Dr . Yousef Abd
Fellow of ICOI and Member of AAID.
osseointegrated implants has been validated over the past 30 years as a
viable alternative to fixed or removable prosthetic restorations. An
increasing number of well-controlled longitudinal studies have demonstrated
that osseointegrated oral implants are a predictable therapy for the
replacement of missing teeth (Rutar et al. 2001). Tooth
restoration using implant-supported prosthesis for functional and esthetic
rehabilitation has become an established and widely used treatment modality
in dentistry ( Von Arx et al. 2001).
Dental implants are one of the fastest growing dental
technologies of the 21st century. Millions of people scanning the
globe are recipients of this fascinating development, ranging from its most
primitive stages to latest inventions. Phenomenally, many of these
individuals function day to day without anyone they encounter ever realizing
that they are not looking at the patient’s natural dentition. In fact, these
patients may even forget that they are functioning with an implant. Implants
have also been a blessing to countless numbers of denture patients that
became fed up with their dentures which are easily and embarrassingly
dislodged. Now their implant supported dentures remain secured, putting the
patient at ease (Iacono et al. 2000).
breakthrough in implant dentistry was initiated by the discovery that dental
implants made of commercially pure titanium can be anchored in the jawbone
with direct bone contact by means of osseointegration (Buser et al.
implants were defined as a biomedical device composed of an alloy placed in
or within the osseous tissue with the goal of restoring masticatory function
and esthetics (American
Academy of Periodontology, 2000).
Osseointegration was discovered in the 1950s by Swedish
bioengineer Per-Ingvar Bränemark. He realized that after implanting titanium
cylinders into the femurs of rabbits, he could not extract the titanium
without destroying the surrounding bone. The discovery that bone will
integrate with titanium components, not rejecting the element as does other
materials, was the beginning of the study of osseointegration.
Osseointegration was originally defined as a direct
structural and functional connection between ordered living bone and the
surface of a load-carrying implant. It is now said that an implant is
regarded as osseointegrated when there is no progressive relative movement
between the implant and the bone with which it has direct contact. In
practice, this means that in osseointegration there is an anchorage
mechanism whereby non vital components can be reliably and predictably
incorporated into living bone and that this anchorage can persist under all
normal conditions of loading (Bränemark
et al. 2001).
osseointegration, adequate bone volume must be present during surgical
placement of the implant fixture to keep it stable during the initial
healing phase. Clinically, many situations deviate from the ideal common
such as inadequate bone circumference at the crestal aspect of the fixture
or a thin shell of cortical bone that may fracture away from part of the
fixture, offering little potential for integration at this site (Spiekermann
At the time of implant placement, anatomic bone deficiencies
will result in exposed implant surfaces, reduced bone-to-implant contact,
and as a consequence, compromised results varying from early implant
failures to late peri-implant infections (Newman
and Flemmig 1988).
Clinical studies have clearly demonstrated that the success
rate of Bränemarkimplants is compromised in areas of poor bone quality or
in those with good quality but inadequate bone height and
the long-term prognosis of dental implants is adversely affected by
inadequate bone volume at implant recipient sites
(Engquist et al. 1988 and Jaffin et al. 1991).
of implants in sites where the bone volume is equal to or less than the size
of the implant results in part of the implant surface not being covered by
bone, with possible peri-implant soft tissue irritation, decreased
bone-implant contact surface, and potential implant failure. A minimum
buccolingual width of 5 mm is recommended for placement of implants without
undesirable complications (Boyne et al.
2001 and Allum et al. 2002).
adequate bone volume at the implant site is a prerequisite for good esthetic
outcome. Alveolar deficiencies can often prevent ideal implant placement.
Furthermore, the gingival margin and papillae, which contribute to the
esthetic outcome, are dependent on support from the underlying vital bone
(Sethi and Kaus 2001).
common complication associated with placement of implants in narrow alveolar
ridges or in an ideal position for esthetics are dehiscence and fenestration
defects (Dahlin et al. 1995). An implant dehiscence is
defined as exposure of the implant surface from the top of an implant head
to the point where the implant is totally covered by bone (Jovanovic
et al. 1992). An implant fenestration or window of exposed implant
surface results from either insufficient buccolingual alveolar width or
inadvertant misdirection of implant placement (Lindhe et al. 1998).
implant supported dental restorations in patients with limited bone volume,
augmentation or rebuilding of the alveolar ridge must be performed. The
final objective is to restore or preserve the height, width, depth
(quantity), and quality of the bone for dental restoration (Brugnami
et al. 1999).
experimented augmentation of bone deficient recipient sites by various means
to achieve sufficient bone volume around the dental implants, including bone
grafting alone (Misch and Dietsh 1994, Lew et al. 1994, Misch 1997,
Verhoeven et al. 1997, Hall et al. 1999, and Van Steenberghe et al. 2003),
use of barrier membranes alone(Sevor et al. 1993, Schliephake et al.
