国外口腔解剖乳牙

1、THE DECIDUOUS DENTITION,INTRODUCTION,The word deciduous comes from a Latin word meaning to fall off. Deciduous teeth fall off or are shed like leaves from a deciduous tree.,The deciduous, primary, or, as they often referred to colloquially, (MILK) teeth, have a relatively short life-span before they

2、 exfoliated to be replaced by the permanent teeth. This usually occurs between the ages of 6 and13 years.,The deciduous incisors and canines have permanent successor but the first and second deciduous molars are replaced by the first and second premolars respectively.,The deciduous dentition compris

3、es fewer teeth than the permanent dentition with a total of TEN maxillary and TEN mandibular teeth.,They are as follows, in order of position from the midline: A-First (central) incisor. B-Second (lateral) incisor. C- Canine. D-First molar.,B,C,D,E,A,E-Second molar.,The shorthand formula for the dec

4、iduous teeth is as follows: I 2 C 1 M2 =10,2,1,2,GENERAL CHARACTERISTICS,The deciduous teeth generally have several important differences in morphology, composition, size colour as listed below: 1-The deciduous teeth are smaller than the permanent teeth.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND P

5、ERMANENT TEETH,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND PERMANENT TEETH,2-The enamel of the deciduous teeth is whiter and more opaque, which gives the crown a lighter colour than that of the permanent teeth. 3-The enamel of the deciduous teeth is more permeable and more easily worn down. The degr

6、ee of permeability is lessened after the start of root resorption.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND PERMANENT TEETH,4-The DEPTH OF ENAMEL is more consistent and thinner than in the permanent teeth, being from 0.5mm to 1.00mm thick.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS TEETH AND PERMANE

7、NT TEETH,5- Deciduous teeth have a pronounced cervical margin. The enamel bulges, instead of tapering gently, at the cemento-enaml junction, which is straighter than in the permanent teeth. This cervical bulge is accentuated in the mesiobuccal area of deciduous molars.,PRINCIPAL DIFFERENCES BETWEEN

8、DECIDUOUS AND PERMANENT TEETH,6-In newly erupted deciduous teeth, the cusps tend to be more pointed.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND PERMANENT TEETH,7-The roots of the deciduous teeth are shorter, less strong and lighter in colour than those of the permanent teeth.,PRINCIPAL DIFFERENCES

9、BETWEEN DECIDUOUS AND PERMANENT TEETH,8-The roots of anterior deciduous teeth are longer in proportion to the crown. The roots of posterior teeth are more divergent to allow for the developing permanent successor. They flare out from each other wider than the crown measurement ,and form a minimal co

10、mmon root trunk.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND PERMANENT TEETH,9-The pulp chambers are larger than in the permanent teeth and follow the exterior morphology of the tooth more closely, there tends, therefore to be less depth of dentine.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND PERMAN

11、ENT TEETH,10-The root canal of deciduous teeth are very fine.,PRINCIPAL DIFFERENCES BETWEEN DECIDUOUS AND PERMANENT TEETH,11-Usually there are no depressions or perikymata on the labial surface of the crown of the incisors. These surfaces are smooth.,ON THE ANTERIOR TEETH,ON THE ANTERIOR TEETH,12-Th

12、ere are no mamelones on the incisal edges.,13-The cervical ridge on the facial surfaces is prominent.,ON THE ANTERIOR TEETH,15-The root is narrow mesiodistally.,ON THE ANTERIOR TEETH,14-The cingulae are prominent or seem to bulge and occupy about one third of the cervicoincisal length lingually,ON T

13、HE POSTERIOR TEETH,16- The molar crown have a narrow chewing (occlusal table) buccolingually. 17- The molars occluosal surfaces are shallow. In other words, the cusps are short, the ridges are not pronounced,and the grooves are correspondingly not as deep.,ON THE POSTERIOR TEETH,18-The molar crowns

14、are wide mesiodistally, yet very short cervico- occlusally. 19-The buccal cusps of molars are not pointed or sharp, with cusp slopes meeting at a very wide obtuse angle.,20- There are few grooves or depressions in all surfaces of the crowns.,ON THE POSTERIOR TEETH,21-The cervical ridge is prominent

