Development of Virtual Simulation Platform for Investigation of the Radiographic Features of Periapical Bone Lesion

Application of Real-Time Augmented Reality-Guided Osteotomy and Apex Location in Endodontic Microsurgery: A Surgical Simulation Study Based on 3D-Printed Alveolar Bone Model

INTRODUCTION

Augmented reality (AR) is a novel visualization technique in which pre-generated virtual 3D content is superimposed on surgical sites. This study aimed to validate the viability of AR-guided endodontic microsurgery (ARG) and compare the changes in objective and subjective outcomes of surgical simulation using ARG and freehand endodontic microsurgery (FH) on customized 3D-printed models.

METHODS

We created and printed a customized 3D alveolar bone model with artificial periapical lesions (APLs) based on cone-beam computed tomography (CBCT). Eight models with 96 APLs were equally divided into ARG and FH groups. We planned surgical trajectories on re-scanned printed models. Four inexperienced residents (IRs) performed ARG and FH on the models and completed pre-and intraoperative confidence questionnaires for the subjective outcome. Postoperative CBCT scans of the models were reconstructed and analyzed, and all procedures were timed. We used pairwise Wilcoxon rank sum tests to compare objective outcomes. Kruskal-Wallis tests and post-hoc pairwise Wilcoxon rank sum tests were used to compare subjective outcomes.

RESULTS

Compared to the FH group, the ARG group significantly reduced deviation of the volume of bone removal, root-end resection, and deviation of bevel angle, with improved confidence of the IRs (P < 0.05); it also significantly increased surgical time and volume of unremoved APL (P < 0.05).

CONCLUSIONS

We customized an APL model through 3D printing and developed and validated a low-cost AR application framework, based on free AR software, for endodontic microsurgery. ARG allowed IRs to perform more conservative and precise surgical procedures with enhanced confidence.

Accuracy of Periapical Radiography and CBCT in Endodontic Evaluation

Introduction

A radiological evaluation is essential in endodontics, for diagnostic purposes, planning and execution of the treatment, and evaluation of the success of therapy. The periapical radiography is nowadays the main radiographic investigations used but presents some limits as 3D anatomic alteration, geometric compression, and possible anatomical structures overlapping that can obscure the area of interest. CBCT (cone beam computed tomography) in endodontics allows a detailed assessment of the teeth and surrounding alveolar anatomy for endodontic diagnosis, treatment planning, and follow-up.

Objective

The purpose of this study was to evaluate the accuracy of CBCT in comparison with conventional intraoral radiographs used in endodontic procedures.

Materials and Methods

Statistical analysis was performed on 101 patients with previous endodontic treatments with the relative radiographic documentation (preoperative, postoperative, and follow-up intraoral X-ray) that had underwent at CBCT screening for surgical reasons. The CBCT scans were evaluated independently by two operators and compared with the corresponding periapical images.

Results

Our analysis shows that the two radiological investigations statistically agree in 100% of cases in the group of patients without any endodontic sign. In the group of patients with an endodontic pathology, detected with CBCT, endodontic under extended treatments (30.6%), MB2 canals in nontreated maxillary molars (20.7%), second canals in nontreated mandibular incisors (9%), root fractures (2.7%), and root resorption (2.7%) were not always visible in intraoral X-ray. Otherwise, positivity in the intraoral X-ray was always confirmed in CBCT. A radiolucent area was detected in CBCT exam in 46%, while the intraoral X-ray exam was positive only in 18%.

Conclusions

Our study shows that some important radiological signs acquired using CBCT are not always visible in periapical X-ray. Furthermore, CBCT is considered as a II level exam and could be used to solve diagnostic questions, essential to a proper management of the endodontic problems.

The remaining dentin thickness investigation of the attempt to remove broken instrument from mesiobuccal canals of maxillary first molars with virtual simulation technique

Background

To investigate differences in the estimated minimum remaining dentin thickness (RDT) between periapical radiographs using the paralleling and parallax technique, after simulated removal of broken instrument from the mesiobuccal (MB) canal of maxillary first molar in virtual simulation model. The 3D measurement was taken as the standard for comparison.

Methods

Thirty-six maxillary first molars were scanned by micro-CT and reconstructed as 3-dimensional (3D) model. A virtual fragment of an instrument was created within the MB canal in software. Removal of the broken instrument was simulated in both the 3D and 2D dataset. Then, the models of all specimens were submitted to 2D and 3D measurements for the lowest (RDT) value in each. Differences in the values between the paralleling and parallax radiographic technique and the 3D-RDT value were analyzed with two-way Analysis of Variance. The Intra-class Correlation Coefficient (ICC) was used to assess consistency of the RDT measurements between the two periapical radiographic and techniques and 3D analysis.

Results

There was significant difference between RDT value obtained from the paralleling technique and 3D-RDT. There were no differences between RDT obtained from parallax (angled) technique and 3D-RDT. The ICC of RDT values between paralleling technique and 3D measurement were lower than 0.75. ICC between angled radiographs and 3D technique was close to 0.75. The optimal horizontal angle for the parallax technique was about 21°.

Conclusions

The virtual simulation technique can provide valuable insight into the benefit/risk analysis before removal of a broken instrument. Parallel radiographs overestimate the actual remain dentin thickness in mesiobuccal canals of maxillary first molars, whereas the parallel technique would give a closer estimate to the actual thickness at a projection angle of about 21°.

Effect of raloxifene on periapical lesions in ovariectomized rats

INTRODUCTION

The aim of this study was to evaluate the effect of raloxifene (RLX) during progression of periapical lesions in ovariectomized (OVX) rats.

