Bio Mechanics of Ede State 2

8/8/2019 Bio Mechanics of Ede State 2

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Causes of patients becoming edentulous

Caries

Periodontal disease

Non disease factors

Attitude

Behavior Dental attendance

Characteristics of health system

Low occupational levels


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Mechanism of tooth support

Teeth function properly only ifadequately supported--- Periodontium(PDM) -- 2 soft & 2 hard tissues

PDM attaches teeth to bone(resilient suspensory

apparatus resistant to functional forces)

Teeth adjust their position under stress Principal function

Support & positional adjustment

Hard tissues (cementum & bone) Soft tissues (periodontal ligament & lamina propria

of gingiva)


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Occlusal forces exerted are controlled byneuromuscular mechanisms of masticatory system

Reflex mechanisms with receptors in muscles,

tendons, joints & periodontal structures --- regulatemandibular movements

Greatest force produced mastication & deglutition,

short & vertical in direction Tongue & circumoral musculature longer duration

& horizontal in direction


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Calculation of forces applied on PDMCHEWING

Actual chewing time per meal 450 secFour meals per day 1800 sec

One chewing stroke per sec 1800 strokes

Duration of each stroke 0.3 sec

Total chewing forces per day 540 sec (9 min)

SWALLOWING

Meals

Duration of one deglutition 1 Sec

During chewing, 3 deglutition per min, 1/3 rd with occlusal

force

30 Sec (0.5 min)

BETWEEN MEALS

Daytime 25 / hr (16 hr) 400 sec (6.6 min)

Sleep : 10 / hr (8 hr) 80 sec (1.3 min)

TOTAL 1050 sec = 17.5 min


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Mechanisms of Complete denture Support

Approximate area of PDL support 45 cm2

Masticatory load (conscious effort) 44 lb (20 kg)

Maximum forces with CD - 13-16 lb (6 to 8 kg)(Selective food habits)

Mucosa support - denture bearing area Maxilla 22.96 cm2

Mandible 12.25 cm2

Residual ridge resorption, little tolerance, systemic diseases

anaemia, hypertension, diabetes, nutritional deficiencies


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Residual ridges


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Residual ridges

Mucosa, submucosa, periosteum & residualalveolar bone


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Dentures move -- resiliency of mucosa &

instability of CD can cause tissue damage

Factors affecting retention

Maximal extension of denture base Maximal intimate contact of denture base & itsbasal seat

Equilization of pressure Muscular factors, impression techniques, polished

surfaces


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Occlusion Primary components

1. Dentition

2. Neuromuscular system

3. Craniofacial structuresFORCE GENERATED

DIRECTION DURATION & MAGNITUDE

Mastication Mainly Vertical Intermittent & lightDiurnal only

Parafunction Frequently Horizontalas well as Vertical

Prolonged, possibly excessiveBoth diurnal & nocturnal


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Distribution of Stress

Mucosal health can be promoted

Hygienic measures Therapeutic measures

Tissue-conditioning techniques

OCCLUSAL LOAD can be reduced by Maximum extension

Reduction of area of occlusal table

Frequent rest periods (8 hours)


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Function &parafunction

generate

Force Time

Pressure Controlled by Controlled partially by

Tissue damaged byoccluding local

circulation

1. Correct clinical technique2. Use of permanent soft liner

Nocturnal tissue rest


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Premature reduction occurs with Attrition /Abrasion of teeth

Reduction is more conspicuous in edentulous &CD wearers

Changes in Face Height

COSMETICCHANGES1. Deepening of Nasolabial groove2. Loss of Labiodental angle3. Decrease in horizontal labial angle

4. Narrowing of lips5. Increase in columella-philtral angle6. Prognathic appearance


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Adaptive & psychological responses CD requires adaptation of learning, muscular skill &

motivation Patients ability & willingness to accept & learn to use

dentures ---- success

Also Habituation gradual diminution of responses tocontinued or repeated stimuli

In old age Memory & Storage is difficult, soadaptation to CD becomes difficult

(as progressive atrophy of elements in cerebral cortex &consequent loss in facility of coordination occurs)

So Dentists role is to MOTIVATE the patients & makeunderstand their NEEDS has proven to be of greatest

clinical value

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Bio Mechanics of Ede State 2