Q. 2. Describe in detail developmental anomalies of shape of teeth.
Developmental disturbances affecting shape of teeth
i. Gemination, fusion and concrescence
ii. Accessory cusps
• Cusp of Carabelli
• Talon cusp
• Dens invaginatous
• Dens evaginatous
iii. Ectopic enamel
• Enamel pearls
• Cervical enamel extensions
vi. Supernumerary roots.
• Gemination is a developmental anomaly that refers to division of single tooth germ into incomplete or complete formation of two teeth.
• Crowns may be partially or totally separated from each other.
• Roots are fused and single root canal is present within the root.
• The structure is usually one with two completely or incompletely separated crowns that have a single root and a root canal.
• The condition is seen in both deciduous and permanent dentition,with a higher frequency in the anterior and maxillary region.
• Fusion is defined as single enlarged tooth or joined tooth in which the tooth count reveals a missing tooth when the anomalous tooth is counted as one.
• One of the most important criteria for fusion is the fused tooth must exhibit confluent dentine.
• Both permanent and deciduous dentition are affected in case of fusion, although it is more common in deciduous teeth.
• Fusion can be complete or incomplete and its extent will depend on stage of odontogenesis at which fusion takes place.
• The incisor teeth are more frequently affected in both the dentitions.
• Concrescence is defined as union of two adjacent teeth by cementum only without confluence of the underlying dentine.
• It is the type of fusion, which is limited only to the roots of teeth and it occurs after the root formation of involved teeth is completed.
• Aetiology: Concrescence may be developmental or postinflammatory or due to traumatic injury.
• Common between maxillary second molar and unerupted third molar.
II. Accessory cusps
a. Cusp of Carabelli
b. Talon cusp
c. Dens invaginatous (dens in dente)
d. Dens evaginatous
Cusp of carabelli
• Present on mesiopalatal cusp of maxillary first molars.
• An analogous accessory cusp is seen occasionally on the mesiobuccal cusp of a mandibular permanent or deciduous molar known as protostylid.
• Talon cusp is an anomalous projection resembling eagle’s talon projects lingually from cingulum area of permanent incisors.
• A developmental groove is present at the site, where this projection meets with the lingual surface of tooth.
• This groove is prone to caries, so it should be removed. If pulp exposure is present then endodontic therapy is done.
• Found in association with ‘Rubinstein–Taybi syndrome’.
Dens in dente or dens invaginatous
• Dens in dente is a developmental variation, which arises as a result of enamel epithelial invagination of the crown surface before calcification.
• Several causes of this condition are: it is because of focal growth proliferation and focal growth retardation that takes place in certain areas of tooth bud, increased localized external pressure.
• After calcification it appears as accentuation of lingual pit.
• Teeth most frequently involved are maxillary lateral and maxillary central incisors.
• Radiographic features
Appearance of tooth within tooth due to deep pear-shaped invagination from lingual pits, approximating to pulp.
This anomaly makes teeth prone to caries so endodontic therapy should be done. Restoratory procedures are unsuccessful because of this deep invagination, which generally approximates pulp.
Dens evaginatous (Occlusal tuberculated premolar, Leong’s premolar, Evaginated odontome)
• Dens evaginatus is a developmental condition appears as an accessory cusp or globule of enamel on occlusal surface between buccal and lingual cusps of premolars unilaterally or bilaterally.
• This is opposite of invagination. That means, there occurs extrusion of the dental papilla outwards into the enamel organ.
• Clinical findings:
• This condition is more common in people of Chinese race.
• More common in maxillary first premolars but also occurs rarely on molars, cuspids and incisors.
• Presents a tubercle of enamel with a core of dentine with a narrow pulp chamber.
• When the tooth erupts, this bit of enamel is higher than the cusps, and covers the underlying mass of dentine.
• If present in deciduous teeth, it causes difficulty in feeding.
• When the thin surface enamel of the tubercle breaks down, infection of the tooth takes place resulting in death of the pulp and abscess formation.
• Treatment consists of extraction of the tooth.
III. Ectopic enamel
• Enamel pearls
• Cervical enamel extensions
• Ectopic enamel or enamel pearls or enameloma or enamel drop usually occur in furcation area below the crest of gingiva.
• Cervical enamel extension, also occurs along the surface of dental roots.
• Maxillary and mandibular molars are most commonly affected.
• Predisposes to development of buccal bifurcation cysts.
IV. Taurodontism (Bull-like teeth)
• Taurodontism is a dental anomaly in which the body of the tooth is enlarged at the expense of roots.
• A specialized or retrograde character
• A primitive pattern
• An atavistic feature
• Mendelian recessive trait
• A mutation
• Associated with Klinefelter syndrome
• It is due to failure of Hertwig epithelial root sheath to invaginate at proper horizontal level.
• It may affect both deciduous and permanent dentition, but more common in permanent dentition.
• Molars are commonly affected.
• Tooth morphology is normal.
• Enlarged and rectangular pulp chamber is present.
• No constriction of pulp at cervical area.
• Roots are very short.
• Furcation is present just above root apex.
• No treatment is required.
• Dilaceration refers to angulation or curve in root or crown of tooth.
• Angulation is caused due to trauma to the tooth during formative stage of tooth.
• Curve is present at apical, middle or at cervical portion depending on the portion which is forming at the time of trauma.
• Occlusal trauma in deciduous tooth may also cause dilaceration of permanent tooth.
• More common in the maxillary anterior region.
• Significance: Tooth with bent root is difficult to extract.
VI. Supernumerary roots
• One or more extra roots may be present in tooth.
• Usually single rooted teeth such as mandibular cuspids and bicuspids are involved.
• Third molars of both jaws also present one or more extra roots.
Q. 1. Internal resorption.
• Internal resorption is also known as chronic perforating hyperplasia of pulp, odontoclastoma or pink tooth of mummery.
• It is an unusual form of resorption that begins centrally within the pulp, apparently initiated by a peculiar inflammatory hyperplasia of the pulp.
• No early clinical signs and symptoms.
• Tooth may show pink spot (pink tooth) when more of dentine is resorbed from one area of the crown, leaving a covering of translucent enamel.
• It appears as a pink area due to vascular pulp visible through the translucent enamel.
• Pink spot appears as round or ovoid area of radiolucency in the central portion of the tooth.
• If condition is discovered before perforation of crown, root canal therapy may be carried out.
• Once perforation has occurred, extraction of tooth is the treatment.
Q. 2. Dens invaginatus.
• Dens invaginatus is otherwise known as dens in dente or gestant odontoma.
• It is a developmental variation that arises as a result of enamel epithelial invagination of the crown surface before calcification.
• It is an enamel lined surface invagination of crown or root.
• It is because of focal growth proliferation and focal growth retardation that takes place in certain areas of tooth bud due to increased localized external pressure.
• Coronal form is formed by the infolding of enamel organ in to dental papilla, while radicular form is produced due to invagination of Hertwig root sheath.
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