Australian Dental Journal
The official journal of the Australian Dental Association
Australian Dental Journal 2015; 60: 426–433 doi: 10.1111/adj.12267
Odontogenic facial swelling of unknown origin S Ranjitkar,* W Cheung,* R Yong,* J Deverell,† M Packianathan,* C Hall† *School of Dentistry, The University of Adelaide, South Australia. †Mawson Institute, The University of South Australia, Mawson Lakes, South Australia.
ABSTRACT Background: Current radiography techniques have limitations in detecting subtle odontogenic anomalies or defects that can lead to dentoalveolar and facial infections. This report examines the application of micro-CT imaging on two extracted teeth to enable detailed visualization of subtle odontogenic defects that had given rise to facial swelling. Methods: Two extracted non-carious mandibular left primary canine teeth (73) associated with odontogenic infections were selected from two patients, and an intact contralateral tooth (83) from one of the patients was used as a control. All three teeth were subjected to three-dimensional micro-CT imaging at a resolution of 20 lm. Results: Tooth 73 from the first case displayed dentine pores (channels) that established communication between the pulp chamber and the exposed dentine surface. In comparison, tooth 73 from the second case had a major vertical crack extending from the external enamel surface into the pulp chamber. The control tooth did not display any anomalies or major cracks. Conclusions: The scope of micro-CT imaging can be extended from current in vitro applications to establish post-extraction diagnosis of subtle odontogenic defects, in a manner similar to deriving histopathological diagnoses in extracted teeth. Ongoing technological advancements hold the promise for more widespread translatory applications. Keywords: Apical periodontitis, cracked tooth, dental anomalies, facial swelling, micro-CT. Abbreviations and acronyms: CT = computed tomography; micro-CT = micro-computed tomography; nano-computed tomography. (Accepted for publication 7 December 2014.)
INTRODUCTION Dental abnormalities in the form of developmental defects (e.g. dens invaginatus and odontodysplasia) and acquired defects (e.g. dental caries, trauma and cracks) can provide pathways for bacterial entry into the root canal system, leading to pulpal inflammation and apical periodontitis. Failed clinical care from inadequate diagnosis and delayed management can progress into facial cellulitis1 and cause life-threatening complications (such as septicaemia, cavernous sinus thrombosis, airway obstruction and mediastinitis).2–5 Patients with acute facial cellulitis are often admitted to major hospitals as the last resort of treatment, resulting in considerable morbidity in terms of social and economic losses to individuals and society at large.1,6 Odontogenic infections comprise around 50.0% to 62.8% of facial cellulitis,2,7 with non-odontogenic causes contributing to the rest.7 While the nonodontogenic causes of dentoalveolar infections include infected fractures, lacerations, sebaceous cysts and folliculitis,7 the most common causes of odontogenic 426
infections are dental caries and trauma.8 Dental practitioners should be aware of these conditions as well as other uncommon or rare odontogenic causes of dental abscesses, including developmental abnormalities of the crown (e.g. dens invaginatus and dens evaginatus), structural abnormalities in dentine (e.g. dentine dysplasia, dentinogenesis imperfecta, rickets and regional odontodysplasia), and other acquired conditions (e.g. pre-eruptive intracoronal resorption of dentine and mandibular infected buccal cyst in primary teeth, as well as internal and external resorption in permanent teeth).9–12 The prevalence of facial cellulitis of ‘unknown’ origin has been reported to vary from 6.3% in adults to 49.7% in children,13 reflecting the potential difficulties when managing facial swellings in emergency situations.14 Even when the odontogenic origin of facial cellulitis has been determined, the precise nature of the odontogenic defects may remain elusive because of the limited resolutions of the current imaging modalities including plain two-dimensional (2D) radiography and three-dimensional (3D) computed © 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects tomography (CT). In this context, identification of odontogenic abnormalities has traditionally relied on histological investigations that involve sample destruction.9,11,15 Advents in CT imaging technology since the 1970s have resulted in numerous translatory clinical applications in the identification and management of congenital and acquired anomalies.16 The pioneering work in CT imaging of a cystic frontal lobe tumour in 1972 encouraged more research and development and wider acceptance of this technology in health care provision. More recent technological innovations have resulted in the development of high-resolution 3D microcomputed tomography (micro-CT) and nanocomputed tomography (nano-CT). These techniques are important laboratory research tools in dental phenomics research.17–19 Ongoing rapid technological advancements in highresolution CT technology have opened the opportunities to explore more relevant clinical applications. This report examines the application of micro-CT imaging to enable detailed visualization and to establish post-extraction diagnosis of subtle odontogenic defects that had given rise to facial swellings in two paediatric patients. The general applications of microCT imaging described here are not limited to paediatric cases as the general principles of tooth imaging apply to individuals of all ages.
palpation. Full clinical and radiographic examinations (including pulp sensibility and percussion tests as well as periapical radiographs) could not be completed due to lack of patient cooperation. There were noncavitated carious lesions in the mesio-occlusal regions of teeth 74 and 84. A CT image of the maxillofacial region obtained under intravenous contrast revealed a large periapical abscess around tooth 73, but there was no anomaly around the control tooth 83 (Fig. 1c). The diagnosis was odontogenic facial cellulitis associated with tooth 73, but the precise cause of the odontogenic infection was unknown. The emergency treatment consisted of surgical extraction and drainage under general anaesthetic with concurrent intravenous antibiotic administration (metronidazole 10 mg/kg 12 hourly and amoxicillin 15 mg/kg 6 hourly). The asymptomatic tooth 83 was also extracted to balance the occlusion.20 A culture of the purulent discharge revealed moderate mixed (normal) oral flora. A post-extraction periapical radiograph of tooth 73 showed a small coronal radiolucency, but without any apparent anomaly around the pulp chamber (Fig. 1d). At one-day postoperative review, facial swelling had subsided and the patient was discharged the same evening on oral metronidazole and amoxicillin. There was a complete resolution of the facial infection eight days postoperatively, and the patient was referred to a private paediatric practitioner for restorative and orthodontic care.
