Impact of Systemic Diseases on Osseointegration

ABSTRACT

Implant based treatments are gaining popularity but also the challenges associated, like the complications due to surgery that interfere with the course of systemic disease.

There have been numerous success and failures in Implant Dentistry, comparison between studies is difficult pertaining to lack of homogeneity in patient systemic conditions. Most systemic contraindications are relative.

Since most of these patients need oral rehabilitation following implants, clinician should be completely aware of the implications of systemic diseases and evaluate both assets and liabilities.

INTRODUCTION

After a clinical breakthrough in oral rehabilitation with the Branemark’s serendipitous finding of Osseointegration, excellent results have been achieved in the edentulous areas. Though there have been numerous success and failures in Implant Dentistry, comparison between studies is difficult pertaining to lack of homogeneity in patient systemic conditions.

The authors either do not give enough insight into the occurrence and nature of the systemic factors among the patients involved or they exclude such patients. The question remains as to whether it compromises the bone-implant interface or its maintenance overtime. Implant based treatments are gaining popularity but also the challenges associated, like the complications due to surgery that interfere with the course of systemic disease.

AGE

Aging can be observed from the molecular to the body level. There is increase in molecular abnormalities and DNA Methylation. There is decrease of calcitonin and Vitamin D absorption and activation, which leads to Osteopenia or may be Osteomalacia. Because of increased pH of stomach fluid,there is decreased absorption of Ca2+ which may lead to Osteoporosis and Vitamin B12 deficiency.

At histologic level there is thinning of cortical bone and increased trabecular spacing, increased number of dead osteocytes. This leads to sclerotic bone,which is brittle.

Another factor is reduced vascular supply, which reduces oxygen tension, that is essential for bone apposition.

BONE FACTORS

Bone volume and bone quality are two factors of relevance when osseointegration is concerned. Radiographic investigations give assessment regarding the volume in two planes,lesser information about the quality. The quality may be assessed by vascularity, cellularity, biomechanical principles and bone turnover.

OSTEOMALACIA

Osteomalacia means a defective mineralization of the organic bone matrix i.e. collagen. In adults it is associated with vitamin D deficiency and alimentary deficiencies. Vitamin D deficiency reduces the intestinal uptake and mobilization if calcium from the bones, resulting in hypocalcemia. This leads to increase in parathyroid hormone (PTH),leading to decrease in concentration of phosphorous in bone fluids thereby preventing a normal mineralization process.

Radiographic findings reveal thnning of the cortices and a decreased density of the trabecular portion.

OSTEOPOROSIS

Osteoporosis can be defined as a reduced weight per volume unit of the bone, without a modified mineral to organic matrix ratio. It is a negative balance of bone remodelling which results in a decreased number and diameter of bone trabeculae and a thinner cortex. Radiologically, there is decreased density of inner part before thinning of cortices.

If the installation of endosseous implants is considered in the signs of osteoporosis,a treatment should be considered. Therapeutic approaches involve prscription of Biphosphonates and Calcitonin.

Biphosphonates such as Alendronate or Tiludronate in a dose of 10mg/day,are inhibitors of bone resorption and can efficiently increase the bone mineral density.

Calcitonin, a polypeptide inhibits bone resorption and alters calcium metabolism. Synthetic form derived from salmon (salcalcitonin) applied parenterally or through a nasal spray 200IU/day advocated for 4 weeks.

POOR BONE QUALITY

All the cases might not be properly diagnosed. The clinician shall notice a poor degree of mineralization of the jaw bone or a limited resistance while drilling. This type of jaw site fits into quality 4 bone according to Lekholm and Zarb Classification. Poor quality bone requires use of more “active” surfaces than the classical machined c.p. titanium surface.

DIABETES MELLITUS

Diabetes mellitus is a common endocrine disorder, subdivided into type 1 and type 2. Type 1 is insulin dependent (IDDM) and type 2 is non-insulin dependent (NIDDM).

