An Array of Patterns in the Diagnosis of Oral Pathosis

Introduction

Pathologies related to oral and para-oral regions show a wide range of clinical presentations and can manifest either as a locally occurring disease or any underlying systemic condition. Hence, oral health assessment becomes a vital element in ascertaining the underlying systemic health, and this may be a person's first indication of such systemic illnesses.¹

Radiographs including Intra-oral periapical radiograph (IOPAR), Bitewing, Cone beam computed tomography (CBCT), Orthopantomogram (OPG), Computed tomo-graphy and Magnetic resonance Imaging (MRI) have been considered a valuable diagnostic tool over the years. They benefit the clinicians by revealing many image patterns attributing to the disease or anatomical landmarks encountered. These x-ray films assist in dealing with uncommon lesions and a complex anatomy and thus in adjunct with the clinical presentation provides an insight to diagnosis.²

Such patterns help in the diagnosis of different conditions and can also help in further diagnostic approaches and thereby in treatment as well. All the patterns are, in their way, unique and elegant.

This review aims to explain the key features of various patterns seen in clinical and radiological settings, It will direct the medical professionals to make an accurate diagnosis.

Materials and Methods

Literature Search Strategy

An electronic search in PubMed and Google Scholar was performed for this review using the keywords, ‘patterns,’ ‘classic sign,’ ‘diagnostic imaging,’ ‘charac-teristic feature,’ ‘orthopantomogram (OPG),’ ‘skull radiographic features.’ Articles published in other languages were not taken into consideration for this evaluation; only English-language publications were. incomplete articles and articles pertaining to animal studies were excluded. The articles were selected from 1993-2022 and from the retrieved articles, some additional references were also cited.

Radiological Patterns

Bone/Hard Tissues

Soap bubble, honeycomb appearance

The bone appears as mixed radiolucent-radiopaque, with bony septa forming several internal compartments, originating from normal bone trapped within the tumour. Internal cystic components are common, often remodelling these septa into curved shapes resembling a honeycomb (multiple small compartments/loculations) or soap bubble (larger compartments of different sizes) appearance.² (Table 1 and Figures 1a and 1b).

Punched out appearance

Osteolytic lesions without a sclerotic rim are known as punched-out lesions.³ They are brought on by a confluence of tumor factors that inhibit osteoblasts and activate osteoclasts, which prevent reactive bone formation, resulting in a hole-like appearance. (Table 2 and Figure 1c).⁴

Ground glass appearance, Cotton wool appearance

The internal structure of bone shows abnormal trabeculae having shorter, thinner, irregularly shaped and numerous trabeculae than normal, giving it a granular, radiopaque pattern called ‘ground-glass appearance’, with ill-defined borders blending into normal adjacent bone.⁵ The bony trabeculae are present as round, radiopaque patches of abnormal bone resulting from thickened, disorganized trabeculae can cause sclerosis to develop in previously lucent bone regions, usually the skull. These patches exhibit uneven sclerosis zones and are puffy and poorly defined, fluffy and show irregular areas of sclerosis, giving a ‘cotton-wool appearance. (Table 3 and Figures 1d and 1e).⁶

 Sunray appearance

In radiography, a ‘sunray appearance’ can refer to new bone that forms perpendicular to the cortex, creating multiple lines resembling sunrays. This can happen when the periosteum is quickly stripped from the cortex, and substances like blood, inflammatory products, or granulomatous reactions come into contact with the exposed periosteum. This can be a sign of aggressive periostitis and is often associated with osteosarcoma, but can also occur with other aggressive bony lesions like Ewing sarcoma or osteoblastic metastases. (Table 4 and Figure 1f).⁷

Moth-eaten appearance

Areas of permeative bone deterioration with jagged edges and inadequate zones of transition are indicated by a moth-eaten appearance. It is caused by bone lysis and replacement with granulation tissue that widens Volkman’s canals and enlarges the medullary spaces. This results in bone fragmentation or sequestration in different foci of sclerosis and bone rarefaction. One Osteomyelitis is the most common cause of it. It is seen most commonly in osteomyelitis (Figure 1g).⁸

