Australian Dental Journal 2008; 53: 11–21
REVIEW
doi:10.1111/j.1834-7819.2007.00008.x
Ridge preservation: what is it and when should it be
considered
I Darby,* S Chen,* R De Poi*
*School of Dental Science, The University of Melbourne, Victoria.
ABSTRACT
The resorption of bone following extraction may present a significant problem in implant and restorative dentistry. Ridge
preservation is a technique whereby the amount of bone loss is limited. This paper discusses the scientific literature
examining the healing post-extraction and ridge preserving techniques, primarily from the perspective of implant dentistry.
Some indications for ridge preservation and methods considered appropriate are discussed.
Key words: Extraction, bone resorption, grafting, membranes, implants.
Abbreviation: ePTFE = expanded polytetrafluoroethylene.
(Accepted for publication 26 March 2007.)
INTRODUCTION
Internal changes
Prerequisites for successful implant therapy are integration of the implant, ideal implant position and
appropriate hard and soft tissue contours. These
require sufficient alveolar bone volume and favourable
ridge architecture coupled with an appropriate surgical technique. However, following extraction of teeth
the alveolar ridge resorbs, the rate of which may vary
between sites and subjects. This may result in
inadequate bone volume and unfavourable ridge
architecture for dental implant placement (Figs 1
and 2).
The aim of this article is to discuss events
following extraction and how these can be optimized
to facilitate successful implant therapy. The same
principles may be applied to edentulous areas in
order to enhance aesthetic outcomes for fixed bridges
and removable dentures. However, the primary focus
of this article is to improve the outcome of implant
therapy.
When a tooth is removed, there is haemorrhage
followed by formation of a blood clot that fills the
entire socket.2 With this is an inflammatory reaction
that stimulates recruitment of cells to form granulation
tissue. Within 48 to 72 hours after extraction the clot
starts to breakdown as granulation tissue begins to
infiltrate the clot especially at the base of the socket. By
four days the epithelium proliferates along the socket
periphery and immature connective tissue is apparent.
After seven days the granulation tissue has completely
infiltrated and replaced the clot. At this stage, osteoid is
evident at the base of the socket as uncalcified bone
spicules. Over the next 2–3 weeks (3–4 weeks after
extraction) this begins to mineralize from the base of
the socket coronally. This is accompanied by continued
re-epithelialization which completely covers the socket
by six weeks post-extraction. Further infill of bone
takes place with maximum radiographic density at
around 100 days.
A number of factors may affect the healing of
undisturbed sockets. The size of the socket is important
with wider sockets requiring more time to bridge the
defect compared with narrower sockets; it takes longer
to completely form bone at molar sites compared to
single-rooted sites. The sockets of teeth with horizontal
bone loss heal more quickly as the lower level of the
Events following an extraction
Healing of an extraction socket is characterized by
internal changes that lead to formation of bone within
the socket, and external changes that lead to loss of
alveolar ridge width and height.1
ª 2008 Australian Dental Association
11
Fig 1. Favourable ridge dimensions for implant placement.
Fig 2. Unfavourable ridge dimensions for implant placement.
alveolar bone means less infill is required. It should be
noted that bone does not regenerate to a level coronal
to the horizontal level of the bone crest or to the level of
the neighbouring teeth (i.e., 100 per cent socket fill does
not occur).1
External changes
A recent study by Araujo and Lindhe3 showed that in
the first eight weeks following extraction in a dog
model there is marked osteoclastic activity resulting in
the resorption of the buccal and lingual crestal walls.
They noted that the reduction of height was more
pronounced at the buccal wall and was accompanied by
a horizontal loss on both buccal and lingual walls. This
is an important finding because an adequate width and
height of buccal bone is important for optimal implant
aesthetics, and this study suggests that loss of buccal
bone may result in poorer, suboptimal aesthetics.
Dimensional changes following an extraction
Resorption of the external buccal and lingual socket
walls results in a change in the dimensions of the ridge.
12
Pietrokovski4 in an examination of healed sockets in
dried skulls showed that, from the occlusal aspect, the
crest of the residual ridge shifts lingually, and from the
lateral aspect, the ridge formed a concavity or flattened
to form a wall running straight between the alveolar
crests of the adjacent remaining teeth. Earlier studies
have shown a wide variation between subjects in the
dimensional changes both clinically and radiographically following removal of teeth, characterized by very
rapid reduction in both height and width.5,6 More
recent studies by Lekovic et al.7,8 have shown that there
is greater loss of alveolar ridge width than height and
that some degree of loss was observed at all extraction
sites. It has been suggested that this variability is due to
anatomic, prosthetic, metabolic, functional, genetic and
iatrogenic factors.9 The most rapid changes were found
in the early post-extraction period, from six months to
two years.10,11 In addition, Atwood and Coy11 showed
that there were differences in the rate of resorption
between maxillary and mandibular sites. They found
that the average change was four times greater in the
mandible than the maxilla. It should be noted that the
above studies were performed on edentulous subjects.
