Implantology

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© Springer Nature Switzerland AG 2021

R. Reti, D. Findlay (eds.)Oral Board Review for Oral and Maxillofacial Surgerydoi.org/10.1007/978-3-030-48880-2_4

4. Dental Implantology

Waldemar D. Polido1  , Akshay Vij2, Robert Reti3, Sherrill Fay4 and Gregg W. Hosch3
(1)

Oral and Maxillofacial Surgery and Center for Implant, Esthetic and Innovative Dentistry, Indiana Universtiy School of Dentistry, Indianapolis, IN, USA
(2)

Missouri School of Dentistry and Oral Health, ATSU, St. Louis, MO, USA
(3)

Southwest Oral Surgery, St. Louis, MO, USA
(4)

The Mount Sinai Hospital, Division of Oral and Maxillofacial Surgery in the Department of Otolaryngology, New York, NY, USA
 
 
Waldemar D. Polido
Keywords

OsseointegrationDental implantsHydroxyapatiteElectrowettingPlatform switchingZirconiaBisphosphonatesDenosumabImplant stability quotientAutogenous boneAllogeneic boneXenograftRecombinant human bone morphogenic proteinPlatelet-rich plasmaCawood and Howell bone classificationSchneiderian membraneSinus liftSinus lift lateral approach (Tatum technique)Sinus lift (summer technique)Tibia bone graftRamus bone graftMandibular symphysis bone graftMaxillary tuberosity bone graftInterpositional graftSandwich graftRidge splitDistraction osteogenesisZygomatic implantImplant bar attachmentHader barRound barWrap around barMontreal barLocator attachmentMagnetic locator attachmentAnterior posterior spreadGuided implant surgeryBone graftsOnlay bone grafts

Dental Implant Basics

  • An implant system can be divided into an endosseous part, a transmucosal section, and a prosthodontic interface.

  • A dental implant is the surgical component that interfaces mechanically and biologically with the bone to support a dental prosthesis.

  • Most commonly used implants are screw root forms that are threaded into a prepared osteotomy, reliant on threads for initial stability via mechanical retention.

  • Implant body can be divided into a crest module, body, and an apex (see Fig. 4.1).

  • Implants can be designed with the neck of the implant supra-crestal (tissue level), crestal (bone level), or sub-crestal.

  • Supra-crestal (soft tissue level) implants are favored to reduce marginal bone loss or saucerization around implants when compared to butt-joint bone level implants, by moving the neck above the bone and preventing bacterial colonization of the microgap. With the advent of platform switching, and internal conical connections, that can also be obtained with bone level or below the bone level implants.

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Fig. 4.1

Dental Implant. Straumann BLX Dental Implant. (Image Courtesy of Straumann)

Length
  • Important for implant primary implant stability, and influences immediate loading. Once secondary implant stability has been achieved (osseointegration), length is not as important. (Side note: thread pitch, drilling sequence, and bone quality also play a great role in gaining stability prior to osseointegration) [1].

  • Increases surface area of bone-implant interface.

  • Most stress of implant at first 5 mm making diameter important in stress reduction.

Diameter
  • Larger diameter implants increase the surface area of bone-implant interface.

  • Disperses forces in poor bone, thereby reducing risk of overload.

  • Reduces the magnitude of force to system when used as part of bridgework or cantilever.

  • Increased diameter can allow for better emergence profile for larger crowns. In modern platform switch implants this is not the case, since the choice of prosthetic components is independent of the implant diameter.

  • Increased diameter of crest module size decreases the risk of implant fracture and prosthetic component fracture.

  • Concern for stress shielding from wide diameter implants leads to bone atrophy due to lack of strain transfer to the bone.

  • Increased diameter implants require a larger drilling, thereby reducing bone thickness around the implant. There is a current trend to not use wide body implants (>5 mm diameter) in order to preserve more alveolar bone.

