MANDIBULAR TOOTH EXTRACTION
When removing lower molar teeth, the index finger of the left hand is in the buccal vestibule and the second finger is in the lingual vestibule, reflecting the lip, cheek, and tongue. The thumb of the left hand is placed below the chin so that the jaw is held between the fingers and thumb, which support the mandible and minimize TMJ pressures. This technique provides less tac-tile information, but during extraction of mandibular teeth the need to support the mandible supersedes the need to support the alveolar process. A useful alternative is to place a bite block between the teeth on the con-tralateral side. The bite block allows the patient to help provide stabilizing forces to limit the pres-sure on the TMJs. The surgeon's hand should continue to provide additional support to the jaw.
Mandibular anterior teeth.
The mandibular incisors and canines are similar in shape, with the incisors being shorter and slightly thinner and the canine roots being longer and somewhat heavier. The incisor roots are more likely to be fractured, because they are somewhat thin and therefore should be removed only after adequate pre-extraction luxation. The alveolar bone that overlies the incisors and canines is quite thin on the labial and lin-gual sides. The bone over the canine may be somewhat thicker, especially on the lingual side.
The lower universal (no. 151) forceps are usually used to remove these teeth. Alternative choices include the no. 151A or the English style of Ashe forceps. The forceps beaks are positioned on the teeth and seated apically with strong force. The extraction movements are generally in the labial and lingual directions, with equal pressures both ways. Once the tooth has become luxated and mobile, rotational movement may be used to expand the alveolar bone further. The tooth is removed from the socket with fractional forces in a labial-incisal direction.
The mandibular premolars are among the easiest teeth to remove. The roots tend to be straight and conic, albeit sometimes slender. The over-lying alveolar bone is thin on the buccal aspect and somewhat heavier on the lingual side The lower universal (no. 151) forceps is usually chosen for the extraction of the mandibular premolars. The no. 151A forceps and the English style of forceps are both popular alternatives for extraction of these teeth.
The forceps is apically forced as far as possible, with the basic movements being toward the buccal aspect, returning to the lingual aspect, and, finally, rotating. Rotational movement is used more when extracting these teeth than any others, except perhaps the maxillary cen-tral incisor. The tooth is then delivered in the occluso-buccal direction. Careful preoperative radio-graphic assessment must be performed to assure the operator that no root curvature exists in the apical third of the tooth. If such a curvature does exist, the rotation-al movements should be reduced or eliminated from the extraction procedure.
Mandibular molars. The mandibular molars are usu-ally two rooted, with roots of the first molar more widely divergent than those of the second molar. Additionally the roots may converge at the apical one third, which increases the difficulty of extraction. The roots are gener-ally heavy and strong. The overlying alveolar bone is heavier than the bone on any other teeth in the mouth. The combination of relatively long, strong, divergent roots with heavy overlying buccolingual bone makes the mandibular first molar the most difficult of all teeth to extract.
The no. 17 forceps is usually used for extraction of the mandibular molars; it has small tip projections on both beaks to fit into the bifurcation of the tooth roots. The forceps is adapted to the root of the tooth in the usual fashion, and strong apical pressure is applied to set the beaks of the forceps apically as far as possible. Strong buccolingual motion is then used to expand the tooth socket and allow the tooth to be delivered in the bucco-occlusal direction. The linguoalveolar bone around the second molar is thinner than the buccal plate, so the sec-
ond molar can be more easily removed with stronger lin-gual than buccal pressures.
If the tooth roots are clearly bifurcated, the no. 23, or cowhorn, forceps can be used. This instrument is; designed to be closed forcefully with the handles, thereby squeezing the beaks of the forceps into the bifurcation. This creates force against the crest of the alveolar ridge on the buccolingual aspects and literally forces the tooth superiorly directly out of the tooth socket. If initially this is not successful, the forceps is given bucco-lingual movements to expand the alveolar bone, and more squeezing of the handles is performed. Care must be taken with these forceps to prevent damaging the maxillary teeth, because the lower molar may actually pop out of the socket and thus release the forceps to strike the upper teeth .
Erupted mandibular third molars usually have fused conical roots. Because a bifurcation is not likely, the no. 222 forceps—a short-beaked, right-angled forceps—is used to extract this tooth. The lingual plate of bone is def-initely thinner than the buccocortical plate, so most of the extraction forces should be delivered to the lingual aspect. The third molar is delivered in the linguloocclusal direction. The erupted mandibular third molar that is in function can be a deceptively difficult tooth to extract.
The dentist should give serious consideration to using the straight elevator to achieve a moderate degree of luxation before applying the forceps. Pressure should be gradually increased, and attempts to mobilize the tooth should be made before final strong pressures are delivered