Factors influencing the survival of dental implants - A review

Diabetes

Distinctive nature is high blood glucose levels

In longrun proinlammatory cytokines and mediators are released like TNF alpha, IL 6 that rise and bringdown osteoblast- osteoclast coupling which are two essential cells for implant osseointegration.

In the same way diabetes also act on the ratio of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegrin (OPG), prime regulators of osteoclast function.

In cases of hyperglycemia, this ratio is destroyed and accentuates bone resorption

Eventually, these patients are liable to both systemic and localized infections, and thus are at a danger for osseointegration collapse due to infection. ^[17]

Altogether, these changes could be a reason for a probable cause for implant failure in diabetic patients.

Therefore, diabetic control is estimated by determining the levels of glycosylated hemoglobin, hemoglobin A1c (HbA1c). Infact, dental measures exist for patients with uncontrolled diabetes, and most clinicians limit their positioning of dental implants, as well as non emergency surgical procedures, in patients with uncontrolled diabetes.

One study explored osseointegration rates in patients with uncontrolled diabetes and found no distiction in patients with high or low HbA1c. ^[18]

Another study that involved 23 patients with HbA1c from 6 to 13.9 who had a sum of 70 implants placed found no distinction in osseointegration among groups.^[19]

In both studies, implant existence rates were comparable, with no statistical differences among groups. However, with low sample sizes, it is tough to draw up definite opinion for implants in patients with poorly controlled diabetes.

Osseointegration rates in all groups were similar, with no statistically remarkable differences

Although these outcomes are inspiring for osseointegration and short-term implant survival, marginal bone loss and longlasting implant survival may be affected by diabetic status; this focuses the need to closely escort these patients for conservation and potential problems.

Osteoporosis

Since osteoporosis is a disorder of reduced bone mass, increased bone delicacy, and prone to fracture, the thin cortical bone and enlarged trabecular spacing is thought to impart higher implant failure.

Mostly seen in postmenopausal women on hormone replacement therapy, particularly in the less dense maxillary(type IV) bone. ^[20], ^[21]

Osteoporosis treatment usually incorpotrates an antiresorptive medication such as a bisphosphonate (BP) or denosumab (Dmab).

Both BPs and Dmab hamper osteoclast differentiation and function, contributing to decreased bone resorption and remodeling.

. But, most studies have failed to show a adverse effect on implant osseointegration or survival after BP therapy, osteonecrosis of the jaw (ONJ) and alveolar bone loss have been described after dental implant placement. ^[22], ^[23]

With the likely destructing effects of ONJ, accepted treatment guidelines should be followed, including avoiding non emergency positioning of dental implants in patients on antiresorptive therapy for malignancies and utilizing a drug holiday and a thorough informed consent in patients on antiresorptives for osteoporosis.^[20]

Human Immunodeficiency Virus

The lONGIVITY for people existing with HIV has increased over the past two decades

Numerous individuals who are HIV-positive survive much longer, healthy lives

As a matter of fact, the regular causes of illness and death in people surving with HIV are alike to those of non-HIV patients that involve heart disease, kidney disease, liver disease, diabetes, depression, and cancer.

However, there is a practical association between HIV-positive individuals and bone metabolic alterations

Rationale for this are low calcium/vitamin D intake, low testosterone, alcohol and opiate abuse, smoking, depression, physical inactivity, and HAART. ^[24]

To date, there is little evidence of the effect of HIV, and more specifically HAART therapy, on osseointegration and long-term success and survival of dental implants.^[25]

Nevertheless, the authors inferred that prophylactic antibiotic treatment, the administration of highly active antiretroviral therapy, and control of the CD4+ T lymphocyte counts were solution in the effective treatment of these groups of patients

Cardiovascular Disease and Antihypertensive Medications

In reality, heart disease is the chief cause of deceased for both men and women, and coronary heart disease is the frequent type, killing over 370,000 people annually.^[26]

Of the different forms of cardiovascular disease, hypertension, atherosclerosis, vascular stenosis, coronary artery disease, and congestive heart failure have the most direct effect on peripheral blood supply.

This will lead to deficient oxygen supply to local tissues, reduced fibroblast activity, collagen formation, capillary growth, and macrophage activity which will have direct effect on bone healing and osseointegration. ^[27]

In a retrospective study analyzing nearly 7,000 implants, Alsaadi and coworkers analyzed the impact of local and systemic factors on the incidence of oral implant failures, up to abutment connection. ^[28]

They concluded that certain factors, such as cardiac diseases, coagulation problems, hypertension, or hypercholesterolemia, did not lead to an increased incidence of early failures. ^[29]

Neurologic Disorders

From ancient times, patients experiencing neurologic diseases have been eliminated from receiving dental implants

The primary rationalization for the exclusion has been the association with poor approach to oral health care, poor oral hygiene, oral parafunctions such as bruxism, harmful habits, and behavioral problems.

