Dental Implantology PDF

1 Dental Implantology Rationale for Dental Implants Definition - A prosthetic device or alloplastic material implanted into the oral tissues beneath the mucosal or/and periosteal layer, and/or within the bone to provide retention and support for a fixed or removable prosthesi...

1 Dental Implantology Rationale for Dental Implants Definition - A prosthetic device or alloplastic material implanted into the oral tissues beneath the mucosal or/and periosteal layer, and/or within the bone to provide retention and support for a fixed or removable prosthesis. Advantages of Implant - Supported Prostheses - Maintain bone volume and density. - Restore and maintain occlusal vertical dimension. - Maintain facial esthetics (muscle tone). - Improve esthetics (teeth positioned for appearance versus decreasing denture movement). - Improve phonetics and occlusion. - Improve/regain oral proprioception (occlusal awareness). - Increase success and survival times of prostheses. - Improve masticatory performance/maintain muscles of mastication and facial expression. - Reduce size of prosthesis (eliminate palate, flanges). - No need to alter adjacent teeth. - Improve psychological and overall health. Indications to Dental Implant Placement - Patients who cannot be treated using other techniques (compromised retention of denture, defects of the jaw). - Patients who benefit from dental implants compared to the conventional therapy (edentulous, shortened arch, single crowns, orthodontic retention). - Patients who have comparable functional outcome using dental implants or a conventional therapy. In these cases subjective personal or esthetic reasons may justify the implant therapy.  2 Contraindications to Dental Implant Placement - Patients with compromised healing capacity (Uncontrolled diabetes, History of osteomyelitis in operative site). - Debilitating or transmittable infection (Hepatitis, HIV). - Pregnancy. - Chronic, severe alcoholism. - Terminally ill patients. - Young patients (not recommended prior to completion of growth as the implants may end up in infraocclusion. It is widely recommended to wait until the patient is at least 17 to 18 years old). Relative Contraindications to Dental Implant Placement (Depends on severity of conditions) - Malignancies with ongoing chemotherapy. - Head and neck radiation treatment (result in endarteritis with impaired bone- healing). - Chemical dependency. - Recent heart transplant or artificial heart valve. - Smoking (systemic vasoconstriction, reduced blood flow and increased platelet aggregation. These effects contribute to reasons why dental implants have approximately twice the failure rate in smokers compared to non-smokers.) Terminology in Implant Dentistry Osseointegration - Brånemark and co-workers coined the term “osseointegration” in 1967 Characterized as direct structural, biological and functional connection between newly formed bone and the implant surface. (Histological not clinical term describes the attachment of bone to the implant surface) Factors that influence osseointegration: - Biocompatible dental implant material. - Implant adapted to prepared osteotomy site. - Atraumatic surgery. - Undisturbed healing phase.  3 Criteria for Implant success: 1. The unattached implant exhibits no clinical mobility. 2. Radiography demonstrates no evidence of radiolucency between implant and bone. 3. Marginal bone loss is less than 0.2 mm annually after the first year of service. 4. Absence of persistent pain, discomfort, or infection. TYPES OF DENTAL IMPLANTS - Based on the site of implantation, there are three main types of dental implants eposteal, transosteal, and endosseous. Eposteal implants - Receive their primary support from contact against the remaining bone of the jaw (not considered to be osseointegrated implants, they gain support by resting on the residual bony ridge). - Less favorable result so not currently considered as the first option for treatment of the edentulous arch. I- Subperiosteal implants - Custom frame is placed subperiosteally with several projections through the mucosa for attachment of the prosthesis. Fixed or removable prostheses can then be connected to these transmucosal posts. - Used for treatment of the edentulous mandible and maxilla. - The best results for treatment of the edentulous mandible because of the greater bone density and resulting capacity to support the load of the prosthesis. II- Ramus frame implant - One piece implant, used in the mandible only, with right and left posterior extensions that are surgically placed into the corresponding right and left ascending rami, and an anterior foot, which is surgically placed in the bone of the symphysis.  