Schropp et al.1 studied the effect of a single tooth
extraction of premolar or molar teeth on bone healing
and soft tissue changes using clinical and radiographic
measurements as well as digital subtraction radiography. They showed that major changes take place in the
12 months following an extraction with an average of
50 per cent reduction in the width of the alveolar ridge.
Two-thirds of this reduction occurred within the first
three months. This loss averaged between 5 and 7 mm
and was similar at all sites in the mouth. Importantly,
most of the subjects did not wear a denture after
extraction. Immediately after tooth extraction the
width of the ridge was an average of 12 mm (8.6–
16.5 mm) and 12 months later 5.9 mm (2.7–12.2 mm).
Given that a standard body implant requires a minimum of 6–7 mm of bone dimension, many of these sites
would not be suitable for implant placement. The
authors conclude it would be advantageous if this loss
of bone dimension could be prevented.
Ridge preservation
Ridge preservation is any procedure undertaken at the
time of or following an extraction that is designed to
minimize external resorption of the ridge and maximize
bone formation within the socket. However, there are
clinical situations where it is not advisable to undertake
ridge preservation at the time of extraction (e.g., in the
presence of acute infection). In these situations, preservation of the ridge may be delayed by six to eight
weeks. A recent consensus report suggested that
minimal dimensional change occurs within six to eight
weeks of an extraction.12 Some ridge preservation
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I Darby et al.
techniques are based on the principles of guided
tissue ⁄ bone regeneration. Many procedures have been
suggested including minimally traumatic tooth extraction, soft and hard tissue grafting, concomitant use of
barrier membranes and immediate implant placement.
(a)
Minimally traumatic tooth extraction
Although tooth extraction is by necessity a traumatic
procedure, the application of appropriate instruments
with minimal force is recommended to limit damage to
the hard and soft tissues. Fine luxators or periotomes
can be inserted into the periodontal ligament to sever
the coronal fibre attachment, thereby loosening the
tooth until forceps can gently deliver the tooth from its
socket (Figs 3a and 3b). Multi-rooted teeth can be
decoronated and the roots sectioned and extracted
individually to facilitate this procedure (Figs 4a
(b)
(a)
Fig 4. (a) Decoronation and sectioning of a molar for extraction.
(b) Appearance of socket after roots sectioned and removed
individually.
and 4b). Given the increasing acceptance of implant
therapy, it may be argued that all extractions should be
undertaken with as minimally traumatic a technique as
possible. Even if an implant is not planned at the time
of tooth removal, the site may subsequently be considered for implant placement.
Timing of extractions
(b)
Fig 3. (a) Use of a periotome to aid in the minimally traumatic
removal of an upper right central incisor. (b) Appearance of the socket
immediately following extraction using periotome and the forceps only
to lift the tooth out of its socket.
ª 2008 Australian Dental Association
The summary of the literature above shows that most
resorption takes place within the first three months
after extraction. Therefore, if possible, the tooth should
be retained for as long as possible and the extraction
scheduled in accordance with the chosen time for
implant placement. A detailed discussion and classification for timing of implant placement after tooth
extraction may be found in the proceedings of the
3rd ITI Consensus Conference.12,13 However, it is not
always possible to retain all teeth in this manner with
pain and infection often necessitating immediate
removal of the offending tooth.
Debridement and decortication of the socket
Some studies recommend that the sockets be debrided
to remove anything that may interfere with healing,
13
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Ridge preservation
whilst others suggest that a round bur should be used to
perforate the socket walls a number of times to allow
greater access for blood vessels into the socket and any
grafting material in an attempt to improve bony infill.14
Conversely, it has been shown in an experimental study
that retention of the periodontal ligament along the
socket walls facilitated retention of the clot during the
early stages of wound healing.15 Thus, apart from
removal of chronically inflamed tissue and foreign
materials, extensive debridement or perforation of the
socket walls may not be required.
Coverage of the socket by soft tissue
The literature is divided over whether soft tissue
coverage of the socket at the time of extraction is
necessary for optimum healing of the socket and
aesthetics. Soft tissue coverage procedures may be
considered to retain, stabilize and protect grafting
materials. It is a critical step when using non-resorbable
membranes. Many techniques have been suggested and
include displacing neighbouring tissue to cover the
socket, such as coronal advancement of a buccal flap,
rotating grafts from tissue adjacent to cover the defect,
or using free gingival or subepithelial connective tissue
grafts.16–18 Alternatively, the site may be left for six to
eight weeks to allow healing and regeneration of
mucosa over the socket. The added volume of soft
tissue at this stage may facilitate optimum closure over
the socket when ridge preservation procedures are
undertaken. In a similar manner, procedures allowing
spontaneous soft tissue proliferation could be considered prior to extraction to increase soft tissue coverage,
such as removing the crown and burying the remaining
root.19 The Bio-Col technique20 involves the placement
of an anorganic bovine bone graft (Bio-Oss) protected
by a resorbable collagen sponge (Collaplug – see below)
and then allowing spontaneous epithelialization of
the socket under a denture tooth or bridge pontic.
However, there is a paucity of research evidence to
support this technique.
