Microbiological Effects of Scaling and Root Planing

Dr. Susan Kinder-Haake

Dr. David Isaacs

At the end of this lecture, you will be asked if you would like to take this course for continuing education units.
California Continuing Education Credits: 3 units

Scaling and root planing has both local and systemic sequelae.

Locally, the results of scaling and root planing are:

• Debridement of bacteria and calculus
• Removal of infected cementum and dentin
• A shift in the microbial population

The microbial shift is effected by two mechanisms

• The removal of bacteria by scaling and root planing
• The clinical outcome of scaling and root planing which alters the environment favoring population by certain bacteria over others
  • Decreased pocket depth
  • Smooth root surfaces
  • Reduction of inflammation

Scaling and root planing also has systemic effects. These are a bacteremia and a host immune response.

The reported incidence of bacteremia after dental procedures varies widely. Incidence rates of 17% to 93% have been reported by various studies, following dental extractions. Variations in sampling techniques and in culturing techniques are probably responsible for this wide range of results. Optimal results are presently being obtained when utilizing lysis-filtering techniques for sampling and anaerobic conditions for culturing the samples. The lysis-filter techniques invovle lysis of RBCS in the blood sample and a filtering step to isolate bacteria from the sample.

The incidence of bacteremia during different dental procedures was studied by Heimdahl and co-workers in 1990 utilizing these conditions of sample handling and culturing. The results of this study are shown in Table 1.

Based on this study it can be seen that immediately after undergoing scaling and root planing the majority of patients (70%) will have a bacteremia.

The same study also showed that ten minutes after the procedure, the incidence of bacteremia is down to 30%. This indicates that the host immune response is effective in eliminating the bacteria from the bloodstream, resulting in the rapid decline in the recovery of bacteria. For this reason, it is referred to as a transient bacteremia.

Clinical Implications of Bacteremia

The viridans streptococci are important in the etiology of infective endocarditis. The data from Heimdahl et al (Table 1) indicates that over half of the scaling and root planing procedures resulted in a bacteremia involving this group of microorganisms. Other periodontal species found in endocarditis include Actinobacillus actinomycetemcomitans and Eikenella corrodens. Further, in patients with a suppressed immune system a bacteremia could result in Septicemia. Thus, clinically we are concerned that these bacteremias raise the risk of:

• Infective endocarditis in predisposed patients
• Septicemia in immunosuppressed patients

For any patient who is immunosuppressed, a consult with the patient's physician is required to determine the patient's need for antibiotic prophylaxis.

To prevent infective endocarditis in predisposed patients, the American Heart Association has established guidelines for antibiotic prophylaxis. These guidelines have been recently updated, and the following information comes from the most recent revision printed in the Journal of the American Medical Association (JAMA 277 (22): 1794-1801, 1997).

Patients are categorized as:

• High risk patients for bacterial endocarditis
• Moderate risk patients for bacterial endocarditis
• Negligible risk patients for bacterial endocarditis

Patients at high risk for bacterial endocarditis

• Prosthetic cardiac valves, including bioprosthetic and homograft valves
• Previous bacterial endocarditis
• Complex cyanotic congenital heart disease (e.g., Tetralogy of Fallot)
• Surgically constructed systematic pulmonary shunts or conduits

Patients at moderate risk for bacterial endocarditis

• Acquired valvar dysfunction (e.g., rheumatic heart disease)
• Hypertrophic cardiomyopathy
• Mitral valve prolapse with valvar regurgitation and/or thickened leaflets
• Most other congenital cardiac malformations (other than those cited as high or low risk)

Patients at negligible risk for bacterial endocarditis

• Mitral Valve Prolapse without valvar regurgitation
• Rheumatic Heart Disease or Kawasaki Disease without valvar dysfunction
• Physiologic, functional or innocent heart murmurs
• Previous coronary artery bypass surgery
• Cardiac pacemakers or defibrillators
• Isolated secundum atrial septal defect
• Surgical repair of atrial septal defect, ventricular septal defect, or patent ductus arteriosus (without residua beyond 6 months)

Indications for Antibiotic Prophylaxis

Prophylaxis is recommended for patients in high and moderate risk categories. Prophylaxis is not recommended for those patients in the negligible risk category. Their risk is estimated to be no greater than that of the general population.