4 Transosteal implant - Pass through the jaw and have been known by the terms staple implant and transmandibular implant. - A design in which posts are inserted through the mandible in an inferior superior direction to fixate a metal framework on which the prosthesis is attached. - A successful clinical solution to prosthetic rehabilitation of patients with severe mandibular atrophy. Endosseous Implants - Designed for placement into the alveolar or basal bone of the mandible or maxilla while maintaining the body of the implant within the bone. - There are two basic types of endosseous implants blade and root form - Although the blade design has fallen out of use, the root form implant (cylinder and screw-shaped versions) continue to be the most widely placed implant designs in use today Blade Implants - Endosseous implants with a flat shape and are available in one-piece and two-piece designs. -Find usage in the narrow bony ridge as an option for horizontal bone grafting. Cylinder (press-fit) Implants - Endosseous design consisting of a straight cylinder that is pushed or tapped into the surgical osteotomy. - Primary stability of these designs relies on a highly roughened surface texture (hydroxyapatite, titanium plasma spray) to increase frictional resistance to dislodgement from the bone. - These implants are used infrequently today because the highly roughened surfaces are associated with increased risk of peri-implant complications.  5 Screw-Shaped Implants - The implant body exhibits screw threads throughout most or all its length. - The most commonly used implant design. - Current designs feature improved primary stability and simplified surgical placement protocols. IMPLANT MATERIALS, SURFACES, AND FORMS The composition and nature of the surface on an implant are important characteristics because of their effect on the biologic development of an interfacial relationship between the bone and the implant. To be successful, an implant must meet four conditions: 1) Be biocompatible so there is no undesirable reaction between the tissues and the implant (ie. corrosion, dissolution and/or resorption). 2) Have an interface that stabilizes postoperatively in as short a time as possible. 3) Be capable of carrying and transferring the occlusal stresses that are placed upon it. 4) Remain stable for a long period of time. IMPLANT MATERIALS Two basic types of materials are used in implant dentistry: metals and ceramics, either in a pure form or a hybrid type. Titanium Implants - Titanium’s biocompatibility, corrosion resistance, relatively light weight, low density, low modulus and high tensile strength make titanium based materials attractive for use in dentistry. - After the machining of a titanium or titanium alloy implant, contact with air causes the immediate development of a titanium oxide surface on the implant. Ceramic Implants - High strength ceramics, based on aluminum or zirconium oxides, have been used for load-bearing implants. However, because ceramic materials are brittle and susceptible to fracture, they are not ideally suited for use as implants, and their use was primarily for the replacement of single teeth. - Ceramic materials are relatively inert, excellent biocompatibility and fully oxidized materials and therefore chemically stable.  6 IMPLANT SURFACES - Implant microstructure refers to the surface structure, or degree of surface roughness, of the dental implant. This is critical for adhesion and differentiation of cells during the bone remodeling process. - The modifications of microtopography contribute to an increase in surface area and increased levels of bone implant contact. Modifications can be divided into: - Subtractive and additive processes, depending on whether material is removed or deposited on the implant surface in the development of the surface. I. Subtractive processes 1. Etching with acid 2. Blasting with an abrasive material, such as silicon or HA; blasting with HA, known as resorbable blast media (RBM), is particularly advantageous because, unlike with grit or sandblasting, any particles remaining on the surface are resorbable. 3. Treatment with lasers II. Additive processes 1. HA coating 2. TPS (Titanium plasma spray) 3. Anodization to thicken the titanium oxide surface IMPLANT COMPONENTS Dental implant body - This term describes the anchorage Component that is designed to be placed into holes drilled in the bone, which is sometimes also referred to as an implant, fixture or implant fixture. Cover screw - Sometimes called a healing screw, is a component used to occlude the connection of the implant while submerged during a two-stage procedure. Healing abutment - A component that connects to the dental implant and protrudes through the soft tissue. It can be connected to the implant at the second-stage surgical procedure, or it can be inserted at the time of implant placement to eliminate the need for a second surgery. This component has also been referred to as a healing collar or permucosal abutment.  7 - Healing abutments are typically provided as stock components with a cylindrical shape, but they also can be customized for the specific case to provide an ideal soft tissue cuff around implant. Laboratory analogue - A base metal replica of the implant body Impression coping - This is also described as a dental implant impression cap, and is used to transfer the position of the implant body or the abutment to the working cast. Implant Restorations Implant Abutment Definition: The portion of the implant that supports or retains a prosthesis or implant superstructure. Superstructure Definition: Metal framework that attaches to the implant abutment(s) and provides either retention for a removable prosthesis (as bar attachment) or the framework for a fixed prosthesis.  