Horz.fm

For reprint orders, please contact: Diagnosis and anti-infective
therapy of periodontitis

Hans-Peter Horz† and Georg Conrads Periodontal diseases (gingivitis and periodontitis) are chronic bacterial infections with a
remarkably high prevalence and morbidity. Periodontitis, in contrast to gingivitis, is not
reversible, is associated with certain bacterial species and affects all of the soft tissue and

bone that support teeth. Among the periodontal pathogens, species, such as
Impact of
Prevotella intermedia, Tannerella forsythensis, and several forms of uncultivable
Etiology of
spirochetes play the major role in the pathogenesis. In severe chronic, recurrent and
especially aggressive forms of periodontitis, diagnosis of the species involved and,
Recommendations for
whenever possible, an optimized evidence-based antimicrobial treatment is indicated. In
microbial diagnostics
order to monitor alarming bacterial changes in the periodontal pocket, several
techniques, namely microscopy, culture, immunoassays, enzyme tests and DNA-based
From species identification
techniques, have been established and the methods are described in the first part of this
to antimicrobial therapy
review. In the second part, the selection and use of locally delivered (topical) and
Locally delivered
systemic antibiotics used adjunctively in periodontal therapy are discussed.
Expert Rev. Anti Infect. Ther. 5(4), 703–715 (2007) Impact of periodontal diseases
attachment, bone resorption and the number Periodontal diseases (gingivitis and periodon- of teeth involved. Advanced chronic or aggres- titis) are chronic bacterial infections with a sive periodontitis are forms associated with remarkably high prevalence and morbidity. For certain bacterial species (called periodontal Key issues
an overview of a current classification system for pathogens or marker bacteria) and affects all of periodontal diseases and conditions, a rather the soft tissue and bone-supporting teeth. An complicated topic that cannot be addressed in estimated 70% of the US adult population is its entire complexity in this review, the reader is affected by a kind of periodontitis with preva- referred to the paper by Armitage [1].
lence rates and severity greater among men †Author for correspondence Almost 100% of adults, but also 90% of than women and among blacks than whites.
Division of Oral Microbiology and children at school age, are periodically or Among those affected, between 3 and 15% are Immunology, Department of Operative and Preventive Dentistry occasionally affected by gingival bleeding, the susceptible to a rapid and advanced loss of per- & Periodontology, and Department most objective sign of early gingivitis. The iodontal attachment. They may develop of Medical Microbiology, mean percentages of maximum community aggressive forms of periodontitis, which cause University Hospital RWTH periodontal index (CPI) among 35–44 year- severe problems. These individuals require Aachen, Pauwelsstrasse 30, olds are higher in the WHO region of the prosthetic treatment within a short period of 52057 Aachen, GermanyTel.: +49 241 808 8448 Americas and the European region compared time. In addition, as periodontal diseases dis- Fax: +49 241 808 2483 with, for example, developing countries [2,3].
turb the integrity of oral mucous membranes, Gingivitis, with some exceptions, is a pol- periodontal pathogens can frequently be ymicrobial infection with no single associated detected in blood cultures. These frequent bac- KEYWORDS:
chlorhexidine, clindamycin,
bacterial agent and is reversible by adequate terial attacks, together with the host's inflam- culture, enzymatic BANA-test, oral hygiene. By contrast, periodontitis is matory reaction, may not only cause bactere- local delivery devices, metronidazole, nucleic acid-based moderately to rapidly progressive and is clini- mia but also (under some circumstances) analysis, penicillins, periodontal cally diagnosed on the basis of gingival inflam- septicemia, organ abscesses or endocarditis, as pathogen, periodontitis, tetracyclines mation, pocket formation, loss of gingiva well as cardiovascular disorders or low birth 2007 Future Drugs Ltd Horz & Conrads
weight when occurring during pregnancy, and the risk of disease and prognosis for the patient can be improved signifi- serious health conditions, such as coronary artery diseases, cantly when the presence or absence of periodontal pathogens cerebrovascular diseases and stroke, can be increased [4–10].
is monitored concurrently.
The direct financial burden of therapy in the USA resulting from periodontal diseases is estimated to be as high as Recommendations for microbial diagnostics in periodontitis
US$5–6 billion annually (total dental costs: $70.3 billion) To monitor periodontal pathogens or shifts in the bacterial com- with increasing tendency [11]. In a relatively small country, such munity in the gingival sulcus or the periodontal pocket, several as Germany, with high standards in dentistry, patients and techniques have been introduced. These procedures were only health insurance companies spend $5 billion each year with available at university institutions 20 years ago but currently, $20 as a minimum annual cost to treat the inflamed periodon- especially in Europe, most of the techniques are widely marketed tium of just one tooth [12]. Furthermore, in a 2-year retrospec- and principally available for every dental practice. tive examination of a large insurance company database, Albert Therefore, the first goal of this review is to provide an over- et al. revealed a possible association between periodontal treat- view of conventional (traditional) and molecular biological ment and increased medical costs per member per month for techniques for testing patients for periodontal infections. For associated systemic disorders [13]. detecting periodontopathogens, microscopy, culture, immuno- There is no doubt that periodontal diseases are a major assays, enzyme tests and DNA-based techniques have been burden and oral health is a WHO priority topic in the 21st introduced. Since chair-side (point-of-care) tests are in current Century [2,14].
