End Exam 1 Material

Question 1

Orofacial Complex: Form and Function

Answer 1

Shape plays an important part with function with the teeth; Speech, jaw function, arch form, temporomandibular joint function, integration of form, function, esthetics

Question 2

Form follows function

Answer 2

Form also has to do with the biomechanical contributions in maintaining function; is a relationship between esthetics and optimal occlusion; physical forces and periodontal ligaments; again TMJ function; proper articulation of teeth is important (Curve of Spee- A to P)

Question 3

Fundamental Curvatures

Answer 3

Tooth form also relates to the form of supporting structures (food impaction, trauma to gingival tissues); self cleansing properties may be in question; Considerations with form in restorations (proximal contacts, interproximal spaces, embrasures (spillways), labial and buccal contours at cervical thords (cervical ridges) and lingual contours , curvature of cervical lines on mesial and distal surfaces

Question 4

CONTACT AREA

Answer 4

Term used to denote the proximal heights of contour of the mesial or distal surface of the tooth that touches its adjacent tooth in the same arch; these are areas not points, reason for proper contact area (prevents food from packing between teeth which may become pathological, provides stabilization for arch, each tooth gets some support from proper contact mesial, distal 3rd molars excluded; 3rd and 2nd molars don’t drift distally due to angulation of occlusal surfaces and roots; pathological conditions include gingivitis, bone loss with attachment loss (periodontitis), contact areas must be observed from 2 views facial and occlusal; excessive occlusal forces can also result in loss of supporting tissues

Question 5

proximal contact

Answer 5

proximal convexity of the teeth create area of contact between adjacent teeth with in the same arch; called proximal contact area; initially as teeth erupt the teeth contact each other at a point (point contact). WIth the passage of time, physiologically tooth movement causes frictional wear enlarging the contact point to contact area; mesial generally higher than distal- as move posteriorly, get closer to cervix

Question 6

Importance of contact

Answer 6

Preserve the stability and integrity of the arch by maintaining normal mesio distal relationship of teeth, prevents food impaction interdentally, protects the soft tissue from periodontal disease, conserve the teeth from proximal caries, premature restorative failure doesn’t occur if stable proximal contact is present

Question 7

Contours on the proximal surface

Answer 7

Teeth show convexities on the D and M surface; the area with max convexity on the proximal surface is the proximal height of contour; proximal height of contour responsible for the creation of the proximal contact and embrasure space

Question 8

Size of contact

Answer 8

Anteriorly (contact point), Posteriorly ( contact area about 1.5-2mm); location of contact (anterior teeth is at incisal one third but posterior teeth is at junction of incisal and middle one third)

Question 9

Interproximal spaces

Answer 9

Triangular in shape to allow for gingival papillae- base is alveolar process, apex contact area, proximal surface of the teeth form the sides of the triangle; size and shape varies with the individual teeth; normally there will be 1-1.5mm between CEJ and crest of alveolar bone; surface keratinization and dense elastic fibers maintain gingival tissues from more trauma from mastication and bacterial invasion; narrowing of the teeth at the cervix and tapering of roots allow for the proper anchoring of the teeth and tissues

Question 10

Embrasures

Answer 10

Curvatures adjacent to the contact areas are the embrasures or spillways; will be labial or buccal, and lingual interproximal embrasures;also have incisal or occlusal embrasures; individual teeth; embrasure is bigger on the lingual; maxillary 1st molar is the opposite of this because its wider on the lingual surface than buccal surface

Question 11

Contours

Answer 11

It is the term used to denote some degree of convexities and concavities on the facial/buccal and lingual surfaces of all the teeth that affords protection to the supporting tissues during mastication; all teeth have some specific convexity on the facial, lingual, proximal and occlusal surface of teeth that afford the protection and stimulation of the supporting tissues during mastication; this convexity are called contours (Types: faciolingual, proximal and occlusal contour)

Question 12

facial and lingual contours

Answer 12

all tooth form have some effect on stabilization of the tooth in the arch; buccal and lingual contour deflect food away from gingival margins during mastication (under contouring can lead to food impaction; overcontouring significance is under review) Labs tend to overdo the contours when they do crowns ; facial surface- cervical one third of all teeth; lingual surface- cervical one third of incisors and canines, middle one third of the premolars and molars

Question 13

Problems of over or under contouring of the facial and lingual surface

Answer 13

Over contoured restoration- they deflect food from the gingiva causing poor gingival stimulation. The gingiva becomes flabby, red, and chronically inflamed due to increased plaque retention. (food retention under overcontour with consequent caries or gingivitis)

Under contoured restoration- This results in irritation and trauma to the attachment apparatus; direct impact of food on supporting tissues causing trauma to them

