Bone and Other Lesions
Upon completing this chapter, the student will be able to:
1. Dene the key terms listed at the beginning of the chapter.
2. Utilize descriptive terminology in providing an
interpretation of bone and other oral lesions.
3. Discuss the following related to cysts, tumors, and bone
dierentiate their appearance from normal.
to formulate a complete radiographic diagnosis of bone
and other oral lesions.
foreign bodies and root tips, extraction sockets, salivary
stones, exostosis, and enostosis.
endostosis (dense bone island,
radiolucent (RL) lesion
radiopaque (RO) lesion
salivary stones, sialoliths, or salivary
Radiolucent versus Radiopaque
In describing or, in some cases, categorizing bone lesions,
they are referred to as radiopaque, radiolucent, or mixed. A
radiopaque (RO) lesion indicates an increase in the density
of the bone or new calcied material being formed (e.g.,
osteoma), whereas a radiolucent (RL) lesion indicates
a decrease in density or destruction of bone (e.g., cyst).
Mixed lesions have both processes occurring (e.g., periapi-
cal cemental dysplasia).
In making a diagnosis of a pathologic bone condition, loca-
tion is very important because some lesions have a predilec-
tion for certain areas of the mouth (e.g., ameloblastoma in
the mandibular third molar region).
Extent of the Lesion
e diagnostician must see the entire lesion and be able
to dene its borders and extent in three planes before
is chapter discusses the application of the principles
of radiographic interpretation previously included in
Chapter 20 to the identication and description of bone
and other ndings that may be discovered in the oral cavity.
It is important for the dental professional to have the skills
to properly identify and provide a description of oral
lesions (such as, cysts, tumors, metabolic bone lesions, trau-
matic lesions, foreign bodies, root tips, extraction sockets,
and salivary stones) when contributing to a successful diag-
Description of Lesions
After discovering a lesion radiographically, the diagnostician
must know certain facts about its radiographic appearance.
In gathering this information, more radiographs may be
required to assemble all the information necessary to make
the nal diagnosis. e following is a repetition of certain
diagnostic criteria and categories that illustrate the diagnos-
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26724 Bone and Other LesionsEDUCATIONAL OBJECTIVESUpon completing this chapter, the student will be able to:1. Dene the key terms listed at the beginning of the chapter.2. Utilize descriptive terminology in providing an interpretation of bone and other oral lesions.3. Discuss the following related to cysts, tumors, and bone lesions:• Recognizecysts,tumors,andbonelesionsanddierentiate their appearance from normal.• Understandwhichradiographicprojectionsareneededto formulate a complete radiographic diagnosis of bone and other oral lesions.4. Discusstheradiographicappearanceoftraumaticinjuries,foreign bodies and root tips, extraction sockets, salivary stones, exostosis, and enostosis.KEY TERMSbenign lesionbiopsyendostosis (dense bone island, idiopathic osteosclerosis)exostosis (hyperostosis)extraction socketfracturehyperostotic linesmalignancy (cancer)metabolic conditionmixed lesionradiolucent (RL) lesionradiopaque (RO) lesionsalivary stones, sialoliths, or salivary calculitrabecular patternRadiolucent versus RadiopaqueIn describing or, in some cases, categorizing bone lesions, they are referred to as radiopaque, radiolucent, or mixed. A radiopaque (RO) lesion indicates an increase in the density of the bone or new calcied material being formed (e.g., osteoma), whereas a radiolucent (RL) lesion indicates a decrease in density or destruction of bone (e.g., cyst). Mixed lesions have both processes occurring (e.g., periapi-cal cemental dysplasia).LocationIn making a diagnosis of a pathologic bone condition, loca-tion is very important because some lesions have a predilec-tion for certain areas of the mouth (e.g., ameloblastoma in the mandibular third molar region).Extent of the Lesione diagnostician must see the entire lesion and be able to dene its borders and extent in three planes before Introductionis chapter discusses the application of the principles of radiographic interpretation previously