Accuracy of digital dental models using the low-cost DAVID laser scanner.

BACKGROUND: Accurate laser scanning of plaster casts using validated, low-cost hardware represents a key issue in 3D orthodontics. OBJECTIVES: The aim of this study was to compare the accuracy of measurements taken from plaster casts (gold standard) with digital models of those casts created with a low-cost structural light DAVID laser scanner. MATERIAL AND METHODS: Five different measurements were taken on each of 14 plaster casts by 2 independent observers with an electronic caliper. The measurements were repeated 10 times on all 14 plaster casts by each observer, with a 1-week interval between each set of measurements. All 14 plaster casts were digitized using a low-cost DAVID SLS 3 laser scanner. The same 5 measurements were performed on each of the 3D virtual surface models of the 14 plaster casts by 2 independent observers using Meshlab software in a manner similar to that used with the digital caliper. The measurements were repeated 10 times by the 2 observers with 1 week between each set of measurements. RESULTS: The laser-scanned models were more accurate than the plaster cast models in defining measurements based on simple tooth fissures. The accuracy of measurements based on complex tooth fissures were equivalent for the 2 types of model. For measurements based on interproximal dental contacts, the 2 methods of measurement were similar and both were notably poor in terms of accuracy. CONCLUSIONS: Three-dimensional virtual models obtained from the low-cost DAVID laser scanner can be used clinically, but only for certain types of measurements and indications.

Nested PCR for the detection of Aspergillus species in maxillary sinus samples of patients with chronic sinusitis.

BACKGROUND: Fungal rhinosinusitis has become an increasingly recognized disease, being Aspergillus species responsible for most of the cases. Its diagnosis is quite difficult because of the non-specific symptoms and low sensitivity of the current diagnostic methods. AIMS: An Aspergillus-specific nested polymerase chain reaction (PCR) assay using biopsy specimens taken from the maxillary sinuses was performed in order to assess its usefulness. Conventional diagnostic methods (histology and culture) were also carried out. METHODS: A case-control study was performed in the Institute of Stomatology, Jagiellonian University in Kraków, between 2011 and 2014. The case group consisted of 21 patients with suspected rhinosinusal mycetoma while the control group included 46 patients with no suspicion of fungal rhinosinusitis. The two-step PCR assay amplified an Aspergillus specific portion of the 18S rRNA gene. Interval estimation of sensitivity, specificity, positive (PPV) and negative (NPV) predictive values were calculated to assess the diagnostic test performance. The agreement between the PCR and the other tests was evaluated using the Kappa coefficient (k). RESULTS: Ninety percent of the samples obtained from patients diagnosed with mycetoma yielded positive PCR results. The PCR showed almost perfect concordance with histology (k=0.88). Sensitivity, specificity, PPV and NPV estimates were 90%; 95% CI: (55.5-99.7%), 98.3%; 95% CI: (90.9-100%), 90%; 95% CI: (55.5-99.7%) and 98.3%; 95% CI: (90.9-100%), respectively. One clinical sample showed growth of Aspergillus fumigatus and positive PCR despite the negative histological examination. CONCLUSIONS: Nested PCR assay is a promising diagnostic tool to evaluate the presence of Aspergillus in the tissue of maxillary sinus from patients with suspicion of sinus aspergillosis.

Nested PCR for the detection of Aspergillus species in maxillary sinus samples of patients with chronic sinusitis / PCR con cebadores internos para la detección de especies de Aspergillus en muestras de seno maxilar de pacientes con sinusitis crónica

Background: Fungal rhinosinusitis has become an increasingly recognized disease, being Aspergillus species responsible for most of the cases. Its diagnosis is quite difficult because of the non-specific symptoms and low sensitivity of the current diagnostic methods. Aims: An Aspergillus-specific nested polymerase chain reaction (PCR) assay using biopsy specimens taken from the maxillary sinuses was performed in order to assess its usefulness. Conventional diagnostic methods (histology and culture) were also carried out. Methods: A case-control study was performed in the Institute of Stomatology, Jagiellonian University in Kraków, between 2011 and 2014. The case group consisted of 21 patients with suspected rhinosinusal mycetoma while the control group included 46 patients with no suspicion of fungal rhinosinusitis. The two-step PCR assay amplified an Aspergillus specific portion of the 18S rRNA gene. Interval estimation of sensitivity, specificity, positive (PPV) and negative (NPV) predictive values were calculated to assess the diagnostic test performance. The agreement between the PCR and the other tests was evaluated using the Kappa coefficient (k). Results: Ninety percent of the samples obtained from patients diagnosed with mycetoma yielded positive PCR results. The PCR showed almost perfect concordance with histology (k=0.88). Sensitivity, specificity, PPV and NPV estimates were 90%; 95% CI: (55.5-99.7%), 98.3%; 95% CI: (90.9-100%), 90%; 95% CI: (55.5-99.7%) and 98.3%; 95% CI: (90.9-100%), respectively. One clinical sample showed growth of Aspergillus fumigatus and positive PCR despite the negative histological examination. Conclusions: Nested PCR assay is a promising diagnostic tool to evaluate the presence of Aspergillus in the tissue of maxillary sinus from patients with suspicion of sinus aspergillosis

Antecedentes: La rinosinusitis fúngica se ha convertido en una enfermedad cada vez más frecuente y el género Aspergillus es el causante de la mayoría de los casos. Su diagnóstico es relativamente difícil debido a la inespecificidad de los síntomas y a la baja sensibilidad de los métodos de diagnóstico actuales. Objetivos: Evaluar la eficacia de un ensayo de reacción en cadena de la polimerasa (RCP), con cebadores internos y específica de Aspergillus en muestras de biopsia tomadas de los senos maxilares de algunos pacientes, y compararla con la eficacia de los métodos de diagnóstico convencionales (histología y cultivo). Métodos: Se realizó un estudio de casos y controles en el Instituto de Estomatología de la Universidad Jaguelónica de Cracovia entre 2011 y 2014. El grupo de casos estaba formado por 21 pacientes en que se sospechaba rinosinusitis por micetoma mientras que el grupo control estaba compuesto por 46 pacientes sin sospecha de rinosinusitis fúngica. El ensayo de PCR en dos etapas amplificó una porción específica del gen 18S rRNA de Aspergillus. Se obtuvieron estimaciones de la sensibilidad, la especificidad y de los valores predictivos positivo (VPP) y negativo (VPN) para evaluar el rendimiento de la prueba. La concordancia entre la PCR y las otras pruebas realizadas se evaluó utilizando el coeficiente kappa (k). Resultados: El 90% de las muestras obtenidas de pacientes diagnosticados de micetoma mostró resultados positivos en la PCR, con una concordancia casi perfecta de este método con la histología (k=0,88). Las estimaciones de sensibilidad, especificidad, VPP y VPN fueron las siguientes: 90%, IC95% (55,5-99,7%); 98,3%, IC95% (90,9-100%); 90%, IC95% (55,5-99,7%) y 98,3%, IC95%: (90,9-100%), respectivamente. Aspergillus fumigatus se aisló en el cultivo de una muestra clínica, además de obtenerse un resultado positivo por PCR de dicha muestra a pesar de que el examen histológico fue negativo. Conclusiones: El ensayo de PCR con cebadores internos es una herramienta de diagnóstico prometedora para evaluar la existencia de Aspergillus en tejidos del seno maxilar de pacientes en que se sospeche aspergilosis sinusal