Treatment Planning of Implants

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Treatment planning of implants.

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Treatment planning of implants in posterior quadrants
- Dr .saleh said “ this lecture is very important and most of his Q will be on it , and we are responsible to study
from the reference .
-this script includes : the record , summary of the reference.
________________________________________________________________________

 Case selection for implants:
1-

Age ; implant is contraindicated in growing patients , in general patient
younger than 20 is not indicated for implants , because he is still growing and
the implant is ankylosed in bone, so you can’t control the growth pattern.

23-

Medical status
Dental status
Psychological and financial factors ; you have to prepare the patient

4psychologically for implant surgery because some patients are afraid of surgery, so don’t
push them for implant. Also Implant is a very expensive procedure worldwide and the cost
may be an obstacle for many patients who are suitable for implants, for example a patient
who has three teeth missing and he is suitable for two or three implants (two implants
and three implants can do the job) , but because he has limited budget for the implants
you will go for two, always give the least number for implants that gives enough retention
and resistance for the final prosthesis.

5-

Marketing of implant from the companies, Choose the implant which has a

system documented in the literature; choose the implant with a good clinical profile and
good history, don’t be tempted with any offer, sometimes the cheapest implant is the
best and sometimes it is the worst.







Planning for implant in anterior area is much more challenging, it's more critical in
esthetic.
Not every patient is appropriate for implants.
Psychological and financial factors are very important for case selection and evaluation,
implants need a patient who can afford it and understand the procedure, you have to
prepare the patient for implants from A to Z , tell him everything about the procedure
then leave him to decide .
keep in your mind that the implant is not a root or a tooth, or even tooth analogous, it's
a device for replacement of missing teeth, so the biomechanical concepts for teeth are
not applicable for implants they are completely different, teeth have PDL and move in
bone but implant is ankyolsed, it has very limited movement ( 3 to 5 microns).

Phases of treatment:
1-

Treatment planning.
History.
Examination
X-rays (CBCT with or without radiographic guide).

2- After you know the number of teeth missing, the diameter and the high of
each implant, the system ..) move to the surgical phase, there are different
surgical procedures ( flaps , computer added, different stages surgery … ) .
3- The restorable phase, after the healing of implant, take impression then
abutment selection and finally the restoration.

4- Maintenance phase, the most neglected phase even it is the most important,
whatever you do  the procedure will have complications over time, patients
who are on follow up protocols have lower complications (it’s easier to treat the
complication at the beginning).



In any case of implants you have to follow these phases in sequence, failure to
fulfill any of them will lead to fail.
Implant surgery is a straight forward procedure if you plan your case in a proper
way.

 The most important rule in implant dentistry is Prosthodontically driven not
surgically. What dictates the position of the implant is the final position of the
tooth; if I want to stick the implant in bone,the final tooth may be a half
centimeter forward, so I can’t restore the implant, some surgeons place implants
wherever they find bone, as a result the implant will be in a place different than
the final position of the tooth that I want to restore.
 Every implant case should start with wax up then a radiographic guide then
the surgical guide (if I need bone graft or soft tissue graft or both or none).

 The complete denture is very important in Implantology especially in full arch
cases, You should make complete denture for every Full arch implants case, you
can’t know the final position of the implant if you don’t know the final position of
the teeth, and what determine the final position of the teeth are esthetic and
phonetics , so you can’t know esthetic and phonetics if you don’t have a complete
denture for the rehabilitation of the patient .
 The predictability of the outcome of an implant restoration in the posterior
part of the mouth is dependent on many variables including but not limited to the
following:
1. Available space.
2. Implant number and position.
3. Occlusal considerations.
4. Type of prosthesis.
5. Overall treatment plan.

 Available space
A. Mesiodistal
 The mesiodistal space required essentially depends on the type of tooth being
replaced (molar or premolar), and the number of teeth being replaced.


Mesiodistal space is evaluated in two dimensions. Adequate prosthetic space must
exist to provide the patient with a restoration that mimics natural tooth contours. If
inadequate prosthetic space exists, it must be created through enameloplasty of
adjacent teeth or orthodontic repositioning.

- The size of the prosthetic tooth must be considered when placing implants; the implant
must be placed sufficiently away from the adjacent tooth to allow the restorative
dentist to develop appropriate contours. If an implant placed for a premolar restoration
is placed too close to the adjacent tooth, compromised contours and unnecessary loss
of hard and soft tissue adjacent to the implant result.



