the SS-FP, and 3 in the D-FP group. All groups had

specimens showing intradentinal cracks. Figure 2, A is

a picture taken under stereomicroscope prior to SEM

analysis, showing a branching pattern of cracks very

similar to that observed under SEM (Fig 2, B).Figure 3 represents a sample belonging to the D-FP

group, showing several dentinal cracks. No significant

difference between groups was outlined for crack type

(P[ .05). No correlation between preparation times and

type of cracks was observed (P[ .05).

Marginal quality of retrograde cavityTable I also reports the scores for marginal chipping

produced using retrotips. Figure 2 illustrates an example

of preparation without marginal defects. Teeth treated by

stainless steel retrotip at high frequency level scored 1sample with chipped margin and another with chipped

margin and defects. The latter is shown in Fig 4. When

using diamond retrotip at high power setting no sample

with chipped margins was observed. No significant

difference was found between diamond-coated and stain-

less steel retrotips for this parameter, at both power

settings. It was observed that the3 samples that presented

chipped margins required almost 4 minutes for the

retrograde cavity preparation, while the preparation was

accomplished in shorter times for most of the other

samples. No statistically significant difference was found

for margin quality between diamond coated and stainlesssteel retrotips. Within the groups using stainless steel

retrotips, the samples treated by the full-power setting

displayed a poorer quality of cavity margin when

compared to half-power-treated teeth (P = .02).

Time required to prepare root end cavityTable II reports the mean time required for cavity

preparation for the 4 experimental groups. We found

that, on the average, diamond-coated retrotips allowed

faster retrograde preparation than stainless steel retrotips,

at both half and full power setting (P\ .05 in each case).

DISCUSSIONRecently, ultrasonic root end preparation tech-

niques for endodontic surgery have gained popularity

in endodontics practice. In contrast to bur-prepared root

end cavities, those shaped using ultrasonic retrotips are

deeper, rarely deviate from the canal space, and require

smaller bony crypts and smaller bevel angles for

preparation.35

However, any approach that could prevent or

minimize adverse effects of the root end preparation

Table I. Results of the evaluation of the quantity and quality of cracks

Full power (FP) Half power (HP)

Group: Control D-FP SS-FP D-HP SS-HP Total

No of cracks per sample

0 9 2 2 5 7 25

1-3 0 7 5 4 2 18

4-6 0 0 1 0 0 1$7 0 0 1 0 0 1

Type of crack

Intra-dentinal 4 4 2 2 12

Incomplete 0 2 0 0 2

Complete 3 1 2 0 6

Quality of cavity margin

No defects 4 2 5 7 18

1 defect 5 5 3 2 15

Chipped, ragged 0 1 1 0 2

Chipped + defects 0 1 0 0 1

D = diamond coated; SS = stainless steel.

Fig 1. A microphotograph (magnification 483) taken with

SEM, showing an example of an incomplete crack. The sample

belonged to the SS-FP group. The crack starts from the canal

margin, as pointed by one of the 2 arrows, and ends into the

dentin at a distance indicated by the other arrow.

OOOOE



5/8

such as the occurrence of dentinal cracks should be

considered. Recently some attempts to improve the

performance of ultrasonic instruments were carried out.

The introduction of diamond-coated and zirconium-

coated retrotips represents an important issue in this

field.This in vitro study investigated the effect of different

ultrasonic retrotip designs and different ultrasonic device

amplitude levels as related to the number of root end

surface cracks, the type of cracks, and the marginalquality of retrograde cavity.

Number of root face cracksCracks on resected root surface of extracted teeth

occur not only during in vitro procedures of root end

cavity preparation but also because of resulting de-

hydration of the dentin.10 In fact, dehydration of dentin

may alter its mechanical properties so that it becomes

more prone to developing cracks when compared to

hydrated dentin.38 In this study only freshly extracted

teeth were used and attention was paid to keep thesamples moist during the root end preparation, as sug-

gested by other authors.31 Moreover, important factors

peculiar to in vitro studies, such as stresses exerted

during extraction, inappropriate storing, and careless

handling of extracted teeth may predispose to dentin

alterations.39 A further limitation of the in vitro approach

is the absence of periodontal ligament, which could

dissipate some of the stress to which the root is subjected

during instrumentation.34 Therefore, in the present study

we could have obtained an overestimation of cracks.

