Digital models: How can dental arch form be verified chairside?

ABSTRACT Introduction: Plaster dental casts are routinely used during clinical practice to access maxillary dental arch form and assist on fabrication of individualized orthodontic archwires. Recently introduced, digital model technology may offer a limitation for the obtainment of a dental physical record. In this context, a tool for dental arch form assessment for chairside use is necessary when employing digital models. In this regard, paper print of the dental arch seems thus to be useful. Methods: In the present study, 37 lower arch models were used. Intercanine and intermolar widths and dental arch length measurements were performed and compared using plaster dental casts, digital models and paper print image of the models. Ortho Insight 3D scanner was employed for model digitalization. Results: No statistically significant differences were noted regarding the measurements performed on the plaster or digital models (p> 0.05). Paper print images, however, showed subestimated values for intercanine and intermolar widths and overestimated values for dental arch length. Despite being statistically significant (p< 0.001), the differences were considered clinically negligible. Conclusion: The present study suggests that paper print images obtained from digital models are clinically accurate and can be used as a tool for dental arch form assessment for fabrication of individualized orthodontic archwires.

RESUMO Introdução: os modelos de gesso são usados rotineiramente, durante a prática clínica, para avaliação da forma da arcada inferior e para auxiliar na confecção de arcos ortodônticos individualizados. A tecnologia dos modelos digitais, introduzida recentemente, pode oferecer uma limitação na obtenção de um registro físico da arcada dentária. Assim, quando se utilizam modelos digitais, faz-se necessária uma ferramenta clínica para obtenção da forma da arcada. Com essa finalidade, poderia-se imprimir, em papel, uma imagem da arcada dentária obtida a partir do modelo de gesso. Métodos: nesse estudo, 37 modelos da arcada inferior foram utilizados, nos quais foram realizadas medições das distâncias intercaninos, intermolares e comprimento da arcada; sendo, então, comparadas entre modelos de gesso, modelos digitalizados com um scanner Ortho Insight 3D e imagens impressas em folha de papel A4. Resultados: não foram encontradas diferenças estatisticamente significativas nas medidas realizadas nos modelos de gesso e modelos digitais (p > 0,05). As imagens impressas, contudo, mostraram valores subestimados para as distâncias intercaninos e intermolares, e superestimados para o comprimento da arcada. Apesar de serem estatisticamente significativas (p< 0,001), as diferenças foram consideradas clinicamente insignificantes. Conclusão: o presente estudo sugere que as imagens obtidas por meio dos modelos digitais e impressas em papel são clinicamente acuradas e podem ser utilizadas como uma ferramenta auxiliar na confecção dos arcos ortodônticos individualizados.

Effect of the High-Pitch Mode in Dual-Source Computed Tomography on the Accuracy of Three-Dimensional Volumetry of Solid Pulmonary Nodules: A Phantom Study

OBJECTIVE: To evaluate the influence of high-pitch mode (HPM) in dual-source computed tomography (DSCT) on the accuracy of three-dimensional (3D) volumetry for solid pulmonary nodules. MATERIALS AND METHODS: A lung phantom implanted with 45 solid pulmonary nodules (n = 15 for each of 4-mm, 6-mm, and 8-mm in diameter) was scanned twice, first in conventional pitch mode (CPM) and then in HPM using DSCT. The relative percentage volume errors (RPEs) of 3D volumetry were compared between the HPM and CPM. In addition, the intermode volume variability (IVV) of 3D volumetry was calculated. RESULTS: In the measurement of the 6-mm and 8-mm nodules, there was no significant difference in RPE (p > 0.05, respectively) between the CPM and HPM (IVVs of 1.2 +/- 0.9%, and 1.7 +/- 1.5%, respectively). In the measurement of the 4-mm nodules, the mean RPE in the HPM (35.1 +/- 7.4%) was significantly greater (p < 0.01) than that in the CPM (18.4 +/- 5.3%), with an IVV of 13.1 +/- 6.6%. However, the IVVs were in an acceptable range (< 25%), regardless of nodule size. CONCLUSION: The accuracy of 3D volumetry with HPM for solid pulmonary nodule is comparable to that with CPM. However, the use of HPM may adversely affect the accuracy of 3D volumetry for smaller (< 5 mm in diameter) nodule.

The arterial blood supply of the temporomandibular joint: an anatomical study and clinical implications

PURPOSE: The aim of this study was to analyze three-dimensional images of the arterial supply to the temporomandibular joint. MATERIALS AND METHODS: Ten patients (five men and five women, mean age 36 years) without signs or symptoms of temporomandibular disorders, who underwent contrast-enhanced computed tomographic (CT) scanning with intravenous contrast, were studied. The direct volume rendering technique of CT images was used, and a data set of images to visualize the vasculature of the human temporomandibular joint in three dimensions was created. After elaboration of the data through post-processing, the arterial supply of the temporomandibular joint was studied. RESULTS: The analysis revealed the superficial temporal artery, the anterior tympanic artery, the deep temporal artery, the auricular posterior artery, the transverse facial artery, the middle meningeal artery, and the maxillary artery with their branches as the main arterial sources for the lateral and medial temporomandibular joint. CONCLUSION: The direct volume rendering technique was found to be successful in the assessment of the arterial supply to the temporomandibular joint. The superficial temporal artery and maxillary artery ran along the lateral and medial sides of the condylar neck, suggesting that these arteries are at increased risk during soft-tissue procedures such as an elective arthroplasty of the temporomandibular joint.