  • Narrow (Reduced Diameter) implants are indicated in the anterior region of the maxilla or mandible. Narrow implants are more prone to implant fracture and internal connection damage, especially when placed in the posterior region. When placed in the posterior region, they shoud be splinted with other(s) implants. Modern alloys (TiZi) provide additional mechanical resistance to narrow implants, increasing survival rates. 

Shape
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 in poor bone quality sites.

  • Reduced apical width allows for placement in constricted sites.

  • Reduced overall surface area increases with taper.

Implant Surface Modifications
  • Hydroxyapatite (HA) – HA-coated implants are no longer used as the processing methods convert HA to tricalcium phosphate which is rapidly absorbed and is easily colonized with bacteria. Additionally, there have been problems with delamination of HA.

  • Micro-rough surfaces 0.5–2.0 microns (minimally rough 0.5–1, intermediately rough 1.0–2.0, and rough 2.0–3.0 microns) create peaks and depressions in the implant to increase surface area. Roughened surfaces can be created by acid etching with such chemicals as sulfuric, hydrochloric, and hydrofluoric acids. Spraying the implant surfaces with titanium oxide, hydroxyapatite, and aluminum oxide is another option. Micro surface roughness causes an increased implant to bone surface area, clot retention, aids in earlier osseointegration, and leads to harder and stronger bone around implants by increasing mRNA expression of osteonectin and osteocalcin [2].

  • Electrowetting – wettability of implants important to improve plasma protein adherence and mesenchymal cell adherence and differentiation. Many methods are available, but commonly fluoride and magnesium ions are used. Some manufacturers package implants in saline.

Crest Module
  • Microthreads – preserves both bone and soft tissue around cervical portion of implant fixture by dissipating forces around crest. Can facilitate higher incidence of peri-implantitis due to plaque retention if the implant is exposed to the oral cavity.

  • Microgap – connection between implant and abutment.

  • Anti-rotational component – platform of the crest module has an anti-rotational feature to retain prosthetic component. This can be a platform such as an external hex (external connection) or within the implant body itself (e.g., internal hex, Morse taper, octagon, internal grooves, or pins).

  • External connection – connection to implant that is superior to coronal portion of implant creating a butt joint connection. Have higher prevalence of screw loosening, rotational misfit, and microbial penetration. Classic example is the External Hexagon connection.

  • Internal connection – internal connection to implant, seen in most modern implants. Can have parallel walls (Internal Hexagon) or morse cone type (connical connection). Conical connection preferred vs. flat connection as it can disperse load and prevent microgap elongation on function with fluid invasion. Connical connections have Improved microbial seal, reduced screw loosening, increased joint strength, and increased platform switching abutment options.

  • Platform switching – it is an horizontal offset between the implant connection and the cervical area of the abutment. This method can help to reduce crestal bone loss using a narrower restorative abutment compared to the crest module which leads to a more superior position of the epithelial attachment around the neck of the implant. This technique also medializes the implant abutment interface, which redirects stress from the crestal bone [3]. Inflammatory infiltrates are positioned away from the crestal bone leading to less bony destruction/loss [4, 5].

Materials
  • Titanium is a metal that presents low-weight, high-strength/weight ratio, low modulus of elasticity, excellent corrosion resistance, excellent biocompatibility, and easy shaping and finishing.

  • Most commonly used: Grade 4 pure titanium (cpTi), titanium-zirconium alloy, and titanium-6 aluminum-4 vanadium (Ti 6AL-4V).

  • Biocompatibility due to surface dioxide layer that forms almost instantaneously upon exposure to air (2–10 nm by 1 second). Important role in corrosion resistance, biocompatibility, and osseointegration. This oxide layer is composed of titanium dioxide (TiO2).

  • Zirconia: Implants produced with zirconia are biocompatible, bioinert, radiopaque, and have a high resistance to corrosion flexion and fracture. They are typically considered “non-metallic” and are white in color.

