describes the biology of bone in physiologic condition, about bone remodeling, bone resorption in complete denture, combination syndrome, bone resorption in immediate denture and overdenture

1. BIOLOGY OF BONE ,AND ITS CONSIDERATION IN
COMPLETE DENTURES, REMOVABLE PARTIAL
DENTURES , OVERDENTURES
Presented by – Piyali Bhattacharya
1st year PGT,
HIDSAR

2. INTRODUCTION:
• Bone is a connective tissue.
Function:
1. Provides shape and support to our body
2. Provides site of attachment for tendon and muscles
which helps in locomotion
3. Acts as a storage site for minerals provides the
medium (marrow) for development and storage of
blood cells.

3. Classification of Bone:
Based on development
Enochondral bones
Intramembranous bones
Based on microscopic
structure
Compact/Lamellar bones
Cancellous bones
Woven bones
Based on shapes
Long bones
Short bones
Flat bones
Irregular bones
Sesamoid bones

4. COMPOSITION OF BONE
1. Inorganic substance :
• Hydroxyapatite crystals, Calcium phosphate, ions of citrate ,
magnesium, sodium, fluoride..
2. Organic substances :
• Organic matrix is called Osteoid, made up of collagen (type1
mostly) and noncollageous proteins (bone sialoproteins,
osteonectin, osteopontin ).

5. • Bone tissue is composed of cells , fibers and ground
substances.
Bony Trabeculae
Osteocyte
Osteoblast
Osteoclast
Histological Composition of Bone

6. • All bones have an outer sheet of Compact
Bone and a central medullary cavity
filled with red or yellow marrow in living
bone.
• This marrow cavity shows a network of
bony trabeculae known asTrabecular
Bone/ Spongy/ cancellous bone.
• Outer fibrocollagen layer
(Periosteum) has two layers :
Outer fibrous and inner layer with rich
vascular supply.
• Between compact and spongy bone is a
thin layer of endosteum .
• At periosteal and endosteal layer,
there are concentric lamellae around
central vascular canal. The lamellae and
Havershian canal together called
Osteon / havershian system.
• Havershian canals are connected to
each other by Volkmann’s canals.
Structure Of Bone

9. SRTUCTURE OF ALVEOLAR BONE:
1. Alveolar Bone Proper :
Consists of
-lamellated bone and
-bundle bone.
2. Supporting Alveolar Bone :
-cortical plates
- spongy bone.

11. BONE REMODELLING
• Bone turnover rate is 30%-100% per year in young growing
children.
• The turnover rate of trabecular bone and endosteal layer is
much higher than cortical bone.

12. • The osteoclasts tunnel into surface of bone , which lasts for
three weeks.
• In havarsian canals, closest to the surface, osteoclasts travel
along a vessel, resorb the haversian lamellae and
circumferential lamellae known as cutting/resorption cone
• After sometime, osteoclasts are replaced by osteoblasts
which lays down new set of haversian lamellae encircling a
vessel.
• The entire area of osteon is called Filling cone.
[The haversian canal can be distinguished from volkmann’s
canal by presence of osteoclasts ]

14. Clinical Significance

15. RESORPTION PATTERN AFTER EXTRACTION
Resorption pattern of alveolar bone :
• The labial aspect of alveolar crest is the principal site of
resorption, which reduces first in width then in height.
Resorption pattern In maxilla Resorption pattern In mandible

16. • The process of bone remodelling is important in areas of
thin cortical bone i.e.; buccal and labial parts of maxilla
and lingual part of mandible.
• During the first year of teeth extraction, the residual ridge
reduction in midsagittal plane is about 2-3 mm for maxilla
and 4-5 mm in mandible.
• After healing of residual ridge, the remodelling process
continues but with reduced intensity. In mandible, the annual
rate of reduction in ridge height is 0.1 to 0.2 mm and about
four times less in maxilla.
RESORPTION IN COMPLETE DENTURE WEARERS

17. Some of the proposed factors of
residual ridge reduction

18. Resorption pattern in
complete denture
wearers

19. 1. In the lower jaw there was an apparent correlation between
the use of dentures and lesser mean vertical and labio lingual
dimensions of the ridges.
2. In the upper jaw the same relationship was apparent in
regard to the labio-lingual dimension of the ridges, but not the
vertical
Campbell RL. A comparative study of the resorption of the alveolar ridges in denture-wearers and non-denture-
wearers. J Am Dent Assoc 1960;60:143-53.

