PART 6 Implant Prosthodontics 26/11/2015 LIMU Dr. Rafik M. - - PDF document

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PART 6 Implant Prosthodontics

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• Dr. Rafik M. Alkowafi

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1- Single tooth implant prosthodontics

• In many respects the prosthodontic treatment for

a single tooth is straightforward if the planning and placement of the implant is correct.

• If implant positioning is poor, the prosthodontic

correction of the error to achieve an acceptable result can be impossible.

• The choice of the appropriate single tooth

abutment is

• ne
• f

the most important prosthodontic factors.

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1- Single tooth implant prosthodontics

• Abutment types:

– All manufacturers produce a variety of abutments suitable for single tooth restorations. Abutments attach the crown to the implant and prevent rotation between components. – The final restoration needs the correct emergence profile to support and contour the soft tissue. This may require a transition from a standard 4-mm-diameter implant to the 7-mm-wide neck of a central incisor for example. – The abutment needs to resist conventional compressive and tensile loads and rotational forces, as it will not be joined to other implants or teeth.

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1- Single tooth implant prosthodontics

• Choosing the Abutment:

– Abutment selection is based on the following features.

1. Depth of Soft Tissue 2. Emergence Profile 3. Orientation 4. Interocclusal Space 5. Retrievability 6. Special Aesthetic Requirements and final restoration.

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1- Single tooth implant prosthodontics

Abutments for single tooth restorations fall into the following categories:

• 1. Standard abutments (readymade)
• 2. Semiprepared abutments
• 3. Fully customized abutments
• 4. Computer-generated abutments [computer-

aided design (CAD)/computer-aided manufacture (CAM)]

• 5. Prepable abutments
• 6. Abutments for screw-retained crowns

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1- Single tooth implant prosthodontics

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1- Single tooth implant prosthodontics

1. Standard Abutments:

• They are usually two pieces with

an abutment that fits onto/into the implant head and a separate abutment screw that can be titanium alloy or gold alloy.

• A variety of heights are offered

with a smooth collar that extends from the implant head to the margin for the crown.

• Matched impression copings,

temporary copings, laboratory analogues, and gold and porcelain cylinders are produced to ease manufacture.

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Selectionof abutment height. (A) A short abutment collar places the margin deeper in the soft tissues but allows more height for development of a suitable emergence angle compared to a longer-abutment collar height (B).

1- Single tooth implant prosthodontics

• Advantages/Indications of Standard Abutments

1. Simple to use 2. Minimal chairside and laboratory time 3. Predictable fit and retention for crown 4. Use in “straightforward” cases where optimal space and implant orientation has been achieved

• Disadvantages/Contraindications of Standard Abutments

1. Margin for crown does not follow gingival contour 2. Cannot be customized for implant orientation or anatomical features—particularly not suited to very labially inclined implants 3. Not suitable for multiple adjacent single tooth restorations as the path of insertion of the crowns is not adjustable. 4. Not suitable for extremes of interocclusal space

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1- Single tooth implant prosthodontics

• 2. Semiprepared Abutments
• These abutments are similar to

standard abutments but have a more anatomic shape and are designed to be modified in the laboratory to customize the shape for differing clinical situations.

• This

includes abutments with angulation changes built in. The abutments have a contoured gingival margin to allow for a deeper margin

• n

the labial aspect in the aesthetic zone and this can be The coronal portion of the abutment can

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1- Single tooth implant prosthodontics

• Advantages

1. Allows for changes to angulation and crown path of insertion 2. Gingival margin contours can be followed 3. Minimal laboratory input

• Disadvantages

1. Customization limited by size of abutment at start 2. Circular in cross section so not able to fully simulate anatomic contours 3. Require abutment selection at start (i.e., multiple sizes/ shapes)

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1- Single tooth implant prosthodontics

• 3. Fully Customized Gold Abutments
• The abutments have a readymade precious metal

component that is the abutment/implant connection corresponding to the implant design. This ensures a perfect fit between abutment and implant.

• The rest of the abutment is a plastic customizable

cylinder that the laboratory technician can wax on to. The plastic cylinder is a burnout plastic so the whole abutment shape apart from the fit part is fully customizable by the laboratory technician who can then cast the abutment using conventional techniques

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1- Single tooth implant prosthodontics

• Advantages

1. Suitable for cemented and screw-retained restorations 2. Fully customizable including angulation 3. Works for extremes of interocclusal space 4. Easy to align multiple implants

• Disadvantages

1. Gold abutments only 2. Expensive and complex laboratory input required

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1- Single tooth implant prosthodontics

• The nonsegmented implant

crown (sometimes termed a “UCLA” restoration as it was first described at the University of California, Los Angeles) bypasses the abutment portion by means

• f a sleeve waxed directly to

the implant.