development with increasing relevance in future, these will alsobe discussed. The second goal will be the presentation of the Etiology of periodontal diseases
current concepts of anti-infective drug therapy for supporting Chronic inflammation of the periodontium is a multifactorial the treatment of periodontal diseases. For the following tech- disease including several factors with triggering or enhancing niques – some personnel and cost intensive – a representative potential, such as underlying systemic risk factors, genetic sus- sample is the essential precondition for an appropriate diagno- ceptibility, negative (dys-) stress, tobacco use, suboptimal sis. As the sampling (i.e., where, how and when) is another and/or high sugar diet, poor oral hygiene and inadequate complex topic that can hardly be addressed here, we would like restorative procedures. However, most forms of gingivitis and to direct the reader to publications in more clinically orientated periodontitis finally result from the accumulation of tooth- journals, for example Beikler et al. [26]. and/or gingiva-adherent microorganisms in plaque. As docu-mented by numerous publications, periodontal diseases are associated with a shift in the periodontal bacterial flora, from The microscopic picture of native subgingival plaque from the healthy to the diseased state. The list of designated perio- healthy and diseased sites is strikingly different. Whereas healthy dontal pathogens might be long; however, according to the plaque consists of mainly coccoid cells or small-to-large rods with current state of knowledge, species, such as Aggregatibacter almost no motility, the plaque of diseased sites presents cells of high motility and mainly consists of rods, spirochetes or long fil- Eikenella corrodens, Filifactor alocis, Fusobacterium nucleatum, aments. The higher the motility of bacteria in plaque (i.e., the Porphyromonas gingivalis, Prevotella intermedia, Tannerella for- bacteria are more invasive/aggressive), the greater the likelihood sythensis and spirochetes appear to play a major role in the of further progression of the disease. Nevertheless, microscopic pathogenesis (for a recent overview of pathogen clusters and examination of freshly sampled plaque is not particularly practi- their virulence factors associated with disease, see [15–18]). It is cal for routine diagnosis. This technique requires special equip- important to note that our current picture of the microbial eti- ment, is time-consuming and, ultimately, gives results for only a ology of periodontal disease is rather incomplete; in particular, small portion of the microbial ecological system. This is why in as the microflora involved is highly complex consisting of a the past chair-side microscopic assessments as a diagnostic strat- large number of uncultivable species, with as yet unknown egy in periodontal diseases have been mainly applied [27]; how- functions at the diseased sites. For instance, some of the ever, the principal value of microscopy to provide preliminary recently discovered microbes in periodontal pockets are not insights in the microbial community should not be ignored. In even bacteria, but belong to archaea, a distinct domain of life particular, technical advancements, such as fluorescence in situ previously believed to be unimportant for human disease hybridization linked with confocal laser microscopy (CLM), [19–21]. In addition, the possible role of viruses (especially vari- with which bacterial species or groups are specifically ‘stained', ous forms of Herpesviridae) for periodontal disease has also enable a 3D pathogen-specific microscopic analysis and, thus, been the focus of recent research [22–25].
have led to a renaissance of microscopic techniques [28].
For diagnosis of the activity of the different forms of perio- dontitis, clinical symptoms (pocket formation, attachment loss and alveolar bone loss) alone may not be sufficient, as they For routine diagnosis in medical microbiology, approved culture provide a historical record only or have low predictive value, methods are still the gold standard for detecting and character- such as ‘bleeding on probing'. But predictions of recurrence of izing human pathogens. However, most periodontal pathogens Expert Rev. Anti Infect. Ther. 5(4), (2007) Diagnosis and anti-infective therapy of periodontitis
are strictly anaerobic and quite fastidious, and some are still Immunoassays & serological tests
uncultivable [29]. In some specialized laboratories, however, the For the detection of periodontal pathogens, polyclonal and cultivation of fastidious periodontal pathogens is well estab- monoclonal antibodies are available. Conjugated with fluores- lished. For culture procedures of anaerobic periodontal patho- cent reporter molecules, these antibodies can enhance the specif- gens, it is extremely important to bear in mind that these bacte- icity and sensitivity of light microscopic methods (see CLM, ria are killed by oxygen very rapidly. As a consequence, rapid previously). Additional immunological methods, such as ELISA transportation of the samples from the dental practice to the or latex-agglutination tests, were also designed for detecting per- diagnostic laboratory is most important. Cultivation needs time iodontal pathogens in plaque [49]. By combining immunoassays for growing and isolating the bacteria, and for biochemical dif- with chromatography in minicolumns, a chair-side technology ferentiation of the dominant species. Therefore, the results is currently in development in Germany. With a requirement of require 10 days or longer before reaching the dentist. Nonethe- approximately 104–105 bacterial cells per sample, the sensitivity less, the cultivation approach is important since resistance test- of these tests is generally low. However, immunological tests ing of pathogens is possible, which might become increasingly may become a considerable tool in the future for diagnosing important with the growing number of reported penicillin- and periodontal diseases, yet specific antigenic molecules for each metronidazole-resistant anaerobes [30,31], and rare species or marker pathogen still have to be identified [50,51].