Criteria for Implant Success
  • Immobile when tested clinically.

  • No radiographic evidence of peri-implant radiolucency.

  • Vertical bone loss is less than 0.2 mm annually after the first year of service of implant.

  • Implant performance is characterized by an absence of persistent or irreversible signs and symptoms of pain, infection, neuropathy, paresthesia, violation of mandibular canal.

    (These aforementioned success criteria were based on radiography, clinical signs, and symptoms. There are other factors today that we would take into account to establish implant success. New parameters to take into account include esthetics, soft tissue integrity/appearance, patient satisfaction, and prosthodontic parameters) [6].

Important Numbers to Know About Implants
  • Distance of 1.5 mm between implants and natural teeth to allow for lateral biologic width. Violation leads to bone loss around implants and adjacent structures.

  • Normal bone loss is <1.5 mm for the first year and 0.2 mm per year after (These numbers do not take into account the prosthetic construct used. For example, an implant supported FPD where forces are evenly distributed may have less bone loss per implant in the entire construct. Platform switching has also lessened the microbial bioburden that contributes to overall bone loss).

  • A minimum distance of 3 mm between two implants must be adhered as to maintain interproximal bone height which provides room for restorative components.

  • Minimum Distance of 1 mm of bone between implant and buccal/lingual wall. In the aesthetic zone, 2 mm posterior to buccal wall is desired for emergence profile and to preserve the buccal bone.

  • Minimum Distance of implant apex is 1 mm from nasal floor.

  • Minimum Distance of implant apex is 2 mm above the inferior alveolar nerve.

  • Implant body 5 mm in front of mental foramen.

  • Head of bone level type implant should be 2–3 mm below gingival margin of planned crown to allow space for emergence profile.

  • Each 0.25 mm increase in diameter yields a 10% increase in surface area.

  • Classic integration timelines for smooth surface implants are 3 months for the mandible and 6 months for the maxillae. Modern implants surface treatments (SLA) can decrease time to as early as 6–8 weeks for conventional loading.

  • Ensure that drills are sharp and use new drills often, especially for dense bone.

  • Thermal necrosis during drilling occurs above temperatures of 47 °C. Keep RPM to 2000 or less and ensure pumping action during drilling to allow water to reach base of osteotomy.

  • Minimal intra-arch space of 5 mm for cement retained and 8 mm for screw retained for single crowns. More inter-arch space may be needed for overdentures or fixed hybrid prosthetics.

  • Minimal interarch clearance for a bar attachment is 12 mm.

  • Implants in a growing child will lead to a submerged implant, that is more palatal/lingual, out of occlusion and deep into alveolus, secondary to facial and dentoalveolar growth adjacent to the implant. Implants should be placed after confirmation of growth cessation by following growth indices for 1 year such as hand-wrist or spine radiography. Some authors recommend a minimum age of 15 for females and 18 for males. Literature shows reports of adult patients with continous alveolar growth, leading to vertical defects around the implant area. 

  • Most implant drills have tapered tips of 0.5 mm beyond their established measurement.

  • In comparison to a medical grade CT, cone beam computed tomography (CBCT) uses about 2% of radiation dose.

  • 40–60% of expected bone loss occurs during the first 36 months after the tooth is extracted.

  • Contact point to crest of bone with presence of papillae [7]:

    • 3 mm – 100%

    • 4 mm – 100%

    • 5 mm – 98%

    • 6 mm – 56%

    • 7 mm – 27%

Osseointegration

  • Process of which there is a bone to alloplastic interface without the interposition of non-bone tissue, which is clinically asymptomatic and is maintained in bone during functional load (based on electron micrographic findings).

  • Classic definition of osseointegration by Branemark: osseointegration is the direct, structural, and functional connection existing between ordered, living bone and the surface of a functionally loaded implant.

  • Primary stability: mechanical stability achieved at the moment of implant placement. Depends on bone quality (density), shape of implant, and adequacy of surgical technique. Can be optimized when these three factors are considered and technique is adequate for existing type of bone and implant placed.

