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
How is the implant complication managed: Sinus penetration?
-Penetration of 1-2 mm have shown to be fully covered with sinus membrane and partially by bone in animal studies, no difference in stability
-3 mm or more showed to exposure to sinus cavity without coverage (consider removing implant
How is the implant complication managed: Mandible fracture?
-Usually occurs late once implants are loaded in an extremely atrophic mandible
-Recommend at least 6 mm in vertical heigh and with for implant placement
-May require large recon plate and bone grafting
What is the effect of excessive countersinking during implant placement?
-May cause excessive bone loss and difficulty with connections
-May also result in loss of primary stability
What is peri-implantitis?
-Infectious disease surrounding a load-bearing dental implant with features of bone loss and inflammation of the soft tissue
-Associated with gram-negative anaerobes (P. gingivalis, P. intermedia and aggregatibacter actinomycentemcomitans
-Symptoms: Bleeding on probing, erythema, hyperplasia, probing depth >5 mm, mobility of implant, swelling (pain normally only in acute infection)
-Adequate soft tissue management (increase thick keratinized tissue), helps reduce change of periimplantitis
What is the treatment for per-implantitis?
-Local debridement: Exposure and cleaning with instrument softer than titanium (rubber cup polisher with paste, plastic scalers, interdental brush)
-Decontamination- 40% citric acid with pH of 1 for 60 seconds, chlorhexidine, tetracycline or local antibiotic, laser
-Surgical: Open flap combo of debridement and decontamination with allograft/autograft with membrane
-Removal of implant
How is the implant complication managed: sublingual gland injury or sublingual artery injury?
-Palpate ridge, visualize CBCT for sublingual fossa
-Injury can be caused by perforation through lingual cortical plate
-Ranula or bleed can occur
-Eval floor of mouth and be mindful of the airway
-Sublingual artery can be managed by exploration with cautery/ligation (consider hospital setting)
-If ranula, consider removal of sublingual gland
How does bone grafting heal?
-Creeping substitution: A process by which osteoclasts resorb bone creating new vascular channels with osteoblastic bone formation resulting in new haversian systems. Laying down new bone and subsequent resorption of old bone
What are the definitions of osteogenic, osteoinductive, osteoconductive?
-Osteogenic: Transfer of osteocompetent cells for de novo bone formation (autografts)
-Osteoinductive: Bone formation by stimulation of host mesenchymal cells to differentiate (allograft, BMP)
-Osteoconductive: Provides scaffolding for new bone formation by native bone (no proteins or cells (xenograft)
What is an autogenous bone graft?
-Composed of tissue from the same person
-Osteogenic, osteoinductive and osteoconductive
-Gold standard
-Disadvantage is second surgical site
What is an allogenic bone graft?
-Graft taken from another individual of same species but different genotype
-Osteoinductive and osteoconductive
-Strict screening for infections by manufacturer
-Comes either mineralized freeze-dried bone allograft or demineralized freeze-dried bone allograft. Both provide type I collagen
-To reduce antigenicity: Freeze-drying, irradiating, dry heating
What is a xenograft?
-Grafts taken from another species
-Osteoconductive
-No organic component
-Treated at 900 degrees C, risk of prion transmission is theoretical only
-Hydroxyapatite crystalline structure allows ingrowth of vessels and migration of osteogenic cells
What is BMP?
-Recombinant Human-Bone Morphogenetic Protein-2
-Part of transforming growth factor b superfamily
What is the formulation and handling of BMP?
-Water soluble protein requiring a collagen type 1 carrier (acellular collagen sponge) for slow release. Requires 15 min of absorption
-Concentration of 1.5 mg/cc mixed with sterile water
How does BMP work?
-Chemotactic for pre-osteoblasts and stem cells
-Induces expression of VEGF by osteoblasts
What is the only label use for BMP?
-Sinus augmentation or alveolar ridge ridge reconstruction
What can you expect with BMP use?
-Expect extensive edema due to influx of fluid and cells from the chemotactic and neovascularization activities of BMP
-Consider post-op steroids/icing of tissue
How long of a healing time do you need after BMP?
