The study is a randomized controlled trial aiming to compare the effectiveness of Silver modified atraumatic restorative technique and (SMART) and conventional atraumatic restorative technique (ART) regarding their caries arresting properties in primary molars, patient acceptance and cost effectiveness.

5-9 years old school children will be recruited for the study. Parents of eligible children will be informed in full details about the purpose of the study and any possible side effects. Prior to enrollment of children in the study, parents will have to sign a written informed consent outlined by the Ethical Committee, Faculty of Dentistry, Ain Shams University. Children will be also informed about the nature of the study using age appropriate language and will have to give an assent to participate before being enrolled in the study.

Children will be clinically examined with the help of a plane dental mirror and an explorer. A single calibrated investigator will undertake all clinical examinations and deliver dental treatment to all patients to ensure standardization. After clinical examination, all children included in the study will be randomly allocated to be one of the two groups either control group (Conventional ART) or experimental group (SMART). Randomization sequence will be electronically generated using (http://randomization.com/). To ensure concealment of allocation, the randomly generated sequence will be concealed and enclosed in sealed, opaque envelopes. The envelopes will be randomly picked up by the children for group allocation. Follow up examinations will be done by a calibrated examiner who was not involved in the treatment procedures. Patients who are no longer willing to continue in the study will have the right to quit at any time without any penalty. All patient information will be collected and recorded in the patient examination chart. All information will be kept as a hard copy and as an electronic copy as well. Patient information will be confidential information that should never be exposed at any point. The data concerning the subjects will be entered into the database with a numerical code only for the purpose of confidentiality.

All data will be tabulated, summarized and statistically analyzed. Data will be statistically described in terms of mean, standard deviation, median and range, or frequencies (number of cases) and percentages when appropriate.

Comparison of numerical variables between the study groups will be done using Student t test for independent samples in comparing normally distributed data and Mann Whitney U test for independent samples when data is not normally distributed. For comparing categorical data, Chi-square test will be performed. Exact test will be used instead when the expected frequency is less than 5.Correlation between various variables will be done using Pearson moment correlation equation for linear relation in normally distributed variables and Spearman rank correlation equation for non-normal variables.

A probability value (p value) less than 0.05 is considered statistically significant. All statistical calculations will be done using computer programs Microsoft Excel 2007 (Microsoft Corporation, NY, USA) and IBM SPSS (Statistical Package for the Social Science; IBM Corp, Armonk, NY, USA) release 22 for Microsoft Windows.

Inclusion Criteria:

1. Medically free children.
2. Clinical examination revealing at least one second primary molar with single surface active dentine carious lesions.
3. Children who agreed to participate and whose parents signed an informed consent.
4. Cooperative or potentially cooperative children according to Wright Classification

Exclusion Criteria:

1. Children who have known allergies to silver products.
2. Children with special health care needs or any medical conditions.
3. Children with designated molars having more than one third of their crown missing.
4. Children with designated molars showing signs of pulpal pathology such as spontaneous pain, presence of an abscess or sinus or mobility.
5. Children with designated molars having an existing restoration.
6. Children with designated molars having deep carious lesions with close proximity to the pulp.