Chronology–
FIRST EVIDENCE OF CALCIFICATION – 1.5 YEARS TO 1 YEAR 9 MONTHS
ENAMEL COMPLETION – 5-6 YEARS
ERUPTION – 10-11 YEARS
ROOT COMPLETION – 12 – 13 YEARS
DIMENSIONS–
LENGTH OF THE CROWN – 8.5MM
LENGTH OF THE ROOT – 14.00MM
LENGTH OF THE MESIODISTAL DIAMETER OF THE CROWN – 7.00MM
LENGTH OF THE MESIODISTAL DIAMETER OF THE CROWN AT THE CERVIX -5MM
LENGTH OF THE BUCCOLINGUAL DIAMETER OF THE CROWN -9MM
LENGTH OF THE BUCCOLINGUAL DIAMETER OF THE CROWN AT THE CERVIX – 8MM
BUCCAL ASPECT-
1.THE CROWN IS ROUGHLY TRAPEZOIDAL IF WE WILL SEE IT FROM THE BUCCAL ASPECT.
2.IT SHOWS VERY LESS CURVATURE AT THE CERVICAL LINE.
3.THE CREST [TOP] OF THE CURVATURE OF THE CERVICAL LINE BUCCALLY IS NEAR THE CENTRE OF THE ROOT BUCCALLY.
4.THE MESIAL OUTLINE IS SSLIGHTLY CONCAVE IF WE MOVE FROM THE CERVICAL LINE TOWARDS THE MESSIAL CONTACT AREA.
5.THE MESIAL SLOPE OF THE BUCCAL CUSP IS STRAIGHT AND LARGER AS COMPARED TO THE DISTAL SLOPE AS THE DISTAL SLOPE OF THE BUCCAL CUSP IS SHORTER AND MORE CURVED.
6.THE DISTAL OUTLINE OF THE CROWN WHICH IS JUST BELOW THE CERVICAL LINE IS MORE STRAIGHT AS COMPARED TO THE MESIAL OUTLINE. BUT IT IS ALSO SOMEHOW CONCAVE.
7.THE CONTACT AREASE ARE MORE NEARLY LEVEL WITH EACH OTHER THAN THOSE FOUND ON THE ANTERIOR TOOTH.
8.BUCCAL CUSP IS LONG AND POINTED WHICH RESEMBLES WITH THAT OF THE CANINE.
9.THE BUCCAL SURFACE OF THE CROWN IS CONVEX WHICH SHOWS THE STRONG DEVELOPMENT OF THE MIDDLE BUCCAL LOBE.
10.THE CONTINUOUS RIDGE FROM CUSP TIP TO THE CERVICAL MARGIN ON THE BUCCAL SURFACE OF THE CROWN IS KNOWN AS THE BUCCAL RIDGE.
11.MESIAL AND DISTAL TO THE BUCCAL RIDGE , DEVELOPMENTAL DEPRESSIONS ARE USUALLY SEEN THAT SERVE AS THE DEMARCATIONS BETWEEN THE MIDDLE BUCCAL LOBE AND MESIOBUCCAL AND THE DISTOBUCCAL LOBE.
12.THE ROOTS ARE 3 OR 4MM SHORTER THAN THOSE OF THE MAXILLARY CANINE.
LINGUAL ASPECT
1.THE GROSS OUTLINE OF THE MAXILLARY 1ST PREMOLAR FROM THE LINGUAL IS THE REVERSE OF THE GROSS OUTLINE FROM THE BUCCAL ASPECT.
2.CROWN TAPERS TOWARDS THE LINGUAL AS THE LINGUAL CUSP IS NARROWER MESIODISTALLY AS COMPARED TO THE BUCCAL CUSP.
3.LINGUAL CUSP IS SMOOTH AND SPHEROIDAL FROM THE CERVICAL PORTION TO THE AREA OF THE CUSP TIP.
4.THE CUSP TIP IS POINTED AND MESIAL AND THE DISTAL SLOPES MEET WITH EACH OTHER AT 90 DEGREES.
5.THE SPHEROIDAL PORTION OF THE CROWN OF THE LINGUAL ASPECT IS CONVES AT ALL THE POINTS.
6.THE SMOOTH LINGUAL PORTION WHICH TERMINATES AT THE POINT OF THE LINGUAL CUSP IS KNOWN AS THE LINGUAL RIDGE.
7.THE MESIAL AND THE DISTAL OUTLINE OF THE LINGUAL PORTION OF THE CROWN IS ALSO CONVEX.
8.THE MESIAL AND THE DISTAL OUTLINE CONTINUES WITH THE MESIAL AND THE DISTAL SLOPES OF THE LINGUAL CUSP.
9.THE MESIAL AND THE DISTAL OUTLINE IS ALMOST STRAIGHT AT THE MESIAL AND THE DISTAL SIDE OF THE ROOT NEAR THE CERVICAL LINE FROM THE LINGUAL ASPECT.