15、mesially (it is easy to distinguish rights from left ).,ON THE POSTERIOR TEETH,22- The second molars are larger than the first molars. 23-The root furcation is near the crown, and there is little if any root trunk.,ON THE POSTERIOR TEETH,ON THE POSTERIOR TEETH,24-The roots are widely spread beyond t

16、he confines of the crown to allow for the developing permanent successors.,ON THE POSTERIOR TEETH,ON THE POSTERIOR TEETH,ON THE POSTERIOR TEETH,25-Roots are thin or slender.,ON THE POSTERIOR TEETH,ON THE POSTERIOR TEETH,26-The second molar roots are spread more widely than the first deciduous molar

17、( opposite of the permanent molars).,E,D,6,7,IMPORTANT FUNCTIONS OF SOUND DECIDUOUS TEETH,Maintenance of a normal appearance. Formulation Efficient mastication of food. of clear speech. Maintenance of a proper diet. Missing or badly decayed teeth may be one reason that young children reject foods th

18、at are difficult to chew.,IMPORTANT FUNCTIONS OF SOUND DECIDUOUS TEETH,5-Avoidance of infection and concomitant pain .An abscess from a deciduous tooth can cause dark spots (Turners spots) on the permanent tooth developing beneath it. 6-Maintenance of space and arch continuity for the emergence of p

19、ermanent teeth.,Chronology: Initial calcification 3-4 months in utero Completion of crown 4 months Eruption 7 months Completion of root 1 years,MAXILLARY FIRST(CENTRAL) DECIDUOUS INCISOR,MAXILLARY FIRST(CENTRAL) DECIDUOUS INCISOR,PRINCIPAL IDENTIFYING FEATURES: 1- Rounded disto-incisal angle: sharp

20、mesio-incisal angle. 2-Similar to maxillary first permanent incisor but smaller and chubbier overall. 3-Large lingual cingulum and pronounced bulge on labial surface.,MAXILLARY FIRST(CENTRAL) DECIDUOUS INCISOR,M,D,M,D,PRINCIPAL IDENTIFYING FEATURES: 4-Root tilts distally and labially from long axis

21、of crown. 5-One root canal; two pulp horns, one mesial, one distal. Mesial horn slightly larger. VARIATIONS No noticeable variations.,MAXILLARY FIRST(CENTRAL) DECIDUOUS INCISOR,MAXILLARY SECOND (LATERAL) DECIDUOUS INCISOR,Chronology: Initial calcification 4 months in utero Completion of crown 5month

22、s Eruption 8-9months Completion of root 1 -2 years,MAXILLARY SECOND (LATERAL) DECIDUOUS INCISOR,MAXILLARY SECOND (LATERAL) DECIDUOUS INCISOR,Chronology: Initial calcification 4 months in utero Completion of crown 5months Eruption 8-9months Completion of root 1 -2 years,Chronology: Initial calcificat

23、ion 4 months in utero Completion of crown 5months Eruption 8-9months Completion of root 1 -2 years,MAXILLARY SECOND (LATERAL) DECIDUOUS INCISOR,PRINCIPAL IDENTIFYING FEATURES: 1-Similar shape to maxillary deciduous central incisor but crown is smaller and narrower in proportion. 2-Lingual cingulum l

24、ess pronounced.,MAXILLARY SECOND (LATERAL) DECIDUOUS INCISOR,3-Rounded disto-incisal angle ;sharp mesio-incisal angle. 4-One root canal; two pulp horns, one mesial ,one distal. Mesial horn slightly larger. VARIATIONS Rare, in contrast to the highly variable maxillary permanent,PRINCIPAL IDENTIFYING

25、FEATURES:,MANDIBULAR FIRST (CENTRAL) DECIDUOUS INCISOR,Chronology: Initial calcification 4 months in utero Completion of crown 4 months Eruption 61/2 months Completion of root 1 -2 years,PRINCIPAL IDENTIFYING FEATURES: 1-Single tapered root more rounded than that of lower mandibular permanent inciso

26、r ,tends to incline distally. 2-Smalles tooth in the deciduous dentition. 3-Sometimes a logitudinal groove on the distal surface of root. 4- cervical margin most sinuous on mesial side.,MANDIBULAR FIRST (CENTRAL) DECIDUOUS INCISOR,MANDIBULAR FIRST (CENTRAL) DECIDUOUS INCISOR,PRINCIPAL IDENTIFYING FE

