anatomy, chronology and vasular supply of primary teeth

GOOD MORNING!

ANATOMY, CHRONOLOGY AND VASCULAR SUPPLY

OF PRIMARY TEETH

CONTENTSCONTENTS

1. Definitions.2. Importance of Anatomy and Chronology of Primary Dentition.3. Basic Terminology.4. Detailed Description Of Each Primary Teeth.5. Clinical Considerations.6. Development Of Vascular Supply Of Primary Dentition.7. Clinical Considerations of Vascular Supply.8. References.

DEFINITIONDEFINITION

• ANATOMY : Greek word anatemnō cut up. Science dealing with the form and structure.

• CHRONOLOGY : Latin chronologia chronos, "time" A study which deals with the timings of various stages of tooth

development , starting with initiation of first dental tissue laid down to the emergence of tooth in the oral cavity and its completion of calcification.

IMPORTANCE OF ANATOMYIMPORTANCE OF ANATOMY

• The anatomy of primary teeth is very important clinically during performing various procedures.

• Good knowledge of anatomy is necessary for cavity preparations and restorations of primary teeth.

IMPORTANCE OF CHRONOLOGYIMPORTANCE OF CHRONOLOGY

• Determination of dental age.• Identification of teeth during examination.• Identification of anomalies- nutritional disturbances, drugs

affecting teeth, pre and post natal disturbances.• Treatment Planning.• It is also of interest to parents as it offers a simple and reliable

method for the evaluation of the stages of development in children (Bailey, 1964)

BASIC TEMINOLOGY

• A cusp is a pyramidal elevation,or peak, located on the crown portion making a divisional part of occlusal surface.

• A cingulum is the lingual lobe of anterior teeth and makes up the bulk of the cervical third.

• A ridge is a linear elevation on the surface of the tooth and is named acc. to location.

• A fossa is an irregular depression or concavity.• A sulcus is long depression or valley between the ridges and

cusps.• A developmental groove is a shallow groove between primary

parts of crown or root.

CALCIFICATION• Calcification (mineralization) takes place following matrix

deposition and involves the precipitation of inorganic calcium salts within the deposited matrix.

• The process begins with the precipitation of a small nidus about which further precipitation occurs.

• The original nidus increases in size by the addition of concentric laminations.

• There is an eventual approximation and fusion of these individual calcospherites into a homogeneously mineralized layer of tissue matrix.

Primary Maxillary Central IncisorPrimary Maxillary Central Incisor

LABIAL ASPECT CROWN Smooth labial surface.M-D diameter > the cervicoincisal length. Incisal edge is nearly straight.Developmental lines usually not seen.

ROOT Cone-shaped. Even, tapered sides.

LINGUAL ASPECT CROWNWell-developed marginal ridges. Highly developed cingulum seen. Cingulum extends up toward the incisal ridge

ROOT•Narrows lingually.

MESIAL AND DISTAL ASPECTS CROWN Similar mesial and distal aspects.The cervical curvature distally is less than the curvature mesially. ROOTThe root is cone-shaped with even, tapered sides.Apex is blunt. Usually Mesial has a developmental groove.

Primary Maxillary Central incisor Primary Maxillary Central incisor

PULP CAVITY3 slight projections on incisal border.Chamber tapers cervically in M-D diameter. Pulp chamber and Canal are larger than permanent ones. No distinct demarcation between canal &chamber Pulp canal tapers evenly until ending in apical foramen Apical ramifications or accessory canals- rare but do occur

INCISAL ASPECT The incisal edge is centered over the main bulk of the crown and is relatively straight.

The labial surface is much broader and also smoother than the lingual surface.

The lingual surface tapers toward the cingulum.

Primary Maxillary Central incisor Primary Maxillary Central incisor

MAXILLARY CENTRAL INCISOR

LABIAL

INCISAL

PALATAL

MESIAL DISTAL

CHRONOLOGY OF MAXILLARY CENTRAL CHRONOLOGY OF MAXILLARY CENTRAL INCISORINCISOR

First evidence of Calcification13-16 weeks in utero

Crown Completed 1 ½ months

Eruption 8-12 months

Root Completed

1 ½ years

Why Mamelons are not seen in primary incisors?

Mamelons are developmental grooves present on incisal edges of a newly erupted incisors. They are seen in permanent teeth as the enamel formation occurs in lobes. The enamel formation of primary teeth takes place in one single lobe and correlating it with chronology of eruption gives a clue for identification of teeth.

