Introduction in Prosthodontics (dental prosthetics)

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Introduction in Prosthodontics (dental
prosthetics)

• Dr. Waseem Bahjat Mushtaha
• Specialized in prosthodontics

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Introduction

• Prosthesis an artificial appliance which replace
  lost or congenitally missing tissue. Some
  prosthesis restore both function and appearance
  of tissue they replace other merely restore one
  of these factors.

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• Prosthetics is the art and science of designing
  and fitting artificial substitutly to replace
  lost or missing tissue.
• Prosthodontics (dental prosthetics)
• Is the branch of dental art and science which
  with the replacement of missing teeth and oral
  tissue to restore and maintain oral form,
  function, appearance, phonetics and health.

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• Complete denture prosthodontics
• involves an artificial replacement of the lost
  natural dentition and associated structures of
  the maxilla and mandible for patient who has lost
  all their remaining natural teeth.

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Function of complete denture

• 1- Mastication chew food for swallowing and
  digestion.
• 2- Speech (phonetics) the teeth either natural
  or artificial assist the tongue and
  lips to form some of the sounds of
  speech.
• 3- Appearance (aesthetic) is influence by the
  shape of jaws together with the
  position and occlusal relation ship of
  the teeth.
• 4- Health of the alveolar bone and the tempro-
  mandibular joints (T.M.J).

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Complete dentures have three structures

• 1- The fitting surface.
• 2- The occlusal surface.
• 3- The polished surface.

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Anatomy and physiology in relation to complete
denture

• I- oral mucosa membrane (tissue compression)
• 1- The bone of the upper and lower edentulous
  jaws are covered with a soft tissues
  and the oral cavity is lined with soft
  tissue known as mucosa membrane.
• 2- This mucosa membrane is composed of two
  layer mucosa and sub mucosa.
• 3- Mucosa consists of stratified squamous
  epithelium.

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• 4- The thickness and consistency of the sub
  mucosa are largely responsible for the
  support denture.
• 5- In the edentulous patient the crest of
  residual alveolar ridge hard palate has
  masticatory mucosa have firmly attached
  to the supporting bone.
• 6- The sub mucosa in the region in the median
  palatine suture of the maxillary bone is
  extremely thin so will become inflamed when
  wearing denture.

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II- the alveolar ridges

• 1) The residual ridge consists of
• 1- Denture bearing mucosa.
• 2- Sub mucosa
• 3- Periostem
• 4- Under laying residual alveolar bone.

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Types of alveolar ridges and palate formation

• I- upper ridges
• 1- well developed (upper ridge) but not
  abnormally thick ridges and palate with a
  moderate vault.
• 2- Flat v- shaped palate usually associated
  with bulky ridge.
• 3- Flat palate with small ridge and shallow.
• 4- Ridge exhibiting gross under cut area.

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II- lower ridge

• 1- Broad and well developed lower ridges.
• 2- Ridges exhibiting under cut areas.
• 3- Well developed but narrow or knife
  edged ridges.
• 4- Flat ridge.

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Anatomical land marks of complete dentures

• I- INTRA ORAL ANATOMICAL LAND MARK
• II- EXTRA ORAL LANDMARK

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Upper denture
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I- INTRA ORAL ANATOMICAL LAND MARK

• 1- Stress bearing (supporting area).
• 2- Peripheral or limiting (sealing) areas

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Incisive papilla
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I- supporting structure

• 1- Incisive papilla
• 1) It is the elevation of the tissue that covers
  the incisive foramens (the opening of
  the nasopalatine canal which, carry the
  nasopalatine vessels and nerves).
• 2) Location, on the median line behind and
  between the central incisors.
• 3) In old edentulous mouth it is located on the
  center of the ridge due to resorption.
• 4) It may require relief in the finished denture
  base to prevent irritation of the
  nasopalatine nerve.

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2- Rugae area
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2- Rugae area

• 1) The rugae are irregular shaped rolls of soft
  tissue.
• 2) Location, lie in the anterior part of the hard
  palate.
• 3) It is considered a secondary stress- bearing
  area for the upper complete denture.
• 4) With the natural dentitions, it assists in
  formation of sounds like the letter
  s.

