Dental Implants: Procedure for Placing Implants and Correct Application - Essay Example

Dental Implants Dental Implants Introduction Teeth may be lost through dental diseases, trauma or be congenitally absent. Missing teeth and supporting oral tissues have traditionally been replaced with removable dentures or fixed partial dentures permitting restoration of masticatory, phonetic, function, and aesthetics. In 1977, Branemark presented his research work carried out over 10 years showing that bone can grow intimately into contact with the surface of titanium implants (Lindhe et al., 2003). Undoubtedly the now well-accepted concept, termed osseointegration, has been one of the most significant scientific breakthroughs in dentistry over the past 30 years. The achievement of osseointegration between the device and the surrounding tissues is an index of a successful implant. The ideal dental prosthesis would be a replacement system that looks and functions like natural teeth, is durable, does not damage existing structures, and doesn't cause unwanted side effects. Many dentists are optimistic that the latest generation of implant technology fulfills these goals. The basis of an implant is a titanium metal screw that is surgically inserted into the alveolar bone of the upper or lower jaw in a spot where the natural tool h has fallen out or been extracted. The screw, which provides the anchor for replacement teeth, acts as a substitute for a natural tooth root. A dentist can place implants alone or in combination. They can serve as abutments for individual replacement teeth or fixed bridges, or as anchors for full or partial removable dentures. (Dental Implant Information, 2006) Literature Review Implants are categorized as endosteal (implants within the bone), subperiosteal (framework placed on bone), or transosteal (implants placed through the bone from the superior to the inferior aspect). The endosteal is the most commonly used at this time and can be either root-, blade-, or plate-form. (Lindhe et al., 2003) The endosteal dental implants can be either two-stage (a portion of the implant is placed within the bone and allowed to heal uninterrupted for 4-6 months prior to placement of the coronal aspect) or single-stage (implant is placed within the bone but the coronal aspect is placed at the gingival margin and not covered with soft tissue, negating the need for uncovering). (Hedia et al., 2004) There are three basic types of synthetic biomaterials for dental implants: metals and alloys, ceramics and carbon, and polymers. (Berglundh et al., 2002) The most commonly used metals are titanium and titanium-aluminum-vanadium alloy. Now all root-form fixtures are titanium or titanium alloy; the titanium has a low density, which gives it a high strength-to-weight ratio and can be alloyed easily with aluminum (to increase the strength and decrease the weight of the material) and vanadium (to act as an aluminum scavenger, preventing surface corrosion). The ceramics would include aluminum oxide and hydroxylapatite. Hydroxylapatite coatings have been applied to the titanium/titanium alloy fixtures to produce a bio-active surface which presumably promotes and induces a direct bond between the implant and the hard tissues (Fiorellini et al., 2000). This direct bond or contact between bone and the implant surface occurs only with hydroxylapatite and has been called "biointegration" (Lindhe et al., 2003). The utilization of synthetic polymers and composites continues to expand for biomaterial application. Fiber-reinforced polymers offer advantages in that they can be designed to match tissue properties, can be anisotropic with respect to mechanical characteristics, can be coated for tissue attachment, and can be fabricated at relatively low cost. In general polymers have lower strengths and elastic moduli and higher elongations to fracture compared with other classes of biomaterials. Compare with bone, most polymers have lower elastic moduli, with magnitudes closer to soft tissues. The phenomenon of osseointegration relies on bone-to-implant contact without the interposition of connective tissue when the implant is immobile and resting. (Hedia et al., 2004) The difference in the finding of osseointegration vs. biointegration lies in a greater amount of bone-to-implant contact with hydroxylapatite-coated implants (biointegration) than with titanium or titanium alloy implant surfaces (osseointegration) (Lindhe et al., 2003). HA-coated surfaces have been referred to as osteoconductive or bioactive, while the titanium/titanium alloy is referred to as bioinert. HA-coated implants are superior in sites which are compromised in either quantity or quality of bone (Oh et al., 2002). However microbiologically, the HA-coated implant surface may be at increased risk to bacterial plaque. Discussion Procedure for Placing Implants Traditional implant placement is a multi-step process. First, the dentist places the implants deep enough so he or she can suture the gum tissue over them. Then they are left to heal for three to six months without any teeth