CHAPTER 16: PRINCIPLES OF MANAGEMENT & PREVENTION OF ODONTOGENIC INFECTIONS

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Odontogenic Infections

Are infections that arise from teeth and is generally caused by bacteria.

Two major origins:

a. Periapical – from pulp necrosis (most common origin)

b. Periodontal – from perio pocket

Microbiology of odontogenic infections

polymicrobial • caused by normal oral bacterial flora (aerobic and anaerobic) • 50% to 60% involves mixed bacteria

Aerobic bacteria

gram-positive cocci: viridans-type Streptococci (45% occurrence)

Anaerobic bacteria

gram-positive cocci: Streptococcus & Peptostreptococcus

gram-negative rods: Prevotella, Fusobacterium, Porphyromonas

Pathophysiology of Odontogenic Infections

begins in periapical/ periodontal area → spreads in all directions favoring the path of least resistance → gradually erodes cancellous bone toward facial or lingual cortices → once through cortical bone, it spreads to fascial spaces (fascial spaces are not actual spaces but become created when invaded by infection)

Fascia

Thin casing of connective tissue beneath the skin that surrounds and holds every organ, blood vessel, bone, nerve fiber, and muscle in place

The deep spaces of the head and neck are fascia-lined spaces containing loose areolar connective tissue. These are “potential” spaces, only existing when invaded by bacteria.

Primary Spaces

Vestibular • Canine/Infraorbital • Buccal • Infratemporal • Submandibular • Submental • Sublingual

secondary Spaces

• Submasseteric/masseteric • Pterygomandibular • Superficial/Deep Temporal (masticator space) • Parapharyngeal • Retropharyngeal • Danger • Prevertebral (deep cervical fascial spaces of the neck) • Periorbital (masticator space) (deep cervical fascial spaces of the neck

The location of the involved potential space is determined by:

1. The thickness of the bone overlying the apex of tooth

2. The relationship of the site of perforation of bone to muscle attachments of maxilla and mandible

1. The thickness of the bone overlying the apex of tooth

Periapical infections arising from maxillary molars generally erode through the thin buccal cortex.

Periapical infections arising from mandibular molars generally erode through the lingual cortex.

2. The relationship of the site of perforation of bone to muscle attachments of maxilla and mandible

If bone erosion is below buccinator muscle attachment:

• Maxilla → Vestibular space

• Mandible → Buccal space

If bone erosion is above buccinator muscle attachment:

• Maxilla → Buccal space

• Mandible → Vestibular space

Lingual perforation

Lingual perforation superior to the mylohyoid attachment = sublingual space (shown in orange). Lingual perforation inferior to the mylohyoid attachment = submand

Four Stages of Odontogenic Infections

inoculation (edema)

cellulitis

abscess

resolution

inoculation (edema)

first 3 days – invasion of bacteria causing soft mildly tender swelling (mostly aerobes)

cellulitis

after 3 to 5 days - swelling becomes diffuse, indurated, acutely tender and painful to palpation (mixed flora)

abscess

at 5 to 7 days - liquefied abscess in the center of swelling; hallmark is formation of purulence (mostly anaerobes)

resolution

spontaneously or surgically drainage of abscessdestruction of bacteria by immune system-healing

Edema

0-3 days

diffuse borders

variable size

normal color

jelly-like consistency

increasing progression

absence of pus

low degree of seriousness

aerobic bacteria

Cellulitis

1-5 days

diffuse borders

larger size

red color

doughy or indurated consistency

increasing progression

absence of pus

greater degree of seriousness

mixed bacteria

Abscess

4-10 days

localized borders

smaller size

shiny center color

fluctuant consistency

decreasing progression

presence of pus

less degree of seriousness

anaerobic bacteria

Principles of Management of Odontogenic Infections

Principle 1: Determine Severity of Infection

Principle 2: Evaluate State of a Patient's Host Defense Mechanism

Principle 3: Determine Whether Patient Should Be Treated by General Dentist or Oral & Maxillofacial Surgeon

Principle 4: Treat Infection Surgically

Principle 5: Support Patient Medically

Principle 6: Choose & Prescribe Appropriate Antibiotics

Principle 7: Administer Antibiotic Properly

Principle 8: Evaluate the Patient Frequently

Principle 1: Determine Severity of Infection

Most odontogenic infections are mild and require only minor surgical therapy.

