Monitoring of healing by ultrasound with color power doppler after root canal treatment of maxillary anterior teeth with periapical lesions

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1 Original Article Monitoring of healing by ultrasound with color power doppler after root canal treatment of maxillary anterior teeth with periapical lesions Ipsita Maity, Anitha Kumari, Anil Kumar Shukla 1, HL Usha, DN Naveen Department of Conservative Dentistry and Endodontics, V. S. Dental College and Hospital, 1 Department of Radiology, Kempegowda Institute of Medical Sciences, Bangalore, India A b s t r a c t Aims: To assess the reliability of ultrasound imaging coupled with Color Power Doppler for monitoring the healing after nonsurgical endodontic therapy. Materials and Methods: Ten asymptomatic maxillary anterior teeth with approximately similar-sized periapical radiolucent lesions of average dimension cm, as observed on an intraoral periapical radiograph, and confirmed by ultrasound was selected for the study. After confirming the diagnosis all the teeth were subjected to nonsurgical endodontic treatment. Postoperative healing was monitored using postoperative subjective feedback, a radiograph, and an ultrasound with a color power doppler, at intervals of six, three, and six. Results: Eight among the ten cases studied showed signs of healing, with an ultrasound, as early as six postoperatively, but the radiographs showed a noticeable change only at the end of three. At the end of the follow-up period of three and six, the findings in terms of change in the lesion size were the same with both the radiograph and ultrasound. Ultrasonography was able to predict the healing very consistently at all recall periods from six onward providing vital information such as changes in vascularity and bone formation as compared to radiographs. Conclusions: Ultrasound with Color Power Doppler is an efficient tool for monitoring bone healing as compared to the conventionally employed radiographic method. Keywords: Color power doppler; healing; neovascularization; periapical lesion; ultrasound INTRODUCTION Imaging techniques play a very important role in the speciality of endodontics. Radiographic images are routinely used in the field of endodontics for diagnosis, treatment planning, and follow-up of periapical bone lesions. [1] However, routine radiographic procedures do not reliably demonstrate the presence of every lesion. They do not provide information on the size of a lesion and its spatial relationship with the anatomic structures as it is a two-dimensional representation of a three-dimensional object. Also, the radiographs cannot differentiate between cystic and non-cystic lesions. [2,3] The traditional method for assessing the success of endodontic therapy involves a clinical examination coupled with recall radiographs. Studies have shown that conventional radiographs are not an ideal tool for Address for correspondence: Dr. Ipsita Maity, Vivekananda Abasan, 94/25, Nayapatty Road, Shyamnagar, Kolkata , India ipsita28_m@yahoo.com Date of submission: Review completed: Date of acceptance: monitoring healing, as there are a lot of variables involved in the developing and processing of a radiographic film. Additionally, there are limitations such as superimposition of anatomic structures, inability to observe minute changes in bone density, and inter-observer variations, in the interpretation of radiographs. Moreover, for monitoring the healing, multiple radiographs are required, which expose the patients to unnecessary radiation. [4] In the healing phase of a lesion, vascular changes are a most important feature and the radiographs do not reveal these changes in the bone. [3] Ultrasound Real Time Imaging [USG] and Color Power Doppler [CPD] have recently been found to be useful in the diagnosis and follow-up of periapical healing. USG has wide diagnostic applications in the field of medicine. It has revolutionized every sphere of science and technology. Access this article online Quick Response Code: Website: DOI: /

2 These applications are further enhanced by their combination with CPD, to assess blood flow. [4] CPD gives a color-coded representation of the doppler signal and its time modification. [4] Cotti et al, reported that USG imaging is a very useful technique, which can give significant diagnostic information in relation to periapical lesions in the anterior region, where the buccal bone is thin. [2] Bone surfaces demonstrate total reflection of the ultrasound waves, thus structures in and beyond the intact bone are not normally detectable by ultrasound. However, where the bone cortex has thinned or perforated, USG can still be performed through such Bone windows. This technique provides specific information on the size of a lesion, its vascular supply, and its internal content, and moreover, it is sensitive enough to