8 Classification of implant abutment 1- Abutment for screw retention: use screw to retain the superstructure. 2- Abutment for cement retention: the cement is used to retain the prosthesis to the abutment. May be one piece or two pieced 3- Abutment for attachment: attachment used to retain the removable prosthesis. Each category can be divided into many types according to: - Material of construction (titanium, zirconium, Co-Cr) - The shape of abutment (straight or angled) - The technique of manufacturing (readymade or custom made) Healing caps - Temporary polymeric covers for abutments to prevent damage and fouling of the screw retainer when the patient has to be without the superstructure during its fabrication or repair. Diagnosis and Treatment planning Diagnosis for dental implants Meticulous initial evaluation is critical to successful treatment. Diagnosis includes systemic evaluation and dental evaluation Objectives: 1- Evaluation of the conditions of the oral tissues. 2- Assessment of the patient’s general health. 3- Evaluation of the patient’s psychology and mental conditions. Medical evaluation - Implant dentistry is an elective procedure and therefore should not usually be performed on patients with severe systemic disease (ASA Status IV patient).  9 - The ASA physical status classification serves as an excellent means of identifying patients that are not well suited for implants because of their systemic status. ASA Physical Status Classification Status Description Activity Limitation Dental treatment Limitations I Normal, healthy patient None 1. None, except possible stress reduction II Mild to moderate None 1. Possible stress reduction Systemic disease 2. Disease specific modifications III Moderate to severe Systemic Some limitation due to 1. Possible stress reduction disease disease, but disease 2. Disease specific modifications is not incapacitating 3. Medical consultation advised IV Severe systemic disease that Incapacitating disease 1. Emergency treatment only under most is a constant threat to life that limits activity circumstances 2. Possible stress reduction 3. Disease specific modifications 4. Medical consultation required V Moribund patient not expected to survive 24 hours with or without surgery - There are specific systemic diseases and conditions that affect bone metabolism, wound healing, and the success of implant therapy. Such as Osteoporosis - Implant designs that assure a stable bone implant interface at insertion should be selected to overcome the inability of less dense osteoporotic bone to stabilize the implant. Self-tapping threaded implants without cortical countersink procedures - Implant designs should be greater in width, and surface conditions of implant bodies should be designed to increase bone contact and density. - The healing period should be extended by 2 months before the placement of the prosthesis: 8 months versus 6 months in the maxilla, and 6 months versus 4 months in the mandible. - Physiologic doses of vitamin D (from 400 to 800 IU/day) & calcium (1500 mg/day) Recommended during the postoperative period. Smoking The failure rate is reported to be 2–2.5 times higher in smokers - Alter wound healing by decreasing proliferation of fibroblasts - Decreases tissue oxygenation - Decreasing tissue perfusion through vasoconstriction - Decreases osteoblast activity, resulting in diminished bone mineral density and delayed bone healing after surgery.  11 Dental evaluation Oral Hygiene - An evaluation of the patient’s existing oral hygiene is essential; the patient should possess both the desire to maintain oral health. Mucosal Characteristics - An evaluation of the quality and quantity of keratinized tissue should be completed. If insufficient attached tissue is present, tissue augmentation procedures should be completed before implant placement. - Attached mucosa around dental implant is preferable; the absence of keratinized mucosa also increases the susceptibility of peri-implant regions to plaque-induced inflammation. - Too thick mucosa may need to be surgically thinned to develop sufficient interarch space, allow for development of appropriate esthetics in the prosthesis, or provide access for oral hygiene procedures. Arch Position - The maximum biting force is greater in the molar region and decreases as measurements progress anteriorly so the larger implant diameter is especially considered in the molar region. - The denser the bone, the greater its resistance to stress applied at the implant–bone interface. As a result the posterior maxilla is the most at-risk arch position, followed by the posterior mandible, and then the anterior maxilla. - The most ideal region is the mandibular anterior. Ridge form - Flat ridge or ridge with undercuts, irregularities, or bony defects may cause difficulties during implant insertion. - Concavities on the lingual aspect of the mandible may lead to perforations while drilling. Trauma to either of these significant sublingual vessels could result in postoperative bleeding, swelling and in some cases life- threatening situations.  