Tuesday, September 13, 2011

Equipments, Instruments and Materials used in Oral Surgery (Armamentarium)

This Post describes the necessary armamentarium,that is equipment and instruments, as well as the rest of the materials the dentist may use in oral surgery.

Surgical Unit and Handpiece

The surgical unit includes the following:
Surgical micromotor. This is a simple machine with quite satisfactory cutting ability. Technologically advanced machines, which function with nitrous dioxide or electricity and have a much greater cutting ability than the afore mentioned micromotor.
The surgical hand piece is attached to the above unit, includes many types, and is manufactured to suit the needs of oral surgery. Its advantages are as
follows:
·         It functions at high speeds and has great cutting ability.
·         It does not emit air into the surgical field.
·         Itmay be sterilized in the autoclave.
·         The handpiece may receive various cutting instruments.


Electric surgical micromotor with adjustable speed

High-speed surgical handpiece

Bone Burs
The burs used for the removal of bone are the round bur and fissure bur. A large bone bur similar to an acrylic burmay be usedwhen the surgical procedure involves greater bone surface area (torus) or smoothing of bone edges of the wound.

Scalpel (Handle and Blade)
Handle. Themost commonly used handle in oral surgery is the Bard–Parker no. 3. Its tip may receive different types of blades.

Blade. Blades are disposable and are of three different types (nos. 11, 12, and 15). The most common type of blade is no. 15, which is used for flaps and incisions on edentulous alveolar ridges. Blade no. 12 is indicated for incisions in the gingival sulcus and incisions posterior to the teeth, especially in the maxillary tuberosity area. Blade no. 11 is used for small incisions, such as those used for incising abscesses. The scalpel

Various types of surgical burs

Scalpel and various types of scalpel blades (nos. 11, 12, 15) commonly used in oral surgery

Correct way to load the scalpel blade on the handle of the scalpel

Sliding of scalpel blade, with the male portion of the fitting facing upward, with the aid of a hemostat

blade is placed on the handle with the help of a needle holder, or hemostat, with which it slides into the slotted receiver with the beveled end parallel to that of the handle. The scalpel is held in a pen grasp and its cutting edge faces the surface of the skin or mucosa that is to be incised.

Scalpel is held in a pen grasp

Periosteal Elevator
This instrument has many different types of end. The most commonly used periosteal elevator in intraoral surgery is the no.9 Molt, which has two different ends: a pointed end, used for elevating the interdental papillae of the gingiva, and a broad end, which facilitates elevating the muco periosteum from the bone. The Freer elevator is used for reflecting the gingiva surrounding the tooth before extraction. This instrument is considered suitable, compared to standard elevators, because it is easy to use and has thin anatomic ends. The elevator may also be used for holding the flap after reflecting, facilitating manipulations during the surgical procedure. The Seldin elevator is considered most suitable for this purpose.

Hemostats
The hemostats used in oral surgery are either straight or curved. The most commonly used hemostat is the curved mosquito type or micro-Halsted hemostat, which has relatively small and narrow beaks so that they may grasp the vessel and stop bleeding. Hemostats may also be used for firmly holding soft tissue, facilitating manipulations for its removal.

Various types of periosteal elevators. a Seldin. b Freer. cNo. 9 Molt

Micro-Halsted hemostats. a Straight. b Curved

Surgical forceps. a Standard. b Adson tissue forceps

Anatomic dissecting forceps. a Standard. b Adson dissecting forceps

Surgical – Anatomic Forceps
Surgical forceps are used for suturing the wound, firmly grasping the tissues while the needle is passed. There are two types of forceps: the long standard surgical forceps, used in posterior areas, and the small, narrow Adson forceps,used in anterior areas.
The beak of the forceps has a wedge-shaped projection or tooth onone side, and a receptor on the other,which fit into each other when the handles are locked. This mechanism allows the forceps to grasp the soft tissues found between the beaks very tightly. Anatomic forceps do not have a wedge-shaped projection, but parallel grooves. This type of forceps is used to aid in the suturing of thewound, as well as grasping small instruments, etc., during the surgical procedure.

Rongeur Forceps
This instrument is used during intraoral surgery as well as afterwards, to remove bone and sharp bone spicules. The ends and sides of the sharp blades become narrow, so that when the handles are pressed, they cut the bone found in between without exerting particular pressure.There is a spring between the handles, which restores the handles to their original position every time pressure is applied for cutting bone. Themost practical rongeur in oral surgery is the Luer– Friedmann, because its blades are both end-cutting and side-cutting.

Bone File
This instrument has two ends: one small end and another with a large surface. The cutting surface is made up of many small parallel blades, which are set in such a way that only pulling is effective. The bone file is used in oral surgery to smooth bone and not to remove large pieces of bone.

Luer–Friedmann rongeur forceps with side-cutting/end-cutting edge

Double-ended bone file with small and large ends

Surgical mallet and chisels. a Partsch monobevel chisel. b Lucas chisel with concave end. c Lambotte bibevel chisel

Chisel and Mallet
Mallets are instruments with heavy-weighted ends. The surfaces of the ends are made of lead or of plastic so that some of the shock is absorbed when the mallet strikes the chisel. The chisels used in oral surgery have different shapes and sizes. Their cutting edges are concave, monobeveled or bibeveled. The bibevel chisel is used for sectioning multi-rooted teeth.

Needle Holders
Needle holders are used for suturing the wound. The Mayo–Hegar and Mathieu needle holders are considered suitable for this purpose. The first type looks similar to a hemostat and is preferred mainly for intraoral placement of sutures. The hemostat and needle holder have the following differences:

·         The short beaks of the hemostat are thinner and longer compared to those of the needle holder.
·         On the needle holder, the internal surface of the short beaks is grooved and crosshatched, permitting a firmand stable grasp of the needle, while the short beaks of the hemostat have parallel grooves which are perpendicular to the long axis ofthe instrument.
·         The needle holder can release the needle with simple pressure, because of the gap in the last step of the locking handle, whereas the hemostat requires a special maneuver, because it does not have that gap in the last step of the locking handle.

Needle holders. a Mayo–Hegar needle holder. b Mathieu needle holder

Beak of the needle holder grasps a suture needle. The needle holder’s beak face is crosshatched, ensuring stability of the needle during tissue penetration


Correct position of the fingers for holding the needle holder

Standard suture scissors. bGoldman–Fox soft tissue scissors

a Blunt-nosed Metzenbaum soft tissue scissors. b Lagrange soft tissue scissors
The correct way to hold the needle holder is to place the thumb in one ring of the handle and the ring finger in the other. The rest of the fingers are curved around the outside of the rings, while the fingertip of the index finger is placed on the hinge or a little further up, for better control of the instrument.

