下颌阻生智齿相关第二磨牙牙根外吸收：曲面断层片与CBCT对比研究

目的 比较曲面断层片和CBCT在诊断下颌阻生智齿相关第二磨牙牙根外吸收的差异。方法 回顾性分析2019年1月—2020年12月于南京医科大学附属口腔医院就诊的832例(1 074颗)近中/水平下颌阻生智齿病例,分别应用曲面断层片和CBCT评估下颌第二磨牙远中牙根外吸收发生率,并分析曲面断层片诊断错误的相关因素。结果 以CBCT影像学结果判定为标准,下颌智齿相关第二磨牙牙根外吸收的发生率为33.15%(356/1 074),曲面断层片诊断正确率为66.39%。经多因素Logistic回归分析发现：中低位、Ⅲ类阻生智齿,下颌阻生智齿与第二磨牙牙根重叠,下颌阻生智齿与第二磨牙牙根接触是导致曲面断层片诊断错误的危险因素(P<0.05)。结论 曲面断层片诊断下颌阻生智齿相关第二磨牙牙根外吸收正确性较低,推荐选用CBCT检测。     

Reprint of: Prevalence and Characteristics of Root Resorption Identified in Cone-Beam Computed Tomography Scans

IntroductionRoot resorption is a destructive process that compromises tooth structure and can result in tooth loss. Often it remains asymptomatic and is an incidental finding on radiographic examinations. The purpose of this study was to determine prevalence and characteristics of root resorption in patients referred for cone-beam computed tomography (CBCT) imaging for a variety of indications.MethodsThe study included CBCT scans of 1086 consecutive patients referred for CBCT imaging over an 18-month period. A total of 1148 scans were acquired. Data were abstracted from radiology reports, and prevalence estimates of resorption were computed for the aggregate sample and also across specific indications.ResultsResorption was identified in 171 patients (15.7%, 95% CI: 13.6%–17.9%) and in 249 teeth with a prevalence range of 2.6%–92.3% across specific indications. An 18.7% of the patients had 2 resorption sites whereas 8.8% had 3 or more resorption sites. The majority of affected teeth were anteriors (43.8%), followed by molars (40.6%) and premolars (14.5%). The most prevalent resorption types were external (29.3%), cervical (22.5%), infection-induced apical resorption (13.7%), internal (9.6%), and impacted tooth induced (8.8%). The majority of teeth with resorption did not have prior endodontic treatment (73.9%) and had radiographically normal periapex (69.5%). Of 249 teeth with resorption, 31% presented as incidental finding. The prevalence of incidental findings of resorption increased with age, P < .05, and was significantly lower for anterior teeth (20.2%) as compared to premolars (41.7%) and molars (36.6%), (P < .05).ConclusionThe high proportion of incidental findings of resorption detected by CBCT suggests that resorption is not recognized/detected by conventional radiography and therefore remains underdiagnosed.     

Prevalence and Characteristics of Root Resorption Identified in Cone-Beam Computed Tomography Scans

IntroductionRoot resorption is a destructive process that compromises tooth structure and can result in tooth loss. Often it remains asymptomatic and is an incidental finding on radiographic examinations. The purpose of this study was to determine prevalence and characteristics of root resorption in patients referred for cone-beam computed tomography (CBCT) imaging for a variety of indications.MethodsThe study included CBCT scans of 1086 consecutive patients referred for CBCT imaging over an 18-month period. A total of 1148 scans were acquired. Data were abstracted from radiology reports, and prevalence estimates of resorption were computed for the aggregate sample and also across specific indications.ResultsResorption was identified in 171 patients (15.7%, 95% CI: 13.6%–17.9%) and in 249 teeth with a prevalence range of 2.6%–92.3% across specific indications. An 18.7% of the patients had 2 resorption sites whereas 8.8% had 3 or more resorption sites. The majority of affected teeth were anteriors (43.8%), followed by molars (40.6%) and premolars (14.5%). The most prevalent resorption types were external (29.3%), cervical (22.5%), infection-induced apical resorption (13.7%), internal (9.6%), and impacted tooth induced (8.8%). The majority of teeth with resorption did not have prior endodontic treatment (73.9%) and had radiographically normal periapex (69.5%). Of 249 teeth with resorption, 31% presented as incidental finding. The prevalence of incidental findings of resorption increased with age, P < .05, and was significantly lower for anterior teeth (20.2%) as compared to premolars (41.7%) and molars (36.6%), (P < .05).ConclusionThe high proportion of incidental findings of resorption detected by CBCT suggests that resorption is not recognized/detected by conventional radiography and therefore remains underdiagnosed.     

