## 4 Discussion  
This study assessed and compared the retention of temporary/provisional anterior crowns based on the combined effect of different digital manufacturing techniques, preparation tapers, and the temporary cements used. A significant difference in retentive force was observed among the eight groups. Therefore, the hypothesis can be rejected. The production of prostheses by digitalization may be achieved by two methods: subtractive and additive manufacturing technologies. Subtractive manufacturing is a method used to obtain a designed shape by grinding the materials of the block or disc, whereas additive manufacturing involves the consecutive piling of powder and liquid material [25]. The results of the present study indicated that the retention of 3D-printed crowns is superior to that of CAD/CAM-milled crowns. The mean pull-off force value (in newtons) was higher for group 5, i.e., 3D-printed crowns with 10-degree taper and non-eugenol cement (49.47 N), than for group 1, i.e., milled crowns with 10-degree taper and non-eugenol cement (43.01 N). When comparing the mean pull-off values between groups 2 and 6, an exponentially higher value (158.38 N) was recorded for the 3D-printed group than for the milled group. Additionally, the outcome pertaining to group 7 (65.48 N) was found to be higher than that for group 3 (49.25 N). Further, the highest outcome was obtained for group 8, i.e., 3D-printed crowns with 20-degree taper and clear cement (178.74 N). Our results were in concordance with a large number of previously conducted studies. A study conducted by [PERSON] et al. evaluated the internal fit of crowns manufactured using the CAD/CAM milling and 3D printing methods. It was concluded that the marginal and internal fit of the provisional restoration/prostheses created using the 3D-printing method was superior to those created using CAD/CAM milling [21]. Additionally, in a study carried out by [PERSON] et al. to assess the influence of fabrication techniques (conventional, CAD/CAM, and 3D printing) on the marginal fit, adaptation, surface roughness, and wear of the interim restorations of crowns, it was highlighted that 3D-printed interim specimens demonstrated superior fit, adaptation, and wear properties compared to the other groups [26]. Prostheses fabricated using 3D printing technology have favorable fracture strength during compression compared to self-cured or CAD/CAM-milled crowns, which could be attributed to the increased flexural strength, since an increase in flexural strength is associated with bending at the onset of compression [27]. It has also been showcased that the 3D printing system makes use of a self-heated tray and an ultraviolet layer-by-layer polymerization technique to manufacture long-term provisional restorations for intraoral use, resulting in acceptable biocompatible properties and a lower tendency of plaque build-up, thus causing fewer chances of gingival irritation [28]. Additionally, 3D-printed crowns have shown superior efficacy to CAD/CAM-milled and conventionally fabricated crowns in terms of marginal fit, adaptation, and surface wear. Retention and resistance forms are the features of a preparation that prevent prostheses from becoming uncemented, debonded, or cement failures [29]. Occlusal convergence may be described as the converging angle of two opposite axial walls in a given plane. The literature suggests that parallel axial walls offer maximum retention and resistance, whereas highly converging or tapering walls offer the least. The permissible degree of preparation taper in the current literature recommends the taper within the range of 2\({}^{\circ}\) to 6\({}^{\circ}\)[30]. However, this is not applicable in clinical situations. An adequate taper in a preparation makes up for any imprecisions that may transpire during the fabrication of the prostheses, facilitates a favorable path of insertion, and permits precise seating during cementation.