To understand the material in this text, it is imperative that the reader approach it in a systematic manner. Significant time is spent in the dental hygiene curriculum identifying and describing normal structures. Before one can identify the abnormal condition, it is necessary to have a solid understanding of the basic and dental sciences such as human anatomy and physiology, histology, and dental anatomy. Once one has a solid understanding of normal structures and those that are variants of normal, findings that deviate from normal and pathologic conditions are recognized more easily. The preliminary evaluation and description of these lesions are within the scope of dental hygiene practice and are truly among the most challenging experiences in clinical practice.
In the first part of this chapter the definitions of commonly used terms that describe the clinical and radiographic features of a lesion, including terms used for normal, variants of normal, and pathologic conditions discussed throughout this text, are presented. The reader is encouraged to use these terms in the clinical setting so that they become part of an everyday professional vocabulary, thereby facilitating communication between the hygienist and other dental practitioners in the clinical setting.
The second part of this chapter focuses on the eight diagnostic categories that provide a systematic approach to the preliminary evaluation of oral lesions. Each area is described, and the strength of that area in the diagnostic process is illustrated using specific examples of lesions.
The final part of the chapter includes conditions that are considered variants of normal and those that are benign conditions of unknown cause. Most are diagnosed from their distinct clinical appearance and history.
How is a diagnosis made? What are the essential components? The answers to these questions begin with data collection. The process of diagnosis requires gathering information that is relevant to the patient and the lesion being evaluated; this information comes from various sources.
Certain distinct diagnostic categories should be thought of as pieces in a puzzle, with each piece playing a significant role in the final diagnosis. The eight categories that contribute segments of information leading to the definitive or final diagnosis are (1) clinical, (2) radiographic, (3) historical, (4) laboratory, (5) microscopic, (6) surgical, (7) therapeutic, and (8) differential findings. It is important to note that usually one area alone does not provide sufficient information to make a diagnosis; the strength of the diagnosis is often derived from one or two areas. As the dental hygienist becomes more aware of the diseases and conditions discussed in this text, it will be most helpful to use the diagnostic categories as a guide to evaluating lesions..
Clinical diagnosis suggests that the strength of the diagnosis comes from the clinical appearance of the lesion. By observing the area in a well-illuminated clinical setting and palpating it if necessary, the clinician can establish a diagnosis for some lesions on the basis of color, shape, location, and history of the lesion. When a diagnosis can be made on the basis of these unique clinical features, biopsy or surgical intervention is not necessary. Examples of lesions that can be clinically diagnosed are Fordyce granules (Figure 1-15), torus palatinus (Figure 1-16), mandibular tori (Figure 1-17), melanin pigmentation (Figure 1-18), retrocuspid papillae (Figure 1-19), and lingual varicosities (see Figure 1-52). These lesions are described later in this chapter.
Other benign conditions of unknown cause that are recognized by their distinct clinical appearance include fissured tongue (Figure 1-20), median rhomboid glossitis (Figure 1-21), geographic tongue (Figure 1-22), and hairy tongue (Figure 1-23). These conditions are also discussed later in this chapter.
Sometimes the diagnostic process requires historical information in addition to the clinical findings. For example, an amalgam tattoo (focal argyrosis) can be observed as a blue-to-gray patch on the gingiva or mucosa where an amalgam restoration is or has been located (Figure 1-24). Although this condition is usually easily observed and a clinical diagnosis made, any history involving the area can still be very helpful in confirming the clinical impression. The patient in Figure 1-24 had root canal therapy and a retrograde amalgam on a deciduous tooth. The amalgam tattoo is observed in the apical area of the permanent central incisor; no evidence of an amalgam restoration exists in the entire anterior area. The history helped confirm the clinical diagnosis.
In a radiographic diagnosis the radiograph provides sufficient information to establish the diagnosis. Although additional clinical and historical information may contribute, the diagnosis is obtained from the radiograph. Conditions for which the radiograph provides the most significant information include periapical pathosis (Figure 1-25), internal resorption (Figure 1-26), external resorption (Figure 1-27), heavy interproximal calculus (Figure 1-28), dental caries (Figure 1-29), compound odontoma (Figure 1-30), complex odontoma (Figure 1-31), supernumerary teeth (Figure 1-32), impacted or unerupted teeth (Figure 1-33), and calcified pulp (Figure 1-34). Normal anatomic landmarks are also easily observed radiographically. In some cases the radiograph may show very distinct and well-defined structures such as the nutrient canals seen in Figure 1-35, A and B and the mixed dentition seen in Figure 1-35, C. Unusual radiographic findings are illustrated in Figure 1-36.