Dental Anatomy -8!28!09

I.

Anatomic and Physiologic Consideratin of Form and Function (Dr. Dosch) a. Function of the Human teeth i. The 3 major functions of the human teeth are: 1. MASTICATION: chewing 2. ESTHETICS: appearance 3. PHONETICS: speech ii. Teeth displa y certain forms with align and stabilize the entire dentition, and protect the teeth and their associated structure from potenetial breakdown b. Periodontium: the supporting tissues, bodth hard and soft of a tooth i. May suffer the consequences of anomalous…..ETC c. Comparative Vertabrate Anatomy i. Most common primitive tooth type is conical in shap; compose of a single cone or lobe ii. The conical type of tooth was common in primitive vertebrates and today is exhibited by many of the lower vertebrates, including reptiles. iii. Lower vertebrates are called homodonts: they have similarly shaped teeth which differ only in size iv. These animals possess only up and down ( hinge action) jaw movements becase the cingle conical cusps lock together on closure, ETC v. Basic purpose of conical teeth of these animals is for grasping vi. ETC vii. ETC viii. From tritubercular tooth, mammals have evolved additional… ix. ETC x. ETC xi. ETC

xii. A mammal which is fully heterodont, but still lacks lateral jaw movmetns, due to (interlocking cusps) is the dog xiii. Type of hing movement is common to most other carnivores xiv. The bear has a dentition suited to its….ETC xv. Most highly developed and complex teeth belong to those animals which are members of the order of mammals xvi. ETC xvii. ETC xviii. Most primates excluding man exist in a tropical climate w/ basically herbivorous diet of fruits xix. Anthropoid apes have dental formulae…. Etc xx. MAN has evolved the most complex dental mechanism of all animals xxi. Man is omnivorous and has developed teeth to function in the mastication of boeth meath and plant foods xxii. In man the elongated and interlocking canines have been reduced ETC xxiii. Individual teeth of man differ both in size and development] xxiv. All teeth in human are composed of:::: II.

Lobes- into a. Animal teeth development b. S c. S d. The theory of separate calcification centers for each lobe has fallen into disfavor in recent years e. Therefore, lobes will be considered only as anatomical divisions of a tooth f.

ETC

g. Anterior teeth

i. Composed of 4 lobes. The three labial lobes are named the mesiolabila, middle labial, etc ii. ETC iii. Evidence for presence of 3 labial lobes is sometimes found on the incisal edge of newly erupted incisors in the form of mamelons(slightly rounded …..ETC)k iv. Then the incisora are in functional occusion, the mamelons are abraded away soon after eruption v. Further evidence of separation of labial lobes of all anterior teeth is found in the form of 2 shallow depressions found in the incisal portion of the labial surface vi. Thes linear, vertical depressions are named mesiolabial, distolabial developmental grooves h. Lobes- premolars i. ETC ii. The exception is a mandibular…. iii. Maxillary molars normally have 4 lobes, named besiolingual, buccal iv. ETC v. Mandibular first molar has 5 lobes; names like the lobes of maxillary molars. The lob vi. Most other mandibular molars exchibit four i.

General Occlusal Curvatures and Axial Position i. The general arrangement ii. ETC iii. ETC iv. Curve of spee: this atheroposterio curvature begins at the canins and follow the buccal cusp o fthe tips of the premolar and molars v. The curve o fspee…..

vi. Based on the curve of spee, the crowns of molars tilt towards the mesial and the root toward the distal vii. NOTE; the premolars are the most upright vertical teeth in the dental arches viii. Purpose of curvature; anterior, posterior movement ix. The Curve of Wilson is the medio-lateral curvature of the ocllusal plane x. The curve of t j.

Curve of Wilson i. For the occlusal surface ii. This curve is deeper posteriorly and the molars inclinations iii. Because of the curve of wilson and its associated tooth inclination, the buccal sucps of mandibular molars and the lingual cusps of maxillary molar appear to be longer

k. Compensating Occusal Curvature i. Compensating occlusal curvature ii. This curvature is l.

