You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Evaluation of apical sealing ability and adaptation to dentine of two resin-based sealers . The purpose of this study was to evaluate the apical sealing ability and adaptation to dentine of two resin-based root canal sealers . The root canals of 55 human maxillary anterior teeth were prepared using a step-back technique and the smear layer removed with 17 % ethylenediaminetetraacetic acid . The teeth were divided into two groups of 25 teeth and the remaining five teeth served as control . Then the teeth were prepared and obturated with gutta-percha by a lateral condensation and either AH plus and EndoRez used as a sealer . Twenty teeth from each group were used for the apical leakage test and the remaining five teeth from each group were used for examination under the scanning electron microscope ( SEM ) . For apical leakage test , teeth were covered with nail varnish and sticky wax to within 1 mm of the apical foramen and placed in 2 % methylene blue for 7 days . After this period , the teeth were sectioned longitudinally and apical leakage measurements made . The mean value of dye penetration for AH plus was 2.87 +/- 0.43 mm , while that of EndoRez was 4.54 +/- 0.36 mm . The difference between mean of dye penetration was statistically significant ( P < 0.01 ) . The SEM examination showed both sealers had better adaptation and penetration in coronal and middle thirds than apical third of root canal . In apical third , AH plus was adapted better adpated to dentine than EndoRez . In conclusion , AH plus sealer has better apical sealing ability and adaptation to dentine than EndoRez sealer .
{"Intervention": ["AH plus sealer", "two resin-based sealers", "two resin-based root canal sealers", "teeth were covered with nail varnish and sticky wax to within 1 mm of the apical foramen and placed in 2 % methylene blue for 7 days", "AH plus", "the teeth were sectioned longitudinally", "EndoRez sealer .", "EndoRez", "prepared and obturated with gutta-percha by a lateral condensation"], "Outcome": ["better apical sealing ability", "adaptation and penetration in coronal and middle thirds", "dye penetration for AH plus", "dye penetration"], "Participant": ["55", "root canals"]}