Gingiva and Peri-implant Tissues

• what is a dental implant?

  an artificial tooth that is placed over an abutment (a metal-like screw) that is fixed into your jaw.

  
• Describe the basic anatomy of the implant restoration.

  
• What is the periodontium?

  all the supporting structures of the tooth:

  • gingiva

  • periodontal ligament

  • cementum

  • alveolar bone
• What is the peri-implant tissue?

  All the supporting structures of the implant:

  • Peri-implant mucosa (like gingiva)

  • NO periodontal ligament

  • NO cementum

  • Alveolar bone

  
• describe gingiva

  • part of the oral mucosa

  • epithelial covering, over connective tissue

  • rapid epithelial turnover

  
• what is the function of gingiva?

  protection
• what are the three gingiva names depending on position?

  - attached gingiva

  (largest element)

  
  

  - free gingiva

  (rolled area around the necks of the teeth)

  
  

  - crevicular (gingival crevice where there is a little ridge where your teeth meet your gums)

  and junctional areas (junctional epithelium attached to tooth surface)

  
• what are the two elements that gingiva has?

  - Epithelial elements

  - Connective tissue elements
• describe the free gingiva


  • from free gingival groove to tooth

  • pale pink, keratinised, slightly loose and smooth

  
• what is in between the free and attached gingiva?

  the free gingival groove

  
• describe the attached gingiva

  • pale pink, keratinised mucosa

  • from mucogingival junction to free gingival groove

  • firm and tightly bound onto bone

  • stippled (but not always)

  
• what is in between the attached and alveolar gingiva?

  mucogingival junction

  
• describe alveolar tissue

  • looser

  • less well bound down

  • much less well keratinized

  • thinner

  
• Interdental gingival tissue: the papilla

  
  

  describe the interdental papilla

  the gum tissue found in the space between the teeth.

  -> It helps protect the roots of your teeth and keeps food from getting stuck between your teeth, leading to decay.

  
• Interdental gingival tissue: the papilla

  
  

  the shape of the dental papilla varies depending on shape and size of teeth.

  when is it pyramidal?


  Where teeth are relatively narrow from buccal to lingual, the papilla is narrow also

  -> It is pyramidal

  
• Interdental gingival tissue: the papilla

  
  

  the shape of the dental papilla varies depending on shape and size of teeth.

  when is it a tent shape?


  Where the tooth is relatively wide from buccal to lingual, for instance at molars, the papilla is more like a tent shape

  -> This is called a COL

  
• how thick is the Gingival epithelium?

  0.2 to 0.3mm thick
• how many layers does the gingival epithelium have?

  4
• what are the 4 layers of the gingival epithelium?

  • stratum basale

  
  

  • stratum spinosum

  
  

  • stratum granulosum

  
  

  • stratum corneum

  
• describe gingival epithelium

  - orthokeratinised or parakeratinised

  - incomplete keratinisation
• what cells does the gingival epithelium contain?

  • melanocytes

  - produces and contains the pigment called melanin.

  
  

  • Langerhan's cells- at most coronal part of junctional epithelium:

  - Langerhans cells take up and process microbial antigens to become fully functional antigen-presenting cells. In severe infection, blood monocytes are recruited and differentiate into replacements.

  
  

  • Merkel cells- sensory touch receptors in stratum basale:

  - modified basal cells connected by desmosomes to neighboring keratinocytes, associated with the presence of nerve endings - more common with inflammation/damage

  - persist in the absence of teeth

  
  

  • some T cells (mostly suppressor)
• describe crevicular epithelium (also known as sulcular epithelium)


  keratinised

  
• describe junctional epithelium

  • non-keratinised, basal & suprabasal cells

  • large intercellular spaces:

  - permeable to chemicals, cells and fluids

  • rapid turnover: no cell differentiation / keratin / membrane coating granules

  • firmly attached by HEMIDESMOSOMES - spot welds to protein layer on enamel (extended basal lamina)

  
• what is the supracrestal tissue attachment (STA), also known as the "biologic width"?

  the distance established from the junctional epithelium and connective tissue attachment to the root surface of a tooth. It acts as a natural seal protecting the tooth from infections and diseases.

