Diagnostic accuracy of CBCT for periodontal lesions

Objectives

The present study compares the diagnostic value of periodontal bone defect images using conventional two-dimensional single-tooth radiographs and three-dimensional cone beam computed tomography (CBCT) images.

Materials and methods

Classified periodontal bone defects were prepared on pig mandibles and presented radiographically. Fifteen dentists were instructed to make a diagnosis based on these x-rays, regarding the type and the extent of the bone defects. Subsequently, the results were evaluated and compared to the morphology of the surgically prepared defects as the gold standard.

Results

On average, the diagnosis of infrabony defects were 21 %, dehiscence 25 %, and fenestration 33 % more accurate using the three-dimensional projection than with the single-tooth radiograph. Furthermore, the CBCT allows grade II furcation to be captured more accurately.

Conclusions

The results of this study indicate that a considerably more precise analysis of periodontal defects is possible due to the third dimension. Particularly, in the oro-vestibular orientation, defects could be detected significantly more accurate.

Clinical relevance

CBCT images offer an advantageous alternative to the conventional single-tooth radiograph while taking the higher exposure of radiation into account.     

Radiologic bone loss in patients with bisphosphonate-associated osteonecrosis of the jaws: a case–control study

Objectives

Most patients with bisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) report a previous tooth extraction at the necrosis site before the diagnosis was made. At older ages, most teeth are extracted due to periodontal disease, which is per se another BP-ONJ trigger factor. The aim of this study was to evaluate the periodontal status of BP-ONJ patients using panoramic radiographs compared to a control.

Materials and methods

All patients treated for BP-ONJ up to January 1, 2010 comprised the study. The very first panoramic radiograph was analyzed. The number of remaining teeth and the radiographic bone loss from the cemento-enamel junction to the crestal bone were measured. For each patient, one control was analyzed (matching for gender and age).

Results

One hundred twenty-nine BP-ONJ panoramic radiographs and 129 controls were analyzed (68 women, 61 men; 67.3?±?9.7 years; osteoporosis [n?=?11], breast cancer [n?=?33], multiple myeloma [n?=?61], prostate cancer [n?=?24]). The average number of remaining teeth was 12.9?±?8.4 for BP-ONJ and 16.4?±?9.4 for the control (p?=?0.02). The average radiographic bone loss was 5.5?±?2.3 mm for BP-ONJ and 3.1?±?1.1 mm for the control (p?<?0.001); 96.6 % of BP-ONJ and 77.5 % had radiographic bone loss of more than 5 mm. Radiographic bone loss in the molar region was the highest for both groups (BP-ONJ 6.0?±?2.3 mm; control 3.6?±?1.4 mm).

Conclusion

Prevalence and severity of periodontal disease in patients with BP-ONJ is higher compared to healthy controls.

Clinical relevance

Patients with periodontal disease might be at a higher risk of developing BP-ONJ; therefore, periodontal disease therapy in patients who are about to receive bisphosphonates should be undertaken.     

The use of cone beam computed tomography to predetermine root canal lengths in molar teeth: a comparison between two-dimensional and three-dimensional measurements

Objectives

The aim of this study was to evaluate the accuracy of two-dimensional (2D) and three-dimensional (3D) root canal length measurements in molar teeth using cone beam computed tomography (CBCT).

Materials and methods

Root canal lengths of twenty molar teeth were measured with two different CBCT approaches. After adjusting the CBCT images, 2D measurements were performed within the sagittal plane between the apical foramen and the coronal reference (cusp). The 3D approach measured centrically in axial planes. A linear mixed model with random intercepts was fitted to compare differences between methods (2D and 3D). The correlation between CBCT measurements and the actual root canal length was evaluated using the Pearson correlation coefficient.

Results

Differences between 3D measurements and the actual root canal lengths were significantly smaller compared to the 2D approach (p?<?0.001). Mean differences were 0.32 and 0.58 mm, respectively. A high correlation was found between the actual root canal length and 3D measurements (Pearson correlation coefficient?=?0.97). Compared to the actual root canal length, 80 % of the 3D measurements were within the limits of ±0.5 mm.

Conclusions

3D measurements of root canals in molar teeth are more accurate than simple 2D measurements and show a high correlation to the actual lengths.

