Spongy bone differs from compact bone in its arrangement of components. It has a porous structure made up of trabeculae that surround large marrow spaces. The trabeculae are oriented along lines of stress to withstand forces. There are two main types of spongy bone in the alveolar process - type 1 has regular horizontal trabeculae while type 2 has irregularly arranged delicate trabeculae. The architecture and number of trabeculae can vary depending on location and function. A decrease in function leads to less bone formation and thinner trabeculae.

1. GUIDED BY:
DR MOHSIN GHANCHI MDS
DR VIKAS BHASKHAR MDS
PRESENTED BY
ARBAZKHAN PATHAN
1ST YEAR BDS
ROLL NO 42

2. SEMINAR TOPIC
SPONGY BONE

3. INTRODUCTION
Spongy bone and compact bone have the same cells
and intercellular matrix, but differ in the arrangement of
components.
Spongy bone looks like a poorly organized tissue in contrast to
compact bone.
The bony substance consists of large slender spicules called
trabeculae.
The trabuculae are oriented along lines of stress to withstand the
forces applied to bone
The marrow space are large.
The trabeculae surround the marrow spaces from where they
derive their nutrition

5.  Spongy bone fills the area between the cortical
plates and the aleolar bone proper.
 The study of roentgenograms permits the
classification of the spongiosa of the alveolar
process into two main types

6. TPES OF THE SPONGY BONE
 The interdental and
interradicular
trabeculae are regular
and horizontal in a
ladderlike
arrangement.
 Both types show a
variation in thickness of
trabeculae and size of
marrow spaces
 It shows irreguralarly
arranged, numerous,
delicate interdental
and interradicular
trabeculae.
 Both types show a
variation in thickness of
trabeculae and size of
marrow spaces
TYPE 1 TYPE 2

7. TPES OF THE SPONGY BONE
 The architecture of
TYPE 1 is seen often in
the mandible and fits
well into the general
idea of the trajectory
pattern of spongy
bone
 TYPE 2, although
evidently fuctionally
satisfactory, lacks a
distict trajectory
pattern, which seems
to be compensated for
by the grater number of
trabeculae in any given
area.
TYPE 1 TYPE 2

8.  This arrangement is more common in the maxilla.
 From the apical part of the socket of lower molars,
trabeculae are sometimes seen radiating in a slightly
distal direction.
 These trabeculae are less prominent in the upper jaw
because of the proximity of the nasal cavity and the
maxillary sinus.
 The marrow spaces in the alveolar process may contain
haemopoietic marrow, but usually they contain fatty
marrow.
 In the condylar process, in the angle of the mandible, in
the maxillary tuberosity, and in other isolated foci,
hematopoietic cellular marrow is found.

9. CLINICAL CONSIDERATION
 The adaptation of bone to function is quantitative
as well as qualitative.
 Whereas, increase in functional forces leads to
formation of new bone, decreased function leads to
a decrese in the volume of bone.
 This can be observed in the supporting bone of
teeth that have lost their antagonists.
 Here the spongy bone around the alveolus shows
pronounced rarefaction.
 The bone trabeculae are less numerous and very
thin.
 The alveolar bone proper, however, is generally
well preserved because it continues to receive
some stimuli from the tension of the periodontal
tissues