Factors Contributing to Implant Failure - Case Study Example

Factors Contributing to Implant Failure Introduction Implant in the fieldof dental prosthetics is given to patients suffering from complete or partial edentulism. This form of oral implantation is quite common in modern day dental surgery and forms a reliable treatment modality with high percentage of success rates. Rates of implant failure though fairly uncommon, do happen from time to time. A detailed study into the various factors that are likely to contribute to the implant failure is necessary to put a cap over the failure rates. This article reviews the various causative factors like local factors, technical factors, patient factors, and iatrogenic factors, and also takes a deep insight into the various types of implant failures. The main objective of this article is to explore the various causal factors of implant failure so that a repetition can be avoided in the future and success rates increased in this field. Body What is dental implant? A tooth in natural condition is made up of two major parts. The upper part of the tooth that can be seen above the gum line forms the crown while the anchor that remains below the gum line forms the root. When this tooth is missing completely or is partially broken due to decay or damage, a metal device is so designed that it can replace the root and a prosthetic tooth is prepared to replace the crown above. The process involves the opening of the gum tissue where the bone tissue below it are exposed to drill in the implant. Once the bone tissues are prepared and the implant placed, the tissues are sutured up and the entire healing process takes around six months. Once the osseointegration is over and the surgical sutures removed, the porcelian crown made with aluminium abetments are cemented over the implant, thus completing the procedure. Types of dental implants : There are various types of implants in use. The two main types are the fibriointegrated implant (includes the older versions of blade implant and subperiosteal implant) and the osseointegrated implant. Of the two the osseintegrated implant is the more popular one in which titanium is used as implants, as it fuses well with the dental bones and poses zero risk as the osteoblasts gradually grow over the implants. In case of complete edentulism a different type of procedure is used in which an implant-supported bridge is formed to replace the missing teeth. Failure of Dental Implants: Failure of dental implants mostly relates to failure of the implant to osseointegrate. As Albrektsson et al. defined osseointegration, “direct functional and structural connection between living bone and the surface of a load- bearing implant” (AlBrektsson et al., 155-170). However, failure of dental implants also implies if lost, moved or if peri-implantitis (inflammation) occurs around the region. There are many causal factors that lead to such failures. According to Manor et al., “Primary predictors of implant failure are poor bone quality, chronic periodontitis, systemic diseases, smoking, advanced age, implant location, parafunctional habits, loss of implant integration, and inappropriate prosthesis”(Manor et al, 2649). Esposito et al. in their research paper defined biological failures that are caused by certain biological factors and processes, while mechanical failures are related to componential breakage or fractures (Esposito et al., 527-51). There are other factors too that may cause failure of implants, such as the patient may for some reason fail to adapt to the new foreign body or there may also be certain iatrogenic failures. As Bornstein et al tell from their extensive research on implants that, “increased failure rates have to be expected in patients exhibiting risk factors such as systemic diseases, heavy smoking, increased periodontal susceptibility, and anatomic factors such as poor bone density or extreme atrophy…”(Bornstein et al., 1114). Types of dental implant failures: Dental failures are primarily of two types- early failures and late failures, based on the timing of the implant failure. Early failures occur, because of the healing process after dental implantation somehow does not occur and so there is no osseointegration at all, while late failures occur sometime later, after the osseointegration has started which somehow is arrested and stops without completion. It is suggested that the process of osseointegration remains incomplete in later implants, because of a breakdown procedure (cef. Alssadi G, Quiryen M, Komerek A, Van Steenberghe D, 610). Manor et al. conducted various experiments and clinical studies on 194 patients who had dental implant failures within the first six years (2000- 2006), of these 98 were men and 96 female patients. They came to the conclusion that around 73.2 % with early failures showed no osseointegration. Late failures comprised of overloading which comprised about 46.4% cases, peri-implantitis comprising of about 32% while implant breakage comprised of only 6.2%. Their experiments also proved that younger females who all were healthy showed earlier implant failures while older males with various medical problems had a tendency of late implant failures, and characteristically showed more implant failures in the posterior region (cef. Manor et al., p. 2650). Fig: 1 A dental implant failure (cef. Dental Health Directory, Bad Teeth: dental implant failure) Factors contributing to implant failure: There are many factors that may cause the dental implant in a patient to be a failure. These are, certain patient factors, local factors, technical factors and iatrogenic factors that may affect osseointegration, leading to implant failure. Patient factors Medical conditions- It has been observed that certain medical conditions seen in patients cause more failures. Hutton et al from his clinical observations concluded that a patient with one implant failure will