included in Chapter 20 to the identication and description of bone and other ndings that may be discovered in the oral cavity. It is important for the dental professional to have the skills to properly identify and provide a description of oral lesions (such as, cysts, tumors, metabolic bone lesions, trau-matic lesions, foreign bodies, root tips, extraction sockets, and salivary stones) when contributing to a successful diag-nostic process.Description of LesionsAfter discovering a lesion radiographically, the diagnostician must know certain facts about its radiographic appearance. In gathering this information, more radiographs may be required to assemble all the information necessary to make the nal diagnosis. e following is a repetition of certain diagnostic criteria and categories that illustrate the diagnos-tic procedures. 268 CHAPTER 24 Bone and Other LesionsCysts and TumorsAll cysts located in bone are seen as RL areas. Tumors can appear RL, RO, or mixed. When the cyst or the tumor appears RL (e.g., ameloblastoma), the lesion has destroyed normal bone and replaced it with less dense cystic or tumor tissue (Fig. 24.3). If the lesion is RO, this signies that the new tumor tissue being formed has a greater density or size than the tissue it is replacing (Fig. 24.4). e mixed lesion may have a variety of densities. Tumors of bone and cartilage appear RO; all other tumors appear RL. e odontoma has a variety of densities corresponding to the densities of tooth structure (i.e., enamel, dentin, cementum, and pulp; Fig. 24.5).Metabolic Bone LesionsMany metabolic conditions, which occur when abnormal chemical reactions in the body alter the normal metabolic process, manifest with changes of the trabecular pattern and lamina dura of the bone in the mandible and maxilla. Examples of this type of disease process are Paget’s disease (cotton wool bony appearance), hyperparathyroidism, and certain types of anemia. e dental professional’s role is not any type of treatment is instituted. Large pathologic areas often require the use of panoramic, extraoral, computed tomographic (CT), cone beam computed tomographic (CBCT), or magnetic resonance projections to obtain this information.Benign versus Malignante possibility of malignancy (cancer) must be considered when diagnosing an unknown lesion. In general, malignan-cies tend to have poorly-dened radiographic borders and destroy normal anatomic structures (Fig. 24.1). Benign tumors and cysts expand slowly, with clearly dened borders referred to on radiographs as hyperostotic lines. eir slow growth tends to displace rather than destroy structures. As seen on occlusal projections, benign lesions expand the buccal and lingual cortex of bone, whereas malignant lesions perforate and invade neighboring tissue (Fig. 24.2). is eect on the buccal and lingual cortices can be seen best on right-angle occlusal projections of the maxilla and mandible, as well as on CT and CBCT scans.BA• Figure 24.1 A, Lateral oblique radiograph showing destruction of the coronoid process by a malignant tumor. B, Periapical radiograph of the maxillary premolar area showing complete bone destruction as evidenced by the radiolucent (RL) malignant lesion. BA• Figure 24.2 A, Occlusal radiograph showing expansion of the buccal and lingual plates of the mandible caused by a benign tumor. B, Occlusal radiograph showing perforation and spread through the buccal and lingual cortices by a malignant tumor. 269CHAPTER 24 Bone and Other Lesions• Figure 24.4 Panoramic radiograph showing a well-dened radiopaque (RO) tumor in the left maxillary sinus. Compare right and left maxillary sinuses. • Figure 24.5 Radiograph of an odontoma. Note the densities that correspond to tooth structures. NOTEThe following is an exercise in applying the principles of interpretation when identifying an oral lesion: A dental professional described a radiolucent (RL) lesion in the mandibular third molar region as being multilocular and locally invasive on a radiographic image (see Fig. 24.3). Judging by this description, this lesion could be identied as an ameloblastoma, among other possible lesions. An ameloblastoma is a locally aggressive benign tumor, commonly found in the posterior region of the mandible or, less commonly, in the maxilla. This lesion appears RL and could be multilocular or unilocular and can be benign or malignant. Ultimately, the denitive diagnosis would depend on the results of a biopsy (an examination of tissue removed from a lesion to discover the presence, cause, or extent of a disease) performed on the specimen sample.