CT and MR Appearance of Teeth: Analysis of Anatomy and Embryology and Implications for Disease

Abnormalities of dental development and anatomy may suggest the presence of congenital or acquired anomalies. The detection of abnormalities, therefore, is an important skill for radiologists to achieve. Knowledge of dental embryology and an understanding of the radiologic appearances of teeth at various stages of maturation are required for the appreciation of abnormal dental development. While many tooth abnormalities are well-depicted on dedicated dental radiographs, the first encounter with a dental anomaly may be by a radiologist on a computed tomographic (CT) or magnetic resonance (MR) exam performed for other reasons. This article depicts normal dental anatomy and development, describing the appearance of the neonatal dentition on CT and MRI, the modalities most often encountered by clinical radiologists. The radiology and dental literature are reviewed, and key concepts are illustrated with supplemental cases from our institution. The value of knowledge of dental development is investigated using the analysis of consecutive MR brain examinations. Finally, the anatomical principles are applied to the diagnosis of odontogenic infection on CT. Through analysis of the literature and case data, the contrast of dental pathology with normal anatomy and development facilitates the detection and characterization of both congenital and acquired dental disease.

Pediatric Odontogenic and Paranasal Sinus Infections

Odontogenic and sinogenic infections are frequently encountered in the pediatric population. Although the diagnosis is often suspected clinically, imaging can play a significant role in localizing the site of infection, assessing for involvement of deep neck spaces, detection of abscess and other potentially life-threatening complications, and providing valuable information to help with treatment planning. This article reviews the general imaging considerations and anatomy relevant to odontogenic and paranasal sinus infections and describes the salient clinical and imaging features of infectious diseases of the dentition and sinuss.

Infections of the Oral Cavity and Suprahyoid Neck

Acute infections of the oral cavity and suprahyoid neck range from simple superficial conditions that can be treated as an outpatient to complex multispatial processes that require surgical intervention and inpatient admission. This article provides an imaging overview of the range of infections in this region that may be encountered by oral and maxillofacial surgeons, emergency physicians, and primary care providers.

Association between Oral Pathology, Carotid Stenosis, and Oral Bacterial DNA in Cerebral Thrombi of Patients with Stroke

Methods

Thrombus aspirates and control arterial blood were taken from 71 patients (70.4% male; mean age, 67.4 years) with acute ischemic stroke. Tooth pathology was registered using CT scans. Carotid stenosis was estimated with CTA and ultrasonography. The presence of bacterial DNA from aspirated thrombi was determined using quantitative PCR. We also analyzed the presence of these bacterial DNAs in carotid endarterectomies from patients with peripheral arterial disease.

Results

Bacterial DNA was found in 59 (83.1%) of the thrombus aspirates (median, 8.6-fold). Oral streptococcal DNA was found in 56 (78.9%) of the thrombus aspirates (median, 5.1-fold). DNA from A. actinomycetemcomitans and P. gingivalis was not found. Most patients suffered from poor oral health and had in median 19.0 teeth left. Paradoxically, patients with better oral health had more oral streptococcal DNA in their thrombus than the group with the worst pathology (p = 0.028). There was a trend (OR 7.122; p = 0.083) in the association of ≥50% carotid artery stenosis with more severe dental pathology. Oral streptococcal DNA was detected in 2/6 of carotid endarterectomies.

Conclusions

Stroke patients had poor oral health which tended to associate with their carotid artery stenosis. Although oral streptococcal DNA was found in thrombus aspirates and carotid endarterectomy samples, the amount of oral streptococcal DNA in thrombus aspirates was the lowest among those with the most severe oral pathology. These results suggest that the association between poor oral health and acute ischemic stroke is linked to carotid artery atherosclerosis.

Imaging of dental infections

Dental infections are a common presentation in the emergency department (ED). To help guide clinical management for these infections, the radiologist must be familiar with the anatomy of the oral cavity and neighboring structures, the range of appearance of dental infections, and the routes along which they may spread. Computed tomography (CT) is often performed when severe dental infections are suspected. This pictorial essay reviews the anatomy pertinent to the imaging evaluation of dental infections and depicts a spectrum of pathology that may be encountered, ranging from simple dentoalveolar infections to complex multispatial infections.

