Elevators
The dental elevators are used to luxate the teeth from the socket prior to application of the forceps. In addition to luxation of the teeth, the elevators also expand the bony socket facilitating tooth extraction. They are also used to remove root remnants from the extraction socket.
The elevator has three components:
1. Handle 2. Shank 3. Blade.
The handle is usually large in size to facilitate a good grip on the instrument while working. It may be 180o to the shank or at right angles to the shank. The latter are known as crossbar elevators. The crossbar elevators can generate tremendous amount of force.
The shank connects the handle to the blade. The shank should be strong enough to withstand and transmit the forces applied to the handle.
The blade of the elevator is the working tip of the elevator which is used to transmit forces to the tooth, root and bone. Blades can vary in size and shape and depending on that the elevators are classified as:
1. The Straight or the gouge type 2. The Triangular type
3. The Pick type
Work Principles of Elevation (Fig. 5.19)
There are three work principles applicable to the elevators. They are:
1. Lever principle
This is the most commonly used principle. The elevator is a lever of the first order. In this the fulcrum is between the effort and the resistance. In
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Principles of Oral and Maxillofacial Surgery
order to gain mechanical advantage, the effort arm must be longer than the resistance arm.
2. Wedge principle
The wedge elevator is forced between the root and the bone , parallel to the long axis of the tooth. The wedge is a movable inclined plane which overcomes a large resistance at right angles to the applied effort.
It is usually used in conjunction with the lever principle.
3. Wheel and Axle Principle
The wheel and axle principle is actually a modified form of lever principle. The effort is applied to circumference of a wheel which turns the axle so as to raise a weight. The principle is used with wedge and sometimes with the lever principle. The principle is applicable to the cross bar elevators.
Indications for the Use of Elevators
1. To luxate multirooted teeth prior to forceps application.
2. To luxate, remove teeth that cannot be engaged by the beaks of the forceps, e.g. Impacted teeth, malposed teeth, badly carious teeth.
3. To remove fractured root stumps, apical tips.
Rules to be Followed While Using the Elevators 1. Never use the adjacent tooth as the fulcrum, unless
that the adjacent tooth is also to be extracted.
2. Never use the buccal or lingual plate as the fulcrum.
3. Always use finger guards to protect the soft tissues if the elevator slips.
4. Support the shank of the elevator with the index finger to control the forces applied to the elevator.
5. Always elevate from the mesial side of the tooth.
6. The concave or flat surface of the elevator faces the tooth/ root to be elevated.
Commonly Used Elevators
Straight Elevators (Coupland, London Hospital pattern) (Fig. 5.20D-I)
They are the most common types used for the luxation of teeth. The blade has a concave surface on one side, Fig. 5.19: Lever principle of elevation
Figs 5.20A to D: (A) Maxillary extraction forceps, (B) Mandibular extraction forceps, (C) (I) Winter cryer’s elevators, (II) Winter’s Crossbar elevators, (D) (I) Straight elevator, (II) London hospital hockey stick pattern elevators, (III) apexo elevators
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Armamentarium Used in Oral and Maxillofacial Surgery
that faces the tooth to be elevated. Sometimes the blade can be at an angle to the shank, allowing the instrument to reach the posterior areas of the oral cavity easily.
Common examples of these elevators are, the Miller and the Pott‘s elevator.
Cryer‘s Elevator
Cryer‘s elevator is a straight elevator with a triangular blade. The working tip is angulated, with one convex and another flat surface. The flat surface is the working side. It is based on the lever and the wedge principle.
Uses
1. For extraction of root stump of mandibular molars when one root is removed and the other is to be removed.
2. For extraction of mandibular molar root stumps when both the roots are present but one is fractured at a lower level than the other or when the bifurcation is intact.
Two separate elevators are available for the mesial and distal roots. The working blade is introduced into the empty socket and moved towards the remaining root piece. In this technique the interradicular bone is fractured prior to removal of the root stump.
Winter’s Elevator
Winter’s elevator is a crossbar elevator. The shank is at right angles to the handle. The working tip is at an angle to the shank. The blade has a convex and a flat surface.
The flat surface is the working surface and is placed facing the tooth to be elevated. It works on the wheel and axle principle.
Uses
To luxate the mandibular molar teeth.
Winter Cryer’s Elevator (Fig. 5.20C-I)
As the name suggests, the elevator is a crossbar elevator with a triangular blade. The uses and the applications of this instrument are similar to the Cryer’s elevator. It works on the wheel and axle and wedge principles.
Apexo Elevators (Fig. 5.20D-III)
These are straight elevators that resemble the Cryer’s elevators, but have a biangulated and sharp, straight working tip. They are paired elevators for the mesial and the distal roots. Their uses and work principles are same as for the Cryer’s elevators. They can also be used to remove the maxillary root stumps.
