Mandibular First Premolars

Mandibular First Premolars

• Considered a transitional zone in the oral cavity.

Resemblances to Mandibular Canine

• Buccal cusp is long and sharp, being the only occluding cusp.
• The buccolingual measurement is similar to that of a mandibular canine.
• The outline from an occlusal aspect resembles the outline from the incisal aspect of the mandibular canine.

Resemblances to Mandibular Second Premolar

• The outline of the crown and root resembles that of a mandibular second premolar when viewed from the buccal aspect.
• Mesial and distal contact areas are nearly at the same level.
• It has more than one cusp.

Chronology

• First evidence of calcification occurs between 1¾–2 years.
• Crown completion happens around 5–6 years.
• Eruption occurs at approximately 10–12 years.
• Root completion takes place around 12–13 years.

Buccal Aspect

• The geometric outline is trapezoid.
• The mesial outline is slightly concave.
• The distal outline is slightly concave.
• Mesial contact area is at the junction between the middle and occlusal thirds
• Distal contact area is just occlusal to the middle of the middle third.
• The tip of the buccal cusp is sharp and located mesial to the center of the tooth.
• The distal slope of the buccal cusp is longer than the mesial slope.
• The cervical line is convex root-wise.
• The cervix of the mandibular first premolar crown is narrow mesiodistally, indicating more cervical constriction.
• The buccal surface is generally smooth and convex, except for the well-developed buccal ridge (middle labial lobe) and shallow depressions on either side of the ridge.
• A single root tends to curve distally.

Lingual Aspect

• General outline is a reversed picture of the buccal surface.
• There is a marked increased lingual convergence.
• The lingual cusp is pointed and shorter than the buccal cusp, measuring only 2/3 of the crown length.
• The lingual cusp is short, less developed, and non-functional.
• The mesiolingual developmental feature is continuous from the central groove.
• It extends between the mesial marginal ridge and mesiolingual cusp ridge onto the lingual surface mesially.
• Roots are narrower than the buccal and taper to a pointed apex.

Mesial Aspect

• Geometric outline is rhomboidal.
• Buccal outline is convex from the cervical line to the buccal cusp tip, with the crest of curvature at the junction of the cervical and middle thirds.
• Lingual outline is more convex, creating an overhang of the crown over the root, the crest of curvature is at the center of the middle third.
• The occlusal surface slopes greatly toward the lingual in a cervical direction down to the short lingual cusp due to lingual tilting.
• The convexity of the outline of the lingual lobe is lingual to the outline of the root due to lingual overhang, the crown presents an overhang above the root trunk in the lingual direction.
• The buccal cusp is centered over the root, with the "tip of cusp" aligned with the center of the tooth.
• The lingual cusp tip is in line with the lingual outline of the root.
• The lingual cusp is 2/3 of the buccal cusp, making the buccal cusp the only occluding cusp and the lingual cusp non-functioning.
• The cervical outline is concave root-wise.
• The surface is smooth except for the mesiolingual developmental groove, and the mesial marginal ridge slopes lingually.
• The root outline from the mesial aspect is parallel until the apical third, then it tapers, giving a pointed apex, and there is a deep developmental groove on the root surface.

Distal Aspect

• It shares similarities with the mesial aspect, except
• The distal marginal ridge is perpendicular to the axis of the crown and root.
• There is no mesiolingual developmental groove.
• Curvature of the cervical line is less pronounced.
• The distal surface of the root exhibits more convexity.
• There is a shallow developmental depression on the root surface.

Occlusal Aspect

• It is diamond or circular in shape.
• The geometric outline follows the rule that the buccolingual measurement is greater than the mesiodistal measurement, and the buccal measurement is greater than the lingual measurement (BL>MD - B>L)
• The crown converges sharply towards the centre of the lingual surface.

Elevations

• The buccal cusp is larger, comprising the major portion of the crown.
• The lingual cusp is smaller.
• The mesial marginal ridge is shorter than the distal marginal ridge.
• It is constricted by the mesiolingual developmental groove and slopes sharply lingually in a cervical direction.
• The two buccal and lingual triangular ridges meet, forming a transverse ridge.