Dental Emergencies: A Practical Guide

Dental disease is a frequent finding on head and neck images, especially in the context of emergencies, and can be a challenge for radiologists who are inexperienced with findings of dental trauma or disease. Dental abnormalities can be subtle and therefore must be included in the systematic approach to these images. Although dedicated dental images are not acquired in most emergency cases, the teeth are included on many different images of the head and neck, and their initial evaluation seldom requires a specific protocol. The high prevalence of craniofacial trauma, sinus infection, and maxillomandibular procedures, among other conditions, frequently requires interpretation of dental images in daily emergency practice. The imaging findings can be categorized into infection, trauma, and complications of procedures, although sometimes these categories can overlap. Such categories can help the radiologist decide which imaging protocol and dynamic maneuvers should be used and are also useful when reading images and proposing differential diagnoses. Familiarity with the imaging findings of dental emergencies improves the radiologist's diagnostic confidence and role in guiding patient care, avoiding progression to life-threatening conditions, and reducing aesthetic problems, dental loss, and related conditions. Information about the imaging protocols is provided, the relevant anatomy of the teeth and related structures is reviewed, and the key imaging findings of dental emergencies are presented.^©RSNA, 2019.

Prevalence and Reporting Rates of Incidental Dental Disease on Head CT Examinations

RATIONALE AND OBJECTIVES

Routine head computed tomography (CT) examinations often inadvertently include dental pathology which is often overlooked. The purpose of this study is to examine the prevalence of dental disease incidentally present and detected on head CT examinations, and to determine the effect of the institution of a dental disease field or macro in a standardized head CT dictation template on the rate of reporting dental disease.

MATERIALS AND METHODS

Head CT examinations were retrospectively and randomly selected from all examinations performed 6 months before, and 6 months after the institution of a dental disease field in a standardized head CT template. Dental findings were recorded from the initial finalized report. Examination images were subsequently reviewed for the presence of dental disease by two neuroradiologists who were blinded to the original reports and to each other's findings.

RESULTS

One hundred examinations were reviewed in the analysis. At our institution, 33% of the randomly selected head CT examinations included the level of the teeth (100/307). Dental disease was determined to be present in 40%-41% of these cases. Only 11% of the initial reports mentioned dental disease (P < .01). Addition of a dental disease field in the dictation template resulted in no significant difference in reporting dental disease (14% vs 8%, P = .371).

CONCLUSIONS

Incidental dental disease is common and frequently underreported. Inclusion of a dental disease field in a standardized template does not significantly improve the rate of reporting dental disease.

Detection of Dental Pathologies in Routine Paranasal CT Scans: A Retrospective Study

INTRODUCTION

Multidetector Computed Tomography (MDCT) is a widespread method for evaluating paranasal sinuses and nasal cavity in daily practice. The maxillary teeth are in field of view in a paranasal sinus CT scan and it is possible to detect dental pathologies with CT.

AIM

To determine the incidence of maxillary teeth pathologies in routine paranasal sinus CT scans.

MATERIALS AND METHODS

A retrospective study was conducted. Consecutive 395 paranasal sinus CT scans were evaluated. All CT images were obtained with a 64 detector-CT. Patients with previous facial trauma, operation, invasive tumors and repeated exams were excluded. Detected findings were classified as "tooth loss, dental restorations or procedures and dental pathologies (carious lesions, dental developmental anomalies, periapical lesions and periodontal diseases). The proportion of findings was reported as simple percentiles.

RESULTS

Three hundred and eighty-four CT scans were included in the study. Dental restorations or procedures were determined in 129 (33.5%) patients. A total of 34 (8.8%) patients had normal teeth count and morphology. A total of 264 (64.3%) patients had at least one tooth loss. A total of 195 (51%) patients had at least one or more dental pathology. Number of dental carious lesions, dental developmental anomalies, periapical lesions and periodontal disease were 104 (27.0%), 78 (14.3%), 46 (11.9%), 44 (11.4%), respectively.

CONCLUSION

Dental pathologies were encountered in more than half of the patients. Detecting dental pathologies may prevent tooth loss and improve oral health. The radiologist should keep in mind dental pathologies while evaluating paranasal sinus CT in daily practice.