• Using nonsegmented

implant crowns may be necessary when soft tissue thickness is less than 2 mm.

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1- Single tooth implant prosthodontics

• 4. Computer-Generated Abutments
• Several manufacturers have systems available to

make abutments, which are fully customized using CAD/CAM techniques

• The abutments are produced as part of a
• factory process so quality control is high.
• Particular advantage is the ability to produce

abutments that are fully customized in ceramic (zirconia) and titanium.

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1- Single tooth implant prosthodontics

• Advantages
• 1. Fully customized

abutments in titanium and zirconia

• 2. High precision
• Disadvantages
• 1. Require specialist

facilities

• 2. Expensive

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• 5. Prepable Abutments
• Prepable abutments are

solid abutments normally made from titanium or titanium alloy that are customized by preparing them with a drill, normally in the laboratory but sometimes in the mouth, into a “crown preparation.”

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1- Single tooth implant prosthodontics

• Advantages

1. Improved flexibility over standard abutments 2. Copes with angulation changes

• Disadvantages

1. More complex laboratory technique than standard abutment 2. Customization limited to the basic size/position of the 3. May require second intraoral impression 4. Precision of fit of crown to abutment is less predictable

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1- Single tooth implant prosthodontics

• 6. Abutments for Screw-Retained Crowns
• For single tooth, the main advantage is simplicity and ease of

insertion and removal.

• Problems can arise when cementing crowns, particularly if deep

margins are used. With a screw-retained approach, the porcelain can be taken further subgingivally with minimal risks.

• Usually screw-retained crowns are more applicable to premolar and

molar regions where occlusal screw access may be less of an aesthetic problem

• The technique utilizes gold fully customizable abutments that are

waxed up to the contour ready for porcelain application so that the abutment and crown are in one-piece.

• Gold suitable for porcelain bonding is used.

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1- Single tooth implant prosthodontics

• Advantages

1. Predictable retention and removal 2. No margins or cement 3. Easy access to abutment screw if tightening required 4. Very robust 5. Takes up less space than conventional two-part technique

• Disadvantages

1. Screw hole must exit in suitable position cosmetically 2. Screw hole may make occlusion less stable if in critical occlusal contact position

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1- Single tooth implant prosthodontics

• Impression Coping
• Impression copings facilitate transfer of the intraoral

location of the implant to the same position on the laboratory cast. Impression copings can be either screwed into the implant body or screwed or snapped onto an implant abutment.

• Typically, the impression transfer can be either closed-tray

transfer or open-tray transfer.

• The closed-tray technique captures the index of the

impression coping, and after the impression is removed from the mouth, the impression coping is unscrewed from the implant and placed along with an implant analog back into the impression.

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1- Single tooth implant prosthodontics

• An open-tray transfer uses a specific impression coping

that is designed to emerge through the impression

• tray. When the impression is ready to be removed from

the mouth, the impression coping is unscrewed and pulled out in the impression.

• The open-tray method is considered the more accurate

transfer method and is indicated when large-span frameworks or bar structures are planned or when the implants are too divergent to easily remove the impression tray in the closed tray technique.

• Addition silicone or polyether impression material is

recommended

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1- Single tooth implant prosthodontics

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• The closed-tray technique
• A two-piece coping

(transfer/closed tray)

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1- Single tooth implant prosthodontics

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• The Open-tray technique
• two-piece coping

(pickup/open tray) is used to orient the antirotational feature or to make impressions of very divergent implants.

1- Single tooth implant prosthodontics

• Implant Analog or Replica
• Implant analogs are manufactured

to replicate exactly the top of the implant fixture (fixture analog) or abutment (abutment analog) in the laboratory cast.

• Both are screwed directly into the

impression coping. The impression coping or analog component is then placed back into the impression (closed-tray transfer) or is maintained in the impression (open-tray transfer), and the impression is ready to be poured.

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1- Single tooth implant prosthodontics

• Prosthesis-Retaining Screw
• Prosthesis-retaining screws are intended to attach

prosthetic abutments, screw-retained crowns,

• r

frameworks to the implant fixture

• r

implant

• abutment. The screws are generally made of titanium,

titanium alloy, or gold alloy and are sized specific to the type, size, and design of the implant or abutment system.

