Amalgam Part II PDF

Operative dentistry I AMALGAM RESTORATION AND MANIPULATION II Dr.Luluah K. Alhagas Assistant professor in operative dentistry department 2024 Lecture objectives: 1- Identify amalgam cavity preparations. 2- Identify amalgam manipulations. 3- Recognize amalgam saftey precutio...

Operative dentistry I AMALGAM RESTORATION AND MANIPULATION II Dr.Luluah K. Alhagas Assistant professor in operative dentistry department 2024 Lecture objectives: 1- Identify amalgam cavity preparations. 2- Identify amalgam manipulations. 3- Recognize amalgam saftey precutions. Dental amalgam cavity preparation  Medical/ dental history Taking Pre- Chief radiographs operative complaint of the ( OPG,BW,..) patient Assessment Dental screening General requirements: 1- remove defects ( caries, defective restoration,… ). 2- prepration extension on sound enamel. 3- establish 90º cavosurface margin. 4- minimum thickness 1.5-2 mm. 5- prepare undercut form. 6- incorporates any additional preparation features (grooves, slots, pins, cove) Cavity principles: 1-Initial 3- 4-Primary 5-Primary 6- tooth 2-Outline Cavosurface retention resistance Convenience preparation form. margin. form. form. form. depth. 1-Initial tooth preparation depth: pulpal floor depth Central grove DEJ 1-Initial tooth preparation depth: Axial wall depth 2-Outline form/ Cavosurface margin: 3- Retention form: It Prevents dislodgment of restoration along the path of insertion. primary 3- Retention form: secondary Auxiliary means: Lock. Coves. Pins. Slots 4- Resistance form: It Prevents dislodgment of restoration if force applied in apical or oblique direction. Primary: 1- preserving cusps and marginal ridges. 2-having pulpal and gingival walls prepared perpendicular to the occlusal forces. 3-having rounded internal preparation angles. 4-removing unsupported or weakened tooth structure. 4- Resistance form: secondary Auxiliary means: Lock. Coves. Pins. Slots 5- Convenience form: Described as features that make the procedure easier or the area more accessible. Extension of outline form for caries removal, matrix placement, amalgam insertion,… Extension of proximal margin to provide clearance from adjacent tooth. Dental amalgam manipulation  Alloy selection Finishing/ Proportion polishing of the restoration of alloy Carving of Trituration the restoration of alloy Burnishing Condensation of the of amalgam restoration mix Alloy selection: It depends on the case 1- particles shape. 2- copper content. 3- zinc content. Alloy proportion: The amount of mercury needed to coat all alloy particles, to produce homogenous amalgam mixture. Ratio of Alloy/Mercury equel to 1:1 Less mercury Some uncoated particles Dry/friable amalgam mix More Pitting/rough surface Excess mercury Excess 2 Less strength More creep & flow Trituration proportion: Mixing of mercury and alloy particles to produce coherent, plastic and and homogenous mass of condensable amalgam.  Under-trituration Over-trituration under mixing, leading the mixure over mixing, leading the mixure to leave some particle uncoated to have high early strength, and by mercury. fast setting. mixture will look dull,and fraible. mixure will look shiny, and hard. Amalgam carrier Condensation of amalgam mix: 1- Increase adaptation. 2- Allow excess mercury to reach the surface. 3- Increase amalgam density. 4- Increase final strength. Why we need to overfill the cavity 1 mm? Burnishing of amalgam restoration: 1- remove mercurry excess from the surface. 2- guidline for amalgam carving. 3-increase adaptation at restoration margin. What is the direction of burnishing? Carving of amalgam restoration: 1- restore normal anatomy and contour. 2-increase adaptation at restoration margin. What is the direction of carving? Checking occlusion  Checking margin A- FLASH MARGIN: explorer tip catch from tooth to amalgam. B- SUBMARGIN/DITCH: explorer tip catch from amalgam to tooth. C- OPEN MARGIN: explorer tip catch in both directions. Finishing/Polishing of amalgam restoration: 1- reduce plaque retention. 2-reduce tarnish and corrosion. Is it necessary to use coolant with handpiece during finishing? Dental amalgam safety precaution Reference: Sturdevant art and science of operative dentistry Chapter 13 “introduction to amalgam restorations” Chapter 18 “ biomaterials” Thank You