DENTAL
PRODUCTS
Introduction
v The
teeth are accessory digestive organs. People use their teeth to bite and chew
food, the first step in the digestion of food. While we chew food, the tongue
pushes the food to the teeth and saliva helps digestion and wets the food.
v A
number of inorganic compounds are used in maintaining the oral and dental
hygiene.
v Dental
products include
1. Anticaries agents -
fluoride salts
2. Dentifrices or cleaning agents- tooth powders,
tooth pastes, liquid dentifrices
3. Polishing agents- Mouth washes and
rinses
4. Desensitizing agents -Toothache drops,
denture adhesives and denture cleaners
Parts of the Teeth
A typical tooth has three major external regions: the crown, root,
and neck.
1
Enamel: Hard calcified (consists primarily of calcium phosphate and
calcium carbonate) tissue covering dentin of the crown of tooth.
2
Crown: The crown is the visible portion of tooth above the level of the
gums.
3
Gingiva (gums): Soft tissues overlying the crowns of unerupted teeth and
encircling the necks of those that have erupted.
4
Pulp Chamber: The space occupied by the pulp.
5
Neck: The area where the crown joins the root.
6
Dentin: That part of the tooth that is beneath enamel and cementum.
7
Alveolar Bone (jawbone): The part of the jaw that surround the
roots of the teeth.
8
Root Canal: The portion of the pulp cavity inside the root of a tooth; the
chamber within the root of the tooth that contains the pulp.
9
Root: Embeded in the socket are one to three roots.
10
Cementum:Hard connective tissue covering the tooth root, giving attachment
to the periodontal ligament.
11
Periodontal Ligament: A system of collagenous connective tissue fibers
that connect the root of a tooth to its alveolus.
Anticaries Agents
v Dental
caries (i.e. cavities), or tooth decay, involves a gradual demineralization
(softening) of the enamel and dentin.
v If
it is not treated then microorganisms bacterial flora may
invade the pulp, causing inflammation and infection, with subsequent death of
the pulp and root’s apex, requiring root canal therapy.
v Dental
caries are formed by the growth and implantation of cariogenic microorganisms.
Bacteria (streptococcus mutans and lactobacillaceae) produce acids, mostly
lactic acid that demineralize the enamel.
v The
formation of bacterial plaque also helps the decay process by forming pockets
on the tooth surface in which the food particles can stick and be decayed by
the bacteria.
v If
plaque is not removed it calcifies into calculus when calcium salt precipitates
from the saliva. Brushing the teeth helps in removing the material from the
tooth surface before it hardens into calculus.
v Dental
caries can be prevented and oral and dental hygiene can be maintained with the
help of dentifrices.
v
The most accepted approach to prevent caries includes flossing and
brushing accompanied by administration of fluoride either internally or
topically to the teeth.
Examples, Sodium
fluoride, Stannous fluoride, Sodium mono fluoro phosphate.
Role of fluoride in the treatment of
dental caries
v The fluoride ion
is bond with the enamel and make it tough against dental caries, topical
fluorides such as those present in tooth pastes, mouth washes and gels.
v Fluoride
ion is a trace material which occur in our body, obtained from food and water.
v Addition
of fluoride to the water, ie) fluoridation is able to help in reducing and
preventing dental caries. But those who receives slow continued ingestion of
fluoride may suffer from mottling of teeth increased strength of bones, gastric
disturbances, muscular weakness, convulsions and even heart failure.
v Fluoride
in solution or in rapidly soluble salts when administered internally is readily
absorbed from the gastrointestinal tract, partially deposited in the bone or
developing teeth and the remainder gets excreted by the kidneys.
v Fluoride
as it replaces the hydroxyl ion in hydroxyapatite with the fluoride ion to form
fluorapatite in the outer surface of the enamel.
v Fluorapatite
hardens the enamel and makes it more acid resistant. Fluorapatite has also
shown antibacterial activity.
v Fluoride
is most beneficial up to an age of 12 or 13 because unerupted permanent teeth
are mineralizing during that time.
v A small quantity of fluoride (1ppm) is
necessary to prevent caries. If more quantity (2-3ppm) is ingested it is carried to
bones and teeth and gives rise to mottled enamel known as dental fluorosis.
v Fluoride
can also be administered orally as sodium fluoride tablets or drops added in
water or fruit juice.
v It
is not always feasible to administer fluoride internally and in post-adolescent
individuals, it is not beneficial. In such cases, fluoride can be administered
topically. A 2% aqueous solution of sodium fluoride is widely used topically. A
freshly prepared 8% solution of stannous fluoride is also extensively used for
topical application of fluoride.
v Besides
fluorides, Inorganic phosphate salts can also be useful in the prevention of
dental caries. It has been shown that soluble salts of phosphates (e.g.,
calcium sucrose phosphate, sodium dihydrogen phosphate, sodium monohydrogen
phosphate etc.)