Mobilization of tissue can be a difficult procedure,
but splitting the periosteum at the base of a flap is
fairly straightforward and as a result may be the
technique of choice. However, coronally advanced
flaps need to be undermined and advanced a relatively
great distance to completely cover an extraction
socket. This may cause complications such as altering
the mucogingival line and creating a shallow vestibule,
either of which may require subsequent surgery to
correct.21 These problems may be avoided using a
subepithelial connective tissue graft taken by a window or envelope procedure from the palate. This
requires an appropriate donor site and sufficient
coverage by soft tissue around the extraction socket
to prevent necrosis of the graft in the initial phase of
healing. The question remains that these techniques
may increase soft tissue coverage, but do they result in
increased bone fill when used on their own. Recent
work by Araujo and Lindhe3 in a dog model showed
that this is not the case, a finding which may argue for
a space filler to be placed in the socket or use of a
membrane to maximize bone infill.
Bone or bone-substitute grafts only
Many grafting materials have been used and these
include autogenous bone, demineralized freeze-dried
bone allografts (DFDBA), xenografts, bioactive glass,
hydroxyapatite and calcium sulphate (Table 1).
Autogenous bone is thought of as the ‘‘gold standard’’.22 Becker et al.22 compared demineralized freezedried bone against autogenous bone in seven paired
sites finding that after three months new bone was
formed at sites where autogenous bone was placed, but
not in six of seven sites using DFDBA. Common sites
intra-orally to harvest autogenous bone are around the
surgical site, ascending ramus, chin and tuberosity.
Table 1. Summary of the studies quoted investigating ridge preservation using bone grafts only, membranes only or
a combination
Method used
Bone Graft only
Membranes only
Bone graft and
membrane
14
Authors
Material(s) used
Outcome
Becker et al. 1994
Artzi et al. 2000
Nemcovsky & Serfaty 1996
Froum et al. 2002
Guarnieri et al. 2004
Camargo et al. 2000
Lekovic et al. 1997
Autogenous bone compared to DFDBA
Bio-Oss
Hydroxyapatite
DFDBA and Bioactive glass
Calcium sulfate
Bioactive glass mixed calcium sulfate
ePFTE
Lekovic et al. 1998
Resolut
Iasella et al. 2003
DFDBA and Bio-Mend
Fowler et al. 2000
DFDBA and acelluar dermal graft
Little new bone formation around DFDBA
On average 82.3% bone infill
Predictable ridge preservation
Biogran 60% infill, DFDBA 33% infill
100% bone infill
Of some benefit
Signif greater infill and bone height ⁄ width
preservation than untreated control
Signif greater infill and bone height ⁄ width
preservation than untreated control
Less ridge width loss and more bone infill
than untreated control
No loss of ridge width or height
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I Darby et al.
Post-surgery the patient may experience considerable
discomfort in the donor.
A study using DFDBA23 showed that DFDBA cannot
speed up bone formation. Both Becker et al.22 and
Froum et al.24 showed little new bone formed around
DFDBA. It is not available in Australia, but it is often
mentioned in studies from North America and included
here for the sake of completeness.
Recently, Artzi et al.25 used a common porous
bovine bone graft (Bio-Oss) in 15 fresh extraction
sockets, covering the graft with soft tissue and
re-entering nine months later. They reported that
there was 82.3 per cent bone infill and all sites
allowed ‘‘safe’’ insertion of fixtures. Histologic appearance showed a mixture of Bio-Oss and new bone
formation, increasing in bone fraction apically. The
use of a xenograft does not require a donor site, thus
reducing morbidity following harvesting and simplifying the procedure. Figure 5 shows Bio-Oss placed in
an extraction socket.
Hydroxyapatite use in fresh extraction sockets in a
series of 23 cases was reported by Nemcovsky and
Serfaty.26 They achieved primary closure by rotating
split thickness flaps and were followed for 24 months.
They showed that there was predictable ridge preservation with minimal postoperative ridge deformation
(1.4 mm vertically and 0.6 mm horizontally). This
would retain sufficient bone volume to allow implants
to be inserted. However, over half the patients experienced some exfoliation of hydroxyapatite suggesting
that the flap design was not predictable in maintaining
soft tissue closure. A bioactive glass (Biogran) was
investigated in fresh extraction sockets by Froum
et al.24 and compared to control sockets and those
with DFDBA. All sites were covered by flap advancement and re-entered six to eight months later. The
placement of Biogran resulted in 60 per cent bone
Fig 5. Bio-Oss placed in an extraction socket for ridge preservation. It
will require something to hold it in place.
ª 2008 Australian Dental Association
vitality, a measure of new bone formation, with the
control and DFDBA sites showing approximately
33 per cent. However, it should be noted that all sites
were to receive implants, which suggests that there may
be little benefit of using a graft material. The placement
of calcium sulphate has been studied in a recent paper.
