Impressions will be taken from the patients with sterilized plastic pedodontic impression trays and alginate under standard conditions by the same researcher. Alginate will be mixed in accordance with the manufacturer's instructions. After the impressions, plaster study casts will be produced and sent to the laboratory. Conventional SMs will be produced by soldering the 0.7-mm bent orthodonic wires (Dentaurum, Germany) onto previously selected prefabricated molar bands. Prefabricated molar bands (Dentaurum, Germany) in the patient's mouth will be chosen by the physician and then sent to the laboratory with the casts.

All SMs will be cemented by the same investigator under standard conditions using a glass-ionomer luting cement (Nova Glass-L, Imicryl, Konya, Turkey).

Patients in this group will be scanned under standard conditions with Medit i500 (Medit Corp. Seoul, South Korea). The scanned data of the patients will be sent to the laboratory via email in Standard Triangle Language (STL) file format.The design of SMs will be carried out on the DentalCAD 2.2 Valletta (Exocad GmbH, Darmstadt, Germany) program to mimic the conventional space maintainer, and the production will be made by the 3D Selective laser melting (SLM Solutions, Germany) method using titanium-based metal powder (Ti64 Gd23; LPW Technology Ltd., Cheshire, UK). The production of 3D-SMs will start in accordance with the C-SM design in many points, such as the fit of the part surrounding the abutment tooth, thickness, and the position of the loop of 3D-SM.

All SMs will be cemented by the same investigator under standard conditions using a glass-ionomer luting cement (Nova Glass-L, Imicryl, Konya, Turkey).

Digitally fabricated #d printed space maintainer

Decementation, debonding, solder breakage, loop breakage, band breakage, and abutment tooth fracture will be evaluated clinically for both space maintainers

Gingival index 0 = normal gingiva; 1 = mild inflammation: slight change in color, slight edema, no bleeding on probing; 2 = moderate inflammation: redness, edema, and glazing, or bleeding on probing; 3 = severe inflammation: marked redness and edema, tendency toward spontaneous bleeding