PERMANENT CENTRAL INCISORS Dr MAJI JOSE https www

PERMANENT CENTRAL INCISORS Dr MAJI JOSE

https: //www. youtube. com/watch? v=r 07 pq. EEUs. Y 8 � Eruption sequence of Max permanent teeth �

PERMANENT INCISORS � Eight in number- four maxilla & four in mandible two central incisors and two lateral incisors � Central incisors are located on either side of the midline with their mesial surfaces in contact. � Lateral incisors are situated distal to the central incisors on each side of the arch.

FUNCTIONS �incising or cutting food. �articulation of speech �aesthetics �guide the jaw during closure.

PERMANENT MAXILLARY CENTRAL INCISORS

INTRODUCTION � either side of the midline. � most prominent teeth � a great aesthetic value � larger in all dimensions than the lateral incisors. Chronology • First evidence of calcification - 3– 4 months • Enamel completed - 4 to 5 years • Eruption - 7 to 8 years • Root completed - 10 years

LABIAL ASPECT � the surface of the tooth facing the lip. � Crown & root � Crown Shape from labial aspect : �Squarish or rectangular with a slight cervical convergence (narrower at the cervical region than incisal). �Cervico-incisal length is 2 mm more than the mesio-distal width.

SHAPE OF LABIAL ASPECT Root cervix Crown

OUT LINES AND CONTACT POINTS Distal contact area Cervical outline Distal outline Mesial outline Incisal outline * # Mesial contact area

OUTLINES FROM THE LABIAL ASPECT Mesial outline - slightly convex with contact area (crest of curvature) at the incisal third close to the mesio-incisal angle. � Distal outline - more convex than mesial outline and contact area is located at the junction between middle and incisal third. � Cervical outline - semicircular with curvature towards the root. � Incisal outline - represented by incisal edge which is straight and regular with sharp mesioincisal angle and slightly rounded disto-incisal angle. �

CERVICAL & INCISAL OUTLINES Semicircular cervical outline curved towards the root Curved/rounded disto-incisal angle Sharp mesioincisal angle Straight incisal edge

LABIAL SURFACE � smooth with convexity at the cervical third. � Surface becomes relatively flat towards the incisal edge � Two shallow vertical depressions may be appreciated dividing the labial surface into three portions, each representing parts developed from three different lobes � Newly erupted teeth may have three mamelons Labial surface

Shallow depressions on labial surface

ROOT FROM LABIAL ASPECT � Root is conical in shape, �broader at cervical 1/3 rd, �narrows through middle part �to end in a relatively blunt apex. �The apex may show a distal tilt.

PALATAL/LINGUAL ASPECT � surface of the tooth facing the palate/tongue. Crown from lingual aspect � The lingual outline is reverse of the labial outline. � The crown & root converge towards the lingual side � the mesial and the distal surfaces visible � the lingual surface shows concavities and convexities.

COMPARISON OF LABIAL & PALATAL ASPECT Mesial surface Distal aspect Smooth surface Mesial outline Distal surface Surface with convexity & concavity Distal aspect

LINGUAL SURFACE Cingulum Mesial marginal ridge Lingual fossa Distal marginal ridge Linguo-incisal ridge

CONVEXITIES � Cingulum- located at the cervical third which is placed slightly distal in a mesio-distal direction. � Either side is bordered marginal ridges. �mesial marginal ridge (slightly longer ) �distal marginal ridge. � Linguo-incisal ridge, at the incisal boundary of the lingual surface.

CONCAVITY lingual fossa � M-shaped � boundaries �superiorly by the cingulum, �inferiorly by the linguo-incisal ridge �on either side by the mesial and distal marginal ridges. �A deep developmental groove may be present extending onto the cingulum. � Cervical outline is semi-circular with curvature towards the root.

ROOT FROM LINGUAL ASPECT � lingually converged � conical in shape with blunt and rounded apex. � Cross section of the root is triangular in shape with rounded angles.

MESIAL ASPECT � is one of the proximal aspects that is closer to the midline of the face. � Crown Shape: triangular or wedge shaped �base at the cervix � apex at the incisal edge

OUTLINES OF MESIAL ASPECT Cervical outline Labial outline Lingual outline Incisal edge

OUTLINES OF MESIAL ASPECT � Labial outline: convex and the maximum convexity (crest of curvature) at the cervical third. �becomes relatively straight from the crest of curvature to the incisal edge. � Lingual outline: shows convexities and concavities: �Cervical third is convex at cingulum �concavity at lingual fossa �Convex at incisal ridge. � Crest of convexity at cervical third, on cingulum.