Guarnieri et al.27 placed calcium sulphate in 10
extraction sockets without a barrier membrane and
re-entered the sites at three months. The graft material
had readily resorbed with 100 per cent bone infill and
implants were able to be placed at all sites. It should be
noted that there is again a general lack of studies
reporting on the use of calcium sulphate, with which
the authors of the above paper concur. One study has
looked at the use of bioactive glass and calcium
sulphate together.28 No statistical difference was found
between experimental and control groups, casting
doubt on the use of these materials in combination.
Another product that was used to graft extraction
sockets is BioPlant HTRTM. It is a biocompatible
microporous composite of methacrylate and calcium
hydroxide. Haris et al.29 reported that after a period of
8 to 12 months there was sufficient hard tissue to
place implants. More recently, biphasic calcium phosphate has become available in Australia. This is a
combination of hydroxyapatite and tricalcium phosphate. However, the authors are not aware of any
peer-reviewed papers investigating its use in ridge
preservation.
Except for the study by Guarnieri et al.27 in each of
the above papers residual particles of the graft were
found at time of re-entry and raises the question of
what effect this may have on implant placement. The
evidence above may argue for use of calcium sulphate
which resorbs completely, but as mentioned earlier
there are few studies. Materials like Bio-Oss have been
much more widely researched. However, the authors
feel that the question remains ‘‘Does it matter if
particles are left?’’. If most bone infill is along the
socket walls and base,25 then any remaining particles
may be removed during the osteotomy. However, in a
dog study of implants placed in sites three months after
grafting with Bio-Oss there was still a substantial
portion of the graft present, and no osseointegration
occurred to the implants within the augmented portion
of the crest.30 This paper reinforces the need to wait
six to eight months post-grafting before implant
placement.
These papers show many different techniques for
improving the bony healing in extraction sockets, but
fail to answer what is the clinical relevance. Can a
particular technique reproducibly achieve a level of
bone fill that allows implant placement and reduces
tissue loss to a minimum? The above reports only
answer this question obliquely by indicating whether or
not implants were placed.
15
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Ridge preservation
Membranes only
It is also possible to cover the socket to prevent ingress
of soft tissue, thereby promoting maximal bony healing. Generally, there are two types of membrane used,
resorbable and non-resorbable. Table 1 summarizes the
papers quoted in this article. In 1997, Lekovic et al.7
investigated the use of a non-resorbable expanded
polytetrafluoroethylene (ePTFE) membrane to maintain
the alveolar ridge after extraction. Two sites each in 10
patients were used, one site receiving a membrane and
the other site as a control. All sockets were debrided
and flaps displaced to cover the membrane and socket.
Reassessment took place at six months, with significantly greater loss of bone height and width in the
control group and more infill in the ePTFE group.
However, 30 per cent of membranes became exposed
and this resulted in similar results to the control group.
Giving the high rate of exposure, this paper suggests the
use of ePTFE membranes should perhaps be avoided.
Figure 6 shows the use of an ePTFE membrane.
A later paper by the same group8 looked at the use of
a resorbable membrane compared to a control site in 16
patients. A polyglycolide ⁄ lactide membrane (Resolute,
WL Gore & Associates) was placed and reassessed at
six months. The experimental sites showed significantly
less loss of alveolar bone height, more internal socket
fill and less horizontal resorption of the ridge. Importantly, there were no exposures. Therefore, it seems that
Fig 7. Bio-Gide membrane used in ridge preservation. These
membranes usually require a bone graft in the socket to sufficient
support to prevent them collapsing into the socket.
resorbable membranes should be preferred over nonresorbable. Unfortunately, the authors did not report
on whether the ridges were suitable for implants
irrespective of technique, which limits the usefulness
of these papers. Although an animal-derived membrane, Bio-Gide is available in Australia and used
widely in clinical periodontal practice. We are unaware
of any ridge preservation studies reporting its use, but
there seems to be no reason why it could not be used
in this manner. Figure 7 shows the placement of a
Bio-Gide membrane.
Bone grafts and membranes together
Fig 6. ePTFE (Goretex) membrane in place. This later became
exposed, with consequent infection and soft and hard tissue loss.
PTFE membrane intentionally left exposed and removed at 4–6 weeks.
16
Some studies have investigated the use of bone grafts
and membranes together (Table 1). Iasella et al.31
reported on the use of tetracycline hydrated freeze-dried
bone allograft and a resorbable membrane (Bio-Mend)
compared to extraction alone in 24 patients. They
replaced the flap without complete socket coverage and
reassessed four to six months later. Both groups lost
ridge width, although the experimental group lost less
width and had more bone infill. The test group sites
were more suitable for implant placement, but all sites
were still able to receive implants. In a case report,
Fowler et al.32 used DFDBA and an acellular dermal
graft for ridge preservation. An acellular dermal graft is
an allograft harvested surgically and with all cellular
material and epidermal layer removed. The authors
found the height of tissue to be acceptable for implant
placement and suggested this technique be used
where primary closure couldnÕt be achieved. Recently,
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I Darby et al.
however, the American Academy of Periodontology
(AAP) issued a notice describing the recall of one
particular brand due to incomplete medical information
regarding the origin of the graft.