METHODS

Female Wistar rats were OVX or subjected to sham surgery and received vehicle or RLX by gavage for 90 days. The treatment groups were as follows: sham surgery and treated with vehicle (SHAM-veh), OVX and treated with vehicle (OVX-veh), and OVX and treated with RLX (OVX-RLX). During treatment, the pulp of lower first molar was exposed to the oral environment for induction of periapical lesion that was analyzed 7 or 30 days after procedure. Blood samples were taken from jugular vein for measurement of estradiol, and the mandibles were removed and prepared for radiographic, histopathologic, histometric, and immunohistochemical analysis.

RESULTS

Estradiol plasma concentration showed hypoestrogenism in OVX rats. The histopathologic analysis of the OVX/RLX group was similar to that of the SHAM-veh group, whereas OVX-veh group showed larger periapical lesions with more intense inflammatory response and more cells positive for tartrate-resistant acid phosphatase. Radiographically, the groups were similar, but lesions on day 7 were smaller than lesions on day 30.

CONCLUSIONS

The results suggest that hypoestrogenism potentiates the progression of periapical lesions, and such condition was reversed by treatment with RLX.

Accuracy of digital radiography and cone beam computed tomography on periapical radiolucency detection in endodontically treated teeth

Objectives

The aim of the present study was to compare the accuracy of intraoral digital periapical radiography and cone beam computed tomography in the detection of periapical radiolucencies in endodontically treated teeth.

Material and Methods

Radiographic images (cone beam computed tomography [CBCT] scans and digital periapical radiography [PR] images) from 60 patients, achieved from September 2008 to July 2013, were retrieved from databases of the Department of Oral Diseases, Lithuanian University of Health Sciences. Twenty patients met inclusion criteria and were selected for further evaluation.

Results

In 20 patients (42.4 [SD 12.1] years, 65% men and 35% women) a total of 35 endodontically treated teeth (1.75 [SD 0.91]; 27 in maxilla and 8 in mandible) were evaluated. Overall, it was observed a statistical significant difference between the number of periapical lesions observed in the CBCT (n = 42) and radiographic (n = 24) examinations (P < 0.05). In molar teeth, CBCT identify a significantly higher amount of periapical lesions than with the radiographic method (P < 0.05). There were significant differences between CBCT and PR in the mean number of lesions identified per tooth (1.2 vs 0.66, P = 0.03), number of teeth with lesions (0.71 vs 0.46, P = 0.03) and number of lesions identified per canal (0.57 vs 0.33, P = 0.005). Considering CBCT as “gold standard” in lesion detection with the sensitivity, specificity and accuracy considering as score 1, then the same parameters of PR were 0.57, 1 and 0.76 respectively.

Conclusions

Within the limitations of the present study, it can be concluded that cone beam computed tomography scans were more accurate compared to digital periapical radiographs for detecting periapical radiolucencies in endodontically treated teeth. The difference was more pronounced in molar teeth.

Radiological diagnosis of periapical bone tissue lesions in endodontics: a systematic review

This systematic review evaluates the diagnostic accuracy of radiographic methods employed to indicate presence/absence and changes over time of periapical bone lesions. Also investigated were the leads radiographic images may give about the nature of the process and the condition of the pulp in nonendodontically treated teeth. Electronic literature search included the databases PubMed, Embase and CENTRAL from January 1950 to June 2011. All languages were accepted provided there was an abstract in English. The MeSH terms were 'Cone beam computed tomography (CBCT)', 'Radiography, panoramic', 'Periapical diseases', 'Dental pulp diseases', 'Sensitivity and specificity', 'receiver operating characteristics (ROC) curve', 'Cadaver', 'Endodontics' and 'Radiography dental'. Two reviewers independently assessed abstracts and full text articles. An article was read in full text if at least one of the two reviewers considered an abstract to be potentially relevant. Altogether, 181 articles were read in full text. The GRADE approach was used to assess the quality of evidence of each radiographic method based on studies of high or moderate quality. Twenty-six studies fulfilled criteria set for inclusion. None was of high quality; 11 were of moderate quality. There is insufficient evidence that the digital intraoral radiographic technique is diagnostically as accurate as the conventional film technique. The same applies to CBCT. No conclusions can be drawn regarding the accuracy of radiological examination in identifying various forms of periapical bone tissue changes or about the pulpal condition.

A suggested technique for the application of the cone beam computed tomography periapical index

OBJECTIVES

Cone beam CT (CBCT) produces undistorted three-dimensional (3D) images of the maxillofacial region with a radiation dosage lower than conventional CT. The periapical index score (PAI) is commonly used to follow up the lesions in the bone using periapical radiographs. Recently, a new PAI based on CBCT was introduced (CBCT-PAI). The aim of this technical report is to present a modified reproducible method to assess the CBCT-PAI.

METHODS

CBCT was used to evaluate a periapical bone lesion observed in the area of tooth number 13 before treatment and 2 years after treatment. The modified CBCT-PAI was applied to both the examinations to measure the lesion. The dimensional analysis of the lesion was performed in each plane, assessing three fixed and reproducible dimensions: mesiodistal (M-D), buccolingual (B-L) and coronoapical (C-A). The images were evaluated by three mutually independent examiners. Data were collected and reported in a chart. The results were compared with each other and with the PAI score from the periapical radiographs.

RESULTS

The three observers reported the same measurements of the lesion for each plane. The CBCT-PAI follow-up showed a reduction of the size of the lesion (5D vs 4D) but also an increase in the erosion of the buccal cortical plate. The comparison of CBCT-PAI with classic PAI showed the first method to be more precise.

CONCLUSIONS

This technical report shows how the CBCT-PAI can be applied to the CBCT exam of a periapical lesion in a reproducible way.