Lecture #9 MID PDF

 Abnormalities Of Teeth IV Environmental alterations of teeth Environmental effects on tooth structure development Post-developmental structure loss Environmental discolorations of teeth Localized disturbanc...

 Abnormalities Of Teeth IV Environmental alterations of teeth Environmental effects on tooth structure development Post-developmental structure loss Environmental discolorations of teeth Localized disturbances in eruption Developmental alterations of teeth  Developmental alterations in the number of teeth  Developmental alterations in the size of teeth  Developmental alterations in the shape of teeth  Developmental alterations in the structure of teeth 7. Developmental alterations in the shape of teeth, continued (1) Accessory Cusps  The cuspal morphology of teeth exhibits minor variations among different populations; of these, three distinctive patterns deserve further discussion: 1. Cusp of Carabelli. 2. Talon cusp. 3. Dens evaginatus.  When an accessory cusp is present, the other permanent teeth often exhibit a slightly increased tooth size. Accessory Cusps, Cusp of Carabelli: Clinical and Radiographic Features  Located on the palatal surface of the mesiolingual cusp of a maxillary molar.  May be seen in the permanent or deciduous dentitions and varies from a definite cusp to a small indented pit or fissure.  When present, the cusp is most pronounced on the first molar and is increasingly less obvious on the second and third molars.  Accessory Cusps, Talon Cusp: Clinical and Radiographic Features  A well-delineated additional cusp that is located on the surface of an anterior tooth and extends at least half the distance from the cementoenamel junction to the incisal edge.  Most occur in the permanent dentition, predominantly on permanent maxillary lateral or central incisors, and less frequently on mandibular incisors and maxillary canines.  Their occurrence in the deciduous dentition is very rare.  In almost all cases, the accessory cusp projects from the lingual surface of the affected tooth and forms a three-pronged pattern that resembles an eagle’s talon.  On rare occasions, the cusp may project from the facial surface or from both surfaces of a single tooth.  A deep developmental groove may be present where the cusp fuses with the underlying surface of the affected tooth.  Most, but not all, talon cusps contain a pulpal extension.  Radiographically, the cusp is seen overlying the central portion of the crown and includes enamel and dentin.  Only a few cases demonstrate visible pulpal extensions on dental radiographs.  Genetic influences: racial variation, occurrence in twins and several syndromes.  Both sexes may be affected, and the occurrence may be unilateral or bilateral. Accessory Cusps, Dens Evaginatus: Clinical and Radiographic Features  Dens evaginatus (Leong premolar) is a cusp-like elevation of enamel located in the central groove or lingual ridge of the buccal cusp of premolar teeth.  Although reported on molars, it typically occurs on premolar teeth.  Usually bilateral, with a marked mandibular predominance.  Deciduous molars are affected infrequently.  The accessory cusp normally consists of enamel and dentin, with pulp present in about half of the cases.  Encountered most frequently in Asians, Inuits, and Native Americans but is rare in whites.  Radiographically, the occlusal surface exhibits a tuberculated appearance, and often a pulpal extension is seen in the cusp.  The accessory cusp frequently creates occlusal interferences that are associated with significant clinical problems: o Pulpal necrosis is common and may occur through a direct exposure due to wear or fracture, or bacterial invasion of patent, immature dentinal tubules. o The accessory cusp also may result in dilaceration, displacement, tilting, or rotation of the tooth.  Frequently, dens evaginatus is seen in association with another variation of coronal anatomy in the same racial groups, shovel-shaped incisors, more prominently maxillary incisors. Accessory Cusps: Treatment and Prognosis  Patients with cusps of Carabelli require no therapy unless a deep groove is present between the accessory cusp and the tooth surface.  Deep grooves should be sealed to prevent carious involvement. Prominent cusp of Carabelli in primary maxillary second  Patients with talon cusps on mandibular teeth often require no therapy. molar teeth bilaterally.  Talon cusps on maxillary teeth frequently interfere with occlusion and should be removed.  Other complications include compromised aesthetics, displacement of teeth, caries, periodontal problems, and irritation of tongue or labial mucosa.  Because many of these cusps contain pulp, removal should be gradual with time allowed for tertiary dentin deposition, to avoid pulpal exposure.  Dens evaginatus typically results in occlusal problems and often leads to pulpal necrosis.  