Research: Prevalence of Dense Bone Island

Dense bone island (DBI) can be defined as an “asymptomatic, uniformly radiopaque foci of dense bone, the existence of which is not the apparent sequel of a local infection or systemic disease.”¹ These lesions are occasionally observed in the alveolar process of the jaws, most commonly in the mandible. They may be noted at root apices, between roots or, in between teeth, primarily in the molar and premolar regions.^2-4

The term dense bone island was coined by McDonnell et al.³ DBI has been called different names such as idiopathic osteosclerosis,² enostosis,⁵ bone scar, bone whorl, and bone eburnation. DBI is seen not only in the jaws but also in other skeletal areas such as pelvic and long bones.⁶ DBI has very broad spectrum of presentation. There is a variation in the size of DBI, which may range from a few millimeters to about 2 centimeters. These islands are developmental anatomic variations identified incidentally on radiographs. Possible complications of DBI in jaws are changes in tooth position, which could create complications in orthodontic treatment.⁷ Another relatively less noted complication is DBI with root resorption.⁸ The affected tooth is usually asymptomatic; simple vitality testing should rule out any further intervention.

A PubMed search revealed no studies dedicated to DBI with root resorption. The purpose of this study is to investigate and report the prevalence of DBI in a northeast Ohio population and its relationship to sex and age, its predominant location, and the number and shape of lesions.

The study was done retrospectively from January 2014 to May 2015 at Case Western Reserve University School of Dental Medicine, in the Department of Oral and Maxillofacial Medicine and Diagnostic Sciences. All cases were examined by one examiner using panoramic images, and occasionally peri-apical images were also reviewed. The examiner was consulted by another author if there was any doubt.

The panoramic radiographs were obtained digitally using the Planmeca Promax^® panoramic x-ray unit (Planmeca, planmeca.com) with SCARA technology (Selectively Compliant Articulated Robot Arm), 70 kV to 74 kV and 11 mA to 16 mA, with 16-second exposure time. During the exposure, settings were adjusted in accordance with each individual patient.

The purpose of this study was to investigate and report the prevalence of DBI with root resorption, with panoramic images of 4581 patients being analyzed. Additionally, the authors collected information regarding the patients’ age and gender; the location, number, and shape of lesions, and DBI’s association with root resorption. When in doubt, periapical (PA) radiographs were also evaluated for confirmation, because PAs have high resolution and can be better visualized.⁹

The inclusion criteria for images in the study included a well-defined radiopaque entity in the alveolar ridges and virgin teeth. The exclusion criteria for images in the study were as follows: (1) pediatric patients 14 years of age or younger; (2) teeth with caries or restorations and teeth associated with condensing osteitis; (3) characteristics of the lesion being mixed with radiopaque-radiolucent areas in the form of periapical cemental dysplasia and other benign fibro-osseous lesions or an odontoma; (4) increased thickening of the lamina dura around teeth with marked malposition or that served as abutments for fixed bridges or partial dentures; (5) radiopacities in edentulous regions; (6) remnants of deciduous or permanent teeth.

Radiopaque areas that were depicted as DBI were classified as follows²:

Inter-radicular: The radiopaque area was confinedbetween the roots and interrelated with the adjacent teeth lamina dura.

Inter-radicular and separate: The radiopaque area was confinedbetween the roots and not interrelated with the adjacent teeth lamina dura.

Apical and inter-radicular: The radiopacities were at the apices and showed significant extension between the roots.

Apical: The lesions were located around the apices of the roots.

Separate: The masses were located apically and clearly separated from the teeth and lamina dura.

The shape of the lesion was classified as round or irregular. The size of the lesion was measured by maximum height and width on Infinitt dental PACS (Infinitt, infinittna.com).

Figure 1 through Figure 3 illustrate cases depicting DBI, as noted on panoramic radiographs.

Panoramic radiographs of 4581 patients taken for general dental examinations were included in the study. The age group ranged from 15 to 84 years of age. There were 2490 males (54.4%) and 2091 females (45.6%) in this study.

