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Alveolar ridge resorption after tooth extraction: A consequence of a fundamental principle of bone physiology

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It is well established that tooth extraction is followed by a reduction of the buccolingual as well as the apicocoronal dimension of the alveolar ridge. Different measures have been taken to avoid this bone modelling process, such as immediate implant placement and bone grafting, but in most cases with disappointing results. One fundamental principle of bone physiology is the adaptation of bone mass and bone structure to the levels and frequencies of strain. In the present article, it is shown that the reduction of the alveolar ridge dimensions after tooth extraction is a natural consequence of this physiological principle.
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Journal of Dental Biomechanics
3: 1758736012456543
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DOI: 10.1177/1758736012456543
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It is well established that tooth extraction is followed by a
reduction of the buccolingual as well as apicocoronal
dimension of the alveolar ridge at the edentulous site.
1,2
It
has been suggested that immediate implant placement into
fresh extraction sockets might counteract this catabolic pro-
cess and preserve the dimensions of the alveolar ridge.
3–6
However, studies in humans
7
and experiments in dogs
8,9
have belied this hypothesis. In another dog study, it was
found that the resorption of the buccal/lingual walls
occurred in two overlapping phases. In a first phase, the
bundle bone was resorbed and replaced with woven bone.
The second phase included resorption from the outer sur-
face of both bone walls.
10
It was stated that the reason for
this additional bone loss was not understood. In a dog study,
extraction sockets were found to be filled by woven bone
after 1 month and after 3 months a cortical ridge including
woven and lamellar bone had been formed.
11
After 6
months, woven bone was being replaced with lamellar bone
and bone marrow. The application of freeze-dried bone
allograft in combination with a membrane was found to
improve the ridge dimensions in patients after 6 months
compared to a control, both vertically and horizontally.
12
In
studies in dogs, grafting with Bio-Oss™ collagen in extrac-
tion sockets improved the ridge dimensions after 6 months
compared to a control,
13
while grafting with autologous
bone did not.
14
The above literature gives the impression that the reason
for bone loss after tooth extraction is unknown. In the year
1881, Roux
15
suggested that the loss of alveolar bone
occurring after tooth loss in the old age is an example of
disuse atrophy. His reasoning was that after tooth loss, the
forces on the bone are reduced, which means that less bone
is needed and that the body gets rid of bone that is not suf-
ficiently used. Our knowledge of bone physiology has
expanded greatly since 1881.
Wolffs
16
law suggests that bone tissue adapts its mass
and structure to the mechanical demands. A more detailed
discussion on this subject requires some insights in the dis-
cipline mechanics of materials. When a structure, for exam-
ple, the mandible, is loaded, it is deformed. There are
stresses and strains in the structure. An infinitesimal cubic
element in the structure is considered (Figure 1(a)). The
stresses on the surfaces of this cube are expressed: tensile/
compressive stresses perpendicularly to the surfaces and
shear stresses parallel to the surfaces. The cube can be
rotated, so that the shear stresses disappear and we only
have stresses perpendicularly to the surfaces (Figure 1(b)).
These latter stresses are called principal stresses. The cor-
responding strains are called principal strains (Figure 1(c)).
With knowledge of the geometry of a structure, the material
properties and the loads upon the structure the stresses and
Alveolar ridge resorption after tooth
extraction: A consequence of a fundamental
principle of bone physiology
Stig Hansson
1
and Anders Halldin
1,2
Abstract
It is well established that tooth extraction is followed by a reduction of the buccolingual as well as the apicocoronal
dimension of the alveolar ridge. Different measures have been taken to avoid this bone modelling process, such as
immediate implant placement and bone grafting, but in most cases with disappointing results. One fundamental principle
of bone physiology is the adaptation of bone mass and bone structure to the levels and frequencies of strain. In the
present article, it is shown that the reduction of the alveolar ridge dimensions after tooth extraction is a natural
consequence of this physiological principle.
Keywords
bone resorption, tooth extraction, implant
1
Astra Tech AB, Mölndal, Sweden
2
Department of Prosthodontics, Faculty of Odontology, Malmö
University, Malmö, Sweden
Corresponding author:
Stig Hansson, Astra Tech AB, P.O. Box 14, SE-431 21 Mölndal, Sweden.
Email: stig.hansson@astratech.com
456543
DBM0010.1177/1758736012456543Journal of Dental BiomechanicsHansson and Halldin
2012
Article
2 Journal of Dental Biomechanics
strains can be calculated.
17
Figure 2 illustrates the concept
of strain. Figure 2(a) shows a piece of material that is
unloaded. In Figure 2(b), it is subjected to a tensile force.
The piece is elongated. The elongation (ΔL) divided by the
original length (L) gives the strain (ΔL/L). In this case, the
strain is positive. With a compressive load, the piece of
material becomes shorter. The strain is negative. Strains in,
for example, cortical bone are small. For this reason, the unit
microstrain is often used. If the elongation is 1% of the orig-
inal length, the strain is 10,000 microstrain.
There is a wealth of literature testifying of profound
effects of strain on bone mass and bone structure. The
lamellae of cancellous bone are preferentially aligned with
the principal strains caused by the dominating loads.
16,18,19
This enables the most economical use of the bone material.
