3.12 Phylogenetic evolution etc

What does phylogenetic evolution entail?

• History of evolution of species or groups, showing broad biological changes between species

• Adaption to the environment and exchange of substances are key aspects

In phylogenetic evolution, when species develop masticatory apparatus for food intake what happened?

• Function of mastication becomes more developed as species evolve

• Mechanical processing is needed, leading to evolution of a masticatory apparatus

• Tissues become harder and a jaw is formed

what is ontogenesis?

• physical and mental development of an organism from fertalisation of the egg to adulthood

In ontogenesis, what do species require for food intake and what occurs as species develop?

Species require an opening for food intake, which necessitates a masticatory apparatus.

As species develop, the function of mastication becomes more and more developed

In what was the evolution of first teeth and jaw bones seen?

Fish

in what was the first TMJ joints found?

amphibians

In what was the first palate that separates the oral and nasal cavity found?

reptiles

in what was the first periodontium found?

crocodiles

what does the oral cavity contain in humans?

• it is completely developed

• contains - lips, cheek, salivary glands and mucosa

what is homodontia?

• teeth that are equal in shape and size, often found in species with an epithelial origin

what is diphyodontia (like humans)?

• the process of tooth replacement, where primary dentition is replaced by secondary dentition

what are the two basic periods for dental development?

• non functional period

• functional period

what was the time frame for the non-functional and functional period of dental development?

• non-functional: in mothers womb during feotal development)

• functional: after birth

what is the timeframe for non-functional period of dental development?

• 12th day - oral fossa (bounded by jawbone) begins to grow

• 5-7 weeks - development of oral cavity begins. Relationship between jaws shows an initial embryonic maxillary prognathism

• 2nd month - two palate lamellae form

• 3rd month - raphe palatine develops. Tongue in lower part of oral-facial complex. Relationship between jaws becomes initial embryonic mandibular prognathism

• Last months - due to position of foetus in womb, maxilla starts to grow intensively. Thus, child born with secondary embryonic maxillary prognathism

what occurs during functional period of dental development?

• New borns - palate and TMJ fossa is flat, TMJ disk is thin

• 6 months - lower incisor erupts

• End of 1st year - mandible becomes single bone

What does masticatory apparatus consist of?

1. Support part

   • Bones, joints, teeth and periodontium

2. Motor part

   • chewing and mimic muscles responsible for movement and function of masticatory system

3. Secretory part

   • Glands play role in secretion of saliva, aid in mastication

4. Neuro-trophic

   • Masticatory apparatus also influenced by neuro, blood and lymphatic system which gives nourishment and support

5. Soft tissues

   • Such as cheeks, lip and skin also involved in masticatory process

what are physiologic and functional changes in masticatory apparatus?

• Occlusal surface becomes worn out

• Ontogenetic periodontal changes (changes that occur during development)

• Tooth loss can be full arch loss or single tooth loss that promotes dental alveolar bone defects (Godons phenomenon)

• TMJ functional changes

• Muscles functional status changes

what are phases of dental worn-out? (Prof. Peev 1993)

1. Compensatory phase

2. Subcompensatory phase

3. Decompensation

What occurs in compensatory phase of dental worn-out?

• Attrito dentis - affects only enamel

• Occlusal contacts become facets up to 4mm²

• chewing efficiency decreases

• Ps gradually increased (specific forces)

what does subcompensatory phase entail of dental worn out?

• Attritio Dentis Cum Abrasione - up to enamel-dentin junction

what does decomposition phase pf dental worn-out entail?

• Abrasio Dentis (4 stages)

What is Godons phenomenenon?

• when tooth is lost, structural integrity of arch is disrupted

• subsequent realignment of teeth so that equilibrium is reached

• Teeth that are adjacent or opposing to the edentulous space begin to move into the gap

what are the affects of Godon phenomenon?

• Masticatory function is disrupted

• speech

• aesthetics compromised