Clinical relevance

In cases where a CBCT is already available, root canal lengths in molar teeth can be accurately predetermined using a standardized 3D approach.     

Comparison of periodontal evaluation by cone-beam computed tomography,and clinical and intraoral radiographic examinations

Objectives

Cone-beam computed tomography (CBCT) has been widely used in many fields of dentistry. However, little is known about the accuracy of CBCT for evaluation of periodontal status. The objective of this study was to compare and correlate periodontal assessments among CBCT, clinical attachment loss (CAL) measurement, and periapical (PA)/bitewing (BW) radiography.

Methods

Eighty patients (28 males, 52 females; age range, 19–84 years) from the University of Texas School of Dentistry at Houston were evaluated retrospectively. Measurements were taken on the central incisors, canines, and first molars of the right maxilla and left mandible. CAL was extracted from periodontal charts. The radiographic distance from the cementum–enamel junction (CEJ) to the alveolar crest was measured for tooth mesial and distal sites on PA/BW and CBCT images using MiPacs software and Anatomage Invivo software, respectively. One-way ANOVA and Pearson analysis were performed for statistical analyses.

Results

The CEJ–crest distances for CBCT, PA/BW, and CAL were 2.56 ± 0.12, 2.04 ± 0.12, and 2.08 ± 0.17 mm (mean ± SD), respectively. CBCT exhibited larger values than the other two methods (p < 0.05). There were highly significant positive correlations among CBCT, PA/BW, and CAL measurements at all examined sites (p < 0.001). The Pearson correlation coefficient was higher for CBCT with CAL relative to PA/BW with CAL, but the difference was not significant (r = 0.64 and r = 0.55, respectively, p > 0.05).

Conclusions

This study validates the suitability of CBCT for periodontal assessment. Further studies are necessary to optimize the measurement methodology with CBCT.

     

Comparison of intraoral radiography and cone-beam computed tomography for the detection of horizontal root fractures: an in vitro study

Objectives

This study aimed to compare the diagnostic accuracy of two different cone-beam computed tomography (CBCT) units with several intraoral radiography techniques for detecting horizontal root fractures.

Methods

The study material comprised 82 extracted human maxillary incisors without root fractures that had not undergone any root canal treatment. Root fractures were created in the horizontal plane in 31 teeth by a mechanical force using a hammer with the tooth placed on a soft foundation as described in a previous study. The teeth were divided into two groups: a control group with no fractures and a test group with fractures. These were randomized to the empty maxillary anterior sockets of a dry human maxilla. Each tooth was imaged at various vertical angles using each of the following modalities: a 3D Accuitomo 170 CBCT, a NewTom 3G CBCT, a VistaScan PSP, a CCD sensor, and conventional film. Specificity and sensitivity for assessing horizontal root fracture by each radiographic technique were calculated. Chi-square statistics were used to evaluate differences between modalities. Kappa statistics assessed the agreement between observers. Results were considered significant at P?<?0.05.

Results

The kappa values for inter-observer agreement between observers ranged between 0.88 and 0.98 for the 3D Accuitomo 170, 0.82 and 0.91 for the NewTom 3G, and 0.61 and 0.72 for the different types of intraoral images. The diagnostic accuracy for detecting fracture lines in 3D Accuitomo 170 (0.93) was significantly higher than NewTom 3G (0.87), VistaScan (0.71), CCD (0.70), and CF (0.68).

Conclusions

3D Accuitomo 170 has the highest sensitivity and diagnostic accuracy for detecting horizontal root fracture among the 5 radiographic modalities examined. CBCT should be considered as the most reliable imaging modality of choice for the diagnosis of horizontal root fracture.

Clinical relevance

CBCT imaging offers the clear advantage over conventional imaging that traumatized teeth can be visualized in all three dimensions—especially the oro-facial dimension     

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.     

Quantification of circumferential bone level and extraction socket dimensions using different imaging and estimation methods: a comparative study

Objective

No studies have yet evaluated linear alveolar bone levels and extraction socket dimensions on dry skulls using different techniques. We aimed to investigate the accuracy of cone-beam computed tomography (CBCT), digital radiography, and digital photography.

