4.  Infection Control in Periodontics

Criteria for Therapeutic Success

The rationale behind antimicrobial treatment in periodontal infections is easy to define; however, it proves more difficult to attain in practice. A new equilibrium between bacterial flora and periodontal tissues needs to be established, and any pathogenic agents present within the oral cavity must be eradicated. The difficulty in reaching these goals is mostly linked to the complex nature of bacterial reservoir sites and the difficulty in performing efficient hygiene procedures in these sites.

The periodontal pocket can be compared to an ecologic niche; this is further supported by the fact that edentulous patients and children present no pathogenic species. For an adult patient presenting with periodontal disease, the most significant risk factor for disease recurrence, among all measurable and bacteriologic clinical signs, is the persistence of periodontal pockets (Goodson 1994).

Conditions for clinical success are directly linked to effective infection control. These conditions are fulfilled once the attachment system has achieved stability, in the context of periodontal health. Variable results may be explained by:

• The presence of numerous etiologic factors, eg, high counts of different bacterial species involved in infection, species that are difficult to identify or culture, and sampling difficulties

• The diversity of clinical presentations: several disease subtypes lead to tissue destruction, and some may progress episodically

• The degree of severity linked to the presence of multiple risk factors, eg, systemic factors, difficulty in obtaining patient compliance, local factors such as those related to the condition of dentition

In treating advanced forms of periodontal disease, there are numerous conditions for success; these are directly correlated with the possibility of:

• Treating chronic and aggressive periodontitis globally

• Controlling all sites in a given patient

• Providing coordinated, multidisciplinary care designed to treat any dental involvement that may compromise periodontal health

• Knowing to what extent a tooth may be preserved when periodontal tissue is severely compromised.

Both esthetic and functional factors must be taken into account when managing advanced forms of severe periodontal disease where dental displacements, migrations, and edentulous areas are present. Prosthetic treatment options should be designed to allow optimal periodontal preservation and to facilitate periodontal maintenance.

Periodontal treatment per se is part of a more complex treatment strategy. Higher complexity levels are encountered when treatment success depends on nonperiodontal parameters; these include endodontic or orthodontic treatment procedures, splinting, provisional prosthetic constructions, implants, and other functional rehabilitation procedures.

Management of complex cases involves devising efficient modalities for treatment provisionalization. This is a difficult task and requires a lot of skill: an ill-fitted provisional crown may represent a local factor for treatment failure, and absence of a posterior occlusion is detrimental to treatment of periodontally compromised anterior teeth. Conditions for treatment success take into account all aspects of global treatment, while simultaneously ensuring stable control of infection.

Therapeutic procedures aiming at global treatment can be grouped into two categories:

• The first category includes the treatment procedures aiming at control of periodontal infection and reduction of bacterial load. The etiologic agent is eliminated or reduced until periodontal flora containing species compatible with periodontal health replaces pathogenic flora for a prolonged time. This is the first phase of periodontal management.

• The second category includes the treatment procedures aiming at repairing or restoring damaged dental and periodontal structures, thereby achieving functional restoration. This second phase cannot be initiated until the first phase has been successfully achieved. It will be described in the following chapters through clinical cases (see specifically the section on high-risk sites in chapter 6).

Periodontal microbiologic conditions can be modified in four different ways: through efficient plaque control, root scaling and planing, antimicrobial therapy (essentially antibiotic therapy), and surgery. At first, these four approaches seem easy to carry out; however, successful management of advanced periodontitis remains a difficult task because the efficacy of each of these methods is variable. Satisfactory results are achieved through a judicious combination of these four approaches.

Effects of Bacterial Plaque Control

The development of supragingival plaque precedes that of subgingival plaque; growth of the latter gradually selects pathogenic, anaerobic species, which exert toxic effects on periodontal tissue. Therefore, efficient plaque control measures should be established before any mechanical treatment is undertaken. Studies have shown that in patients with poor plaque control, there is a poor response to periodontal treatment (Nyman et al 1975); on the other hand, patients with chronic periodontitis who maintain good levels of plaque control are able to maintain satisfactory periodontal health over a 5-year period (Lindhe and Nyman 1975).

No invasive treatment should be initiated before significant improvement of plaque control.

Meticulous elimination of supragingival plaque, that is, reduction of plaque to indices below 20%, leads to significant alteration of the quantity and composition of subgingival bacterial flora (Dahlen et al 1992). Improvement of oral hygiene reduces bacterial load in deep pockets as well as in sites with lower probing scores, such as those found in gingivitis or untreated moderate periodontitis.

Growth of subgingival plaque can be reduced or arrested by toothbrushing and flossing. By limiting the accumulation of supragingival plaque, it is possible to interfere with the formation and maturation of pathogenic microbiota. Efficient supragingival plaque control deprives the subgingival environment of nutrients necessary to its growth. Also, supragingival plaque control reduces the intensity of gingival inflammatory response: inflammatory exudates, which represent an important source of nutrients for bacterial populations, are produced in smaller quantities (Listgarten 1999). In addition, adequate plaque control often means the patient is highly motivated and complies with recommendations given by the periodontist or dental hygienist. Individual hygiene is associated with regular professional periodontal maintenance, at a frequency determined according to the patient’s personal risk factors.

