A dental implant (also known as endosseous implant or fixture ) is a surgical component that connects with the jawbone or skull to support a dental prosthesis such as a crown, bridges, denture, facial prosthesis or to act as an orthodontic anchor. The basis for modern dental implants is a biological process called osseointegration, in which a material such as titanium forms a tight bond with the bone. The first implant fixture is placed so that it is possible for osseointegrate, then the prosthetic gear is added. A varying amount of healing time is required for osseointegration before the prosthetic teeth (teeth, bridges or denture) are attached to the implant or a buffer placed that will hold the prosthetic tooth.
The success or failure of the implant depends on the health of the person receiving the treatment, the drugs that affect the osseointegration possibilities, and the health of the tissues in the mouth. The amount of stress to be put on the implant and equipment during normal function is also evaluated. Planning the position and number of implants is key to long-term prosthetic health because the biomechanical forces created during chewing can be significant. The position of the implant is determined by the position and angle of adjacent teeth, with a lab simulation or by using computed tomography with CAD/CAM simulation and surgical guides called stents. The prerequisites for the long-term success of dental implantation osseointegration are healthy bones and gingivae. Since both can have atrophy after tooth extraction, a pre-prosthetic procedure such as a sinus lift or a gingival graft is sometimes necessary to recreate the ideal bone and gingiva.
The final prosthetic can be repaired, in which a person can not lift an artificial tooth or teeth from their mouth, or removed, where they can remove the prosthetic. In each case the support is attached to the implant fixture. Where prosthetic is repaired, crown, bridge or denture is fitted to either abutment with lag screws or with cement gear. Where the prosthetic is removed, the appropriate adapter is placed in the prosthetic so that two pieces can be secured together.
The risks and complications associated with implant therapy are divided into those that occur during surgery (such as excessive bleeding or nerve injury), occurring within the first six months (such as infection and osseointegrate failure) and which occur in the long term (eg peri-implantitis and failure mechanical). In the presence of healthy tissue, well-integrated implants with appropriate biomechanical loads can have a 5-year survival rate plus from 93 to 98 percent and 10 to 15 years lifespan for prosthetic teeth. Long-term studies show a success of 16 to 20 years (implant survival without complication or revision) between 52% and 76%, with complications that occur up to 48% of the time.
Video Dental implant
Medical use
The main use of dental implants is to support dental prosthetics. Modern dental implants use osseointegration, a biological process in which bones coalesce closely to the surface of specific materials such as titanium and some ceramics. Implant and bone integration can support physical loads for decades without failure.
For individual tooth replacements, the implant buffer is first secured to the implant with an abutment screw. The crown (prosthesis gear) is then connected to a support with cement gear, small screw, or fused with abutments as one part during fabrication. Dental implants, in the same way, can also be used to maintain multiple denture teeth either in the form of fixed bridges or removable dentures.
Implants supported by bridges (or permanent dentures) are a group of teeth secured for dental implants so that the prosthetic can not be removed by the user. Bridges are usually connected to more than one implant and may also be connected to the tooth as an anchor point. Usually the number of teeth will exceed the anchor points with a tooth that is directly above the implant called abutment and the tooth between abutments called as pontik. The implant-supported bridge is attached to the implant buffer in the same way as a single dental implant replacement. The bridge can still replace at least two teeth (also known as permanent partial denture) and can extend to replace the entire dental arch (also known as full artificial tooth). In both cases, the prosthesis is said to be fixed because it can not be removed by the denture wearer.
Denture-supported detachable implants (also overdenture-supported implants) are a permanently installed non-permanent dental prosthesis. The dental prosthesis can be disconnected from the implant support with the finger pressure by the wearer. To enable this, the abutment is formed as a small connector (button, ball, bar or magnet) that can be connected to the analog adapter at the bottom of the prosthesis gear. Facial prosthetic, used to correct facial deformity (eg from cancer treatment or injury) can use a connection to an implant placed on the facial bone. Depending on the situation the implant may be used to maintain a fixed prosthetic or removal that replaces the face.
In orthodontics, small diameter dental implants, referred to as Temporary Anchorage Devices (or TADs) can help the movement of teeth by creating an anchor point from which strength can be generated. In order for the tooth to move, a force must be applied to them in the direction of the desired movement. This force stimulates cells in the periodontal ligament to cause bone remodeling, removing the bone in the direction of the tooth travel and adding it to the space created. To produce a force on the tooth, anchor point (something that will not move) is required. Because implants do not have periodontal ligaments, and bone remodeling will not be stimulated when tension is applied, they are the ideal anchor point in orthodontics. Typically, implants designed for orthodontic motion are small and not fully osseointegrate, allowing easy removal after treatment.
