CD+Midterm+Exam+Review+ENK+DMA-part-3.pdf

COLLEGE OF DENTAL MEDICINE Why do you need to know? • • • • Determine Dental age Identify abnormalities in development Identify when disturbances in formation occurred Anomalies occur most commonly in 3rd molars (wisdom teeth), maxillary lateral incisors, and mandibular second premolars. • Restor...

COLLEGE OF DENTAL MEDICINE Why do you need to know? • • • • Determine Dental age Identify abnormalities in development Identify when disturbances in formation occurred Anomalies occur most commonly in 3rd molars (wisdom teeth), maxillary lateral incisors, and mandibular second premolars. • Restorative concerns and challenges • Extraction concerns COLLEGE OF DENTAL MEDICINE Tissuesof the tooth • Dental pulp- connective tissue organ. Contains artery, veins, lymphatic tissue, nerves • Primary function is to form dentin • Apical Foramen-opening at apex where nerve and blood supply pass • Cementoenamel junction- may occur in different configurations • Enamel overlaps cementum • End-to-end approximation • Absence of connection enamel and cementum so that dentin is exposed • CEJ is landmark for periodontal probing • Estimate the timing of enamel hypoplasia by measuring from CEJ to mid-point of defect. • ADF=ACF ( years of formation/crown height x distance of defect from CEJ) ADF- age at which hypoplasia occurred. ACF- age at which crown was completed COLLEGEOFDENTALMEDICINE COLLEGE OF DENTAL MEDICINE Developmental Anomalies • In the absence of permanent tooth, primary root may not fully resorb or resorb at all • When root resorption does not follow normal pattern and permanent tooth is present, it may be blocked out of arch • Retention of primary tooth can occur with altered resorption Clincal pearl: knowing your eruption and exfoliation sequence can help you spot potential issues early! COLLEGE OF DENTAL MEDICINE Dental Anatomy Session 3: The Primary Dentition COLLEGEOFDENTALMEDICINE COLLEGE OF DENTAL MEDICINE New Terms COLLEGE OF DENTAL MEDICINE Contrasts Between Primary and Permanent Teeth • Roots of primary molars are longer, more slender, and flare beyond outline of crowns to allow for developing permanent tooth. • Cervical ridges are very distinct and offer restorative challenges. • Slender cervical third in the mesiodistal dimension. • The buccal and lingual surfaces above the cervical ridge are flatter than in permanent teeth leading to a narrow occlusal surface, comparatively. • Primary teeth are whiter. COLLEGE OF DENTAL MEDICINE Function of Primary Teeth • Functions in chewing, speaking, swallowing. • Maintains space for permanent dentition. • Development of occlusion in the permanent dentition. COLLEGE OF DENTAL MEDICINE Pulp Chambers and Pulp Canals of Primary Teeth A. Enamel cap of primary molars is thinner with more uniform depth. B. Comparatively greater thickness of dentin over the pulpal wall at the occlusal fossa of primary molars. C. Pulp horns are high and dentinal thickness is limited especially in mandibular 2nd molars. D. Cervical ridges are distinct and more pronounced in primary teeth especially on buccal. E. Enamel rods at the cervix slope occlusally instead of gingivally. F. Primary molars have narrow neck. G. The roots of the primary teeth are longer and narrower in comparison with crown size. H. The roots of the primary molars flare out nearer the cervix. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary Central Incisor Labial: M-D diameter of crown is greater than its Cervicoincisal length. (wider than it is tall) Lingual: well developed marginal ridges and cingulum. 10mm 16mm Pulp Canal Mesial/Distal: curvature of CEJless distinct than in perm. Incisal: straight. Looking down, labial surface is much broader and smoother. Primary teeth lack mammelons and have a very straight incisal edge. Pulp Horn 6mm COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary Lateral Incisor 5.6mm 15.8 mm Labial: distoincisal point angle of the crown are more rounded than central. 11.4 mm Mesial/ Distal: Larger curvature of CEJ mesially than distally, but less so than permanent. Labial Lingual Similar in all ways to central. Root is longer in proportion as compared to central. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary Canine Labial: crown is more constricted and cervical and mesial and distal surfaces more convex. Long triangular shaped cusp. Root is long, slender and more than twice the crown length. Compared to permanent, cusp is longer and sharper. Lingual: merging enamel ridges: cingulum and M and D marginal ridges and incisal cups ridges. Tubercle at cusp tip. Shallow ML and DL fossae. Tooth tapers lingually and usually distally inclined above middle 1/3. 6.5mm 19 mm M Mesial/Distal: similar to incisors, but wider at cervical 1/3 of mesial evidencing function. Incisal: diamond shaped. Cusp tip is distal to the center of the crown and mesial cusp slope is longer than distal which intercuspates with the longer distal slope of the mandibular canine. 