INTRODUCTION

INTRODUCTION
TREATMENT OF PARTIALLY EDENTULOUS PATIENT
Causes of teeth loss

1- The main cause of teeth loss in young patient (about 35 years old) is usually caries attacking the enamel and dentine.
2- After the age of 35 years old the cause is usually related to periodontal diseases, due to progressive degeneration of the connective tissue of the periodontium and because of highly calcified teeth, bacteria may not be able to penetrate the tooth from above, what usually happens is that the bacteria goes downward causing mobility of teeth.
3- Another important cause for the loss of teeth is traumatic injuries, such as accidents, falls, violence, sports, etc.
4- Cysts and malignancies can cause destruction of the alveolar bone.
5- Radiation therapy of tumors often requires extraction of teeth in the path of the radiation as a precautionary measure.
6- Congenitally missing teeth; anodontia, or partial anodontia.
7- Failure to erupt (impacted teeth).







The partially edentulous arch is treated either with:
I- Removable partial denture is a prosthesis that replaces some teeth in a partially dentate arch, and can be removed from the mouth and replaced at will; it is either acrylic type or metallic type (cobalt/chrome).
Why do we have to make a removable partial denture?
1- For esthetic reason (fill the empty space and restore the facial proportion).
2- For proper function and occlusion (to be able to masticate food properly).
3- To prevent extrusion of opposing teeth (super-eruption), and migration or tilting of adjacent teeth.
4- To stimulate the underlying ridge and mucosa (prevent disuse atrophy).
5- To restore the phonetic problems associated with loss of teeth (especially anterior teeth).
6- For support facial musculature (proper balance of muscular relationship).
7- To restore the psychological status of the patient.
Components of removable partial denture
1. Major connectors
2. Minor connectors
3. Rests
4. Direct retainers
5. Stabilizing or reciprocal components (as parts of a clasp assembly)
6. Indirect retainers (if the prosthesis has distal extension bases)
7. One or more bases each support one to several replacement teeth.









Each component of a removable partial denture has a name that is descriptive of its function; are you think so?!





Indications of removable partial dentures
1- Distal extension situations (free end situation).
2- Long span tooth-bounded edentulous area.
3- Need for cross-arch (bilateral) stabilization.
4- Excessive loss of the residual ridge.
5- Unusually sound abutment teeth.
6- If the prognosis of remaining teeth are questionable.
7- After recent extraction.
8- Patient younger than 18 years old. WHY?!
9- Economic consideration.

DISADVANTAGES OF CLASP-RETAINED PARTIAL DENTURE
1. Strain on the abutment teeth often is caused by improper tooth preparation, clasp design, and/or loss of tissue support under distal extension partial denture bases.
2. Clasps can be unesthetic, particularly when they are placed on visible tooth surfaces.
3. Caries may develop beneath clasp components, especially if the patient fails to keep the prosthesis and the abutments clean.

II- Fixed partial denture (fixed bridge): A partial denture that lutes or otherwise securely retained to (natural teeth, tooth roots, and/or dental implant) that furnish the primary support and retention for the prosthesis.

Indications of fixed partial denture
1- Unilateral bounded edentulous short span.
2- Class IV Kennedy with normal loss of bone.
3- Modification area located anteriorly with class I and class II Kennedy classification for simplify the design of removable partial denture.








III- Dental implant therapy:
The dental implants are considered adjuncts in fixed and removable therapy. However, not all patients are candidates for dental implant therapy.


Contraindications for dental implant therapy:
1- Unfavorable regional anatomy.
2- Uncontrolled systemic disease.
3- Extreme surgical risk.
4- High-dose head and neck radiation.
TERMINOLOGY
Abutment is a tooth, a portion of a tooth, or a portion of an implant that serves to support and/or retain prosthesis.


Height of contour is defined as a line encircling a tooth, designating its greatest circumference at a selected position determined by a dental surveyor.
Undercut is that portion of a tooth that lies between the height of contour and the gingiva; when it is used in reference to other oral structures, undercut means the contour or cross section of a residual ridge or dental arch that would prevent the placement of a denture.

The angle of cervical convergence is an angle viewed between a vertical rod contacting an abutment tooth and the axial surface of the abutment cervical to the height of contour.

Guiding planes are two or more vertically parallel surfaces of abutment teeth shaped to direct prosthesis during insertion and removal.

Nesbitt denture is a unilateral removable partial denture design.

Path of insertion (path of placement) is the specific direction in which prosthesis is placed on the abutment teeth.
Bilateral bracing: to achieve good balance with removable denture, the work should extend to the other side of the arch.


What is the difference between Nesbit denture design and bilateral bracing denture?