  • Secondary stability: biological stability, achieved after bone healing (osseointegration). Influenced by bone quality, implant surface, overall health of patient, and loading protocols.

  • Two mechanisms of osseointegration: (1) distance osteogenesis occurs from existing bone and blood supply and (2) contact osteogenesis (de novo bone formation) from osteogenic cells.

Bone Quality

  • Implant survival is multifactorial but arch location plays a vital role. Most failures occur in softer bone.

  • Bone density is directly correlated to bone strength.

  • Lekholm and Zarb, in 1985, classified based on the ratio of cortical and cancellous bone using radiographs [8].

    • Type 1 bone is composed mostly of compact bone.

    • Type 2 is mostly a compact bone surrounded by a core of trabecular bone.

    • Type 3 is composed of thin layer of cortical bone surrounded mostly by trabecular bone.

    • Type 4 is composed of thin layer of cortical bone surrounded by a core of low-density trabecular bone.

  • In 1998, Misch described bone densities in the edentulous maxilla and mandible based on macroscopic specimens based on cortical and trabecular bones. In 1999 Misch updated his classification to include bone density independent of region of jaw while taking into consideration Hounsfield units. Classes range from D1 to D4, with D1 being the most dense (see Fig. 4.2) [8].

  • Misch classification: Bone elasticity increases from D1 to D4, leading to increased micro strain and implant mobility leading to failure. The cortical cancellous ratio decreases from D1 to D4.

  • Crestal strain and stress transfer increase with decreasing bone density.

  • As bone density decreases, it is prudent to treatment plan longer/wider implants with maximization of the number of implants and designs, which increase surface area.

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Fig. 4.2

Misch bone density classification. (Modified from Torabinejad et al. [21])

Testing for Implant Stability

  1. 1.

    Insertion torque of an implant should ideally be 35 Ncm or more. Over Torquing >80 Ncm may impair implant healing.

     
  2. 2.

    Absence of clinical mobility with 500 g in any direction.

     
  3. 3.

    Implant stability quotient (ISQ) – a resonance frequency analysis with a number between 1 and 100. High stability, >70 ISQ; medium stability, between 60 and 69 ISQ; and low stability, <60 ISQ.

     

Loading Protocols

  1. 1.

    Immediate loading – prosthesis is delivered up to 7 days after implant placement.

     
  2. 2.

    Early loading – prosthesis is delivered 6–12 weeks after implant placement. Some implant surfaces consider 8 weeks as conventional loading.

     
  3. 3.

    Conventional loading – prosthesis is delivered after osseointegration is achieved. Classic period is 3 months for mandible and 4–6 months for maxilla.

     

Pre-surgical Workup

CC/HPI: Patient’s desires or concerns, prior prosthetic reconstructive efforts, expectations, how long has the patient been without teeth, and causes of tooth loss.

REMEMBER: the patients want teeth and not implants. Make sure that all surgical procedures follow a restoratively-driven plan, in order to ensure the best possible restorative outcome.

Medical History/Medication History/Surgical History
  • Smoking – reduced success rate, about 6.5–20% lower than in nonsmokers [9].

  • Diabetes – need longer healing times to reach stability [10, 11].

  • Osteoporosis – studies have found similar rates of implant failure in patients suffering from osteoporosis vs patients with normal bone densities. Some weak evidence reduced bone healing and may consider longer healing times [1214]. Higher risk for failure of bone grafting procedures in this patient population [15].

  • Oral bisphosphonates – AAOMS recommends a drug holiday of 2 months, for patients taking oral bisphosphonates, prior to surgery. The bisphosphonate should be held until osseous healing has occurred [16].

  • Avoid implants in patients using IV bisphosphonates or antiangiogenic drugs.

  • IV bisphosphonates or antiangiogenic drugs for cancer.

