orthodontic insight
Obesity and orthodontic treatment: is there
any direct relationship?
Alberto Consolaro1
DOI: https://doi.org/10.1590/2177-6709.22.3.021-025.oin
Obesity is a wide-spread condition directly or indirectly connected with an increase in the prevalence of a variety of human diseases. It affects over 50% of the western overall population. In 2017, a thorough analysis of 204 studies on obesity
and cancer revealed that the condition increases the risk of the following types of cancer: stomach, colon, rectal, bile duct,
pancreatic, esophagus, breast, endometrial, ovarian, kidney and multiple myeloma. The first study aiming at establishing a
connection between obesity and the rate of induced orthodontic tooth movement was conducted by Saloom et al; however,
it could not effectively nor significantly reveal any direct influence or effect. Despite being identified during the first week,
differences could not be explained and treatment time remained unchanged. In spite of lack of studies in the literature on
the connection between obesity and the rate of induced tooth movement, in clinical practice, courses or specialized training, we should not have protocols changed nor adopt any measures or expect significant differences between normal-weight
and obese individuals. It should be emphasized that unsuccessful cases or cases of root resorption associated with treatment
should not be assigned to obesity, since scientific data is insufficient to do so.
Keywords: Obesity. Orthodontic movement. Induced tooth movement. Orthodontics.
A obesidade representa uma epidemia que afeta mais de 50% da população ocidental e está, direta ou indiretamente, relacionada com o aumento na prevalência de algumas doenças humanas. Em 2017, em uma análise minuciosa de 204 trabalhos sobre a obesidade e o câncer, observou-se que ela aumenta os riscos de câncer de estômago, cólon, reto, vias biliares, pâncreas,
esôfago, mama, endométrio, ovário, rim e mieloma múltiplo. O primeiro trabalho que procurou relacionar a obesidade
com a velocidade de movimentação dentária ortodôntica foi apresentado por Saloom et al., mas não conseguiu demonstrar,
de forma efetiva e significativa uma influência ou efeito direto. As diferenças ocorreram apenas na primeira semana, e sem
explicação, mas o tempo total do tratamento não foi alterado. Na prática clínica, em aulas ou nos treinamentos de especialistas, não devemos — tendo em vista a ausência na literatura que correlacione a obesidade e a velocidade da movimentação
dentária induzida — mudar protocolos, adotar medidas ou ter expectativas de diferenças significativas entre pessoas com
peso normal e obesas. Ressalta-se, ainda, que casos de insucesso e/ou de reabsorções radiculares associadas ao tratamento
nesses pacientes não devem ser atribuídos à obesidade, pois não há base científica para isso.
Palavras-chave: Obesidade. Movimento ortodôntico. Movimento dentário induzido. Ortodontia.
1
How to cite this article: Consolaro A. Obesity and orthodontic treatment:
is there any direct relationship? Dental Press J Orthod. 2017 May-June;22(3):21-5.
DOI: https://doi.org/10.1590/2177-6709.22.3.021-025.oin
Full professor at the Dental School of Bauru, Universidade de São Paulo
(FOB-USP) and in the Post-graduation program at the Dental School of Ribeirão
Preto, Universidade de São Paulo (FORP-USP).
Submitted: April 13, 2017 - Revised and accepted: April 19, 2017
» The authors report no commercial, proprietary or financial interest in the products
or companies described in this article.
Contact address: Alberto Consolaro
E-mail: consolaro@uol.com.br
© 2017 Dental Press Journal of Orthodontics
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Dental Press J Orthod. 2017 May-June;22(3):21-5
orthodontic insight
Obesity and orthodontic treatment: is there any direct relationship?
Obesity has been considered a wide-spread condition
in the last 20 years. It is directly or indirectly connected
with an increase in the prevalence of a variety of human
diseases, such as malignant neoplasm, as identified among
900,000 Americans analyzed between 1982 and 1998.1
The authors conducting the study assessed the connection established between 57,145 deaths due to cancer with
the Body Mass Index (BMI) of those individuals. Those
with a BMI over 40 had the risk of dying from cancer
increased in 52% in comparison to those who had a BMI
between 20 and 24.9 — which is considered within normal standards. Among women, the risk was increased in
62%. The most prevalent types of cancer were: esophagus, colon, rectal, liver, vesicle, bile duct, pancreatic, kidney, multiple myeloma and non-Hodgkin’s lymphoma.
In the USA, obesity accounted for 20% of cancer deaths
among women and 14% among men.