Scissors
Various types of scissors are used in oral surgery, depending on the surgical procedure. They belong to the following categories: suture scissors and soft tissue scissors. The most commonly used scissors for cutting sutures have sharp cutting edges, while Goldman–Fox, Lagrange (which have slightly upward curved blades), and Metzenbaum are used for soft tissue. Lagrange scissors are narrow scissors with sharp blades and are mainly used for removing excess gingival tissue, while theMetzenbaumare blunt-nosed scissors and are suitable for dissecting and undermining the mucosa from the underlying soft tissues. Scissors are held the same way as needle holders.
 Correct way to hold scissors


Towel clamps

Towel Clamps
Towel clamps are mainly used for fastening sterile towels and drapes placed on the patient’s head and chest, as well as for securing the surgical suction tube and the tube connected to the handpiece with the sterile drape covering the patient’s chest.
 Farabeuf retractors for retraction of the cheek and mucoperiosteal flap
 Kocher–Langenbeck retractors, used in the sameway as Farabeuf retractors
Minnesota retractors for retraction of the cheek and tongue

Retractors
Retractors are used to retract the cheeks and mucoperiosteal flap during the surgical procedure. The most commonly used retractors are Farabeuf, Kocher–Langenbeck, and Minnesota retractors. Tongue retractors may be used to retract the tongue medially away from the surgical field, facilitating manipulations
 Weider retractor for retraction of tongue to the side during surgical procedure
Rubber bite blocks for adults (a) and for children (b)
 Side action adjustable mouth props

Bite Blocks and Mouth Props
These instruments facilitate opening and keeping the mouth openwhen the surgical procedure requires this for prolonged periods and when patients cannot fully cooperate with the dentist. The types usually used are rubber bite block, and the side action adjustable mouth prop.

a Fergusson suction tip with wire stylet used as a cleaning instrument. b Disposable suction tip
a Special irrigation system for irrigating the surgical field with a steady stream of saline solution. b Regular plastic syringe used for the same purpose

Surgical Suction
There are a variety of designs and sizes of surgical suctions that are used for removing blood, saliva, and saline solution from the surgical field. Certain types of surgical suctions are designed so that they have several orifices, preventing injury to soft tissues (greatest danger for sublingual mucosa) during the surgical procedure. The standard surgical suction has a main orifice for suctioning and only one smaller orifice on the handle, for the reasons mentioned above. This orifice is usually covered when rapid suctioning of blood and saline solution from the surgical field is required.

Irrigation Instruments
Irrigating the surgical field with saline solution during bone removal is necessary and a plastic syringe or a special irrigation system with a steady stream of saline solution may be used for this purpose. In the first case, the syringe used is large, with a blunt needle that is angled (facilitating irrigation especially in posterior areas) with its end cut off so that it does not damage soft tissues. In the second case, the special irrigation system is directly connected to the bottle of saline solution, with a small tube. A knob stops the flow of solution.

Electrosurgical Unit
This is an electrical device, providing high-frequency radio waves for cauterization (hemostasis) of the vessels and incision of tissues. Incising tissues with the help of electricity is called electrosurgery. The main parts of the electrosurgical unit are:
The active electrode, to which the handpiece is usually connected. The end of the handpiece receives a metallic electrosurgical tip for incision or an electrosurgical ball for hemostasis. There are other designs of electrodes as well, such as loops and needles, which may be used according to the needs of the surgical procedure.
The passive electrode, or ground plate, which is a separate electrode connected to the metallic plate, sized 30 - 20 cm. The metallic plate is placed in direct contact with the naked skin of the patient and is necessary for his or her safety.
Foot pedal. This usually includes a separate switch for incising tissue and another one for electrocoagulation (hemostasis). On certain units, the handle of the positive cable controls this function.
Switches. The main switches are: cauterization switch, voltage switch, switch for incising tissue, and a mixed switch for cauterization and incision. The last switch is found only on more modern units and is very useful, because the surgeon may alternately incise and cauterize, so that turning the switch back and forth from one function to the other is avoided. There are also small portable electrosurgical units that are battery-operated and simple to use. They may be disposable or used more than once, depending on the model.

Electrosurgical unit with various handpieces


Portable electrosurgical units. a Disposable. b Unit that may be used many times

Binocular Loupes with Light Source
This system is comprised of binocular loupes, which may be adapted to eyeglass frames or a headband, en- suring good vision of the surgical field. This system also has a light source that projects intense light into difficult areas of the surgical field (e.g., posterior teeth), where vision by means of standard lighting is not satisfactory.

Binocular loupes with light source, adapted to a headband

Binocular loupes with light source, adapted to eyeglass frames

Maxillary extraction forceps used for the six anterior teeth of the maxilla (superior and side view)

Extraction Forceps
The simple intra-alveolar extraction is accomplished with the help of extraction forceps and elevators. Each extraction forceps is composed of two parts, which are crossed in such a way that they make up one instrument when used to extract a tooth. The basic components of the extraction forceps are the handle, which is above the hinge, and the beaks, which are below the hinge. The instrument is held in the hand by the handle, upon which pressure is exerted during the extraction. The beaks are the functional component of the forceps and grasp the tooth at the cervical region and remove it fromthe alveolar socket. Because tooth anatomy varies, extraction forceps with specially designed beaks have been manufactured, so that they may be used for specific teeth. So, according to the size and shape of the handles and beaks, the following types exist.

Maxillary Extraction Forceps for the Six Anterior Teeth of the Maxilla.
Beaks that are found on the same level as the handles characterize these forceps, and the beaks are concave and not pointed.
 Maxillary universal forceps or no. 150 forceps (mainly used for upper premolars)

Maxillary right molar forceps, for the first and second upper molars of the right side
Maxillary left molar forceps, for the first and second upper molars of the left side

Maxillary Universal Forceps or No. 150 Forceps.
The forceps used for premolars have a slightly curved shape and look like an“S.” Holding the forceps in the hand, the concave part of the curved part of the handle faces the palm,while the concave part of the beaks is turned upwards. The ends of the beaks of the forceps are concave and are not pointed. These forceps may also be used for extraction of the six anterior teeth of the upper jaw.

Maxillary Molar Forceps, for the First and Second Molar.
There are two of these forceps: one for the left and one for the right side. Just like the previouslymentioned forceps, they have a slightly curved shape that looks like an “S” . The buccal beak of each forceps has a pointed design, which fits into the buccal bifurcation of the two buccal roots, while the palatal beak is concave and fits into the convex surface of the palatal root.

Maxillary third molar forceps
Maxillary root tip forceps


Maxillary Third Molar Forceps.
These forceps have a slightly curved shape, just like the aforementioned forceps, and are the longest forceps, due to the posterior position of the third molar. Because this tooth varies in shape and size, the beaks of the forceps are concave and smooth (without pointed ends), so that these forceps may be used for extraction of both the left and right thirdmolar of the upper jaw.

