Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Dental Amalgam - Operative Dentistry - Lecture Slides, Slides of Dental surgery

Dental Amalgam, Alloy of Mercury, Dental Filling, Types of Dental Amalgam, Alloy Powder Composition, Amalgam Capsules, Low-Copper Alloys, Composition of Set Amalgam. Exact name of subject is Operative Dentistry. I have 24 lectures, each one has own main topic.

Typology: Slides

2011/2012

Uploaded on 12/13/2012

naseem
naseem 🇮🇳

4.5

(22)

80 documents

1 / 13

Toggle sidebar

Related documents


Partial preview of the text

Download Dental Amalgam - Operative Dentistry - Lecture Slides and more Slides Dental surgery in PDF only on Docsity! Dental Amalgam: Material Properties and its Use in Clinical Dentistry Docsity.com What is Amalgam? a·mal·gam: any alloy of mercury with another metal or other metals [silver amalgam is used as a dental filling]† †Source: Webster’s New World Dictionary of the American Language, Guralnik DB, Ed., New York: World Publishing Co., 1972. Docsity.com Amalgam Capsules • Contain (in separate compartments): – powdered amalgam alloy – liquid mercury • Some are manually activated, others self- activated • Pestle usually included Docsity.com Amalgamator (Triturator) • Speeds vary upward from 3000 rpm • Times vary from 5–20 seconds • Mix powder and liquid components to achieve a pliable mass • Reaction begins after components are mixed Docsity.com Reaction: Low-Copper Alloys Ag3Sn(γ) + Hg → Ag2Hg3(γ1) + Sn7-8Hg(γ2) + Ag3Sn(γ) Docsity.com Properties of Mercury • Only liquid metal at room temperature • Evaporation rate – Theoretical maximum is 57.9 µg·cm2·s–1 from pristine, oxide-free surface into a vacuum (= 57,900 ng·cm2·s–1) – Measured rate in vacuum is ~40 µg·cm2·s–1 (= ~40,000 ng·cm2·s–1) – Oxidation of Hg lowers rate by factor of 1000 Docsity.com Hg Evaporation from Amalgam • Baseline Hg vaporization rate (unstimulated) from amalgam in humans is 0.027 ng·cm2·s–1 • Average vaporization rate (over 24-h period) in humans is 0.048 ng·cm2·s–1 • The evaporation rate of Hg from amalgam is 800–1500 times lower than from oxidized mercury Docsity.com Mercury Dose from Amalgam • Person with average number of fillings (7) would absorb ~1.6 µg/day • Person with a moderately high number of fillings (13) would absorb ~3 µg/day • According to EPA, absorbed dose of mercury from food, water, and air is 5.7 µg/day Docsity.com