those of secondary importance (e.g. Eubacterium spp., Pepto-streptococcus micros, Streptococcus constellatus, enteric rods or Nucleic acid-based analysis
pseudomonades [32]), usually not covered by molecular It has become widely recognized that a high proportion of approaches, can also be recovered if present in dominating pro- microbes (at least 50% of the microflora in humans) cannot be portions at the diseased sites. Furthermore, culture analysis will cultivated under state-of-the-art laboratory conditions and that always be an important reference approach or complementation those that can be grown in the laboratory are not necessarily the for advanced molecular techniques [33–39], which are addressed most relevant species. As mentioned previously, this difficulty later in this review. applies, in particular, to periodontal pathogens. Therefore, theywere one of the first candidates used as a target for nucleic acid- based identification techniques in the field of medical micro- A rapid but less precise diagnosis can sometimes be preferable biology. Two different main strategies have been pursued, based to a diagnosis that might be highly accurate but time-consum- on hybridization of genomic DNA of single bacterial species ing. Taking this as a rationale, chair-side tests were developed used as targets to total genomic DNA obtained from clinical based on the enzymatic activity of periodontal pathogens.
samples, and hybridization of short oligonucleotides of Pathogens, such as Treponema denticola (one of the few cultiva- 18–35 bp in length to the homologous region of specific genes ble spirochetes), P. gingivalis or T. forsythensis, produce trypsin- from individual bacterial species. While the former strategy, so- like proteases. If these enzymes are present in the paper-immo- called ‘checkerboard hybridization', has been applied in very bilized plaque tested, special substrates (benzoyl-DL-arginine-β- specialized laboratories and more frequently in research than in naphthylamide [BANA]) are hydrolyzed, leading to a color routine diagnosis [52,53], the use of the latter approach is com- reaction. According to the first publication by Loesche et al., mon and widespread in both fields. The reason for this is that the sensitivity of this technique lies between 90 and 96% and oligonucleotides are synthetically produced, short, stable mole- specificity between 83 and 92% [40]. Note that the terms sensi- cules and can be introduced easily into automated systems, the tivity and specificity here and in the following text refer to future trend of diagnostics. In addition, with the development other diagnostic methods, especially culture methods, and not of the PCR and sequence technology and recognition of the to disease progression. 16S rRNA gene as an outstanding phylogenetic marker gene, However, one of the major pathogens, specific probes and primers at almost every taxonomic level have A. actinomycetemcomitans, is negative for the trypsin protease been designed and used for detection and phylogenetic charac- reaction, which means that important cases must be diagnosed terization of known and novel human pathogens [54]. Since differently. Another disadvantage of this method is its insensi- then, 16S rRNA gene databases have been growing constantly tivity for diagnosis of the disease at an early stage, such as early and becoming increasingly robust, leading in turn to an onset in childhood and puberty [41]. However, until now it is increased usefulness and attractiveness of the 16S rRNA gene, the only practical and easy-to-use chair-side (point-of-care) test which had become the most common target for broad-ranged or available for studying, for example, the effect of antimicrobials species-specific microbial identification. Meanwhile, numerous on specific (proteolytic) microbes [42,43]. oligonucleotide-based test systems for different periodontal As an alternative, markers involved in inflammation and tis- pathogens have been developed [15,34,36,38,39,55–60] and different sue destruction, such as matrix metalloproteinases (MMPs; detection formats have been introduced into the European mar- especially MMP-8, including collagenases), are becoming ket. Two approaches are of particular interest. First, single path- widely used for predicting periodontitis but also other oral dis- ogens or the whole bacterial load in periodontal pockets can be eases using immunoassays [44–48]. These approaches could be accurately quantified by use of real-time quantitative PCR integrated in miniaturized point-of-care systems. (abbreviated inconsistently in the literature as ‘RTQ-PCR' or Horz & Conrads
‘qPCR'). This approach enables not only identification but also Locally delivered anti-infective drugs
determination of the proportion of individual species relative to For the treatment of periodontitis, several locally applied the total microflora, an important aspect for assessing the role products for the slow release of antimicrobials have been any given species might play in the disease. The second promis- approved within the last few years. The concept that local ing approach is multiplex species identification and (semi)quan- delivery of an antibiotic into the periodontal pocket always tification using microarray technology. Microarrays were origi- adjunctive to mechanical debridement achieves a greater and, nally introduced for differential expression profiling in both thus, more potent concentration than systemic delivery has eukaryotic and prokaryotic cells. They have also been applied to some striking advantages. The amount of drug delivered often support bacterial identification, especially in polymicrobial creates sulcular medication concentrations exceeding the infections [61–64]. An example of a commercially available micro- equivalent of 1000 µg/ml. This high level is bactericidal for array is the ParoCheck® chip for the rapid detection of ten or 20 the majority of bacteria and will cover some species otherwise different periodontal marker species [33]. not affected by the lower systemically delivered concentra- Despite intriguing advantages for species identification, the tions. On the other hand, the physiological flora (e.g., of gut, nucleic acid-based approach also has an important shortcoming skin and vagina) is not affected by the immobilized drug in when polymicrobial infections are to be analyzed. This is the periodontal pocket.
because the DNA extraction procedure (lysis conditions), aswell as the PCR-based techniques (access of primer to template sequences), might lead to a biased retrieval of amplicons [65].