Maxillary Cowhorn Molar Forceps.
The upper cowhorn forceps are a variation of the maxillary molar forceps. The beaks of this type of forceps have sharply pointed ends, which fit into the trifurcation of the roots of the molars. They are primarily used for extraction of teeth with severely decayed crowns, because when they are used to extract intact teeth, they may fracture the buccal alveolar bone due to the large amount of force they generate.

Maxillary Root Tip Forceps.
The handles of the root tip forceps are straight, while the beaks are narrow and angle-shaped. The ends of the beaks are concave and without a pointed design.


Mandibular Forceps for Anterior Teeth and Premolars or Mandibular Universal Forceps or No. 151 Forceps.
 Unlike the maxillary forceps, the beaks and handles of these forceps face the same direction, creating an arch.When the forceps are held in the hand, the concave part of the arch of the handles faces the palm, while the beaks obviously face downward. The ends of the beaks are concave,withoutpointedends. The no. 151 forceps are used for extraction of the six anterior teeth and the four premolars of the lower jaw.

Mandibular Molar Forceps.
These forceps are used for both sides of the jaw and have straight handles while the beaks are curved at approximately a right angle compared to the handles. Both beaks of the forceps have pointed ends, which fit into the bifurcation of the roots buccally and lingually. These forceps are used for the removal of both the first and second molar of the right and left side of the lower jaw.
Mandibular forceps for anterior teeth and premolars of the mandible or mandibular universal forceps or no. 151 forceps

Mandibular molar forceps

Mandibular third molar forceps

Mandibular Third Molar Forceps.
These forceps also have straight handles, while the beaks, just like those of the first and second molar forceps, are curved at a right angle compared to the handles. The beaks are a little longer compared to the previous forceps, due to the posterior position of the third molar in the dental arch. Because this tooth varies in size and shape and because there is usually no root bifurcation, the ends of the beaks of the forceps are concave without a pointed design.
Mandibular Cowhorn Molar Forceps.
The lower cow horn forceps or no. 23 forceps are a variation of the mandibular molar forceps. In comparison to the standard forceps, the beaks have a semicircular shape with sharply pointed ends so that they can fit into the bifurcation of the roots and firmly grasp the tooth. Owing to the function of these forceps, tooth extraction may be achieved quite easily as long as the roots are not curved. With the beaks of the forceps grasping the crown of the molar and the

Mandibular cowhorn molar forceps for sectioning roots. They are used for extracting molars with intact crowns, and also when only sectioning of roots is necessary
Mandibular cowhorn forceps adapted to molars

English-style forceps with the hinge in the vertical direction
sharp ends fitting into the root bifurcation, the surgeon squeezes the handles and, using small buccolingual movements, slides the tooth out of the socket. Also, the cowhorn forceps are very useful for sectioning roots of posterior teeth in the lower jaw, when their crowns are severely decayed. After grasping the roots, the teeth are easily sectioned after applying pressure at the bifurcation point.

Vertical Hinge Forceps.
These English-style forceps differ from the aforementioned forceps in that their hinges have a vertical direction. Their use is limited, because large amounts of force can be generated during extraction with this type of forceps, so that if the bone is not elastic, there is increased risk of fracture of the alveolar bone.
Mandibular root tip forceps

Mandibular Root Tip Forceps.
The handles of the root tip forceps are straight,while the beaks are curved at a right angle. Their ends are very narrow and meet at the tip when the forceps are closed.

Elevators
The elevator is the second most important instrument (after the extraction forceps) with which tooth extraction is achieved or aided. It is composed of three parts: the handle, the shank, and the blade. The shape of blade differs for each elevator type, and each is used as the need dictates. There are three main types of elevators used today in oral surgery: the straight elevator, the pair of elevators with T-shaped or crossbar handles, and the pair of double-angled elevators.

Straight Elevator.
This is the most commonly used type of elevator for the removal of teeth and roots, in both the upper and lower jaws. As already mentioned, the elevator’s components are the handle, shank, and blade. The handle is pear-shaped, and big enough to be held comfortably in the hand for the surgeon to apply pressure to the tooth to be luxated. The shank is narrow and long and connects the handle to the blade. The blade has two surfaces: a convex and a concave one. The concave surface is placed buccally, either perpendicular to the tooth or at an angle, and always in contact with the tooth to be luxated. The elevator is held in the dominant hand, and the index finger is placed along the blade almost reaching its end. The end of the blade is left exposed and is seated between the socket and the tooth to be luxated.

Pair of Elevators with T-shaped or Crossbar Handles.
This type of elevator  is used only in the lower jaw for removal of a root of a molar, after the other root has already been removed with the straight elevator. Each of these elevators is composed of the handle, shank, and blade. The shank is connected to themiddle of the handle, giving the elevator a T-shaped appearance, while the connection of the shank to the blade is angled, and the blade end is sharp-tipped. The blades on this pair of elevators face in opposite directions, and the appropriate one is used according to the root that has to be removed. One elevator is used to remove the mesial root, and the other for the distal root, for each side of the lower jaw. Angled Seldin elevators are a variation of the elevators with T-shaped handles.
In certain cases, the T-shaped elevator may be used to remove a whole thirdmolar of the lower jaw. The tip of the elevator is placed into the root bifurcation buccal to the tooth, using the external oblique ridge as a fulcrum.

Pair of Double-Angled Elevators.
Double-angled elevators are mainly used to remove root tips in both jaws. They are also very useful instruments for the extraction of impacted third molars of the upper jaw. Their handle is similar to that of the straight elevator. The shank has a double angle, so that the instrument may enter the socket, and the two elevators face in opposite directions. The blade has a convex and concave surface, ending in a sharp point. There are also double-angled elevators with narrow blades and very sharp ends, which may easily remove small broken root tips.

Straight Bein elevator

StraightWhite elevator with slightly curved blade, suitable for extracting posterior maxillary teeth

 Pair of elevators with crossbar or T-shaped handles

Pair of angled Seldin elevators suitable for extracting roots in the mandible

Pair of double-angled elevators

Chompret elevators; a straight, and b curved

Sharp-tipped angled elevators suitable for removal of root tips

Other Types of Elevators

Straight Chompret Elevator.
The narrow blade of this instrument means that this type of elevator may also be used as a straight elevator. The straight Chompret elevator may only be used this way when the width of the straight elevator blade prevents its correct placement for the luxation of the tooth or root.

Curved Chompret Elevator and Doubleangled Elevators with Narrow Blades and Sharp Tipped Ends.
These instruments are used by the dentist as the need dictates.

a Special instrument for removing roots belowthe margin of alveolar bone. b Bur for widening the root canal

Periapical curettes with ends of different sizes

Desmotomes. a Straight. b Curved

Special Instrument for Removal of Roots
The instrument in is used to remove broken roots found below the alveolar crest. The spiral end of the instrument is placed inside the extraction socket, and, after screwing the instrument into the root canal of the broken root, traction is used to remove the root from the socket.

