Evaluation of radiographic magnification in lateral cephalograms obtained with different X-ray devices: experimental study in human dry skull

OBJECTIVE: The purpose of this study was to evaluate the influence of the magnification factor of the radiographic image in angular, linear and proportional measurements. METHODS: From a dried human skull where metallic spheres with predetermined size were fixed (1.0 mm), 14 radiographs were obtained in devices of three different manufacturers: Panoura, Instrumentarium and Tomeceph. The Pearson correlation test was used to investigate the relationship between the rate of radiographic magnification and the cephalometric measurements assessed. RESULTS: According to the results, the linear measurements showed a high positive correlation, pointing out great influence of the magnification factor, while the angular and proportional measurements did not correlate. CONCLUSIONS: Comparisons between linear cephalometric measurements obtained with different devices from the same manufacturer showed maximum rates of expansion of 0.6%, 1.25% and 2.3%, respectively, for the devices from Instrumentarium (OP-100, Instrumentarium, Finland), Panoura (10CSU, Yoshida, Japan) and Satelec/Tomeceph (XMind, Satelec/Tomeceph Orion Corporation, Finland).

OBJETIVO: avaliar a influência do fator de magnificação da imagem radiográfica nas grandezas angulares, lineares e proporcionais. MÉTODOS: a partir de um crânio seco humano, no qual foram fixadas esferas metálicas de dimensões pré-definidas (1,0mm de diâmetro), 14 telerradiografias foram obtidas em diferentes aparelhos de três fabricantes: Panoura, Instrumentarium e Tomeceph. Foi realizada a análise estatística descritiva e utilizado o teste de correlação de Pearson para verificar a relação entre a taxa de magnificação radiográfica e as grandezas cefalométricas analisadas. RESULTADOS: as medidas lineares apresentaram alta correlação positiva, evidenciando grande influência do fator de magnificação sobre essas grandezas, ao passo que as angulares e proporcionais não apresentaram correlação. CONCLUSÃO: comparações entre medidas cefalométricas lineares obtidas com diferentes aparelhos do mesmo fabricante demonstraram taxas de ampliações máximas de 0,6%, 1,25% e 2,3%, respectivamente, para os aparelhos Instrumentium (OP-100 Instrumentarium), Panoura (10CSU Yoshida) e Satelec/Tomeceph (XMind Satelec/Tomeceph Orion Corp).

Facial harmony in orthodontic diagnosis and planning

Facial Harmony is one of the main goals of orthodontic treatment, and it is not always correlated with the attainment of cephalometric objectives. The purpose of this study was to evaluate two groups of subjects presenting a clinically balanced soft tissue profile using cephalometric radiographs. Thirty lateral cephalometric radiographs of white females, divided in two groups, one with excellent facial profile (Group 1), and the other with good facial profile (Group 2) were used. Student's t-test (P?< .05) was used to compare the cephalometric parameters of the 2 groups. Linear regression analysis was also performed between 1.NB and SnV-Pog and between AB horizontal and SnV-Pog'. Group 2 showed higher mean values than group 1 for ANB (p = 0.002), AB horizontal (p < 0.001), 1.NB (p < 0.001), and a lower mean value for SnV-Pog (p = 0.003). The higher the SnV-Pog value, the lower the 1.NB value, no matter what group was evaluated. For each 1 mm increase in SnV-Pog, a 0.61º decrease could be expected in 1.NB (p = 0.003). The higher the SnV-Pog value, the lower the AB horizontal value, although group 2 presented greater AB horizontal values. For each 1 mm increase in SnV-Pog, a 0.24 mm decrease could be expected in AB horizontal (p = 0.019). We concluded that women with good facial profile do not necessarily present the same cephalometric values, and facial analysis should be the main reference in planning orthodontic treatments and should be considered together with cephalometric analysis in an individualized way.

Reproducibility, reliability and validity of measurements obtained from Cecile3 digital models

The aim of this study was to determine the reproducibility, reliability and validity of measurements in digital models compared to plaster models. Fifteen pairs of plaster models were obtained from orthodontic patients with permanent dentition before treatment. These were digitized to be evaluated with the program Cécile3 v2.554.2 beta. Two examiners measured three times the mesiodistal width of all the teeth present, intercanine, interpremolar and intermolar distances, overjet and overbite. The plaster models were measured using a digital vernier. The t-Student test for paired samples and interclass correlation coefficient (ICC) were used for statistical analysis. The ICC of the digital models were 0.84 ± 0.15 (intra-examiner) and 0.80 ± 0.19 (inter-examiner). The average mean difference of the digital models was 0.23 ± 0.14 and 0.24 ± 0.11 for each examiner, respectively. When the two types of measurements were compared, the values obtained from the digital models were lower than those obtained from the plaster models (p < 0.05), although the differences were considered clinically insignificant (differences < 0.1 mm). The Cécile digital models are a clinically acceptable alternative for use in Orthodontics.

Avaliaçäo da reprodutibilidade da posiçäo natural da cabeça: estudo radiográfico / Evaluation of natural head position reproducibility: a radiographic study

O objetivo neste estudo foi avaliar a reprodutibilidade do registro da Prosiçäo Natural da Cabeça (PNC) em crianças brasileiras como método de padronizaçäo para obtençäo de telerradiografias em norma lateral. Foram utilizadas 30 telerradiografias laterais, obtidas de 15 pacientes tratados na Clínica de Ortodontia Preventiva da Faculdade de Odontologia da Universidade de São Paulo. A amostra consistiu de crianças dos sexos masculino e feminino, com idade de 5 anos e 10 meses e 12 anos. De acordo com o protocolo da clínica duas séries de radiografias foram obtidas com intervalos de 4 a 6 meses. A PNC foi obtida com os pacientes em pé, utilizando-se o método do espelho. Para testar a reprodutibilidade foi utilizada a referência intracraniana SN, linha que une os pontos Sela e Násio, que ao interceptar a linha Vertical Verdadeira (referência extracraniana cuja imagem radiopaca aparece na película radiográfica), forma um ângulo que corresponde ao grau de inclinaçäo da cabeça. Utilizando-se a fórmula de Dahlberg para avaliar o erro do método e o teste t de Student, obteve-se o valor de 1,15 indicando que a Posiçäo Natural da Cabeça foi reproduzível na amostra estudada, o que valida sua utilizaçäo na obtençäo de radiografias em norma lateral com finalidade ortodôntica