Stereolithography:
1. Used in complicated cases usually (like resoroped bone), because we
can’t plan dental implant theoretically unless we have detailed image
about alveolus so we can avoid perforation of bone plate or nerve and
other consequences that we won’t.
2. Not used in simple cases where enough ridge width and height
because we have here safety margin. Here we use conventional way.
3. Give us detailed image.
4. Very precise dental implant.
Technique:
You take CT scan and produce sterolithograph(3D model or printing)
As an example (bottle put it in 3D laser machine then by software print it
as a wax model) this the concept of stereolithography.
We can use it in surgery of skull to facilitate the surgery like broken orbit
on one side but other side is sound so we can use sound one to do
template for the other.
Now in dental implants we use CT scan image and by software program
we can put treatment plan for your implants (length, diameter, site,….)
and you can put prosthetic part to see end result. Once you finish that you
can print your trt plan ,now you can prepare surgical template (acrylic)
on this final model.
Surgical guide it’s look like night guard but here with cylindrical holes.
Why cylindrical? To prevent inclination for twist drill so prevent
perforation for lingual plate for example. Surgical guide should be fit on
final model.
The problem of stereolithograhy or computer assisted treatment plan is
average error in treatment plan (1-2mm deviation for implant site) and
other studies reported (6mm) which is not accepted.
surgical phase of implant
2 stages of this phase:
Stage 1: is placement of implant (last lec)
How much do we wait after placement? Usually 2 months and in maxilla
about 3 but there are many systems improve surface treatment of implant
so we can wait just 3 wks. But when we talk about conventional implant
we wait 2 months in mandible and 3 in maxilla.
Stage 2:
Pt come to clinic we take x-ray to examine bone around implant. If there
is good bone around implant we need to open or to uncover the implant.
Which 2nd stage.
As we know we have non submerged and submerged implants.
When we have non submerged we don’t need 2nd stage because it is ready
for loading.
But in submerged implant we need to open or uncover and remove
healing screw then put temporary healing abutment (cylindrical one that
have screw) then leave it for 2-3 wks for soft tissue healing and
contouring for gum happen then after that we put final abutment.
How do we uncover or open it??
1. Tissue punch: circular punch.
2. Or crestal incision.
3. Or apically repositioned flap: used when minimal keratinized
tissue found so we try to keep it not to cut it. Why do we need
keratinized tissue? To prevent infections and gingival ression.
3-4mm (as minimum) of attached gingiva is needed around
implant. So when little keratinized tissue is found we don’t use
tissue punch or crestal incision we use apically repositioned.
This sheet discuss difficult cases like resorbed ridge, proximity to vital
structure like sinuses we know that after extraction of post teeth the sinus
pneumtize so we should be careful , ID nerve (it’s very annoying for pt to
be parasethized lower lip) and nasal cavity. So:
Advanced surgical techniques:
1. Immediate implant placement: last time we talked about
conventional implant placement. Now we can place implant
immediately after extraction but there is special technique. Now we
have anterior zone and posterior one.
In anterior zone the problems that we can face:

if incisor or canine has infection or periodontal problems
here it could be associated with resorbed labial plate so we
need CBCT and evaluate labial plate if it is definitely
resorbed we can’t proceed immediate implant we need to
wait. So we can’t always do immediate implant (in infected
teeth or extracted with loss bone). Other opinions to do
Socket preservation: after extraction we put bone graft
(synthetic or natural) to minimize bone resorption not
prevent it.
in posterior zone we have:



multirooted teeth so the shape of roots is unfavorable as we
know the shape of implant it is single not multi so what do
we do here?? We usually examine the sockets we try to
choose the one that run with long axis of future prosthesis
so here we need good planning for inclination of implant to
be placed. Usually second part (abutment) manufactured by
companies in different angulation (25,30-45 degree) to
facilitate crown fitting on abutment. So if dentist places
implant that inclined up to 30 degree he can put 30 degree
angulated abutment. Again we take x-ray and evaluate
interdental bone if its good we can place implant inside it if
not you have to choose one of the roots and leave others.
Bone resorption either vertically or horizontally. Usually
vertical bone loss is worse than horizontal it is not easy to
put bone graft so usually what happened that
osteointegration occur with exposed threaded of implant so
here you should be careful by either change the planed place
or to postponed the implant. If vertical bone loss we do
bone graft but if horizontal we might think if loss more than
3mm we do.
Primary stability. Because of the large bone defect after
extraction for multirooted tooth due to wide socket we
depend on apical portion for primary stability of implant so
we prepare apically with twist drills and place implant so
we get the primary stability from apical portion not coronal.
Coronal wider than implant , do we need to put bone graft at
same time here?? No it is just around 1-2mm which is not
indicated. Usually for bone graft we need to be more than
3mm defect and this again to minimize buccal bone
resorption.