attached. This approach, called "unloaded" healing, reflects the belief that observing a long waiting period before burdening the implant with the stress of replacement teeth is essential to osseointegration. At the end of this healing period, a second surgery is performed to uncover the implants and to attach metal extensions (called abutment cylinders) that protrude above the gums. The individual then waits another two to four weeks for the gum tissue to heal before the replacement teeth arc installed. (Hedia et al., 2004) Although certain cases still demand this more conservative protocol, advances in implantation techniques mean that the treatment can now be clone successfully in fewer steps over a shorter period. Some of the newer options available to implant candidates include: a) one-stage placement, in which die abutments and implants are placed in a single surgery; b) immediate implants, in which the implants are inserted right after tooth extraction; c) shorter healing times before installing the teeth c 8 weeks instead of 3-6 months overall); d) immediate loading, a less common procedure in which teeth are attached to implants immediately after surgery (Lindhe et al., 2003). It's important to recognize, though, that successful osseointegration demands certain conditions. The implant material must be titanium. The dentist must use a careful surgical technique, drilling slowly and irrigating copiously to avoid overheating that can damage the bone. The implant should be placed firmly into the alveolar bone so that it remains stable (bone won't heal on a mobile implant), and there must be no infection in the implant site. Given these requirements, the dentist performing the procedure must carefully evaluate the oral status of each patient to determine which surgical process has the best chance of success. Correct Application and Adaptation Implants aren't a good option for children and adolescents, because their jawbones are still growing. For adults though, age doesn't matter. Adults of any age may be good candidates for implants, depending on several other factors. For example, certain medical conditions can interfere with the success of implants. Treatments such as chemotherapy, radiation, and immunosuppression can hinder a person's ability to heal. In addition, people with conditions such as type 2 diabetes, bleeding disorders immune deficiency, impaired cardiovascular function, or certain bone diseases are not good candidates for implants (Oh et al., 2002). People who smoke more than 10 cigarettes a day may not have as much success with implants. Generally, smokers have a 5%-10% lower long-term success rate than non-smokers. (Axelsson et al., 1998) If patient have any oral diseases - such as mouth ulcers, active periodontal disease, decay, or pulp problems - a dentist should treat them before placing dental implants. Having osteoporosis - a disease that causes bone loss - does not necessarily prevent a person from getting implants. Although bones elsewhere in the body may be damaged, the jawbone may not be affected to the degree that implants are impossible. Implants may not be suitable for individuals who aren't motivated to maintain their oral health or who have conditions that interfere with their ability to care for an implant over rime (Oh et al., 2002). Putting in an Implant The implant procedure begins with the dentist opening the gums and drilling a hole in the upper or lower jaw in the spot where the tooth will be set. Then the titanium screw that will hold the tooth is set into the hole and the gum tissue is stitched around or over the healing cap. The area is then allowed to heal for six weeks to six months so that the bone can grow around the titanium screw. Then if necessary, another surgery is done to uncover the healing cap. The dentist removes the healing cap and replaces it with an abutment. Finally, the custom-made crown, which is fabricated in the dental laboratory, is attached to the abutment. The new tooth is in place. (Lindhe et al., 2003) Bone Grafts and Implants In the past, having an alveolar bone that wasn't wide or high enough also made dental implants impossible. That's no longer the case, thanks to significant advances in techniques to regenerate or replace missing jawbone. Newly developed augmentation or grafting procedures enable a dentist to add bone to areas that are deficient. One example is the "sinus lift" procedure, in which the thin bone at the bottom of the maxillary sinuses in the back of the upper jaw is augmented with additional bone, typically from another pan of the body. (Hedia et al., 2004) This process nets enough bone to support the placement of dental implants. Bone grafting can be done at the same time that the implant is placed, provided there is enough bone to stabilize the device. If there is too little bone at die outset to guarantee that the implant can be placed firmly, the process is done in steps. The bone grafting is performed first, and the new bone is allowed to heal for several months before the dentist places the implant. The length of