Primary Maxillary Lateral Incisor Primary Maxillary Lateral Incisor

• Similar to the central incisor from all aspects, but its dimensions differ width.

• The disto-incisal angles of the crown are more rounded than those of the central incisor.

Primary Maxillary Lateral Incisor Primary Maxillary Lateral Incisor

PULP CAVITY

•The pulp chamber follows the contour of the tooth, as does the canal.•Light demarcation between the pulp chamber and the canal.

MAXILLARY LATERAL INCISOR

LABIAL

MESIAL

INCISAL

PALATAL

DISTAL

CHRONOLOGY OF MAXILLARY LATERAL INCISOR

• First evidence of Calcification

142/3 to 16 ½ months

• Crown Completed 2 ½ months

• Eruption 9-13 months

• Root Completion 2 years

Primary Maxillary CaninePrimary Maxillary Canine

LABIAL SURFACE CROWN •More constricted at the cervix in relation to its M-D width.•Mesial and distal surfaces are more convex. •Has a long, well-developed, sharp cusp. •Contact areas are at the same level.•Mesial slope of the cusp is longer than the distal slope ROOT •Long, slender, and tapering and is more than twice the crown length

LINGUAL SURFACE • Shows well pronounced enamel ridges that merge with each other.• This lingual ridge divides the lingual surface into shallow mesiolingual and distolingual fossae.• The root of this tooth tapers lingually and is usually inclined above the middle third.

MESIAL ASPECT • Similar to that of the lateral and central incisors.• Difference in proportion is evident.• The measurement labiolingually at the cervical third is much greater.

DISTAL ASPECT • Reverse of the mesial aspect. • Cervical line towards the cusp ridge is less than on the mesial surface.

PULP CAVITY•There is a little demarcation between pulp chamber and the canal. •The canal tapers as it approaches the apex. •Pulp chamber follows the external contour of teeth.• Central pulpal horn is projecting incisally.

INCISAL ASPECT

• Diamond-shaped • Angles found at the contact areas mesially and distally are more pronounced and less rounded than those on permanent canines.• Mesial cusp slope is longer than the distal cusp slope, i.e for intercuspation with the lower canine

MAXILLARY CANINE

LABIAL

MESIAL

INCISAL

PALATAL

DISTAL

CHRONOLOGY OF MAXILLARY CANINE

• First evidence of calcification

15-18 weeks in utero

• Crown Completed 9 months

• Root Completed 3 ¼ years

Primary mandibular central incisor Primary mandibular central incisor

LABIAL ASPECT CROWN•Flat face. •No developmental grooves.•Crown is wide in proportion to its length.ROOT •Long and evenly tapered down to the apex, which is pointed. •Almost twice the length of the crown.

LINGUAL ASPECT

•The marginal ridges, cingulum - located easily.

• Middle third may have a flattened surface

incisal third - slight concavity called

lingual fossa.

•Lingual Convergence of the crown

and root is seen.

MESIAL ASPECT CROWN •Incisal ridge is centered over the center of the root. •Convexity of the cervical contours labially and lingually at the cervical third is Most pronounced. ROOT•The mesial surface of the root is nearly flat and evenly tapered; the apex blunt.

DISTAL ASPECT • Reverse of mesial. • Cervical line is less curved.• Developmental depression is evident on the distal side of the root.

Primary Mandibular Central Incisor Primary Mandibular Central Incisor

Primary Mandibular Central Incisor Primary Mandibular Central Incisor PULP CAVITY

•Widest mesiodistally at the roof .•Labiolingually the is widest at the cingulum.•Oval in appearance, tapers as it reaches apex.•Definite demarcation between chamber and canal

INCISAL ASPECT• The incisal ridge is straight and bisects the crown Labiolingually. • A definite taper is evident toward the cingulum on the lingual side. •The labial surface from this view presents a flat surface that is slightly convex, whereas the lingual surface presents a flattened surface that is slightly concave.

MANDIBULAR CENTRAL INCISOR

LABIAL

MESIAL DISTAL

INCISAL

LINGUAL

CHRONOLOGY OF MANDIBULAR CENTRAL INCISOR

• Crown Completion 9 months

• Eruption 19 months

• Root Completion 3 ¼ years

Primary mandibular lateral incisorPrimary mandibular lateral incisor

• Outlines are similar to those primary central incisor. • These two teeth supplement each other in function.• Somewhat larger in all measurements except Labiolingually. • Cingulum of the lateral incisor may be a little more generous than that of the central incisor• Crown root ratio is more in lateral than in central.

