IMPLANTS IN OMFS
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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
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Topics –in seminar
Dental implants Implant retained prosthesis- Ear, Nose & Eye. Tmj implants Zygoma implants. Bone augmentation. (vertical)
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Dental implants- types
Endosseous – types, Root form, Blades, Ramus blade & Ramus frame.
ROOT FORMS- if sufficient bone height & width is available this is choice of implant. Types –Press fit, Self tapping, Pre tapping (threaded) . Prosthetic options- used in fixed, fixed detachable, over denture & single tooth purposes. Required bone- >8 mm vertical height >5.25 mm bone width (bucco-lingual) >6.5 mm bone length (mesio-distal) www.indiandentalacademy.com
Blades
These are submergible two-stage & single-stage one piece implants. Types- Prefabricated, Custom- cast, Alterable (by cutting, bending, Shaping on chair side) Prosthetic options- single & multiple tooth Required bone- >8mm vertical height >3.0 mm width >10 mm length. www.indiandentalacademy.com
Ramus blade & Ramus Frame
One piece blade –used for the post mandible when insufficient bone exists in the body. Ramus frame – Three blade, one piece deviece designed for relatively atrophied mandible. Prosthetic options – overdentures Required bone- >6mm verically >3mm width.
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Subperiosteal implants
Principally used in atropic mandilble. Cast metal frame which fits the jaw bone & has projections into the oral cavity on which a prosthesis may be mounted. Frame- usually made of cobalt chromium alloy. Disadvantage- the implant host interface is fibrous & oral epithelial down- growth eventually occurs around the implants. www.indiandentalacademy.com
Transosseous implants
One- piece implants. A submental incision is required. Advantage- implant predictable longevity. Types- single component, multiple component, staples. Prosthetic options- usually over dentures, alternative fixed bridges. Suitable arch- mandible-ant region, complete or partial edentulism. Bone required- >9mm verically www.indiandentalacademy.com >5mm width.
Implants parts ď Ź
Body, Apex, Module.
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Osseointegration
“A process where by clinically asymptomatic rigid fixation of alloplastic materials is achieved & maintained in bone during functional loading”. In 1809 Maggiolo-gold implant in fresh extracted socket-complicated by post op pain & gingival inflammation. A 2 staged threaded Ti root implant was first presented in North America by BRANEMARK in 1978. www.indiandentalacademy.com
Materials and Surfaces
First metals used were Gold, Silver, Lead which had electrolytic reactions when they bought in contact with body fluids. Recently used is Ti-6Al-4V alloy becoming the metal of choice. Exposed to air, 2-10 nm thick oxide layer is formed & is bioinert. HA – plasma sprayed onto a roughened & prepared Ti implant to enhance bone connection. www.indiandentalacademy.com
HA- ranges from 50 to 70 µ. A pressurized hydrothermal post plasma-spray increases the crystalline HA content from 77 to 96%offers improved bone adhesion. Despite the success of smooth Ti implants, use of roughened surface has been substituted as the current choice of texture. www.indiandentalacademy.com
Time & Reason –Integration & Failure
Branemark protocol states 4-6 months for mandible & 6 months for maxilla to prevent fibrous encapsulation . This is out dated because it is based on clinical observation & not on the biological factors. Recently -designed on the microtopograhic surface & histology. Cooper, Felton, I J OMFS implants,2001-96.2% survival rate of single staged implant in 3 weeks. www.indiandentalacademy.com
Failure
Endosseous implants distribute occlusal load best in Axial direction, but in lateral, many damaging stress, shear stresses were generated directly at the crest of bone. Over heating during placement- fibrous tissue against implant surface rather than bone . Lack of bone contact leading to lack of integration & marginal integration. Presence of infection. www.indiandentalacademy.com
Keratinized gingiva has shown to promote soft tissue health around teeth. Preserving Keratinized gingiva recommended when placing & exposing implants. Incision design should result in Keratinized gingiva labial to the implant. In post maxilla, vertical bone loss is due to excessive cantilever type forces placed on the implants. Improper oral hygiene. www.indiandentalacademy.com
Periimplant Biology ď Ź
The placement of an implant between two periodontally healthy teeth is a unique situation whereby the bone and soft tissue is maintained in part by the teeth.
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The suggested depth of placement of an implant below the free margin of soft tissue is approximately 3 to 4 mm.
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The distance suggested from the side of the implant to the adjacent tooth should be about 2 mm to avoid horizontal bone loss affecting the adjacent tooth.