Methods

Circumferential linear alveolar bone level measurements were performed at six sites on the examined teeth using gutta-percha points placed for reference at the cementoenamel junction and alveolar bone crest. Dimensions of the extraction socket were evaluated by linear measurements in the mesiodistal and buccolingual directions. Groups were formed according to the following imaging and estimation techniques: (1) direct measurement using digital calipers under loupe magnification (gold standard); (2) direct measurement using only digital calipers; (3) digital photographs/ImageJ (Photo/I); (4) digital paralleling long-cone periapical radiographs/ImageJ (Periapical/I); (5) digital panoramic radiographs/digital calipers; (6) digital panoramic radiographs/digital calipers and loupe magnification; (7) digital panoramic radiographs/ImageJ; and (8) CBCT/ImageJ (CBCT/I).

Results

Statistical analyses showed significant differences for all panoramic radiography subgroups in all examined regions compared with the gold standard (p < 0.001). Results of the CBCT/I (r = 0.930, p < 0.01), periapical/I (r = 0.939, p < 0.01), and Photo/I (r = 0.978, p < 0.01) techniques showed high correlation with the gold standard. Reliability of repeated measurements was higher with loupe magnification and the image-processing program.

Conclusions

Periapical/I and CBCT provide promising results in analyses of the dimensions and relations of periodontal tissues. Routine clinical digital photographs can be converted to scaled images and applied to treatment planning and preoperative–postoperative comparisons.

     

Incidental findings on cone beam computed tomography scans in cleft lip and palate patients

Objectives

Cone beam computed tomography (CBCT) is frequently used in treatment planning for alveolar bone grafting (ABG) and orthognathic surgery in patients with cleft lip and palate (CLP). CBCT images may depict coincident findings. The aim of this study was to assess the prevalence of incidental findings on CBCT scans in CLP patients.

Subjects and methods

Initial CBCTs taken from consecutive patients (n?=?187; mean age 11.7 years, range 6.9–45) with a non-syndromic orofacial cleft from January 2006 until June 2012 were systematically evaluated. Twenty-eight patients (mean age 19.3 years, range 13.2–30.9) had been subjected to ABG before their first CBCT was taken; 61 patients had a CBCT before and after ABG. Sinuses, nasopharynx, oropharynx, throat, skull, vertebrae, temporomandibular joint (TMJ), maxilla and mandible were checked for incidental findings.

Results

On 95.1 % of the CBCTs, incidental findings were found. The most prevalent were airway/sinus findings (56.1 %), followed by dental problems, e.g. missing teeth (52 %), nasal septum deviation (34 %), middle ear and mastoid opacification, suggestive for otitis media (10 %) and (chronic) mastoiditis (9 %), abnormal TMJ anatomy (4.9 %) and abnormal vertebral anatomy (1.6 %). In the 28 patients whose first CBCT was taken at least 2 years after ABG, bone was still present in the reconstructed cleft area except in 2 out of 12 patients with a bilateral CLP. The ABG donor site (all bone grafts were taken from the chin area) was still recognizable in over 50 % of the patients. Based on the CBCT findings, 10 % of the patients were referred for further diagnosis and 9 % for further treatment related to dental problems.

Conclusion

Incidental findings are common on CBCTs. Compared with the literature, CLP patients have more dental, nasal and ear problems. Thus, whenever a CBCT is available, this scan should be reviewed by all specialists in the CLP team focusing on their specific background knowledge concerning symptoms and treatment of these patients.

Clinical relevance

The high number of findings indicates that CBCT imaging is a helpful tool in the treatment of CLP patients not only related to alveolar bone grafting and orthognathic surgery but it also provides diagnostic information for almost all specialties involved in CLP treatment.     

Radiographic outcomes following treatment of intrabony defect with guided tissue regeneration in aggressive periodontitis

Objectives

This study reports the radiographic analysis of a split-mouth, single-blinded, randomised controlled clinical trial which was designed to compare the efficacy of simplified papilla preservation flap (SPPF) with or without guided tissue regeneration (GTR) in patients with aggressive periodontitis (AgP).

Methods

Eighteen AgP patients who had similar bilateral intrabony defects were treated. In all patients, the defects presented with radiographic evidence of an intrabony defect ≥3 and ≥5 mm of periodontal pocket depths (PPD). The surgical procedures included access for root instrumentation using SPPF alone (control) or, after debridement, a placement of resorbable GTR membrane (test). The standardised radiographic assessments were carried out at pre-surgical baseline and at 6 and 12 month post-surgery. Radiographic linear measurements and subtraction radiography were used as the method of analysis.

