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

http://www.ajodo.org/http://www.ajodo.org/

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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