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RETENTION AND STABILITY

RETENTION AND STABILITY. WHAT IS RETENTION?. IT IS THE ABILITY OF THE DENTURE TO RESIST VERTICAL TISSUE AWAY MOVEMENT. WHAT IS STABILITY?. IT IS THE QUALITY OF THE DENTURE TO BE FIRM AND STEADY, WHEN FUNCTIONAL FORCES ARE APPLIED. (RESISTANCE TO HORIZONTAL AND ROTATIONAL FORCES).

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RETENTION AND STABILITY

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  1. RETENTION AND STABILITY

  2. WHAT IS RETENTION? • IT IS THE ABILITY OF THE DENTURE TO RESIST VERTICAL TISSUE AWAY MOVEMENT.

  3. WHAT IS STABILITY? • IT IS THE QUALITY OF THE DENTURE TO BE FIRM AND STEADY, WHEN FUNCTIONAL FORCES ARE APPLIED. (RESISTANCE TO HORIZONTAL AND ROTATIONAL FORCES).

  4. FACTORS AFFECTING RETENTION.

  5. 1- ADHESION • PHYSICAL ATTRACTION BETWEEN UNLIKE MOLECULES.(DENTURE-SALIVA-MUCOSA)

  6. 2- COHESION • PHYSICAL ATTRACTION BETWEEN SIMILAR MOLECULES.(SALIVARY MOLECULES)

  7. 3-INTERFACIAL SURFACE TENSION(CAPILLARY ATTRACTION). • THE ATTRACTIVE FORCES BETWEEN SURFACE MOLECULES. • IT IS THE RESISTANCE TO SEPARATION POSSESED BY A FILM OF LIQUID BETWEEN 2 WELL ADAPTED SURFACES.

  8. 4- ATMOSPHERIC PRESSURE WHEN YOU SEAT THE DENTURE, AIR ESCAPES FROM UNDERNEATH THE FITTING SURFACE, FORMING A PARTIAL VACCUUM BETWEEN THE MUCOSA AND THE DENTURE, RESULTING IN TRAPPED REDUCED PRESSURE. ATMOSPHERIC PRESSURE IS LARGER, THUS SEATS THE DENTURE.

  9. 5- VISCOSITY. • THE RESISTANCE OF PART OF THE FLUID TO MOVE OVER ANOTHER. THE GREATER THE VICOSITY THE BETTER THE RETENTION.

  10. 6- GRAVITY. • IS CONSIDERED RETENTIVE TO THE LOWER DENTURE, AND DISPLACING TO THE UPPER DENTURE.

  11. ALL THE FACTORS WORKING TOGETHER.

  12. 1-SHAPE OF POLISHED SURFACE.

  13. 2-DENTURE FOUNDATION AREA

  14. 3-PRESENCE OF UNDERCUTS

  15. 4- DENTURE EXTENSION

  16. 5- INTIMATE CONTACT

  17. 1-RIDGE HEIGHT

  18. 2-SOFT PALATE ANATOMY

  19. 3- ARCH RELATIONSHIP

  20. 4- TONGUE SHAPE

  21. 5- VISCOSITY OF SALIVA

  22. 1- RIDGE AUGMENTATION

  23. 2- VESTIBULOPLASTY DEEPENING OF THE VESTIBULE TO GAIN RIDGE HEIGHT.

  24. 3- DENTAL IMPLANTS

  25. 1- ADHESIVES • CREAMS USED AS ADHESIVE IN THE FITTING SURFACE OF THE DENTURE.

  26. 2- MICRO SUCTION DISCS

  27. 3- DENTAL IMPLANTS

  28. SOME PATIENTS HAVE THE NEUROMUSCULAR AND PSYCOLOGICAL ABILITY, TO COPE AND USE THE DENTURE.

  29. RETENTION.

  30. FOR A DENTURE TO BE STABLE IT SHOULD BE RETENTIVE FIRST.!!!!!!!

  31. BALANCED OCCLUSION.

  32. HEIGHT OF OCCLUSAL PLANE.

  33. WHICH IS MORE STABLE!!!!!!!!!!!

  34. THE FURTHER AWAY THE OCCLUSAL PLANE , FROM THE RIDGE, THE LESS THE STABILITY.

  35. POSITION OF POSTERIOR TEETH.

  36. PLACING THE POSTERIOR TEETH SLIGHTLY LINGUAL TO THE CREST OF THE RIDGE, THE MORE STABLE. THE FORCES FALLING ON THE TEETH BECOMES MORE CENTRALISED. THIS IS KNOWN AS “LEVER BALANCE”.

  37. INCLINED PLANE ACTION

  38. PROPER RELEIF.

  39. FIRST ROCKING THEN MIDLINE FRACTURE.

  40. RIDGE FORM.

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