Lec.10 Radiology Dr.Sura

Lec.10 Radiology Dr.Sura Radiographic appearance of dental variations Radiographic appearance of dental Common diseases of teeth &supporting structures: Dental caries: Dental caries is a destructive process which affects the enamel and dentine of erupted teeth. The initial lesion is caused by Gram-negative bacilli which form acid below a dental plaque. The earliest radiological change is a small defect in the enamel surface due to decalcification. This defect is difficult to demonstrate at first, but when the carious process has penetrated the enamel and reached the dentine, the defect is usually obvious. The destruction of dentine progresses much more rapidly than the destruction of enamel, and is soon apparent as a radiolucent area within the crown. If unchecked, the process continues until the crown of the tooth is completely destroyed. bacterial invasion of the pulp (pulpitis) and periapical infection are inevitable sequelae of advanced caries. Radiation caries: is the term given to the high incidence of dental caries which often follows therapeutic radiation to the maxillofacial region in adults. It is almost certainly due to a reduction in salivary flow, and not to any alteration in the structure of the teeth which are fully formed in early adult life. Interpretation of incipient occlusal lesions Radiographs are usually not effective for detection of an occlusal carious lesion until it reaches the dentin Interpretation of moderate occlusal lesions The moderate occlusal lesion is usually the first to induce specific radiographic changes, prompting a definitive decision regarding the presence of caries. The classic radiographic change is broad based, thin radiolucent zone in the dentin with little or no changes apparent in the enamel.

Interpretation of severe occlusal lesions Sever occlusal lesions are readily observed both clinically and radiographically. They appear as large holes, or cavities, in the crowns of teeth. Pulp exposures cannot be determined by radiographs, however; only clinical evidence can substantiate the radiographic impression.

Interproximal caries: detected by bitewing radiographs or periapical taken with parallel technique.it start as small notch on the enamel surface below the interproximal contact point. The shape of this caries as a triangle with the base towards the outer surface of the tooth & apex towards the dentino-enamel junction (DEJ). when caries reaches the DEJ, another triangle extended towards the pulp. when the undermined unsupported enamel fractured, the entire carious lesion radiographically appears as a kind of V-shape.

Lec.10 Radiology Dr.Sura

Buccal & lingual margin. It appears round, or oval or semilunar, while the gingival caries firstly appears as oval and then semilunar. Depth of the caries cannot be determined because of superimposition of the caries lesion on the remaining dentin &pulp. Its difficult to differentiate between buccal and lingual caries on a radiograph.

Root surface caries Also called cemental caries involves both cementum and dentin. Its prevalence is approximately 40% to 70% in aged population. The tooth surfaces most frequently affected are, in order, buccal, lingual, and proximal.

Lec.10 Radiology Dr.Sura

Recurrent caries Recurrent caries is that occur immediately next to the restoration, it may result from poor adaptation of a restoration, which allows for marginal leakage, or from inadequate extension of a restoration. approximately 16% of restored tooth surface have recurrent caries. The radiographic appearance depends on the amount of decalcification present and whether a restoration is obscuring the lesion

Lec.10 Radiology Dr.Sura Apical lesions: Common Periapical radiolucencies: 1. Abscess. 2. Granuloma 3. Cyst . Less-common pathological conditions: 1. First stage cementoblastoma. 2. Superimposition on mental or incisive foramina, maxillary sinus or inferior dental canal…also superimposition on pathological cavities separated from tooth apex, may simulate apical pathology.

Root-end changes: 1. Hypercementosis: clubbing of root-end .radiopaque mass associated to apex of apex of vital tooth is seen radiographically (thickening of cementum).

2. Root resorption: • Smooth resorption: roots appear blunted& shortened, surrounded by periodontal space &lamina dura,teeth are vital with partially or totally- obliterated pulp canal. • Rough resorption: Roughened surface of root associated with infection .periodental space is widened ,absent lamina dura &its either within the canal or on the external surface of the root.

Lec.10 Radiology Dr.Sura Bone changes associated with apical alteration: 1. condensing osteitis: radiographically ,the bone appear with increased bony density & reduction of the intertrabecular spaces.

2. Ankylosis: bone & tooth roots become fused ,so its impossible to observe the separation between tooth & bone radiographically(no P.D.space &no laminal dura).

Periodontal disease 1. Incipient periodontal disease: Radiographic evidence takes the form of three signs: 1. Triangulation; widening of the periodontal space at the crest of interproximal bone. The sides of the triangle are formed by lamina dura &root surface & the base towards the crown of the tooth. 2. Crestal irregularities: The normal smooth crest that is running between the cemento-enamel junction of two adjacent teeth become irregular &destructed with periodontal disease. 3. Alveolar bone changes: Sclerosis of the bone between the lamina dura of two adjacent teeth(more radiopacity with reduction of the inter-trabecular spaces).. 2. Advanced periodontal disease: It includes the above stages with periodontal pocket formation because of bone loss