• The lingual surface of the crown between the marginal ridges may be more concave. • Incisal ridge tends to slope downward distally.• This design lowers the distal contact area apically, so that proper contact may be made with the mesial surface of the primary mandibular canine

PULP CAVITY•Oval in appearance.•Tapers as it reaches apex. •No demarcation between chamber and canal.

MANDIBULAR LATERAL INCISOR

LABIAL

MESIAL

INCISAL

LINGUAL

DISTAL

Primary mandibular lateral incisor

16 weeks in utero

• Crown completed 3 months

• Root completed 1 1/2 years

Primary Mandibular CaninePrimary Mandibular Canine

• CROWN M-D measurement at the root trunk > M-D Measurement at the contact areas

• It is "thicker" accordingly at the "neck" of the tooth.

• The cervical ridges labially and lingually are not quite as pronounced. • The greatest variation is the distal cusp slope is longer than the mesial slope.

Primary Mandibular CaninePrimary Mandibular Canine

PULP CAVITY•Wide mesiodistally as labiolingually • No diff between canal &chamber•Ends in marked constriction at the apex

MANDIBULAR CANINE

LABIAL

MESIAL

INCISAL

LINGUAL

DISTAL

Primary Mandibular Canine

• First evidence of Calcification

17 weeks in utero

• Root Completion 3 ¼ years

CLINICAL CONSIDERATIONS

• Class III restorations of primary incisors can be quite challenging.

Due to the small clinical crown, the relatively large size of the pulp chamber, the close proximity of the pulp horns to the interproximal surfaces, and the thinness of the enamel.

• Repairing interproximal decay in these teeth requires preparations that are conservative in depth with close attention to detail, both to the preparation itself and to the material placement

• Accessory root/root canal variations in mandibular anterior teeth is more than in maxillary counterparts.

• Dental practitioners should thoroughly assess all teeth scheduled for root canal treatment to prevent the undesirable consequences caused by inadequate debridement of accessory configurations of the root canal system.

• Acess openings of primary anterior teeth traditionally have been through the lingual surface . This remains a surface of choice expect for maxillary incisors where the recommended approach is facially.

• The anatomy is such that the access is successfully made from the facial surface with more extension to the incisal edge than with normal lingual acess.

Primary maxillary first molarPrimary maxillary first molar

BUCCAL ASPECT CROWN•The widest measurement is at the contact areas mesially and distally. •From the contact points, the crown converges toward the cervix.•The occlusal line is slightly scalloped. •Smooth buccal surface.•Little evidence of developmental grooves seen.

ROOT • slender and long, and they spread widely. •All three roots may be seen from this aspect. •The distal root is shorter than the mesial one.•bifurcation begins almost immediately at the site of the cervical line (CEJ).

LINGUAL ASPECT•The general outline is similar to that of the buccal aspect. •The crown converges considerably in a lingual direction, which makes the lingual portion calibrate less mesiodistally than the buccal portion.

• Mesiolingual cusp -most prominent, longest and sharpest. • Distolingual cusp - poorly defined, small and rounded. • Distobuccal cusp -longer and better developed than the distolingual cusp.• All three roots also may be seen from this aspect. • The lingual root is larger than the others.

Primary maxillary first molarPrimary maxillary first molar• MESIAL ASPECT• The dimension of cervical third is greater than occlusal third • The mesiolingual cusp -longer and sharper.• A pronounced convexity is evident on the buccal outline of the cervical third *characteristic bulge• Gives the impression of overdevelopment in this area

Primary maxillary first molarPrimary maxillary first molarMESIAL ASPECTROOT•Mesiobuccal and lingual roots are visible• Distobuccal root is hidden behind the mesiobuccal root. • Lingual root - long and slender. •It curves sharply in a buccal direction above the middle third

DISTAL ASPECTCROWN•Crown is narrower distally than mesially; it tapers markedly toward the distal end.•Distobuccal cusp -long and sharp,•Distolingual cusp -poorly developed. •Prominent bulge seen from the mesial aspect at the cervical third does not continue distally.

DISTAL ASPECTDISTAL ASPECTROOT• All three roots may be seen.•Distobuccal root is superimposed on the mesiobuccal root so that only the buccal surface and the apex of the latter may be seen.• Point of bifurcation of the distobuccal root and the lingual root is near the CEJ.