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Residual alveolar ridge
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3- Residual alveolar ridge

• 1) The residual alveolar ridge and most of the
  hard palate are considered the major or
  primary stress bearing area in the upper jaw.
• 2) The crest of the residual ridge is covered
  with layer of fibrous
  connective tissue which is most favorable for
  supporting the denture because of
  it is firmness and position.
• 3) The crest of ridge is described as a primary
  stress-bearing area and most
  tolerated to resisting the denture movement and
  resulting irritation

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Median palatine raphe
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4- Median palatine raphe

• 1) It is median suture formed by the union of
  the palatine processes of maxilla and
  horizontal plates of the palatine bones.
• 2) It is covered with mucosa membrane and
  little sub mucosa tissue.
• 3) This area may require selective relief with
  in denture base.

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5- The tuberosities
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5- The tuberosities

• 1) The posterior part of the maxillary alveolar
  ridge forms prominence called the tuberosity.
• 2) It is usually a bulbous extension of the
  residual ridge in the second and third molar
  region.
• 3) Terminating hamular notch.

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• 4) Large tuberosities bounded by deep salci
  offer very satisfactory denture
• 5) Tuberosities exhibiting gross undercuts
  may require surgical treatment.
• 6) They are identified in the finished denture
  by the tubercular fossa.

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6- Fovea palatinae
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6- Fovea palatinae

• 1) These are indentations near the midline of
  the palate formed.
• 2) They are close to the vibrating line and
  always in soft tissue.
• 3) Which makes an ideal guide for the ending
  of the posterior border of the denture

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7- Tours palatinus
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7- Tours palatinus

• 1) At the junction of the palatine process of the
  maxillary bone, in the midline or on
  each side lateral to the midline.
• 2) A bony projection is some times observed.
• 3) It varies in size and form.
• 4) If it is too large it should be surgically
  removed.
• 5) If it is small the denture base should be
  relieved of that area.

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Border structures that limit the periphery of the
upper denture (limiting structure)

• 1- The maxillary labial frenum
• 1) It is a fibrous bond covered by mucosa
  membrane that extends from the
  labial aspect of the residual alveolar ridge
  to the lip.
• 2) It has no muscle fiber and has no action of it
  is own.
• 3) The labial in the labial flange of the denture
  must be just wide and deep enough to allow
  the frenum to pass through it
  without manipulation of the lip.

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The maxillary labial frenum
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2- Labial vestibule and labial flange

• 1) The labial flange of maxillary denture
  occupies a potential space bounded by labial
  aspect of the residual alveolar ridge, the
  muco-labial alveolar fold, and the orbicularis
  oris muscle.
• 2) The length of this flange should not extend
  beyond the normal drape of the
  muco-labial fold.
• 3) The thickness of the flange depends up on the
  degree of alveolar resorption.
• 4) The denture border area between the labial
  frenum and the buccal frenum is known as
  the maxillary labial flange.

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2- Labial vestibule and labial flange
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3- Buccal frenum

• 1) It is a some times a single fold of mucosa
  membrane, sometimes double and in
  some mouths, broad and fan shaped.
• 2) The buccal notch in the denture must be broad
  enough to allow the movement of the
  buccal frenum.
• 3) Inadequate provision for the buccal frenum or
  excess thickness of the flange distal to
  the buccal notch can cause
  dislodgment of the denture when the
  cheeks are moved posterioly as in abroad
  smile.

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Buccal frenum
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4- Buccal vestibule

• 1) It is extended from the buccal frenum to the
  hamular notch.
• 2) It houses the buccal flange of the denture.
• 3) This space between the ridge and cheek.
• 4) The buccal flange of maxillary denture should
  fill but not over fill it.
• 5) The thickness of the distal end of the buccal
  flange of the denture must be adjusted to
  accommodate the ramus and cronoid process and
  masseter muscle as they function.
• The distal end of the buccal flange must not be
  too thick because the ramus will push the denture
  out of the place during opening or lateral
  movement of mandible.

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Buccal vestibule
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5- Pterygomaxillary (hamular) notch

• 1) It is formed by the pterygoid process of
  sphenoid bone and the posterior end of
  maxilla, back to the tuberosity.
• 2) It is used as boundary of the posterior
  border of maxillary denture.
• 3) It is important for sealing.