CASE REPORTS Case 2 Case 1 A 3-year-old boy presented for emergency care at a major hospital in March 2012 with a two-day history of progressive ‘swelling of the left cheek’. A private medical practitioner at another clinic had prescribed oral cephalexin the previous day. The medical history was unremarkable and there was no familial history of dental or craniofacial anomalies. The patient had reduced food intake and was non-compliant with oral cephalexin, but he was tolerating fluids. Clinical and orthopantomographic examinations conducted at the hospital did not detect any systemic or odontogenic infections. The patient was then referred to a paediatric dental facility for further management. There was no known history of dental trauma or tooth grinding. Extraoral examination revealed an extensive erythematous, tender and fluctuant swelling in the left buccal and submandibular regions. Intraorally, there was a soft tissue swelling in the lower left buccal sulcus, extending from the mesial surface of tooth 73 to the distal surface of tooth 75. Tooth 73 had yellowish, discoloured and notched enamel on the labial surface and exposed dentine on the lingual surface (Fig. 1a and 1b). It also displayed Grade I mobility and was tender to apical © 2015 Australian Dental Association
A 3-year-old boy presented to a private paediatric dentist in July 2013 with a six-day history of facial swelling and fever. A macrolide antibiotic (roxithromycin 50 mg twice daily for 10 days) had been prescribed by medical practitioners in another hospital six days earlier, but he re-presented to the same hospital four days later because of persistent infection. At the second appointment, the medical practitioners carried out a full blood count that revealed normal results. For the second time, the source of the infection could not be determined and he was discharged with a different antibiotic (clindamycin 75 mg three times daily for 7 days). On the sixth day since the infection began, the parents noted an intraoral abscess that prompted them to appoint the child with a paediatric dentist. At the paediatric clinic, the child was upset, restless and lethargic but did not have any fever. Extraoral examination revealed a noticeable swelling (4 cm long 9 3 cm wide) in the buccal and submandibular regions, and intraoral examination revealed a noticeable swelling extending from the mesial surface of tooth 72 to the mesial surface of tooth 74. Tooth 73 had Grade III mobility and was very tender to apical palpation. The buccal and lingual coronal surfaces 427
S Ranjitkar et al. (a)
(c)
(b)
(d)
Fig. 1 Clinical appearance of tooth 73 in Case 1. (a) A post-extraction photograph, obtained under a stereomicroscope under optimum lighting and magnification, showing the labial enamel notch (defect) with an underlying yellowish appearance (dotted white arrow). (b) A post-extraction photograph showing the lingual stained, exposed dentine surface (two dotted white arrows). (c) A multidetector medical computed tomography of the maxillofacial region (image thickness, i.e. z-axis spatial resolution = 0.625 mm) in frontal view, displaying a periapical abscess around tooth 73 (solid white arrow). (d) A post-extraction periapical radiograph taken in the same plane as image (b) featuring a small coronal radiolucency but without any noticeable defect around the pulp chamber.
of tooth 73 displayed craze lines (as shown in post-extraction images in Fig. 2a and 2b), and there was an incisal wear facet consistent with the history of occasional ‘very loud’ tooth grinding. However, there was no other plausible explanation for the odontogenic infection. Orthopantomogram and periapical radiographs could not be taken because of poor patient cooperation. A periapical radiograph of tooth 73 was taken under general anaesthetic at a local private hospital, and it revealed an extensive periapical radiolucency tracking along its mesial root surface (Fig. 2c). The tooth was extracted immediately with forceps using minimal forces under the general anaesthetic and the patient was advised to complete the remaining course of clindamycin (for the remaining five days). The facial infection resolved completely one week later and the socket healed uneventfully in four weeks. Micro-CT imaging Both teeth 73 (n = 2) associated with facial cellulitis were subjected to micro-CT analysis, while the 428
asymptomatic tooth 83 from Case 1 was used as a control. The teeth were sealed in plastic vials using compressed foam that had been soaked with water to prevent dehydration. Tomograms were obtained by using the Xradia (Pleasanton, CA, USA) MicroXCT400 high-resolution cone beam x-ray imaging system (FEI, Visualization Sciences Group, Burlington, USA). Each tooth was scanned in four vertical sections using 1801 projections with an exposure time of 45 s at binning 2 and source energy of 55 kV /10 W. For 3D reconstruction, the four sections were stitched into a single tomogram using proprietary Xradia software. The data were then processed using VSG Avizo Fire 7.0 (FEI, Visualization Sciences Group, Burlington, USA) with a non-local means smoothing filter before they were subjected to 2D Histogram segmentation, tophat, thresholding and manual correction. Longitudinal micro-CT sections of the teeth were generated automatically using the Aviso Fire 7.0 from volumetric cross-sectional data. In addition, surface (*.stl) files from Case 1 were reduced to 10% of their initial number of faces from each segmented label field © 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects (a)
(b)
(c)
Fig. 2 Clinical appearance of tooth 73 in Case 2. (a) A post-extraction photograph of the craze line (solid white arrow) from the labial view obtained under a stereomicroscope under optimum lighting and magnification. (b) A post-extraction photograph of the same craze line (solid white arrow) from the lingual view obtained under a stereomicroscope under optimum lighting and magnification. (c) A preoperative periapical radiograph of a radiolucency tracking along its mesial radicular surface (dotted white arrow).