Prevalence and characteristics of intracoronal resorption in unerupted teeth in the permanent dentition: a retrospective study

Objective  To determine the prevalence, types of teeth, and distribution of intracoronal resorption in permanent dentition in a large population. Methods  A total of 9,570 panoramic radiographs were screened, and 2,922 unerupted teeth were examined. Results  The prevalence of intracoronal dentine defects was 1.55% in subjects and 0.95% in teeth. The highest prevalence of intracoronal radiolucencies was noted in the mandibular second molar (9.5%), followed by the maxillary second premolar tooth (4.7%). To our knowledge, this is the first report of coronal radiolucency in maxillary supernumerary teeth. Of the lesions identified, 39.3% were two-thirds of the dentine thickness, and 21.4% included the enamel; 85.7% of the defects were located at the central aspect of the crown. Ectopically positioned teeth showing intracoronal resorption accounted for 14.3% of the cases. Conclusions  Intracoronal resorption in an unerupted tooth occurs frequently and can be seen in more than one tooth in an individual. This condition is usually associated with not only an ectopic position but also resorption, which may be a progressive process. Dental clinicians should conduct periodic follow-ups, both clinical and radiographic, of these unerupted teeth.     

C-shaped canals in mandibular molars of a Brazilian subpopulation: prevalence and root canal configuration using cone-beam computed tomography

Objectives

To assess C-shaped root canal configuration by identifying its prevalence and each configuration type proportion, according to tooth (mandibular first or second molar) and demographic characteristics in a Brazilian population, using cone-beam computed tomography (CBCT). Moreover, it was verified if there is a relationship between root canal configuration observed in two-dimensional reconstructions of CBCT and presence of C-shape.

Methods

Mandibular jaw CBCT scans (184 males and 220 females, aged 15 to 80 years), which presented 1464 mandibular molars (710 first molars and 754 second molars), were assessed. Teeth were evaluated for the presence and type of C-shaped root canals by observing the roots at five levels in CBCT axial reconstructions. Root canal configuration was assessed in panoramic reconstructions. Data were statistically analyzed at a significance level of 5%.

Results

Of the 1464 mandibular molars, 125 (8.5%) were classified as C-shaped. This variation was more prevalent in females (n = 107, 85.6%) and in second molars (n = 108, 86.4%). C1 (uninterrupted C-shaped canal) was the most prevalent type of C-shaped configuration (41.76%), while C5 (no canal lumen) was the least prevalent type (0.96%). Single root with single canal in panoramic reconstructions was the most predominant configuration for C-shaped teeth (n = 54, 43.2%). Fused roots presented 17.2 higher odds of being associated with C-shaped root canals than non-fused roots.

Conclusions

C-shaped root canals were more prevalent in mandibular second molars and in females. Additionally, clinicians should bear in mind the greater possibility of C-shaped configuration in mandibular molars with fused roots.

Clinical relevance

Mandibular molars with C-shaped canals present a clinical challenge. A higher C-shaped proportion was noted in radiographic fused root types, which had 17.2 higher odds of presenting such anatomy when compared to radiographic non-fused roots. Root radiographic features may help in diagnosis of complex C-shaped morphologies.