 

Assessment of plaque control:

• Evaluation of plaque indices

• Evaluation of bleeding indices

Constant evaluation of plaque indices implies that the patient should brush after each meal. It is unacceptable for a patient to show up at an appointment without having brushed previously.

Effects of Scaling and Root Planing

Mechanical treatment consists of treating root surfaces manually with curettes or with ultrasonic scalers in order to eliminate the bacterial biofilm, endotoxins, calculus, and local factors contributing to plaque retention. Mechanical treatment includes supragingival scaling, subgingival scaling, and root planing. The overall objective of this aspect of treatment is to render root surfaces biologically compatible with the formation of a healthy new attachment apparatus.

Cementum elimination

Should all of the root’s cementum tissue be eliminated? The biofilm is found at the surface of cementum tissue. Some toxins and bacteria are able to infiltrate the more superficial cementum strata, which consequently become unfit for the formation of a new attachment. The objective of scaling and root planing is to disorganize these bacterial niches and polish root surfaces while preserving a maximum amount of uninfected cementum (Figs 4-1a to 4-1c). This is a difficult task for several reasons:

• Cementum tissue width is reduced, and it is easily eliminated in just a few curette strikes.

• Complete absence of cementum prohibits the formation of new attachment tissue.

• Exposure of root dentin and dentinal tubules, especially when this occurs brutally, may cause root hypersensitivity and subsequent patient discomfort (Nyman et al 1988).

Calculus elimination and attachment gain

In terms of efficacy, there is no difference between manual instrumentation and ultrasound devices. However, manual scaling is 20% to 50% more time-consuming. Best results are obtained when both methods are combined (Sherman et al 1990).

• In small pockets with probing depths less than 4 mm, it has been estimated that up to 86% of calculus can be eliminated without resorting to surgical methods.

• In medium-depth pockets with probing depths ranging between 4 and 6 mm, up to 43% of calculus can be removed manually, compared with 76% surgically. Pocket depth reduction is more significant after surgical intervention.

In deep pockets featuring probing depths exceeding 6 mm, 32% of calculus can be removed manually, compared with 50% surgically. Pocket depth reduction and attachment gain are more important after surgical treatment. Recurrence is more frequent when initial treatment consists of root scaling and planing only, compared with root scaling/planing in conjunction with periodontal surgery (Ramfjord et al 1987; Becker et al 1988).

• In invaded furcations, elimination of calculus is always somewhat random, as are clinical attachment gains, compared with gains obtained for monoradicular teeth (Loos et al 1988). Surgical access to the site improves calculus elimination, with a removal rate no higher than 68%, regardless of the clinician’s experience. This efficacy rate decreases as periodontal pocket depth increases (Fleischer et al 1989).

After 24 months, attachment loss increases in 25% of molar-furcation cases, compared with 10% for molars with flat-surface sites (Loos et al 1989). In another study, similar clinical improvements were found among nonsmokers and ex-smokers but not among subjects who smoked at the time of study (Haffajee et al 1997).

Bleeding indices

Bleeding indices improve in sites where pocket depth is equal to or less than 4 mm, but they remain high in deeper pockets. In furcations, initial values return 24 months after root scaling and planing (Loos et al 1989).

Bacterial flora

Combined root scaling and planing allow for a relative increase in the total numbers of beneficial bacteria and reduce bacterial loads and the amount of pathogenic species present in all sites, except in furcations where the bacterial load decrease is less significant (Loos et al 1988). Porphyromonas gingivalis is eliminated from most sites whereas Actinobacillus actinomycetemcomitans tends to persist in different sites (Renvert et al 1990).

Where probing depths exceed 6 mm, there is a significant decrease in the number of pathogens from the red complex (P gingivalis, Treponema denticola, Tannerella forsythensis) in nonsmokers. In smokers, on the contrary, there is an increase in bacterial population numbers. P gingivalis counts tend to decrease in all pocket subtypes. T forsythensis counts seem to decrease only in small pockets (Haffajee et al 1997).

Taken together, these elements illustrate the difficulty posed by deep lesions and furcations when they are treated nonsurgically. In these cases, it is necessary to resort to other treatment modalities.

Root scaling and planing treatment procedures are not sufficiently effective to eliminate red complex bacterial populations altogether. Neither do they suffice to remove all root calculus, particularly that found in deep pockets. Surgical management significantly improves clinical results obtained after root scaling and planing. However, the outcome is not as favorable in smokers as it is in nonsmokers. Potential for repair in severely compromised sites becomes apparent during the first series of scaling and root planing sessions, which, in the case of severe periodontal disease, are usually performed in four to six consecutive sessions. Treatment rationale therefore requires that scaling and root planing be initiated immediately after the patient has acquired satisfactory plaque control. To reduce tissue damage, local anesthesia is avoided a/>

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Jan 20, 2015 | Posted by in Periodontics | Comments Off on 4.  Infection Control in Periodontics
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