Principles of Exodontia

Exodontia services comprise the largest portion of clinical practice for most oral and maxillofacial surgeons in the United States. This article is an overview of the principles of exodontia including the physics principles underlying the appropriate use of dental elevators and forceps. Failure to understand the instrumentation and the physics principles being used can cause prolonged operative time, iatrogenic injury to the patient, and unnecessary fatigue and/or injury to the provider. Advances in materials, technology, and innovative design have produced interesting new instruments for exodontia. New instruments including periotomes, piezosurgery, physics forceps, and vertical extraction systems are introduced and reviewed.

Key points

  • Exodontia services comprise the largest portion of clinical practice for most oral and maxillofacial surgeons in the United States.

  • This article is an overview of the principles of exodontia including the physics principles underlying the appropriate use of dental elevators and forceps.

  • New instruments including periotomes, piezosurgery, Physics Forceps, and vertical extraction systems are also introduced and reviewed.

The most common procedure performed by most oral and maxillofacial surgeons is extraction of decayed or impacted teeth. According to the National Institute of Dental and Craniofacial Research, 92% of US citizens age 20 to 64 have had dental caries in their permanent dentition, with 26% of adults in this age range with current untreated caries. Many patients require one or more extractions throughout their lifetime because of impaction, caries, periodontal disease, fracture of teeth from mastication or previous dental procedures, and failed root canal therapy. The ideal principles of exodontia should allow the efficient, effective, and safe removal of teeth with a primary focus on minimizing complications and maximizing comfort for the patient and provider. Failure to understand the instrumentation and the physics principles being used can cause prolonged operative time, iatrogenic injury to the patient, and unnecessary fatigue and/or injury to the provider. This article reviews the principles, techniques, and instrumentation of exodontia, and presents new instruments being currently marketed for exodontia.

Preoperative assessment

Before any surgical procedure, a thorough history and physical examination must be completed. Although most patients can safely undergo basic exodontia procedures, medical history and current medications can allow the surgeon to anticipate and avoid intraoperative and postoperative complications including bleeding issues, bone and/or soft tissue healing issues, and the best pain management strategy for the individual patient. This assessment also includes forecasting the specific instrumentation that may be needed for the procedure. Communication of the need for special instrumentation or hemostatic agents to the surgical team maximizes procedural efficiency. The examination process also includes diagnostic radiographs of the teeth requiring removal to confirm necessity of removal and to assess for possible complications. The radiograph also allows the patient to visualize the teeth that are to be removed, and to participate in the informed consent process by seeing the structures that may be at risk, such as the maxillary sinus cavity, the inferior alveolar nerve canal, or adjacent restorations.

The use of cone beam computed tomography (CBCT) scan by oral and maxillofacial surgeons has become increasingly popular in the United States. Although most patients having routine exodontia do not require CBCT, CBCT may be indicated when impacted mandibular wisdom teeth are in close proximity to the inferior alveolar canal. Matzen and Wenzel performed a comprehensive and well-designed review of the efficacy of CBCT before mandibular wisdom tooth extraction. They found a paucity of randomized controlled trials in their review of more than 300 articles, and ultimately concluded that periapical and panoramic imaging is sufficient for most patients undergoing wisdom tooth removal. However, they did find that CBCT may be indicated if traditional imaging suggested high risk of inferior alveolar nerve proximity, and that the CBCT would change clinical decision making, such as performing coronectomy instead of extraction.

Instrumentation/staffing

The instrumentation necessary for successful dental extractions includes optimal lighting, suction, and proper retraction of the soft tissue. A well-trained assistant is a critical component to any successful procedure by providing suction, irrigation, and anticipating instrument needs as the procedure progresses. The assistant can also serve as a last line of defense for verification of correct patient, procedure, allergy profile, consent completion, and preprocedural sedation requirements (eg, NPO status, adult driver). The value of a formal “time-out” checklist and strict adherence of the surgical team to the checklist cannot be understated.

Patient positioning is important for visualization of the surgical field by the entire surgical team and for the appropriate posture of the surgeon. Patient positions that cause unnecessary bending or twisting of the neck or back can cause significant disability for the surgeon over time.

Dental elevators come in a wide array of designs to facilitate luxation of the tooth. However, the forces applied to the tooth are encompassed by three principles of physics: (1) a lever, (2) a wedge, and (3) a wheel. It behooves the oral and maxillofacial surgeon to understand these principles to maximize the effectiveness of the elevators, while minimizing excessive or ill-directed force. The goal of the dental elevators is to luxate the tooth in a manner that disrupts the periodontal ligament, thus allowing removal of the tooth with a forceps.