     

Diagnostic accuracy of panoramic radiography,stereo-scanography and cone beam CT for assessment of mandibular third molars before surgery

Abstract

Objective. To compare the diagnostic accuracy of panoramic imaging, stereo-scanography and cone beam computed tomography (CBCT) for assessment of mandibular third molars. Material and methods. One hundred and twelve patients (147 third molars) underwent radiographic examination by panoramic imaging, stereo-scanography and CBCT. Tooth angulation, root morphology, number of roots and relation to the mandibular canal were assessed. The same variables were assessed intra- and post-operatively and served as reference for the radiographic assessments. The diagnostic accuracy for each variable was compared between the three modalities and accuracy was further expressed as sensitivity and specificity and tested between the modalities for identifying the relation to the mandibular canal. Results. There were no significant differences between the modalities regarding tooth angulation, root morphology and number of roots. However, CBCT was more accurate than stereo-scanography for determining root bending in the bucco-lingual plane (p = 0.02). Moreover, sensitivity for direct contact to the mandibular canal (panoramic imaging: 0.29, stereo-scanography: 0.57, CBCT: 0.67) was higher for CBCT than for panoramic images (p = 0.05) and specificity for no direct contact to the mandibular canal (panoramic imaging: 0.78, stereo-scanography: 0.53, CBCT: 0.68) was higher for panoramic images and CBCT than for scanograms (p < 0.001). Conclusion. Panoramic imaging, stereo-scanography and CBCT seem equally valuable for examination of tooth angulation, number and morphology of roots of mandibular third molars. However, CBCT was more accurate for assessment of root bending in the bucco-lingual plane and more accurate than panoramic images to identify direct contact to the mandibular canal.     

Is periapical surgery follow-up with only two-dimensional radiographs reliable? A retrospective cohort type sensitivity study

Background Two-dimensional (2D) radiographic techniques are commonly used for assessing lesion prognosis after endodontic surgery. The present retrospective cohort study analyzes the sensitivity and ability of different radiographic techniques in obtaining area and volume measurements of periapical lesions.Material and Methods Preoperative and follow-up (6-48 months) periapical and panoramic radiographs (index test) and cone-beam computed tomography (CBCT) images (reference standard) were selected from an endodontic microsurgery database. Sensitivity was analyzed independently by two examiners. The areas of the 2D radiographic images and CBCT volumes were studied using Itk-Snap software and Romexis viewer.Results The sample comprised 105 patients and 105 teeth, with a mean follow-up of 21 months (range 6-48). Preoperatively, CBCT detected all the periapical areas, periapical radiography detected 67, and panoramic radiography detected 60. Postoperatively, of the 52 cases in which CBCT detected remains of the periapical area, periapical radiography detected 22, and panoramic radiography detected 17. The measurements of the areas obtained by the 2D methods, and the volumes obtained by CBCT, had to be transformed into linear measures for comparison purposes. The measurements were found to be significantly different in both the preoperative and the follow-up images.Conclusions  Periapical radiography showed greater sensitivity than panoramic radiography, both preoperatively and at follow-up. The lesions measured with CBCT were larger, with significant differences than as evidenced by the periapical and panoramic radiographs. Key words:Periapical radiography, panoramic radiography, CBCT, sensitivity, treatment outcome, size of periapical radiolucency, area, volume.     

External root resorption of the second molar associated with mesially and horizontally impacted mandibular third molar: evidence from cone beam computed tomography

Objectives

The aim of the present study was to assess the incidence and risk factors of ERR in second molars with mesially and horizontally impacted mandibular third molars using cone beam computed tomography (CBCT) images from patients in a Chinese tertiary referral hospital.

Materials and methods

A total number of 216 patients with 362 mesially and horizontally impacted mandibular third molars who were treated at our institution from 2014 to 2015 was retrospectively included. The ERR in second molars was identified on CBCT multiplanar images. The associations between incidence of ERR and multiple clinical parameters were statistically analyzed by Chi-square test. Moreover, the risk factors for ERR in second molars were further assessed by multivariate regression analysis.

