The Antimicrobial Approach

The oral cavity is an ideal location for the formation of dental biofilms (plaque). These highly organized bacterial microcosms love the warm, moist environment and the many niches available for colonization. The sulcus, tongue, tonsils, and crevices around restorative margins are highly conducive for repopulation, proliferation, and survival of many of the pathogenic species that contribute to periodontal disease.

Biofilms are difficult to remove and are not easily penetrated due to their protective layer and their uncanny ability to adapt to or create their own environment.¹ However, the most common treatment strategies for periodontal disease—scaling, root planing, and surgery—can never completely eliminate subgingival biofilm and calculus. This leaves antimicrobials, irrigation agents, and local delivery antibiotics with important adjunctive roles to play in the battle against biofilm.

Biofilms and Mechanical Therapy

Periodontal debridement (scaling and root planing (SRP)) is very effective in removing biofilm and, consequently, in controlling most inflammatory periodontal diseases. It remains the cornerstone of nonsurgical and surgical therapy and can be performed in either an open (surgical) or closed environment (nonsurgical).² In both cases, the successful removal of root-associated deposits is limited by clinicians’ tactile, visual, and auditory senses and their innate and learned clinical skills.³ In open surgical debridement, access to the infected roots is more readily available. However, studies show that despite the increased ability to visualize the root surfaces during surgery, a significant amount of calculus is left behind during both open and closed debridement.²

Surgical debridement is superior to nonsurgical (debridement) in deep pockets and furcations.² However, a new endoscopic device that enables clinicians to better visualize the roots at a magnification of 48x is enhancing the potential outcomes of closed debridement through better identification and removal of subgingival calculus.⁴ New technology holds great promise for minimally invasive periodontal treatments much like other endoscopic procedures that are so widespread in medicine.

Surprisingly, a significant number of controlled long-term clinical trials ranging from 1 to 8 years show that when clinical attachment levels (CAL) and probing depth (PD) reductions are compared between surgery and nonsurgery, the mean differences are very similar over time.⁵ In the absence of adjunctive antimicrobials, many studies comparing surgical to nonsurgical therapy show that surgery reduces PD slightly better than SRP, and scaling and root planing favor slightly better improvements in CAL. Attachment levels appear to maintain at similar levels over several years for both surgical and nonsurgical therapy.⁵

Clinical Significance

Often, mean differences between therapies are statistically significant. However, changes between PD reductions and CAL gains are, on average, only tenths of a millimeter different between SRP alone and SRP plus an adjunctive antimicrobial. This raises the question, is an additional 0.3 mm mean change in PD or CAL clinically significant? Some have set the standard of at least a 2 mm difference before a therapy is considered clinically significant.⁶ So who cares about 0.3 mm? In my experience, the patient does! Sometimes preserving that small amount of attachment may prevent post-therapy “black holes” in anterior interproximal spaces and long-term dentinal hypersensitivity.

Thus, in the very beginning of the periodontal treatment plan, both practitioners and patients must agree on their respective expectations for the outcome of the periodontal therapy. Dental hygienists can often accomplish definitive nonsurgical therapy in early to moderate periodontitis cases with thorough periodontal debridement and the appropriate use of adjunctive antimicrobials.

If reevaluation results indicate a reduction of probing depths to <5 mm, decreased mobility and bleeding on probing, and the patient is comfortable and satisfied with the esthetic result, then an appropriate periodontal maintenance program (3 months for most patients) is established.

Inflammatory Periodontal Disease

So what does all this have to do with adjunctive antimicrobial therapy? If scaling and root planing with or without surgery is so effective, why do we even need adjunctive antimicrobials? The answer is because we are never 100% successful in removing all of the subgingival biofilm and calculus2 and many patients find it difficult to maintain a plaque-free environment.

Some bacteria are very resistant to treatment like Porphyromonas gingivalis (Pg), Bacteroides forsythus (BF), and Treponema denticola (TD).⁷ These three are highly pathogenic and become more dominant in the later stages of biofilm development.⁷ In addition, Actinobacillus actinomycetemcomitans (Aa) is strongly associated with aggressive forms of periodontitis (formerly known as juvenile or early onset periodontitis). It is very difficult to eradicate due to the enzymes, leukotoxins, and other products that enable it to penetrate epithelium, connective tissue, and bone. Sometimes scaling and root planing are unsuccessful in arresting the disease without the addition of surgical debridement plus antibiotic therapy.

In chronic periodontitis (formerly adult periodontitis), systemic antibiotics are not usually needed except in severely advanced or recurrent periodontal disease.⁸ Mechanical debridement, either with or without surgical access, is successful in treating most chronic periodontitis. If, however, clinical signs of disease, such as increasing pocket depths, loss of attachment, and bleeding on probing persist or recur following therapy, other pharmacotherapeutic agents might be considered.

Topical Antimicrobials

In gingivitis subjects, when initial removal of plaque and calculus deposits and good oral hygiene do not reverse the inflammation, prescription or over-the-counter antigingivitis mouth rinses and toothpastes or irrigation with antimicrobials can be added to the patient’s home care regimen.