DBI was noted in 147 cases (3.2%). Of these, 14 cases had two lesions and one case had three lesions. All in all, a total of 163 lesions were noted among 147 cases. Of the 163 lesions, 68 (41.7%) were seen in males and 95 (58.3%) in females; this is statistically significant. Of the 147 cases, root resorption was seen in four lesions, i.e., in 2.72% cases of DBI (Table 1). Figure 4 depicts DBI with root resorption.

In this study the size of the lesions varied from 3 mm to 33 mm. Table 2 shows that the lesions were round or irregular in shape, but mostly round (57.1%).

Among the age groups involved, DBI was most prevalent in subjects aged 15 to 24 years, and this is statistically significant. Table 3 shows the prevalence of DBI according to age.

A total of 14 lesions (8.6%) of DBI were observed in the maxilla and 149 (91.4%) lesions in the mandible. In the maxilla, right and left side was equally affected, whereas in the mandible, right side was most commonly affected (Table 4).

Figure 5 and Table 5 show the prevalence of DBI based on location. The most common location in the maxilla was at the incisors, while in the mandible it was at the premolars.

DBI lesions were mostly identified at the apices (44.8%) of teeth. Figure 6 and Table 6 show the prevalence of DBI location in relation to teeth.

The prevalence of DBI in this northeast Ohio population was about 3.2%, which is within the range of a previous study.² The reason that the prevalence was low compared to the remaining studies is because of the difference in definition of DBI and the inclusion criteria. The isolated radiopacities and nonvital carious and restored teeth were excluded, but these were included by other authors.⁴

In the present study, patients in their second and third decade were mostly affected. The findings are in correlation with the study done by Sisman et al.¹⁰ This is in relation with the study done. The reason might be because of the growth and modification of bone at that age.

The predilection for females was greater compared to males and was statistically significant, which is in agreement with other studies.^2,3,11,12 In some studies, there is no statistical significance between males and females.^4,13,14

Among the jaws, mandible was mostly involved compared to maxilla and was statistically significant. This may be because of the different radiographic techniques used (panoramic, periapical) and overlapping of anatomical structures in the maxilla. The most common location in the maxilla was at the incisor region, which is in agreement with other studies.^5,10 In the mandible, it was at the premolar region, which also is in agreement with other studies.^2,11 Some authors found more lesions at the mandibular molar region.^3,4,10,13

The lesions of DBI were mostly associated with the apical part of the teeth. This is similar to the study done by Sisman et al.¹⁰ The reason for this might be because of occlusal forces. Some authors reported separate lesions.¹⁴ A case report with DBI and root resorption was presented in a study by Marques et al.⁸ This is the first study to compare prevalence of DBI with root resorption. About four cases (2.72%) of resorption were reported. DBI with root resorption is a rare entity and is self-limiting in nature and requires no treatment or further follow-up. Cases should be considered as anatomical variants.¹⁵ Simple vitality test should rule out any treatment considerations.

This is the first study done to determine the prevalence of dense bone island in an Ohio population with a large sample size. Results from this study showed that DBI can occur at any age and at any location, with predilection for females. The lesions were mostly seen in the mandibular premolar apical area. Resorption was seen in few cases of DBI. In most cases, no treatment was rendered, however, radiographic monitoring was recommended.

Ali Zakir Syed, BDS, MHA, MS
Director of Radiology and Admitting Clinic
Assistant Professor
Department of Oral and Maxillofacial Medicine and Diagnostic Sciences
CWRU School of Dental Medicine
Cleveland, Ohio

Savitha Deepthi Yannam, BDS, MDS
Fellow, Restorative Dentistry
CWRU School of Dental Medicine
Cleveland, Ohio

Gedela Pavani, BDS
Former Fellow, Restorative Dentistry
CWRU School of Dental Medicine
Cleveland, Ohio
General Practice Residency
Meharry School of Dentistry
Nashville, Tennessee
General Dentist
High Point, North Carolina