Results

The overall incidence of ERR in second molars was 20.17 % (73/362) as detected on CBCT images. The presence of ERR significantly associated with patients age and impaction depth of mandibular third molars. However, no significant relationship was found between ERR severity and impaction depth or ERR location. Multivariate regression analyses further revealed age over 35 years and impaction depth as important risk factors affecting the ERR incidence caused by mesial and horizontal impaction of mandibular third molar.

Conclusions

ERR in second molar resulted from mesially and horizontally impacted mandibular third molar is not very rare and can be reliably identified via CBCT scan.

Clinical relevance

Given the possibility of ERR associated with third molar impaction, the prophylactic removal of these impacted teeth could be considered especially for those patients with over 35 years and mesially and horizontally impacted teeth.

     

What kind of third molars are disease-free in a population aged 30 to 93 years?

Objectives

The aim of the study was to characterize third molars that have remained disease-free in a representative sample of the Finnish population aged 30 years and older.

Materials and methods

Two-staged stratified cluster sampling (N = 8028) was used, and 6005 subjects participated in a clinical oral examination and panoramic radiography. Disease-free third molars were characterized as follows: no dentinal caries, no filling, periodontal pocket depths of neighboring second molars less than 4 mm, and no radiographic pathological findings. Logistic regression analyses served for assessment of the strength of characteristics of third molars for disease-free status.

Results

Of the subjects, 2653 (44%) had at least one third molar. Of them, the majority (62%) had only diseased third molars, 16% had only disease-free ones, and 22% had both. Participants had in total 5665 third molars; 29% of them were disease-free. Female gender, higher level of education, and younger age were related to disease-free status (P < 0.001). Disease-free status was more likely for third molars at cervical or apical level than at occlusal level: odds ratio was 10.1 for all teeth, 8.5 for maxillary teeth, and 6.2 for mandibular teeth.

Conclusion

A third molar situated deeper in the bone was more likely to be disease-free than a tooth at occlusal level in the population aged 30 years and older.

Clinical relevance

Our results suggest that the number of disease-free third molars decreased with increasing age, and most dramatically, this occurred among teeth at cervical level with the neighboring second molar.

     

Influence of Length of Root Canal Obturation on Apical Periodontitis Detected by Periapical Radiography and Cone Beam Computed Tomography

IntroductionThe verification of the best length of root canal instrumentation and obturation still is controversial theme in endodontics. The purpose of this study was to determine the influence of length of root canal obturation on apical periodontitis (AP) detected by periapical radiography and cone beam computed tomography (CBCT).MethodsA total of 503 root canal obturations were evaluated by using periapical radiography and CBCT. Distances from the radiographic apex to the tip of filling material were measured and classified as close to 2 mm, 1 mm short or beyond apex, and at the apex. Obturations at the apex were associated with AP. Odds ratio, confidence intervals, and χ² test were used for statistical analyses.ResultsPeriapical radiographs showed that root canal obturations were 1–2 mm short of the apex in 88%, 89.3%, and 95% of the anterior teeth, premolars, and molars, respectively. CBCT images showed obturations had the same length in 70%, 73.7%, and 79% of anterior teeth, premolars, and molars, respectively. The frequency of AP was significantly greater in molars than in the other tooth groups, regardless of diagnostic method. AP was detected more frequently when CBCT was used.ConclusionsAP was detected at all lengths of root canal obturation. The analyses of diagnostic methods showed that AP was detected more frequently when CBCT was used.     

Evaluation of the maxillary third molar position and its relationship with the maxillary sinus: a CBCT study

Objectives

The present study investigated the position and relationship of the maxillary third molars to the maxillary sinus. These molars were detected to have a close relationship with the maxillary sinus based on panoramic images, using cone-beam computed tomography (CBCT).

Methods

This retrospective study evaluated 162 impacted third molars from 100 patients that showed a superimposed relationship between the maxillary sinus and third molars on panoramic images obtained from CBCT. CBCT images were used to assess the horizontal (buccopalatal) and vertical positions of the maxillary sinus relative to the maxillary third molars, proximity of the roots to the sinus, and angulation and depth of the third molars. The associations among the angulation, depth of third molars, and horizontal and vertical positions of the maxillary sinus relative to the third molar findings were examined using Chi square tests.

