Deciduous Dentition PDF

ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Learning Outcomes: 1. Tooth mo...

ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Learning Outcomes: 1. Tooth morphology of the incisors, canines and molars. 1.1 Features noticed on the incisal/occlusal surfaces; labial/buccal surfaces; mesial and distal surfaces. 2. The similarities and differences between the different types/class of teeth. 3. The size differences between similar teeth in the maxilla and mandible. FACULTY OF DENTISTRY 4. The similarities and differences between the morphologies of DOCTOR OF DENTAL SURGERY deciduous dentition and permanent dentition. ORAL BIOLOGY-DDS1:0409 By: Prof Dr Phrabhakaran ([email protected]) ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Deciduous dentition Permanent Dentition Heterodont Monophyodont Diphyodont Polyphyodont  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Mesiodistal crown diameters Maxilla (mm) Mandible -There are twenty primary teeth, “milk” teeth, (mm) “deciduous” teeth, five in each quadrant. A 6.6 4.0 -Two incisors, one canine, two molars per quadrant (no premolars). B 5.3 4.7 -Serve extremely important functions; C 6.9 5.9 - mastication D 7.1 7.8 - speech E 9.0 9.8 - growth of jaws - maintenance of space - esthetics - as a “weapon” ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Morphological Differences between deciduous and -Deciduous teeth emerge between 6 months and 2 ½ permanent dentition years of age. 1) Deciduous teeth are smaller, except molars which are larger than the premolars which replace them; this -Deciduous molar may be retained till 12-13 years of difference in size is called leeway space and provides age. some space for permanent teeth in the developing dentition. -Natural loss of deciduous teeth is called exfoliation; the roots are resorbed. -Morphologically they are similar in many ways to their permanent successors, but there are differences.  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION 3) Cervical ridges are more prominent in deciduous 2)The crowns of deciduous teeth are wider teeth which make them appear more bulbous; the mesiodistally compared with their crown height; this enamel retains its thickness at the cervical region and makes anterior teeth appear more cup-shaped and then stops abruptly rather than thinning down as in gives molars a squat appearance. the permanent teeth; teeth seem to have constricted necks; in anteriors there is a bulge in the cervical 1/3 on both the lingual and the labial; in molars only the buccal surface is bulged. BUCCAL SURFACE ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION 4)The roots of deciduous teeth differ; anterior teeth have narrower roots which are comparatively longer in 6) There are other differences including – cusps relation to the crown; molars have roots which are tend to be more pointed but they wear quickly; the relatively longer and more slender; molar roots flare enamel is thinner (1mm), more opaque and more more to accommodate the developing premolars; there even in thickness, giving deciduous teeth a whiter is no root trunk. appearance; the pulp horns of deciduous teeth are prominent, especially the mesial of molars.  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION 5) The enamel rods of the deciduous dentition are directed occlusally at the cervical area, while for the Deciduous (General findings) permanent teeth they are directed towards the root. - incisors and canines are similar in morphology to their permanent successors. - the deciduous second molars are similar to morphology to the permanent first molars. - the deciduous first molars are unlike any other tooth; midway between premolars and molars. ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Upper central incisor - Smaller than permanent tooth - Increased mesiodistal diameter which is greater than the height of the crown. - Cup shaped, bulbous - Smooth labial surface, straight incisal edge. - Well-defined marginal ridges, large cingulum - Constricted at the neck - Sharp mesioincisal angle, rounded distoincisal angle - Root tilts distally  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Upper lateral incisor - Smaller than central, especially mesiodistally - Cingulum not as prominent - Rounded distoincisal angle - Not variable as the permanent lateral incisor. ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Upper canine - Diamond shaped from labial and incisal - Cusp very pointed initially, more so than the permanent canine. - Cervical bulge - Contact areas on the same level - Mesial cusp slope longer than distal cusp slope (opposite for the permanent canine) - Lingually- cingulum; mesial and distal marginal ridges; incisal ridges; lingual ridge. - Root tapers lingually and distally  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Lower central incisor Lower lateral incisor - Smallest tooth in the deciduous dentition - Larger than lower central - Bilaterally symmetrical - Not symmetrical, incisal edge follows line of - Lingual surface flatter than uppers arch, distal twist. - Rounded distoincisal angle - Cervical constriction - Bulge on labial and lingual - Single root - Single root, tapering ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Lower Canine - smaller, slimmer than upper - Crown height is greater than mesiodistal diameter - Distal cusp slope longer than mesial - The lingual ridge and marginal ridges are not so pronounced. ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Upper first molar - Occlusal divided into buccal and lingual halves by central groove. - Generally described as having four cusps; mesiobuccal, distobuccal, mesiolingual, distolingual. - But often only three cusps (no distolingual cusp) or sometimes only two cusps (no distobuccal) ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION - Mesiolingual cusp is largest - Squat appearance from the buccal; cusps not pronounced. - On the mesial side of the buccal surface there is a pronounced bulge (sometimes called the tubercle of Zuckerkandl).  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION - The central developmental groove joins the central - When viewed from the occlusal, the outline fossa with the mesial triangular fossa; extends to the converges lingually and distally. distal triangular fossa. - Supplemental grooves radiate from the mesial pit. - Three roots; two buccal and one lingual. - Sometimes the oblique ridge- triangular ridge connecting the mesiolingual cusp with the distobuccal cusp. - Distobuccal root smallest and the palatal root is the largest. ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Upper second molar - Central fossa with central pit - Morphologically like the permanent first molar. - Central groove connecting mesial triangular fossa - Smaller than the permanent first molar, but larger with central fossa than the deciduous first molar. - Buccal developmental groove separates the mesio- - Roots more slender and diverge compared with and distobuccal cusps. permanent. - Oblique ridge connects the mesiolingual cusp with - Prominent bulge on the cervical part of the buccal distobuccal cusp. surface. - Distal developmental groove continues as the lingual - Four cusps, oblique ridge etc. like permanent first developmental groove. molar. - Cusp of Carabelli often present ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION FC - CUSP OF CARABELLI DECIDUOUS DENTITION Lower first molar - Four cusps; two buccal and two lingual (mesiolingual is the largest) - Joining the two mesial cusps is a ridge of enamel called the buccolingual crest or transverse ridge. - Pronounced cervical bulge (tubercle of Zuckerkandl) LDG  ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION - Buccal cusps are compressed labiolingually; Buccal - From the occlusal view the tooth outline converges developmental groove may separate the cusps lingually, especially on the mesial - Lingual cusps clearly defined by lingual - From the occlusal view there is a rhomboidal developmental groove. outline, with the mesiodistal diameter greater than the buccolingual. - There are two roots; one mesial, one distal. - The mesial root is longer and does not taper much and so appears rectangular. FIRST MOLAR ORAL BIOLOGY ORAL BIOLOGY DECIDUOUS DENTITION DECIDUOUS DENTITION Lower second molar - Morphologically like the permanent lower first molar. - Five cusps; three buccal, two lingual. - The three buccal cusps are approximately equal in size; so are the lingual cusps - Smaller than permanent molar - Prominent bulge on buccal surface - Rectangular occlusal outline.  ORAL BIOLOGY DECIDUOUS DENTITION It is important to know and appreciate the differences in morphology between permanent and deciduous teeth, especially in paedodontics (children’s dentistry). Differences in anatomy are relevant to treatments such as stainless steel crowns and pulpotomies. Also the concept of leeway space is important in orthodontics.