  - it is approximately 2mm

  
• when is junctional epithelium completely replaced?

  Completely replaced every 4 to 6 days

  -> Very rapid cell division and migration: all cells look like basal cells
• describe the permeability of the junctional epithelium

  VERY PERMEABLE

  
  

  - Cells and fluid from connective tissue go into the crevice

  - Toxins and other bacterial products enter into connective tissue and can cause inflammation and lead to gingival crevicular fluid leaking out.
• why do we put a periodontal probe in the crevice when the junctional epithelium is inflamed?

  - It is usually long, thin, and blunted at the end.

  - Its main function is to evaluate the depth of the pockets surrounding a tooth in order to determine the periodontium's overall health.

  - if the periodontium is healthy, the probe will extend into the junction epithelium which will give resilience and eventually cause the probe to stop.

  
• What is it like probing inflamed junctional epithelium?

  in the presence of inflammation, the epithelium is ulcerated and has less resilience and the connective tissue structure is broken down, so the probe will extend further into the area and it will be uncomfortable for the patient and may cause bleeding

  
• Is it possible to develop a junctional epithelium around implants?

  Yes, it exists and has variable length.

  
  

  It attaches to the titanium of:

  -implant surface

  -implant abutment

  
  

  Via:

  -hemidesmosomes which attaches to a basal lamina-like material on titanium surface
• What is a biological seal of an implant?

  The biological seal of the soft tissue-implant interface is created by epithelium and connective tissue

  
  

  - however the attachment is weaker

  
• What is a stable biological seal obtained with?

  3mm supracrestal soft tissue attachment, 1mm CT and 2mm JE
• what does the biological seal happen with?

  - A range of systems

  - Following abutment connection and disconnection

  - With or without loading

  - Different roughnesses

  - Alterations in tissue thickness
• What stops the epithelial downgrowth?

  The epithelium stops at a certain point, it doesn't keep growing down the side of the tooth.

  
  

  • Granulation tissue / mature underlying connective tissue controls epithelial downgrowth, even though adult mucosal epithelium is a stable phenotype.

  • However this is not deep underlying tissue, only the subepithelial area:

  it may be that apical migration is stopped by a lack of migration and differentiation signals from deeper tissue

  
• What comprises the gingival connective tissue?

  • Glycosaminoglycans

  + fluid (from blood)

  • Collagen (type I & III) fibres: organised and strong, 50-60% tissue volume: functions?

  • Elastic fibres

  • Fibroblasts

  • Blood vessels

  • Lymph vessels

  • Nerves
• what are the gingival connective tissue fibre groups called?

  - dentogingival fibres

  (around the teeth out into the gingival tissue)

  
  

  - alveolar crest fibres

  (from tooth area to alveolar crest)

  
  

  - circular fibres

  (form loops around the tooth)

  
  

  
  

  -> THESE FIBRE GROUPS WORK TOGETHER TO GIVE THE TISSUE ITS ROBUSTNESS (it is strong)

  
• What does clinically healthy soft & hard tissue surrounding an implant look like?

  
• What does the outer & inner zone surrounding the implant consist of?

  Inner zone:

  - contacting implant surface

  - 50-100um thick

  - Fibre-rich

  - 87% collagen

  - Few cells & vessels

  - Resembles scar tissue

  
  

  Outer zone:

  - Between bone & epithelium

  - Multidirectional fibres

  - Less (63%) collagen

  - More cells & vessels (but still less than gingiva)

  
• Where does gingival connective tissue get its blood supply from?

  - Partly from periodontal ligament

  - partly from supraperiosteal supply, extending on the outer aspect of the alveolar bone

  (and limited amount of blood supply from the bone itself)

  
• What do the blood vessels that supply the gingival connective tissue do?

  They come together and form a plexus of arterioles which exist beneath the crevicular and junctional epithelium

  - allows the delivery of a lot of blood and associated things (like white blood cells and antibodies) in order to deal with challenges around the neck of the tooth.

  
• How does peri-implant tissue blood supply differ from gingival connective tissue blood supply?

  Peri-implant tissues have no PDL blood supply, it all comes from the supra-alveolar connective tissue so there is no local vascular plexus to compensate so very limited blood supply