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Pterygomaxillary (hamular) notch
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6- Vibrating line of the palate

• 1) It is an imaginary line drawn across the
  posterior part of the palate that marks the
  beginning of motion in the soft palate
  when the patients say "ah".
• 2) It extends from one pterygomaxillary notch
  to other.
• 3) It is not the junction between hard and soft
  palate. It is always in soft palate.

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Vibrating line of the palate
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7- Posterior palatal border (Potsdam)

• 1) The distal edge of the maxillary denture base
  terminates in the posterior palatal
  seal area.
• 2) This denture edge generally ends at or before
  the vibrating line.
• 3) The seal of this border must be situated in
  the region of compressible tissue just
  distal to the hard palate. (But it must be
  anterior to the vibrating line).

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Posterior palatal border (Potsdam)
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8- The soft palate

• Patient may be broadly divided in to classes with
  regard to non mobile area
• 1) Those whose palates exhibit movement at
  the junction of the hard palate and soft
  palate.
• 2) Those whose soft palates move some
  distance behind the junction.

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• The width of the area available for the posterior
  palatal seal will depend up on the curvature of
  the soft palate. There are three classes of
  curvature of soft palate
• Glass I the soft palate has a gentle curvature
  and allows for
  abroad posterior palatal seal area.
• Glass II the soft palate has a medium curvature
  and allow for a medium width of the
  posterior palatal seal area.
• Glass III the soft palate has a sharp and abrupt
  curvature
  and allows for a narrow
  posterior palatal seal area.

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The soft palate
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II- lower denture

• Intra oral structures that support the lower
  denture (supporting structure)
• 1) Residual alveolar ridge
• The crest of the residual alveolar ridge is
  covered by fibrous connective tissue, but in many
  mouths the under lying bone is and without a good
  bony plate covering it.

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2) External oblique ridge

• 1- It is a bony ridge.
• 2- It begins at the junction of alveolar ridge
  and the ramus of the mandible.
• 3- It descends obliquely downward and forward
  across the outer surface of the body.
• 4- It fades out at appoint nearly opposite the
  mesial surface of the first molar.
• 5- It is recorded in the impression and wed as
  appoint reference in the impression
  making.

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3) The buccal shelf of bone

• 1- Location it is the area between the
  mandibular buccal frenum and the anterior
  edge of masseter
• 2- This area is bonded
• - Medially the crest of residual ridge.
• - Anteriorly buccal frenum.
• - Laterally external oblique ridge.
• - Distally retromolar pad.
• 3- The buccal shelf offers excellent resistance
  to forces (primary stress bearing area
  of the mandibular denture) due to
• - It is at right angles to the vertical occlusal
  forces.
• - Very wide.
• - It is covered with good smooth cortical bone.

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• 4) Retromolar region and pad
• 1- It is a triangular soft pad of tissue at the
  distal end of the lower ridge.
• 2- It must be covered by denture base.
• 3- Sealing the retromolar pad aids in the
  stability of the denture.
• 5) Mylohyoid ridge (internal oblique ridge)
• 1- It descends obliquely down and across the
  inner surface of the body of the
  mandible.
• 2- It begins in the region of the third molar and
  continuous downwards and forwards
  to the lower border of the mandible
  near the midline.

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6) Mental foramen

• 1- location on the buccal surface of the
  mandible in the premolar region.
• 2- Mental nerves and vessels pass thought it.
• 3- In cases of extreme ridge resorption it is
  usually located on the crest of the ridge.
• 4- Pressure from the denture may cause pain
  and numbness (require relief in finished
  denture)

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7) Torus mandibularis

• 1- It is bony projection.
• 2- Sometimes found on the lingual surface in
  the premolar region.
• 3- If it is too large it will require surgical
  removal.
• 4- If small, the denture should be relived in
  that area.

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Border structures that limit the periphery of the
lower denture (limiting structures)

• 1) The mandibular labial frenum
• 1- It is a band of fibrous connective tissue that
  helps to attach the orbicularis oris
  (muscle of the lip)
• 2- It is accommodated by a groove in the
  mandibular denture.

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• 2) The mandibular vestibule and labial flange
• The part of the denture that extends
  between the labial notch and the buccal
  notch is called the mandibular labial
  flange.
• 3) Buccal frenum
• 1- This attachment connects with continuous
  band through the corner of the mouth
  And on up to the buccal frenum of the
  maxilla.

