This article emphasizes the selection criteria for radiographic acquisition in children due to the greater sensitivity of children for radiation compared with adults. Diagnosis of common pediatric dental conditions, including dental caries, periodontitis, dental anomalies, cysts, tumors, and traumatic dental conditions, are discussed with relevant clinical scenarios.
Children are susceptible to the deterministic and stochastic effects of radiation; hence, the risks, and benefits of ionizing radiation should be considered carefully prior to prescribing radiographs.
Recommendations have been put forth for prescribing dental radiographs for children in primary dentition, transitional dentition, and permanent dentition.
In routine dental practice, bitewing radiographs are useful to diagnose dental caries in proximal surfaces and monitor caries risk status.
Panoramic radiographs are helpful to assess dental development and detect developmental anomalies.
Computed tomography is employed as an adjunct to diagnose and treatment plan, certain dental anomalies, dentoalveolar infections, trauma, cysts, and tumors.
Children have increased cellular metabolism and life expectancy and often a decreased willingness to cooperate. When prescribing radiographs to children, exposure settings are adjusted to accommodate a smaller physique and less calcified structure. The risk and benefit ratio must be justified, optimizing protection where dose remains as low as reasonably achievable and applying dose limits appropriate for the individual. Mitotic cell activity in children is much higher than in post-pubescent persons of the same size, as is their life expectancy; this enables greater time and circumstance for tumor development or risk of exposure-induced cancer death.
Considering the potential greater effect of radiation in children, radiographs should be obtained based on the individual needs of a patient and calculated risk rather than determined by a general protocol. Radiographs commonly are prescribed in children for diagnosis and treatment planning of dental diseases and developmental abnormalities, monitoring growth and development, and assessment of dentoalveolar trauma. In an everyday dental practice, radiographs are obtained in children primarily for routine diagnosis for dental caries and assessment of growth and maturity. Some dental anomalies are identified as incidental findings during imaging. General dental practitioners should have adequate knowledge of diagnosing common developmental and pathologic conditions from radiographs to enable appropriate referral and timely management of those conditions. This article aims to describe radiographic diagnosis of common dental conditions in children.
Diagnosis of dental caries and periodontal conditions
A survey conducted by National Center for Health Statistics in the United States found that 23% of children ages 2 years to 5 years had dental caries in primary teeth. Similarly, 21% of children ages 6 years to 11 years had caries in permanent teeth. The prevalence was relatively higher in adolescents ages 12 years to 19 years, in whom 3 of 5 children had dental caries. It is imperative for dental practitioners to identify the caries at an early stage to take necessary steps to restore the teeth and avoid further progression of caries.
Although occlusal caries can be identified clinically, proximal caries requires further investigation. Proximal caries present on the distal surface of primary second molars increases the risk of developing caries on the mesial surface of the first permanent molars. The importance of bitewing radiographs in diagnosing proximal carious lesions has been emphasized and a recent study has reported that 30% of caries in proximal surfaces of posterior teeth could go undetected without radiographic examination. ,
The American Academy of Pediatric Dentistry recommends taking posterior bitewing radiographs on every new patient and at 6 months to 12 months intervals if the proximal surfaces cannot be examined visually or through probing the surfaces. Several classification systems are available to record and score interproximal caries, and the most commonly accepted system was proposed by the International Caries Classification and Management System/International Caries Detection and Assessment System. Based on the extension of the caries and the location, they are ben classified as initial lesions (RA) when radiolucency is seen in the enamel or outer surface of dentine, moderate lesions (RB) when lesion extends into dentine, and severe lesions (RC) when the caries involves inner surface of dentine or pulp ( Fig. 1 ).
Anterior Occlusal Radiographs
Maxillary anterior teeth are affected most commonly by dental caries, in addition to the molars in primary dentition. This is due mostly to nursing habits and prolonged duration of exposure to milk and sugars from the nursing bottle in the maxillary anterior region. Anterior occlusal radiographs are useful to detect extension of caries into enamel, dentine, or pulp, so appropriate treatment could then be planned. Usually, mandibular anterior teeth are least affected by dental caries; however, in severe caries, occlusal radiographs may be indicated for mandibular anterior teeth. An adult-sized periapical radiographic detector, in horizontal position, usually is used to obtain anterior occlusal radiographs in primary dentition ( Fig. 2 ).
In primary dentition, periapical radiographs commonly are indicated to evaluate the patency in periapical region of the root canal following involvement of caries. Ideally, radiolucency can be detected first in the furcation region due the presence of accessary root canals in primary molars, and this can be observed in bitewing radiographs. Sometimes, this could be the first indication of caries progression in the periradicular region, prompting further examination using the periapical radiograph to analyze the extension of infection. In pulp-treated primary molars, it is common to see internal or external root resorption. Although this is a manifestation of inflammation, it should not warrant any immediate treatment, because most such presentations heal over a period of time based on immune response of an individual. It is strongly recommended to follow-up at update radiographs at regular intervals.