Periapical Curettes
These are angled double-ended, spoon-shaped instruments. The most commonly such used instrument is the periapical curette, whose shape facilitates its entry into bone defects and extraction sockets. The main use of this instrument is the removal of granulation tissue, small cysts, bone chips, foreign bodies, etc.

Desmotomes
These instruments are used to sever the soft tissue attachment, and are either straight or curved. The straight desmotome is used for the anterior teeth of the upper jawand the curved desmotome for the rest of the teeth of the upper jaw as well as all of the teeth of the lower jaw.

Set of instruments necessary for simple tooth extraction

Set of instruments necessary for surgical tooth extraction

Sets of Necessary Instruments
For practical reasons, sterilized and packaged full sets of instruments for the most common surgical procedures must always be available. These sets include:
a. Set for simple tooth extraction:
1. Local anesthesia syringe, needle, and ampule.
2. Desmotome or Freer elevator.
3. Retractor or mouth mirror.
4. Extraction forceps
(depending on the tooth to be removed).
5. Surgical or anatomic forceps.
6. Elevators.
7. Sterile gauze.
8. Periapical curette.
9. Suction tip.
10. Towel clamp.
11. Needle holder.
b. Set for surgical tooth extraction:
1. Local anesthesia syringe, needle, and ampule.
2. Scalpel and blade.
3. Periosteal elevators.
4. Elevators.
5. Bone chisel.
6. Mallet.
7. Rongeur forceps.
8. Bone file.
9. Periapical curette.
10. Bone burs.
11. Hemostat

Set of instruments necessary for soft tissue specimen sampling by biopsy

Set of instruments necessary for incision and drainage of abscesses
12. Retractors.
13. Needle holder.
14. Surgical forceps and anatomic forceps.
15. Scissors.
16. Towel clamps.
17. Disposable plastic syringe.
18. Suction tip.
19. Straight handpiece.
20. Bowl for saline solution.
21. Sutures.
22. Sterile gauze.
c. Set of instruments for surgical biopsy (bone and soft tissue) :
1. Local anesthesia syringe, needle, and ampule.
2. Scalpel and blade.
3. Periosteal elevator.
4. Scissors.
5. Surgical forceps and anatomic forceps.
6. Periapical curette.
7. Needle holder.
8. Hemostats.
9. Rongeur forceps.
10. Towel clamps.
11. Suction tip.
12. Sutures.
13. Sterile gauze.
14. Retractors.
d. Set of instruments for incision and drainage of abscess :
1. Local anesthesia syringe, needle, and ampule.
2. Scalpel and blade.
3. Hemostats.
4. Surgical and anatomic forceps.
5. Scissors.
6. Needle holder.
7. Suction tip.
8. Towel clamps.
9. Sutures.
10. Sterilized Penrose rubber drain 1/4 in.
11. Sterile gauze.


Different types of resorbable sutures made fromgut tissue and synthetic material

Sutures
Great progress in sutures has been made since 1865, when disinfection and sterilization first started being used in surgery. There is a big variety in the size of  surgical sutures available today, and two basic categories: (1) resorbable, and (2) nonresorbable sutures.

Resorbable Sutures.
These sutures are resorbed after a certain time, which usually coincideswith healing of the wound. These sutures are made of gut or vital tissue (catgut, collagen, fascia, etc.) and are plain or chromic, or of synthetic material, e.g., polyglycolic acid (Dexon) . Plain catgut sutures are resorbed postsurgically over 8 days, chromic sutures in 12– 15 days,and synthetic (Dexon) sutures in approximately 30days. These types of sutures are used for flaps with little tension, children, mentally handicapped patients, and generally for patients who cannot return to the clinic to have the sutures removed.

Nonresorbable Sutures.
These sutures remain in the tissues and are not resorbed, but have to be cut and removed about 7 days after their placement. They are fabricated of various natural materials, mainly surgical silk (monofilamentous or multifilamentous, in many diameters and lengths) and surgical cotton suture. Silk sutures are the easiest to use and the most economical, and have a satisfactory ability to hold a knot. The most commonly used suture sizes are 4–0 and 3–0 for resorbable sutures, and 3–0 and 2–0 for nonresorbable sutures. These kinds of sutures are sold in sterilized packages with pre-attached atraumatic needles or in bundles without needles.

Nonresorbable surgical sutures made of silk

Cross-sectional view of needles. a Round tapered (1), oval tapered (2), cutting (3, triangular with one of the three cutting edges on the inside of the semicircle), reverse-cutting (4, triangular with two cutting edges on the inside of the semi-circle). b Size of needle compared to regular circle: one-quarter of a circle (1), three-eighths of a circle (2), half a circle (3), three-quarters of a circle (4)

Needles
A variety of needles are available in oral surgery, and they may differ in shape, diameter, cross-sectional view, and size. They are usually made of stainless steel, which is a strong and flexible material. The needles preferred by surgeons today are atraumatic disposable needles with pre-attached sutures on their posterior ends. Needles that may be used and sterilized many times are also available, with an eye or groove in the needle, through which the suture is passed.

Needles with Round or Oval Cross-Sectional View.
These are considered atraumatic and are mainly used for suturing thin mucosa. Their disadvantage is that great pressure is required when passing through the tissues, which may make suturing the wound harder.

Triangular Needles.
These needles have sharp cutting edges and are preferred for suturing thicker tissues. When they are used for thin mucosa, care is required because they may tear the tissues. The most suitable needles are semicircular or three-eighths of a circle and 19–20mmlong, in both cases.

Local Hemostatic Drugs
These drugs are suitable only for local use and can stop heavy bleeding, which is due to injury of capillaries or arterioles. The main hemostatic drugs are listed below.
Alginic Acid. This is sold in powder form in special 5-mg packages. It is placed on the bleeding surface, creating a protective membrane that applies pressure to the capillaries and helps hold the blood clot in place.
Natural Collagen Sponge. This is a white sponge material, non antigenic and fully absorbable. Its hemostatic ability is due to promotion of platelet aggregation. Also, it activates coagulation factors XI and XIII. It is used for patients who are prone to hemorrhage after dental surgical procedures.