distinguish the fluid content. [2] This clinical study was designed to asses the reliability of the ultrasound with CPD as a tool for monitoring the healing of periapical lesions at time periods of six, three, and six. MATERIALS AND METHODS Ten patients with a noncontributory medical history were selected for this study. After a thorough clinical examination and radiographic evaluation, patients with asymptomatic maxillary anterior teeth, with approximately similar-sized periapical lesions [average dimension 1.3 to 1.9 cm] of endodontic origin were included in this study. These patients were subjected to an investigation and treatment protocol involving a preoperative ultrasonographic examination followed by a nonsurgical, single-visit endodontic therapy. For the ultrasound technique, the machine used was the state-of-the-art GE Voluson PRO 730. This was a multitransducer system with doppler facilities. Preoperative ultrasound examination was carried out with an intracavitary multifrequency ultrasound probe of 8 12 MHz. The probe was first covered with a disposable latex for the control of infection and then covered with a layer of ultrasound gel. The probe was positioned intraorally on the buccal sulcus corresponding to the apical area of the tooth. All lesions were measured in three planes, that is, anteroposterior, superoinferior, and mesiodistal, and the dimensions were recorded. CPD was applied to each examination to detect the blood flow and the information was recorded. The periapical lesions were classified as granulomatous or cystic, based on the findings on USG combined with CPD, as seen in Table 1. Nonsurgical root canal treatment was performed on all the Table 1: Preoperative ultrasound features of all the ten cases Case Echography Margins PDF Diagnosis Nos. Vascularity 1. Focal Well-defined Cyst 2. Anechoic Well-defined Cyst 3. Poorly defined Traces Granuloma 4. Well-defined Cyst Anechoic and Focal 5. Focal Well-defined Cyst 6. Focal Well-defined Cyst 7. Focal Well-defined Cyst 8. Poorly defined Traces Granuloma 9. Anechoic Well-defined Cyst 10. Focal Well-defined Cyst patients in a single visit. Pre-procedural mouth rinsing was carried out with 0.12% chlorhexidine before the involved tooth was isolated with a rubber dam. The isolated area was disinfected with 0.12% chlorhexidine. Access opening was done with a sterile bur [Endo Access Bur, Dentsply] at a slow speed, with sterile saline as a coolant. Coronal flaring was carried out with a gates glidden drill. The working length was determined radiographically and was confirmed with an apex locator. It was followed by canal preparation using the hybrid technique-coronal two-third, with a gates glidden drill and apical one-third with the hand K-files. Each file was followed by irrigation with 2 ml of 1% NaOCl in a syringe, with a 27 gauze needle. [5] After completion of the shaping procedure, the canal was rinsed with 15% Ethylenediaminetetraacetic acid (EDTA) solution for one minute, using 5 10 ml of the solution. [5] Passive ultrasonic irrigation was carried out with 1% NaOCl for at least three minutes, after completing the canal preparation. [6,7] A final rinse with 2% chlorhexidine was used in the canal. Various studies have proved that 2% chlorhexidine significantly reduces the bacterial loads in the root canal. [5,8] The master cone was selected on the basis of the master apical file size. The canal was obturated using the lateral condensation method, with zinc oxide eugenol as the sealer. Finally the access cavity was restored with Glass Ionomer Cement (GIC). The patients were followed up after treatment with clinical, radiological, and ultrasonographical evaluation to monitor the healing process at the end of six, three, and six. Clinically the patients were evaluated for pain, swelling, tenderness on palpation and percussion, and presence or absence of sinus. All the radiographs were taken using the paralleling 253

3 a b c d a b e f g Figure 1: (a) Preoperative: Showing dimension and volume, (b) Preoperative: Application of CPD showing no vascularity, (c) Postoperative six : Showing dimension and volume, (d) Postoperative six : Application of CPD Showing presence of vascularity, (e) Postoperative three : Showing dimension and volume, (f) Postoperative three : Application of CPD showing presence of reduced vascularity than before, due to bone deposition, (g) Postoperative six : Complete healing of the lesion technique, with the help of the XCP Rinn instrument and analyzed with the help of the Adobe Photoshop CS image analysis software, and changes in the lesion dimensions were noted [9-11] [Figures 2-3]. Ultrasonographically, the echo changes, changes in the dimension and volume of the lesion, and vascularity of the periapical lesions were observed and recorded. The ultrasonographical examination was carried out by a qualified, experienced radiologist [Figures 1a-g]. The informed consent of all patients who participated in this study was obtained after the nature of the procedure and possible discomforts and risks had been fully explained. Results Follow up of the periapical lesions at the end of 6 c d Figure 2: (a) Preoperative radiograph [Granuloma], (b) postoperative radiograph [no changes are seen], (c) postoperative [decrease in size of lesion], (d) postoperative [completely healed] showed no detectable changes radiographically as compared to the pre-operative one. Evidence of healing in the radiograph was noticed only at the end of 3, where the size of the lesions had decreased in 8 cases. At the end of 6, 3 cases had completely healed, 5 cases were healing lesions and two cases had failed. Ultrasonographically decrease in the size and volume of the lesion was evident as early as 6 post-operatively. Changes in echo and vascularity were also seen in eight cases. By the end of 3, further decrease in the size of the lesion and volume and increase in echogenicity indicating healing were observed. At the end of 6, 3 patients showed complete healing, 5 cases were healing lesions and two cases had failed. DISCUSSION Accurate assessment of the periradicular status is crucial in the diagnosis, treatment, and evaluation of healing in endodontic therapy. The traditional method of assessing the success of endodontic therapy involves clinical examination and the use of periodic recall radiographs. The problem of unreliability in the radiographic interpretation of periapical lesions has been addressed by numerous studies since [12] To better predict the outcome of 254

4 that only two patients, Case Nos. 5 and 7, were clinically symptomatic. The other patients were completely asymptomatic. a b The radiographic follow-up for all the ten cases, showed no detectable changes at the end of six. Significant evidence of healing was noticed only at the end of three for eight cases; the lesion size had decreased from the preoperative size, In case of No. 5, the lesion showed no changes and in case of No 7, the lesion showed a slight increase in size, indicative of a progressing lesion. In this study, the ultrasonographic probe was used intraorally to avoid interference of the labial blood supply with that of the lesion. Moreover, extraoral probe placement would be more difficult than intraoral placement because of the interference of the nasal structures. [1] The thin anterior buccal bone and possible fenestration allowed the ultrasound images to be obtained in all the cases and the echo characteristics of the apical lesions were determined. c d Figure 3: (a) Preoperative radiograph [cyst], (b) postoperative radiograph, (c) postoperative [decrease in the size of lesion], (d) postoperative [further decrease in the size of lesion] nonsurgical endodontic treatment, it is important to evaluate new and more promising methods of imaging for the study of periapical lesions. [2] Ultrasound with CPD is recognized as one of the most risk-free methods for evaluating any disease in the human body. Cotti et al, reported positive findings using the ultrasound in the differential diagnosis of periapical lesions and found it to be a very useful imaging technique, which could give significant diagnostic information in relation to periapical lesions in the anterior region, where the buccal bone is thin. [2,3] Apart from its use as a diagnostic tool, the ultrasound is also used in orthopedics for monitoring the healing of fractured bones. [13] It possesses the advantage of being a noninvasive and radiation-free procedure. Studies have shown that as compared to conventional radiographs, ultrasound with CPD clearly reveals the healing of the fracture along with details of the improvement in vascularity of the affected bone. [4] In the present study, the follow-up protocol during the recall period to monitor post endodontic healing included, clinical examination, radiographic examination, and ultrasonographic examination. During the recall period, the clinical examination showed Table 2 shows that with the help of ultrasonographic examination, changes in size and volume of the lesion, changes in echo, and the presence of vascularity were detectable as early as six postoperatively [Figures 1c and d] for eight cases. The changes detected by ultrasound and CPD in the eight healing cases also included proliferation of the blood vessels (NEOVASCULARIZATION). Figure 1d shows signs of neovascularization as denoted by red spicules. This clearly demonstrates that ultrasound coupled with CPD is a superior tool as compared to radiographs, for evaluating post-endodontic healing at the end of six. No changes were seen in cases 5 and 7 at the end of six. By the end of three, a further decrease in the size of the lesion and volume and increase in echogenecity and decrease in the flow signal [Figures 1e and f], in