Clinical and radiological diagnosis may not always correlate; hence, both findings must be taken into consideration when planning treatment. Periapical radiographs also are used as a diagnostic tool to evaluate resorption pattern of pulp-treated primary teeth and development status of the developing permanent teeth ( Fig. 3 ). In permanent teeth, a periapical radiograph is used to diagnose the presence of granuloma or a cyst that presents initially as widening of periodontal ligament (PDL) space followed by development of circumscribed or diffuse radiolucency in the apex of the root. This occurs as a sequela of long-standing pulpal infection due to caries or trauma.
Extraoral images, including panoramic radiographs or computed tomography (CT) scans, are indicated when the dental caries progress into a space infection. In the maxillary arch, it commonly is seen in the infraorbital region ( Fig. 4 ), whereas in the mandibular arch, it manifests as submandibular space infection. Extraoral space infections should be attended immediately and aggressively. The imaging techniques provide an overall insight on the spread of infection originating from the infected tooth.
Gingival and periodontal conditions
It was found that 9% of children and adolescents showed some evidence of abnormal bone resorption in the molar region due to periodontitis, proximal caries, stainless steel crowns, and pulp pathology. Most common gingival conditions in children do not warrant taking radiographs because the lesions are confined mostly to soft tissues. Periodontal conditions, however, like chronic aggressive and necrotizing periodontitis in children and adolescents present with bony changes that could be diagnosed from intraoral or panoramic radiographs. Generalized chronic periodontitis can be either localized or generalized and presents with loss of crestal bone surrounding all the teeth, particularly in a severe condition, when the clinical attachment loss in greater than or equal to 5 mm ( Fig. 5 ). Refer to the latest classification of periodontal and peri-implant diseases. Clinically, children and adolescents with aggressive periodontitis show severe interproximal attachment loss, categorized as localized aggressive periodontitis when 2 permanent first molars and incisors are involved and generalized chronic periodontitis when at least 3 teeth are involved other than molars and incisors. Periodontitis also can present as a manifestation of systemic disease in children, including diabetes, cyclic neutropenia, Down syndrome, hypophosphatasia, leukocyte adhesion deficiency, and Papillon-Lefèvre syndrome.
Diagnosis of trauma to primary and young permanent teeth
The prevalence of dental trauma is approximately 30% in the primary dentition and 20% in the permanent dentition. Particularly, in preschool children, oral injuries make up to 17% of overall bodily injuries. For optimal treatment outcome, correct diagnosis of the severity of the injury is essential and should be achieved through a comprehensive history taking and clinical examination along with radiographic assessment. In the event of trauma, radiographs serve as a diagnostic tool in the detection of injuries that often are not identified from clinical examination. Traumatic dental injuries based on both clinical and radiographic evidence enables making a better diagnosis than when based on clinical examination only. A study found that 2.5% of trauma to primary incisors were observed from radiographic evidence alone without any clinical evidence of trauma. Most recently, the International Association for Dental Traumatology has provided the most updated guidelines for clinical management in 3 separate sections for fracture and luxation injuries, avulsion injuries, and trauma to primary dentition respectively. Trauma to the dentoalveolar region can be observed in both primary and permanent dentition, and management strategies vary between these dentitions.
Trauma to the Primary Dentition
Traumatic dental injuries can be distressing to both child and caretaker, and this might lead to difficulty in performing history taking, clinical examination, or radiographs. In addition to assessment of medical history, including immunization record, a systematic approach should be followed in deriving a diagnosis. Thorough extraoral and intraoral examination should be performed to identify any soft tissue injuries. Examination of all the teeth to identify fractures or mobility should be conducted, followed by radiographs as necessary. Trauma to primary teeth can directly affect the developing permanent teeth due to close proximity. Any disturbance to the developing permanent teeth could result to enamel defects, impaction, or ectopic eruption of permanent teeth. Of all the injuries, intrusion and lateral luxation injuries commonly are associated with developmental anomalies in permanent dentition.
Fractures of tooth fragments and impregnation into soft tissue could be identified by palpation of lips, cheeks, or tongue, and radiographs can be taken at low exposures to identify the embedded tooth fragments. For complicated fractures, a periapical radiograph using size 0 film or an occlusal radiograph with a size 2 film should be taken using paralleling technique. Some root fractures may be obscured by the developing permanent tooth, so it is desirable to take several images at different vertical angles ( Fig. 6 ). For alveolar fractures, in addition to periapical radiographs, it is recommended to take a lateral cephalogram to establish the relationship between maxillary and mandibular dentitions.
