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Combining Terms of orientation





Eruption (emerging)

will be used here to denote the emergence of the tooth through the gingival;
 Also means the continued movement until the tooth makes contact with the opposite ones


Primary teeth

Occur at different rates; may have some with root resorption while others are being formed; all of these rates may differ from child to child; usually completely formed by about 3 yrs; permanent dentition is usually completed by about age 25 if 3rd molars are counted; calcification begins in utero 13-16 weeks, and 18-20weeks all have begun to calcify; calcification of permanents is postnatal with formation 8-12 years to complete; primary crown formation continues after birth for the centrals for 3 months, 4 months for the laterals, 7 months for the first molars, 8 1/2 months for canine, 10 1/2 months for 2nd molar


Clinical consideration

malformations; chronologies sometimes play role in form, color, arrangements; anomolies most often seen in maxillary laterals, third molars, and mandibular 2nd premolars, enamel hypoplasia (defect in thickness) develops during enamel formation, clefts, knowing characteristics of some malformations may help to find cause


Crown and Root Development (2 components)

formation of crown and roots, eruption of teeth


Root formation begins after the crown has formed

cementum forms as a covering on the root, is similar to bone, and is a thin layer, cementum of permanent teeth is much thicker than primary teeth, continued root formation aids in the tooth erupting and contacting opposites;


Root resorption

In the absence of a permanent successor, the root may only partially resorb; failure to resorb may result in prolonged retention of primary tooth



classes (primary, mixed, permanent); prenatal begins as early as the 6th week, mandibular jaw is larger than maxilla, very little vertical dimension, primary development, no teeth visible at brith (rare exceptions), alveolar bone height increases to accommodate the increasing length of teeth


Sequence of eruption

Central incisors, lateral incisors, first molars, canine, second molar (some variation may occur) tooth size, morphology, and formation are highly inheritable characteristics


Emergence of Primary teeth

Mandibular central 8 mo (6-10)
At about 13-16 mo all 8 of primary central incisors have erupted; 1st primary molars (16 mo), usually the maxillary emerge first; primary maxillary canines 19 mo (16-22), primary mandibular canines 20 mo (17-23); primary 2nd mandibular molars 27 mo (23-31); primary 2nd maxillary molars 29 mo (25-33) Primary dentition is completed by 30 months


Mixed dentition

Begins with the emergence of mandibular 1st permanent molar and ends with the loss of the last primary tooth about 11-12 yrs. Permanent teeth do not begin eruptive movement until crown is completed; mandibular 1st molar is guided by the distal surface of the primary 2nd molar (molars are not succedaneous)


Loss of primary teeth

Premature loss due to caries affect the development of permanent dentition; lack of dental knowledge, poor attitudes of parents leads to same attitudes and habits with adult dentition, leads to a lack of space for permanent teeth, "going to lose them anyway" mentality, don't realize may be in use from 6mo-12 yrs; contribute to the health during the important developing years; may lead to abnormal occlusion, loss of arch length, and crowding


Permanent dentition

All 32 teeth completed 18-25 years of age; 4 centers of formation (developmental lobes); injuries during dentinogenesis leads to anomalies ; sites of fusion can show developmental grooves; follicles of developing incisors and canines are lingual to deciduous roots (it will eventually move forward); follicles of premolars are in bifurcation of deciduous roots; incisors, canines, and premolars are succedaneous- they take the place of their primary predecessors


Emerging sequence of permanent teeth

1st molars, central incisors (6-7) mandibular before maxillary, may erupt at same time as the mandibular 1st molar; mandibular lateral may erupt along with central incisor, before central incisors can take their place, the primary must be exfoliated, maxillary centrals, maxillary laterals about a year after centrals, first premolars at about 10 years, mandibular canines at about same time as first premolars, and second premolars during next year, maxillary canines, 2nd molars at about 12 yr, third molars about 17 or later


size of teeth

genetically determined for the most part, also has to do with racial differences (Lapp-small, aborigines-large)


dental pulp

CT with arteries, veins, lymphatic system, nerves; is large in primary teeth and young permanent, hence these teeth are more sensitive than teeth in older people, pulp gets smaller with age due to deposition of secondary dentin


Cementoenamel Junction Types

1. Enamel overlaps cementum (excess enamel)- happens in posterior teeth in bifurcation (fibers can't attach) 2. end to end 3. gap exposing dentin (sensitive to decay) 4. cementum overlapping enamel 5. enamel extending into bifurcation of molars creates periodontal risks 6. periodontal fibers can't embed into enamel; epithelium attachment


