Oral Anatomy and Physiology - Midterms PDF

**ORAL ANATOMY AND PHYSIOLOGY (MIDTERMS)** The Permanent Incisors - The first and second teeth from the midline which along with the canines, comprise the anterior teeth of each quadrant - The incisor closest to the midline is termed the Central Incisor , while the second tooth from t...

**ORAL ANATOMY AND PHYSIOLOGY (MIDTERMS)** The Permanent Incisors - The first and second teeth from the midline which along with the canines, comprise the anterior teeth of each quadrant - The incisor closest to the midline is termed the Central Incisor , while the second tooth from the midline is the Lateral Incisor. - CI & LI resemble each other although : - Maxillary CI crown is normally larger than the crown of the LI - mandibular LI crown and root are generally larger than those of the CI, although only very slightly PARTICIPATE IN ALL THREE OF THE MAJOR FUNCTIONS 1. MASTICATION - biting , incising and shearing (breaking the food particles into smaller pieces suitable for grinding. 2. ESTHETICS- not only do the size,shape,color,and manner of placement of incisors directly directly contribute to a person's appearance but they provide the support necessary for the normal profile of the lips and face. 3. PHONETICS- they are necessary for the execution of certain sounds. 4 FEATURES WHICH AID IN DIFFERENTIATING THE CROWN OF INCISORS FROM THE CROWNS OF OTER PERMANENT TEETH 1. INCISAL EDGE- this flattened edge,or surface, differs greatly from the singlecusp of canines, and the multi-cusped occlusal surfaces of posterior teeth 2. MAMELONS- rounded extesions of enamel on the incisal ridge of recently erupted incisors, most often are 3 in number - Irregular in number, shape and prominence - Wear away soon after incisors come into active occlusion but can occasionally be seen in adult. 3. POSITION AND ANGULATION OF MARGINAL RIDGES - The location & angulation of the marginal ridges of incisors (& canines) contrast MARKEDLY with the same features of the marginal ridges of posterior teeth - Incisors-marginal ridges are the mesial & distal terminations of the lingual surface and are more or - less parallel to the tooth's long axis - Posterior teeth-marginal ridges are found on occlusal surface, and roughly at right angles to the long axis of the tooth 4. LINGUAL FOSSA AND CINGULUM - Crowns of the incisors exhibit a concavity which covers roughly the incisal half of the lingual surface PERMANENT MAXILLARY CENTRAL INCISOR GENERAL CHARACTERISTICS ARCH POSITION -- the 2 teeth which are adjacent to the midline in the upper arch, sharing a mesial contact with each other & the distal in contact with the lateral incisors Viewed labially / lingually: crown is TRAPEZOIDAL in shape, WIDEST MESIODISTALLY Viewed proximally: TRIANGULAR in shape DEVELOPMENT Initiation of calcification: 3-4 mo Completion of enamel : 4-5 yrs Eruption -- 7-8 yrs Completion of root -- 10 yrs LABIAL ASPECT - Generally CONVEX in both mesiodistal & incisogingival - Convexity is GREATEST in the cervical 3^rd^ (normally) - Tends to approach FLATNESS toward the incisal 3^rd^ - MESIALLY -- Slightly convex but can be nearly straight - Crest of curvature at the contact area in the incisal 3rd near the mesio-incisal angle - Mesio-incisal angle -- SHARP - DISTALLY -- Convex outline, but more rounded disto-incisal angle - Crest of curvature is associated with the contact area which is located in the incisal 3rd VERY NEAR the junction of incisal middle 3rd - INCISALLY -- May exhibit MAMELONS - Generally straight outline Nearly perpendicular to the long axis of the tooth - CEJ curves evenly toward the root - CERVICALLY -- Crown is narrower mesiodistally at the cervical margin DEVELOPMENTAL - DEPRESSIONS-2 Straight, shallow depressions, which extend from the incisal edge toward the gingival, and fade out in the middle 3rd - MESIOLABIAL & DISTOLABIAL - They represent the division of the 3 labial lobes - IMBRICATION LINES -- faint, curved lines which roughly parallel the CEJ in the cervical 3rd of the surface - Not always present LINGUAL ASPECT - Generally the lingual surface is ROUGHLY TRAPEZOIDAL - Slightly narrower mesiodistally (mesial & distal surfaces CONVERGE slightly toward the lingual - Has both concavity & convexity - LINGUAL FOSSA-concavity from incisal half to two-thirds of the surface - CINGULUM-convex structure in the cervical