Immediate implant its very successful:
1. pt doesn’t need another surgery. Doesn’t wait for healing.
2. theoretically it minimizes possibility of bone resorption because
within 2-3 wks it loaded and this stimulate bone deposition and
preserve the alveolus.
It is common good practice to do immediate implant.
2. Guided tissue regeneration used in bone defect. Now
what happen usually when there is bone defect and put bone graft
without GTR?? Usually soft tissue regenerate faster than bone then
invade and fill the defect. In this teq we put membrane on bone
graft to separate it from surrounding tissue (gum and epithelium)
and this retard soft tissue regeneration. We have many types
resorbable and non resorbable. The conventional is Goretex. How
do we place it?? We need to make sure that the membrane larger
than defect then place first the bone graft then fix the membrane on
it away from adjacent teeth by stretches or special pins. See
slides(61-64). As you see there is defect in ridge width, we place
synthetic bone graft (hydroxyapitate), then cover it by the
membrane.
Grafitting methods: to provide bone for deficient area:
1. Local manipulation:
take bone from adjacent area (anterior nasal
septum, chin, intersptal bone from extraction site) any bone we can
use it. Ridge expansion without need for bone grafting: used when
narrow ant. Maxilla or madible ridge we bring osteotome and
break ridge in the middle and put osteotome and expand the ridge
(slide66) you can see microfracture in labiopalatal cortex then we
can put implant after expansion.
2. In extensive grafitting (large or gross defect or atrophic jaw):
bimaxillary surgery (sandwich teq), they do osteotomy cut in
maxilla to advance it downward then they graft bone in between
the maxilla and midface. (not common).
3. Distraction osteogensis: they do osteotomy cut in jaw and
stimulate formation of bone and callus by elongated distance
between 2 fragments so they put device that activate it everyday 12mm that distract fragments from each other. So we can apply this
teq in dental implant to elongate the atrophic ridge but the problem
it is expensive.
4. Tissue engineering:
stimulate bone generation by tissue
mediators (morphgenic protein) that stimulate the formation of
osteoblasts to deposit more bone.
3. Sinus lifting: common in dental implant. After extraction the sinus
pneumtize downward with just 2or3 mm away from crest. And the
minimum length of the implant is 6mm so if we put implant here it goes
in the sinus and there is no primary stability. So what we can do is sinus
lifting:
a. Direct sinus lifting: slide 67 on buccal side we move to sulcus
make a window 2-5 mm (cadluk procedure) we elevate the
opening itself and the membrane up and then we insert
synthetic bone then we wait 6 months for bone healing and
generation then take radiograph to make sure of bone height.
Now 6mm of bone height is not enough to support the implant
so we do 2 procedures sinus lifting and bone graft. Direct sinus
lifting is very predictable procedure almost the success is100%.
Synthetic bone graft isn’t always successful but when used
with sinus lifting it succeed. Some literatures show success of
sinus lifting even without bone graft. Main principle is to
elevate the membrane without tearing which is the common
problem of sinus lifting. What we can do when the membrane
tears is putting GTR membrane and cover the perforated area
then proceed as usual. Another solution is to use piezosyrgery
which ultrasonic cutting device it cuts bone without affecting
soft tissue so it doesn’t cut the sinus lining membrane. And we
can use it in mandible so it doesn’t injure the ID nerve.
b. Indirect sinus lifting: here we use it when there is good bone
but we need few mms to be enough. so from the socket and
after extraction we insert blunt instrument (blunt that doesn’t
injure the lining membrane) slide 68 the left pic. Blunt
instrument push the membrane up then we insert bone graft
then we can put longer implant than estimated alveolar bone
height.
Dr show his case (70-84): panoramic radiograph show very resorbed ridge
almost 2 mm btn sinus and crest. If we do implant without sinus lifting we
will end up with sinus perforation and compromised primary stability. he
planned sinus lifting bilateral. Slide 71 show left side he did incision and
elevated the bone. 72 he cut in the wall of sinus without perforating the
lining membrane.74 show the membrane. clinically you can see the
membrane move up and down as pt breath . 76 by special elevator we
elevate the membrane. 77 you can see the gap. 79 place synthetic bone graft
in the sinus. Reposition the bone and close the flap. 86 panoramic view after
6monthes procedure.
Materials used for bone graft
We should know some terms first :
Osteoconductive: work as network or frame for cells and bone deposition.
Osteoinductive: stimulate bone deposition by natural cells –
osteoblast,osteocytes…) and tissue mediators. Like natural bone.
1. Synthetic bone: osteocondutive. Minerals like hydroxyapitate,
Tricalium phosphate. Biocompatible.