Changes in loading direction result in changes in the direc-
tions of the principal strains, and the lamellae of the cancel-
lous bone realign with the new principal strain directions.
20
Petrtýl et al.
21
found that the Haversian systems of cortical
bone preferentially are aligned with the first principal strain
caused by the dominating loads. This also means an eco-
nomical use of the bone material. The bone mass primarily
depends on the magnitude of the strains
22
and the number
of strain cycles per time unit.
23
Based on a compilation of
animal experimental data, Qin et al.
23
proposed the follow-
ing formula for a daily stress stimulus,
Ψ
bi
i
m
m
n=
σ
day
1/
(1)
where n
i
is the daily number of cycles of loading type i, σ
i
is the stress associated with loading type i and the exponent
m is a constant, the value of which depends on the daily
number of loading cycles. By substituting σ
i
in equation (1)
with ε
i
/E, where ε
i
is the strain associated with loading type
i and E is the modulus of elasticity of the bone, a formula
for a daily strain stimulus is obtained (equation (2))
n
/
day
bi
m
m1
/E
i
W
=
f
d
_
n
i
/
(2)
Qin et al.
23
found that the strain stimulus needed per day
to maintain bone mass could be expressed by the following
formula
y = 10
2.28
(5.6 log
10
x)
1.5
(3)
where x is the number of loading cycles per day and y is the
strain magnitude. Rubin et al.
24
observed that the maximum
bone strains measured in the metacarpal bone of a galloping
horse, the tibia of a running human, the femur of a running
sheep, the humerus of a flying goose and the mandible of a
chewing macaque are remarkably similar, ranging between
2000 and 3500 microstrain. These strains are about 50% of
the yield strain of cortical bone, indicating that nature
applies a safety factor of approximately 2 when designing
bones. The aim of the present study was to investigate
whether the observed changes in alveolar ridge dimensions,
after tooth extraction, can be understood within the frame-
work of established principles of bone physiology.
Methods and results
Bending of a beam
Consider the beam in Figure 3 that is subjected to pure
bending. The beam is assumed to have a symmetrical cross
section. The bending moment (M) gives rise to stresses and
strains in the beam. At the longitudinal axis of the beam, the
stresses and strains are zero. When the strains are below the
yield strain of the material (6000 microstrain for cortical
Figure 1. (a) Tensile/compressive stresses and shear stresses on the surfaces of an infinitesimal cubic element, (b) principal stresses
and (c) principal strains.
Hansson and Halldin 3
bone), there is a linear relationship between stress and
strain. The stresses create an internal bending moment that
exactly counterbalances the external bending moment (M).
The mandible as a beam subjected to
bending moments
Consider a mandibular tooth. When the tooth is loaded, it
will induce a mechanical stimulation, strains, in the bone
immediately adjacent to the tooth. The loading of more dis-
tant teeth, the action of the masticatory muscles and the
reaction forces at the temporomandibular joints will give
rise to bending moments in the mandible. These bending
moments will also give rise to strains in the bone adjacent
to the tooth in question. A steady-state condition is assumed
to prevail, which means that the sum of these strains will
represent the strain stimulus needed to maintain bone mass
as proposed by Qin et al.
23
Consider a section of the mandible containing one tooth
(Figure 4). The mandible section is assumed to be subjected
to a bending moment (M
z
), which gives rise to deformations
in the horizontal plane (vertical moment vector). Consider a
bending moment of such a magnitude that an average strain
of ±2000 microstrain arises in the buccal and lingual extrem-
ities of the mandible section. This is an unusually high strain
for cortical bone.
24
As the length of the mandible section is
assumed to be 7 mm, these bending moments will give rise
to a maximum elongation or reduction in the length of the
section, which amounts to 0.002 × 7 = 0.014 mm. The length
changes of the part of the mandible section that contains the
periodontal ligament are smaller (Figure 4). Theoretically,
these latter length changes will be absorbed by the bone, by
the periodontal ligament and by the tooth. Subtracting the
part that is absorbed by the bone, the maximum length
changes that are absorbed by the periodontal ligament and
the tooth will be well below 0.014 mm.
In Figure 5, the mandible section is assumed to be sub-
jected to bending in vertical direction, which results in an
average strain in the uppermost part of ±2000 microstrain.
This implies that length changes amount to ±0.014 mm,
which will be absorbed by the bone, the periodontal liga-
ment and the tooth together. The maximum length changes
that will be absorbed by the periodontal ligament and the
tooth together will be below 0.014 mm.
Figure 2. (a) A piece of a material that is unloaded and (b) a distributed tensile force (F) elongates the piece of material.
Figure 3. A beam, with a symmetric cross section, subjected to pure bending. The bending moment (M) induces tensile stresses and
strains in the lower half of the beam and compressive stresses and strains in the upper half.
4 Journal of Dental Biomechanics
From a mechanical point of view, the mandible
behaves as if the space occupied by the
periodontal ligament and the tooth was empty
The thickness of the human periodontal ligament is about
0.1–0.3 mm. Assume an average thickness of 0.2 mm.
25
Pini et al.
26
derived stress–strain curves in compression and
tension for bovine periodontal ligaments. With strains
below ±10%, the stresses were close to 0. This finding was
confirmed by Sanctuary et al.
27
who investigated the
mechanical properties of the bovine periodontal ligament.
