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1. Restorative Dentistry!
A clinical and cost-benefit evaluation of five facebows
Nachum Samet, DMDVAmi Smidt, DMD, MSc^/Naama Samet, DMD^/Ervin Izhak Weiss, DMD"
Objective: Aithough the use of an arbitrary facebow and a full-sized artictjlator can reduce laboratory er-
rors, many dentists do not use a taoebow routinely because the procedure seems to be both irlrioate and
time consuming.The purpose of the present study was lo evaluate tour earpiece-type facebows and the
Snow facebow and to compare Ihe time required lor registration, the ease of manipulation, and cost-bene-
fit oonsiderations. Method and materials: Twenty-five dentists who routinely used only the Snow facebow
were asked, after a brief explanation, to perform registrations with the Snow facebow and four new-gener-
ation, earpiece-type facebows. The time required for each iacebow registration was recorded. Dentists
were also asked to fill out a questionnaire concerning ease of manipulation and cost-benefit factors.
Results: The Quiok facebow was the facebow of choice of most of the dentists because of its favorable
design and usage characteristics and cost-benefit ratio. The Artex 3-D facebow proved to be both the easi-
est and the fastest to manipulate. The Spring-bow and the Whip-Mix Quickmouni were next in rank, and
the Snow facebow scored the lowest. Conclusion: The use of earpiece-type facebows is both simple and
fast, and practitioners judged this type of facebow to be superior to the Snow facebow (Quintessence Int
2002:33:511-515)
Key words: centering mechanism, clinioal evaluation, earpiece, facebow, fork mechanism
CLINICAL RELEVANCE: The ease ano speed of face-
bow registration, coupled with the knowledge that greater
precision can be obtained with a full-sized articulator,
should persuade dentists to regularly employ this impor-
tant tool.
Precise occlusai restorations, both fixed and remov-
able, require accurate occlusal records and a set of
working casts, which shouid be mounted on a full-sized
articulator, at least a semiadjustable one.^-* There is no
'Instructor, Deparlment ot Prosthodontrcs, Hadassah-Hebrew Unrveisity,
Faculty ot Dental Medicine, Jerusalem, Israel.
Clinical Lecturer, Department of Prosttiodontics. tHadassati-Hebrew
University, Facutty ot Dental Medicine, Jeiusalerr, Israel.
'InsUuctor, Department ot Oral Surgery, Tel-Aviv university, Maurice and
Gabriela Goldsctileger School of Dental Medicine. Tel-Aviv, Israel.
'Associate Professor and Head, Department of Prosthodoniics. Hadas-
sah-Hebrew University, Faculty ot Dental Medicine, Jerusalem, Israel,
ReprinI requests: Dr N, Samel, Department of Prosttiodontics. Hadas-
sah-Hebrew University, Faoully ot Dental Medicine, PO Boi
Jerusalem 91130, Israel. E-mail: nsamel@yahoo.com
perfect device that can duplicate the mandibular move-
ments of a particular patient. The aim is to minimize
the occlusal errors produced in the laboratory without
adding any comphcated and time-consuming proce-
dures. An arbitrary facebow is a tool for achieving this
goal as well as a means for allowing correct mounting
of the casts in both the horizontal and the sagittal
planes. Correct motinting of the casts is of crucial im-
portance to esthetic diagnosis and treatment.
The occlusa) paths are basically three-dimensional
movements that take place within a known space.
These paths are lhnJted by the two condyles. the bony
structures of the eminence, the ligaments, and tbe
contacts of the teeth. Simplification of this complex
movement can be achieved if the condyles are viewed
as the two centers of rotation, and the cusps as the
"pencil points" of the calipers. The aim of the face-
bow is to transfer the geometric distances (radii) and
the correlation between the patient's condyles and the
occlusal plane to an articulator.'-' Theoretically, the
use of these geometric distances should allow the
dental laboratory to reproduce the patient's occtusal
paths when the occlusal surfaces of the restorations
are fabricated.'"^
Quintesse 511

2. • Samet et al
Fig 1 Upper view of the ¡ive tacebows: (A) Snow; (B) Ariex 3-0;
(C) Spring-tjow; (D) Quick; (E¡ Whip-Mix Qjickmount.
