BDS Y1 2021 Gingival & Peri-implant Tissues HO PDF

BDS3 Periodontology Gingiva and Peri-implant tissues in health: anatomy and function Professor M Ide, 2021 Learning Objectives To provide introductory and complementary materials related to the relationships between periodontal diseases and systemic health, in conjunction with other resources availa...

BDS3 Periodontology Gingiva and Peri-implant tissues in health: anatomy and function Professor M Ide, 2021 Learning Objectives To provide introductory and complementary materials related to the relationships between periodontal diseases and systemic health, in conjunction with other resources available on KEATS. This content is mapped to General Dental Council Outcomes: 1.1.7 Describe relevant physiology and discuss its application to patient management 1.2 Comprehensive patient assessment 1.4 Diagnosis 1.5 Treatment planning 1.7 Patient management Titanium implant showing bone formation Basic anatomy of the implant restoration Abutment Fixture The periodontium is.... all the supporting structures of the tooth gingiva periodontal ligament cementum alveolar bone The peri-implant structure contains.... all the supporting structures of the implant peri-implant mucosa (like gingiva) NO periodontal ligament NO cementum alveolar bone Gingiva part of the oral mucosa epithelial covering, over connective tissue rapid epithelial turnover defined by tooth and mucogingival junction function: protection divided into three by position: – attached gingiva – free gingiva – crevicular and junctional areas Gingiva part of the oral mucosa epithelial covering, over connective tissue rapid epithelial turnover defined by tooth and mucogingival junction function: protection divided into two by structures: – Epithelial elements – Connective tissue elements NEW NAME SUPRACRESTAL TISSUE ATTACHMENT Attached gingiva pale pink, keratinised mucosa from mucogingival junction to free gingival groove firm and tightly bound onto bone stippled (but not always) Free Free Gingival groove Attached Mucogingival junction Attached gingiva pale pink, keratinised mucosa from mucogingival junction to free gingival groove firm and tightly bound onto bone stippled (but not always) Free Free gingival groove Attached gingiva Mucogingival junction Free gingiva from free gingival groove to tooth pale pink, keratinised, slightly loose and smooth Free Free Gingival groove Attached Mucogingival junction Interdental gingival tissue: the papilla Shape varies depending on shape and size of teeth Where teeth are relatively narrow from buccal to lingual, the papilla is narrow also It is pyramidal Interdental gingival tissue: the papilla 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 Contact point Gingival epithelium 0.2 to 0.3mm thick, with four layers stratum basale stratum spinosum stratum granulosum stratum corneum; – orthokeratinised – parakeratinised – incomplete keratinisation Gingival epithelium contains: melanocytes Langerhan’s cells – at most coronal part of juncnl 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 neighbouring keratinocytes, associated with the presence of nerve endings – more common with inflammation / damage – persist in the absence of teeth some T cells (mostly suppressor) Crevicular & Junctional Epithelium crevicular epithelium – keratinised 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) Junctional epithelium Completely replaced every 4 to 6 days Enamel Dentine 30 cells thick Hemidesmosomes Free gingival groove 3 cells thick Cementum Connective tissue BONE Junctional epithelium dynamics: rapid cell division Cells shed into crevice Enamel Junctional epithelium completely replaced in 4 to 6 days Dentine Very rapid cell division and migration: all cells look like basal cells Connective tissue Cementum BONE Junctional epithelium dynamics: permeability Cells and fluid from c.t. go into crevice Enamel Dentine Toxins and other bacterial products enter into connective tissue Connective tissue Cementum BONE Probing healthy junctional epithelium Enamel Dentine Cementum Connective tissue BONE Probing inflamed junctional Probe enters further epithelium Probing hurts! Site BLEEDS on probing Enamel Dentine Ulcerated junctional epithelium Inflamed connective tissue Cementum BONE Junctional epithelium around implants / abutments It exists! And variable length It attaches to titanium of: – Implant surface – Implant abutment surface Via: – by HEMIDESMOSOMES – Attached to basal lamina-like material on Ti surface Biologic seal A stable biological seal is obtained with: – 3mm supracrestal soft tissue attachment, 1mm CT and 2mm JE This happens with: – – – – – A range of systems (Abrahamsson et al 1996, Ericsson et al 1996, Hermann et al 1997) Following abutment connection and disconnection (Abrahamsson et al 1997) With or without loading (Cochran et al 1997) Different roughnesses (Abrahamsson et al 1998) Alterations in tissue thickness (Berglundh & Lindhe 1996) 2.0+ mm 0.7 mm Probe stops in CT Probe stops in JE Ericsson & Lindhe, 1993 & Lang et al, 1994 Difference is more profound if there is disease A weaker implant attachment? Or weaker JE? Use light forces when probing Palmer et al “Implants in Clinical Dentistry” 2nd Edn 2011 Soft tissue Biology: challenges and defences Leonhardt et al 1992 – Microbial colonisation and composition same as teeth in experimental gingivitis studies Seymour 1989, Tonetti et al 1995, Liljenberg et al 1997 – Inflammatory connective tissue infiltrates, of similar makeup, in healthy and inflamed samples, even if tissues look clinically healthy. – Concluded that there is a stable, gingivitis-like lesion even in health. This was also found to resemble inflammation around teeth with T-cell dominated infiltrate – Inflammatory barrier function would appear to exist Plaque formation around an implant Showing plaque formation around a natural tooth What stops the epithelial downgrowth? Granulation tissue / mature underlying CT controls epithelial downgrowth (Chehroudi et al 1992 & 1995 MacKenzie & Hill 1984), 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. 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 Gingival connective tissue fibre groups Enamel Dentine Dentogingival fibres BONE Gingival connective tissue fibre groups Enamel Dentine Alveolar crest fibres Dentoalveolar fibres BONE Gingival connective tissue fibre groups Enamel Dentine Circular fibres BONE Gingival connective tissue fibre groups Enamel BONE Dentine Clinically healthy soft tissue showing the gingival fibres Palmer et al “Implants in Clinical Dentistry” 2nd Edn 2011 Clinically healthy soft and hard tissue surrounding implant Apical termination of Junctional epithelium Abutment-fixture No dento gingival fibres present Outer zone, Between bone & epithelium Multidirectional fibres Less (63%) collagen More cells & vessels(but still less than gingiva) Inner zone, contacting implant surface, 50-100um thick Fibre-rich 87% collagen Few cells & vessels Resembles scar tissue Gingival connective tissue blood supply Enamel BONE Dentine Soft tissue biology: morphology III Berglundh et al 1991 – Peri-implant tissues have no PDL blood supply: it all comes from the supra-alveolar connective tissue Berglundh et al 1994 – No local vascular plexus to compensate: v limited blood supply To show blood vessels around implant -natural tooth Palmer et al “Implants in Clinical Dentistry” 2nd Edn 2011 Bone Various classifications: alveolar bone is that which makes up the alveolar ridge. It is tooth dependant and has two types of bone in it: Cortical bone Cancellous bone 65% mineralised by weight Palmer et al “Implants in Clinical Dentistry” 2nd Edn 2011 Reading Clinical Periodontology and Implant Dentistry 6th Edition: Lindhe et al Chapters 1 and 4 (would be also good to look at Chapters 2 and 5) Available as an e-book via KCL