  • Denosumab – no studies to support discontinuation at this time [16].

  • Radiation of the head and neck: consider HBO if necessary (>60 Gy); failure rates similar with the advent of newer radiation protocols [17].

  • Parafunctional habit – consider wider diameter or stronger alloy implants. Judicious planning of designing load-sharing prosthetics, occlusal adjustments of prosthetics, and longer healing time for loading bearing bone formation may help counteract the destructive forces of parafunctional habits.

  • TMD complaints –assess for placement and length of procedure.

  • Debilitating disease – e.g., rheumatoid arthritis, scleroderma, or Parkinson’s disease that may cause xerostomia due to medications and make dental care difficult to maintain. Consider home assistance and prosthetic type, fixed vs. removable.

Evaluation
  • Head and neck exam as expected on all patients.

  • Lip support/gingival display on repose and animation. Short upper lip, high smile line, or hyperanimation may reveal artificial teeth and flange.

  • Width of remaining ridge. If edentulous a prosthesis with flange may be desirable vs. fixed crown and bridge to provide lip support and better esthetic outcome.

  • Papillae position and gingival margins of adjacent teeth.

  • Condition of the oral cavity and restorability of teeth to determine best prosthetic type.

  • Palpation of muscles of mastication and observe for hypertrophy of masseter, concern for parafunctional habit. Assess for wear pattern of teeth, bruxism, or occlusal interferences.

  • Occlusion – assess for angle classification, scissor bites, and cross bites and how these occlusions may affect implant success. May create prosthesis design issues or cantilevers. May require orthognathic procedures.

  • Inter-incisal opening ability to access site of implant.

  • Periodontal health/oral hygiene. Periodontal probings to ensure healthy cervical margins of adjacent teeth. Higher failure rate in those with poor periodontal status and poor hygiene (should be controlled before dental implant placement).

  • Gingival biotype: assess visibility of probe through gingival sulcus. Thick biotype associated with greater soft tissue stability, less recession, and is more resilient to oral flora.

  • Keratinized tissue – 2 mm or more of keratinized gingivae reduces gingival inflammation, increases implant survivability, and reduces marginal bone loss.

  • Interarch crown height space, ideal 8–12 mm for fixed restoration or 12 mm or more for bar connections.

  • Ridge contour – bone loss may push prosthesis palatal/lingual if restored with implant which will lead to extensive ridge overlap or food trap. Bone grafting may be indicated.

  • Articulated diagnostic models aid in planning with diagnostic wax-ups, stent fabrication, and easier measurements such as for prosthetic space.

  • Photos of patient in repose, full smile, lateral views for implants in the aesthetic zone.

Radiography

  • Overall use is to rule out pathology, assess bone quality, dental relationships, and proximity to vital structures.

  • Periapical films – may use for initial evaluation, intraoperative assessment, and postoperative monitoring. However, periapical films lack reproducibility and it is often difficult to assess the proximity of vital structures (best indicated to observe crestal bone around adjacent teeth especially in the aesthetic zone).

  • Orthopantogram – used as a generalized scout film that allows the visualization of vital structures, bone quality, and the presence of pathology. A major drawback is magnification. Vertical magnification is more uniform than horizontal magnification and can be overcome by radiographic markers of a known size.

  • Cone Beam Computed tomography – allows for accurate assessment of distances to vital structures. Can view the height and width of ridge to plan for bone graft needs. Software allows for easier planning with dental implant database. Digital workflow improves collaboration and interaction with prosthodontic plan. Involves merging and superimposition of DICOM and STL files (created from intraoral or model scanning) data to create a fully guided stent for guided surgery. For the vast majority of implant cases, a CBCT is the indicated imaging modality. 

    Hounsfield unit assessment gives objective measures of bone density in region and is based on medical CT imaging. CBCT imaging utilizes a gray value and is not directly correlated to Hounsfield units.