• Most prosthesis screws are tightened to specific

tolerance by a torque wrench or handpiece. The torque value is measured in newton centimeters, and typically ranges from 10 to 40 Ncm.

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1- Single tooth implant prosthodontics

• Impression and abutment selection:

–Before an abutment is selected, a choice needs to be made between two alternative techniques:

• 1. Abutment impressions.
• 2. Implant head impressions.

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1- Single tooth implant prosthodontics

• 1. Abutment impressions.
• The conventional approach for single tooth restorations

using standard manufacturer-made components, by choosing the abutment and place it into position.

• An impression is made of the abutment and a working

model produced using readymade components

• The abutment can be left in position and covered with a

temporary cover or a temporary crown can be build up using conventional crown and bridge techniques.

• Alternatively, the abutment can be removed following

impression taking and stored for use at the next

• appointment. The healing abutment is therefore replaced.

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(A) Healing abutment in position. (B) The impression coping. (C) The coping is seated into the implant— the metal part will stay in the implant following removal of the impression. (D) The blue plastic component is picked up in impression. The metal coping that remained attached to the implant will reseat back into this. (E) Working cast with abutment in position. (F) The metal coping for crown manufacture.

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1- Single tooth implant prosthodontics

(G) Completed crown on cast. (H) Internally the use of a premade coping ensures an accurate fit. (I) Abutment seated. (J) The crown immediately after cementation

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1- Single tooth implant prosthodontics

• 2. Implant Head Impressions
• This technique is mandatory for all abutment types
• ther than standard abutments
• An impression (closed or open tray methode) is

recorded of the implant head using an impression coping which is cast with an analogue of the implant head to produce a working model.

• The abutment can be selected and seated onto the
• model. Choice of the abutment outside of the mouth

ensures that the correct decision can be made more easily without taking up clinical time. Any of the abutment types can be used in this way.

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1- Single tooth implant prosthodontics

• Further steps for completion of restoration are

same as conventional crown and bridge work and includes:

– Temporary Restorations. – Shade taking and laboratory procedures. – Try-in (fitting, margins, gingiva, contour, occlusion, esthetic.....) – Cementation. – Instructions to the Patient (oral hygiene, Patients should be warned that the new implant restoration might feel “hard” and “heavy” to bite on for a few days, a feeling that soon passes.

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• 2. Fixed bridge prosthodontics
• Principles:

– Short-Span and Long-Span Bridges, Linking implants in a fixed bridge has the following benefits:

• 1. Shorter implants (under 8 mm) can be protected

from overload.

• 2. Implants placed in areas of high potential stress

can be protected by linked structures.

• 3. Linked implants allow limited cantilever pontics

to be incorporated into a bridge

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• 2. Fixed bridge prosthodontics

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• (A) Guide pins have been placed

in the implant analogues following head

• f

implant impressions. The path

• f

insertion of the implants would dictate labial screw access holes if convention screwretained abutments are used.

• (B) Using angled abutments, the

screw access can be realigned to an acceptable position.

• (C) Angled abutments in position.
• (D) The completedbridge
• (E) The palatal screw access
• 2. Fixed bridge prosthodontics
• A) Prior to restoration, the

healing abutments are in

• place. (B) From the occlusal

view, the narrowness of the ridge is clear.

• (C) An angled abutment is

screwed into place. The screwdriver, which is tightening the abutment screw, is in the long axis of the

• implant. The guide pin is in the

bridge screw hole showing the degree of change the angled abutment has produced.

• (D) A titanium angled

abutment from Astra Tech

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• 2. Fixed bridge prosthodontics

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• E) The pick-up abutment impression

copings are attached.

• (F) A customized tray.
• (G) Impression material (Impregum)

is syringed around the copings.

• (H) The tray is seated and the tops of

the impressions pins identified.

• (I) On removal, the impression

copings are visible

• (J) Abutment replicas are attached to

the copings. (K) The metal framework.

• (L) From the occlusal surface,

adequate space for the porcelain is prepared.

• 2. Fixed bridge prosthodontics
• (M) Metal try in
• (N) The completed bridge.

Note that there is a small part of the titanium abutment visible on the distal implants but this will not cause an aesthetic problem.

• (O) The completed bridge

in position.

