Dr . Yousef Abd
Fellow of ICOI and Member of AAID.
The grafts used are either cortical, cancellous or corticocancellous.
The corticocancellous grafts are considered the best to use as they
carry the benefits of both cortical grafts which are rigidity,
stability and higher content of BMPs that will initiate the
osteoinductive process by its release, and the cancellous grafts
benefits by having viable osteobslats and undifferentiated mesenchymal
cells (Misch et al. 1998).
The extraoral autografts are used generally to restore severely
resorbed alveolar ridges. The preferred extraoral sites for autogenous
bone grafts are iliac crest, tibial shaft, rib, and parietal bone of
the skull. Grafts harvested from membranous bone as the cranium have
faster revascularization than grafts harvested from endochondoral bone
(Kusiak et al. 1985).
Although iliac crest is the most common extraoral site used to harvest
bone for purpose of augmenting anatomically compromised alveolar
ridges, patients still describe considerable pain and walking
difficulties post-operatively. Harvesting from tibial shaft is
considered to be a relatively fast and complication free procedure.
Donor site morbidity was much less than iliac crest when using tibial
shaft trephined grafts (Ilankovan et al.
The main advantage of intraoral bone grafts is their convenient
surgical access. The close proximity of donor and recipient sites can
reduce operative and anesthesia time with avoidance of general
anesthesia, making them ideal for implant surgery. Another advantage
is that there is no visible external scar. In addition patients report
minimal discomfort and these areas may offer decreased morbidity from
graft harvest. Also, bone harvested from intraoral sites is associated
with less resorption when compared to iliac crest, tibial shaft, and
rib grafts. The only disadvantage of intraoral grafts is that there is
less bone available than from extraoral sites (Misch
and Misch 1998).
Intraoral sources of autogenous bone grafts include edentulous spaces,
maxillary tuborosity, mandibular ramus, mandibular symphysis, and
extraction sites. Bone from a recent extraction site (within 6-12
weeks) may have advantage of increased osteogenic activity as compared
with other sites. The maxillary tuborosity provides a more cellular
source of autogenous bone as compared with other sites. However, the
trabecular nature of this site provides a lesser quantity of
mineralized matrix and the resultant total volume of bone available
for grafting is often inadequate. For greater amount of bone, it is
more desirable to harvest bone from the mandibular ramus or symphysis
(chin). The bone grafts obtained from mandibular ramus and symphysis
are typically more cortical which can be harvested and used as a block
graft or ground or shaved into small fragments and used as a granulate
graft (Newman et al. 2002).
study was performed to compare intraoral donor sites for onlay
grafting prior to implant placement. The choice of donor site, either
symphysis or ramus, was determined preoperatively based on defect
morphology and recipient site location. The ramus grafts gave rise to
no complications in comparison with symphysis graft, however the
procedure is more difficult, with restricted access and risks to
inferior alveolar nerve need to be considered
The morbidity of donor site for autogenous bone grafts harvested from
symphysis region was investigated. The osteotomies were accomplished
with the use of trephines to obtain corticocancellous grafts, or thin
carbide burs to obtain individually shaped monocortical bone grafts.
Some complications were observed with group of patients who were
subjected to harvesting of bone procedures from the chin such as,
bruising at the lower face (100%), bruising of the upper neck (12%),
and paresthesia (15%) (Dennis et al. 1999).
The timing of graft placement is either prior to the placement of
implants (staged approach) or simultaneously with the implants
(combined approach). The staged approach method is primarily chosen in
situations with large bony defects. The main advantages of placing the
implants after graft maturation are better graft evaluation and
appropriate implant selection; decreased time required for the initial
surgical stage and a more accurate surgical template can be
constructed on the improved underlying bone for better site selection
and implant angulation. The combined approach method offers some
advantages such as decreased patient morbidity, decreased treatment
time, and decreased costs (Misch and Dietsh
The autografts may be used as corticocancellous block or
corticocancellous granulates. The extent of osseointegration of
implants in corticocancellous blocks was less than it was in
corticocancellous blocks. Also, the bone granulates showed better
adaptation to the receptor site and lower rate of graft resorption.
Using bone blocks alone showed high rate of graft resorption and graft
rejection was also reported in some cases (Lew
et al. 1994).
defects adjacent to dental implants can be grafted with small
autogenous bone granulates, which results in significant improvement.
In a study of Becker et al. 1994, the initial mean vertical
defect depth was 5.7 mm, and the average residual depth at second
stage surgery was 0.03 mm. These changes were statistically (p<0.001)
significant and clinically relevant.
osseous defects adjacent to oral implants have been successfully
treated with intraoral autogenous bone alone, there is lack of
evidence as to the ultimate fate of these bone grafts. Some authors
claimed that using the grafts alone in treating peri-implant defects
may lead to graft resorption, also loss of graft or even incomplete
defect coverage may occur. (Curtis and Ware 1983).
