1. INTRODUCTION An occlusal splint is a custom fabricated hard acrylic device that fits over the occlusal and incisal surface of maxillary or mandibular teeth. Occlusal splints represent the main therapeutic option for patients suffering from temporomandibular disorders (TMDs) and bruxism. 1 Its principle use is to prevent the patient from finding his usual occlusion of maximal intercuspal position (ICP) and to oblige him to place his mandible in a new posture, thus, resulting in a new muscular and articular balance.3 Occlusal splints must withstand occlusal forces, be aesthetically pleasing and comfortable. Occlusal splints are conventionally made with self-cure or heat cure acrylic resin. But a great quantity of residual monomer and polymerization shrinkage can influence the mechanical properties of occlusal splints and decrease their clinical performance.2 The materials used in fabrication of occlusal splints must have adequate occlusal stability to withstand applied loads in the oral environment without changing their mechanical properties.2 In the human dentition, the mean occlusal forces range from 107 to 156 N (10 kg to 15kg).4 During parafunctional habits, these forces can reach upto 794 N (81.2 kg). 5Recently, digitally supported fabrication processes such as Computer-aided design/Computer-aided manufacturing (CAD/CAM) has allowed the usage of Subtractive technology (Milling) and Additive technology (3D-printing) and has given rise to an improvement in materials used in fabrication of occlusal splints. CAD/CAM Milling is well known in the field of dentistry and so is the reason it is studied widely. Whereas studies on 3D printing still remains less documented. In this study the Comparison for mechanical properties will be made between will be made between Conventional technique, Milled and 3D printed occlusal splints. 2. AIM AND OBJECTIVES Aim: The aim of this study is to compare the flexural strength and surface roughness of occlusal splints fabricated by Conventional technique, Milling and 3D printing in order to determine the suitability for clinical applications in Prosthodontics. Objectives:  To Evaluate and compare the flexural strength values amongst the occlusal splints fabricated by Conventional technique, Milling and 3D printing.  To Evaluate and compare the surface roughness values amongst the occlusal splints fabricated by Conventional technique, Milling and 3D printing.  To draw conclusions based on the comparative analysis of flexural strength and surface roughness of occlusal splints fabricated by Conventional technique, Milling and 3D printing. DISCUSSION The present in-vitro study compared the flexural load-bearing capacity and post-polishing surface roughness (Ra) of denture base resins fabricated by three contemporary techniques: conventional heat-cured compression moulding (Group I), subtractive CAD-CAM milling (Group II), and additive 3D printing (Group III). The milled specimens recorded the highest mean flexural strength (543.50 N), followed by the 3D-printed specimens (403.66 N), with the conventionally processed specimens performing markedly lower (130.55 N). An almost identical hierarchy was observed for surface smoothness, where the milled group achieved the lowest, most favourable Ra value (0.093 µm), the 3Dprinted group an intermediate value (0.300 µm), and the conventional group the highest, least favourable value (0.363 µm). The consistency of this ranking across two mechanically and clinically distinct properties suggests that both outcomes are governed by a common underlying variable: the degree of polymer homogeneity and porosity produced by each fabrication method. FLEXURAL STRENGTH The superior performance of the milled group is consistent with several recent comparative studies. Milled denture base pucks are machined from industrially pre-polymerised, highly cross-linked polymethyl methacrylate (PMMA) blanks that are polymerised under standardised high pressure and temperature, which minimises residual monomer content, porosity, and processing-related defects, in turn translating into higher flexural strength and modulus [1,3,4]. Alshali et al. similarly reported that milled denture base materials exhibited significantly higher flexural strength than 3D-printed materials across control, thermocycled, and fatigue-cycled conditions, attributing this to the superior degree of conversion achieved during industrial block manufacture compared with layer-by-layer photopolymerisation [1]. Alharethi reached the same conclusion, showing that CAD-CAM milled resin achieved flexural stress roughly 1.7-2.0 times that of 3D-printed resin printed at two different build angles [3]. The intermediate strength of the 3D-printed group in the present data is also broadly in keeping with the literature, although the magnitude of the printedversus-conventional advantage is not universally reproduced. Some authors report that 3D-printed resins can match or even exceed milled and conventional materials in flexural strength and modulus when optimal post-curing protocols are used, attributing this to a higher degree of cross-linking achieved through UV/thermal post-polymerisation of printable resins containing multifunctional methacrylate oligomers [2]. This discrepancy across studies highlights that the mechanical performance of 3D-printed denture base resin is highly dependent on printer technology, resin chemistry, layer thickness, build orientation, and post-curing regimen, factors that are not standardised between commercial systems [3,6]. In the present study, the comparatively low strength recorded forthe conventionally processed group (130.55 N) is lower than is typically reported for heat-cured PMMA in the literature, and most plausibly reflects porosity introduced during manual powder-liquid mixing, packing, and dough moulding, along with a wider range of individual specimen values (113.5-147.5 N) than seen in the other two groups. This variability is a well recognised drawback of the conventional technique, where operator-dependent factors such as mixing ratio, working time, and curing cycle can introduce internal voids that act as stress concentrators and crack initiation sites during flexural loading [4,7]. It should be noted that flexural strength values in this study were recorded as load-tofracture in Newtons (N) rather than converted flexural stress in MPa; because this comparison was performed on specimens of standardised, identical dimensions within the same study, the relative ranking between groups remains valid, though the absolute values cannot be directly compared with the MPa-based minimum requirement of 