Results

Both treatments showed significant improvements in linear radiographic bone fill and defect resolution at 6 and 12 months, compared to baseline. The 12-month subtraction radiography at the GTR sites showed a significant improvement compared to the 6-month outcomes.

Conclusions

Both therapies were effective in the treatment of intrabony defects in AgP patients although no significant differences between them could be demonstrated. The finding that the bone fill and resolution of the defect at the GTR sites were significantly higher at 12 months than at 6 months after treatment indicates that bone regeneration is still an ongoing process at 6 months post-surgery.

Clinical relevance

Radiographic assessment of periodontal regeneration should be carried out at 12 months post-surgery in order to evaluate the complete healing of the bony defect.

     

Numerical simulation and biomechanical analysis of an orthodontically treated periodontally damaged dentition

Background and objective

Once periodontitis has been completely resolved, one common follow-up method is to carry out orthodontic treatment to take advantage of the residual bone, i.e., via tooth intrusion. In this study, the biomechanical behavior of teeth in a reduced periodontium was studied by numerically simulating upper-incisor intrusion accomplished with various orthodontic mechanics.

Materials and methods

Using the finite element method, a patient-customized 3D model of a periodontally reduced dentition was generated in order to simulate tooth movement. The morphology of this upper-jaw model was derived from cone-beam computed tomography (CBCT) datasets of four patients. Material parameters were adopted from previous investigations, including teeth (E=20 GPa), periodontal ligament (PDL) (bilinear elastic; E₁=0.05 MPa; E₂=0.20 MPa; ε₁₂=7%), and bone (homogeneous, isotropic; E=2 GPa). Two intrusion scenarios were used, the first drawing from Burstone’s segmented-arch technique to intrude four splinted incisors at a time, and the second one using cantilevers to intrude single incisors. The aforementioned PDL material parameters were varied in several ways to simulate different biological and biomechanical states of PDL. All simulations were recalculated with an idealized, periodontally intact model to assess the effect of bone loss by way of comparison.

Results

Single-tooth intrusion via cantilever mechanics was accompanied by less rotation than the segmented-arch approach. Both intrusion systems involved significantly greater degrees of tooth displacement and PDL load in the periodontally reduced model.

Conclusion

Periodontally reduced dentitions are associated with an increased load on periodontal tissue. This can be counteracted by reducing orthodontic force levels and by selecting mechanics that do not harm the tissue. In so doing, the use of numerical methods may greatly facilitate individualized computer-aided treatment-planning strategies.     

Influence of voxel size on the diagnostic ability of cone-beam computed tomography to evaluate simulated root perforations

Objectives

This study aimed to assess the use of different voxel sizes of a cone-beam computed tomography (CBCT) unit for detecting root perforations of different sizes and locations ex vivo and to compare the diagnostic possibilities of CBCT with those of periapical radiography (PR).

Methods

The study included 36 recently extracted intact human mandibular one-rooted teeth with developed apices. Root perforations of 0.2, 0.3, or 0.4 mm in diameter were drilled on the buccal and lingual sides at the cervical, middle, and apical thirds. A total of 216 portions were obtained. One tooth at a time was placed in a dry human mandible in an artificially created alveolus. Cross-sectional CBCT images were obtained using voxel resolutions of 0.4, 0.3, 0.25, and 0.2 mm. PRs were obtained using the paralleling technique in three directions in the horizontal plane: direct view, mesial angulation, and distal angulation with a 20° angle.

Results

There were no significant differences in sensitivity between 0.4/0.3 and 0.25/0.2-mm voxel resolutions. Significant differences were found between voxel sizes of 0.4/0.25, 0.4/0.2, 0.3/0.25, and 0.3/0.2 mm. The observers failed to diagnose any of the perforations using PR.

Conclusions

CBCT is a reliable imaging system for detecting root perforations that are not detectable with PR. A 0.2-mm voxel resolution was the best choice for diagnostic use in this study. Neither perforation location nor size influenced the diagnostic abilities of CBCT, except that it was harder to detect a root perforation in the apical part of the root.     

