Agenesia del tercer molar en pacientes atendidos en la clínica odontológica de la Universidad de Antofagasta, Chile / Third molar agenesis in patients of dental clinic of the Universidad de Antofagasta, Chile

Se define agenesia como la ausencia de dientes por alteraciones genéticas aisladas o sindrómicas. La agenesia del tercer molar está asociada a malformaciones y es considerada por diversos autores, consecuencia de la evolución humana (Larmour et al., 2005). Son los dientes con mayor prevalencia de agenesia junto con segundos premolares e incisivos laterales (Fuller & Denehy, 1984). La prevalencia varía entre 9% y 37% (McNamara & Foley, 2006); Arboleda et al. (2006) señalan una prevalencia del 20%. La literatura indica variables estadísticas porcentuales, por género, por arcada dentaria, por lado y por diente, con escasos artículos sobre grupos originarios de Chile. La población en estudio consistió en 52 hombres y 48 mujeres, de 14 a 26 años de edad, pacientes de la Clínica Odontológica de la Universidad de Antofagasta. Todos los individuos eran sanos, sin ninguna malformación general o maxilofacial, no habían presentado enfermedades infecciosas que afectaran la odontogénesis y los períodos de erupción dentarios, sin exodoncias de ningún tercer molar y tratamiento ortodóncico previo al examen radiográfico panorámico. Se determina un 20,0% de casos de agenesia, con 8,25% de agenesia, respecto a número total de terceros molares y 1,03% de agenesia de terceros molares en relación al total de dientes. No se determina ninguna diferencia estadística significativa al 95% de confianza, predominando la agenesia en el género femenino, a nivel maxilar, en el lado izquierdo, de tipo simple, siendo el tercer molar superior izquierdo el diente que presenta el mayor número de casos de agenesia.

Agenesis is defined as the absence of teeth by genetic alterations isolated or syndromic. Agenesis of third molar is associated to malformations and is considerate by diverse authors as a consequence of human evolution (Larmour et al, 2005). The third molars are teeth with higher prevalence of agenesis together with seconds premolars and lateral incisive (Fuller & Denehy, 1984). The prevalence varies between 9 percent to 37% (McNamara & Foley, 2006). Arboleda et al. (2006) indicated a prevalence of 20%. The literature notes statistical variables percentage by gender, dental arch, side, and tooth, with few articles on groups originating from Chile. The population in study consisted of 52 men and 48 women between 14 and 26 years old, patients of the dental clinic of the Universidad de Antofagasta. All individuals were healthy, without any general or maxillofacial malformation without infectious diseases affecting the odontogenesis and dental eruption, without extractions of third molar and orthodontic treatment prior to the panoramic x-ray. A 20% of individuals with agenesis was determined, with 8.25% of agenesis respect the total number of third molars and 1.03% agenesis respect the total number of teeth. Statistical analyses did not show significant differences at 95% level, with agenesis of third molar prevalence in females, in maxilla, in the left side, simple, being the left maxillary third molar the tooth that present many number of agenesis.

Agenesia del tercer molar en una etnia originaria del Norte de Chile: atacameños o Lican Antai / Third molar agenesis in native ethnia from north of Chile: atacamenos or Lican Antai

Agenesia es la ausencia de dientes por alteraciones genéticas aisladas o sindrómicas. La agenesia del tercer molar está asociada a malformaciones y considerada por diversos autores consecuencia de la evolución humana (Larmour et al., 2005). Son los dientes con mayor prevalencia de agenesia junto a los segundos premolares e incisivos laterales (Fuller & Denehy, 1984). La prevalencia varía entre 9 y 37 por ciento (McNamara & Foley, 2006), en tanto, Arboleda et al. (2006) señalan una prevalencia del 20 por ciento. La literatura señala variables estadísticas porcentuales, por género, por arcada dentaria, por lado y por diente, con escasos artículos sobre grupos originarios de Chile. La población en estudio consistió en 33 hombres y 57 mujeres de 16 a 55 años, de la etnia atacameña, sin exodoncias del tercer molar ni tratamientos ortodónticos y sin malformaciones congénitas. Se determinó el grado de mestizaje mediante técnica serológica de hemo-aglutinación y por aplicación de la fórmula de Bernstein, que demostró 56 por ciento de mezcla indígena. A cada individuo se le tomó radiografía panorámica para observar presencia o ausencia de terceros molares. Se determina un 26,7 por ciento de individuos con agenesia de uno o más terceros molares, con mayor porcentaje en hombres. En la muestra y en hombres hay mayor agenesia de terceros molares mandibulares; en cambio, en mujeres existe mayor agenesia de terceros molares maxilares. Predominan agenesias izquierdas, lo mismo se comprueba en mujeres, mientras en hombres se comprueba igual porcentaje bilateral. Predomina la agenesia de dos molares en ambos sexos. No existen diferencias estadísticas significativas al 95 por ciento y los resultados coinciden con la literatura. La investigación representa un aporte a la antropología del Norte de Chile, pero considerando lo reducido de la muestra, no fue posible determinar variables étnicas.