The development of guided bone regeneration (GBR) has substantially
influenced the possibilities for using implants. The use of bone
augmentation procedures has extended the use of oral implants to jaw
bone areas with insufficient bone volume. The treatment of alveolar
defect conditions through guided bone regeneration (GBR) is a
treatment modality that provides clinicians with the possibility of a
successful outcome and diminishes the complications associated with
the graft itself (Dahlin et al. 1989).
Numerous publications have indicated that guided bone regeneration (GBR)
is a viable method for enhancing bone formation in peri-implant
defects (Becker et al. 1992, Kohal et al.
1999, Nemcovasky et al. 2000, Hämmerle and Lang 2001, Rosen and
Reynolds 2001, Brunel et al. 2001, and Dogan et al. 2003).
Regeneration may be defined as a biological process by which the
architecture and function of the lost tissues are completely renewed.
In periodontal therapy,
guided cell repopulation, or guided tissue regeneration (GTR),
describes procedures designed to manipulate the cells that repopulate
the wound healing site to ensure that this repopulation includes cells
that lead to regeneration (American Academy
of Periodontology 1992).
GTR (guided tissue regeneration) had been developed, based on the
principle of guiding the proliferation of the various periodontal
tissue components during healing following periodontal surgery using
membrane barriers (Gottlow et al. 1986 and Caffesse et al. 1988).
These membranes were used to prevent apical migration of the gingival
epithelium and the connective tissue fibroblasts along the root
surface and to create a space over the defect to allow the remaining
periodontal ligament and alveolar bone cells to selectively repopulate
the root surface (Nyman et al. 1982).
Guided tissue regeneration (GTR) therapeutic modalities had led to the
development of the principle of guided bone regeneration (GBR), which
aims at regeneration of alveolar bone defects around dental implants.
Guided bone regeneration can be of value in restoring
horizontal and vertical alveolar ridge defects, treating dehiscence
and fenestration defects associated with implants and in obtaining
bone fill associated with immediate post-extraction and failing dental
implants (Parodi et al. 1998).
The application of GBR for improvement
of dental implants prognosis may take several forms. One form is a one
phase treatment of implant bed preparation, in which the implant is
surgically placed at the same time as GBR (Buser et al. 1993).
Another form is two phase treatment, in which surgical implant
placement is performed after the GBR procedure, when new bone has
matured (Buser et al. 1996). Other treatment forms include
repair of bony peri-implant defects secondary to advanced forms of
peri-implantitis (Francisco et al. 2001).
Successful clinical outcomes can be obtained if the used GBR barrier
membrane possesses certain requirements: 1) Cell exclusion: Certain
cells must be excluded from the area targeted for regeneration. The
used barrier membrane should prevent gingival fibroblasts and/or
epithelial cells from gaining access to the wound site and forming
fibrous connective tissue. 2) Tenting: The membrane is carefully
fitted and applied in such a manner that a space is created beneath
the membrane, completely isolating the defect to be regenerated from
the overlying soft tissue. To accomplish this tenting function and to
completely isolate the defect, it is important that the membrane be
trimmed so that it extends 2-3 mm beyond the margins of the defect in
all directions. 3) Scaffolding: The cells will come from adjacent bone
or bone marrow occupying the tented space which serves as a scaffold
for the ingrowth of progenitor cells. 4) Framework: In non-space
maintaining defects such as dehiscences or fenestrations, the membrane
must be supported to prevent collapse. Bone-replacement grafts
consisting of autografts, allografts, xenografts, alloplasts, or
combinations of these materials are often used for this purpose.
Stiffer membranes such as titanium-reinforced membranes have also been
used for this purpose. 5) Stabilization: The membrane must also
protect the clot from being disturbed by movement of the overlying
flap during healing, so the membrane should be fixed in place by
retentive means including sutures, mini bone screws, bone tacks, or
fixed by the covering screws of the implants. Sometimes, the edges of
the membrane are simply tucked beneath the margins of the flaps at the
time of closure (Hardwick et al. 1994 and Lang et al. 1999).
There are two main classes of membranes that can fulfill the above
mentioned requirements, the non-resorbable and the resorbable
membranes. Non-resorbable membranes are barriers that are not degraded
by the tissue. They are placed underneath the flap and removed one
month later by re-entry procedure. The non-resorbable membranes are
numerous. They include expanded polytetraf-luoroethylene (e-PTFE),
titanium reinforced (e-PTFE), titanium mesh, and titanium foil.
Expanded polytetrafluoroethylene (e-PTFE) was used to enhance the
regenerative potential in periodontal defects. The (e-PTFE) may
provide protection to the blood clot and prevent apical migration of
junctional epithelium. Many studies have used (e-PTFE) barriers and it
was claimed to be the current standard in the field of (GBR), but
there has been a drawback associated with the use of this material
which is the need for secondary surgery for membrane removal
et al. 1994).