Depressions

• Central developmental groove is crescent-shaped with two mesial and distal developmental grooves flaring towards the buccal.
• Mesiolingual developmental groove passes over the mesial marginal ridge onto the lingual surface mesially.

Fossae

• Mesial triangular fossa is linear.
• Distal triangular fossa is more circular and larger.

Second Premolar

• The second premolar has a generally larger crown and root than the first premolar.
• There are two general forms; one with two lingual cusps, the other with one.
• The primary difference between the two forms is in occlusal morphology, other surface contours are similar.
• Regardless of the number of lingual cusps, the occlusal table more resembles a small molar.

Chronology of Mandibular Second Premolar

• First evidence of calcification occurs around 2¼–2½ years.
• Crown completes at approximately 6–7 years.
• Eruption happens at 11–12 years.
• Root completes nearly 13–14 years.

Buccal Aspect of Second Premolar

• Geometric outline is trapezoid.
• Mesial outline is convex.
• Distal outline is more convex.
• This premolar resembles the first premolar from the buccal with certain distinctions:
  • The teeth is slightly larger.
  • The buccal cusp tip is not as high, less sharp
  • Cusp tip is centered mesiodistally, slopes of cusp are approx equal in length,
  • Contact areas both mesial & distal even "juntion b/w middle occlusal 3rds"
  • Root is broader mesiodistally with a blunter apex

Lingual Aspect of Second Premolar

• General outline is a reversed picture of buccal surface.
• Lingual cusps are not as long as the buccal cusp, so parts of the portion can be seen.
• Lingual cusps are more than 2/3s of the crown length.
• Three-cusp Type:
  • Mesiolingual and distolingual cusps are present.
  • Mesiolingual cusp larger/longer than distolingual.
  • A lingual groove, between them extending only a short distance and centered.
  • There is no lingual convergency.
• Two-cusp Type:
  • A single lingual cusp is displayed.
  • No lingual groove.
  • Single cusp ~ same height mesiolingual cusp of three-cusp type.
  • Little lingual convergency.

Mesial Apect of Second Premolar

• This is similar the first premolar. There are however differences
  • Wider bucco-lingually.
  • Shorter occluso-cervically
  • It the buccal cusp is no center it its rather shifted. Also it buccal cusp is not as sharp.
  • The crest of curvature is lingually and is unqiue to this tooth.
  • No mesiolingual developmental groove on the scond premolar.

Distal Aspect of the Second Premolar

• It is similar but
• The distal margin ridge is higher cervically
• The third cusp when it there is shorter
• There is lower concavity
• No mesiolingual groove

Occlusal Aspect of Mandibular Second Premolar

• There are 2 common of occulsal morphology
  • 3-cusps follows "Y groove" pattern
  • 2-cusps follows "U or H groove" pattern pattern

General Notes on 3 Cusp Type

• Crown shapes is squarelike w/nearly equal mesiodstal crown.
• Buccal cusp being the largest followed Mesiolingual & Distolingual.
• Mesiolingual wider & distal marginal ridges are well marked.

Notes on Depressions

• The central pit is midb/w buccal & lingual. The mesial pit radiates development pattern from M-D. the lingual grove is also froms 2 lingual cusps from crown surface.

###General Notes on the 2-Cusp Type -Shape is either circular. The two cusps are Buccal are Lingual which form a transerve groove.