Fig 2 CloseDp ot the rigtit earpieces ot each facebow. (A) Snow,
(B] Artex 3-D; (C) Spring-bow; (D) Quick; (E) Whip-Mix
Quickmount.
Fig 3 Closeup of the fork mechanism of each facebow. (A)
Snow; (B] Artex 3-D, (C) Spring-bcw; (D) Quick, (E¡ Whip-Mix
Quickmount.
Because the condyles cannot be viewed directly, ex-
ternal markers are used for this purpose. This, of
course, does not allow a perfect reproduction of the
occlusal paths but is far more accurate than an arbi-
trary mounting of the casts on the articulator.'
There are two basic types of facebows: the kinematic
and tbe arbitrary.^ While the first demands precise deter-
mination of the actual hinge axis, the second makes use
of average determinants for the position of the hinge
axis,'-^ Although the kinematic facebow is more accu-
rate, the far less complicated arbitrary facebow is consid-
ered stifficiently accurate for routine laboratorj' work.^'*
Snow's arbitrary facebow, introduced in 1899, is
still in use today. However, the need for better and less
intricate devices lias led to the development of a new
generation of facebows,'-" which also serve to en-
hance esthetic analysis and restorative treatment.'^
Tbe main innovations are (1) the use of the external
auditory mcatus to represent the hinge axis and the
condyles, (2) the developtnent of self-centered bows,
and (5) tbe development of superior and more reliable
fork devices.
Tbe purpose of tbe present study was to evaluate
clinically four earpiece facebows and compare them
witb tbe Snow facebow. The evaluation assessed tbe
time involved in performing the required registration
and the ease of manipulation. The cost-benefit of tbe
facebows was also considered.
METHOD AND MATERIALS
The study group comprised 25 dentists wbo routinely
used tbe Snow facebow only. None of tbese dentists
bad previous experience witb earpiece-type facebows.
After a brief explanation and demonstrafion, the den-
tists were asked to perform facebow registrations witb
five different facebows: Snow facebow (model 132-2SM,
Tcledyne Water Pik), Quick (Sintec), Whip-Mix
Quickmount (Whip-Mix), Artex 3-D (Girrbacb Dental),
and the Hanau Spring-bow (Teledyne Water Pik).
Tbe Snow facebow was the only nonearpiece-iype
facebow, while the other four were earpiece-type face-
bows. The earpiece-type facebows differed in tbe de-
sign of their self-centering mecbanism (Fig 1), earpiece
(Fig 2), fork mechanism (Fig 3), and attacbment de-
vice to the corresponding articulators. Tbe main char-
acteristics of each facebow are summarized in Table 1.
All facebow registrations were performed on one
volunteer in a single session. Each dentist was asked
512

3. • Samet et ai
TABLE 1
Facebow
Snow
Artex 3-D
Spring-bow
Quick
Whip-Mix
Quickmount
Mean characteristics of five facebows
Type
Nonearpiece
Earpiece and
nonearpiece
Earpiece
Earpiece
Earpiece
Centering
mechanism
None
Simple slide
mechanism
Eiastic bow
Three-point
Slide mechanism
Three-point
slide mechanism
Fork
mechanism
One knob, nonrigid
One knob.
flexible chain
Three smali i<nobs:
two perpendicular
rods
Two large knobs;
two perpendicuiar
rods
Two screws: two
perpendicular rods
Earpiece
design
No earpiece
Round or
pointed
Round
Round
(changeable)
Angied
Third point of
reference
Infraortiital
Infraorbital or
nasion
Infraorbital or
nasion
Infraorbitai or
nasion
Infraortjital or
nasion
to manipulate each facebow five times. The actual reg-
istrafion time did not include the preparation of the
wax bites on the forks. All the registration times were
measured by a single person and were recorded in
minutes, at intervals of 5 seconds.
