الفهرس 
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Abstract
The aim of the study was to evaluate sealing ability and marginal adaptability of MTA, Nano-MTA and Biodentine different bioceramics as furcation perforation repair materials.
A total of 80 freshly extracted mandibular permanent molars were used in the study. The standard access cavity was made in the Eighty extracted mandibular permanent molar teeth using high-speed handpiece with water coolant. Iatrogenic furcal perforations were made in the center of the pulp chamber floor in seventy teeth.
1) Sealing ability:
Fifty samples were divided into five groups (n=10) according to the type of the repair material used:
• group 1: Perforations were repaired with MTA.
• group 2: Perforation were repaired with Nano-MTA.
• group 3: Perforation were repaired with Biodentine.
• group 4: Perforation were left un repaired (positive control).
• group 5: Without Perforation (negative control).
3 mm from the root end were cut using diamond disc on a straight handpiece. All the canal orifices and root ends were acid etched with 37% phosphoric acid gel (3M ESPE Dental Products, St. Paul, MN, USA) for 30 seconds. Then washed and dried. Two coats of bond (3M ESPE Dental Products, St. Paul, MN, USA) were applied on the teeth and cured using a light curing device for 20 seconds. All the canal orifices and root ends were sealed with FiltekTM Z350 XT flow- able composite (3M ESPE, USA). Two layers of nail varnish was used to coat the entire tooth except the perforation area. A moistened cotton was placed below the furcation perforation to mimic the oral conditions. Then, the perforations were sealed with the three repair materials (MTA, Nano-MTA and Biodentine).
Method of evaluation:
Sealing ability was evaluated using Enterococcus faecalis microbial leakage test.
The bacterial strain was prepared by growing on the brain heart infusion medium for 24 hours at 37O C. Using a sterile disposable micropipette, 100μL of the culture suspension (106 cells/mL) was placed in the pulp chamber of each tooth every 48 hours. All the tested specimens were hanged in a broth until all the furcation area was covered by the medium by using orthodontic wire. The teeth were observed for 45 days for color change and turbidity.
2) Marginal Adaptation:
Thirty samples were divided into three groups according to the type of the repair material used.
All the samples were cut longitudinally in buccolingual direction through the center of the tooth. Diamond disc attached to low-speed straight hand piece was used with water coolant to separate the tooth into two even halves (mesial & distal).
Method of evaluation:
Marginal Adaptation was evaluated under Scanning Electron Microscope.
Results:
Nano-MTA presented the best sealing ability with the least bacterial leakage followed by MTA then Biodentine which showed maximum bacterial leakage.
Nano-MTA presented the best marginal adaptability while MTA showed the least marginal adaptability. There was no significant difference between MTA and Biodentine.