When a tooth is extracted, the periodontal ligament fibres must be severed to allow the tooth to be removed from the socket. Which type of fibre forms the majority that must be severed during this procedure?

The correct answer highlights the significance of oblique fibres in the periodontal ligament during tooth extraction. Oblique fibres primarily function to support the tooth by connecting the cementum of the tooth root to the alveolar bone, providing resistance to the forces of mastication and helping to stabilize the tooth within the socket. During the extraction process, these fibres must be severed to facilitate the removal of the tooth, as they are the predominant type of fibres oriented in a way that resists the upward movement of the tooth.

The oblique fibres are positioned in such a manner that they run from the bone to the cementum at an angle, which is crucial in retaining the tooth in its socket. Severing these fibres is essential to make the extraction easier and prevent damage to surrounding structures.

In contrast, while alveolar crest fibres, apical fibres, and transeptal fibres also play roles in periodontal attachment, they do not have the same predominant presence nor the same orientation as oblique fibres, making them less critical in the context of extracting a tooth. Alveolar crest fibres are located along the crest of the alveolar bone, apical fibres are found at the apex of the root, and transeptal fibres connect adjacent teeth, but they are not