PERSPECTIVE IN DENTISTRY

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Created by
Lauranna Celestine

Cards (195)

  • DENTAL AMALGAM
     It is an alloy made by mixing mercury (Hg) with a silver(Ag) tin (Sn) alloy.
  • Dental amalgam alloy is a silver tin alloy to which varying amount of copper and small amount of zinc has been added.
  • According to Skinner’s, amalgam is a special type of alloy in which one of its constituent is mercury.
  • In dentistry, it is common to use the term amalgam to mean dental amalgam.
  • First used by Chinese.There is a mention of silver mercury paste by Sukung (659AD)in the Chinese medic.
  • In 1578, lshitichenused 100parts if Hg, 45 parts of Ag and 100 part of Sn Hg Ag Sn 100 parts (%) 45 parts (%) 100 parts (%}.
  • LiuWen-Thai (1508)and Li Shih-Chen (1578) discussed its formulation; 100 parts of mercury to 45 parts of silver and900partsoftin, trituration of these ingredients produced a paste said to be as solid as silver. Hg Ag Sn 100 parts (%) 45 parts (%) 900 parts (%}
  • In 1800s, introduced in France an alloy of bismuth (Bi), lead (Pb), tin (Sn) and mercury (Hg) plasticized at 100 “C poured directly into cavity.
  • During 1819 in England, Bell advocated the use of a room temperature mixed amalgam as a restorative material.
  • During 1826 in France, M. Traveau is credited with advocating the first form of amalgam paste.
  • In 1833, Crawcour brothers introduced amalgam to US
  • Powdered silver coins mixed with mercury
  • In 1895, to overcome expansion problems of amalgam, G.V. Black developed a formula:
    67%silver,27%tin, 5%copper ,1%zinc = Ag Sn Cu Zn 67% 27% 5% 1%
  • GV Black’s formula was well accepted and not much changed for nearly sixty years (1890-1963). • In 1946, Skinner added copper (Cu) to the amalgam alloy composition in a small amount.
  • In 1971, Johnson designed a spherical particle alloy with composition of: Ag 64% Sn Cu 26% 10 % • In 1973- First single composition spherical alloy named Tytin (Kerr) a ternary system (silver/tin/copper) was discovered by Kamal Asgar of the University of Michigan
  • During 1980’s, alloys similar to Dispersalloy and Tytin was introduced.
  • DENTAL AMALGAM: Advantages
     Ease of use
     Easy to manipulate
     Relatively inexpensive
     Excellent wear resistance
     Restoration is completed within one sitting without requiring much chair side time.
     Well condensed and triturated amalgam has good compressive strength.
     Sealing ability improves with age by formation of corrosion products at tooth amalgam interface.
     Relatively not technique sensitive.
     Bonded amalgams have “bonding benefits”.
     Less micro leakage
     Slightly increased strength of remaining tooth structure.
     Minimal postoperative sensitivity.
  • DENTAL AMALGAM: Disadvantages
    Unnatural appearance (non-esthetic)
     Tarnish and corrosion
    Metallic taste and galvanic shock
     Discoloration of tooth structure
     Lack of chemical or mechanical adhesion to the tooth structure
    Mercury toxicity
     Promotes plaque adhesion
     Delayed expansion
     Weakens tooth structure (unless bonded)
  • G.V. Black’s: Silver- Tin Alloy or Low CopperAlloy
  • Low copper alloys are available as comminuted particles (Lathe-cut and Pulverized) and spherical particles.
  • Low copper composition:
    Silver : 63-70%
    Tin : 26-28%Copper : 2- 5%
    Zinc : 0-2%
  • SILVER (Ag)
     Constitutes approximately 2/3rd of conventional amalgam alloy.
     Contributes to strength of finished amalgam restoration.
     Decreases flow and creep of amalgam.
     Increases expansion on setting and offers resistance to tarnish.
     To some extent it regulates the setting time
  • TIN (Sn):
     Second largest component and contributes ¼ of amalgam alloy.
     Readily combines with mercury to form gama-2 phase, which is the weakest phase and contributes to failure of amalgam restoration.
     Reduce the expansion but at the same time decreases the strength of amalgam.
     Increase the flow.
     Controls the reaction between silver and mercury.
     Tin reduces both the rate of the reaction and the expansion to optimal values.
  • COPPER (Cu):
     Contributes mainly hardness and strength.
     Tends to decrea
  • ZINC (Zn):
     Acts as Scavenger of foreign substances such as oxides.
     Helps in decreasing marginal failure.
     The most serious problem with zinc is delayed expansion, because of which zinc free alloys are preferred now a days.
  • INDIUM (In)/PALLADIUM (Pd):
     They help to increase the plasticity and the resistance to deformation.
  • Amalgam Wars
    In 1845, American Society of Dental Surgeons condemned the use of all filling material other than gold as toxic, thereby igniting "first amalgam war'. The society went further and requested members to sign a pledge refusing to use amalgam.
  • In mid-1920's a German dentist, Professor A. Stock started the so called "second amalgam war". He claimed to have evidence showing that mercury could be absorbed from dental amalgam, which leads to serious health problems. He also expressed concerns over health of dentists, stating that nearly all dentists had excess mercury in their urine.
  • "Third Amalgam War' began in 1980 primarily through the seminars and writings of Dr. Huggins, a practicing dentist in Colorado.
  • Professor A. Stock
    He was convinced that mercury released from dental amalgam was responsible for human diseases affecting the cardiovascular system and nervous system.
  • Professor A. Stock
    Also stated that patients claimed recoveries from multiple sclerosis, Alzheimer’s disease and other diseases as a result of removing their dental amalgam fillings.
  • DENTAL RADIOGRAPHY
    It is a radiographic procedure that is used or employed to take images of the teeth, bones, and soft tissues around them, in order to identify, diagnose, plan treatments and monitor both treatments and lesion development.
  • The Radiographers practicing dental radiography are called Dental Radiographers and provide dental images/radiographs for the dentist.
  • he first dental clinic was established by Dr. C.E. Kells in July 1896,using Xray machine.
  • DENTAL RADIOGRAPHY: Purpose
     To detect pathology associated with teeth and their supporting structures, such as caries, periodontal disease and periapical pathology.
     To detect anomalies/injuries associated with the teeth, their supporting structures, the maxilla and the mandible.
     To determine the presence/absence of teeth and to localize unerupted teeth.
     To measure the length of the roots of teeth before endodontic therapy.
  • DENTAL RADIOGRAPHY: Purpose
     To detect the presence/absence of radiopaque salivary calculi and foreign bodies.
     To detect anomalies/injuries/pathology of adjacent facial structures.
     To evaluate skeletal and/or soft tissues before orthodontic treatment.
     To monitor the progression of orthodontic treatment and dental disease.
  • DENTAL AMALGAM: PURPOSE
    To enable a preoperative assessment of skeletal and soft tissue patterns before orthographic surgery.
     To assess bony healing and effectiveness of surgical treatment of the patient postoperatively.
  • DENTAL RADIOGRAPHY: Types:
    Bitewing, periapical, occlusal
  • Extra-Oral Radiography:
     Panoramic radiography
     Oblique lateral radiography
     Cephalometric radiography
     Cone-beam CT(CBCT)
  • Intra-Oral Radiography: Bitewing
     INDICATION: Detection or monitoring of interproximal caries if the surface is cannot visually examined
     Occlusal caries
    Crestal alveolar bone level
    Caries and restoration proximity to pulp spaces
     Primary molar furcation pathology
     Developmental anomalies