Orthodontic treatment of patients medicated with bisphosphonates—a clinical case report

Introduction

Bisphosphonates (BP) are an established medication, e.g., for the prevention/therapy of osteoporosis. The effects of the changed bone metabolism for orthodontic treatments are unknown.

Case report

A 66-year-old woman underwent a total oral rehabilitation. The therapy included (1) tooth extractions, (2) periodontal treatment, (3) insertion of dental implants, (4) provisional implant restorations, (5) orthodontic treatment, and (6) definite implant restorations. The orthodontic tooth movements were in- and retrusion of the upper frontal teeth, intrusion of the lower front teeth, using the dental implants as skeletal anchorage. After implant insertion and one month before beginning the orthodontic treatment, osteoporosis was diagnosed in this patient and, without notification to our facility, BP treatment was initiated by her general practitioner (alendronate oral, 70 mg/week), with an overall duration of intake of 7 months. After 13 months, the orthodontic treatment was successfully accomplished; however enlarged periodontal gaps, sclerotic bone areas, and mild apical root resorptions of the upper frontal teeth were found in this patient.

Conclusion

Currently, there are no recommendations for orthodontic patients undergoing BP therapy. Orthodontic tooth movement in this low-risk patient with a short duration of intake and a low-dose BP medication was possible. Because of the reduced bone metabolism and the higher amount of side effects, the treatment should be performed with extremely light forces and frequent monitoring.     

Imaging of mandible invasion by oral squamous cell carcinoma using computed tomography,cone-beam computed tomography and bone scintigraphy with SPECT

Objectives

The objective of this paper is to evaluate the predictability of preoperative tumour bone invasion of the mandible by squamous cell carcinoma of the oral cavity using CT, cone-beam CT and bone scintigraphy with SPECT.

Material and methods

Eighty-four patients who had received CT, SPECT or cone-beam computed tomography (CBCT), as well as a further 48 patients who undergone all these investigations for preoperative evaluation of bone invasion were included in the study. A case–control analysis and the receiver operating characteristics were performed. Histological results of bone specimens served as the gold standard for assessment of bone invasion.

Results

CBCT and SPECT showed a comparable sensitivity for bone invasion (93 % [CI 0.816–0.972] and 96 % [CI 0.867–0.990], respectively) which was significantly higher than that of CT (63 % [CI 0.488–0.752]). Further, CBCT obtained higher specificity than SPECT (62 % [CI 0.478–0.743] and 48 % [CI 0.342–0.614], respectively), whereas CT showed the best specificity among the investigation methods (81 % [CI 0.677–0.896]).

Conclusions

CT scan provides by its high specificity and positive predictive value a precise imaging technique for clinical routine. However, CBCT shows a much higher sensitivity for cortical bone invasion and a better negative predictive value. With a significantly lower exposure dose it can rule out this invasion effectively and prevent overtreatment.

Clinical relevance

Considering the high-resolution images delivered by CBCT along with minimized artefacts in the mandible it provides an alternative imaging technique, which could be combined and accomplished with another soft-tissue imaging modality like MRI to obtain optimal hard and soft-tissue visualisation in patients with squamous cell carcinoma of the oral cavity.     

Accuracy of peri-implant bone thickness and validity of assessing bone augmentation material using cone beam computed tomography

Objectives

The aim of this study was to evaluate the accuracy of measuring bone thickness surrounding dental implants and the reliability of assessing existence and completion of osseous integration of augmentation material using a cone beam computed tomography (CBCT) system.

Materials and methods

In jaws of foxhounds, artificial defects were regenerated by guided bone regeneration and then dental implants were placed. After putting down the dogs, the jaws were separated from the bodies and exposed in a CBCT system. The bone thickness was measured on both buccal and oral sides of the implants at different levels. Every examiner evaluated existence and integration of bone augmentation materials (BAM) and the completeness of marginal implant covering. The same measurements and evaluations were performed at digital images of the corresponding histological sections.

Results

The mean and the standard deviation of the differences between radiological and histological measurements of peri-implant bone thickness were ?0.22 mm and 0.77 mm, respectively. Sensitivity and specificity were 0.77 and 0.60 for existence of BAM, 0.59 and 0.74 for completed integration, and 0.39 and 0.71 for full covering of the implant surface.

