The first air rotary handpiece was
created by Green in 1868 while the modern air turbine handpieces were
presented by Borden during the last century (1957) and could attain very
high speeds [up to 300,000 rpm]. (2) Handpiece is a device that holds
rotary instruments providing power to them to complete the actual cutting
or polishing of tooth structure and castings. It is classified according
to the shape into straight handpiece and contra angle handpiece, according to the
speed into low speed handpiece and high speedhand piece that more effective
than low. (3)
Cutting instruments
desin consists of 3 parts; (1) Shank that fits into handpiece and accepts
rotary motion from handpiece, (2) Neck that connects the shank to the head
and transmit rotational and translation forces to the head, (3) Head that
consider the working part of the instruments and perform the
desiredshaping of tooth structure.
Mouth mirror : The mouth mirror has many uses as allowing the
dentist to see indirectly, to reflect light on desired surfaces, and to
retract tissues such as the tongue or cheeks, to gain better visualization
of the teeth and soft tissue retraction. The mirror head is normally
round, with the most common sizes used being No. 4 Ø (18 mm) and No. 5 (Ø
20 mm).
Intraoral cameras : (IOCs) are cameras used by dentists or doctors
as an alternative to using a mirror to show a patient the inside of their
mouth. in 1989, they were first introduced and are now widely used in
dental offices. IOCs allow the patient to see a clear picture of
the inside of his or her mouth, helping the dentist to consult with them
on different treatment options. Images may be saved for future reference
in a patient's file.
Peridontal probe : Peridontal probe is usually long, thin, and
blunted at the end. it is used to measure the extent of reduction, to
assess the relative parallelism of the alignment grooves with one another
or with the proposed path of placement of a secondary retainer if the
prepared tooth is to serve as a fixed dental prosthesis abutment.
Tweezer : These are used to hold cotton roll,different material and
alse used to transport any material in and out of mouth.
Handpiece : The handpiece considers a key instrument in dentistry
because it is used for a number of functions including cavity preparation,
caries removal, tooth tissue grinding, and restoration finishing and
polishing. the first air rotary handpieces were invented by Green in 1868
and this handpiece was followed by electric handpiece technologies
that introduced in 1873. (2) In the last century (1957) the
first air turbine handpieces were invented by Borden and can reach very
high speeds [up to 300,000 rpm]. High speed dental air turbine handpieces
fostered a revolution and changed dental practice significantly. (2) Air
turbine handpieces became popular and are used actively in clinical
dentistry. high-speed handpieces in north America are utilized for the
majority of clinical procedures including fixed prosthodontics in pre-doctoral
programs. These handpieces are so prevalent because of specific benefits,
including low cost, low weight, ease of repair, rapid cutting of the tooth
structure, and a reduced risk of pulpal damage. While high speed air
turbine handpieces are reliable instruments for cavity preparation
in clinical practice, low speed handpieces are still widely used during
preclinical training to prepare cavities in artificial teeth. (2) Low-speed
air turbine handpieces resemble electric motors; the main disadvantages
are the large size and heavy weight compared to air turbine high-speed
handpieces. The large size of the handpiece head could hinder the operator 's
access and visibility. Additionally, the large size and the high weight
could cause ergonomic problems especially for some operators. High speed
air turbines handpieces cause trauma in teeth structures and minimized
when utilized properly. (2) High-speed handpiece is used for removal
of old or damaged restoration, preparation of outline and retention
grooves for new restoration, reduction of the crown portion of a tooth in
preparation for a crown or bridge, finishing or polishing of restoration,
sectioning of a tooth during surgery. (10) Low speed handpiece is
used for Removal of deep decay and finishing of cavity preparations,Initial
preparation of grooves and pin holes, Finishing and polishing
of restorations, Coronal polishing and removal of stains, Root canal
preparation to receive posts,Trimming and contouring of temporary crowns
and Finishing and polishing of dental castings and restorations. (10)
Dental burs : Dental burs have improved and promoted the dentistry
fields in cutting of the hardest tissues like bones or teeth. They are
normally fabricated from stainless steel, diamond particles and tungsten carbide
and they are fitted to a dental drill incorporating an air turbine. The
dental bur was developed <300 years ago and still widely used. (4) The
dental bur has three parts: the head, the neck, and the shank; The
head contains the blades, which produce cutting action by rotary motion.
The blades are positioned at various degree angles in order to change the
property of the bur.
The laser: The use of lasers in dental treatment often is
complementary to the manufacture of fixed prosthodontics and this can be
their first experience of such devices among many patients. (19) Laser
is categorized by wavelength into : the ultraviolet spectrum range
(about 400 nm), the visible spectrum range (about 400-700 nm) and the
infrared spectrum range (about 700 nm to the microwave spectrum). (20) Laser
has many uses in fixed prosthodontics for example : (A)Crown lengthening:
Lasers have optimum operator control, finely traces the incision lines and
precisely sculpts the gingival margin. For osseous crown lengthening,
Erbium laser treatment shows minimal displacement of the tissue
and isolated papillae is limited for flap preparation if necessary. (21) (B)
Tooth preparation: Er:YAG laser is the treatment of choice for
preparing dental hard tissues. In most instances, the Er:YAG laser numbs
the tooth, so anesthetic is usually not needed. A high-speed handpiece can
lead to microfractures in the enamel while the laser does not present a
risk of microfracture.
(C) Veneer removal: The laser energy
passes through the ceramic glass and is absorbed by the molecules of water
present in the adhesive. De-bonding takes place at the silane – resin
interface. The technique takes approx. Two seconds to 2 minutes
for ceramic restorations, based on the thickness of the ceramic restoration. (20) (D)
E model preparation: 3D laser scanner is a valuable tool for its ease of
use, and no cast preparation is required as e-models are prepared from
scanned impressions. It consists of laser beam (visible light) and
camera-like device that employs triangulation principles.
CAD/CAM technology: In 1989, Mormann & Brandestinni introduced
CAD / CAM technology in dentistry in Germany and is still commonly used in
all branches of prosthodontics. (22) CAD/CAM technology was developed
to solve 3 challenges. The first challenge was to create restorations with
a natural appearance. The second challenge was to ensure adequate strength
of the restoration, especially for posterior teeth. The third challenge
was to make tooth restoration easier, faster, and more effective. In
some cases, CAD/CAM technology provides patients with same-day
restorations. (21) The use of CAD / CAM for dental restoration
technology has many benefits over conventional techniques. These
advantages include No Traditional Impressions, Producing Chair-side
Restorations, Less appointment, High Precision and Accuracy, Improve the
Qualities of Restoration, Removing the Use of Laboratory Equipment Needed
for Conventional LOST-WAX Technique, Speed, Facility of Use and Better Digital
ultrasonic instruments compared with rotary instrument: During
comparison Ultrasonic instruments with the rotation of
conventional instruments, there is found that Ultrasonic instruments have
an oscillating action that has led to their recent adaptation for finish
line preparation in fixed prosthodontics by Sous and colleagues. (24) There
was a better defined axial wall / margin angle and a smoother
marginal surface in the margins finished with the ultrasonic
instruments. (24) Ultrasonic instruments are largely atraumatic to
the adjacent teeth, gingival attachment and pulp. (24) With the
ultrasonic instrument, the margins produced were in a better
condition than those produced with the rotary instrument. Thus, they
rejected the null hypothesis. (24) The surface finished with the
rotary instruments was more than three times rugged than the surface
finished in one dimension with the ultrasonic instruments. (24
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