in probability show more failures (cef. Hutton et al., 42) while Weyant and Burt observed that, a patient with multiple implants run the risk of having a second implant failure if he is already diagnosed with one failure (cef. Weyant and Burt, 2- 8). Other researchers have also come to with more or less the same conclusion, that patients with medical histories are more prone to failures, thus giving rise to the theory that dental implant failure does not occur randomly amongst all patients, but takes place only in a select few with certain medical conditions. Alsadi et al. came to the conclusion after conducting many experiments that “cardiac and gastric diseases, controlled diabetes type II, coagulation problems, hypertension, hypo- or hyperthyroidism…..did not lead to an increased incidence of the early failures. Crohn’s disease and osteoporosis, in contrast were significantly related to implant failures”( cef. Alssadi G, Quiryen M, Komerek A, Van Steenberghe D, 613). Uncontrolled diabetic conditions are also known to cause dental implant failures. In diabetes healing of wounds take a long time, which in turn affects the process of osseointegration, by inhibiting it, thus leading to implant failure. Olson et al observed in their clinical findings that patients with a long history of diabetes were more likely to show implant failures, thus giving the idea that duration of diabetes may be a causal factor for failure of dental implants (Olson et al., 811-8). It has also been observed by Fiorellini et al that most implant failures seen in diabetic patients occur during the first year itself (Fiorellini et al., 366-73). Thus treating diabetic patients for implants will have to be handled with care and reviews to be made, and there should be an exigency plan in place. Cigarette smoking – It has been proven many times by various researchers that smoking adversely affects dental implants leading to a high rate of failure. Lambert et al. in their longitudinal study found that patients who smoked showed more implant failures (Lambert et al., p. 79-89). There is quite a large amount of marginal bone loss in smokers while Lemons et al. in their experiments have effectively proven that there is significant decrease in the bone density of the vertebral column, jawbone and the femur, in smokers (Lemons et al., S72-5). It has also been seen that if a patient stops smoking for a certain period before and after the implant surgery, percentage of implant failures drops significantly, almost compatible to the rates shown by non-smokers. Age- Age does not show much co relation with implant failure, though it is of general knowledge that health deteriorates with age. Though certain results from experiments by Salonen et al. propose that old age may be a contributing factor to implant failures (Salonen et al., p. 92- 7) but no conclusive co-relation between the two has been established until date. Local factors Quality of bones at the site of implant- This is a very important factor for the success of the implant. Low density and quantity of bones, account for a high percentage of implant failures. It has been reported by Jaffin and Berman in their five-year long observations that almost 35% of dental implant failures are reported from patients with bones showing weak medullary strength, poor trabecular density and thin cortex (Jaffin and Berman, p. 2- 4). These bone characteristics are categorized as the bone type IV and are very hard to diagnose, as a lingual plate even during periapical radiography may hide the internal weakness of the bone. Osteoporosis is also often considered as major factor for causing dental implant failure. However, osteoporosis seen at one location of the body may not necessarily mean that dental bones are affected. As Dao et al suggests that instead of systemic bone density it the nature of the local bone density that is a more likely factor for implant failure (Dao et al, p. 137-44). Peri-implantitis- This is a condition which accounts for almost 50% of all the implant failures during the first year of the implant loading. Peri implantitis is a chronic condition in which there is inflammation round the tissues surrounding the dental implant leading to destruction of the bones that support the implant. It ultimately leads to implant failure. The exact cause of peri-implantitis is still unknown though it is often surmised that normal plaque formation may lead to accumulation of bacteria around the site of dental implant leading to inflammation. In their experiments, Apse et al found that there were increased levels of gram-negative bacteria in patients showing signs of peri-implantitis (Apse et al, 96- 105). This condition can be treated by antiseptic and antibiotic medicines, resective treatment and also mechanical debridement. Dental implant site location- Since the maxillae has bones that are of a poor quality, the implants located at the maxillary region tend to show more failure when compared to the mandibular implants. The implants located at the latter position also tend to survive for a longer period than the ones located at the former position. Irradiated bone- Implants are used as prostheses during craniofacial surgeries and radiotherapy is also used to treat bone cancer in those locations. For such previously irradiated dental patients, adjunctive hyperbaric oxygen (HBO) therapy can be used. Granstorm et al. in their researches found out that around 58% of cases reported failure when not using HBO therapy, while those using the therapy reported only about 2.6% failure rate. They also showed that in irradiated bones, HBO therapy helped to reduce implant failure rate (Granstorm et al., 15-25). Technical factors Variations in implant system may affect the failure rate though nothing has been proven conclusively until date. Lengths of dental implants also affect the success rates of implant survival and it is said the longer the implant, the