Posted in Dento-alveolar

Exodontia : Basic Principles & Methods

EXODONTIA: Basic Principles & Methods

  1. Pain and Anxiety control:
  • Removal of a tooth requires profound local anesthesia to prevent pain during extraction, and control of patient anxiety is necessary to prevent psychological distress.
  • Local anaesthesia must be absolutely profound to prevent and eliminate painful sensations from the pulp, periodontal ligament and buccal and lingual soft tissues.

LOCAL ANESTHESIA

  • For obtaining profound anaesthesia of the tooth to be extracted, it is essential for the surgeon to remember the precise innervation of all teeth and their surrounding soft tissue and the techniques necessary to anaesthetize those nerves totally.
  • It is necessary to remember that in areas of nerve transition. There is almost always overlap in some areas. Therefore, it may be necessary to supplement the primary block with additional infiltration to prevent pain from the transitional nerve endings from the surrounding tissue area.
  • Profound local anesthesia results in loss of all pain, temperature and touch sensations but does not anaesthesize the proprioceptive fibres of the involved nerves. Thus, the patient feels a sense of pressure, especially when the force is internal. One must therefore remember to that the patient will need to distinguish between the sharp pain and the dull, although intense, feel of pressure.
  • Inspite of profound anaesthesia, the patient may continue to have sharp pain as the tooth is luxated. This is especially likely when the teeth have pulpitis or the surrounding soft and hard tissue is inflamed or infected. A technique that should be employed in such situations is the PDL injection. When this injection is delivered properly, there is immediate profound local anesthesia in almost all situations. The anesthesia is short lined, so the surgical procedures should be one that can be accomplished in 15 to 20 minutes.
  • It is important to keep in mind the pharmacology of the various local anaesthetic solution that are used, so that they can be employed properly. Following points should be remembered.
    1. Amount of time they can be expected to provide profound anaesthesia (Ref. Table 7.3).
    2. Pulpal anesthesia of maxillary teeth after local infiltration lasts a much shorter time than does pulpal anesthesia for mandibular teeth after block anaesthesia.
    3. Pulpal anesthesia disappears 60 to 90 mts before soft tissue anesthesia does.
  • Maximum dose that can be given safely for the particular anaesthetic agent in use (Ref Table 7.4). It is wise to remember that the smallest amount of local anesthetic solution between sufficient to provide profound anaesthesia is the proper and safe amount.

Sedation:

  • Management of patient anxiety must be a major consideration when one performs oral surgery procedures.
  • Anxiety lessens the pain threshold, and frequently patients are already in pain and may be agitated and fatigued. This lessens the patients ability to deal with pain and pain related situations.
  • Also, as noted before, although local anesthesia eliminates, sharp pain, the dull sense of pressure is still present, which may be come quite intense.
  • For all of these reasons, it is prudent for a dentist to use a prospective planned method of anxiety control to prepare themselves and their patients for the anxiety a/w tooth extraction and oral surgical procedures.

Various methods of anxiety control:

  • Proper explanation of the planned procedure, including assurance that there will be no sharp pain but honest acceptance that there will be dull discomfort due to pressure.
  • An expression of concern, caring and empathy is required of the dentist. For the mildly anxious patient, with a caring dentist, no pharmacologic assistance is required.
  • For the more anxious patient it becomes necessary to employ pharmacologic assistance. Preop orally administered drugs, such as diazepam or chloral hydrate may provide a patient with rest the night before the surgery and some relief of anxiety in the morning.
  • However, orally administered drugs are usually not profound enough to control moderate to severe anxiety once the patient enters the operative suite.
  • Sedation by Nitrous Oxide gas and oxygen is frequently the technique of choice and may be the sole technique needed for many patient who have mild to moderate anxiety. If the dentist is skilled in the use of nitrous oxide gas and the patient requires a routine, uncomplicated surgical procedure, sedation is frequently sufficient.
  • An extremely anxious patient who is to have several uncomplicated extractions may require parenteral sedation, usually by IV route. It may be necessary to administer IV sedation with diazepam or other drugs to aid such patient in tolerating the surgical procedure.
  1. Presurgical Medical Assessment:

When evaluating a patient preop it is critical that the surgeon examine the patients medical status. Patients may have a variety of maladies that require treatment modification before the surgery can be performed safely. Special measures may be needed to control bleeding, prevent, infection and prevent worsening of the patients preexisting state or condition.

