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DENTAL TECHNOLOGY, JULY-SEPTEMBER 2023
cosmetic section 25

division between macro-aesthetics, micro-aesthetics and nano-aes- (Medeiros, 2013; 2018), as well as the Chu rule (German et al,
thetics guides the analysis of the anatomical components that cre- 2016), allows us to work with real dental measurements, different
ates dental and facial harmony. from the digital smile design, the ‘golden ratio’ (Lobbezoo et al,
The ‘golden ratio’ is an aesthetic reference that has been used for 2013; Snow, 1999; Soares, 2006) and the Levin grid (Lombardi,
more than 2,000 years (Preston, 1993) and was introduced to the 1973), which works with apparent measurements.
dental industry by Lombardi (1973). The Levin grid was created to True dimensions lead us to greater precision in planning – this is
simplify its use (Levin, 1978) and for a long time was the largest the great advantage when performing diagnosis and planning with
standard reference for rehabilitation. accurate measurements (German et al, 2016; Medeiros, 2013;
There is, however, some controversy as to whether this is actual- 2018).
ly in the dental ratio (Preston, 1993; Soares, 2006). Perhaps this Together with the ‘wish smile’, the patient can already see their
inconsistency is the reason for the increasing search for aesthetic treatment suggested on the first session, also optimizing the
treatments for smile transformation (Coachman and Calamita, patient’s and the professional’s time, which is a real challenge in
2012; Frese et al, 2012; Fradeani and Corrado, 2006; Medeiros, dental treatments.
2013; 2018). The 4D protocol extends far beyond smile aesthetics, but also
Digital smile design (Coachman and Calamita, 2012) is used for seeks to restore facial aesthetics and stomatognathic system bal-
smile planning. With the correct photographs, digital planning pres- ance. Its goal is to create a simple and accurate step-by-step guide
ents simple steps for assessing the size, shape and position of teeth, for the first query.
as well as gingival contour.
However, with some limitations,
planning is performed through a
frontal view, not using actual

widths for the lateral and canine
incisors, as in the ‘golden ratio’
(Levin, 1978; Lombardi, 1973;

1

,

Mondelli, 2003; Preston, 1993). , 1 7 ( 5 1 $ , 7 2 $ / 1 ' , $ % % ' ' H H D D O O D D Q Q Q Q L L F F O O D D W W Q Q U3 J J 3 U U 7 7 U H H I I R R V V H H G G D D R R L L V V Q Q G G D Q Q D

Sterret (2003) evaluated dental
measurements in three groups:
canines, lateral incisors and maxil-
lary central incisors; gender, eth-
nicity and height were recorded for
all participants. The Caucasian

group prevailed, while the largest F F g F F g G H F N F G
measurements were in males.

X

These measures help plan the peri- X
odontal recontour.
Magne et al (2003) performed
mesio/distal and cervical/incisal
measurements on images of 146
maxillary anterior extracted teeth.
Measurements were evaluated on
erupted and non-erupted teeth in
Caucasian individuals. Yamaguto
and Vasconcelos (2005) measured
the distal width from molar to
molar by the upper and lower teeth
in 60 models of orthodontic acces-
sories. As measures presented in
the Brazilian sample, the results in
Sterret (2003) and Magne et al
(2003) were close.
After reviewing the literature,
and during the creation of the ‘rule
of 20’, it was observed that dental
measurements begin to coincide
with harmonic smiles, as observed
in Magne et al (2003), Sterrett
(2003), and Yamaguto and
Vasconcelos (2005).
According to the Chu method,
teeth with appropriate harmonic
proportions have a width/height
ratio of 75% to 80%. This simple
calculation makes quick planning
possible based on previous dental
measurements.
The ‘rule of 20’ and the Chu
method are ways of planning teeth
based on real measurements, and
both find similar values (German et

&
1
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0

1
(

5
5

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4

al, 2016). The ‘rule of 20’ 5 1 1 + 6 # + % 0 0 6 & 7 ; 4 6 5 0& & # & ' 0 # +