Hemostatic powder suitable for stopping capillary bleeding

Absorbable hemostatic natural collagen sponges. These are indicated in cases of postextraction bleeding
Fibrin Sponge. The fibrin sponge is nonantigenic, and is prepared from bovine material that has been processed in order to avoid allergic reactions. It is used locally in the bleeding area and especially in the postextraction socket. It promotes coagulation, creating a normal hemostatic blood clot, but it also functions as a plug over the edges of the bleeding area. The fibrin sponge is fully absorbed by the tissues within 4–6 weeks.
Gelatin Sponge. This is a relatively spongy material, nonantigenic and fully absorbable. Its hemostatic action and application are the same as that of the fibrin sponge.
Oxidized Cellulose. This is an absorbable hemostatic material, which is manufactured by controlled oxidation of cellulose by nitrous dioxide. It is available in gauze form or pellet form (Fig. 4.67). It is used topically as a hemostatic material, because it releases cytotoxic acid, which has significant affinity for hemoglobin. Its attachment to the walls of the postextraction socket for the treatment of bleeding is quite satisfactory and therefore it is considered superior to various other hemostatic sponges, which have a tendency to expel thematerial from the socket.
Bone Wax. Bone wax is a sterilized, nonabsorbable mix of waxes, and is composed of white beeswax, paraffin wax, and an isopropyl ester of palmitic acid It is white and available as a solid rectangular plate weighing 2.5 g. It is used to control bleeding that originates in bone or chipped edges of bone. Before its application, bone wax is first warmed with the fingers, so that the desirable consistency is reached. Its hemostatic action is brought about through mechanical obstruction of the osseous cavity, which contains the bleeding vessels.

Gelatin sponges. These are used to treat postextraction bleeding

Oxidized cellulose in pellet form

Surgical bone wax for treatment of bone hemorrhage

Petrolatum (VaselineR) gauze in a sterile container

Materials for Covering or Filling a Surgical Wound

Petrolatum Gauze.
Petrolatum (VaselineR) gauze is available in sterilized packages and is used mainly for covering exposed wounds, for tamponade of bone cavities after marsupialization of cysts, for surgical procedures in themaxillary sinus, etc. Before its application, the excess petrolatummust be removed and the gauze saturated with antibiotic ointment (oxytetracycline), if deemed necessary.

Iodoform Gauze.
This gauze has antiseptic, analgesic and hemostatic properties. Its indications for use are the same as for petrolatum gauze, although it may remain in place for longer. The iodoform gauze is also available in small-sized packages, for the treatment of dry socket.

Surgical Dressing.
This is an autopolymerized puttylike paste, available in sterilized packaging. It is used in periodontology and oral surgery as a temporary protective covering of intraoral wounds after surgical procedures.

Clinical photograph showing closure of the operative field with surgical dressing

Materials for Tissue Regeneration
Sometimes during surgical procedures (removal of cysts, extraction of impacted teeth, etc.) large bony defects are created, which cause problems associated with esthetics, function, and the healing process, or They may even affect the stability of the jaw bone. Recently, application of a variety of materials in oral surgery to the area around these bony defects aids bone regeneration and eliminates the defect or limits its size. These materials may also prove useful in the regeneration of periodontal tissues, for the filling of bone defects around an implant, or for augmentation of a deficient alveolar ridge, etc. The most commonly used such materials are membranes and bone grafts.
Membranes. These may be absorbable or non absorbable. Synthetic polymer and collagen membranes are absorbable. Non absorbable membranes include those reinforced with titanium, aswell asmetallic titanium network membranes. The main disadvantage of non absorbable membranes is the need to perform a second surgical procedure for their removal.
Bone Grafts. These belong to four categories:
1. Autografts, which are composed of tissues from the actual patient.
2. Allografts, which are composed of tissues from another individual.
3. Heterografts, which are composed of tissues from various animals.
4. Alloplastic grafts, which are composed of synthetic bone substitutes, e.g., hydroxylapatite, phosphoric calcium ceramics, and oily calcium


a Absorbable collagen membrane used for guided bone regeneration. b Clinical photograph showing stabilization of the membrane in an area of bone deficit after surgical extraction

Heterografts of bovine bone (Bio-Oss) for the regeneration of large osseous defects; a in compact form, and b in granules


a Synthetic bone substitute (hydroxylapatite) in granules. b Clinical photograph of transplantation of lateral incisor of the maxilla. The area of osseous defect is filled with hydroxylapatite
Amelogenin (base and catalyst) used for tissue regeneration


a Oily calciumhydroxide in creamformused for bone regeneration. b Postextraction socket with buccal loss of bone. The area is filled with synthetic material
Other materials that contain amelogenin as the active ingredient, amelogenin being one of the proteins associated with tooth enamel, may also promote tissue regeneration. Of all the grafts, bone autografts give the best results. In spite of that, their use of limited, because a second concurrent surgical procedure is required. For this reason, the aforementioned synthetic substitute materials are used today instead, and bone regeneration in areas with large bone defects is accomplished satisfactorily.

Monday, September 12, 2011

Impacted Mandibular 3rd Molar Classification, Complications, Indications for surgical removal, Assessment and Surgical removal

“Definition of Impacted tooth”
An impacted tooth is any tooth that is prevented from reaching its normal position in the mouth by tissue, bone, or another tooth.

Of the surgical procedures performed in the oral cavity, the removal of impacted and semi-impacted teeth is the most common. The extraction of these teeth, depending on their localization, may prove to be relatively easy or extremely difficult and laborious. Regardless of the degree of difficulty of the surgical procedure though, its success primarily depends on correct preoperative evaluation and planning, as well as on the treatment of complications that may arise during the procedure, or the management of complications that may present after the surgical procedure. For these reasons, a medical history, clinical examination of the patient, and radiographic evaluation of the area surrounding the impacted tooth are deemed necessary.

Indications for removal of impacted tooth

Specialists have divergent points of view concerning the necessity to extract impacted teeth. Certain people suggest that the removal of impacted teeth is necessary as soon as their presence is confirmed, which is usually by chance. They even believe that it must be done as soon as possible, as long as there is no possibility that the impacted tooth may be brought into alignment in the dental arch using a combination of orthodontic and surgical techniques. On the other hand, others suggest that the preventive removal of asymptomatic impacted teeth, besides subjecting the patient to undue discomfort, entails the risk of causing serious local complications (e.g., nerve damage, displacement of the tooth into the maxillary sinus, fracture of the maxillary tuberosity, loss of support of adjacent teeth, etc.). As far as impacted teeth that have already caused problems are concerned,everyone agrees that they should be removed, regardless of the degree of difficulty of the surgical procedure. The most common of these problems are now given.

 

Pericoronitis in a semi-impacted mandibular third molar. Diagrammatic illustration showing inflammation under the operculum and distal to the crown of the tooth.
Clinical photograph. Characteristic swelling of the operculum due to constant biting from the antagonist

Localized or Generalized Neuralgias of the Head(Prevention of pain of unexplained origin.
Impacted teeth may be responsible for a variety of symptoms related to headaches and various types of neuralgias. If this is the case, the pain may be due to pressure exerted by the impacted tooth where it comes into contact with many nerve endings. Many people suggest that the symptoms may subside after the removal of the offending tooth, which basically involves ectopic impacted teeth.

