Purpose: To assess the clinical effectiveness of silver diamine fluoride (SDF) to control asymptomatic cavitated carious lesions compared to conventional glass ionomer restoration in preschool children.

1. Introduction The global spread of COVID-19 has led to drastic modifications affecting different fields including the field of Pediatric Dentistry. The last emergent guidelines of dental caries management under and following the current pandemic status, specifically recommended minimization of Aerosol Generating Procedures (AGP) and shifting to non- and minimally invasive biological approaches for dental caries management like the use of Silver Diamine Fluoride (SDF).

   In addition, convincing young children to cooperate during conventional restorative dental procedures could be stressful and usually challenging, where the dentist might be compelled to use advanced behavior management techniques such as sedation or general anesthesia.

   The application of SDF focused on arresting and preventing dental caries progression, particularly in children. A high success rate was reported following SDF treatment in arresting dental caries progression. SDF treatment is also considered of low-cost, easy application technique, does not require extensive caries removal, and thus omits the need for local anesthesia administration.

   The SDF clinical effectiveness is obtained through a series of chemical reactions that promote carious lesion arrest. Silver ions possess a bactericidal effect via the inhibition of bacterial cell wall synthesis and DNA synthesis resulting in the disruption of plaque biofilm formation. Both silver and fluoride ions in SDF synergistically enhance remineralization of affected tooth structure and formation of fluorapatite, silver phosphate, and calcium fluoride compounds; hence termed "Silver-fluoride pullet" to arrest dental caries. The formed precipitate not only causes occlusion of the dentinal tubules but also reduces collagen degradation following caries affection. Furthermore, the sustained bactericidal effect of SDF arises from the ability of silver-affected bacteria to kill living bacteria of the same species as they come into contact which is known as the "Zombie phenomenon".

   However, SDF treatment has the side effect of staining everted carious lesions permanently black as a result of the precipitation of silver protein and silver phosphate complexes which could represent a barrier to its application. However, most parents compromise esthetics when their children are subjected to an invasive approach to dental caries management particularly under general anesthesia.

   The use of conventional glass ionomer dental restorations has been frequently used to restore known to have a potent ability to release fluoride which aids in enhancing the remineralization of dental caries and further reduction in the development of new carious lesions. In addition, it is provided in various shades making it a more esthetically appealing dental restoration. However, its application technique necessitates a degree of compliance that could be challenging in young children.

   Thereby, this study will focus on the assessment of the clinical effectiveness of SDF treatment on cavitated carious lesions in preschool children compared to conventional glass ionomer restoration.

2. Materials and methods

2.1. Study design This clinical study will be conducted on a convenient sample of pre-school children attending the Pediatric Dental Clinics, at the College of Dentistry, Umm AlQura University, seeking oral and dental care. Children and their guardians will receive a comprehensive explanation of the dental procedure and expected complications, in addition to the declaration of possible treatment alternatives. A voluntary approval of written consent is required for child participation in this study.

2.2. Sample size calculation The estimation of the sample size relays on that SDF treatment can arrest caries at a rate of 80 percent, with a 10 percent difference to reach clinical significance, at statistical power of 80 percent and the statistical significance level equals 5 percent (α =0.05). Using ClinCalc.com (https://clincalc.com/Stats/SampleSize.aspx), the results showed that 199 carious surfaces per test group will be required. Considering the 10 percent dropout rate at the reassessment time, a minimum of 220 carious teeth surfaces per group will be needed for this study. The average caries tooth surface in children is estimated to be about four surfaces, thus, 60 participants per group will be included in this study.

2.3. Participants' grouping Participants will be randomly assigned using closed envelops distributed by the clinic receptionist, into one of the following groups; Group A: who will receive SDF treatment at the baseline and at Week 24. Group B: who will receive conventional glass ionomer restoration following manufacturer instructions.

2.4. Study procedures Parents will be asked to complete a questionnaire to assess family sociodemographic characteristics. The participants will receive a simple explanation regarding the dental application of SDF, indications, merits, demerits, and barriers to conventional restorative dental treatment as a child crying, screaming, or kicking. Standard sets of high-quality colored pictures that displayed cases of primary and permanent teeth, before and after treatment using SDF for comparison, will be shown to the participants and their parents.

All participants will receive a thorough clinical examination using a disposable dental mirror and ball-end community periodontal index probe. The following will be assessed at the first visit (base record) and at the end of six months (follow-up record):

1. Dental caries experience: using dmfs index (decayed, missing due to caries and filled deciduous tooth surfaces) and the caries lesion extent (ICDAS codes from 3- to 5).
2. Caries activity: arrested or active.
3. Caries risk susceptibility using CariScreen meter.
4. Plaque and gingival indexes will also be scored to assess oral hygiene status.
5. Stimulated saliva will be collected to estimate salivary flow rate and saliva pH.

At the end of the first visit, each participant will receive strict instructions toward guided oral hygiene practice using a dental model.

2.5. Statistical analysis Continuous variables will be summarized with means and standard deviations, and categorical variables will be summarized with counts and percentages.

All data will be analyzed using the SPSS (version 16.0) software package (SPSS Inc., Chicago IL, USA). The significance level will be tested at 0.05.

Inclusion Criteria:

• Healthy children without a history of serious systemic conditions necessitating chronic use of medications.

  • Children whose dental examination reveals at least one untreated asymptomatic cavitated carious lesion (ICDAS index: code 3-5) affecting primary molars.
  • Absence of former history of spontaneous pain from the offending tooth/teeth.
  • Teeth with normal vital pulp response when assessed using sensibility test and absence of any signs of irreversible pulpitis or necrotic pulp degeneration.
  • Absence of abnormal grade of tooth mobility, swelling, or tenderness on palpation or percussion.
  • Absence of any evidence of peri-radicular pathosis, or internal- or external resorption on radiographic examination.

Exclusion Criteria:

• Patients with proven allergy to silver compounds or any component of dental materials to be applied.
• Patients or guardians who refuse to participate in the study or had poor acceptance of SDF treatment.
• Patients with ulcerative gingivitis or stomatitis.