Planning and Placement Flashcards
What is Osseointegration?
A direct functional and structural connection between a load bearing dental implant and living (organised) bone.
What are the 2 phases of osseointegration with implant and bone?
First phase- implant is held in by mechanical locking of threads into bone (friction fit)
Second phase- functional connection- bone grows into thread (integrated surface)
-> Initially the threads are empty apart from blood clot, as it reorganises and become vascularised it can then develop into osteoid and mature bone
Bone-implant contact- measure of osseointegration
How do implants and tooth differ in terms of supra-crestal tissue?
Tooth
- More fibroblasts
- Less collagen
- Collagen fibres orientated perpendicular to root surface
Implant
- More collagen
- Less fibroblasts
- Collagen fibres orientated parallel to implant crown
How do implants and tooth differ in terms of sub-crestal tissue?
Tooth
- Anchored to bone by periodontal complex (bone/PDL/cementum)
- Capable of physiologic adaption (viscoelastic)
- “Resilient” tissue attachment
Implant
- Implant anchored to bone by direct functional contact
- No Physiologic adaption present
- Rigid connetion
What materials are used in implants?
Titanium- pure type 4 (>85%)
Titanium- zirconia (85:15)
-> Stronger than Ti
Ceramic- ytrria-stablised zirconia
-> tooth coloured/high survival rate
What are the different aspects of implant design?
Bone or tissue level
Tapered or Parallel
Narrow, wide, regular
-> diameter
Length
Surface texture- machined or treated?
When are bone/tissue level implants used?
Bone level commonly used in aesthetic zone
-> more space to modify emergence profile
Tissue level used posteriorly
When may tapered implants be preferred?
Tapered may provide increased primary stability in immediate placement
Tapered may be used where there is root convergence apically
What factors determine which size of implant to use?
Site
Indication
Local anatomy
-> narrower/shorter tend to have high survival
What levels of roughness can implants be available in?
Smooth (0-0.5um)
Mild (0.5-1um)
Moderately (1-2um)
Rough (>2um)
What treatments can be done to roughen surface of implants?
Sand blasting
Acid etch
Plasma spray
-> allows reparative osteocytes to grow into implant and provide connection
What is the function of a dental implant?
Replace missing teeth
- Functionally
- Aesthetically
- Psychologically (difficulty tolerating dentures)
What are the primary aims of implant treatment?
Replace missing teeth with aesthetic, functional and predictable restoration
Low rate of complications during healing and maintenance period
Long term stability
What should be assessed when considering removal of teeth to replace with dental implants?
Prosthetic value of the tooth
Periodontal status
Endodontic status
What is used to determine the complexity of a case when considering dental implants?
SAC guidelines
-> low, medium, high risk
What should we ask/tell the patient about dental implants when considering their aesthetic demand?
Will implants address the patients presenting complaint
I.e. if they do not want a removable prosthesis is a fixed implant supported prosthesis possible?
What is the patients expectation?
Are they realistic?
Can you achieve them with implants?
Implants are not a panacea
Implant restorations are often not as aesthetic as natural teeth
What are the categories for a patients aesthetic demand as per SAC?
Low
Medium
High
What must we consider in terms of medical health when selecting a case for implants?
ASA class
Haematological isses
Medications- SSRIs, PPIs, bisphosphonates, steroids
Radiotherapy
CVD
Poorly controlled diabetes
What are the categories for medical health in terms of SAC?
Low- healthy, intact immunes system
High- reduced immunes system
What does smoking affect in terms of dental health?
Vascularity
Fibroblast/Osteoblast function
PMN function
How does smoking affect implants?
Increased risk of implant failure
Increased risk of peri-implantitis
What are the risk classifications for smoking as per SAC?
Low- non-smoker
Medium- <10 per day
High- >10 per day
What aspects of dental history may be considered when assessing suitability for implants?
Patient attendance
Motivation
Self performed plaque control
Past tx
Suitable for a surgical procedure
Presence of bruxism- increased risk of failure due to screw fractures, porcelain fractures, implant fractures, framework fractures
What issues can occur when you place implants in patient who has not stopped growing?
Relative infra-occlusion
Suboptimal aesthetics
Occlusal disharmony
Implant fenestration
-> Delay until at least 21 years of age
What are the different smile lines?
High- >2mm ST show (unforgiving, minor errors will be obvious)
Medium- <2mm ST show
Low- lip covers >25% of teeth
What intra-oral checks should be done when assessing suitability of a patient for implants?
Presence of incisal cants
Presence of gingival cants
Width of aesthetic zone
What extra-oral checks should be done when assessing suitability of a patient for implants?
Skeletal relationship
-> Will impact on positioning of prosthetic tooth and therefore implant 3d position
-> May impact on occlusal forced on tooth and guidance
What are the gingival phenotypes and which category are each in terms of SAC?
Low risk- thick, low scalloped
Medium- medium thickness, medium scalloped
High risk- Thin, highly scalloped
In terms of shape of crown what is considered high and low risk in SAC?