1.
Sodium Fluoride: NaF
Mol. Wt. 41.99
v It contains not
less than 98.5 percent and not more than 100.5 percent of NaF, calculated with
reference to the dried substance.
Preparation:
1.
It
is prepared by reacting hydrofluoric acid with sodium carbonate. Sodium
fluoride being not very soluble precipitates out.
2HF
+ Na2CO3 → 2NaF
+ H2O
+ CO2↑
The precipitate is contaminated with
fluorosilicate and the acid salt. It is made alkaline
to phenolphthalein with sodium carbonate and then heated to neutralize the acid salt and decompose the
fluorosilicate.
Na2SiF6 + 2H2O →
2NaF + 4HF + SiO2
2.
It
can also be prepared by reacting calcium fluoride with sodium carbonate.
CaF2 + Na2CO3
-à
2NaF + CaCO3
Properties
v It occurs either
as a white powder or as colourless crystal.
v It is soluble(l
in 25) in water but is practically insoluble in alcohol.
v When a mineral
acid is added, hydrofluoric acid is produced. This is weak acid and is
poisonous.
NaF + HCl -à NaCl + HF
v Since sodium
fluoride is the salt of a weak acid and a strong base, it hydrolyzes in aqueous
solution to give an alkaline reaction.
NaF + H2O à
HF + NaOH
v Calcium chloride
gives a white gelatinous precipitate of CaF2 with fluoride ions. The
precipitate dissolves in ferric chloride solution.
CaCl2 + 2NaF → 2NaCl + CaF2 ↓
v It forms stable
complexes with ferric compounds.
FeCl3 + 6NaF àNa3FeF6+
3NaCl
This
reaction was the basis of an assay method for sodium fluoride. In this method a
neutralized solution of sodium fluoride in a strong alkaline solution was
titrated with a freshly prepared and standardized ferric chloride solution.
Potassium thiocyanate was used as the indicator. End point is the appearance of
a red colour (ferric thiocyanate), Sodium fluoride gives a yellow colour (due
to the formation of a complex with a zirconyl-alizarin red lake.
Test
for purity:It
has to be tested for acidity or alkalinity; fluorosilicate; clarity and colour
of solution; chloride; sulphate and loss on drying.
Assay:
1.
It is assayed by non-aqueous titration
method as per IP.
v
Weigh accurately about 80 mg and add a mixture of 5 ml of acetic
anhydride and 20 ml of anhydrous glacial acetic acid to it. Heat to dissolve,
cool, add 20 ml of dioxan and titrate with 0.1M perchloric acid using crystal
violet solution as indicator until a green colour is produced. Carry out a
blank determination and make any necessary correction.
v
Each ml of 0.1M perchloric acid is equivalent to 0.004199 of NaF
2.
It is also assayed by complexometric
titration method using disodium edentate.
Uses:
It
is used as preventive for dental caries because of its fluoride ion content.
Usual
dose:2.2
mg (equivalent to 1 mg of fluoride ion)
Application:
1.5-3.0
ppm (equivalent to 0.7-1.3 ppm of fluoride ion) in drinking water; topically,
as 2% solution to the teeth.
Formulations:
Sodium
fluoride is administrated as solution, tablet, oral gel for systemic use or as
mouth wash for local use.
Storage. Store
protected from moisture.
Dentifrices or
Cleaning agents
v Dentifrice is a
material which is used for cleaning tooth surfaces and adjacent gums with the
help of tooth brush.
v Dentifrices are
applied as powders or pastes which contains trace materials such as fluoride,
antiseptics, deodorants etc.
v Flavours and
colours are usually added to dentifrices for improving their acceptance.
v A good cleaning
agent must remove stains from teeth and to achieve this suitable abrasiveness
is essential.
v Examples,
Calcium carbonate, Dibasic and tribasic calcium phosphate, Sodium meta
phosphate, Strontium chloride, pumice powder (Complex silicates of aluminium,
potassium and sodium).
Calcium
Carbonate, CaCO3
v It is also
called as precipitated chalk.
v It is a fine
powder used in dentifrices both in powder and paste.
v It gives both
abrasive and antacid effects in mouth.