At the end of the session, the dentists were asked to
fill out a quesfionnaire regarding the ease of manipulat-
ing the bow and fork devices and the facility of adapting
the earpieces. They were also asked to provide an overall
assessment of each facebow, with emphasis on the possi-
bility of their using it in the futitre. Participants were also
given a table ranking the price of each facehow. All para-
meters were scored as follows: 5 = excellent; 4 = good; 3
^reasonable; 2 = inferior; and 1 = unacceptable.
RESULTS
The four earpiece-type facebows were superior to the
classic Snow facebow on the basis of the time involved
in registrafion and tbe ease of use. Tbe mean time re-
quired for facebow registration performed by 25 inex-
perienced dentists ranged fiom 1.75 to 3.25 minutes for
these four facebows (Fig 4). The results of tbe ques-
tionnaires are summarized in Table 2. The Artex 3-D
facebow scored the highest in all but one of the cate-
gories. The only marked disadvantage was its high
price. The Quick facehow scored the highest among
the facebows ufilizing a fork mecbanism based on per-
pendicular rods. The operators' comments emphasized
(he conveniently large knobs, the large, replaceable
earpieces, and the smooth slide mechanism. The
Spring-bow was ranked lower than tbe Quick facebow,
and some users commented negatively on its excessive
flexibility. The Whip-Mix Quickmount facebow ranked
fourth, and 22 of 25 operators commented on its
unique earpiece design, which was found to be
nonanatomic and disturbing to the patient. The Snow
facebow ranked the lowest in all categories.
The same two comments appeared in 23 of 25
questionnaires:
1. More than one person is needed to achieve correct
registration with the Snow facebow.
2. When an earpiece-type facebow Is used, the patient
must confirm equal pressure on both ears to ensure
centralization of the bow.
The cost-benefit evaluation is summarized in Table
3. The Quick facebow was the first or second choice of
88% (22) of the denfists. The Spring-bow was selected
as a first or second choice by 84% of the dentists,
mainly because of its flexible nature. The Artex 3-D
facebow was tbe first or second cboice of 52''/Ö, despite
its relatively high price, because of its other character-
istics. The Whip Mix Quickmount facebow was the
first or second choice of 26% of the dentists, and none
of the operators considered buying the Snow facebow.
DISCUSSION
This evaluation showed that the four earpiece-type fece-
bows were significantly superior to the Snow facebow,
both in the time involved in registrafion and in the ease
of manipulation. The mean registration time using an
earpiece-type facebow ranged from 1 minute 45 seconds
to 3 minutes 15 seconds. In view of the fact that the users
were inexperienced, it may be assitmed that the clinical
durafion of this procedure would be substanfially shorter.
Qjinte 513

4. • Samet et al
TABLE 2
Facebow
Artex 3-D
Quick
Spring-bow
Whip-Mix
Quickmount
Snow
' Scores: t ^ u
Scores* for ease of manipulation of lestcd facebows
Centering
mechanism
Mean
4.36
4.52
4.44
4.48
1.00
nacceptable: 2
Range
4-5
4-5
3-5
4-5
1
interior, 3 = reaso
Fork
mechanism
Mean
4.76
4.48
3.38
2.7
1.00
nable, A ^
Range
4-5
4-5
3-5
2-3
1
good: E = encellen!.
Ear
adapt
Mean
4.88
3,38
4.8
2.72
1.00
tion
Range
4-5
3-5
3-5
2-3
1
Overa 1
assessment
Mean
4.48
4.41
3.59
3.20
1.00
^ange
4 - 5
3-5
3-5
2-A
1
Mean score
4.80
4.20
4.01
3.54
1.00
TABLE 3 Cost-benefil factors of tested facebows
Facebow
Quick
Spring-bow
Artex 3-D
Whip-Mix
Quickmount
Snow
Price
$225
$200
$375
$194
$204
"Scores: 1 = unacceptable: 2 ~
excellent.
'Percentage ot de
choice.
Cost-benefit assessment
Mean score'
(dentists)i
4.40 (88%!
