Embed Size (px)
Citation preview
Volume 51 • Issue 5 • 2006 285
placement amplitudes of the other tips differed signifi-
cantly.
Discussion.—Tips of the same design differed signifi-
cantly from one another in terms of vibration displacement
amplitude. This was true for all 3 of the designs tested.
Both loaded and unloaded situations demonstrated the dif-
ferences in the oscillation of scaling tips. Thus, clinicians
who do not replace their inserts for years may be using in-
struments that are reduced in length and in their ability to
perform effectively.
Lea SC, Landini G, Walmsley AD: The effect of wear on ultrasonicscaler tip displacement amplitude. J Clin Periodontol 33:37-41, 2006
Reprints available from SC Lea, School of Dentistry, The Univ ofBirmingham, St Chad’s Queensway, Birmingham s B4 6NN, UK:e-mail: [email protected]
Clinical Significance.—Instruments wearwith use. Although sharpening may restorehand instruments, wear in ultrasonic scalersshortens the functioning tip, reducing thedisplacement amplitude of vibration. Thesechanges adversely affect performance.
fect of tip wear on the displacement amplitude of 3 widely
available designs of scaler tip was investigated with the use
of scanning laser vibrometry.
Methods.—The Cavitron SPS ultrasonic generator and
the FSI-100, FSI-1000, and FSI-SLI-10S scaler tip inserts
were studied. The tips were tested when new under un-
loaded conditions, and then as they contacted tooth sur-
faces with loads of 0.5 and 1.0 N. Tip vibration displace-
ment amplitude was measured under each condition. The
tips were ground down by 1 mm and then by 2 mm, and
more scans were obtained.
Results.—In assessing all tips, both load and length
were significant variables. For unloaded conditions, FSI-100
tips were highly variable in their performance. Tip 3 of this
type had about 50% of the vibration displacement ampli-
tude of the other 4 tips tested. Similar variability was noted
for the other types of tips.
For the FSI-1000 tips, differences in performance were
not significant between tips 1 and 4; 1 and 5; 2 and 3; 2 and
4; or 4 and 5. All the other tips demonstrated significant dif-
ferences.
For the FSI-SLI-10S tips, only tips 1 and 2 and tips 3 and
4 showed no significant differences. All the vibration dis-
Background.—Sealers are an essential part of the seal
itself. When no sealer is used, extensive leakage occurs.
How sealers work has not been clearly delineated. It has
been assumed that they form a continuous barrier and seal
between the components of the material and the canal
wall, but this has not been found to be present in all cases.
Five obturation systems/techniques were evaluated to de-
termine the distribution patterns of sealer relative to the
primary obturant and the canal wall.
Methods.—Five groups of 20 teeth each were formed
of 100 extracted single-rooted teeth. The 5 systems/tech-
niques investigated were vertical condensation, Obtura II,
System B, SimpliFill, and Thermafil Plus. These were com-
pared with lateral condensation, which was done in 5 ad-
ditional teeth. The manufacturers’ recommendations
were followed in choosing instrumentation technique
and sealer. After obturation, the teeth were stored at 37°C
in 100% humidity for 4 months. The teeth were then split
EndodonticsHow do sealers work?
Hugh CL, Walton RE, Facer SR: Evaluation of intracanal sealer distri-bution with 5 different obturation techniques. Quintessence Int36:721-729, 2005
Reprints available from RE Walton, Dept of Endodontics, Univ ofIowa College of Dentistry, 435 Dental Science Bldg S, Iowa City, IA52242-1001; e-mail: [email protected]
Clinical Significance.—The idea that a con-tinuous layer of sealer between the canal walland gutta percha filler accounts for a hermet-ic apical seal was not demonstrated with anyof the techniques studied. What, then, ac-counts for the seal needs further study.
longitudinally in half and assessed by stereomicroscope to
detect how much sealer coverage was present between
gutta-percha and canal wall. Coverage was measured as
slight (0 to 1/3), low partial (1/3 to 2/3), high partial (2/3
to 9/10), or complete (9/10 to 10/10).
Results.—Each group had incomplete sealer distribu-
tion (Table 1). Areas where sealer was often missing in-
cluded the canal wall/dentin interface and the spaces be-
tween cones. The group having the most samples with
complete coverage was SimpliFill, and that with the most
samples having high partial coverage was System B.
Discussion.—Clearly, the use of sealer to achieve an
apical seal is needed. However, evidence indicates that
sealers do not behave as one would assume. Neither total
filling of all the spaces between cones nor formation of a
continuous layer between gutta-percha and canal wall is
needed to achieve an effective seal.
Background.—Rotary nickel-titanium endodontic in-
struments are widely used today. Among their advantages
are greater flexibility than stainless steel hand files, re-
duced incidence of canal transportation, less zipping and
ledge formation, and production of rounded, more cen-
tered preparations in less time than with hand instru-
ments. Metal fatigue does make them more susceptible to
separation. The LightSpeed system for endodontic therapy
of adult patients was studied to assess the incidence of
nonretrievable instrument separation when the instru-
ments were used by third- and fourth-year dental students
in a clinical environment.
286 Dental Abstracts
Rotary instrument separation
Table 1.—Sealer Coverage and Voids Present (%) According to Technique in Coronal and Apical Halves
Vertical Obtura II System B Thermafil SimpliFill Lateral
C A C A C A C A C A C A
Slight 0 0 65 0 0 0 0 0 0 0 0 0Low partial 63 53 35 10 20 16 11 5 0 5 100 100High partial 37 47 0 85 75 74 89 95 40 45 0 0Complete 0 0 0 5 5 10 0 0 60 50 0 0Voids present 42 32 0 5 30 5 0 5 15 5 40 0
Note: Numbers indicate percentage of samples within respective category.Abbreviations: C, Coronal half; A, apical half.(Courtesy of Hugh CL, Walton RE, Facer SR: Evaluation of intracanal sealer distribution with 5 different obturation techniques. Quintessence Int 36:721-729,2005.)
