2.1 Study setting
The study setting of this research includes the Department of Paediatric Dentistry and the Laser Centre of the Faculty of Dental medicine, Medical University – Plovdiv, Bulgaria.
2.2 Eligibility
2.2.1 Inclusion criteria
- Participants in the study are children ages 12 and older, in good general health;
- Children, requiring fixed orthodontic treatment (brackets);
- Children at high caries risk according to `Oral disease risk assessment tool` accepted and used in the Department of Paediatric Dentistry, Faculty of Dental medicine, Medical University – Plovdiv, Bulgaria (see supplementary data file S1 `Appendix for risk assessment of oral diseases`);
- Children with untreated non-carious vestibular surfaces of the six maxillary anterior teeth of the permanent dentition (central and lateral incisors, canines) with ICDAS code 0 22,23,24
- Verbal assent from the child willing to comply with all study procedures and protocol;
- Obtained written informed consent by the patient`s parent/guardian for participation in the study (see supplementary data file S2 `Patient consent form` and S3 `Information leaflet`).
2.2.2 Exclusion criteria
- Children with systemic diseases that may affect oral health or oral microflora (such as diabetes, etc.);
- Children with medication intake that could affect the salivary flow or oral microflora (such as antibiotics, etc.);
- Children with mental or cognitive problems;
- Patients with maxillary anterior permanent teeth affected by disturbances in the development of dental structures (hypoplasia, hypomineralization, fluorosis).
2.2.3 Interventions
A low-speed rubber cup and pumice paste (CleanPolish, Kerr) will be used for 30 seconds for cleaning and polishing of the maxillary anterior teeth and then they will be washed for debris and organic residue removal. A baseline visual inspection using ICDAS criteria of the vestibular surfaces of the investigated teeth as well as white and blue light digital photographs using the device SoproLife ® (Sopro-Acteon group, La Ciotat, France) will be made.
Topical fluoride application protocol (according to the instructions for use of the manufacturer):
- following the instructions of the dosing guide, the required amount of the varnish (Clinpro™ White Varnish 5% Sodium Fluoride, 3M ESPE, USA) is determined - 0.5ml.
- isolation
- opening of the unit-dose package of the varnish and dispensation of the entire content onto the round dosing guide on the back of the foil pouch follows
- since components of all sodium fluoride varnishes can separate during storage, thoroughly mixing with the applicator brush is required
- application of the varnish evenly in a thin layer over the whole vestibular surfaces of all anterior maxillary teeth with sweeping, horizontal brush strokes. No suction is required.
Laser irradiation protocol:
The vestibular surfaces of the left maxillary anterior teeth will be exposed to CO2-laser (Ultra Dream Pulse, DS_40U, Daeshin Enterprise, Seoul, South Korea), emission wavelength 10,600 nm. The parameter settings used will be:
Time on—100 μs, time off—40 ms;
Average power—0.73 W; peak power—292.73 W
Speed of movement—2 mm/s;
Energy density with movements—5 J/cm2;
Tip-to-tissue distance—20 mm; tip diameter 700 μm;
Irradiation time—30 s.
The measured values were confirmed using a power meter. The chosen protocol parameters are modified in a previously conducted study.5
Placebo protocol:
The vestibular surfaces of the right maxillary anterior teeth are exposed to sham light (as a placebo light). No pulse energy will be applied.
Bonding brackets protocol includes the following steps:
- isolation
- tooth surfaces will be etched with 35% phosphoric acid gel (Etching gel, DMP Ltd) for 30 seconds and rinsed for the same time
- reisolation
- tooth surfaces will be dried with air spray for 15s
- an adhesive bonding agent (AdperTM single bond, 3M ESPE, USA) will be applied on the enamel surfaces according to the manufacturer’s instruction, and then will be cured for 20s
- Fluoride-free Transbond XT resin composite (3M Unitek, USA) will be applied, and stainless steel brackets with a slot size of 22 (3M Unitek, USA) will be placed while excess composite will be removed. Resin composites will be cured for 20s from occlusal, gingival, mesial, and distal directions.
The patient will be recalled 6 and 12 months post-irradiation. A visual inspection and reapplication of the fluoride varnish will be conducted by the same operator. During the evaluation, the teeth will be thoroughly cleaned with a rubber cup and pumice and then washed. After drying, the vestibular surfaces will be visually evaluated using ICDAS and SoproLife ® daylight and blue fluorescence, followed by topical fluoride application.
2.2.4 Clinical protocol
First visit:
- Parents/guardians are informed about the protocol of the study and the laser technique. They sign the informed consent form (see Supplementary data file S2 `Patient consent form`). Verbal assent from the child is obtained.
- The teeth are cleaned and polished with a rubber cup and pumice paste.
- A visual inspection of the vestibular surfaces of the investigated teeth and SoproLife ® Daylight and SoproLife ® Blue fluorescence digital images are made and recorded.
- Application of fluoride varnish Clinpro™ White Varnish 5% Sodium Fluoride over the whole vestibular surfaces of all anterior maxillary teeth
- The chosen method, CO2 laser irradiation or placebo, is applied.
- Follows direct adhesive bonding of orthodontic brackets
Second visit:
- The teeth are cleaned and polished with a rubber cup and pumice paste.
- The incidence, extent, and severity of the lesions are assessed using ICDAS criteria and SoproLife ® daylight and blue fluorescence. The data are recorded and digital photographs are made.
- Reapplication of the fluoride varnish Clinpro™ White Varnish 5% Sodium Fluoride
Third visit:
- The teeth are cleaned and polished with a rubber cup and pumice paste.
