ASSOCIATE FELLOW WRITTEN EXAMINATION KEY WORDS AILING IMPLANTS A prerequisite ...

304 Pages·2009·3.8 MB·English

ASSOCIATE FELLOW WRITTEN EXAMINATION
KEY WORDS

AILING IMPLANTS

A prerequisite for a successful endosteal dental implant should be obtaining a
perimucosal seal of the soft tissue to the implant surface. Failure to achieve, or
maintain, this seal results in the apical migration of the epithelium into the bone-to-
implant interface, and possible complete encapsulation of the endosseous or root
portion of the implant system.

CRITERIA FOR IMPLANT SUCCESS:
- clinical immobility
- ability to bear load
- no associated symptoms
- no danger to adjacent structures
- no progressive periimplant radiolucency
- minimal loss of crestal bone height (less than 0.2 mm annually after the first year of
function or service.) 12
Complications, which may cause a failure of an implant, may result from biological,
iatrogenic or mechanical factors.

BIOLOGICAL FACTORS INCLUDE:
- bone of poor quality or inadequate volume
- smoking
- previous irradiation or immunosuppression
IATROGENIC FACTORS INCLUDE:
- inappropriate case selection
- faulty planning
- deviation from recommended surgical protocol
- prosthodontic overloading owing to poor design

1 Albrektsson T, Zarb G. Current interpretations of the osseointegrated response: clinical significance. Int J Prosth 1993: 6: 95–105.
2 Albrektsson T, Sennerby L, Wennerberg A.State of the art of oral implants. Periodontol 2000. 2008;47:15-26. Review

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MECHANICAL FACTORS INCLUDE:
- overly forceful manipulation
- patient parafunctional habits, such as bruxism.
In addition to the above factors, poor oral hygiene, associated with bacterial plaque, is
perhaps the primary aetiological factor in the loss of implants, resulting in periodontitis
or periimplantitis which may be induced by similar bacterial flora.
Pathogens associated with periodontal disease are gram-negative, black-pigmented,
anaerobic flora.
Bacterial flora at ailing implant sites consist of gram-negative rods, including bacteroids
and fusobacterium.
These gram-negative micro-organisms produce endotoxins, heat stable
lipopolysaccharides that have been shown to initiate an acute inflammatory response in
addition to producing bone destruction.
A condition known as retrograde peri-implantitis, may also be associated with implant
failure. Retrograde implant failure may be a result of bone microfractures, caused by
premature implant loading or overloading, other trauma, or occlusal factors. Failing
implants with traumatic aetiology have microflora more consistent with gingival health,
and composed primarily of streptococci. 34

TREATMENT OF AILING IMPLANTS:
1. If there is active infection, with radiographic bone loss:-
- reflect tissue - degranulate
- if implant is HA coated, and the HA is undergoing resorption, has changed colour
and texture; remove all the HA until metal surface is visible (avoid air abrasives).
- detoxify the implant with 40% citric acid for thirty (30) seconds - flush with sterile
water
- graft with freeze-dried bone
- protect the graft with a membrane
- leave implant out of function and covered for 10 to 12 weeks
2. If there is no active infection:
- treat as above, leaving the HA intact.5

3 Heitz-Mayfield LJ. Peri-implant diseases: diagnosis and risk indicators.J Clin Periodontol. 2008 Sep;35(8 Suppl):292-304. Review.
4 Holm-Pedersen P, Lang NP, Müller F. What are the longevities of teeth and oral implants? Clin Oral Implants Res. 2007 Jun;18
Suppl 3:15-9. Review. Erratum in: Clin Oral Implants Res. 2008 Mar;19(3):326-8.
5 Lindhe J, Meyle J; Group D of European Workshop on Periodontology. Peri-implant diseases: Consensus Report of the Sixth
European Workshop on Periodontology. J Clin Periodontol. 2008 Sep;35(8 Suppl):282-5.

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ALLOGRAFTS

Bone augmentation materials can encourage or stimulate bone growth in areas where it
is lost as a result of pathology, trauma or physiological process. These materials can be
classified according to their mode of action:
- osteoconduction
- osteoinduction
- osteogenesis

Osteoconduction characterises bone growth by apposition from the surrounding bone.
Therefore, this process must occur in the presence of bone on differentiated
mesenchymal cells. Examples of osteoconductive materials include bio-active ceramics
such as synthetic Hydroxyapatites (HA).
Osteoinduction involves new bone formation from osteoprogenitor cells derived from
primitive mesenchymal cells under the influenced of one or more inducing agents that
emanate from the bone matrix.
Osteoinductive materials are more contributory to bone formation during the
remodelling process. Commonly used materials in implant dentistry are bone autografts
and allografts.6
Osteogenesis NEED INFO HERE
Osteoprogenitor cells living within the donor graft, may survive during transplantation,
could potentially proliferate and differentiate to osteblasts and eventually to osteocytes.
These cells represent the ‘‘osteogenic’’ potential of the graft ‘‘Osteoinduction’’ on the
other hand is the stimulation and activation of host mesenchymal stem cells from the
surrounding tissue, which differentiate into bone-forming osteoblasts. This process is
mediated by a cascade of signals and the activations of several extra and intracellular
receptors the most important of which belong to the TGF-beta superfamily 7