Onion skin appearance

Periosteal new bone growth is stimulated by chronic osteomyelitis and manifests radiographically as a single or many radiopaque lines parallel to the cortical bone surface, resembling an onion skin. The internal structure of sialolith is a homogeneous radiopacity having a laminated pattern resembling an onion skin (Figures 1h, 1i).⁹

Cookie-bite

Cookie-bite lesion was first used by Deutsch et al., to describe a saucerized, osteolytic, cortical, metastatic lesion, occurring in the mandible from bronchogenic carcinoma (most commonly). The possible mechanism for such metastasis is arterial dissemination via the vascular network of the periosteum (Figure 1j).¹⁰

Spoke - wheel appearance

Worth HM described the formation of linear bony spicules arising from the bone surface, resembling a hub or spoke-wheel pattern. This is seen when the central (intraosseous) hemangioma perforates the outer cortex and displaces the periosteum. It is commonly seen in the vertebrae and skull, with the jaws being rarely affected (Figure 1k).¹¹

Sharpened pencil appearance

Almost half the patients suffering from rheumatoid arthritis show temporomandibular joint (TMJ) involvement. It shows synovial proliferation (pannus) and erosions in the bone. This pannus causes disc destruction and decreases the joint space width. The anterior aspect of the condylar head and articular eminence are frequently damaged. At the locations where the synovial lining attaches, the anterior and posterior condylar surfaces erode, giving the condyle the appearance of a sharpened pencil (Figure 1l).¹²

Beaten copper appearance

A beaten copper appearance is a feature seen in normally growing individuals, which represents the gyral pattern of the growing brain. A more diffuse pattern however indicates an increased intracranial pressure from the growing brain. They appear as multiple radiolucencies due to depressions in the inner surface of the cranial vault, owing to elevated pressure from the growing brain in individuals with premature craniosynostosis (closure of cranial sutures), resulting in a beaten copper appearance. The coronal suture closes first, followed by all the other cranial sutures (Figure 1m).¹³

Bird’s beak appearance

Radiographically, osteoarthritis presents with flattening and osteophyte formation on the anterosuperior surface of the condyle, creating a wider articulating surface that resembles a “bird’s beak.” It is a non-inflammatory disorder characterized by both joint deterioration (bone erosion) and bony proliferation (osteophyte formation and subchondral sclerosis), which ultimately destroys the articulating fibrocartilage and leads to bone destruction. The possible etiology is the inability of the joint to adapt to excessive forces (Figure 1n).¹⁴

Snow driven appearance

According to radiography, calcifying epithelial odontogenic tumors (CEOT/Pindborg tumors) have scalloped, clearly defined borders and either unilocular or multilocular radiolucencies. The radiolucency shows calcifications of different sizes and densities, which are scattered, giving it a “driven-snow” appearance, and is often associated with an impacted tooth. It is a rare neoplasm of the jaws producing calcifications within an amyloid-like material and containing strands or sheets of polyhedral epithelial cells in a fibrous stroma (Figure 1o).¹⁵

Salt and pepper appearance

In skull radiographs, multiple, small, well-defined, radiolucent areas with dense dot-like foci are seen due to endosteal resorption, with reduced mineralization of the skull, called the “salt and pepper” appearance. It is caused due to increased bone remodelling and osteoclastic resorption, mobilizing calcium from bone and increasing its serum level (Figure 1p).¹⁶

Dental

Spiked root appearance

Root resorption usually occurs in a smooth pattern in benign tumors. In malignancies, smaller amounts of root resorption results in tapered narrowing of the root, giving it a ‘spike-like’ appearance (Figure 1q).¹⁷

Floating teeth appearance

Langerhans Cell Histiocytosis (LCH), an abnormal proliferation of Langerhans cells or their precursors, exhibits a radiographic appearance of the jaw where the bone destruction is so severe that teeth appear to be floating in the air. It begins in the teeth's mid-root area. A portion of the alveolar process's superior border is included in the circular progression of bone degradation, which gives the appearance of being scooped out. LCH appears in the ribs, pelvis, long bones, skull, and jaws. In the jaws, it causes bony swelling, soft tissue mass, gingivitis, bleeding gingiva, pain, ulceration and loosening of the teeth after the destruction of alveolar bone. Floating teeth appearance is also seen in periodontitis, but with reactive marginal sclerosis (Figure 1r).¹⁸