The preparation of a sample for SEM analysis is one of

the most critical aspects of this method of investigation.

In fact, dehydration and drying procedures may create

artifacts in hard tissues. Prior to gold sputtering of the

sample, 2 different approaches may be identified for

sample preparation. These 2 approaches were compared

in the past by Janda.37 The direct approach consists of

the dehydration and drying of the original sample. Theindirect approach is carried out by taking impressions

of the tooth surfaces with appropriate materials (such as

polysiloxane). A positive model is then manufactured

from the impression using a transparent resin or an epoxy

resin. The replica is then gold sputtered and examined.

Even if the indirect method should avoid creation of

artifacts and preserve the original sample, Janda found

that this approach does not provide detailed information

of the original tooth surface, especially when examining

tooth structures at high magnification ($ 4003) using

Fig 2. A, A specimen observed under stereomicroscope prior to preparation for SEM analysis. The branching pattern of dentinal

crack in this sample is the same as later observed under SEM. B, Sample belonging to the D-HP group, showing a complete canal

crack. The inner and the outer ends of the crack are indicated by the arrows. In the sample are visible several dentinal branches of theprincipal crack.

Fig 3. Intradentinal cracks (arrows) of a sample belonging to

the D-FP group.

OOOOE



6/8

SEM.37 The direct method proposed by this author

involves effective dehydration and drying of the sampleso that critical point drying can be avoided. In this way he

found that the possibility of artifacts is greatly reduced.37

Other authors stated that any kind of dehydration and

drying process causes artifacts, and recommend the

indirect method.39-40 We are aware that the risk for

technique problems leading to artifact cracks may

always exist. In our investigation we followed the

preparation method suggested by Janda that associates

a low risk for artifacts to a high sample definition.

Furthermore, the preliminary observation of the samples

under stereomicroscopy allowed us to identify some

peculiar patterns of dentin fracture. The same patternswere observed when the samples were examined by

SEM as showed in Figs 2 and 4. Finally, in the samples

of the control group we never detected dentin cracks,

suggesting that the main cause for root face cracks in our

case was retrograde preparation.

We found a significant difference between the SS-FP

and SS-HP groups: A higher incidence of cracks was

observed in the group using the full power setting.

Few studies have investigated the effect of ultrasonicretrotips on resected root surfaces after root end prep-

aration with the ultrasonic device set at different power

levels. Some researchers have used only stainless steel

retrotips and showed controversial results.22,24,29,35

Other studies investigated the possible differences

between diamond coating, stainless steel, and zirconium

nitride coating on root end preparation of resected root

surfaces.30-31 These studies adopted only a single power

setting. No significant differences were found between

results obtained with different kind of retrotips. In

the present study, when a given power setting was

considered, no significant difference was observed be-

tween diamond and stainless steel retrotips.

Peters et al found a correlation between the incidence

of cracks and the time needed to accomplish root end

preparation.30 In the present study no correlation was

observed between preparation times and the incidence of

cracks using either medium power or full power settings.

There is little evidence in the literature about this subject,

and it would appear that further investigation is needed to

make clear the influence of the preparation time on the

occurrence of dentinal cracks.

Types of cracksA further aim of this study was to assess if stainless

steel and diamond-coated retrotips produced different

types of cracks. Only the specimens treated with a

stainless steel retrotip at half power did not show

complete or incomplete dentinal fractures. Conversely, 3

complete canal fractures were found when using

diamond tips at the full power setting. However, maybe

Fig 4. A, A specimen observed under stereomicroscope prior to preparation for SEM analysis. The crack pattern and margin defectsare the same as observed with SEM. B, Microphotograph of a sample belonging to the SS-FP group, classified as D for the marginal

quality. In this picture are visible: a defect produced by the contact between the angle of the tip and the cavity margin ( 1), defects due

to the tip bouncing off the root face during root end preparation (2), and chipped, ragged cavity margin (3).