Hockey Stick or London Hospital Elevator (Fig. 5.20D-II)
This elevator is similar to the Cryer’s elevator, with the working blade at an angulation to the shank, but the
blade is straight, rather than triangular, and has a convex and a flat surface. The flat surface is the working surface and has transverse serrations on it for better contact with the root stump. When viewed, the instru-ment looks like a Hockey stick and hence the name.The principles and functions are similar to the Cryer’s elevator.
Extraction Forceps
They are designed to deliver the teeth from the sockets.
Each forceps has two handles, a joint and two beaks.
All the forceps have crosshatching on the handles to allow a firm grip and have serrations on the inner side of the beaks to allow a better grip on the tooth. The beaks are applied along the long axis of the tooth, below the CE junction in mandibular teeth, and above the CE Junction in maxillary teeth. A firm grip on the tooth is established prior to giving any forceps movements.
Maxillary Extraction Forceps (Fig. 5.20A)
In all the maxillary extraction forceps the handles and the beaks are at 180o to each other, i.e. in a straight line.
Maxillary anterior forceps They have identical beaks that are closed, straight, flat and broad. They are used for extraction of the maxillary incisors and the canines.
Basic forces: Maxillary central incisors: Labial movement, mesial rotation
Maxillary lateral incisors: Labio-palatal movements, removal in the labial direction
Maxillary canine: Labio-palatal movements, removal in the labial direction.
Maxillary premolar forceps They have identical beaks that are concave on the side facing the operator. The beaks are broad and open. They are used for extraction of the maxillary premolars. The curvature of the blade is to give access to the premolars placed posteriorly in the arch. Rotational and buccal movements are given for the maxillary second premolar, while only bucco-palatal movements are given for the first premolar.
Basic forces
First Premolar: Bucco-palatal movements and removal in the buccal direction.
Second Premolar: Bucco-palatal movements and removal in the buccal or palatal direction.
Maxillary Molars (Right and Left)
The beaks of these forceps are not identical. One beak is rounded and the other one is pointed. The pointed beak engages the groove between the buccal roots and the other beak engages the palatal surface above the CEJ. The beaks also have a curvature towards the
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Principles of Oral and Maxillofacial Surgery
operator like the premolar forceps. When viewed, if the pointed beak is to the left of the operator it is a right sided forceps and vice versa.
Basic Forces The first and the second molars are extracted by giving bucco-palatal movements and removal in the buccal direction.
The third molar is extracted by giving buccal movements and distal rotation.
Maxillary Cowhorn forceps These forceps have unidentical beaks, one of which has a single pointed tip and the other a bifid pointed tip. The single pointed tip engages the furcation between the two buccal roots and the other tip engages the palatal root. It is a paired forceps. The beaks are curved towards the operator.
While viewing the concave surface of the beaks, the bifid beak will be on the right for the maxillary right sided forceps and vice-versa. They are used for maxillary teeth, where there is extensive destruction of the crown, but the trifurcation of the roots is intact.
Maxillary anterior root forceps They have identical, straight, slender and closed beaks. They are used primarily for the extraction of the root stumps of the maxillary anterior teeth.
Maxillary posterior root forceps They are similar to the anterior root forceps, but like the premolar forceps, they have a curvature towards the operator for access posteriorly. They are used for removing single molar root pieces and premolar root stumps.
Bayonet forceps They have identical, pointed, angulated and closed beaks. The length of the beaks vary from long to short. According to the thickness of the beaks they can be classified into thick beak and thin beak bayonet forceps. The thick beak bayonet forceps is used to remove maxillary posterior root stumps that are not separated, while the thin beak forceps are used to remove single roots.
Mandibular Forceps (Fig. 5.20B)
The mandibular forceps are designed such that the handles and the beaks are at right angle to each other to facilitate easy access to the mandibular teeth.
Mandibular anterior forceps The mandibular anterior forceps have identical broad, short, closed beaks. The joint is a rivet joint unlike most forceps that have a box joint. They are used for extracting mandibular anterior teeth.
Basic forces: Central and lateral incisors : Labio- lingual and mesio- distal movements and removal in the labial direction.
Cuspid: Labio- lingual movement and removal in the labial direction.
Mandibular premolar forceps The mandibular premolar have identical broad open beaks that are longer than the beaks of the anterior forceps. They are used for extraction of the mandibular premolar teeth.
Basic forces Both the premolars are extracted with buccolingual and mesiodistal movements.
Mandibular molar forceps They have identical, broad, open beaks with a pointed tip. They are used for the extraction of mandibular molar teeth.
Basic forces: All the molars are extracted by bucco-lingual movements and removal in the buccal direction.
Mandibular Cow Horn forceps The mandibular Cow Horn forceps have identical, open, short, pointed beaks that resemble the horns of a cow. The beaks are round and taper to a point. The forceps grips the tooth at the bifurcation between the mesial and distal roots. When pressure is applied and the beaks are closed using the buccal and the lingual plates as the fulcrum, the tooth is luxated or literally squeezed out of the socket, provided the root morphology is favourable. They are used to remove grossly carious mandibular molars with extensive destruction of the crown.