Bull’s eye appearance

Dilaceration is a tooth developmental defect causing a sharp bend or curve in the crown or root. The central beam of lingually or buccally dilacerated roots runs almost parallel to the dilacerated portion of the root. Consequently, the apical portion of the root takes on the appearance of a bull's eye, with a central radiolucency and a round or oval radiopacity. The PDL space surrounding the dilacerated part appears as a radiolucent halo around the radiopaque area (Figure 1s).¹⁹

Thistle tube appearance

Dentin dysplasia is an autosomal dominant condition. Two types of dentin dysplasia are- type I (radicular) and type II (coronal). In type II dentin dysplasia, the pulp chamber extends into the root and the root canal is thinned out giving it a “thistle tube” appearance (Figure 1t). In addition, pulp stones are frequently seen obliterating the pulp chambers and root canals.²⁰

Shell teeth appearance

Dentinogenesis imperfecta is a genetic condition affecting dentin.” They are known as "shell teeth" because they have larger pulps, very thin dentin, and enamel of typical thickness. Radiographically, these teeth have bulbous crowns, cervical constriction, thin roots, and early obliteration of the root canals and pulp chambers. There are three types of dentinogenesis imperfecta. Type I is associated with osteogenesis imperfecta and results from mutations in one of the two genes for collagen synthesis: COL1A1 or COL1A2 genes. Types II and III occur due to mutations in dentin sialoprotein (DSP) and dentin sialophosphoprotein (DSPP) genes (Figure 1u).²⁰

Ghost teeth appearance

Radiographically, the enamel and dentin are extremely thin with an enlarged radiolucent root canal and pulp chamber creating a pale wispy ‘ghost teeth’ appearance, seen in regional odontodysplasia. It is a rare abnormality affecting both enamel and dentin, making them hypoplastic and hypocalcified. Because the hypocalcified and hypoplastic enamel is stained, the impacted teeth seem tiny and mottled brown. Maxillary anterior teeth are commonly affected, especially central incisors. The affected teeth show delayed eruption and may not erupt in severe cases (Figure 2a).²¹

Soft Tissues

Tram track appearance

Monckeberg’s medial calcinosis (arteriosclerosis) shows fragmentation, degeneration and loss of elastic fibres, followed by calcium deposition in the medial coat of the vessel. The vessel lumen is normal with normal blood flow. It is common in patients with diabetes mellitus or chronic renal failure. It is asymptomatic initially, but as the disease progresses it may cause cutaneous gangrene, peripheral vascular disease and myositis due to vascular insufficiency. A calcified vessel might have a straight or winding route, appearing as a parallel pair of thin, radiopaque lines, resembling a pipe stem or tram-track appearance (Figure 2b).²²

Sausage string appearance

Sialodochitis is an inflammation of the ductal system of either parotid or submandibular gland. It occurs due to dilatation of the duct secondary to distal obstruction. In chronic conditions, interstitial fibrosis leads to constriction of a small portion of the dilated duct, which appears on sialography as a sausage-string appearance of the primary duct and major branches due to alternating strictures and dilatations (Figure 2c).²³

Hanging drop appearance/Trapdoor sign

When an item larger than the orbit, such as a fist or a ball, strikes the orbit directly, blow-out fractures of the orbital walls result. The impact force traverses the bone involving one or more thin walls of the orbit. Hanging drop appearance, a classical radiographic sign seen in Waters’ view is due to the presence of herniated orbital content like periorbital fat and inferior rectus muscle hanging from the bony defect of the orbital floor into the maxillary antrum. Coronal CT also shows the classic “trapdoor” sign of the displaced orbital floor in pediatric patients where the fractured orbital floor returns to its original position due to the young bone’s softness, potentially trapping orbital soft tissues (Figure 2d).²⁴