Each of the three prominent tetracyclines, doxycycline, mino- Consequently, some bacterial species might be discriminated cycline and tetracycline itself, which all inhibit bacterial pro- against others. Such biases can be crucial since knowledge tein synthesis at the 30S ribosomal subunit, are commercially regarding the proportion of individual pathogens in a poly- available in form of local delivery devices. However, as the microbial infection is important for deciding the most adequate application procedure is not only time-consuming and rela- antibiotic therapy. tively expensive but has also led, in some cases, to suboptimal In future, diagnostic systems will be available for chair-side results, it did not gain very much popularity among dentists.
testing by targeting either microbial DNA or enzymes involved Nevertheless, all three are major tetracycline preparations for in infection/inflammation with a time requirement of probably local delivery: 12.7 mg tetracycline-HCl in an ethylene/vinyl 1 h or less [42,44,45,60,66,67]. However, proper interpretation of acetate copolymer fiber (known as Actisite®), 10% doxycy- the onsite findings and the measures to be taken can vary con- cline hyclate in a gel delivery system (known as Atridox®), and siderably from patient to patient so that, at least in some cases, the more lipophilic minocycline-HCl microspheres (known as the consultation of a microbiologist will still be indispensable.
Arestin®), confer a statistically significant improvement ofclinical and microbial parameters when compared with From species identification to antimicrobial therapy
mechanical SRP alone [71–76]. Page has recently shown that Severe chronic or aggressive forms of periodontitis often cannot Atridox and Arestin (as well as the device PerioChip® [see be controlled by instrumental treatment (scaling and root plan- chlorhexidine (CHX) section]) enabled a significantly greater ing [SRP]) alone. In addition, refractory subjects or non- reduction of periodontal pocket depth and increase in clinical responding sites are also a problem. Recurrence is mainly periodontal attachment level (∼0.8 mm) than sole mechanical related to the persistence of pathogens in the pocket after treat- treatment. However, the increase of clinical attachment level ment or to the production of specific bacterial virulence factors was on average larger in deeper than in shallower pockets [77].
(leukotoxin and encapsulation) interfering with the host The effect of tetracycline fibers was recently reproven [78].
defense. It could also be due to the recolonization of treated However, as a matter of fact, these fibers produced in the USA sites from oral reservoirs, such as the deep sites of mucous (ALZA Corp.) did not prevail on most markets (including the membranes [68]. In this context, it is evident that local or sys- German market), probably because of the time-consuming temic treatment with an antimicrobial agent is a valuable placement and replacement procedure. Two further tetracy- adjunctive to mechanical therapy. cline alternatives, Atridox gel and Arestin microspheres, exist In the early 1980s, systemically applied antimicrobials were but the marketing strategy is in a constant state of flux. For first introduced for the treatment of periodontitis. However, instance, the Atridox gel was retracted from the European concern emerged regarding the risks of hypersensitivity, market in 2006 and is currently almost exclusively available gastrointestinal disturbances and bacterial resistance, and for US and Canadian dentists (for background information, regarding the problem of reaching an adequate concentration the delivery platform for Atridox is Atrigel®, a QLT Inc. prod- at the periodontal site for a sufficiently long period of time uct and licensed to CollaGenex Pharmaceuticals in the USA [69]. As a consequence, locally (topically) applicable formula- and to PharmaScience Inc. in Canada). On the other hand, tions (e.g., slow-release matrices) of antimicrobial agents were the Arestin microsphere product (OraPharma Inc.) was developed. Such formulations are of particular use in cases announced for marketing in Europe by 2005–2006 but has where systemic drug application seems inappropriate, such as not been launched in this area so far. Meanwhile, both prod- localized periodontitis [70].
ucts, where available, have become important in periodontal Expert Rev. Anti Infect. Ther. 5(4), (2007) Diagnosis and anti-infective therapy of periodontitis
therapy, especially in cases of locally expressed recurring or single usage. It has been applied primarily for controlling dental refractory periodontitis and especially in patients with systemic plaque in order to reduce the risk of caries or gingivitis. When used during nonsurgical and surgical periodontal treatment,CHX offers three recognized advantages: • A bacteriostatic effect In Europe, but not in the USA, an injectable lipid-like vehicle • Improved wound healing based on glycerol monooleate and sesame oil containing 25%metronidazole benzoate (Elyzol®; Dumex-Alpharma, Copen- • General plaque control as an alternative when proper hagen, Denmark) is used frequently with apparent evidence of tooth-cleaning is difficult or painful efficacy. After being syringed into the pocket, the gel first Furthermore, a number of studies have indicated that CHX becomes more liquid owing to body temperature but after con- is also applicable for direct anti-infective treatment of perio- tact with sulcus fluid, the carrier turns into highly viscous liq- dontitis but concentration and exposure time need to be uid crystals and immobilizes (based on ambient responsive liq- adjusted. While simple intracrevicular irrigation has only a uid crystal technology, Camurus®; Lund, Sweden).
short-term effect on the sulcus or pocket flora, long-term effi- Metronidazole benzoate gradually disintegrates into metronida- cacy of CHX on the periodontal microflora increases with zole and the drug is released into the periodontal pocket for duration of exposure. In order to reduce periodontal pathogens approximately 24–32 h after placement. Normally, two such significantly, a slow-release device might be advisable [81,82].