Implant Complications of Implant Placement

Failure to Integrate/Fibrous Connection

Likely due to lack of primary stability, type IV bone, inadequate preparation of osteotomy (over-preparation of osteotomy, excessive torque when placing implants in type 1 bone, poor irrigation leading to bone necrosis and infection). Treatment is to remove the implant and assess the need for graft for future implant placement or if ridge allows preparing the site for a wider or longer implant. Soft tissues recession may require additional soft tissue graft or place implant in a secondary procedure. 

Encroachment to IAN Canal

Patient may express discomfort as though they experienced an electrical shock, or a rush of blood may come through the osteotomy site. Verify implant position with radiography (3D imaging preferred). The implant should be removed immediately if noted to encroach upon the nerve. In theory removal allows psychological therapy for the patient, pathway for escapement of debris and irritants, ease for future nerve repair, and takes pressure of the nerve (if not severed). No bone graft should be placed into the site. Steroid application to the injury site and high-dose steroids orally for a week may help reduce neuropathy. NSAIDs such as ibuprofen 800 mg q 8 h for 3 weeks also have been recommended in the literature. The benefit of steroids and NSAIDs is questionable. Neurosensory testing is evaluated serially. If the patient has anesthesia/dysesthesia for 3 months or hypoesthesia for 4 months, then consider microneurosurgery. If no evidence of encroachment with patient complaining of a neurological disturbance, then one cannot rule out injection injury. Consider removing implant.

Sinus Penetration

Implant penetration into maxillary sinus of 1–2 mm has been shown to be fully covered with sinus membrane and partially by bone in animal studies. No difference in stability is noted. Penetration of 3 mm or more showed exposure into the sinus cavity without any coverage.

Mandible Fracture

Usually occurs late once implants are loaded but can also happen when placing implants in extremely atrophic mandibles. Recommended at least 6 mm in vertical height and width required for implant placement. If there is not enough bone stock, then a bone graft is indicated. Treatment follows basic trauma principles. Treatment of the edentulous mandible may require a large reconstruction plate with consideration for bone grafting.

Excessive Countersinking

May cause excessive bone loss and difficulty with connections. May also result in loss of primary stability.

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 including P. gingivalis, P. intermedia, and Aggregatibacter actinomycetemcomitans. Symptoms include bleeding on probing, bone destruction, suppuration on probing, erythema, hyperplasia, probing depth >5 mm, mobility of implant, and swelling. Pain is normally only present in the setting of acute infection.

Adequate soft tissue management (plan to increase or maintain thick keratinized tissue around neck of implant) can reduce the chance for periimplantitis.

Treatments
  1. 1.

    Local debridement – exposure and cleaning with instrument softer than titanium. Consider rubber cup polisher with paste, plastic scalers, abrasive air powder treatment, and interdental brushes.

     
  2. 2.

    Decontamination – 40% citric acid with a pH of 1 for 60 seconds, chlorhexidine, tetracycline (50 mg/ml saline for 2 minutes), or application of local antibiotics (e.g.,tetracycline granules), Er:YAG or CO2 laser or 3% H2O2.

     
  3. 3.

    Surgical – open flap combination of debridement and decontamination with allograft/autograft with membrane.

     
  4. 4.

    Removal of implant.

     
Sublingual Gland Injury/Sublingual Artery

Palpate ridge or CBCT to visualize the sublingual fossa. Injury can be caused by perforation through the lingual cortical plate. Ranula or bleed can occur. Evaluate floor of mouth and be mindful of the airway. Sublingual artery bleed can be managed by exploration with cautery/ligation (Consider treatment in the hospital setting for airway protection). If ranula develops, consider removal of sublingual gland.

Bone Augmentation

Bone Grafting
  • Heals by 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.

  • Osteogenic – transfer of osteocompetent cells for de novo bone formation, e.g., autografts.

  • Osteoinduction – bone formation by stimulation of host mesenchymal cells to differentiate, e.g., allograft, bone morphogenic protein.