Newer technology and improvements in medicine have permitted for enhancement in patient care and personal satisfaction, including patients suffering from neurologic disorders.

This improvement in patients’ emotional and social well-being has been a key factor in the reinstitution of dental implants, allowing them to work alike to their natural teeth.

Unfortunately, there is limited documentation to contribute the use of dental implants in patients affected by neurologic disorders.

In a prospective study, Ekfeldt et al ^[30] evaluated the medium- to long-term outcome of dental implant therapy in patients with neurologic disabilities.

Twenty-seven patients with different disabilities and in need of prosthodontic treatment were treated with various implant-supported prostheses.

Nonetheless, the authors concluded that implant therapy can be a valid option for the rehabilitation of patients with neurologic disabilities.

Hypothyroidism

Hypothyroidism is a familiar endocrine disorder, most commonly affecting women of advanced age

As many organs have receptors for thyroid hormone, its inadequacy impedes withvast number of the body’s metabolic processes.

In addition to controlling temperature, generalized energy, metabolism, skin moisture, gastrointestinal motility, muscle metabolism, mental and memory ability, libido, and menstrual cycle, thyroid hormone affects bone metabolism. ^[31], ^[32]

Thyroid hormone regulates adult bone mass and revives production of insulin-like growth factor-1 (IGF-1), which rises osteoblast formation and differentiation, and bone remodeling. ^[33], ^[34]

For bone metabolism, hypothyroidism has been associated with RETARDED bone regeneration, proliferates fracture risk, and retards fracture repair. ^[35], ^[36]

Treatment hypothyroidism, including long-term levothyroxine, has correlation with accentuated risk for osteoporosis and late fracture recovery in animal studies, making the condition and its therapy a cause for concern in patients seeking dental implants. ^[34]

Studies that have investigated implant survival in patients with hypothyroidism did not demonstrate a significantly higher rate of implant failures as compared to control patients. ^[37], ^[38]

Rheumatoid Arthritis

RA is an autoimmune disease in which the body’s immune system produces inflammation that leads the synovium to stiffen, developing inflammation edema and pain in and around the joints, gradually destructingthe bone itself.

RA is usually followed by osteoporosis as a result of increased systemic bone turnover and anti-inflammatory and/or combined anti-immune treatment regimens.

Although the etiology of RA is idiopathic, there is documentation that genetics, hormones, and environmental factors are involved in the process.

Genes associated to RA include: STAT4, a gene that plays important roles in the controlling and renewing of the immune system; TRAF1 and C5, two genes relevant to chronic inflammation; and PTPN22, a gene associated with both the development and progression of RA.

iIndividuals with RA with or without concomitant corticosteroid treatment will develop localized osteopenia and generalized osteoporosis in 30% to 50% of all cases.

But, there is scanty documentation on the effect of RA on osseointegration and dental implant outcomes.^[39]

In a case series, Weinlander et al ^[40] evaluated implant and prosthodontic treatment outcomes of patients suffering from rheumatic disorders such as RA and connective tissue diseases (CTDs).

The authors concluded that a high implant and prosthodontic success rate can be anticipated, even for patients suffering from autoimmune rheumatic disorders such as RA and CTDs. ^[41]

Selective Serotonin Reuptake Inhibitors

Usually adviced antidepressants that accentuates levels of serotonin in brain

They stop the uptake of 5HT by inhibiting 5^HT transporter

Recent studies have shown a wider role for the SSRIs, as 5-HT plays an active role in numerous pathways including that of bone metabolism. ^[42]

The results of this study suggested that SSRIs may lead to an increase in the rate of osseointegration failure, although not reaching statistical significance.

Proton Pump Inhibitors

1. They are employed for the elimination and therapy of acid-related conditions such as esophageal, duodenal, and stomach ulcers; NSAID-associated ulcer; gastroesophageal reflux disease (GERD); and Zollinger-Ellison syndrome.

2. They are used together with antibiotics for preventing Helicobacter pylori, a bacterium in combination with acid results ulcers of the stomach and duodenum.

3. longterm use of PPIs could have potential adverse effects, due to the effect of chronic acid suppression on the absorption of vitamins and nutrients. Gastric acid secretion can affect the absorption of a number of nutrients, drugs, and vitamins, particularly Vitamin B12, iron, calcium, and magnesium.

4. Recent studies showed a possible association between chronic PPI use and increase in bone fractures, possibly by decreasing calcium absorption. ^[43]

5. The most widely assumed mechanism is that long-term PPI use leads to decreased intestinal absorption of calcium, resulting in negative calcium balance, increased osteoporosis, development of secondary hyperparathyroidism, increased bone loss, and increased fractures.

6. Even though evidence exists on the negative effects of PPIs on bone, there is little evidence on their effect on osseointegration and dental implants.

7. Statistical analysis revealed that the failure rates were 6.8% for people using PPIs compared to 3.2% for nonusers. ^[42]

8. In their conclusions, the authors also suggested that the intake of PPIs may be associated with an increased risk of dental implant failure.