Conclusions

The present study indicates that the PaX Duo3D® CBCT system allows measurements of peri-implant bone thickness at an accuracy of half a millimeter, and—within limits—assessing the existence and integration of BAM. It is not possible to evaluate whether the implant is covered completely by hard tissue.

Clinical relevance

Peri-implant bone thickness is a key factor for obtaining initial implant stability. The accuracy of its measurement has clinical impact. Radiological assessment of existence and integration of BAM would be of great benefit to the evaluation of augmentation procedures.     

Orthodontic bracket debonding: risk of enamel fracture

Objectives

Until now, it is not clear if various procedures of bracket debonding differ with regard to their risk of enamel fracture. Therefore, the objective of the present study was to compare these procedures biomechanically for assessing the risk of complications.

Materials and methods

An anisotropic finite element method (FEM) model of the mandibular bone including periodontal ligament, enamel, dentin, and an orthodontic bracket was created. The morphology based on the CT data of an anatomical specimen. Typical loading conditions were defined for each method of bracket debonding (compression, shearing off, twisting off). Shortly before the adhesive’s break, the induced stress in enamel, periodontal ligament, and in the alveolar bone was measured. The statistical analysis of the obtained values was performed in SPSS 19.0.

Results

Relatively high stresses occurred in the enamel using frontal torque (max. 44.18 MPa). With shearing off, the stresses were also high (max. 41.96 MPa), and additionally high loads occurred on the alveolar bone as well (max. 11.79 MPa). Moderate maximum values in enamel and alveolar bone appeared during the compression of the bracket wings (max. 37.12 MPa) and during debonding by lateral torque (max. 35.18 MPa).

Conclusions

The present simulation results indicate that the risk of enamel fracture may depend on the individual debonding procedure. Further clinical trials are necessary to confirm that.

Clinical relevance

For patients with prior periodontal disease or loosened teeth, a debonding procedure by compression of the bracket wings is recommended, since here the load for the periodontal structures of the tooth is lowest.     

Cone-beam computed tomography evaluation of palatogingival grooves: a retrospective study with literature review

Objectives

The purpose of the present study was to radiographically evaluate the prevalence and characteristics of palatogingival grooves (PGs) in maxillary anterior teeth on cone-beam computed tomography (CBCT) to better understand the nature of these defects.

Methods

The CBCT examinations of 993 teeth (330 canines, 315 lateral incisors, 348 central incisors) in 191 patients (87 males, 104 females; age range 16–80 years) were evaluated retrospectively. The diagnosis and radiographic condition of PGs were obtained by consensus among all observers. Verification of PGs was achieved from the patients’ clinical records, which were stored in a database after their clinical evaluation. Differences in age, sex, occurrence, and location were evaluated by the Chi-square test. The level of significance was set at p < 0.05.

Results

Among the 993 teeth examined, nine PGs were observed in seven lateral incisors and two central incisors in eight patients (four males and four females). There was one bilateral case in the lateral incisors. The frequencies of PG occurrence and affected patients were 0.90 and 4.18%, respectively, without significance for sex and location (p > 0.05).

Conclusions

PGs were a relatively infrequent anomaly of teeth in this population, but when present, clinicians should understand the clinical features of these root variations.

     

Absorbed dose to the eye lens during dental radiography

Objectives

Radiographic examinations have clinical validation/relevance in dental practice. Dentists pay strong attention to absorbed doses to the eye lens, which is located near or inside the irradiation field. Recently, the ICRP recommended a new threshold dose for the eye lens. Therefore, we carried out eye lens dose measurements using a head phantom.

Methods

We affixed fluorescence glass dosimeters to a head phantom and measured the absorbed doses during intraoral radiography, panoramic radiography, cephalography, helical scan computed tomography (helical CT), and dental cone beam computed tomography (dental CBCT).

Results

The mean absorbed dose to the eye lens in intraoral radiography examinations for maxillary incisor teeth and molar teeth was 0.11 ± 0.09 and 0.08 ± 0.04 mGy, respectively. Corresponding values in occlusal method examinations for the maxillary (craniocaudal angulation 70° parallel to the occlusal plane) and mandibular (craniocaudal angulation 90°) regions were 0.19 ± 0.01 and 0.19 ± 0.07 mGy, respectively. The mean value for panoramic radiography examinations was 0.07 ± 0.02 mGy, while that for cephalography examinations in the posteroanterior projection and left lateral projection was 0.02 ± 0.00 and 0.18 ± 0.02 mGy, respectively. The corresponding value for helical CT was 11.87 ± 1.12 mGy, while those for dental CBCT of the front teeth and molar teeth were 0.07 ± 0.02 and 0.12 ± 0.09 mGy, respectively.