27、ATURES: 5-Large , convex cingulum and pronounced bulge on labial surface. 6-One root canal; two pulp horns ,one mesial, one distal. VARIATIONS: The pronounced cervical bulge on the labial surface may be reduced or completely absent.,MANDIBULAR SECOND (LATERAL) DECIDUOUS INCISOR,MANDIBULAR SECOND (LA

28、TERAL) DECIDUOUS INCISOR,Chronology: Initial calcification 4 months in utero Completion of crown 41/2months Eruption 7 months Completion of root 1 -2 years,Chronology: Initial calcification 4 months in utero Completion of crown Eruption,PRINCIPAL IDENTIFYING FEATURES: 1-Single tapered root with roun

29、d cross-section, tend to incline distally . 2-Rounded disto-incisal angle; sharp mesio-incisal angle.,MANDIBULAR SECOND (LATERAL) DECIDUOUS INCISOR,MANDIBULAR SECOND (LATERAL) DECIDUOUS INCISOR,3-Incisive edge slopes downwards from mesial to slightly lower distal surface. 4-Crown may, in some cases,

30、 show twisting on root for incisive edge to follow mandibular arch.,PRINCIPAL IDENTIFYING FEATURES:,MANDIBULAR SECOND (LATERAL) DECIDUOUS INCISOR,PRINCIPAL IDENTIFYING FEATURES: 5- Larger than lower first (central) deciduous incisor. 6-Lingual surface may be more concave than that of the madibular c

31、entral deciduous incisor. 7-Single root; two pulp horns, one mesial, one distal. VARIATIONS No noticeable variations . A feature of the deciduous dentition is its consistency in its morphology. .,MAXILLARY DECIDUOUS CANINE,Chronology: Initial calcification5 months in utero Completion of crown 9month

32、s Eruption 16-20 months Completion of root 3years,MAXILLARY DECIDUOUS CANINE,PRINCIPAL IDENTIFYING 1-Mesial slope of cusp longer than distal slope. 2-Conical crown with pronounced cervical bulge and pointed cusp.,MAXILLARY DECIDUOUS CANINE,MAXILLARY DECIDUOUS CANINE,MAXILLARY DECIDUOUS CANINE,MAXILL

33、ARY DECIDUOUS CANINE,MAXILLARY DECIDUOUS CANINE,MAXILLARY DECIDUOUS CANINE,MAXILLARY DECIDUOUS CANINE,MAXILLARY DECIDUOUS CANINE,M,D,FEATURES :,D,M,MAXILLARY DECIDUOUS CANINE,PRINCIPAL IDENTIFYING FEATURES 3-Labial and lingual logitudinal ridges extending from cusp tips :,4-Crown more bulbous than t

34、hat of maxillary permanent canine.,MAXILLARY DECIDUOUS CANINE,PRINCIPAL IDENTIFYING FEATURES:,5-Diamond-shape outline rounded corners from incisal aspect. 6-Cervical margin rises further incisally on the mesial than on the distal surface.,D,M,PRINCIPAL IDENTIFYIN 7- Single root often more than twice

35、 the length of the crown. Slender taper with similar cross-section to that of the maxillary permanent canine; distally inclined. 8-Single root canal ;pulp chamber elongated and directed towards cusp. VARIATIONS A symmetrical and symmetrical crown forms are equally common. Otherwise no noticeable var

36、iations.,MAXILLARY DECIDUOUS CANINE,FEATURES:,MANDIBULAR DECIDUOUS CANINE,MANDIBULAR DECIDUOUS CANINE,Chronology: Initial calcification 5months in utero Completion of crown 9 months Eruption 16-20 months Completion of root 2-3 years,PRINCIPAL IDENTIFYING FEATURS: 1-Smaller and slimmer overall than t

37、he maxillary deciduous Canine. 2-Less well-defined labial and lingual longitudenally ridges; lingual ridge often completely absent. 3-Concave lingual surface. 4-Distal slope longer than mesial. 5-Cervical margin more sinuous on mesial side. 6-Single tapering root inclines distally and slightly labia

