Sealing effect of GuttaFlow2 in curved root canals / 北京大学学报(医学版)

Objective:To evaluate the sealing ability of GuttaFlow2 single cone obturation in curved root canals.Methods:(1)Slight,moderate and severe curved 3D printed root canals were made.After instrumentation,these samples were randomly divided into 2 groups(n=10)according to different root canal filling techniques:GuttaFlow2 single cone group(GF2)and AH-Plus warm vertical compation group(WVC).All the samples were sectioned at 2 mm to apex(the apical of the root),4 mm,6 mm to apex(the middle of the root)and 8 mm to apex(the coronal of the root).The filling void areas were ob-served by stereomicroscope,and the percentages of void areas in each section were calculated by ImageJ 1.52a.(2)Forty-eight roots of extracted adult molars were selected.After instrumentation,they were randomly divided into 2 groups(n=8):GF2 group and WVC group.Before root canal filling,the sea-lers were mixed with Rhodamine B dye for visualization under confocal laser scanning microscope.All samples were sectioned at 2 mm to apex(the apical of the root),5 mm to apex(the middle of the root)and 8 mm to apex(the coronal of the root).Then,the percentages of sealer penetration into dentinal tu-bules in each section were calculated.Results:At the apical of the root,there were no obvious voids in slight,moderate and severe curved canals in the GF2 group and the WVC group.There was no signifi-cant difference between the two groups(P＞0.05).At the middle of the root,there was no significant difference in the percentages of void areas between the two filling methods,but at the coronal of the root,there were more voids in the slight curved root canal in the GF2 group than in the WVC group,and the difference was significant(P=0.009).The percentages of sealer penetration into dentinal tubules of slight,moderate and severe curved root canals in the GF2 group were 36.10％,55.80％,65.08％,re-spectively.And they were all higher than those in the WVC group(15.78％,20.70％,15.61％),re-spectively,the difference between the two groups was significant(P=0.001).At the middle of the root,the percentages of sealer penetration into dentinal tubules of slight and moderate curved root canals in GF2 group were also significantly higher than those in the WVC group(P=0.001).At the coronal of the root,there was no significant difference between the two groups(P＞0.05).Conclusion:Gutta-Flow2 filling technique has the same sealing effect on the root canal at the apical and middle of the root as the warm vertical technique,but has a better sealing effect on the dentin tubules,especially for severe curved root canal.

Advantages and disadvantages of endocrown restorations of endodontically treated teeth with large coronal destruction / 中华口腔医学杂志

The strength of endodontically treated teeth were reduced apparently because of structural damage, therefore further reduction of healthy tissue should be avoided as much as possible in restoration. Endocrown made by chair-side CAD/CAM is some kind of minimal invasive restoration, and the retention of restoration is achieved by reliable bonding and macromechanial retention forces. Without post preparation, the root structure could be resevered. Following the indications and use of biomechanical dentin-like CAD/CAM materials could reduce the adverse effect of tensile stress on cervical part.

Rapid method of object detection based on color feature / 医疗卫生装备

Object detection systems are widely used in many fields. To speed up object detection, a rapid method based on color feature is presented in this paper. Artificial neural network is used for color classification. A series of original objects are gained through searching the most outstanding feature of the marker based on multi-resolution. A set of features obtained from these original objects in the original image, and artificial neural network are used for object classification. Experimental results prove the effectiveness of this method.

Parsing and encoding of DICOM Nesting Data Set and its application to PACS / 医疗卫生装备

DICOM is a standard for data format and transmission of digital medical image. DICOM Data Set is a binary data stream using DICOM encoding rule. DICOM Nesting Data Set is a kind of complex Data Set with a tree structure, and is widely used in DICOM services and encoding of DICOM files for its special structure. In this article, the functions and encoding rule of Data Set and Nesting Data Set in DICOM format are presented, and the way of parsing and organizing of them is put forward. The realization method and practical application are also discussed.

Research of automatic peripheral white blood cell classification system / 医疗卫生装备

Identification and classification of white blood cells are important for clinical diagnosis.Many researchers have been seeking the effective methods for white blood cells' automatic classification based on morphological characters.After cell segmentation,leukocytes' feature acquirement and selection,this paper accomplishes white blood cells' automatic classification using Sugeno-model fuzzy neural network and compares the result with that from classifier of BP network.