The stress–strain curves exhibited a central ‘zero zone’ in
which the periodontal ligament behaved like a fluid. In this
zone, straining of the periodontal ligament sample did not
result in any significant stress response. Independently of
strain rate, no significant stresses appeared below a strain
of ±20%. The above discussed length change of less than
0.014 mm distributed over two periodontal ligament pas-
sages (2 × 0.2 = 0.4 mm) implies a strain that is less than
0.014/0.4 = 0.035. It can be concluded that the stresses in
the periodontal ligament with this strain are negligible. This
means that no stresses are transmitted from the bone to the
tooth. The tooth does not participate in resisting the bend-
ing moments. From a mechanical point of view, the mandi-
ble behaves as if the space occupied by the periodontal
ligament and the tooth was empty.
Figure 4. Schematic picture of a section of a mandible seen from above. The section contains a tooth, the periodontal ligament and
the surrounding bone. The mandible section is subjected to bending in the horizontal plane. The tensile and compressive strains and
the length changes are the highest buccally and lingually.
Figure 5. (a) A section of a mandible containing one tooth. The mandible section is subjected to bending in a vertical plane, which
creates strains. The strains are highest in the upper and lower extremities of the section. (b) The mandible section seen from above.
The length changes in the uppermost part are shown.
Hansson and Halldin 5
When the extraction socked is filled with
bone the mandible becomes stiffer and the
strains are reduced
After resorption of the bundle bone, the extraction socket
will gradually be filled with lamellar and cancellous bone
(Figure 6), which will make the mandible section stiffer
both with respect to horizontal bending and vertical bend-
ing. A consequence of this is that with unchanged bending
moments, the bone strains will be reduced. The absence of
the extracted tooth represents a further strain reduction.
Reduced bone strains result in bone loss.
23,24
In a study in
dogs, the right forelimb was functionally isolated, by encas-
ing in plaster, while the left forelimb served as control.
28
Functional isolation results in reduction of the bone strains.
After 40 weeks, approximately 50% of the bone mass was
lost on the third metacarpal, 42% on the radius, 35% on the
ulna and 28% on the humerus of the experimental limb. In
total, 80%–90% of the bone loss occurred at the periosteal
surface. Thus, bone resorption, mainly at the external bone
envelope, resulting in reduced vertical and horizontal
dimensions of the mandible, appears to be a natural conse-
quence of tooth extraction. The bone resorption can be
expected to continue until the bone strains have reached the
levels of the pre-extraction time with healed conditions in
the extraction socket.
An implant will further increase the stiffness
of the mandible
Consider the mandible section, now containing an implant,
that is subjected to a bending moment (M
z
), which gives
rise to deformations in the horizontal plane (Figure 7(a)).
About half of the implant will be subjected to compressive
stresses, and the other half will be subjected to tensile
stresses. On the compression side, the implant will contrib-
ute to the stiffening of the mandible. The magnitude of this
stiffening effect depends on the implant design and the
implant material. The modulus of elasticity of titanium,
cortical bone and cancellous bone are about 107, 19 and 0.8
GPa, respectively.
29
Since titanium is much stiffer than cor-
tical and cancellous bone, the implant will, compared to the
situation with bone completely filling the previous extrac-
tion socket, further increase the stiffness of the mandible on
the compression side. On the tension side, the situation is
more complicated. The tensile strength between implant
and bone is limited.
30
Theoretically, this tensile strength can
locally be exceeded, and a small gap arise between implant
and bone. This will have a reducing effect on the mandible
stiffness. However, the net effect of the implant should be a
further stiffening of the mandible as compared to the situa-
tion with bone filling the previous extraction socket. The
same line of argument applies to the situation when the
mandible section is subjected to vertical bending (Figure
7(b)). Thus, on theoretical grounds, immediate implant
placement into fresh extraction sockets should not be
expected to prevent the reduction of the buccolingual or
apicocoronal dimensions of the alveolar ridge.
Retention elements at the endosseous neck
portion of the implant should preserve the
apicocoronal dimension of the alveolar ridge
An increased resistance to bending of the mandible, both in
horizontal and vertical directions, seems to be an inevitable
consequence of the replacement of the tooth and periodontal
Figure 6. (a) A mandible section containing one tooth (bottom) or one extraction socket (top), as seen from above. The mandible
section is subjected to bending in a horizontal plane with a specific bending moment (M
z
). The stiffness of the mandible section is
the same in these two cases. Consequently, the strains are the same. (b) When the extraction socket is filled with bone, it becomes
stiffer and the strains are reduced. (c) A mandible section containing one tooth (bottom) or one extraction socket (top). The mandible
section is subjected to bending in a vertical plane with a specific bending moment (M
y
). The stiffness of the mandible section is the
same in these two cases. Consequently, the strains are the same. (d) When the extraction socket is filled with bone, it becomes stiffer
and the strains are reduced.
6 Journal of Dental Biomechanics
ligament by an implant and bone. An increased resistance to
bending implies reduced strains provided that the magnitude
of the bending moments remains unchanged. Nature’s nor-
mal response to reduced bone strains is to reduce the bone
mass and architecture in such a way that the daily stress/
strain stimulus needed to maintain bone mass is reached
again.
23
This is normally done by resorption at the external
bone envelope.