  1. Indications for Removal of teeth:

Although it is the position of dental practice to take all possible measures to preserve and maintain teeth in the oral cavity, it is sometimes necessary to remove some of them for various reasons. The following are some such reasons.

  1. Severe caries : When a tooth is so severely caried that it cannot be restored, it frequently is necessary to remove it.
  2. Pulpal necrosis : Second rationale is the presence of pulpal necrosis or irreversible pulpitis that is not amenable to endodontics. This may be caused by a patient who refuses to or cannot afford endodontic treatment or it may be caused by a root canal that is tortous, calcified and untreatable by standard endodontic technique. Also included is the endodontic failure.
  3. Severe periodontal disease : A common reason for tooth removal is severe and extensive periodontal disease. If severe adult periodontitis has existed for some time, there is excessive tooth mobility due to irreversible bone loss leading to pain and loss of function. There may also be formation of a periodontal abscess. In these situations, the hypermobile teeth should be extracted.
  4. Orthodontic reasons: Patients about to undergo orthodontic correction of crowded dentition frequently require the extraction of teeth to provide space for tooth alignment. Most commonly extracted teeth are the maxillary and mandibular first premolars, but second premolars or a mandibular incisor may occasionally need extraction for this same reason.
  5. Malopposed teeth: Teeth that are malopposed or malposed may require extraction if they traumatize soft tissues and cannot be repositioned by orthodontic treatment. A common example is the maxillary 3rd molar which erupts in buccoversion and causes ulceration and soft tissue trauma in the check. Another example is hypererupted teeth due to loss of antagonist tooth. These may interface with construction of an adequate prosthesis. Such teeth may need to be extracted.
  6. Cracked teeth: A clear but uncommon indication for extraction of teeth is when a tooth is cracked or has a fracture root. The cracked tooth can be painful and is unmanageable by a more conservative technique. Even endodontic and complex restorative procedures cannot relieve the pain of a cracked teeth.
  7. Preprosthetic extraction: Teeth occasionally interface with the design and proper placement of prosthetic appliances full dentures, partial dentures or fixed partial dentures. In such cases preprosthetic extractions may be necessary.
  8. Impacted teeth: These should always be considered for extraction. If it is clear that an impacted teeth is unable to erupt into a functional occlusion because of inadequate space, interference from an adjacent teeth or some other reason, it should be scheduled for surgical removal unless contraindicated.
  9. Supernumerary teeth: Supernumerary teeth are usually impacted and should be removed. They may interface with eruption of succedaneous teeth and have the potential for causing their resorption and displacement. They are also frequently involved with cyst formation.
  10. Teeth a/w pathologic lesions: Teeth a/w lesions like tumors and cysts frequently require extraction unless they can be retained and endodontic treatment performed. However, if maintaining the teeth compromises the surgical removal of the lesion, it should be extracted.
  11. Preradiation therapy: Patients who are to receive radiation therapy for a variety of oral tumors should have serious consideration given to removing teeth in the line of radiation prior to therapy.
  12. Teeth involved in jaw fractures: Patients who sustain fractures of the mandible or the alveolar process occasionally need to have teeth removed. In majority of situations the involved teeth may be retained but if the teeth is injured or severely luxated, it may need extraction.
  13. Esthetics: Severely stained, malposed or protruding teeth may sometimes require extraction.

Contraindications:

These are relative and not absolute, many times extraction can still be done with use of additional care, modified techniques and resolution of underlying problem that contraindicate extraction. Two groups: Systemic and Local.

Systemic contraindications:

In these situations the patients general health is such that it cannot withstand surgical treatment as the condition may be further aggravated.