Mandibular root forceps These forceps have identical, slender beaks that are closed. The beaks are longer than that of the premolar forceps to enable the forceps to take a deep grip on the root stump. It is used for removal of root stumps of all the mandibular teeth.
Surgical Diathermy (Cautery, Electrocautery) (Fig. 5.21)
There are two basic types of cautery:
1. Mono or unipolar 2. Bipolar
Monopolar Diathermy It basically consists of:
1. High frequency A.C. generator (over 20,000 Hz) 2. Regulator
3. Foot control
4. Indifferent electrode 5. Active electrode
The A.C. electrode generates a high frequency alternate current, the intensity of which is controlled by the regulator. The indifferent electrode is a flat steel plate which is put in contact with the patient’s back, thigh or buttocks. The contact between the patient’s skin and the indifferent electrode may be improved by,
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Armamentarium Used in Oral and Maxillofacial Surgery
either shaving that area or by using a conductive jelly.
The electrode is usually wrapped with a wet cloth to improve conduction.
The active electrode or the tip touches the haemostat in which the bleeder is held. When the foot control is pressed, current is generated and discharged through the active electrode.
Principles
The large, flat steel plate or the indifferent electrode acts as the earth. The active electrode is a fine tip. Due to the large difference in the size of the two electrodes, a high current density is generated around the active electrode, resulting in a heating effect. By changing the intensity of the current, various functions are possible.
1. Coagulation 2. Cutting 3. Fulguration
Coagulation Bleeding from the small vessels, viz the capillaries, arterioles, can be controlled. The subcutaneous bleeders and oozing vessels from the incision lines are first clamped with a haemostat and then the cautery is applied. Bleeding from thin walled veins and large arteries cannot be controlled by cauterization. They have to be ligated and then divided.
Cutting An incision can be made by increasing the current and using a cutting tip. It is used for incising soft tissues with diffuse capillary network so that the small bleeders get coagulated as cutting occurs. It is never used for taking skin incisions.
Fulguration Fulguration burns the tissue margins. This is useful in resecting small growths, e.g. papilloma, leukoplakia, so as to prevent recurrence.
Precautions
1. Care must be taken to ensure intimate contact between the patient and the indifferent electrode.
Avoid point contact.
2. Avoid placement of the indifferent electrode near bony ridges.
3. If ether, cyclopropane are used for general anaesthesia, risk of sparking is high.
4. Operator using the tip should wear rubber footwear so as to avoid accidental burn.
5. Avoid contact of the tip with retractors or other metal instruments which will conduct electricity.
6. Do not use near isolated vascular pedicles or nerves.
Bipolar Diathermy
This consists of an A.C. generator foot switch. It does not have an indifferent electrode. The A.C. is of low power. The active electrode is in the form of forceps, the two tips of which serve as the two electrodes. As the current generated is smaller, the bipolar diathermy can be used only for coagulation, but not for cutting.
When the two ends of the forceps are brought together, a circuit is created, producing a localized current.
Bipolar diathermy reduces the risk of burns, and interference with other instruments such as ECG units pacemakers. It also reduces the risk of spark ignition of anaesthetic gases.
Cryosurgery (Figs 5.22 (1 and 2))
It is the technique of using extreme rapid cooling to freeze and thereby destroy tissues. Rapid cooling to temperatures below freezing point produces a localized destructive effect than slow freezing which causes generalized tissue necrosis.
The effects of rapid freezing on the tissues are:
1. Reduction of intracellular water.
2. Cellular shrinkage.
3. Increased concentration of intracellular solutes.
4. Cell membrane damage.
5. Formation of intracellular ice crystals.
6. Formation of extracellular ice crystals.
The apparatus consists:
1. Bottles for storage of pressurized liquid gases.
Liquid nitrogen gives a temperature of - 196o C, while liquid carbon dioxide, or nitrous dioxide give a temperature between -20 o C to -90o C 2. A pressure and temperature gauge
3. A probe: The probe is connected to the bottles via a tubing through which the pressurized gas can be directed at the tissue to be destroyed.
Fig. 5.21: Surgical diathermy (electrocautery machine):
(I) Indifferent electrode plate, (II) Active electrode tip
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Principles of Oral and Maxillofacial Surgery Following freezing, the tissues are thawed and
refreezed. Alternate cooling and thawing destroys the tissues. The time and temperature for cryotherapy is determined by the depth and extent of the tumour.
Figs 5.22 (1 and 2): (1) Old cryosurgery unit. A—Nitrous oxide cylinder, B—Cryoprobe, C—Warming cycle light, D—Freezing cycle light, E—Foot switch, (2) New Cryosurgical units
It is applied in the treatment of malignancies, vascular tumours, aggressive tumours like amelo-blastoma.
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Suturing Materials and Techniques