2000, Francisco et al. 2001, and Oh et al. 2003), or combined use of
both bone grafting and barrier membranes (Hockers et al. 1999, Carpio
et al. 2000, Brunel et al. 2001, Rosen and Reynolds 2001, VonArx et al.
2001, Tawil et al 2001, and Zahran and Al-Shirbiny 2003). Other
means for placing implants in bone deficient recipient sites was also
investigated including ridge expansion (Scipioni et al. 1994),
distraction osteogenesis (Oda et al. 1999), sinus elevation,
tuberosity and pterygoid implants and zygoma fixtures (Balshi and
Wolfinger 2003), and last but not least nerve lateralization (Garg
and Morales 1998).
and their substitutes are evaluated from an understanding of the mechanism
of bone formation processes which include osteogenesis, osteoinduction
The cellular elements within a donor graft, which survive
transplantation and synthesize new bone at the recipient site.
New bone realized through the active recruitment of host mesenchymal
stem cells from the surrounding tissue, which differentiate into
bone-forming osteoblasts. This process is facilitated by the presence of
growth factors within the graft, principally bone morphogenetic proteins (BMPs).
The facilitation of blood-vessel incursion and new-bone formation into a
defined passive trellis structure.
All bone graft
and bone-graft-substitute materials can be described through these processes
(Greenwald et al. 2001).
The autograft is tissue from one person or animal that is transferred from
one portion of the body to another. The allograft is tissue that is
transferred from one individual to another individual of the same species.
The xenograft is tissue that is taken from animals and transferred after
processing to an individual of a different species
Alloplasts or synthetic bone substitutes are synthetic commercially
available bone substitutes which can also be used as a grafting material
around implants (Hall et al. 1999).
At the present
time it is very popular to use a plasma product by spinning down blood from
the patient to obtain a platelet-derived growth factor (PDGF) which can be
mixed with other osseous graft materials and placed in the defects around
implants to restore alveolar bone. The platelet-derived growth factor may
assist in the healing of soft tissues of the alveolar ridge, so it may
eventually affect the overall osseous healing, but it is less effective in
the formation of bone than BMPs. An advantage of platelet-derived growth
factor is that it can be taken from the same patient and simply given back
to the patient as an autogenous graft material (Becker et al. 1992 and
bone grafts are considered to be the gold standard for bone grafts as it is
the most predictable material that possess both osteoconductive and
osteoinductive properties. They stimulates non-differentiated mesenchymal
cells to form new bone ingrowth with no risk of disease transmission.
Moreover, they do not induce an immunologic reaction (Al Ruhaimi
2001). Autografts show higher bone-to-implant contact more than
other bone grafting materials with minimal or no fibrous tissue between the
newly-formed bone and the implant surface in regenerated defects around
implants (Hockers et al. 1999).
such as freeze-dried bone allografts (FDBA) and demineralized freezed dried
bone allograft (DFDBA) are used to treat bony defects with its success
attributed to its osteoinductive potential (Hall et al. 1999).
Freeze-drying of bone allograft material markedly reduces the antigenicity
of the allograft. Animal studies indicate that demineralizing bone
which is followed by freeze drying, significantly enhances the osteogenic
potential of the allograft, supposedly by exposing the "bone morphogenetic
proteins" (Blumenthal and Steinberg 1990). Bone morphogenetic
proteins (BMPs) are natural proteins which are primarily morphogenetic in
nature, changing the stem cells directly to osteoblasts to initiate bone
formation and the regeneration cascade (Cochran et al. 2000 and
Hanisch et al. 2003).
studies suggested that the quantity of BMP in allografts was too small to
induce bone formation. The quantity of the BMPs is also variable according
to the age of the donor (Spampata et al. 1992 and Schwartz et al.
used for their osteoconductive potential but they lack osteoinductive
potential. Xenografts have many types according to their source of origin,
such as bovine (BioOss), porcine, equine, and coralline xenografts. Pep
Gen-15 is a natural, anorganic, microporous, bovine-derived hydroxyapatite
bone matrix which was used in combination with a cell binding polypeptide
that is a synthetic clone of the 15 amino acid sequence of type І collagen.
