Introduction
Oral implants have been utilized with full effect for many years to replace missing teeth that are lost due to diseases or extracted. Also, there has been a growing concern regarding peri-implant diseases recently. There are so many factors that contribute to the emergence and progression of peri-implant diseases which were identified after numerous studies The impact of smoking on the healing of peri-implant bone and its association with peri-implantitis is also studied in ongoing research. The research findings point out that smoking plays an important role as a risk factor for the development of peri-implantitis and eventual implant failure.
What Is Peri-Implantitis?
Peri-implantitis is a disease linked to plaque accumulation, which arises within the tissues surrounding dental implants. It presents clinically as an inflammation in the mucosal area surrounding the implant, leading to a reduction in the supporting bone. Sites affected by peri-implantitis display evident clinical signs of inflammation, such as bleeding when probed, discharge of pus, increased depths upon probing, and recession of the mucosal edge. Also, there will be observable radiographic evidence of bone loss when compared to prior assessments. Notably, peri-implantitis lesions extend beyond the junctional or pocket epithelium and can be larger in size compared to those observed in cases of peri-implant mucositis and periodontitis.
What Is the Prevalence Rate of Peri-Implantitis?
The development of mucosal inflammation in the oral soft tissue around a dental implant without losing the underlying support bone is called peri-implant disease. If left untreated or without follow-up in dental implant patients, especially with systemic factors involved, the possibility of dental implant failure over the long term may exist, and implant instability, infection, or prosthetic fractures occurs due to biological or mechanical failure of the dental implant.
Following are a few common factors that are associated with the increased prevalence of peri-implant infections:
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Alteration of the oral microbiome associated with gingival and periodontal irritation in the oral cavity.
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Cigarette smoking.
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Poor oral hygiene.
As mentioned in implant literature, the prevalence rates of peri-implantitis are high within three years of the dental implant. Calculus and debris that further develops at the implant site aggravate with an accelerated pattern over nine to ten years after implant placement in subjects.
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By analysis in implant literature, over the recent decades, the prevalence of peri-implant tissue inflammation globally ranges between 19 to 65 % (implant soft tissue inflammation), while peri-implantitis or peri-implant diseases causing implant failure ranges from around 1 % to approximately around 47 %.
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Collectively, it remains a common condition on a worldwide scale affecting the prognosis of dental implants. Published case reports depict systemic, local, iatrogenic and genetic risk factors associated with implant failure.
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There are marked differences in global risk assessment, which may also be due to the varying definitions or criteria adopted to judge the success rates of dental implants and the clinical inflammation or mobility observed by implant dentists. Clinical assessment is done by observation of clinical soft tissue inflammation around the dental implant with two millimeters of crestal bone loss. For example, most dental operators or clinicians follow the baseline radiographs with a presence of clinical inflammation with crestal bone loss of 1 to 1.5 millimeters as peri-implantitis.
What Are the Common Risk Factors for Peri-Implant Disease?
The iatrogenic factors include:
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Improper implant positioning.
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Excess cement deposition during prosthetic cementation.
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Lack of cleaning ability around an implant restoration.
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Systemic or local risk factors also affect the primary stability of a dental implant.
These factors mentioned above render either biological or mechanical failure of the dental implant. Following are a few other factors that influence dental implant success, mainly post-dental implantation being:
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Supportive maintenance care and regular six monthly to yearly dental follow-ups with implant dentists.
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Surface characteristics of the dental implant placed.
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Patients' individual oral hygiene maintenance and status.
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Prosthetic structure functionalities.
The genetic factors that may predispose an individual to develop a peri-implant disease that may lead to long-term dental implant failure, the genes in which polymorphisms have been evaluated, are associated with the malfunctioning of implants. Following are the genetic factors associated with implant failure. It is categorized into three types :
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Genes associated with individual immune function.
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Genes associated with bone growth.
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Genes associated with the regulation or regulatory expression of genes.
What Are the Gene Expression Changes Causing Peri-Implant Disease?
The cause of any of these gene polymorphisms though exactly not known, is mainly linked with cytokine molecules released. Cytokines are small signaling molecules mainly associated with carrying out functions of the immune system and are responsible for intercellular mediation or communication in the host.
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The interleukin family of immune cells is constituted of cytokines and has a similar pro-inflammatory mode of action. When these cytokines or interleukins are overproduced due to the polymorphisms encountered in genes, they would be held responsible for causing severe soft tissue lesions or impacting a negative alteration of the normal healing response of the individual's soft tissues.
The pathogenesis would be attributed to the hypothesis considered by dental researchers as follows :
The proinflammatory cytokines cause an upregulation or expression of several other molecules like TNF alpha (tumor necrosis factor-alpha), nuclear factor-K beta, or osteoprotegerin, all of which mediate bone resorption. This explains why dental implants would also be a potential failure in some individuals with predisposing genetic factors. Research also observed that they are due to genetic polymorphisms and gene regulatory defects. In smokers, these same signaling molecules, like TNF alpha, interleukins, etc., stimulate bone resorption. Therefore, dental implant failure is common in regular smokers. Recent research reports in the last decade have also shed light upon specific polymorphisms in these genes, namely,
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The MMP13 collagenase.
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TIMP 2 tissue inhibitor of metalloproteinases.
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The transforming growth factor or TGF beta 3.
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BMP 4 (bone morphogenetic protein 4).
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BRINP 3 (bone morphogenetic protein retinoic acid inducible neural specific 3).
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FGF (fibroblast growth factor 3).
Conclusion:
The etiology of peri-implant soft tissue inflammation is complex, with research now identifying several potential genetic biomarkers in individuals that can predispose an individual to implant failure. It happens due to poor soft tissue healing and the negative impact on implant-bone fusion. Individuals with genetic risk factors or polymorphisms can be helped by dental clinicians who can choose alternative prosthetic rehabilitation instead.