before being exported to Adobe 3D Reviewer (Adobe Systems Inc., California, USA) to generate embedded 3D models. Dental caries or resorption was not observed in the micro-CT images of any tooth. The dentine-pulp complex of tooth 73 in Case 1 was anomalous, with numerous pores (channels) (around 2.2 lm long 9 14 to 90 lm wide) extending from the exposed dentine surface into the finger-like projections of the pulp chamber (Fig. 3). In Case 2, tooth 73 had a vertical crack (around 40 lm wide) extending from the external enamel surface into the pulp chamber (Fig. 4). Figure 5 shows the micro-CT images of the control tooth 83 with three minor cracks confined to enamel, © 2015 Australian Dental Association
but there were no structural anomalies (as observed in Fig. 3) or major cracks (as observed in Fig. 4). DISCUSSION These two cases fall into a wide spectrum of enigmatic clinical presentations of odontogenic facial swellings that can cause diagnostic dilemma and delayed management. While micro-CT was not essential for the clinical management of the cases described, it enabled establishment of post-extraction diagnosis of subtle odontogenic defects beyond speculation. The approach used in the present report is similar to the standard method of deriving definitive 429
S Ranjitkar et al. (a)
(b)
(c)
(d)
(e)
Fig. 3 Micro-computed tomography (micro-CT) images of tooth 73 in Case 1. (a) A lingual longitudinal section showing the external enamel surface (whitish layer) and the exposed dentine surface (solid black arrow). (b) The same longitudinal section from (a) after removing the enamel cap and adding the pulp chamber. The dotted black arrow points to the dentine pores (channels). (c) A distal longitudinal section of the same image from (b), with the dotted black arrow pointing to the dentine pores (channels). (d) A superior transverse section of the dentine pores (channels) at the distolingual part of the crown, with the central thick pore representing the pulp horn. The labial defect noted in Fig. 1a appears as a notch in the enamel, and the dentine pores (channels) noted in Fig. 1b appear as numerous open tubules in the distolingual part of the crown. (e) A mesial longitudinal section showing dentine pores (channels) extending from the exposed dentine into the pulp chamber. Abbreviations: La = labial; Li = lingual; Me = mesial; Di = distal. Length of each unit of measurement in (d) = 1.0 mm and in (e) = 2.5 mm.
(b) (a)
Fig. 4 Micro-computed tomography (micro-CT) images of tooth 73 in Case 2 showing a crack (white arrow) running from the external enamel surface into the pulp chamber in (a) superior transverse section and in (b) a lingual longitudinal section. Abbreviations: La = labial; Li = lingual; Me = mesial; De = distal. Length of each unit of measurement in (a) = 1.0 mm and in (b) = 2.5 mm. 430
© 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects
(b) (a)
Fig. 5 Micro-computed tomography (micro-CT) images of the control tooth 83 in Case 1 in (a) a superior transverse section and (b) a distal longitudinal section. This tooth shows three minor cracks confined to enamel, as shown in the three insets in (a), indicating that these features occur commonly in healthy teeth. However, this tooth did not display any anomaly (as observed in Figs. 3d and 3e) or a major crack (as observed in Figs. 4a and 4b). Abbreviations: La = labial; Li = lingual; Me = mesial; De = distal. Length of each unit of measurement in (a) = 1.0 mm and in (b) = 2.5 mm.
diagnoses of hard tissue conditions from histopathological examinations of extracted teeth.21 Clearly, more work is needed to explore the logistic issues (such as accuracy, reliability and efficiency) before micro-CT imaging can be considered routinely in contemporary clinical practice. Growing concerns of litigation arising from misdiagnosis of microcracks and fractures also warrant better diagnostic aids, using high-resolution 3D imaging.22 In relation to the findings of delayed management of both cases in medical practices, there is a need for better collaboration between medical and dental professionals as well as better training of medical practitioners in aspects of dental diseases.23,24 Published guidelines for emergency physicians have highlighted the need to avoid pitfalls of managing odontogenic infections by antibiotic therapy alone, without addressing the primary cause.25 In Case 1, dentine pores (channels) that were probably associated with either missing or worn hypoplastic enamel (on the lingual surface) would have provided pathways for bacterial ingress into the pulp tissue, resulting in facial cellulitis (Fig. 3). The prevalences of localized enamel hypoplasia of the labial surfaces of primary canine teeth vary from around 1% to 41%,26,27 but the prevalence of lingual enamel hypoplasia and its association with odontogenic infection need further investigation. The dentine defects observed in both our cases did not resemble any anomalies that have been described in unusual cases of dental abscesses.9–11 Although the dentine pores in our first case have some structural resemblance with dentine clefts in familial hypophosphataemic rickets,9 our patient did not suffer from that condition. Further stud© 2015 Australian Dental Association
ies are recommended to conduct a more detailed investigation of the nature and frequencies of enamel and dentine defects associated with odontogenic infections. In Case 2, heavy occlusal loading from tooth grinding is a plausible explanation for the initiation and propagation of the longitudinal microcrack (Fig. 4). Given the limitation of the current micro-CT systems in establishing prospective diagnosis, the role of forceps in crack development cannot be ruled out. However, forces exerted by the extraction forceps are unlikely to have caused the vertical crack, as only minimal forces were required to remove the tooth 73 (with Grade III mobility). Furthermore, the two other teeth extracted using the forceps in this study did not display a major crack. Smaller microcracks occur commonly in healthy teeth as observed in the present study (Fig. 5) and in a previous study.28 They are non-problematic unless they coalesce and propagate under the occlusal loading (stress) to establish the communication between the oral environment and the pulp chamber. Crack detection using currently available clinical tests and imaging modalities is challenging, although the emerging applications of cone beam CT are now being realized.29 Lower voxel resolution of cone beam CT (76–600 lm)30 relative to the width of the major crack observed in our second case (40 lm wide) still emphasizes the need for better imaging modality for fractographic analysis of teeth. Indeed, a previous observation of improved diagnostic accuracy of vertical root fractures from 59.5% to 100.0% with the corresponding increases in the voxel resolution from 80 lm to 9 lm31 implies that micro-CT technology has the potential to inspire more widespread transla431
