DEFINITIONS A trait is distinguishing characteristic, quality, peculiarity or attribute. Set Traits Arch Traits Class Traits Type Traits
SET TRAITS (Dentition traits) Distinguish teeth in the primary (deciduous) from secondary (permanent) dentition. ARCH TRAITS Distinguish maxillary from mandibular teeth.
CLASS TRAITS Distinguish the four categories (or classes) of teeth: namely incisors, canines, premolars and molars. Example: incisors have crowns compressed labiolingually for efficient cutting; canines have single pointed cusps for piercing food; premolars have two or three cusps for shearing and grinding; molars have 3-5 somewhat flattened cusps for grinding.
TYPE TRAITS Differentiate teeth within one class (such as differences between central and lateral incisors, or between 1st and 2nd premolar or between 1st, 2nd, and 3rd molars).
DIFFERENCES BETWEEN MAXILLARY AND MANDIBULAR INCISORS LABIAL VIEWWider, less symmetrical points. Long, narrow, symmetrical crown.Mesial contacts are more incisally Mesial and distal contacts are atlocated than distal contacts. about the same level. Mesial and distal incisal angles areMore rounded distoincisal angles. sharp.Common labial depressions. Less frequent labial depressions.More cervically located contacts. Contacts very near incisal edgeLevel of mesial and distal contact (both medial and distal).vary.
LINGUAL VIEW Lingual smooth, almost noPronounced marginal ridges. marginal ridges.Deeper lingual fossa. Shallow lingual fossa.Sometimes lingual pits. No pits.Larger cingulum. Smaller cingulum. Central almost perfectlyCentral Incisor has cingulum to symmetrical (Lateral hasdistal. cingulum to distal).
PROXIMAL VIEWIncisal edge labial to root Incisal edge on or lingual toaccess. root axis lines.Elevated cingulum. Small cingulum. Roots noticeably widerRoots narrower, specially in facio-lingually (withapical third. depressions on both sides of roots).
INCISAL VIEW Crowns wider facio-Crowns wider mesio- lingually than mesio-distally than facio-lingually. distally.Incisal edge labial to mid- Incisal edge is lingual to orroot axis. centered on mid-root axis.Central cingulum is to Central cingulum isdistal. centered.Lateral cingulum is Lateral cingulum is tocentered. distal.
INCISAL VIEW (cont.)Lateral has almost round Lateral crown is oblongcrown outline. facio-lingually.Central has more triangular Central crown is oblongcrown outline. facio-lingually. Lateral and central areLateral is convex labially nearly flat labially nearnear incisors. incisal.
DIFFERENCES BETWEEN MAXILLARY CENTRAL AND LATERAL INCISORS LABIAL VIEW Smaller crown tip distally atLarger crown, wider cervically. cervix.More symmetrical. Less symmetrical.Mesial Incisal angle is 90 Rounded and acute angle.degrees.Mesial contact near incisal Distal contact near middle third.Root is wide cervically, tapering Longer and narrower root.to blunt apex.Less root apex bend to distal. Root tip often bend to distal.
LINGUAL VIEWLarge shallow lingual fossa. Deep but small fossa.Cingulum distally positioned. Cingulum is centered.Incisal edge outline curves less Rounded incisal edge slopes upmesio-distally (is flatter) distally.Shorter distance than mesio- Mesio-lingual ridge is straightlingual marginal ridge. with distal curve.Less frequent lingual pits. Common lingual pits.
PROXIMAL VIEW Slightly less cervical lineGreater cervical line curve. curve.Evenly tapered root with Root outlines more convex.mesial side. Slightly shallower lingualDeeper lingual fossa outline. fossa.
INCISAL VIEWCrown noticeably wider mesio- Crown size mesio-distally anddistally. facio-lingually almost the same.Crown outline roughly triangular. Crown outline round or oval.Incisal ridge curves mesio- Shorter incisal ridge is straighterdistally. mesio-distally.Cingulum is off centered to Cingulum is centered.distal.Labial developmental Sometimes labial depressions.depressions.
DIFFERENCES BETWEEN RIGHT & LEFT MAXILLARY INCISORS LABIAL VIEWFlat mesial but rounded distal Asymmetrical crown outline,crown outline. shorter on distal.Mesio-incisal angle is 90 Acute mesio-incisal angle.degrees.Slightly rounded disto-incisal More rounded disto-incisalangle. angle. Distal contact is much moreDistal contact more cervical. cervical.
LINGUAL VIEWSame as labial. Same as labial. Long and straight mesio-Cingulum towards distal. lingual ridge.Longer mesio-lingual Short and curved disto-marginal ridge. lingual ridge.
PROXIMAL VIEWLarger cervical line curve on Larger cervical line curve onmesial than distal. mesial than distal.Flat mesial side of root withdepression. INCISAL VIEW Shorter curved disto-lingualCingulum towards distal. marginal ridge.Longer mesio-lingual marginal Mesial crown outline flatterridge. than distal on lingual taper.