applications, 1 week apart, are recommended. High levels Cosyn and Sabzevar summarized the results of eight studies in (100–1000 µg/ml) of metronidazole have been initially meas- which gel vehicles with 0.2–2.0% CHX were used [83].
ured in the sulcus fluid for the first 8 h and therapeutic dosages Although some evidence of temporary reduction of bleeding on (5–20 µg/ml) have been reported for another 24 h. Given its probing was found, the use of the adjunctive medicament did spectrum against anaerobic bacteria, which are by far the most not have a beneficial effect on the overall treatment outcome.
common of all periodontopathogens, metronidazole gel in The matrix of CHX gel in its current form seems not to be combination with SRP appears to be more effective in terms of appropriate to further support the substantivity of CHX. both clinical and microbiological improvements compared with A second-generation slow-release device, such as a bioabsorb- pure mechanical treatments. However, controversial results do able chip containing 2.5 mg CHX in a cross-linked hydrolyzed exist [79,80], which might be due to three facts: gelatine matrix, was developed recently (PerioChip, Astra- • The sometimes rapid, burst-like, release of metronidazole Zeneca). While the chip is degraded, CHX is gradually released together with rapid elimination from the pocket, for for approximately 7–10 days with concentrations approaching, instance, when the sulcus fluid rate is increased in on average, 125 µg/ml within the gingival crevicular fluid. A inflamed pockets; systematic review performed by Cosyn and Wyn has listed dis-crepant results using CHX chips [84]. Although earlier multi- • The primary evaluation of chronic periodontitis patients center studies indicated significantly higher pocket reduction responding well to SRP alone without the need for and clinical attachment gains, some more recent studies failed adjunctive antibiotics; to confirm the value of CHX chips. However, while chip • The presence of tissue-invasive anaerobes, especially spirochetes, administration itself is a standardized aspect of treatment pro- which can hardly be reached by topical antibiotics.
cedure, the application intervals or further aspects might have However, the gel formulation enables minimal amounts of varied among these studies. For instance, by choosing a regime drug to achieve high concentrations, alleviating many adverse of 3-month intervals of CHX chip administration, the overall reactions and unpleasant side effects, as is often the case with clinical outcome might be better than with SRP alone [85]. Of systemic administration. course, some side effects of CHX, such as staining of teeth, In conclusion, after meta-analyzing a high number of pre- taste disturbances, increase in calculus accumulation and the and contra studies, it is still difficult to ascertain whether additional costs of chip production, are aspects that have to be local delivery of metronidazole as an adjunct to SRP conveys taken into account. Finally, it should be noted (although well a significant clinical advantage over SRP alone.
understood and self-evident), that for an optimum beneficialeffect of (every) adjunctive chemotherapy, a proper disruption of the biofilm is indispensable.
The use of CHX as an auxiliary antibacterial (and antifungal)agent in dentistry has a long tradition and is well documented.
Other local anti-infective drugs
Its mode of action relates to disintegrating the microbial cell wall, increasing microbial cytoplasmatic membrane permeabil- [PVP–iodine]) might constitute a valuable adjunct to current ity and, ultimately, leading to cell lysis and alteration of bacte- periodontal therapy because of its broad-spectrum antimicro- rial adherence to the pellicle-covered teeth. As a highly kationic bial activity, low potential for developing resistance and adverse disinfectant, CHX exhibits high substantivity, which means reactions, broad availability, ease of use and low financial cost.
that it remains on oral surfaces for a prolonged period after a Hoang et al. concluded that addition of subgingival Horz & Conrads
PVP–iodine irrigation to conventional mechanical therapy is a improvement following LDD treatment was observed at the cost-effective means of reducing periodontal pathogens and most severely diseased sites [47,98,104,106–108]. The lack of any helping to control disease [86]. However, in chronic periodon- detectable effect on the (physiological) bacterial flora and on titis, no effect was seen by Zanatta et al. [87] and by testing cases antibiotic resistance seems evident not only for the oral cavity of class II furcation involvements, again no adjunctive effect but also for the intestinal and vaginal tract, as well as the skin was seen in another study [88]. Finally, some ‘alternative' [81,109–111]. The reason why LDD treatment might not affect the approaches formulating medicinal herbs or green tea catechin physiological flora is that 20 mg twice daily leads to serum con- in the form of biodegradable chips or strips for subgingival centrations of 0.7–0.8 µg/ml and to steady state concentrations application have recently been reported [89,90], and the develop- of around 0.4 µg/ml. This concentration of doxycycline is sig- ment of various further local formulations can be expected in nificantly lower than most MICs of periodontal species, espe- cially when drug diffusion is additionally inhibited by the sub-gingival biofilm [81]. However, although microbial resistance appears to not be induced under prolonged therapy with LDD treatment, the potential of any inverse development should be Since the early 1980s, tetracycline has been recognized as a kept in mind and further examined in future studies. drug with elevated gingival crevicular fluid levels inhibitory for In summary, as new diagnostic systems will soon be able periodontal pathogens [81,91,92]. Several smaller clinical trials (and available) to measure the destructive MMPs chair side using various designs have been conducted evaluating the effi- and as LDD has a worldwide recognized anti-MMP effect, a cacy of tetracycline adjunctive to SRP in the treatment of the new concept for diagnosing and treating periodontal disease then-called ‘adult periodontitis'. In these studies, probing may be emerging. depth and attachment level were slightly improved in the tetra-cycline group but were rarely significant (reviewed in [81]). By contrast, double-blind clinical studies enrolling patients with Clindamycin (lincosamide) inhibits the bacterial protein syn- refractory or recurrent periodontitis demonstrated that adjunc- thesis by binding to the 50S ribosomal subunit. Depending on tive systemic tetracyclines, especially doxycycline, significantly the local drug concentration and the susceptibility of bacteria, reduced major clinical parameters relative to SRP and placebo, clindamycin has either a bacteriostatic or bactericidal effect.