Interestingly, Fugazzotto33 in a report on a comparison of resorbable and titanium-reinforced membranes
used with Bio-Oss found that ‘‘significant bucco-lingual
ridge collapse was noted upon re-entry’’. The findings
of this paper are supported by the work of Zubillaga
et al.34 who showed that tacked membranes in place
results in less loss of augmented bone than non-tacked
membranes.
Other ‘‘space fillers’’
It appears that insertion of a filler material into the
socket is important to preserve as much bone as
possible, but does it always have to be a bone graft?
In addition, the presence of graft particles at time of
placement may not be desirable. Serino and co-workers35 placed in 36 patients a commercially available
bioabsorbable sponge of polylactide-polyglycolide. The
teeth were surgically extracted, sockets debrided, the
sponge inserted and flaps replaced with no primary
closure. Six months later all sites were reassessed and
implants placed. There were 26 test sockets and 13
control. All test sockets healed with less bone resorption than the controls especially in the mid-buccal
region. The authors suggested that the sponge served as
a support to prevent the collapse of the surrounding
soft tissue into the socket during the healing process. A
similar product is available commercially in Australia
and is a collagen plug (Collaplug, Zimmer Dental). This
and the sponge above can be placed into the socket
without raising a flap, but there is little research in this
area and the materials may only act to stabilize the clot
and not to preserve the ridge. Figure 8a shows
Collaplug before it is placed, Fig 8b after placement
in the socket and Fig 8c demonstrates healing after
three weeks.
(a)
(b)
(c)
Implants as ridge preservers
The third ITI consensus report showed that immediate
implants are a very successful form of therapy.12
However, it has been reported that implants do not
‘‘preserve’’ the ridge they are placed into.36–38 Araujo
et al.36 demonstrated that immediate implant placement
in a dog model failed to prevent resorption of the socket
walls, especially buccally. They suggested that this may
be due in part to the early disappearance of the bundle
bone and also disruption of the blood supply buccally
due to elevation of a flap. Bundle bone, in the presence
of a tooth, occupies a larger fraction of the marginal
portion of the bone wall in the buccal than lingual and
has a large number of fibres from the periodontal
ª 2008 Australian Dental Association
Fig 8. (a) Collaplug before placement. (b) Collaplug placed in an
extraction socket. It quickly soaks up blood and reduces in size.
(c) Healing after three weeks after Collaplug placement.
ligament inserting. It seems that when a tooth is removed
bundle bone is resorbed rather than replaced. If one
thinks in terms of solely being able to place an implant
17
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Ridge preservation
then this may not matter at all as long as there is
enough bone initially, but this may cause problems
later especially in aesthetic areas if there is buccal tissue
loss.39
The future
Given the current advances in stem cell technology we
may in the future be able to place tooth buds in sockets
to regrow teeth or place a cellular scaffold in the socket
to maintain the bone. Cultivated scaffolds from bone
marrow mesenchymal stem cells have been placed
into fresh extraction sockets with results that ‘‘show
promise’’.40
Complications
It needs to be mentioned that any surgical procedure
may have complications. These commonly are postoperative pain and swelling, and occasionally infection.
Any surgery on the gingival tissues will cause some
recession. It is well known that in GTR procedures
up to 70 per cent of non-resorbable membranes may
become exposed to the oral environment, severely
reducing the amount of new tissue formed.41 In
addition, Girard et al.42 reported a case of a foreign
body granuloma following placement of a graft into an
extraction socket with pain and sensation disturbance.
It should be noted that the site was already compromised by previous infection and may serve as a
reminder to debride sockets fully or not to undertake
preservation in the presence of infection.
DISCUSSION
Although the literature presents a confusing picture
with difficulty in comparing studies, ridge preservation
does appear to limit the loss of hard and soft tissue at
extraction sites, and can provide less bone loss compared to non-preserved sites. While there were extraction-only sites that were suitable for implant therapy,
the most predictable maintenance of ridge width, height
and position was achieved using ridge preservation.
Ideally, a technique for socket preservation ought to be
easy to use, not involve surgery, leave no residual
foreign bone particles, involve no ‘‘floppy’’ membranes
likely to collapse into the socket and result in no bone
loss. However, it appears that no material or technique
fully meets these criteria.
The authors experience with Collaplug (Zimmer) is
that, after six to eight weeks, resorption is similar to
that seen in a normal extraction socket; the material
therefore does not seem to do much to preserve the
ridge. The PGA ⁄ PLA plug reported by Serino et al.35
may have been designed to have a much slower
resorption rate.
18
Although no one procedure or technique meets all of
the above criteria, a reasonable choice would seem to
be a surgical procedure involving placing an osteoconductive bone graft with a slow resorption rate (BioOss or a synthetic material) covered with a resorbable
membrane which may be tacked into place. This
appears to be a method that may preserve sufficient
volume and contour to permit subsequent implant
placement and achievement of acceptable aesthetic
results. Compared to the plugs this technique has been
proven to provide adequate ridge height and width for
implant placement.