-6 months
What are contraindications to BMP?
-Pregnancy
-Allergy to rhBMP or typeI bovine collagen
-Active infection
-Active or history of malignancy at site
-Skeletal immaturity
What is PRP (Platelet rich plasma)?
-Platelet-derived growth factors encourage cell division and osteoid production as well as endothelial cell replication
-PRP is a blood blot that is highly concentrated with platlets 1 million platlets/mL
How is PRP made?
-Collection tubes with citrate dextrose as an anticoagulant
-Platelets are spun down in either two or one spins
-Activated via the addition of CaCL2 and thrombin
What is PRF (platelet rich fibrin)?
-Improved formulation of PRP, serve as a 3D scaffold to biologically enhance healing
How is PRF made?
-Centrifuge w/o anticoagulants
How does PRF work?
-Fibrin matrix contains platelets and leukocytes as well as a variety of growth factors and cytokines (TGF-b1, PDGF, VEGF, IL-1b, IL4, IL6)
-Promote the proliferation and differentiation of of osteoblasts, endothelial cells, chondrocytes, and fibroblasts
What is the Cawood and Howell classification?
Class 1: Dentate
Class 2: Immediately post-extraction
Class 3: Well rounded ridge, adequate height and width
Class 4: Knife edged ridge, adequate height, inadequate width
Class 5: Flat ridge, inadequate height and width
Class 6: Depressed ridge with varying degrees of basal bone loss that may be extensive but follows no pattern
What are the anatomical dimension of the maxillary sinus and sinus membrane?
-15 mL per sinus, ~2.5 cm of width and 3.75 cm height
-Sinus ostium is located in the superior medial sinus wall (halfway in the AP distance ~25 mm above antral flor. Opens to the middle meatus via the infundibulum
-Underwood’s septa- 5 bony projections from floor of maxillary sinus which can cause compartments. Makes sinus grafting more difficult. At least one septum present in 90% of patients
-Schneiderian membrane 0.13-0.5 mm thick
What is the vascular supply to the maxillary sinus?
Branches of maxillary artery
-Posterior superior dental artery
-Anterior superior dental artery
-Greater palatine
-Lesser palatine
-Lateral and posterior nasal branches of the sphenopalatine
-Venous flow occurs via the facial vein, sphenopalatine vein and pterygoid plexus
What technique should you use based on remaining alveolar height?
<4 mm: Lateral approach and delayed implant placement
>4 mm: Lateral approach with simultaneous implant placement
6-8 mm: Transalveolar approach with simultaneous implant placement
10+ mm: Immediate implant placement
What medical conditions are important to discuss with the patient prior to sinus lift surgeries?
-Upper respiratory tract infection
-History of sinusitis or chronic sinus disease (acute sinusitis: delay until resolved)
-Sinus or nasal surgeries
-Otitis media
-Smoking (doesn’t affect sinus lift but implant viability)
-Chronic steroid use (may thin membrane)
What is meniere’s disease?
-Ménière disease is a disorder caused by build of fluid in the chambers in the inner ear. It causes symptoms such as vertigo, nausea, vomiting, loss of hearing, ringing in the ears, headache, loss of balance, and sweating.
-Contraindication to Transalveolar sinus lift approach
What radiograph do you obtain prior to sinus lifts?
-CBCT
-Rules out pathology
-Allows identification of remaining alveolar height and width
-Identifies septae, air fluid levels, presence of polyps
-Antral pseudocyst/mucocele: Should be removed/aspirated 6 months prior to lift and re-evaluated for recurrence. A relative contraindications
Describe your technique for the lateral approach of a sinus lift.
-Local anesthetic
-Incision should be palatal to the alveolar ridge (helps reduce risk of post-op fistula if implant not planned). Crestal flap if implant is planned at time of augmentation
-Ostectomy: Thin out lateral sinus wall exposing sinus or window outline (quadrilateral ostectomy) to act as a superior bony roof. The inferior extent should be 1 mm superior to the floor.
-Elevate sinus membrane with sinus curettes. Check for perforations
-Graft (start medially), then implant, then more graft
-Place absorbable membrane at bony window
-Suture watertight closure flap
Describe your technique for a transalveolar approach?
