BioCem™ (NuSmile, Texas, USA) was evenly distributed to the inner surface of the crown with the syringe and immediately placed onto the teeth. Crowns were stabilized for 20 seconds before applying halogen/LED light (800-1200mW/cm2) (Valo Cordless, Ultradent) to the buccal and lingual/palatal surfaces for three seconds each.

The inner surface of the crowns was treated with 'G-Multi Primer' using a brush and subsequently air-dried. The surfaces of the prepared teeth were treated with 37% orthophosphoric acid. The tooth surfaces were rinsed with an air-water spray to remove the acid from the surfaces. After the etching process, the 'G-Premio Bond' was applied to the teeth surfaces with a brush, rubbed for 10 seconds, and then air-dried for five seconds. Then the teeth were exposed to halogen/LED light (800-1200mW/cm2) (Valo Cordless, Ultradent) for 10 seconds. G-CEM Linkforce (GC, USA) resin cement was gently applied to crowns, and then crowns were pressed onto the prepared teeth with finger pressure.

The capsule was attached to the mixer and mixed for 10 seconds. The cement was evenly distributed to the crowns paying attention that there were no air voids. Then crowns were placed by pressing them onto the prepared teeth with finger pressure.

After the caries were removed, the teeth were prepared by shaving according to the manufacturer's recommendations for NuSmile ZR.

The clinical success of the crowns regarding the retention status was evaluated as either present or absent based on whether the crown remained on the restored tooth at each follow-up appointment. Crowns that were still in place during the follow-up visit were considered successful in terms of retention, while those that had decemented were considered unsuccessful.

Maintaining pulpal vitality is also a criterion for the success of a restoration and is assessed not by a graded score but by the presence or absence of symptoms and findings. In this study, pulpal vitality was clinically evaluated based on the presence or absence of percussion sensitivity, palpation sensitivity, gingival redness, fistula or abscess. If percussion sensitivity, palpation sensitivity, or the formation of a fistula or abscess were present, the restoration was classified as unsuccessful regarding pulpal vitality. In cases of gingival redness or unclear clinical symptoms, a periapical radiograph was taken. If presence or absence of radiolucency in the periapical or furcal area was detected in the radiograph, the restoration was classified as unsuccessful regarding pulpal vitality.