Dental Amalgam : Uses, Classification, Advantages and Disadvantages

An amalgam is defined as a special type of alloy in which mercury is one of the components. Dental amalgam is the most widely used filling material for posterior teeth. As one of the oldest restorative material, dental amalgam has evolved over time and has become successful to stand the test of time.
The quantity of mercury has been reduced over time and newer and newer components are incorporated in the alloy powder to reduce the corrosion of dental amalgam in the oral cavity.

HISTORY
Louis Regnart added mercury to the D’Arcet’s Mineral Cement mixture, which was widely used in France then, lowering the temperature required to boil the mixture significantly, and for this became known as the ‘Father of Amalgam’. Early amalgam was made by mixing mercury with the filings of silver coins. Crawcour brothers (from France) introduced the amalgam in the United States of America in 1833 which used to have significant expansion which even caused tooth fractures in some restorations. However, this challenge was overcome when in 1895, GV Black developed a
formula (67% silver, 27% tin, 5% copper, 1% zinc) for modern amalgam alloy. Black’s formula overcame the expansion problems of the existing amalgam formulations.

APPLICATIONS
1. As a permanent filling material for
— Class I and class II cavities, and
— Class V cavities where aesthetics is not important.

2. In combination with retentive pins to restore a crown

3. For making dies

4. In retrograde root canal fillings

5. As a core material.

CLASSIFICATION OF AMALGAM ALLOYS
BASED ON COPPER CONTENT
Low copper alloys: Contain less than 6% copper (conventional alloys)
High copper alloys: Contain between 13-30% copper.

The high copper alloys are further classified as:

• Admixed or dispersion or blended alloys.
• Single composition or unicomposition alloys.

BASED ON ZINC CONTENT

Zinc-containing alloys: Contain more than 0.01% zinc

Zinc-free alloys: Contain less than 0.01% zinc

BASED ON SHAPE OF THE ALLOY PARTICLE
Lathe cut alloys (irregular shape)
Spherical alloys
Spheroidal alloys

BASED ON NUMBER OF ALLOYED METALS
Binary alloys, e.g., silver-tin
Ternary alloys, e.g., silver-tin-copper
Quaternary alloys, e.g., silver-tin-copper-indium.

BASED ON SIZE OF ALLOY
Micro-cut
Macro-cut

ADVANTAGES AND DISADVANTAGES OF AMALGAM  RESTORATIONS
Advantages
1. Reasonably easy to insert.
2. Not overly technique sensitive.
3. Maintains anatomic form well.
4. Has adequate resistance to fracture.
5. After a period of time prevents marginal leakage.

6. Have reasonably long service life.
7. Cheaper than other alternative posterior restorative material like cast gold alloys.

Disadvantages
1. The color does not match tooth structure.
2. They are more brittle and can fracture if incorrectly placed.
3. They are subject to corrosion and galvanic action.
4. They eventually show marginal breakdown.
5. They do not bond to tooth structure.
6. A risk of mercury toxicity.

Oral Pathology Histopathological Diagrams - All in one - Histology made easy

This post contains 33 sorted diagrams of histopathological pictures of pathologies related to oral and maxillofacial regions. From benign to malignant neoplasms of oral cavity, salivary gland tumors, cyst and tumors of jaws and oral cavity, to lesions affecting nerves and muscles and soft tissues, it contains all you need to have a good command in oral pathology. 