The authorsÕ recommendation is that if a ridge is to
be preserved with predictable bone-fill, then a material
with osteoconductive properties and slow rate of
resorption (Bio-Oss or other synthetic material) should
be used. The socket should be sealed with a CT graft or
the Bio-Col technique used to effect soft tissue closure.
The implant would then be placed four to six months
later to provide sufficient time for maturation of the
graft.
If it is planned that the implant be placed within six
to eight weeks of extraction, then techniques and
materials designed to promote bone fill are not
necessary. Instead, the authors would recommend using
a resorbable collagen sponge (Collaplug or other
similar material) to aid with initial clot stabilization,
but the authors would not be relying on it to preserve
the ridge.
Indications for ridge preservation
The review of the literature above shows that ridge
preservation should be considered if an implant is to
be placed more than six to eight weeks after tooth
extraction. If an implant is to be placed at the time
of extraction or within six to eight weeks following
extraction, there appears to be little benefit in carrying
out ridge preservation procedures at the time of
extraction. Even when an implant might not be planned
in the near future, ridge preservation should be
considered in strategically important sites to retain the
possibility of an implant option for the patient in the
future. Ridge preservation should also be considered for
aesthetic reasons at pontic sites in conventional fixed
prosthodontics.
Figure 9 presents an outline of the questions that the
authors suggest should be asked at the time when
extraction is considered and the suggested approaches
that should followed. Specific indications for ridge
preservation include the following: (1) sites where the
buccal plate is less than 1.5–2 mm thick (virtually
always in the anterior and aesthetic zone) and sites
where there has been damage or loss of one or more of
the socket walls. These sites may lose a clinically
significant amount of the buccal plate upon healing3,42
ª 2008 Australian Dental Association
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I Darby et al.
Is implant placement
being considered
within the next 6 to 8
weeks?
Should the alveolar ridge be preserved?
YES....Does the tooth
need to be extracted
immediately?
Yes......Is there anything
stopping placement of a ridge
preserving material, such as acute
infection or medical issues?
NO....Why no?
Is the site extremely compromised,
the buccal plate more than 2 mm
thick, bone volume does not have to
be maintained or have previous
extraction sites healed up well?
No.....Try to keep the tooth until
time of implant therapy
NO.... there is significant
damage to the socket walls,
primary implant stability cannot
be assured or implant placement
has to be delayed due to
scheduling problems
Select a material that has a slow
rate of resorption and which will
eventually form new bone
– anorganic bovine bone
– bioactive glass
– biphasic calcium phosphate
Delay implant placement for 4 to
6 months
YES....is a graft required?
NO.... the
socket walls
are intact and
significant
resorption is
not
anticipated in
the following
6 to 8 weeks
– no graft
required
YES.... One or more
of the socket walls
have been lost, and
collapse of the ridge
needs to be
minimized.
Select a material that
will rapidly resorb
– collagen plug
– calcium sulfate
No....Is it a surgical extraction?
Yes......Debride
socket as much
as possible and
leave to heal.
Consider some
form of ridge
preservation 6–8
weeks later
Fig 10. Questions to be asked to assist with selection of an
appropriate material to be used for ridge preservation.
Yes.... consider the use
of bone grafts and
membranes to promote
as much bone
preservation as possible
and to build out the
buccal plate. Also
consider soft tissue
coverage of the socket
No.... use a material
that can be easily
contained in the socket
to preserve the ridge
Fig 9. An evidence-based outline of the questions that should be asked
at the time when extraction is considered and suggested approaches
that should followed.
and are more likely to present a challenge for successful
implant therapy; (2) sites where maintaining bone
volume is crucial to minimize the risk of involving
anatomical structures, such as the posterior maxilla or
mandible, where the maxillary sinus or inferior alveolar
nerve may present as a complication if further bone is
lost; (3) a patient with high aesthetic demands, such as
a high lip line or a thin biotype, which is prone to more
recession; and (4) in patients where many teeth are to
be extracted and preservation of the bone is important
of further restoration.
It should be noted that it is difficult to predict how
sites will heal. Some sockets will heal without much
resorption, whereas others will lose a lot of hard and
soft tissue. If the patient has had a number of previous
extractions then the loss of supporting ridge at these
sites might provide an indication of what will happen.
It appears that if there is any doubt about hard and soft
tissue loss then one should try to preserve the ridge.
Figure 10 presents an outline of the questions we
suggest that should be asked to assist with the selection
of materials, etc. The first consideration is timing of
implant placement. Will it be within six to eight weeks
or will implant placement be delayed beyond this time?
ª 2008 Australian Dental Association
If not then the next question is ‘‘Is there significant
damage to the socket that prevents primary stability
and requires grafting?’’, which will not only require
new bone formation, but the maintenance of as much
existing bone as possible. A slowly resorbing material
which will support the tissues and eventually form bone
is the material of choice. If the implant will be placed
within six to eight weeks then we suggest that the
following question should be ‘‘Is a graft required?’’.
The answer will be in the negative if the socket walls
are intact and significant resorption is not anticipated.
However, if there has been damage, i.e., where one wall
has been lost and collapse of the ridge must be
minimized that a rapidly resorbing material could be
chosen.
