Maxillomandibular giant osteosclerotic lesions

Abstract Giant Osteosclerotic Lesions (GOLs) are a group of rarely reported intraosseous lesions. Their precise diagnosis is important since they can be confused with malignant neoplasms. Objective This retrospective study aimed to record and analyze the clinical and radiographic Giant Osteosclerotic Lesions (GOLs) detected in the maxillomandibular area of patients attending to our institution. Materials and Methods: Informed consent from the patients was obtained and those cases of 2.5 cm or larger lesions with radiopaque or mixed (radiolucid-radiopaque) appearance located in the maxillofacial bones were selected. Assessed parameters were: age, gender, radiographic aspect, shape, borders, size, location and relations to roots. Lesions were classified as radicular, apical, interradicular, interradicular-apical, radicular-apical or located in a previous teeth extraction area. Additionally, several osseous and dental developmental alterations (DDAs) were assessed. Results Seventeen radiopacities in 14 patients were found and were located almost exclusively in mandible and were two types: idiopathic osteosclerosis and condensing osteitis. GOLs were more frequent in females, and in the anterior and premolar zones. 94.2% of GOLs were qualified as idiopathic osteosclerosis and one case was condensing osteitis. All studied cases showed different osseous and dental developmental alterations (DDAs). The most common were: Microdontia, hypodontia, pulp stones, macrodontia and variations in the mental foramina. Conclusions GOLs must be differentiated from other radiopaque benign and malignant tumors. Condensing osteitis, was considered an anomalous osseous response induced by a chronic low-grade inflammatory stimulus. For development of idiopathic osteosclerosis, two possible mechanisms could be related. The first is modification of the normal turnover with excessive osseous deposition. The second mechanism will prevent the normal bone resorption, arresting the osseous breakdown process.


Introduction
During many years, two radiopaque entities were confused and known with different names: osteosclerosis, sclerosing osteitis, condensing osteitis, bone whorls, bone eburnation, chronic focal sclerosing osteomyelitis and idiopathic osteosclerosis. 25 In 1985, Stafne divided these lesions in two entities: Condensing osteitis (CO) and osteosclerosis. 12 CO lesions were known since the Brower, et al. 7 (1974) report. They presented the clinical, roentgenologic and microscopic findings of radiopaque, fusiform, painful, slow growing, clavicular swellings in two patients and, later, more cases were added 8 . COs are intrabony, radiopaque lesions associated to inflammatory processes, more commonly to low-grade inflammation and, to date, etiological factors associated to development of COs are numerous. 1,3,5,7,8,20,26 COs are infrequent lesions in the general population, they are more common in females and most of them appear as radiographic images smaller than 2 cm. 5,20,26 They are usually found in mandible and posterior regions are more commonly involved. 5,7,20,26,27 Idiopathic osteosclerosis (IO) lesions are reported in pelvis, long bones, maxilla and mandible mainly as asymptomatic, non-expansible, radiopaque or mixed images diagnosed at any age. IO was found in both genders and lacks any relationship to inflammatory, infectious or traumatic stimulus. It is more prevalent in females, more frequently found in mandible and posterior areas and it is considered as an anatomic variant or a developmental osseous entity. [9][10][11]18,19,23 In 1973, Smith 24 reported two cases of large osteosclerotic lesions located in the acetabular area and ileum suggesting, the term "giant bone island" to those radiopacities measuring 2 cm. Since then, numerous cases were reported in femur, tibia, ribs, pelvis, spine, sacrum, ilium and iliac bones. 4,6,21,22,24 These lesions measured from 2 to 10.5 cm 21 and were more frequently found in male patients. 6 To date, reports on the incidence in the general population are not published.
Kawai, et al. 17 (1996) wrote on the features of 21 intraosseous lesions larger than 2 cm, located in the maxillomandibular area and described their clinical, radiographic and microscopic features. This is the sole report on these lesions found in the maxillomandibular area.
During the review of the radiographs from the patients seeking stomatological attention to the Oral As COs, we diagnosed all radiopaque or mixed intraosseous images associated to teeth with deep caries or large restorations, lesions located in edentulous regions related to dental extraction and those located around teeth showing marked malposition or served as abutments for fixed bridges or partial dentures. Also, images related to teeth under orthodontic forces or those associated to resorption of the adjacent teeth were also included.
Assessed parameters of the GOL studied were gender and age of the patients. Other parameters were: side, radiopaque or mixed appearance, shape, homogeneous or heterogeneous core, borders, size, location and relation to roots or bone. Classification: Analyzed lesions were grouped as radicular, apical, interradicular, interradicular and apical, associated  Figure 1 shows the different types of GOLs according to their relationship to adjacent tooth or teeth, and in Table 1 the main demographic data is presented.
Comparing mean size of the lesions in 30 year-old or younger patients and their size in older people, there were no statistically significance (p>0.05). Comparing the frequency of IO and CO, statistical difference was found (p<0.05). Also, frequency of GOLs in maxilla and mandible was statistically different (p<0.001).
All GOLs were considered as incidental radiographic findings, since they were all asymptomatic at first appointment and patients were unaware about their presence or development. Additionally, at clinical review, palpation of the involved zones showed no bony expansion, and even those cases located in a dental extraction area were painless lesions at exploration or interrogation.
Radiodensity of the images was statistically significant (p=0.01). Figure 2 shows a lesion in an  illustrates an image in radicular-interradicular place.
Radicular position is shown in Figure 5, and a CO located in an edentulous area is in Figure 6.
Detailed data on the type of GOL and the type of DDA found in each of the studied cases are presented in Figure 7.
Interestingly, we detected several cases showing unusual alterations in the mandibular foramina. One      Tilting of the related roots was seen in cases 1, 2, 6 and 9 (Figures 2 and 3). Additionally, patient 8 was previously diagnosed with the Prader-Willi syndrome ( Figure 8) and an odontogenic keratocyst in the right mandibular premolar-molar zone was previously resected to patient 4 ( Figure 9).

