The spread of odontogenic infection (with sincere thanks to the late Dr. John Gregg).

1. Thickness of the cortical bone
2. Relationship of tooth to mylohyoid
3. Relationship of tooth to buccinator

In the posterior mandible, the cortical plate is much thicker labially than lingually such that it is quite common to have an infection break through the lingual aspect of the mandible. The apecies of the premolars and the incisors all lie above the mylohyoid line therefore infection may commonly spread to the floor of the mouth, raising the tongue as it crosses the midline in the fascial cleft between the mylohyoid and the geniohyoids. The roots of the second molar (and sometimes the first) like below the mylohyoid such that infection tends to spread to the submental and diagastric triangles. Finally the roots of the third molar are generally at the posterior border of hte mylohyoid and infection can spread in either or both directions.

In the maxilla the buccinator attaches to the alveolar process lateral to the molars. the roots of the second and third molars are superior to the buccinator thus odontogenic infection can easily spread in the left between masseter and buccinator and from there to the infratemporal fossa and temporal fossa between the fascia and the temporalis muscle. Occasionally (thought this is relatively rare) the infection may break into the maxillary sinus. Commonly pain from an odontogenic infection of the maxillary molar may be referred to the maxillary sinus. Please pay attention to the difference between the last two statements. The location of the first molar roots is variable with respect to the buccinator. The canine and premolar roots are anterior to the buccinator and odontogenic infection here tends to spread to the canine fossa and then to the lower eyelid while infections from the apecies of the incisors, which are also anterior to the buccinator, will spread to the upper lip. Their further dissemination is somewhat limited by the levator labii superioris and the levatior labii superioris alaquae nasi.

It is important to remember, however, that none of these "barriers" are absolute and unchecked purulence and bacterial activity can destroy fascial barriers. Furthermore, the natural "clefts" that occur in the fascial planes of the head and neck provide a "highway" to the mediastinum while the valveless vein system of the head permits retrograde flow of bacteria to the cavernous sinus. Purulence in either of these areas can be rapidly life threatening.

Principles of Therapy

1. Determine the severity of the infection
2. Evaluate the state of the patient's host defense mechanisms
3. Determine whether the patient should be treated by a general dentist or a specialist
4. Treat the infection surgically - remove the source, debride and decrease bacterial load
5. Support the patient medically
6. Choose and prescribe the appropriate antibiotic; administer the antibiotic properly

Dr. Goldman's Diatribe on Drains

I do not place modified penrose (flat yellow rubber) drains in the office for infections. If a patient would benefit from such a procedure I choose to manage these patients by incising, irrigating and then give the patient an irrigating syringe and teach the patient how to irrigate through the same opening I used. My rationale for this is that it avoids the placement of a foreign body intraorally which can be irritating AND for those patients who are somewhat unreliable, I do not have to worry about what happened to the drain when they did not return to have it removed. You will find other surgeons who swear by the use of drains. You can make your own choice once you are in practice and there are many right choices. You must always, however, understand why you made the choice you made.