Pericoronitis.
This is an acute infection of the soft tissues covering the semi-impacted tooth and the associated follicle. This condition may be due to injury of the operculum (soft tissues covering the tooth) by the antagonist third molar or because of entrapment of food under the operculum, resulting in bacterial invasion and infection of the area. After inflammation occurs, it remains permanent and causes acute episodes from time to time. It presents as severe pain in the region of the affected tooth,which radiates to the ear, temporomandibular joint, and posterior submandibular region. Trismus, difficulty in swallowing, submandibular lymphadenitis, rubor, and edema of the operculum are also noted. A characteristic of pericoronitis is that when pressure is applied to the operculum, severe pain and discharge of pus are observed. Acute pericoronitis is often responsible for the spread of infection to various regions of the neck and facial area.

Production of Caries.
Entrapment of food particles and bad hygiene, due to the presence of the semi-impacted tooth, may cause caries at the distal surface of the second molar, as well as on the crown of the impacted tooth itself.

Decreased Bone Support of Second Molar.
The well-timed extraction of a semi-impacted tooth presenting a periodontal pocket ensures the avoidance of resorption of the distal bone aspect of the second molar, which would result in a decrease of its support.

Obstruction of Placement of a Partial or Complete Denture.
The impacted teeth of edentulous patients can erupt towards the residual alveolar ridge, creating problems when applying a prosthesis. The localization of the tooth is often observed after its communication with the oral cavity and the presence of pain and edema.

Obstruction of the Normal Eruption of Permanent Teeth.
Impacted teeth and supernumerary teeth often hinder the normal eruption of permanent teeth, creating functional and esthetic problems.

Provoking or Aggravating Orthodontic Problems.
Lack of roomin the arch is possibly themost common indication for extraction, primarily of impacted and semi-impacted third molars of the maxilla and mandible.

Participation in the Development of Various Pathologic Conditions.
The coexistence of an impacted tooth and various pathologic conditions is not an uncommon phenomenon. Often cystic lesions develop around the crown of the tooth and are depicted on the radiograph as different-sized radiolucencies. These cysts may be large and may displace the impacted tooth to any position in the jaw. Whenthe presence of such osteolytic lesions is verified radiographically, they must be removed together with the associated impacted tooth.

Destruction of Adjacent Teeth Due to Resorption of Roots.
Resorption of the roots of adjacent teeth is another undesirable situation that may be caused by the impacted tooth; the effect isbrought about through pressure. This case primarily involves the posterior teeth of the maxilla and mandible. It begins with resorption of the distal root and, eventually, may totally destroy the tooth. The resorption of rootsmay also be observed in other areas of the dental arch and may involve dental surfaces other than those mentioned above. Having mentioned the undesirable situations that are associated with impacted teeth, and given the fact that no one can guarantee that an asymptomatic impacted tooth will not create problems in the future, the choice of removing or preserving the impacted tooth must be made after considering all the possibilities.

Prevention of fracture of jaws

Prevention of Periodontal Disease


Caries on the distal surface of the second molar, caused by a semi-impacted mandibular thirdmolar

Caries in the distal area of the crown of semi impacted third molar, due to entrapment of food and bad hygiene

Bone resorption at the distal surface of the root of a mandibular second molar, resulting in a periodontal pocket

Impacted mandibular third molar in edentulous area, which erupted after placement of a partial denture

Obstruction of the eruption of a mandibular second molar because of an impacted third molar

Impacted maxillary central incisor, whose eruption was obstructed because of a supernumerary tooth

Impacted mandibular third molar with well-defined radiolucency at the distal area

Impacted mandibular canine that is surrounded by a lesion

Extensive radiolucent lesion in the posterior area of the mandible, occupying the ramus. The impacted tooth has been displaced to the inferior border of the mandible.

Extensive radiolucent lesion in the mandible, extending from the mandibular notch as far as the canine. The impacted tooth has been displaced to an area high in the ramus of the mandible

Complete resorption of the distal root of the left mandibular firstmolar, due to an impacted second molar

Medical History
A detailed medical history is necessary because, based on the information provided, useful information may be found concerning the general health of the patient to be operated on. This information determines the preoperative preparation of the patient, as well as the postoperative care instructions.

Clinical Examination
During the intraoral clinical examination, the degree of difficulty of access to the tooth is determined, especially concerning impacted third molars. When the patient cannot open his or her mouth, because of trismus that is mainly due to inflammation, the trismus is treated first, and extraction of the third molar is performed at a later date. In certain cases of impacted teeth, especially canines, buccal or palatal protuberance may be observed during palpation or even inspection, which suggests that the impacted tooth is located underneath. Also, the adjacent teeth are examined and inspected (extensive caries, large amalgam restorations, prosthetic appliance, etc.) to ensure their integrity during manipulations with various instruments during the extraction procedure.

Radiographic Examination
The radiographic examination provides us with all the necessary information to program and correctly plan the surgical removal of impacted teeth. This information includes: position and type of impaction, relationship of impacted tooth to adjacent teeth, size and shape of impacted tooth, depth of impaction in bone, density of bone surrounding impacted tooth, and the relationship of the impacted tooth to various anatomic structures, such as the mandibular canal, mental foramen, and the maxillary sinus. These aforementioned data may also be provided by periapical radiographs and panoramic radiographs, as well as occlusal radiographs.

Assessment and Classification of Impacted third molar

Impacted Third Molar Classification.
The impacted mandibular third molar may present with various positions in the bone, and so the technique for its removal is determined by its localization. The classic positions of the tooth, depending on the direction of the crown of the tooth, are (according to Archer 1975; Kruger 1984): mesioangular, distoangular, vertical, horizontal, buccoangular, linguoangular, and inverted. Impacted teeth may also be classified according to their depth of impaction, their proximity to the second molar, as well as their localization in terms of the distance between the distal aspect of the second molar and the anterior border of the ramus of themandible. As far as the depth of impaction is concerned, mandibular third molars may be classified (according to Pell and Gregory 1933) as belonging to three categories:

Class A: The occlusal surface of the impacted tooth is at the same level as, or a little below that of, the second molar.
Class B: The occlusal surface of the impacted tooth is at the middle of the crown of the second molar or at the same level as the cervical line.
Class C: The occlusal surface of the impacted tooth is below the cervical line of the second molar As for the distance to the anterior border of the ramus of the mandible, impacted teeth may be classified as belonging to one of the following three categories:

Classification of impaction of mandibular third molars, according to Archer (1975) and Kruger (1984). (1Mesioangular, 2 distoangular, 3 vertical, 4 horizontal, 5 buccoangular, 6 linguoangular, 7 inverted)

Class 1: The distance between the second molar and the anterior border of the ramus is greater than the mesio distal diameter of the crown of the impacted tooth, so that its extraction does not require bone removal from the region of the ramus.
Class 2: The distance is less and the existing space is less than the mesiodistal diameter of the crown of the impacted tooth.
Class 3: There is no room between the second molar and the anterior border of the ramus, so that the entire impacted tooth or part of it is embedded in the ramus.