The elevator is used as a wedge when the thin sharp edge of the instrument is directed parallel to root surface with apical force. This transects the periodontal ligament, but also expands the periradicular bone laterally, and displaces the tooth coronally.

The elevator is used as a class I lever (fulcrum located between the source of effort and the source of resistance) when the tip of the instrument is placed between the bone and the root surface using the crest of the alveolar bone as a fulcrum ( Fig. 1 ). The longer the lever arm, the greater the force that is generated by the working end of the elevator. A stable purchase point on the tooth is necessary to allow the force to be adequately applied to the tooth. If the tooth has significant caries, a trough or sectioning of the tooth may need to be completed to achieve a purchase on stable tooth structure. Another technique is to create a purchase point on the tooth with a drill to allow the use of a Crane pick to be used as a lever.

Fig. 1
Class I lever.

Finally, the elevator (particularly the Cryer-type elevators) is used as a wheel and axle. With a Cryer elevator, the handle acts as an axle, and the working end of the elevator acts as a wheel to generate increased force and arc of rotation to elevate a root. This is primarily used in the mandibular molar region.

Often, a combination of all three physics principles are used simultaneously to wedge the elevator as apical as possible for optimum purchase/fulcrum, then apply lever and rotational forces to the tooth to quickly and efficiently extract the tooth. The development of a feel for the correct application of these forces is critical and must be carefully and continually reassessed as surgeon skill develops. With time, one can quickly assess by feel whether the tooth can be successfully elevated, or whether the use of a drill would be most effective.

Dental forceps also have a multitude of designs to adapt to the specific teeth that they are being used on. The fundamental principle of the forceps is as a lever; however, some designs also create a wedge effect (eg, #23 forceps or forceps with thin beaks). As with the elevators, prudent use of force is key to avoiding complications. The lever that is created by the conventional forceps is that of two type I levers connected by a hinge. In this configuration, the hinge is acting as the fulcrum with the handle being the long lever and the beaks being the short lever.

Perhaps the greatest advance in modern exodontia is the drill. The modern surgical drill is a sophisticated instrument that creates high-speed, high-torque rotation of the bur that can function in the presence of water and blood and withstand repeated sterilization cycles. The drill allows for efficient removal of cortical bone and sectioning of teeth. The liberal use of irrigation to minimize overheating and subsequent necrosis of surrounding bone is critical. Adequate lighting, retraction, and suctioning is important to avoid iatrogenic injury to adjacent tissues. The impact of the surgical drill on the efficiency of office-based exodontia cannot be understated and is an invaluable surgical tool. The use of the drill allows significant mechanical advantage by allowing apical position of the elevators, increased purchase, and dividing of multirooted teeth.

Novel instrumentation/extraction techniques

Advances in materials, technology, and innovative design have produced interesting new instruments for exodontia. Here we review some of the new products that have been marketed.

Physics Forceps

The Physics Forceps (GoldenDent, Roseville, MI) uses a class I lever by placing a bumper in the buccal vestibule and a thin beak on the lingual aspect of the tooth. Constant pressure is then applied for several minutes to the tooth, which elevates the root from the socket 1 to 3 mm. Per the manufacturer, the combination of the lever arm combined with release of hyaluronidase within the periodontal ligament space causes release of the periodontal ligament. The tooth can then be removed with rongeur or other tooth forceps. The manufacturer claims that the forceps provides atraumatic extractions that minimize root or alveolar bone fractures and preserves surrounding bone. Fig. 2 shows the instrument design, and Fig. 3 shows how the forceps is positioned to create a class I lever. El-Kenawy and Ahmed compared the Physics Forceps with conventional forceps with regard to incidence of root, crown, and buccal plate fracture. The authors found a significant reduction in incidence of crown and root fracture with the Physics Forceps. The design of the Physics Forceps replaces the buccal beak on a traditional forceps with a rubber bumper that seats against the soft tissue deep in the vestibule. This creates a significant mechanical advantage with the class I lever analogous to using the claw of a hammer to remove a nail from a board. The manufacturer intends for the forceps to be used with gentle constant pressure applied over several minutes in contrast to traditional forceps, where squeezing and rotation are often used. Patel and colleagues used a split-mouth prospective methodology to compare the Physics Forceps with conventional forceps for orthodontic extractions. The study found a significant reduction in operative time and immediate postoperative marginal bone and soft tissue loss with the Physics Forceps. Hariharan and coworkers found advantages with the Physics Forceps over conventional forceps with regards to pain scores.

Oct 10, 2020 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Principles of Exodontia
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