Question 14

Height of the Epithelial attachment- curves of the cervical lines

Answer 14

attachment seals the soft tissue to the tooth; can adjust to different conditions and changes; very vulnerable to injury caused mostly by careless treatment; this can create an ongoing pathologic condition- more breakdown; height of the gingival tissue mesially and distally is directly related to the height of attachment; normal attachment follows the curvature of the cervical line (this is assuming normal tooth alignment and contact with other teeth; they only follow the same curvature; extent of curvature depends on size and diameter of the crown labiolingually, buccolingually)

Question 15

Practical application

Answer 15

When restoring anterior teeth, be aware of the height of attachment; posterior teeth have less accentuated curves; if in doubt, use the perio probe before operative procedures; also need to use caution when using impression material

Question 16

Permanent Mandibular Premolars

Answer 16

20,21, 28,29
Lower 1st premolar:4, lower 2nd premolar: 5

Mandibular 1st premolars are developed from 4 lobes, as are the maxillary premolars; mandibular 2nd premolars mostly derived from 5 lobes- 3 buccal, 2 lingual; 1st premolar has long, well formed buccal cusp, small nonfunctioning lingual cusp (almost like a cingulum found on a canine); 1st premolar resembles a canine since only the buccal cusp is in occlusion and is generally smaller of the 2 (opposite of the maxillary premolars); 2nd premolars has 3 well formed cusps- one large buccal cusp and 2 smaller lingual cusps (exception to the one developmental lingual lobe in others); 2nd premolar is more like a small molar due to the high horizontal marginal ridges; neither are real “bicuspids”

Question 17

Mandibular First premolar

Answer 17

Resembles a canine (long sharp buccal cusp [and is the occluding cusp], only one in occlusion; BL measurement is similar; occlusal surface slopes lingually in cervical direction; MB cusp ridge is shorter than DB; outline form of the occlusal resembles the canine)

Resembles the 2nd premolar ( outline of crown and root from B are similar except for longer cusp; M and D contact areas are nearly same level; cervical line curvatures M and D are similar; tooth has more than one cusp) Root of the 1st premolar is usually shorter than 2nd

Question 18

Buccal aspect of the mandibular first premolar

Answer 18

Form is nearly symmetrical bilaterally; middle lobe is well developed with large pointed cusp; broad contact areas at nearly the same level; shape is trapezoidal; cervical line from buccal has very little curvature; M outline is straight above cervical line, may show slight concavity to contact; outline of mesial cusp ridge may show concavity before wear; tip of buccal cusp is pointed and just mesial to center of crown; distal outline has slight concavity above the cervical line to contact area; root is usually 3-4mm shorter than mandibular canine; buccal surface is more convex than maxillary premolars; will see developmental depressions between the 3 lobes; a buccal ridge is present from cusp to cervical margin ; D contact area is more occlusal than the M contact area therefore mesial contact is lower (an exception to the rule)

Question 19

Lingual aspect of the mandibular first premolar

Answer 19

Crown tapers (converges) toward the lingual (narrower on L side than B); lingual cusp is small and pointed; looks like a canine from the L; due to taper to the L, M and D surfaces can be seen from L; occlusal surfaces slopes to the L to the short L cusp; most of the occlusal surface can be seen; cervical part of crown is narrow, convex, and concavities are seen between contacts and cervical line; contact areas and marginal ridges are prominent and extend past narrow cervix; lingual cusp though small is sharp and pointed and is in line with buccal triangular ridge with M and D occlusal fossae present on either side of ridge; ML developmental groove (is a boundary of the MB lobe and the lingual lobe; extends into the M fossa on the occlusal surface; helps determine left from right); root is also narrower from lingual with a ridge extending the full length; can see depressions in the root with M being more of a groove; ONLY tooth in mouth where the mesial marginal ridge is more apical than the distal marginal ridge

Question 20

Mesial aspect of the mandibular first premolar

Answer 20

Outline is rhomboidal (same with all mandibular posteriors) tip of buccal cusp is nearly centered over the root; convexity of lingual outline extends past the root trunk; convexity of buccal outline goes from cervical line with crest near middle third; convexity and crest holds for all mandibular posteriors from buccal; crest on lingual is near the middle third and may be in line with lingual border of root; distance from cervical line to lingual root is about 2/3 that of buccal; MB lobe development is prominent with prominent marginal ridge (MMR is lower than DMR); ML developmental groove is seen; can see some of the occlusal surface (more so than on the distal); triangular ridge parallels the marginal ridge; cervical line curves occlusally by about 1 mm or it may be straight across; surface is smooth except for the developmental groove; just below the contact area there is a concave area going to the cervical line; mesial surface of the root is smooth from buccal to center- developmental groove or even shallow depression may end in a bifurcation at apical third (have a shallow root depression in the apical and middle thirds of both M and D root surfaces)