Doughnut appearance

A rare soft tissue ossification of the skin or subcutaneous tissues, osteoma cutis typically affects the face and is caused by the focused formation of bone within the dermis from an initial bone that has been surgically removed. Most occurrences are linked to skin injury, such as chronic inflammatory dermatosis, scarring, or long-lasting acne. Radiographically, osteoma cutis is common in the cheek and lip regions. Radiographically, it shows smooth, washer-shaped radiopacities. They are single or multiple, very small, uniformly radiopaque with a radiolucent centre representing normal fatty marrow, giving it a doughnut appearance (Figure 2e).²⁵

Cherry blossom appearance

A collection of conditions affecting the salivary glands that share autosensitivity is known as autoimmune sialadenitis. It is a frequent, painless enlargement of the salivary glands, which includes the lacrimal glands as well as the parotid gland. This causes xerostomia and exophthalmia (Primary Sjogren’s syndrome) and progressively involves the connective tissue causing rheumatoid arthritis, progressive systemic sclerosis, systemic lupus erythematosus or polymyositis (Secondary Sjogren’s syndrome). Sialography shows punctate and globular, spherical collections of contrast agent distributed evenly throughout the glands (sialectases). As the disease progresses, these collections of contrast agent appear larger in size and irregular in shape, forming cavitary sialectases, producing a ‘cherry blossom’ or ‘branchless fruit-laden tree’ appearance (Figure 2f).²⁶

Clinical Patterns

Dental

Bull teeth

The enlargement of a multirooted tooth's body and pulp chamber, along with the apical displacement of the pulpal floor and root bifurcation, is known as taurodontism. Taurodontism is either unilateral or bilateral and permanent teeth are commonly affected. Hammer et al. (1964) proposed that taurodontism results due to the failure of Hertwig’s epithelial sheath to invaginate at the proper horizontal level. The shape of the taurodont is like the molar teeth of cud-chewers i.e., ‘bull-teeth.’ (Figure 2g).²⁷

Screw driver incisors / Hutchinson’s incisors

Syphilis is a chronic infection caused by treponema pallidum. The primary modes of transmission include sexual contact (acquired syphilis) or from mother to fetus (congenital syphilis). In 1958, Sir Jonathan Hutchinson identified the Hutchinson triad, three pathognomonic diagnostic characteristics of congenital syphilis: Hutchinson's teeth, eighth nerve deafness, and ocular interstitial keratitis. Hutchinson’s incisors occur due to severe spirochaetal infection of the incisor tooth germ, causing calcium metabolic disturbances. They show the greatest mesiodistal width in the middle third of the crown with the incisal third tapering towards the incisal edge, giving it a screwdriver-shaped appearance. The incisal edge shows a central hypoplastic notch (Figure 2h).²⁸

Mulberry/Fournier’s molars

Congenital syphilis affecting the molars gives them a characteristic appearance. Mulberry molars result from severe infiltration of spirochaetes into the developing molar tooth germ. These teeth taper toward the occlusal surface, leading to narrowed occlusal outline. The occlusal anatomy shows abnormal, disorganized globular projections resembling a mulberry fruit (Figure 2i).²⁸

Peg lateral

A disease known as microdontia causes teeth to appear smaller than they actually are. It stands for microdontia affecting a single tooth as well as true generalized and substantially generalized cases. "Peg lateral," which affects the maxillary lateral incisors, is one of the prevalent types of localized microdontia. Converging mesial and distal surfaces incisally results in peg laterals, forming a peg-shaped or cone-shaped crown with roots that are shorter than usual (Figure 2j).²⁹

Submerged teeth

‘Submerged’ teeth frequently affect the primary dentition, most commonly the mandibular second molars. This condition occurs due to trauma to the dental follicle or developing periodontal ligament, followed by ankylosis to the bone. Exfoliation of such teeth is prevented, and permanent teeth do not erupt. However, the eruption of adjacent permanent teeth makes the ankylosed tooth look submerged below the level of occlusion (Figure 2k).³⁰

