periodontium

PERIODONTIUM

-Dr Ambreen Ifikhar

-Dr Anika Anis Gul

Periodontium

Definition: Periodontium refers to the specialized

tissues that both surround and support the teeth, maintaining them in the maxillary and mandibular bones.

The word comes from the Greek terms peri-, meaning "around" and -odons, meaning "tooth”.It provides the support necessary to maintain the teeth in function.

Components of Periodontium

It consists of four principal components namely:

Gingiva Periodontal ligament

(PDL) Cementum Alveolar bone

Gingiva

The gingiva covers the alveolar bone and the tooth root to a level just coronal to the CEJ

TYPES : Marginal gingiva Interdental gingiva Attached gingiva

Mucogingival junction:

A clearly defined mucogingival line that demarcates the attached gingiva from the adjacent alveolar mucosa.

Clinically the alveolar mucosa is red,smooth and shiny unlike the gingiva which is pink and stippled in appearance.

Histologically, the epithelium is thinner,non keratinized and contains no rete pegs.

Gingival Epithelium : 1. Oral (outer) epithelium

2. Junctional epithelium

3. Sulcular epithelium

1) ORAL EPITHELIUM:

Covers the crest & outer surface of marginal gingiva & the surface of attached gingiva.Average thickness is ‘0.2-0.3mm’

2) SULCULAR EPITHELIUM:

Lines the gingival sulcus & is thin,non-keratinized stratified.sq epi. extends from coronal limit of JE to crest of gingival margin.

3) JUNCTIONAL EPITHELIUM:

Consists of a collarlike band of stratified.sq epi.Length of JE ranges from `0.25-1.35mm’

Biological WidthThe dimension of space that the healthy gingival tissues occupy above the alveolar bone is identified as the biological width.

clinically biologic width violation is done when the restoration margin is placed 2mm or less from the alveolar bone ,esp.when the gingival tissues are inflamed.

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Periodontal ligament

Definition: The periodontal ligament is the soft

specialized connective tissue situated between the cementum covering the root of the tooth

and the bone forming the

socket wall.

Functions of Periodontal ligament :

It provides a soft tissue casing to protect the vessels and nerves from injury by mechanical forces

Attachment of teeth to the bone Maintenance of gingival tissues in their

proper relationship to the tooth Resistance to impact of occlusal forces

Components of the Periodontal ligament

The PDL consists

CELLS

osteoblasts,osteoclasts,fibroblasts,rest cells of malassez,macrophages,undifferentiated mesenchymal cells and cementoblasts AN EXTRACELLULAR COMPARTMENT

Consists of well defined collagenous fibres embedded in a non collagenous extra cellular matrix of glycoproteins and glycolipids.

PERIODONTAL FIBRES: The predominant collagens of PDL are types 1. They are arranged in distinct and definite fiber

bundles and are able to adapt to the continual stresses placed on them

The principal fibres consists of

- alveolar crest group

-the horizontal group

-the oblique group

-the apical group

-the interradicular group All these principal fibres are embedded as

sharpeys fibres in the cementum or bone.

Principal Fibres The Alveolar crest fibres extend

obliquely from the cementum to the alveolar crest

The Horizontal fibres extend at right angles to the long axis of the tooth from the cementum to the alveolar bone

The Oblique fibres extend from the cementum in a coronal direction obliquely to the bone

The Apical fibres radiate at the apical region of the socket from the cementum to the bone

The Interradicular fibres fan out from the cementum to the tooth in the furcation areas of multi rooted teeth

Cementum:

Definition:

Cementum is a calcified avascular tissue that forms the outer covering of the anatomic tooth.

Types of cementum

-Primary (accelular) cementum

-Secondary (cellular) cementum

Composition of cementum:

INORGANIC: -45 to 50% hydroxyapatite crystals

ORGANIC: -50% organic(collagens and non collagenous

proteins)

90% is type 1 & 5% type 3 collagen.

Classification of cementum Acellular afribrillar cementum(AAC):

-Mineralized ground substance

-No cells nor intrinsic or extrinsic collagen

-Present as coronal cementum Acellular extrinsic fiber cementum(AEFC):

-densely packed sharpeys fibres

-lacks cells

-found in cervical 3rd of the roots Cellular mixed stratified cementum(CMSC):

-contains cells,extrinsic and intrinsic fibers.

-found in the furcation area and in apical 3rd of roots Cellular intrinsic fiber cementum(CIFC):

-contains cells but no extrinsic fibres

-fills the resorption lacunae Intermediate cementum:

-a poorly defined zone near the CEJ of teeth.

Cementoenamel junction:Three types of joints may exist:

- 60-65%Cementum overlaps enamel

-30% edge-edge butt joint exists.

- 5-10% where enamel and dentin fail to meet, leaving dentin exposed.

Alveolar ProcessAlveolar process is the portion of maxilla and mandible that forms and supports the tooth sockets.

It consists of,

-External buccal and lingual cortical plate.

-Inner socket wall of compact bone called Alveolar bone proper,seen as lamina dura in radiographs.

-Cancellous trabeculae between these two layers,which act as a supporting alveolar bone.

Thank you!