Exodontia: Extractions & Impactions MCQ

Removing a tooth is applied mechanics. The goal of every extraction is to expand the bony socket and sever the periodontal ligament so the tooth can be delivered with controlled force, not brute force. Forceps grasp and expand, elevators luxate using the lever, wedge, and wheel-and-axle, and the movements are matched to the root anatomy (rotation only where a single conical root allows it). When a tooth will not come by a simple closed technique, a surgical approach uses a flap, bone removal, and sectioning. Impacted teeth, especially third molars, add their own classifications and the all-important assessment of the inferior alveolar nerve and maxillary sinus before the tooth is touched.

Indications and Contraindications

• Common indications for extraction include a nonrestorable tooth (gross caries or fracture), severe periodontal disease with hopeless prognosis, symptomatic or pathologic impactions, teeth in the line of a fracture, and removal for orthodontic or prosthetic reasons.
• Most contraindications are relative rather than absolute: uncontrolled systemic disease (managed first), and a history of radiation to the jaws, which raises the risk of osteoradionecrosis.
• Acute infection (such as severe pericoronitis or a spreading infection) may warrant addressing the infection first, though removing the source is often part of the solution.
• The decision to extract weighs restorability, the patient's medical status, and the alternatives, after the medical risk assessment is complete.

Instruments: Forceps and Elevators

• Forceps grasp the tooth at the cementoenamel junction and root and are used to expand the socket and deliver the tooth; the beaks are shaped to adapt to specific teeth and roots.
• Elevators are used to luxate (loosen) the tooth, often before forceps are applied, by applying force against the bone and tooth using mechanical advantage.
• A periosteal elevator is used to reflect a mucoperiosteal flap in surgical extractions, separating the soft tissue from the bone.
• Choosing instruments adapted to the tooth, and using elevators to luxate first, makes the delivery controlled and reduces the force needed.

Mechanical Principles and Extraction Movements

• Elevators work by three mechanical principles: the lever (a first-class lever for mechanical advantage), the wedge (driven between the tooth and bone to displace the tooth), and the wheel-and-axle (rotational force).
• Extraction force does two things: it expands the bony socket and severs the periodontal ligament, allowing the tooth to be delivered.
• Movements combine apical pressure with buccolingual (labiolingual) rocking; rotational movement is reserved for teeth with a single, straight, conical root (the classic example is the maxillary central incisor).
• Multirooted or curved-rooted teeth are not rotated, because rotation would fracture the divergent or curved roots.

Simple versus Surgical Extraction

• A simple (closed) extraction removes the tooth with forceps and elevators without raising a flap, suitable for an erupted, intact, accessible tooth.
• A surgical (open) extraction raises a mucoperiosteal flap and may remove bone and section the tooth; it is used for impacted teeth, ankylosed teeth, badly broken-down or root-tip remnants, and teeth with divergent or curved roots.
• Sectioning divides a multirooted tooth into single-rooted segments so each root can be delivered along its own path of withdrawal, reducing the force and fracture risk.
• Surgical flaps are designed with a broad base (to preserve blood supply), are full-thickness mucoperiosteal, and are planned to avoid vital structures and allow tension-free closure.

Impacted Teeth

• Third molars are classified by angulation: mesioangular (the most common), distoangular (often the most difficult to remove because it tips away from the path of withdrawal), vertical, and horizontal.
• The Pell and Gregory classification describes a lower third molar by its relationship to the ramus (class 1, 2, 3) and its depth relative to the second molar (level A, B, C).
• The maxillary canine is the second most commonly impacted tooth; impacted canines are often surgically exposed for orthodontic alignment rather than extracted.
• Before removing a lower third molar, the proximity of its roots to the inferior alveolar nerve is assessed (panoramic, and CBCT when indicated), and for an upper third molar, proximity to the maxillary sinus.

Socket Healing

• The extraction socket heals in a sequence: a blood clot forms, is replaced by granulation tissue, then by woven bone, which finally remodels into mature bone.
• A surgical flap is closed and heals by primary intention, while the open socket itself heals by secondary intention.
• Preserving the blood clot is essential to normal healing, which is why patients are instructed to avoid vigorous rinsing, sucking, and smoking early on.
• Loss or breakdown of the clot leads to the painful complication of a dry socket, which is taken up in the complications module.