Discussion
This is the first report on three subjects: Diagnosis of GOLs in Latin American population and the presence of osseous and dental developmental alterations.
The presence of GOLs in the maxillomandibular  The term CO was first applied to "those instances in which sclerotic bone is most often dense and has been formed as a direct result of infection" 3  Frequency of CO lesions varied from 0.6% 20 to 6.9% 3 and it is more common in female patients. 1,3,5,26,27 Commonly, COs measure from 2 mm 5 to 6.5 cm 26 and it was reported that less than 2% were larger than 2 cm 5 . These lesions are more frequently found in mandible and in posterior zone. 7,5,20,26,27 An unexpected frequency of 33% was found in Iranian edentulous patients 3 . Proposed factors to explain the development of CO are numerous: inflamed dental pulp, orthodontic forces, dental eruption, deep dental caries, large dental restorations, dental extraction, teeth with marked malposition or teeth serving as abutments for fixed bridges or partial dentures. 1,3,5,7,8,20,26,27 IO is a radiopaque lesion previously detected in pelvis and long bones mainly. 14,19 It was defined as an asymptomatic, non-expansile, radiopaque or mixed lesion, developing in the tooth bearing area that occurs at any age, it appears in women and men, lacking any relationship with inflammatory, infectious or traumatic phenomena." 21 IO is a lesion preferentially found in females and more common in mandible and posterior areas, with preference by the premolar and molar zones. 9,11,19,23 To date, it is considered as an anatomic variant or a developmental bone lesion. 9,10,18 Analyzed GOLs present similarities and differences with those found in IO and CO previously reported series measuring less than 2.5 cm. 1,3,5,7,8,20,26,27 In our sample, IO:CO rate was 2.4:1, but in previously reported studies analyzing smaller cases, COs were more frequently found. 20, 26,27 As it has been reported, smaller IOs and COs rarely were painful lesions. 1,3,11,[18][19][20][21][22][23]26,27 Our studied examples were similar in mean age of the patients, gender and mandibular location to those reported in smaller IO and CO cases.
Interestingly, our finding on the higher frequency of GOLs in the anterior and premolar zones suggest that differences between GOLs and smaller IOs and COs could exist.
Similarities between our studied GOLs and the gigantic dense bone islands from Kawai, et al. 17 (1996) study exist. In both studies, more IOs than COs were found. They were more common in females and were mainly located in mandible. In contrast, premolar and molar zones were more frequently affected in the Kawai, et al. report 17 (1996), and in ours, GOLs were more commonly discovered in the mandibular anterior zone. Additionally, both studies found that round and homogeneous lesions were more frequent. Painful

Conclusions
It is possible that the abnormal bone deposit distinctive of both studied GOLs could be related with excessive bone activity producing accumulation.
For development of CO, two mechanisms working together could be related with its excessive osseous accumulation. The first is modification of the normal turnover producing increase of osseous deposition.
The second will prevent the normal bone resorption, arresting the osseous breakdown process.
Note that, as any retrospective study, ours only estimates the relative incidence of this entity in a defined period.