Concussion injuries usually present with pain on touch but without mobility or displacement. In such cases, no radiographs are required. However, in subluxation, extrusive and lateral luxation injuries where the tooth exhibits mobility and sulcular bleeding, a periapical radiograph or occlusal radiograph might be indicated for baseline record, this could show widening of PDL space around the tooth. Lateral luxation with lingual displacement of the root could affect the development or eruption of the permanent tooth. For intrusive luxation, it is recommended to take periapical or occlusal radiographs to identify the side of displacement. When the apex of the tooth is displaced labially, the tooth appears shorter than the contralateral tooth. In contrast, if the tooth is displaced palatally, the tooth appears elongated. A similar radiograph is required for avulsion of primary tooth to identify any displacement of the permanent tooth. Reimplantation is not recommended considering potential damage to the developing permanent tooth. Among all injuries, intrusive luxation and avulsion are likely to affect the permanent tooth to a greater extent. Sometimes, trauma to primary incisors could result in dark gray coloring due to pulp necrosis. In the event of absence of clinical or radiographic symptoms, it is advised to follow-up, and root canal therapy not always is indicated. Follow-up radiographs are required for all traumatic injuries to primary teeth at designated time intervals.
Trauma to the Permanent Dentition
Several conventional and 2-dimensional images and angulations are recommended for traumatic injuries to the permanent dentition. Similar to the primary dentition, when soft tissue injury to lip, cheek, or tongue is evident due to trauma and the tooth fragment is missing, radiographs should be taken to rule out any embedded tooth structures. For enamel and dentine fracture, and with pulp exposure, it is recommended to take 1 parallel periapical radiograph and additional radiographs based on the injuries. For crown-root fracture, root fracture, and alveolar fracture, obtain 1 parallel periapical radiograph, 2 additional radiographs at different horizontal and vertical angulations, and occlusal radiograph. Cone beam CT (CBCT) additionally can be taken to visualize the direction of fracture in relation to the marginal bone and determine the crown and root ratio. Similarly, the same radiographic images are recommended for subluxation, intrusive, lateral and extrusive luxation injuries.
Avulsion is considered one of the most serious injuries to permanent teeth and it represents 0.5% to 16% of all oral injuries. Reimplantation is the ideal treatment of choice and the success of the treatment primarily depends on the extraoral time and the stage of tooth development. The survival of reimplanted tooth is good if the PDL cells are viable with the extraoral dry time less than 60 minutes ( Fig. 7 ). A periapical radiograph is indicated before reimplantation to evaluate the patency of the socket and to rule out marginal alveolar bone fractures and after reimplantation to verify the correct position of the tooth prior to splinting. Sometimes, root canal treatment might be indicated, and this should be initiated within 2 weeks. Radiographs should be taken based on the indicated treatment. Delayed reimplantation has poor prognosis, leading to replacement resorption, which present as ankylosis and infraocclusion. The rate of ankylosis and resorption varies based on several factors; hence, clinical and radiographic examinations are required at regular intervals to initiate appropriate treatment ( Fig. 8 ). Ideally, follow-up radiographs should be obtained for all traumatic injuries involving permanent teeth. Based on the extension of the injury, radiographs are recommended at 2 weeks, 4 weeks, 6 weeks to 8 weeks, 3 months, 6 months, 1 year, and yearly for at least 5 years.
Radiographic Imaging Following Dental Trauma
Panoramic radiographs can help detect condylar fractures. If unavailable, reverse Towne posterior-anterior projection can be recommended. These images provide nondetailed images of teeth, hence cannot detect additional trauma to the dentition. In such cases, it is advised to take CT or CBCT, particularly in cases involving midfacial fractures.
Based on the age of the patient and the stage of dental development, periapical radiographs (size 0–2) or occlusal radiograph (size 4) is recommended. Ideally, parallel images with positioning device are indicated for consistent repeated measurements. To detect root or alveolar bone fractures, it is recommended to take 2 horizontal or 2 vertical angulations. It is advised to project the central beam from +10° to −20° in relation to the normal angulation, which is perpendicular to the long axis of the tooth.
Diagnosis of common oral pathologies in children
As in cases of adults, radicular cysts are localized in the apex of nonvital permanent teeth of children. They usually are less than 1 cm in diameter and appear as well-defined round or pear-shaped unilocular lucent lesions with a well-defined cortical border ( Fig. 9 ). If the cyst is secondary infected, the cortical bone may be lost.