Biology & Biomechanics of dental Implants Flashcards
How is bone classified?
- Compact/Cortical
- Trabecular/Cancellous
Compact Bone
- Aka Cortical Bone
- Dense & strong
- Give implant primary stability
Trabecular Bone
- Aka Cancellous Bone
- Fibrous Looking
- Provides blood flow & healing
What are the different types of bone? How do they differ?
- Types:
- Lamellar bone
- Woven Bone
- Bundle Bone
- Different
- arrangement ofcollagen fibril
- Mineral content
Woven Bone
- Disorganized form during healing
- Highly cellular
- Low Mineral content
- More pliable than mature lamellar bone
- Formed by osteoprogenitor cells near blood vessels
- during prenatal development, growth, healing
- can stabilize an unloaded implant
- can’t handle functional loading (weak)
Lamellar Bone
- Primary Load-bearing tissue
- Main component of mature cortical and trabecular bone
- Highly organized
- orientation of collagen fibrils: 1 direction
- differ from one layer to another
- orientation of collagen fibrils: 1 direction
- Dense Mineralized matrix
Bundle Bone
- Lines Socket
- directly connected to tooth structure (Sharpey’s fibers)
- first to degrade after extraction
- Next to PDL of physiologically drifting teeth
Bone Density Classification:
- Description
- Tactile Analog
- Typical Anatomical Location
- affects initial stability of implant → osseointegration
- D1 (most dense)
- Dense cortical bone
- marrow spaces barely visible
- anterior mandible
- very difficult to drill
- Dense cortical bone
- D2
- Thick porous cortical bone
- coarse trabecular bone
- anterior & posterior Mandible
- anterior Maxilla
- Thick porous cortical bone
- D3
- Thin porous cortical bone
- fine trabecular bone
- Anterior & posterior maxilla
- Posterior Mandible
- Thin porous cortical bone
- D4 (least dense)
- fine trabecular bone (primarily)
- very thin cortical bone
- posterior maxilla
- Big marrow spaces
- poor initial stability of implant
- fine trabecular bone (primarily)
Bone Volume Classification
- Compact Cortical
- Thick cortical surrounds highly trabecular bone
- Thin cortical surrounds highly trabecular bone
- Thin Cortical bone and spongy core
Define: Osseointegration
- direct connection b/w ordered, living bone & surface of load-carrying implant
- structural & functional
Define: Fibre-osseous integration
- Presence of CT b/w implant and bone
What are the different types of bone tissue response?
- Distance osteogenesis
- Contact osteogenesis
Distance osteogenesis
- bone healing moves toward the implant
- from edge of osteotomy to the implant
- bone does not grow directly on implant
Contact Osteogenesis
- Bone-guiding cells
- migrate through clot matrix to implant surface
- Bone forms quickly on implant surface
Implant: Healing Process
-
2 Hours:
- Socket filled w/coagulum from blood
- Peripheral threads→Primary stability
-
Day 4:
- Coagulum is exchanged for mesenchymal fibroblast cells
- osteoclasts on bone surface
-
Week 1
- Provisional matrix for woven bone & osteoblasts appear
- new bone contacts implant surface
-
Week 2:
- A lot of new bone around the implant
- vascular structures appear
-
Week 4:
- Lamellar bone appears
- Central Bone is filled with primary spongiosa and vascular structures
-
Week 6:
- 1° and 2° osteons are present in new bone
- continued remodeling of lamellar bone
Osseointegration Factors
- Implant biocompatibility
- Design
- Surface
- Host Bed State
- Surgical technique
- Loading conditions
Implant Biocompatability: Osseointegration Factor
- surface oxide properties
- Titanium
- Titanium alloy
- Corrosion resistant
- Load bearing capacity
Implant Design (Macrostructure)
-
Threaded vs cylinder
-
Threaded/screwed
- 3 parameters:
- Shape
- Pitch (distance of full thread turn)
- Depth (b/w root and crest of thread)
- promote osseointegration
- more functional for stress distribution
- 3 parameters:
-
Cylindrical
- press fit root form implants
- depend on coating or surface condition for microscopic retention
-
Threaded/screwed
- Thickness
-
Platform Switching
- smaller abutment on larger collar
- helps move inflammation away from bone
-
Tissue vs bone level implant
- tissue level implant
- posterior region (non-esthetic)
- large taper at top
- tissue level implant
Implant Surface
- rough vs smooth
- rough: more bone grown
- greater bone to implant contact
- rough: more bone grown
- Type of treatments:
- turned/machined
- sand blasted
- acid etched
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Tooth vs Implant:
-Connection, Junctional epithelium, Connective Tissue, Biological Width, Vascularity, Probing depth, Bleeding of Probing
Tooth vs Implant
-diseased implants
- Implants
- high survival rate
- superior option to replace teeth
- biological and mechanical complications
- Diseased implants
- same treatment for natural teeth
- not as successful
- same treatment for natural teeth
Implant Host tissues
- Weaker Sulcular attachment→ ⇡BW → ⇡PD
- implant PD: 4-5 mm
- Ankylosis in bone
- Circular & Parallel CT fibers
- poor CT adhesion
- No PDL
- occlusal loads transferred directly to bone
- Overload=Bone Loss
- especially Lateral Forces
- Overload=Bone Loss
- occlusal loads transferred directly to bone
- gingival Fibers:
- parallel to long axis
- do not attach
-
decreased vascularity→ Slower Healing
- Unpredictable tissue regeneration
- Less reliable BOP
- Plaque/Bacteria→Greater Inflammatory Response→ More susceptible to tissue & bone loss
Implants: Vertical Height from the Occlusal Surface to the Crest
- ⇡Crown Height= ⇡stress on alveolar crest= Lever Arm
Implant Diameter
- Wider Diameter → ⇡ surface area of bone to implant contact → ⇡ stress distribution → ⇣MD and BL cantilever
- Narrower implants in high stress areas
- Mechanical implant failure or implant fracture
Splinting Implants vs teeth
- Implants:
- Improves stress distribution
- Indication
- high occlusal load areas
- More difficult:
- oral hygiene
- make a passively fitting prosthesis
- No PDL; osseointegrated
- Teeth
- PDL
- allows vertical & horizontal movement
- PDL
- Splinting implants to teeth
- increases stress at the neck of implant
- Crestal bone loss
Factors causing marginal bone loss around implants
- Infectious process
- excessive loading conditions
- Location, shape, and size of the implant-abutment micro gap and its microbial contamination
- Biologic width geometry
- implant surface roughness
- Peri-implant inflammatory infiltrate
- Micro-movement of implant and prosthetic components
- repeating screwing & unscrewing
- Traumatic surgical technique