Primary maxillary first molarPrimary maxillary first molarOCCLUSAL ASPECT•Crown outline converges lingually.•Outline is rectangular, shortest sides is represented by the marginal ridges •Central fossa.• Mesial triangular fossa is just inside the mesial marginal ridge, with a mesial pit in this fossa and a sulcus with its central groove connecting the two fossae.• Well-defined buccal developmental groove divides the mesiobuccal cusp and the distobuccal cusp occlusally.

• Supplemental grooves radiate from the pit in the mesial triangular fossa.

• Oblique ridge.

• Distal marginal ridge is thin and poorly developed.

PULP CAVITY•Pulp Cavity Consists of a chamber - Straight 3 pulpal canals corresponding to 3 roots• Pulp horn sizes MB>ML>DB•Bifurcation of the mesial-facial root into two canals occurs in approximately 75% of maxillary first primary molars.

• Mesio-buccal horn –largest, occupies a prominent portion of pulp chamber. • Mesiolingual horn is second in size, angular. • Distobuccal horn is smallest , sharp & occupies distobuccal angle. • Occlusal view of the pulp chamber resembles somewhat a triangle with rounded corners

MAXILLARY FIRST MOLAR

BUCCAL

MESIAL

PALATAL

OCCLUSAL

DISTALOCCLUSAL

• Distal surface is most caries susceptible surface.• Class II – proximal preparation is initiated after occlusal. Ease of access to the lesion; Ease of polishing the restoration.• Extremely narrow occlusal table.

• Mesiobuccal pulp horn is very large.

• If the distal surface is involved- avoid overextension beyond the oblique ridge.

• Prominent mesiobuccal cervical ridge must be accomodated during SS crown preparation.

CHRONOLOGY OF PRIMARY MAXILLARY FIRST MOLAR

14 ½ - 17 weeks in utero

• Crown Completed 6 months

• Root completion 2 ½ years

Primary Maxillary Second MolarPrimary Maxillary Second Molar

BUCCAL ASPECTCROWN•Resemble those of first permanent molars , but is smaller.•Two well defined buccal cusps with buccal development grooves between them.•The crown is narrow at the cervix in comparison with its M-D measurement at the contact areas.

ROOT•Slender , are much longer and heavier than maxillary first molar•The point of bifurcation between buccal roots is close to the cervical line of crown.•The two buccal cusps are more nearly equal in size and development than those of permanent max 1st molar.

Primary Maxillary Second MolarPrimary Maxillary Second MolarLINGUAL ASPECTCROWN•3 cusps seen•Mesiolingual cusp- large and well developed•Distolingual cusp- well developed more then primary 1st molar•Third supplemental cusp- apical to mesiolingual cusp called the tubercle of carabelli, or fifth cusp•Poorly developed and merely acts as a buttress or supplement to bulk of mesiolingual cusp.

• Well defined developmental grooves separates mesiolingual cusp from distolingual and connects with developmental groove which outlines with fifth cusp.

ROOT• All three roots are visible from this aspect.• Lingual root is large and thick in comparison with other two

roots.

MESIAL ASPECTCROWN•A typical molar outline that resembles that of the permanent molars.•crown appears short because of its width buccolingually in comparison with its length.• Mesiobuccal cusp from this angle is relatively short and sharp. •Little curvature to the cervical line is evident.

MESIAL ASPECTROOT•The mesiobuccal root -broad and flat. •The lingual root - same curvature as of 1 molar.•Mesiobuccal root extends lingually far out beyond the crown outline. • The point of bifurcation between the mesiobuccal root and the lingual root is 2 or 3 mm apical to the cervical line of the crown.

Distal AspectCROWN•Outline of the crown lingually creates a smooth, rounded line.•Buccal surface is almost straight from the crest of curvature to the tip of the buccal cusp. •Distobuccal cusp and the distolingual cusp are about the same in length. •The cervical line - approximately straight.

Primary Maxillary Second Molar

DISTAL ASPECTROOT All three roots are seen •Mesiobuccal root may be seen, since the distobuccal root is superimposed over it. •Distobuccal root - shorter and narrower •Point of bifurcation between the distobuccal root and the lingual root is more apical in location than any of the other points of bifurcation.

OCCLUSAL ASPECT•Tooth resembles the permanent first molar•Somewhat rhomboidal four well-developed cusps : mesiobuccal, distobuccal, mesiolingual, distolingual, and fifth supplemental cusp.•Buccal surface is rather flat with the developmental groove between the cusps less marked than that found on thefirst permanent molar.