-Local anesthetic
-Crestal incision to expose ridge
-Start osteotomy with 2 mm twist drill to 1 mm below sinus floor
-Guide pin placed and PA taken to ensure sub-sinus ideal position
-Osteotomies of different gauges are now malleted 2 mm higher than native bone using up to appropriate gauge of planned implant
-Test with valsalva and hand mirror to eval sinus integrity
-Placement of autograft/allograft and work into sinus space created to dome sinus
-Place implant
-Repair incision with sutures
What is your post-operative management for a sinus lift patient?
-Sinus precautions: No nose blowing for 2 weeks, sneeze with mouth open, no pressure changes such as scuba diving , use of straws, or wind instruments
-Antibiotic with sinus coverage (amoxicillin 500 mg q8h x7 days), oxymetazoline 0.05% q12 h for 3 days, saline nasal spray prn, pseudoephedrine 30 mg q6h prn congestion
-Allow 6 months for graft consolidation
How is a sinus perforation treated from a sinus lift procedure?
-If 2-3 mm will likely self repair by folding over or blood clot formation. Consider collagen wound dressing.
-If 5-10 mm, consider bioabsorbable collagen membrane
-If >10 mm, assess possibility of using collagen membrane to completely cover graft. If not possible, abort surgery and return in 3 months. At this point the sinus will be thicker in the area of perforation
How is an antral septae treated during a sinus lift procedure?
-Make two windows and treat as two compartments or osteotomize septum along sinus floor
How is bleeding treated during a sinus lift procedure?
-Pack sinus with epinephrine soaked gauze.
-Enlarge opening and attempt to visualize bleeder for cauterization
-Clamping vessel may cause further damage and increase bleeding
How is infection/acute sinusitis treated (complication of sinus lift)?
-Common side is swelling over lateral window site with pain and localized tenderness
-Antibiotic with respiratory flora coverage
-If no spontaneous drainage, surgical drainage is indicated with consideration for graft removal
How is graft exposure treated (complication of sinus lift)?
-Gentle daily normal saline irrigation and chlorhexidine rinses
How is a blockage ostium treated (complication of sinus lift)?
-Caused by overfill or migration of particles, infection or inflammation.
-Access extent of sinusitis with imaging
-Place on steroids and antibiotics
-If no improvement, consult with ENT
How is vertigo treated (complication of sinus lift)?
-Usually resolves on its own
-Attempt Epley maneuver (series of head movements)
-Anti-vertigo drugs like meclizine 50 mg PO BID for symptomatic treatment
What is the location of a mandibular symphysis bone graft harvest?
-Harvest lateral to midline, 5 mm below canine
-Can be done bilaterally
-Preserve anterior chin contour
How much time is required for integration of a mandibular symphysis bone graft?
-5 months
How long after a graft can you obtain a second graft from a mandibular symphysis?
-Must wait 10 months from initial harvest
Describe your technique for a mandibular symphysis bone graft.
-Infiltration of local with vasoconstrictor
-Incision from canine to canine, through mucosa, 1 cm below the mucogingival junction then through mentalis and periosteum
-Expose symphysis using periosteal elevator (don’t completely remove mentalis muscle)
-Outline planned osteotomy with bur and ensure 5 mm from canine roots and 5 mm from inferior border. Try to preserve midline region
-Remove graft with a curved chisel, may access cancellous bone too
-Close in layers with 4/0 deep and 3/0 resorbable for mucosa
-Pressure dressing over chin
How long does a ramus graft take to integrate?
-5 months
Describe your ramus graft surgical technique.
-Local anesthetic
-Open and prepare graft recipient site to confirm graft size
-Sharp incision along external oblique ridge from level of maxillary oclusal plane to distal of third molar
-Periosteal elevator to reflect periosteum and temporalis tendon
-Outline graft
-Make osteotomy (end 5 mm distal to last molar)
-Remove graft
-Close with 3/0 vs 4/0, can apply collagen plug
What are risks with maxillary tuberosity graft harvest?