Contraindications to ridge preservation are acute
infection, where unassisted socket healing is likely to
result in good ridge morphology, when maintaining
bone volume is not critical and where surgery is
contraindicated by medical issues. The patient must
consent to the procedure also, which will involve
explaining the source of all materials. There might be
religious and ethical issues with some of the materials
(i.e., vegetarians and vegans with animal products).
Limitations
Ridge preservation has been developed recently. There
are a great number of techniques that have been
presented, but with only few research reports to
support. Further long-term studies are required especially to assess the ridge dimension following preservation and implant placement. From the studies reviewed
above there is no ideal technique to achieve 100
per cent bone preservation every time. No one technique is appropriate for all situations and a flap might
19
18347819, 2008, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1834-7819.2007.00008.x by Nat Prov Indonesia, Wiley Online Library on [14/09/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
Ridge preservation
have to be raised in some cases. Much may depend on
the general health and habits of the patient, such as
smoking.
13. Hämmerle CHF, Chen ST, Wilson TG. Consensus statements and
recommended clinical procedures regarding the placement of
implants in extraction sockets. Int J Oral Maxillofac Implants
2004;19(Suppl):26–28.
CONCLUSIONS
14. Buser D, Dula K, Belser U, Hirt HP, Berthold H. Localized ridge
augmentation using guided bone regeneration. I. Surgical procedure in the maxilla. Int J Periodontics Restorative Dent
1993;13:29–45.
Implant treatment can be facilitated at the time of
extraction by considering ridge preservation and maintaining sufficient bone for optimal implant placement
and consequently appearance. Consideration has been
given to healing of extraction sockets and previously
published studies that have attempted to preserve the
alveolar ridge. Based on these studies the authors have
designed an outline of the questions the authors feel
should be asked when considering ridge preservation.
This article also covers some of the materials available.
The majority of teeth are extracted by general dental
practitioners and it is hoped that this article will
stimulate some thought on the topic of ridge preservation. Not all extraction sockets need to be preserved,
but the authors feel that ridge preservation ought to be
considered at the time of tooth removal.
REFERENCES
1. Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing
changes and soft tissue contour changes following single-tooth
extraction: a clinical and radiographic 12-month prospective
study. Int J Periodontics Restorative Dent 2003;23:313–323.
2. Amler MH, Johnson PL, Salman I. Histological and histochemical investigation of human alveolar socket healing in undisturbed
extraction wounds. J Am Dent Assoc 1960;61:31–34.
3. Araujo MG, Lindhe J. Dimensional ridge alterations following
tooth extraction. An experimental study in the dog. J Clin Periodontol 2005;32:212–218.
4. Pietrokovski J. The bony residual ridge in man. J Prosthet Dent
1975;34:456–462.
5. Johnson K. A study of the dimensional changes occurring in the
maxilla following tooth extraction. Aust Dent J 1969;14:241–
244.
6. Atwood DA. Post-extraction changes in adult mandible as illustrated by microradiograph of midsagittal section and serial
cephalometric roentogenograms. J Prosthet Dent 1963;13:810–
824.
7. Lekovic V, Kenney EB, Weinlaender M, et al. A bone regenerative
approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases. J Periodontol 1997;68:563–570.
8. Lekovic V, Camargo PM, Klokkevold P, et al. Preservation of
alveolar bone in extraction sockets using bioabsorbable membranes. J Periodontol 1998;69:1044–1049.
9. Jahangiri L, Devlin H, Ting K, Nishimura I. Current perspectives
in residual ridge remodeling and its clinical implications: a
review. J Prosthet Dent 1998;80:224–237.
10. Tallgren A. Positional changes of complete dentures. A 7-year
longitudinal study. Acta Odontol Scand 1969;27:539–561.
15. Cardaropoli G, Araujo M, Lindhe J. Dynamics of bone tissue
formation in tooth extraction sites. An experimental study in
dogs. J Clin Periodontol 2003;30:809–818.
16. Carmagnola D, Berglundh T, Lindhe J. The effect of a fibrin glue
on the integration of Bio-Oss with bone tissue. An experimental
study in labrador dogs. J Clin Periodontol 2002;29:377–383.
17. Misch CE, Dietsh-Misch F. A modified socket seal surgery with
composite graft approach. J Oral Implantol 1999;25:244–250.
18. Landsberg CJ, Bichacho NA. A modified surgical ⁄ prosthetic
approach for optimal single implant supported crown. Part 1. The
socket seal surgery. Pract Periodontics Aesthet Dent 1994;6:11–
17.
19. Langer B. Spontaneous in situ gingival augmentation. Int J
Periodontics Restorative Dent 1994;14:524–535.
20. Sclar A. The Bio-Col technique. In: Bowyers LC, ed. Soft tissue
and esthetic considerations in implant therapy. Chicago, IL:
Quintessence, 2003:163–187.
21. Seibert JS, Slama H. Alveolar ridge preservation and reconstruction. Periodontol 2000 1996;11:69–84.
22. Becker W, Becker BE, Caffesse R. A comparison of demineralized
freeze-dried bone and autologous bone to induce bone formation
in human extraction sockets. J Periodontol 1994;65:1128–1133.