Table II. Time required for retrograde preparation

Group: D-FP SS-FP D-HP SS-HP

Mean time, minutes 1.5 2.2 1.8 2.8

Standard deviation .5 .6 .6 .5

Range (min-max) 1.2-2.6 1.6-3.6 1.4-3.2 2.2-3.3

OOOOE



7/8

owing to the small number of cracks examined, no

significant differences were found between diamond tips

and stainless steel at both power settings.

Few other studies observed the different types of

cracks produced after root end preparation with ultra-

sonic retrotips.

Rainwater et al, using a stainless steel and a diamondretrotip (Amadent, Cherry Hill, NJ) and setting the

ultrasonic device at low power, found no significant

difference between the 2 kinds of tips for both the

number and the type of cracks.28 Most cracks consisted

of intracanal or extracanal types, and a lower number

were of communicating type.

Beling et al, using a stainless-steel retrotip (EIE, San

Diego, Calif) and setting the ultrasonic device at low -

power, found intradentinal and incomplete but not

complete cracks following root end preparation.23

Furthermore, no differences were recorded in the inci-

dence of cracks in canals which were filled or unfilled

prior to root end cavity preparation.

It is difficult to compare results of studies with

dissimilar experimental design. In fact using differenttypes of retrotip design and material could represent an

important source of variability. A further point is the

variation in oscillation of the retrotip according to the tip

design, in particular to angulation and position of bend.35

Differences between ultrasonic devices could change the

vibratory pattern of the tips.41 Finally, different apical

diameter of the specimens used in the various studies

could also lead to increased variability in outcomes.

Until standardization in experimental study design is

obtained, a comparison between heterogeneous reportswill occur and may lead to flawed conclusions.

Marginal quality of the retrograde cavityThe quality of cavity margins produced either using

diamond coated tips or stainless-steel ones was very

similar. In the former case the margin quality didnt seem

to be influenced by the power setting of the ultrasonic

device. Conversely, when using the stainless steel tips

a better cavity margin quality was observed in those

samples treated by half power compared to full power.

Only the latter in fact displayed specimens with chippedmargins.

Gray et al, using stainless steel retrotips, found that

when increasing the powersetting of the ultrasonic unit

chipping is not increased.29 These conclusions, however,

are dissimilar to those of several other studies.21-22,35

The retrotip coating might be as important as power

setting to chipping production.

It has been suggested by Lloyd et al that some defects

observed might be due to the tips bouncing off the root

face during root end preparation.20 They also showed

that the margin quality was significantly worse in roots

sectioned at a 458 bevel.

Very few chipped margins were observed in the

present study. Owing to this fact, no correlation may be

attempted with preparation time. However, we observed

that the time needed to accomplish cavity preparation in

the 3 samples that presented chipped and ragged marginswas higher than the average of the respective groups. It is

possible that the longer the preparation time the higher

the chance of producing chipped margins, but this

subject would need further investigation and a larger

number of observations.

Chipping of the cavity margin may affect sealing of

the root end filling, or favor the harboring of bacteria.

This issue needs to be evaluated in further leakage

studies to clarify the relation of chipping to long-term

sealing at the apex.

Preparation timeWe found that cavity preparation is completed ina faster time when using diamond-coated retrotips ascompared to stainless steel ones. This result is in line

with previous observation by Peters et al30 but does not

correspond to a different incidence of cracks between the

2 types of retrotips.

CONCLUSIONS

1. Root face cracks number: Comparing diamond-

coated and stainless steel tip groups, no significant

differences were found in the number of cracks

produced at both full and half power setting. In the

groups using stainless steel retrotips the FP group

showed a significantly higher number of cracks than

the HP group.2. Type of cracks: No significant difference was found

between diamond-coated tips and stainless steel tips

at both power setting.