Maps Dental implant
Technique
Planning
General considerations
Planning for dental implants focuses on the patient's general health condition, local health conditions of mucous membranes and jaws and the shape, size, and position of the jawbone, adjacent and opposing teeth. There are some health conditions that actually hinder the placement of the implants even if there are certain conditions that may increase the risk of failure. Those with poor oral hygiene, heavy smokers and diabetics are all at greater risk for gum disease variants that affect implants called peri-implantitis, increasing the likelihood of long-term failure. Use of long-term steroids, osteoporosis, and other diseases affecting bone can increase the risk of early implant failure.
It has been suggested that radiotherapy may adversely affect the viability of the implant. Nevertheless, a systemic study published in 2016 concluded that dental implants installed in irradiated areas of the oral cavity may have high survival rates, provided that patients maintain oral hygiene measures and regular follow-up to prevent complications.
Drug bisphosphonates
The use of bone-building drugs, such as bisphosphonates and anti-RANKL drugs require special consideration with implants, as they have been associated with a disorder called Bisphosphonate-associated osteonecrosis of the rahaw (BRONJ). Drugs change bone turnover, which is thought to put people at risk of bone death while undergoing minor mouth surgery. In routine doses (eg, used to treat routine osteoporosis) the effects of drugs linger for months or years but the risks seem very low. Because of this duality, uncertainty exists in the dental community about how best to manage BRONJ's risk when placing an implant. A 2009 position paper by the American Association of Oral and Maxillofacial Surgeons, discusses that the risk of BRONJ from oral slow-dose therapy (0.01 to 0.06 percent) for any procedure performed on the jaw (implant, extraction, etc.). The risk is higher with intravenous therapy, mandibular procedures, people with other medical problems, those taking steroids, those with stronger bisphosphonates and people who have been taking this drug for more than three years. Position paper recommends not to place implants in people who use high-dose or high-dose intravenous therapy for cancer treatment. Otherwise, the implant can generally be placed and the use of bisphosphonates does not seem to affect the implant's viability.
Biomechanical considerations
The long-term success of the implant is determined, in part, by the strength they must support. Since the implant lacks a periodontal ligament, there is no pressure sensation when it bites so that the created power is higher. To compensate for this, the location of the implant must evenly distribute the power across the prosthetics they support. Concentrated forces may result in bridgework fractures, implant components, or bone loss adjacent to the implant. The primary location of the implant is based on both biological (bone type, vital structure, health) and mechanical factors. Implants placed in thicker and stronger bones such as those found on the lower front of the mandible have a lower failure rate than implants placed in low-density bones, such as the upper back of the upper jaw. People who grind their teeth also increase the power on the implant and increase the likelihood of failure.
The implant design should take into account the lifelong real-life use in a person's mouth. Regulators and dental implant industries have created a series of tests to determine the long-term mechanical reliability of implants in a person's mouth where the implant is hit repeatedly with increasing strength (similar in magnitude to bite) to failure.
When more precise plans are needed beyond clinical judgments, dentists will create acrylic guides (called stents) before surgery that guides optimal placement of implants. The more, the dentist chooses to get the CT scan of the jaw and the existing dentures, then plans the operation on the CAD/CAM software. Stents can then be made using stereolithography after computerized case planning of CT scan. The use of CT scans in complex cases also helps surgeons identify and avoid vital structures such as the inferior alveolar nerves and sinuses.
Main surgical procedure
Placing implants
Most implant systems have five basic steps for placement of each implant:
- Soft tissue reflexology: An incision is made over the top of the bone, splitting the gingiva attached to the thickness of about half so that the final implant will have thick bands around it. The edge of the tissue, each referred to as flap is pushed back to expose the bone. Flapless surgery is an alternative technique, in which a small puncture of tissue (implant diameter) is removed for implant placement rather than raising the flap.
- High-speed drilling: After reflecting soft tissue, and using the required surgical or stent guidance, the pilot hole is placed with a high-speed precision exercise to prevent combustion or bone necrosis pressure.
