Treatment of the grossly
resorbed mandibular ridge
Mohammad Al Sayed
22/4/2008
Gross mandibular atrophy:
Multifactorial biomechanical disease
resulting from a combination of anatomic,
metabolic, and mechanical determinant
varying with time from patient to patient in
an infinite number of combinations
Causes of mandibular atrophy and
alveolar bone loss:
1.Disuse atrophy.
2.Localized excessive pressure during incising and
unilateral function under a denture .
3.Periodontal bone loss before extraction of the
teeth.
4.Hyperparathyroidism.
5.Hypogondism.
6.Nutritional deficiencies and tissue resistance to
stress.
Clinical factors affecting bone resorption:
1.Anatomic factors
As the size and shape of the ridge, the ridge
relations, and the thickness and character of
mucosal covering
2.Metabolic factors
As age, Sex, nutrition, hormonal balance,
osteoporosis.
3.Functional factors
Frequency, direction, and amount of force
applied to bone.
4.Prosthetic factors
The type of denture base, the form and type of
teeth, the interocclusal distance and etc.
Problems as a result of extensive
changes in the facial and intraoral
tissues following the loss of permanent
dentition:
1.Morphological changes:
caused by either reduction in facial tissue
support due to resorption and
remodeling of the alveolar tissues.
2.Neuromuscular changes:
Resulting in indefinite occlusal positions
Facial morphological changes:
Changes in facial contour
Facial support
Rest facial height
Changes in facial muscles
Loss of support for the facial musculature
Muscle attachment
Changes in temporomandibular joints.
Intraoral morphological changes:
-Apparent loss of sulcus width and depth
-Muscle attachment
-Bony prominence
1. Sharp, spiny ridges
2. Uneven alveolar bone
3. Prominent mylohyoid and internal
oblique ridge.
4. Sharp mentalis eminence.
5.Enlarged genial tubercle.
The problem of the Mandibular
reduced residual ridge:
1.The average maxillary denture bearing area is 23cm²,
while the average mandibular denture bearing area is
only 12cm² and the mandible is susceptible to resorption
four times than the maxilla.
2. The surface contour of the resorbed ridge may prejudice
denture support and the superficial aspect of the
mylohyoid ridge may also be sharp, irregular, and
prominent which makes it unfavorable for support due to
painful loading of the covering mobile mucosa. In cases
of nerve dehiscence and ridge irregularity the master
cast should be relieved before construction of the
conventional denture base, where surgery is thought to
be inappropriate
3. Lack of retention and stability of the conventional
mandibular complete denture is commonly a complaint
of patient’s with reduced residual ridges because of the
unfavorable flat ridge from which does not provide any
resistance to anteroposterior or lateral movements.
Chronic mucosal irritation, discomfort, and the inability to
properly masticate are usually attendant history findings
as well.
4. As a result of the reduction of the residual ridge, the floor
of the mouth becomes relatively superficial.
5. Severe mandibular atrophy will result in the genial
tubercle and attached muscle becoming sufficiently
superficial to interfere with the lingual flange.
6. On the labial surface of the anterior region several
muscles show proximity to the crest of the ridge,
especially in badly resorbed ridges. These muscles
should not be impinged on because their action is nearly
at right angles to the flange.
7. The influence of the lip on lower denture stability
becomes more critical as resorption of the ridge
increases or as the patient becomes older. The
lip instead of being everted as in young
individual becomes thinner and inclines
backward into the mouth.
8. The large intermaxillary space that results from
excessive bone loss creates prosthesis
problems of esthetics related to loss of facial
support, occlusion, and the patient ability to
control the prosthesis.
9. These cases with grossly resorbed lower ridges
often have the crest of the ridge at the level of
the mental foramina, in which the nerves and
blood vessels are impinged on easily. This
causes paresthesia of the lower lip occurring
during mastication.
Treatment :
Ideal denture supporting ridge:
1.Adequate bone support for dentures.
2.Bone covered by adequate soft tissue.
3.No undercuts or hanging protuberances.
4.No sharp ridges.
5.Adequate buccal and lingual sulci.
6.No scar bands to prevent normal seating of a denture.
7.No muscle fibers or frenula to interfere with the periphery
of the prosthesis.
8.Satisfactory ridge relationships between the maxillae and
mandible.
9.No soft tissue folds, hypertrophies on the ridge or sulci.
10.A ridge free of neoplastic disease.
1. Preventive prosthodontics:
The greatest way to preserve the
mandibular anterior ridge comes from the
maintenance of one or more
endodontically treated roots and the
placement of an overdenture.
The advantages of the overdenture over the
conventional denture are:
The advantages of the overdenture
over the conventional denture are:
1.The denture bearing mucosa of the
residual ridges are spared abuse.
2.Maintenance of the alveolar bone.
3.Sensory feedback.
4.Minimal load thresholds.
5.Tactile sensitivity discrimination.
6.Masticatory performance.
7.Reduction of Psychological trauma.
2.Prosthodontic Treatment:
Many techniques have been developed to deal
with the problem of the compromised ridge.
1.Principle of mucostatics.
2.Using metal bases for snugness of fit of the
mandibular denture.
3.Implanting platinum cobalt magnets to increase
mandibular denture stability.
4.The flange technique which provided greater
denture-bearing surface for stabilization.
Proper coverage of all available denture-bearing
surface is fundamental to good denture
construction.
3.Surgical management:
1.Enlagement of denture-bearing areas
a)Vestibuloplasty.
b)Ridge augmentation.
2.Implants
a)Subperiosteal.
b)Transosseous
c)Endosseous.