20. RESORPTION PATTERN IN COMPLETE DENTURE
WEARERS
• A study of the morphologic changes in the facial skeleton
during seven years of complete denture wear revealed that
the decrease in facial height was mainly due to a
pronounced reduction of the mandibular ridge and a
consequent forward upward rotation of the mandible.
• The reduction of the residual alveolar ridges was most rapid
during the first year of denture wear.
• study of the positional changes of the complete dentures due
to the alveolar resorption revealed particularly marked
changes of the lower denture.
Antje Tallgren ,The continuing reduction of the residual alvealar ridges in complete denture wearers: A mixed-
longitudinal study covering 25 years, J. Prosthet. Dent., February, 1972, vol 27, no.2

21. • In addition to a pronounced settling on the basal seat, the
lower denture displayed also a forward slide on the
residual ridge.
• The upward rotation of the mandible and the forward slide of
the lower denture led to a reduction in the horizontal
overlap, and in some patients, even to a horizontal overlap
of the lower teeth over the upper ones.
Antje Tallgren ,The continuing reduction of the residual alvealar ridges in complete denture wearers: A mixed-
longitudinal study covering 25 years, J. Prosthet. Dent., February, 1972, vol 27, no.2

22. Antje Tallgren ,The continuing reduction of the residual alvealar ridges in complete denture wearers: A mixed-
longitudinal study covering 25 years, J. Prosthet. Dent., February, 1972, vol 27, no.2

23.  The alveolar bone in the posterior part of the mandible is
slightly more at risk to resorption , with an average vertical
bone loss over a 5-year period of 1.5 mm in the incisor
region, 1.6 mm in the premolar region, and 1.6 mm for the
molar region.
 The difference in occlusal forces, between the anterior region
where lighter forces for incising food occurs compared with
the posterior region where heavier forces are required for
trituration, may be responsible.
Wyatt, The effect of prosthodontic treatment on alveolar bone loss: A review of the
literature, The Journal Of Prosthetic Dentistry, Volume 80 Number 3

24. CHANGES CAUSED BY WEARING MANDIBULAR
REMOVABLE PARTIAL DENTURE OPPOSING A MAXILLARY
COMPLETE DENTURE
• The anterior part of maxillae is the weakest part of the
upper arch to resist stress.
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

25. • When the mandibular anterior teeth occlude anterior to the
basal support, trauma
is inevitable.
• There are five probable
changes which may
constitute a syndrome:
1. Loss of bone from
anterior maxilla,
2. Overgrowth of tuberosities,
3. Papillary hyperplasia in hard palate
4. Extrusion of lower anterior teeth
5. Loss of bone under partial denture bases
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

26. • The early loss of bone from the anterior part of the maxillary
jaw is the key to the other changes of the combination
syndrome.
• With the anterior loss of bone, a flabby hyperplastic
connective tissue makes up the anterior part of the ridge. this
hyperplastic tissue does not support the denture base and
usually it folds forward, forming a characteristic deep fold or
crease
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

27. 1.Bone and ridge
height are lost
anteriorly,
2. Posterior residual ridge
becomes larger with the
development of enlarged
tuberosities
3.The occlusal plane
migrates up in the
anterior region and down
in the back
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

28. Excessive bony resorption
under the lower
removable partial denture
bases occurs
to permit these changes
Natural lower anterior
teeth migrate upward, the
anterior teeth on the
complete denture
disappear under the
patient’s lip
Both dentures migrate
downward in the posterior
region.
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

29. PAPILLARY HYPERPLASIA
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

30. MECHANICS WHICH PRODUCE THE COMBINATION
SYNDROME
Bone is being lost in the anterior
region in the upper jaw, bony
resorption also occurs under the
mandibular partial
denture bases
The maxillary denture then moves up
in the anterior region and down in the
posterior region in function causing
tipping of denture. The fulcrum of
movement is in the cuspid-first
bicuspid region,
With the posterior palatal seal, a negative
pressure is produced posterior to the
fulcrum line. This negative pressure may
account for the enlarged tuberosities and
the papillary hyperplasia.

