Bacteraemia Secondary to Tooth Extraction: Chlorhexidine Prophylaxis Protocols

The study group will be formed of patients undergoing tooth extraction under local anaesthesia in the Department of Stomatology and Maxillofacial Surgery of the Santo Antonio General Hospital (Oporto, Portugal).The following exclusion criteria will be applied: patients under 18 years of age; antibiotic treatment in the previous three months; routine use of oral antiseptics; and any type of congenital or acquired immunodeficiency or other disease that can favour the onset of infection or haemorrhagic complications. Applying these criteria and after a statistic power test, the sample will be 208 patients. The select patients will be attributed randomly a number of participation and they will be distributed into four groups:

• Control Group: 52 patients who will use no prophylactic chlorhexidine (CHX) regimen.
• CHX mouthwash group (CHX-MW group): 52 patients who will perform a mouthwash with 0.2% CHX (10 ml for 1 minute, BSAC recommendations) (Oraldine Perio®, Johnson and Johnson, Barcelona, Spain) before the tooth extraction.
• CHX mouthwash/subgingival irrigation group (CHX-MW/SUB_IR group): 52 patients who will perform a mouthwash with 0.2% CHX (10 ml for 1 minute) (Oraldine Perio®) and who then will undergo subgingival irrigation with 1% CHX on the tooth to be extracted; the irrigation will be done with the Heraeus Citojet Intraligamental Syringe (CIS) (Kulzer Heraeus S.A., Madrid, Spain) at six points on each tooth (3 points on the vestibular surface and 3 on the palatine surface).
• CHX mouthwash/supragingival irrigation group (CHX-MW/SUPRA_IR group): 52 patients who will perform a mouthwash with 0.2% CHX (10 ml for 1 minute) (Oraldine Perio®) and who then will undergo supragingival irrigation with 1% CHX on the tooth to be extracted; the irrigation will be done continuously around the tooth to be extracted by a conventional syringe.

The mouthwash and subgingival or supragingival irrigation will be performed before injection of the local anaesthetic.

After recording the sex and age of each patient, a single dentist will perform an intraoral examination 2 days before the intervention, collecting the following information: plaque deposits (simplified Greene and Vermillion oral hygiene index) , calculus deposits (Ramfjord calculus index), presence of gingival bleeding (Löe and Silness gingival index), depth of periodontal pockets (Ramfjord index), degree of tooth mobility (Ramfjord tooth mobility index), number of caries (including root remnants), and presence of submucosal abscesses, fistulae and periapical foci detected clinically and/or radiologically. Each patient will be assigned an overall oral health status using a scale designed by the authors and published previously; the scale incorporates dental and periodontal health criteria.

Local anaesthesia will be administered to all patients using conventional techniques (regional block and/or infiltration). The anaesthetic will be lidocaine plus adrenaline (1:100,000) and not more than 2 cartridges in any patient.

The prevalence of baseline bacteraemia will be determined by collection of a peripheral venous blood sample (10 ml) from each patient before performing any manipulation. The prevalence of bacteraemia secondary to a mouthwash and subgingival or supragingival irrigation will be determined by the collection of a peripheral blood sample (10 ml) 30 seconds after each of these actions. Further samples (10 ml) will be drawn 30 seconds and 15 minutes after completion of the tooth extraction in order to determine the prevalence and duration of post-extraction bacteraemia.

Intravenous access will established using an 18-22 gauge "angiocath" catheter (Becton Dickinson, Sparks, MD, USA) inserted in the antecubital fossa or dorsum of the hand after disinfection of the area with alcohol and povidone iodine. The catheter will be flushed with 3 ml of saline after each extraction and the first 2 ml of blood was discarded. Equal volumes of each sample will be inoculated into two bottles containing aerobic and anaerobic culture media (Bactec Plus, Becton Dickinson), and the bottles will be immediately transferred to the laboratory. The whole process of manipulation and transport of the samples will be performed in accordance with the recommendations of the Spanish Society of Infectious Diseases and Clinical Microbiology.

The blood culture bottles into which the blood samples will be injected and processed in the Bactec 9240 (Becton Dickinson). Gram stain will be performed on all positive cultures. The positive aerobic blood cultures will be subcultured on blood agar and chocolate agar in an atmosphere with 5%-10% CO2, and on MacConkey agar under aerobic conditions. The same protocol will be used for the positive anaerobic blood cultures but include subculture on Schaedler agar and incubation under anaerobic conditions. The bacteria isolated will be identified using the battery of biochemical tests provided by the Vitek system (bioMérieux Inc., Hazelwood, Missouri, USA) for gram-positive bacteria, Neisseria spp./Haemophilus spp. and obligate anaerobic bacteria. Applying the Ruoff criteria, Streptococcus viridans will be classified into five groups: mutans, salivarius, bovis, anginosus and mitis.