more area of osseointegration, thus better chances of survival. Researches by Winkler et al. conclusively prove that longer implant lengths have better survival chances when compared to shorter implants which in general report more failures (Winkler et al., 22-31). The reasons may be that in, shorter implants there are chances of mechanical overloading and also a quicker succumbing to peri-implantitis. Dental implants have screws that are retained within them. However, these screws often create problems by becoming loose, and in such conditions, tightening becomes necessary to keep the implants in place. Loose screws are dependent on the framework fitting of the implant and also on handiwork of the person who is doing the implant. Implant fractures though rarely seen may happen due to mechanical overloading, or due to the presence of cytotoxic nickel ions coming out from the supra structure. Iatrogenic factors Implant positioning is an important factor in implant failure statistics. This is because wrong placing of an implant would serve to curb the creation of the supra structure of an implant. Those that were placed too near or too far away from the esthetic region invariably resulted in the failure of the dental implant. Another very important iatrogenic factor for failure is when the bones become overheated during surgery. When bones are heated to a temperature of 47 degree Celsius, even for a minute, it may lead to bone necrosis. To avoid this Brisman recommended the use of a high load and high-speed hand piece to avoid high heat and more efficient cutting (Brisman, 35-7). There are many teams that work together to produce an implant and the whole process is multidisciplinary. Beginning with checking and assessing the patient for possible medical histories, moving through various laboratory processes that manufacture the prostheses, to the final treatment and placement of the implant and prostheses, all the different teams play an important part that count together for the success of the implant. Tolman and Laney in their article have placed importance in the fact that many implant failures have arisen from the fact that patients were wrongly diagnosed, the treatment given to patients were of inferior quality and they were miscommunications or a total lack of communication between the various team members working together (Tolman and Laney, 477-84). Conclusion Factors causing dental implant failures are many and varied. A failure may occur due to one factor or it may be the culmination of many factors working together. One of the best ways to avoid such failures is to assess and correctly diagnose the patient. A patient’s medical history is of primary importance to check for medial factors and other local factors that are probable causes for an implant failure. The dentist who is handling the implant should conduct the entire treatment process with utmost care, to rule out possible iatrogenic factors. As further researches are being conducted into the failures, there are chances of having a low failure rate in the future. The better we understand the causative agents that lead to a failure, the better precautions we can take to avoid such failures, leading to a better and an advanced medical care. Works Cited AlBrektsson, T, Branemark, P and Lindstrom, J. Osseointegrated Titanium Implants. Requirements ensuring a long lasting, direct bone-to- implant anchorage in man. Acta orthop Scend 1981; 52: 155-170. Alssadi G, Quiryen M, Komerek A and Van Steenberghe D. Impact of local and systemic factors on the incidence of implant failure, upto abutment connection with modified surface oral implants. J Clin Periodontol 3, 2007; 34: 610-617. Apse P, Ellen RP, Overall CM, Zarb GA. Microbiota and crevicular fluid collagenase activity in the osseointegrated dental implant sulcus: a comparison of sites in edentulous and partially edentulous patients. J Periodontal Res 1989;24:96-105. Bornstein, M. et al. A Retospective Analysis of Patiemts Referred for Implant Placement to a Specilaity Clinic: Indications, Surgial Procedures, and Early Failures. The international Journal of oral and maxillofacial implants. Volume 23. Number 6. 2008. Brisman DL. The effect of speed, pressure, and time on bone temperature during the drilling of implant sites. Int J Oral Maxillofac Implants 1996;11:35-7. Dao TT, Anderson JD, Zarb GA. Is osterporosis a risk factor for osseointegration of dental implants? Int J Oral Maxillofac Implants 1993;8:137-44. 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The excessive loss of Branemark fixtures in type IV bone: a 5-year analysis. J Periodontol 1991;62:2-4. Lambert PM, Morris HF, Ochi S. The influence of smoking on 3-year clinical success of osseointegrated dental implants. Ann Periodontol 2000;5:79-89. Lemons JE, Laskin DM, Roberts WE, et al. Changes in patient screening for a clinical study of dental implants after increased awareness of tobacco use as a risk factor. J Oral Maxillofac Surg 1997;55(12 Suppl 5):S72-5. Manor,Y. et al. Characteristics of Early Versus Late Implant Failure: A Retrospective Study. American Association of maxillofacial surgeons. J Oral Maxillofac Surg 2009;67: 2649- 2652. Olson JW, Shernoff AF, Tarlow JL, Colwell JA, Scheetz JP, Bingham SF. Dental endosseous implant assessments in a type 2 diabetic population: a prospective study. Int J Oral Maxillofac Implants 2000;15:811-8. Salonen MA, Oikarinen K, Virtanen K, Pernu H. Failures in the osseointegration of endosseous implants. Int J Oral Maxillofac Implants 1993;8:92-7. Tolman DE, Laney WR. Tissue-integrated prosthesis complications. Int J Oral Maxillofac Implants 1992;7:477-84. Weyant RJ, Burt BA. An assessment of survival rates and within patient clustering of failures for endosseous oral implants. J Dent Res 1993;72:2-8. Winkler S, Morris HF, Ochi S. Implant survival to 36 months as related to length and diameter. Ann Periodontol 2000;5:22-31. Read More