Removal of the cusp often is indicated but attempts to maintain vitality have met with only partial success. Clinical view showing the fractured tubercle of second premolar. Radiograph shows periapical lesions around the apices of second premolar and first molar. (2) Dens Invaginatus  A deep surface invagination of the crown or root that is lined by enamel.  Two forms, coronal and radicular, are recognized. Clinical and Radiographic Features  Coronal dens invaginatus is seen more frequently.  In descending order, the teeth affected most often include the permanent lateral incisors, central incisors, premolars, canines, and molars.  Involvement of deciduous teeth has been reported but is uncommon. bilateral maxillary dens invaginatus  A strong maxillary predominance is seen.  The depth of the invagination varies from a slight enlargement of the cingulum pit to a deep infolding that extends to the apex.  Before eruption, the lumen of the invagination is filled with soft tissue similar to the dental follicle.  On eruption, this soft tissue loses its vascular supply and becomes necrotic.  Large invaginations may become dilated and contain dystrophic enamel in the base of the dilatation.  In some cases, the enamel lining of the invagination is incomplete, and channels communicate between the invagination and the pulp.  These connections can result in pulpal necrosis long before the apex has closed.  Occasionally, the invagination may be rather large and resemble a tooth within a tooth; hence the term dens in dente.  In other cases, the invagination may be dilated and disturb the formation of the tooth, resulting in anomalous tooth development termed dilated odontoma.  Involvement may be singular, multiple, or bilateral. Dilated odontoma: Gross specimen cut into two halves in labiolingual direction shows core containing amorphous debris. Ground section shows a central dilated area with dentin surrounded by pulp space.  Radicular dens invaginatus is rare and thought to arise secondary to a proliferation of Hertwig root sheath, with the formation of a strip of enamel that extends along the surface of the root.  This pattern of enamel deposition is similar to that frequently seen in association with radicular enamel pearls (see Ectopic Enamel).  Rather than protrude from the surface (as seen in an enamel pearl), the altered enamel forms a surface invagination into the dental papilla.  Radiographically, the affected tooth demonstrates an enlargement of the root.  Close examination often reveals a dilated invagination lined by enamel, with the opening of the invagination situated along the lateral aspect of the root. Treatment and Prognosis  In small invaginations, the opening of the invagination should be restored after eruption in an attempt to prevent carious involvement and subsequent pulpal inflammation.  If the invagination is not detected quickly, then pulpal necrosis frequently results.  With larger invaginations, restoration or endodontic treatment may be needed.  Large and extremely dilated invaginations often have abnormal crowns and need to be extracted. (3) Ectopic Enamel  Refers to the presence of enamel in unusual locations, mainly the tooth root.  The most widely known are enamel pearls.  These are hemispheric structures that may consist entirely of enamel or contain underlying dentin and pulp tissue.  Most enamel pearls project from the surface of the root and are thought to arise from a localized bulging of the odontoblastic layer.  This bulge may provide prolonged contact between Hertwig root sheath and the developing dentin, triggering induction of enamel formation.  Similar internal projections of enamel into the underlying dentin rarely have been reported in the crowns of teeth.  In addition to enamel pearls, cervical enamel extensions or projections also occur along the surface of dental roots.  These extensions represent a dipping of the enamel from the cementoenamel junction toward the bifurcation of molar teeth.  This pattern of ectopic enamel forms a triangular extension of the coronal enamel that develops on the buccal surface of molar teeth directly overlying the bifurcation. Ectopic Enamel, Enamel Pearls: Clinical and Radiographic Features  Enamel pearls usually develop on the roots of the maxillary permanent molars followed in prevalence by the mandibular permanent molars.  Premolars and incisors are rarely affected.  Involvement of deciduous molars has been reported.  In most cases, one pearl is found.  The majority occur on the roots at the furcation area or near the cementoenamel junction.  Radiographically, pearls appear as well-defined, radiopaque nodules along the root surface.  Mature internal enamel pearls appear as well-defined circular areas of radiodensity, extending from the dentinoenamel junction (DEJ) into the underlying coronal dentin.  The enamel surface of pearls precludes normal periodontal attachment with connective tissue, and a hemidesmosomal junction probably exists.  