Physiology of Dental Implant Failure in Smokers

Introduction

According to the data statistics by the world health organization, in 2018, there were more than seven million people who are the victims of chronic tobacco smoking leading to significant systemic disease development and predisposing them to mortality every year. The dental implants primarily fuse to the alveolar bone by maintaining bone-implant contact through the phenomenon of osseointegration or fusion to the bone. This successful phenomenon determines the dental implants' long-term success rates.

The most common question that arises in people, whether they are addicted to smoking or it may be just another detrimental habit they possess, is whether dental implants are successful in these individuals or not? The answer based on the research and documented evidence accumulated through dental literature indicates that the upregulation of pro-inflammatory cytokines (cells present at the site of inflammation), especially interleukin-1, is responsible for aggravating localized tissue damage as well as alveolar bone resorption. These can be inflammatory reactions as well, due to which the smoker develops peri-implantitis or peri-implant mucositis that disturbs the functions of dental implant stability or anchorage. Hence it has been recognized as a significant factor for dental implant failure. This means that in chronic smokers, it can severely impact the localized peri-implant tissue of contact and the underlying alveolar bone, which would impede the effective osseointegration of the dental implant. Though smoking is a prevalent habit and behavior worldwide, the negative or detrimental effects are numerous concerning both oral and systemic health.

Which Are the Systemic and Oral Diseases for Which Smoking Is a Risk Factor?

The detrimental effects of smoking on general health in the long term that are linked to systemic diseases are given below. These systemic diseases in chronic smokers enlisted below do have the potential to interfere again in turn with the phenomenon of osseointegration and cause dental implant instability or failure in the long run. They are;

• Heart stroke or cardiovascular disease.

• Chronic obstructive pulmonary disease (COPD).

• Cancers.

  Related Topics

  ---

  History and Composition of Dental Implants

  Surgical Templates in Implant Dentistry

  Osseointegration: Science Behind Dental Implant Fusion

• Coronary heart disease.

• Low birth weight infants or stillbirth in the pregnant smoker.

• Pneumonia.

• Atherosclerosis.

In terms of detrimental impact on the oral tissues or in the oral cavity, smoking is a risk factor for the conditions given below;

• Periodontitis or periodontal disease.

• Oral cancers.

• Precancerous lesions of the oral cavity.

• Root caries.

• Delayed extraction site healing.

• Delayed oral wound healing.

• Taste derangement or alteration of taste sensation.

• Staining dental restorations.

• Staining of tooth enamel.

• Periimplantitis or periimplant mucositis.

According to the reviews of traditional medicine and dental literature in the field of implant dentistry, the exact mechanisms regarding the failure of dental implants in smokers remains elusive. However, there are several proposed hypotheses or mechanisms that are widely accepted by dental implantologists as to the mechanism of action through nicotine that renders implant failure.

What Is the Difference in Osseointegration Between a Non-smoker and a Smoker?

In a normal osseointegration phenomenon for a successful dental implant, the implant contacts the bone without deposition of any fibrous tissue. Also, this phenomenon is influenced by local oral factors such as the presence and functionality of the preosteoblasts that differentiate into osteoblast cells. The osteoblasts are, in fact, responsible for the secretion of the extracellular matrix that results in calcification between the bone-implant surface (BIC). The cells around successful dental implants exhibit anchorage, adhesion, proliferation, and differentiation into osteoblasts.

In smokers, there is primarily the formation of fibrous tissue that may be deposited at this interface between the bone and implant, forming a coagulum. In addition, the nicotine in tobacco or any cigarette product will usually release nitrosamine compounds, carbon dioxide, ammonia, aldehydes, benzene, etc., that correlates directly with bone resorption rendering the dental implant unstable primary anchorage in the bone. The negative impact of cigarette contents released is also due to the carbon monoxide element that acts as a potent inhibitor for oxygen. The red blood cells that carry oxygen are not only depleted of sufficient oxygen, but these compounds mentioned above inhibit enzyme systems in the oral cavity that is essential for normal oxidative metabolism (like hydrogen cyanide).

How Does Nicotine Cause Microvascular Constriction?

Nicotine has the detrimental ability to activate the voltage-gated calcium channels that regulate bone metabolism and fusion to the dental implant by severe changes in the intracellular calcium ion levels. The major effect studied in dental research is "the phenomenon of microvascular obstruction."

By the vasoconstrictive effect of nicotine exerted over the blood cells and the nutrients, ideally available at the bone-implant junction, interference is created due to reduction in blood flow as well as nutrients post-implant insertion. It is one of the reasons why dental implants would possibly fail at a very early stage, even in a few months in severe smokers. The evidence of the inhibition of immune T cells and B cells is also considered a bioactive factor for implant failure through peri-implant disease.

According to the evidence presented by the "human microbiome project," smokers developed an ecological succession of bacterial flora specific to peri-implant mucositis and peri-implant disease development that results eventually in "fibro-osseous" integration instead of "osseointegration."

Conclusion

Smoking is not a strict contraindication, but it is a risk factor for implant failure. When implant therapy is being considered, a person's smoking history should be gathered. This information should include how long the person has smoked, how much they have smoked in the past and how much they smoke now. Dentists should strongly advise smokers to give up smoking before undergoing any implant-related surgery or dental implantation, pointing out that smoking might raise problems and lower the success rate of these treatments. In high-risk scenarios, the clinician must determine whether or not to begin implant therapy; nonetheless, if treatment is chosen to begin, the patient's informed permission is required.