28
The resistance to bending of the mandible in horizontal
and vertical directions can be reduced by reducing the
buccal-lingual dimensions, by reducing the apicocoronal
dimensions or by doing both. Theoretical
31,32
and clinical
studies
33–35
have demonstrated that the reduction of the api-
cocoronal dimensions can be reduced to a minimum if the
endosseous neck portion is equipped with retention ele-
ments of suitable design. With such retention elements of a
dental implant, the daily stress/strain stimulus needed to
maintain bone mass seems to be reached for the coronal-
most bone. Thus, with an implant that maintains the mar-
ginal bone level, nature achieves the required reduction in
resistance to bending of the mandible primarily by reduc-
tion of the buccal-lingual dimensions.
A theoretical possibility to also maintain the
buccal-lingual dimensions of the mandible
The bending moment required to produce a certain strain
on the surface of the beam in Figure 3 is proportional to the
product of a geometric entity called section modulus and
the modulus of elasticity of the material. For a beam with a
circular cross section, the section modulus equals πD
3
/32,
where D is the diameter of the cross section. The fact that
the diameter, D, is raised to the power of three means that
the section modulus is very sensitive to the size of the cross
section. In the mandible containing one implant, there are
three different materials: cortical bone, cancellous bone
and the implant material. The modulus of elasticity of corti-
cal bone is about 20–50 times as high as that of cancellous
bone.
29
If cortical bone is replaced by cancellous bone, the
resistance to bending is decreased, and the bending moment
required to produce a certain strain is decreased. This
should imply that if there exists a means to reduce the
thickness of the cortical bone and to replace this by cancel-
lous bone, this should be instrumental in maintaining
the buccal-lingual dimensions of the mandible ridge.
Furthermore, the modulus of elasticity of cancellous bone
varies widely, which means that if there exists a means to
get cancellous bone of a low modulus of elasticity, this
should also be instrumental in maintaining the buccolin-
gual dimensions of the mandible ridge.
Discussion
Physiology is the science about the physical and chemical
functions of a living body. This article deals with the physi-
cal aspect of bone physiology. The language of physics is
mathematics. It would have been natural to express the line
of arguments of this study in a strictly mathematical lan-
guage. However, in the interest of readability, the message
has been worded in a qualitative manner.
The above analysis shows that the changes in the dimen-
sions of the alveolar ridge observed after tooth extractions
and after placement of implants in fresh extraction sockets
appear to be a natural consequence of the biologic laws
according to which the body is designed. In the evolution,
in the struggle for life, it has been important not to be too
Figure 7. (a) A mandible section, containing an implant, as seen from above. The mandible section is subjected to bending in the
horizontal plane. The implant makes the mandible section stiffer, and the strains are reduced. (b) A mandible section containing an
implant. The mandible section is subjected to bending in a vertical plane. The implant makes the mandible section stiffer, and the strains
are reduced.
Hansson and Halldin 7
heavy. For this reason, nature economizes with bone; it gets
rid of bone that is not sufficiently used by which the daily
stress/strain stimulus seems to be the measure of use
applied.
23
The above analysis was made on the mandible since the
mandible exhibits many similarities with a common engi-
neering structure – a curved beam. It is however suggested
that the same line of arguments can be applied on the max-
illa with its more complicated anatomy. Like the mandible,
the maxilla, in a mechanical sense, behaves as if the space
occupied by the periodontal ligament and the tooth was
empty. When, after tooth extraction, this space is occupied
by bone or by an implant and bone, the stiffness of the max-
illa will be increased. With unchanged loads, increased
stiffness implies reduced strains. The strain stimulus needed
to maintain bone mass is no longer reached. The biologic
response to this is to remove bone, which is preferentially
performed at the external bone envelope. The dimensions
of the alveolar ridge will be reduced.
Freeze-dried bone allograft in combination with a mem-
brane was found to improve the ridge dimensions in patients
after 6 months,
12
and in dogs grafting with Bio-Oss colla-
gen in extraction sockets was found to improve the ridge
dimensions, also after 6 months.
13
It was suggested above
that a theoretical possibility to maintain the ridge dimen-
sions after tooth extraction is to have the extraction socket
filled with bone of a low modulus of elasticity. It can be
speculated that the freeze-dried allograft and the Bio-Oss
collagen achieved that. A question that immediately pre-
sents itself is ‘what will happen in the long run?’ Will the
modulus of elasticity of the bone filling the extraction
socket increase with time? Grafting with autologous bone
did not improve the ridge dimensions after 6 months.
14
A consequence of tooth extraction is alveolar ridge
resorption.
2,36
The placement of implants in fresh extraction
sockets has failed to prevent this bone modelling process.
8
The present analysis shows that this reduction of the dimen-
sions of the alveolar ridge after tooth extraction seems to be
a natural consequence of well-known physiological laws.
After healing of the extraction socket, the strain stimulus
needed to maintain bone mass is no longer reached. The
bone resorption is normally larger at the buccal aspect of
the ridge than at the lingual aspect.
7,37,38
In animal and clini-
cal studies, the vertical component of the bone loss has
been more pronounced at the buccal aspect.