The addition of the cell binding polypeptide was shown to enhance the bone
regenerative results (Yukuna et al. 2000). Xenografts are also
manufactured from calcifying marine algae named coralline officinalis (Frios
Algipore) (Schopper et al. 2003).
were used extensively in Europe as the law is still uncertain about the use
of allografts due to the hazards of disease transmission through donor
cadavers. Nonetheless, it was reported that some dangerous diseases such as
bovine spongiform encephalopathy could be theoretically transmitted to the
recipient patient (Sogal and Tofe 1999).
include different types of alloplastic materials commercially available as
nonporous dense hydroxyapatite, porous hydroxyapatite, beta tricalcium
phosphate, and HTR polymer (a calcium layered polymer of
polymethylmethacrylate and hydroxyethylmethacrylate) (Gross 1997).
Bioactive glasses could be used also as bone substitutes. Bioactive glass
was initially introduced to dentistry as a method of filling osseous
defects. This biocompatible material is composed of 45% SiO2, 24.5% CaO,
24.5% Na2O and 6% P2O5 (Cordioloi et al. 2001). However,
bioactive glass alloplasts have a limited criterion of success to be used
with dental implants. Histologically, alloplasts acted almost as
biocompatible fillers, induced little bone fill and were encapsulated by
connective tissue (Yukuna 1994).
Autogenous bone grafts can be obtained either from extraoral
sites or intaroral sites. Several methods were developed to obtain
autografts such as monocortical graft splitting using burs, microsawing
disks and chisels, trephining (Dennis et al. 1999), scraping,
cancellous bone and bone marrow excavation, bone collectors (Kainulainen
and Oikarinen 1998), laser microsawing (Frentzen et al. 2003),
and piezoelectric devices (Varcelloti 2000)...
to be continued in next issue
Career Options in Dentistry
SUNY at Stony Brook NewYork
I have always believed that every specialization is
good in itself, having its own share of uniqueness and a person can be the
best in just any field he is in by commitment and hard work. Like any other
dental graduate I had this time in my life when deciding on what I do after
my graduation was a big question. This has been quite a perennial question
in all the freshly graduated students. With so many specialization to choose
from and with the options of general or specialized practice one is left
quite confused what to do and whom to ask for guidance. Let me try to
address various career options available to a dental graduate.
1) Academics: One can choose to be in academics being a full time
academician. This is possible after any specialization (i.e. periodontics,
prosthodontics, etc..), one can be a full time faculty in the department of
his /her field of specialization. An additional PhD would be helpful for a
full time faculty.
2) Basic research: A good training in basic research is necessary and can be
attained with a good masters or PhD program. Additional training can also be
obtained by working as post doc in specific areas of interest. Areas such as
biomaterials, immunology, microbiology are few areas one can look into but
generally the field of research vastly depends on ones own interest. Basic
research mainly deals with research carried out in the lab setup or studies
on animal models or epidemiological studies. Basic research is always in
demand and is the cornerstone for all the new techniques and new materials
3) Clinical research: A specialization in any particular field with
additional training in research is necessary. This field basically deals
with clinical testing of the materials discovered/invented in the lab (basic
research). Translation of the results obtained in the lab setting into a
clinical setup, for example, testing various bone graft materials already
tested in animals on to human subjects ,looking for efficacy of drugs, or
testing different tooth implant systems in a clinical setting. This is a
very interesting field especially to those who are good clinicians and are
inclined towards research. Specialized program for training in clinical
research are also available.
4) General or specialized private practice: This is possible with either a
DDS/BDS alone or with additional specialized training in various fields
respectively. Various centers and institute provide specialized training in
implants, cosmetic and esthetics dentistry, endodontics and others which
span from few days to few weeks or a year. Such training helps those
candidates who are not much interested in a masters program but want
additional knowledge to start their own specialized dental office.
5) Combination of the above: Few individuals who are good at multitasking do
try this by being a part time academician and part time into private
practice. Also the other combination which usually works out is being a
academician and researcher. These combinations can often be rewarding as
they help being adjunctive to each other and also keep out boredom of a
single routine job.
6) Private Sector: Those who are not into the usual dental jobs and have a
eye for change can sign up for business school. Now what am I talking about?
Well a master in business administration will help you to join the private
sector as a consultant for various industries dealing with dental materials/
dental consumer products. A master in hospital management/ public health may
help you to work at administrative position in various hospitals. Those
interested in research in private sector can think of working in industries
with clinical testing various dental materials and dental consumer products
with a PhD or good research experience at hand. Many companies hire people
as clinical research coordinators who overlook the clinical trials, or as
product development associates to help plan new product design and to
conduct testings and trials.
7) Organisations and Goverments: Masters in public health would help those
interested in epidemiologic studies or taking up jobs which include making
strategies to combat disease and helping governments and non government
agencies plan and induct preventive programs. They also have options of
joining agencies like WHO or various UN agencies.
The various options to the dentist in so many different countries are
limited and these graduates look to continue their future studies in
countries like USA and UK. I have received so many emails asking for the
procedure to get into US dental schools. Let me try to briefly sum up few
steps in how to go about it.
