Complete Denture Impression

Document Sample
Complete Denture Impression Powered By Docstoc
					                                                        Complete Denture
                                                          Impression



                                                                           What’s our job?
                                                           • Create a 3-Dimensional representation
                   Complete Denture                          of the patient’s tissues that the denture
                     Impression                              will be sitting on!




                                                   1                                                      2




Complete Denture                                        Complete Denture
  Impression                                              Impression



                   What’s our job?                                         What’s our job?
   • All tissues in the mouth ?                            • All tissues in the mouth ?
   • Hard - Soft                                           • Movable
       – Residual ridges - palate - any boney areas ?          – Soft palate - frenum - vestibules
       – Cheeks - mucosa - tongue - lips ?                     – Stretched - at rest - somewhere in between ?




                                                   3                                                      4




Complete Denture                                        Complete Denture
  Impression                                              Impression



                   What’s our job?                                         What’s our job?
   • The denture sits on the oral tissue.                  • What type of tissue would be capable of
   • When the denture contacts an opposing                   taking the force? Soft - Hard?
     prosthesis - or natural teeth - what
     happens to the tissue under the                       • Big surface area - or small?
     denture?
                                                           • Who cares - we’ll tell the patient to just
                                                             eat water!

                                                   5                                                      6




                                                                                                                1
Complete Denture                                                 Complete Denture
  Impression                                                       Impression


                                                                 Force directed to a large bearing area is more equally
                                                                 distributed and much less per sq. mm. than the same force
                                                                 directed against a smaller area.
  The amount of biting force an edentulous ridge will tolerate                      F                      F
                      is directly proportional
               to the amount of surface area covered




                                                            7                                                            8




Complete Denture                                                 Complete Denture
  Impression                                                       Impression



 Consequently, if we hope to assist a patient to achieve                 Are all the tissues the same ?
 maximum biting force and preserve the supporting
 structure over a longer period of time,

                                                                                        NO !
 The maximum amount of denture bearing
         area must be covered.                                    Macroscopically (palate, mandibular ridge)
                                                                  Microscopically (submucosa)


                                                            9                                                           10




Complete Denture                                                 Complete Denture
  Impression                                                       Impression




                                                           11                                                           12




                                                                                                                             2
Complete Denture                       Complete Denture
  Impression                             Impression




                                  13                                               14




Complete Denture                       Complete Denture
  Impression                             Impression                  Retromylohyoid
                   Buccal Shelf                                      Space - Lateral
                                                                     Throat Form




                                  15                                               16




Complete Denture                       Complete Denture
  Impression                             Impression




                                               Are these tissues all equal
                                               in their capability to
                                               support a denture under
                                               pressure?


                                                            NO !
                                  17                                               18




                                                                                        3
Complete Denture                                          Complete Denture
  Impression                                                Impression




                                                                 Primary stress bearing area
(1) Primary stress bearing area,
                                                             Best to resist vertical forces of occlusion

(2) Relief area                                              Base of cortical bone
                                                             Protected by firmly attached epithelial type tissue
(3) Peripheral seal area                                     Sufficient thickness to form a cushion against the forces
                                                             of occlusion.



                                                     19                                                              20




Complete Denture                                          Complete Denture
  Impression                                                Impression




                           Relief area                                       Peripheral seal area
                                                            Soft tissue border areas, which the periphery of the
   Pressure causes discomfort to the patient                denture must contact in order for the factors of retention
   Pressure causes instability of the denture base          to be effective.

                                                            The peripheral seal area is divided into two parts:

                                                            (1) Resistant peripheral area
                                                            (2) Nonresistant peripheral area
                                                     21                                                              22




Complete Denture                                          Complete Denture
  Impression
                                            Stress          Impression
                                                                                                           Relief
                                            Bearing                                                        Areas


Ridge Crest                                               Papilla
                                                          Zygomatica
Lateral Hard Palate                                       Suture


                   Ridge Crest
                   Buccal Shelf
                                                                               Mylohyoid Ridge
                   Retromolar Pads                                             Mental Foramen
                                                     23                                                              24




