14

Exodontia

Hazel J. Fraser

Introduction

Exodontia is the subject of extraction of teeth or parts of them. It also includes the techniques used in the extraction of teeth.

The current legal position for dental therapists in the United Kingdom is that they are permitted to extract primary (deciduous) teeth only and they can only be extracted using local analgesia. Student dental therapists can extract primary (deciduous) teeth under general anaesthesia with direct supervision from a registered dentist. This is in order to gain practice in extracting primary teeth. If primary teeth are extracted when the patient is sedated then a registered dentist must be present in the room.

Indications for tooth extraction

A study by Alsheneifi and Hughes (2001) showed that first primary molars were the most common tooth type extracted and comprised 30% of teeth removed. Central incisors were the next most common tooth type extracted and accounted for 25% of extractions.

It may be considered necessary to extract primary teeth because of:

• Caries: In a study by Tickle et al. (2002) it was found that 44% of primary teeth which were carious or had received an intervention of some kind were extracted, however only 12% were extracted due to pain or sepsis.
• Pain.
• Sepsis: This may be either chronic or acute e.g. acute abscess with cellulitis.
• Trauma: Up to 30% of children up to 7 years of age sustain injury to primary incisors, including crown fracture, root fracture, tooth avulsion, and dental displacement.
• Failed restorative treatment: research by Milsom et al. (2002) suggests that the risk of carious primary molars being extracted is similar whether these teeth receive restorative care or not.
• Periodontal disease: This is an uncommon reason for extraction in children.
• Altered eruption pattern: Most infraoccluded and ankylosed primary molars with a permanent successor will exfoliate normally; therefore the usual treatment recommendation is to await normal exfoliation and then eruption of the permanent successors. Retained primary teeth can be extracted as part of an orthodontic treatment plan.
• Misplaced primary teeth, natal and neonatal teeth: Although rare, teeth present when the baby is born can interfere with the baby’s nutrition. The decision to extract should take into consideration the trauma to the child’s oral tissue or mother’s breast, mobility of the tooth, the danger of inhalation and the potential orthodontic effects of tooth loss.
• Overcrowding: A study by Kau et al. (2004) showed that there was a reduction in lower incisor crowding as a result of lower primary canine extraction. However, arch perimeter decreased more in those patients who had extractions, leaving less space for the eruption of the lower permanent canines.
• Poor co-operation of the patient during restorative treatment can lead to extractions as an alternative method to the removal of disease from the patient’s mouth.
• Medical history: If the patient has a medical condition and the teeth are carious then extractions may be indicated.
• A negative attitude regarding restorative treatment from the parent or patient may influence the decision to extract.
• Insufficient tooth structure may make satisfactory restoration impossible or impracticable.
• Pulpal involvement which might involve more than one tooth could make extraction the preferred treatment option.

Contraindications for tooth extraction

• Medical history: Certain medical conditions such as blood dyscrasias or renal disease may be a contraindication to extractions. Healing can be prolonged in diabetic patients or patients suffering from malignancy such that a restorative approach may be the preferred option.
• Space maintenance: If a primary tooth is extracted early then the remaining teeth may drift mesially or distally closing the space for the permanent successor. This may prevent its eruption into the correct position resulting in a subsequent malocclusion.

Relevant anatomical structures

The teeth of the primary dentition are situated in the alveolar bone of the maxilla and mandible and as such are not closely related to any major anatomical structures. However, the difficulty of an extraction can be significantly influenced by the presence and position of the developing permanent teeth. This is particularly the case with the developing first and second premolars where the crowns of the teeth are closely related to and enveloped by the roots of the primary molars. Injudicious extraction can therefore result in the dislodgement of the permanent successor.

The eruption dates of primary teeth are described in Chapter 12, p. 245.

Nerve supply

It is important to remember that when extracting primary teeth, the innervation of not only the teeth but also the supporting structures needs to be considered. The relevant nerve supply is described below; however the relationship of the nerves to various anatomical structures in the adult is described in more detail in Chapter 10, p. 209–210.

All the primary dentition is supplied by the trigeminal (Vth) cranial nerve; its maxillary nerve trunk supplying the maxillary primary dentition and the mandibular nerve trunk supplying the mandibular dentition. These two trunks further subdivide as follows:

The upper anterior primary incisors and canines and the labial gingivae are supplied by the anterior superior alveolar nerve branch; the palatal gingivae are supplied by the nasopalatine (long sphenopalatine) nerve and the soft palate and uvula are supplied by the lesser palatine nerve.

The upper primary molars are supplied by the middle superior alveolar nerve, which also supplies the buccal gingivae whilst the palatal gingivae are supplied by the greater palatine nerve.

The nerve supply to the primary mandibular teeth is the inferior alveolar nerve; a branch of the mandibular trunk of the trigeminal nerve. The buccal gingivae and mucosa are supplied by the mental nerve, a branch of the inferior alveolar nerve. The lingual gingivae and mucosa are supplied by the lingual nerve. A more detailed description can be found in Chapter 1, p. 19.

Preparation of the patient

Prior to embarking on the extraction of a primary tooth, it is important to address the preoperative medical and psychological management and care of the patient. The following points need to be considered:

• Medical history. This needs to be checked and confirmed particularly with respect to a history of bleeding, blood dyscrasias, etc.
• Consent. Consent must be given by both the patient and the parent or guardian before extraction of teeth. The consent must be obtained both orally and in writing.
• Prescription. This must be written by a registered dentist who has examined the patient and is included as part of the treatment plan.
• Confirmation with the patient and parent/guardian that there is agreement with the tooth or teeth prescribed by the dentist for extraction. Any uncertainty must be clarified.
• An explanation to the patient and the parent/guardian as to what the procedure involves and how it will be carried out.
• Appropriate protection of the patient. There should be adequate protection of the patient’s clothing together with appropriate eye protection. The operator should also have appropriate protective clothing (see Chapter 8, p. 164).
• Non-pharmacological behaviour techniques that can be used for the management of an anxious child are: behaviour shaping, tell/show/do, reinforcement, desensitisation, modelling and hypnosis. These and other methods of behaviour management which might apply to any operative dental treatment on a child are fully described in chapter 12, p. 262–263.

