Tooth resorptions are not hereditary

ABSTRACT Root resorptions caused by orthodontic movement are not supported by consistent scientific evidence that correlate them with heredity, individual predisposition and genetic or familial susceptibility. Current studies are undermined by methodological and interpretative errors, especially regarding the diagnosis and measurements of root resorption from orthopantomographs and cephalograms. Samples are heterogeneous insofar as they comprise different clinical operators, varied types of planning, and in insufficient number, in view of the prevalence of tooth resorptions in the population. Nearly all biological events are coded and managed through genes, but this does not mean tooth resorptions are inherited, which can be demonstrated in heredograms and other methods of family studies. In orthodontic root resorption, one cannot possibly determine percentages of how much would be due to heredity or genetics, environmental factors and unknown factors. There is no need to lay the blame of tooth resorptions on events taking place outside the orthodontic realm since in the vast majority of cases, resorptions are not iatrogenic. In orthodontic practice, when all teeth are analyzed and planned using periapical radiography or computerized tomography, and when considering all predictive factors, tooth resorptions are not iatrogenic in nature and should be considered as one of the clinical events inherent in the treatment applied.

RESUMO As reabsorções radiculares decorrentes da movimentação ortodôntica não têm evidência científica consistente que as correlacione com a hereditariedade, predisposição e suscetibilidade genética ou familiar. Os trabalhos sobre esse tema apresentam erros metodológicos e interpretativos, em especial quanto ao diagnóstico e à mensuração das reabsorções radiculares a partir de ortopantomografias e cefalogramas. As amostras são heterogêneas - quanto aos operadores clínicos e tipos de planejamentos aplicados - e em número muito pequeno, considerando-se a prevalência das reabsorções dentárias na população. Quase todos os eventos biológicos são codificados e gerenciados a partir dos genes, mas não por isso as reabsorções dentárias são hereditárias, o que seria demonstrado em heredogramas e outras formas de estudos familiares. Nas reabsorções radiculares em Ortodontia, não é possível determinar percentuais de quanto seria decorrente da hereditariedade ou da genética, de fatores ambientais e de fatores desconhecidos. Não se faz necessário transferir a "culpa" das reabsorções dentárias para eventos externos à Ortodontia pois, na grande maioria dos casos, elas não são iatrogênicas. Na prática ortodôntica, quando se faz a análise de todos os dentes e o planejamento, via radiografia periapical ou tomografia computadorizada, e quando se leva em consideração os fatores preditivos, as reabsorções dentárias não serão de natureza iatrogênica, e devem ser encaradas como uma das intercorrências clínicas do tratamento aplicado.

Polimorfismo (+3954c>T) del gen IL-1B y su asociación con la resorción radicular apical externa post-tratamiento ortodóntico / IL-1B (+3954c>T) gene polymorphism and its association with external root resorption after orthodontic treatment

El objetivo fue determinar la presencia del polimorfismo rs1143634 (+3954C>T) del gen Interleuquina 1 Beta (IL-1B) y su asociación con la resorción radicular apical externa (RRE) post-tratamiento ortodóntico. Se realizó un estudio piloto de individuos tratados con aparatología ortodontica, 13 (casos) presentaron RRE posterior al tratamiento ortodóntico y 22 (controles) estaban clínicamente sanos. A partir de muestras de células epiteliales de mucosa bucal se extrajo ADN y se genotipificó el polimorfismo rs1143634 (+3954C>T) del gen IL-1B mediante la reacción en cadena de la polimerasa y digestión del producto con la enzima de restricción TaqI. Se estimaron las frecuencias alélicas y genotípicas del rs1143634; además, se evaluó la desviación del equilibrio de Hardy-Weinberg. Las frecuencias alélicas y genotípicas se compararon mediante la prueba de c2 con razón deverosimilitud (p <0,05). El promedio de edad de los participantes fue 28,1 (DE=11,5) años y el 68,6 % era mujeres. Al comparar la distribución de los genotipos del polimorfismo IL-1B (+3954C>T) entre grupos no se encontró una diferencia estadísticamente significativa (p=0,0926). Sin embargo, se observó una diferencia significativa en la distribución de alelos (p= 0,035), siendo el alelo T (alelo 2) más prevalente en el grupo control. El polimorfismo IL-1B (+3954C>T) se encontró presente en la población de estudio. Aunque no existieron diferencias en la distribución de los genotipos que apoyara una asociación entre este polimorfismo y la RRE, si hubo una diferencia en la distribución de los alelos, sugiriendo que el alelo T posiblemente actúa como factor protector contra el desarrollo de la RRE.

The objective of this study was to determine the presence of Interleukin 1 beta (IL-1B) rs1143634 (+3954C>T) gene polymorphism and its association with external apical root resorption (ERR) after orthodontic treatment. We conducted a pilot study of individuals treated with orthodontic treatment, 13 (cases) had ERR after orthodontic treatment and 22 (controls) were clinically healthy. DNA was extracted from samples of epithelial cells from the oral cavity and IL-1B rs1143634 (+3954C>T) gene polymorphism was genotyped by polymerase chain reaction and digestion product through the TaqI restriction enzyme. Genotype and allele frequencies of rs1143634 were estimated; in addition, the deviation from Hardy-Weinberg equilibrium was assessed. Allele and genotype frequencies were compared using the c2 test with likelihood ratio (p <0.05). The mean age of participants was 28.6 (SD= 11.5) years and 68.6 % were females. No statistically significant association was found between the genotypes distribution of IL-1B (+3954C>T) polymorphism with ERR (p= 0.0926). However, a significant difference in the alleles distribution (p= 0.035) was observed, where the allele T (allele 2) was more prevalent in the control group. IL-1B (+3954C>T) polymorphism was present in the study population. Although there were no differences in the genotypes distribution to support an association between this polymorphism with ERR, there was a difference in the alleles distribution, suggesting that the allele T possibly acts as a protective factor against the development of ERR.