Dental 3D Cone Beam CT Imaging: Part V Dental Incidentalomas (Pre-surgical analysis for the insertion of dental implants)
Dental 3D Cone Beam CT Imaging: Part V Dental
Incidentalomas (Pre-surgical analysis for the insertion of
Using 3D CT imaging for diagnostic purposes in medicine has uncovered incidental
tumors that had no clinical symptoms in various tissues when there was no previous
suspicion that they were present. These incidental tumors have been dubbed
“incidentalomas,” and been discovered in adrenal glands, kidneys, pituitary glands,
thyroid glands, liver, lungs, and the parathyroid glands (1-18). It has been estimated that
approximately 7% of all patients over 60 may harbor a benign growth (often of the
adrenal gland) and with the increase of "whole-body CT scanning" as part of health
screening programs, the chance of finding incidentalomas is expected to increase to 37%
(19). These chance findings will, in many cases, require further investigation.
A search of the dental literature did not reveal any studies that dealt with incidental
findings on 3D CT studies taken on cone beam scanners. Nor has the term
“incidentaloma” been applied to dentistry.
In this 3D CT cone beam study, 500 consecutive patients sent to one of nine i-dontics, llc
radiologic labs were analyzed for a variety of normal and abnormal findings. Part I
studied why patients were referred for CT studies including their age, gender, and format
of the requested study. Part II studied the lingual artery and its insertion into the
mandible. Part III studied the frequency and location of bifid canals. Part IV studied the
length and location of the anterior canal extending anterior to the mental foramen. And
in this study, Part V, the frequency and type of incidental findings on patients ostensibly
sent to a dental CT radiological lab for 3D scans for dental implants were analyzed.
Methods and Materials
Data from five hundred (500) consecutive patients sent for 3D CT cone beam studies to
one of 9 centers located in 3 states were evaluated. Scans were taken on either i-CAT (8
centers) or on a NewTom 3G scanner, and uploaded to a central data center. All studies
were converted to SimPlant™ (Materialise, Glen Burnie, MD.). When not specified, the
data was converted to SimPlant™ version 10.
In this part of the 3D study, the following parameters were recorded for each patient: if
the maxillary sinuses were free of pathology or to what extent pathology was present. In
addition, the following were noted: the presence of radiolucencies at the apices of teeth;
were the teeth noted with radiolucencies vital or non-vital; impacted teeth and
supernumeraries, retained roots, cysts, the presence of dental implants, and the
radiopaque presence of bone graft material. Other incidental findings noted on the 3D Ct
images included the notation of severe periodontal bone loss, fourth molars, condensing
osteitis, surgical tacks, etc.
Five hundred (500) patients were included in this study. Of the five hundred, two
hundred and four (204) were referred exclusively for maxillary studies and an additional
seventy-nine (79) (refer to Part I of this study), were referred for both maxillary and
mandibular studies. A total of two hundred and eighty-three maxillas studied (Figure 1)
for observations about the maxillary sinus. The CT scans for all 500 patients were
analyzed for incidental findings.
Figure 1. Of the 500 patients in this study, 279 had maxillary scans evaluated.
Ninety-one (91) patients had both maxillary sinuses free of pathology while ninety (90)
patients had pathology in both sinuses at the same time, as noted on the CT images.
Pathology was defined as less than 1mm of a mucosal thickening measured at any part of
the sinus visible in the CT scan. When pathology was present (1mm or greater of
mucosal thickening), one maxillary sinus remained clear or free of pathology in 78
patients: 41 in the right and 37 in the left.
When present, the amount of mucosal thickening was measured in each sinus. The
mucosal thickening in the right sinus averaged 5.3mm and it measured 5.6mm in the left
In addition, 26 patients had polyps in the right maxillary sinus and 22 patients had polyps
in the left maxillary sinus. Six maxillary sinuses were totally blocked both right and left
(Figure 2). Polyps were observed in some patients with mucous thickenings, so that the
total number of observations is greater than the 283 maxillary sinuses studied.
Figure 2. 91 of the 283 maxillary scans had no pathology in both the right and left maxillary sinuses. 90
patients had pathology noted in both maxillary sinuses and 78 patients had pathology in only one of the
maxillary sinuses. 48 patients had a polyp noted in either the right or left maxillary sinus, or both.