- Drilling at low speed: The pilot hole is extended by progressively progressing exercises (usually between three and seven consecutive drilling steps, depending on the length and length of the implant). Treatment is taken not to damage osteoblast cells or bones from overheating. Copy cooling or water spray keeps the temperature low.
- Implant placement: The implant screw is placed and can be tapped on its own, otherwise the prepared site is tapped with an implanted analog. It is then screwed into place with a torque-controlled lock at the proper torque to avoid burdening the surrounding bone (an overloaded bone can die, a condition called osteonecrosis, which can cause an implant failure to fully integrate or bond with the jawbone).
- Network adaptation: Gingiva is adapted around the entire implant to provide a thick band of healthy tissue around the healing buffer . In contrast, the implant can be "buried", where the top of the implant is sealed with a closed screw and a closed network to cover completely. The second procedure will then be needed to uncover the implant in the future.
Implant installation time after tooth extraction
There are different approaches to the placement of dental implants after tooth extraction. The approach is:
- Immediate post-extraction implant placement.
- The post-extraction implant placement is immediately delayed (two weeks to three months after extraction).
- Slow implantation (three months or more after tooth extraction).
There are also various options for when to put the teeth into dental implants, classified into:
- Immediate loading procedure.
- Initial loading (one week to twelve weeks).
- Pending delay (more than three months)
Healing time
In order for the implant to become permanently stable, the body must grow the bone to the surface of the implant (osseointegration). Based on this biological process, it is thought that inserting an implant during the osseointegration period will produce a motion that will prevent osseointegration, and thus increase the implant failure rate. As a result, three to six months of integration time (depending on various factors) is permitted before placing teeth on an implant (restoring them).
However, subsequent research shows that the initial stability of the implant in the bone is a more important determinant of successful integration of the implant, rather than a certain period of healing time. As a result, the time allowed to heal is usually based on the implant bone density placed in and the number of implants splinted together, rather than a uniform amount of time. When the implant can withstand high torque (35 Ncm) and be inserted into other implants, there is no significant difference in long-term implant survival or bone loss between implants that are loaded immediately, at three months, or at six months. The natural consequence is that single implants, even in solid bones, require a no-load period to minimize the risk of initial failure.
One-on-two-stage operation
After the implant is placed, the internal component is covered with a healing buffer, or a screw cover. A healer heal goes through the mucosa, and the surrounding mucosa is adapted around it. The screw cover is rinsed with a dental implant surface, and is designed to be completely covered by the mucosa. After a period of integration, a second operation is required to reflect the mucosa and place the healing buffer.
In the early stages of implant development (1970-1990), the implant system uses a two-stage approach, believing that it increases the chances of early implant survival. Subsequent research has shown that there is no difference in the viability of existing implants between single stage and two-stage operations, and whether or not to "bury" the implants in the first stage of the surgery into soft-tissue management (gingival)
When the tissue is deficient or mutilated by tooth loss, the implant is placed and allowed for osseointegrate, then the gingiva is surgically removed around the healing support. The down side of the two-stage technique is the need for additional surgery and the compromise of circulation to the network due to repeated operations. A choice of one or two stages, now centered around the best way to reconstruct the soft tissue around the missing tooth.
Immediate placement
An increasingly common strategy for preserving bone and reducing maintenance time includes the placement of dental implants to a recent extraction site. On the one hand, it shortens maintenance time and can improve aesthetics due to the soft tissue envelope being preserved. On the other hand, the implant may have a slightly higher initial failure rate. The conclusions on this topic are difficult to draw, however, as several studies have compared direct and scientifically delayed implants strictly.
Additional surgical procedures
For implants to osseointegrate, it is necessary to be surrounded by healthy amounts of bone. In order to survive in the long run, it is necessary to have a thick healthy soft tissue envelope (gingiva) around it. It is common for the bone or soft tissue to be so lacking that the surgeon needs to reconstruct it either before or during the placement of the implant.
Hard tissue (bone) reconstruction
Bone transplantation is needed when there is a lack of bone. While there are always new types of implants, such as short implants, and techniques to allow compromise, the general treatment goal is to have at least 10 mm in bone height, and 6 mm in width. Or, bone damage is assessed from A to D (A = 10 mm bone, B = 7-9 mm, C = 4-6 mm and D = 0-3 mm) where the probability of an osseointegrating implant is related to bone level.