                                                                                                                          4
Complete Denture                                Complete Denture
  Impression       Resistant Peripheral Areas     Impression                        Resistant Peripheral Areas




                                        25                                                               26




Complete Denture                                Complete Denture
  Impression       Resistant Peripheral Areas     Impression                        Resistant Peripheral Areas




                                        27                                                               28




Complete Denture                                Complete Denture
  Impression       Resistant Peripheral Areas     Impression                        Resistant Peripheral Areas

                                                                                    Hamular Process of the
                                                                                    Medial Pterygoid Plate




                                                Lip
                                                                                  Tuberosity
                                                              Mucosa   Alveolar      Hamular Notch
                                                                       Bone


                                                                                           Pterygomandibular
                                                                                                 Raphe
                                        29                                                               30




                                                                                                                 5
Complete Denture                                          Complete Denture
  Impression                 Resistant Peripheral Areas     Impression                               Non-Resistant Peripheral Areas



     It is imperative that all maxillary denture
     bases terminate in this notch.


    Bases short of the hamular notch will
    end on the thin - nonflexible - tissue
    of the tuberosity and will
    consequently lack retention.
                                                  31                                                                                   32




Complete Denture                                          Complete Denture
  Impression            Non-Resistant Peripheral Areas      Impression                               Non-Resistant Peripheral Areas




                                                  33                                                                                   34




Complete Denture                                          Complete Denture
  Impression            Non-Resistant Peripheral Areas      Impression




                                                                                                    Hard Palate
                                                                                                               Posterior Limit
                                                                                         Alveolar
                                                                                                               of Hard Palate
                                                                                         Process
                                                                                                                         Soft Palate




                                                                    Lip
                                                                             Labial          Mucosa                Vibrating Line
                                                                             Vestibule



                                                  35                                                                                   36




                                                                                                                                            6
Complete Denture                                                       Complete Denture
  Impression                     Non-Resistant Peripheral Areas          Impression                  Non-Resistant Peripheral Areas

                                                                            Classifications of Throat Form


                                                                          CLASS I
                                                                          6 - 8 mm of soft palate extends beyond the hard
                                                                          palate before dropping downward or registering
                                                                          movement when the patient speaks
                                                                          CLASS II
                                                                          3 - 4 mm
                                                                          CLASS III
                                                                          0 mm
                                                                 37                                                                  38




Complete Denture                                                       Complete Denture
  Impression                     Non-Resistant Peripheral Areas          Impression                          Peripheral Areas


                                                                                                        Resistant Peripheral Areas
                                       CLASS III                                                        1.Labial frenum
                                                                                                        2.Lingual frenum
                                                                                                        3.Buccal frenum
                                                                                                        4.Distobuccal arch
                                                                                                        5.Pterygomandibular raphe
                                                                                                        6.Retromylohyoid curtain
                                                                                                        7.Alveolo-lingual fold
   Lip                                Vibrating Line
                                                                                                        Nonresistant border areas

                                                                                                        8.Labial vestibule
    For the Class III throat form where the movement of the soft
                                                                                                        9.Buccal vestibule
    palate starts immediately at the posterior border of the hard
    palate, problems may be encountered in establishing a good
    seal.                                                      39                                                                    40




Complete Denture                                                       Complete Denture
  Impression                             4.Distobuccal arch              Impression                           4.Distobuccal arch
                                         5.Pterygomandibular raphe                                            5.Pterygomandibular raphe
                                         6.Retromylohyoid curtain                                             6.Retromylohyoid curtain
                                         7.Alveolo-lingual fold                                               7.Alveolo-lingual fold



                                                                                 Posterior Limit of the Lower Denture

                                                                         The pterygomandibular raphe forms the attachment
                                                                         of the superior constrictor to the buccinator muscle.
The distobuccal arch is under the control of the masseter muscle         It runs from the posterior border of the hamular
which has its origin at the zygomatic arch. It is attached to the        notch downward to the apex of the retromolar pad.
lateral border of the mandibular ramus. Dentures, which are              The raphe stretches when the mouth is opened,
overextended in this area, interfere with the contraction of the         pulling the distal edge of the pad upward. Dentures
masseter muscle, which pushes forward against the buccinator
                                                                         should not extend beyond this line of movement.
muscle creating discomfort when the patient closes. The
distobuccal arch flange, if properly shaped, will usually run at a
45-degree angle from the mesiobuccal arch to the apex of the
                                                                  41                                                                 42
retromolar pad.




