Teeth and supporting tissues

Transcription

1 Teeth and supporting tissues 1. The permanent teeth shape, relief and histological structure 2. Periodontium 3. Abnormalities of teeth 4. Phylogenetic and ontogenetic tooth development 5. The deciduous teeth 6. Eruption of the deciduous and permanent teeth

2 Teeth, dentes Teeth, dentes (Gr. odus, odontos): mechanical breakdown (chew) of food help in phonation derivatives of oral mucosa cornified papillae 2

3 Phylogenetic development of teeth 3

4 Teeth, dentes Characteristics of human dentition: close contact between teeth heterodont dentition (Gr. different teeth ) teeth differ both morphologically and functionally teeth have the same general structure, regardless of their functional segregation diphyodont dentition two successions of teeth (two types of dentition) in a process of evolution reduction in tooth number 4

5 Dental morphology Anatomical parts of a human tooth: tooth crown, corona dentis surfaces margo incisialis (incisivus) incisors facies occlusalis (masticatoria) premolars and molars o tuberculum dentale (cuspis dentalis) facies vestibularis (labialis, buccalis) facies lingualis facies contactus (mesialis et distalis) anatomical vs. clinical crown tooth neck, cervix dentis tooth root, radix dentis in dental alveolus apex radicis dentis dental cavity cavitas dentis (pulparis) cavitas coronae canalis radicis dentis tooth pulp, pulpa dentis pulpa coronalis pulpa radicularis 5

6 Basic tooth structure Tissue components of the tooth crown: dental cuticle, cuticula dentis 5-30 µm ectodermal origin an amorphous layer that covers the tooth crown non-mineralized layer of organic material o proteins, glycosaminoglycans enamel, enamelum (substantia adamantina) ectodermal origin the hardest substance in the body thickness 0.01 (tooth neck)-2.5 mm acellular and nonreplaceable highly mineralized substance 96-97% o hydroxyapatite crystals o closely packed enamel prisms, prisma enameli and interprismatic substance organic matrix 2-3% o fibrous keratin-like glycoproteins enamel defects dental caries produced by secretory ameloblasts 6

7 Basic tooth structure Tissue components of the tooth root: dental cement, cementum mesenchyme hard, avascular material covering the tooth root bone-like tissue: o mineral intercellular substance, substantia intercellularis cementi calcium hydroxylapatite 45-50% organic matter and water 50-55% numerous fibrils of type I collagen glycoproteins and proteoglycans o cells, cementocyti located in lacunae joined together by canaliculi o the cement is destroyed by odontoclasts in the tooth neck acellular cement o location of tooth decay 7

8 Basic tooth structure Tissue components of the tooth: dentin, dentinum (substantia eburnea) located in the tooth crown, neck and root elastic, yellowish-white, avascular tissue hard, bone-like tissue: o inorganic matter 70% calcium hydroxylapatite crystals and amorphous calcium phosphate o organic matrix (collagen) 20% o water 10% o cells, odontoblasts with long cytoplasmic processes of Tomes in dentine canals (dentinal tubules) dentin layers: o mantle(0.5 mm) closest to enamel o predentine innermost o secondary dentin 8

9 Basic tooth structure Tissue components of the tooth: dental pulp, pulpa dentis inside the dental (pulp) cavity o crown pulp chamber o root root canal(s) undifferentiated mesenchyme soft loose connective tissue microscopic structure: o cells odontoblasts and dentinoblasts numerous fibroblasts undifferentiated mesenchymal cells macrophages, monocytes and lymphocytes o collagen fibers o ground substance o abundant myelinated and unmyelinated fibers o richly vascularized nutritive function 9

10 Periodontium Attachment apparatus of a tooth gomphosis the tissues investing and supporting the teeth Periodontium (Gr.περι, around + οδονσ, tooth): alveola dentalis periosteum alveolare (insertionis) lig. periodontale cementum radicis dentis periodontium protectoris (gingiva) Desmodontium (Sharpey fibers) fibroblasts Parodontium (in German) functional unit 10

11 Human dentition Permanent teeth, dentes permanentes: 32 teeth into two symmetrical halves upper dental arch, arcus dentalis superior lower dental arch, arcus dentalis inferior 11

12 Permanent (adult) teeth, dentes permanentes: Human dentition anatomical and functional groups: incisors, dentes incisivi canine (dogteeth), dentes canini premolars, dentes premolares molars, dentes molares 12

13 The adult human dentition Coding of the permanent teeth: dental formulae for humans: anatomical I 2 C 1 P 2 M 3 clinical 13

14 Dental panoramic radiography (Orthopantomography) Dental radiology 14

15 Incisors, dentes incisivi The incisor teeth, dentes incisivi: used to incise food total number 8 (2 in each jaw quadrant: 4 upper and 4 lower) crown, corona dentis chisel shaped biting edge, margo incisialis labial surface (facies labialis) lingual surface tuberculum dentale contact surface (mesial and distal) root, radix dentis conical shape root apex, apex radicis dentis medial (central) incisors lateral incisors smaller in size to absent diastema lucky teeth cosmetic dentistry dental consonants 15

16 Canines, dentes canini The canine (dog)teeth, dentes canini: used primarily for firmly holding food the longest teeth in mouth 25 mm in the root total number 4 (two in the upper eye teeth, and two in the lower arch) root single, longer and thicker, conical in form apex radicis dentis compressed laterally crown large and conical; occlusal surface labial surface very convex lingual surface mesial and distal lingual fossae tuberculum dentis sexual dimorphism much larger in the males than in the females, or are absent in females 16