S Ranjitkar et al. tory applications. Current chairside clinical applications of micro-CT imaging are limited by prolonged operation time, and high cost and high radiation dose. However, continued interdisciplinary research involving X-ray optics, structural biology, medical engineering and clinical practice holds the promise to overcome these problems.16,19,32 CONCLUSIONS Microscopic pores (channels) and cracks may provide pathways for bacterial ingress into the pulp chamber, resulting in apical periodontitis that can eventually lead to facial cellulitis. At present, high-resolution micro-CT imaging can assist in establishing postextraction diagnosis of dental anomalies or defects that is not possible with other clinical tools. This new application of micro-CT imaging holds the promise for broader translatory applications, particularly in improving endodontic diagnostics. ACKNOWLEDGEMENTS This project was supported by the Australian Dental Research Foundation Inc. (ADRF). The micro-CT work was performed at the South Australian node of the Australian National Fabrication Facility under the National Collaborative Research Infrastructure Strategy to provide nano and microfabrication facilities for Australia’s researchers. We would also like to acknowledge the facilities and assistance provided by Adelaide Microscopy to conduct aspects of image analysis, and the assistance provided by Dr Ben Wade with tooth imaging. The authors have no conflicts of interest to declare. REFERENCES
7. Wang J, Ahani A, Pogrel MA. A five-year retrospective study of odontogenic maxillofacial infections in a large urban public hospital. Int J Oral Maxillofac Surg 2005;34:646–649. 8. Wong NH, Tran C, Pukallus M, Holcombe T, Seow WK. A three-year retrospective study of emergency visits at an oral health clinic in south-east Queensland. Aust Dent J 2012;57:132– 137. 9. Seow WK. Diagnosis and management of unusual dental abscesses in children. Aust Dent J 2003;48:156–168. 10. Seow WK. Developmental defects of enamel and dentine: challenges for basic science research and clinical management. Aust Dent J 2014;59(Suppl 1):143–154. 11. Tervonen SA, Stratmann U, Mokrys K, Reichart PA. Regional odontodysplasia: a review of the literature and report of four cases. Clin Oral Investig 2004;8:45–51. 12. Heithersay GS. Management of tooth resorption. Aust Dent J 2007;52(Suppl 1):S105–S121. 13. Scutari P Jr, Dodson TB. Epidemiologic review of pediatric and adult maxillofacial infections in hospitalized patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;81:270– 274. 14. Hong L, Ahmed A, McCunniff M, Liu Y, Cai J, Hoff G. Secular trends in hospital emergency department visits for dental care in Kansas City, Missouri, 2001–2006. Public Health Rep 2011;126:210–219. 15. Kulild JC, Peters DD. Incidence and configuration of canal systems in the mesiobuccal root of maxillary first and second molars. J Endod 1990;16:311–317. 16. Morris P, Perkins A. Diagnostic imaging. Lancet 2012;379: 1525–1533. 17. Yong R, Ranjitkar S, Townsend G, et al. Dental phenomics: advancing genotype to phenotype correlations in craniofacial research. Aust Dent J 2014;59(Suppl 1):34–47. 18. Townsend GC, Brook AH. The face, the future, and dental practice: how research in craniofacial biology will influence patient care. Aust Dent J 2014;59(Suppl 1):1–5. 19. Anderson P, Yong R, Surman T, Rajion Z, Ranjitkar S. Application of three-dimensional computed tomography in craniofacial clinical practice and research. Aust Dent J 2014;59 (Suppl 1):174–185. 20. Ball IA. Balancing the extraction of primary teeth: a review. Int J Paediatr Dent 1993;3:179–185. 21. Zhou J, Zhao YF, Xia CY, Jiang L. Periodontitis with hypercementosis: report of a case and discussion of possible aetiological factors. Aust Dent J 2012;57:511–514.
1. Tran C, Gussy M, Kilpatrick N. Pathways to emergency dental care: an exploratory study. Eur Arch Paediatr Dent 2010;11: 97–100.
22. Rosen E, Tsesis I, Tamse A, Bjorndal L, Taschieri S, Givol N. Medico-legal aspects of vertical root fractures in root filled teeth. Int Endod J 2012;45:7–11.
2. Unkel JH, McKibben DH, Fenton SJ, Nazif MM, Moursi A, Schuit K. Comparison of odontogenic and nonodontogenic facial cellulitis in a pediatric hospital population. Pediatr Dent 1997;19:476–479.
23. Caspary G, Krol DM, Boulter S, Keels MA, Romano-Clarke G. Perceptions of oral health training and attitudes toward performing oral health screenings among graduating pediatric residents. Pediatrics 2008;122:e465–e471.
3. Marioni G, Rinaldi R, Staffieri C, et al. Deep neck infection with dental origin: analysis of 85 consecutive cases (2000– 2006). Acta Otolaryngol 2008;128:201–206.
24. Lewis CW, Boulter S, Keels MA, et al. Oral health and pediatricians: results of a national survey. Acta Pediatr 2009;9:457– 461.
4. Dalla Torre D, Burtscher D, Hofer D, Kloss FR. Odontogenic deep neck space infection as life-threatening condition in pregnancy. Aust Dent J 2014;59:375–378.
25. Hodgdon A. Dental and related infections. Emerg Med Clin North Am 2013;31:465–480.
5. Celakovsky P, Kalfert D, Smatanova K, et al. Bacteriology of deep neck infections: analysis of 634 patients. Aust Dent J 2015;60:212–215. 6. Kim MK, Allareddy V, Nalliah RP, Kim JE, Allareddy V. Burden of facial cellulitis: estimates from the Nationwide Emergency Department Sample. Oral Surg Oral Med Oral Pathol Oral Radiol 2012;114:312–317.
432
26. Skinner MF, Hung JTW. Localized enamel hypoplasia of the primary canine. ASDC J Dent Child 1986;53:197–200. 27. Needleman HL, Leviton A, Allred E. Macroscopic enamel defects of primary anterior teeth – types, prevalence, and distribution. Pediatr Dent 1991;13:208–216. 28. De-Deus G, Silva EJ, Marins J, et al. Lack of causal relationship between dentinal microcracks and root canal preparation with reciprocation systems. J Endod 2014;40:1447–1450. © 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects 29. Metska ME, Aartman IH, Wesselink PR, Ozok AR. Detection of vertical root fractures in vivo in endodontically treated teeth by cone-beam computed tomography scans. J Endod 2012;38: 1344–1347.
32. Kalender WA. X-ray computed tomography. Phys Med Biol 2006;51:R29–R43.
30. Scarfe WC, Li Z, Aboelmaaty W, Scott SA, Farman AG. Maxillofacial cone beam computed tomography: essence, elements and steps to interpretation. Aust Dent J 2012;57(Suppl 1):46–60.
Address for correspondence: Dr Sarbin Ranjitkar School of Dentistry The University of Adelaide Adelaide SA 5005 Email: [email protected]
31. Huang CC, Chang YC, Chuang MC, et al. Analysis of the width of vertical root fracture in endodontically treated teeth by 2 micro-computed tomography systems. J Endod 2014;40: 698–702.