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Crown to Implant ratio
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A crown-to-implant ratio of 1:1 or less is desired. The minimum length needed approaches 10 to 12 mm since the clinical crown length frequently approaches this measurement. Replacement of teeth in a compromised site gives rise to single or multiunit restorations that have poor or unfavorable crown-to-implant ratios. If the restoration participates in anterior guidance, it should be splinted to other implants. www.indiandentalacademy.com
Radiographic Classification ď Ź
Lekholm & Zarb correlated implant success with the radiographic appearance of the remaining cross- sectional bone by classifying the amount of remaining cortical to cacellous bone. Type 1- Greater than 75% cortical/cancellous bone Type 2- Thick corical surrounding dense cancellous bone Type 3- Thin cortical surrounding dense cancellous bone Type 4- Thin cortical surrounding low density cancellous bone. www.indiandentalacademy.com
Implant selection ď Ź
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Historically, osseointegrated dental implants were introduced in their original configuration as a machined parallel walled screw. In later years the use of surface-textured press-fit type implants also became popular because their surgical installation was simplistic and achieved earlier integration into softer types of bone. Current trends -use of tapered macroretentive implant configurations, based on the fact that tapered screw type implants have increased surgical stability in soft bone. www.indiandentalacademy.com
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This taper creates a seating effect of the connection to the internal aspects of the implant; therefore, fewer lateral stresses are transferred to the abutment screw, resulting in a less frequent incidence of screw loosening and fracture. Consideration of the components makes it easier to select the appropriate system for both surgical installation and restoration.
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One stage & immediate loading ď Ź
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Recently, more interest has arisen for placement of implants into the esthetic zone of the maxilla, with either immediate loading or the use of a healing abutment that mimics the natural shape of the tooth. The hypothesis is that by placing a healing abutment with natural contours, the soft tissue response will be enhanced, potentially resulting in a more esthetic final restoration. Treatment planning for a one-stage or immediately temporized anterior maxillary restoration begins with a list of contraindications.
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A one-stage exposed implant placement at the time of extraction will require the following: • No purulent drainage or exudate from the site • Excellent gingival tissue quality without excessive granulation tissue • Lack of periapical, uncontrolled radiolucency • Adequate bone levels circumferentially without the need for additional soft or hard tissue grafting
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Complications
Soft tissue complications: seen in areas where the quantity of keratinized soft tissue is minimal. Soft tissue may also be compromised in area were the implant angulation's is not ideal in an esthetic zone. Soft tissue depths exceeding 5 to 6 mm may present with long term maintenance.
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Radiographic Bone Loss : It is normally expected in implant placement; how ever this loss should not exceed 1.5mm in the first 12 to 18 months. Bone loss in excess of this value exposes a significant portion of the implant surface, making hygiene procedures difficult. Screw Loosening : Abutment and Prosthetic screw loosening can be a recurrent problem seen often with single tooth restorations. www.indiandentalacademy.com
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A method of reducing screw loosening is to use a new abutment or prosthetic screw, torque once to the recommended torque application, wait 5 min, and then torque again. Repeated screw should bring to mind occlusal over load, heavy contact in lateral excursions or implant mobility. Abutment Fracture: is relatively uncommon but problematic particularly in cemented implants.
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Implant retained facial prosthesis
Auricle, Orbit, Nasal. First introduced by Pare in 1575. Metal, Porcelin, Acrylic resin, Chrome cobalt were the materials used. A study by Tolmen & Taylor I J OMF Implants in1995 showed as -318 mastoid, 98 orbit, 36 nasal bones had a success rate of 99% in irradiated cases of mastoid, 79% & 81% in orbit & Nasal bone. www.indiandentalacademy.com
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Implant placement is guided by design of prosthesis & availability of sound bone in & around the defect site. Implant placement must be 15mm from the defect.
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Design of craniofacial implants
Available in wide range of shapes & surface preparations. Most widely used Branemark implants. Implants –shorter than intra oral implants & have perforated flange. Flange- increase the implant surface area in bone contact- mainly theoretical. Flange- creates a protected environment from infection which would be difficult to control. Flangeless 3 mm & 4 mm implants recently introduced. www.indiandentalacademy.com
Auricular implants
2-3 implants is been placed in the posterior auricular region. This area corresponds the location of Helix & Antihelix. Mainly it is limited by the location of mastoid aircells.
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Orbital implants
3-5 implants were used depending the area of the defect. They were placed with in the orbital rim. Due to complex anatomy implants were placed only in the superior & lateral part of the rim. Placement should be parallel or slightly inward in relation to frontal plane. Sup orbital rim is reduced or flattened. Extensive defects implants can be placed in the Zygoma or Maxilla. www.indiandentalacademy.com
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Nasal implants
Placed in maxillary or frontal bones. Limiting factors in this frontal sinus & superior margin of the prosthesis for superior aspect of the defect. 3-4 implants were used. Implants were placed in outer counters of the positioner to ensure the best aesthetic results.