A bone allograft is an osseous, transplanted tissue from the same species as the
recipient, but of different genotypes. The tissue is obtained from cadavers, processed,
and then stored in various shapes and sizes, in bone banks for future use. There are
primarily three types of bone allografts:
- frozen
- freeze dried
- demineralised freeze dried

6 Misch C.Contemporary Implant Dentistry. Misch C. Chapter 36.Keys to Bone Grafting and Bone Grafting Materials. 3 edition,
Editorial Elsevier Mosby 2008. pag 855-863
7 Giannoudis PV, Dinopoulos H, Tsiridis E.Bone substitutes: an update.Injury. 2005 Nov;36 Suppl 3:S20-7. Review.

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Frozen bone:
Frozen bone is rarely used in implant dentistry because of the risks of rejection and
disease transmission. Although irradiation may decrease the immune response, viral
transmission is still possible.
Freeze dried bone:
Cortical and/or trabecular bone is harvested from a disease free donor, washed in
distilled water, and ground to a particle size of 500 µm to 5 mm. It is then immersed in
100% ethanol to remove fat, frozen in nitrogen, then freeze dried and ground to a
smaller particle size of 250 µm to 750 µm, which has been shown to promote
osteogenesis. The dessicating steps allow for long-term storage and decreased
antigenicity. The inorganic and organic matrix is therefore maintained because the
calcium salts remain. The inorganic portion of bone serves as a scaffold and mineral
source for bone formation. The inorganic material which includes Bone Morphogenetic
Protein (BMP), is found within the structure of the HA. Osteoclasts are required to
resorb the bone in order to release its bone growth.8
Demineralized freeze dried bone allografts:
Calcium and phosphate salts are removed from DFDB with hydrochloric or nitric acid.
The demineralisation rapidly exposes the bone morphogenetic proteins (BMPs). DFDB
has been shown to stimulate more bone formation initially than FDB, because of the
composition ie: protein, bone growth factors and collagen.9

ANEMIA
Anaemia is the most common haematological disorder. It is not a disease entity; rather
it is a symptom complex that results from a decreased production of erythrocytes, an
increased rate of their destruction, or a deficiency in iron.
It is defined as a reduction in the oxygen-carrying capacity of the blood and results from
a decrease in the number of erythrocytes or the abnormality of the haemoglobin.10
Anemia is a disease resulting from a decrease in the normal amount of circulating
hemoglobin. A variety of factors cause this decrease, including iron deficiency,
hemolysis, a decrease in the production of red blood cells (RBCs), folic acid deficiency,
or a combination of these entities. 11

The general symptoms and signs are all a consequence of either a reduction of oxygen
reaching the tissues or alterations in the red blood cell count.

8 Eppley BL, Pietrzak WS, Blanton MW. Allograft and alloplastic bone substitutes: a review of science and technology for the
craniomaxillofacial surgeon. J Craniofac Surg. 2005 Nov;16(6):981-9. Review.
9 Hoexter DL. Bone regeneration graft materials. J Oral Implantol. 2002;28(6):290-4.
10 Mish CE, Contemporary Implant Dentistry. Mish CE. Chapter 4:. Medical Evaluation of the Implant Patient. 2nd edition. Editorial
MOSBY, 1999, pag. 57
11 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.

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SYMPTOMS:

Anemia is a symptom complex that can be caused by numerous diseases. Proper
recognition of symptoms may help in the diagnosis of underlying systemic disease. In
addition, anemias have oral manifestations that dentists must be able to recognize. The
anemia or its medical management may affect the dental management in an outpatient
setting. Special consideration for the prevention and treatment of infection is
necessary.12

* mild anaemia - fatigue, anxiety, sleeplessness.
* Chronic anaemia - shortness of breath, abdominal pain, tingling of extremities,
muscular
* Weakness, headaches, fainting, change in heart rhythm and nausea.