Classification of impacted mandibular third molars according to Pell and Gregory (1933): a according to the depth of impaction and proximity to the second molar; b their position according to the distance between the secondmolar and the anterior border of the ramus of the mandible

The above classification methods refer to all of the aforementioned positions of the impacted tooth. Furthermore, the number of roots of the impacted tooth and their relationship to the mandibular canal are taken into consideration. It is obvious that the cases belonging to Class 3 present more difficulty during the surgical procedure, because the extraction of the tooth requires removal of a relatively large amount of bone and there is a risk of fracturing the mandible and damaging the inferior alveolar nerve.

Winter's Lines (WAR)

The position & depth of the mandibular 3rd molar can be determined using the Winter’s Lines (WAR).  These are 3 imaginary lines (red, amber & white) “drawn” on the dental  X-ray (these days, normally an OPG / DPT).


White Line
The white line is drawn along the occlusal surfaces of the  erupted mandibular molars & extended over the 3rd molar  posteriorly.  It indicates the difference in occlusal level of  the 1st & 2nd molars & the 3rd molar.

Amber Line
The amber line represents the (height of the) bone level. The amber line is drawn from the surface of the bone on  the distal aspect of the 3rd molar (or from the ascending  ramus) to the crest of the inter dental septum twixt the 1st  & 2nd molars.  This line denotes the margin of the alveolar  bone covering the 3rd molar and gives some indication to  the amount of bone that will need to be removed for the
tooth to come out.

Red Line
The red line is an imaginary line drawn perpendicular from  the amber line to an imaginary point of application of an elevator.  Usually, this is the cemento-enamel junction on the mesial aspect of the impacted tooth (unless, it is the disto-angular impacted tooth where the application point  is the distal cemento-enamel junction).  The red line indicates the amount of bone that will have to be removed before elevation of the tooth i.e. the depth of the tooth in  the jaw & the difficulty encountered in removing the tooth.

With each increase in length of the red line by 1mm, the  impacted tooth becomes 3 x more difficult to remove (as opined by Howe).  If the red line is < 5mm, than the tooth  can be removed under just LA; anything above, a GA or  LA Sedation would be more appropriate.

Another method of judging the depth of the 3rd molar is to divide the root of the 2nd molar into thirds.  A horizontal line is drawn from the point of application for an  elevator to the 2nd molar.  If the point of application is adjacent to the coronal, middle or apical root third, then the tooth extraction is assessed as easy, moderate or difficult respectively.

Steps of Surgical Procedure
The surgical procedure for the extraction of impacted teeth includes the following steps:
1. Incision and reflection of the mucoperiosteal flap
2. Removal of bone to expose the impacted tooth
3. Luxation of the tooth
4. Care of the postsurgical socket and suturing of the wound

The main factors for a successful outcome to the surgical procedure are as follows:
·         Correct flap design, which must be based on the clinical and radiographic examination (position of tooth, relationship of roots to anatomic structures, root morphology).
·         Ensuring the pathway for removal of the impacted tooth, with as little bone removal as possible. This is achieved when the tooth is sectioned and removed in segments, which causes the least trauma possible.

Principles of Mucoperiosteal flap design
1.       Preservation of blood supply
2.       Adequate access
3.       Prevent damage to vital structures
4.       Incision margins should lie on sound bony margins
5.       Ease of repositioning

Types of Flaps.
According to the type of incision
·         Envelope
·         Two sided
·         Three sided
·         Apically repositioned flap
·         Semilunar

According to the thickness
·         Full thickness
·         Partial thickness

According to the site
·         Labial or buccal flap
·         Palatal or Lingual flap

Many types of flaps may be used when surgically removing impacted mandibular third molars: the triangular and the envelope flap are the commonest using flaps. The choice depends on the evaluation of the various data pertaining to the case (e.g., depth of impaction, position, etc.).

Triangular flap:
The incision for this type of flap begins at the anterior border of the ramus (external oblique ridge) with special care for the lingual nerve and extends as far as the distal aspect of the second molar, while the vertical releasing incision is made obliquely downwards and forward, ending in the vestibular fold In certain cases, e.g., when impaction is deep, to ensure a satisfactory surgical field or when the impacted tooth conceals the roots of the second molar, the incision may continue along the cervical line of the last tooth while the vertical incision begins at the distal aspect of the first molar. 


Variation of incision shown in figure (vertical releasing incision is distal to the first molar). The mesial extension of incision is necessary due to the position of the third molar compared to the second molar

Horizontal (envelope) flap:
The incision for the flap also begins at the anterior border of the ramus and extends as far as the distal aspect of the second molar, continuing along the cervical lines of the last two teeth, and ending at the mesial aspect of the first molar. This type of flap is usually used in cases where impaction is relatively superficial.


Clinical photograph and b diagrammatic illustration showing incision for envelope flap

Anesthesia.
Anesthesia in cases of impacted mandibular third molars is achieved by: inferior alveolar nerve block, buccal nerve block, lingual nerve block, and local infiltration for hemostasis in the surgical field.

Techniques of bone removal
·         Use of Burs
·         Use of chisel and mallet

Bone removal with burs-Points to remember

·         Copius irrigation
·         Protect vital structures

Principles of closure of flaps
·         Gentle tissue handling
·         Not too tight sutures
·         Haemostasis prior to closing
·         Avoid dead space
·         Decontamination and debridement
·         Proper approximation

Surgical removal of different types of impactions will be discussed in later posts

Sunday, September 11, 2011

Sickle cell anaemia

Pathogenesis (mechanism)
In a normal person,
  • RBCs contain Hb molecules.
  • One Hb molecule contains 4 polypeptide chains.
  • 2 alpha & 2 beta chains.
  • A particular gene is responsible for the formation of 2 beta chains.
  • It is situated on the short limb of 11th chromosome.
  • In a particular beta chain, 6th amino acid is the hydrophilic glutamic acid.
  • Glutamic acid is responsible for the polarization of a particular oxygen molecule to bind with the Hb molecule.
  • The bound oxygen molecule is then transported in the RBC to supply the body cells.
 