Results

Based on the winter classification, the most frequent tooth position was vertical (59.9 %), followed by mesioangular (14.2 %), distoangular (9.9 %), and others. Most impacted teeth were at the level between the occlusal and cervical levels of the adjacent second molar. Regarding the relationships of the maxillary third molars with the maxillary sinus examined on CBCT, vertical type III (buccal root related with maxillary sinus) (34 %) and horizontal type 2 (maxillary sinus located between roots) (64.8 %) were seen most frequently.

Conclusions

The relationship between the maxillary sinus and third molar roots should be considered during extraction. When a risk of sinus perforation is predicted in an extraction, a presurgical CBCT examination could be valuable.

     

Pre-eruptive intracoronal resorption of permanent dentition: A new classification and a multidisciplinary study

The aims of this study were to develop a new classification for pre-eruptive intracoronal resorption(PIR) with different resorption areas and sizes and to compare the new classification scores among observers from different specialities and professional experience. The PIR was evaluated according to the new classification by two dentomaxillofacial radiologists and two endodontists. Information regarding the patient's age, gender, systemic diseases, the number of PIR, the affected tooth area and the size of the PIR was recorded. The new classification system showed that PIR six and seven defects were the most detected. Regarding jaw regions, the highest reliability was seen in the maxillary central teeth between observers I and IV, and maxillary premolar-molar teeth between observers II and III. This study revealed that PIR can be found in both root and crown dentine. Professional experience and specialty and awareness of the PIR defect may affect the diagnosis.     

A survey of the first 6 years of experience with cone beam CT scanning in a teaching hospital orthodontic department

Abstract

Objective: Cone beam computed tomography (CBCT) is a specialized form of radiography and has been used in the Glasgow Dental Hospital since 2006. The clinical notes of all patients referred for CBCT from the orthodontic department between 2006 and 2011 were evaluated to determine the reasons for referral, scan parameters and clinical findings.

Design: Retrospective observational study.

Materials and methods: From a general database, the notes of patients from the Orthodontic Department of Glasgow Dental Hospital & School referred for CBCT imaging, since the inception of the service (2006 through to 2011) were examined. Information was obtained from CBCT request forms, case notes and radiology reports.

Results: During the chosen time period, 290 patients were referred for CBCT. Of these, 280 had clinical records that were available for investigation. Analysis showed approximately a third of scans were carried out within 4 weeks of referral. The smallest height of 4 cm was used for over a third of the scans investigated. Sixty-two per cent of the scans examined the maxilla only, 32% both jaws and 6% the mandible only. The two most common reasons for referral were to accurately determine the position of impacted teeth and to identify the presence of root resorption in relation to impacted teeth. In this cohort, 39% of teeth adjacent to an impacted tooth were found to have some root resorption, which closely supports the current literature.

Conclusions: This study provides a general overview of CBCT used by an orthodontic department in a teaching hospital environment.     

Investigation of the prevalence of impacted third molars and the effects of eruption level and angulation on caries development by panoramic radiographs

Background This study is aimed to determine the prevalence of impacted third molars and to investigate the effects of their eruption level and angulation on caries formation in the distal of the adjacent tooth.Material and Methods This cross-sectional study was conducted on panoramic radiographs of 38481 patients who were admitted to the Trakya University, Faculty of Dentistry. The panoramic radiographs of 7998 patients with at least one impacted third molar were included. Third molars were classified according to Winter’s classification and Pell and Gregory’s classification. The frequency of caries in partially impacted third molars and adjacent second molars was determined. The chi-square tests were used to determine potential associations between the third molars'' level of eruption, angulation, and caries development.Results The study group consisted of 4423 females (55.3%) and 3575 males (44.7%) with a mean age of 36.3±13.4 years. The prevalence of the third molar impaction rate was 23%. The impaction pattern of partially erupted third molars was characterized by an eruption level of A with the vertical position in both jaws. Partially erupted and vertically placed maxillary third molars in the level of position A caused more caries in the adjacent tooth and mesioangularly located partially erupted mandibular third molars were associated with more caries in the adjacent tooth.Conclusions The angulation and eruption level of partially erupted third molars should be carefully examined. The prophylactic extraction of vertically and mesioangularly located third molars, especially with an eruption level of position A can be suggested to eliminate the related complications and risk of caries. Key words:Dental caries, digital radiography, impacted tooth, panoramic radiography, third molar.     