8,38
A conse-
quence of a greater vertical bone loss buccally than lin-
gually is a ridge that is sloped in the lingual-buccal
direction. In cases with such a sloped alveolar ridge anat-
omy, the placement of a standard implant might not be opti-
mal. The placement of the implant in level with the lingual
bone margin may result in compromised aesthetics. If the
implant instead is placed in level with the buccal bone mar-
gin, the lingual marginal bone is at risk to be resorbed due
to insufficient strain stimulus. In a clinical study, Fiorellini
et al.
39
used an implant with a sloped marginal contour in
cases where the patient presented with an alveolar crest that
was sloped in the lingual to buccal direction. Both the mean
buccal marginal bone level change and the mean lingual
marginal bone level change after 16 weeks amounted to
−0.2 mm. Thus, the installation of an implant with a sloped
marginal contour may be a treatment option in cases where
the alveolar ridge is sloped in lingual to buccal direction.
Conclusion
The reduction of the buccolingual as well as the apicocoro-
nal dimension of the alveolar ridge, commonly observed
after tooth extraction, can be explained by the physiologi-
cal law, according to which the maintenance of the bone
anatomy requires a certain daily stress/strain stimulus.
Funding
This research received no specific grant from any funding agency
in the public, commercial, or not-for-profit sectors.
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... Alveolar bone loss after tooth extraction can be an issue during dental implant placement and may result in compromised aesthetics [1]. The alveoli may have about 40% height and 60% width bone volume loss within 6 months after tooth extraction [2], [3]. ...
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Bone volume loss appears after tooth extraction and socket preservation is the most applied procedure to prevent an alveolar resorption. The aim of this study was to retrospectively analyse three socket preservation cases with high-density polytetrafluoroethylene barrier membrane (permamem®) for open healing with and without the use of additional dental regeneration biomaterials. Here no bacterial plaque was present and the soft tissue completely re-epithelialized, which allowed new bone formation and implant treatment. The current findings indicate that the use of this membrane, leads to successful socket treatment during open healing.
... Moreover, a significant factor that limits the clinical application of an endosteal implant is the restrictive necessity for alveolar bone mechanical support. 4 Successful implant placement requires sufficient alveolar bone volume in order to ensure implant stability and osseointegration, but the extraction of teeth will result in loss of alveolar ridge width and height within three years. 5 This bone loss is exacerbated if the tooth is removed traumatically or if there are pre-existing endodontic or periodontal pathologies. ...
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Alveolar ridge atrophy brings great challenges for endosteal implantation due to the lack of adequate vertical bone mass to hold the implants. To overcome this limitation, we developed a novel dental implant design: sub-scaffold dental implant system (SDIS), which is composed of a metal implant and a micro-nano bioactive glass scaffold. This implant system can be directly implanted under mucous membranes without adding any biomolecules or destroying the alveolar ridge. To evaluate the performance of the novel implant system in vivo, SDISs were implanted into the sub-epicranial aponeurosis space of Sprague-Dawley rats. After 6 weeks, the SDIS and surrounding tissues were collected and analysed by micro-CT, scanning electron microscopy and histology. Our results showed that SDISs implanted into the sub-epicranial aponeurosis had integrated with the skull without any mobility and could stably support a denture. Moreover, this design achieved alveolar ridge augmentation, as active osteogenesis could be observed outside the cortical bone. Considering that the microenvironment of the sub-epicranial aponeurosis space is similar to that of the alveolar ridge, SDISs have great potential for clinical applications in the treatment of atrophic alveolar ridges. The study was approved by the Animal Care Committee of Guangdong Pharmaceutical University (approval No. 2017370).
... Our findings showed that alveolar ridge resorption is inevitable with tooth loss, as evidenced in the literature [25][26][27]. Also, in our study, it was aimed to evaluate the relationship between long-term and short-term residual ridge loss and the type of prosthesis used. ...
Article
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Objectives The aim of this study was to compare the changes in mandibular bone structure in edentulous patients who were rehabilitated with conventional complete dentures (CCD) and implant supported overdentures (ISO), by evaluating alveolar bone loss (ABL), panoramic mandibular index (PMI), mandibular cortical width (MCW), gonion index (GI), antegonial index (AI), and articular eminence inclination (AEI). Materials and methods Panoramic radiographs of 63 edentulous patients using CCD, 63 edentulous patients using ISO, and 126 patients without tooth loss were evaluated. Edentulous patients had a 2-year and 6-year follow-up panoramic radiograph image. ABL (anterior, premolar, and molar regions), MCW, PMI, AI, GI, and AEI were measured in each patient. Variation between measurements was analyzed using repeated measures ANOVA test and post hoc Tukey test. Results Both edentulous groups showed significantly lower mean than without tooth lost group in all measures (p < 0.000). ISO group showed significantly lower mean ABL than CCD group in anterior (p = 0.000), right premolar (p = 0.005), left premolar (p = 0.005), right molar (p < 0.000), and left premolar (p < 0.000) regions in short term. ISO group showed significantly lower mean ABL than CCD group in anterior (p = 0.021), right molar (p < 0.000), and left premolar (p < 0.000) regions in long-term. There is no statistically significant difference between the CCD and ISO groups in right premolar (p = 0.200) and left premolar (p = 0.134) regions in long term. Both edentulous groups showed significantly lower mean MCW (p < 0.000), PMI (p < 0.000), AI (p < 0.000), GI (p < 0.012), and AEI (p < 0.002) than the without tooth loss group. There is no statistically significant difference between the CCD and ISO groups in terms of changes in the mean MCW, PMI, AI, GI, and AEI measurement in short and long term (p > 0.000). Conclusions In the short and long term, edentulism reduced alveolar crest height, MCW, and AEI in individuals, but had no effect on PMI, AI, or GI. The use of prosthesis did not prevent the decrease of alveolar crest height, MCW, or AEI (CCP or ISO). In the short and long term, however, ISO created less ABL in the mandibular anterior and molar regions than CCD. Clinical relevance ABL cannot be halted in edentulous people, but by using ISO instead of CCD for rehabilitation, resorption can be reduced.