Among these agents, the most effective mouth rinse for reducing plaque and gingivitis is chlorhexidine, a drug that is available only by prescription in the United States. A gold standard among all mouthrinses, it contains 0.12% chlorhexidine and is a cationic surface-active agent with substantivity—meaning it absorbs into soft and hard tissues and is released over time in active form. Many professionals underutilize chlorhexidine despite overwhelming evidence to support its efficacy and safety because of the significant staining that occurs with prolonged use. Other disadvantages include altered taste sensation and potential mucositis.⁹ Unfortunately, recent research of biofilm in laboratories around the world shows that many of these agents, including chlorhexidine and antibiotics, do not penetrate the entire depth of the biofilm and that, sometimes, much longer exposure times and higher concentrations of the agents are needed to be completely effective.¹

Phenolic agents hold the American Dental Association Seal of Approval for reduction of plaque and gingivitis. One study indicates that phenolic mouth rinses help some patients compensate for failure to comply with daily flossing by decreasing interproximal gingival inflammation associated with poor plaque removal.¹⁰

Since supragingival plaque reappears within hours or days after its removal, patients need to practice good oral hygiene. Products with fluoride are recommended for caries reduction. New formulations containing triclosan are capable of reducing plaque and caries, in addition to reducing gingivitis. Triclosan toothpaste appears to have a positive effect on the long-term maintenance in gingivitis patients.¹¹

Daily irrigation with a powered irrigation device, with or without an antimicrobial agent, is also useful for decreasing the inflammation associated with gingivitis and periodontitis.¹² Clinically significant changes in probing depths and attachment levels are not usually expected with irrigation alone, however, significant reduction in bleeding on probing and gingival inflammation using patient applied irrigation is predictable. Recent reports indicate that when daily irrigation with water (no antimicrobial) is added to a regular oral hygiene home regimen, a significant reduction in probing depth, bleeding on probing, and Gingival Index occurs.¹² This indicates that irrigation’s positive effects may be attributed to physically ” flushing” out the sulcus and dilution of the pro-inflammatory molecules from the gingival crevicular fluid. This simple, cost-effective therapy using water irrigation with a subgingival “PikPocket^®; tip” is often overlooked and underutilized. The addition of fluorides, phenols, chlorhexidine, or sodium hypochlorite to the irrigating solution provides small adjunctive effects in reducing clinical parameters compared to irrigation with water alone.¹²

If, however, patient-applied topical antimicrobial therapy is insufficient in preventing, arresting, or reversing periodontal disease progression, then other professionally applied antimicrobial agents, such as 0.05% to 10% povidone iodine, or sustained local drug delivery products should be considered.

Locally Delivered Antimicrobials

Currently, there are three generations of locally delivered sustained release products: tetracycline fibers, doxycycline gel and chlorhexidine chips, and, finally, minocycline miscrospheres (Table 1). However at the present time, tetracycline fibers are not available in the United States.

When used in conjunction with mechanical debridement, these products significantly reduce signs of inflammation and probing depths or improve clinical attachment levels.¹² They reach adequate levels in the gingival crevicular fluid to suppress or kill bacteria without causing the development of bacterial resistance. Of these products, only the chlorhexidine chip is an antiseptic; the others are antibiotics. Indications include isolated pockets of >5 mm that bleed on probing. These products are particularly useful in patients with moderate pockets that may not require surgery, and can be used at the time of debridement or at the reevaluation time. Only the doxycycline gel has been tested as a stand-alone product, but recent work indicates that placement at the time of full mouth debridement produces the best results.¹³ If multiple sites need treatment, particularly in aggressive forms of periodontitis, then systemic antibiotics should be considered.

Systemic Antibiotics for Periodontal Treatment

Most periodontal infections are dominated with anaerobic bacteria and will respond favorably to penicillin, amoxicillin, tetracycline, doxycycline metronidazole, and clindamycin or a combination of these antibiotics. While antibiotics are not routinely used for chronic periodontitis, they may enhance healing by reducing the bacterial load or eliminating specific pathogens for up to 6 months to 1 year. Like all other antimicrobial therapy, the effect is short lived and may need to be repeated when symptoms of active disease, such as bleeding on probing and attachment loss occur.

More aggressive types of periodontitis require a combination of surgery and systemic antibiotics.

Conclusion

Nonsurgical therapy remains the cornerstone of periodontal treatment. In general, locally delivered antimicrobials are intended for treating isolated sites with moderate disease and are most effective when combined with mechanical debridement.

Some argue that scaling and root planing alone are very effective, and that when compared to SRP plus a locally delivered antimicrobial, the 0.3 mm mean differences that are reported as statistically significant improvements in PD and CAL are too small and not clinically significant.⁶ However, these are means and some sites will exhibit far more improvement in PD and CAL, where others may stay the same or, in a small percentage of sites, actually get worse. So prudent dental hygienists will factor in all of these considerations and use their clinical judgment in their final treatment decisions.

Systemic antiobiotics or host modulating drugs (Periostat™) used in conjunction with periodontal debridement may be indicated for multiple failing sites.

In the anterior sextants, many periodontists have moved away from pocket elimination surgery to scaling and root planing with locally delivered antimicrobials. In posterior sextants where esthetics is less of a concern, surgical procedures are still more commonly performed.

As with all of dentistry, there is no “cookbook” approach that works for every site in every patient. Therefore, combined surgical and nonsurgical therapies are often used today along with adjunctive antimicrobials when indicated. Treatment decisions should be made according to the patient’s needs and desires.

References

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