To achieve adequate bone width and height, various bone grafting techniques have been developed. The most commonly used augmentation is guided bone graft in which a defect is filled with bone or allograft (donor bone or synthetic bone replacement), which is covered with a semi-permeable membrane and allowed to heal. During the healing phase, the natural bone replaces the graft forming a new bone base for the implant.
Three common procedures are:
- Lift the sine
- Lateral alveolar enlargement (site width increase)
- Vertical alveolar augmentation (height increase of a site)
Other more invasive procedures are also present for larger bone defects including inferior alveolar nerve mobilization to enable fixture placement, onlay bone grafting using iliac crest or other large sources of bone and microvascular bone graft in which blood supply to bone. transplanted with source bone and reconnected with local blood supply. The final decision on the best bone grafting technique is based on an assessment of existing vertical and horizontal bone loss rates, each classified as mild (2-3 mm), medium (4-6 mm) or weight (greater than 6 mm). Orthodontic extrusion or orthodontic implant site development may be used in certain cases for vertical/horizontal alveolar augmentation.
Soft-tissue reconstruction (gingiva)
The gingiva that surrounds the tooth has a bright pink 2-3 mm band, a very strong inherent mucosa, then a darker and larger area of ​​the unbinding mucosa that folds into the cheek. When replacing a tooth with an implant, a group of strong and attached gingiva is needed to keep the implant healthy over the long term. This is especially important with implants because the blood supply is more precarious in the gingiva that surrounds the implant, and theoretically more susceptible to injury due to longer attachment to the implant than on the teeth (longer biologic width).
When an inadequately attached adhesive group is absent, it can be recreated with a soft tissue graft. There are four methods that can be used for soft tissue transplantation. The coil of tissue adjacent to the implant (referred to as the palatal roll) may be moved toward the lips (buccal), the gingiva from the ceiling may be transplanted, the deeper connective tissue of the ceiling may be transplanted or, when larger pieces of tissue are required , tissue fingers based on blood vessels in the ceiling (called interferitional tissue periosteal-connective vascularization (VIP-CT) flap) can be positioned back into the area.
In addition, for implants to look aesthetic, a full roll of gingiva is required to fill the space on either side of the implant. The most common soft-tissue complication is called the black triangle, where the papilla (a small triangular piece of tissue between two teeth) shrinks backwards and leaves a triangular gap between the implant and adjacent teeth. Dentists can only expect 2-4 mm high papillae over the underlying bone. A black triangle can be expected if the distance between where the tooth is touching and the bone is larger.
Recovery
The prosthetic phase begins after the implant is well integrated (or has a reasonable guarantee that the implant will integrate) and the abutment is installed to carry it through the mucosa. Even in the case of initial loading (less than 3 months), many practitioners will place temporary teeth until a confirmation configuration is confirmed. The prosthetic phase to return the implants requires technical expertise in the same amount of surgery as biomechanical considerations, especially when some teeth need to be restored. The dentist will work to restore the vertical dimensions of occlusion, the aesthetics of the smile, and the structural integrity of the teeth to distribute the implant power evenly.
Prosthetic procedures for single tooth, bridges and permanent dentures
Abutment is selected depending on the application. In many single crowns and some fixed denture scenarios (bridgework), custom abutment is used. The impression from the top of the implant is made with adjacent teeth and gingiva. A dental lab then simultaneously creates an abutment and a crown. The buffer sits on top of the implant, the screw passes through the abutment to secure it to the internal thread on the implant (lag-screw). There are variations in this, such as when the abutment and implant bodies are one part or when abutment stock (prefabricated) is used. Custom mounts can be made by hand, as cast or custom cast pieces are milled from metal or zirconia, all of which have the same success rate.
The platform between the implant and the abutment can be flat (berbanir) or conical fit. In a conical buffer, the collar of the buffer sits inside the implant allowing a stronger intersection between the implant and the abutment and a better seal against the bacteria into the implanted body. To increase the gingival seal around the abutment collar, a narrow collar in abutment is used, referred to as a platform transition. The combination of conical installation and platform transition provides a slightly better long periodontal condition than a flat buffer.
Regardless of the material or abutment technique, the abutment impression is then taken and the crown secured to the abutment with cement gear. Another variation in the abutment/crown model is when the crown and abutment are one part and the lag-screw crosses both to secure the one-piece structure to the internal thread on the implant. There seems to be no benefit, in terms of success, to cement prosthetics versus screw retention, although the latter is believed to be more easily maintained (and altered when prosthetic fractures) and the former offers high aesthetic performance.