... 29 Choosing a classic implant treatment approach with extractions at the first stage decreases load stimuli on bone and reduces bone volume during healing. 30 This can hinder future implant treatment or result in the need for additional regeneration procedures. The immediate implantation and provisionalization provide continuous stress and strain forces and stimulate favorable bone remodeling. ...
Article
Purpose: Comprehensive rehabilitation in patients with severe periodontal destruction may require the use of dental implants. The primary aim of this study was to evaluate bone volume changes in periodontally compromised patients over a 12-month follow-up period after immediate full-arch implant reconstruction of the mandible. The secondary aim was to evaluate the repeatability of 3D bone volume change measurement methods around dental implants. The null hypothesis was that bone volume would decrease in the first year after delivery of the definitive prosthetic reconstruction. Materials and methods: This retrospective study analyzed CBCT scans of 16 patients before and after computer-guided immediate full-arch implant reconstruction of the mandible. The bone volume change in the mandibular body and around the implants and the peri-implant bone area in coronal and axial cross sections were calculated. Results: The average bone gain for the mandibular body was 3.3% ± 1.8%. The average bone volume increase in the peri-implant area was 23.2% ± 16.7%. The interobserver and intraobserver ICC values for 3D measurements were high (> 0.85). Conclusion: The null hypothesis was rejected. Both mandibular body and peri-implant surroundings undergo bone remodeling in the form of bone gain over 12 months after immediate implantation.
... The resorption of the alveolar bone stabilizes between the first and second years from the extraction. However, although the percentage of bone loss in subsequent years is lower, the process continues throughout life [4]. If the alveolar socket is managed correctly, there is less bone resorption, especially in the first years. ...
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Background: After tooth extraction, the alveolar bone loses volume in height and width over time, meaning that reconstructive procedures may be necessary to perform implant placement. In the maxilla, to increase the bone volume, a mini-invasive surgery, such as a sinus lift using the crestal approach, could be performed. Methods: A crestal approach was used in this study to perform the sinus lift, fracturing the bone and inserting collagen (Condress®). The single dental implant was placed in the healed bone after six months. Results: The newly formed bone was histologically analyzed after healing. Histomorphological analyses confirmed the quality of the new bone formation even without graft biomaterials. This is probably due to the enlargement of the space, meaning more vascularization and stabilization of the coagulum. Conclusion: Using just collagen could be sufficient to induce proper new bone formation in particular clinical situations, with a minimally invasive surgery to perform a sinus lift.
... Bone loss and collapse of the surrounding gingiva occur in the normal healing response to tooth extraction. e bone resorption occurs in the bucco-lingual and apicocoronal dimensions [24]. However, the mesio-distal dimension is supported by interdental bone and intact adjacent teeth. ...
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Vitamin C is essential for wound healing. However, there are no reports concerning the effect of a different dose of vitamin C on extraction wound size clinically. Therefore, the aim of this study was to investigate the effect of different oral vitamin C doses on extraction wound healing. A split-mouth, double-blind randomized clinical trial was performed in 42 patients who underwent symmetric bilateral noninfected premolar extraction. The patients were randomly divided into 3 groups, namely, P/600, P/1,500, and 600/1,500 (14 patients for each group); P/600: placebo vs. 600 mg vitamin C/d, P/1,500: placebo vs. 1,500 mg vitamin C/d, and 600/1,500: 600 mg vitamin C/d vs. 1,500 mg vitamin C/d. Patients were prescribed placebo or/and vitamin C three times a day for 10 days after each tooth extraction. Extraction wound size and pain score were evaluated. The wound assessment was performed on day 0, 7, and 21; and then the tooth on the other side was extracted using the same protocol. Pain score was recorded on the first three days after extraction. The reduced size of mesiodistal extraction wound in percentage reduction between day 0 and 7 of teeth receiving vitamin C 600 mg/d was more than that in placebo ( P < 0.05 ). Pain scores on day 1–3 of teeth receiving vitamin C 600 mg/d were significantly lower than the placebo side ( P < 0.05 ). Taking oral vitamin C 600 mg/d over three doses for 10 days after tooth extraction enhances extraction wound healing by reducing mesiodistal extraction wound and reduces postoperative pain.
