Lecture 11: Extractions II

How should you create a flap for an extraction of the maxillary 4th premolar?

• Create a triangle (3-corner) mucogingival flap.

• Ensure preservation of structures exiting infraorbital anal mesially and the parotid salivary duct distally.

• The base of the flap should be about twice as large as the area you will be covering

• Be mindful of the location of the parotid and zygomatic salivary ducts!!

How do you divide the roots of the maxillary 4th premolar?

• Section the distal root from the two mesial roots using a crosscut fissure bur through furcation.

• Make a V-notch to allow better access for the elevator.

• Section the mesiobuccal root from the mesiopalatal root using a crosscut fissure bur

What root is being sectioned off here on the maxillary 4th premolar?

mesiobuccal root

What are the indications and contraindications of crown amputations in cats?

Indications:

• Type 2 Tooth Resorption

• Where the root has been so resorbed that no PDL is present

Contraindications:

• Type 1 tooth resorption

• Teeth with endodontic disease

When may leaving root fragments be considered?

should patient be at high risk IF tooth <4mm, patient is unstable under anesthesia, and/or high risk of damaging surrounding structures

What are the common causes of fractured root tips?

• Too aggressive elevation - impatience.

• Insufficient buccal bone removal - Apically, mesially, or distally.

• Ankylosed roots / hypercementosis/dilacerated roots.

• Incomplete sectioning of multi-rooted teeth.

How do you prevent fractured root tips?

• Judicious elevation – slow down and be patient.

• Remove enough bone – esp. if the tooth is periodontally sound.

• Radiograph prior to extractions to evaluate periodontal ligament space.

What are the consequences of not removing fractured root tips?

• Pain.

• Infection from pulp necrosis within the pulp of the retained root tip.

• This risk is higher in teeth affected by endodontic or periodontal disease.

How are fractured root tips removed?

• take rads with multiple view to confirm location, adjacent structure, and pathology with surrounding bone

• visualize root tip and use surgical extraction technique

• create adequate exposure - remove more buccal bone if possible → find periodontal space

• outline perimeter of root to create a gutter around root

What are these tools?

left: root tip pick

right: root tip extraction forceps

What are common spaces that fractured root tips are accidentally displaced to?

• nasal cavity

• maxillary recess (palatal to PM4 in dogs)

• mandibular canal

• retrobulbar space

How do you prevent displaced fractured root tips?

• Remove enough alveolar bone and use cylindrical diamond bur to visualize the root tip.

• Carefully elevate root tip without excessive apical force.

• Don’t blindly elevate down in the apical alveolus.

• Don’t attempt to pulverize the root tip with a high-speed bur.

How do you respond if you displace a fractured root tip?

• If displaced into the mandibular canal, carefully remove additional bone to be able to visualize root tip.

• Be careful to avoid the neurovascular bundle in the mandibular canal.

• Can use suction with a red rubber catheter to attempt to retrieve the root tip.

• Root tips displaced into the nasal passages should be referred to a dental specialist.

Occasionally, alveolar bone may fracture due if excessive force is applied during elevation or with the use of extraction forceps without sufficient elevation. What do you do if this happens?

remove loose bone fragments and smoothen rough bony surfaces with a diamond bur

When is iatrogenic mandibular fractures at highest risk?

• during extraction of mandibular canine tooth of dogs or cats or the 1st mandibular molar tooth in small breed dogs (disproportionally large in comparison to size of mandible)

• teeth disease by periodontal or endodontic disease

What structures are at risk of damage when operating on the maxillary 4th pre-molars and the 1st and 2nd maxillary molar extractions

optic nerve, autonomic innervation to the eye, maxillary artery, maxillary branch of the trigeminal nerve, infraorbital nerve, penetration of the retrobulbar space and brain

How do you prevent iatrogenic trauma to adjacent anatomic structure when extracting teeth?

• Be familiar with regional anatomy.

• Use appropriate elevation technique.

• Short finger stops.

• Gentle and patient elevation.

What are the keys to a tension-free closure of a gingival flap to prevent dehiscence?

• creation of a well-designed, wide-based mucoperiosteal flap and release of the periosteum

• A good rule of thumb is that the base of the flap should be 2x the size of the defect area you are trying to close

What is a potential complication of maxillary canine tooth extraction, most commonly seen in cats? What are the consequences of this?

lip entrapment → can result in an ulcer

How is lip entrapment avoided?

by paying close attention to flap positioning and by not removing excess bone during extraction of the maxillary canine tooth

How is an oronasal fistula associated with maxillary canine teeth repaired?

• perform a horizontal releasing incision by gently incising the periosteal layer of the flap at its base

• use diamond bur to smooth any rough portions of alveolar bone

• flush and freshen edges of gingival margin

• single-layer mucoperiosteal flap

Why should you NOT put bone grafting material in the defect when repairing an oronasal fistula?

nothing you can do to replace the lost bone → they will sneeze out bone graft material

Why should sutures be positioned over bone rather than over the fistula during ONF repair?

• Protects and support the suture line and help provide a blood supply for healing.

• Placing the suture line directly over the fistula subjects the sutures to excessive forces when the patient sneezes.

• To achieve this goal, a crescent-shaped section of palatal soft tissue must usually be removed prior to closure.

• This requires that the flap be longer to close the defect, but ensures suture placement over bone