Lec.10 Radiology Dr.Sura Location of bone loss: either generalized or localized to one or few areas. Amount of bone loss: normally alveolar bone level is (1-1.5 mm)from the CEJ(cemento enamel junction)to the crest of the alveolar bone, if more than 1.5 mm, it indicates the presence of bone loss &its amount is measured. Direction of bone loss: Intercrestal bone should be parallel with a line drawn from the CEJ of one tooth to the adjacent tooth..bone loss can occur on a plane that is when horizontal bone loss…parallel to the imaginary drawn line called there is greater bone loss on the proximal surface of one tooth than the other,so the bone level will not be parallel to the imaginary line..called ….vertical bone loss Other common diseases of the teeth &supporting structures: I-Tooth resorption: either smooth or rough. If it occurs on the pulpal surface called internal tooth resorption, or external surface and called external tooth resorption. Types of tooth resorption: 1-Physiological. normal following the exfoliation of the deciduous teeth 2-Idiopathic. 3-Pathologic: caused by pressure, infection, trauma &neoplasm. alter the shape of the tooth like single pit 2.hypoplastic defects: - defect or series of pits which may coalesce to form a groove or band covering appreciable part of tooth. 3.crown-pulpal calcification: A. pulp stones (oval or round radiopacity within the pulp) B. secondary dentin: reduction in pulp chamber, either partial or complete. C. dental bridge: found after successful use of calcium hydroxide. D. Pulpal obliteration: associated with ageing, appear as very small or completely-obliterated pulp chamber 4.Tooth fracture radiolucent fracture line and discontinuity of the tooth outline. If superimposition of fracture segments occurs, the fracture will be hidden so multiple views of the area resolve such difficulties.

Lec.10 Radiology Dr.Sura 5.Erosion, abrasion and attrition: Loss of tooth structure that can be seen radiologically

6.Pericoronitis: primary acute pericoronitis infection do not demonstrate radiographic changes. Chronic pericoronitis demonstrate the enlargement of the space of enamel follicle. Bone loss amount depend on duration and severity of infection.

7.Dry socket & pulpitis: do not demonstrate significant radiographic changes Radiographic Appearance of Dental Anomalies There are many developmental anomalies that can affect the teeth and facial skeleton. The diagnosis of these variations based on both the clinical and radiographic findings. Classification of developmental anomalies Developmental anomalies of the maxillofacial region are usually classified into: • Anomalies of the teeth • Skeletal anomalies. Anomalies of the teeth: -These include abnormalities of the teeth in: ❖ Number ❖ Structure ❖ Size ❖ Shape ❖ Position. Abnormalities in number: - Hypodontia It’s a condition at which the patient has missing teeth as a result of their failure to develop. It could happen in Ectodermal Dysplasia [lack of hair, sweat glands, and teeth (partial anodontia)].

Lec.10 Radiology Dr.Sura

Hypertonia It’s a condition of having supernumerary teeth, or teeth which appear in addition to the regular number of teeth. When classified by position, a supernumerary tooth may be referred to as a mesiodens, a paramolar, or distomolar. The most common supernumerary tooth is a mesiodens, which is a mal-formed, peg-like tooth that occurs between the maxillary central incisors. Fourth and fifth molars that form behind the third molars are another kind of supernumerary teeth. It could be associated with Cleidocranial Dysplasia (an inherited disorder involving the cranium, face, clavicles and supernumerary teeth).

Abnormalities in structure: The Abnormalities in teeth structures are subdivided into: 1- Genetic defect: - Amelogenesis imperfect Genetic disturbances in enamel formation leading to altered morphology of enamel. There is normal dentin and pulp formation

Lec.10 Radiology Dr.Sura

Dentinogenesis imperfecta In dentinogenesis imperfect there is pulp obliteration and short blunt roots.

Odontodysplasia (ghost teeth) A marked decrease in radiodensity, very thin enamel and dentin with large pulp chamber.

Lec.10 Radiology Dr.Sura 2- Acquired defects: - Turner hypoplasia It’s a frequent pattern of enamel defects seen in permanent teeth secondary to periapical inflammatory disease of the overlying deciduous tooth. The altered tooth is called (Turner’s tooth).

- Congenital syphilis It’s a dental hypoplasia that results from direct infection of the developing tooth by spirochete of syphilis, involves the permanent incisors that called (Hutchinson's teeth) and first molars that called (mulberry molars).

Abnormalities in size: - Macrodontia( large teeth) It’s a condition in which the teeth are abnormally large, also called megadontism, or megalodontia.

Lec.10 Radiology Dr.Sura

Microdontia (small teeth) It’s a condition in which teeth appear smaller than normal. In the generalized form, all teeth are involved. In the localized form, only a few teeth are involved. The most common teeth affected are the upper lateral incisors and third molars. The affected teeth may be of normal or abnormal morphology. There are 3 types of microdontia: 1. True generalized microdontia 2. Relative generalized microdontia 3. Microdontia involving a single tooth

Abnormalities in shape: - Fusion Two teeth joined together into a single anatomic crown (union of two separated tooth germ)

Lec.10 Radiology Dr.Sura

Gemination Two teeth joined together arising from a single tooth germ (single root with two anatomic crowns).

Dens invaginatus It’s a malformation of teeth most likely resulting from an enfolding of the dental papilla during tooth development or invagination of all layer of the enamel organ in dental papillae

Lec.10 Radiology Dr.Sura

- Enamel pearl It’s small spherical enamel masses located at the root of the molars and are found in 2% of the population. There can be a small pulp chamber extending from the parent tooth.

Taurodontism It’s a condition found in the molar teeth of humans whereby the body of the tooth and pulp chamber is enlarged vertically at the expense of the roots. As a result, the floor of the pulp and the furcation of the tooth is moved apically down the root.

Lec.10 Radiology Dr.Sura

Talon cusp: It’s an Accessory cusp like structure projecting from the cingulum area or cement- enamel junction of the maxillary or mandibular anterior teeth.

Abnormalities in position: The Abnormalities in teeth position may caused by: Local causes: — Loss of space — Overcrowding — Additional teeth — Retention of deciduous predecessor

Lec.10 Radiology Dr.Sura Systemic causes — Metabolic diseases — Developmental disturbances — Hereditary conditions. Skeletal anomalies e.g. Micrognathia, Macrognathia, Cleft lip and palate, Torus palatines, Torus mandibularis.