11 - Measurements performed on a CAT scan will delineate the ridge’s anatomic volume and contours that are favorable for implant placement. CAT scan of thin ridge CAT scan of undercut ridge Arch relationship This is either normal which indicates a favorable prognosis, or there may be maxillary or mandibular protrusion which lessens the chance of success. Inter-maxillary space - A small space between maxillary and mandibular arch may cause some difficulty during the prosthetic phase of treatment. - Case failure can occur if there is undiagnosed limited interarch space Smile Line With fixed complete dentures, patients may smile in a manner that the border of the prosthesis would be visible, producing an undesirable esthetic result and necessitating the use of an implant overdenture. Parafunctional habits - using the progressive bone-loading technique, poorer bone density may be transformed into better quality bone, which is more ideal for adapting to excessive occlusal loads. - The use of wider-diameter implants or an additional number of implants. - Use of an occlusal guard. Tongue Size/Position - Patients with tongue thrust or larger tongue complains of inadequate room for the tongue and may bite it during function so a fixed restoration is more advantageous for this type of patients.  12 Bone Quantity - The occluso-cervical height of the residual ridge should be at least 7 mm, since that is the shortest available implant length. It should also be remembered that short implants (7-10 mm) have a higher failure rate. - The faciolingual ridge thickness should have a minimal dimension of 6-8 mm so the implants can be housed within bone. These minimal dimensions make the implant placement very critical to avoid fenestration/dehiscence of the implant. - Minimal faciolingual dimensions do not permit changing the implant angulation in the bone. Bone Quality The density of the bone (as determined radiographically) is an important factor to evaluate; Bone quality and volume are of key importance in implant success. Bone density classification D1…...... bone is primarily dense cortical bone (anterior mandible). D2 ……… bone has dense to thick porous cortical bone on the crest and coarse trabecular bone underneath (anterior maxilla). D3 ……… bone has a thinner porous cortical crest and fine trabecular bone within (posterior mandible). D4………. bone has almost no crestal cortical bone. The fine trabecular bone composes almost all of the total volume of bone (posterior maxilla). Importance of bone density classification  D4 associated with high implant loss (the percent of implant loss in Type D4 bone was much higher than the loss in Types D1- D3 bone)  D1 difficult surgical preparation  Determination of treatment planning (decrease Bone density = increase Implant area)  Indication of implant survival  13 BASIC RADIOGRAPHIC EVALUATION Objectives of Preprosthetic Imaging Identify normal versus abnormal anatomy. Identify anatomic variants. Determine bone quality and quantity Identify ideal implant positioning. Use for surgical templates. Types of Imaging Modalities Periapical Panoramic Computed tomography Cone beam CT Periapical Radiography Indications/Use(s)/Advantages - Should be limited to an initial evaluation of a proposed implant site, intraoperative evaluation, and postoperative assessment. - A useful modality for ruling out local bone or dental disease. Limitations - Providing only a 2D image of a 3D object. - Inability to determine the buccal-lingual bony dimensions. - Little value in determining quantity and quality of bone and identifying vital structures. Panoramic Radiography Indications/Use(s) - Initial evaluation of bone dimensions and in screening for the detection of pathologic conditions when planning for dental implants Limitations - A lower resolution prevents evaluation of the fine detail that is required for the assessment of osseous structures and anatomy. -Magnification of up to 25% which results in a linear measurement error of up to 3.0 mm. - The image has superimposition of real, double, and ghost images, which result in difficulty in visualizing anatomic and pathologic details.  