  • Metabolic diseases – e.g. Severe uncontrolled diabetes, end-stage renal disease with severe uremia. Patients with mild or well controlled diabetes can be treated as reasonably normal patients.
  • Uncontrolled leukomias and lymphomas: extraction may lead to infection due to non-functional white cells and profound bleeding due to deficient platelets.
  • Cardiac disorders: Severe myocardial ischaemic such as unstable angina and patients with recent MI should not have a tooth extracted. Patients with severe malignant hypertension should also have extraction deferred due to risk of persistent bleeding, acute myocardial insufficiency and cerebrovascular accidents.
  • Pregnancy: Patients in first and 3rd trimester should have extraction deferred as much as possible. Latter part of 1st trimester and 1st month of 3rd trimester are just as safe as 2nd trimester and extractions can be carried out if necessary, but more extensive surgical procedures should be deferred until after delivery.
  • Severe bleeding diathesis: Coagulopathy should be corrected by transfusion of coagulation factors and / or platelets. Close coordination with patients hematologist is needed.

Local Contraindications:

  1. Therapeutic radiation for cancer: Extraction in irradiated areas may lead to osteoradionecrosis and therefore must be done with extreme caution.
  2. Teeth located in an area of a malignant tumor should not be extracted – it would lead to dissemination of cells and thereby hasten metastatic process.
  3. Patients who have severe pericoronitis around an impacted 3rd molar should not have extraction until the pericoronitis has been treated. Non surgical treatment with irrigations, antibiotics and removal of maxillary 3rd molar to relieve impingement on the edematous pericoronal tissues will lead to resolution of the infection. Otherwise extraction would lead to severe infection which is potentially fatal.
  4. Acute dentoalveolar abscess: Normally the most rapid resolution of an infection secondary to pulpnecrosis is observed when the teeth is removed as soon as possible. Therefore, acute infection should not be a contraindication to extraction. However, it may be difficult to extract such a tooth because the patient may not be able to open his/her mouth sufficiently wide or it may be difficult to obtain adequate local anesthesia due to increased pH. With resolution of acute symptoms, extraction can be done.

Mechanical principles involved in Exodontia:

Removal of teeth from the alveolar process employs the use of several mechanical principles and simple machines: The lever, the wedge and the wheel and axle.

  • Elevators are used primarily as levers. A lever is a mechanism for transmitting a modest force with the mechanical advantage of a long lever arm and a short effector arm into a small movement against resistance. When an elevator is used for teeth extraction, a purchase point can be made on the tooth and a straight or crane pick elevator can be used to elevate the tooth or root from the socket using the alveolar bone as a fulcrum. The mesial cervical junction of the tooth can also be used as a purchase point and a small straight elevator can luxate the tooth.
  • Secondly, a wedge can be used in several different ways. First, the beaks of extraction forceps are usually narrow at their tips. When the forceps are held, they should be forced into the PDL space to expand the bone and displace the tooth out of the socket. The wedge is also useful when a straight elevator is used to luxate a tooth from its socket by forcing it into the PDL space.
  • The 3rd machine used is the wheel and axle which is most commonly identified the Cryer’s and Winter’s cross-bar elevator. When one root of a multirotated tooth is left in the alveolar process, Cryer’s elevator can be positioned in the socket and turned. The handle then serves as the axle and tip acts as the wheel and engages and elevates the root from the socket.

Principles of forceps use:

Goals of forceps use are 2 fold:

  1. Expansion of the bony socket.
  2. Removal of teeth from the socket.

There are 5 major motions that the forceps can apply to luxate and mobilize the tooth by expanding the bony socket.