Importantly, this type of study requires a high number of individuals in order to represent the overall population, as the number of variables is considerably high. The
connection established between obesity and cancer might
be considered of greater importance in comparison to
the connection between cancer and smoking, especially
because ¾ of the American population is overweight or
obese. In 2017, Kyrgiou et al11 from the Imperial College
London presented a thorough analysis of 204 studies on
obesity and cancer, revealing that the condition effectively
increases the risk of the following types of cancer: stomach, colon, rectal, bile duct, pancreatic, esophagus, breast,
endometrial, ovarian, kidney and multiple myeloma.
The connection established between obesity and
other diseases can be explained by the following hypotheses:
1st) One of the major hypothesis explains obesityrelated diseases by the increased secretion of hormones
produced by adipocytes commonly referred to as fat
cells. The term “hormone” can be used as reference to
any mediator/substance released at its production site,
capable of reaching further and yet producing an effect
which can be referred to as endocrine action.
In their host, adipocytes produce metabolically active proteins and adipokines, affecting metabolic function and inflammatory response,15 including proinflammatory leptins,24 resistin21 and anti-inflammatory adiponectin.20 Therefore, the adipose tissue might affect the
intensity and resolution of inflammatory processes in a
number of tissues.9,17
© 2017 Dental Press Journal of Orthodontics
Obesity also affects systemic metabolism in bones
through hormonal mechanical systems and inflammatory interactions,12 as well as by increasing mineral bone
density.18 It has been demonstrated that tooth eruption
speed is higher among obese individuals.13
In addition, those individuals present a higher risk of
chronic periodontitis10,22 inducing variations among metabolic and inflammatory markers, when compared to normal-weight individuals.16 Nevertheless, obese teenagers
reported having contributed less when submitted to long
orthodontic treatments with fixed appliances.14,23
2nd) The second hypothesis about obesity inducing
other chronic diseases is relative to inflammation found
in adipose tissues.4,5 In fact, this inflammatory process is
referred as such, but it actually represents an increased
concentration of macrophages among adipocytes. It is
even questionable whether such increased accumulation
of macrophages in the adipose tissue can be effectively
identified as inflammation as initially stated by Hotamisligil8 in 2006 — considering that macrophages are
also cells present in connective tissues.
Inflammation with clusters of macrophages in adipose tissues exist to eliminate fragments of cell dying
due to apoptosis, the mechanism by which old cells
die and tissues are renewed. The higher the number
of adipocytes, the greater the population of inflammatory or immune cells at the site, which would subsequently lead to inflammation in order to have the
affected region repaired.
At the time of repair, mediators stimulate cells to
proliferate at a higher rate, thus increasing the chances
of proliferation-related mistakes and the risk of malignant neoplasm. The higher amount of hormones released by adipocytes and inflammation with a view to
reaching repair at site must be directly associated with
other illnesses, namely: heart attack, diabetes, cancer
and autoimmune diseases.
Nearly 52% of the Brazilian population is overweight or obese, whereas in countries such as the
USA and Mexico that number reaches 70%. Obesity is an endemic condition not only in America, but
also in Europe, Australia, the Middle East and China.
A BMI value lower than 18.5 is typical of malnutrition, whereas values ranging between 18.5 and 24.9
is considered as healthy and normal, between 25 and
29.9 is typical of overweight and a BMI value equal
to 30 is typical of obesity.
22
Dental Press J Orthod. 2017 May-June;22(3):21-5
Consolaro A
orthodontic insight
BMI
< 10
10-19.9
20-29.9
≥ 30
Not evaluated
N/A
Figure 1 - Worldwide distribution of the percentage of obese population with BMI above 30 (source: WHO data5,11,12 in 2014).
Nevertheless, BMI is not the only trait used to assess
cases of obesity. Waist circumference2 is used as well,
since apple-shaped bodies signal that fat is accumulated among one’s abdominal viscera, which is way more
harmful. On the other hand, pear-shaped patients have
fat accumulation distributed focally, for instance, in
their hips, without necessarily having fat accumulated
in their abdomen.
Results achieved by Cerhan et al2 in 2004 with analyses
carried out in 11 studies involving 650,386 people in total
have proved waist circumference measurement as a method
used to assess patients under risk of obesity. Male patients
with waist circumference greater than 110 cm presented
mortality rates 52% higher than those with waist circumference lower than 90 cm. As for female patients, those
with waist circumference greater than 95 cm presented with
mortality rates 80% higher than those with measures lower
than 75 cm. Obesity-related illnesses and effects have been
associated with waist and hip-bone circumference.
Based on the aforementioned data, BMI might and
should be considered as an obesity criterion; however, it
is not seen as the best one used to assess mortality rates
and induction to other illnesses: without fat accumulation in one’s abdomen, risks are much lower.
