biomechanics of edentulous state

Biomechanics of edentulous state : 

Biomechanics of edentulous state

Causes of patients becoming edentulous : 

Causes of patients becoming edentulous Caries Periodontal disease Non disease factors Attitude Behavior Dental attendance Characteristics of health system Low occupational levels

Mechanism of tooth support : 

Mechanism of tooth support Teeth function properly only if adequately 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)

Slide 4: 

Occlusal forces exerted are controlled by neuromuscular mechanisms of masticatory system Reflex mechanisms with receptors in muscles, tendons, joints & periodontal structures --- regulate mandibular movements Greatest force produced – mastication & deglutition, short & vertical in direction Tongue & circumoral musculature – longer duration & horizontal in direction

Mechanisms of Complete denture Support : 

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

Residual ridges : 

Residual ridges

Residual ridges : 

Residual ridges Mucosa, submucosa, periosteum & residual alveolar bone

Slide 9: 

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 & its basal seat Equilization of pressure Muscular factors, impression techniques, polished surfaces

Occlusion : 

Occlusion Primary components 1. Dentition 2. Neuromuscular system 3. Craniofacial structures

Distribution of Stress : 

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)

Changes in Face Height : 

Premature reduction occurs with Attrition / Abrasion of teeth Reduction is more conspicuous in edentulous & CD wearers Changes in Face Height COSMETIC CHANGES Deepening of Nasolabial groove Loss of Labiodental angle Decrease in horizontal labial angle Narrowing of lips Increase in columella-philtral angle Prognathic appearance COSMETIC CHANGES Deepening of Nasolabial groove Loss of Labiodental angle Decrease in horizontal labial angle Narrowing of lips Increase in columella-philtral angle Prognathic appearance

Adaptive & psychological responses : 

Adaptive & psychological responses CD – requires adaptation of learning, muscular skill & motivation Patient’s ability & willingness to accept & learn to use dentures ---- success Also – Habituation – gradual diminution of responses to continued or repeated stimuli In old age – Memory & Storage is difficult, so adaptation to CD becomes difficult (as progressive atrophy of elements in cerebral cortex & consequent loss in facility of coordination occurs) So Dentist’s role is to MOTIVATE the patients & make understand their NEEDS has proven to be of greatest clinical value