Cementum

Cementum Least highly mineralised tissue of the tooth Covers the entire root surface Two main types: Acellular Cementum Cellular Cementum No cells present in the acellular There are cells present in the cellular – Cementocytes The cells that form both – Cementoblasts

Cementum Acellular cementum covers the entire root surface Lies next to the outer surface of the dentine Cementoblasts lie next to the outer surface of the dentine Start to form cementum – this will be acellular – very slowly Organic matrix, mainly collagen, along with a ground substance is laid down first, and is subsequently mineralised

Cementum The fibres, referred to as intrinsic fibres, are very small These fibres are aligned parallel to root surface Is the means by which the fibres of the periodontal ligament (PDL) are attached to the tooth Collagen fibres of the PDL are inserted into the cementum These (second type) are referred to as the extrinsic fibres

Cementum Aligned perpendicular to the root surface Formed by fibroblasts – originated from within the PDL Cellular cementum – found usually around the apex of a single-rooted tooth and at both the apices and bi/trifurcation region of multi-rooted tooth Formed much more rapidly than the acellular – probably the reason why cells are therefore ‘caught up’ in the tissue

Cementum Cementocytes are no longer formative cells – exist permanently within lacunae within the cementum Thin processes (canaliculi) point towards the PDL Source of nutrition for both acellular and cellular cementum During periodontal disease – there is loss of (PDL) attachment of the tooth to bone

Cementum Cementum in those areas becomes redundant Should be removed during treatment Has lost its source of nutrition and function, and so becomes merely a roughened source covering the outer surface of the root of a tooth No function! If not removed, will attract dental plaque and may encourage further loss of attachment of the tooth

Ground section of a tooth showing enamel, dentine, the pulpal cavity and cementum The cementum at the apex is thicker and will be made up mainly of cellular cementum

  Ground section of a root demonstrating dentine (A) and cellular cementum (B)