  • Osteoconduction – providing scaffolding for new bone formation propagated by native bone. Does not contain proteins or cells, e.g., xenograft.

Bone Graft Materials
Autogenous – composed of tissue from the same person

  • Osteogenic, osteoinductive, and osteoconductive.

  • Gold standard.

  • Disadvantage is a second surgical site.

Allogeneic grafts taken from another individual of the same species but different genotype

  • Osteoinductive and osteoconductive.

  • Strict screening for infections, malignant neoplasm, degenerative bone disease, hepatitis B or C, STDs, autoimmune disease, or other diseases that may affect bone quality.

  • Comes as a mineralized freeze-dried bone allograft (FDBA) or demineralized freeze-dried bone allograft (DFDBA). Both provide type 1 collagen which is the exclusive organic component of bone.

  • Methods to decrease antigenicity – freeze-drying, irradiating, dry heating.

Xenograft – grafts taken from another species

  • Osteoconductive.

  • No organic component.

  • Treated by sintering at 900 °C or high alkaline solution. Risk of prion transmission (e.g., bovine spongiform encephalopathy) is theoretical.

  • Hydroxyapatite crystalline structure allows for ingrowth of vessels and migration of osteogenic cells.

Recombinant Human-Bone Morphogenetic Protein-2 (BMP)
  • Part of transforming growth factor β superfamily.

  • Recombinant DNA technology in Chinese ovarian hamster cells allows for transcription and collection of non-contaminated protein.

  • Water soluble, requiring a collagen type 1 carrier (acellular collagen sponge) for slow release. Requires 15 minutes of absorption.

  • Concentration of 1.5 mg/cc mixed with sterile water (do not substitute with normal saline as too hypertonic).

  • Chemotactic for preosteoblasts and stem cells as well induces expression of VEGF by osteoblasts.

  • Only on label use is currently for sinus augmentation or alveolar ridge reconstruction.

  • Will have extensive edema due to influx of fluid and cells from the chemotactic and neovascularization activities of BMP.

  • Allow healing of 6 months prior to implant placement.

  • Contraindications: (1) pregnancy, (2) allergy to rhBMP or type I bovine collagen, (3) active infection at recipient site, (4) active or history of malignancy at site, and (5) skeletal immaturity.

  • Postoperative steroids and icing of tissue may reduce the intensity of swelling.

Platelet-Rich Plasma (PRP)

  • Platelet-derived growth factors act as a mitogen (encourages cell division) and encourage osteoid production and endothelial cell replication.

  • PRP is a blood clot that is highly concentrated with platelets, about 1 million platelets/μL.

  • Alpha granules in platelets secrete the growth factors that bind to transmembrane receptors to induce its effect, initiating a faster initial cellular response.

  • Collection tube contains citrate dextrose as anticoagulant, which works by binding to calcium.

  • The platelets are spun down either in two spins (separation spin followed with a concentration spin) or some manufacturers offer single spin units.

  • Activated via the addition of CaCl2 and thrombin.

  • Utilized in soft and hard tissue grafting.

Platelet-Rich Fibrin (PRF)

  • Platelet-rich fibrin (PRF) was developed as an improved formulation of the previously utilized platelet-rich plasma (PRP), to serve as a three-dimensional scaffold to biologically enhance healing.

  • This new approach is based on the concepts that were introduced over a decade ago consisting of a platelet concentrate without the use of anticoagulants.

  • PRF is obtained simply by centrifugation without anticoagulants and is therefore strictly autologous.

  • This fibrin matrix contains platelets and leukocytes as well as a variety of growth factors and cytokines including transforming growth factor-beta1 (TGF-β1), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), interleukin (IL)-1β, IL-4, and IL-6.

  • These factors act directly on promoting the proliferation and differentiation of osteoblasts, endothelial cells, chondrocytes, and various sources of fibroblasts.

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Jul 23, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Implantology
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