Axial position: the inclination foa l tooth form a vertical axis

m. Axial position is normally described in terms of the roots n. These inclinations are necessary for the proper occlusal and incisal function of teeth o. Etc. p. Maxillary anterior teeth i. The faciolingual dimension: 1. The maxiallary anterior teeth exhibit great inclination of the root toward the lingual ii. The mesiodistal direction: iii. Maxillary premolars: maxillary

iv. Maxillary molars: the roots of maxillary molars display great lingual inclination and moderate distal inclination v. Mandibular anterior teeth: the mandibular incisors and canines vi. Mesiodistally, the incisorsa are nearly straight or diplay on y minor mesial root inclination, while the canines have slight distal root inclination vii. Mandibular premolars: mesiodistally, these teeth show some distal root inclination. In viii. Mandibular molars: the mandibular molars exhibit moderat to great buccal and distal root angulations III.

Crown surface form: introduction a. The geometric configuration of all the crown surfaces: trapezoidal, rhomboidal b. Facial and lingual surfaces i. From the facial and lingual aspects, the crowns ii. The incisal or inclusal iii. Arrangmeent of these iv. ETC c. Mesial Distal surfaces i. IN a proximal view, the crowns of the permanent ii. The shape fits… iii. Crowns of the maxillary preci iv. ETC v. ETC vi. From the proximal aspect, the crowns fo the mandibular posterior teeth are roughly rhomboidal in shape vii. The crowns incline towars the lingual viii. This form is

IV.

Contact areas

a. The places where teeth touch b. Each tooth normally contacts 2 adjacent teeth. The most posterior tooth in each quantrant only has a tooth on the mesial contact c. Central incisors contact each other at the midline d. Contact areas normally increase in size w/ age e. The initial f.

The broadening of contact is due to the abrasions

g. Asa aresult of this abrasive action, the mesiodistal length of the dental arches is slowly becoming shorter. The teeth become narrower mesiodistally and move mesially or closer to the midline (mesial drift) h. Proper location of contact areas aid in stabilizind the dental arches i.

Proper contact areas also prevent

j.

ETC

k. The replacement of proper contact in dental restorations is of extreme importance l.

The contact area must be TIGHT to prevent food packing

m. Its proper lodcation, both in an inciso ETC n. GENERAL RULES OF CONTADCT AREAS i. Contact areas become more cervicallly located ii. The distal contact area of a tooth normally has a move iii. The Relative size of the contact areas increases from the anterior to posterior in each quadrant iv. Anterior teth have a contact areas which are normally centerin v. Posterior teeth have a acontact areas which are normally located to the buccal V.

Interproximal Space a. The triangular shaped area between adjacent teeth that is cervical to the contact area b. The interproximal space isuaually filled with interdental papilla

c. The Triangle is forme by: alvoel d. ETC e. Embrasure: the open space beween the proximal surface of adjacent teeth, there they diverge facially, lingually, incisally (occlusally) or cervically f.

When veiwd the teeth from….

g. The Cervical (ginvgival) embrasure ccorrespons to the interproximal space oand is normally larger in area than the incisal (occlusal) embrasure h. When viewing the teeth from the icisal or occlusal surface…ETD i.

If an imaginary line is drawn to bisect any emprasure space, the 2 protions

j.

Asymmetrical embrasure may

k. Proper embrasure form hs 2 main phy. Purpose: i. Spillway for food material ii. Serve as integral part of self celasning iii. ETC iv. GENERAL RULES 1. From the facial or lingual aspect, incisal occlusal embrasure increase in relative size from the anterior teeth towrd 2. From the facil or lingual 3. From the incisal aspect, the labial and lingual embrasures 4. From the occlusal aspect, the lingual is normally larger than the bucfcal embrasure in 5. When the one side of an embrasure (tooth outline) has a certain contour, the other side has…. ETC v. Contact areads & Embrasure vi. The contact areas vii. ETC

viii. ETC l.