Micro titanium mesh was also used to protect and stabilize autograft
in place to treat dehiscence and fenestration bony defects around
dental implants. This was described in a study by
Von Arx and Kurt 1998
6 patients requiring bone augmentation. Resorption of
graft varied from 0 to 8% of the total graft height. It was concluded
that the use of a micro titanium mesh has been shown to provide the
combined space maintenance due to its improved mechanical strength,
and it may be left over the long-term due to its inherent
bone regeneration using titanium foil was evaluated in a study by
Gaggle and Schultes 1999. Forty-two patients with deep intra
alveolar peri-implant defects were treated by means of a titanium
foil-guided bone regeneration technique. Autogenous bone in
combination with DFDBA composite was used for augmentation. Clinical
and radiological control was performed 3, 6, and 12 months after
surgery. In 37 cases, the average 12-month postoperative increase in
bone was 4.2 mm, and the decrease in augmented bone was only 4%
compared with the postoperative situation. The main problem with foil
loss was denudation and infection 6 weeks after surgery.
The non-resorbable barriers showed high
rate of complications such as exposure to the oral environment i.e.
soft tissue dehiscence, with subsequently developing infection.
Frequently, exposure rates may affect around 20% of the sites treated
with a major negative effect on GBR around dental implants (Machtei
2001). Simion et al. 1994 reported significantly less bone
gain when the membranes were exposed compared to non-exposed membrane
treated sites (41.6% versus 96.6%). Impaired treatment outcomes, lack
of predictability of the therapy and resorption of the already
regenerated bone or even loss of parts of the pre-existing bone have
been also reported as sequelae of these complications (Hockers et
To overcome the previously mentioned complications associated with
non-resorbable barriers, as well as to obviate the need for a second
surgery needed for membrane removal; various resorbable GBR materials
have been evaluated.
Researches in the field of barrier membranes have focused on the
development and application of suitable resorbable materials for GBR
- A basic Comparison between Er:YAG and Er,Cr:YSGG
DDS, MSc, PhD
Assistant Prof. ZPP,
RWTH Hospital, Aachen, Germany
When the Hibst and Keller have published the first articles about the
ablation of tooth with Er:YAG laser on 1989 in English journals (some years
after German versions), nobody was estimating that in 8 years the speed of
cut (Volume of ablation) could be practically
suitable for dental daily needs. On that time the 4-6 pulses per second were
recommended and the laser was cutting the tooth very slowly. On 1995, the
number of pulses increased to 20 and Er,Cr:YSGG was also introduced to
American dental society on 1997. At the same year both wave lengths were
successfully cleared with FDA and delivered to dental clinics to be used
as an adjacent to drills!
On 2000, the discussions about the basics of mechanisms were hottest topic
of dental congresses and WATER role was under the focus of investigators. On
2002 a basic study started by the author in Aachen RWTH Hospital following
the advance advises of Prof.Dr. Norbert Gutknecht and guidances of Dr. Leon
Vanweersch, Dr. Joerg Meister and Dr. Rene Franzen.
The project was done with the help of two HIGH TECH cameras. First one was
able to make up to 40500 pictures per second. So, as is seen in Figure-1,
the author was able to monitor any pulse (with a length of 140-180
microseconds) with looking at about 30 pictures. Therefore, the accurate
interactions between laser light, water and enamel were accurately
Both wave lengths of 2780 nm (Er,Cr:YSGG) and 2940 nm (Er:YAG) were
irradiated in a distance of 1 mm in front to the enamel surface. The water
selected as the media between laser tip and tooth. By this method, the
different phases of any pulse interactions with first micrometers of water
layer at the start of pulse were reported. There was no difference seen
between two wave lengths not only at start of pulse, but also in the rest of
The most important finding is that the basics of ablation with both wave
lengths are more and less the same and the important characters of both in
increasing the speed of cut would be the duration of pulses and energy of
any pulse, as well as suitable amount of water between the laser irradiating
tip and tooth surface.
This research have been presented in 2nd international congress of Laser
Dentistry in Dubai on 11th January 2007 by the author and is IN PRESS in one
of the high rank ISI indexed scientific journals. For more information the
interested persons could kindly write to:
As a conclusion could be addressed that there are enough evidence which show
30 pulses per second of both wave lengths with a pulse energy of 300 mJ and
pulse length of 60-90 microseconds, could cut the enamel even faster than
high speed drills. The accuracy of cut margins with NON-CONTACT laser
handpieces could be comparable also for preparing the
bevels and shoulders in the aim of Veneer, Inlay and Onlay, or crown and
Our master students are using this applications daily and we present the
clinical procedures world wide by video online lectures as you could see in
Figure-2. It is the wish of author to be able in near future make the direct
video conference presenting live cavity preparations with same methods for
the Indian friends as well. The ideas are most welcome and the positive
and negative comments are open to be discussed in the dental forum of this