Description
- Amongst the most common claim against anaesthetist. Damage can occur from laryngoscopy, hard suction catheters, and the insertion, removal, or biting on emergence of the airway device or oral airway.
- The incidence increases in patients with pre-existing dental disease, difficult and emergent intubations, or the skill of the laryngoscopist.
- Types of damage include avulsions (complete removal), damage to crowns and bridges, dislocation, and fractures.
Epidemiology
Incidence
- Damage is difficult to assess due to inconsistent reporting or recognition; ranges from 0.02% to 12.1% (1).
- Dental injury requiring dental intervention is estimated to occur in 1:4,500 anesthetics (1).
- Damage in the setting of:
- Difficult intubation: 20% of all cases
- >2 laryngoscopy attempts: 1–4%
- Trainees/level of training: Surprisingly incidence amongst residents is lower than "experienced" hands (1,2,3)
- Damage during:
- Intubation: 50–75%
- Extubation or recovery room: 9–20% (2)
- Maxillary incisors (#8, #9) are most commonly injured.
- Types of damage:
- Enamel fractures and partial dislocation: 55.2%
- Avulsion: 9%
- Crown fracture: 7.7% (3)
Etiology/Risk Factors
- Laryngoscopy in the setting of:
- Difficult intubations; small mouth opening, prominent upper teeth, poor neck mobility, large neck, and small thyromental distance
- Emergency intubations
- Pre-existing dental condition; caries, periodontitis
- Restorations, prosthetics; synthetic materials may not be as "hard" as natural enamel (1,2,3).
- Traumatic insertion, removal, or biting of the airway device or oral airway
- Hard suction catheters
- There are 16 maxillary teeth and 16 mandibular teeth. The Universal Numbering System provides a method to identify teeth: Maxillary teeth are #1–16 and mandibular teeth are #17–32.
- The tooth is composed of a crown (enamel and dentin) and the root (cementum and pulp):
- Enamel is the exposed portion of the tooth. It is composed of mineralized substances and is the hardest substance in the human body.
- Dentin lies directly underneath and is softer than enamel. However, it functions to provide a foundation or framework.
- Cementum is a specialized bony substance covering the root of a tooth. It functions in providing a substance to which the periodontal ligaments can attach to.
- Pulp is the innermost portion. It contains nerves and blood vessels and connects to the gums.
- The periodontium is composed of the periodontal ligaments, gingiva, and alveolar bone.
- Laryngoscopy: Blades attached to a handle are utilized to displace the tongue and epiglottis in order to insert the endotracheal tube. They are composed of metal and are inflexible and noncompliant. Optimal patient positioning and laryngoscopy technique aim to align the oropharynx, hypopharynx, and larynx in order to attain direct visualization of the glottis opening.
- In the event that this alignment is not, or cannot, be achieved, the laryngoscopist may be more likely to "crank" the wrist and utilize the maxillary teeth (maxillary central incisors #8, #9) as a fulcrum.
- In addition to the vulnerable location during laryngoscopy, teeth #8 and #9 are single rooted and have a small cross-sectional area.
- These 2 incisors are estimated to be involved in >90% of reported instances of dental damage.
- Airway devices: Endotracheal tubes, laryngeal mask airways, bite blocks, and oral airways can cause damage during insertion, removal, or biting during emergence.
- Pre-existing dental conditions increase the risk of dental injury.
- Cavities or caries consist of a bacterial process that causes rotting of the root.
- Periodontal disease consists of gingival inflammation, alveolar bone loss, and tartar build-up.
- Restorations and prosthetics increase the risk of dental injury:
- Bridges: Replacement of one or more missing teeth. A pontic is fused between 2 porcelain crowns to fill in the space left by the missing teeth.
- Bonding: Restoration of decaying teeth or cosmetically improving teeth (discoloration, abnormal shapes, small gaps). A composite resin filling is applied to the anterior face of the tooth, followed by a bonding material that can be shaped or colored to achieve the desired result.
- Veneers: Improvement cosmetically of discolored, worn, chipped, or misaligned teeth
- Crowns: Coverage of the visible surface of a decayed or worn-down tooth in order to reduce further wearing down
- Pulmonary aspiration of foreign body: Detection requires identification of the event. Any missing tooth should be assumed to have been aspirated until proven otherwise. A chest radiograph can identify the presence and location.
Prevantative Measures
- Preoperative evaluation and assessment of the airway should include the dentition:
- Loose teeth
- Chips
- Fractures
- Restoration or prosthetics (crowns, bridges, veneers, bonding)
- Periodontal disease
- Documentation preoperatively: If pre-existing dental disease is present, the patient should be informed and findings should be confirmed with the patient. Documentation should include a careful description of the preoperative evaluation record.
- Consent: Anesthesia consent should include a verbal discussion, followed by a written consent that is signed by the patient or their designated caretaker/power of attorney regarding the possibility of dental injury. More time or attention should be given to those with pre-existing dental disease or anticipated difficult intubation.
- Alternative airway management:
- Anticipated difficult intubation: May be prudent to preemptively utilize special airway management tools such as fiberoptic bronchoscopy, indirect laryngoscopy tools (GlideScope, etc.), laryngeal mask airway guided intubation, etc. If laryngoscopy is to be attempted, consider special angulated blades (McCoy, Belscope), plastic blades, or blades with soft heels.
- Unexpected difficult airways: Consider alternative devices early to avoid repeated laryngoscopy attempts and fulcruming the laryngoscope.
- Standard and routine laryngoscopy: Should avoid teeth with gentle insertion and advancement. Proper patient positioning (head, neck, shoulder rolls, ramps), pre-oxygenation ("buys time" before desaturation), and avoidance of "cranking" the wrist should always be performed.
- Tooth guards: Routine use is controversial. They may impair visualization, insertion of the endotracheal tube, or increase apneic time. One study demonstrated that insertion increased intubation time by 7 seconds (statistically significant) (4).
- Insertion and removal of airway devices and bite blocks should always be done gently. Laryngeal mask airways have a thicker diameter and are less compliant than endotracheal tubes. Avoid forceful pulling and removal of items while the patient is biting (downward movement).
- Soft bite blocks constructed from gauze may reduce damage from biting of the endotracheal tube. Consider utilizing when motor evoked potentials are being performed.
- Dental consultation and treatment prior to surgery for dentition "at risk" for avulsion or further damage may prevent or reduce the incidence of damage. If this is not feasible, one technique that has been suggested is the wrapping of suture around the gingival margins several times and taping the other end to the cheek.
- Studies have suggested that despite careful attention to poor dentition, the risk of dental lesions cannot be completely eliminated.
Outline