2. Natural bone (best): osteoconductive, osteogenic, osteoinductive. Like
Auto genus bone graft is the gold standard .
Adjunctive implant techniques:
1. Sinus lift : long term success.
2. Rib graft : not common, because most implant procedures elective
one. But in large constructive procedure like trauma or cancer we can
use.
so we usually we choose simple procedure like we take bone from
oral cavity, or to use synthetic material, or use short implant.
Q : why the rib not other site??
Because the rib has favorable shape like mandible so don’t need a lot
of modification. And we not affect the donor site.
But actually you can take graft from everywhere like tibia, radius,
iliac crest, clavicle. Each one has own morbidity but the easiest one is
the iliac crest. Here we chose rib due to favorable shape.
Slide 91: they did sinus lift without bone graft. They put materials
used in tissue engineering and they found it’s successful .
3. Onlay grafting : replacing large bone loss, however we face sever
resorption rate. We take from iliac crest or from another place. We
don’t prefer this teq.
4. Pterygoid & maxillary tuberosity implants: the idea here is to
place implant in difficult area like tuberosity or pterygiod if we have
atrophic maxilla but it’s not common.
Special consideration in atrophic mandible:
1. Interforaminal area: between 2 mental foramina is safe usually
we have good bone height but the problem the ridge is very thin. So
we can depend on anterior region for ex. If we plan to place
overdenture we can place 4or 3 even 1 implant in anterior region.
2. Behind mental foramen: the problem here is ID canal it’s very
close when we have atrophic mandible. What can we do??
a. Nerve repositioning: we do incision , take nerve out the canal
laterally or medially , place bone graft, then place dental
implant. So implant enter to lower border without injury for the
nerve. But the problem here that we might injure the nerve
during this manipulation. Piezosurgery is one of option. But
again nerve injury is the side effect. Difficult to pt they not
accept.
b. Short wide implant: 6mm implant length. Most atrophic post
mandible ridge height is 7mm so it can do the job. If we have
big load we can place more than 1 implant to distribute it. Pts
accept this option.
c. Lingually positioned implant: the idea is to place implant
lingually behind ID nerve. How?? By computer assisted dental
planning , you plan angulated implant lingaully, produce stent
or guide, place implant. It is not easy to do.
Q: in this option could we injure the lingual nerve??? No
because it outside the mandible anatomy, it is between
mandible and soft tissue. This happen if operator perforate
lingual plate and retract soft tissue but not from Implant.
Complications:
1. Sinus perforation: you can prevent by good planning (good
radiograph, length of implant….)
2. Perforation of ID canal is serious. You might injure the nerve and
induce parasthsia or anesthesia. If this happen you should remove
implant or replace by short one. And wait nerve healing which takes
weeks to months or year.
3. Perforation of buccal or lingual plates: due to bad planning or
surgeon didn’t see lingual undercut in mandible.
4. Wound dehiscence: tension of suture.
5. Implant failure : there are many causes (early, late failure). The
important thing is technical error that we should avoid like
overheating for bone during preparation, and contamination,
perforation. Otherwise implant success is v.very high it can reach
100% if well planned even if your pt has systemic problems.
The most failure causes related to operator.
 When you have parasethsia due to nerve impingement you
have very limited options to restore function of nerve, you just
can remove the impingent and wait for healing (3-6months).
But if it is complete cut you can think about other options.
Growth and transplantation of a custom vascularised
bone graft in a man
 Now allograft same tissues from different pt. they treat the
tissue remove antigens and check them for viruses and aids.
then produce this tissue as powder or paste after treatment. It is
not good as autogenus because not contain cells. It contain
dead cells so it is bone graft without inductive ability .
 Xenograft tissues from different species. Like hydroxyapatite
from coral, caws (fears about caw disease that can be translated
to human), membranes from pigs.
 Usually in dental practice we deal with autograft or synthetic
bone like hydroxyapatite or Tricalium phosphate.
 Donor sites for dental implant
o Extraoral: rib, iliac crest, clavicle……
o Intraoral: chin (incision from canine to canine, exposed
the area, cut bone from apices of teeth to chin without
any change in contour of the chin so there is no side
effect aesthetically nor functionally complete healing
without any defeciency, take thin blocks better blood
supply than thick and less porn to resorption, transfers to
recipient site, fix it with screws, cover it with synthetic
bone and membrane to make it thicker) , retromolar area,
anterior ramus laterally, coronoid, …..
 Healing cap (healing abutment), you put it after
osteointgration, this in submerged implant but non submerged
we don’t need. The aim of it to allow healing of gum after
punch or incision, the gum needs healing.
What dr want from us to understand are:
Indications of bone graft, options, how to diagnose defects whether 2D or
3D, horizontal or vertical, complication, how to avoid by good planning.
Good luck 