© 2015 Australian Dental Association
433
The official journal of the Australian Dental Association
Australian Dental Journal 2015; 60: 426–433 doi: 10.1111/adj.12267
Odontogenic facial swelling of unknown origin S Ranjitkar,* W Cheung,* R Yong,* J Deverell,† M Packianathan,* C Hall† *School of Dentistry, The University of Adelaide, South Australia. †Mawson Institute, The University of South Australia, Mawson Lakes, South Australia.
ABSTRACT Background: Current radiography techniques have limitations in detecting subtle odontogenic anomalies or defects that can lead to dentoalveolar and facial infections. This report examines the application of micro-CT imaging on two extracted teeth to enable detailed visualization of subtle odontogenic defects that had given rise to facial swelling. Methods: Two extracted non-carious mandibular left primary canine teeth (73) associated with odontogenic infections were selected from two patients, and an intact contralateral tooth (83) from one of the patients was used as a control. All three teeth were subjected to three-dimensional micro-CT imaging at a resolution of 20 lm. Results: Tooth 73 from the first case displayed dentine pores (channels) that established communication between the pulp chamber and the exposed dentine surface. In comparison, tooth 73 from the second case had a major vertical crack extending from the external enamel surface into the pulp chamber. The control tooth did not display any anomalies or major cracks. Conclusions: The scope of micro-CT imaging can be extended from current in vitro applications to establish post-extraction diagnosis of subtle odontogenic defects, in a manner similar to deriving histopathological diagnoses in extracted teeth. Ongoing technological advancements hold the promise for more widespread translatory applications. Keywords: Apical periodontitis, cracked tooth, dental anomalies, facial swelling, micro-CT. Abbreviations and acronyms: CT = computed tomography; micro-CT = micro-computed tomography; nano-computed tomography. (Accepted for publication 7 December 2014.)
INTRODUCTION Dental abnormalities in the form of developmental defects (e.g. dens invaginatus and odontodysplasia) and acquired defects (e.g. dental caries, trauma and cracks) can provide pathways for bacterial entry into the root canal system, leading to pulpal inflammation and apical periodontitis. Failed clinical care from inadequate diagnosis and delayed management can progress into facial cellulitis1 and cause life-threatening complications (such as septicaemia, cavernous sinus thrombosis, airway obstruction and mediastinitis).2–5 Patients with acute facial cellulitis are often admitted to major hospitals as the last resort of treatment, resulting in considerable morbidity in terms of social and economic losses to individuals and society at large.1,6 Odontogenic infections comprise around 50.0% to 62.8% of facial cellulitis,2,7 with non-odontogenic causes contributing to the rest.7 While the nonodontogenic causes of dentoalveolar infections include infected fractures, lacerations, sebaceous cysts and folliculitis,7 the most common causes of odontogenic 426
infections are dental caries and trauma.8 Dental practitioners should be aware of these conditions as well as other uncommon or rare odontogenic causes of dental abscesses, including developmental abnormalities of the crown (e.g. dens invaginatus and dens evaginatus), structural abnormalities in dentine (e.g. dentine dysplasia, dentinogenesis imperfecta, rickets and regional odontodysplasia), and other acquired conditions (e.g. pre-eruptive intracoronal resorption of dentine and mandibular infected buccal cyst in primary teeth, as well as internal and external resorption in permanent teeth).9–12 The prevalence of facial cellulitis of ‘unknown’ origin has been reported to vary from 6.3% in adults to 49.7% in children,13 reflecting the potential difficulties when managing facial swellings in emergency situations.14 Even when the odontogenic origin of facial cellulitis has been determined, the precise nature of the odontogenic defects may remain elusive because of the limited resolutions of the current imaging modalities including plain two-dimensional (2D) radiography and three-dimensional (3D) computed © 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects tomography (CT). In this context, identification of odontogenic abnormalities has traditionally relied on histological investigations that involve sample destruction.9,11,15 Advents in CT imaging technology since the 1970s have resulted in numerous translatory clinical applications in the identification and management of congenital and acquired anomalies.16 The pioneering work in CT imaging of a cystic frontal lobe tumour in 1972 encouraged more research and development and wider acceptance of this technology in health care provision. More recent technological innovations have resulted in the development of high-resolution 3D microcomputed tomography (micro-CT) and nanocomputed tomography (nano-CT). These techniques are important laboratory research tools in dental phenomics research.17–19 Ongoing rapid technological advancements in highresolution CT technology have opened the opportunities to explore more relevant clinical applications. This report examines the application of micro-CT imaging to enable detailed visualization and to establish post-extraction diagnosis of subtle odontogenic defects that had given rise to facial swellings in two paediatric patients. The general applications of microCT imaging described here are not limited to paediatric cases as the general principles of tooth imaging apply to individuals of all ages.
palpation. Full clinical and radiographic examinations (including pulp sensibility and percussion tests as well as periapical radiographs) could not be completed due to lack of patient cooperation. There were noncavitated carious lesions in the mesio-occlusal regions of teeth 74 and 84. A CT image of the maxillofacial region obtained under intravenous contrast revealed a large periapical abscess around tooth 73, but there was no anomaly around the control tooth 83 (Fig. 1c). The diagnosis was odontogenic facial cellulitis associated with tooth 73, but the precise cause of the odontogenic infection was unknown. The emergency treatment consisted of surgical extraction and drainage under general anaesthetic with concurrent intravenous antibiotic administration (metronidazole 10 mg/kg 12 hourly and amoxicillin 15 mg/kg 6 hourly). The asymptomatic tooth 83 was also extracted to balance the occlusion.20 A culture of the purulent discharge revealed moderate mixed (normal) oral flora. A post-extraction periapical radiograph of tooth 73 showed a small coronal radiolucency, but without any apparent anomaly around the pulp chamber (Fig. 1d). At one-day postoperative review, facial swelling had subsided and the patient was discharged the same evening on oral metronidazole and amoxicillin. There was a complete resolution of the facial infection eight days postoperatively, and the patient was referred to a private paediatric practitioner for restorative and orthodontic care.