Maxillary Molars

• The permanent maxillary molars are the three most posterior teeth in each upper quadrant.
• Molars are named as First(six year), Second(twelve year), Third(wisdom tooth)

First Molar Characteristics

• Maxillary First Molar is the largest tooth in the maxilary and will have 4 developed cusps and also has one supplemental cusp. the are mesiobuccal, distobuccal, the mesiolingua & the distolingual
• That supplemental cusp is called 'Carabelli's Tubercle" and usally found lingual

Chronology for first and second Maxillary Molars

• First molar evidence At Birth
• 2nd Molar occurs 2 1/2 - 3 Years after birth
• First Molar crown completes 3-4 years
• 2nd molar crown completes 7-8 years
• First molar Erupts 6-7, 2nd molar 12-13 yrs old
• First molar completes root 9-10 years 2nd molar 14-16 years

Buccal Aspecft

• It has trapezoid shape w/short uneven cervial sides with occluscal
• It has startight starting cervical to mesial. The mesial outline becomes slightly convex at outline. and then the outlines are convex starting w/the occlusal outlines"
• The mesial is at junction b/w middle/occlusal & distal id dlwe center.
• all cusps can be seen and the lingual culps are londer then buccsl once

• Occlusal outine of meso/distal cusps and their slopes

• Mesiobuccal being widest and the slopes form abtuse angles
• The distal cusps are pointed and the meet an right angle
• The cervical line shapes Irregular & slightly convex

• The buccal de developmental groove separates the buccal cusp runs for 1/2 the buuccal surface and the "buccsl pit"

• The three roots can be seen :Mesuobuccal/ Distobuccal/ Distal , and is 4mm away" The distal surface is concave

Palatal Aspect

• The measial line shapes straight. The cusps can be seen (Mesiolingual/Distal)
• The cervical like is nearly straight."Carabelli"
• "The three roots are seen from the lingual/ they're mostly larg and are cornical with blunt apex

• Notes there is not really Lingual concemerge in the first molar

Mesial Aspect

• "Geomtric Trapezoid w/ the smallest side being on the occlusal and crest. That is at mid cervicals"
• "Its Mesiolingual, Mesiobuccal+5th cusps/The axis lines up w/ the roots. The cervical curve is the sligh concave root".There concave cervical is when the root trunk extends
• Contact Area is where crown is and more towards buccally. This is where the edge meets, and the cusps line up
• the roots make approx 2/3 of Buccal measurement. The outlines buccal outwards and straght lingual . Distial root and almost hidden behind mess

Distal Aspect

• The distal is more Narrower the center . Marginal Ridge
• The 4 major cusps are all "shorter"
• the 2 sides ar lined more closed on
• The sides the has has
• A
• Concave sides

Occlusal Aspect

• "Geometry is rhobodal 2/atue ""mesio""lingal and obtuse angles Distallly/The B Side > Medial .C does not show convergence in permenent teeth
• Wider mesaillly and ligulally.The 3 major cusps are mesiloigual is the first and secondary .3 for triangle is same in all maxillary Molar

Cusp Arragngment for molars

"" according to mesial then the 4cusp " Mesial/Buccal > Distal/lingual
The 5th cusop May

• Not be preset
• Obliuge Ridhes from the traigle Ridge
• Mesial .the mesial triagke ridges

First Mandibular Molar

• The first mandibular molar, which is the initial permanent tooth to erupt, is positioned sixth from the midline.
• It sits distal to the second deciduous molar and is not a succedaneous tooth.
• Being the first to erupt it is referred to as a "six-year molar.
• It holds position of occlusion in the mandibular arch.
• This molar makes a mesial contact w/2nd deciduous molar which is appriox 5/years, then replaced it does not contact distal side until the 2nd has errupted.
• This is the biggest of all molar teeths. It has wide cusps & big roots.

###Chronology

• The 6 Year
• The molar arrivers at brith. Its crowm takes 2/1 half to complete 3 years."
• The erupts at six/seven / its trunk completion for root almost ten years +a few yrs.

The crown of a molar

It’s that're shape and gets smaller mesailly its convex makes. I had cervical curve with the projection. It is made from 2 lingua cups,

Mesial Outline,

is con to the middle with the contract spot and this is by the junction

the teeth are

Distial to straigh to the cervial. It curve and is 3. Cervical tip is pointed

The cusps ar everywherrreererr

Its form in the buccal sides. And a smal