What are dental extraction forceps ?
Extraction forceps are the most familiar instruments with regard to extraction of tooth/ teeth. Intra- alveolar extractions are mainly accomplished using elevators and extraction forceps. They are the instruments that are used to remove the tooth out of the alveolar bone socket. Ideally, forceps are used to lift the tooth, which is luxated by the elevator. Also, they are useful in expansion of bone. The design and configurations of the extraction forceps are such that they can be adapted for removal of specific tooth.
Classification of dental extraction forceps
Based on the arch to be used:
Based on the hinge direction:
– American type (Hinge in horizontal direction)
– English type (Hinge in vertical direction)
Based on the design of handle:
– Straight handle
– Curved handle
Based on the teeth to be extracted:
(Adapted from Kruger)
– Standard forceps No 1 for maxillary central and lateral incisors, canines, and premolars in some instances.
– Standard No 65 for maxillary root tips.
– Standard No 210S for maxillary molars.
– Ash, Mead No 1, for mandibular teeth.
– Standard No 16, cowhorn, for mandibular molars
– Standard No 150 for maxillary premolars
– Standard No 151 for mandibular premolars
Working principle/ Mechanics
Forceps use is based on the wedge principle. The tips of the forceps are forced into the periodontal ligament space at the bony crest to expand the bone and force the tooth out of socket. Forceps can apply five major motions to luxate the teeth and expand the socket. They are:
1. Apical pressure: It causes bony expansion and results in center of rotation of tooth is displaced apically. This causes greater expansion of buccal cortex, less movement of the apex of tooth and therefore lesser chances of fracture of the root.
2. Buccal force: It results in expansion of buccal plate, particularly at the crest of the ridge. However, excess force can lead to fracture of the apical portion of the root.
3. Lingual or palatal pressure: This causes expansion of linguocrestal bone and reduces excess force on buccal aspect.
4. Rotational pressure: Causes internal expansion of the tooth socket and tearing of periodontal ligaments. It is most suitable for single or conical rooted teeth.
5. Tractional forces: Useful for delivering the tooth from socket once adequate expansion is achieved. It has to be gentle and teeth should not be pulled from their sockets.
Design of dental extraction forceps
*ISO 9173 specifies the general performance requirements for extraction forceps used in dentistry.
They have three basic components. They are beak, hinge and handle.
Beak: It is the functional working end of forceps which contacts the teeth. Beak design is the greatest source of variations. Beaks are designed such that they adapt to the junction of crown and root. In order to avoid complications, it has to be remembered that beaks of the forceps are structured to adapt to the root structure of the tooth. Adaptation of beak on the crown structure alone poses high risk of fracture of root during extraction. Thus, single-rooted teeth, two- rooted teeth and three- rooted teeth have different forceps with beaks that are suitable for the structure.
Width of the beak is an important consideration in the design. It is necessary to have forceps with narrow beak for the removal of narrow teeth like incisors and those with wider beaks are meant for teeth that are substantially wider, for example the molars. Beaks are designed to be parallel to the long axis of the tooth. In this regard, beaks of maxillary anterior forceps are usually parallel to the handles, while the beaks are offset in a bayonet fashion for accessibility to the posterior teeth. The beaks of mandibular forceps are set perpendicular to the handles which allows the beaks to be placed parallel to the long axis of tooth in a comfortable and controlled manner.
Hinge/Joint: Hinge is the connection point for first and second handles which are pivotally connected. It is the analogue of shank in elevators, which is merely a mechanism of connecting the handle to the beak. The applied force is transferred and concentrated by the hinge.
Based on the hinge design two distinct type of forceps exist. The American style has a hinge in horizontal direction. American pattern dental extracting forceps are typically identified by the shape of connecting point where two forceps beaks connect. They have a hidden or seamless bolt which keeps the two arms connected. English style have the hinge in vertical direction and corresponding vertically positioned handle.
Handle: It is the part which is held in the hand. Size of the handle is an important factor to use comfortably and to deliver sufficient pressure and leverage to remove the required tooth. To avoid slippage and for the firm grip, handles are designed with serrated surface. Handles of the forceps are usually straight. However, curved handles are designed for the sense of better fit.
Article by Dr. Siri P.B.