Artificial tooth selection: Could digital photographs be helpful?

1
Artificial tooth selection Could digital
photographs be helpful?

• Stipetic J, Celebic A, Nola P, Petricevic N,
  Knezovic-Zlataric D, Baucic I, Baucic-Bozic M.
• Department of Prosthodontics, School of Dental
  Medicine, University of Zagreb, Croatia

INTRODUCTION Adequate choice of dimensions
of artificial teeth is difficult without
pre-extraction records. Many various methods and
anatomical landmarks have been used to aid in the
selection and placement of artificial teeth for
complete dentures (1-8), but none of them seem to
be fully accurate. The patient's old photographs
have also been recommended (9,10). Wehner et al.
(9) and Bindra et al (10) described a method of
calculating dimensions of maxillary central
incisor by measurements made on pre-extraction
photograph and on the patient by substituting in
the following equation calculated central
incisors width actual interpupillary distance
x photographic width of central incisor/
photographic interpupilar distance. However, the
quality of an old photograph has been questioned
for this purpose. Recent development of digital
photography and wide use of personal computers
and their low cost have made these techniques and
equipment available to wide public.
AIM OF THE STUDY to study possibility of
calculating the width of a missing central
incisor using digital photographs.
SUBJECTS AND METHODS Fifty one dentate subjects,
18-48 years (30 females and 21 males)
participated and gave a written consent. Digital
photographs were obtained (digital camera Fuji
Finepix A310 3.1 Megapixel 3x Optical/2.9x
Digital Zoom) on an adjustable tripod (Manfrotto
Tripod Digi MN714SHB) in a portrait mode. The
tripod was adjusted in the height of the
subjects tip of nose. Four photographs were
made from a distance of 35 cm, 70 cm, 1 m and
1.5 m (Figure 1). Images were transferred to a
personal computer in JPEG format. Microsoft
Office Paint program was used to stretch or
reduce an image and to cut and enlarge any part
of an image, so that a full size of a face could
fit to an A4 size paper (29.7 cm x 21 cm) (Figure
2). After that, images were printed in color (A4
laser printer Xerox Phaser 6250N resolution
2400 dpi). The width of the maxillary left
incisor (MLI) and interpupilar distance were
measured on participants prior to photography by
a caliper with a precision of 0.1 mm (MEBA,
Zagreb, Croatia). The interpupilar distance was
measured between the centers of pupils (IPD),
which had been marked on a wooden spatula while
each subject was looking at the object at least
four meters distant from the eyes. Afterwards the
same measurement was repeated on each of the four
images on, printed on a A4 size paper. To
calculate the width of MLI the following equation
was used MLIcalculated photographic width of
MLI x IPD / photographic IPD. Intraobserver and
interobserver variability was assessed for both,
clinical and photographic measurements. Three
different observers measured ten subjects and
their photographs in two different occasions.
There was no significant difference between the
two occasions (t test for dependent samples
pgt0.05) and between three different observers
(one way ANOVA pgt0.05). Maximum difference
between three observers in two time intervals was
0.8 mm for interpupilar distance, 0.2 mm for the
width of MLI, 0.2 for the interpupilar distance
on photographs and 0.1 mm for the width of MLI on
photographs. These values were within acceptable
limits clinically. Finally, one observer
completed all the measurements. Statistical
analysis was made using SPSS 12.0 for Windows
(Chicago, Illinois) (one sample
Kolmogorov-Smirnov test, descriptive statistics t
test for dependent samples).
VARIABLE t p
Measured MLI value calculated MLI value - 35 mm -3.813 lt0.001
Measured MLI value calculated MLI value - 70 mm -1.55 0.127
Measured MLI value calculated MLI value - 1 m 0.299 0.766
Measured MLI value calculated MLI value 1.5 m 0.437 0.664
TABLE 1. T test for dependent samples between
actual maxillary central incisor value (MLI) and
calculated MLI values from images made with a
digital camera from 35 cm distance, 70 cm
distance, 1 m distance and 1.5 m distance t t
value df degree of freedom p p value
Figure 3.
RESULTS The calculated tooth width from 4
different photographs are in Figure 3. The width