This junction is less resistant to breakdown; once separation occurs, rapid loss of attachment is likely.  In addition, the exophytic nature of the pearl is conducive to plaque retention and inadequate cleansing. Enamel pearl associated with extensive bone loss and abscess formation  Ectopic Enamel, Cervical Enamel Extensions: Clinical and Radiographic Features  Located on the buccal surface of the root overlying the bifurcation.  Mandibular molars are affected slightly more frequently than maxillary molars.  In some studies on extracted teeth, the prevalence is surprisingly high, with approximately 20% to 50% of molars being affected.  Because connective tissue cannot attach to enamel, these extensions have been correlated positively with localized loss of periodontal attachment with furcation involvement.  The greater the degree of cervical extension, the higher the frequency of furcation involvement.  Cervical enamel extensions (in some cases) have been associated with the development of inflammatory cysts that are histopathologically identical to inflammatory periapical cysts.  The cysts develop along the buccal surface over the bifurcation and most appropriately are called buccal bifurcation cysts.  The association between cervical enamel extensions and this unique inflammatory cyst is, however, controversial. Bilateral mandibular buccal bifurcation cyst Ectopic Enamel: Treatment and Prognosis  When enamel pearls are detected radiographically, most are incidental findings that require no therapy.  Despite this, the area should be viewed as a weak point of periodontal attachment and meticulous oral hygiene should be maintained.  If an enamel pearl becomes exposed due to periodontal pocket formation and removal is contemplated, then the clinician must remember that lesion occasionally contains vital pulp tissue.  For teeth with cervical enamel extensions and associated periodontal furcation involvement, advanced periodontal surgical therapy is indicated. (4) Taurodontism  An enlargement of the body and pulp chamber of a multirooted tooth, with apical displacement of the pulpal floor and bifurcation of the roots.  The overall shape of the taurodont resembles that of the molar teeth of cud-chewing animals (tauro = bull; dont = tooth). Clinical and Radiographic Features  Affected teeth tend to be rectangular and exhibit pulp chambers with a dramatically increased apico- occlusal height and a bifurcation close to the apex.  Diagnosis is usually made subjectively from the radiographic appearance.  The degree of taurodontism has been classified into mild (hypotaurodontism), moderate (mesotaurodontism), and severe (hypertaurodontism), according to the degree of apical displacement of the pulpal floor.  Taurodontism may be unilateral or bilateral and affects permanent teeth more frequently than deciduous teeth.  There is no sex predilection.  The reported prevalence is highly variable (0.5% to 46%) and most likely is related to different diagnostic criteria and racial variations.  Some investigators believe the alteration is more of a variation of normal rather than a definitive pathologic anomaly.  The first molar is usually affected least with increasing severity noted in the second and third molars, respectively.  Taurodontism may occur as an isolated trait or as a component of various syndromes.  An increased frequency of taurodontism has been reported in patients with hypodontia, cleft lip, and cleft palate. Non syndromic familial bilateral decidious taurodontism  Investigations have shown that taurodontism may develop in the presence of any one of a large number of different genetic alterations.  These findings suggest that chromosomal abnormalities may disrupt the development of the tooth’s form and that taurodontism is not the result of a specific genetic abnormality Treatment and Prognosis  Patients with taurodontism require no specific therapy.  Coronal extension of the pulp is not seen; therefore, the process does not interfere with routine restorative procedures.  If endodontic therapy is required, then the shape of the pulp chamber frequently increases the difficulty of locating, instrumenting, and obturating the pulp canals. Endodontic treatment of a taurodontism tooth (5) Hypercementosis  Non-neoplastic deposition of excessive cementum that is continuous with the normal radicular cementum.  Systemic Factors  Local Factors o Acromegaly and pituitary o Abnormal occlusal trauma gigantism (hyperfunction) o Arthritis o Adjacent inflammation (e.g., pulpal, o Calcinosis periapical, periodontal) o Paget’s disease of bone o Unopposed teeth (lack of function), (e.g., o Rheumatic fever impacted, embedded, without antagonist) o Thyroid goiter o Repair of vital root fracture o Gardner syndrome o Vitamin A deficiency (possibly)  Clinical and Radiographic Features  Radiographically, affected teeth demonstrate a thickening or blunting of the root.  