  1. Apical pressure: Results in a minimal movement of the tooth in an apical direction and expansion of the tooth socket by the insertion of the beaks into the PDL space. Secondly, apical pressure with resultant bony expansion pushes the centre of rotation more apically which results in a greater expansion of the socket at the alveolar crest region when the forceps is moved. This prevents fracture of apical segment of the root and more ideal expansion of the socket.
  2. Buccal motion: Results in expansion of the buccal plate, particularly at the crest of the ridge. It is important to remember that this also lends to apical pressure and must not be excess or fracture will occur. Maxillary buccal bone is usually thinner and the palatal bone thicker, thus maxillary teeth are removed primarily by buccal pressure.
  3. Lingual motion : Similar to buccal motion but in lingual direction aimed at expanding the lingual crestal bone. Mandibular molars have thick buccal bone and thin lingual bone. Thus they are removed primarily by lingual force.
  4. Rotational motion: Rotates the tooth which causes some internal expansion of the bone. Teeth with single cervical roots like maxillary incisor and mandibular premolars are most amenable to luxation by this method.
  5. Tractional forces: Useful for delivering the teeth from the socket once adequate bony expansion is achieved.


Procedure for closed extraction:

An erupted root can be extracted in 2 major ways: closed or open.

Closed technique is also called as simple or forceps technique. The closed technique is the most commonly used one and given primary consideration for almost every extraction. The open technique is used when there is reason to believe that excessive force would be required or when substantial portion of the crown is missing and access to the root is difficult. For the tooth to be removed from the bony socket, it is necessary to expand the alveolar bony walls to allow the tooth/ root an unimpeded pathway and it is necessary to tear the periodontal fibres that hold the tooth in the bony socket. The use of elevators and forceps as levers and wedges can accomplish these objectives.

Five general steps in closed extraction procedure:

  1. Loosening of soft tissue attachment from the tooth:

This is done using the sharp end of a molts No. 9 or Woodson’s elevator. The purpose is two fold:

  1. Allow surgeon to assure both themselves and the patient that profound LA is achieved. Small amount of pressure will be felt but not a sensation of sharpness or discomfort.
  2. To allow the tooth extraction forceps to be positioned more apically without interference from or impingement on the soft tissue of the gingiva.

If a straight elevator is used to luxate the tooth, the mesial papilla is detached using the sharp end of the Woodson’s molts elevator, which allows the elevator to be placed directly onto the alveolar bone without crushing and injuring the papilla.

  1. Luxation of tooth with a dental elevator:

Usually a straight elevator is used. Expansion and dilatation of the alveolar bone and tearing of the periodontal ligaments ensure that the tooth be luxated in several different ways. The straight elevator is inserted perpendicular to the tooth into the interdental space and then turned so that the inferior portion of the blade rests on the alveolar bone and the superior portion of the blade is on the root of the tooth being extracted. With thumb pressure resting on the mesial tooth, strong, slow, forceful turning of the handle is done to move the tooth in a posterior direction, which results in tissue expansion of the alveolar bone. In some instances, the elevator can be turned in the opposite direction and more vertical displacement of the tooth will be achieved.

  1. Adaptation of the forceps to the tooth:

The proper forceps are then chosen for the tooth to be extracted. Beaks should be shaped to adapt anatomically to the teeth apical to the cervical line, on the root surface. Atleast a 2 point if not complete surface contact should be achieved. The forceps are then seated onto the tooth so that the tips of the forceps beaks grasp the root underneath the soft tissues. The lingual beak is usually seated first, then the buccal beak. Once the beaks have been positioned, the surgeon grasps the handles of the forceps at the very end to maximize mechanical advantage and control.

The beaks of the forceps must be held parallel to the long axis of the tooth so that forces generated by the application of the pressure are delivered along the long axis for maximal effectiveness in dilating and expanding alveolar bone. If beaks are not parallel, fracture of tooth / root may occur. The forceps are then forced apically as far as possible. This accomplishes 2 things. First, the beaks of the forceps act as wedge and expand crestal alveolar bone. Secondly, the centre of rotation is displaced towards the apex of the tooth with resultant increased effectiveness of bone expansion. At this point the surgeons hand should be grasping the forceps firmly, with the wrist locked and arm held against the body, the surgeon should be prepared to apply force with the shoulder and upper arm without any wrist pressure. He or she should be standing straight with the feet comfortably apart.