Agenesis is the absence of teeth by genetic alterations, single or as syndrome. Agenesis of third molar is associated to malformations and is considered by diverse authors a consequence of the human evolution (Larmour et al., 2005). The third molars together with second premolars and lateral incisors are the teeth with greater prevalence of agenesis (Fuller & Denehy, 1984). The prevalence varíes between 9 percent and 37 percent (McNamara & Foley, 2006); Arboleda et al. (2006) indicated a prevalence of 20 percent. Literature indicate variable percentage, by gender, dental arches, side and tooth, with few arricies on original groups of Chile. The population in study consisted of 33 men and 57 women between 16 and 55 years of the ethnic group of atacameños, without extractions of third molar ñor orthodontic treatments and without congenital malformations. Hybridism was determined by means of serum technique by blood agglutination and by application of the formula of Bernstein, demonstrated a 56 percent of indigenous mixture. To each individual a panoramic x-ray was taken to observe presence or absence of third molars. A 26.7 percent of individuals with agenesis of one or more third molars was determined, with greater percentage among males. Agenesis lower third molar predominates in the sample and in men; however in women are greater agenesis upper third molar. In addition, agenesis predominates of the left side in both sexes, while in men equal bilateral percentage is verified. Agenesis of two molars predominates in both sexes. Statistical analyses did not show significant differences at the 95 percent level, and the results, in general, agree with those in the literature. This research represents a contribution to the anthropology of the north of Chile, but it is not possible to determine ethnic variables considering the small sample in study.

A influência do terceiro molar no apinhamento ântero-inferior / The influence of the third molar on lower anterior crowding

O presente trabalho tem como objetivo avaliar a influência do terceiro molar no apinhamento ântero-inferior bem como indicar a melhor conduta clínica aos Cirurgiões-Dentistas para resolução desse problema. Por meio de revisão de literatura, foram avaliadas a erupção, a impactação, a agenesia e a exodontia profilática dos terceiros molares em relação ao apinhamento dentário. Pôde-se observar a prevalência de três pensamentos distintos a respeito da etiologia: primeiro, a ação dos terceiros molares, por exercerem uma pressão mesial; segundo, acreditou-se que os terceiros molares possuem influência, mas não é a única causa determinante; o último descartou totalmente o relacionamento entre o apinhamento e o terceiro molar. Ademais, de acordo com os autores, a remoção profilática do terceiro molar, a fim de diminuir a força de contato interproximal e solucionar o problema do apinhamento, só foi válida, fossem analisados simultaneamente todos os fatores associados a esse problema. Dessa forma, pode-se afirmar que em pacientes com dentição permanente completa, não foi possível associar o apinhamento ântero-inferior com a presença dos terceiros molares inferiores erupcionados e/ou impactados.

The aim of the present study was to assess the influence of the third molar on lower anterior crowding, as well as to recommend the best clinical management for dental practitioners to solve this problem. The eruption, impaction, agenesis and prophylactic removal of lower crowding were evaluated by means of a review of the literature. It was possible to observe the prevalence of three distinct postures regarding the etiology : first, the action of the third molar in exerting a forward pressure; second, the belief that the third molar has some influence, but is not the only cause; and third, a total rejection of a relationship between crowding and the third molar. Moreover, according to the authors, the prophylactic removal of the third molar to reduce the force of the interproximal contact and to solve the problem of crowding was only valid if all factors associated with this problem were analyzed simultaneously. Therefore, it can be asserted that in patients with complete permanent dentition it was not possible to associate antero-inferior crowding with mandibular erupted and/or impacted third molars.