In general The implant should be 1-1.5 away from the adjacent teeth, if the
adjacent tooth has a flat surface proximally  leave 1.5 mm either from the contact
point or from the root surface; it doesn’t make a difference, but if the adjacent tooth
has a bulbous surface proximally  it’s better to leave 1 mm as minimum from the
contact point(NOT root surface) or you modify the tooth by enameloplasty to
improve the contact area , because If you leave 1-1.5 mm from the root surface ,
your implant might be under the contact point and the final restoration will not fit.
-For example, Missing upper six  if your implant is 5 mm in diameter and you leave
1.5 mm distally and 1.5 mm mesially then 8 mm space is needed ;
( 5mm +1.5mm+1.5mm).
- Let’s take the space for two 4mm implants ; I need 14mm :
1.5+1.5=3  3+3=6  6+4+4=14mm
Mesially+
Distally

inter-implant
space

diameter of the
two implants



For anterior area ; the implant should be 1.5-2 mm from adjacent teeth to avoid
encroachment on interdental bone and to avoid its resorption which causes loss of
the papilla and poor esthetic.



In multiple implants cases ; The implant should be at least 3 mm away from an
adjacent implant . but why it should be at least 3 mm not 1.5 mm ?
1- because generally implants cause bone resorption by 1.5 mm , so if the
inter-implant space was less than 3 mm , and each one of the implants

ended up with 1.5 mm resorption of bone that will cause loss of the inter
implant bone  flat bone + papilla will fall down to the bone level  black
triangle will be formed  poor esthetic especially in the anterior area.
2- To maintain good oral hygiene .


A wider diameter implant should be selected for molar teeth ; we use regular
implants for the upper central incisors + premolars , narrower implants for the
upper laterals + lower anterior teeth + some cases in premolars (when it is small)
, wider implants in molars .



Missing upper lateral  7-8 mm mesiodistally , if the space is 10 mm (more than
needed) then you have to change the treatment ; because it is unesthetic to
make a lateral with 10 mm mesiodisally , also the space is not enough to put two
adjacent teeth.

 So the guidelines that should be used when selecting implant size and
evaluating mesiodistal space for implant placement:
o The implant should be at least 1.5 mm away from the adjacent teeth
o The implant should be at least 3 mm away from an adjacent implant
o A wider diameter implant should be selected for molar teeth.

- the minimum inter implant space is 3mm > true
- the inter implant space should be 3mm > false , because it is at least 3mm , not 3mm
specifically .

D. Buccolingual
At least 6 mm of bone (not with soft tissue)
buccolingually is required for placement of a 4mm
diameter implant and at least 7 mm for a wider
diameter 5 mm implant. So the space is minimum 2
mm wider than the implant buccolingually .

- Implants in the picture illustrating inadequate buccolingual positioning. This can be avoided by use of an
appropriately fabricated surgical guide
- Correct angulation is always achieved if the surgeon is diligent and makes use of a surgical
guide to place implants in the correct position. Placing implants in off angle positions (like
the pictures below )always complicates the process for the restorative dentist who now has
to use a host of restorative components to achieve an acceptable end result .

C. Occlusogingival
- This parameter needs to be considered in two
dimensions:
1. Adequate space for restoration ; Sufficient space must
exist to allow the restorative dentist to fabricate
restorations which are harmonious aesthetically with the
adjacent teeth. On examination the space between the
residual ridge and the opposing occlusal plane should be
evaluated . Often, when teeth are missing for prolonged
periods of time, opposing teeth overerupt and
compromise the restorative space ,But If this is minimal
then enameloplasty or minimal restorative therapy may
be required to create space.
Ideally 7-10 mm of space is
required from the head ofthe
fixture to the opposing occlusion

2. Adequate osseous volume for placement of the implant.
Now minimum in natural teeth there should be 1:1 crown root ratio to withstand the load ,
but in implant there is a difference ; I can make an implant (6mm) with crown (10mm)
,because it is ankylosed.
- From the book :
For a standard protocol 7.5 mm of bone height is required for a 6 mm long fixture and
8.5 mm is required for a 7 mm fixture.
- Prior to fixture placement the maxillary sinus, inferior alveolar canal and mental foramina
must be evaluated by means of a CT scan. There should be at least 2 mm of bone between
the apical end of the implant and neurovascular structures.

 Implant number and position
- Single missing tooth  one implant .