yet failed to prevent further disease progression as was shown in While this drug is active against anaerobes associated with other studies. Profound clinical studies on the then-called periodontitis, it is not active against aerobic Gram-negative per- ‘localized aggressive (juvenile) periodontitis' led to similar iodontal pathogens, such as E. corrodens and, unfortunately, results [93–95]. Temporary improvements were probably due to A. actinomycetemcomitans. However, the orally administrated the repression of A. actinomycetemcomitans at the infected clindamycin-HCl has been shown to penetrate into the gingival site(s) but a complete elimination of this marker bacterium crevicular fluid and to achieve and maintain high and effective could not be achieved using doxycycline or minocycline [96,97].
For a recent metareview see [98] and for predicting changes in Owing to its acidic nature and to its effect on the Gram-neg- antibiotic susceptibility, see [99].
ative intestinal bacteria, minor adverse effects, such as diarrhea, In summary, systemic administration of tetracyclines as abdominal cramping, esophagitis and stomach irritation, are adjunct to SRP may yield some benefits in certain clinical con- not uncommon. A severe adverse effect, the pseudomembran- ditions, such as localized aggressive and refractory periodontitis ous colitis has also been attributed to administration of this where A. actinomycetemcomitans is the principal agent.
drug, however, more frequently in the form of clindamycin Tetracyclines have a ‘second nature' as they are not only inhib- phosphate than clindamycin-HCl [81].
itors of microbial growth but also inhibitors of MMPs, a family Gordon et al. demonstrated that 11 subjects out of a total of of enzymes that degrade extracellular matrix molecules, such as 13 tested experienced no further loss of clinical attachment collagen [100]. When periodontal disease is present, increased after clindamycin therapy and the number of active sites secretion of MMP-8 and -9 occurs by infiltrating poly- decreased significantly [113,114]. Other studies confirmed these morphonuclear leukocytes, leading to digestion of collagen, a results, demonstrating that clinical improvement was associated main structural component of the periodontal ligament. A sub- with a reduction of the Gram-negative periodontopathic flora antimicrobial (or low) dose of doxycycline (abbreviated incon- [81,98,115,116], which fortunately seem not to become resistant to sistently as SDD or LDD, 20 mg twice daily, Periostat®) down- clindamycin over time [117]. regulates the collagenase activity in inflamed periodontal tissues However, as A. actinomycetemcomitans is intrinsically resistant (and also in inflamed skin under acne or rosacea conditions) by to clindamycin, prior to initiating therapy, microbial testing is a mechanism unrelated to its antimicrobial properties [101,102]. A strongly recommended to screen for the presence of A. actino- number of double-blind, placebo-controlled clinical trials have mycetemcomitans and, with minor impact, E. corrodens. If these demonstrated clinical improvement while the subgingival flora species are present in high numbers, clindamycin is contra- was stable and an increase in antibiotic resistance was not found indicated. If present in relatively low numbers, and if other [82,102–105]. As found frequently in further studies, the greatest anti-infective options (e.g., owing to allergy against penicillins) Expert Rev. Anti Infect. Ther. 5(4), (2007) Diagnosis and anti-infective therapy of periodontitis
do not exist, clindamycin could, however, still be prescribed metronidazole exist, including gastrointestinal disorder, vomit- since its second mode of action, the stimulation of granulocyte ing, headache, anorexia, drowsiness, depression, skin rashes and [118] could indirectly help in eradicating vaginal or urethral burning [81]. Alcohol ingestion under therapy A. actinomycetemcomitans and E. corrodens. However, success- is strictly contraindicated as metronidazole affects the hepatic ful elimination of these pathogens should be confirmed by enzyme alcohol dehydrogenase, causing accumulation of acetal- subsequent diagnostic tests. In addition, due to the potential dehyde in the blood. Furthermore, metronidazole is strictly con- serious adverse effects, although relatively rare with clindamy- traindicated for nursing mothers or during pregnancy and, prin- cin-HCl, this drug should be reserved for aggressive and/or cipally, as a single drug in cases of periodontitis in which aerobic refractory periodontitis patients.
pathogens, such as A. actinomycetemcomitans and E. corrodens,play a key role [127].
