Basic Research—Technology
Ultrasonic Chemical Vapor Deposition– coated Tip versus
High- and Low-speed Carbide Burs for Apicoectomy: Time
Required for Resection and Scanning Electron Microscopy
Analysis of the Root-end Surfaces
Ricardo Affonso Bernardes, DDS, MS, PhD,* José Villela de Souza Junior, DDS,*
Marco Antonio Húngaro Duarte, DDS, MS, PhD,† Ivaldo Gomes de Moraes, DDS, MS, PhD,‡
and Clovis Monteiro Bramante, DDS, MS, PhD‡
Abstract
This study compared ultrasonic chemical vapor deposition
(CVD)-coated tip (CVDentus #8.1117-1; Clorovale Diamantes
Ind. e Com. Ltda Epp, São José dos Campos, SP, Brazil) versus
high-speed (#FG700L) and low-speed (#699) carbide burs for
apicoectomy, evaluating the time required for resection and
analyzing the root-end surfaces by scanning electron microscopy. Thirty extracted human premolars had the canals instrumented and obturated and were randomly assigned to 3
groups (n ⫽ 10), according to the instrument used for rootend resection. The time required for resection of the apical 2
mm of each root was recorded. The resected apical segments
were dried, sputter coated with gold, and examined with a
scanning electron microscope at ⫻350 magnification. A fourpoint (0–3) scoring system was used to evaluate the apical
surface smoothness. The results were analyzed statistically by
the Kruskal-Wallis test, and two-by-two comparisons analyses were performed using the Miller test. The significance
level was set at 5%. Root-end resection with the high-speed
bur was significantly faster (p ⬍ 0.05) compared with the
low-speed bur and CVD tip. The carbide burs produced significantly smoother root-end surfaces than the CVD tip (p ⬍
0.05). The low-speed bur produced the smoothest root-end
surfaces, whereas the roughest and most irregular root ends
(p ⬍ 0.05) were obtained with the CVD tip. However, no
statistically significant difference (p ⬎ 0.05) was found between the high- and low-speed burs regarding the surface
roughness of the resected root ends (p ⬎ 0.05). In conclusion,
under the tested conditions, ultrasonic root-end resection
took a longer time and resulted in rougher surfaces compared
with the use of carbide burs at both high and low speed. (J
Endod 2009;35:265–268)
Key Words
Apicoectomy, endodontic surgery, ultrasound
D
entistry has experienced a great technological evolution in all fields in the last
decades. In endodontics, in particular, this evolution has been reflected in root
canal therapy with the development of new diagnostic methods, biomechanical preparation, and obturation. However, the biological factors involved in the endodontic
therapy should not be overlooked, and failure may occur despite the technological
advance.
Endodontic surgery is indicated to eliminate or arrest an infection originated in the
root canal system that cannot be eradicated by a conventional orthograde route (1). The
most frequent surgical modalities include curettage with scaling and root planning,
apicoectomy, endodontic surgery with simultaneous root canal obturation, and retrograde filling is one of the most common procedures in these cases.
Apicoectomy associated or not with root-end cavity preparation and retrograde
filling is a surgical procedure that consists in mucoperiosteal flap elevation followed by
osteotomy to gain access to the periapical region. The elimination of pathological
periapical tissues and other irritating agents is essential for the clinical and radiographic success. The choice for the apicoectomy technique is a critical step in endodontic surgery. Gutman and Harrison (1) recommend that the root resection method
be highly refined in order to favor controlled removal of the radicular apex and to
produce smooth and clean surfaces, thus preventing excavations or a sulcus effect.
Numerous techniques and instruments have been evaluated and recommended in
the literature in an attempt to find the ideal approach in endodontic surgery (2– 4).
Neddermann et al. (2) comparing different burs at high and low speeds found that
low-speed plain fissure burs #57 produced smoother and more regular root-end surfaces when compared with those produced by crosscut fissure burs in both high and low
speeds. Morgan and Marshall (3) analyzed the surface topography of roots resected
with #57 Lindemann and multipurpose burs, with or without refinement with multifluted carbide and ultrafine diamond finishing burs. These authors observed that the
multipurpose bur produced smoother and more regular surfaces and less debris.
