Cone beam computed tomography for dental and maxillofacial imaging: technique improvement and low-dose protocols

Midpalatal Suture Maturation in Relation to Age, Sex, and Facial Skeletal Growth Patterns: A CBCT Study

BACKGROUND

The evaluation of midpalatal suture maturation is essential to undertake the most predictable maxillary expansion approach. Several factors, such as age, gender, and facial growth patterns, seem to be involved in midpalatal suture staging and, consequently, in its opening; however, the link between these variables and the stages of midpalatal suture development remains poorly understood. Our study aimed to analyse the midpalatal suture maturation in relation to age, sex, and skeletal growth patterns by CBCT.

METHODS

We enrolled 263 patients (119 males and 144 females) aged from 8 to 20 years. The midpalatal suture maturation was defined according to Angelieri et al.'s classification using a low-dose CBCT. The chi-square test and linear regression were applied to investigate the suture stages by age, sex, and vertical and sagittal growth patterns.

RESULTS

Stage A was present in 8- and 9-year-olds with a larger prevalence in boys, while the prevalence of stage E increased progressively with age. Stage D was the most prevalent in our sample. The statistical analysis described that stage A was more likely in the youngest subjects, and stage E in the oldest participants. The males tended to have lower maturation stages. Moreover, the hypodivergent and normodivergent subjects tended to have higher maturation stages, while Class III was more likely in subjects in stages D or E.

CONCLUSIONS

A total of 127 patients were in stages A, B, and C, showing an unfused suture. In young individuals, the opening of the midpalatal suture leads to a proper facial growth development by correcting the transverse superior hypoplasia. The midpalatal sutural maturation classification was related to age, sex, and divergence.

Three-Dimensional Analysis of the Maxillary Sinuses in Ancient Crania Dated to the V-VI Centuries BCE from Opi (Italy): Volumetric Measurements in Ancient Skulls from the Necropolis of Opi, Abruzzi, Italy

Cone beam computed tomography (CBCT) can provide precise information about complex anatomical structures as it is characterised by rapid volumetric image acquisition with high resolution. The aim of this study was to provide measurements for 20 ancient skulls of the Samnite people found in the necropolis of Opi, a small and isolated mountain village in Abruzzo, a region in central Italy. All the images (left and right) of the 20 ancient skulls from Opi were acquired. All the data are the property of the Department of Innovative Technologies in Medicine and Dentistry of G. D'Annunzio University, Chieti, and different parameters (area and volume) were measured and evaluated. The mean and standard deviation of the facial measurements were also calculated. All the data were subjected to statistical analysis. CBCT scan data of 20 fossil skulls did not show significant values regarding the MS area and the volume between the right and left sides. In the ancient skulls, no difference was found between the right and left sides.

Changes in condylar position during orthodontic treatment depending on the amount of incisor retraction: a cone-beam computed tomography study

OBJECTIVES

Orthodontic treatment may be associated with temporomandibular disorders through changes in the condylar position. This study aimed to evaluate changes in the condylar position among different amounts of maxillary incisor retraction during orthodontic treatment using cone-beam computed tomography images.

MATERIALS AND METHODS

Fifty-four participants were enrolled and divided into minimal (n = 14), moderate (n = 20), and maximal (n = 20) retraction groups based on the amount of incisor retraction (< 1, 1-6, and > 6 mm, respectively). Changes in condylar position before (T0) and after (T1) orthodontic treatment were assessed for the superior, anterior, posterior, and medial joint spaces (SJS, AJS, PJS, and MJS, respectively). Changes in joint spaces were compared between T0 and T1 in each group using paired t-tests and among the three groups using analysis of variance.

RESULTS

Anterior movement of the condyle was observed in the maximal retraction group with a 0.2 mm decrease in ΔAJS and a 0.2 mm increase in ΔPJS, significantly greater than those in the minimal retraction group. The AJS and PJS showed statistically significant differences between T0 and T1 (P < 0.05) in the maximal retraction group.

CONCLUSIONS

The condyle may show a statistically significant but clinically insignificant forward movement in the maximal incisor retraction group, whereas it was relatively stable in the minimal and moderate incisor retraction groups.

CLINICAL RELEVANCE

More attention should be paid to the signs and symptoms of the condyle in patients with excessive incisor retraction during orthodontic treatment.