These diagrams were drawn with Hematoxylin and Eosin colored Pencils by Raman Dhungel during his Bachelor of Dental Surgery course on third year at B.P. Koirala Institute of Health Sciences, BPKIHS Dharan.  The slides included in this video are: Fibroma, FIbrosarcoma, Papilloma, Verrucous carcinoma, Mild dysplasia, Carcinoma in situ, Squamous cell carcinoma (well differentiated), Neurilemmoma, Neurofibroma, Oral submucous fibrosis, cavernous hemangioma, Lipoma, Lichen planus, malignant melanoma, osteosarcoma, pleomorphic adenoma, warthin's tumor, Adenoid cystic carcinoma, Mucoepidermoid carcinoma, Calcifying epithelial odontogenic tumor, Adenomatoid odontogenic tumor, Keratocystic odontogenic tumor, Dentigerous cyst, Radicular cyst, Plexiform ameloblastoma, Follicular ameloblastoma, Central giant cell granuloma, Peripheral giant cell granuloma, Fibrous dysplasia, Paget's disease of bone, Pemphigus, Pemphigoid (Bullous pemphigoid), and pyogenic granuloma.

Much time and effort was needed to produce this post. We would be gratified to know that if this postbecomes of some help to you. Please share with your friends and students too. 

Behcet's Syndrome

Behçet’s syndrome is a multisystem disease that predominantly affects young males and is
characterized by multiple superficial, painful “aphthous-like ulcers” in the oral cavity.
However to fulfill the criteria of being Behçet’s syndrome, clinically there should be a presence of an aphthous-like ulcer in the oral cavity along with at least two of the following lesions e.g. skin lesion, eye lesion or genital lesion, etc.

ETIOLOGY
Etiology of Behcet’s syndrome is unknown; however, the disease is believed to be caused by
some immunologic abnormality.

CLINICAL FEATURES
Oral lesions: Aphthous-like ulceration in the oral cavity.

Skin lesions: Erythematous macular, papular, vesicular or pustular lesions in the skin; thrombophlebitis may also sometimes develop.

Eye lesions: Ocular lesions in Behçet’s syndrome include uveitis, conjunctivitis, photophobia and retinitis, etc.

Genital lesions: Ulceration in the genitalia, which looks similar to those of the oral cavity.

Other lesions: Behcet’s syndrome sometimes presents some additional features like neural,
vascular, articular, renal or gastrointestinal lesions of various kinds.

HISTOPATHOLOGY
Microscopically the lesions produce similar feature to what is found in a minor aphthous ulcer. However, there can be some additional features like severe vasculitis and vascular damage, etc.

TREATMENT
Behçet’s syndrome is treated by systemic steroid therapy.

Pyogenic Granuloma

Pyogenic granuloma represents an over-exuberant tissue reaction to some known stimuli or injuries. The term pyogenic granuloma is somewhat a misnomer since the condition is not associated with pus formation.

CLINICAL FEATURES
Age: occurs at an early age.
Sex: seen more frequently in females.
Site: mostly occurs in relation to the gingiva, however on rare occasions, other mucosal sites may be involved.

PRESENTATION
• The lesion appears as a small, pedunculated or sessile, painless, soft, lobulated growth on the gingiva

• Labial surface of the gingiva is more frequently affected than the lingual surface.

• The lesion is often ulcerated and bleeds profusely, either upon provocation or spontaneously.

• The ulcerated area of the lesion is often covered by a yellow fibrinous membrane.

• The rate of growth of the lesion is very rapid and its maximum size could be up to 1 cm in
diameter

•Untreated lesion of pyogenic granuloma undergoes fibrosis due to decreased vascularity and in such cases it appears small, firm with little tendency to bleed. This lesion is called “fibroepithelial polyp”

• Similar lesions appearing on the gingival tissue of pregnant women are known as “pregnancy tumor”.

HISTOPATHOLOGY 
• Histologically, the lesion is composed of lobular masses of hyperplastic granulation tissue, containing multiple proliferating fibroblasts, many blood capillaries and a variable number of chronic inflammatory cells.

• The lesion is a vascular one and it occurs due to the proliferation of the endothelial cells.

• The overlying epithelium is thin and ulcerated, and in most of the cases the underlying
connective tissue shows intercellular edema.

• Areas of hemorrhage and hemosiderin pigmentation are often seen within the connective tissue stroma.

TREATMENT
Pyogenic granuloma is treated by surgical excision.