healing time needed after bone grafting depends primarily on the type of grafting material used. (Lindhe et al., 2003) The surgeon performing the bone graft can choose from a variety of materials and techniques. One option is to take bone from another place in the patient's mouth, such as the back of the lower jaw or the chin. These sources are used when relatively small amounts of bone are needed. If a larger amount is required, the surgeon must look to sites outside the mouth, such as the hip, shin, ribs, or even the skull. Someone who has worn dentures for many years and has lost most of his or her alveolar bone would need this type of larger graft. Other sources for replacement bone include allo-grafts (human cadaver bone), xenogralts (animal tissue), or synthetic products. (Hedia et al., 2004) Generally, overall success rates are very good for the bone grafts themselves, as well as for implants placed in bone grafts. The surgeon's expertise with the particular technique seems to be more important than the material used or the technique chosen. Conclusion Complications of Implants There are two categories of complications that occur in implant therapy: biological and technical (mechanical) (Berglundh, et al. 2002). Biological complications refer to disturbances in the function of the implant characterized by biological processes that affect the tissues supporting the implant. They can be distinguished into early and late losses. Biological complications also include reactions in the peri-implant hard and soft tissues, and the detection of such complications requires adequate clinical, and radiographic examination methods. Mechanical complications serve as a collective term for mechanical damage of the implant/implant components and suprastructures. The success rate for modem implants is very good. Recent data from long-term clinical trials have shown success rates of more than 95% at the end of five years and 90% after 10 years. (Fiorellini et al., 2002) Implications for Dental Hygienists With the advent of implant prosthetics resembling more traditional crown-and-bridge restorations, it is often impossible to recognize what is an implant-supported prosthesis vs. a traditional prosthesis. The hygienist needs to be aware of the presence of implants and decide which instrumentation is best for that particular implant system and prosthetics. Many controversies surround implantology. Dental professionals are only beginning to understand issues such as surgical sterility, attachment apparatus, and probing. It is so important for hygienists to be continually updated about implants. There are a variety of opinions regarding whether implants should be probed, but all agree that they should only be probed with plastic probes. Probing, while using pressure-sensitive probes is considered safe around implants. This light pressure is needed to avoid damage to the delicate fibers that surround the implant. The best option is to probe initially at the time of the first restorative maintenance visit and thereafter only if problems arose. However, a current recommendation is to probe initially, and then yearly, but only on the buccal and lingual surfaces. Radiographs can be taken to see the mesial and distal aspects of the implants. But since radiographs are a two-dimensional view of a three-dimensional area, the buccal and lingual areas are indistinguishable (Oh et al., 2002). Probing once a year can reveal any problems that could lead to loss of osseointegration. However, prior to each measurement, the probe should be dipped into chlorhexidine solution to prevent bacterial cross-contamination. Depending on the type of abutment present - either straight or angled - the depth of the perimucosal seal may be two to three millimeters, or as much as five millimeters, but still healthy- The hygienist needs to know baseline measurements, to be able to distinguish health from disease, or loss of osseointegration. References Axelsson P., Paulander J., Lindhe J. (1998). Relationship between smoking and dental status in 35-, 50-, 65-, and 75-year-old individuals. Journal of Clinical Periodontology, 25, 297-305. Berglundh T., Persson L., Klinge B. (2002). A systematic review of the incidence of biological and technical complications in implant dentistry reported in prospective longitudinal studies of at least 5 years. Journal of Clinical Periodontology, 29 (3), 197-212. Dental Implant Information (2006) The University of Iowa College of Dentistry. Retrieved on July, 16 from http://www.dentistry.uiowa.edu/public/oral/implant.html Fiorellini J., Martuscelli G., Weber H. (2000). Longitudinal studies of implant systems. Periodontology, 17, 125-131. Hedia, H. S.; Mahmoud, N. (2004) Design optimization of functionally graded dental implant. Bio-Medical Materials & Engineering, 14 (2), 133-143 Lindhe J., Lang N., Karring T. (2003). Clinical Periodontology and Implant Dentistry. 4th Ed. Blackwell Publishing. Oh T., Yoon J, Misch C., Wang H. (2002). The causes of early implant bone loss: myth or science Journal of Periodontology, 73, 322-333. Read More