CASE REPORTS Case 2 Case 1 A 3-year-old boy presented for emergency care at a major hospital in March 2012 with a two-day history of progressive ‘swelling of the left cheek’. A private medical practitioner at another clinic had prescribed oral cephalexin the previous day. The medical history was unremarkable and there was no familial history of dental or craniofacial anomalies. The patient had reduced food intake and was non-compliant with oral cephalexin, but he was tolerating fluids. Clinical and orthopantomographic examinations conducted at the hospital did not detect any systemic or odontogenic infections. The patient was then referred to a paediatric dental facility for further management. There was no known history of dental trauma or tooth grinding. Extraoral examination revealed an extensive erythematous, tender and fluctuant swelling in the left buccal and submandibular regions. Intraorally, there was a soft tissue swelling in the lower left buccal sulcus, extending from the mesial surface of tooth 73 to the distal surface of tooth 75. Tooth 73 had yellowish, discoloured and notched enamel on the labial surface and exposed dentine on the lingual surface (Fig. 1a and 1b). It also displayed Grade I mobility and was tender to apical © 2015 Australian Dental Association
A 3-year-old boy presented to a private paediatric dentist in July 2013 with a six-day history of facial swelling and fever. A macrolide antibiotic (roxithromycin 50 mg twice daily for 10 days) had been prescribed by medical practitioners in another hospital six days earlier, but he re-presented to the same hospital four days later because of persistent infection. At the second appointment, the medical practitioners carried out a full blood count that revealed normal results. For the second time, the source of the infection could not be determined and he was discharged with a different antibiotic (clindamycin 75 mg three times daily for 7 days). On the sixth day since the infection began, the parents noted an intraoral abscess that prompted them to appoint the child with a paediatric dentist. At the paediatric clinic, the child was upset, restless and lethargic but did not have any fever. Extraoral examination revealed a noticeable swelling (4 cm long 9 3 cm wide) in the buccal and submandibular regions, and intraoral examination revealed a noticeable swelling extending from the mesial surface of tooth 72 to the mesial surface of tooth 74. Tooth 73 had Grade III mobility and was very tender to apical palpation. The buccal and lingual coronal surfaces 427
S Ranjitkar et al. (a)
(c)
(b)
(d)
Fig. 1 Clinical appearance of tooth 73 in Case 1. (a) A post-extraction photograph, obtained under a stereomicroscope under optimum lighting and magnification, showing the labial enamel notch (defect) with an underlying yellowish appearance (dotted white arrow). (b) A post-extraction photograph showing the lingual stained, exposed dentine surface (two dotted white arrows). (c) A multidetector medical computed tomography of the maxillofacial region (image thickness, i.e. z-axis spatial resolution = 0.625 mm) in frontal view, displaying a periapical abscess around tooth 73 (solid white arrow). (d) A post-extraction periapical radiograph taken in the same plane as image (b) featuring a small coronal radiolucency but without any noticeable defect around the pulp chamber.
of tooth 73 displayed craze lines (as shown in post-extraction images in Fig. 2a and 2b), and there was an incisal wear facet consistent with the history of occasional ‘very loud’ tooth grinding. However, there was no other plausible explanation for the odontogenic infection. Orthopantomogram and periapical radiographs could not be taken because of poor patient cooperation. A periapical radiograph of tooth 73 was taken under general anaesthetic at a local private hospital, and it revealed an extensive periapical radiolucency tracking along its mesial root surface (Fig. 2c). The tooth was extracted immediately with forceps using minimal forces under the general anaesthetic and the patient was advised to complete the remaining course of clindamycin (for the remaining five days). The facial infection resolved completely one week later and the socket healed uneventfully in four weeks. Micro-CT imaging Both teeth 73 (n = 2) associated with facial cellulitis were subjected to micro-CT analysis, while the 428
asymptomatic tooth 83 from Case 1 was used as a control. The teeth were sealed in plastic vials using compressed foam that had been soaked with water to prevent dehydration. Tomograms were obtained by using the Xradia (Pleasanton, CA, USA) MicroXCT400 high-resolution cone beam x-ray imaging system (FEI, Visualization Sciences Group, Burlington, USA). Each tooth was scanned in four vertical sections using 1801 projections with an exposure time of 45 s at binning 2 and source energy of 55 kV /10 W. For 3D reconstruction, the four sections were stitched into a single tomogram using proprietary Xradia software. The data were then processed using VSG Avizo Fire 7.0 (FEI, Visualization Sciences Group, Burlington, USA) with a non-local means smoothing filter before they were subjected to 2D Histogram segmentation, tophat, thresholding and manual correction. Longitudinal micro-CT sections of the teeth were generated automatically using the Aviso Fire 7.0 from volumetric cross-sectional data. In addition, surface (*.stl) files from Case 1 were reduced to 10% of their initial number of faces from each segmented label field © 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects (a)
(b)
(c)
Fig. 2 Clinical appearance of tooth 73 in Case 2. (a) A post-extraction photograph of the craze line (solid white arrow) from the labial view obtained under a stereomicroscope under optimum lighting and magnification. (b) A post-extraction photograph of the same craze line (solid white arrow) from the lingual view obtained under a stereomicroscope under optimum lighting and magnification. (c) A preoperative periapical radiograph of a radiolucency tracking along its mesial radicular surface (dotted white arrow).
