Introduction: Access cavity preparation is indeed a pivotal step in successful endodontic treatment. It ensures efficient removal of diseased or infected tissue, facilitates thorough cleaning, and enables effective shaping and sealing of the root canal system, therefore eventually giving favorable results of the treatment. Conservative endodontic cavity (CEC) preparation aims to reduce the removal of tooth structure while still providing access to the root canal system. Unlike traditional endodontic cavity (TEC) preparation, where the roof of the pulpal chamber is detached, CEC focuses on preserving as much of the tooth architecture as possible, including pericervical dentin. The primary goal is to locate and access the canal orifices while maintaining the integrity of the tooth. Lateral compaction (LC) has been the most widely used root canal obturation technique. Thus, the study objective is to compare the fracture resistance by a universal testing machine (UTM) and to evaluate the compaction quality of lateral condensation (LC) obturation using radiovisiography (RVG) and stereomicroscope. Objectives: • Evaluation and correlation of fracture resistance of endodontically treated teeth with traditional vs conservative endodontic/access cavity preparation in permanent mandibular molars. • To analyze and compare compaction quality of LC obturation in teeth with Traditional vs Conservative endodontic/access cavity preparation in permanent mandibular molars. Materials and methods: Forty extracted permanent mandibular molars were gathered for the study. Through random allocation, they were split into two main groups, group I and group II, each comprising 20 teeth. These groups were then subdivided into two additional subgroups, denoted as group Ia, Ib, group IIa, and IIb, allowing for nuanced examination within the experimental framework. In group I, samples were prepared for determination of fracture resistance. In group Ia TEC was prepared and in group Ia CEC were prepared. Class II mesio-occlusal cavities were prepared for both group Ia and Ib. In group II, samples were prepared for the determination of the compaction quality of LC obturation. In group IIa TEC were made and in group IIb CEC were prepared. A UTM, was employed to test for fracturing for samples in group I, a constant compressive pressure was applied on the central fossa at a 15° angle in the lingual direction to the long axes of the teeth. The speed of pressure application was set at 1 mm/min using a 6 mm round-head tip as before the fracture. Those particular pressures that consequently resulted in concomitant fracture were noted down in Newton units. For compaction quality testing, in group II all samples were subjected to radiographic evaluation in both buccolingual (BL) and mesiodistal (MD) views for the quality of obturation using a four-point scale (Kersten et al. 1987) and then evaluated under stereomicroscope for apical dye penetration (microleakage evaluation) using (WP Saunders et al. 1993) criteria. The data collected was statistically analyzed. Results: In terms of fracture resistance, group Ib CEC showed higher fracture resistance as compared to group Ia TEC. Whereas, in terms of compaction quality of LC obturation, the group IIa TEC and group IIb CEC showed that, there were no noteworthy differences between compaction quality of LC obturation technique (both radiographic evaluation and microleakage evaluation). Conclusion: Due to pitfalls of aforesaid in vitro study, it may be summarized as: • The greater fracture resistance was recorded for CEC treated teeth, those made with the endodontic procedure when compared with teeth made by employing TEC preparative method. • A notable distinction in fracture resistance was observed between TEC and CEC endodontic cavity approaches. • There was no significant difference between the compaction quality of LC obturation technique of TEC and CEC procedures.