The problem of root caries has been increasing in last decades as the an average life expectancy is rising. Due to progress of medicine and dentistry humans also maintain natural dentition longer.

The aim of the study is to determine the effectiveness of photoactivated disinfection / photodynamic therapy / photodynamic antimicrobial therapy in elimination of cariogenic bacteria after manual root caries removal.

If proved to be effective in eliminating bacteria from prepared cavity PAD could be incorporated in the protocol of treatment of root cavities.

Elimination of cariogenic bacteria is to be determined in this study - Mutans streptococci, Lactobacillus spp. and Actinomyces spp.

After manual preparation of the cavity with an excavator and taking a sample for a microbial analysis with a rose bur on micro motor (size 014) the cavity undergoes the procedure of photodynamic disinfection:

• application of photosensitizer 'Fotosan Agent' (CMS Dental, Denmark) for 5 minutes,
• radiation with low power laser, wavelength 635 nm power 200mW 120 s. ('Lasotronix', DiodeLX model SMART)
• rinsing with water and drying

After photodynamic disinfection another sample for microbial analysis is taken form the neighboring area to get the material for a comparison analysis.

Filling the cavity with a material for permanent fillings (glass-ionomer cement)

Samples are inoculated on:

• Mitis-Salivarius ('Difco') for Streptococci
• Rogosa SL 2% aqar ('Oxoid') for Lactobacillus
• Columbia with blood for Actinomyces (2 dilutions - 1:10 and 1:100)

Inclusion Criteria:

• more than 10 teeth
• at least one tooth with primary caries lesion with contraindicated non-invasive treatment (lesion which needs to be prepared and filled with material for permanent fillings); tooth with no clinical and/or radiological symptoms of pulp involvement.
• no systemic disease

Exclusion Criteria:

• systemic diseases (may affect saliva flow and properties)
• antibiotic therapy in previous 3 months before the appointment