Conclusions

Eye lens doses ranged between 0.02 and 0.19 mGy in individual radiographic examinations, including CBCT. Although helical CT recorded 11.87 mGy, it was still lower than the recent ICRP-recommended threshold (500 mGy).

     

A Retrospective Case Series in Regenerative Endodontics: Trend Analysis Based on Clinical Evaluation and 2- and 3-dimensional Radiology

Introduction

A regenerative endodontic procedure (REP) is a biologically based treatment to functionally replace the pulp of infected immature permanent teeth. The purpose of this retrospective case series was to assess the outcome of REPs of infected immature permanent teeth in terms of periapical bone healing (PBH), root development (RD), and pulp vitality.

Association of cortical shape of the mandible on panoramic radiographs with mandibular trabecular bone structure in Japanese adults: a cone-beam CT-image analysis

Objectives

The purpose of this study was to assess the association between the cortical shape of the mandible, as detected on panoramic radiographs, and trabecular bone structure, as assessed by cone-beam computed tomography (CBCT), in Japanese adults.

Methods

Panoramic radiographs and CBCT images of the mandibles of 50 subjects (18 men, 32 women), aged 45–86 years, were evaluated. An experienced oral and maxillofacial radiologist categorized the cortical shape of the mandible as detected on panoramic radiographs as normal, mildly to moderately eroded, and severely eroded cortices, respectively. All mandibles were scanned using CBCT. Four bone structure parameters of the basal portion of the mandible were calculated in three dimensions using an image-analysis system: total bone volume (mm³); cortical bone volume fraction (%); trabecular bone volume fraction (%); fractal dimension. One-way analysis of covariance with Bonferroni correction was employed to evaluate differences in the four bone parameters among the three cortical shape groups. Pearson’s correlation coefficient was calculated to examine correlations between age and cortical and trabecular bone volume fractions.

Results

Progression of cortical bone erosion was significantly associated with increased trabecular bone volume fraction (P < 0.001) and increased fractal dimension (P = 0.01). Cortical bone volume fraction decreased significantly with age (P = 0.04). However, trabecular bone volume fraction tended to increase with age (P = 0.06).

Conclusions

The change in the trabecular bone structure of the mandible may differ from that of the general skeleton in Japanese adults.     

Buccal cortical bone thickness at miniscrew placement sites in patients with different vertical skeletal patterns

Objective

Cortical bone thickness plays an important role in the primary stability of miniscrews. The purpose of this study was to evaluate the buccal cortical bone thickness in adolescent subjects with different vertical skeletal patterns using cone-beam computed tomography (CBCT).

Materials and methods

We examined the CBCT images of 75 patients (30 males, 45 females; mean age 16.5 years; range 15.3–17.7 years) in the present study. High-, average- and low-angle subgroups were generated according to SN-GoMe angle. On volumetric images, we measured the buccal cortical bone thickness from canine to the second molar teeth at heights of 5, 7 and 9 mm from cemento-enamel junction (CEJ). For statistical evaluation, the Wilcoxon signed rank, Kruskal–Wallis and Tukey HSD tests were applied at the p?Results Buccal cortical bone was thickest in the low-angle group. We observed statistically significant differences in the maxilla between the high- and low-angle groups at all levels. In the mandible, we noted statistically significant differences between high-angle and low-angle groups in the canine–first premolar regions at heights of 5 and 7 mm, and in the second premolar–first molar region at 7 mm height from CEJ. Significant differences were also present between the first and second premolars at heights of 7 and 9 mm. Average cortical bone thickness ranged from 1.10–1.37 mm in the maxilla and 1.20–3.28 mm in the mandible for all groups.

Conclusion

Buccal cortical bone thickness in adolescents varied in different vertical skeletal patterns and was greater in the mandible than in the maxilla, with the distance increasing from the CEJ to the apex. As the buccal cortical bone is thinner in high-angle patients, patient-specific measures should be taken when performing miniscrew treatment.