before being exported to Adobe 3D Reviewer (Adobe Systems Inc., California, USA) to generate embedded 3D models. Dental caries or resorption was not observed in the micro-CT images of any tooth. The dentine-pulp complex of tooth 73 in Case 1 was anomalous, with numerous pores (channels) (around 2.2 lm long 9 14 to 90 lm wide) extending from the exposed dentine surface into the finger-like projections of the pulp chamber (Fig. 3). In Case 2, tooth 73 had a vertical crack (around 40 lm wide) extending from the external enamel surface into the pulp chamber (Fig. 4). Figure 5 shows the micro-CT images of the control tooth 83 with three minor cracks confined to enamel, © 2015 Australian Dental Association
but there were no structural anomalies (as observed in Fig. 3) or major cracks (as observed in Fig. 4). DISCUSSION These two cases fall into a wide spectrum of enigmatic clinical presentations of odontogenic facial swellings that can cause diagnostic dilemma and delayed management. While micro-CT was not essential for the clinical management of the cases described, it enabled establishment of post-extraction diagnosis of subtle odontogenic defects beyond speculation. The approach used in the present report is similar to the standard method of deriving definitive 429
S Ranjitkar et al. (a)
(b)
(c)
(d)
(e)
Fig. 3 Micro-computed tomography (micro-CT) images of tooth 73 in Case 1. (a) A lingual longitudinal section showing the external enamel surface (whitish layer) and the exposed dentine surface (solid black arrow). (b) The same longitudinal section from (a) after removing the enamel cap and adding the pulp chamber. The dotted black arrow points to the dentine pores (channels). (c) A distal longitudinal section of the same image from (b), with the dotted black arrow pointing to the dentine pores (channels). (d) A superior transverse section of the dentine pores (channels) at the distolingual part of the crown, with the central thick pore representing the pulp horn. The labial defect noted in Fig. 1a appears as a notch in the enamel, and the dentine pores (channels) noted in Fig. 1b appear as numerous open tubules in the distolingual part of the crown. (e) A mesial longitudinal section showing dentine pores (channels) extending from the exposed dentine into the pulp chamber. Abbreviations: La = labial; Li = lingual; Me = mesial; Di = distal. Length of each unit of measurement in (d) = 1.0 mm and in (e) = 2.5 mm.
(b) (a)
Fig. 4 Micro-computed tomography (micro-CT) images of tooth 73 in Case 2 showing a crack (white arrow) running from the external enamel surface into the pulp chamber in (a) superior transverse section and in (b) a lingual longitudinal section. Abbreviations: La = labial; Li = lingual; Me = mesial; De = distal. Length of each unit of measurement in (a) = 1.0 mm and in (b) = 2.5 mm. 430
© 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects
(b) (a)
Fig. 5 Micro-computed tomography (micro-CT) images of the control tooth 83 in Case 1 in (a) a superior transverse section and (b) a distal longitudinal section. This tooth shows three minor cracks confined to enamel, as shown in the three insets in (a), indicating that these features occur commonly in healthy teeth. However, this tooth did not display any anomaly (as observed in Figs. 3d and 3e) or a major crack (as observed in Figs. 4a and 4b). Abbreviations: La = labial; Li = lingual; Me = mesial; De = distal. Length of each unit of measurement in (a) = 1.0 mm and in (b) = 2.5 mm.
diagnoses of hard tissue conditions from histopathological examinations of extracted teeth.21 Clearly, more work is needed to explore the logistic issues (such as accuracy, reliability and efficiency) before micro-CT imaging can be considered routinely in contemporary clinical practice. Growing concerns of litigation arising from misdiagnosis of microcracks and fractures also warrant better diagnostic aids, using high-resolution 3D imaging.22 In relation to the findings of delayed management of both cases in medical practices, there is a need for better collaboration between medical and dental professionals as well as better training of medical practitioners in aspects of dental diseases.23,24 Published guidelines for emergency physicians have highlighted the need to avoid pitfalls of managing odontogenic infections by antibiotic therapy alone, without addressing the primary cause.25 In Case 1, dentine pores (channels) that were probably associated with either missing or worn hypoplastic enamel (on the lingual surface) would have provided pathways for bacterial ingress into the pulp tissue, resulting in facial cellulitis (Fig. 3). The prevalences of localized enamel hypoplasia of the labial surfaces of primary canine teeth vary from around 1% to 41%,26,27 but the prevalence of lingual enamel hypoplasia and its association with odontogenic infection need further investigation. The dentine defects observed in both our cases did not resemble any anomalies that have been described in unusual cases of dental abscesses.9–11 Although the dentine pores in our first case have some structural resemblance with dentine clefts in familial hypophosphataemic rickets,9 our patient did not suffer from that condition. Further stud© 2015 Australian Dental Association
ies are recommended to conduct a more detailed investigation of the nature and frequencies of enamel and dentine defects associated with odontogenic infections. In Case 2, heavy occlusal loading from tooth grinding is a plausible explanation for the initiation and propagation of the longitudinal microcrack (Fig. 4). Given the limitation of the current micro-CT systems in establishing prospective diagnosis, the role of forceps in crack development cannot be ruled out. However, forces exerted by the extraction forceps are unlikely to have caused the vertical crack, as only minimal forces were required to remove the tooth 73 (with Grade III mobility). Furthermore, the two other teeth extracted using the forceps in this study did not display a major crack. Smaller microcracks occur commonly in healthy teeth as observed in the present study (Fig. 5) and in a previous study.28 They are non-problematic unless they coalesce and propagate under the occlusal loading (stress) to establish the communication between the oral environment and the pulp chamber. Crack detection using currently available clinical tests and imaging modalities is challenging, although the emerging applications of cone beam CT are now being realized.29 Lower voxel resolution of cone beam CT (76–600 lm)30 relative to the width of the major crack observed in our second case (40 lm wide) still emphasizes the need for better imaging modality for fractographic analysis of teeth. Indeed, a previous observation of improved diagnostic accuracy of vertical root fractures from 59.5% to 100.0% with the corresponding increases in the voxel resolution from 80 lm to 9 lm31 implies that micro-CT technology has the potential to inspire more widespread transla431