3. Marginal quality of retrograde cavity: No significant

differences were found comparing the results of

diamond-coated tip groups versus stainless steel

ones. Samples treated by stainless steel tips dis-

played better margin quality when using half power

instead of full power settings.4. Time required to prepare root end cavities: Di-

amond retrotips were faster than stainless steel ones

to prepare root end cavity, independent of power

setting.

REFERENCES1. Gutmann JL, Pitt Ford TR. Management of the resected root end:

a clinical review. Int Endod J 1993;233:273-83.2. Carr GB. Advances in apical surgery [videotape]. San Diego

(CA): Pacific Endodontic Research Foundation; 1990.

OOOOE



8/8

3. Wuchenich L, Meadows D, Torabinejad M. A comparisonbetween two root-end preparation techniques in human cadavers.J Endod 1994;20:279-82.

4. Gutmann JL, Harrison JW. Posterior endodontic surgery:anatomical considerations and clinical techniques. Int Endod J1985;18:8-34.

5. Gutmann JL, Saunders WP, Nguyen L, Guo IY. Ultrasonicroot-end preparation Part 1. S.E.M. analysis. Int Endod J 1994;27:318-24.

6. Mehlhaff DS, Marshall JG, Baumgartner JC. Comparison ofultrasonic and high-speed-bar root-end preparations using bi-laterally matched teeth. J Endod 1997;23:448-52.

7. Tidmarsh BG, Arrowsmith MG. Dentinal tubules at the root endsof apicected teeth: a scanning electron microscopic study. IntEndod J 1989;21:184-9.

8. Shani J, Friedman S, Stabholz A, Abed JA. Radionuclidic modelfor evaluating sealability of retrograde filling materials. Int J NuclMed Biol 1984;11:46-51.

9. Gilheany P, Figdor D, Tyas MJ. Apical dentin permeability andmicroleakage associated with root-end resection and retrogradefilling. J Endod 1994;20:22-5.

10. Engel TK, Steiman HR. preliminary investigation of ultrasonicroot-end preparation. J Endod 1995;21:443-5.

11. Gormann M, Steimar R, Gartner AH. Scanning electronmicroscopic evaluation of root end preparations. J Endod 1995;

21:113-7.12. Pashley DH. Smear layer: physiological considerations. Oper

Dent Suppl 1984;3:13-29.13. Sumi Y, Hattori H, hayashi K, Ueda M. Ultrasonic root-end

preparation: clinical and radiographic evaluation of results. J OralMaxillofac Surg 1996;54:590-3.

14. Bader G, Lejeune S. Prospective study of two retrogradeendodontic apical preparations with and without the use ofCO2-laser. Endod Dent Traumatol 1998;14:75-8.

15. Rubinstein RA, Kim S. Short-term observation of the results ofendodontic surgery with the use of a surgical operationmicroscope and super-EBA as root-end filling material. J Endod1999;25:43-8.

16. Testori T, Capelli M, Milani S, Weinstein RL. Success and failurein periradicular surgery. A longitudinal retrospective analysis.Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:

493-8.17. von Arx T, Kurt B. Root-end cavity preparation after apicoec-

tomy using a new type of sonic and diamond-surfaced retrotip:a 1-year follow-up study. J Oral Maxillofac Surg 1999;57:656-61.

18. Saunders WP, Saunders EM, Gutmann JL. Ultrasonic root-endpreparation Part 2. Microleakage of EBA root-end fillings. IntEndod J 1994;27:325-9.

19. Abedi HR, van Mierlo BL, Wilder-Smith P, Torabinejad M.Effects of ultrasonic root-end cavity preparation on the root-apex.Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:207-13.

20. Lloyd A, Jaunberzins A, Dummer PMH, Bryant S. Root-endcavity preparation using the MicroMega Sonic Retro-Prep Tip.SEM analysis. Int Endod J 1996;29:295-301.

21. Frank RJ, Antrim DD, Bakland LK. Effect of retrograde cavitypreparations on root apexes. Endod Dent Traumatol 1996;12:

100-3.22. Layton CA, Marshall JG, Morgan LA, Baumgartner JC.Evaluation of cracks associated with ultrasonic root-end prepa-ration. J Endod 1996;22(4):157-60.