Pulp Cavity • 3 pulp canals corresponding to three roots. • Canals leave floor of chamber at the mesiobuccal & distobuccal corners & from lingual area. • Pulp chamber has 4 pulpal horns, a fifth horn projecting from lingual aspect of mesiolingual

horn may be present. • The mesiobuccal pulp horn is largest, pointed & extends

occlusally

• Mesiolingual pulp horn is second in size, when combined with fifth horn it presents a bulky appearance.

• Distobuccal pulp horn is third in size, joining mesiolingual pulp horn as slight elevation.

• Distolingual pulp horn is shortest & extends only slightly above occlusal level.

MAXILLARY SECOND MOLAR

BUCCAL

MESIALOCCLUSAL

PALATAL

DISTAL

• The central pit is most often carious.• If the lingual pit is involved then the preparation on the distal

surface should be extended to form a two surface restoration that includes the distal and lingual pits.

• The Overall preparation is somewhat larger because of its broad flat contacts.

• CLASS II – Proximal box preparation can be somewhat deeper.

The pulp does not extend far into the dentine.

• The disto-occlusal preparation is difficult because the contact is broad in all directions.

This preparation should not be neglected because it can influence the decalcification on the mesial surface of the immature Permanent first molar.

CHRONOLOGY OF PRIMARY MAXILLARY SECOND MOLAR

• Root Completion 3 years

Primary Mandibular First Molar Primary Mandibular First Molar • Strange and Primitive BUCCAL ASPECT • The mesial outline of the crown is almost straight from the contact area to the cervix • Distal portion converges toward the cervix more than usual, so

that the contact area extends distally to a marked degree. • Distal portion of the crown is shorter than the mesial portion,

with the cervical line dipping apically where it joins the mesial root.

Primary Mandibular First Molar Primary Mandibular First Molar

•The mesial cusp is larger than the distal cusp. •A developmental depression dividing them (not a groove) extends over to the buccal surface. THE ROOT •Long and slender•Spread greatly at the apical third beyond the outline of the crown.• The buccal aspect emphasizes the strange, primitive look of this tooth.

LINGUAL ASPECT •Mesially, the crown and root converge lingually to a marked degree •Distolingual cusp - rounded.•Mesiolingual cusp - long and sharp at the tip. •Mesial marginal ridge is well developed. • Part of the two buccal cusps may be seen from this angle.• The cervical line is straighter.

MESIAL ASPECT • Mesiobuccal cusp and the mesiolingual cusp are in view from

this aspect, also the well-developed mesial marginal ridge. • Cervical line slanted upwards buccolingually.• The buccal and lingual outlines of the root drop straight down

and are approximately parallel for more than half their length, tapering only slightly at the apical third

DISTAL ASPECT• Cervical line does not drop buccally.• Distobuccal cusp and distolingual cusp - not as long or as sharp as mesial cusps.• Distal marginal ridges not as straight and well defined as

mesial marginal ridge• Distal root is rounded and shorter and tapers more apically

Primary mandibular first molar Primary mandibular first molar

OCCLUSAL ASPECT• Crowns outlines converges lingually and also distally• More nearly rectangular with shorted sides of the rectangle

represented by marginal ridges• Occlusal surface has central fossa.• Mesial triangular fossa is just inside the mesial marginal

ridge , with a mesial pit in this fossa and a sulcus with its central groove connecting the two fossae

• OCCLUSAL ASPECTA well defined buccal developmental groove divides mesiobuccal cusp and distobuccal cusp.

• Supplemental grooves radiate from the pit in mesial triangular fossa as follows- one buccally , one lingually and one towards the marginal ridge with last sometimes extending over the marginal ridge mesially.

• PULP CAVITY

• Pulp chamber had 4 pulpal horns • Mesiobuccal horn- largest and rounded • Distobuccal pulp horn-is second , but lacks height of mesial horns • Mesiolingual Horn is third in size and second in height. • Distolingual pulpal horn is smallest • Occlusal view of pulp chamber is rhomboidal.

MANDIBULAR FIRST MOLAR

BUCCAL

MESIAL OCCLUSAL

LINGUAL

DISTAL

CLINICAL CONSIDERATIONS• Distal and central pits- Most carious

• Unless the transverse ridge is undermined – Should be kept intact.

