RESUMO Objetivo: o objetivo deste estudo foi comparar as doses equivalentes e efetivas absorvidas pelo mesmo receptor, quando exposto a diferentes exames radiográficos digitais (panorâmica, telerradiografia lateral e periapicais) e à tomografia computadorizada de feixe cônico (TCFC). Métodos: dosímetros termoluminescentes pré-calibrados foram colocados em 24 locais em um phantom antropomórfico (Alderson Rando Phantom, Laboratórios de Pesquisas de Alderson, New York, NY, EUA), o que representa um adulto de tamanho médio. Os seguintes equipamentos foram avaliados: Heliodent Plus (Sirona Dental Systems, Bernsheim, Alemanha), Orthophos XG 5 (Sirona Dental Systems, Bernsheim, Alemanha) e i-CAT (Imaging Sciences International, Hatfield, PA, EUA). As doses equivalentes e as doses efetivas foram calculadas tendo-se em conta as recomendações da Comissão Internacional de Proteção Radiológica (International Commission on Radiological Protection, ICRP), publicadas em 1990 e 2007. Resultados: embora a dose eficaz do set radiográfico tenha correspondido a 17,5% (ICRP 1990) e 47,2% (ICRP 2007) da dose da TCFC, as doses equivalentes na pele e superfícies ósseas e musculares desse set foram maiores, quando comparadas às da TCFC. Em algumas áreas, a radiação produzida pelo set de radiografias foi maior, devido à radiação do exame periapical completo. Conclusão: considerando-se o princípio da otimização da proteção radiológica, a tomografia computadorizada adquirida no tomógrafo i-CAT deve ser usada apenas em circunstâncias específicas e justificadas. Além disso, seguindo o princípio ALARA, radiografias periapicais unitárias de áreas pré-selecionadas são mais apropriadas do que o exame periapical completo.

ABSTRACT Objective: The aim of this study was to compare the equivalent and effective doses of different digital radiographic methods (panoramic, lateral cephalometric and periapical) with cone-beam computed tomography (CBCT). Methods: Precalibrated thermoluminescent dosimeters were placed at 24 locations in an anthropomorphic phantom (Alderson Rando Phantom, Alderson Research Laboratories, New York, NY, USA), representing a medium sized adult. The following devices were tested: Heliodent Plus (Sirona Dental Systems, Bernsheim, Germany), Orthophos XG 5 (Sirona Dental Systems, Bernsheim, Germany) and i-CAT (Imaging Sciences International, Hatfield, PA, USA). The equivalent doses and effective doses were calculated considering the recommendations of the International Commission of Radiological Protection (ICRP) issued in 1990 and 2007. Results: Although the effective dose of the radiographic set corresponded to 17.5% (ICRP 1990) and 47.2% (ICRP 2007) of the CBCT dose, the equivalent doses of skin, bone surface and muscle obtained by the radiographic set were higher when compared to CBCT. However, in some areas, the radiation produced by the orthodontic set was higher due to the complete periapical examination. Conclusion: Considering the optimization principle of radiation protection, i-CAT tomography should be used only in specific and justified circumstances. Additionally, following the ALARA principle, single periapical radiographies covering restricted areas are more suitable than the complete periapical examination.

AIM: In order to determine the reliability between two of these methodologically different method, this study evaluated the systematic and random errors of the method proposed by Tanaka and Johnston, which is based on the sum of mandibular permanent incisors, and the Huckaba method, which uses radiographs. METHODS: In a random sample of 28 plaster models of mandibular dental arches belonging to individuals of both genders, aged six to eleven years old, a single investigator performed the measurement of required space, according to the two methods evaluated. After 15 days, the measurements were repeated, and each of them was performed twice in sequence to calculate the repeatability and reproducibility conditions, and the systematic and random errors for each method. RESULTS: The random error of the method proposed by Huckaba was larger in terms of reproducibility (1.53 mm) and repeatability (0.57 mm) compared with the analysis proposed by Tanaka and Johnston (0.20 mm and 0.12 mm, respectively). CONCLUSIONS: The method proposed by Huckaba was proved to be inadequate in relation to reproducibility, with respect to the random error, and should be used with caution to measure the required space in the mandibular arch.

O objetivo da pesquisa foi estudar o crescimento da nasofaringe e o desenvolvimento da adenóide. Foram utilizadas as radiografias cefalométricas de perfil obtidas de 320 indivíduos brasileiros brancos, cujas idades variavam entre 4 e 16 anos. Todos os participantes apresentavam respiração predominantemente nasal e não haviam sido submetidos previamente à adenoidectomia. A partir das radiografias foram feitos traçados cefalométricos, sobre os quais foram realizadas medições. Os resultados revelaram que a espessura sagital da adenóide é maior na faixa etária de 4 a 5 anos, regredindo, então, progressivamente, até a faixa etária de 10 a 11 anos, quando ocorre um leve aumento, voltando a diminuir em seguida. O espaço aéreo livre nasofaríngeo, entretanto, não diminui na faixa etária de 10 a 11 anos, mesmo diante do aumento da espessura da adenóide. Esse fato se deve ao deslocamento do palato duro para baixo, o que determina a ampliação do espaço aéreo livre em razão do crescimento. Apesar de a nasofaringe seguir um padrão de crescimento similar ao do resto do corpo, a adenóide não o segue. O desenvolvimento da adenóide parece ser diferente do dos demais tecidos de origem linfóide, apresentando um padrão peculiar que pode ser percebido quando se elimina a hipertrofia causada por infecções e alergias.

The purpose of this research was to study the growth of the nasopharynx and adenoid development. Lateral cephalometric radiographs obtained from 320 white Brazilian subjects between 4 and 16 years of age were used. All the participants were nose breathers and none of them had previously undergone adenoidectomy. Tracings were made from the radiographs and cephalometric measurements were performed. The results showed that adenoid sagital thickness is larger in the age group 4 - 5 years and decreases progressively. There is a slight increase in the age group 10 - 11 years, but afterwards the decrease continues. However, the nasopharyngeal free airway space does not decrease in the age group 10 - 11 years, despite the increasing thickness of the adenoid. This is attributable to the downward displacement of the hard palate, resulting in an increase of the free airway space due to growth. Although the nasopharynx follows a growth pattern similar to that of the rest of the body, adenoid tissue does not. Adenoidal development seems to differ from that of other lymphatic tissues, showing a peculiar pattern that can be revealed when hypertrophy due to infections and allergies is eliminated.