Comparative assessment of panoramic radiography and CBCT imaging for radiodiagnostics in the posterior maxilla

Objective

The purpose of this study was to assess whether and how the information obtained by means of cone beam computed tomography (CBCT) on maxillary posterior teeth differs from that obtained by panoramic radiography.

Materials and method

From 157 subjects (mean age 48 years, range 19–84 years; 89 females) referred to the oral imaging center, a pair of panoramic and CBCT images was selected for further analysis. Both imaging modalities were analyzed to determine the topographic relationship of maxillary teeth to the sinus floor. Pathologic conditions, apical periodontitis, and presence of soft tissue thickening were also examined with both techniques.

Results

CBCT showed an intimate relationship of the first and second molar with the maxillary sinus in 54 and 38 %, respectively. Thirty-nine apical periodontitis lesions causing reactive changes in the maxillary sinus were detected by CBCT, while just six of them were diagnosed with panoramic imaging. A total of 26 teeth with apical extension to the maxillary sinus were detected with CBCT, from which two could be identified with panoramic radiography.

Conclusion

This study emphasizes that anatomical and pathological involvement of the maxillary sinus in relation to posterior teeth is considerably high. It is of clinical importance that the 3D nature of CBCT imaging allowed a better assessment of the relationship between the maxillary sinus and posterior root apices compared to the low detection on panoramic radiographs.

Clinical relevance

CBCT imaging can be a valuable adjunct in radioanatomical and radiodiagnostic observations in the posterior maxilla. It may better visualize maxillary sinus involvement for posterior upper teeth than panoramic radiography.     

Dentists’ use of digital radiographic techniques: Part II – extraoral radiography: a questionnaire study of Swedish dentists

Objective: The present study aims to gain knowledge about the dentist’s use and choice of digital extraoral imaging methods, panoramic radiography and cone beam computed tomography (CBCT).

Materials and Methods: A questionnaire sent to 2481 dentists within the Swedish Dental Society contained questions about the panoramic technique and CBCT technique used, education, clinic size and type of service. The response rate was 53%.

Results: The study showed that 61% of the Swedish dentists had access to panoramic techniques and that 84% used a direct digital sensor, while 6% used storage phosphor plate techniques. Around 8% of the Swedish dentists had access to CBCT. It was also observed that group practices had two times higher odds of having panoramic equipment compared with solo practices. Approximately 40% of the dentists had undergone postgraduate education in oral radiology during the last 5 years. Dental nurses and dental hygienists exposed 92% of the panoramic radiographs and 75% of the CBCTs. Thirty per cent of those clinics with access to a panoramic unit exposed >30 panoramic radiographs per month and 56% of the clinics having access to CBCT did more than 75 examinations per year.

Conclusions: Today 61% of Swedish dentists have access to panoramic radiography and 8% have access to CBCT. There is a greater likelihood of having access if the dentist works in the public dental health service or in a group practice and if the dentist has undergone any postgraduate course in oral radiology.     

Root and root canal morphology of permanent mandibular first and second molars in a Kuwaiti population: A retrospective cone-beam computed tomography study