• (P) From the occlusal

surface, the screw holes are in a favorable place.

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• 3. Implant overdentures

1. Selection of abutments:

– When a two-stage submerged procedure has been carried

• ut, the patient should be seen about four weeks after

second-stage surgery for selection of abutments and primary impressions. – When a one-stage procedure has been carried out, this prosthodontic stage would normally be carried out approximately three months after implant placement. – The abutment gingival height selection is based on a measurement using the abutment depth gauge. – There is only one size of ball attachment, which has a 2.25 mm diameter.

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• 3. Implant overdentures

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Locator Abutment

Measuring gingival height Nobel Biocare 2.25 ball abutment

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• 3. Implant overdentures
• 2. Recording Primary Impression:

– Once the measurements for the planned abutments have been made, the healing abutments should be replaced and primary impressions made. – The purpose of these impressions, usually made with alginate impression material, is to produce casts on which custom trays can be made.

• 3. Custom tray Construction and Final Impression

– A custom tray is made on the primary cast from acrylic resin or light-cured tray material. Addition silicone or polyether impression material for the final impressions.

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• 3. Implant overdentures

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Final Impression Locator impression coping on abutment Acrylic custom-made tray

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• 3. Implant overdentures
• 4. Recording the maxillomandibular relationship

– For the construction of implant dentures, just as with conventional complete dentures, the spatial relationship between the maxilla and the mandible is recorded by the use of occlusion rims

• n record bases.
• 5. Selection of Denture Teeth
• 6. Try-in

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• 3. Implant overdentures

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• 3. Implant overdentures
• 7. Completion of implant overdentures:
• Where a milled bar and clip-retention system is being used, the

trial denture setup is sent to the laboratory where the bar is now constructed

• If a cast bar is being used, it should be tried in the mouth prior

to completion of the dentures. If the bar demonstrates a passive fit on the abutments, then the denture can be finished.

• The implant overdentures should now be finished with any clips

attached to the bar over appropriate spaces and all but the retention elements of the clips blocked out with plaster prior to flasking, packing, and processing in the usual way

• Where ball attachments are being used, the retention caps are

attached to the laboratory replicas and again blocked out with plaster

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• 3. Implant overdentures

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PART 7 Implant Failure

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Definition

• Implant failure is defined as the total failure of

the implant to fulfill its purpose (functional, esthetic or phonetic) because of mechanical

• r biologic reasons.

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Etiology of Failure

I. Improper patient selection.

• II. Surgical complications.
• III. Improper implant selection.
• IV. Prosthetic complications.

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I . Improper patient selection

• A. Patients with compromised medical status:

1) Osteoporosis, Paget’s diseases and Fibrous Displasia. 2) Uncontrolled diabetes. 3) Psychological problem.

• B. Patients with destructive habits:

1) Parafunctional habits (Bruxism and Clenching) more in maxilla ?. 2) Smoking (failure rate among smokers is 11.28% compared for non smokers 4.76%).

• C. Intraoral Condition:

1) Poor oral hygiene (Peri-implantitis). 2) Irradiation Therapy.

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• II. Surgical complications
• 1. Hemorrhage:

a) Soft tissue incision (managed by applying pressure for 5-10 min or suturing. b) Intraosseous surgery (managed by applying bone wax or haemostatic agent or even the implant itself.

• Perforation of lingual plate in posterior mandible can cause

injury to lingual artery that may lead to life threatening airway obstruction.

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• II. Surgical complications
• 2. Inferior alveolar nerve injury.
• 3. Lingual nerve injury.
• 4. OAC (Oroantral communication).

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• II. Surgical complications
• 5. Broken Bur.
• 6. Oversized osteotomy (managed by selection of larger

diameter implant or application of bone graft.

• 7. Air embolism and emphysema (injection of air and

water through the hollow dental drill directly in to the mandible the into facial and pterygoid plexus of veins to superior vena cava to right atrium).

• 8. Accidental swallowing.
• 9. Fractured cortical plate.
• 10. Fracture Mandible.

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• II. Surgical complications

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• II. Surgical complications
• 11. Hematoma.
• 12. Chronic pain.
• 13. Implant exposure.
• 14. Implant mobility (due

to bone resorption or infection, the implant should be removed).

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• II. Surgical complications
• 15. Lack of initial stabilization.
• 16. Implant angulation.
• 17. Improper flap design and wound dehiscence.
• 18. Bone overheating and exerting extra pressure.