14 Computed Tomography Indications/Use(s)/Advantages - It is widely advocated for use in assessing potential implant sites and planning for complex treatments. - The recommended slice thickness for implant analysis is 1.5 to 2 millimeters. - The reported CT scan error is between 0.5 to 2 millimeters. - used to provide an indication of bone quality. - Special software is available that creates 3-D images. - The information can be analyzed in a computer, implant design/placement can be simulated, and measurements can be made of the forces/moments that will occur with proposed designs. Limitations - There is a greater cost. - There is greater radiation exposure for a CT than for other imaging techniques. Cone Beam Computed Tomography (CBCT) The gold standard for dental implant treatment planning Indications/Use(s)/Advantages - In-office installation and use. - Low radiation dose - The scanning speed (4 months after tooth extraction  17 Immediate Placement after Extraction versus Placement in Healed Sites - The standard protocol dictated that after tooth extraction the site should be allowed to heal before implant placement. - Immediate placement at the time of extraction requires no evidence of periapical infection and sufficient bone about 2-4 mm is recommended apical to the extraction site that will permit primary implant stability. Advantages of immediate implant Placement Decreased treatment time and cost Decreased need for bone augmentation Preservation of the soft tissue drape Improved implant positioning High patient satisfaction Disadvantages of immediate implant Placement Site morphology Surgical technique is more complicated Anatomic limitations Lack of primary closure Presence of acute/chronic pathology Consequences of implant failure Implant Restorations The restoration of dental implants consists of the procedures needed for the connection of prosthesis to one or more implants. Loading Protocols 1. Conventional loading: Restoration occurs after the initial bone and soft tissue healing process, usually in 3 to 6 months, depending on bone density. 2. Immediate loading: Prosthesis is connected at the time of implant placement. This is usually a provisional restoration that is replaced with a definitive restoration after implant and soft tissue healing. 3. Early loading: The prosthesis connection occurs from 2 to 3 weeks after implant placement. A less predictable loading protocol because the restoration is sometimes placed during the stability dip, which is the period of lowest implant stability. 4. Delayed loading: The prosthesis is connected 6 to 12 months after implant placement. This method is often chosen in poor quality bone and in situations in which primary stability cannot be achieved during surgical placement.  18 Dental Implant Surgery Surgical Protocols Three different surgical protocols have been used for two-piece implant systems: one stage, two stage, and immediate restoration. Two-stage protocol (standard) The implant body, with a cover screw, is submerged below the soft tissue until the initial bone healing has occurred. During a second-stage surgery, the soft tissues are reflected to attach a component that passes from the implant connection, through the soft tissue, and enters the oral cavity. One-stage surgical Protocol The surgeon places the implant body and a temporary healing abutment, which emerges through the soft tissue. During the restorative process, the healing abutment is replaced so that the prosthetic abutment or restoration can be connected, eliminating the need for a second surgery. Immediate restoration protocol The implant body and a prosthetic abutment are both placed at the initial surgery. A provisional restoration is then attached to the abutment. Surgical technique of fixture installation Operating conditions - The preferred environment for dental implant surgery is a sterile hospital-type operating room significantly improves the success rate of dental implants. Surgical Instrumentation - Implant systems include a surgical instrumentation kit with drills, drivers, wrenches, screw taps, and implant mounts designed for the surgical protocol for that specific implant system. Implant Drills - Implant drills are rotary cutting instruments that are used to create an osteotomy in bone. They are made of various materials, including surgical stainless steel, titanium alloy, and ceramics.  19 - When used in the proper sequence with the recommended rotary speed, torque, and irrigation, the drills are designed to create the correct size and shape of the osteotomy, providing initial stability without causing mechanical or thermal damage to the bone. Drivers - Various screws drivers are used in the course of implant treatment are engaged with hexed, slotted, or unigrip drivers (depending on the manufacturer) Implant Mounts - Some systems require an implant mount to be attached to the implant to facilitate the delivery of a dental implant to the surgical site, and it can be used to rotate the implant to the correct depth. The implant mount is then removed from the implant to obtain visual confirmation of the position. - Other implant systems incorporate a direct-drive feature, in which an instrument engages directly into the implant, allowing for a simpler procedure and better vision during implant placement. Wrenches - A ratchet wrench or torque wrench is used to place the implant. - It is a manual instrument used to apply a specific amount of torque when placing an implant or prosthetic screw (Possible 15/25/35N tool adjustment). Surgical Procedure Incision design - The mucosa and periosteum are incised to the full thickness at the crest of the edentulous ridge and the flaps are usually fully elevated and displaced to expose the area where the implants will be placed. - Incisions for single implants are sometimes made so they do not include the interdental papillae. They may also be reflected from a location remote to the crest of the ridge when bone regenerating membrane procedures are used in conjunction with implant placement.  