- The incidence, extent, and severity of the lesions are assessed using ICDAS criteria and SoproLife ® daylight and blue fluorescence. The data are recorded and digital photographs are made.
- Reapplication of the fluoride varnish Clinpro™ White Varnish 5% Sodium Fluoride
2.3 Outcomes
2.3.1 Primary outcome measures
The primary outcome measures are the number of newly appeared caries lesions and the changes into ICDAS scores in the experimental and control teeth (within one patient) from baseline to 12 months. The International Caries and Detection System (ICDAS) is a visual scoring system developed for use in clinical assessment and clinical research of caries development and progression. It uses a numbered scoring system with a range from 0 to 6, to grade enamel demineralization and cavitation. Code of `0` represents unaffected/sound enamel, no caries change, `1` - first visual change, represents initial demineralization that is visible only after air drying, `2` represents a distinct visual change in the enamel that is visible when the surface is wet, `3` represents localized enamel loss or breakdown, no visible dentin or underlying shadow, and `4-6` represent larger carious lesions in dentin. Time Frame: 1 year
2.3.2 Secondary outcome measures
The secondary outcome measures are changes in SoproLife ® scores in the experimental and control teeth (within one patient) from baseline to 12 months. The SOPROlife score is a visual assessment of the caries levels. The SoproLife ® daylight intraoral camera (SoproLife ® Daylight mode) is used to record an intraoral picture with Sopro-imaging software (Acteon, Sopro, La Ciotat, France). The SoproLife ® blue fluorescence mode scores range from 0 to 5. Code of `0` is given when the surface appears shiny green, the enamel appears sound, and there are no visible changes, code `1` - a tiny, thin red shimmer is observed, no red dots appeared, code `2` - darker red spots are visible, code `3` - dark red spots have extended, a slight beginning roughness of the red areas can be visible, and codes `4-6` represent larger carious lesions in dentin. Time Frame: 1 year
2.3.3 Participant`s timeline
Each eligible patient undergoes three visits. The first appointment includes screening, consenting and assenting, recording of initial values, topical fluoride application, and treatment with the selected specific parameters of CO2-laser of the left maxillary anterior teeth and Placebo procedure for the right, contralateral teeth, and orthodontic treatment at the end of the visit. The second appointment at the 6-month recall includes an oral examination, cleaning of the investigated surfaces, collection of data values, reapplication of the fluoride varnish. The third appointment at the 12-month recall includes an oral examination, cleaning of the investigated surfaces, collection of data values, reapplication of the fluoride varnish.
2.3.4 Sample size calculation
The sample size calculation is based on our primary outcome endpoint of changes in ICDAS score on the vestibular surfaces of the anterior maxillary teeth in the left and the right quadrants per subject, by comparing the proportion of teeth with worsening ICDAS score in experimental in comparison to the control group. To determine the sample size for each group, a priori power analysis was conducted as follows:
p1: 8.7% of the lesion incidence in the control group
p2: 3.6% of the lesion incidence in the laser group
The data for this power analysis were obtained from a previous study.9 The significance level was considered as 95% and power was 80%. By inserting the minimum values in the above formula, the sample size was calculated as 241 teeth (121 teeth per group, i.e. a total number of 41 patients).
2.4 Recruitment
The patients at the Department of Paediatric Dentistry of the Faculty of Dental Medicine, Medical University – Plovdiv, Bulgaria, who meet the inclusion criteria, will be screened for eligibility. Once identified, patients will be informed about this research project and will receive information about the possibility of potential study participation. Patient recruitment starts obtaining the full quota of participants within a one-year time frame. It begins in September 2021 with an estimated enrollment capacity of 4 patients per month.
2.5 Participating centers
The patients are randomly selected from the visitors in the Department of Paediatric Dentistry of the Faculty of Dental Medicine, Medical University – Plovdiv, Bulgaria, and treated in the Laser Centre of the same university.
2.6 Assignment of the intervention
2.6.1 Sequence generation
A randomization sequence for the allocation of the quadrants will be created using a computerized random generator. The study is a split-mouth randomized control study and each patient will receive both procedures during the first visit. The patient will be randomized to receive first the laser irradiation and second the placebo procedure or first the placebo procedure and second the laser irradiation before the bonding of the brackets.
2.6.2 Allocation concealment mechanism and implementation
The sequence of the application of the two protocols – laser and placebo, is randomly assigned. A randomization list will be created by a random generator and kept in a locked drawer. Assignments will be kept in separate, closed opaque, sequentially numbered envelopes, enabling the sequence to be concealed until the intervention is assigned.
2.6.3 Blinding
Due to the nature of the intervention, the operator and the dental assistant will not be blinded to subjects’ group assignments as they are participating in the treatment. The patient will be also not blind to the treatment. The dental assistant will inform the doctor which protocol will be the first to start with and which will be the second protocol. The statistician will be blinded to treatment assignment as data will be masked before the analysis by labeling the 2 quadrants as 0 and 1, without giving the statistician the key.
2.6.4 Data collection, confidentiality, storage, and monitoring of the study documents
Collection, coding, storage, and evaluation of personal data within the project will be carried out in accordance with The General Data Protection Regulation (EU) 2016/679 (GDPR). A prerequisite for data collection will be the voluntary written informed consent of the patient`s parent or guardian. Confidentiality will be guaranteed by a coded ID number, access will be granted exclusively to the study investigators. The information from the paper forms will be exported to a database file and stored on a password-protected computer. Only the investigators and the statistician will have access to the final data set. All data collected will be stored in sealed containers in areas of the Department of Paediatric Dentistry, Faculty of Dental Medicine, Medical University – Plovdiv, Bulgaria with limited access.