of MLI calculated from a 35 cm distance was
bigger than the actual width, which is a tendency
to overestimate the actual width. The dependent t
test between calculated MLI width (35 cm, 70 cm,
1 m and 1.5 m distance) and the actual MLI width
are in the Table 1. The difference was
significant from a 35 cm distance (plt0.05), while
there was no significant differences from a 70
cm, 1 m and 1.5 m distance (pgt0.05). Paired
intercorrelations (r) were MLI MLI 35
cm0.605 MLI MLI 70 cm 0.914 MLI MLI 1 m
0.657 MLI MLI 1.5 m 0.608 (p lt0.05), the
highest (0.914) between the actual MLI width and
the MLI width calculated from a 70 cm distance.
Percentage of calculated MLI values that fell
within 0.3 mm 0.5 mm and 1 mm range of the
actual MLI values are shown in the Table 2.
DISCUSSION Bindra et al.(10) described a
technique of calculating the width of a central
incisor from a pre-extraction photograph.
However, he stated that it is of value only when
the photograph is a full-face portrait of
sufficient size with visible frontal teeth, which
is not often available. Nowdays digital
photography has been available for wide public
and the study was made with the idea that general
practitioners can store digital images of each
patient in a PC together with other personal data
and status. The aim was to check the accuracy of
calculating central maxillary incisors width
from various camera-object distances. The camera
used in this study was not a professional one and
no knowledge of how to obtain professional
photographs was needed. The program Paint is a
part of Microsoft Office package, available to
wide public. Our results showed that images from
a distance of 35 cm were inaccurate (probably
distorted manufacturers manual the focus range
was 2.0 ft to infinity, Macro 0.3ft. - 2.6ft).
The highest correlation with actual MLI width was
0.914 from a 70 cm distance.
DISTANCE within 0.3 mm within 0.5 mm within 1 mm
35 cm 33.3 45.1 82.4
70 cm 66.7 86.3 100
1 m 37.3 64.7 88.2
1.5 m 17.6 41.2 76.5
TABLE 2. Percentage of calculated MLI values
that fit within 0.3 mm 0.5 mm and 1 mm
range from the actual MLI values
However, the distance of 1 m was also acceptable.
The length of a central incisor was not
calculated in this study, for the reason that
longer maxillary incisors ars necessary in
dentures to compensate for bone resorption.
Clinical relevance of the results also showed
that the distance of 70 cm revealed the best
results (Table 2) . However, better digital
cameras, with better optical and digital
characteristics would give even better results.
CONCLUSION Obtaining digital photographs is of
proven value in calculating the width of a
maxillary central incisor. The photographs using
a simple, not expensive and non-professional
digital camera (3.2 Mpix) should be taken from a
distance 70 cm to 1 m.
LITERATURE
1. Sellen PN, Jagger DC, Harrison A.
Computer-generated study of the correlation
between tooth, face, arch forms, and palatal
contour. J Prosthet Dent 199880163-8. 2. Sellen
PN, Jagger DC, Harrison A. The selection of
anterior teeth appropriate for the age and sex of
the individual. How variable are dental staff in
their choice? J Oral Rehabil. 200229853-7. 3.
Seluk LW, Brodbelt RH, Walker GF. A biometric
comparison of face shape with denture tooth form.
J Oral Rehabil. 198714139-45. 4. Bell RA. The
geometric theory of selection of artificial
teeth is it valid? J Am Dent Assoc.
197897637-40. 5. Mavroskoufis F, Ritchie GM.
The face-form as a guide for the selection of
maxillary central incisors. J Prosthet Dent.
198043501-5. 6. Ibrahimagic L, Jerolimov V,
Celebic A, Carek V, Baucic I, Zlataric DK.
Relationship between the face and the tooth form.
Coll Antropol. 2001 25619-26. 7. LaVere AM,
Marcroft KR, Smith RC, Sarka RJ. Denture tooth
selection an analysis of the natural maxillary
central incisor compared to the length and width
of the face Part II. J Prosthet Dent.
199267810-12 8. Sellen PN, Jagger DC, Harrison
A. Methods used to select artificial anterior
teeth for the edentulous patient a historical
overview. Int J Prosthodont. 19991251-8. 9.
Wehner PJ, Hickey JC, Boucher CO. Selection of
artificial teeth. J Prosthet Dent.
196718222-32. 10. Bindra B, Basker RM, Besford
JN. A study of the use of photographs for denture
tooth selection. Int J Prosthodont.
200114173-7.