In the revised guideline of the AHA, Antibiotic Prophylaxis is not recommended for all dental procedures, even for patients at high and moderate risk for endocarditis.

Dental procedures for which prophylaxis is recommended for high and moderate risk patients:

• Dental extractions
• Periodontal procedures including probing, scaling and root planing, surgery and recall maintenance
• Dental implant placement and reimplantation of avulsed teeth
• Endodontic instrumentation or surgery only beyond apex
• Subgingival placement of antibiotic fibers or strips
• Initial placement of orthodontic bands (but not brackets)
• Intraligamentary local anesthetic injections
• Prophylactic cleaning of teeth or implants where bleeding is anticipated

Dental procedures for which prophylaxis is not recommended:

• Restorative dentistry (operative and prosthetic) with or without the use of retraction cord (Clinical judgment may indicate use of prophylaxis if significant bleeding is anticipated)
• Local anesthetic injections (other than intraligamentary)
• Intracanal endodontic or restorative treatments
• Placement of rubber dams
• Postoperative suture removal
• Placement of removable prosthodontic/orthodontic appliances
• Taking of oral impressions
• Fluoride treatments
• Taking of oral radiographs
• Orthodontic appliance adjustment
• Shedding of primary teeth

In adults, the new antibiotic regime recommended for the prevention of bacterial endocarditis is:

• Amoxycillin: 2.0 grams, 1 hour prior to the procedure (Four 500 mg tablets)

For those patients allergic to penicillin,

• Clindamycin: 600 mg, 1 hour to the procedure (Four 150 mg tablets)

The guidelines for Children are:

• Amoxycillin: 50 mg/kg, 1 hour prior to the procedure

  or

• Clindamycin: 20 mg/kg, 1 hour prior to the procedure, in patients allergic to penicillin.

These new guidelines involve a number of changes from the previous set of guidelines. Firstly, only one antibiotic dosage is required. Secondly, the recommended antibiotic for penicillin-allergic patients is clindamycin not erythromycin. Lastly, prophylaxis is no longer required for many dental procedures.

In July 1997, the first guidelines regarding antibiotic prophylaxis for patients with total joint replacements came out. This was published in the Journal of the American Dental Association (JADA 125: 1004-1008, 1997). Antibiotic prophylaxis is recommended for patients with total joint replacements that are considered at increased risk of hematogenous total joint infection. They are the following:

1. Joint replacement within the last two years
2. Previous history of prosthetic joint infection
3. Immunosuppressed/immunocompromised patients
   • Inflammatory arthorpathies: Rheumatoid arthritis
   • Disease-, drug- or radiation-induced immunosuppression
4. Insulin dependent diabetics; Type 1
5. Malnourished patients
6. Hemophiliacs

The suggested antibiotic regimen for prophylaxis against total joint infection is:

• Amoxycillin: 2 g orally 1 hour prior to the procedure
• For patients allergic to penicillin,
  Clindamycin: 600 mg orally 1 hour prior to the procedure

Note that this regime is identical to that of the AHA endocarditis prophylaxis. Antibiotic prophylaxis is not recommended for patients with pins, plates, and screws, or routinely for patients with total joint replacement.

It should be remembered that every time a patient is scaled and root planed a form of inoculation by a variety of organisms found in the periodontal region occurs. Increased systemic antibody titers to these organisms are well documented. The significance of this is unclear. The antibody mediated immune response typically seen in many exogenous infections has not yet been clearly demonstrated in periodontal conditions.