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Background: Characterizations of rat mandibular second molar extraction socket with significantly different buccal and lingual alveolar ridge width remain unclear. Objective: To observe alterations in the alveolar ridge after extraction of mandibular second molars, and to examine processes of alveolar socket healing in an experimental model of alveolar ridge absorption and preservation. Methodology: Eighteen Wistar rats were included and divided into six groups regarding healing time in the study. Bilateral mandibular second molars were extracted. The rats with tooth extraction sockets took 0, 1.5, 2, 3, 4 and 8 weeks of healing. Histological observation, tartrate-resistant acidic phosphatase (TRAP) staining, Masson's trichrome staining, immunohistochemical staining and micro-computed tomography (micro-CT) were applied to estimate alterations in the alveolar ridge. Results: Different buccal and lingual alveolar ridge width led to different height loss. Lingual wall height (LH) decreased significantly two weeks after tooth extraction. Buccal wall height rarely reduced its higher ridge width. From two to eight weeks after extraction, bone volume (BV/TV), density (BMD), and trabecular thickness (Tb.Th) progressively increased in the alveolar socket, which gradually decreased in Tb.Sp and Tb.N. LH showed no significant change during the same period. Osteogenic marker OCN and OPN increased during bone repair from two to eight weeks. The reduced height of the lingual wall of the tooth extraction socket was rarely repaired in the later repair stage. Osteoclast activity led to absorption of the alveolar ridge of the alveolar bone wall within two weeks after operation. We observed positive expression of EMMPRIN and MMP-9 in osteoclasts that participated in the absorption of the spire region. Conclusion: Extraction of rat mandibular second molars may help the study of alveolar ridge absorption and preservation. The EMMPRIN-MMP-9 pathway may be a candidate for further study on attenuating bone resorption after tooth extraction.
Article
Purpose There is no consensus in the literature on whether grafting the jumping gap (the distance between the inner surface of the labial bone plate and the implant surface) in immediately placed implants influences the thickness of the labial bone plate. This study aimed to compare the efficacy of particulate bone graft filling material and spontaneous bone healing following blood clot formation when placing immediate implants in the esthetic zone. Materials and Methods A double-blind randomized controlled clinical trial was conducted in a private practice on patients scheduled for immediate implant placement using the vestibular socket therapy between November and December 2019. Participants were assigned to two groups. In Group 1, the jumping gap was filled with a mixture of 75% autogenous bone chips and 25% deproteinized bovine bone mineral (DBBM). In Group 2, the gap was unfilled. The regenerated facial bone thickness was evaluated using CBCT. Measurements were taken at baseline before tooth extraction and 12 months postoperatively. The Mann Whitney U test was used for between group comparisons and Wilcoxon signed-rank test for within-group comparisons. Results Twenty-two patients (8 men and 14 women; mean age, 45.22 years) were randomly assigned to Group 1 or Group 2, with 11 patients each. A statistically significant difference in bone thickness was found between groups (p=0.008). The mean (SD) overall bone thickness was 2.95 (0.97) mm for the particulate bone group compared to 1.45 (0.92) mm preoperatively. While, for the unfilled group, the mean (SD) overall bone thickness was 1.98 (0.56) mm compared to 0.79 (0.49) mm preoperatively. Conclusion The results suggested that, grafting the jumping gap with particulate bone graft when implementing the vestibular socket therapy enhanced the thickness of the labial bone plate of immediately placed implants in the esthetic zone.
Article
The present study was aimed at assessment of the soft tissue condition around immediate implants used to replace periodontally compromised mandibular anterior teeth. A longitudinal study was conducted on 17 functionally loaded immediate implants placed in periodontally compromised sockets at mandibular anterior region. Clinical and biochemical assessment of inflammatory status of peri-implant mucosa were recorded at 2 week, 6and 12-month intervals after loading. Clinical parameters included modified Plaque Index (mPI), modified Bleeding Index (mBI), marginal soft tissue level (ML), Papilla Index (PI) and width of attached mucosa (AM). Biochemical parameter was the levels of Aspartate aminotransferase (AST) enzyme in peri-implant crevicular fluid (PCF). Inter-comparison of observations were statistically analysed using repeated-measures ANOVA. The mean mPI score was 0.71, 0.41 and 0.53 at three intervals (p=0.354) indicating moderate score. The mean mBI was1.06, 0.35 and 0.29 at various intervals (p=0.000), pointing reduced bleeding tendency. Throughout the study, 70.588% of sites had positive ML, suggesting soft tissue stability. Mean PI scores were 1.71, 2.06 and 2.65 and for AM were 2.41, 2.41 and 2.94 respectively at the three intervals, with a statistically significant p-value of 0.000 for both. The mean AST level in PCF was 1876.47 μIU, 1729.41 μIU and 2117.65 μIU (p=0.431), pointing no increase in inflammation. Considering the results obtained, implants under study exhibited no major inflammatory changes in the soft tissue, during the study period.
Article
The mechanical response of the bovine periodontal ligament (PDL) subjected to uniaxial tension and compression is reported. Several sections normal to the longitudinal axis of bovine incisors and molars were extracted from different depths. Specimens with dimensions 10×5×2 mm including dentine, PDL and alveolar bone were obtained from these sections. Scanning electron microscopy suggested a strong similarity between the bovine PDL and the human PDL microstructure described in the literature. The prepared specimens were tested in a custom made uniaxial testing machine. They were clamped on their bone and dentine extremities and immersed in a saline solution at 37°C. Stress–strain curves indicated that the PDL is characterized by a non-linear and time-dependent mechanical behaviour with the typical features of collagenous soft tissues. The curves exhibited hysteresis and preconditioning effects. The mechanical parameters evaluated in tension were maximum tangent modulus, strength, maximizer strain and strain energy density. For the molars, all these parameters increased with depth except for the apical region. For the incisors, all parameters increased with depth except ultimate strain which decreased. It was assumed that collagen fibre density and orientation were responsible for these findings.