31. SEQUELEA OF WEARING MAXILLARY IMMEDIATE DENTURE
OPPOSING MANDIBULAR CLASS I RPD
A study conducted on 20 patients for a period of 3 yrs -
• All of the patients received maxillary complete immediate
dentures opposing Class I lower partial dentures. All were
first-time denture wearers.
• The first radiograph ( cephalogram) was made after the initial
healing of the anterior part of the maxillary ridge had taken
place, and after the anterior section of the immediate denture
had been refitted with cold-curing acrylic resin.
• A second radiograph was made after six to eight months.
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

32. Measurements were made directly on the radiographs, using the sella-nasion line
as a base.
Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.

33. Ellsworth Kelly ,Changes caused by a mandibular removable partial denture opposing a maxillary complete
denture; .I. Prosthet. Dent.February, 1972,Vol 27, no 2.
• All of the patients showed a loss of 1 to 3 mm. of ridge height
in the anterior region.
• All of the subjects showed an increase of 1 to 2.5 mm
posteriorly.

34. IMMEDIATE DENTURE
 after the first year the anterior dimensional changes are less
for immediate denture patients than for those who delay the
insertion of a denture until normal healing is completed.
 immediate full upper denture treatment results in the
preservation of the maxillary alveolar ridge.
K. Johnson, A three-year study of the dimensional changes occurring in the maxilla
following immediate denture treatment, Australian Dental Journal, April, I967,

35. OVERDENTURES
 The overdenture transfers occlusal forces to the alveolar
bone through the periodontal ligament of the retained tooth
roots *
 A comparison of immediate conventional dentures and
immediate overdentures found half as much bone loss (0.9
mm compared with 1.8 mm) in the anterior
mandible over the first year in the overdenture group**
*Brewer AA, Morrow RM. Introduction. In: Overdentures. 2nd ed. St Louis: CV
Mosby; 1980. p. 12-6.
**van Waas MA, Jonkman RE, Kalk W, van’t Hof MA, Plooij J, Van Os JH.
Differences two years after tooth extraction in mandibular bone reduction
in patients treated with immediate overdentures or with immediate complete
dentures. J Dent Res 1993;72:1001-4.

36.  a mean vertical bone loss in the anterior of the mandible of 5.2
mm after 5 years for immediate dentures compared with 0.6
mm for immediate overdentures.
 patients treated with complete maxillary dentures and
mandibular overdentures demonstrate less vertical alveolar
bone reduction than patients with complete maxillary and
mandibular dentures.
Crum RJ, Rooney GE Jr. Alveolar bone loss in overdentures: a 5-year study.
J Prosthet Dent 1978;40:610-3.

37. References
1. Orban’s Oral Histology and Embryology 12th Edition
2. Review Article : Biology of Bone Tissue: Structure, Function,
and Factors That Influence Bone Cells
3. Complete denture prosthodontics, 3rd edition, John J.Sharry
4. Prosthodontic Treatment for Edentulous Patients, 12th
edition, Zarb,Bolender
5. Campbell RL. A comparative study of the resorption of the
alveolar ridges in denture-wearers and non-denture-wearers.
J Am Dent Assoc 1960;60:143-53.
6. Wyatt, The effect of prosthodontic treatment on alveolar
bone loss: A review of the literature, The Journal Of
Prosthetic Dentistry, Volume 80 Number 3

38. 7. Antje Tallgren ,The continuing reduction of the residual alvealar
ridges in complete denture wearers: A mixed-longitudinal study
covering 25 years, J. Prosthet. Dent., February, 1972, vol 27,
no.2
8. Ellsworth Kelly ,Changes caused by a mandibular removable
partial denture opposing a maxillary complete denture; J.
Prosthet. Dent.February, 1972,Vol 27, no 2.
9. K. Johnson, A three-year study of the dimensional changes
occurring in the maxilla following immediate denture treatment,
Australian Dental Journal, April, I967,
10. Brewer AA, Morrow RM. Introduction. In: Overdentures. 2nd ed.
St Louis: CV Mosby; 1980. p. 12-6.
11. van Waas MA, Jonkman RE, Kalk W, van’t Hof MA, Plooij J, Van
Os JH. Differences two years after tooth extraction in mandibular
bone reduction in patients treated with immediate overdentures
or with immediate complete dentures. J Dent Res 1993;72:1001-
4.
12. Crum RJ, Rooney GE Jr. Alveolar bone loss in overdentures: a 5-
year study. J Prosthet Dent 1978;40:610-3.