Therapeutic Goals of Periodontal Treatment

To determine efficacy of therapy, therapeutic goals must first be established. In periodontal therapy, our objectives are as follows:

• Suppression or elimination of pathogenic bacteria
• Establishment of a healthy root surface
• Conversion of inflamed to healthy tissues
• Reduction of periodontal pockets

Scaling and root planing is an integral part of periodontal therapy. The rationale for scaling and root planing is the following:

• Removal of calculus and "infected" root structure
• Achievement of a smooth root surface which is less prone to plaque accumulation

Although there is agreement about the need to remove calculus, removing what is referred to as infected root surface is a more controversial area. Recent data suggests that root structure removal is not necessary. The end point of scaling and root planing is however a smooth root surface as rough surfaces are more prone to plaque accumulation.

It is important to assess how difficult or easy a case is going to be. The more calculus one sees, the more work one has to do. Calculus can be seen in radiographs or detected clinically. For clinical detection, visual and tactile senses are important. Clinical signs and symptoms are also important indicators of the presence or absence of calculus and plaque.

The Efficacy of Scaling and Root Planing

• Efficacy in Calculus Removal

A study published in 1987, by Buchanan and Robertson, examined teeth (treatment planned for extraction) that were scaled and root planed for 12-15 minutes each, subsequently extracted and examined microscopically for residual calculus. Results were recorded as percentages of calculus positive teeth (CPT) and calculus positive surfaces (CPS). These were compared to similarly examined teeth that received no treatment prior to extraction. The results are tabulated in Table 2.

Even on treated teeth, a fairly high percentage of calculus was remained after scaling and root planing.

When comparing calculus removal by tooth type, tooth surface and probing depth, the results were fairly in keeping with logic (Table 3-5). These data indicate that generally calculus is harder to remove in the posterior teeth as compared to anterior teeth, or with proximal surfaces as compared to facial or lingual/palatal surfaces, and in deeper pockets as compared to more shallow pockets. An interesting point is that calculus removal by scaling and root planing was more efficient in the molar region than in the premolar region, but only slightly so.

The specific plaque hypothesis states that infection is associated with the presence or increase in levels of pathogenic organisms.

Specific microorganisms are related to periodontal diseases. They include the facultative species:

• Actinobacillus actinomycetemcomitans
• Campylobacter rectus
• Eikenella corrodens

And the anaerobic species:

• Black Pigmented Bacilli
  • Porphyromonas gingivalis
  • Prevotella intermedia
• Fusobacterium nucleatum
• Spirochetes
  • Treponemia denticola

In a study by Walsh et al, 1996 the microbiological effects of scaling and root planing were examined. The table below shows the difference in microorganism levels between sites in patients who underwent scaling and root planing and those who did not, at baseline and 3 months later. These data indicate that scaling and root planing is effective in reducing the levels of anaerobes and BPB in the subgingival flora for a sustained time period.

In relation to the effects of scaling and root planing on bacterial morphotypes, we see from the table below, that the levels of cocci and non-motile rods increased from baseline to 3 months in the scaling and root planing group. This is a desirable effect, as is the decrease in numbers of motile rods and spirochetes. In the no-treatment group, the levels remained fairly constant.

In a study of a large group of patients, published in 1986, Slots correlated percentage recovery of microorganisms at a large number of sites with disease activity at those sites. As can be seen in the table below, greater levels of Aa., P. gingivalis and spirochetes correlated positively with increased loss of attachment.

The study by Walsh et al (1986) also examined how scaling and root planing affected clinical parameters as opposed to no therapy. The parameters examined included plaque index, bleeding index, probing depth and attachment loss. From the tables shown here it is clear that scaling and root planing had a very positive effect.

The endpoint of clinical therapy is the elimination of inflammation. To achieve this, open debridement may be required in addition to scaling and root planing, and treatment may be aided by chemotherapeutic agents.

In conclusion, scaling and root planing results in systemic effects (including bacteremia) and local effects which include decreases in the levels of calculus, pathogenic microorganisms and clinical inflammation. Additional therapy may be required to achieve clinical health.

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