Junctional Epithelium / Epithelial Attachment

1. Junctional Epithelium / Epithelial Attachment What and where it is Where it comes from What it does Why it does it

2. What and Where is the Junctional Epithelium • Epithelial attachment and clinical attachment level • Collar-like band of nonkeratinised stratified squamous epithelium • Extends from cementoenamel junction - bottom of gingival sulcus • Coronally: 15-30 cells thick. Apically: narrows to 1-3 cells • Length: 0.25 – 1.35mm & has rate of turnover

3. A- gingiva B- sulcular epithelium C- junctional epithelium D- lamina propria (connective tissue) E- alveolar process F- PDL ES- enamel space JE – junctional epithelium CT- connective tissue

4. Where does it come from ? • Initially derived from Reduced Enamel Epithelium • REE replaced once tooth erupts – REE covering crown lost rapidly replaced by squamous epithelial cells • Transformed REE & oral epithelium form dentogingival junction and junctional epithelium • Final conversion of REE to JE may not occur until 3-4 years post eruption

5. Important Features • Cells of JE immediately adjacent to tooth attach to tooth by hemidesmosomes & basal lamina • Combination is known as the epithelial attachment • Basal lamina in contact with tooth: Internal Basal lamina • On opposite surface – JE in contact with lamina propria of gingiva & attached by hemidesmosomes and basal lamina • Basal lamina in contact with lamina propria: External Basal Lamina

6. Junctional epithelium is unique as it possess 2 basement membranes – the internal and external basal lamina Enamel Lamina propria Hemidesmosomes Internal Basal Lamina External Basal Lamina

7. JE CT External basal lamina Enamel space Internal basal lamina

8. Enamel Cuticle • Not visible in demineralised sections • Non-mineralised structure between JE and underlying hard tissue • Cuticle also seen between JE and underlying cementum

9. Length of Junctional Epithelium • Length varies according to stage of eruption • Tooth first erupts – most of enamel covered by JE • Tooth reaches occlusal plane – ¼ enamel surface covered • Eventually JE lies close to CE junction • Older patients with root exposure (passive eruption or disease) JE proliferates apically - firm attachment with cementum

10. Other Fantastic Facts You Really Wanted to Know About the Junctional Epithelium!!!! • Lamina propria of gingiva – good vaculature and source of nutrient to JE and source of GCF • JE is permeable & tissue fluid and cells pass into GCF • Turnover of JE is rapid. Epithelial cells migrate coronally & shed into oral cavity via gingival crevice • Rate of turnover dependent on demands placed on tissue. Directly related to degree of inflammation

11. What it does and why it does it • Has attachment role and protective role • Permeability allows GCF and defence cells to pass across to protect underlying tissues from disease processes (periodonal disease) • Helps maintain integrity of tooth / periodontium structure.

12. Role of JE – Clincial significance • GCF contains g globulins and ploymorphonucleocytes (PNMs) giving it immunological / phagocytic properties to combat disease processes • Such molecules pass readily across JE to underlying tissues • JE (& GCF) good indicator for severity of periodontal disease – may contain neutrophils & other inflammatory cells indicating disease – & state of health of periodontium • Research into this ongoing in Bham – understanding progression of disease & development of diagnostic marker of severity of disease

14. Reason why I have not been around for the past 2 weeks!!