Quiz 5 Flashcards
Permanent Maxillary Molar Overview
Largest and strongest of the maxillary teeth (size including a broad base and root trunk; anchorage into the jaw- 3 full sized roots with considerable spread); generally they have 4 well formed cusps; the lingual root is the largest of the 3 roots- other 2 are buccal roots; perm. 1st usually emerge at 6 yrs with mandibular preceeding maxillary; NOT succedaneous teeth; space is created for these teeth due to the downward and outward growth of the bones of the face; normal position of the 1st molar is at center of adult jaw anteroposteriorly; 1st molars are sometimes referred to as cornerstones of dental arch
Permanent Maxillary 1st molar overview
Is wider BL than MD; even though the crown is somewhat short, the other measurements provide a large occlusal surface (it is the largest tooth in the max. arch) 4 well developed functioning cusps, one supplemental cusp of little use ( MB,DB, ML, DL, cusp of carabelli [cusp could be well-developed or down to grooves or pits, trait can be used to distinguish populations; located lingual to the ML cusp, Cusp or remnants can be used to identify the 1st molar]) ; roots:MB, DB, L usually well separated giving tooth a strong anchorage to jaw; L root is longest, tapered and rounded, MB root is shorter but has a broad dimension BLingually giving greater resistance to rotation or torsion forces; DB root is the smallest and roundest
Permanent Maxillary 1st Molar Buccal Aspect
Shape is trapezoid; D side can bee seen from B side if sight in at B groove; DB line angle is obtuse; can see parts of 4 cusps; MB cusp is broader than DB, cusp slopes meet at obtuse angle; cusp slopes of DB cusp meet at about right angle; B developmental groove divides the 2 cusps which ends with a slight dip; cervical line (little curvature, though not smooth or regular; may have convexity toward the root); M outline is straight downward and M curving occlusally at contact area (crest or contact area is 2/3 distance cervical line to tip of cusp); D outline is convex, distal surface is spheroid; crest of curvature is half distance from cervical line to cusp tip; contact area is in middle of middle 3rd; may be a flat or concave area on distal surface above DB cusp; all 3 roots are visible with incline to D; MB root curves distally at middle 3rd; D root is straighter; point of bifurcation is about 4 mm above the cervical line (farther than deciduous molars); deep developmental groove starts on root trunk at bifurcation and goes downward becoming more shallow and ends at cervical line; the common root base is called the root trunk; root usually avg. about twice the length of the crown
Permanent Maxillary 1st Molar Lingual Aspect
Outline is the reverse of the B at the M and D; outline of the D blends with the roundness of the DL cusp in a close to perfect semicircle; the line of the L developmental groove is confluent with the outline of the DL cusp as well; the L groove goes M and cervical to about the center of the crown; only the L cusps can be seen from the L; ML cusp the the widest and longest before wear; outline of the M of the crown forms almost a right angle with the ML cusp; ML cusp ridges form an acute angle; DL cusp is round with no angle showing; when the 5th cusp is well developed, the cusp angle is less obtuse and sharper than the ML cusp; L root is conical with a bluntly rounded apex
Permanent Maxillary 1st Molar Mesial Aspect
One can see the increase in the BL dimension and the cervical curve outlines (buccally cervical line is a short arc to the B to crest at cervical 3rd; there is a shallow concavity just occlusal to crest; from there it is a slight convexity to the tip of the cusp) lingual outline of the crown ( crest of curvature is in the middle 3rd; if a 5th cusp is present, there will be a dip inward in the outline- if not, it’s smooth curve; point of cusp is more centered in the root base than are the B cusps with the cusp in line with the long axis of the L root) MMR is irregular, curves cervically, centered with crown buccolingually (curve of cervical line is not more than 1mm- centered above the contact area); M contact area is closer to the marginal ridge than to the cervical line at junction of the middle and occlusal 3rd, and B to center BL; MB root (broad and flattened on the M surface often with flutings partway, width near the crown is about 2/3 the width of the crown; extends upward and outward with blunt apex, extension does not extend past the extension of the crown; bifurcation is closer to the cervical line than that on the B) there is a smooth depression going from the bifurcation onto root base ending just above the cervical line and above the ML line angle of the crown; L root is longer than the MB root, and narrower