In summary, the adjunctive use of metronidazole results in Penicillins are a broad class of bactericidal antibiotics that significant reduction of anaerobic periodontal pathogens, inhibit the enzymatic activity of transpeptidases (also referred to including P. intermedia, P. gingivalis, T. forsythensis and spiro- as penicillin-binding proteins), which are essential for bacterial chetes. Clinical improvement has been reported to be better in cell wall (murein) synthesis. All penicillins consist of a β-lactam deep pockets (>5 mm) than in moderate sites (≤5 mm) [128,129]. ring, a thiazolidine ring, and an acyl side with varying substitu-tions yielding penicillin derivates with improved qualities, Other systemic monotherapies
including stability against gastric acid, absorption, serum con- Fluoroquinolones are active and bactericidal by inhibiting the centrations and the antimicrobial spectrum. In particular, amox- bacterial topoisomerases class II (gyrase), which interferes icillin, a semisynthetic penicillin, has excellent activity against with bacterial DNA packaging, transcription and replication.
oral bacteria, is absorbed well following oral administration and Older quinolones, such as ciprofloxacin, are only recom- reaches high levels in sulcus fluid or the periodontal pocket.
mended as part of combined therapies (see later). However, However, two main problems associated with the administra- newer fluoroquinolones (moxifloxacin and levofloxacin) have tion of amoxicillin are allergic reactions (as are common for all an extended spectrum of activity, including against Gram-neg- penicillins and, to some extent, for related cephalosporins as ative (aerobic and anaerobic) periodontopathogens [127,130,131].
well) and its high susceptibility to bacterial β-lactamases, which However, as they serve as ‘reserve antibiotics' for intensive care inactivate the antibiotic through hydrolyzation of the β-lactam patients, their regular prescription – even in cases of aggressive ring. The β-lactamases are relatively common in periodontal periodontitis – cannot be recommended.
pockets and correlate positively with age of patient and depthof pocket [119], reducing the overall drug efficacy. The efficacy Amoxicillin plus metronidazole
of Augmentin® (the combination of amoxicillin with the β- The combination of amoxicillin plus metronidazole (also lactamase inhibitor clavulanic acid) is theoretically higher than known as the ‘van Winkelhoff combination' after the first that of amoxicillin alone, as has been tested in a few clinical tri- describer [132]) in conjunction with SRP in periodontal therapy als, but the results are still conflicting [120–122]. In summary, provides a substantial benefit over SRP alone. Clinical improve- clinical studies do not support the use of Augmentin as a partic- ment and pathogen reduction have been reported in patients ularly effective adjunctive antibiotic in advanced periodontitis.
with periodontitis associated with A. actinomycetemcomitans It may provide some benefit over mechanical therapy for cer- [133–136] but also with other severe periodontitis cases. In the tain patients but other amoxicillin-containing combinations study by Winkel et al., in which 49 adult periodontitis patients (see later) appear more effective.
were included, the antibiotic treatment group demonstratedsignificantly greater improvement in bleeding, probing pocket depth and clinical attachment level as P. gingivalis, P. intermedia Metronidazole, a 5-nitroimidazole, specifically targets anaerobic and T. forsythensis were reduced [136]. Similar results were found microorganisms including anaerobic bacteria, anaerobic proto- in a placebo-controlled clinical trial by Rooney et al. [137]: zoa, such as trichomonades or anaerobic parasites. In the oxy- reduction in bleeding, suppuration and pocket depth, as well gen-free cytoplasma of these organisms, the highly oxidized as a gain in attachment level, could be improved best in the (nitrogroup) drug causes a radical chain reaction as the short- metronidazole/amoxicillin group followed by the metronida- lived free radicals interact with bacterial DNA and, possibly, zole/SRP and amoxicillin/SRP groups with these clinical other macromolecules, resulting in cell death. Although resist- parameters being significantly different compared with the ance to metronidazole occurs in some anaerobic bacteria, for placebo/SRP group. In addition, recent data from Guerrero example, intestinal Bacteroides fragilis and related species [123,124] et al. indicate that a 7-day adjunctive course of systemic met- but also oral Fusobacterium, Porphyromonas and Prevotella spp.
ronidazole and amoxicillin significantly improves the short- [30,31], resistance among anaerobic periodontopathogens is (still) term clinical outcomes of full-mouth nonsurgical periodontal relatively rare but should (or probably must) be monitored in debridement in subjects with generalized aggressive periodon- future. High levels of metronidazole can be achieved in the peri- titis [138]. In addition, data from Slots and Ting suggest that odontal pockets [125,126]. A number of common side effects with metronidazole/amoxicillin is an appropriate choice for Horz & Conrads
approximately 70% of advanced periodontitis patients [93].
polymicrobial disease, we are equipped with a wide range of However, given the increasing number of patients allergic to modern diagnostic techniques, including microarrays, able to penicillins, microbial diagnosis should be performed prior to detect simultaneously a growing number of periodontopatho- administration of metronidazole/amoxicillin and, in the genic species. While complete elimination of most virulent absence of A. actinomycetemcomitans, alternative antibiotic microorganisms might be impossible, a significant reduction in drugs should be considered.
