Review Article Biology and Medicine, 3 (2) Special Issue: 164-170, 2011 eISSN: 09748369, www.biolmedonline.com Biological factors responsible for failure of osseointegration in oral implants *Hadi SA1, Ashfaq N2, Bey A2, Khan S2 1Postgraduate Student, Postgraduate Certificate in Oral Implantology-2010, IGNOU, India. 2Department of Periodontics and Community Dentistry, Dr. Z.A. Dental College and Hospital, A.M.U., Aligarh, India. *Corresponding Author: [email protected] Abstract Oral implantology (implant dentistry) is the science and discipline concerned with the diagnosis, design, insertion, restoration, and/or management of alloplastic or autogenous oral structure to restore the loss of contour, comfort, function, esthetic, speech, and/or health of the partially or completely edentulous patient. Osseointegration, a term coined by Branemark and co-workers in early 1960s, represents a direct connection between bone and implant without interposed soft tissue layers. The aim of the present review is to discuss various factors responsible for loss of oral implants. The factors contributing to failure of osseointegration have been identified as medical status of the patient, smoking, bone quality, bone grafting, irradiation, bacterial contamination, lack of preoperative antibiotics, degree of surgical trauma, and operator experience. Furthermore, it appears that implant surface properties, roughness and premature loading influence the failure pattern. Keywords: Implants; Osseointegration; Failure; Alloplast. Introduction achieve osseointegration following placement. Dental implants are inert, alloplastic materials Using a meta-analysis, failure rates for embedded in the maxilla and/or mandible for Branemark dental implants were 7.7% the management of tooth loss and to aid (excluding bone grafts) over five years. replacement of lost orofacial structures as a Interestingly, failure rates within edentulous result of trauma, neoplasia and congenital patients were almost double those for partially defects. The most common type of dental dentate patients (7.6% versus 3.8%). implant is endosseous comprising a discrete, single implant unit (screw- or cylinder-shaped Implant complications and failure are the most typical forms) placed within a A multifactorial background for implant drilled space within dentoalveolar or basal complications and failure has been extensively bone. They implants have become an reviewed by Esposito and co-workers (1998). important therapeutic modality in the last Factors affecting early failure of dental decade, mainly after the works developed by implants may be broadly classified as: implant- Brånemark (1960s), in which the direct contact , patient- and surgical technique/environment- between the bone functional tissues and the related (Table I). Three major etiologic factors biomaterial titanium was termed have been suggested: osseointegration. 1. Infection: Bacterial infection that leads to Success and failure implant failures can occur at any time Albrektsson (1986) proposed the criteria for during implant treatment. Several terms are successful integration of dental implants have currently used indicating failing implants or been. Of these, a lack of mobility is of prime complications. These are: peri-implant importance as ‘loosening’ isthe most often disease, peri-implant mucositis, and peri- cited reason for implant fixture removal. Adell implantitis. Peri-implant disease is a (1981) reported the success rate of 895 collective term for inflammatory reactions in implant fixtures over an observational period of the soft tissues surrounding implants. Peri- 5 years after placement. Eighty-one per cent of implant mucositis is a term describing maxillary and 91% of mandibular implants reversible inflammatory reactions in the soft remained stable. tissue surrounding implants. Other soft Despite high success rates, implant tissue complications (hyperplasticmucositis, fixture failure may occur and is defined as ‘the fistulations and mucosal abscess) seem inadequacy of the host tissue to establish or mainly to have an infectious etiology. maintain osseointegration. One review (Adell, Fistulations and hyperplastic mucositis are 1990) suggested that 2% of implants failed to often found in relation to loose prosthetic 164 MAASCON-1 (Oct 23-24, 2010): “Frontiers in Life Sciences: Basic and Applied” Review Article Biology and Medicine, 3 (2) Special Issue: 164-170, 2011 components. Abscesses can occasionally Medical status be seen in relation to food particles trapped in the peri-implant crevice. a) Diabetes Diabetic patients experience delayed wound 2. Impaired healing: It is believed that the healing, which logically affects the magnitude of the surgical trauma (lack of osseointegration