In addition, the multifluted carbide bur finishing produced smoother surfaces than
the ultrafine diamond bur. Weston et al. (5) evaluated eight different instrument
configurations by scanning electron microscopy (SEM) and two different directions in which the bur moved across the root surface in relation to its direction of
rotation. Each instrument was found to produce a fine root surface irrespective of
the design of the instrument used. Smearing and shredding of the gutta-percha was
From the *Department of Endodontics CPO SL Mandic, Brasiliense Dental School, Brasília, DF, Brazil; †Department of Dentistry, Sagrado Coração University, Bauru,
SP, Brazil; and ‡Department of Operative Dentistry, Dental Materials and Endodontics, Dental School of Bauru, University of São Paulo, Bauru, SP, Brazil.
Address reprint requests to Dr Ricardo Affonso Bernardes, SEPS 705/905 Centro Emp, MONT BLANC, Salas 425/427, CEP 70390-055 Brasília-DF, Brazil. E-mail
address: [email protected].
0099-2399/$0 - see front matter
Copyright © 2008 American Association of Endodontists.
doi:10.1016/j.joen.2008.11.009
JOE — Volume 35, Number 2, February 2009
Evaluation of Root-end Resection Methods
265
Basic Research—Technology
observed only when the handpiece was moved across the root surface in the reverse direction in relation to the direction of rotation of
the bur.
Laser has also been used for surgical endodontic procedures including apicoectomy and preparation of retrograde cavities, with some
advantages over burs such as disinfection of the surgical site, absence of
vibration, increased patient comfort, and anti-inflammatory and biostimulating effects. However, root-end resection with laser has been
shown to take longer and produce rougher surfaces compared with
burs (4).
Ultrasound has been more frequently used for root-end cavity
preparation (6 –9) with carbide or diamond burs. A Brazilian company
(Clorovale Diamantes Ind. e Com. Ltda Epp, São José dos Campos, SP,
Brazil) has recently developed chemical vapor deposition (CVD)coated diamond tips adaptable to conventional ultrasound devices,
marketed under the brand name CVDentus System (10). These tips are
manufactured by the deposition of continuous diamond coatings
onto molybdenum shafts in an excess hydrogen environment. After
some physicochemical interactions, a pure diamond film is covalently formed on metal surface and strongly adhered to the shaft
without metallic binder between the crystals (10). Bernardes et al.
(11) compared the time, occurrence of fractures, and the quality of
apical cavity preparation using CVD, Trinity (São Paulo, SP, Brazil),
and Satelec (Paris, France) ultrasonic diamond tips and found that
the CVD tips presented better quality and shorter preparation times.
However, the literature is scarce in studies evaluating the use of
ultrasound-activated instruments for apicoectomy, and the feasibility of ultrasonic root-end resection in endodontic surgery should be
investigated. Therefore, this study compared ultrasonic CVD-coated
tip versus high- and low-speed carbide burs for apicoectomy, evaluating the time required for resection and analyzing the root-end
surfaces by SEM.
Material and Methods
Thirty freshly extracted single-rooted premolars were selected,
radiographed to confirm the presence of a single root canal and stored
in 10% formalin solution for a maximum time of 3 months until use in
the study. Access to the pulp chamber was obtained, and the root canal
was instrumented by the modified Oregon technique as defined by Berbert et al. (12). This technique consists in a crown-down pressureless
biomechanical instrumentation of the main canal until the desired
working length is reached for cleaning purposes followed by a stepback preparation to increase the canal diameter. A serial enlargement
of the root canal is performed up to a size 40 K-file at the working length
established at 1 mm short of the apical foramen followed by progressive
step-back with size 45 to 80 K-files and cervical and middle third flaring
with sizes 2 and 3 Gates drills, respectively (Maillefer, Ballaigues, Switzerland).
The canals were irrigated with 1% NaOCl at each change of file.
