الفهرس 
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Abstract
The present study was designed to compare between Nano Mineral Trioxide Aggregate and Mineral Trioxide Aggregate regarding their apical sealing ability, marginal adaptation and healing potentials when used as root-end filling.
Part I of this study (In-vitro study) was the apical sealing ability and adaptability test. Forty extracted human maxillary incisors with straight roots were used. After root canals preparation and obturation, the apical 3 mm of each root was resected perpendicular to the long axis of the tooth. Root end cavities were prepared to a depth of 3mm parallel to the long axis of the tooth using a diamond-coated ultrasonic retro-tip mounted on an ultrasonic unit. The teeth were randomly divided into two main equal groups of 20 samples each according to the root-end filling material used either MTA or Nano MTA. Ten samples from each group were sectioned longitudinally in to two equal halves to measure the sealing ability and another ten samples from each group were section transversally obtain 1 mm thick section to measure the adaptability of both materials. All samples were photographed under the SEM at three different magnifications (×1000). The gap thickness between the root end filling material and the retro cavity dentine walls were measured at seven selected points at the material-dentine interface in micrometers (µm).
At high magnification, the surface of Nano-MTA appeared homogenous. Almost no voids or cracks could be detected within the material bulk, while the surface of the MTA seemed to be irregular in structure. Presence of few voids and cracks was clearly at certain areas within the bulk of the material.
Nano MTA and MTA showed no statistical significant difference in the gap thickness between dentin-material interface in both longitudinal and transverse sections. Regarding the sealing ability, the mean value in MTA was (3.27±0.77), while the mean in Nano-MTA was (3.15±0.71). Regarding the adaptability, the mean value in MTA was (2.46±0.60), while the mean in Nano-MTA was (2.05±0.712). Both materials showed good sealing ability and good adaptation to the dentinal wall.
In part II of this study (clinical trial), a total of 30 medically free patients in the age range of 20-50 years were selected. Demographic patient data as well as primary detailed history of chief complaint and clinical signs and symptoms were recorded. Inclusion criteria were anterior teeth with necrotic pulps affected by caries or trauma, history of chronic periapical lesion and presence of apical radiolucency.
Endodontic procedures were performed in the involved teeth followed by peri-radicualr surgery. Retro-cavities were prepared followed by the placement of root end filling material either Nano MTA or MTA. Clinical and radiographic post-operative evaluation was done after 1 year using cone beam computed tomography (CBCT). Radiographic healing was assessed by measuring the volumetric changes in periapical bone lesion size after 1 year period. Manual segmentation was chosen on 3D slicer software. Painting option is activated, and lesion was painted by investigator manually starting from when the lesion became first evident in bone. Painting was done in axial, coronal and sagittal plane to ensure that lesion is fully filled by selected color. After that show 3D volume was selected and software calculated volume of the segment that represents lesion volume in mm3.
Based on study findings, the mean value was of volumetric changes in the periapical bone lesions size in (Nano-MTA) is (70.98±4.83), while the mean value was of volumetric changes in the periapical bone lesions size in (MTA) is (68.59±6.18).
There was no statistically significant volumetric changes in periapical bone lesion size between Nano-MTA and MTA groups after 1 year follow up period