Dental age

General rules is that when the last tooth has been completed, skeleton is near maturation; while teeth are forming, very little environmental influences will affect teeth; tetracycline is one exception- brown to bluish color; fluoride will make enamel less susceptible to caries; excess fluoride will result in fluorosis- white to brownish spots or bands; children should only be given a pea sized amount of fluoride paste under age 3


Permanent Mandibular Incisors Intro

Smallest mesiodistal dimensions; central somewhat smaller than lateral- opposite with maxillary; mamelons worn away early, contact areas are near the incisal ridges (incisal third area) near the same level for all; very few anomalies; labial surfaces are inclined lingually so that ridges are lingual to bisecting line of root


Permanent Mandibular central

is smallest tooth, crown has slightly more than half the mesiodistal diameter of maxillary central incisor; labiolingual dimension is 1mm less than maxillary central; masticatory stress is in a labio-lingual direction (reinforcement); root is narrow mesiodistal, wide labiolingual, length of root is as great if not longer than maxillary central incisors


Lingual aspect of permanent mandibular central

Lingual surface is smooth, slight concavity at incisal third; marginal ridges are almost absent, sometimes prominent near incisal, surface is flat progressing to convexity at cervical third, show least developmental grooves along with lateral, outlines are symmetrical


Mesial aspect of permanent mandibular central

Labial face is straight above cervical curvature, lingual outline is straight with labial inclination above cingulum, concave at middle third, incisal ridge either round or worn flat and is lingual to center of root, cervical line curvature toward the incisal almost one third the length of crown, root outline is straight from cervix through middle third, then tapers rapidly, apex is blunt or pointed, mesial surface is convex, smooth at incisal third, tending to concanvity at cervix, mesial surface of root is flat below the cervical line, usually have broad developmental depressions along most of root and these depressions usually deeper at middle to apical thirds


Distal aspect of permanent mandibular central

Cervical line curvature is about 1mm less than mesial, distal surface of crown and root similar to mesial, developmental depression on distal may be more marked with developmental groove at its center


Incisal aspect of permanent mandibular central

Bilateral symmetry is evident, mesial half almost identical with distal half, incisal edge is almost at right angles with labiolingual bisecting line,, (this is an important identifier between central and lateral) the labiolingual dimension is always greater than mesiodistal, crown tapers to the lingual, mesiodistal measurement is greater at labial


pulp chamber anatomy of permanent mandibular central

Labiolingual section (pulp horn is well developed, large pulp chamber, tapering to apex) mesiodistal section ( narrow cavity with usually only one pulp horn, tapers to apex), root section (often ribbon like, sometimes 2 canals may be present)


Permanent Mandibular Lateral Incisor

resembles the central with the following exception: lateral is somewhat larger than the central


Mesial and distal aspects of the permanent mandibular lateral incisor

Mesial side of crown is usually longer than distal, incisal ridge slopes downward in a distal direction, distal contact area is more in a cervical direction (this is so that the lateral can contact the canine), may have a deeper concavity above the cervical line on the distal, the root is usually considerably longer, will be developmental depressions mesially and distally


Incisal aspect of permanent mandibular lateral incisor

ridge is not at right angles to bisecting line as in the central, ridge or edge is curved to follow the curvature of the arch, this curvature gives the appearance of the crown being twisted on the root


Pulp chamber anatomy of mandibular lateral

form and function are similar to central


Deciduous Teeth general information

Order of eruption (incisors, first molars, canines, second molars with mandibular before maxillary), order of loss (exfoliation)( incisors, first molars, canines, second molars with mandibular before maxillary) high peak attack of caries is at about 13 when there are only about 5% of primaries left; primary teeth are completely finished for only 1-2 years before root resportion begins, 20 primary teeth (4 incisors, 2 canines, 4 molars per ARCH)