When the instrumentation was completed, the canals were filled with 1
mL 17% EDTA during 5 minutes, received a final flush with 1% NaOCl,
and were dried with sterile absorbent paper points. The canals were
obturated with gutta-percha and an epoxy-based root canal sealer
(Sealer 26; Dentsply Ind. e Com Ltda, Petrópolis, Rio de Janeiro, RJ,
Brazil) using a hybrid technique as described by Tagger (13), whereby
cold lateral condensation of the apical third of the canal was associated
with thermomechanical compaction of the filling material at the coronal
and middle thirds with McSpadden compactors (Maillefer). The coronal openings were sealed with glass ionomer cement, and the root-filled
teeth were stored in saline at 37°C during 72 hours, which is a longer
period than the setting time recommended by the sealer’s manufacturer.
After this period, the apical 2 mm of each root were resected at a
90° angle with the root long axis (4, 11, 14) using the following instruments under copious sterile saline irrigation: group 1 (n ⫽ 10): a plain
tapered fissure #170L (multipurpose) tungsten carbide bur (KG Sorensen, São Paulo, SP Brazil) at high speed (350,000 rpm); group 2
(n ⫽ 10): a crosscut tapered flat end #699 tungsten carbide bur (KG
Sorensen) at low speed (15,000 rpm); group 3 (n ⫽ 10): CVD-coated
diamond tip (#8.1117-1, CVDentus) (Fig. 1) coupled to the handpiece
of a conventional ultrasound device set at medium power intensity (Jetsonic Four; Gnatus, Ribeirão Preto, SP, Brazil) using a special connector. The total time required for apicoectomy, from the beginning to the
end of the resection, was recorded for each root.
The resected apical segments were left drying at room temperature
and then mounted on metallic stubs sputter-coated with gold (Hammer
VI Sputtering System; Anatech Ltd, Alexandria, VA) and examined with a
scanning electron microscope (JSMT220A; Jeol, Tokyo, Japan). SEM
micrographs were taken at ⫻350 magnification for analysis of surface
roughness by two calibrated examiners in a double-blinded fashion
using a 4-point (0 –3) scoring system as described by Duarte et al. (4):
0 ⫽ smooth surface, 1 ⫽ surface with slight roughness, 2 ⫽ surface
with moderated roughness, and 3 ⫽ surface with severe roughness
(Fig. 2). The interexaminer agreement was assessed by the Kendall test.
The results obtained for each group were analyzed by the nonparametric Kruskal-Wallis test for overall comparison of the groups and by
Figure 1. Ultrasonic CVD-coated diamond tip. (A) Detail of the angulated CVD tip used in this study for apicoectomy. (B) SEM micrograph of this CVD tip showing a
thick layer of pure diamond that is covalently formed and strongly adhered to the metallic shaft forming a single stone that covers the entire surface of the active part
of the tip.
266
Bernardes et al.
JOE — Volume 35, Number 2, February 2009
Basic Research—Technology
Figure 2. Panel showing the scores used for the analysis of surface roughness. Score 0 ⫽ smooth surface, score 1 ⫽ surface with slight roughness, score 2 ⫽ surface
with moderated roughness, and score 3 ⫽ surface with severe roughness (⫻350 magnification).
Miller’s test for pair-wise individual comparisons. The significance level
was set at 5%.
Results
The total time (in seconds) required for apicoectomy in each
root and the average of each group are presented in Table 1. The
analysis of the cutting times by the Kruskal-Wallis test revealed statistically significant differences among the groups (p ⬍ 0.05). Rootend resection with the high-speed bur was significantly faster (p ⬍
0.05) compared with the low-speed bur and CVD tip. The time
required for apicoectomy with the low-speed bur was significantly
shorter (p ⬍ 0.05) than that needed for the CVD tip.
