treatment planning of implants

8/10/2019 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.

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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 cant control the growth pattern.

2-

Medical status

3- Dental status

4- Psychological and financial factors ;you have to prepare the patient

psychologically for implant surgery because some patients are afraid of surgery, so dont

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, dont 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 inesthetic.

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).


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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 dothe procedure will have complications over time, patients

who are on follow up protocols have lower complications (its easier to treat the

complication at the beginning).

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 cant 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).

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.


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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

cant know the final position of the implant if you dont know the final position of

the teeth, and what determine the final position of the teeth are esthetic and

phonetics , so you cant know esthetic and phonetics if you dont have a completedenture 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.


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- 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 mmeither from the contact

point or from the root surface; it doesnt make a difference, but if the adjacent tooth

has a bulbous surface proximally its 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 sixif 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).

-Lets take the space for two 4mm implants ; I need 14mm :

1.5+1.5=33+3=6 6+4+4=14mm

Mesially+ inter-implant diameter of theDistally space two implants

For anterior area; the implant should be 1.5-2 mmfrom 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 mmaway 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 theinter-implant space was less than 3 mm , and each one of the implants


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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 levelblack

triangle will be formedpoor 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

implantsfor the upper central incisors + premolars , narrower implantsfor the

upper laterals + lower anterior teeth + some cases in premolars (when it is small)

, wider implantsin 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 .


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D. Buccolingual

At least 6 mmof bone (not with soft tissue)

buccolingually is required for placement of a 4mm

diameter implant and at least 7 mmfor a wider

diameter 5 mm implant. So the space is minimum 2

mm wider than the implant buccolingually .

- Implants in the picture illustrating inadequate bucco-

lingual 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 .


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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 inadequatetreatment 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 dont 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.

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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 ismore than 3mm, the final restorations are almost always restored

directly to theimplant.

Screw retained abutments are only used when the implants are placed

deeply or soft tissue depth is excessive( in deep implants its better to make thefinal restoration at abutment level).Disadvantages of this that there will be a

display of metal on the restorationand 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.


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segmented vs. non segmented.D

When cemented restorationsare to be used we make them segmented but if

screw retainedwe 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.

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

Summary:

If the implant is deepwe put the margins

of the final crown on the abutment.

Not deep implantwe put the final

restoration at the implant level.

Cemented restorationsmake them

segmented.

Screw retainedmake them non

segmented

treatment planning of implants

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