Prosthetic procedure for removable dentures
When the removable denture is used, the holders to hold the denture in place may be a specially made or off-the-shelf (stock) buffer. When a custom follower is used, four or more implant fixtures are placed and implanted implants are taken and the dental lab makes a custom metal rod with an attachment to hold the dentures in place. Significant retention can be made with multiple attachments and use of semi-precision attachments (such as small diameter pins pushing through dentures and into bars) that allow for little or no movement in dentures, but can be removed. However, four similarly skewed implants in such a way as to distribute occlusal forces may be able to hold fixed artificial teeth at comparable costs and the number of procedures that provide denture wearers of fixed solutions.
Alternatively, stock abutment is used to maintain dentures using a male adapter attached to an implant and a female adapter in a denture. Two common types of adapters are ball bearing styles and socket and button-style adapters. This stock buffer type allows for the movement of the denture, but sufficient retention to improve the quality of life for dentist users, compared with conventional dentures. Regardless of the type of adapter, the female portion of the adapter placed on the denture will require periodic replacement, but the number and type of adapter does not seem to affect patient satisfaction with prosthetics for various removable alternatives.
Maintenance
After placement, the implants need to be cleaned (similar to natural teeth) with Teflon instruments to remove plaque. Because of the more dangerous blood supply to the gingiva, care must be taken with dental floss. The implant will lose bone at the same level as the natural teeth in the mouth (for example if a person suffers from periodontal disease, the implant may be affected by a similar disorder) but will last a long time. Porcelain on the crown should be expected to change color, fracture or require repair approximately every ten years, although there are significant variations in the life of the dental crown based on the position in the mouth, the force applied from the opposing teeth and the restorative material. Where implants are used to maintain complete denture, depending on the type of attachment, the connection needs to be changed or refreshed every one to two years. A powerful irrigator may also be useful for cleaning around implants.
Risks and complications
During operation
Placement of dental implants is a surgical procedure and carries a normal risk of surgery including infection, excessive bleeding and tissue necrosis of the tissue around the implant. The closest anatomical structures, such as the inferior alveolar nerve, the maxillary sinus and blood vessels, can also be injured when osteotomy is made or an implant is placed. Even when the maxillary sinus layer is perforated by implants, long-term sinusitis is rare. The inability to place implants in the bone to provide implant stability (referred to as primary stability of the implant) increases the risk of failure for osseointegration.
First six months
Primary implant stability
The stability of the primary implants refers to the stability of the dental implants immediately after implantation. The stability of titanium screw implants in postoperative patient bone tissue may be assessed non-invasively using resonance frequency analysis. Sufficient initial stability allows immediate loading with prosthetic reconstruction, although initial loading has a higher risk of implant failure than conventional loading.
The relevance of primary implant stability decreases gradually with the re-growth of bone tissue around the implant in the first weeks after surgery, leading to secondary stability. Secondary stability differs from initial stabilization, due to the result of a continuous process of regrowth of bone into the implant (osseointegration). When this healing process is complete, the initial mechanical stability becomes biological stability. Primary stability is essential for successful implantation until bone regrowth maximizes the mechanical and biological support of the implant. Re-growth usually occurs for 3-4 weeks after implantation. Inadequate primary stability, or high initial implant mobility, can lead to failure.
Post-operative risk immediately
- Infection (pre-op antibiotics reduce the risk of implant failure by 33 percent but does not affect the risk of infection).
- Excessive bleeding
- Flap details (less than 5 percent)
Failure to integrate
Implants were tested between 8 and 24 weeks to determine if it was integrated. There are significant variations in the criteria used to determine the success of the implant, the criteria most often cited at the implant level is the absence of pain, mobility, infection, gingival bleeding, lucency radiography or peri-implant loss greater than 1.5 mm.
The success of dental implants is related to operator skills, the quality and quantity of bones available on the site, and the oral hygiene of the patient, but the most important factor is the stability of the primary implant. Although there are significant variations in implant levels that fail to be integrated (due to individual risk factors), the estimated value is 1 to 6 percent
Integration failure is rare, especially if the dentist's instructions or oral surgeon is followed by the patient. Implant loading may soon have a higher failure rate, potentially because it is loaded immediately after trauma or extraction, but the difference with proper care and maintenance is good in statistical variance for this type of procedure. More often, osseointegration failure occurs when a patient is too unhealthy to receive an implant or engage in proper contraindications to proper dental hygiene including smoking or drug use.