High- triangular
Low rectangular
How is risk of Black triangle formation between implants and adjacent teeth determined?
Depends on relative height of alveolar bone in relation to contact point
- If this is more than 7mm (high risk of black triangle)
- 5.5mm-6.5mm (increased/medium risk)
- <5mm- full papilla infill (low risk)
What aspects of soft tissue should be assessed before placing an implant?
M-D papilla
Gingival zenith
Mucosal contour/deficiency
ST colour and texture
How does local presence of infection at site of implant placement affect a patients suitability for implants?
Low risk- none
Medium risk- chronic infection
High risk- acute
How can risks caused by infection at site of implant placement be mitigated?
- Ensure that infection has resolved prior to implant placement
- Acute infection must be managed- consider RCT prior to extraction to reduce size of pathology and encourage healing
- Get rid of infected teeth several weeks prior
How can restorative status of adjacent teeth affect placement of implants?
Risk of recession with subgingival restoration margins on adjacent teeth
Risk of suboptimal aesthetics if trying to match a maxillary central incisor to a translucent, contralateral tooth with characterization
Also consider vitality, caries, perio
How is restorative status of adjacent teeth categorised in terms of SAC?
Low risk- virgin teeth
High risk- restored
What are the issues if the edentulous span is too narrow for implant?
Risk of damage to adjacent teeth
Risk of necrosis of bone between teeth and implants
Will have significant effect on ST aesthetics
What are the issues if edentulous span is too wide for implants?
Challenge to fill place
Decision may be required on where to leave residual space
How is length of edentulous span categorised as per SAC?
Low risk- one tooth > or equal to 7mm, one tooth > or equal to 5.5mm
Medium risk- one tooth <7mm, one tooth <5.5mm
High risk- 2 teeth or more
How does bone at implant site alter risk of failure in dental implants?
Low risk- no deficiency
Medium risk- horizontal bone deficiency
High risk- vertical bone deficiency
How does soft tissue at implant site alter risk of failure in implants?
Low risk- intact ST
High risk- ST defect
What can help us evaluate the anatomy of implant site?
CBCT
What are the relevant local anatomical features which could affect implant placement in maxilla?
Maxillary Sinus
Nasal Floor
Naso palatine canal
Infra-orbital nerve
What are the relevant local anatomical features which could affect implant placement in mandible?
Inferior alveolar canal
Mental Foramen
Incisive canal
Lingual perforating vessels
Submandibular fossa
What are the principles in prosthetically driven planning in implants?
Implants should be planned starting from the final planned prosthesis position (top-down planning)
This should be taken into account when requesting special tests
Prosthetic tooth position will dictate wheter an implant is possible in the correct 3d position
What needs to be considered in 3D implant positioning?
Mesio-distal positioning
Mesio-distal orientation
Bucco-palatal positioning
Bucco-palatal orientation
Apico-coronal postioning
What does 3D implant positioning depend on?
Implant system
Proposed gingival margin
Local anatomy
Prosthetic plan (cement v screw
What must be considered in terms of mesio-distal orientation when placing implants?
Place safe distance from adjacent teeth (1.5mm on each side- not much margin for error)
-> Lowers risk of damage and bone necrosis which could result in ST defect between teeth/implants
-> May take radiographs halfway through treatment to check
*** If adjacent implants- must be 3mm apart
What is the aim in terms of bucco-lingual positioning/orientation when placing implants?
Aim for 1mm of bone labially, >2mm of hard and soft tissue labially
When may guided bone regeneration be considered?
Dehiscence
Fennestration
Inadequate contour
In terms of apical-coronal position, how should implants be placed
Place implant 2mm apical to ACJ of adjacent tooth
-> Varies depending on implant system
What are the different placement protocols for implants?
T1- immediate
T2- Early placement with soft tissue healing (4-6 weeks)
T3- Early placement with partial bone healing (12-16 weeks)
T4- Late placement in healed sites (6+months)
What planning aids are used in implant treatment?
Study models- Mounted
Diagnostic wax up
Surgical template
Essex (provisional)
Clinical photographs
CBCT
Surgical Guide
How is analogue planning of implants carried out?
Diagnostic wax ups can be utilized to plan the size and position of teeth to be replaced
-> Combined with CBCT information and knowledge of implant diameter to aid in planning
Can be transferred to mouth to demonstrate to patient aim of treatment
When agreed (and achievable!) can be converted to stone and surgical template made
How is Digital planning of implants carried out?
Uses software to help identify relevant local anatomical structures and their proximity
Software will highlight potential issues with inter-implant spacing and orientation
Can be used to produce a surgical guide for implant placement
-> 3D printed
-> helps guide drilling
What are the basic steps in placing a dental implant?
- Raise full thickness mucoperiosteal flap buccally and lingually
- Osteotomy- drill hole in bone (take radiograph after a few mm to check position)
- Once at length place implant
- Cover over with guided bone regeneration (collagen membrane)
- Suture
- Take post-op radiograph to ensure correct position