Question 21

Distal aspect of the mandibular first premolar

Answer 21

DMR is higher than M with less lingual slope and may be at right angles to the crown and root; most of the surface of crown is convex, smooth with unbroken curve; D contact area is broader than the M; curvature of cervical line is about the same as the M; surface of the root is more convex than M; D surface slopes more gradually toward the lingual than the M

Question 22

Occlusal aspect of the mandibular first premolar

Answer 22

Most common shape is diamond converging lingually- similar to that of mandibular canine; other shape is circular; shape of crown is asymmetrical (more bulky on the distal); some will be like mandibular 2nd premolars; have much variation in the occlusal morphology;

Question 23

Characteristics common to all

Answer 23

Middle buccal lobe is most of the bulk of the tooth; prominent buccal ridge; rounded yet prominent MB and DB line angles; broad contact areas just L to B line angles, D broadest; crown converges from contact area rapidly to lingual; well developed marginal ridges; lingual cusp is small; buccal triangular ridge on occlusal is heavy, lingual triangular ridge- small; 2 depressions on occlusal surface are the M and D fossae; most forms have a ML developmental depression groove which makes the M contact area small so that it contact with canine; Mesial fossa is linear in form from which the M developmental groove goes BL; distal fossa is circular and may have a distal developmental groove or crescent shaped; most of the buccal surface can be seen from the occlusal view

Question 24

Mandibular 2nd premolar

Answer 24

Resembles the 1st premolar from only the buccal view; less pronounced B cusp; is larger and better developed

2 common forms: 3 cusp and is more angular (most common) and 2 cusp; single root is larger and longer, seldom bifurcated. May see deep developmental groove buccally

Question 25

Buccal aspect of mandibular 2nd premolar

Answer 25

Buccal cusp is shorter than 1st premolar and shows less angulation; contact areas appear higher due to shorter cusp; root is broader MD than 1st premolar; apex of root is more blunt

Question 26

Lingual aspect of mandibular 2nd premolar

Answer 26

Variation from 1st premolar; lingual lobes have more development, cusp are longer; see less of occlusal surface (part of B portion of occlusal surface may be seen); in the 3 cusp, ML cusp and DL cusp are seen- ML is the largest and longest of the 2; In the 2 cusp type, lingual cusp is as long as the 3 cusp type and may show a developmental depression where the lingual cusp ridge joins the DMR; root is wide, not as wide as the B portion with less lingual convergence than the 1st premolar

Question 27

Mesial aspect of mandibular 2nd premolar

Answer 27

crown and root are wider BL than 1st; buccal cusp is not centered over root and is shorter than 1st; greater lingual lobe development; marginal ridges are at right angles to long axis of tooth; see less of the occlusal surface (Mesial is higher); No ML developmental groove; root is longer, slight convexity on mesial surface; apex is more blunt on the 2nd

Question 28

Distal aspect of mandibular 2nd premolar

Answer 28

Similar to Mesial except more of the occlusal surface may be seen (distal contact is lower; opposite of 1st) ; marginal ridge is at a lower level than the Mesial (can see more of the occlusal); crowns of all posterior teeth dip distally part of the curve of spee ( starts at 1st premolar which has the highest marginal ridge and then starts going down as you move posteriorly)

Question 29

Occlusal aspect of mandibular 2nd premolar

Answer 29

3 cusp type appears more square lingual to buccal cusp ridges; with 2 cusp type appears round; buccal cusp is the largest followed by the ML , DL; triangular ridges converge in a central pit that is Y shaped (3 cusp type; most common) ; pit is located midway between the buccal cusp ridge and lingual margin off occlusal surface, slightly distal MD; mesial developmental groove goes MB and ends in M triangular fossa; D developmental groove goes DB and is shorter; ML cusp is wider MD than DL cusp so that the L developmental groove is D to center of crown; will see supplemental grooves radiating from developmental grooves; On occasion, a groove may cross over a marginal ridge; other variations seen; round or 2 cusp type (outline is round lingual to the buccal cusp ridge, may see more lingual convergence, ML and DL line angles are more rounded, have one well-developed L cusp opposite the B cusp; triangular ridges converge in a central pit that is H or U shaped ) central developmental groove, straight, crescent shaped; ends are M and D fossae, may have developmental pits in these terminations, may have a developmental depression crossing the DL cusp ridge

Question 30

Pulp chamber of the mandibular premolars

Answer 30

Pulp cavity of 1st premolar is similar to mandibular canine with usually one canal; 1st premolar may have prominent pulp horn on buccal; 1st premolar has large pulp chamber; 2nd premolar has larger pulp chamber than 1st premolar; 2nd premolar has more prominent pulp horns but M-D is similar to 1st