#FIXEDPROS

Basic principles

implants

• pure titanium is highly bio compatible and has an affinity for bone
  • if placed in direct contact with undamaged bone cells, fresh bone will be deposited on the titanium surface and can be a very stable and dynamic bone
• implants typically titanium cylinders with coarse external thread and an internal threaded space allowing for resto to be attached to the implant
• 3 parts
  • implant/fixture, placed in residual alveolar bone
  • abutment, attached to and removable from the implant, extending through soft tissues and gives support to resto
  • resto, crown bridge, rem denture
• typically placed for 3 months to allow for bone to grow on surface before abutment and resto placed to resist occlusal loads

Osseointegration

• process of titanium implant fusing into alveolar bone
• similar to ankylosis
• surface finish of titanium is very important in affected speed and degree of bone apposition on the surface
• slightly roughened surface (40-80 microns) is similar to acid etched or sandblasted is better than very smooth or course surfaces
• features affecting integration process
  • bone must be in close contact, hole cut for implant must permit a tight fit
  • must be uncontaminated titanium surface with commercially pure titanium
  • bone cant be damaged, particualrly by heating, 3-4 degrees of rising temp may damage osteoblasts and prevent osseointegration
  • density, vascularity and volume of bone important

General indications

• spaced dentition where bridges are impossible
• key abutment teeth missing
• no suitable abutment teeth
• long spans with previous bridge failure
• disturbance of current restos is more complex/expensive than ipmlants
• adjacent teeth are unrestored

General contraindications

• uncontrolled diabetic patient, more surgical complications, higher risk of long term loss of implants
• following raidotherapy, less vascular bone likely
• uncontrolled perio, higher ris kcomplication
• heavy smoking, even if long term heavy smoker who has quit
• younger patient, 18 for women or 21 for men
• strong bruxing habit more complications

Designs

• many different type
• width 3-6mm, usually 3.75-4mm
  • wider implant more surface area for greater mechanical strength and osseointegration
• length from 6-20mm, usually 9-13mm
  • longer can be harder to place, harder to cool the burs
• abutment varies
  • most have transmucosal abutment, which mean implant is entirely in bone and part that extends through mucosa is detachable abutment

Abutment

• screw or cement retained
• screw very predictable, can just composite over it after if single implant to never be removed
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Impression

• impression coping
  • 
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• use identical coping for master cas

Resto

• single tooth usually metal ceramic or all ceramic
• extensive bridges may be gold or titanium frame with acrylic teeth over top or lab composite

Implant survival

• soon after
  • surgical complications
• time of loading
  • lack of osseointegration which failed to develop during healing
• years later
  • mechanical overloading or implant
  • peri implantitis - progressive boen loss
• no bone loss can be demonstrated over many years, any degree of bone loss should be investigated and treated
• restoration failure common, patient has no PDL so no normal proprioception from implants
• depends on all factors

Planning

• planning is complex, the implant itself is not
• number and position
  • short implants have to be splinted to other implants
  • minimum space required as per manufacturers instructions
  • no margin for error in placing
  • use surgical guide from CT scan using radiolucent stent and radiopaque markers to create it
• bone and grafting
  • inadequate bone/soft tissue can be augmented by a grift
  • bone harvested from retromolar, edentulous sites, hip, cranium, mental
• appearance
  • use a realistic denture with tooth over ridge exactly where planned to give a realistic look of what it will be like
• radio
  • OPG, CT, lone cone
• provisional
  • can give provisional denture modified to fit over implanted area

Surgical procedures

procedure

• typically teeth extracted 6-12 weeks prior
• strict aseptic technique
• series of drills with increasing diameter, until ideal hole made
• then implant slowly screwed into bone utilising self cutting threads
• one stage
  • at implant placement a healing abutment placed and flaps are sutures so abutment is just projecting through soft tissue, holds back soft tissue to create soft tissue tunnel
  • once healing of soft tissue and bone has occurred, implant ready to be restored
  • most common approach
• two stage
  • after insertion of implant, hole for abutment screw is sealed with cover screw and flaps are sutured over the area
  • healing period of 6-12 weeks
  • second stage surgery performed to lcoated top of implant, removed cover screw and place healing abutment
  • extra surgery but encourages uneventful healing with no loading to implants during healing
  • best for bone graft or protection from loading not guaranteed
• immediate placement
  • can be possible to extract a root and immediately place an implant into the site
  • only if tooth uninfected, residual socket smaller than implant being placed
  • increased risk of failure, usually placed where soft tissue and gingival contour maintenance is key for appearance

Abutment

• needs to be attached with manufacturers protocol
• impression made with silicon gingiva, and labial putty mask for master model

Impression

• special tray or modified stock tray
• polyether or silicone

Maintenance

• clinical and radio every year for 2-3 years and then longer recall
• no metal scalers around implants, plastic scalers only

Complications

signs of failure

• implant mobility
• pain or discomfort
• bone loss more than 1mm in first year or more than 0.2mm per year after

complications

• bone loss around top of implant may indicated occlusal overloading or poor oral hygiene