• CLASS II – Both buccal , lingual and proximal box should extend adequately to allow for polishing but not overdone. This causes weakening of both cusps with increased tendency to fracture.

• Prominent mesiobuccal cervical ridge must be accommodated for in SS crown preparation.

CHRONOLOGY OF PRIMARY MANDIBULAR FIRST MOLAR

14 ½ -17 weeks in utero

• Crown Completion5 ½ months

• Root Completion 2 ¼ years.

Primary Mandibular Second MolarPrimary Mandibular Second Molar

• It has characteristics that resembles those of Permanent mandibular first molar, although its dimensions differ

BUCCAL ASPECT• Narrower M-D calibration at the cervical portion of the crown than at contact level.• The mandibular first permanent molar, accordingly is wider at the cervical portion

ROOT•The roots are slender and long•Characteristic flare mesioditally at the middle and apical thirds.•The point of Bifurcation of the roots starts immediately below the CEJ.

Primary Mandibular Second Molar Primary Mandibular Second Molar

LINGUAL ASPECT• Two cusps are almost equal dimensions• A short lingual groove is between them • Cervical line is relatively Straight • The mesial Portion of the crown seems to be a little higher then the distal portion , thus appears tipped distally

MESIAL ASPECT• Outline resembles permanent mandibular first molar• The crest of contour is more prominent bucally • Marginal ridge is high.• Lingual cusp is longer or higher then Buccal • Cusp.• Cervical line is regular.

• ROOTMesial root is unusually broad and flat with a blunt and apex sometimes serrated.

• The distal root is almost as broad as the mesial root and is flattened on distal surface.

• The distal root tapers more at the apical end.

DISTAL ASPECT• Crown is not as wide distally.• Distolingual cusp appears well developed and triangular ridge

is seen over the distal marginal ridge• The distal marginal ridge dips down moresharply and is shorter buccolingually than mesial marginal ridge

Occlusal Aspect•Occlusal outline- rectangular•Three buccal cusps are similar in Size •Two lingual cusps are also equally Matched •Well defined triangular ridges seen•The distal triangular fossa - not well defined as mesial triangular fossa•The mesial marginal ridge is better developed and more pronounced than the distal marginal ridge •Supplemental grooves are seen on the slopes of triangular ridges and in the mesial and distal triangular fossa

PULP CAVITY • Pulp cavity is made up of chamber and usually 3 pulp canals• Two mesial pulp canals are confluent as they leave floor of pulp chamber through A common orifice• Distal canal is constricted in the centre

• Pulp chamber has 5 pulp horns corresponding to 5 cusps. • Mesiobuccal and Mesiolingual Pulp Horns are largest• Distobuccal horn - Smaller than mesial horns.• The distal horn is shorter and smallest occupying a position distal to distobuccal Horn.

MANDIBULAR SECOND MOLAR

BUCCAL

MESIAL OCCLUSAL

LINGUAL

DISTAL

• Central pit is more often involved. • Mesial surface is most often involved. • Outline is similar to Permanent first molar.• Occlusal preparation includes all the developmental grooves.• Beware of the mesiobuccal pulp horn.

CHOLONOLOGY OF PRIMARY MANDIBULAR SECOND MOLAR

18 weeks in utero

• Crown completion 10 months

• Root completion 3 years

CLINICAL CONSIDERATIONSCLINICAL CONSIDERATIONS

• The width of the isthmus should be approx. 1/3rd the dimension between buccal and lingual cusps – reduces the possibility of ditching along the occlusal margins and undermining the cusps.

• Greater constriction of the neck increases the danger of damaging soft tissues interproximally during proximal box preparation.

• The depth necessary to penetrate into the pulpal chamber during access openings in posterior teeth is quite less than that in the permanent teeth.

• The distance from the occlusal surface to the pulpal floor of the pulp chamber is much less than in permanent teeth.

• In the primary molars, care must be taken not to grind on the pulpal floor since perforation is likely.

• Conical roots of anterior teeth facilitate easy removal. However, flared roots of primary molar dictates that teeth be removed with care. Pre-molar buds are located between the roots. In some instances the primary molars must be sectioned and removed in two pieces to prevent interference during eruption.

• The inter-proximal contacts are broad and flat.• The contacts are restored in a “back-to back” procedure by a

firm wedge at the cervical part.