OUTLINES OF MESIAL ASPECT Crest of convexity Labial outline Crest of convexity * * Cingulum Lingual fossa Linguo-incisal ridge

Bisecting line passing through root tip & incisal edge Extent of cervical curvature-3. 5 mm Contact point at middle of middle 1/3 rd *

� Cervical outline: �curved with curvature towards the crown. �extent of curvature is more on mesial side. � The incisal edge: �incisal edge and the root tip lies in the midline which bisects the tooth. � Mesial surface: Mesial surface of central incisor is smooth and convex. �Contact point at middle of middle 1/3 rd in labiolingual direction

ROOT FROM MESIAL ASPECT � is cone shaped and tapered with a rounded apex. � The root surface on the mesial aspect is relatively flat � may show longitudinal developmental depression.

COMPARISON OF MESIAL & DISTAL ASPECT

DISTAL ASPECT OF MAX CI � is the proximal aspect that is away from the midline of the face. � Distal aspect is similar to that of mesial aspect with slight differences. � The crown appears to be broader from this aspect than the mesial aspect. � Extent of curvature of cervical line is less on the distal aspect � The root is tapered towards the rounded apex.

INCISAL ASPECT OF MAX CI � is the cutting/biting surface of the tooth. � root will be visible from this aspect as it superimposed over the crown. � shape is triangular with the base on the labial surface and the apex towards the cingulum. � The mesio-distal dimension is greater than the labio-lingual dimension. � As the incisal edge is located at the center, equal extent of the labial and lingual halves can be seen.

INCISAL ASPECT – TRIANGULAR SHAPE WITH BASE ON LABIAL ASPECT AND APEX AT CINGULUM Labial aspect Distal aspect Mesial aspect Lingual aspect

GREATER M-D DIMENSION THAN B-L Labial aspect Distal aspect Mesial aspect Lingual aspect

INCISAL EDGE AT CENTER IN LA-LI DIRECTION Labial aspect Distal aspect Mesial aspect Lingual aspect

� The labial aspect shows a semi- circular arch � lingual aspect is tapered and more convex at the cingulum. � Slight disto-lingual twist of the incisal edge may be appreciated from this aspect because of lingual positioning of the disto-incisal angle compared to that of mesio-lingual angle.

OUTLINES Labial aspect Distal aspect Semicircular labial outline Mesial aspect Lingual outline Lingual aspect

LABIAL SURFACE � Smooth � Convexity at cervical 1/3 rd � Flat at middle and incisal 1/3 rds Convexity at cervical 1/3 rd Flat incisal & middle 1/3 rd

DISTO-LINGUAL TWIST OF THE INCISAL EDGE Labial aspect Distal aspect Mesial aspect Lingual aspect

LINGUAL SURFACE- FROM INCISAL ASPECT Labial aspect Mesial aspect Distal aspect Mesial marginal ridge (longer) Distal marginal ridge(smaller) Cingulum ( off to distal) Lingual aspect Lingual fossa

LINGUAL SURFACE FROM INCISAL ASPECT � The lingual fossa, marginal ridges and distally placed cingulum can be appreciated on the lingual aspect.

FEATURES TO BE CONSIDERED TO DIFFERENTIATE SIDE � Labial Aspect �Straight incisal edge with sharp mesio incisal angle and rounded disto-incisal angle. � Relatively straight mesial outline and slightly curved distal outline. �Mesial contact area is more incisally placed (incisal 1/3 rd, closer to mesio-incisal angle) than distal (at junction of incisal and middle 1/3 rd). � Distal tilt of root.

� Lingual Aspect �Distal placement of cingulum. �Longer mesial marginal ridge than distal marginal ridge. � Proximal �Cervical Aspect line more curved on mesial aspect than distal. � Incisal Aspect �Disto-lingual twist of incisal edge

DEVELOPMENTAL VARIATIONS AND CLINICAL CONSIDERATIONS 1. ‘Shovel shaped’ central incisors: � incisor that has prominent mesial and distal marginal ridges and deep lingual fossa.

2. DEEP LINGUAL PIT: � may show a deep lingual pit at the incisal border of cingulum. � Such teeth may be prone to develop dental caries. lingual pit

3. ACCESSORY LINGUAL RIDGE: � Rarely maxillary central incisors may show vertical ridges extending from cingulum to incisal edge.

4. TALON CUSP: � the cingulum may become very prominent to such an extent, it resembles eagle’s talon, which is referred to as talon cusp. � Higher chances of dental caries � may interfere with occlusion � may cause trauma to tongue Talon cusp

5. SCREW DRIVER SHAPED CENTRAL INCISOR � Seen in patients affected by congenital syphilis - a bacterial infection � due to the absence of middle lobe, mesial and distal outlines of central incisors converge incisally making incisal 1/3 rd narrower than cervical 1/3 rd. � In addition incisal edge will be showing notching.

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