portion - MESIAL & DISTAL OUTLINES- similar to their labial counterparts, except that they converge slightly more toward the gingival - INCISAL MARGIN-similar to labial aspect - CERVICAL MARGIN -- slightly greater depth of curvature apically than in labial; ASYMMETRICAL OTHER CONSIDERATIONS: 1. LINGUAL FOSSA - The shallow concavity found in the incisal half to 2/3 of the crown, which includes the largest area of the lingual surface - Bounded by 4 concavities: mesial & distal marginal ridges, incisal edge,cingulum - Often smooth, occasionally poorly defined forming a "W" shaped pattern 2. CINGULUM - the bulky convexity located in the cervical portion of the lingual surface - Generally smooth - Sometimes there is a LINGUOGINGIVAL GROOVE which separated the cingulum & fossa - LINGUAL PIT-between the cingulum & fossa, found near the center of the linguogingival groove if present \*more commonly found on a maxillary LI 3. MARGINAL RIDGES - Mark the mesial &distal borders of the lingual fossa, as well as the lingual surface - Linear & extend from their respective incisal angles to the cingulum - Named by locataion ( MESIAL & DISTAL MARGINAL RIDGES ) 4. HEIGHT OF CONTOUR- lingual crest of curvature is located in the cervical 3^rd^ , at the greatest convexity of the cingulum MESIAL ASPECT - **GENERAL CONSIDERATION:** - CI is roughly triangular in shape, and the incisal edge at the apex of the triangle, lies over the long axis of the tooth - Generally CONVEX in both dimensions, incisocervically & labiolingually **Mesial aspect -- labial outline** - Convex - Height of contour & greatest convexity located in the gingival third - Some may exhibit a flat outline incisal to the crest of curvature **Mesial aspect -- cervical margin** - CEJ curves evenly towards the incisal. - Exhibits the greatest depth of curvature of any tooth surface of the mouth **Mesial aspect -- incisal outline** - Usually pointed or slightly rounded, in newly erupted incisors (due to the convergence of the labial & lingual surface - With Incisal wear -- outline in straight but slopes from labial to lingual - "INCISAL RIDGE: projection of enamel on newly erupted teeth, which is the incisal termination of the tooth - Proximally-pointed, or slightly rounded - INCISAL EDGE: flattened area as the ridge is blunted due to occlusion - Proximally-sloping/ straight outline **Other considerations (MESIAL)** - Height of contour-located on the incisal 3rd of contact area - Contact area -located in the encisal 3rd, near the incisal margin & is centered labiolingually - Ovoid, long incisogingivally & narrow labiolingually - the only proximal area in the maxillary arch where the mesial surface contacts mesial surface **Distal aspect** - Resembles the mesial EXCEPT: - Distal surf. Is generally smaller than the mesial, because the incisocervical dimension is shorter - Distal surf. Is more convex incisogingivally - The cervical margin does not curve as far incisally - Distal contact area is smaller in size, located farther gingivally, very near the junction of the incisal & middle 3rds but still in the incisal 3rd **Incisal aspect** - Roughly triangular - Lingual surface is narrower mesiodistally than labial surface - Incisal edge is the widest mesiodistally os any permanent incisor - Labial & lingual outlines -- convex - Labial line angle is more distinct than lingual line angle - Portions of lingual fossa & cingulum are visible - Greatest contour of the cingulum is offset to the distal **ROOT** - Single, conical, relatively straight & tapes to a rounded apex - Horizontal x-section near cervical line -- shows a rounded triangular outline - Root is wider at the labial, which is the base of the triangle, & narrower at the lingual, which is the apex - Mid-root x-sec-ovoid outline, wider labiolingually than mesiodistally - Length-approximately 1% times crown length (10- 11mm) **Variation & anomalies** - Hutchinson's incisor - Talon cusp - Mesiodens - Dwarfed root - The second tooth from the median line in the maxillary arch - It resembles the central incisor but is smaller in all dimensions. - More prominent curvatures, concavities and convexities. **LABIAL ASPECT** - The labial surface is narrower and shorter than that of the central incisor - The distoincisal angle is more rounded than the mesioincisal angle - MOST ROUNDED distoincisal angle of any incisor in