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Surgical procedure
Basically it is 2 staged. In stage 1- implants were placed. Normally healing takes 3 months & for irradiated 6 months. In stage 2- implants uncovered & exposed through the skin by connecting abudments. Abudments –shorter 1-2mm above the level of the skin, this decreases stress & less space. www.indiandentalacademy.com
Retentive system
Ball & socket Magnet & Clips Bars & clips. Delvalle –in 1995 studied the mechanical evaluation of craniofacial Osseo integration of retention system. I J OM Implants. It is concluded as Bars & Clips have high retention. www.indiandentalacademy.com
Temporomandibular Joint Implants ď Ź
IndicationsSevere degenerative joint disease, Recurrent ankylosis, Irreparable condyle fracture, Avascular necrosis, Neoplasm requiring extensive resection, Congenital disorders. (TSC)
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Advantages ď Ź
Theoretically-advantages for adult is Lack of donar site morbidity Occlusal stability (autogenous- resorption) No need for intermaxillary fixation Decreased risk of ankylosis from heterotopic bone formation Early range of motion.
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Different materials were used & time tested-tantalum, stainless-steel, vitallium, titanium. www.indiandentalacademy.com
Boyne -1980 used Ti mesh plate over head –but was discontinued because of excessive heterotopic bone formation, leading to ankylosis. Currently used- Christensen prosthesis.-it is a Vitallium fossa implant of 0.5mm thick & available in 40 sizes for Rt & Lt. Implants secured to the eminence & lateral border of the zygomatic arch with 2.0mm screws. 2-TYPES –were type 1 not used because it had 6% to 8% of fracture incidence. www.indiandentalacademy.com
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Stock length ranges from 45 – 55mm & secured with 6 to 8 screws. Care to be taken for inf dental nerve during the placement of then ant ramal screws. Pt is capable of only rotational forces –dues to loss of lateral pterygoid insertion. Unilateral replacement –deviation to the same side on opening.
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Complication
Prosthesis displacement & Fracture Foreign- body reaction to polymeric or mettalic debris Heterotopic bone formation Damage to inferior alveolar nerve by screws Pain Unilateral deviation
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Zygoma Implants
In 1999 Dr. Per-Ingvar Brånemark and colleagues introduced the zygoma implant. Zygoma implant -viable alternative for treatment of patients with extreme resorption of the edentulous maxilla or large pneumatized maxillary sinuses. Initial stability of this elongated fixture is assured by its contact with four osseous cortices, 1. At the ridge crest 2. The sinus floor 3. The roof of the maxillary sinus 4. The superior border of the zygoma.
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Indications When full maxillary edentulism is accompanied by advanced posterior resorption that would otherwise require grafting. ď Ź In partial or incomplete maxillectomy patients when additional implants can be placed in other sites such as the piriform sinus, orbital rims, palatal shelves, or pterygoid plates to support cross-arch stabilization. ď Ź
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Contraindications
There are only two specific situations that would complicate the use of the zygoma implant or make it unnecessary. First, where adequate maxillary bone exists for implant placement in numbers and positions to support a prosthetic appliance, the zygoma implant is not needed. Second situation is where there is not enough premaxillary support for at least two stable implants with good potential longevity.
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Complications
Significant complication is the loss of the implant. Risk of injury to adjacent structures that is, orbit, orbital contents, facial nerve, lacrimal apparatus, infraorbital nerve. Risk of postoperative sinusitis, although less than with sinus lift procedures. Surgical access difficult, deep sedation or general anesthetic required. Fixture failure—although rare, more difficult to retreat. www.indiandentalacademy.com
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The schneiderian membrane in the sinus is removed to allow good visualization and to prevent its interference with site preparation and implant insertion. If portions of the membranes are “picked up” by the implant and carried into the implant preparation in the body of the zygoma, they could interfere with osseointegration. The zygoma implant varies in length from 30 to 52.5 mm. The zygoma implant has an angulated abutment platform. The 45° angulation allows the platform of the implant to emerge in the same plane as that of the www.indiandentalacademy.com conventional implants.
Protective Splinting ď Ź
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One of the unique features of these implants is the strength they provide when used with splinting and cross-arch stabilization. When used or loaded independently, however, it is felt that the off-axis load transfer can be detrimental and possibly counterproductive for maintenance of osseointegration. Immediately following stage II surgery, or exposure of all implants with abutment connections, it is recommended that some protective measures be used to prevent independent stress transfer from the denture base to the implants individually. www.indiandentalacademy.com
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The current protocol calls for splinting all of the newly exposed implants with a soldered bar within 24 hours of abutment connection.