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• 4) Buccal vestibule and buccal flange
• 1- It extends from the buccal frenum posteriorly
  to the out side back corner of the
  retromolar pad and from the crest of the
  residual alveolar ridge to the cheek.
• 2- It houses the buccal flange of the mandibular
  denture.
• 5) Masseter muscle influence area
• 1- The distobuccal corner of the mandibular
  denture must coverage rapidly to
  avoid displacement due to
  contracting pressure of the masseter muscle.
  
• (Whose anterior fibers pass out side buccinator
  in this region)

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• 6) Lingual flange area (alveolingual sulcus)
• The distal extention of the lingual flange lies
  in the lingual pouch.
• Lingual pouch (retromylohoid fossa)
• Is the area bounded medially by the tongue,
  laterally by the mandible, posteriorlly by the
  palatoglussus arch, which is formed in part by
  the palatoglossus muscle and in part by the
  lingual extention of the superior constructor
  muscle and anteriorly by the posterior 3 mm of
  the mylohoid muscle. Forward on the lingual
  extension, the area is influence by the mylohoid
  muscle, which attaches to the mylohoid ridge. The
  flange extends below and medially from the
  mylohoid ridge to fill the fold formed by the
  tongue and the tissue of the floor of the mouth.
• This means that the inner surface of this flange
  does not rest on mucosa membrane over bone, but
  on soft tissue. It leaves the bony attachment at
  the mylohoid ridge, and the flange extends out
  under the tongue to fill the fold. The forward
  part of the flange area of this region over the
  sublingual stand usually is shallow because of
  the movement of the tissue that is controlled
  indirectly by the mylohoid muscle.

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7) Lingual frenum

• 1- It is anterior attachment of the tongue.
• 2- Very resistant and active and often wide.
• 3- It needs complete functional trimming to
  avoid having the attachment displace the
  lower denture.

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II- EXTRA ORAL LANDMARK
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II- EXTRA ORAL LANDMARK

• 1) Inter papillary line
• This is an imaginary line running between the two
  pupils of the pupils of the eye when the patient
  is looking straight forward.
• 2) ala-tragus line
• This is an imaginary line running from the
  inferior border of the ala of the nose to the
  superior border of the tragus of the ear
  (camper's line).
• (Establishing the posterior occlusal plane of the
  artificial teeth).

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• 3) Canthus tragus line
• This is an imaginary line running from the outer
  canthus of the eye to the superior border of the
  ear.
• (Aid in locating the position of the condyles).
• 4) naso-labial sulcus
• 1- This is a depression that extends downward and
  laterally to the corner of the mouth.
• 2- It becomes deeper and more prominent with
  aging and due to loss of teeth.
• 3- It should be restored to normal contour by
  proper positioning of the anterior teeth and
  proper contouring of the upper labial flange.

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• 5) Vermilion border
• 1- It is the transitional epithelium between the
  mucosa membrane of the lip and skin.
• 2- The amount of the vermilion border showing
  depends on
• 1. Bulk of orbicularis oris muscle.
• 2- The amount of labial alveolar bone.
• 3- Alignment of teeth.
• 3- Following the loss of teeth and resorption of
  bone
• There is a reduction in the amount of vermilion
  border showing.
• It should be restored with dentures.

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• 6) Philtrum
• 1- It is a diamond shaped area between the base
  of the nose and center of the upper lip.
• 2- It becomes distorted with the loss of teeth
  and becomes flat, it should be restore
  by normal shape with denture
• 7) Modiolus
• 1- This is located at the confluence (meeting
  place) of the buccinator and other facial
  muscles.
• 2- The arch form of maxillary teeth support it
• 3- With the loss of teeth it droops giving the
  characteristic look of the edentulous person
  (sunken cheek)

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• 8) Mento labial sulcus
• 1- It runs from side to side horizontally
  between lower lip and chin
• 2- Its curvature indicates the maxillo-mandibular
  relation.

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• a- Angle class I the curvature is gentle with
  an obtus angle (normal anterioposterior
  relation)
• b- Angle class II this represents a retruded
  mandibular position
• The mento-labial sulcus present an acute angle
  when the lower lip is folded toward the chin
• C-angle III this is a protruded maxillo-
  mandibular relation when the mento-
  labial sulcus may an angle of almost 180º

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