Concordance and reproducibility in the location of reference points for a volumetric craniofacial analysis: Cross-sectional study

Background

Considering the limitations of visualization that occur even with the use of radiographs, the cone beam computed tomography (CBCT) becomes more attractive to diagnose and propose an assertive treatment plan. This study aimed to evaluate intra and interobserver reproducibility, and concordance of 31 reference points we described considering visualization tools and the three planes of space in a bimaxillary CBCT.

Methods

Three observers located in triplicate the 31 reference points in the CBCT of six healthy patients. Friedman test was used to compare intraobserver paired samples, and interobserver concordance was determined by the intraclass correlation coefficient (ICC) with ranges>0.75 (excellent), between 0.60 and 0.74 (good), between 0.40 and 0.59 (sufficient) and<0.40 (poor). The P value was set at<0.05.

Results

A high ICC (>0.75%) was obtained by comparing the x, y, and z values at the location of landmark points. Excellent ICC>0.75 was for 81.7% and poor<0.40 was 7.5% in the interobserver evaluation. Data showed that 25 points had excellent concordance on the x-plane, 25 on the y-plane, and 26 on the z-plane (0.75%).

Conclusion

Intraobserver concordance analysis indicated that location of anatomical reference points on bimaxillary CBCT is performed with great reproducibility by interpreting their location with a clear description in the three planes of space. Complexity of achieving a good precision degree in the manual marking of reference points caused by convexities of the anatomical structures involved, might explain the variability found. The systematized location of the reference points would contribute to reduce such variability.

Evaluation of Third Molar Maturity Index by Cone Beam Computed Tomography in Legal Age Estimation: A Preliminary Study

ABSTRACT

This retrospective study aimed to evaluate the accuracy and applicability of the third molar maturity index (I 3M ) for discriminating Turkish minors from adults, and its relationship with chronological age using cone beam computed tomography (CBCT). A total of 122 CBCT scans of Turkish individuals (55 boys and 67 girls) aged 13 to 23 years were evaluated using the I 3M cutoff value. Chronological age gradually decreased as the I 3M value increased. The overall accuracy was 95.9%. The sensitivity and specificity of this test were 93.5% and 97.4%, respectively. Positive predictive value was 95.6%. The intraclass correlation coefficient values of the I 3M for the intraobserver and interobserver agreements were 0.998 and 0.996, respectively. This study showed relatively higher reproducibility of measurements on CBCT scans than on panoramic radiographs in the literature. Cone beam computed tomography may be advantageous and preferred over panoramic radiographs in distinguishing the legal age threshold of 18 years according to Cameriere's method when a more extensive investigation is needed to support the solution of challenging and uncertain cases in forensic medicine.

Computerized three-dimensional cephalometric template for Thai adults

Cephalometry is essential in several fields of study. These include health science, anthropology, and forensic studies. Furthermore, cephalometric norms are essential for numerous disciplines in the health sciences, such as clinical anatomy, plastic surgery, pediatrics, pediatric dentistry, orthodontics, oral and maxillofacial surgery, and forensic medicine. Three-dimensional (3D) cephalometric templates offer an advanced but simple method for these specialties. This study aimed to establish cephalometric norms by developing 3D templates for Thai adults, based on cephalometric landmark coordinates obtained from skull cone-beam computed tomography (CBCT) scans of individuals with normal skeletal patterns. Full-head CBCT scans of 45 individuals (20 men and 25 women) were obtained from the archive. All had a Class I molar relationship with minor crowded teeth. The scans were captured in a normal head position, and the coordinates of 21 important cephalometric landmarks were identified using Slicer 4.10.2 software. Manual affine transformation of all landmarks was used to transfer medical image coordinates (Digital Imaging and Communications in Medicine [DICOM] or Right-Anterior-Superior [RAS] systems) to Cartesian universal coordinates. Intraclass correlation coefficients (ICC) and Bland-Altman (BA) plots were used to assess inter- and intra-examiner reliability (ICC = 0.961-1.000, BA mean errors = -0.1 mm). Important cephalometric measurements were compared to the most relevant and recent study with a sample size of 200. Most measurements showed no statistical difference (one-sample t-test, p > 0.05). Independent samples t-tests revealed that there was no statistically significant difference in the X and Y axes; however, most mean coordinates between men and women in the Z-axis coordinates were statistically significant. Consequently, 3D cephalometric templates were generated separately for adult Thai men and women using landmark coordinates. Although they are available for all disciplines at no cost through QR codes, these templates should be used with care, especially for the upper and lower incisor angulation. The application and future development of each specialty are also described here.