Diabetic patients are more prone to healing complications.the duration of diabetes is a significant predator for implant failures. Antimicrobial therapy may reduce the implant failure rate.

SJOGREN’S DISEASE

Sjogren’s disease is an autoimmune disorder, affecting all the exocrine glands (explaining xerostomia and xeropthalmia) and collagen-containing tissues (explaining rheumatoid arthritis). Very rare and most of the times remains undiagnosed. Marginal bone loss may be anticipated in certain cases, one can encourage the use of osseointegrated implants in xeromatic patients who often experience prosthesis retention problem because of the dryness.

DEVELOPMENTAL DISORDERS OF THE SKIN

These include a large series of rare ectodermal anomalies which are characterised by hypohydrosis,skeletal deformities and often mental retardation. It may involve hypodontia or anodontia and aggressive forms of juvenile periodontitis, which may lead to a need for oral implants.

Since retention of dentures might be a problem due to extremely thin jaw bone ridges, ZYGOMATIC implants may be a solution for maxillary rehabilitation. Various case reports presented till date reveal that ectodermal dysplasias and hyperkeratosis,palmo-plantaris do not constitute contraindications for oral implant placement.

SCLERODERMIA

Only one case report is available reporting the impact of sclerodrmia on osseointegration. The 11 implants placed successfully integrated.

CROHN’S DISEASE

The circulating antigen-antibody complexes in Crohn’s disease may lead to autoimmune inflammatory processes in several parts of the body,including bone-implant interface during healing phase. Factors associated with the disease such as medication or malnutrition,may also play a role in respect to implant placement.

PARKINSON’S DISEASE

It is a chronically progressive neurologic disorder caused by neurodegeneration. The disease results in rigidity of limbs,tremors and bradykinesia. The oro-pharyngeal musculature is often affected,leading to problems with speaking, chewing and swallowing. Implants can increase patient’s comfort in cases of partial edentulism.

CARDIOVASCULAR DISEASES

Cardiovascular diseases do not constitute a serious challenge to osseointegration.

HEMATOLOGIC DISEASES

LEUKEMIAS

Acute leukemia is characterised by lymphadeno pathies, hepato and spleenomegaly, anemia thrombo cytopenia and a high leokocytosis. Cases have shown that even in a patient successfully treated with an allogenic bone marrow transplantation for myelogenous leukemia, osseointegration was possible.

The relevance of lymphoid cell malignancies in terms of implant placement is unknown.

PLATELET AND COAGULATION ANOMALIES

It is known that osseointegartion depends on the formation of a normal blood clot, which leads to an organizes fibrin clot,allowing an uneventful migration of bone cells to implant surface.

Thrombocytopenia jeopardizes a normal blood clotting.one such patient was treated with oral implants 3 out of 4 failed.

Any coagulation anomaly, from blood vessel wall anamoly to haemophilia is a challenge to any surgery and achievement of proper osseointegration. Only specialised team shoul place implants in such patients.

MEDICATIONS

PHENYTOIN

Antiepileptic drug Phenytoin is known to provoke gingival enlargement in the presence of plaque and thus in edentulous areas because of plaque carrying prosthesis in intimate contact with the underlying gingival.

Gingival overgrowth may also happen around transgingival/mucosal abutments in presence of plaque. Resection of the soft tissue can be performed by gingivectomy for limited overgrowths or by flap surgery when larger volumes are involved.

CALCIUM-CHANNEL ANTAGONISTS

Dihydropyridines, calcium-channel blockers for hypertension and cyclosporine have gingival overgrowth as a side effect.

Cyclosporine has a more challenging effect on osseointegrated implants,accelerating bone turnover provoking a negative bone balance.

CONCLUSIONS

Most systemic contraindications are relative. Since most of these patients need oral rehabilitation following implants, clinician shall evaluate both assets and liabilities.

REFERENCES