                                                                                                                                          7
Complete Denture                                                               Complete Denture
  Impression                                 4.Distobuccal arch                  Impression                                 4.Distobuccal arch
                                             5.Pterygomandibular raphe                                                      5.Pterygomandibular raphe
                                             6.Retromylohyoid curtain                                                       6.Retromylohyoid curtain
                                             7.Alveolo-lingual fold                                                         7.Alveolo-lingual fold
     Distolingual Extension of the Lower Denture

 The retromylohyoid curtain lies lingual and inferior to the retromolar
 pad. It is formed by the mucous membrane of the lingual lateral border
 of the mandible and is attached to the posterior sides of the tongue. Its
 size, shape, and position vary with tongue movements. The curtain
 moves upward and backward as the tongue moves upward and
 backward in swallowing. It moves upward and forward during
 protrusive and lateral movements of the tongue. The amount of
                                                                                 The amount of posterior lingual extension of the base is controlled by the
 upward and forward movement of the curtain during these protrusive
                                                                                 movement of this curtain. Overextension of the denture flange results in
 and lateral movements is referred to as the lateral throat form of the
                                                                                 the patient complaining of a sore throat or unseating of the denture.
 mandibular denture. If this movement is slight and the angle formed by
                                                                                 Underextension handicaps the tongue in controlling the lower denture
 the posterior part of the curtain to the retromolar pad is approximately
                                                                                 and allows ingress of food under the denture. This tissue offers very little
 90 degrees, it is a Class I throat form. Extreme forward movement of
                                                                                 resistance to pressure so the operator must be careful not to create a
 the curtain resulting in an angle of 45 degrees or less in Class III throat
                                                                         43      false undercut by displacing it when making the impression.          44
 form and in between the two is Class II throat from




Complete Denture                                                               Complete Denture
  Impression                                                                     Impression




                                                                        45                                                                             46




Complete Denture                                                               Complete Denture
  Impression                                                                     Impression




                                                                        47                                                                             48




                                                                                                                                                                8
Complete Denture
  Impression                               4.Distobuccal arch
                                                                             The mylohyoid muscle originates at the mylohyoid ridge.
                                           5.Pterygomandibular raphe
                                           6.Retromylohyoid curtain          Its fibers pass downward and inward and are inserted
                                           7.Alveolo-lingual fold            posteriorly to the hyoid bone and anteriorly, with its
                                                                             neighbor, form the opposite side at the median raphe.
         Lingual Extension of the Denture

 The alveololingual fold is formed by the mucous
 membrane's attachment to the lingual side of the mandible
 laterally and its attachment to the lateral borders of the
 tongue lingually. Because of this attachment, the fold is
 elevated when the tongue is protruded or when the tongue
 is moved laterally. Supporting the mucous membrane and
 forming the floor of the mouth is the mylohyoid muscle
 posteriorly and the sublingual gland anteriorly.


                                                                        49                                                                                50




Complete Denture                                                             Complete Denture
  Impression                                                                   Impression
                                   Mylohyoid
                   Buccinator
                                                                              The mylohyoid muscle, along with the mucous membrane can be
                                                   3rd Molar Region           easily displaced by pressure. Overextended bases in this lingual
                    Mandible
                                                                              area will cause the denture to either lift out of position or result in a
                                                                              denture injury.
                                                                              For this reason it is necessary that an accurate non!pressure
                                                   1st Molar Region           impression be obtained of the functional range of the fold.




                                                   Premolar Region




                                                   Canine Region
                                                                        51                                                                                52




Complete Denture
  Impression
                                                                                                 What’s our job?
  Below the sublingual gland are the mylohyoid muscles, and when
  this muscle raise upon swallowing it forces the gland and the floor
  of the mouth upward. Therefore, this is a resistant border area,
  and extension of the base is limited to the functional position of
  these tissues.




                                                                        53                                                                                54




                                                                                                                                                               9