terms of vascularity was observed for the eight healing cases. The observed decrease in vascularity is known to indicate remodeling of the cortical plate, which interferes with the CPD signals. [4] Case 5 showed no changes and case 7 shows a slight increase in the size of the lesion. At the end of six an ultrasound examination of the three patients showed echogenicity comparable to the normal bone in the healing lesion, as seen in Figure 1g. This suggests that there was complete new bone formation in that area. The lesion size and volume in the remaining five cases decreased in a manner that could be related to progressive healing. No doppler signal was noted at six, as is evident in Figure 1g. The CPD detects minute areas of blood flow in the healing bone by recording the change in frequency caused by the moving red blood cells. It demonstrates the 255

5 Table 2: Preoperative and postoperative ultrasound and color power doppler findings in the periapical lesions Preoperative Postoperative Case and Tooth Nos. Cases 1, Cases 2, 11, and 12 Cases 3 and 21 Cases 4, Cases 5, 11, and 12 Cases 6 and 21 Cases 7, Cases 8, Cases 9, 11, and, 12 Cases 10 and 21 Dimension [in cm] Volum [in cm 3 ] Focal Hypo-echoic Echo Vascularity Dimension [in cm] Volume [in cm 3 ] Anechoic anechoic and focal Focal Focal Focal three six three Anechoic Focal three Echo Hypoehoic at Focal Focal at Focal Focal Focal Focal at at Focal Focal Focal at hyperechoic Focal Focal at hyperechoic Vascularity progressive formation of new blood vessels in the bone during the initial healing period. As bone remodeling proceeds, there is a decrease in flow signals. This is attributed to the decrease in penetration of the doppler 256

6 ultrasound waves with an increase in bone deposition over the affected region. In contrast, a lack in development of flow signals during the first six may indicate delayed bone healing or non-healing lesions. In this study it was also possible to recognize the initial signs of healing in eight patients, by ultrasonography, in as early as six, by observing the change in the initial regions becoming hyperechoic postoperatively. Ultrasound has an advantage over CT scans, in that it is free of ionizing radiations. [14,15] However, the major disadvantage of ultrasound is that it can only be used if there is a bony defect over the lesion, through which ultrasonic waves can traverse. [2] The other limitation of ultrasound is that it cannot be used easily in the posterior region of the mouth as accessibility is difficult with the present probe design. The presence of a thick cortical plate in the posterior region prevents the ultrasound waves from traversing easily. This study confirms that ultrasound real time imaging is a useful imaging technique, which can give significant information in relation to a periapical lesion in the anterior region. USG is easy, reproducible, and convenient to use. The equipment is relatively cheap compared to the other advanced imaging modalities. The images obtained are easy to read once the observer is trained. By obtaining a real time image, a working diagnosis can be made without delay and it also prevents unnecessary exposure of the patient to ionizing radiation. No harmful effects of ultrasound waves have been observed in the tissues as a result of ultrasound examination. As of now ultrasound devices do not have probes specifically designed for intraoral use. In order to make ultrasound more practical, an effective modification of the probe, especially for intraoral use, is required. CONCLUSIONS From this study it can be concluded that ultrasound with color power doppler is a very important and efficient tool for diagnosis and also for monitoring post-endodontic healing. ACKnowledgement We would like to express our deep sense of gratitude and sincere thanks to Dr. N. Meena, Professor and Head of the Department, Dr. Ashish Shetty K.R., Professor, Dr. N. Shubhashini, Dr. Adarsh M.S., Dr. Anjali Kaiwar, Dr. Chethana S. Murthy, Dr. Ranjini M.A., and Dr. Ashwini P. Santosh, Senior Lecturers, who willingly helped with their valuable suggestions and advice in completing this study. REFERENCES 1. Gundappa M, Ng SY, Whaites EJ. Comparison of ultrasound, digital and conventional radiography in differentiating periapical lesions. Dentomaxillofac Radiol 2006;35: Cotti E, Campisi G, Garauand V, Puddu G. A new technique for the Study of periapical bone lesions: Ultrasound Real Time Imaging. Int Endod J 2002;35: Cotti E, Campisi G, Ambu R, Dettori C. 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J Endod 2008;34: How to cite this article: Maity I, Kumari A, Shukla AK, Usha HL, Naveen DN. Monitoring of healing by ultrasound with color power doppler after root canal treatment of maxillary anterior teeth with periapical lesions. J Conserv Dent 2011;14: Source of Support: Nil, Conflict of Interest: None declared. 257