S. R. Prabhu - Handbook of Oral Pathology and Oral Medicine

Oculodentodigital dysplasia

Segmental odontomaxillary dysplasia

Odonto‐onychodermal dysplasia

Odontochondrodysplasia

History

Clinical examination

Radiography

Unerupted teeth to remain without any interference

Erupted teeth: steel crowns

Non‐salvageable teeth to be extracted

Delayed tooth eruption is the emergence of a tooth into the oral cavity at a time that deviates significantly from norms established for different races, ethnic groups and sexes

Delayed eruption is relatively common; racial and gender variations exist

Failure of eruption is less common

Agenesis of teeth cause failure of eruption

Local causes associated with delayed tooth eruption:Supernumerary teethMucosal barrier scar tissue due to trauma/surgery/gingival hyperplasiaTumours: odontogenic or non‐odontogenic tumoursAnkylosis of deciduous teethEnamel pearlsInjuries to primary teethRegional odontodysplasiaEctopic eruptionImpacted permanent teethEmbedded primary teethOral cleftsRadiation damage

Systemic causes associated with delayed tooth eruption:Nutritional deficienciesVitamin D‐resistant ricketsHypoparathyroidismHypopituitarismLong‐term chemotherapyCerebral palsyPrematurity or low birth weightPhenytoin useGenetic disorders

Local factors causing delayed tooth eruption are frequently detected by radiography

Systemic factors causing delayed tooth eruption are detected by systemic clinical features and laboratory findings

Failure of tooth eruption: congenital absence of teeth (third molars, mandibular second premolars and maxillary lateral incisors) results in failure of tooth eruption

Radiographical evidence of absence of teeth is diagnostic

History

Clinical examination

Radiography (panoramic view is ideal)

Laboratory tests if systemic factors are suspected

Patient with eruption delay of more than 12 months (delayed eruption) of the normal age range should be referred to a paediatric dentist for further evaluation

Identification of the causes and their elimination is important

Surgical exposure followed by orthodontic treatment may be required for some patients with delayed eruption

Teeth that are completely or partially retained in the jaws beyond their normal date of eruption

Common; variations in incidence and prevalence exist

The mandibular third molars are the most common impacted teeth, with their prevalence ranging from 27% to 68.8% in various parts of the world

The reported prevalence of impacted teeth of canines and second premolars ranges from 2.9% to 13.7%

Lack of space for tooth eruption due to inadequate arch length

Crowding of teeth

Dense overlying bone

Excessive soft tissue in the path of eruption

Genetic abnormalities

Long tortuous path of eruption (for canines)

Frequently impacted teeth: mandibular third molars followed by the maxillary third molars, maxillary canines and mandibular premolars

Young adults are commonly affected; often detected on routine radiography

Impacted deciduous teeth are extremely rare

Impacted permanent first and second molars are rare

Often supernumerary teeth are impacted (detected on radiography)

Impacted teeth may or may not be symptomatic

With no history of extraction, clinically the number of teeth present in the dentition is less than normal

Impaction can be full or partial

Symptomatic patients with lower third molar may complain of earache or paraesthesia of the lip

Pericoronitis may occur (pain, inability to open the mouth, swelling of the pericoronal soft tissue)

Often, all four third molars may be impacted

Occasionally impactions are associated with syndromes or odontogenic cysts and tumours

Types of impaction: mesioangular, distoangular, vertical or horizontal impaction for third molars ( Figure 1.9a‐d). Canine impaction may be bilateral ( Figure 9 e) or inverted

Proximity of the impacted tooth to the inferior dental nerve for lower third molar impactions may cause paraesthesia

Impacted teeth may be associated with cysts or odontogenic tumours

History

Clinical examination

Radiography (panoramic view)

No treatment is required for asymptomatic impactions

Surgical removal for symptomatic impacted teeth

Surgery for impacted teeth associated with cysts or tumours Figure 1.9(a) Mesioangular impaction of the mandibular third molar. (b) Distoangular impaction of the mandibular third molar (c) Vertical impaction of the mandibular third molar. (d) Horizontal impaction of the mandibular third molar. (e) Bilateral impaction of maxillary canines.

Dens invaginatus refers to an exaggeration of the process of formation of lingual pit causing invagination (also called dens in dente or dilated odontome)

Dens evaginatus refers to an enamel and dentin covered spur extending outward from the occlusal surfaces of molars or premolars and rarely lingual surfaces of lower anterior teeth. This is the opposite of dens evaginatus (also called evaginated odontome)

Dens invaginatus: prevalence: 0.3–10%, affecting more males than females

Dens evaginatus: more common in people of Asian descent; prevalence: 0.06–7.7%; 15% in Inuit and Native American populations

Dens invaginatus:Deepening or invagination of the enamel organ into the dental papilla prior to calcification of the dental tissuesGenetics may play a role

Dens evaginatus:A result of an unusual growth and folding of the inner enamel epithelium and ectomesenchymal cells of dental papilla into the stellate reticulum of the enamel organ

Dens invaginatus:The permanent maxillary lateral incisors appear to be the most frequently affected tooth (90% of all cases)Maxillary posterior teeth: 6.5% of all casesMandibular teeth are very rarely affected

May be associated with taurodontism, microdontia, gemination, supernumerary tooth and dentinogenesis imperfecta Figure 1.10(a) Dens invaginatus; radiograph showing dens invaginatus in a peg lateral incisor(source: by kind permission of Professor Charles Dunlap, Kansas City, Kansas, USA).(b) Dens evaginatus; radiograph showing dens evaginatus. Note a tubercle extending outward from the occlusal surface of the premolar.

Causes food debris deposits and renders tooth vulnerable to caries

Dens evaginatus:More common in mandibular premolar teethMay be bilateral and symmetrical tubercles on the occlusal surfaces of posterior teeth or on lingual surfaces of lower anteriorSlight female sex predilectionCan cause malocclusion with opposing teethAbnormal wear and fracture of the tubercle may occur