Severity can be determined by: complete history taking & physical examination

• Complete History Taking:

How long the infection has been present? → time of onset, progression of infection, rapidity of progression

Information on patient’s symptoms → cardinal signs of inflammation

Determine the general health of patient → malaise. fatigue, feverish, weak & sick patients

• Physical Examination:

1. Vital signs → Pulse Rate (Increases with a rise in body temperature • Severe infection = >100 beats/min), Blood Pressure (Generally not altered by infection. • Pain and anxiety can cause an increase in BP), Respiratory Rate (• Normal: 12–20 breaths/minute. • Mild to moderate infection: >20 breaths/min), Temperature (Normal: 36.5°C – 37.5°C (97.7°F – 99.5°F) • Fever: more than 38°C (WHO)) [Ergo, Mild infection: vital signs normal, slight inc in temp Severe infection: vital signs abnormal, high inc in temp]

2. General Appearance: Toxic Appearance → (Suggests severe infection • Elevated temperature, pulse, and respiratory rate)

3. Head & Neck Examination (Inspect cardinal signs of infection & inflammation)

4. Palpation of Swelling (Assesses tenderness, amount of heat and • Consistency of swelling: • Fleshy swelling → Doughy swelling • Firm or hard swelling → Indurated swelling • Fluctuant swelling → fluid-filled balloon • Indicates liquid pus in the center)

5. Others → Perform intra oral examination, radiographic examination, the staging of infection

Principle 2: Evaluate State of a Patient's Host Defense Mechanism

Estimate the patient's ability to defend against infection

This ability can be REDUCED BY:

• Medical conditions → such as uncontrolled diabetes mellitus, HIV, leukemia, malignancy, congenital and acquired immunological disease

• Drugs → such as cancer chemotherapy, and immunosuppressive drugs

Criteria for referral to an OMFS

1 Difficulty breathing 2 Difficulty swallowing 3 Dehydration 4 Trismus 5 Extra oral swelling 6 Temperature >101°F 7 Sever malaise / toxic appearance 8 Compromised host defense 9 Need for GA 10 Failed previous treatment

Criteria for Immediate Hospital Emergency Room Admission

1 Threat to Airway or vital structures 2 Rapidly progressing infection 3 Difficulty breathing (dyspnea) 4 Difficulty swallowing (dysphagia) 5 Temperature >101 °F (38.3 °C)

Trismus

results from involvement of the muscle of mastication by inflammatory process

Medial pterygoid muscle

is the most commonly affected muscles during an inferior alveolar nerve block

Mild Trismus

Maximum interincisal opening between 30-40 mm

Moderate Trismus

Maximum interincisal opening between 15-30 mm

Severe Trismus

Maximum interincisal opening is <15 mm

How to anesthesize patients with trismus?

research on this!

The principal managements of odontogenic infection are

Primary Goal: Remove the cause of infection

Secondary Goal: Surgical drainage of pus

Reasons for performing incision and drainage (I&D)

Remove the accumulated pus and bacteria from the tissues. 2. Decreases the load of bacteria and necrotic debris. 3. Reduce hydrostatic pressure by decompressing tissues. 4. Prevent the spread of infection into deeper anatomic spaces

[Ergo, decreases bacterial load and decreases pressure.]