-Older patients have more fatty marrow
-Contraindicated if highly pneumatized sinus or sinus infection
-Risk of sinus exposure if over aggressive harvesting
Describe your technique for a maxillary tuberosity bone graft harvest.
-Local anesthesia
-3-corner full thickness flap with distal release
-Rongeur used to remove bone or chisel
-Close with 3/0 resorbable
How do you manage an exposure of a block graft?
-Overall poor prognosis
-Inform patient
-Chlorhexidine rinses x4 weeks with debridement/reduction of graft
-Don’t open wound and attempt to re-suture: Increases micro load, large dehiscence and possible flap necrosis
How do you manage a screw exposure for a block graft?
-Decreased bone volume up to 25% is expected
-Keep screw clean with chlorhexidine rinse and tooth brushing
How do you manage membrane exposure for a block graft?
-Titanium membranes commonly exposed and are treated with 0.5% chlorhexidine gel or 0.12% rinse
-Membranes of e-PTFE need complete removal with graft as the membrane is quickly vegetated with microorganisms
-Resorbable membrane will break down quickly with resorption of the bone
What do you do if you notice mobility of the graft at time of implant placement?
-Graft not properly integrated
-Remove covering soft tissue, provoke bleeding and fragment should be re-secured with screws
-Allow additional 4 months of healing
What is the interpositional/sandwich graft?
-Used in esthetic zone, anterior maxilla
-Blood supply maintained from lingual/palatal pedicle
-Vertical bone height of 5 mm can be expected
-Bring tissue with osteotomized bone
-Final position usually more lingual/palatal
What is your technique for an interpositional/sandwich graft?
-Local
-Elevate flap with a horizontal component in vestibule, vertical limits at papillae of adjacent papillae
-Divergent wall osteotomies to allow for a free path of advancement
-Hole graft in maximal expansion and place a fixation plate
-Graft around gaps of the osteotomy
-Close wound
-Allow 6 months of healing prior to implant placement
What is the ridge split technique?
-More common in maxilla than mandible, need 10 mm of bone height in maxilla or 12 mm above canal in mandible
-Need minimum of 3 mm width
-Consolidate/heal for 6 months
Describe your ridge split technique
-Local
-Gingival incision midcrest
-Minmal reflection of mucoperiosteal flap
-Use piezotome or saw to make osteotomy parallel with residual ridge
-Use increasing spatula osteotomes to start widening
-Graft the gap
-Collagen membrane
-Close
-Heal 6 months
Describe indications for distraction osteogenesis for implant site development.
-Based on tension-stress, brings bone and tissue
-Defects 6-9 mm in height are often indicated for distraction
-Difficult to control vector (convergent lingual osteotomy to avoid lingual tipping)
What are the regnerate zones of distraction osteogenesis?
-With expansion of bony segments, a regenerate is formed
- Fibrous tissue zone: Located centrally and is organized type I collagen
- Extended bone formation: Located on both sides of the fibrous tissue zone. Mesenchymal and osteoblasts synthesize early bone spicules
- Zone of bone remodeling: Osteoblastic and osteoclastic activity causing b one remodeling
- Zone of mature bone: Located at the edges of the osteotomies
What are the phases of distraction?
- Surgical procedure: Ensure divergent walls to allow passive movement. Incision should be in attached gingiva if possible to encourage gingival growth on distraction. 1 mm is allowed between roots to prevent injury during osteotomy
- Latency period (3-7 days): mobilizing too early will cause high level of fibrous tissue and low bone density
- Activation phase: 0.7-1.3 mm per day recommended. If too much (>2mm), impaired angiogenic response and fibrous bone, if too slow risk of premature ossification. Better to do multiple lesser turns throughout the day rather than one big turn per day (better for soft tissue)
- Consolidation (3 months): Keep device on until seeing radiographic evidence of bone healing. Can place implants at time of device removal
Complication management: Immobility of transport segment with distraction osteogenesis.