– Bone cell death at temp. 47 ºC and higher for 1 min. – Drill speed not more than 2000 rpm + graded drill series. – external irrigation – Excessive pressure cause bone cell necrosis (C.T. interface).

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• II. Surgical complications
• 19. Damage to adjacent teeth.
• 20. Implant placement in an infected socket or

a pathological lesion or immature grafted sites.

• 21. Implant contamination (before insertion).

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• II. Surgical complications
• 22. Postoperative Infection:

– Pain – Swelling – Pus formation

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• III. Improper Implant Selection
• 1. Implant type Vs. Bone type:

– Titanium screw implants for ant. mandible (type I bone) depth ˃ 10mm. – HA coated screws for ant. maxilla & post. mandible (type II & III bone) depth ˃ 10 mm. – HA coated cylinders for post. maxilla (type IV). – Self tapping designs for soft bone in maxilla.

• 2. Implant length:

– Shorter implants have less bone contact and less mechanical support. – Crown implant ratio (lateral forces).

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• III. Improper Implant Selection
• 3. Implant diameter:

– Large diameter implant (greater surface area – mechanical anchorage – initial rigidity). – Wide implant in narrow ridge (less than 1 mm bone buccal and lingual) …… affect blood supply, dehiscence and failure. – Narrow implant in wide ridge (stress concentration).

• 4. Implant number:

– Increase implant no. reduce implant failure.

• 5. Implant design:

– Solid implants better than hollow implants. (dead space) – Cylindrical and screw implants better than conical implants. (stress) – Press fit design (ease of placement in difficult access locations). – Surface treatment.

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• IV. Prosthetic problems
• 1. Abutment fit:

– Misfit leads to screw joint failure. – Clinical and radiographic exam. before impression making.

• 2. Passive prosthetic fit:

– Reduce long term stresses in super structure, implant components and bone adjacent to implants.

• 3. Pier abutment:

– Change the situation into total implant supported or using stressbreakin designs.

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• IV. Prosthetic problems
• 4. Connecting implant to natural abutment:

– Physiologic tooth micromovementbut implant not. – To overcome this by Non rigid connection between natural teeth and implants.

• 5. Excessive cantilever:

– Result in (fracture of prosthesis – loss of osseointegration – bone fracture).

• 6. Poor esthetics:

– Improper implant placement. – Improper soft tissue management.

7. Traumatic occlusion:

– More offensive than natural teeth (lack of proprioception).

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• IV. Prosthetic problems
• 8. Screw Loosening and Fracture. (more

common in maxilla 50% than mandible 20%)

• 9. Implant fracture (by fatigue or trauma. The

most common site is just below the abutment level). 10.Framework fracture.

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• IV. Prosthetic problems
• 11. Ailing Implant:

– Exhibits soft tissue problems (peri-implant mucositis). – Have a favourable prognosis.

• 12. Failing Implants:

– Shows evidence of: Pocketing, bleeding upon probing, purulence exudate, bone loss. – Have poorer prognosis than ailing implants. – If properly treated, a failing implant can be saved.

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• IV. Prosthetic problems

13.Failed Implant:

– Shows evidence of horizontal mobility > 0.5mm – Rapid progressive bone loss – Tender to percussion or during function. – Continued uncontrolled exudate. – Generalized radiolucency around an implant. – More than half of the surrounding bone is lost.

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• IV. Prosthetic problems
• Peri-implant diseases present in two forms; peri-implantmucositis

and peri-implantitis.

• Peri-implantmucositis has been described as a disease in which the

presence

• f

inflammation is confined to the soft tissues surrounding a dental implant with no signs of loss of supporting bone.

• Peri-implantitis has been characterized by an inflammatory process

around an implant, which includes both soft tissue inflammation and progressive loss of supporting bone.

• In general, problems limited to the soft tissue compartment and

not involving the supporting bone defined as ailing implants.

• If the supporting bone is involved and the implant is still stable, the

implant is failing. The implant is failed if it is mobile.

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• IV. Prosthetic problems
• Signs of failure:
• 1. Connecting screw loosening.
• 2. Connecting screw fracture.
• 3. Gingival bleeding and enlargement.
• 4. Purulent exudate from large pockets.
• 5. Pain.
• 6. Fracture of prosthetic components.
• 7. Angular bone loss (radiographically).
• 8. Long standing infection and soft tissue sloughing.

26/11/2015 LIMU

• Dr. Rafik M. Alkowafi

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