Technique for I&D of a Vestibular Abscess or Cellulitis (Hilton’s Method)

1. Anesthesia • Preferred: Regional nerve block • Alternative: Infiltration

2. Stab Incision • At the site of maximum swelling • In MX: inferiorly for maximum gravity-dependent drainage • No more than 1 cm in length. • Avoid frenum and mental nerve

3. Insertion of Hemostat or Sinus Forceps • If pus is not encountered, deepen the surgical site carefully with sinus forceps to avoid damaging vital structures. • Steps • Closed forceps are pushed through the deep fascia towards the pus collection. • Once the abscess cavity is entered, the forceps are opened parallel to vital structures. • Pus drains along the sides of the forceps. • Entire cavity is explored for additional loculi.

4. Placement of Drain • A rubber drain is inserted into abscess cavity. • External part is secured to the wound margin. • Drain is left for at least 2–5 days. • Purpose of Drain: • Allows continuous drainage of contents. • Maintains the opening for drainage. • Enables irrigation and debridement. • Commonly used drain: • ¼ inch sterile Penrose drain (most common) • Alternative: sterile glove or rubber dam

5. Dressing • For extraoral incisions to protect the wound

Principle 5: Support Patient Medically

During infection, body's physiologic reserves are altered.

Children are particularly susceptible to dehydration and high fever during infection

Old patients are less susceptible to fever, but in them dehydration occurs during infection

Principle 6: Choose & Prescribe Appropriate Antibiotics

• First, determine the NEED for antibiotic administration.

The need can be determined from following 3 factors:

1 Seriousness of infection

2 Whether adequate surgical treatment can be achieved

3 State of patient's host defenses

[Antibiotics do not speed up the wound healing and do not provide any benefit for non-bacterial conditions]

Conditions that Antibiotics are Necessary

Swelling extending beyond the alveolar process • Acute onset infection with diffuse swelling & moderate to severe pain (cellulitis) • Immunocompromised patient • Deep fascial space infection • Severe pericoronitis • Temperature >101°F • trismus • swelling • Osteomyelitis • Lymphadenopathy

Conditions that Antibiotics are NOT necessary

Minor, chronic, well-localized dentoalveolar, periapical, periodontal abscess • alveolar osteitis (dry socket) • Mild pericoronitis • Patient Demand • Severe Pain • Toothache • Multiple extraction in patient who is NOT immunocompromised • Drained Alveolar abscess

Empirical therapy

refers to treatment initiated before a definitive diagnosis is made

use of antibiotics on the assumption that it is the appropriate drug

Recommended Oral Antibiotics

Penicillin - first line (drug of choice)

• Penicillin G - original penicillin; IV route

• Penicillin V - oral route

Amoxicillin - preferred due to better absorption

Penicillin allergy - clindamycin

Clindamycin allergy: cephalexin, clarithromycin, azithromycin

Patient Compliance & Dosage Considerations • Compliance decreases as dosage frequency increases • Once daily → 80% compliance • Twice daily → 69% compliance

indications for Culture & Sensitivity Testing

rapidly progressive infection

previous, multiple antibiotic therapy

nonresponsive infection (after >48hts)

recurrent infection

compromised host defense

[When to Perform Culture & Sensitivity Testing • Routine testing is NOT recommended but should be done in cases like nonresponsive infections]

Principle 7: Administer Antibiotic Properly

Prefer narrow spectrum antibiotics (targets a limited range of bacteria)

Avoid broad spectrum unless necessary

Kills not only oral bacteria but also beneficial flora in the gut, skin, and other areas

Use Bactericidal Antibiotic, if possible • Bactericidal = interferes with cell wall • Bacteriostatic = interferes bacterial reproduction

Use Cost Effective Antibiotics • Do not always need to be expensive

Use the Antibiotic with Lowest Incidence of Toxicity & Side Effects • Penicillin, clindamycin, macrolide, moxifloxacin, oral cephalosporins, tetracycline, metronidazole

Follow proper dose and at the proper dose interval

Plasma level of drug should be high enough to kill the bacteria but not so high to cause toxicity.

Peak plasma: 4-5x the minimal inhibitory concentration of bacteria.