either arch - The labial surface is convex - Root curves distally **LINGUAL ASPECT** - Mesial and distal marginal ridges are pronounced, with a deeper lingual fossa - Linguogingival groove -- common - Lingual pit (near the center of the groove & is a potential for caries) - Linguogingival fissure -- a groove usually originating in the lingual pit & extends cervically & slightly distally onto the cingulum - Cingulum is usually prominent with the tendency toward deep developmental grooves within the lingual fossa where it joins the cingulum - Lingual fossa is more Concave and Circumscribed **MESIAL ASPECT** - The mesial surface, is like that of the central incisor, except that the root appears longer - With lessened dimensions - Contact area also similar in shape to the contact of Cl; found in incisal 3rd very near junction OF INCISAL & MIDDLE 3RD - Cervical line exhibits less depth of curvature than it does on the mesial of the CI - Wedge-shaped - The curvature of the cervical line is marked in the direction of the incisal ridge **DISTAL ASPECT** - The distal surface resembles the mesial surface - facial outline is more convex - Incisal portion of the lingual outline is more concave - The curvature of the cervical line is usually a mm. less than on the mesial - Distal CA: normally located at the junction of the incisal & middle 3rd **INCISAL ASPECT** - Sometimes resembles that of the central incisors or a small canine - The cingulum and the incisal ridge maybe large - The labiolingual dimension maybe greater than the usual in comparison with the mesiodistal dimension - Exhibit more convexity labially and lingually from the incisal aspect **ROOT** - Single, - Wider labiolingually than mesiodistally - Longer in relation to its crown; slightly shorter or equal that if the Cl - Apex -- sharper than Cl - Apical third most often toward the distal - Cervical & midroot x-sec = ovold, wider labiolingually than mesiodistally - Labial dimension is wider mesiodistallly **VARIATIONS & ANOMALIES** - Presence of a tubercle - Linguogingival fissure may extend all the way onto the root surface - Distorted crowns & unusual root curvatures - Peg lateral - Congenitally missing - Dens in dente - Simplest & least variable teeth in the mouth - Smallest permanent teeth - Central-slightly smaller than lateral - CI & LU resemble each other - Compared to maxillary incisors, the mandibular incisors have relatively longer crowns incisocervically & markedly narrower mesiodistally **General characteristic** - Arch position-adjacent to the midline in each mandibular quadrant - Share a mesial contact with each other, while the distal contact is with the permanent lateral incisor - Normally has the narrowest mesiodistal dimension & the smallest crown size of any permanent tooth - Symmetrical crown (mesial & distal nearly identical - Function biting, cutting, incising & shearing **Development table** **Labial aspect** - Mesial outline -- margin tapers evenly toward the gingiva in a nearly straight line - Mesio-incisal angle is quite sharp. - Height of contour is associated with the contact area in the incisal 3rd, very close to the incisal margin - Distal outline: outline is straight almost exactly like mesial - Height of contour is also in the incisal 3rd - Incisal outline-mamelons (when present) = 3 - After incisal wear outline is straight & at right angles to the long axis of the tooth - Cervical outline -- symmetrically curved toward the root **Other considerations : labial aspect** - Labial surface -- generally convex (greater convexity in the cervical 3rd) - Surface outline is roughly Trapezoidal - Some are rectangular - Developmental depression & imbricaton lines are NOT normally present - Occasionally very faint depressions occur near the incisal margin of the labial surface **Lingual aspect** - Mesial, distal & incisal outlines: closely resemble the labial - Cervical outline: the CEJ curves evenly toward the root, but is located farther from the incisal - Other considerations: lingual is relatively smooth, structures are generally less prominent than maxillary Cl - Presence of a slight concavity, or lingual fossa, bordered by indistinct marginal ridges on the mesial & distal - Normally no grooves, fissures or pits on the lingual surface - Cingulum is normally present(not as prominent as in max CIs - Height of contour is located on