Oral signs of anemia include:
- angular stomatitis
- sore, painful, smooth tongue
- loss of papillae and redness
- loss of taste sensation
- parasthesia of the oral tissues13

Several forms of classification of anemia are used, however the following are the
most widely adopted:
- acute post-haemorrhagic anemia
- iron deficiency anemia
- megaloblastic anemia
- haemolytic anemia
- anemia of bone marrow inadequacy

Iron deficiency anaemia Causes:
- Iron deficiency anemia is the most common of all anemias
- chronic blood loss as in gastro-intestinal bleeding from ulcers, tumours
or menorrhagia

12 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.
13 Mish CE, Contemporary Implant Dentistry. Mish CE. Chapter 4:. Medical Evaluation of the Implant Patient. 2nd edition. Editorial
MOSBY, 1999, pag. 57

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- defective iron intake due to dietary deficiency as in infants, pregnant
women and the elderly, or due to defective absorption from the bowel.
- Other causes of iron deficiency anemia include chronic blood loss such
as menstrual or menopausal bleeding, parturition, bleeding hemorrhoids,
or a bleeding malignant ulcer in the gastrointestinal tract.
- Malabsorption of iron can also cause this anemia, such as is seen in
subtotal or complete gastrectomy, a habit of eating clay (pica), or as part
of a malabsorption syndrome.
- Helicobacter pylori may impair iron absorption or increase iron demand
because the organism uses iron as an essential growth factor.14

Megaloblastic anaemia: the essential feature is the presence of megaloblasts in the
bone marrow and is due to a deficiency of vitamin B12 or folic acid. Causes:
* dietary deficiency
* pregnancy
* gastric disease e.g. Pernicious anaemia
drugs - some anti-convulsants and anti-metabolites antagonise folic acid.

 Malabsorption occurs secondary to the inadequate gastric production or
defective functioning of intrinsic factor, which is necessary to absorb vitamin
B12. Other conditions that can lead to vitamin B12 deficiency include
gastrectomy, small bowel bacterial overgrowth, diverticulosis, blind intestinal
loops, scleroderma, tapeworm, tropical sprue, celiac disease, Crohn’s
disease, alcoholism, HIV, and medications such as neomycin and
colchicine.15

Haemolytic anaemia:
 Anemia due to hemolysis results from the decreased survival of
erythrocytes, either from an intracorpuscular (hereditary) or
extracorpuscular factor
 corpuscular defects e.g. Sickle cell disease (Sickle cell anemia falls
under a broad entity of diseases known as hemoglobinopathies, which
are a group of disorders characterized by the presence of structurally
abnormal hemoglobin. Sickle cell anemia is an autosomal recessive
disorder and is characterized by an abnormality in the chain of
hemoglobin.)

14 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.
15 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.

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 Hemolytic crisis may be precipitated by taking oxidative drugs such as
sulfonamides, by ingesting fava beans, or by infections like hepatitis or
pneumonitis. Although much attention has been given to drug-induced hemolytic
crisis, infections cause the majority of crises. 16

Anaemia of bone marrow inadequacy:
* a complication of many chronic diseases e.g. Rheumatoid arthritis and
leukaemia
* High risk of infection, bacterial sepsis, and fungal infections are the most serious
complications in this disease and occur due to the absence of neutrophils. Etiologies
range from idiopathic to posthepatitis aplastic anemia to pharmaceutically induced
aplastic anemia.17

Anaemia complications in implant patients may affect both the short term and
long term prognosis.
* Bone maturation and development are often impaired in the long-term
anaemic patient.
* Abnormal bleeding is also a common complication of anaemia
* Increased oedema and subsequently increased post -operative
discomfort are common consequences
* Anaemic patients are more prone to infections from surgery.
*
An accurate test for anaemia is the hemotocrit, followed by the haemoglobin. The
hemotocrit indicates the percentage of a given volume of blood made up of
erythrocytes. The normal values for men range from 40% to 54% and those for women
range from 37% to 47%.
Haemoglobin makes up almost 95% of the dry weight of red blood cells. Normal values
for men are 13.5 to 18.8dl; those for women are 12.0 to 16.8 dl. The baseline
recommended for surgery is 10 mg.
Pre-operative and post-operative anti-biotics should be administered.

Dental management considerations for patients with anemia

Before treatment
● CBC with differential if patient presents with signs and symptoms of anemia
● Consultation with a physician if low hemoglobin levels are found
● Assessment of the severity of the underlying anemia in conjunction with the patient’s
physician or hematologist

16 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.
17 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.