Obtaining local analgesia

Topical analgesia

Prior to an injection of local analgesia in children it is wise to use a topical analgesic. Preparations include:

• 10% lidocaine hydrochloride spray.
• 5% lidocaine hydrochloride gel.
• 20% benzocaine gel.

The gel preparation is easier to apply than sprays and can be more easily localised. Sprays can affect unwanted areas in the mouth and because the taste may not be well tolerated by the patient it should be sprayed on to cotton wool before placing in the mouth. Benzocaine gel is flavoured with attractive tastes such as bubble gum, and so is more popular with children.

Topical analgesics penetrate keratinised mucosa poorly. They are much more effective on non-keratinised mucosa. This means that they are less effective on palatal mucosa and attached gingivae. The topical analgesic should be applied to as small an area as possible. This reduces potential toxicity and prevents excessive numbness in the tongue and soft palate which may be unpleasant for the child. Adequate time (approximately 2–3 minutes) should be allowed for the topical analgesic to take effect before embarking on infiltration analgesia.

Infiltration analgesia

The positioning of the local analgesic is crucial to achieving adequate analgesia. Failure to achieve this will result in both loss of confidence and loss of co-operation by the patient. An aspirating syringe should be used for all local analgesia (see Chapter 10).

Maxilla

Buccal infiltration

The needle should be inserted into the free gingivae, just above the attached gingiva of the tooth to be anaesthetised. This is achieved by retracting and holding the cheek or lip taut to improve access and visibility and increase patient comfort. The apices of the primary teeth lie near to the point of needle insertion.

Palatal infiltration

Prior to undertaking a palatal infiltration, it may be necessary to carry out a transpapillary injection. The needle is inserted from a buccal approach into the papillae, mesially and distally to the tooth being extracted. The needle is advanced while depositing a small amount of local analgesic solution. Blanching of the mucosa will be seen palatally at the gingival margin.

The palatal infiltration should now be less uncomfortable for the patient. The needle is inserted at right angles to the mucosa at the apex of the tooth to be extracted. This is approximately 5–7 mm from the gingival margin.

Mandible

Buccal infiltration

Infiltration techniques are generally used, (unlike block injections which would normally be necessary in adults) as the alveolar plate is perforated by many vascular canals. The same principles apply as to the maxilla. If analgesia cannot be obtained with a buccal infiltration then an inferior dental block injection may be necessary (see Chapter 10, p. 213).

Lingual infiltration

This may be achieved using a transpapillary injection followed by lingual infiltration if necessary.

The most common choice of analgesia for children is 2% lidocaine hydrochloride with 1:80 000 epinephrine (adrenaline), 3% prilocaine (Citanest) with felypressin or 4% articaine with 1:100 000 epinephrine (adrenaline). The dosage is influenced by age and body weight as described in Chapter 12, p. 265. Epinephrine (adrenaline) and felypressin are added as vasoconstrictors to reduce the dispersion of the local analgesic and thereby localise and prolong the analgesia. They also reduce postoperative bleeding and systemic toxicity. The manufacturer’s instructions and current clinical guidelines should always be followed.

Clinical assessment

Prior to embarking on the extraction of a tooth or root, the operator should attempt to assess the degree of difficulty which is likely to be anticipated. Therefore the following factors should be considered:

• Ease of access. Children have small mouths and primary molars can present greater access problems than teeth in the anterior part of the mouth.
• Degree of mobility. Anterior teeth are generally easier to remove than primary molars. Ankylosis (the fusion between cementum and/or dentine and alveolar bone) is more common in the mandible than the maxilla and more common with first molars than second molars. An ankylosed tooth tends to appear less erupted and tends to occupy a more inferior position in relation to the occlusal plane when compared to the adjacent teeth and tooth extraction can be significantly more difficult.
• Extent of tooth breakdown. Heavily carious teeth tend to have fragile crowns which can easily fracture during extraction.
• Co-operation of the patient. Successful extraction under local analgesia requires a high degree of cooperation by the patient.

Extraction instruments

Forceps and elevators are the two types of instruments used for the extraction of primary teeth. They are all made to conform to International Organization for Standardization (ISO) specifications. A surgical approach must be taken when extracting teeth and therefore the instruments used should have been autoclaved and be sterile immediately prior to use.

Forceps

The choice of forceps depends on the morphology of the tooth, its root anatomy, the number of roots (Table 14.1), and its location in the mouth.

The forceps available are shaped to accommodate these factors. Forceps are manufactured specifically for the extraction of primary teeth and are smaller than those used for the extraction of permanent teeth (Figure 14.1).

The upper arch

Forceps used for extracting teeth in the upper arch have the handles in the same long axis as the blades although the handles of upper molar forceps are slightly sigmoid to allow the beaks to align with the long axis of the molar teeth. The blades of forceps used to extract anterior teeth (incisors and canines) and retained roots have rounded tips. Shorter-bladed forceps can be used for the canines since they have bulkier roots than the incisors. The molar forceps have two broader blades, one of which is pointed or beaked. Because of the morphology of the upper primary molar teeth in that they have two buccal roots, it is necessary to have forceps designed specifically for either the left or right molars (i.e. upper right forceps for the patient’s right side and left forceps for the patient’s left). The forceps have a beaked blade and a smooth blade. The beaked blade is designed to fit into the />

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