-Incomplete osteotomy or poor osteotomy design that leads to blocking of transported segment. Treatment is to retrace osteotomies
Complication management: Loss of distractor with distraction osteogenesis
May be due to poor bone stock. Options are to replace distractor or consideration of bone graft and segment fixation with plate
Complication management: Tissue dehiscence with distraction osteogenesis
Slow the rate of distraction
-This allows for short period of tissue healing. Consider smoothing edges of segment if there are sharp areas
Complication management: Resorption of transport segment with distraction osteogenesis
-Due to interruption of blood supply that is most likely due to over reflection of tissue
-Allow for prolonged latency period before further distraction
Complication management: Inadequate vector of transported segment
-Can avoid using extraoral devices or dental wiring to aid in vector guidance
-May also consider other ridge augmentation techniques to overcome the malpositioned regenerate
What situations are zygomatic implants indicated in?
-Good for large maxillary ablative defects, traumatic defects, severely atrophic maxillae, cleft palate unrepaired defects, patient refusal of a sinus augmentation
What is the success rate of zygomatic implants?
-97%
What is the length of zygomatic implants?
-30-52.5 mm length
-4 mm diameter in apical 2/3
-5 mm diameter in alveolar 1/3
-45 degree tilted connection to correct for angulation
What is the intraoral and zygomatic position of a zygomatic implant?
-Enter oral cavity at palatal side (This reduces tongue space and disrupts palatal contour of prosthesis)
-Placement should be in the premolar region introrally
- Placement into the mid portion of the zygomatic body at zygomatic side
What would you expect with a zygomatic implant in a patient that has sinusitis
-May compromise survival
-Address sinusitis prior to zygomatic implant placement
-Higher risk of post-op sinus infection
What is the healing time for a zygomatic implant?
-3-4 months
When can a zygomatic implant be immediately loaded?
->40 Ncm
What is the intrasinus technique for a zygomatic implant?
-Create a lateral sinus window to push sinus membrane from implant.
-May bone graft around implant and sinus cavity
What is the extra sinus technique for a zygomatic implant?
-Allows more crestal emergence
-Reduces sinus complications
-Increases tongue space (allows for decreased risk of altered speech and increase hygiene space)
-Disadvantage: Mid-portion of implant is in direct contact with soft tissue which may cause exposure and perforation
Why is cross-arch stabilization needed for zygomatic implants?
-Due to long moment arm of zygomatic implant
What are the two components of a locator attachment?
-Male part: Consists of an implant screw-metallic abutment
-Female part: Metallic cap lined with nylon (different color) which is anchored to the denture
How many degrees can a locator attachment correct?
-Can correct non-parallel implants up to 40 degrees
What is the minimum space requirement for an implant-supported overdenture with locator attachment?
-8.9 mm of vertical restoration space and 9 mm of horizontal space
What is an O RIng or ball attachment?
-Similar to locator
-Doe not require much prosthetic space
-Allow hinge and rotational dislodgements
How is AP spread determined?
-Distance between a line drawn between the distal sides of the posterior implants and a parallel line through center of most anterior implants
What is an ideal AP spread?
-1 cm (when 4-5 implants are placed)
How much cantilever can be supported by AP spread?
-2 times the AP spread
-Some say 1.5x AP spread
-Not beyond 20 mm
Where is the most force/load delivered on a cantilever?
-Load delivered to posterior implants
-Can lead to screw fractures and prosthesis/implant failure
What are advantages of an implant supported fixed prosthesis?
-Psychological and psychosocial advantages of having a fixed prosthesis
-Increased bite force
-Patient prefers not having the palatal coverage in the denture
-Improves phonetics, appreciation of temperature and taste
What is a hybrid prosthesis?
-Denture teeth embedded in a heat-cured acrylic resin supported by a rigid metal framework
What is a metal-ceramic prosthesis?
-Can be cast or milled.
-Tissue response is excellent, acceptable esthetics, little wear on occlusal surfaces
-High cost
What is a zirconia prosthesis?
-Aesthetic
-Biocompatible
-Less wear than porcelain surfaces
-High strength
-Minimal abrasiveness
What data components are required in guided surgery?
-CBCT (DICOM information). Teeth must be partially seperated
-Intraoral scan (STL file) or stone models