Prevalence of Ponticulus Posticus and Migraine in 220 Orthodontic Patients: A Cross-Sectional Study

BACKGROUND

Ponticulus posticus (PP) is a medical term that describes an anomaly of the atlas (C1), which has a complete or partial bone bridge over the vertebral artery (VA) groove. The purpose of the study is to estimate the prevalence of PP in patients with a diagnosis of migraine.

METHODS

Cone beam CT (CBCT) scans (n = 220) were reviewed for the detection of PP in the University "G. D'Annunzio" of Chieti in the Department of Medical, Oral and Biotechnological Sciences. The sample included 220 Italian patients between 18 and 87 years. Pearson chi-square analysis (p < 0.05 and 95% CI) was used to establish an association between migraine and PP.

RESULTS

The present study found a prevalence of PP of 20.9% and a prevalence of migraine of 12.272%. The association between migraine and PP was confirmed by the chi-square statistic, since the p-value was 0.008065 (significant at p < 0.05). PP was more frequent in the migraine without aura group, without a statistical difference relative to the migraine with aura group.

CONCLUSIONS

The study concluded that PP is positively associated with migraine.

Assessment of thin bony structures using cone-beam computed tomography

OBJECTIVES

To investigate the validity and reliability of marginal bone level measurements on cone-beam computed tomography (CBCT) images of thin bony structures using various reconstruction techniques, two image resolutions, and two viewing modes.

MATERIALS AND METHODS

CBCT and histologic measurements of the buccal and lingual aspects of 16 anterior mandibular teeth from 6 human specimens were compared. Multiplanar (MPR) and three-dimensional (3D) reconstructions, standard and high resolutions, and gray scale and inverted gray scale viewing modes were assessed.

RESULTS

Validity of radiologic and histologic comparisons were highest using the standard protocol, MPR, and the inverted gray scale viewing mode (mean difference = 0.02 mm) and lowest using a high-resolution protocol and 3D-rendered images (mean difference = 1.10 mm). Mean differences were significant (P < .05) at the lingual surfaces for both reconstructions, viewing modes (MPR windows), and resolutions.

CONCLUSIONS

Varying the reconstruction technique and viewing mode does not improve the observer's ability to visualize thin bony structures in the anterior mandibular region. The use of 3D-reconstructed images should be avoided when thin cortical borders are suspected. The small difference when using a high-resolution protocol is unjustified due to the higher radiation dose required. Previous studies have focused on technical parameters; the present study explores the next link in the imaging chain.

Machine Learning Analysis of the Anatomical Parameters of the Upper Airway Morphology: A Retrospective Study from Cone-Beam CT Examinations in a French Population

The objective of this study is to assess, using cone-beam CT (CBCT) examinations, the correlation between hard and soft anatomical parameters and their impact on the characteristics of the upper airway using symbolic regression as a machine learning strategy. Methods: On each CBCT, the upper airway was segmented, and 24 anatomical landmarks were positioned to obtain six angles and 19 distances. Some anatomical landmarks were related to soft tissues and others were related to hard tissues. To explore which variables were the most influential to explain the morphology of the upper airway, principal component and symbolic regression analyses were conducted. Results: In total, 60 CBCT were analyzed from subjects with a mean age of 39.5 ± 13.5 years. The intra-observer reproducibility for each variable was between good and excellent. The horizontal soft palate measure mostly contributed to the reduction of the airway volume and minimal section area with a variable importance of around 50%. The tongue and the position of the hyoid bone were also linked to the upper airway morphology. For hard anatomical structures, the anteroposterior position of the mandible and the maxilla had some influence. Conclusions: Although the volume of the airway is not accessible on all CBCT scans performed by dental practitioners, this study demonstrates that a small number of anatomical elements may be markers of the reduction of the upper airway with, potentially, an increased risk of obstructive sleep apnea. This could help the dentist refer the patient to a suitable physician.

Three-dimensional evaluation using CBCT of the mandibular asymmetry and the compensation mechanism in a growing patient: A case report

Background

This case report aims to evaluate the development and the compensation mechanisms of the mandibular asymmetry in a growing male patient using cone beam computed tomography (CBCT). In this case, the menton deviated on the right, a sporadic condition, which may be the consequence of a disorder in the mandibular growth.