• Figure 24.3 Radiograph of a tumor (ameloblastoma) envelop-ing teeth on the right side of the mandible. to diagnose these diseases but rather to recognize the change from normal as seen on the radiographs (Figs. 24.6 to 24.8) and then refer the patient for treatment.Traumatic InjuriesFractures of teeth, especially anterior teeth, are very common. Clinically and radiographically, a fracture of the crown of a tooth is easier to detect than a root fracture. e fracture appears on the radiograph as a RL line or the missing part of the tooth is apparent (see Fig. 24.7). A root fracture also is seen as a RL line but is much more dicult to visualize because of superimposition of alveolar • Figure 24.6 Paget’s disease. Lateral skull projection showing the characteristic “cotton wool” appearance of Paget disease of bone. 270 CHAPTER 24 Bone and Other Lesionsneeded for complete visualization (Figs. 24.11 and 24.12). e fracture appears as a RL line, and radiographs may show displacement of the fracture segments.Foreign Bodies and Root TipsAny sort of foreign body can be embedded in the jawbones. Only those that are RO can be seen radiographically. Metal-lic foreign bodies are the most common and the easiest to see because of their increased density and appear more RO than bone. ese radiopacities may be amalgam, burrs, broken instruments, needles, or metallic fragments from an external source (Fig. 24.13), wires used to reduce fractures, or metallic implants (Figs. 24.14 and 24.15).Retained root tips have the density of tooth structure (Fig. 24.16); thus, sometimes it is dicult to distinguish between the retained root tip and dense areas of bone. One way to achieve this dierentiation is by the appearance of a pulp canal or the conical shape of a root tip. ese root tips should be localized radiographically in three dimensions before treatment is attempted.Extraction SocketsExtraction sockets may be radiographically evident in the bone up to 6 months after surgery. ey initially appear as bone trabeculation (Figs. 24.9 and 24.10). Tooth and root fractures can lead to pulp damage and ensuing periapical pathologic conditions. Fractures of the maxilla and man-dible may be seen in part on periapical projections, but larger views, such as panoramic or other extraoral lms, are • Figure 24.7 Radiolucent (RL) lesion of hyperparathyroidism seen between roots of premolars. • Figure 24.8 Trabecular bone pattern of anemia. Note the enlarged medullary spaces. • Figure 24.9 Root fracture near apex of the maxillary central incisor. • Figure 24.10 Root fracture, maxillary central incisor. 271CHAPTER 24 Bone and Other Lesions• Figure 24.11 Panoramic radiograph showing fractured mandible. • Figure 24.12 Fracture of mandible on a lateral oblique projection. • Figure 24.13 Metallic foreign body in the mandible. • Figure 24.14 Metallic implant of the mandible serving as a distal abutment. Note the thinning of bone, indicating start of the rejection process. • Figure 24.15 Osseointegrated (endosseous) implant seen on a periapical radiograph. • Figure 24.16 Retained root tip in the maxillary molar region. RL areas, and then the area eventually lls in with bone in the normal trabecular pattern (Fig. 24.17).Salivary Stones (Sialoliths or Salivary Calculi)Although not a bone lesion, salivary stones are included here because salivary gland disease is often treated by the dentist and can be seen on dental radiographs. Although the 272 CHAPTER 24 Bone and Other Lesions• Figure 24.17 Extraction socket in the mandible. • Figure 24.18 Occlusal radiograph of an edentulous mandible showing a radiopaque (RO) salivary stone in the submandibular duct in the oor of the mouth. • Figure 24.19 Salivary stone seen on a panoramic image . The stone is seen twice, as this Panoramic unit produces a redundant image. locations as discussed in Chapter 19 of this text. Other areas of external bone growth can be present anywhere in the oral cavity but most commonly occur on the buccal surfaces of the maxillary canines and molar regions. An endostosis, also known as a