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Vertical Alveolar Augmentation-Bone Grafting ď Ź
Strategies for vertical bone grafting comes in six categories, -guided bone graft augmentation -onlay bone grafting -interposition alveolar bone graft -alveolar distraction osteogenesis -iliac bone graft -sinus bone graft.
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Augmentations without the placement of implants generally resorb unless a nonresorbable grafting material such as hydroxylapatite is used. Alveolar vertical defects -classified according to the size of the defect. Deficiencies can range from1 or 2 mm to 20 mm in height. Monocortical grafts or guided bone graft augmentations are useful for smaller augmentations. Interpositional grafts work well for moderate-sized defects. Distraction osteogenesis is reserved for more extensive alveolar defects. Sinus bone graft, which functions as an “endosteal” www.indiandentalacademy.com expansion of alveolar vertical bone mass.
Guided Bone Graft Augmentation ď Ź ď Ź
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Techniques allow vertical augmentation of up to 10 mm both in the posterior and anterior maxilla and mandible. A barrier membrane is placed and stabilized with tacks or screws in order to protect an autogenous bone graft usually harvested from the retromolar area in the mandible. The membrane is maintained in the site completely covered by the soft tissues for a period of at least 6 months. The implants can be placed either at the time of bone regeneration or at the membrane removal surgery. www.indiandentalacademy.com
Onlay bone grafting
Mandibular bone graft are extensively used with great success rate and include symphysis & ramus buccal shelf as donar site. Success with these grafts can be achieved with defects of up to 6mm. The posterior maxilla and mandible -most common areas of deficiency. Implants are placed in a submerged or nonsubmerged mode after appropriate healing time with the block grafts. Quality of bone from the ramus buccal shelf is typically type 1, and the symphysis normally exhibits type 2. www.indiandentalacademy.com
Four key principles -First, recipient site preparation must be done to allow access for trabecular bone blood vessels and osteogenic cells. Second, two-point fixation of each block is important to prevent microrotation of the graft resulting in incomplete bone incorporation. Third, primary closure without tension of the wound site is critical to prevent dehiscence. Finally, implant placement must follow graft incorporation and should never be done simultaneously. www.indiandentalacademy.com
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The symphysis can provide a range of dense cortical cancellous bone ranging from 4 to 11 mm, in contrast to a typical ramus buccal shelf block graft that is 3 to 4 mm.
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These grafts can be used for predictable horizontal augmentation of 5 to 7 mm and vertical augmentation of up to and including 6 mm.
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Interpositional Bone Graft
Interpositional bone graft is placed between a mobilized segmental osteotomy and the basal bone. Vertical gain is 4 or 5 mm in the maxilla but 5 to 10 mm in the mandible. Indication -alveolar defect where there is insufficient vertical height for placement of implants such as in the anterior maxilla or in the posterior mandible when a stable vertical augmentation is required, usually over a three- or four-tooth segment.
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Alveolar Distraction Osteogenesis
A deficient alveolus can be distracted to improve vertical dimension for implant placement. Sufficient width (5 mm) and vertical height (8 to 10 mm) of a distraction site are needed in order to ensure sufficient (5 × 5 mm) bone mass of the segment to be translated. A biphase distractor plate is placed in order to gain vertical and horizontal displacement of the bone.
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Illiac Corticocancellous Grafting ď Ź
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When the jaw is too deficient to do monocortical grafting or osteotomies, bone graft augmentation with iliac corticocancellous graft is needed. Major grafting is usually required when bone mass needs to be expanded in order to gain enough bone for osseointegration.
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Sinus Bone Graft
Three tech are used, 1. Sinus intrusion osteotomy 2. Lateral approach sinus membrane elevation 3. Alveolar augmentation combined with sinus elevation. The sinus intrusion osteotomy can be done on the day of extraction if the wound is clear of soft tissue and infection. The intrusion was done with a bone graft and implant placement 6 weeks after the dental extraction. Bone graft was also placed into defects within the extraction socket. www.indiandentalacademy.com
The lateral sinus graft is done through a Caldwell-Luc approach by elevating the sinus membrane in order to preserve a “closed wound.” This approach can be used for both simultaneous and delayed implant placement. Barrier membranes are usually not required but benefit over the grafted site if a large “window” is made. The use of piezoelectric surgery is helpful in avoiding perforation of the membrane.
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Thank you
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