Implantology Flashcards
Predictors for long term success of implants
- Sufficient volume of healthy bone
- Density of bone
Healthy bone to house adequate size and no. of implants
Failure of impants associated with bone with low mineral content
Main clinical manifestation of a successful implant
- Absence of mobility
Main determinants of implant stability
- Mechanical properties of the bone tissue at implant site
- Implant engagement with bone tissue
Mechanical properties of the bone tissue at implant site dettermined by
- Composition of bone at implant site
- Stage of healing
Trabecular bone transformed into dense cortical bone near implant surface
Transformed into dense cortical bone near implant surface
Trabecular bone
Implant engagement with bone tissue dettermined by
- Surgical technique
- Design of implant
- Osseointegration process
Successful healing of implant results in
- Bone formation reinforcing interface zone
- Forms bridges and direct contact between implant surface and surrounding bone
Unsuccessful healing of implant results in
- Interface fibrous scar tissue
- Caused by infection or mobility of implant after placement
A clinically stable implant shows a degree of mobility
True
This is on the microscale for example the application of a lateral load(bending)-implant is displaced and then returns to natural position
Types of load implants are subject to
- Axial
- Lateral
- Rotational
Axial loads direction
Push in /pull out direction
Lateral loads direction
Any direction 360 degrees around implant
Rotational loads direction
Clockwise or counter clockwise
Primary implant stability
Contact between implant surface and surrounding bone at placement
Primary implant stability depends on
- Bone
- Surgical technique
- Implant design
Implants
Biomechanical properties of bone dettermined by
- Ratio of cortical to trabecular bone at implant site
Cortical bone for implants
- Outer layer of bone beneath periosteum
- Densly packed mineralised lamallae
- 10-20 stiffer than trabecular bone->better support
Trabecular bone for implants
- Porous structure
- More soft tissue components than mineralised tissue
Surgical technique effect on implant stability
- Choice of drill diameters
- Depth of preparation
- Whether pretapering is used or not
- 1 degree implant taper
Using thinner drill diameters, omitting pretaperinf and use of a tapered implant results in higher primary stability
Secondary implant stability
- Delayed bone response after implant placement
- Change in cortical/trabecular bone ratio
- Increasing degree of bone implant contact
- 12-18 months
Other endogenous and exogenous factors that influence implant healing and bone remodelling capacity
- Patient general health
- Use of drugs
- Smoking
- Irradiation
Overload threshold is lower for
Implants with low stability than for one with high stability
Bone healing response after implant placement
- Blood clot formation
- Fibrin network provides scaffold
- Mesenchymal cells in granulation tissue differentiate to preosteoblasts then osteoblasts to form bone
- Erythrocytes, leukocytes, thrombocytes
- Aids migrating cells involved in formation of new vessels, extracellular matrix and bone
Stages of bone regeneration
- Immature woven bone replaced with mature lamellar bone
- Early bone formation after 3-4 months
- Remodelling process of repair-another 9-12 months
- Performed by bone metabolising units-osteoclasts and osteoblasts
Can result in more rapid integration of implants
- Rougher implant surface
- More bone contacts at earlier stage
Two types of implant integration
- Contact osteogenesis
- Distance osteogenesis
Implant intergration by formation of bone directly to implant surface
Contact osteogenesis
Bone formation from pre-existing bone surfaces towards implant surface
Distance osteogenesis
Benifits of rougher implant surface
- Initial blood clot better retained to implant surface
- Clot acts as scaffold for migration of mesenchymal cells to interface
- In smooth implants-shrinkage of blood clot after some time results in gap at implant interface
- Better results in situations where bone grafting and immediate loading required
The soft tissue barrier around an implant is important for
- Implant stability and long term clinical function
- Protects integrity of bone implant interface
Morphology of soft tissue barrier around implant
- Similar to gingiva around teeth
- Sulcus epithelium
- Contact epithelium followed by zone of connective tissue down to marginal bone
Difference between soft tissue barrier around implant and gingiva is direction of collagen fibres which run parallel with implant/abutment surface-perpendicualar fibres also present at teeth
Expected bone loss during healing and first year of implant loading
0.5-1.5mm
Surface roughness and geometric features such as microthreads at neck of implant may reduce marginal bone loss
Implant components
- Implant fixture
- Cover screw
- Abutments
Indications for implant treatment
- Edentulism
- Partial edentulism
- Single tooth loss
Contra-indications to implant treatment
- Untreated periodontal disease
- Periapical lesions in adjacent teeth
- Untreated jaw bone infections or cysts
- Terminal illness
- Uncontrolled metabolic disease
- Severe bleeding disorders
Systemic risk factors of poor implant performance
- Local bone quality
- Bisphosphonate treatment in osteoporosis
- Metabolic disease-diabetes
- Smoking
- Chemotherapy
Intravenous bisphophonate treatment may increase jaw osteomyelitis and necrosis as well as combination with corticosteroids
Smoking affects peripheral microcirculation and wound healing as well as bone quality