S Ranjitkar et al. tory applications. Current chairside clinical applications of micro-CT imaging are limited by prolonged operation time, and high cost and high radiation dose. However, continued interdisciplinary research involving X-ray optics, structural biology, medical engineering and clinical practice holds the promise to overcome these problems.16,19,32 CONCLUSIONS Microscopic pores (channels) and cracks may provide pathways for bacterial ingress into the pulp chamber, resulting in apical periodontitis that can eventually lead to facial cellulitis. At present, high-resolution micro-CT imaging can assist in establishing postextraction diagnosis of dental anomalies or defects that is not possible with other clinical tools. This new application of micro-CT imaging holds the promise for broader translatory applications, particularly in improving endodontic diagnostics. ACKNOWLEDGEMENTS This project was supported by the Australian Dental Research Foundation Inc. (ADRF). The micro-CT work was performed at the South Australian node of the Australian National Fabrication Facility under the National Collaborative Research Infrastructure Strategy to provide nano and microfabrication facilities for Australia’s researchers. We would also like to acknowledge the facilities and assistance provided by Adelaide Microscopy to conduct aspects of image analysis, and the assistance provided by Dr Ben Wade with tooth imaging. The authors have no conflicts of interest to declare. REFERENCES
7. Wang J, Ahani A, Pogrel MA. A five-year retrospective study of odontogenic maxillofacial infections in a large urban public hospital. Int J Oral Maxillofac Surg 2005;34:646–649. 8. Wong NH, Tran C, Pukallus M, Holcombe T, Seow WK. A three-year retrospective study of emergency visits at an oral health clinic in south-east Queensland. Aust Dent J 2012;57:132– 137. 9. Seow WK. Diagnosis and management of unusual dental abscesses in children. Aust Dent J 2003;48:156–168. 10. Seow WK. Developmental defects of enamel and dentine: challenges for basic science research and clinical management. Aust Dent J 2014;59(Suppl 1):143–154. 11. Tervonen SA, Stratmann U, Mokrys K, Reichart PA. Regional odontodysplasia: a review of the literature and report of four cases. Clin Oral Investig 2004;8:45–51. 12. Heithersay GS. Management of tooth resorption. Aust Dent J 2007;52(Suppl 1):S105–S121. 13. Scutari P Jr, Dodson TB. Epidemiologic review of pediatric and adult maxillofacial infections in hospitalized patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;81:270– 274. 14. Hong L, Ahmed A, McCunniff M, Liu Y, Cai J, Hoff G. Secular trends in hospital emergency department visits for dental care in Kansas City, Missouri, 2001–2006. Public Health Rep 2011;126:210–219. 15. Kulild JC, Peters DD. Incidence and configuration of canal systems in the mesiobuccal root of maxillary first and second molars. J Endod 1990;16:311–317. 16. Morris P, Perkins A. Diagnostic imaging. Lancet 2012;379: 1525–1533. 17. Yong R, Ranjitkar S, Townsend G, et al. Dental phenomics: advancing genotype to phenotype correlations in craniofacial research. Aust Dent J 2014;59(Suppl 1):34–47. 18. Townsend GC, Brook AH. The face, the future, and dental practice: how research in craniofacial biology will influence patient care. Aust Dent J 2014;59(Suppl 1):1–5. 19. Anderson P, Yong R, Surman T, Rajion Z, Ranjitkar S. Application of three-dimensional computed tomography in craniofacial clinical practice and research. Aust Dent J 2014;59 (Suppl 1):174–185. 20. Ball IA. Balancing the extraction of primary teeth: a review. Int J Paediatr Dent 1993;3:179–185. 21. Zhou J, Zhao YF, Xia CY, Jiang L. Periodontitis with hypercementosis: report of a case and discussion of possible aetiological factors. Aust Dent J 2012;57:511–514.
1. Tran C, Gussy M, Kilpatrick N. Pathways to emergency dental care: an exploratory study. Eur Arch Paediatr Dent 2010;11: 97–100.
22. Rosen E, Tsesis I, Tamse A, Bjorndal L, Taschieri S, Givol N. Medico-legal aspects of vertical root fractures in root filled teeth. Int Endod J 2012;45:7–11.
2. Unkel JH, McKibben DH, Fenton SJ, Nazif MM, Moursi A, Schuit K. Comparison of odontogenic and nonodontogenic facial cellulitis in a pediatric hospital population. Pediatr Dent 1997;19:476–479.
23. Caspary G, Krol DM, Boulter S, Keels MA, Romano-Clarke G. Perceptions of oral health training and attitudes toward performing oral health screenings among graduating pediatric residents. Pediatrics 2008;122:e465–e471.
3. Marioni G, Rinaldi R, Staffieri C, et al. Deep neck infection with dental origin: analysis of 85 consecutive cases (2000– 2006). Acta Otolaryngol 2008;128:201–206.
24. Lewis CW, Boulter S, Keels MA, et al. Oral health and pediatricians: results of a national survey. Acta Pediatr 2009;9:457– 461.
4. Dalla Torre D, Burtscher D, Hofer D, Kloss FR. Odontogenic deep neck space infection as life-threatening condition in pregnancy. Aust Dent J 2014;59:375–378.
25. Hodgdon A. Dental and related infections. Emerg Med Clin North Am 2013;31:465–480.
5. Celakovsky P, Kalfert D, Smatanova K, et al. Bacteriology of deep neck infections: analysis of 634 patients. Aust Dent J 2015;60:212–215. 6. Kim MK, Allareddy V, Nalliah RP, Kim JE, Allareddy V. Burden of facial cellulitis: estimates from the Nationwide Emergency Department Sample. Oral Surg Oral Med Oral Pathol Oral Radiol 2012;114:312–317.
432
26. Skinner MF, Hung JTW. Localized enamel hypoplasia of the primary canine. ASDC J Dent Child 1986;53:197–200. 27. Needleman HL, Leviton A, Allred E. Macroscopic enamel defects of primary anterior teeth – types, prevalence, and distribution. Pediatr Dent 1991;13:208–216. 28. De-Deus G, Silva EJ, Marins J, et al. Lack of causal relationship between dentinal microcracks and root canal preparation with reciprocation systems. J Endod 2014;40:1447–1450. © 2015 Australian Dental Association
Facial swelling from subtle odontogenic defects 29. Metska ME, Aartman IH, Wesselink PR, Ozok AR. Detection of vertical root fractures in vivo in endodontically treated teeth by cone-beam computed tomography scans. J Endod 2012;38: 1344–1347.
32. Kalender WA. X-ray computed tomography. Phys Med Biol 2006;51:R29–R43.
30. Scarfe WC, Li Z, Aboelmaaty W, Scott SA, Farman AG. Maxillofacial cone beam computed tomography: essence, elements and steps to interpretation. Aust Dent J 2012;57(Suppl 1):46–60.
Address for correspondence: Dr Sarbin Ranjitkar School of Dentistry The University of Adelaide Adelaide SA 5005 Email: [email protected]
31. Huang CC, Chang YC, Chuang MC, et al. Analysis of the width of vertical root fracture in endodontically treated teeth by 2 micro-computed tomography systems. J Endod 2014;40: 698–702.
© 2015 Australian Dental Association
433
