Lecture 5. etiology and risk factor

Definition: (main) cause of a disease

Etiology

Definition: a modifying characteristic that is associated with an increased chance of developing a disease

Risk factor

Extrinsic or intrinsic factors:

• plaque, smoking, dental restorations

Extrinsic factors

Extrinsic or intrinsic factors:

• genetics, age, gender, race, diabetes, tooth anatomy

Intrinsic

The three types of factors for perio

• extrinsic

• Intrinsic

• Idiopathic

How does bacteria and inflammation cause periodontitis?

1. Gram-negative anaerobes

2. Inflam response (PGE2, IL1, collagenase)

3. Destruction of periodontal ligament and bone

4. Deeper perio pockets

Repeat!

How do deep pockets effect the positive feedback loop?

They contain more (gram-neg) bacteria and are harder to keep clean

T or F: there is a single bacteria strain that us cause of periodontitis

False: no single strain but rather groups of bacteria

T or F: tissue damage is directly caused by the bacteria

False the body’s immune response

What are the six things periodontal attachment loss can lead to?

• Periodontal pocket formation

• Gingival recession

• Root exposure

• Bone loss

• Tooth loosening

• Tooth loss

Where does perio attachment occur?

The CEJ

T or F: in attachment loss both sift and hard tissues are affected

True (gingiva and bone)

What is dysbiosis and what can it lead to?

Imbalance of bacteria and the host

Leads to a disproportionate immune response to periodontal bacteria and causes tissue injury and bone loss

Symbiosis with proportional host response

Clinically healthy

Incipient dysbiosis with proportional host response

Gingivitis

Frank dysbiosis and disproportional host response aka hyper-inflammatory

Periodontitis - body conceded to prevent bacteria

How to decrease bacterial load disrupts positive feedback loop of periodontitis

Plaque and calculus removal leads to a goal of less bacterial load:

• controlled inflam response

• No tissue destruction

• Normal periodontal sulcus

Three ways plaque and calculus can be removed

Brushing, flossing, prophylaxis

Major risk factors for periodontitis

• smoking

• Diabetes

Minor risk factors

• Genetics

• Diabetes

• Age

• Gender

• Race

• Obesity

• Poor nutrition

• Alcohol consumption

• Medication

• Dental restorations

• Occlusal trauma

Compared to non-smokers, smokers generally have what 6 characteristics:

• Fewer teeth

• Deeper periodontal pockets

• More supragingival calculus

• More attachment loss

• More bone loss

• Less gingival bleeding on probing

Heavy smokers have a relative risk for perio attachment loss of?

4.75x

Heavy smokers have relative risk of severe bone loss of?

4.75x

What are the three mechanism of negative effects of smoking on the peridontium?

• impaired immune response

• Increased prevalence of periodontal pathogens

• Impaired healing

Which mechanism of negative effects of smoking on periodontium?

• Neutrophil chemotaxis and phagocytosis

• Decreased IgG antibody production

• Decreased B-helper lymphocyte numbers

Impaired immune response

Which mechanism of negative effects of smoking on periodontium?

• Altered fibroblast attachment and function

• Negative local effects on cytokine and growth factor production

• Poor response to periodontal therapy

Impaired healing

Normal fasting blood glucose

<100 mg/dL

Hyperglycemic fasting blood glucose

>126 mg/dL

Causal blood glucose

>200 mg/dL

Normal blood glucose vs HbA1c

Hour-to-hour vs 3 month average (rec life cycle)

Glycated hemoglobin

Normal HbA1c

<5.7%

Therapeutic HbA1c target

<6 .5%

Most common relative risk of diabetes

Retinopathy (rr = 25x)

Relative risk of periodontal disease for diabetic pt

2.3x

Three ways diabetes damages tissues

1. Vascular changes

2. Host immune response

3. Altered CT metabolism

What can diabetic vascular changes lead to?

diabetic microangiopathy = capillary walls thicken and weaken

resulting in kidney failure, retinopathy, atherosclerosis and impaired wound healing

Explain role of neutrophils & monocytes and macrophages in diabetic altered host immune response

• neutrophil adherence impaired, so chemotaxis and phagocytosis affected

• Hyper-responsive monocytes and macrophages = increased pro-inflam cytokines and mediators

Change in CT metabolism could …

uncouple the resorptive and formative responses and impair bone remodeling

Are genetics the main contributor to periodontitis?

NO just a contributor

Environmental appear more powerful

Which deficiency may lead to early onset periodontitis?

Inherited leukocyte deficiency

Which genotype was associated with severity of periodontitis in non-smokers?

Interleukin-1 polymorphic gene cluster

Variant of IL1β gene associated w high lvls of IL-1 production

IL1 pathogenesis mechanism

• Pro-inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFalpha) are key regulators of the host response to microbial infection during periodontal pathogenesis

• IL-1 is also a major modulator of extracellular matrix catabolism and bone resorption

• increased production of IL-1 may result in greater periodontal tissue destruction (i.e. alveolar bone, extracellular matrix).

T or F: prevalence and severity of periodontitis increases with age

True

Is periodontitis an inevitable consequence of aging?

No (“age effect” is likely due to cumulative effect of prolonged exposure to true risk factors (wear ‘n’ tear)

T or F: there is a clear difference btwn male and female in susceptibility to periodontitis

false (women have better oral hygiene and mya retain teeth longer due to Tx preference)

which ethnic groups show higher prevalence of periodontitis?

US Mexican Americans and Non-Hispanic Black Americans

no pattern worldwide

the overall odd ratio of having perio disease in obese or overweight indiv is (?)

2.13

The negative association between low plasma (?) lvls and perio attachment loss suggests the deficiency may contribute to perio severity

vitamin C

(?) consumption may be associated with increased severity of attachment loss in a doe-dependent fashion

alcohol

which meds can cause gingival hyperplasia?

anticonvulsants, β-blockers, immunosuppressants

blood diseases: acute leukemias can cause…

enlargement, bleeding, ulcerations (severe effects)

blood diseases: neutropenia and agranulocytosis can cause…

ulcerations, attachment loss (severe effects)

blood diseases: anemia can cause…

hemorrhage, mucosal atrophy

what are some local contributing factors to perio?

• verhang/defective restorations

• open contacts/ food impaction

• subgingival calculus deposits

• brushing trauma (NNCL non-carious cervical legion)

• tooth position (labially positioned, gingival recession)

• local tooth related anatomy

• occlusal trauma

(?) was found greater around overhanging and defective restorations

alveolar bone loss

opn interproximal contact in class (?) restorations were found to be associated with less alveolar bone height

class II, open contact, food impaction

what is the principal irritant of subgingival calculus, a local contributing factor?

the non-mineralized layer of plaque that covers subgingival calculus

the underlying calcified portion may be a significant contributing factor

can occlusal trauma (ie bruxism, premature occlusal contact, crossbite, attrition, wear facets) alone cause perio?

NO, but when combined w perio inflam the occlusal trauma may accelerate attachment loss and development of vertical bone loss

what is cervical enamel projection? perio relevance?

developmental anomaly where a triangular-shaped extension of enamel projects apically from the cementoenamel junction (CEJ) onto the tooth's root

may be removed bc CT attachment not possible on enamel

ateh projections may create pathway for bacteria ingress

what is radical groove? perio relevance?

enamel-covered groove on root resulting in deep probing and food impaction