Dental Implantology Flashcards
What are the benefits of a supra-crestal implant?
-Reduce marginal bone loss or saucerization around implants compared to but-joint bone level implants
-Moving the neck above the bone and preventing bacterial colonization of the microgap
What stage of implant placement is the length of the implant important?
-Important in primary implant stability
-Influences immediate loading
-Once secondary implant stability has been achieved (osseointegration), length not as important
What factors play a role in primary implant stability?
-Implant length
-Thread pitch
-Drilling sequence
-Bone quality
Where is the most stress of an implant?
-First 5 mm (this makes diameter important in stress reduction
Why is implant diameter important?
-Large implant diameter increases surface area of bone-implant interface
-Reduces magnitude of force to system
-Can allow for better emergence profile for larger crowns
What are the two shapes of an implant?
Parallel wall: Provides increased surface area
Tapered: Provides stability by creating pressure on cortical bone, which is good for poor bone quality sites. Allows compression, allows for placement in constricted sites. Reduced overall surface area
Why isn’t hydroxyapatite coating no longer used?
-Rapidly absorbed and easily colonized by bacteria
What are the benefits of a micro-rough surface of an implant?
-0.5-2 microns
-Create peaks and depression in the implant to increase surface area.
-Aids in earlier osteointegration
What are the benefits to electrowetting of an implant?
-Improve plasma protein adherence and mesenchmal cell adherence and differentiation
What is the function of the microthreads at the crest module?
-Preserves bone and soft tissue around cervical portion of implant fixture
-Dissipates forces around crest
-Can facilitate higher incidence of peri-implantitis due to plaque retention
What is the micrograp?
-Connection between implant and abutment
What is the anti-rotational component of the implant?
-Platform of the crest module has an anti-rotational feature to retain the prosthetic component
-Can be a platform such as an external hex (external connection)
-Can be within the implant body itself (internal hex, octagon, internal grooves or pins)
What is an external connection?
-Connection to implant that is superior to coronal portion of implant creating a butt joint connection.
-Have higher incidence of screw loosening, rotational misfit, microbial penetration
-Ex: external hexagon connection
What is an internal connection?
-Seen in most modern implants
-Can be parallel walls or conical connection
-Connical connection preferred because it can disperse load. Have improved microbial seal
What is platform switching?
-Horizontal offset between implant connection and cervical area of the abutment
-Can reduce crestal bone loss (better position of epithelial attachment around neck of implant
What material is most commonly used in implants?
-Grade 4 pure titanium, titanium-zirconium alloy, titanium-6 aluminum-4 vanadium
What dictates the biocompatibility of an implant?
-Titanium dioxide (oxide) layer
-Upon exposure to air this oxidation happens and is important in corrosion resistance, biocompatibility and osseointegration
Describe zirconia implants.
-Implants produced with zirconia are biocompatible, bioinert, radiopaque and have higher resistance to corrosion flexion and fracture
What are the criteria for implant success?
-Immobile when tested clinically
-No radiographic evidence of per-implant radiolucency
-Vertical bone loss less than 0.2 mm/year after first year of service
-Absence of persistent or irreversible signs/symptoms of pain, infection, neuropathy, paresthesia, violation of mandibular canal
-New parameters take into account esthetics, soft tissue integrity/appearance, patient satisfaction, prosthodontic parameters
What distance is required between implants and natural teeth and why?
-1.5 mm
-Allow for lateral biologic width
-Violation leads to bone loss around implants and adjacent structures
What is normal bone loss for an implant?
-<1.5 mm in first year, 0.2 mm per year after
What distance is required between two implants and why?
-3 mm
-Maintain interproximal bone height (provides room for restorative components)
How much bone is required between implant and buccal/lingual wall?
-1 mm
-In esthetic zone, 2 mm posterior to buccal wall is desired for emergence profile and to preserve buccal bone
What are the minimum distances to nasal floor, IAN, mental foramen?
-Nasal floor: 1 mm
-IAN: 2 mm
-Mental nerve: 5 mm anterior to mental foramen
What are the integration timelines for maxilla and mandible?
-Maxilla: 6 months
-Mandible 3 months
-Modern implant surface treatments can reduce time 6-8 weeks for conventional loading
At what temperature does thermal necrosis occur?
-Temps above 47 degrees C
-Keep RPM to 2k or less, ensure pumping motion to allow water to reach osteotomy
What is the minimal intra-arch space for a cement retained and screw retained single implant crowns?
-Cement retained: 5 mm
-Screw retained: 8 mm
What is the minimal interarch clearance for a bar attachment?
12 mm
What happens if you place an implant in a growing child?
-Leads to a submerged implant that is more palatal/lingual
-Out of occlusion and deep to alveolus
-Because of facial and dentoalveolar growth of adjacent bone to implant
-Minimum age of 15 for females or 18 males (growth cessation, wrist x-rays)
How much of a taper is on an implant drill?
-May extend up to 0.5 mm beyond established measurement
What is a CBCT radiation compared to a medical grade CT?
2% of radiation dose
How much bone loss happens after a tooth is extracted?
40-60% bone loss occurs in 36 months
Percentage of papilla present at 3, 4, 5, 6, and 7 mm height (crest of bone to contact point.
3 mm, 100%
4 mm, 100%
5 mm, 98%
6 mm, ,56%
7 mm, 27%
What is the definition of osseointegration?