AimEndodontic diseases typically affect the mandibular molars. Understanding the complex morphology of the root canal system and its variations is necessary for successful endodontic treatment. The aim of this study was to evaluate the morphology of roots and root canals of mandibular first and second permanent molar teeth in a Kuwaiti population using cone-beam computed tomography (CBCT).Materials and methodsCBCT images of 651 mandibular first and second molar teeth were obtained from specialist government dental centers. The age, sex, root canal configuration, and number and type of roots were recorded. The data were statistically analyzed.ResultsThe most common canal configuration in the mandibular first and second molars was type II (65.6% and 54.4%, respectively), with no significant difference seen between the sexes (p = 0.234). The canal configuration was significantly different between the mandibular first and second molars (p < 0.001). Most teeth had two roots (94.5%); split roots were common (92.6%) and the number thereof varied significantly. Radicular grooves were most common on the lingual side (4.9%). C-shaped canals were present in 43 (6.60%) teeth. Additionally, one tooth had a confluent middle mesial canal and nine (1.4%) had radix entomolaris.ConclusionMandibular molars in our Kuwaiti population typically had two split roots with type II and IV canal configurations. The prevalence rates of C-shaped canals, middle mesial canals, and radix entomolaris were remarkably low.     

Efficacy of clinical and radiological methods to identify second mesiobuccal canals in maxillary first molars

Abstract

Introduction. The success of endodontic treatment depends on the identification of all root canals. Technological advances have facilitated this process as well as the assessment of internal anatomical variations. The aim of this study was to compare the efficacy of clinical and radiological methods in locating second mesiobuccal canals (MB2) in maxillary first molars. Methods. Fifty patients referred for analysis; access and clinical analysis; cone-beam endodontic treatment of their maxillary first molars were submitted to the following assessments: analysis; access and clinical analysis; cone-beam computed tomography (CBCT); post-CBCT clinical analysis; clinical analysis using an operating microscope; and clinical analysis after Start X ultrasonic inserts in teeth with negative results in all previous analyses. Results. Periapical radiographic analysis revealed the presence of MB2 in four (8%) teeth, clinical analysis in 25 (50%), CBCT analysis in 27 (54%) and clinical analysis following CBCT and using an operating microscope in 27 (54%) and 29 (58%) teeth, respectively. The use of Start X ultrasonic inserts allowed one to detect two additional teeth with MB2 (62%). According to Vertucci's classification 48% of the mesiobuccal canals found were type I, 28% type II, 18% type IV and 6% type V. Statistical analysis showed no significant differences (p > 0.5) in the ability of CBCT to detect MB2 canals when compared with clinical assessment with or without an operating microscope. A significant difference (p < 0.001)was found only between periapical radiography and clinical/CBCT evaluations. Conclusion. Combined use of different methods increased the detection ofthe second canal in MB roots, but without statistical difference among CBCT, operating microscope, Start X and clinical analysis.     

Comparison of cone-beam computed tomography and periapical radiography for detecting simulated apical root resorption

Objective:To compare the diagnostic accuracy between cone-beam computed tomography (CBCT) and periapical radiography for detecting simulated external apical root resorption (EARR) in vitro.Materials and Methods:The study sample consisted of 160 single-rooted premolar teeth for simulating EARR of varying degrees according to four setups: no (intact teeth), mild (cavity of 1.0 mm in diameter and depth on root surface), moderate (0.4 mm, 0.8 mm, 1.2 mm, and 1.6 mm root shortening), and severe (2.4 mm, 2.8 mm, 3.2 mm, and 3.6 mm root shortening). Two groups of radiographic images were obtained via CBCT and periapical radiography. The absence or presence and the severity for all resorption lesions were evaluated blindly by two calibrated observers.Results:With the CBCT method, the rates of correct classification of no, mild, moderate, and severe EARR were 96.3%, 98.8%, 41.3%, and 87.5%, respectively; with the periapical radiography method, the rates were 82.5%, 41.3%, 68.8%, and 92.5%, respectively. Highly significant differences were found between the two imaging methods for detection of mild (P < .001), moderate (P < .001), and all EARR (P < .001). For detection of all EARR, the sensitivity and specificity values were 75.8% and 96.3% for CBCT, compared with 67.5% and 82.5% for periapical radiography.Conclusion:CBCT is a reliable diagnostic tool to detect simulated EARR, whereas periapical radiography underestimates it. However, if a periapical radiograph is already available to the diagnosis of EARR, CBCT should be used with extreme caution to avoid additional radiation exposure.