10.THE CERVICAL LINE IS REGULAR , IT SHOWS SLIGHT CURVATURE TOWARDS THE ROOT AND THE CREST OF THE CERVICAL LINE IS CENTRED ON THE ROOT.
11.IF WWE WILL SEE THE ROOT OF THE LINGUAL PORTION THEN IF TWO ROOTS ARE PRESENT , IT IS SMOOTH AND CONVEX AT ALL THE POINTS.
12.THE APEX OF THE LINGUAL ROOT OF THE TWO ROOT SPECIMEN TENDS TO BE BLUNTER THAN THE BUCCAL ROOT APEX.
MESIAL ASPECT
1.THE MESIAL ASPECT OF THE CROWN IS ROUGHLY TRAPEZOIDAL IN SHAPE.
2.THE MEASUREMENT FROM THE TIP OF THE BUCCAL CUSP TO THE TIP OF THE LINGUAL CUSP IS LESS AS COMPARED TO THE BUCCOLINGUAL MEASUREMENT OF THE ROOT AT ITS CERVICAL PORTION.
3.THERE ARE MANY MAXILLARY 1ST PREMOLARS WHO HAVE TWO ROOTS THAT IS BUCCAL ROOT AND THE LINGUAL ROOT , ALL THESE ARE CLEARLY OUTLINED FROM THE MESIAL ASPECT.
4.THE CERVICAL LINE MAY HAVE REGULAR OR IRREGULAR OUTLINE.
5.THE BUCCAL AND THE LINGUAL CUSPS ARE VISIBLE BOTH FROM THE MESIAL AND THE DISTAL ASPECT.
6.MESIAL MARGINAL RIDGE AND THE MESIAL MARGINAL DEVELOPMENTAL GROOVE ARE ALSO SEEN
7.MESIAL DEVELOPMENTAL DEPRESSSION IS ALSO PRESENT WHICH CROSSES THE CERVICAL LINE.
8.THE OCCLUASAL MARGIN IS CONCAVE IRREGULARLY AND MOST OF THE PARTS ARE MADE UP OF MESIAL MARGINAL RIDGES.
DISTAL ASPECT
1.THE DEVELOPMENTAL GROOVE / THE DEVELOPMENTAL DEPRESSIONS ARE ABSENT AND IT IS CONVEX AT ALL THE POINTS FROM THE DISTAL ASPECT.
2.THE CURVATURE OF THE CERVICAL LINE IS LESS AS COMPARED TO THE MESIAL ASPECT.
3.THE CONTACT AREA IS PRESENT AT THE OCCLUSAL THIRD AND THE MIDDLE THIRD.
4.DISTAL ASPECT IS SIMILAR TO THE MESIAL ASPECT BUT OCCLUSO-CERVICALLY IT IS SLIGHTLY SHORTER.
5.LINGUAL MARGIN IS SLIGHTLY CONVEX AND MOSTLY SYMMETRICAL.IT IS ESPECIALLY IN THE MIDDLE THIRDS WHERE THE HEIGHT OF COUNTOUR IS PRESENT.
6.MARGINAL GROOVE IS ABSENT.
OCCLUSAL ASPECT
TBC – TIP OF BUCCAL CUSP
TLC – TIP OF LINGUAL CUSP
BTR – BUCCAL TRIANGULAR RIDGE
LTR – LINGUAL TRIANGULAR RIDGE
DBDG – DISTO-BUCCAL DEVELOPMENTAL GROOVE
DTF- DISTAL TRIANGULAR FOSSA
MTF – MESIAL TRIANGULAR FOSSSA
CG – CENTRAL GROOVE
DBCR – DISTO BUCCAL CUSP RIDGE
MBCR – MESIO BUCCAL CUSP RIDGE
THE OUTLINE OF THE CROWN IS HEXAGONAL IN SHAPE.
IT IS WIDER BUCCOLINGUALLY AS COMPARED TO THE MESIODISTALLY.
LINGUAL MARGIN IS SEMI CIRCLED OR CONVEX IN SHAPE.
ROOT
MOST OF THE MAXILLARY 1ST PREMOLARS HAVE 2 ROOTS BUT THERE ARE SOME PREMOLARS WHO CAN HAVE 1 OR 3 ROOTS ALSO.
NAME OF THE 2 ROOTS ARE BUCCAL ROOT AND LINGUAL ROOT.
BUCCAL PORTION OF THE ROOT RESEMBLES WITH THAT OF THE CANINE.
BIFURCATION AREA IS SEEN WHERE THE BUCCAL AND THE LINGUAL ROOTS GET SEPARATED.
A DEVELOPMENTAL DEPRESSION IS SEEN ON THE MESIAL ASPECT OF THE TOOTH
Contributor- Medico Abinash Jena
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