Table 2 presents the scores attributed by the two examiners to each
specimen according to the apical surface smoothness. The Kendall test
showed a high interexaminer agreement. The analysis of the scores
obtained for surface roughness by the Kruskal-Wallis test revealed significant differences among the groups (p ⬍ 0.05). The carbide burs
produced significantly smoother root-end surfaces than the CVD tip
(p ⬍ 0.05). However, no statistically significant difference (p ⬎ 0.05)
TABLE 1. The Total Time (seconds) Required for Apicoectomy in Each Root
and Each Group
Specimen
High-speed Bur
Low-speed Bur
CVD Tip
1
2
3
4
5
6
7
8
9
10
Mean
SD
6.76
10.14
10.34
10.5
6.75
6.47
9.56
9.72
9.35
9.87
8.946
1.616
3.3
12.8
11.34
40.13
16.24
11.21
28.26
16.73
8.55
37.26
19.582
12.428
26.21
20.02
24.37
27.09
25.87
35.01
40.84
51.23
34.16
22.19
30.699
9.648
JOE — Volume 35, Number 2, February 2009
was found between the high- and low-speed burs regarding the surface
roughness of the resected root ends (p ⬎ 0.05).
Discussion
Ultrasound has been used in the preparation of root-end cavities
for retrograde filling because it offers a safer and regular preparation
without causing alterations in root apex topography (11, 14 –17).
The company CVD has recently launched ultrasonic tips to the
Brazilian market for root-end preparation and enamel/dentin cavity
preparation, which present special manufacturing characteristics.
These tips have been proven effective for apical cavity preparation (11).
However, there are no reports on the use on ultrasonic tips for root-end
resection, which makes it difficult to compare the findings of the present
study with the literature.
One of the concerns in apicoectomy is the manner in which rootend resection is performed. Care should be taken regarding both the
cutting angle formed between the instrument and the root and the
smoothness of the resected apical surface. Several authors (2, 3, 14,
15) have shown that the type of instrument and the cutting angle have a
direct influence on apical surface roughness and dentinal tubule exposure observed after root-end resection. In this study, the ultrasoundactivated CVD-coated tips produced rough root-end surfaces probably
because the longer time required for ultrasonic root-end resection
makes it difficult to maintain a uniform and continuous cutting.
The carbide burs produced smoother and more regular root-end
surfaces, and the crosscut tapered flat end #699 carbide at a low speed
had a better performance than the plain tapered fissure #170L carbide
bur at a high speed. These results are consistent with those of a previous
study by Duarte et al. (4) in which root resection with high-speed #699
bur and high-speed #699 bur followed by Shofu point finishing produced more regular and smoother surfaces than the Zekrya bur, which
is a plain fissure bur. However, our findings do not agree with those of
Nedderman et al. (2) and Morgan and Marshall (3) who had better
results with a plain fissure bur or a multipurpose bur, respectively.
Evaluation of Root-end Resection Methods
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Basic Research—Technology
TABLE 2. Scores Attributed to Each Specimen According to the Apical Surface Smoothness
Specimen
1
2
3
4
5
6
7
8
9
10
High Speed Bur
Low Speed Bur
CVD Tip
Examiner 1
Examiner 2
Examiner 1
Examiner 2
Examiner 1
Examiner 2
1
3
1
1
1
3
1
2
3
0
1
1
0
2
1
3
1
1
2
1
1
2
1
1
1
1
0
0
0
0
1
0
1
0
0
1
1
0
0
0
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Score 0 ⫽ smooth surface, score 1 ⫽ surface with slight roughness, score 2 ⫽ surface with moderated roughness, and score 3 ⫽ surface with severe roughness.
The high-speed bur performed root-end resection within the
shortest times, although it did not produce the smoothest and most
regular apical surfaces. Even not considering that the 90° cutting angle
(4, 11, 14) facilitates the use of the ultrasonic tip in the analysis of the
cutting time, ultrasonic root-end resection took the longest time to be
performed, which discourages its indication as the main choice for
apicoectomy. However, it should be mentioned that the CVD tips have
been shown to have a greater cutting efficiency than conventional ultrasonic diamond tips and presented the shortest root-end cavity preparation time compared with other brands of ultrasound-activated diamond
tips in a recent study (11).
In conclusion, under the tested conditions, ultrasonic root-end
resection took a longer time and resulted in rougher surfaces compared
with the use of carbide burs at both high and low speeds. Further studies
are necessary, especially in vivo investigations, to determine the influence of root-end resection technique on the apical healing after endodontic surgery.
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