parallel the course of the major palatine artery, well away from it. Transverse releasing incisions are neither necessary nor recommended in implant surgery, and might very well cross the vessel's pathway.

If the major palatine artery is accidentally severed anteriorly, from the premolar to incisor region, local pressure (14) should be quickly applied in the region of the last molar where the vessel emerges through the greater palatine foramen. Clamping (15) and ligation (16) should immediately follow. If the injury is so close to the foramen that local procedures are impossible, the hemorrhaging must be stopped in the neck by ligation of an external carotid artery, a drastic but vital recourse.

Keeping basic considerations in mind — including the fact that the more the ridge has resorbed, the closer the vessel to the operative field — should avoid accidental injury to the major palatine artery.

Anteriorly the copious blood supply provided by the numerous terminal branches of the major palatine artery and the superior alveolar artery may produce considerable bleeding. The numerous, small vessels do not require clamping or ligation, but it is often advisable to reinsert the patient's old denture, hollowed and lined by a soft base conditioner, to prevent hematoma formation and to inhibit excess swelling.

The branches of the maxillary artery that supply the maxillary sinus, the nasal cavity, and the hamular notch area are well away from the dental arch and, therefore, from implant surgical procedures. Neither incisions, impression-taking procedures, nor the insertion of implants should interefere with them.

Veins

The veins of the head are numerous and the network they form is complicated and highly variable. Their complexity is more due to their nondental functions than to their dental, and their great variability in the face and neck is due to the large number of possible outlets for the draining of venous blood. Multiple anastomoses between intracranial and extracranial veins permit the flow of blood in both directions, an advantage in maintaining intracranial pressure but a disadvantage in permitting a two-way flow

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