bonetti inclinacion de canino permanente superior por edad un estudio radiologico
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8/2/2019 Bonetti Inclinacion de Canino Permanente Superior Por Edad Un Estudio Radiologico
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Percentiles relative to maxillary permanentcanine inclination by age: A radiologic study
Giulio Alessandri Bonetti, Matteo Zanarini, Margherita Danesi, Serena Incerti Parenti, and Maria Rosaria Gatto
Bologna, Italy
Introduction: Few studies have investigated devel-
opmental norms for maxillary permanent canine erup-
tion. In this observational cross-sectional study, we
aimed to provide an age-related description of the per-
centiles relative to canine inclination in a large sample
of nonorthodontic patients. Associations between incli-
nation and sector were also analyzed.Methods: Canine inclination and sector location
were measured on 1020 panoramic radiographs ob-tained from subjects of white ancestry aged between 8
and 11 years not seeking orthodontic treatment. The
total sample comprised 2037 canines.Results: Canine inclination increases between 8 and
9 years and decreases between 9 and 11 years. The
greatest value for each percentile is at 9 years. A linear
model should be hypothesized for differences in canine
inclination between 2 successive ages in correspon-
dence to each percentile. The proportion of sector 2
canines decreases and that of sector 1 increases with
age. In the same age group, the inclination generally
decreases as the sector decreases.Conclusions: Percentiles by age show the average
canine inclination in a certain population. Further stud-
ies are required to verify whether percentiles can be a di-
agnostic aid for determining normal canine inclination
at a given age and for quantifying the risk of canine
impaction or adjacent root resorption.
Read the full text online at: www.ajodo.org,
pages 486.e1-486.e6.
EDITORS SUMMARY
Because I had a palatally impacted maxillary canine
as a child, I was concerned that one of my children might
have a similar problem. I regularly took radiographs of
their developing canines, but I still was not sure whether
they would become impacted until they reached adoles-
cence. Sure enough, 2 of my 3 children developed pal-
atally impacted canines requiring surgical exposureand lengthy orthodontic treatment. Would access tothe information from these authors in Bologna, Italy,
have helped me?
As part of a large cross-sectional study, these
researchers developed an age-related description of
the percentiles relative to canine inclination in white
nonorthodontic patients, ages 8 to 11 years old. Their
thinking was similar to mine in observing children as
they matured. An understanding of the normal path
of canine eruption should therefore be of critical inter-
est to a clinician hoping for early detection of canine
impaction for which preventive measures could be
used. Few studies have tried to determine the normal
pattern of maxillary canine eruption for different age
groups.
To gather the sample, patients referred for pano-
ramic radiographs over several years from a general
pediatric population were included. The study sample
comprised 1020 subjects with a total of 2037 perma-
nent maxillary canines. The results clearly indicate
that the maxillary canines show an initial increase in
mesial inclination between 8 and 9 years of age, fol-
lowed by a decrease between 9 and 11 years, with
the maximum value for each percentile at 9 years of
age. There was considerable individual variability inthis study, as in other similar studies. To explore the
possibilities of using data like these to help diagnose
my childrens eruption problems, I might have had
more success by analyzing the differences in inclina-
tion of the canines between 2 successive ages as they
corresponded to each percentile, thus providing a linear
model for such variations. These data will provide
greater benefit to patients once validated by additional
studies.Am J Orthod Dentofacial Orthop 2009;136:486-7.
0889-5406/$36.00
Copyright 2009 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2009.04.012
486
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Q & A
Editor: Did you gather family histories for these
children, or did you have only the radiographs to
evaluate?
Alessandri Bonetti: We were dealing with patients
in the mixed dentition stage referred to the Depart-
ment of Radiology for a routine panoramic radio-
graph. We started to observe and collect
radiographs based on the absence of the following:
previous orthodontic treatment, trauma, agenesis,
odontomas, cysts or supernumerary teeth in the studyzone, small or peg-shaped maxillary lateral incisors,
craniofacial syndromes, and cleft lip or palate (or
both). We mainly focused on local factors that might
have affected the eruptive positioning of the maxil-
lary permanent canine. Any eventual inherited ten-
dency for ectopic canines was not controlled for.
If proven in future studies, the percentiles described
in our research could be an effective tool for clini-
cians in clinical decisionseg, more frequent
checkups for borderline patients. If aberrant eruptive
positioning of the canine is identified, regardless of
hereditary factors, its correction with preventive
measures should be considered to improve the local
condition for its uneventful eruption. However, sys-
temic factors such as those from family histories
could provide additional information or, otherwise,
additional indications for more frequent check-ups.
Editor: With such a large sample, do you think you
overcame much of the bias in the sample by examin-
ing only those who were referred after getting the
panoramic radiograph?
Alessandri Bonetti: We tried to do that. Because of
the high variability of the data relative to the average
canine inclination reported in the previous study by
Fernandez et al (1998), our purpose was to obtain
a larger sample of subjects to minimize the effects
of such variability, which limits the capacity to pre-
cisely predict canine inclination at a given age.This observational study gave us the only chance to
work on a large scale. Furthermore, low variations
between the interquartile range found in this study
show minor variability in the data.
The results of this study represent a certain popula-
tionwhite patients in northern Italy referred to the
Department of Oral Sciences of the University of
Bologna; they were screened and do not represent
the developmental norm in general. Further valida-tion is required to determine the percentiles clini-
cal effectiveness. However, our results agree with
what Fernandez et al (Eruption of the permanent
upper canine: a radiologic study. Am J Orthod Den-
tofacial Orthop 1998;113:414-20) had previously
reported (maximum mesial inclination is reachedat approximately 9 years of age, and gradual
straightening occurs until emergence is complete).
Furthermore, in our subjects, an inclination $25
to the midline coincides with the interval between
the 90th and 95th percentiles for each age, suggest-
ing high risk for canines at these percentiles. On
the contrary, negative values or near zero values
for canine inclination (between 3.68 and 10.50)
have been found below the 10th percentile for
each age, suggesting low risk for canines at these
percentiles.
At any rate, further clinical studies are required to
identify a percentile cutoff that is clinically signifi-
cant, thereby indicating canines with a high risk of
impaction or possible detrimental effects, and defin-
ing the range of normal variability for each age group
in terms of canine inclination.
Editor: Do you plan a followup study of this sample
to determine how many were actually treated for
palatally impacted maxillary canines?
Alessandri Bonetti: This observational study led us
to set up a new longitudinal study to determine
whether tooth impaction or adjacent incisor root re-
sorption will occur for maxillary permanent canines
defined as high risk and whether canines not at risk or
at low risk will spontaneously and uneventfully
erupt. Such a study can give more evidence-based in-
formation about the clinical effectiveness of the per-centiles elaborated in this research, thereby defining
the range of normal variability for each age group in
terms of canine inclination.
American Journal of Orthodontics and Dentofacial Orthopedics Alessandri Bonetti et al 487Volume 136, Number4