DISTURBANCES IN SIZE OF TEETHDISTURBANCES IN SIZE OF TEETH

Microdontia - teeth that are smaller than normal. True Generalized Relative generalized

•Macrodontia - teeth that are larger than normal. True Generalized Relative generalized

DEVELOPMENTAL DISTURBANCES OF SHAPE

GEMINATION

Anomaly which arise from an attempt at division of a single

tooth germ by an invagination with resultant incomplete

formation of two teeth.

FUSION

• Union of two normally separated tooth germ before

calcification.

• Dentine is confluent, root canals maybe separate or fused

CONCRESENCE

• Teeth are united by cementum.• May occur before or after the tooth has erupted• Clinical Implication : Radiographic examination is must

before extraction.

DILACERATION

• Angulation or sharp bend in the root or crown.

• Condition is due to trauma during period in which the tooth

is forming. The curve or bend may occur anywhere along

the root.

• Care must be taken during endodontic therapy and

extraction .

TALONS CUSP

• Anomalous structure resembling an eagles talon projecting

lingually from the cingulum areas of a maxillary or

mandibular incisor.

• CLINICAL IMPLICATION: occlusal interference, prone to

caries,

GOOD MORNING!

TOOTH CROWN LENGTH

ROOT LENGTH

ROOT CANALSYSTEM

MAXILLARY INCISORS

5.6- 6 mm 14-16mm 1 canal, no bifurcations,Apical ramifications and accessory canals are rare.Roots curve facially in apical third to half of root.Pulp chamber – fan shaped

MANIBULARINCISORS

5-5.2 mm 9-10 mm Presence of 2 canals are seen in almost 10% of cases. Accessory canals- Rare but observed.

MAXILLARY AND MANDIBULAR CANINE

6-6.5 mm 11.5- 13.5 mm

Rounded , triangular shape with base towards the facial surfaceBifurcations do not occur.Lateral and accessory canals are rare.

TOOTH CROWN LENGTH

ROOT LENGTH

ROOT CANAL SYSTEM

MAXILLARY FIRST PRIMARY MOLAR

5.1mm 10 mm • Bifurcation of mesio-facial root into canals is common and occurs approximately 75% of cases.

• Fusion of palatal and disto-facial approx. 1/3 rd of cases.

• Most cases- 2 separate canals are present

• Islands of dentine may exist between the canals with many connecting branches and fibrils.

MAXLLARY SECOND PRIMARY MOLAR

5.7 mm 11.7 mm Mesio –facial usually bifurcates or contains two distinct canals.

85-95 % Fusion of palatal and distofacial

roots occur. They have a common canal or two canals with a narrow connecting isthmus of dentine islands between them.

TOOTH CROWN LENGTH

ROOT LENGTH

ROOT CANAL SYSTEM

MANDIBULAR FIRST PRIMARY MOLAR

6 mm 9.8 mm 75% of cases show mesial roots contain two canals.

25% cases show distal roots contain more than one canal.

MANDIBULAR SECOND PRIMARY MOLAR

5.5 mm 11.3 mm Mesial root has two canals approximately 85% of the time.Distal root contains more than one canal 25% of the time.

• According to Paras, accessory formina was found in 20% of internal surfaces and 50% of external surfaces of primary molars.

• Wrabs studied the patency of the accesory canals- 30% were accessible in maxillary and mandibular second molars.

• Kramer performed SEM studies on furcations of primary molars. External furcations had a higher prevelance of accesory foramina.

• Presence/ Absence of infection- No effect

Effect of resorption on Canal Anatomy and Apical Foramen

• Newly erupted primary teeth – Apical foramen is seen in the anatomic apices

• During resorption – The foramen do not coincide to the anatomic apex but be more coronal.

Radiographic assessment is quite challenging.

• Resorption can extend into root and root canals creating additional communications with periapical tissues. This has been shown in all levels of the root.

Development Of Vascular Supply In Development Of Vascular Supply In Primary TeethPrimary Teeth

Clusters of blood vessels enter the dental papilla ( CAP STAGE)

Max. number of blood vessels in papilla( BELL STAGE)

Vessels cluster into groups

These areas conicide with positions where the roots will form.

VASCULAR SUPPLY

In the developing tooth germ, the vascular plexus of the dental follicle and dental papilla have a common origin and are intimately related.

This relationship persists throughout the life of the tooth. The apical foramina carry numerous small and large vessels. The individual vessel increases in size after entering the root

canal proper.

VASCULAR SUPPLY

• The veins are located centrally, while arteries are placed peripherally in the root canal.