© 2017 Dental Press Journal of Orthodontics
OBESITY AND ORTHODONTIC TREATMENT:
NO DIRECT CONNECTION!
Extrapolating findings on the influence of obesity to periodontal and bone tissues during orthodontic movement requires some degree of caution.
Variables regarding obesity itself and patients’ overall health, in addition to variables regarding tooth
movement, are plenty. Whenever great variability is
involved, studies on a high number of people to be
observed throughout time, usually for many years,
are required.
Several studies have revealed lack of direct connection between systemic factors, endocrine disorders as well as heredity and phenomena observed
during orthodontic movement, in terms of speed and
induced root resorption rates.6,7 One of the major
reasons is regarding some degree of normality concerning phenomena found during orthodontically
induced tooth movement, particularly in terms of
bone metabolism. During orthodontic movement,
the periodontal ligament experiences a greater deal
of cell stress and increased cell and tissue activity at
site in comparison to inflammation. Inflammation is
triggered at site only as a result of excess force.
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Dental Press J Orthod. 2017 May-June;22(3):21-5
orthodontic insight
Obesity and orthodontic treatment: is there any direct relationship?
patients undergoing orthodontic treatment with fixed
appliance, and obese patients required less time for
completion of tooth alignment in comparison to normal-weight patients; however, such finding was not
statistically significant.
Taking the epidemiological extent of obesity into
account, as well as its multiple consequences, any finding and evidence of influences it exerts over orthodontically induced tooth movement require samples to
be uniform in terms of diagnosis and treatment plan,
in addition to treatment extent and time and more
precise criteria on the type of obesity. Above all, the
number of patients comprising the sample should be
rather considerable. Meanwhile, experimental studies
carried out with obese animals should likely present
limitations and there should be some degree of caution
when extrapolating their outcomes to humans.
Another reason for being cautious in extrapolating the effects of obesity on orthodontic movement is
relative to the role played by cementoblasts, a type of
cell which does not respond to bone turnover mediators due to lacking cell membrane receptors.3 This is a
natural characteristic which ensures that teeth remain
preserved in the ongoing process of bone contouring.
Recently, Saloom et al19 sought to obtain evidence showing that tooth movement in obese patients would occur within a shorter period of time up
to the moment when alignment would be achieved
by means of fixed appliances. However, in order to
gather such probable data, the authors compared 28
normal-weight adolescents with 27 obese ones, a
quite small sample of patients, especially if obesityrelated variables as well as parallel diagnoses and orthodontic movement-related variables were taken into
consideration. Obesity type, waist circumference and
adipose tissue accumulation site were not assessed
nor compared as they should have. Results involving
all 55 patients – 27 males and 28 females with mean
age of 15.1 years – were quite inconsistent, as stated
by the authors themselves. Gingival and dental plaque
build-up indexes were increased among obese patients.
In addition to tooth movement, the authors measured
a number of biochemical markers in patients’ saliva.
Results revealed no differences among groups, thus
not allowing them to draw any conclusive evidence
based on their findings.
The analysis carried out by Saloom et al19 reveals
an increase in the rate of tooth movement, especially during the first week, but the rate of orthodontic
alignment finishing remained the same. In the last
paragraph, the article concludes: Obese patients need
less time for completion of tooth alignment in comparison to normal-weight patients; however, such
finding is not statistically significant. Orthodontic
movement rate during the first week was significantly
increased in the obese group. Nevertheless, the period that goes from one week to finished alignment
was not significantly different between groups.
In short, it is possible to conclude, based on the
authors’ statements, that this prospective study investigated tooth alignment in obese and normal-weight
© 2017 Dental Press Journal of Orthodontics
FINAL CONSIDERATIONS
The first study aiming at establishing a connection between obesity and the rate of induced orthodontic tooth movement was conducted by Saloom
et al;19 however, it could not effectively nor significantly reveal any direct influence or effect. Despite
being identified during the first week, differences
could not be explained and treatment time remained
unchanged.
In spite of lack of studies in the literature on the
connection between obesity and the rate of induced
tooth movement, in clinical practice, courses or
specialized training, we should not have protocols
changed nor adopt any measures or expect significant
differences between normal-weight and obese individuals. It should be emphasized that unsuccessful
cases or cases of root resorption associated with treatment should not be assigned to obesity, since scientific data is insufficient to do so.
Based on the fact that the majority of the western
population is overweight or obese, it is proved to be
relevant to have insights for future research carried out
with significant samples, so as to determine whether
specific situations or care are required for orthodontic
patients bearers of obesity — considering that appropriate literature on the matter is insufficient.
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Consolaro A
orthodontic insight
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