4.21 (84%)
2.60 (52%)
1.32(26%)
0.00 (0%)
interior: 3 = reasonable
Range
4-5
4-5
1-5
1-2
0
4 = good;5 =
ntrsts ranking the (aceöow as tiieir first or second
Workingtime(min)
9 -
7-
6-
5 -
4 -
3-
1 -
T
7.50
B
0 ' "-^ '
Snow Whip-Mix
Quickmount
3.00
Spring-bow Quick
1.75
Artex 3-D
Fig 4 Working times required tor the live (acebow registrations. The bars represent mean working times
and standard deviations for five consecutive registrations of each tacebow by 25 operators.
514

5. Samet et al
From a clinical point of view, the Artex 3-D face-
bow headed the list. It was found to be both the easi-
est to operate and the quickest. The overall assessment
was very high because of its round, large earpiece ele-
ments and its unique flexible fork device, although
some users commented on the device's tendency to ro-
tate even after firm adjustment of the knob. To elimi-
nate the possibility of damaging the registration, the
fork device must be mounted immediately on a spe-
cially designed table that can be transferred safely to
the dental laboratory. This, of course, demands more
time.
The Quick facebow ranked second. Many of the re-
spondents preferred this facebow because of the sta-
bility obtained after the device's large knobs were se-
cured and its convenient and innovative attachment to
the articulator. Its main disadvantages were the
slightly more complicated fork mechanism.
The Spring-bow and the Whip-Mix Quickmount
facebows ranked next. The Hanau Spring-bow's ex-
cessiveflexibilityled most of the dentists to comment
that this could compromise the accuracy of registra-
tion, and its small knobs were difficitlt to maniptiJate.
The Quickmonnt facebow was considered the least
convenient because of its unique earpiece elements
that do not aUow set placement in the external audi-
tory meatus and because of the need for a screwdriver
to secure the screws of the fork device. An advantage
of the Whip-MLx system is its ability to assess inter-
condylar distance and to transfer it to the correspond-
ing articulator.
The Snow facebow, the only nonearpiece-type face-
bow tested, was found to be the most cumbersome to
operate, even for experienced dentists. Two people
were required to perform accurate registrations. The
average registration time of 7 minutes 30 seconds, was
two to fotir times longer than that required for the ear-
piece-type facebows.
In the cost-benefit analysis, the Quick facebow was
accorded the highest score. Its moderate price in com-
parison with the price of the Artex 3-D system com-
pensated for the need for up to 1 minute more in reg-
istration time.
This seems to be the first pubhshed clinical evalua-
tion of the ease of manipulation and time involved in
performing a facebow registration. The study also re-
vealed that inexperienced dentists can perform a face-
bow registration within 3 minutes or less, without any
additional help. The use of a kinematic facebow and a
fully adjustable articulator would undoubtedly pro-
duce better results, but these systems are much more
expensive and far more time consuming. They are,
therefore, used almost exclusively for teaching pur-
poses and by researchers, and are only rarely used by
dentists in clinical practice.
QUIntoooonro Inlomatif'nqi , ^ ^ ^ ^ ^ ^
CONCLUSION
The present study revealed that the use of earpiece-
type facebows is both simple and fast. Most of the
dentists involved in this study {23 of 25) who tried
these earpiece-type facebows were impressed by the
ease of manipulation and by the short time required
for registration. Although the Artex 3-D facebow was
the easiest to operate and the quickest, the Quick
facebow was the facebow of choice of most of the
dentists because of its design characteristics, fairly fast
and simple manipulation, and relatively low price.
The ease of facebow registration, coupled with the
knowledge that greater precision can be obtained with
a semiadjustable articulator, should persuade more
dentists to regulariy employ this important tool. This
also applies to undergraduate students, who should be
encotiraged to adopt this important device and to use it
routinely when performing prosthetic treatment, to the
benefit of the patient, the technician, and themselves.
ACKNOWLEDGMENTS
We [hank Prof Jacob Ehrlich and Prof Noah Stem from the Hadas-
sah-Hebrew Universily. Facult)' of Dental Medicine, for their guid-
ance and assistance.
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