process. Uncontrolled irrigation and overheating), micromotion diabetes has been shown to inhibit and some local and systemic osseointegration and leads to implant failure. characteristics of the host play a major role Fiorellini et al (2001) demonstrated a lower in implant failures related to impaired success rate of only 85% in diabetic patients, healing. while Olson et al (2000) found that the duration of the diabetes had an effect on implant 3. Overload: Implant failures related to success: more failures occurred in patients overload include those situations in which who had diabetes for longer periods. Fiorellini the functional load applied to the implants et al (2001) also observed that most failures in exceeds the capacity of the bone to diabetic patients occurred in the first year after withstand it. Failures that happen between implant loading. Special review programs and abutment connection and delivery of the contingency plans are prudent commitments in prosthesis, probably caused by the treatment planning for this category of unfavourable loading conditions or induced patients. by the prosthetic procedure, considered to have an overload etiology. Other attributes b) Cigarette smoking to implant failures are poor surgical The adverse effects of cigarette smoking on technique, poor bone quality and poor implant treatment are well documented. A prosthesis design in addition to the longitudinal study by Lambert et al (2000) traumatic loading conditions. found more failures in patients who smoked, and Bain and Moy (1993) observed that a Esposito et al (1999) defined biological significantly greater percentage of failures failures related to biological process, and implant occurred in smokers (11.3%) than in mechanical failures related to fractures of non-smokers (4.8%). The difference was components and prostheses. Koutsonikos highly significant for implants placed in all (1998) added the categories of iatrogenic regions of the jaws, with the exception of the failure and failure due to patient adaptation. El posterior mandible. Several retrospective Askary et al (1999) further defined failure as short-term studies in different populations and ailing, failing, or failed implants. This article with different implant systems have been provides an overview of the important published demonstrating similar results. Kan et biological factors that affect osseointegration al (1999) reported that smoking also affects and thus lead to loss of implant. implants in the grafted maxillary sinuses. Cigarette smoking is associated with Patient factors significantly higher levels of marginal bone Patient factors are important determinants of loss, and the effect of smoking status on the implant failure. Ekfeldt et al (2001) identified hard and soft peri-implant tissues has been the patient risk factors leading to multiple clearly shown. Lemons et al (1997) further implant failures and concluded that a showed that smoking reduced bone density in combination of several medical situations the femur and vertebrae as well as in the could provide a contraindication to implant jawbone. treatment. Hutton et al (1995) showed that The short-term benefits of a smoking subjects with one implant failure would be cessation protocol suggested by Bain (1993) likely to have others, and Weyant (1994) further explained the causal relationship stated that a positive medical history is between smoking and implant failure. The associated with an increase in implant loss. protocol specifies complete smoking cessation Weyant and Burt (1993) observed a 30% for 1 week before and 8 weeks after surgery. increase in the probability of removal of a The results indicated that the smokers who second implant in patients with multiple complied with the cessation protocol displayed implants presenting with one failure. This short-term implant failure rates similar to non- evidence indicates that implant failures are not smokers, and significantly lower than smokers randomly distributed in the population, but who did not follow the protocol. Although the seem to occur in a small subset of individuals. meta-analysis published by Bain et al (1993) concluded that patients who smoked fewer than 12 cigarettes per day did not significantly 165 MAASCON-1 (Oct 23-24, 2010): “Frontiers in Life Sciences: Basic and Applied” Review Article Biology and Medicine, 3 (2) Special Issue: 164-170, 2011 affect implant osseointegration, the adverse studies should not be ignored. effects mentioned by the previous mentioned Table I. Factors related to the failure of dental implants. Factor Comments Implant Previous failure Surface roughness Surface purity and sterility Fit discrepancies Intra-oral exposure time Mechanical Premature loading overloading Traumatic occlusion due to inadequate