-Process of which there is bone to alloplastic interface without the interposition of non-bone tissue, which is clinically asymptomatic and is maintained in bone during functional load
-Branemark: Direct structural and functional connection existing between ordered, living bone and the surface of a functionally loaded implant
What is primary stability?
Mechanical stability achieved at the moment of implant placement. Depends on bone quality (density), shape of implant, adequacy of surgical technique
What is secondary stability?
Biological stability achieved after bone healing (osseointegration). Influenced by bone quality, implant surface, overall health of patient and loading protocols
What is distance osteogenesis?
Occurs from existing bone and blood supply (mechanism of osseointegration)
What is contact osteogenesis?
De novo bone formation from osteogenic cells (mechanism of osseointegration)
Describe Type 1 to Type 4 bone
-Classified by Lekholm and Zarb
Type 1: Most dense, composed mostly of compact bone (anterior mandible)
Type 2: Mostly compact bone, surrounded by a core of trabecular bone
Type 3: Thin layer of cortical bone surrounded mostly by trabecular bone
Type 4: Thin layer of cortical bone surrounded by a core of trabecular bone (posterior maxilla)
What is Misch classification of bone?
Bone elasticity increases from D1 to D4. Mostly cortical bone in D1
What is the ideal insertion torque of an implant?
-35 Ncm or more (don’t want to over torque >80 Ncm)
or
-Absence of clinical mobility with 500 g in any direction
-Implant stability quotient (ISQ): A resonance frequency analysis with a number between 1-100. High stability >70, low <60
What are the timelines of immediate, early and conventional loading?
-Immediate: Prosthesis delivered up to 7 days after implant placement
-Early loading: Prosthesis delivered 6-12 weeks after implant placement
-Conventional loading: 3 months for mandible, 4-6 for maxilla
How does smoking affect implant success?
-6.5-20% reduced success rate
How does diabetes affect implant treatment plan?
-Need longer healing times to reach stability
How does osteoporosis affect an implant treatment plan?
-Higher risk of bone grafting procedures
-Similar success rate as healthy patient, may consider longer healing time
How do oral bisphosphonates affect an implant treatment plan?
-Consider 2 month drug holiday
-No longer need a drug holiday (new white paper)
-Look at other co-morbidities
How do IV bisphosphonates or antiangiogenic drugs affect an implant treatment plan?
-Avoid implants in IV bisphosphonate patients/anti-angiogenic drugs.
How does IV Prolia/denosumab affect an implant treatment plan?
-No studies to support discontinuing at this time (review white paper)
How does head and neck radiation affect an implant treatment plan?
-Consider HBO
->60 Gy failure rate higher
-Neweer radiation protocols may limit radiation
How does bruxism/parafunctional habits affect an implant treatment plan?
-Consider a wider implant diameter or stronger alloy implant
-Consider load sharing prosthesis
-Occlusal adjustments of prosthesis
-Longer healing time for loading
What aspects of a physical exam are needed for an implant evaluation?
-Full head and neck exam
-Lip support/gingival display on repose/animation (high smile line, hyperanimation)
-Remaining ridge width
-Papillae positions
-Condition of oral cavity and restorability of other teeth
-Palpate muscles (hypertrophy) to eval for parafunctional habits
-Occlusion: Assess for angle classification and crossbites
-MIO
-Perio health/hygiene. Gingival biotype (assess visibility of probe through gingival sulcus)
-Keratinized tissue (2 mm or more reduces gingival inflammation and increases survivability)
-Inter-arch height (need 8-12 mm for fixed restoration)
-Ridge contour (concavities)
-Diagnostic models/wax up
-Pt photos
How is a periapical film used in implant treatment planning?
-May be used for initial evaluation, intra-op assessment or post-op monitoring
-Difficult to reproduce and assess proximity to vital structures
-Best to observe crestal bone
How is an orthopantogram used in implant treatment planning?
-Generalized scout that allows the visualization of vital structures, bone quality and presence of pathology
-Drawback is magnification
How is a CBCT (Cone Beam Computed tomography) used in implant treatment planning?
-Allows for accurate assessment of distances to vital structures
-View height and width of a ridge
-Digital workflow improves collaboration
-Merging DICOM and STL files from intraoral scans to create guides/stents for surgery
What is a hounsfield unit?
-Assessment give objective measure of bone density in a region
-Based on medical grade CT imaging only
-CBCT imaging utilized gray value and is not directly correlated to Hounsfield units
How is the implant complication managed: Failure to Integrate/Fibrous connection
-Likely due to lack of primary stability due to type IV bone, inadequate prep of osteotomy (over-prep or excessive torque, poor irrigation)
-Treatment is to remove implant and assess need for graft for future implant placement
-Consider wider, longer implant if site allows
-May need soft tissue grafting
How is the implant complication managed: Encroachment to IAN canal?
-Pt may experience an electrical shock or blood may come rushing from osteotomy
-Verify implant position with 3D radiograph
-Remove implant immediately if close to nerve (take pressure off nerve, allow decompression of area)
-No bone graft should be placed
-Steroid application to injury site and oral steroid may help reduce neuropathy
-NSAIDs x3 weeks
-Neurosurgical testing serially
-If anesthesia/dysesthesia x3 months or hypoesthesia x4 months consider microsurgery
If not encroaching, may be injection injury or from preparation of site, consider removing implant