PRINCIPLES OF FORCEPS USE
The primary instrument used to remove a tooth from the alveolar process is the extraction forceps. Although elevators may help in the luxation of a tooth, the instrument that does most of the work is the forceps. The goal of forceps use is twofold: (1) Expansion of the bony socket by use of the wedge-shaped beaks of the forceps and the movements of. the tooth itself with the forceps, and (2) removal of the tooth from the socket.
The forceps can apply five major motions to luxate the teeth and expand the bony socket: The first is apical pressure, which accomplishes two goals. Although the tooth moves in an apical direction minimally, the tooth socket is expanded by the insertion of the beaks down into the periodontal ligament space (Fig. 7-44). Thus apical pressure of the forceps on the tooth causes bony expansion. A second accomplishment of apical pressure is that the center of the tooth’s rotation is displaced apically. Because the tooth is moving in response to the force placed on it by _ the forceps, the forceps becomes the instrument of expansion. If the fulcrum is high (Fig. 7-45), a larger amount of force is placed on the apical region of the tooth, which . increases the chance of fracturing the root end. If the beaks of the forceps are forced into the periodontal ligament space, the center of rotation is moved apically, which results in greater movement of the expansion forces at the crest of the ridge and less force moving the apex of the. tooth lingually (Fig. 7-46) This process decreases the chance for apical root fracture.
The second major Pressure or movement applied by forceps is the buccal force. Buccal pressures result in expansion of the buccal plate, particularly at the crest of the ridge (Fig. 7-47). Although buccal pressure causes expansion forces at the crest of the ridge, it is important to remember that it also causes lingual apical pressure.
Third, lingual pressure is similar to the concept of buccal pressure but is aimed at expanding the linguocrestal bone and, at the same time, avoiding excessive pressures on the buccal apical bone (Fig. 7-48).
Fourth, rotational pressure, as the name implies, rotates the tooth, which causes some internal expansion of the tooth socket. Teeth with single, conic roots, such as the maxillary incisors, and mandibular premolars, with roots that are not curved, are most amenable to luxation by this technique (Fig. 7-49). Teeth that have other than conic roots or that have multiple roots especially if those roots are curved-are. more likely to fracture under this type of pressure.
Finally, tractional forces are useful for delivering the tooth from the socket once adequate bony expansion is achieved. Tractional forces should be limited to the final portion of the extraction process and should be. gentle (Fig. 7-.50).
In summary, a variety of forces can be used to remove teeth. A strong apical force is always useful and should be .
applied whenever forceps is adapted ‘to the tooth. Most teeth are removed by a combination’ of buccal and lingual forces. Because maxillary buccal bone is usually thinner and the palatal bone is a thicker cortical bone, maxillary teeth are usually removed by strong buccal forces and less vigorous palatal forces. In the mandible the buccal bone is thinner from the midline posteriorly to the area of the molars. Therefore.the incisors, canines, and premolars are removed primarily as a result of strong buccal force and
less vigorous lingual pressures. The mandibular molar teeth have stronger buccal bone and usually require a stronger lingual pressure than the other teeth in the mouth. As mentioned earlier, rotational forces are useful for single-rooted,teeth that have conic’ roots and no severe curvatures at the root end. The maxillary Incisors,particularly the central incisor and mandibular premolars (especially the second premolar), are most amenable to rotational forces.