cervical 3rd of the surface (assoc. with the greatest convexity of the cingulum **Mesial aspect** - Labial outline: slopes in a straight to slightly convex line from the incisal ridge to the crest of curvature; then convex in the remainder of gingival 3rd - Lingual outline: concave in the incisal 2/3 & convex in the cingulum area - Incisal outline: edge is normally straight, but can be slightly rounded, located lingual to the center of the root - Incisal edge has an inclination toward the labial due to the wera pattern between upper & lower incisors - Cervical outline: marked, even curvature incisally on the cervical margin **Other considerations : mesial** - Mesial surface is roughly Triangular, or wedge -- shaped - Contact area is located about halfway from labial to lingual & is in the incisal 3rd, very close to the incisal edge - Has an ovoid shape-long incisogingivally & narrow labiolingually **Distal aspect** - Similar to mesial EXCEPT: cervical margin curves slightly LESS toward the incisal - Similar contact area location **Incisal aspect** - symmetry of proximals & straight incisal edge - Tooth is roughly 4-sided or Diamond-shaped - Normally wider labiolingually than mesiodistally - More labial surface is visible than lingual - Cingulum is VERY SLIGHLTY offset toward the distal (to distinguish left from right) **Root** - Normally single & straight - Generally symmetrical (labial & lingual aspect) & tapers gradually to a relativel shape Apex - Mesial & distal aspect: wider, slightly convex cervicoapically on both labial & lingual margins - Usually flat - Longitudinal groove :concave-shape on middle 3rd x-sec: roughly a triangle with rounded corners, slightly wider at the labial than at lingual - Mid root xsec: similar to cervical section only more ovoid **Variations & anomalies** - Great variability in the lingual inclination of the labial surface - Anomalies are rare - Bifurcated root **GENERAL CHARACTERISTIC** - Arch position: 2 tooth from the midline, sharing a mesial contact with the central incisor and distal contact with the canine - General form & function: slightly larger than mandibular Cl: complements the central in function **Development table:** - Initiation of calcification: 3-4 months - Completion of enamel: 4-5 yrs - Eruption: 7-8 yrs - Completion of root: 10 yrs **LABIAL ASPECT:** - Incisal margin may slope slightly gingivally toward the distal → rounded distoincial angle slightly shorter distal margin compared to the mesial - Contact area (distal) more cervically located than mesial cervically located height of contour on the distal outline creating a more - Mesial distal heights of contour are still in the incisal 3rd **LINGUAL ASPECT** - Cingulum is more offset to the distal curvature of the cervical line is also offset distally **MESIAL & DISTAL ASPECT** - LI distal surface is slightly shorter incisocervially than mesial - Mesial cervical line shows greater incisal curvature than distal - Distal contact area is more cervically located than on the mesial - Distal contact area is the most cervically located of any mandibular inciso contact **INCISAL ASPECT** - Incisal edge is not straight mesiodistally, as it is in the central; rather curves toward the lingual in its distal portion - Lingual contour/cingulum appears displaced toward the distal - Gives the crown the appearance of being twisted on its root **ROOT** - Normally a little greater than CI - Slighity thicker & wider - Concavities may be found mesially & distally (more on distal) **VARIATION & ANOMALIES** - Bifurcated root **GENERAL CHARACTERISTICS** - The \"single\" members of the dental arches - The most stable teeth in the dental arches - Their roots are the longest (16.2mm) - Well-anchored in the alveolar bone - Last teeth to be lost - 4 canines - The longest of the permanent teeth Called CORNERSTONES of the arches - AKA cuspids - Erupt into the mouth at 11-13 yrs of age - Frequently the last teeth be lost to dental disease **FUNCTION OF CANINE** - Support the lip & facial muscles - Cut, pierce or shear food morsels - Guide occlusion - Good anchors due to size & length of roots **CLASSIC CANINE TRAITS** - Long, thick roots that help anchor them in the alveolar process - The incisal ridge is divided into 2 inclines or slopes - The mesial cusp ridge is shorter than the distal - The labial surface is prominently CONVEX with