The first permanent molar has no deciduous predecessor. The first molar erupts in permanent dentition around the age of six, marking the onset of a period of mixed dentition. The upper molar has four cusps and three roots, while the lower has five cusps and two roots. It is the strongest and largest tooth, which compensates for the physiological strain upon chewing. It is considered the “key of occlusion” due to a stable position determining the formation of a regular occlusion. Its eruption marks the beginning of the second stage of physiological occlusion. They are regularly the first and most often affected by caries, due to their morphology, contaminated environment and underdeveloped tooth enamel at the eruption stage, negative effects at the pre-eruptive stage, exposure to microorganisms or positioning in the dental arch. Preventive methods of treatment include parent and child education, mechanical and chemical control of dental plaque, regular check-ups with a dental surgeon and a controlled diet. Remineralising products are frequently fluorine-based and due to specific morphology fissure sealing is another option. A good and timely diagnosis is the key in choosing therapeutic procedures, which include restorative procedures, indirect or direct pulp capping, partial or complete pulpotomy, apexogenesis, revascularisation or conventional endodontic treatment. Although indications to first molar extraction are rather limited, a questionable long-term prognosis coupled with a second permanent molar meeting the necessary criteria, it is a reasonable therapeutic option. Should the extraction be executed outside this indication, the biostatic balance and articulation of the whole dentition will be disrupted.