13.5 ML,DLFossae Labial Lingual COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular Central Incisor Labial: crown has flat face without developmental grooves. Mesial and distal sides of the crown are evenly tapered from the contact areas with narrowing at the cervix. Crown is wide in proportion to length compared to permanent. Heavy trunk resembles the permanent max lateral incisor. Root is long and tapered. Root is almost twice the crown length. Lingual: May have slight concavity called lingual fossa. Easily seen ridges and cingulum. Lingual narrower than facial. 5 mm 14mm 9 mm Mesial: Incisal ridge centered over center of the root and between the crest of curvature of the crown labially and lingually. Significant cervical bulges typical of primary incisors. Labiolingual measurement is only 1mm less than primary max central evidencing heavy function. Distal: Reverse of mesial. Curvature of DEJless pronounced. Often has a developmental depression. Incisal: Incisal ridge is straight and bisects the crown labiolingually. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular Lateral Incisor 5 mm The primary mandibular lateral is similar, but larger, in all dimensions to the central except labiolingually, where the two are the same. The lingual surface may be more concave and there is tendency for incisal edge to slope toward distal. 15 mm 10 mm COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular Canine 6 mm Very similar to maxillary canine except in dimension. The crown is approximately 0,5mm shorter and the root at least 2mm shorter. The M-D measurement at the root trunk is greater. The most obvious differentiating trait is that the distal ridge slope is longer than the mesial slope where the opposite is true of the primary maxillary canine. 17.5 mm 11.5 mm COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary First Molar Buccal- M and D contact areas are widest, converging sharply to the cervix, which is 2mm less in width. It has a narrower appearance at the neck than its permanent counterpart. It is much smaller than the primary second molar. It is shaped like a premolar. Roots - Slender and long and widely spread. D root is much shorter than M. Bifurcation begins almost at the site of the CEJ.Characteristic of all primary molars. Very small root trunk compared to permanent teeth. Lingual – Similar to buccal. ML cusp is most prominent cusp. It is longest and sharpest. DLcusp is poorly defined, small, and rounded, if it exists. May have only one lingual cusp. 5.0 mm 15.2 mm 10 mm Mesial – Wider at cervical than occlusal. ML cups is longer and sharper than MB cusp. Pronounced convexity is evident on the buccal outline of the cervical third. Distal – Crown is narrower distally than mesially. Tapers markedly toward the distal. DBcuspislongandsharpandtheDLcuspispoorlydeveloped.Prominentbulge atcervicalthird. *What guesses can you make about the function of the larger sharper cusps? What is the relationship between cusp function and root size? COLLEGEOFDENTALMEDICINE COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary First Molar Occlusal - Crown outline converges lingually and also distally, but occlusal surface is almost a rectangle. Awell-defined buccal developmental groove divides (BDG) divides the MB and DB cusps. Supplemental grooves radiate from the pit in the Mesial Triangular Fossa (MTF), one to the buccal, one to the lingual and one toward the marginal ridge. Sometimes an oblique ridge is present. There is always a distal developmental groove (DDG). This tooth does not resemble its counterpart in the permanent dentition, but does resemble a premolar, even though the primary dentition does not have them. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary Second Molar Buccal – Resembles first permanent maxillary molar but is smaller. Two welldefined buccal cusps with a buccal developmental groove between them. The crown is narrow a the cervix in comparison with its MD measurement. Much larger than that of the first primary molar with much longer and heavier roots. Cusps are of nearly equal size. Lingual - Three cusps: Mesiolingual cusp, the largest and most well developed, Distolingual cusp, and a third supplemental cusp which is apical to the ML cusp and is often called the cusp or tubercle of Carabelli. Mesial – Resembles permanent molars. ML cusp appears large. MV cusp is relatively short from this angle. CEJ nearly straight. MB root extends lingually far out beyond the crown outline. 11.7 mm 17.5 mm 5.7 mm COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Maxillary Second Molar Distal – Smaller than Mesial. CEJis mostly straight. All roots can be seen from this aspect. DB root is shorter and narrower than the other from this view. This surface shows the most centered bifurcation between these roots. Occlusal - Resembles permanent first maxillary molar. Somewhat rhomboidal with four well-developed cusps and a cusp of Carabelli. There is a central fossa containing the Central Pit (CP), a Mesial Triangular Fossa (MTF) just distal to the Mesial Marginal Ridge (MMR) with its Mesial Pit (MP),A well defined Central Groove (CG) connects the MTF with the CF.The Buccal Developmental Groove extends buccally from the central pit separating the triangular ridges. There is a prominent Oblique Ridge (OR) just mesial to the Distal Fossa (DF). The DFcontains the Distal Developmental Groove (DDG). COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular First Molar Occlusal– Rhomboidal.MB prominence visible. ML cusp may be seen as the largest and best developed of all the cuspsand has a broad flatsurfacelingually. The MB cusp has a well-defined triangular ridge on the occlusal which terminates in the center of the occlusal surface buccolingually at the Central Developmental Groove (CDG).TheLingual Developmental Groove (LDG)extends towardlingualfromthe CDGseparatingtheMLandDLcusps.UsuallytheLDGextends just to the junction of the lingual cusp ridges without crossing over to the lingual surface. Themandibular primary firstmolarisunique.It doesnotresembleanyoftheotherteethin either dentition. