This study will investigate the clinical performance of a novel restorative glass ionomer (DeltaFil, DMG) in comparison to an established restorative glass ionomer (Riva Self Cure HV, SDI) in the restoration of Class II cavities in primary molars.

Dental caries (tooth decay) remains one of the most prevalent diseases worldwide. It is a dynamic and continuous process that, if uncontrolled, eventually leads to cavitation and the need for restorative treatment to maintain the form and function of the tooth.Today there are many possibilities for direct restorations, e.g. resin composites, compomers, resin-modified glass ionomer cements (RMGICs) and glass ionomer cements (GICs), which all offer their own advantages and disadvantages.

GIC are particularly suitable for treatments in young patients due to their high biocompatibility, fluoride release, less moisture and technique sensitivity as well as compatibility with Atraumatic restorative treatment (ART) treatment. However, these materials have lower mechanical properties compared to other restorative materials, which negatively affects the survival rate when placed in load bearing areas. Fracture, loss and wear being the most common causes for failure.

This randomized, controlled non-inferiority trial aims to evaluate the performance of the new restorative glass ionomer DeltaFil, that offers an increased fracture toughness, in comparison to an established restorative glass-ionomer (Riva Self Cure HV).

Inclusion Criteria:

• At least 1 and up to 3 primary molars with either International Caries Detection and Assessment System (ICDAS) lesions stage 2-5 or preexisting restorations requiring placement/replacement of Class II restorations
• Defects limited to occlusal-proximal surface, with cavity sizes smaller than 3 mm mesio-distally and 3 mm in the occluso-cervical and bucco-lingual directions measured with a World Health Organization (WHO)-graded periodontal probe
• Teeth should have both adjoining and their antagonist teeth present. After restoration the restored tooth should enable appropriate proximal contacts on both mesial and distal surfaces after setting of the class II restoration and be in occlusion with the antagonist tooth
• Good access
• Good general health (ASA I, II)
• Good oral hygiene (OHI-S < 1.9)
• Guardians have given informed consent
• Child is cooperative and assented

Exclusion Criteria:

• Known allergy/ sensitivity to GIC or other materials used in this study
• Space maintainers or orthodontic appliances
• Tooth has a caries lesion or restoration other than those included in the study
• Tooth has pathological mobility
• Tooth has preexisting developmental defects
• Tooth with pulp exposure or indication for endodontic treatment
• Pain, fistula or abscess related to the selected tooth
• Obvious signs of parafunctional habits (e.g. bruxism)
• Participation in another study
• Incapable to participate in the recall visits at the university hospital