## 4 Discussion
Nonetheless, few authors have pointed out a lesser risk of errors compared to the replica technique [6; 7]. The material type used also plays an important role in producing a better marginal fit and enhances surface properties [8]. In the present study, we used dimethacrylates in 3D printing, PMMA blocks in the CAD-CAM technique, and powder liquid PMMA resins in the conventional technique. According to [PERSON] (2009), polyfunctional methacrylate, multifunctional methacrylate, and PMMA resins produce optimum marginal fit and better surface property because difunctional monomers permit the additional attachment of excess monomers that lead to a better mechanical property [9]. For conventional techniques, studies have reported that it is necessary to allow the resin-based material (PMMA) to properly mix under the standard powder and liquid ratio until a consistent mixture is reached and allowed to set on the prepared tooth [8; 9]. The discrepancy is associated with the polymerization shrinkage of PMMA loose material compared to a condensed block of PMMA, which reduces the problem of shrinkage as these milled blocks are pre polymerized and dense [8; 21; 9]. For a better fit, the authors emphasized removing the crown at a suggested duration to limit the distortion of the interim restoration. [PERSON] and [PERSON] (2015), on the other hand, showed that the composite material used is far more superior to the auto polymerizing PMMA because of low polymerizing shrinkage capability and no exothermic reaction [10; 11]. Hence, following up with the previous study findings, 3D printing produced better outcomes comparable to the conventional technique but similar to CAD-CAM. Certain studies have pointed out that the length, width, and thickness of the samples are equally important for accurate fitting restoration [10; 11]. [PERSON] et al. (2018) observed that the average error noted in length was lower when the machine settings of 3D printers were at white and flex resins [13]. The outcome of the white resin setting showed a significantly lower error compared to the castable resin setting group. Furthermore, the width of the restoration showed a significant impact in resin settings, where the correct settings offered a lower error than all other groups except the flex resin, which proved a lower error in marginal accuracy [13]. The surface roughness of a restoration alters under the influence of multiple factors, which include the fabrication technique, oral conditions, opposite dentition load, diet, material composition, and polishing techniques [12]. In the present study, the surface roughness was assessed based on the fabrication technique--CAD-CAM, 3D printing, and the conventional technique. The highest surface roughness was observed in 3D printing,with a similar outcome to the conventional technique. Nevertheless, the least surface roughness was observed using a CAD-CAM technique. This indicated that CAD-CAM produced a better milled interim crown, favorable for use in the long term. [PERSON] et al. (2004), in contrast to the present study, emphasized the effect of oral conditions on the restoration surface [14]. The author replicated storage conditions to identify the impact of saliva on the restoration. He pointed out that changes in the pH (acidic to alkaline) contribute mainly to surface changes of the restoration, especially interim crowns. In addition, literature has shown that upon exposure to a moist environment, the degree of surface roughness increases [15,16]. This signifies that if the produced interim restoration has surface defects, then the risk for surface roughness greatly increases upon exposure to oral conditions. Hence, a better selection of fabrication is important to reduce the risk of surface change over time under the influence of an altered oral environment. The present study revealed a significant difference in surface property, irrespective of the oral conditions present. This suggested that the difference in material composition acted as a major factor for affecting surface smoothness [22,23].