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular First Molar Buccal – The mesial outline of the crown at the contact is nearly straight, dropping down from the marginal ridge to the cervix. The distal makes up for it and converges dramatically toward the cervix. The distal portion of the crowns is shorter than the mesial portion with the CEJdipping apically where it joins the M root. Two distinct buccal cusps with the being larger. The roots are long and slender and spread at apical ½. If the crown were to be bisected through the furcation, the tooth would be evenly divided, but the mesial portion would be almost twice as tall as the distal half with a root that is a third longer than the distal. Lingual - The crown and root converge to the lingual markedly on the mesial surface. Distally, the opposite is true. The DLcusp is rounded with a hint of developmental groove between this cusp and the ML cusp. The ML cusp is a distinguishing feature. It is almost centered lingually but also in line with the mesial root. The mesial marginal ridge is very well developed almost resembling a small cusp. Mesial – The most noticeable detail is the extreme curvature toward the buccal at the cervical third. 6 mm 9.8 mm 15.8 mm Which side is the mesial? COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular First Molar Mesial – The most noticeable detail is the extreme curvature toward the buccal at the cervical third. In this view, it otherwise resembles the mesial of the primary second mandibular molar and the mesial of the mandibular permanent molars. Cusps are over the root base and the lingual outline extends beyond the root base. The CEJslants upward buccollingually due to the larger MB cusp. Note the flattened buccal surface from the crest of curvature on the buccal surface at the cervical third to the tip of the MB cusp.All primary molars have flattened buccal surfaces in this segment. Distal – Differs from mesial surface. The CEJdoes not drop buccally. The length of the crown bucaly and lingually is more uniform and the CEJis nearly straight. The DB cusp and DLcusp are not as long or sharp as the mesial cusps. The distal marginal ridge is smaller and the distal root is rounder and shorter. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular Second Molar B Buccal – From the buccal, the primary mandibular second molar is narrow at the cervical portion of the crown compared to its width at the level of the contact. The tooth is divided into three similarly sized cuspal portions by developmental grooves, which results in a straight buccal surface with a Mesiobuccal, a buccal, and a distobuccal cusp. The roots are slender and long and flare widely. The roots of this tooth may be twice as long as the crown. Lingual– Two lingual cusps of nearly equal size separated by short lingual groove. The cuspsare not as wide as the threebuccalcuspsso the lingual is narrowerthanthe buccal. Relatively straight CEJ. Crown extends over root more at distal. L The primary mandibular second molar resembles the permanent mandibular first molar. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular Second Molar Mesial – Resembles the permanent first molar. Crest of contour on buccal is more prominent on the primary molar which constricts toward the occlusal as it flattens above the cervical ridge. The buccal cusp is over the root and the lingual is extended beyond it. The lingual cusp is higher than the buccal cusp. The CEJis regular but slightly upward slanted from buccal to lingual to compensate for larger buccal cusp. The mesial root is broad and flat with a blunt apex. M Distal – Differs from Mesial. CEJdoes not drop to buccal. Length of crown is more uniform buccally and lingually. The CEJis almost straight across. The DB cusp and the DLcusp are not as long or as sharp as the mesial cusps. The distal marginal ridge is not as straight or well defined as on the mesial. The distal root is rounder, shorter, and more tapered. COLLEGE OF DENTAL MEDICINE Tooth by Tooth Description Primary Mandibular Second Molar Occlusal-Fairly rectangular. Three similarly sized buccal cusps and two lingual. The tooth is slightly wider at the buccal. Welldefined triangular ridges extending from each cusp tip to the central groove. Compared to the permanent mandibular first molar, the MB, DB, and DB are almost equal in size and development. The D cusp of the permanent molar is smaller than the other two. Because of the small buccal cusps, the primary tooth crown is narrower buccolingually compared to its mesiodistal measurement, than it is in the permanent tooth. COLLEGE OF DENTAL MEDICINE