Dental extraction and Bishoping in animals
Dental extraction and Bishoping in animals are important surgical procedures to treat surgical affections of teeth.
Tooth surgical procedures in animals are-
Exodontia or Dental extraction
Exodontia or Dental extraction is the procedure to remove a tooth from the gum.
Indication for dental extraction
The indications for Exodontia or tooth extraction in animals are-
- Retained deciduous teeth
- Infected teeth
- Traumatised teeth
- Mal occluded and supernumerary teeth
Normally the eruption of permanent tooth causes the shedding of the temporary one, whose roots are small and rudimentary.
The cause for failure of shedding of temporary teeth is considered to be due to the failure of the periodontal membrane to detach from the tooth and alveolus.
Canine distemper may facilitate retention of temporary teeth.
Retention of the cheek tooth is very rare as the growing permanent tooth virtually push the temporary tooth out. But the permanent incisors and canines being not directly beneath the deciduous teeth, if they are not shed in time, there will be extra number of such teeth.
In the case of puppies, if the temporary incisors or canines are not shed even by 6-7 months of age, they should be extracted.
Infection of a dental root with damage to the periodontal membrane is the most common indication for extraction.
The infection may be either primary bacterial invasion or a sequel to gingivitis.
In brachycephalic breeds and in certain individuals, short jaws lead to crowding of the teeth and malocclusion. In such cases, it is advisable to extract those mal occluding teeth.
Technique of dental extraction
The instruments required for dental extraction are root elevators, canine extractors, molar extractors. Small sized hack saw blades, bone chisels, rongeur forceps and periosteal elevators.
In small animals, general anaesthesia is required to get effective control of the patient. Regardless of type of tooth, the principle of tooth extraction is to displace the root from the socket using a root elevator.
The first step is to loosen the gums by inserting the elevator completely around the neck between the tooth and gum. The elevator is then inserted around the root, separating it from the remaining attachments.
Loosening the root in the alveolus can be hastened by using the dental extractor to twist the tool gently back and forth. Once the tooth is loosened, the back of the extractor can be used as a fulcrum against the remaining teeth to withdraw the loosened one.
The upper molar and 4th premolar teeth present special problems because they have 3 roots. The single posterior root should be separated from the anterior pair before extraction. After loosening the gum from the neck, the tooth is split with a tooth splitter or a small hack saw blade. Once split, the roots can be extracted separately as described earlier.
The upper carnassial tooth may sometimes pose difficulty while extraction. In such cases the alveolar resection method is adopted. In this case, the gum over the affected tooth is incised vertically between the anterior and posterior roots. The gum is reflected from the tooth and then the lateral aspect of the alveolus is removed with a mallet and chisel. The root elevator is driven between the roots and by it’s up and down movement, roots are loosened.
Loosened molars are removed using molar extractors. The cut edges of the gum may be apposed with interrupted absorbable sutures. In the case of canine teeth, their long root and firm attachment present difficulty while extraction. In cases of failure of conventional methods of tooth extraction, the alveolus may be opened using a bone chisel from the neck to the apex of the root, after retracting the gum. The lateral wall of the alveolus is removed and the root is loosened and the tooth is removed. The gingival incision is sutured with interrupted sutures.
Post operative care
Control of haemorrhage is most important. This is done by packing the alveolus with cotton or absorbable gelatin foam.
The alveolus should be checked for bone spicules or rough edges and in case of their presence, they should be removed with a burr or a rongeur forceps. Most alveoli fill with granulation tissue and ossify. But if the cavity is very large or when many teeth are removed, the alveoli should be packed with dental wax. This will seal the cavity and as the granulation tissue fill the cavity, this plug will be pushed out.
Post operative complication
Osteomyelitis, endocarditis and suppurative arthritis are the common sequelae to dental extraction. Hence these can be prevented by providing sufficient antibiotic cover, which should be started a day or two ahead of surgery.
Removal of molars in bovines
Extraction of molars is indicated in ossifying alveolar periostitis, odontoma and in extensive.
General anaesthesia or local infiltration anaesthesia or maxillary nerve block or mental nerve block may be given and the animal is controlled on lateral recumbency.
Anatomy
The roots of the first three cheek teeth are directed slightly forward and are not in maxillary sinus. But the roots of the 4th and 5th cheek teeth are in the floor of the maxillary sinus and are directed backwards.
The infra-orbital and alveolar branches of the internal maxillary artery supply nutrition. The branches of the maxillary nerve exit through the infraorbital foramen and supply the upper cheek tooth. Mandibular nerve supplies the lower cheek teeth.
Technique of molar extraction
Simple extraction by using dental forceps is possible in cases when tooth is diseased.
Repulsion through the maxillary sinus after trephining the maxillary sinus and removal of the external alveolar plate in cases where the roots are embedded in the sinus. Here the maxillary sinus is trephined in level with the root of the affected tooth. The mouth is kept open using a mouth gag. The roots of the tooth are identified by breaking the alveolar plates using a chisel and mallet through the trephine opening. A punch is applied against the root in the direction of the tooth and it is struck with a mallet till the tooth could be safely extracted by the hand in the mouth. Occasionally it may become necessary to break the root from the crown and remove them separately.
In the case of lower cheek tooth, trephine openings are made on the inferior borders of the ramus of the mandible and the tooth is repelled out.
Bishoping
Bishoping is a technique used to make an aged horse to appear as young by creating infundibular marks artificially.
The normal infundibulum marks disappear from centrals by six years. From lateral and corners by seven and eight years respectively.
By staining with silver nitrate, the artificial infundibulum marks are made to resemble normal infundibulum marks.
Artificial marks less deep on centrals, moderate in laterals, deeper in corners.
Bishoping can be easily detected by noting the shape of the table surface of the tooth.
In the young horse (less then 8 years), the table is roughly oval sideways, whereas in aged animals (more then 8 years) the table is triangular.
In very old animals the tables become circular in shape and also the artificial markings are not lined by enamel unlike the normal infundibulum.