bacterial cell number by adequate antimicrobial therapy in con- In summary, a therapy of metronidazole/amoxicillin in junction with SRP results, at least, in an improvement in perio- conjunction with SRP appears to be the treatment of choice dontal health. Since improvement has been consistently for generalized aggressive periodontitis and for any other reported to be better when treating sites with deeper pockets, forms of periodontitis associated with A. actinomycetemcomi- the use of an adjunctive antimicrobial treatment to support tans. However, a few exceptions exist, in particular when per- SRP in mild or moderate cases should be considered carefully, iodontal lesions are associated with pseudomonades, Gram- especially in light of adverse side effects and development of negative enteric rods or E. corrodens, which are intrinsically drug resistance. resistant against metronidazole and also, to a large extent, toaminopenicillins [32,81,139–141]. Oral microbiology is an emerging research area owing to its Other systemic combinations
importance not only for dentistry but for the entire body and The combination of ciprofloxacin/metronidazole has been sug- general medicine. In the next few years, new oral microbial gested as adjunctive therapy for periodontal infections when species and genera and, presumably, even novel divisions will enteric rods, pseudomonads or A. actinomycetemcomitans are be characterized. On the other hand, known oral taxa will be present or in cases of penicillin allergy [139,142].
reclassified and renamed, as has for instance occurred most This combination is useful since ciprofloxacin has an excel- recently with Aggregatibacter (formerly Actinobacillus) actino- lent activity against a wide range of Gram-negative aerobic and mycetemcomitans. This means that the etiological picture of facultative anaerobic bacteria with the gap in the spectrum of periodontal diseases becomes more and more complex. For Gram-negative anaerobes being filled by metronidazole. Drug- diagnosis, chair-side (point-of-care) tests will be available and related side effects with ciprofloxacin are generally mild and used by some specialized practices while others will send sam- consist primarily of photosensitivity, headache, dizziness, light- ples to laboratories that have a variety of diagnostic tools to headedness, nausea, abdominal discomfort or epigastric upset.
quantify putative pathogens and/or monitor host-specific As with almost all antibiotics, ciprofloxacin is contraindicated markers associated with genetic predisposition, inflammation during pregnancy and lactation. and tissue destruction. Concern will arise regarding the com- Another combination could be the use of metronidazole with plexity of incoming data and its clinical handling, especially as amoxicillin plus clavulanic acid (Augmentin, see previously); only a few new drugs will become available and most of them however, no real advantage over metronidazole/amoxicillin was as locally deliverables. observed in the vast majority of periodontal cases. In addition, Some periodontologists will appreciate the new evidence- the clavulanate component is strongly acidic and, for some based dentistry using selected diagnostic and treatment patients, difficult to tolerate, so the only indication is given options, while others might prefer to rely on clinical diagnosis when penicillin-resistant β-lactamase-producing E. corrodens is solely and will probably still use nothing but mechanical involved. This pathogen is susceptible to amoxicillin/clavu- debridement to treat periodontitis. An ongoing discussion of lanate and the metronidazole component would cover the the controversial findings reviewed in this article is needed and more guidelines should be established by the dental societiesand directed to the individual practitioner. However, every case or patient has an individual form of periodontitis with an Most severe periodontal diseases occur and progress due to the individual mixture of underlying risk factors. This means that destructive activity of opportunistic pathogenic micro- the dentist, while facing exponentially growing information, organisms that overgrow and infect the subgingival area. Several still has to find individual solutions. so-called periodontopathogens have been characterized but stilla considerable proportion of microbes, including life forms other than bacteria, such as methane-producing archaea, para- We thank Morgana Eli Vianna and three anonymous reviewers sites and viruses, await detection and elucidation of the role for comments on a draft of the manuscript.
they might play in this disease. Understanding and treatingperiodontal disease is particularly challenging since the micro- flora involved are not only different from patient to patient The authors have no relevant financial interests related to this but change constantly within a patient along with other rap- manuscript, including employment, consultancies, honoraria, idly shifting parameters, such as pH, redox potential and gin- stock ownership or options, expert testimony, grants or patents gival crevicular fluid rates. To deal with such an intractable received or pending, or royalties. Expert Rev. Anti Infect. Ther. 5(4), (2007) Diagnosis and anti-infective therapy of periodontitis
Key issues
• Although our perspective on the complexity of the microflora associated with the multifactorial disease periodontitis has improved enormously in the past few decades, we are facing a constantly growing number of newly identified periodontal species with as yet unknown function at the infected sites.
• Since species-directed antibiosis can be crucial for successful treatment of periodontitis, a variety of approaches aimed at pathogen identification, including real-time quantitative PCR, microarrays and miniaturized enzyme tests, have been established and are commercially available as high-end diagnostic systems.
• Besides nucleic acid-based detection methods, chair-side diagnosis of metalloproteinase (collagenase) activity and therapeutic inhibition of this enzymatic activity by administration of low (subantimicrobial) doses of doxycycline appears to be a rising and promising new concept. • For periodontal therapy both, local and systemic, no general consensus worldwide and even not within Europe exists regarding the choice of the anti-infective drug, indicating the lack of a global gold standard for treating periodontal diseases. • For treatment of generalized aggressive periodontitis and for cases in which the prominent marker pathogen Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans is involved, however, general agreement exists that the drug combination metronidazole plus amoxicillin in conjunction with scaling and root planing is the treatment of choice.
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Tel.: +49 241 963 2141 metronidazole and professional plaque Fax: +49 241 808 2483 removal in the treatment of chronic

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