The enlarged root is surrounded by the radiolucent periodontal ligament space and adjacent intact lamina dura (in cases not associated with periapical inflammation).  May be isolated, involve multiple teeth, or generalized.  Mandibular molars are affected most frequently.  Occurs predominantly in adulthood, and frequency increases with age, most likely secondary to cumulative exposure to causative influences.  Occurrence reported in younger patients, in many cases demonstrating a familial clustering, suggesting hereditary influence.  All the listed systemic factors (slide 4) exhibit a weak association with hypercementosis except for Paget’s disease of bone.  Paget’s disease of bone should be considered whenever generalized hypercementosis is discovered in a patient of the appropriate age.  Despite the association with a number of disorders, most localized cases of hypercementosis are not related to any systemic disturbance. Histopathologic Features  The periphery of the root exhibits deposition of an excessive amount of cementum over the original layer of primary cementum.  The excessive cementum may be hypocellular or exhibit areas of cellular cementum that resemble bone (osteocementum).  Often the material is arranged in concentric layers and may be applied over the entire root or be limited to the apical portion.  On routine light microscopy, distinguishing between dentin and cementum may be difficult, but viewing the section with polarized light helps to discriminate between the two different layers.  Treatment and Prognosis  Patients with hypercementosis require no treatment.  Because of a thickened root, occasional problems have been reported during the extraction of an affected tooth, especially if hypercementosis is associated with ankylosis.  Sectioning of the tooth may be necessary in certain cases to aid in removal. (6) Dilaceration  An abnormal angulation or bend in the root or, less frequently, the crown of a tooth.  Although most examples are idiopathic, some teeth with dilaceration appear to arise after an injury that displaces the calcified portion of the tooth germ, and the remainder of the tooth is formed at an abnormal angle. Endodontic treatment of Dilacerated Crown of a Permanent mandibular molar with Mandibular Central Incisor. root dilaceration  The damage frequently follows avulsion or intrusion of the overlying primary predecessor occurring before 4 years of age.  Injury-related dilaceration more frequently affects the anterior dentition and often creates both a functional and a cosmetic dental problem.  Less frequently the bend develops secondary to the presence of an adjacent anatomic structure, cyst, tumor, or supernumerary tooth. Clinical and Radiographic Features  The bend may occur anywhere along the length of the crown or root.  Impaction of the affected tooth occurs in approximately 50% of these cases.  Dilaceration usually is radiographically obvious if the bend occurs in a mesial or distal direction.  Roots that bend facially or lingually may be more difficult to detect.  Treatment and Prognosis  Vary according to severity of deformity.  Deciduous teeth: inappropriate resorption resulting in delayed eruption of permanent teeth. o Extraction when necessary for normal eruption of succedaneous teeth.  Patients with minor dilaceration of permanent teeth frequently require no therapy.  Teeth that exhibit delayed or abnormal eruption may be exposed and orthodontically moved into position.  Difficulties in: 1. Extraction: may be difficult and result in root fracture. 2. Endodontic procedures: great care to avoid root perforation. 3. Prosthetic appliance: root dilaceration concentrates stress if affected tooth is used as an abutment, which may affect stability and longevity of abutment tooth.  Splinting of dilacerated tooth to an adjacent tooth overcomes the stress- related problems. (7) Supernumerary Roots  An increased number of roots on a tooth compared with that classically described in dental anatomy. Clinical and Radiographic Features  Any tooth may develop accessory roots in both deciduous and permanent dentitions.  Prevalence appears to vary significantly among different races.  Most frequently affects permanent molars (especially 3rd molars) from either arch and mandibular cuspids and premolars.  In some instances, the supernumerary root is divergent and seen easily on radiographs; in others, the additional root is small, superimposed over other roots, and difficult to ascertain. Three-rooted mandibular first molar Treatment and Prognosis  No treatment is required, but detection of accessory root is of critical importance when endodontic therapy or exodontia is undertaken.  Extracted teeth should be always examined closely to ensure that all roots have been removed successfully, because accessory roots may not be obvious on the presurgical radiographs. DONE WITH LOVE ❤️