23. Aspenberg P, Kalebo P, Albrektsson T. Rapid bone healing
delayed by bone matrix implantation. Int J Oral Maxillofac
Implants 1988;3:123–127.
24. Froum S, Cho S-C, Rosenberg E, Rohrer M, Tarnow D. Histological comparison of healing extraction sockets implanted with
bioactive glass or demineralised freeze-dried bone allograft: a
pilot study. J Periodontol 2002;73:94–102.
25. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing
of human extraction sockets. Part 1: Histomorphometric evaluations at 9 months. J Periodontol 2000;71:1015–1023.
26. Nemcovsky CE, Serfaty V. Alveolar ridge preservation following
extraction of maxillary teeth. Report on 23 consecutive cases.
J Periodontol 1996;67:390–395.
27. Guarnieri R, Pecora G, Fini M, et al. Medical grade calcium
sulfate hemihydrate in healing of human extraction sockets:
clinical and histological observations at 3 months. J Periodontol
2004;75:902–908.
28. Camargo PM, Lekovic V, Weinlaender M. Influence of bioactive
glass changes in alveolar process dimensions after exodontia.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
2000;90:581–586.
29. Haris AG, Szabo G, Ashman A, Divinyi T, Suba Z, Martonffy K.
Five-year 224-patient prospective histological study of the clinical
applications using a synthetic bone alloplast. Implant Dentistry
1998;7:287–299.
30. Carmagnola D, Berglundh T, Araujo M, Albrektsson Lindhe J.
Bone healing around implants placed in a jaw defect augmented
with Bio-Oss. An experimental study in dogs. J Clin Periodontol
2000;27:799–805.
11. Atwood DA, Coy WA. Clinical, cephalometric and densitometric
study of reduction of residual ridges. J Prosthet Dent
1971;26:280–295.
31. Iasella JM, Greenwell H, Miller RL, et al. Ridge preservation
with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: A clinical
and histologic study in humans. J Periodontol 2003;74:990–999.
12. Chen ST, Wilson TG, Hämmerle CHF. Immediate or early
placement of implants following tooth extraction: review of
biologic basis, clinical procedures and outcomes. Int J Oral
Maxillofac Implants 2004;19(Suppl):12–25.
32. Fowler EB, Breault LG, Rebitski G. Ridge preservation utilising
an acellular dermal allograft and demineralised freeze-dried bone
allograft: Part 1. A report of 2 cases. J Periodontol 2000;
71:1353–1359.
20
ª 2008 Australian Dental Association
18347819, 2008, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1834-7819.2007.00008.x by Nat Prov Indonesia, Wiley Online Library on [14/09/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
I Darby et al.
33. Fugazzotto PA. GBR using bovine bone matrix and resorbable
and nonresorbable membranes. Part 1: Histologic results. Int J
Periodontics Restorative Dent 2003;23:361–369.
34. Zubillaga G, Von Hagen S, Simon BI, Deasy MJ. Changes in
alveolar bone height and width following post-extraction ridge
augmentation using a fixed bioabsorbable membrane and demineralised freeze-dried bone osteoinductive graft. J Periodontol
2003;74:965–975.
35. Serino G, Biancu S, Iezzi G, Piattelli A. Ridge preservation following tooth extraction using a polylactide and polyglycolide
sponge as space filler: a clinical and histological study in humans.
Clin Oral Implants Res 2003;14:651–658.
36. Araujo MG, Sukekava F, Wennstrom JL, Lindhe J. Ridge alterations
following implant placement in fresh extraction sockets: an experimental study in the dog. J Clin Periodontol 2005;32:645–652.
37. Botticelli D, Berglundh T, Lindhe J. Hard-tissue alterations following immediate implant placement at extraction sites. J Clin
Periodontol 2004;31:820–828.
38. Chen ST, Darby IB, Adams GG, Reynolds EC. A prospective
clinical study of bone augmentation techniques at immediate
implants. Clin Oral Implants Res 2005;16:176–184.
39. Araujo MG, Wennstrom JL, Lindhe J. Modeling of the buccal
and lingual bone walls of fresh extraction sites following
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implant installation. Clin Oral Implants Res 2006;17:606–
614.
40. Marei MK, Nouh SR, Saad MM, Ismail NS. Preservation and
regeneration of alveolar bone by tissue-engineered implants.
Tissue Eng 2005;11:751–767.
41. Cortellini P, Tonetti MS. Focus on intrabony defects: guided
tissue regeneration. Periodontol 2000 2000;22:104–132.
42. Girard B, Baker G, Mock D. Foreign body granuloma following
placement of hard tissue replacement material: a case report.
J Periodontol 2000;71:517–520.
Address for correspondence:
Dr Ivan Darby
Senior Lecturer and Head of Periodontics
School of Dental Science
The University of Melbourne
720 Swanston Street
Parkville, Victoria 3010
Email: idarby@unimelb.edu.au
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Ridge preservation