a vertical labial ridge - they are the only teeth with a labial ridge - Greater labiolingually than mesiodistally - Root is oblong faciolingually in cross section - Canines are wedge- shaped proximally - Lingual height of contour is in the cervical 3rd - Remaining outline is convex on the lingual in the incisal 3rd - Maxillary canine cusp tip is labial to the long axis of the root - Mandibular canines cusp tip is lingual to the long axis of the root **DIMENSIONS:** - Tooth length: 27.0mm - Crown height: 10.0mm - M-D width-7.5mm - L-Lwidth-8.0mm **LABIAL ASPECT:** - Facial is made of 3 lobes - Cingulum is the fourth **LABIAL** - Mesial outline is broadly convex in the middle Ird & flat in the cervical 3rd - Distal cusp ridge is usually longer than the mesial - Mesial contact is at the junction of the incisal & middle 3rds **LABIAL** - Distal aspect makes a shallow \"S\" & convex in the middle 3rd Slightly concave in the cervical 3rd - Distal contact is in the middle 3rd **LINGUAL ASPECT** - Crown & root, narrower lingually than labially - Lingual ridge from incisal to cingulum present - Has 2 shallow fossae on either side - the root bends distally in the apical 3rd - Cingulum & tip of the cusp are usually centered mesiodistally - Lingual ridge more prominent than the mesial & distal marginal ridges - Distal marginal ridge more prominent (or elevated) than the mesial - Mesial margin longer than the distal - The root is narrower on the lingual than facial **PROXIMAL VIEW** - Labial surface is more convex than incisors - Labial height of contour is in the cervical 3^rd^ - Cervical line dips incisally 2.0mm at the mesial - Facial & lingual outline of the root is convex - Quite broad faciolingually **DISTAL ASPЕСТ** - Same as mesial except the following: - Less curvature of CEJ (approx. 1 mm) - Contact area is broader - Distal marginal ridge is heavier - More irregular in outline - More concave surface - More pronounced root developmental depression **INCISAL VIEW** - STRIKING FEATURE: - ASYMMETRY OF CROWN - Line drawn from cusp tip through cingulum will yield a greater distal half - Notice the marked concavity labially - Facial aspect quite convex - Mesial half rounded - Distal half flat or Concave - 3 distinct lobes - Middle lobe is the most prominent - Third tooth from the midline in each lower quadrant - The replacement of the deciduous mandibular canine **TO COMPARE WITH MAX CANINE:** 1. crown is long/longer INCISOCERVICALLY than max CI 2. MD & Labio-lingual dimensions of both crown & root are normally less in the mand. Canine 3. root is shorter than the max canine or may be as long 4. the lingual surface & its structures are less well developed than the max canine 5. The cusp of the mand canine is not so well developed, nor its tip normally as sharp mesiodistally as in the maxillary canine 6. The labial surface is generally not so convex as in the max canine **DEVELOPMENTAL TABLE (MANDIBULAR CANINE)** - Initiation of calcification: 4 to 5 months - Completion of enamel: 6 to 7 years - Eruption: 9 to 10 years - Completion of root: 12 to 14 years **LABIAL ASPECT** - Smooth & convex with labial ridge - Labial ridge not as pronounced as maxillary canine - General outline is PENTAGONAL - Labial surface is not so convex as maxillary canine - Mesial outline of crown is slightly convex to flat - Disal outline is slightly concave in the cervical third - Mesial slope of cusp is shorter than the distal - Mesial contact is well within the incisal third - Distal contact is at the junction of the incisal & middle 3rd s - Tapers to a blunt apex - Root is convex on the facial surface - Pits & grooves rarely ever present - Marginal ridges not prominent - surface appears smooth Distal marginal ridge more prominent than lingual & mesial ridges - Facial outline of root is visible from the lingual **PROXIMAL ASPECT** - The crown is wedge-shaped but thinner in the incisal aspect than the maxillary - Incisal ridge is lingual or on the long axis of the root **INCISAL VIEW** - Labially, the mesiolabial outline is more convex - while the distolabial outline is flat or concave - The distal cusp slope is directed slightly lingually from the cusp tip, which places the distoincisal angle in a lingual position to the cusp tip. - Outline is more symmetrical than maxillary canine - LABIOLINGUAL MEASUREMENT IS GREATER THEN THE MESIODISTAL