• In multi-rooted teeth the diaphragm divides the many vessels of the dental papilla into pulp canals, thus establishing a double interradicular vascular flow.

• It is postulated that the anastomoses between the pulpal and the periodontal vascular plexuses is responsible for the extension of disease from one area to another.

• This factor further explains how inflammatory diseases of the periodontal tissue and gingiva may extend to the pulp and how diseases of the pulp may extend to the periodontal tissues, even without the presence of accessory canals

Vascular Supply In Primary TeethVascular Supply In Primary Teeth

• Infra-orbital and posterior superior artery and vein supply the maxillary teeth.

• Mandibular teeth are supplied by the inferior alveolar artery and vein. It enters the mandibular canal and gives off branches to each teeth.

• Mental artery – Lower lip and chin• Incisive artery- Incisors.

• The vascular distribution within pulps of human primary teeth has not been as well studied.

• Small arterioles enter the apical foramen to pass through the root canal to the pulp chamber.

• The dental pulp has a relatively high blood flow. It is estimated to be 40–50ml/min/100g of pulp tissue in a mature tooth as determined by radioactive microsphere techniques. *

(*The Blood Vascular Supply of the Dental Pulp with Emphasis on Capillary Circulation.)

• Using transmission electron microscopy, capillary structures with typical morphological characteristics of lymphatic vessels were found apically.

• The coronal part of the pulp did not reveal any such vascular structures. It may be concluded from these findings that the lymph in the coronal region is collected in interstitial tissue clefts and drained towards the apex and it is further transported via lymph capillaries.**

(**Microsc Res Tech. Lymph drainage in the human dental pulp. Oehmke MJ1, Knolle E, Oehmke HJ)

• Arterioles entered the apical foramina and travelled throughout the root canal(s) to the pulpal chamber, giving off branches which passed toward the dentinal walls.

• Within the pulpal chamber, the arterioles passed toward the occlusal and proximal surfaces and arborized profusely to form a subodontoblastic plexus of capillaries.

The capillaries lead to larger diameter venules, which exited the pulp through apical foramina. Many unusual vascular pathways existed within the root structure. (*J Clin Peditr Dent. 1992 Spring;16(3):183-201.Vascular pathways within pulpal tissue of human primary teeth.)

• Blood vessels present within three regions: the pulp horn, the subodontoblastic region, and the mid-coronal pulp.

• Only the mid-coronal region of the primary tooth pulp was found to be significantly more vascular.

• Significant increase in vascularity within the pulp horn region with caries progression, but this was not accompanied by an increase in vessel number.

(*Vascular status in human primary and permanent teeth in health and disease.)

• The pulp blood flow is under nervous, humoral, and local control. • Inflammatory vascular responses, vasodilation, and increased vessel

permeability induce an increase in IFP that can be followed by a temporarily impaired blood flow response.

• Lipopolysaccharides (LPS) from bacteria may cause endothelial activation in the pulp, leading to vasoconstriction and reduced vascular perfusion. Lymphatic vessels are identified with specific lymphatic markers in the pulp but so far, little is known about their function.

( *Circulation in normal and inflamed dental pulpELLEN BERGGREEN, ATHANASIA BLETSA and KARIN J. HEYERAAS )

• McDonald reported that the localization of infection and inflammation is poorer in the primary pulp.

• Primary teeth, with their abundant vascular supply, demonstrate exaggerated inflammatory response. This accounts for increased internal and external root resorption from calcium hydroxide pulpotomies.

• Following injury vascular congestion may occur, and this may lead to necrosis of the pulp.

CONCLUSION

• There are several reasons that a dentist requires a through understanding of primary tooth morphology. Cavity preparations must conform to the anatomy of the tooth. Restoration of natural contours and morphology of primary teeth is needed for function.

Performance of pulpal procedures, atypical situations and judgement of indicated treatment for primary teeth are also important considerations.

ReferencesReferences

• Wheeler's Dental Anatomy, Physiology and Occlusion.• Shafer'S Textbook Of Oral Pathology (6Th Edition).• Orban's Oral Histology and Embryology.• Clinical Pedodontics, 4th edition -FINN• Woelfel's Dental Anatomy: Its Relevance to Dentistry.• Fundamentals of Pediatric dentistry –Mathewson• Pathways of Pulp- Cohen• Internet.

Questions

• Morphology and histology of primary teeth. how does it influence restorative dentistry?-20(May 2013)

THANK YOU !

anatomy, chronology and vasular supply of primary teeth

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