Permanent Maxillary 1st Molar Distal Aspect
Variations from M: will see most of the B surface due to distal taper; BL measurement is greater at the M than the D due to the slant of the B surface; DMR dips more sharply to cervical than does M (exposes the triangular ridges); cervical line is most straight across; D surface is more convex except a small area at DB root at cervix which concavity extends onto DB root; DB root is narrowest of the 3 at its base- this root is S shaped going inward then outward to a rounded apex
Permanent Maxillary 1st Molar Occlusal Aspect
Somewhat rhomboidal especially when following the outline of the 4 major cusps and the marginal ridges, BL measurement is greater at the M, MD measurement is greater just lingual to contact areas than that just B to contact areas; crown is wider M than D and L than B; 4 well developed major cusps; size in order of cusps: ML, MB, DL, DB, 5th cusp; acute angles (MB, DL), obtuse angles (ML, DB); primary cusps- ML and 2 B cusps form the Max. molar primary cusp triangle (outline of 3 cusps, MMR, oblique ridge [made from the union of the triangular ridge of the DB cusp and the D ridge of the ML cusp. It crosses the occlusal surface obliquely]); central fossa and distal fossa are the major fossa; minor fossa are the M and D triangular fossa; oblique ridge crosses the occlusal surface diagonally (loses height at center of the occlusal surface same level as marginal ridges; sometimes has a developmental groove crossing it) central fossa is concave and usually has a central pit with sulcate grooves radiating (also has a B developmental groove extending onto the B; has a central developmental groove going M ending in the M triangular fossa-joined by supplemental grooves from cusp) M triangular fossa- base is marginal ridge, apex is at point where supplemental grooves join the central groove; transverse groove of the oblique ridge goes over the oblique ridge when one is there; groove that outlines 5th cusp is called the 5th cusp groove; D oblique groove has several supplemental grooves; may be a slight concavity in the DMR; DL cusp is smooth, rounded from the concavity, cusp ridge extends farther L than the ML cusp
Permanent Maxillary 2nd Molar Overview
roots are as long as, and sometimes longer than the 1st molar; DB cusp is not as large as or as well developed than the 1st; DL cusp is smaller; no 5th cusp; crown is about 0.5 mm shorter from cervical to occlusal; measurement BL is about the same; occlusal shape may be similar to 1st molar or it may resemble a 3rd molar; with a poorly developed DL cusp, the other 3 will be more prominent; this give the tooth a heart shape
Permanent Maxillary 2nd Molar Buccal Aspect
Crown is shorter and narrower than first; DB cusp is smaller with some of the DMR exposed
Permanent Maxillary 2nd Molar Lingual Aspect
Differs from 1st: DL cusp is smaller; DB cusp may be seen through the area between the ML and DL cusps; No 5th cusp is evident; apex of lingual root is in line with DL cusp tip, not with the L groove as 1st milar
Permanent Maxillary 2nd Molar Mesial Aspect
roots are not as spread, and are within the confines of the crown outline
Permanent Maxillary 2nd Molar Distal Aspect
D can see some of the MB cusp due to smaller DB cusp
Permanent Maxillary 2nd Molar Occlusal Aspect
MB and ML cusps are as large and well developed as the 1st; DB and DL cusps are smaller and less developed; usually find more supplemental grooves, other grooves and pits than first molar
Permanent Maxillary 3rd Molar Overview
Less well developed; usually resemble the 2nd; crown is smaller, roots are shorter, and sometimes fused; will show a lot of variations with some resembling none other
Permanent Maxillary 3rd Molar Buccal Aspect
crown is shorter and narrower MD; roots are usually fused so that it looks like a single root, ending in taper at apex