Pink tooth of mummery

Internal resorption is an uncommon type of tooth resorption that starts inside the tooth and is brought on by inflammatory pulp hyperplasia. Inflamed granulation tissue replaces the resorbed dentin. The "pink tooth of Mummery" was described by anatomist James Howard Mummery as crown discolouration resulting from loss of dentin and the presence of large, hyperplastic, vascular pulp tissue filling the resorbed area, visible through the tooth (Figure 2l).³¹

Bone/Hard Tissues

Bird face deformity

Ankylosis of the temporomandibular joint (TMJ) can be a bony or fibrous attachment of the joint’s anatomical components which can result in loss of function. The bilateral intracapsular bony ankylosis of TMJ is connected to mandibular retrognathism due to defective osteogenesis, resulting in a ‘bird face deformity’. This adhesion occurs either between the temporal bone's glenoid fossa and the mandibular condylar head, or between any soft or hard lower jaw tissue and the maxilla, zygoma, or the base of the skull, causing a disabling condition with problems in mastication, digestion, speech, appearance, and oral hygiene (Figure 2m).³²

Arnold head

Persistent open skull sutures, delayed closure of anterior fontanel, and depressed sagittal suture give the skull a flattened appearance. Cleidocranial dysplasia is characterized by frontal, occipital, and parietal bossing, which gives it a huge globular shape with a small face known as the "Arnold head. It affects several bones along with skull bones, of which partial or complete absence of clavicles is the most striking feature. The skull base is dysplastic with reduced growth, resulting in increased skull width causing brachycephaly and hypertelorism (Figure 2n).³³

Kleeblattschädel (cloverleaf-shaped) skull

Cloverleaf-shaped skull, first described by Holtermuller and Wiedemann, represents a complex synostosis, presenting with enlarged tri-lobar skull, enlarged fontanelles, causing temporal bulging and a flat posterior skull, owing to premature closure of several sutures. Premature closure of the sagittal suture gives the skull a characteristic appearance, with horizontally enlarged head due to hydrocephalus, leading to disproportionate ballooning of the temporal horns. The ring of bone that divides the cloverleaf's top and lower leaves is the same. It is observed in severe cases of Thanatophoric dysplasia, Saethre-Chotzen syndrome, Carpenter syndrome, Apert syndrome, Crouzon syndrome, and Pfeiffer syndrome; Pfeiffer syndrome accounts for 15%-20% of cases (Figure 2o).³⁴

Eye to heaven appearance/Cherubic face

Cherubism is a rare autosomal dominant disorder marked by painless, symmetrical enlargement of the jaws, resulting from the replacement of normal bone with fibrous tissue. It typically presents with dental malocclusion, intact oral mucosa, and an absence of pain. The bilateral expansion of the mandible and/or maxilla leads to a characteristic rounded facial appearance with swollen cheeks often referred to as a "cherubic face." The condition also causes an upward gaze, as fibrous lesions in the maxilla extend into the orbital region, elevating the sclera beneath the iris, producing the classic "eyes raised to heaven" appearance (Figure 2p).³⁵

Leontiasis ossea (Lion facies)

In extreme cases of Paget’s disease, facial bones involved appear thickened and swollen producing a typical facial deformity known as ‘leontiasis ossea’, meaning the face of a lion. It is a skeletal disorder involving osteoclasts causing abnormal resorption and apposition of poor-quality bone due to intense osteoblastic activity in one or multiple bones. The axial skeleton, which includes the pelvis, femur, spine, skull, and tibia, is frequently damaged; the maxilla is slightly more impacted than the other jaw bones . Bone pain is the chief complaint which worsens at night. Other features such as bone expansion and deformities like bowing of legs, curvature of the spine and skull enlargement are also seen. Intra-oral features include jaw enlargement, expanding alveolar ridge causing denture tightening, flattened palate and excessive spacing between the teeth (Figure 2q).³⁶

Conclusion

Clinical signs and patterns provide essential details regarding the possible aetiology of any disease. Radiographs supplement clinical examination in establishing the diagnosis and guiding treatment, though certain diagnosis may be made mostly based on the clinical presentation. This pattern-based approach assists the dental practitioners and students to evaluate and provide definitive diagnosis and an efficient treatment planning.

Funding

Nil

Conflict of Interest

Nil