Preparation
1.
In
nature, it is found in chalk, marble, lime stone, aragonite, calcite, pearls
and shells.
2.
On
commercial scale, it is prepared by mixing the boiling solutions of calcium
chloride and sodium carbonate and allowing the precipitate to settle down. The
ppt is washed with boiling water to remove chlorides and dried.
CaCl2 + Na2CO3
à CaCO3 + 2NaCl
Properties
1.
It
is a white fine, microcrystalline powder.
2.
It
is colourless and tasteless.
3.
It
is insoluble in water and alcohol.
4.
It
neutralizes acid with effervescence.
CaCO3 + 2HCl
à CaCl2
+ CO2 + H2O
Test for purity
It
is tested for Al, Fe, Phosphate, matter insoluble HCl, As, Heavy metals, Cl,
SO4, Ba, soluble alkali and loss on drying.
Assay
It
is assayed by complexometric method.
Medicinal use
It
is used as dentifrices, antacid along with magnesium salt, because it produce
constipation for continuous used as antacid.
Dose : 1-4 g, six
times per day
Storage : stored in
tightly closed containers.
Polishing
Agents
v Dentifrices
contain agents for cleaning tooth surfaces and providing polishing effect on
the cleaned teeth.
v They are
responsible for physically removing plaque and debris.
v The overall
effect provides whiteness to the teeth.
v Many dentifrices
have desensisting agent along with policing agents.
v Examples include
dicalcium phosphate, sodium metaphosphate, calcium pyrophosphate, calcium
carbonate and calcium monohydrogen phosphate.
Desensitizing
Agents
v Desensitizing
agents reduce the pain in sensitive teeth caused by cold, heat or touch.
v These products
should be non-abrasive and should not be used on a regular basis unless
directed by a dentist.
v They act
probably like local anaesthetic.
v Examples include strontium chloride and zinc
chloride.
Oral
antiseptics and Astringent
v Some inorganic
compounds are used as antiseptics in oral cavity.
v For oral hygiene
some products having inorganic chemicals may be used for antiseptic(To destroy
micro organism) and/or astringent action (Precipitate protein)
v Examples-
Hydrogen peroxide, Sodium perborate, Magnesium peroxide.
Mouth Washes
v Mouth washes
having zinc sulphate (for antiseptic and astringent action) or zinc chloride
(for deodorant and Desensitizing acton) or potassium permanganate (for
antiinfective and astringent action) or sodium bicarbonate (fir its antacid
property) or sodium chloride (for irrigation) are generally used in dental for
various reasons.
v Ammoniacal
silver nitrate solution is also used for its astringent action and also
decrease hyper sensitivity of teeth and gums.
Cements and
fillers
v Dental cements
are used to temporarily cover protect areas that have undergone dental surgery.
v The cementing
material is applied as a paste, which get hardened and forming protective
layer. After operation, the cement can be removed.
v The cement is
also medicated with euginol which is antiseptic and local anaesthetic.
v The cement of
suitable consistency used as temporary filler for cavities.
v Some metals like
Gold and Silver are used as permanent filling materials.
Zinc-Eugenol Cement
Preparation: Zinc-Eugenol cement consists of two
parts and is prepared as follows
Part A. The Powder:
Zinc Acetate 0.5
g
Zinc Stearate 1 g
Zinc Oxide 70 g
Rosin 27.5 g
Rosin is powdered and mixed with about an equal weight of zinc
oxide. The mixture is sifted through a sieve of not less than 100–mesh. The
material retained on the sieve is regrinded with additional zinc oxide, and
sifted again. The process of regrinding and sifting is repeated until all of
the material passes readily through the sieve and the two mixtures are then
mixed with the remainder of the zinc oxide.
Part B. The Liquid:
Eugenol 85 ml
Cottonseed Oil 15 ml
The liquids are mixed together in the proportion specified.
Zinc-Eugenol cement is prepared by mixing 10 parts of the powder
with 1 part of the liquid to a thick paste immediately before use. For
obtaining any desired consistency the amount of the liquid may be varied.
Uses:
It is a temporary cement with a zinc oxide eugenol base for crown
and bridge procedures.
It can be used in
dentistry as a filling or cement material.
It is used in
temporary restorations, in managing dental caries as a temporary filling .
It is also used as an
impression material during construction of complete dentures.
Zinc-Eugenol cement has anaesthetic and antimicrobial effect due
to the eugenol content and is used in painful conditions of dental pulp.