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● Possible blood transfusions if the underlying anemia is severe
● Avoidance of elective treatment in patients who are in a “crisis,” as occurs in sickle
cell anemia.
● In patients receiving blood transfusions, a thorough history and physical examination
to determine the potential risk of acquiring hepatitis or HIV
● Judicious use of general anesthesia if hemoglobin levels are below optimal levels
● If deemed necessary, administration of antibiotic prophylaxis prior to treatment for
appropriate anemias

During treatment
● Short appointments
● Cautious use of nitrous oxide analgesia in patients with sickle cell anemia and in
patients with poorly controlled vitamin B12 deficiency
● Primary closure
● Aggressive management of infections

After treatment
● Avoidance of prescription drugs that can precipitate a crisis or cause hemolysis in
patients with hemolytic anemias
● Emphasis of impeccable oral hygiene techniques/recommendation of prophylactic
antibiotics if poor wound healing is anticipated
● Cautious use of respiratory depressant analgesics with Hgb/dL.

Medications known to cause hemolysis
Drugs used in dentistry that can precipitate a hemolytic event in G-6-P-D deficiency
● ASA
● Sulfonamides
● Chloramphenicol
● Acetophenetidin
● Dapsone
● Ascorbic acid
● Vitamin K

Dietary product that can cause hemolysis
● Fava beans

Drugs used in dentistry that have a lesser link to hemolysis in G-6-P-D deficiency
● Penicillin
● Streptomycin
● Isoniazid18

18 Derossi SS, Raghavendra S. Anemia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Feb;95(2):131-41. Review.

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ANAPHYLACTIC SHOCK
Anaphylaxis is the word used for serious, rapid, allergic reactions, usually involving
more than one part of the body.
Anaphylactic Reaction: to the sufferer there is no difference. To the doctor there is no
difference to the treatment. However, there is a difference in the way it comes about.
The antibodies IGE cause anaphylaxis. But exactly the same end results can happen in
various ways without IGE. That is called an anaphylactoid reaction. (Morphine-like
drugs, and some intravenous liquids given to replace blood or fluid loss, cause
anaphylactoid reaction without IGE.

Most anaphylactic episodes involve an immediate hypersensitivity reaction following
allergen interaction with cellbound immunoglobulin E (IgE). Less commonly other
immunologic mechanisms, for example autoimmune mechanisms, are involved; or no
immune mechanism is involved, for example when anaphylaxis is triggered by exposure
to cold air or water. Some individuals have idiopathic anaphylaxis with no obvious
trigger. Regardless of the inciting mechanism, the final common pathway involves
release of histamine and other mediators from mast cells and basophils.19

Common causes of anaphylaxis:
* Foods - especially nuts, fruits, fish and less common spices.
* Drugs - especially penicillins, anaesthetic drugs, some IV infusion compounds and
things injected during X-rays. Aspirin and NSAIDS.
* Latex - mainly in rubber latex gloves, catheters and other medical products.
Sufferers are mainly health care workers.
* Bee or wasp stings - (yellow jackets).
* Idiopathic causes.
* Exercise - may precipitate such reactions as exercise induced anaphylaxis or
exercise induced food dependent anaphylaxis.
* Medicines - beta-blockers can change mild reactions from another cause into severe
anaphylaxis because they block the body's main defence against anaphylaxis.

Anaphylaxis from the four most common triggers (foods, insect stings, medications and
natural rubber latex) may affect more than 1% of the general population with
considerable variations in age and in age-specific aetiology.20

19 Sheikh A, Shehata YA, Brown SG, Simons FE Adrenaline for the treatment of anaphylaxis: cochrane systematic review. Allergy.
2009 Feb;64(2):204-12.
20 Sheikh A, Shehata YA, Brown SG, Simons FE Adrenaline for the treatment of anaphylaxis: cochrane systematic review. Allergy.
2009 Feb;64(2):204-12.

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Symptoms:
* urticaria
* generalised itching
* nasal congestion
* difficulty breathing
* cough
* cyanosis
* fainting
* dizziness
* anxiety
* confusion
* slurred speech
* rapid pulse
* palpitations
* nausea, vomiting
* diarrhoea
* abdominal pain or cramping
* wheezing
* nasal flaring
* intercostal retractions.

Skin symptoms and signs, including generalized urticaria, flushing, itching and
angioedema [swelling of the subcutaneous tissues], are the most common
manifestations of anaphylaxis (in 80%–90% of those affected) followed by respiratory
(70%) and gastrointestinal (40%) symptoms; hypotension occurs in 10–30% of
episodes. Symptoms often occur within 5–30 min of exposure to the trigger factor,
although occasionally they do not develop for several hours. Anaphylaxis may be fatal
within minutes, usually through cardiovascular or respiratory compromise or both. Upper
and lower respiratory tract obstruction is commonly reported in fatal cases .True
mortality rates are unknown in anaphylaxis because of under-recognition and
underdiagnosis of the disease.21

21 Sheikh A, Shehata YA, Brown SG, Simons FE Adrenaline for the treatment of anaphylaxis: cochrane systematic review. Allergy.
2009 Feb;64(2):204-12

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