Applicability of cone beam computed tomography gray values for estimation of primary stability of dental implants / Aplicabilidade dos valores de cinza da tomografia computadorizada de feixe cônico na estimativa da estabilidade primária de implantes dentários

Objetivo: Avaliar a relação entre a densidade óssea medida em imagens de tomografia computadorizada (TC) e tomografia computadorizada de feixe cônico (TCFC) e relacionar com a estabilidade primária de implantes dentários. Material e métodos: Foram utilizadas neste estudo 20 cabeças femorais bovinas frescas, preparadas pela remoção de partes moles, secção do osso e colocação de marcadores para localização e angulação dos implantes. A densidade óssea da área peri-implantar foi determinada no pré-operatório em imagens TC e TCFC das amostras de osso peparado, representadas por unidades Hounsfield (HUs) e valores de cinza (GVs), respectivamente. Em seguida, 60 implantes em três tamanhos (diâmetro = 4 mm, comprimento = 8, 10 e 12 mm) foram inseridos nos ossos e o torque máximo de inserção (TI) foi registrado. O dispositivo Osstell também foi usado para determinar o quociente de estabilidade do implante (ISQ) para cada implante. A análise estatística foi realizada nos dados (α = 0,05). Resultados: Os valores médios ± DP de GV,HU e ISQ foram 1592,75 ± 231,82, 675,26 ± 115,38 e 61,90 ± 10,14, respectivamente. Além disso, o limite de TI mais frequente foi 30-35 Ncm (41,4%). Relações significativas foram observadas entre HU e IT, GV e IT, HU e ISQ, GV e ISQ, e IT e ISQ em todos os tamanhos de implante. Os GV e HU também se correlacionaram significativamente. Conclusão: Os valores da densidade óssea em imagens de TCFC e TC mostram-se positivamente associados para estabilidade primária de implantes dentários. Portanto, os GVs obtidos no Sistema de TCFC (Sirona's Galileos) poderiam ser usados para a seleção pré-operatória de sítios edêntulos que permitam uma melhor estabilidade do implante ou locais que requerem procedimentos adicionais para aumentar a taxa de sucesso dos implantes dentários. (AU)

Objective: To evaluate the relationship between bone density measured by computed tomography (CT) and cone beam computed tomography (CBCT) (Sirona's Galileos scanner) with primary stability of dental implants. Material and methods: 20 fresh bovine femoral heads were prepared by removal of soft tissue, sectioning of the bone, and placement of markers for location and angulation of implants. Bone density of peri-implant areas was determined preoperatively by CT and CBCT scanning of the prepared bone samples represented by Hounsfield units (HUs) and gray values (GVs), respectively. Then, 60 implants in three sizes (diameter = 4 mm, length = 8, 10, and 12 mm) were inserted into the bones and maximum insertion torque (IT) was recorded. Osstell device was also used for determining the implant stability quotient (ISQ) for each implant. Statistical analysis was performed on the data (α = 0.05). Results: Mean ± SD values of GV,HU, and ISQ were 1592.75 ± 231.82, 675.26 ± 115.38 and 61.90 ± 10.14, respectively. Moreover, the most frequent IT limit was 30-35 Ncm (41.4%). Significant relationships were observed between HU and IT, GV and IT, HU and ISQ, GV and ISQ, and IT and ISQ in all implant sizes. Moreover, GV and HU also significantly correlated to each other. Conclusion: Bone density values in CBCT and CT scans are positively associated to primary stability of dental implants. Therefore, GVs obtained from Galileos CBCT scanner can be used for preoperative selection of edentulous sites which allow for better implant stability or locations which require further procedures for enhancing the success rate of dental implants (AU)

Accuracy of Demirjian’s Method to Estimate Chronological Age in 5‒17-Year-Old Iranian Population

Introduction:To detect physiological maturity of a child, use of dental and skeletal development can be helpful. The Demirjian’s Method is one of the commonly used methods to estimate dental age. The aim of the present study was to evaluate the validity of Demirjian method in Iranian population with different races.Materials and Methods:The present cross-sectional study was performed on a randomly selected sample of panoramic radiographs of 3073 patients aged 5‒17 years. The chronological age (CA) was calculated by subtracting the date of birth from the date on which the radiographs were taken. Estimated age (EA) was performed by Demirjian method using seven left mandibular teeth. Paired t-test was used to compare differences between chronological and estimated age.Results:The mean of CA was 11.14±2.61 years whereas the mean EA was 11.35±2.62; Original Research Article therefore, EA was calculated 2.5 months more than CA. According to paired t-test the difference between CA & EA was significant (P≤ 0.001). Pearson’s correlation coefficient showed a strong linear correlation between CA and EA in total (r=0.891, P≤0.001), in girls (r=0.895, P≤ 0.001) and in boys (r=0.876, P≤ 0.001). The new regression line equation based on Iranian standards would be CA=1.08±0.89EA in total, CA=1.09±0.89EA in girls and CA=1.12+0.88EA in boys. Conclusion:Using Demirjian’sMethod overestimated dental age in the Iranian population. A new regression line equation based on Iranian standards was obtained according to the results of the present study