Facial line angles i. The 2 facial line angles of the anterior teeth and premolar ii. Their outline is best seen from the incisal iii. These prominent line angles are actually the faical iv. For any specifica facial embrasure, the line angles are located irectlyy adjacent to each other v. This placement is consistent with the concept of syhmmetry vi. The height of contour or crest of contour is the greatest area of contour inciso(occluso) – cervically on vii. Mesial and distal surfaces also have heights of contour and they are normally located at the contact areas

m. Heights of countour i. As with embrasure form, these contours aid ii. If the contour is excessive iii. When insufficient contour does not provide adequate protection, iv. Thus, it is very important for the dentist to restore correcgt facial and lingual heights of contour v. The facial height of contour of all teeth is located in the cervical 1/3 vi. The lingual height of contour of all anterior thierd vii. The lingual height of contour of tall posterior teeth is located in the middle or occlusals n. Cervical Line Curvatures i. The cervical linde or cement-enamel junction is defined as the observable liena around the tooth where ii. The cervical line is a stable entity, in contrast to the gingival line which may be ever chaning iii. On any individual tooth, the amount (depth)……. Seems to be related to (1) length 2

1. Cervical line is normally curved convex toward the apical on the facial and lingual surfaces of teeth 2. The cervical line is normally curved (convesx) toward the incidsal….. 3. The amount (depth) of curvature on any tooth is normally greater on the mesial surfacethan on the distal 4. Cervical lines on adjacent proximal surfaces of adjacent teeth have approximately the same depth of curvature 5. The depth of the curvature on all surfaces is greatest on the central incisor and decreases posteriorly. o. Gingival line i. The gingival line is the imaginary line which marks the level of termination of the soft tissue surrounding the tooth. It is also call…. ii. The level of the gingival line is variable….ETC iii. As the individual ages, the gingival line often recedes to a lower level. iv. The gingival line separates the clinical crown and the root v. The cervical line sepearates the anatomical crown and root vi. EPITHELIAL ATTACHMENT 1. Is the attachment of the gigiva to the tooth 2. The epithelial attachment can be sistinguished 3. The epithelial attachmen serves as the connection for the soft 4. The periodontal ligament provides the attachment of the hard tissue (bone) and is much more 5. Since there is usually a sulcus between he gibinval margina dn the epithelial attachment 6. Like the gingival,,, ETDC 7. Apical migratin of the periiodonalt ligament 8. ETC

p. Continuety of marginal ridges i. Are the mesial and distal termination of the occusal surfaces of posterior teeth and the lingual surfaces of anterior teeth ii. Marginal ridges are normally bulkier on the posterior teeth iii. The height of marginal ridges of adjacent teeth in the same arch should be that th sem hight iv. Adjacent marginal ridges are norally shaped so that they creat a small occusal embrasure on posterior teeth v. The highes and shpas of the vi. Marginal ridges on adjacent teeth q. Continuity of Cdentral Grooves i. Central grooves of posterior teth are normally alighted into one, more or less contuous valley ii. This allows for r.

Faciolingaul taper i. Faciolinguual taper – a tapering reuctino in the mesiodistal wideth of the teeth, which starts at the center of the ii. Mandibular second

s. Occlusal Anatomy i. Another feature of posterior teeth is the groove and ridge pattern on the masticating surface ii. ETC t. Root shape & # of branches i. The shape , length and number of roots branches are also intimately ii. The canine by virtue of its location in the arch and its evolutionary function as the fang of carnivores, has the longest and strongest root in both arches. iii. Molars are multirooted to comlelment the increased size of the occlusal table

iv. Root form is directly related to crown form, placemtn of tooch in arch, function v. RULES 1. Normally widest towards the cervical 2. Anterior teeth and premolars…. 3. Maxiallary molars normally possess 3 4. ETC VI.

Conclusions a. Tooth forma nd function are directly related b. The potential for the breakdown of the periodotium is directly related to form and function c. The dentist is under an obligation to understand and apply the principles of