17 Premolars, dentes premolares The premolar teeth, dentes premolares: primary functions of both molars and canines in chewing total number 8 (two per quadrant) first and second premolars crown quadrangular with at least two cusps buccal and palatal occlusal (masticatory) surface buccal surface quite rounded lingual surface rounded in all aspects root single (except the maxillary first premolar) (lingual) 17

18 Molars, dentes molares The molar teeth, dentes molares: serve to chew, crush and grind food the largest of the teeth in mouth total number 12 (six upper and six lower) crown cube-shaped occlusal surface o 4-5 cusps o tuberculum anomale (cusp of Carabelli) roots multiple and separated upper jaw 3 (two labial and one palatal) lower jaw 2 dens serotinus (wisdom tooth) generally appear between the ages of 17 and 25 may never erupt 18

19 Dental arches Dental arches upper and lower: superior dental arch, arcus dentalis superior: larger and semi-ellipsoid inferior dental arch, arcus dentalis inferior: has a parabolic shape dental occlusion and articulation Orthognathism (Gr. orthos straight, gnathos jaw) Progenism vs. Prognathism 19

20 Tooth abnormalities of size and form Anodontia: a complete lack of tooth development rare, most often occurring in a condition called Hypohidrotic ectodermal dysplasia Hypodontia: a lack of some tooth development affecting % of the population absence of third molars % second premolar and lateral incisor Hyperdontia: development of supernumerary teeth develop from a second tooth bud 20

21 Abnormalities in tooth shape Congenital syphilis Hutchinson s teeth: smaller and more widely spaced teeth have notches on their biting surfaces Rickets (rachitis): delayed and abnormal sequence eruption dental deformities enamel defects Hypocalcemic tetany: serious abnormalities of enamel of the canine and molar teeth hypoplasia malformed teeth Elderly face: alveolar ridge resorption loss of teeth jaw atrophy 21

22 Embryonic development of teeth Odontogenesis around 6 th week molecular control of tooth development transcription factor Lef-9; FGF-8 signaling molecules BMP-2,-4 and-7 homeobox genes tooth bud (germ) origin ectoderm lamina dentalis organum epithelum (dentis) mesenchyme o enamel amelogenesis gemma dentis(papilla dentis) o dentin dentinogenesis o tooth pulp cementum cementogenesis 22

23 Histogenesis of dental tissue Odontogenesis: amelogenesis enamel organ bell stage: o outer enamel epithelium cuboidal o enamel pulp, pulpa enamelea o inner enamel epithelium simple columnar epithelium proameloblasts ameloblasts dentinogenesis preodontoblasts young odontoblasts predentin mantle dentin mineralization (maturation) of predentin apatite crystals cementogenesis mesenchymal cells of dental sac cementoblasts tooth root development 23

24 Human dentition Deciduous (milk) teeth, dentes decidui: the first set of teeth in the growth development of humans 20 teeth into two symmetrical halves distinguishing features (traits): similar morphology; smaller in size slightly blue tone of enamel shorter roots wider root canals and cavity 24

25 Human dentition Deciduous teeth, dentes decidui: anatomical and functional groups: incisors, dentes incisivi 2 canine teeth, dentes canini 1 molars, dentes molares 2 25

26 The human deciduous dentition Coding of the deciduous teeth: human dental formulae an expression in symbols of the number and arrangement of teeth in the jaws: anatomical I 2 C 1 M 2 clinical 26

27 Human tooth development timeline Deciduous tooth eruption: begin 6 th mo. central incisor end 2 nd -3 rd yrs. second molars formed temporary dentition until 5-6 years of age Permanent tooth eruption: begin 5 th -6 th yrs. first (six-year) molar end yrs. third molar (wisdom tooth) Deviations from the established norms: precocious dentition, dentitio praecox delayed dentition, dentitio tarda 27

28 Disturbances in tooth formation Dilaceration: a disturbance in shape of teeth due to trauma during the period in which tooth is forming Enamel hypoplasia: defective enamel matrix formation with a deficiency in the cementing substance tooth enamel: hard but thin deficient in amount Turner s hypoplasia: a tooth enamel defect missing or diminished enamel usually affects only one tooth in the mouth (Turner s tooth) associated with the dilaceration 28

29 Upper tooth row: molars Blood supply of the teeth rr. dentales of a. alveolaris superior posterior the remaining teeth rr. dentales of a. alveolaris superior anterior Lower tooth row: rr. dentales of a. alveolaris inferior Venous drainage: plexus venosus pterygoideus vv. maxillares v. retromandibularis v. facialis Lymphatic drainage: teeth in upper jaw submandibular nodes parotid and supraclavicular nodes teeth in lower jaw submental and submandibular nodes cervical and paratracheal nodes 29

30 Innervation of the teeth Teeth and gums in upper jaw: nerve plexus formed by the infraorbital nerve: rr. alveolares superiores anteriores rr. alveolares superiores posteriores r. alveolaris superior medius rr. dentales superiores rr. gingivales superiores Teeth and gums in lower jaw: n. alveolaris inferior plexus dentalis inferior: rr. dentales inferiores rr. gingivales inferiores 30

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