The aim of the study is to clinically evaluate the performance of S-PRG based & Alkasite based resin composite restorations versus conventional resin composite restorations after caries control in Class I carious cavities in posterior molar teeth over 1 year follow up.

Traditionally, less conservative methods have been employed to treat tooth decay, which implied more loss of healthy dental tissue in order to increase the mechanical retention of the restorative material. Minimally invasive treatments have been proposed as an alternative therapy, which has evolved in with the development of new biomaterials.Bioactive restorative materials, as advocated by the FDI World Dental Federation, can promote mineralization/hard tissue creation, bacterial infection control, inflammation prevention, and tissue regeneration. In simpler terms : One efficient way to achieve bioactive functionalities in dental materials is to use particles that have the ability to release particular component.The development of "Giomer" based resin composites, which have the added benefit of prolonged fluoride and other ions release as well as rechargeability, is one of the key technological advances in resin composites to promote its usage as a bioactive material.In fact, Giomers with S-PRG fillers can release more fluoride than that of other fluoride-releasing restorations.Acid neutralization capacity by S-PRG fillers, one of many bioactive functions, is in which the pH of the surrounding environment became slightly alkaline upon contact with water or acidic solutions, exhibiting a modulation impact on acidic circumstances. Owing to the release of multiple ions, such modulation effect might be brought about by the release of Sr, B, Na, and F ions clarifying an acid buffering mechanism.A modification of GIC is Cention-N, which was introduced as a new resin-based material containing alkacid fillers, such as fluoride, calcium, and hydroxide ions, to neutralize acids. Owing to being tooth-colored, inexpensive, and having good flexural strength, It's considered as a subcategory of the composite material class.With properties similar to those of GICs and RBCs, Cention-N releases calcium, hydroxyl, and fluoride ions to prevent tooth demineralization. The presence of hydroxide ions on the material's surface may be crucial in neutralizing the acids that were produced by cariogenic bacteria Additionally, the filler's release of calcium and fluoride ions contributes in remineralization process.In Conclusion; S-PRG & Alkasite based composite restorative materials are able to release ions that contribute to tooth mineralization as well as have a modulation effect on the acidic conditions produced by oral cariogenic microorganisms.

Inclusion Criteria:

• Patient inclusion:

  1. Adult Patients (Male or Females) aging ≥21-50 years.
  2. Patients with high level of caries risk.
  3. Patients with good likelihood of recall availability.

Tooth inclusion:

1- Permanent posterior molar teeth with primary simple occlusal Class I carious lesions (ICDAS 3 or 4 scores) 3- 2- Vital, periodontally sound and with positive reaction to cold stimulus. 4- 3-Well-formed and fully erupted in normal functional occlusion with natural antagonist and adjacent teeth

Exclusion Criteria:

- Participants with general/systemic illness. 2- Pregnant or lactating females. 3- Concomitant participation in another research study. 4- Inability to comply with study procedures. 5- Heavy bruxism habits. 6- Last experience with allergic reactions against any components of the used materials.

7- Patients receiving orthodontic treatment.

Tooth exclusion:

1. Teeth with clinical symptoms of pulpitis such as spontaneous pain or sensitivity to pressure.
2. Non-vital teeth, Fractured or cracked teeth.
3. Secondary carious lesions.
4. Hypocalcified or hypoplastic teeth.