CHAPTER TWO: THE THEORY AND PRACTISE OF ORAL
IMPLANTOLOGY USING MOSTDIS
GENERAL THEORY
The
basic requirements of successful oral implantology is caricatured as follows:-
(a)
Titanium: It has been proven through the years that titanium is eminently
biocompatible to the human body. The surface layer of titanium dioxide is able
to form an intimate bond with living bone in the right circumstances. This bond
may be either biological or mechanical or both.
(b)
Sterilility: The implant must be sterile
when placed to prevent infection and to allow an intimate bone implant contact
to develop.
(c)
Atraumatic Placement: The less trauma to the bone, the smaller the inflammatory
response and the more likely osseointegration will take place uneventfully.
(d)
Covered Healing: Again this will decrease the possibility of infection.
(e)
Retrievability: The principle of retrievability was achieved by using screws to
retain the crown and bridges. Screws were used so that the bridges and crowns
were easily retrieved by exposing the screws and unscrewing them.
Retrievibility was emphasized by the professor during that pioneering period so
that if any complications arose around the implants, the crowns and bridges
would be swiftly and reversibly removed in order to eyeball the complications
and treat them. Briefly, it was to prevent the implants from being hot,
hidden and hazardous. Thus, the dental implants and its immediate
surrounding tissues were made cool, accessible and therefore safe.
With
the advent of mini implants, the principle of retrievability became a problem.
The mini-implant was too small to fix a screw on and cementation would mean
great difficulty in removing the crowns and bridges. Temporary cementation
usually resulted in the crowns and bridges coming loose in a short time.
Permanent cementation would mean having to cut through the thick metal of the
crowns and bridges if there arises a need to retrieve them. The metal is thick
because the mini-implants have small diameters and therefore a lot of metal and
porcelain had to be used to bulk up the prosthesis to the correct sizes.
HISTORY AND PROGRESS OF
MINI DENTAL IMPLANTS
Mini-implants
alias small dental implants alias reduced diameter implants alias MOSTDIs were
first used to stabilize dentures and transitionals while waiting for implants
to osseointegrate. In recent years however, they are increasingly used very
successfully in supporting crowns and bridges. If the trend continues, minis
will become the main work horse in dental implantology. It is not inconceivable
that in 10 years or so, dental implantology especially MOSTDIs will become a
regular part of undergraduate dental training. (MOSTDIs stand for Minimized Osseointegrated Titanium Screw Dental
Implants and for the purposes of this book we will mainly use this term from
hereon)
This
is because of the realization that dental implantology has so revolutionized
every field of dental treatment, be it restorative, prosthodontic, endodontic,
orthodontic, oral surgery, etc. Optimal dental care would not be complete
without including dental implantology into the treatment planning. With
MOSTDIs, dental implantology has become simpler, cheaper and with a much
smaller learning curve than conventional sized dental implants, which we will
refer from now on as COSTDIs. It must be added that MOSTDIs are also much more
forgiving when complications arise because they are small and once removed, the
bone and mucosa grow back much more rapidly than in the case of COSTDIs. (COSTDIs
stand for Conventional Osseointegrated Screw Titanium Dental Implants).
The
change will speed up considerably as prosthodontic solutions designed
especially for MOSTDIs are invented and disseminated. In this book, I will
present in some detail the possible prosthodontic solution for MOSTDIs that
will keep the critical margins of soft and hard tissues around the neck of the
implants cool, accessible and safe
as opposed to hot, hidden and hazardous.
This will also help to overcome the challenge of retrievability of crowns and
bridges when MOSTDIs are used.
HARD TISSUE
Hard
tissue in implant dentistry refers to the bone. Generally, the bone in the
maxilla is softer than the bone in the mandible. The hardness of the bone also
varies within the same arch. The bone in the anterior of the maxilla is usually
harder than that of the posterior and vice versa in the mandible. Hardness of
the bone depends on bone density, i.e. the degree of calcification of the bone.
Bone is divided into cortical bone that forms the outermost layer of bone which
is hard and cancellous bone which is the bone encased by the cortical bone and
is softer. The cancellous bone also varies in hardness within the same jaw. For
the practical purposes of preparing the bone hole or osteotomy for receiving a
dental implant, bone quality is classified into D1, D2, D3 and D4 bone, in
descending hardness. The hardest is D1 and the softest is D4. The hardest will
be more difficult to drill and must therefore be drilled slower with plenty of
irrigation to prevent overheating the bone. The harder the bone will require
the size of the bone hole to be closer to the size of the final implant,
whereas in soft bone, the bone hole can be smaller.
SOFT TISSUE
Soft
tissue in the mouth for the purpose of placing dental implants will refer mainly
to the mucosa overlying the alveolar ridge where the missing tooth or teeth
were. This mucosa will be usually attached mucosa in that the epithelium is
directly attached to the periosteum of the bone. Attached mucosa is where it is
advised that the dental implant should be placed so that it will most simulate
the natural tooth and will be easier to clean. Unattached mucosa will be loose as there is a layer of
connective tissue between the epithelium of the mucosa and the periosteum. A
dental implant emerging through unattached or loose mucosa is thought to be
more prone to plaque formation and more difficult to keep clean.
OCCLUSION
A
preliminary assessment of the patient’s occlusion is paramount to the long term
success of dental implants. Is the occlusion overclosed, open, deviating, have
premature contacts? Is the patient suffering from bruxism. All these have to be
considered together with the final treatment plan. The more teeth the patient
has lost, the more important this process of treatment planning is.