Long run
The long-term complications resulting from dental recovery with implants are directly related to patient and technology risk factors. There are risks associated with appearance including high smile lines, poor gingival quality and missing papilla, difficulty in matching natural tooth form which may have unequal contact points or unusual shapes, missing bone, stop developing or other forms of unsuitable expectations, unrealistic expectations of the patient or poor oral hygiene. Risks can be attributed to biomechanical factors, where the implant geometry does not support teeth in the same way as natural teeth when there is a cantilever extension, fewer implants than roots or teeth longer than the implants that support them (poor crown-to-root ratio ). Similarly, grinding of teeth, lack of bone or low diameter implants increases the risk of biomechanics. Finally there is a technological risk, where the implant itself can fail due to fracture or loss of retention on the teeth they want to support.
From these theoretical risks, get real world complications. Long-term failure is due to bone loss around the teeth and/or gingiva due to peri-implantitis or implantable mechanical failure. Since there is no tooth enamel on the implant, it does not fail because the cavities are natural. While long-term and rare studies, some systematic reviews estimate the long-term (five to ten years) dental implant survival at 93-98 percent depending on their clinical use. During the early development of the implanted denture, all crowns are attached to the teeth with screws, but more recent advances have enabled the placement of the crown on the support with cement gears (similar to placing the crown on the teeth). This has created the potential for cement, which escapes from beneath the crown during cementation to get trapped in the gingiva and create peri-implantitis (see image below). While complications may occur, there appears to be no additional peri-implantitis in the crown retained on cement compared to the overall screw crown crown. In compound implants (two-stage implants), between the actual implant and the superstructure (abutment) are the gaps and cavities in which bacteria can penetrate from the oral cavity. Later this bacteria will return to adjacent tissues and can cause periimplantitis. As prophylaxis, these implant interior spaces must be sealed.
The prosthetic-supported dental implant success criteria vary from study to study, but can be broadly classified into failure due to implant, soft tissue or prosthetic components or lack of satisfaction in the patient's part. The most frequently cited criterion for success is a function of at least five years in the absence of pain, mobility, lucency radiography and peri-implant loss greater than 1.5 mm in implants, lack of suppuration or soft tissue bleeding. and the occurrence of technical complications/prosthetic treatment, adequate function, and aesthetics in the prosthetic. In addition, patients should ideally be free of pain, paresthesias, able to chew and feel and feel happy with the aesthetics.
The degree of complications varies with the use of implants and prosthetic types and is listed below:
Single crown implant (5 years)
- Live implants: 96.8 percent
- Fracture of crown: a) metal-ceramic: 95.4 percent, ceramic powder; 95.4 percent (cumulative rate of ceramic crack or veneer: 4.5 percent)
- Fairy-implantitis: 9.7 percent to 56 percent
- Implant fracture: 0.14 percent
- Abutment screws or sealing: 12.7 percent
- Abutment screw fracture: 0.35 percent
Fixed full dentures
- Progressive vertical bone destruction but still functioning (Peri-implantitis): 8.5 percent
- Failure after first year 5 percent at five years, 7 percent in ten years
- Incidence of veneer fracture in:
-
- 5 years : 13.5 to 30.6 percent,
10 years : 51.9 percent (32.3 to 75.5 percent with 95 percent confidence intervals)
15 years : 66.6 percent (44.3 to 86.4 percent with 95 percent confidence intervals) -
- 10 years incident fracture framework: 6 percent (2.6 to 9.3 percent with 95 percent confidence interval)
- 10 years of aesthetic deficiency: 6.1 percent (2.4 to 9.7 percent with 95 percent confidence interval)
- prosthetic screws loosen: 5 percent for five years to 15 percent for ten years
The most common complications are fracture or tooth structure wear, especially over ten years with fixed-metal dentures that have a ten-year survival higher than those made from gold-acrylic.
Overdentures
- Loosen the removable denture retention: 33 percent
- Dentures need to be connected or have a retention clip fracture: 16 to 19 percent
History
There is archaeological evidence that humans have been trying to replace missing teeth with rootform implants for thousands of years. The rest of ancient China (dating 4000 years ago) has carved bamboo sticks, tapped bones, replaced lost teeth, and the 2000-year-old remnants of ancient Egypt had similar-shaped pegs made of precious metal. Some Egyptian mummies are found to have transplanted human teeth, and in other cases, the teeth are made of ivory.
