## 2 Materials and Methods  
This in vivo study was approved by the Tel-Aviv University Ethics Committee and was performed in the student dental clinic at Tel-Aviv University, School of Dental Medicine. Inclusion criteria were periodontitis healthy patients, fully dentate with stable occlusion, and a single posterior (molar or premolar) tooth intended to receive a monolithic crown adjacent to or between natural teeth. Exclusion criteria were patients with periodontal disease, absent adjacent tooth, subgingival preparations or practical difficulties in achieving accurate digital impressions. The teeth were prepared to receive all ceramic crowns of lithium disilicate (IPS e.max CAD; Ivoclar Vivadent, Schaan, Liechtenstein). Preparations were completed using diamond burs F1R and F2R (Strauss Co., Raanana, Israel), with 1 mm chamfer finish line and occlusal reduction of 1.5 mm. The final preparations were checked by two clinical instructors using digital software (PrepCheck; Dentsply Sirona, York, PA, USA), which validated acceptable clinical preparation including convergence angle and equi-gingival finish line design. Digital impressions were made using an intra-oral, powder-free scanner (Omnicam; Dentsply Sirona). The crowns were digitally designed in CAD software (Cerec SW4.3; Dentsply Sirona) and milled (Cerec MC XL; Dentsply Sirona) with a spacer setting of 120 \(\upmu\)m for the internal gap and 0 \(\upmu\)m for the marginal gap. The designed occlusal scheme was designed according to the adjacent teeth. The milled crowns were then sintered and glazed following manufacturer's instructions. The crowns were randomly divided into 3 groups and cemented to the prepared teeth using 3 different lung agents: (1) SARC group (n = 15) self-adhesive resin cement (G-CEM LinkAce, GC Corporate, Tokyo, Japan), (2) RMGIC group (n = 15) resin-modified glass ionomer cement (GC FujiCem2, GC Corporate), and (3) ARC group (n = 15) adhesive resin cement (G-CEM LinkForce, GC Corporate: Tokyo, Japan). Proximal inferences were examined, and digital bitewing X-rays were taken just before cementation using an XCP film holder (Dentsply) to ensure adequate fitting of the restoration. The crowns were cemented following manufacturer's instructions. For etching, 5% hydrofluoric acid (Vita Ceramics Etch; Vita Zahnfabrik, Bad Sackingen, Germany) was applied for 20 s to the intaglio surface of the lithium disilicate crowns and rinsed with gentle water spray for 20 s. Subsequently, silane was applied on the inner surface (Monobond Plus; Ivoclar Vivadent). In the SARC group, the resin material was placed in the crowns, which had been seated immediately using bite pressure for 3 s. Afterwards, each surface was tack cured with a visible light curing unit. The excess cement was removed, and each surface was cured again for 20 s.  
In the RMGIC group, before applying the mixing tip, a small amount of paste was bled to ensure even flow from the cartridge. The cement was applied in the crowns and seated on the teeth. The excess cement was removed when it felt rubbery. Finger pressure was maintained for 5 min by a single operator (AB). In the ARC group, the teeth were etched with 37% phosphoric acid for 15 s, then gently rinsed and dried. An adhesive (G-Premio Bond; GC) was applied on the prepared surface. It was scrubbed for 10 s, dried for 5 s and then light cured for 10 s. The cement was applied to the internal surface of the crown with an automix syringe, and the crowns were seated on the respective teeth as described for the SARC group. Intra-oral scans of the restoration including the two adjacent teeth using a standardized scanning protocol including a buccal starting point on the distal adjacent tooth to the buccal surface of the mesial adjacent tooth to the occlusal surfaces, finally to the lingual surfaces. All scans were performed by a single operator (AB) and were conducted at 2 time points: after final treatment of the crown immediately before cementation and after cementation after removing the excess cement.