23. Beling KL, Marshall JG, Baumgartner JC. Evaluation for cracksassociated with ultrasonic root-end preparation of gutta-perchafilled canals. J Endod 1997;23(5):323-6.

24. Min MM, Brown CE, Legan JJ, Kafrawy AH. In vitro evaluationof effects of ultrasonic root-end preparation on resected rootsurfaces. J Endod 1997;23:624-8.

25. Calzonetti KJ, Iwanowski T, Komorowski R, Friedman S.

Ultrasonic root-end cavity preparation on assessed by an in situ

impression technique. Oral Surg Oral Med Oral Pathol Oral

Radiol Endod 1998;85:210-5.26. Brent P, Morgan L, Marshall J. Evaluation of diamond-coated

ultrasonic instruments for root-end preparation. J Endod 1999;

25(10):672-5.27. Lin CP, Chou HG, Chen RS, Lan WH, Hsieh CC. Root

deformation during root-end preparation. J Endod 1999;25:668-71.

28. Rainwater A, Jeansonne B, Sarkar N. Effects of ultrasonic root

end preparation on microcrack formation and leakage. J Endod

2000;26(1):72-5.29. Gray GJ, Hatton JF, Holtzmann DJ, Jenkins DB, Nielsen CJ.

Quality of root-end preparations using ultrasonic and rotary

instrumentation in cadavers. J Endod 2000;26:281-3.30. Peters CI, Peters OA, Barbakow F. An in vitro study comparing

root-end cavities prepared by diamond-coated and stainless steel

ultrasonic retrotips. Int Endod J 2001;34:142-8.31. Navarre SW, Steiman R. Root-End fracture during retroprepara-

tion: A comparison between zirconium nitrideecoated and stain-

less steel microsurgical ultrasonic instruments. J Endod 2002;

28:330-2.32. Ishikawa H, Kobayashi SC, Suda H. Evaluation of root-end

cavity preparation using ultrasonic retrotips. Int Endod J 2003;36:

586-90.33. Gondim E Jr, Figuereido Almeida de Gomes BP, Ferraz CC,

Texeira FB, de Souza-Filho FJ. Effect of sonic and ultrasonic

retrograde cavity preparation on the integrity of root apices of

freshly extracted human teeth: scanning electron microscopy

analysis. J Endod 2002;28:646-50.34. van Arx T, Walker WA. Microsurgical instruments for root-end

cavity preparation following apicoectomy: a literature review.

Endod Dent Traumatol 2000;16:47-62.35. Waplington M, Lunmley PS, Blunt L. Incidence of root face

alteration after ultrasonic retrograde cavity preparation. Oral Surg

Oral Med Oral Pathol Oral Radiol Endod 1997;83:387-92.36. Jameson MW, Tidmarsh BG, Hood JA. Effect of storage media

on subsequent water loss and regain by human and bovine

dentine and on mechanical properties of human dentine in vitro.Arch Oral Biol 1994;39:759-67.

37. Janda R. Preparation of extracted natural human teeth for SEM

investigations. Biomaterials 1995;16:209-17.38. Kahler B, Swain MV, Mouble A. Fracture-toughening mecha-

nisms responsible for differences in work to fracture of hydrated

and dehydrated dentine. J Biomech 2003;36:229-37.39. Roulet J-F, Michellod P-Y. La dessiccation dobturations en

composite pour letude au microscope electronique a` balayage-

une etude methodologique. Schweiz Monatsschr Zahnmed 1984;

94:1049-60.40. Crang R, Klomparens K. Artifacts in biological electron

microscopy. New York: Plenum Press; 1988.41. Ahmad M, Roy RA, Kamarudin AG, Safar M. The vibratory

pattern of ultrasonic files driven piezoelectrically. Int Endod J

1993;26:120-4.

Reprint requests:

Massimo Del Fabbro

Istituto Ortopedico Galeazzi

Via R. Galeazzi 4

20161 e Milano

Italy

[email protected]

OOOOE

mailto:[email protected]:[email protected]

Documents

Taschieri Root End Tip Design