Article
studies in humans and animals have shown that following tooth removal (loss), the alveolar ridge becomes markedly reduced. Attempts made to counteract such ridge diminution by installing implants in the fresh extraction sockets were not successful, while socket grafting with anorganic bovine bone mineral prevented ridge contraction. to examine whether grafting of the alveolar socket with the use of chips of autologous bone may allow ridge preservation following tooth extraction. in five beagle dogs, the distal roots of the third and fourth mandibular premolars were removed. The sockets in the right or the left jaw quadrant were grafted with either anorganic bovine bone or with chips of autologous bone harvested from the buccal bone plate. After 3 months of healing, biopsies of the experimental sites were sampled, prepared for buccal-lingual ground sections and examined with respect to size and composition. it was observed that the majority of the autologous bone chips during healing had been resorbed and that the graft apparently did not interfere with socket healing or processes that resulted in ridge resorption. autologous bone chips placed in the fresh extraction socket will (i) neither stimulate nor retard new bone formation and (ii) not prevent ridge resorption that occurs during healing following tooth extraction.
Article
The primary objective of this study was to determine the association between the size of the void established by using two different implant configurations and the amount of buccal/palatal bone loss that occurred during 16 weeks of healing following their installation into extraction sockets. The clinical trial was designed as a prospective, randomized-controlled parallel-group multicenter study. Adults in need of one or more implants replacing teeth to be removed in the maxilla within the region 15-25 were recruited. Following tooth extraction, the site was randomly allocated to receive either a cylindrical (group A) or a tapered implant (group B). After implant installation, a series of measurements were made to determine the dimension of the ridge and the void between the implant and the extraction socket. These measurements were repeated at the re-entry procedure after 16 weeks. The study demonstrated that the removal of single teeth and the immediate placement of an implant resulted in marked alterations of the dimension of the buccal ridge (43% and 30%) and the horizontal (80-63%) as well as the vertical (69-65%) gap between the implant and the bone walls. Although the dimensional changes were not significantly different between the two-implant configurations, both the horizontal and the vertical gap changes were greater in group A than in group B. Implant placement into extraction sockets will result in significant bone reduction of the alveolar ridge.
Article
In previous short-term studies, it was observed that while the placement of biomaterial in alveolar sockets may promote bone formation and ridge preservation, the graft may in fact also delay healing. The objective of the present experiment was to evaluate the more long-term effect on hard tissue formation and the amount of ridge augmentation that can occur by the placement of a xenogeneic graft in extraction sockets of dogs. Five beagle dogs were used. The third mandibular premolars were hemi-sected. The distal roots were carefully removed. A graft consisting of Bio-Oss collagen was placed in one socket while the contra-lateral site was left without grafting. After 6 months of healing, the dogs were euthanized and biopsies were sampled. From each experimental site, four ground sections - two from the mesial root and two from the healed socket - were prepared, stained and examined under a microscope. The placement of Bio-Oss collagen in the fresh extraction socket served as a scaffold for tissue modeling but did not enhance new bone formation. In comparison with the non-grafted sites, the dimension of the alveolar process as well as the profile of the ridge was better preserved in Bio-Oss-grafted sites. The placement of a biomaterial in an extraction socket may modify modeling and counteract marginal ridge contraction that occurs following tooth removal.
Article
The histodynamic response to long-term "non-traumatic" immobilisation was studied in young adult Beagle dogs by means of radiomorphometry and histomorphometry, the right forelimb being encased in plaster and the left forelimb serving as a control. The dogs were killed at two, four, six, eight, twelve, sixteen, twenty, twenty-four, thirty-two and forty weeks and the third metacarpal, radius, ulna and humerus removed for analysis of the contributions of the periosteal, haversian and endosteal envelopes to the bone loss at the mid-diaphysis. The bone mass responded to long-term immobilisation in three stages. First there was a rapid initial loss of bone, reaching its maximum (some 16 per cent of original mass) at six weeks, to which all three bone envelopes, to some extent, contributed. A rapid reversal followed, the bone mass approaching the control values between eight and twelve weeks after immobilisation. A second stage of slower but longer lasting bone loss ended twenty-four to thirty-two weeks after immobilisation; the periosteal envelope was the main contributor (80 to 90 per cent of the total loss). The third stage was characterised by maintenance of the bone mass which had been reduced by some 30 to 50 per cent of original values. This pattern was qualitatively similar in all four bones but the distal bones lost more bone than the proximal bones. The extent of resorption surface and the total histologically "active" periosteal envelope increased parallel to the phases of bone loss. The linear mineralisation rate did not differ significantly between the experimental and control sides.
Article
This paper demonstrates that an intact extraction socket is not necessary for the successful integration of a titanium implant fixture. Several case reports are used to describe the immediate placement of fixtures into compromised sockets, some in conjunction with bone grafting and/or guided tissue regeneration techniques to enhance the surgical result. Advantages of immediate implant placement are threefold: (1) treatment time is significantly reduced; (2) ridge contour can be preserved; and (3) it is possible to place the fixture in a more ideal axial position, thus enhancing fabrication, esthetics, and biomechanics of the subsequent restoration.