65 MPa specified in ISO 20795-1, or with stress values reported in other studies, without knowledge of specimen crosssectional geometry. SURFACE ROUGHNESS Surface roughness after polishing followed the same overall pattern, with milled specimens smoothest and conventional specimens roughest. This is consistent with Kraemer Fernandez et al. and Nejatidanesh et al., who found that milled PMMA disks retained a smoother, more homogeneous surface after polishing than printed or conventional resins, attributed to the absence of internal porosity that would otherwise be exposed and roughened during finishing and polishing procedures [8,10]. Heat-cured conventional acrylic, by contrast, is known to retain surface and subsurface porosities from the mixing and curing process that become exposed as micro-pits during polishing, elevating Ra despite mechanical or chemical polishing [8]. The intermediate roughness of the 3D-printed group likely reflects the characteristic "staircase" effect of layer-by-layer photopolymerisation, where residual ridges between print layers persist even after polishing unless print orientation and layer thickness are carefully optimised; build orientation has been shown to significantly affect roughness independent of print parameters otherwise held constant [3,11]. Clinically, surface roughness is important because it directly influences plaque and biofilm accumulation on the denture-fitting and polished surfaces, and hence the risk of denture stomatitis and halitosis. Bollen and colleagues proposed a threshold Ra of 0.2 µm, below which further reductions in surface roughness produce no additional decrease in bacterial adhesion, while values above this threshold are associated with a roughness-proportional increase in bacterial retention [9]. Applying this benchmark to the present findings, only the milled group (0.093 µm) fell below the 0.2 µm threshold, suggesting that milled denture bases are likely to be clinically more resistant to biofilm accumulation than either 3D-printed (0.300 µm) or conventional (0.363 µm) bases, both of which remained above the threshold despite standardisedpolishing. This finding has direct relevance to denture hygiene, patient comfort, and the incidence of prosthesis-associated stomatitis, particularly in medically compromised or elderly denture wearers who may have reduced manual dexterity for oral hygiene maintenance. INTEGRATION OF FINDINGS AND CLINICAL IMPLICATIONS Taken together, the concordant ranking of flexural strength and surface roughness (milled > 3D-printed > conventional for strength; milled < 3D-printed < conventional for roughness) supports the interpretation that industrially controlled, subtractive milling currently offers the most favourable combination of mechanical durability and surface quality among the three fabrication methods evaluated. This has practical implications for material selection: milled bases may be preferable for patients with heavy occlusal loads, parafunctional habits, thin denture bases, or long-term/definitive prostheses where fracture resistance is a priority, and for patients at higher risk of denture stomatitis where a low-plaque-retentive surface is desirable. 3D printing, while currently intermediate in both properties in this dataset, remains attractive for its manufacturing speed, material efficiency, and suitability for interim or transitional prostheses, and its mechanical and surface performance is likely to improve as resin formulations and printing protocols mature. Conventional heat-cured acrylic, despite its lower performance in both parameters here, remains the most accessible, cost-effective, and clinically established technique, and its shortcomings may be mitigated through improved mixing, packing, and curing protocols, and possibly through processing under vacuum or pressure to reduce porosity. LIMITATIONS Several limitations should be acknowledged. The sample size (n = 15 per group) is comparable to similar in-vitro studies but limits generalisability; testing was confined to a single commercial product per fabrication category, whereas resin chemistry varies considerably between manufacturers and printing systems [2,3,6]; specimens were tested in a single "as-polished" condition without simulated intraoral aging, thermocycling, or mechanical/chemical brushing, all of which are known to alter both flexural strength and surface roughness over time [1,11]; and flexural strength was recorded as load-to-fracture (N) rather than converted flexural stress (MPa), restricting direct comparison against ISO benchmarks and other published stress-based data. Furthermore, in-vitro bar or disc specimens do not fully replicate the complex geometry, thickness variation, and functional loading patterns of a clinical denture base, and correlation with actual clinical fracture rates, patient-reported outcomes, or biofilm colonisation was not assessed. Future work should incorporate multiple brands per fabrication category, simulated aging and fatigue protocols, conversion of load data to standardised flexural stress and modulus values, and clinical or in-vivo biofilm correlation studies to validate these laboratory findings. CONCLUSION Within the limitations of this in-vitro study, CAD-CAM milled denture base resin demonstrated significantly superior flexural strength and the smoothest postpolishing surface among the three fabrication techniques evaluated, followed by 3D-printed resin, with conventionally heat-cured resin showing the lowest flexural strength and the highest surface roughness. Only the milled group achieved a mean surface roughness below the 0.2 µm threshold considered clinically significant for bacterial plaque retention, while both the 3D-printed and conventional groups remained above this threshold. These findings suggest that milling currently offers the most favourable balance of mechanical strength and surface quality for denture base fabrication, that 3D printing represents a viable but currently intermediate alternative whose performance is likely to improve with technological refinement, and that conventional processing, while clinically proven and economical, may benefit from technique modifications to reduce porosity-related weaknesses. These laboratory observations should be corroborated by studies using standardised stress-based mechanical testing, simulated intraoral aging, larger and more diverse material samples, and clinical outcome data before firm evidence-based recommendations can be made for denture base material selection. cite these articles according to vancouver style and write references and bibliography for my thesis