Choose drug which could be given once a day for not more than 4 - 5 days to get more compliance.

narrow-spectrum antibiotics useful for treating simple odontogenic infections

penicillin

amoxicillin

clindamycin

metronidazole

broad-spectrum antibiotics useful for treating simple odontogenic infections

amoxicillin with clavulanic acid (for sinus infections)

azithromycin

moxifloxacin

Penicillin

drug of choice

Major Side Effect: Allergic reactions (hives, itching) • Prophylactic dose: 2g ; 60mins before operation

clindamycin

Advantages: low incidence of toxicity & side effects • Side effect: pseudomembranous colitis caused by Clostridium difficile

macrolides

No longer used due to drug reactions • BEST: Azithromycin due to low toxicity

Moxifloxacin (Fluoroquinolone Class)

Advantages: more effective than older fluoroquinolones • Toxicity: muscle weakness, mental clouding, drug interactions

Oral Cephalosporins (Cephalexin & Cefadroxil)

Mild toxicity • Not recommended for odontogenic infections • Cross-allergenicity with penicillin allergy

Tetracycline

Not used for odontogenic infections • Used topically in high concentrations (periodontal pockets) • Tooth discoloration (pregnant women; children under 12 year) • Mechanism: chelation of tetracycline to calcium

Metronidazole

For anaerobic bacteria ONLY • Mild toxicity = gastrointestinal disturbances • Disulfiram-like reaction or antabuse effect • Interacts with alcohol leading to: • Severe abdominal cramping • Violent vomiting

Other side effects: a. inhibits warfarin metabolism prolonging prothrombin time b. avoided in patients who are taking lithium

Principle 8: Evaluate the Patient Frequently

If Therapy is Successful:

Assess the I&D site to determine whether the drain can be removed. • Evaluate other key parameters: • Temperature (should be returning to normal) • Trismus (should be improving) • Swelling (should be reducing) • Patient’s subjective feelings (should report overall improvement)

If Therapy is unSuccessful:

Conduct a thorough examination to identify possible reasons for treatment failure, such as: • Inadequate drainage • Persistent infection • Antibiotic resistance • Undiagnosed systemic conditions

Principles of Prophylaxis Of Post-operative Wound Infection

Infection rate: 6–9% (clean-contaminated) and 40% (dirty wounds) • Antibiotics can reduce infection by up to 70% in OMFS

• Prophylactic drug = 2x the usual therapeutic dose Penicillin or Amoxicillin = 2g (1hr before) Clindamycin = 600 mg (1hr before)

• Antibiotics DO NOT replace proper surgical technique.

Surgical features that need prophylaxis

increase size of inoculum, complex surgeries, presence of foreign bodies, immunocompromised patients

Principles of Prophylaxis Against Metastatic Infection

refer to infections that occur in distant sites, not directly connected to the site of origin

• most commonly occur via hematogenous route

• sites most susceptible to metastatic spread:

1. heart valves = infective endocarditis 2. prosthetic joint replacements = prosthetic failure

Prophylaxis Against Infective Endocarditis

• is an infection of the endocardial surface of the heart (heart valves)

• caused by bacteremia

non-antibiotic prophylactic measures: 1. oral hygiene 2. chlorhexidine gluconate rinses

Prophylaxis Against Prosthetic Joint Infection

For patients with recently placed prosthetic joints who are immunocompromised or have poor glycemic control.

Prophylaxis in Patients With Other Cardiovascular Conditions

For patients with • arteriovenous shunt (AV) shunts for dialysis • ventriculoatrial shunts (VA) shunts for hydrocephalus

Antibiotic regimen recommended for the prevention of infective endocarditis for adults

Drug of choice → Amoxicillin 2g 1hr prior the procedure (four 500mg tablets)

Alternative (with Amoxicillin allergy) → Clindamycin 600mg 1hr prior the procedure (four 150mg tablets)

Antibiotic regimen recommended for the prevention of infective endocarditis for children

Drug of choice → Amoxicillin 50mg/kg 1hr prior the procedure

Alternative (with Amoxicillin allergy) → Clindamycin 20mg/kg 1hr prior the procedure