21 Osteotomy preparation - After flap reflection, it may be necessary to recontour the alveolar ridge crest (reduce the ridge height) to remove thin areas of bone so there is sufficient faciolingual thickness of the ridge, thereby permitting the implant to be contained within bone. - It may also be necessary to reduce the ridge height to provide sufficient interarch space for the prosthesis. - Osteotomies into which implants will be placed are prepared following the surgical template’s planned implant positions. Prior to use, the template is immersed in a new solution of 3% glutaraldehyde for 12 hours and then thoroughly rinsed. - In preparing dental implant osteotomies, the surgeon uses a surgical unit with a contra-angle and handpiece that produces an 18:1 gear reduction and 1500 revolutions per minute. - Three drills are usually required to initiate site preparation (pilot, guide, and depth drills) for most implant systems. Each drill is marked to identify various depths to which the sites can be prepared. After the site is prepared to the desired depth and diameter, a countersink drill is used. Preparation of Implant Recipient Site - The first bur used to prepare the bone is the round guide bur. - Drilling of the bone is performed with constant irrigation of saline solution, while the bur must move in an up-down direction, so that the saline solution may reach the depth of the implant recipient site. - A spiral bur with a diameter of 2mm is then used to prepare the implant recipient sites. There are markings on the surface of the bur indicating suitable preparation depths for the various implant recipient sites.  21 - Widening the implant recipient sites is achieved using a longer twist bur, also with a diameter of 3 mm. The entire length of the recipient sites is widened with this bur. - A marginal countersink with a conical shape can often be used to prepare the shelf for installation of the implant THREAD FORMATION - Threads are created in the bone of the osteotomy walls using a bone tap in a contra-angle handpiece capable of producing a 200:1 gear reduction and 40-50 rpm’s. At this reduced speed and with higher torque, the surgeon creates the bone threads necessary to insure primary stabilization of the dental implant. - Self-threading (self-tapping) implants can also be used. They are placed in situations where softer, poorer quality bone is present, such as the maxilla. After the appropriate depth and diameter are established, they are placed directly into the bone without prior thread formations. - The drills for the osteotomy preparations can be used with internal or external irrigation for cooling the prepared bone. Irrigation must always be used while preparing a site for a dental implant to control the heat generated (keeping the temperature below 47c and preserve bone vitality) To minimize thermal injury to bone 1- Intermittent drilling technique 2- Copious irrigation (internal or external) to prevent a rise in the temperature of the drill bits, which then overheats the bone and Continually wash away bone chips and keep the drill bits clear of debris. 3- Fresh, sharp drills. 4- Controlled cutting speeds.  22 IMPLANT PLACEMENT - The implant is removed from the sterile package (without touching the implant). - When the implant is placed into the osteotomy by hand, it is rotated until resistance to advance is noted. If the implant does not completely seat using hand pressure and more force is required, a hand ratchet and ratchet adapter can be attached to the insertion assembly and the implant placed to its final depth. - Alternately, the implant can be placed to its final depth using a handpiece adapter located in the surgical kit. The plastic carrier is removed and the insertion assembly attached to the handpiece adapter. The implant can be inserted using the handpiece at 35-50 rpm drill speed and a torque limit of up to 40 N cm, depending on bone density. - Initial stability of the implant, immediately after placement, is always confirmed. Neither mobility nor rotation of the implant should be present. Removal of Insertion Assembly and Placement of Cover (Healing) Screw - After implant placement is complete, the handpiece is disconnected from the insertion assembly. The insertion assembly screw is unscrewed and removed, and the insertion assembly is detached from the implant revealing the top of the implant. - The healing screw is removed from the packaging and threaded into the top of the implant to cover and seal the open internal portion of the implant during bone healing. Suturing - Various techniques are used during closure and suture of the tissue flaps. The most common suturing techniques are vertical mattress and single interrupted ties.  23 Posto-perative management - A post-operative radiographic evaluation should be taken at this time to confirm implant placement and proper seating of the healing