Difference between primary and permanent teeth

Smaller in dimension, crowns are wider in comparison to length than permanent, roots of anteriors are narrower and longer comparatively, roots of molars are longer and flare more so that permanent can develop between them, cervical ridges of anteriors are more prominent- requiring more care in operative work, crown and roots at cervix are more slender, cervical ridges on molars are much more pronounced- especially on 1st molars, buccal and lingual surfaces are flatter above cervical line, less pigmented giving a whiter appearance (milk teeth)


pulp chambers and canals of deciduous teeth

enamel is thin with a consistent depth; dentin thickness is thin, pulp horns are high with large pulp chambers, primary roots are narrow and long, roots of molars flare


labial view of primary maxillary central incisors

Mesiodistal measurement is greater than cervicoincisal length (opposite in permanents), labial surface is very smooth, incisal edge is nearly straight, root is cone shaped, sides taper evenly, root length is great in comparison to crown length


lingual view of primary maxillary central incisors

Well developed marginal ridges, highly developed cingulum extending into concavity sort of dividing it into fossae, root narrows lingually


mesial and distal view of primary maxillary central incisors

crown appears thicker at middle third and even on incisal third; cervical line curves toward the incisal less than on permanent, root shows an even taper, note the more pronounced cervical ridges


incisal view of primary maxillary central incisors

Ridge is centered over main bulk and is straight; labial surface is broader and smoother than lingual surface, lingual surface tapers toward cingulum


Primary maxillary lateral incisors

similar to central, only smaller, cervicoincisal length is greater than mesiodistal width, root appears longer in comparison to crown


labial view of primary maxillary canine

crown is more constricted at cervix, mesial and distal surfaces are more convex, long well developed cusp, crest of contour mesially is not as far down as permanents, mesial cusp slope is longer than distal, root is long and slender and more than twice the length of crown


lingual view of primary maxillary canine

Pronounced enamel ridges merging with others, ridges are cingulum mesial and distal marginal ridges and cusp ridges and tubercle at cusp tip connecting cingulum and cusp tip, root tapers evenly


mesial view of primary maxillary canine

outline is similar to lateral and central; has a greater measurement labiolingual at cervical third, gives an appearance of a tooth on steroids


Distal view of primary maxillary canine

Reverse the mesial


Incisal view of primary maxillary canine

Diamond shaped, tip of cusp is distal to the center of the crown, mesial slope is longer than the distal (cusp) slope


Labial view of Primary Mandibular Central

Surface is flat with no developmental grooves, mesial and distal sides taper evenly from contact areas, heavy look at root trunk gives an appearance of maxillary permanent lateral, root is long and evenly tapered


lingual view of Primary Mandibular Central

cingulum and marginal ridges can easily be seen, lingual surface may have a flattened look at middle to incisal third, may have a slight concavity or lingual fossa


Mesial view of Primary Mandibular Central

Incisal ridge is centerd over center of root and labial and lingual crest of contour, cervical bulges are prominent, labiolingual measurement is only 1mm smaller than maxillary central (for strength)


Distal view of Primary Mandibular Central

Reverse the mesial; will often see a developmental depression on distal side of root


Incisal view of Primary Mandibular Central

Edge is straight and bisects the crown labiolingual, will see a taper towards the cingulum, can see a flattened labial surface, only slightly concaveon the lingual


Primary mandibular lateral incisor

Outlines are similar to central only this tooth is larger than central except labiolingual where they are about the same, incisal ridge tends to slope downward distally so that the contact area on the distal is lower


Primary mandibular canine

very similar to maxillary canine except the crown and root may be a little shorter; cervical ridges are not as pronounced as are the maxillary canine, **major difference is that the distal slope is longer than the mesial slope** (aids in proper intercuspation)


Measurements of permanent Mandibular Central Incisor

Cervicoincisal crown (9.5mm),
root (12.5 mm),
M-D diameter of crown (5mm),
M-D diameter at cervix (3.5mm),
L-L crown (6mm),
L-L crown at cervix (5.3mm),
mesial curvature at cervical line (3mm),
distal curvature at cervical line (2mm)


Measurements of permanent Mandibular Lateral Incisors

Cervicoincisal crown (9.5mm),
root (14mm),
M-D diameter of crown (5.5mm),
M-D diameter at cervix (4mm),
L-L crown (6.5mm),
L-L crown at cervix (5.8mm),
mesial curvature at cervical line (3mm),
distal curvature at cervical line (2mm)


Mandibular permanent central Incisor labial view

incisal ridge is straight, at right angles to long axis of root, mesial and distal outlines drop straight down to contact areas, taper evenly to cervix, mesial and distal outlines of root are fairly straight to apical area, slight curve to distal; labial face is smooth, with flattened surface at incisal third, middle third convex, face at cervix is more convex along with the root