In an anaemic patient,
  • Beta globin gene is affected (point mutation).
  • It is responsible for the formation of affected beta chains.
  • Normal 2 alpha chains & 1 beta chain combine with the affected beta chain to form an abnormal Hb molecule called sickle cell haemoglobin (Hbs).
  • So, 6th amino acid of the affected beta chain is not the glutamic acid but hydrophobic amino acid called valine.
  • The oxygen molecules cant bind with the valine.
  • Then the total number of oxygen molecules that can bind with a Hb molecule become less.
  • So, the body cells prone to ischemia. 
  • In low oxygen concentrations (ex – high altitude), absence of the polar amino acid at the 6th position of beta chain promotes non covalent polymerization of Hb molecules.
  • Hb molecules become aggregated.
  • Aggregated Hb molecules become precipitated.
  • Due to the precipitate, RBCs loss their membrane elasticity.
  • RBCs distort their shape due to loss of membrane elasticity.
  • This process is called sickling.
  • Sickle cells are rapidly removed from the circulation because they are non reversible with high oxygen concentrations.
 
Inheritance
  • Autosomal recessive disease.
  • Inherited by consanguineous marriages.
  • Both males & females are affected.
  • The trait is shown when both genes are recessive (homozygous).
  • Heterozygous females are carries.
  • They do not show the disease (asymptomatic).
  • But they transmit this gene to their children.
  • There is a 1-in-4 chance of their child developing the disease & 1-in-2 chance of their child is being just a carrier.
  • Heterozygous individuals are moderately resistant to the malarial infection.  
 
Complications

  • Splenomegaly
  • Jaundice
  • Severe anaemia
  • Tachycardia
  • Reticulocytopenia
  • Stroke

Friday, September 9, 2011

Pterygomandibular Abscess,Anatomic Location,Etiology, Clinical presentation and Treatment


Anatomic Location.
This space is bounded laterally by the medial surface of the ramus of the mandible, medially by the medial pterygoid muscle, superiorly by the lateral pterygoid muscle, anteriorly by the pterygomandibular raphe, and posteriorly by the parotid gland. The pterygomandibular space contains the mandibular neurovascular bundle, lingual nerve, and part of the buccal fat pad. It communicates with the pterygopalatal, infratemporal, submandibular, and lateral pharyngeal spaces. 
 
Etiology
An abscess of this space is causedmainly by infection of mandibular third molars or the result of an inferior alveolar nerve block, if the penetration site of the needle is infected (pericoronitis).

Clinical Presentation
Severe trismus and slight extraoral edema beneath the angle of the mandible are observed. Intraorally, edema of the soft palate of the affected side is present, as is displacement of the uvula and lateral pharyngeal wall, while there is difficulty in swallowing.

Treatment
The incision for drainage is performed on themucosa of the oral cavity and, more specifically, along the mesial temporal crest. The incision must be 1.5 cm long and 3–4 mm deep. A curved hemostat is then inserted, which proceeds posteriorly and laterally until it comes into contact with the medial surface of the ramus. The abscess is drained, permitting the evacuation of pus along the shaft of the instrument.

Diagrammatic illustration showing the spread of a dentoalveolar abscess into contiguous fascial spaces. (1 Submandibular abscess, 2 pterygomandibular abscess, 3 parapharyngeal abscess, 4 retropharyngeal abscess)


Incision for drainage of a pterygomandibular abscess

 

Wednesday, September 7, 2011

DiGeorge Syndrome Lecture Note

A word about nomenclature
          Chromosome 22q11.2 deletion syndrome
          DiGeorge syndrome
          Velocardiofacial syndrome
          Conotruncal anomaly face
          Some CHARGE

The majority of patients with DiGeorge syndrome, VCFS, CTAF have hemizygous deletions of chromosome 22q11.2.  The nomenclature is not synonymous.

The Phenotype of Chromosome 22q11.2 Deletion Syndrome
          Cardiac anomaly 75%
        TOF-20%
        IAA-15%
        Truncus arteriosus-8%
          Palatal anomaly-69-100%
          Hypocalcemia-17-60%
          Speech delay-75%
          Renal anomaly-36-37%
          Skeletal anomaly-17-19%
          Immunodeficiency-60-77%

Where to look for the deletion?

Cardiac Diseases
Any cardiac lesion-1.1%
Interrupted aortic arch-50-60%
Pulmonary atresia-33-45%
Aberrant subclavian-25%
Tetralogy of Fallot-11-17%

Others
Velopharyngeal insufficiency following adnoidectomy-64%
Isolated velopharyngeal insufficiency-37%
Neonatal hypocalcemia-74%
Schizophrenia-0.3-6.4%

The diagnosis is established by FISH


 
22 well-characterized genes
The critical region was established by generating mice with comparable deletions 

The Heterozygous  Murine  Deletion
25-50% of mice have cardiovascular anomalies
o   Aberrant great vessels (right subclavian, IAAB)
o   VSDs
o   Conotruncal anomalies rare
Thymus was variably effected depending on background strain
Parathyroid gland variable
Homozygous mice have additional features of Ch22q11.2 D

Tbx-1
          Expressed in developing mesenchyme
          Expressed in pharyngeal arches, otic vesicle, tooth buds, sclerotome
          Heterozygous mutations of Tbx-1 are associated with great vessel defects in mice
      Homozygous deficient mice have a small mandible, low set ears, a single cardiac outflow tract, deficient thymus/parathyroid/salivary glands

TBX1 in humans

More than TBX1?
          COMT, GPIBB may modify the phenotype
          Background genes outside the deleted region may modify the phenotype

The significance of establishing the diagnosis
Toddlers
        79% significant motor delay
        53% significant expressive delay
        26% significant receptive delay

School-age
        12.7% average IQ (Weschler)
        25.5% low average
        34.5% borderline
        27.3% retarded
Behavior/School issues
          65.5% have a nonverbal learning disability
          25% have ADHD
          6-30% will develop schizophrenia

The Immunodeficiency of Chromosome 22q11.2 Deletion Syndrome
          60-77% of patients have laboratory evidence of quantitative T cell defects
          Only 0.5-1.0% have absent T cells
          T cell proliferation is usually normal
          2-4% are IgA deficient
          10% have delayed production of IgG

The Role of the Thymus in the Immunodeficiency


        15-20% of patients have an absent anatomic thymus
        Thymic tissue is found in aberrant locations
        Only 0.5-1.0% of patients have no T cells and truly  have thymic aplasia

80% of patients have thymic hypoplasia
          Restricts T cell output
          T cells are qualitatively normal
          CD4/CD25 T cells are markedly decreased
          There can be secondary effects on antibody production

Clinical Immunodeficiency
7% of all ages have significant, serious infections
9% have autoimmune disease
Older children and adults continue to get infections
                27% recurrent sinusitis
                25% recurrent otitis media
                7% recurrent bronchitis
                4% recurrent pneumonia

Autoimmunity
          JRA is seen 20X more frequently  (2%)
          ITP is seen 200X more frequently  (4%)
          AHA, IBD are seen in about 1%
          Older patients develop autoimmune diseases of adults

T cell findings
          The mean T cell number is about 50% of normal in infancy
          The mean T cell number is about 80% of normal in adulthood
          Why are the adults sick so much?

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