38、lly. 7-Single root canal; pulp chamber elongated and directed towards cusp. VARIATIONS: No noticeable variations. Lingual logitudenal ridge occasionally present on lingual surface.,MANDIBULAR DECIDUOUS CANINE,PRINCIPAL IDENTIFYING FEATURS: 1-Smaller and slimmer overall than the maxillary deciduous C

39、anine. 2-Less well-defined labial and lingual longitudenally ridges; lingual ridge often completely absent. 3-Concave lingual surface. 4-Distal slope longer than mesial. 5-Cervical margin more sinuous on mesial side. 6-Single tapering root inclines distally and slightly labially. 7-Single root canal

40、; pulp chamber elongated and directed towards cusp. VARIATIONS: No noticeable variations. Lingual logitudenal ridge occasionally present on lingual surface.,MAXILLARY FIRST DECIDUOUS MOLAR,Chronology: Initial calcification 5months in utero Completion of crown6 months Eruption 12-16months Completion

41、of root 2-2 years,PRINCIPAL IDENTIFYING FEATURES: 1- Pronounced bulge on mesial side of buccal surface: molar tubercle of Zuckerkandl. 2-Trapezoid coronal outline with narrow occlusal surface running mesiodistally.,MAXILLARY FIRST DECIDUOUS MOLAR,MAXILLARY FIRST DECIDUOUS MOLAR,MAXILLARY FIRST DECID

42、UOUS MOLAR,PRINCIPAL IDENTIFYING FEATURES: 3-Lingual surface shorter, mesiodistally, than the buccal. 4-Mesiolingual cusp largest and pointed. 5-Widest labiolingual crown measurement at mesial end.,MAXILLARY FIRST DECIDUOUS MOLAR,PRINCIPAL IDENTIFYING FEATURES: 6-Three root canals ; four pulp horns:

43、 mesiobuccal, distolingual, distobuccal and mesiolingual. VARIATIONS: Palatal and distobuccl roots sometimes fuse. Mesiobuccal cusp sometimes has an accessory cusp mesial to it. Distolingual cusp sometimes absent. Zuckerkandl, tubercle is occasionally scarcely discernible.,MAXILLARY FIRST DECIDUOUS

44、MOLAR,MAXILLARY SECOND DECIDUOUS MOLAR,Chronology: Initial calcification 6 months in utero Completion of crown 10-12 months Eruption 1 -2 years Completion of root 3 years,PRINCIPAL IDENTIFYING FEATURES: 1-Morphology of maxillary first permanent molar duplicated on a smaller scale. 2-More prominent b

45、ulge on cervical part of buccal surface.,MAXILLARY SECOND DECIDUOUS MOLAR,D,D,L,L,M,M,B,B,PRINCIPAL IDENTIFYING FEATURES: 3-Roots have wider divergence than those of maxillary first permanent molar. 4-Cusp of Carabelli present in most cases.,MAXILLARY SECOND DECIDUOUS MOLAR,MAXILLARY SECOND DECIDUOU

46、S MOLAR,PRINCIPAL IDENTIFYING FEATURES: 5-Three root canals ; three pulp horns: mesiolingual, distobuccal and distolingual. VARIATIONS: Cusp of Carabelli may be absent. Very rarely the distolingual cusp may be so reduced as to be scarcely discernible. The palatal and distobuccal roots may sometimes

47、be fused.,MANDIBULAR FIRST DECIDUOUS MOLAR,MANDIBULAR FIRST DECIDUOUS MOLAR,MANDIBULAR FIRST DECIDUOUS MOLAR,Chronology: Initial calcification 5months in utero Completion of crown 6months Eruption 12-16months Completion of root 2-2 years,PRINCIPAL IDENTIFYING FEATURES: 1-Molar tubercle of Zuckerkand

48、l: an exaggerated cervical bulge on the buccal surface of the crown over the mesial root, with a considerable cervical constriction. 2-Four cusps: buccal cusps compressed labiolingually with no clear separation between them in contrast to the two lingual cusps which are clearly defined and roughly conical in shape. 3-Mesiolingual cusp largest.,MANDIBULAR FIRST DECIDUOUS MOLAR,MANDIBULAR FIRST DECIDUOUS MOLAR,MANDIBULAR FIRST DECIDUOUS MOLAR,MANDIBULAR FIRST DECIDUOUS MOLAR,MANDIBULAR FIRST DECIDUOUS MOLAR,L,B,D,M,