  1. Luxation of the tooth with the forceps:

The surgeon begins to luxate by using the motions described earlier. As the alveolar bone begins to expand, the forceps are reseated apically with a strong, deliberate motion; which causes additional expansion of the alveolar bone. Buccal and lingual pressure continue to expand the socket and for some teeth rotational motions are then used to help expand the tooth socket and tear the PDL attachment. The forces applied should be slow, firm and deliberate and not jenky. It must be remembered that teeth are not pulled from the socket but rather gently lifted from the socket once the alveolar process is sufficiently expanded.

  1. Removal of tooth from socket:

Once the alveolar bone has expanded sufficiently, a slight tractional force, usually directed bucco-occlusally is used. These should be minimal and result in removal of the tooth from the socket.

Role of opposite hand:

The opposite hand plays an active role in the procedure. It is responsible for reflecting the soft tissues of the cheeks, lips and tongue to provide adequate visualization. It helps to protect other teeth from the forceps. It helps to stabilize the patients jaw during the extraction. It is often necessary to apply significant pressure to expand heavy mandibular bone and such forces can cause discomfort and even injury to the TMJ unless they are counteracted by a steady support of the mandible. Finally, the opp hand supports the alveolar process and provides tactile information to the operator concerning the expansion of the alveolar process during luxation and tooth extraction.


Post extraction care of the socket:

Socket should be debrided if necessary. If there is a periapical lesion visible on the radiographs, the periapical regions should be carefully curetted to remove the granuloma or cyst. Any debris in the socket like calculus, bone or root fragments etc. should be gently removed with a curette or suction tip. However vigorous and excess curettage of the socket produces unnecessary injury and may delay healing. The expanded cortical plates should be compressed with gentle pressure, which prevents bony undercuts from forming and improves healing. Excess granulation tissue if present is removed, bony margins are trimmed and a moistened gauze pack is placed so that when the patient bites his teeth together, it fits into the space previously occupied by the crown of the tooth. This pressure results in haemostasis and should be kept for half an hour.

Odontectomy and tooth division:

Odontectomy is the surgical removal of a tooth or teeth by the reflection of an adequate mucoperiosteal flap, removal of an overlying bone and also bone between the buccal roots of molars by means of chisels, burs and / or rongeurs. After the removal of bone, in many cases, tooth division is indicated. In tooth division, one or many roots are separated from the crown by cross-cut fissure burs or the crown is completely separated from the roots and the roots are then cut apart. This is followed by application of elevators or forceps for the extraction of the crown and then the roots.

The advantage of odontectomy are: the reduction in the number and incidence of fracture crowns or roots during extraction, less danger of oro-antral fistulation or injuring neuro-vascular bundles, less possibility of fracture of mandibular or maxillary and less incidence of tearing out large areas of cortical and cancellous bone with the tooth during extraction.

Indications for odontectomy and tooth division:

  1. Hypercementosis of rests.
  2. Widely divergent roots.
  3. Locked roots – where the roots curve towards each other and touch or nearly touch such that a portion of bone is locked between the roots.
  4. Teeth with dilacerated root tips.
  5. Teeth with post crowns.
  6. Extensively decayed teeth, particularly with those with deep gingival cavities.
  7. RCT treated teeth.
  8. When a thick, dense buccal or labial cortical plate or multinodular exostasis is present on the maxilla or mandible.
  9. When a low antral floor dips between the buccal and lingual roots of the maxillary molars.
  10. When the maxillary alveolar tuberosity is hollowed out by extension of the antral cavity.
  11. Thin mandible with bone, standing teeth which excess forces will be required – fracture of mandible.
  12. Malposed, impacted, unerupted supernumerary teeth.
  13. When the forceps pressure that was used so great that dislocation of the condyles has occurred.
  14. Ankylosed roots.
  15. Variant root pattern that will lead to fracture of roots during normal forceps procedure.
  16. Where the customary force fails to produce any luxate.

 

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Author:

I am a practicing maxillofacial surgeon working in India.

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