dense bone island or idiopathic osteo-sclerosis (Fig. 24.20) is an internal growth of bone that is considered to be the internal version of exostoses. Both exostoses and enostoses appear RO on radiographic images and are asymptomatic and within normal limits. Exostoses are identied on clinical and radiographic examination. e identication of endostosis (dense bone island, idiopathic osteosclerosis) is usually made as a result of a radiographic examination only.salivary glands and ducts are soft tissue, radiographs are still important in the diagnostic workup. Salivary stones, also known as sialoliths or salivary calculi, are a common cause of obstruction, secondary swelling, and infection. Because the sialolith is calcied, it can be seen on radiographs. Stones in the submandibular duct can be seen best on a mandibular right-angle occlusal projection (Fig. 24.18). Stones also can be seen on panoramic radiographs and periapical projections but may appear as superimpositions on the radiograph (Fig. 24.19). Advanced imaging systems, including CBCT and CT scanning images, are also used to locate salivary stones. For the parotid gland, in which stones are not so common, a lateral oblique, posteroanterior, CT scan, or soft tissue projection with the receptor placed in the mucobuccal fold can be employed.Exostosis and EnostosisAn exostosis (hyperostosis), by denition, is an over-growth of bone on the surface of the alveolar bone. Both torus palatinus and torus mandibularis are considered to be areas of exostoses but are located in their respective specic 273CHAPTER 24 Bone and Other Lesions• Figure 24.20 Endostosis (dense bone island, periapical idiopathic osteosclerosis) in the mandibular premolar region. (From White SC, Pharoah MJ: Oral radiology: Prinicples and interpretation, ed 7, St Louis, 2014.)Chapter Summary• When identifying bone and other lesions in the oralcavity, the dental professional should note the radio-graphic appearance, location, and extent of the lesion.• eradiographicappearanceoftheorallesionsdiscussedin this chapter is dependent on the actual density of the structure.• edentalprofessionalshouldchoosethetypeofradio-graph that will include the entire lesion on the image.• e dental professional should know the radiographicappearance and other identifying characteristics of common oral ndings, including benign lesions, malignant lesions, various cysts and tumors, metabolic bone lesions, fractures, foreign bodies, retained root tips, extraction sockets, salivary stones, exostoses, and enostoses.Chapter Review QuestionsMatchingMatch the term in Column A with the appropriate radio-graphic appearance in Column B.Column A Column B1. Paget’s disease2. Odontoma3. Endosseous implant4. Fracture5. Retained root tip6. Benign lesion7. Malignant lesion a. Has poorly dened radiographic borders b. Has the density of root structures c. “Cotton wool” appearance d. Appears as a RL line e. Has a hyperostotic border f. Mixed lesion corresponding to tooth structures e. Has the radiopacity of a metallic objectCase-Based ExercisesIdentify the oral lesion that the following case descriptions and images are referring to. Provide an answer for items a, b, and c associated with each case.1. A male patient presents to your dental clinic with pain and swelling in the oor of his mouth. After a clinical examination is performed, a panoramic radiograph is taken of the patient and the lesion plus a ghost image (refer to Chapter 12) of the lesion is seen. 274 CHAPTER 24 Bone and Other LesionsBibliographyWhite SC, Pharoah MJ: Oral radiology: Principles and interpretation, ed 7, St Louis, MO, 2013, Mosby. a. Describe the radiographic appearance of the lesion. b. Discuss the location of the lesion. c. Comment on whether the radiograph taken is suf-cient or if another type of image could be utilized in the case. d. What do you think this oral lesion could be?2. A patient presents for a follow-up visit with no com-plaints or symptoms. A selected periapical radiograph of the area that a recent procedure was performed in is prescribed. a. Describe the radiographic appearance of the lesion. b. Discuss the location of the lesion. c. Comment on whether the radiograph taken is suf-cient or if another type of image could be utilized in the case. d. What do you think this oral lesion could be?