Purpose: to investigate the response of periradicular tissues of monkeys to MTA and amalgam when used as root-end filling materials in teeth in which bacterial contamination of root canals was avoided
• The left and right maxillary central and lateral incisors of three healthy 4-yr-old monkeys
•Intramuscular injection of 0.5 ml Ketamine to anesthetize monkeys then supplemented by intraoral buccal infiltration of 2% lidocaine with epinephrine
•Rubber dam, access opening to expose the pulp, canals were instrumented till size 40, then obturation using lateral condensation and finally amalgam was placed on the access.
•1 week later a full thickness buccal mucoperiosteal flap with two vertical incisions to gain access to the periradicular tissue of maxillary incisors. •Removal of cortical bone and root end cavities were prepared to a depth of 2 mm
•The root end cavities were randomly selected to be filled with zinc-free amalgam and MTA then the flap was sutured and healing took place in all cases after 1 week
•5 months later monkeys were re-anesthetized ,block sections containing incisor teeth and their surrounding tissues were removed and placed in formalin to examine the teeth histologically
•Severity of inflammation: none: no inflammatory cells, mild: few inflammatory cells, moderate: inflammatory cells did not obscure the normal tissues, severe: inflammatory cells replaced normal tissues.
•The extent of inflammation from the surface of root-end filling material was recorded as <= 0.2 mm,<=0.5 mm or<+ •1mm.
•Presence or absence of bacteria within the teeth, fibrous capsule ,cementum deposition on the root end and root end filling materials and new bone formation were recorded
Most highlighted Results :
-A total of 6 amalgam and 6 MTA samples were available for histological examination §Five of six root end filled with MTA showed no PA lesion and cementum layer deposition over the MTA
-All roots with amalgam periradicular tissue has moderate to severe inflammation.
-Cementum formation was observed over the dentinal surface of all root ends but not over the amalgam
-Lympohcytes were the predominant inflammatory cell in the bulk of the lesions §Fibrous capsule was found over most of amalgam root-end fillings. -New bone formation occurred regardless of the type of the root end filling. -No bacteria were observed at the root ends.
Clinical significance :
–MTA showed superior properties than amalgam as root-end filling material