- Multiple missing teeth  it is not necessary to make an implant for each missing
tooth ; you can do 2 implants for 3 missing teeth , but in general the number of
implants almost is equal or less than the number of missing teeth .
 The number of implants is dependent on :
1- bone quantity and quality. Often(not always) in the maxilla where less
dense bone is found, surgeons favor placing three implants  one for
each tooth and 2 implants in the mandible for 3 missing teeth. (but as we

said this is not a rule , it is just like a guide so sometimes we make 3
implants for 3 missing teeth in the mandible ) .
2- the biomechanics of the prosthesis and how load is distributed.

- If anterior or posterior implants were to fail the prosthesis design  they would
include an anterior or posterior cantilever. Cantilever type prostheses have been
associated with higher rates of failure in traditional prosthodontics. These types
of prosthesis failed due to mechanical complications of the abutment teeth. Also
Distal cantilevers have been reported to be unfavourable from a biomechanical point
of view and have increased the number of complications for implant supported
prostheses.

 Occlusal considerations :
-Masticatory forces developed by a patient restored with implant supported

restorations are equivalent to those of a natural dentition.When treatment planning
patients for implant supported restorations, a general assessment of the likely
load to be placed on the implants should be made. If the patient is a bruxer the
clinician may plan additional implants to allow for more favourable load distribution.
-Complications with dental implants are most often the result of inadequate
treatment planning. Consideration of bone density and volume, anticipated loads
and planned restorative design are all important to review before number, length
and diameter of implants are determined.
- Implants, unlike natural teeth, are ankylosed to the surrounding bone without an
intervening periodontal ligament. The mean values of axial displacement of teeth in
the socket vary between 25-100 microns while the implants don’t move.
- always minimize excessive loading on implant supported restorations. The
occlusion should be evaluated and organized so that there is anterior guidance and
disclusion of posterior teeth on lateral excursion. There should be no contact of
posterior teeth on both working and non working sides.
_______________________________________________

 Type of prosthesis :
A- Splinted or non-splinted :
-when multiple implants are placed in posterior quadrants  they may be splinted.
- Stress distribution can be manipulated by splinting. The retention of the prosthesis
is also improved with a greater number of splinted abutments. Splinting also has
biomechanical advantages in that it will also reduce the incidence of screw loosening
and unretained restorations.
B - Screw retained or cemented
- Many advantages of prosthesis retrievability can be afforded by screw retention.
Retrievability facilitates individual implant evaluation, soft tissue inspection and any
necessary prosthesis modifications. Additionally, future treatment considerations can be
made more easily and less expensively. But Many practitioners favor cemented type
restorations because this provides a more aesthetic result, as screw access holes can be
avoided.

C. Abutment level vs. implant level restoration







When implants are aligned to allow screw retention, unless the soft tissue
depth is more than 3mm, the final restorations are almost always restored
directly to the implant.
Screw retained abutments are only used when the implants are placed
deeply or soft tissue depth is excessive( in deep implants it’s better to make the
final restoration at abutment level).Disadvantages of this that there will be a
display of metal on the restoration and there will be less room for transitional
contours.
For screw retained pre angled abutments the implant must be planned to be
placed deeper to accommodate the thickness of the abutment , However
loading implants at an angle can be problematic to the screw joint between the
restoration and the abutment.

D. segmented vs. non segmented



When cemented restorations are to be used we make them segmented but if
screw retained we make them non segmented.

 The cement margin should not be placed more than 1 mm sub mucosal to
facilitate cement removal. When cement retention is desired there must be
sufficient inter occlusal space.
Summary:





If the implant is deep  we put the margins
of the final crown on the abutment.
Not deep implant  we put the final
restoration at the implant level.
Cemented restorations make them
segmented.
Screw retained  make them non
segmented

 Overall treatment plan
 Decisions to use implants should be based on prosthetically oriented risk assessment.
 When replacing long span fixed partial dentures consideration should be given to
decreasing the number of pontics and increasing the number of implant abutments.
 Implants added more options to successful prosthodontic rehabilitation.
 Reasons for prescribing implant supported prosthesis:
 Improve support retention
 more stable occlusion
 Preservation of bone
 Simplification of prosthesis
 Long term oral health is often improved because less invasive restorative procedures
are required.

Finally done :D
To live a creative life we must lose our fear of being wrong

Done by :
Rasha Al-Shboul & Rawan Shatnawi

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