dental implant failure [compatibility mode].pdf

7/23/2019 Dental Implant Failure [Compatibility Mode].pdf

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Dental Implant Failure

By

Mahmoud RamadanBDS MUST 2003

HDD Mans. Univ. 2007MDS Mans. Univ. 2011

President of 4Dent Int. Community

DK Syndicate Ass. Secretary



Definition

Implant failure is defined

as the total failure of the

implant to fulfill its

purpose (functional,

esthetic or phonetic)

because of mechanical or

biologic reasons.



Etiology of Failure

I. Improper patient selection.

II. Improper surgical placement.

III. Improper implant selection.

IV. Prosthetic problems.



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).

2) Smoking.

C. Intraoral Condition:1) Poor oral hygiene.

2) Irradiation Therapy.



II. Improper surgical placement

1) Lack of initial stabilization:- Poor bone quality.

- Faulty hand positioning.

- Disengaging a locked drill.

2) Implant angulation:- Occlusal load (Axial – Lateral).

- Angulation not more than 25º.

- Options: Bone Graft – Angulated implant - Angulated abutments.

3) Improper flap design:- Wound Healing and early infection.

- Basic surgical procedures, blood supply, visibility and access.



4) 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).

5) Inter-implant space:- Recommended space 4 – 7 mm bet. Implants:

( good blood supply – better access for hygiene).

- Recommended space 3 mm bet. Implant and

neighboring tooth.

6) Placing implant in immature grafted sites:- Premature loading of implant before maturation of bone graft from

woven to lamellar bone.

- Waiting period of grafted bone site (6 – 9 months).



7) Implant placement in an infected socket or a

pathological lesion:- Placement of fixture (infected socket – pathological lesion).

- Infection from neighboring tooth.

- To reduce chance of contamination (debridement of the socket –

use of antibiotics 2 days preoperative and 10 days postopererative –

using of wider implant to reach fresh bone).

8) Implant contamination

(before insertion):- Reasons of contamination ( Manufacturer – non

titanium instruments – bacteria – glove powder)

- Autoclaving contaminated implants.



III. Improper Implant Selection

1) Implant type Vs. Bone type:- Titanium screw implants for ant. mandible (type I bone) depth ˃ 20

mm.

- 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:

- Sorter implants have less bone contactand less mechanical support.

- Crown implant ratio (lateral forces).



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.



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 componentsand bone adjacent to implants.

- C.P.: pain & discomfort in short term.

implant loosing or fracture in long term.

3)

Pier abutment:- Change the situation into total implant supported or using stress-breaking designs.



4) Connecting implant to natural abutment:- Natural tooth intrusion.

- Non rigid connection between natural teeth and implants.

5) Excessive cantilever:- Result in (fracture of prosthesis – loss of osseointegration – bone

fracture).

- Cantilever and bone type.

- Cantilever and biomechanics.

6) Bad esthetics:- Improper implant placement.

- Improper soft tissue management.

7) Traumatic occlusion:- More offensive than natural teeth (lack of proprioception).



8) Over load:- Caused by (leverage – bruxism).

9) Premature load:- Stress free healing period (3 – 6 months) is recommended for

osseointegration.

- Role of temporary implants to support temporary prosth. to preventstresses on defintive implants.

- Immediate loading reports early failure 7 times higher than delayedcases.

- Time of loading depends on (Bone quality – implant characteristics).

10) Torqueing:- Preloading of implant components was introduced

to apply a fixed load not more than (20 N) using torquewrenches.



Stage of failure

A. Healing period failures:1) Implant placement in infected sockets,

2) pathlogical lesions,

3) immature augmented bone or

4) contaminated implants.

B. Loading failures:• Due to excessive torquing during abutment placement into bone.

C. Post loading failures:• After loading due to occlusal trauma.



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.



Reducing failure risk

Review the causes of implant failures.

Form teamwork for all cases involving different

specialties.



Thank You

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