The first thing to be understood is that you need to get license to practice
in US, most of which can be learned by visiting the ADA website (http://www.ada.org/prof/prac/licensure/us.asp).
All international dental graduates (other than from US and Canadian dental
schools), are required to complete an additional 2-3 years of DDS training
in a US dental school. The list of the dental schools can be found on the
ADA website (http://www.ada.org/prof/ed/programs/search_ddsdmd_us.asp)
and the requirements of each university mentioned on the respective
websites. Ideally you would need your TOEFL scores, 2-3 letters of
recommendations and statement of purpose and national board examination
scores (http://www.ada.org/prof/ed/testing/natboard/index.asp). The other
important thing to be noted is that the fees for the dental schools vary
between 60,000 – 85,000$ per year and financial aid to foreign dentist in
form of scholarships/stipend is mostly not available and other financial
aids are very limited, the exact details of this can be found on the
university website. More information can be also found on
Many students initially join the masters in public health/oral biology, this
also helps them adjust to US and to prepare for the national board exams.
Kaplan used to provide I-20 to students who enroll for their national board
examination training, which students can use to apply for the F-1 visa. This
has been very recently stopped, you can find more of it on this groups (http://groups.msn.com/dentalsurgery/general.msnw). A good
score in NBDE exams is essential as there is a very stiff competition for
the limited seats of the Advanced DDS program for the international
Those wishing to go in for PhD need to submit your GRE scores, TOEFL scores,
recommendation letters and statement of purpose. Mostly the PhD students are
paid a monthly stipend and have the tuition fees covered by the
university/department. You need to decide which university you want to apply
by looking in to each university website and finding out if research in area
of your interest is been carried out in that university. Also important is
to find out if that particular professor with whom you want to work has an
approved grant and is willing to sponsor you, and this can be found by
looking up the university website and/or by directly contacting the
professor. These are few of the pre requisites of an application. Most
universities offering doctoral studies can be found on
Wishing every aspirant the very best!
India International Dental Congress -Mumbai
,India Feb 23rd to 25 2007
Could what we see in our CLINICS be EVIDENCE?!
DDS, MSc, PhD
Assistant Prof. ZPP,
RWTH Hospital, Aachen, Germany
the Dental Clinicians, when hear about a new equipment, just buy it and try
it! If works well will take the advantage of treatments assisted by that,
but if does not work well?! Who is responsible for the troubles and side
first Endo Rotary files were introduced to the market, one Endodontist
friend of me bought a Japanese one and at the first week all files of the
kit were gifted to the patient's teeth canals, because of mishandling of
machine! I mean they were all broken inside the canals and he left them
professor, from the first day told me very serious that please take
photograph from all the phases of procedures that you will do with laser. I
started with normal digital cameras and for any patient made a FOLDER in my
computer. After three years, we had a collection that could show us the
success rate of a variety of methods we applied in practice. I was very
happy that felt proud of having such a back bone for what I daily do.
Parallel to these Folders, some thing about 500 articles were also
automatically colleted in my computer, from different aspects of Laser
Applications in Dentistry! I was looking for a way to bring my knowledge and
CLINICAL experiences together and could build up a CROWN out of them to be
the BASE of my professional work kingdom.
November 2005, again the Professor asked me for a short talk and informed me
about an Event?! He told me that 16 of the Pioneers of Lasers in Dentistry
are invited to come to our university for making a professional congress"
Evidence Based Laser Dentistry”.
really surprising for me and it was my duty to collect all of the papers and
classify them in different orders to make them able to have fast access to
any literature they wish during the congress.
It was a
three HARD days’ work, from 8 AM till 5 PM, just one hour lunch break for
eating some thing LIGHT. I was mostly helping all of the professors to find
the right articles form our DATA BANK. Also, it was a part of my duty to
help to Prof. Dr. Ishikawa (Tokyo, JAPAN) and some other professors in
writing the conclusion out of all the papers in any field.
learned more that what was estimated and could feel that know nothing and
need to do active research for a long time to have some EVIDENCE only in an
small part of Dentistry while applying lasers!
professors read, discussed and wrote gave me new concepts and they are yet
after one year discussing to complete the work and I wish that the
collection be published till end of year by QUINTESSENCE. The book is called
“Proceeding of First congress of Lasers in Dentistry”.
Dr.Maziar Mir working on a patient
back to the CLINIC, we are not anymore bothering the patients for taking
photographs and now use a microscope and record all the procedures we do on
DVD. These clinical treatments now are based on the GOVERNMENT of EVIDENCE.
We are looking forward to collect more and more INFORMATION and produce more
and more knowledge and gift them to all dentists all around the world.