Systemic antimicrobials and local adjuncts in periodontitis

Question 1

What is the main aetiological factor of periodontal disease?

Answer 1

Dental biofilm.

Question 2

What 2 pathogens are targeted by systemic antimicrobials and why?

Answer 2

1. P. gingivalis and A. actinomycetemcomitans
2. They both invade periodontal tissues.

Question 3

Why are antibiotics generally not effective against dental biofilm?

Answer 3

Due to extra-cellular polysaccharides that protect the bacteria in biofilm.

Question 4

Why are periodontal diseases treated differently to conventional infections?

Answer 4

They are:

1. Chronic in nature
2. Caused by bacteria normally present in the mouth - so eradicating all may cause adverse effects
3. Caused by dysbiotic biofilm - biofilm hard to remove w medication.
4. RSD alone can be effective.

This is why we must think twice before prescribing systemic antimicrobials - used w susceptible patients such as thsoe w grade C periodontitis

Question 5

Give 4 examples of adjunctive therapies used after RSD.

Answer 5

1. Antimicrobials
2. Probiotics
3. Lasers
4. Host modulators

Question 6

Give 4 characteristics of antibiotics that must be looked at before prescribing.

Answer 6

1. Pharmacodynamics - how it is absorbed.
2. Pharmacokynetics - what types of microorganisms it affects.
3. Interactions with other drugs.
4. Side effects.

Question 7

Give the 3 recommended regimes of systemic antimicrobials in periodontitis.

Answer 7

1. Amoxicillin + Metronidazole - known as the periodontal cocktail.

Amoxicillin 500mg/3x7d inhibits the bacterial glycans in gram positive bacteria.

Metronidazole 400mg/3x7d affects DNA synthesis and replication in anaerobic gram negative bacteria.

2. Metronidazole alone 400mg/3x7d
3. Azithromycin 500mg/1x3d

Macrolide antibiotics

Inhibits ribosomes, which stops the synthesis of proteins of bacterial cells.

Convenient for patient as dose is only for 3 days.

Can accumulate in immune cells after the 3 days, boosting protection.

Question 8

For locally applied periodontal adjuncts to be effective what 3 things must they do?

Answer 8

1. Need to be in the right location
2. With a high enough concentration
3. For a long enough period of time.

Question 9

Give 3 advantages of periodontal locally applied adjuncts.

Answer 9

1. Assured compliance

As they have been applied by dental professionals.

2. Minimal systemic exposure

By applying locally there are less side effects.

3. Drug levels far exceed the minimal inhibitory concentration.

They are applied directly in pockets so the concentration is high.

Question 10

Give 1 potential disadvantage of periodontal locally applied adjuncts.

Answer 10

Substantivity - refers to the time these agents are present in the local area.

Question 11

Give 2 indications for periodontal locally applied adjuncts.

Answer 11

1. Isolated pockets which do not react to conventional periodontal treatment.
2. In patients with good oral hygiene.

Question 12

Give 3 examples of local agents.

Answer 12

1. TetracyclineVery effective when applied locally.They inhibit synthesis of bacterial proteins by attaching to the surface of the bacterial ribosomes.Actisite (impregnated w tetracyline) which is applied using a fiber in the pocket. The fiber resists the rinsing effect caused by GCF. Fiber needs to be manually removed after use.
   2. Metronidazole
   Elyzol 25% Met gel - gels can get rinsed away by GCF quite easily so need to apply more.
   3. Chlorhexidine
   Periochip 2.5mg of chlorhexidine gluconate - uses fibres that resorb naturally.