Reasons for dental 3D CT scans. The predominant reason for referral for dental CT
scans was for pre-surgical analysis for the insertion of dental implants. Four hundred
and fifty-one patients (451) were referred for implants; 20 for impacted teeth; 10 for
pathology; 7 for endodontics; 4 for orthodontics; 1 for TMJ disorder; 7 unknown (Figure
Figure 3. A = 451 Patients referred for CTs for implants; B = 20 patients for impacted teeth; C = 10
patients for pathology; D = 7 patients for endodontics; E = 4 patients for orthodontics; F = 1patient for
TMJ; G = 7 patients unknown reason for referral for CT.
Incidental findings. While 451 patients (out of 500) were referred for a 3D dental CT
scan for the express purpose of pre-surgical planning for implant insertion, many
incidental findings were noted. The most common incidental findings (Figure 4) were
periapical radiolucencies (229), socket preservation bone grafts (46), impacted teeth (27),
retained root tips (24), sinus grafts (12), cysts (8), and supernumerary teeth (2). In
addition, 70 dental implants were previously inserted in these patients. Other
observations (142) included cementomas, surgical screws and tacks, assorted opacities
within the body of either arch, 4th molars, blunted apices (due to orthodontics), blocked
ethmoid sinus, condensing osteitis, and advanced periodontal disease nearly to the apices
of many teeth.
Figure 4 The most common incidental findings were: 229 periapical radiolucencies; 46 socket
preservation bone grafts; 27 impacted teeth; 24 retained root tips; 12 sinus grafts; 8 cysts; 2 supernumerary
In the medical literature, the term “incidentaloma” refers to the discovery of a previously
unsuspected tumor when taking a CT scan for another purpose. This term has not entered
the dental literature. It is suggested that a dental “incidentaloma” be defined as the
discovery of any unsuspected pathology, anomaly, dental structure (such as a retained
root tip, impacted tooth, or supernumerary), or deviation from normal anatomy on a CT
scan. The implications of these findings challenge the dentist and dental surgeon to be
familiar with both normal and abnormal structures as they present on 3D cone scan
imaging, which can appear different and unfamiliar compared to traditional 2D X-ray
images such as periapical dental films or panoramic X-rays. Furthermore, it is
incumbent for the dentist to interpret the entire field of view of each CT scan, and not just
the area of concern, such as a dental implant site or a recalcitrant endodontic lesion or
where the IAN is relative to an impacted third molar.
The most frequent incidental finding in this study was periapical radiolucencies. Many
authors have acknowledged that 3D cone beam CT scans are extremely accurate and can
be relied on for making a diagnosis of periapical pathology (20-23). For purposes of this
study, periapical pathology was defined as a lesion expanding larger than 1mm from the
apex. This was chosen to remove doubt that a pseudoperiapical lesion was not a
thickened PDL due to trauma from occlusion. There was no attempt to obtain the
previous history of teeth with root canal therapy to compare the size of the present lesion
with past X-rays. No determination was made if a periapical lesion noted in this study
was old, non-expanding, or a healing granuloma.
This 3D CT study noted trends in therapy. For instance, 46 extraction sockets were
treated with graft material and the dental surgeon was interested in a 3D analysis of the
healing lesion. Likewise, patients who had previously had maxillary sinus grafts (12)
received 3D CT scans to determine the success of these surgeries.
Twenty-seven (27) teeth other than the ones patients who were originally referred for CT
scans, were impacted, and two supernumeraries were noted. These “incidental” findings
were sent in a report to each dentist for their review, final approval, and action when they
deemed it necessary.
It is apparent that with the advent of dental cone beam scanners, more dentists will take
advantage of 3D technology for better surgical planning, improved diagnostic preparation
for orthodontic patients, all of which contribute to lower risk and more successful
outcomes for the patients. While dentists embrace 3D technology, they need to become
familiar with normal and abnormal landmarks. In addition, they need to be prepared to
identify incidental findings and inform their patients as to the existence of these findings
and their clinical relevance.
This study noted many incidental findings on 3D dental CT scans and suggests that these
findings be described as “incidentalomas.” These unexpected findings include sinus
pathology, cysts, impacted teeth, supernumeraries, periapical radiolucencies, and more.
It is suggested that dentists become more familiar with normal and abnormal landmarks
in the increased field of view of CT studies, especially when these 3D images are taking
in preparation for dental implant treatment planning.
Acknowledgements: Support for this study was generously given by Nobel Biocare AB
Gothenberg, Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA.
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