The Effect of Photodynamic Therapy on Plaque in Orthodontic Patients

This randomized controlled trial will be conducted on 40 orthodontic patients at the Department of Orthodontics, University Hospital Centre Zagreb, Croatia. Respondents will be randomly allocated into 4 groups (n=10). The first group will receive photodynamic therapy, the second tricalcium phosphate varnish with 5% NaF (sodium fluoride), the third 1% chlorhexidine varnish, while the fourth group will be the negative control. Before and after the mentioned interventions, the participants will have the amount of plaque measured using the plaque index and the bacteriological composition of the plaque assessed using the mass spectrometry and PCR. The gingival condition will be assessed using the gingival index. Also, the occurrence of white spot lesions will be evaluated on intraoral photographs.

Goals of this research are: 1. To compare the plaque index in orthodontic patients treated with different antibacterial agents (photodynamic therapy, tricalcium phosphate varnish with 5% NaF, chlorhexidine varnish) before insertion of a fixed orthodontic appliance (T0), 6 weeks (T1), 12 weeks (T2) and 18 weeks later (T3); 2. To compare the bacteriological composition of supragingival plaque using the mass spectrometry in orthodontic patients treated with different antibacterial agents before insertion of a fixed orthodontic appliance (T0), 6 weeks (T1), 12 weeks (T2) and 18 weeks later (T3); 3. To compare the bacteriological composition of subgingival plaque using polymerase chain reaction in orthodontic patients treated with different antibacterial agents before insertion of a fixed orthodontic appliance (T0) and 18 weeks later (T3); 4. To compare the gingival index in orthodontic patients treated with different antibacterial agents before insertion of a fixed orthodontic appliance (T0), 6 weeks (T1), 12 weeks (T2) and 18 weeks later (T3); 5. To compare the occurrence of white spot lesions in orthodontic patients treated with different antibacterial agents before insertion of a fixed orthodontic appliance (T0) and 18 weeks later (T3).

This study hypothesizes that photodynamic therapy is just as effective in reducing plaque accumulation, reducing bacteria in supragingival and subgingival plaque, preventing gingival inflammation and preventing initial carious lesions (white spot lesions) in orthodontic patients as tricalcium phosphate varnish with 5% NaF and 1% chlorhexidine varnish.

Participants (40 orthodontic patients at the Department of Orthodontics, University Hospital Centre Zagreb, Croatia) will be randomly assigned to one of four groups. Randomization will be performed before the recruitment using software for randomization (Research Randomizer; permuted blocks randomization). Outcome assessor will be blinded, while participants and care providers will be aware of the group allocation.

Group of participants (n=10) allocated to the first group will receive photodynamic therapy which consists of toluidine blue based dye (155 mg/mL) and 660 nm diode laser. Participants (n=10) allocated to the second group will receive tricalcium varnish with 5% NaF which will be applied according to the manufacturer's recommendations. Group of participants (n=10) allocated to the third group will receive chlorhexidine varnish which will be applied according to the manufacturer's recommendations. All interventions will be performed right after the placement of a fixed orthodontic appliance (T0), 6 weeks (T1) and 12 weeks (T2) later. The fourth group (n=10) will be the negative control which means that participants will not receive any intervention.

Primary outcome measures: assessment of dental plaque accumulation using plaque index and assessment of the bacteriological composition of supragingival plaque using mass spectrometry. Secondary outcome measures: assessment of the bacteriological composition of subgingival plaque using the polymerase chain reaction, assessment of gingival condition using the gingival index and diagnosis of white spot lesions on intraoral photographs.

Eligibility Criteria:
Inclusion Criteria:

* 12 to 17 years of age
* indication for fixed orthodontic treatment without the need for extraction
* permanent dentition (including second molars)
* absence of oral lesions, caries, pulpal and periapical diseases and gingival and periodontal diseases

Exclusion Criteria:

* previous orthodontic treatment
* taking antibiotics and anti-inflammatory drugs 3 months before the study and during the study
* use of antiseptic rinses 3 months before the study and during the study
* taking corticosteroids and immunosuppressive drugs
* smoking
* systemic conditions that can affect the inflammatory response of soft tissues and the possibility of maintaining adequate plaque control (diabetes, immune disorders, etc.)