screw. Time Guidelines for Patient Follow-up Appointment The most common periods for patient follow up after implant surgery can be outlined as follows: - Suture removal 10 days after surgery. - Placement of a provisional soft liner (3 mm thick) if a denture will be worn by the patient to optimize the cushioning and minimize the chances of adverse pressure being applied to the implants. - Post-operative evaluation of soft tissue health and confirmations of no loading of implants 3 weeks after suture removal and every month after surgery for the entire healing period. - The post-operative bone healing time depends on several factors including quantity and quality of bone, implant stability, health of the patient, and the clinical judgment and experience of the surgeon. A general guide for healing time is: Type I bone (3 to 4 months) Type II bone (4 to 5 months) Type III bone (5 to 6 months) Type IV bone (6 to 8 months) Second stage (Uncover) surgery - Second-stage surgery is required if a two-stage technique is being employed. This involves exposure of the head of the implant body and the placement of a connecting component, either a healing abutment (facilitate gingival healing, allow easy access to the implants following healing) or more permanent transmucosal abutment that connects the head of the implant through the mucosal tissue. Location and Exposure of Implants - Where the implant is relatively superficial it can usually be located by palpation, and possibly probing and then exposed with a local incision or surgical punch (punch avoiding the need to strip periosteum but not indicated where only a narrow band of keratinized tissue exists) - Where the implant lies deeper, and is perhaps covered with bone, Implants can identify first on a radiograph and then a probe is used to locate the domed cover screw  24 below, Reuse of the surgical stent might help in their location. it is necessary to raise a full flap, depending on the position of the implant in the arch, while trying to keep the edges within keratinized tissue. - In general, incisions are made directly over the implant head unless the surgeon wishes to relocate some of the available keratinized tissue. The use of relieving incisions should be avoided if possible and, if necessary, placed remote from the edges of the abutments, as wound breakdown may occur if the flap margins are not on sound tissue. - Once the flap has been raised, the cover screw on top of the implant is removed. It may be necessary to remove excess bone from the head of the cover screw before this can be done, using purposed-designed mills or burs and taking care not to damage the implant. - An appropriate healing abutment is then removed from its sterile pack and secured on the implant. The healing abutment length should be chosen so that it just emerges through the soft tissue and does not require too much modification of the provisional prosthesis. - The flap is then repositioned and sutured. Rotational flaps can be used to try to reconstruct some of the lost papillae. This technique may enhance the amount of interdental tissue, especially between implant and natural teeth. - After two weeks of soft tissue maturation, healing abutments are removed to reveal a healthy peri-implant cuff, that should demonstrate tone and be absent of frank bleeding. - The permanent transmucosal abutment locates the internal hexagon of the fixture and is secured to it by means of an abutment screw, which passes through the center of the hollow abutment. Then after placement of the abutments, the patient is ready to begin the procedure for a fixed or mobile prosthetic restoration.  25 Dental Implant Complications - Potential complications may be minor or major, reversible or irreversible in nature and may be result from placing implants in compromised sites using more aggressive protocols. Implant failure - May be early failures before osseointegration, primarily the result of surgical and/or postoperative complications (6–8 weeks) or late failures after the osseointegration period, usually arising during and after the restorative phase. - May be caused by infection, Tissue trauma (e.g. overheating of bone, pressure necrosis), Overload (e.g. transmucosal loading, occlusal trauma), or Iatrogenic. Malposed or non-restorable implants Avoidance of malposition: Comprehensive assessment and diagnosis. Prosthetic driven treatment planning. CBCT scans, radiographic surgical guides. Plan ridge augmentation as needed. Implants causing permanent damage to vital structures Damage to adjacent anatomic structures may include perforation of the maxillary sinus, nasal cavity, and mandibular canal by the implant. Implant fractures - Usually involves the abutment screw or the implant itself (Uncommon occurrence) - Small-diameter implants have a high stress transfer to the bone, perhaps increasing the risk of fracture. - Minimize torsion to the implant– driver interface, which could potentially distort the platform connection. Implant placement in type IV bone should be preceded by tapping the bone instead of relying on the implant to tap the osteotomy. Esthetic implant failures - Aesthetic problems usually arise from incorrect implant placement apico- coronally, facio-lingualiy, or mesio-distally.  