Wilson Popenoe and his wife in 1931, at a site in Honduras since 600 AD, found the lower jaw of a young Mayan woman, with three missing incisors replaced by shell pieces, shaped like teeth. The bone growth of about two of the implants, and the formation of calculus, indicates that they function as well as esthetically. This fragment is currently part of the Osteological Collection of the Peabody Museum of Archeology and Ethnology at Harvard University.
The early part of the 20th century saw a number of implants made of various materials. One of the earliest successful implants was the Greenfield implant system of 1913 (also known as the Greenfield bed or basket). Greenfield implants, iridioplatinum implants attached to golden crowns, show evidence of osseointegration and last for several years. The first use of titanium as an implant material was by Bothe, Beaton and Davenport in 1940, who observed how close the bone grew into titanium screws, and the difficulties they had in extracting them. Bothe et al. was the first researcher to describe what came to be called osseointegration (a name that will be marketed later by Per-Ingvar BrÃÆ' nemark). In 1951, Gottlieb Leventhal implanted a titanium rod in a rabbit. Leventhal's positive results make him believe that titanium represents an ideal metal for surgery.
In the 1950s research was underway at Cambridge University in England in the bloodstream of living organisms. These workers devised a method of constructing titanium spaces that were then embedded into the soft tissues of rabbit ears. In 1952, the Swedish orthopedic surgeon, Per-Ingvar BrÃÆ' nemark, was interested in studying the healing and regeneration of bones. During his research time at Lund University, he adopted a "rabbit ear room" designed for use in rabbit's thighs. After doing the research, he tried to take the expensive rooms of the rabbits and found that he could not remove them. BrÃÆ'  ¥ nemark observes that the bone has grown so close to the titanium that it is effectively attached to the metal. BrÃÆ'  ¥ nemark undertook further studies into this phenomenon, using animal and human subjects, all of which affirmed the unique properties of this titanium. Leonard Linkow, in the 1950s, was one of the first to insert titanium and other metal implants into the jawbone. The artificial teeth are then attached to these pieces of metal. In 1965 BrÃÆ'  ¥ nemark placed his first titanium dental implant into human volunteers. He started working at the mouth because it was more accessible for follow-up observation and there was a high level of tooth loss in the general population that offered more subjects for extensive study. He called clinically observed bone compliance with titanium as "osseointegration".
Since then the implants have evolved into three basic types:
- Root form implant; the most common types of implants are indicated for all uses. In the root form of this type of implant, there are about 18 variants, all made of titanium but with different surface shapes and textures. There is limited evidence to suggest that implants with relatively smooth surfaces are less susceptible to peri-implantitis than implants with rough surfaces and there is no evidence to suggest that certain types of dental implants have superior long-term success.
- zygoma implants; long implants that can be attached to the cheekbones by passing through the maxillary sinus to keep the complete top denture when the bone does not exist. While the zygomatic implant offers a new approach to severe upper bone loss, it has not been proven to offer any benefit to functional bone grafting although it may offer a less invasive option, depending on the size of the reconstruction required.
- Small diameter implants are low-diameter implants with one-piece (implant and abutment) construction that are sometimes used for denture retention or orthodontic retention.
A typical implant consists of a titanium screw (resembling a tooth root) with a coarse or fine surface. The majority of dental implants are made of commercially pure titanium, which is available in four grades depending on the amount of carbon, nitrogen, oxygen and iron contained. Cold work hardened CP4 (maximum impurity limit of.05 percent, C10 percent, H0.0 percent, Fe 50 percent, and O.40 percent) was the most commonly used titanium for implants. Titanium grade 5, Titanium 6AL-4V, (indicating titanium alloy containing 6 percent aluminum and 4 percent vanadium alloy) is slightly harder than CP4 and is used in industry especially for abutment and abutment screws. Most modern dental implants also have a textured surface (via etching, anodic oxidation or blasting of various media) to increase the surface area and potential osteointegration potential of the implant.
If C.P. titanium or titanium alloy has a titanium content of more than 85%, it will form a titanium titanium titanium layer biocompatable titanium or veneer that encloses another metal that prevents it from bone contact.
References
Source
Source of the article : Wikipedia
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