2. A Proposal for the Classification of Bony
Defects Adjacent to Dental Implants
Leonardo Vanden Bogaerde,
Private Practice, Concorezzo, Italy
IJPRD Volume 24, Number 3, 2004
Pg No. 264 – 271
3. CLASSIFICATION
In 1964 Sherp noted:
Discussions of disease commonly begin with the tacit
assumption that all participants are considering the
same entity.
Since the variations of diseases are almost limitless,
depending on ones taste for subclassification, any
unqualified usage often leads to fruitless semantic
misunderstandings
4. The goal of classification of bone defects related
to dental implant placement is to help clinicians
accurately discuss proposed treatment regimens
and organize treatment for clinical correction.
A further goal is to categorize bone defects
requiring bone augmentation for implant placement
is to standardize terminology to allow for more
accurate dental communication.
5. BONE DEFECTS
In the last decade, dental
implants have become a reliable
procedure for the treatment
of partially or completely
edentulous jaws.
The lack of bone adjacent to an
implant can be considered a
true “Bony Defect”
6. ETIOLOGY
Bacterial Infection
Studies suggest that plaque
associated soft tissue
inflammation around implants may
have more serious implications
than marginal inflammation around
teeth with a periodontal ligament
Low vascularity soft tissue
band
Difference in
collagen/fibroblast ratio
Implant surface characteristics
7. Biomechanical Factors
Clinical evidence supports the concept that excessive
biomechanical forces may lead to high stress or
microfractures in the coronal bone to implant contact and
thus lead to loss of osseointegration around implant .
Overloading is likely to increase in 4 clinical situations:
1. The implant is placed in poor quality bone
2. The implants position or the total amount of implants
placed does not favor ideal load transmission over the
implant surface
3. The patient has a pattern of heavy occlusal function
associated with parafunction
4. The prosthetic superstructure does not fit the
implants precisely
ETIOLOGY
8. PREVIOUS CLASSIFICATIONS
Acc to Carranza
The pattern of bone destruction caused by periimplant
disease varies and in general depends on the amount of bone
present at the time of implant placement and the length and
severity of pathologic insult. The bone defects can be
divided into 4 groups
Group I – it demonstrates moderate horizontal bone loss
with a minimal intrabony component. This group of implants
is usually covered by a thin buccal and lingual/palatal bone
crest at time of placement and is an early stage of
periimplant breakdown.
Group II presents moderate to severe horizontal bone loss
with a minimal intrabony component. This group of implants
is an advanced condition of the implants in Group I
9. Group III demonstrates minimal to moderate horizontal
bone loss with an advanced circumferential intrabony lesion.
These implants are initially covered by a thin coronal bony
crest with a wider apical bone base.
Frequently the pattern of bone loss has a symmetric
feature with a circular trough of uniform width and depth
occurring around the circumference of implant
Group IV presents more complicated implant defects with
moderate horizontal bone loss with an advanced
circumferential intrabony lesion; additionally the buccal and
/or lingual plate has been lost. These implants usually
demonstrated a thin bone plate at the time of implant
placement, which resorbed under the pathologic conditions.
10. Acc to Carlo Tinti & Stefano Parma-
Benfenati
Five categories of defects:
1. Extraction wounds
2. Fenestrations
3. Dehiscences
4. Horizontal ridge deficiencies
5. Vertical ridge deficiencies
18. JOURNAL CLUB PROPER
Much effort has been devoted to improving GBR
procedures by either modifying the membrane
structure or improving the surgical technique for
membrane placement.
The importance of the anatomy of the defect and
its relationship to the regenerative process
however, have not, been adequately analyzed.
19. In 1993, Gelb proposed a classification of defects adjacent
to dental implants, distinguishing one- and three-walled defects
on the basis of the integrity of the bone surrounding the
implants.
That study emphasized the correlation between the
configuration of the defect and the clinical result:
A defect with minimal residual walls (zero-walled defect)
requires the use of a membrane with real spacemaker support to
heal,
whereas a defect with preserved walls (a three-walled defect)
could be healed by several regenerative procedures
20. The present article proposes a morphologic
classification of bony defects adjacent to dental
implants and briefly discusses the clinical
implications of the classification.
Bone defects adjacent to dental implants are
divided into two main groups according to the
remaining bone walls lining the defects:
• Closed defects: Defects with fully preserved
surrounding bone walls
• Open defects: Defects lacking one or more
surrounding bone walls
22. Considering the implant-bone contact at four sites
(mesial, buccal, distal, lingual), at the level of the
implant neck, the open defect group is further
divided into the following subgroups:
• ONs: No implant-bone contact at implant
neck, suprabony defect
23. ON: no implant-bone contact at implant
neck, intrabony defect
26. O3i: Three implant-bone contacts at implant
neck, intrabony defect (dehiscence
within the envelope)
27. O3e: Three implant-bone contacts at implant
neck, extrabony defect (dehiscence
outside the envelope)
28. DISCUSSION
The classification presented in the present article
divides defects into two main groups: closed
defects, with conserved surrounding bone walls,
and open defects, with the lack of one or more
bone walls.
Closed defects offer an ideal environment for
bone regeneration and tend to respond positively
to different regenerative procedures. It is
possible to achieve defect fill using membranes
alone, autologous bone particles alone, or a
combination of these techniques.
29. The healing environment of open defects is more
exposed to the undesirable external forces than
that of the previous group. The lesser space-
making features of these defects require the use
of an accurate regenerative procedure to ensure
sufficient space for bone growth and blood clot
protection during healing.
The most challenging procedure is the treatment
of suprabony defects (ONs), which are
characterized by a complete absence of bone
support around implants placed intentionally a few
millimeters above the alveolar crest.
30. Bony defects included within the bone contour
(ON, O1, O2, O3i) are more susceptible to
repopulation by osteogenic cells moving from the
surrounding bone walls, and the outcome of
treatment in these defect classes depends on the
space-making properties of the defect itself.
Bony defects located outside the bone contour
(O3e) are generally non–space making defects,
since there are no bone walls ensuring room for
regeneration
31. Clinical significance of the Classification
The real indications for GBR treatment. It is possible
to plan in advance the real need for a regenerative
procedure on the basis of the features of the defect.
Some defects often require no regenerative procedure
The type of GBR treatment suited to the morphology of
the defect
32. The amount of bone regeneration. The
measurements recorded at implant placement
and repeated at reentry surgery permit
assessment of the quantity of bone fill.
The prognostic index for each type of defect
33. There are two kinds of people,
those who do the work and
those who take the credit. Try
to be in the first group; there
is less competition there.
- Indira Gandhi