26 Dental Implant Maintenance - The maintenance of healthy peri-implant tissues contributes to implant success and minimizes peri-implant disease. In addition, tissues free of inflammation and a biofilm-controlled implant sulcus will support the patient’s general and oral health. - Implants and associated prostheses are much different from natural teeth and may require adjunctive procedures and instruments for professional and patient care. Peri-implant Diseases - Defined by changes in the level of crestal bone, presence of bleeding on probing, and/or suppuration; with or without deepening of the peri-implant pockets - peri-implant infections are always caused by plaque and its by-products (i.e., biofilm). Two conditions of peri-implant disease are: 1- peri-implant mucositis - An inflammatory condition of the soft tissue surrounding an implant, which is similar to gingivitis around natural teeth. - A reversible condition with no loss of attachment or bone loss. However may progress to peri-implantitis if not treated. - Clinically, erythematous gingiva with bleeding on peri-implant probing. Etiology Poor Oral Hygiene Poor Compliance with Supportive Procedures Poor Prosthesis Design Poor Fit of Prosthesis Non-ideal Implant Position Lack of Non-Keratinized Peri-Implant Mucosa Retained Cement Prevention - A comprehensive medical history should be evaluated for any risk factors (poor oral hygiene, history of periodontal disease, Diabetes Mellitus, smoking) and the patient should be informed of possible associated complications. Management - Nonsurgical (closed debridement) mechanical debridement to remove plaque and calculus from the implant surface using mechanical instruments such as scalers and curettes coupled with antimicrobial rinse therapies (chlorhexidine 0.12% or 0.2%).  27 - Various types of curettes (Titanium-coated, Carbon-fiber, Teflon, and Plastic) are available for debridement procedures to minimize surface changes after treatment. - Stainless-steel curettes are much harder than titanium alloy and are not recommended for use around dental implants because they may alter the implant surface. 2- Peri-implantitis - An inflammatory reaction with loss of supporting bone around an implant, exhibit similar microbial flora as chronic periodontitis. Clinical symptoms Vertical bone greater than 2 mm (radiographic, probing, or both) Peri-Implant pockets (exceeding 3–4 mm) Bleeding on probing Exudate Mucosal swelling Erythema Usually no associated pain Etiology stress factors caused by poor biomechanical forces. Poor implant placement Poor oral hygiene Residual cement Poor implant surface Unfavorable osseous density. Untreated periodontitis. Host response, Alcohol excess, smoking, diabetes. Prophylactic procedures - An effective oral hygiene program is paramount to minimize peri-implant disease. - Patients with periodontitis must have this pathologic condition controlled before implant placement. - Ideal implant position is paramount to allow for a properly designed prosthesis that is cleansable. - Use a screw retained prostheses. If a cementable prosthesis is utilized, the clinician must take precautions to prevent residual cement. - An occlusal guard is crucial in preventing unfavorable occlusal stress.  28 Management - The objective of treatment is osseous regeneration of the implant-bone defect. - This may involve nonsurgical and surgical treatment. Cumulative interceptive supportive therapy  Mechanical débridement (supportive therapy protocol A) - Oral implants with evident plaque or calculus deposits adjacent to only slightly inflamed peri-implant tissues but lacking suppuration and having a probing depth not exceeding 3–4 mm - Calculus may be chipped off using carbon-fiber curettes - Plaque is removed by means of polishing using rubber cups and polishing paste  Antiseptic treatment (supportive therapy protocol B) - Probing depth is increased to 4–6 mm. Suppuration may or may not be present. - Performed in conjunction with the mechanical treatment (protocol A). - Comprises the application of the most potent antiseptic available (chlorhexidine) either in the form of a daily rinse of 0.12%, or 0.2%, or as a gel applied to the site of desired action. - 3–4 weeks of regular administration are necessary to achieve positive treatment results.  Antibiotic treatment (supportive therapy protocol C) - pocket increase to 6 mm or more - The mechanical (A) and the antiseptic (B) treatment protocols have to be applied. - An antibiotic directed at the elimination of Gram negative anaerobic bacteria, Systemic: metronidazole (500 mg, 3 times/daily for 8 days) is administered Local: Tetracycline, Doxycycline or Minocycline  Regenerative therapy (supportive therapy protocol D) - Only if infection is controlled successfully, as evidenced by an absence of suppuration and reduced edema. - Restore the bony support of the implant by means of regenerative techniques (guided tissue and bone regeneration).