Case presentation

The young male patient was treated with rapid palatal expander (RPE) and Fränkel functional regulator III (FR-3). The initial CBCT was acquired at the beginning of therapy when the patient was 8 years old, and the final CBCT was developed at the end of the treatment when the patient was 12 years old. The patient's CBCT was performed with the head oriented according to the Natural Head Position (NHP); the NHP is a physiological and reproducible posture defined for morphological analysis. The 3D image of the cranium was oriented in the Dolphin software according to NHP posture, and cephalometric measurements were taken in the software's frontal, laterolateral right and left, posteroanterior, and submentovertex views. The therapy lasted 3.8 years and ended with significant regression of the mandibular asymmetry from moderate grade (4.2 mm) to slight grade (1.3 mm).

Conclusion

The literature shows that the left hemi-mandible has grown more than the right side, which affirms that in case of deviation of the menton >4 mm, the bone volume increases on the non-deviated side.

Effect of field of view (FOV) positioning and shielding on radiation dose in paediatric CBCT

OBJECTIVE

To investigate the effect of two different large field of view (FOV) positions in the vertical dimension and shielding (thyroid collar and eyeglasses) on the effective dose and the local doses of various sites of the craniofacial complex.

METHODS

Organ doses and effective doses were calculated based on the measured doses using 27 pairs of thermoluminescent dosemeters in a paediatric tissue-equivalent of a 10-year-old anthropomorphic phantom. The large FOV of the 3D Accuitomo F170 CBCT scanner was used to image parts of the craniofacial complex. Six protocols were performed: (A) cranial position without shielding; (B) cranial position with shielding; (C) caudal position without shielding; (D) caudal position with shielding, (E) similar to C with 3600 rotation and (F) similar to D with 360° rotation. Measurements were obtained in duplicate, and the relative δ value (%) was applied to compare the average doses between the protocols.

RESULTS

Changing the FOV position from cranial to caudal without using shielding resulted in an increase of the effective dose of 18.8%. Use of shielding in the caudal position reduced the dose by 31.6%. Local absorbed dose of the thyroid had the most relevant impact on calculation of the effective dose, followed by oesophagus, bone marrow and bone surfaces, especially when comparing the different protocols.

CONCLUSIONS

Application of shielding devices for thyroid in combination with a most caudal positioning of FOV led to the lowest local absorbed doses as well as the effective dose in a child phantom model.

Evaluation of the dosimetry and centralization of scout-view function in CBCT

This study evaluated the centralization of the region of interest (ROI) in acquisition of the CBCT images, when the freely positionable scout-view (SV) function is applied. Additionally, the dosimetry of the acquired images was assessed in the SV function alone as well as in complete tomographic image in two different fields of view (FOV) (50x50 and 78x150mm). A three-location device was created to accommodate the dosimeters and the specimens, in the right, middle and left location during image acquisition. For dose assessment, thermoluminescent dosimeters were irradiated within the FOV and analyzed in a portable reader. For ROI evaluation, three specimens of gutta-percha stick were placed on the same device and the CT scans were acquired (CBCT OP 300 Maxio device, 90kV, 13mA, 85 µm voxel size, FOV of 50X50mm), with and without the SV, in three positions (3-9, 1-7 and 5-11 o’clock), simulating different regions of the mouth. Two image evaluations were performed, an objective and subjective. There was a slight percentage increase (1.36% to 1.40%) of the radiation dose with the use of SV. The distances were significantly greater in the images acquired without SV (p < 0.05). Every image obtained with SV was classified as being at the FOV’s center. In conclusion, the results demonstrated that SVs function is effective to centralize the ROI in the FOV, increasing the scan precision and avoiding repetitions due to positioning errors.

Bone Modifications Induced by Rapid Maxillary Expander: A Three-Dimensional Cephalometric Pilot Study Comparing Two Different Cephalometric Software Programs

Cone-beam computed tomography (CBCT) allows for more accurate 3D study of the craniofacial region and the development of a very precise treatment plan. The present pilot study aims to evaluate the skeletal outcomes of the rapid maxillary expander (RME) on the sagittal, transverse and vertical planes in growing patients subjected to CBCT at T0 and T1, and to compare the results from two different programs. The effects of the RME are monitored in 11 patients who were subjected to CBCT at T0, before the expansion, and at T1, 6 months after the end of the RME therapy. The results obtained are evaluated using two programs: Simplant and Delta-Dent. All of the analyses were performed by the same operator. Both programs reported statistically significant differences between the pre- and post-expansion values of the parameters on the transverse plane. On the vertical plane, only posterior facial height showed a statistically relevant variation. Both programs underlined a discrepancy between the pre- and post-expansion infraorbital and mental foramina distance values; however, this difference was considered statistically significant by Delta-Dent, and not by Simplant. CBCT is a reliable and effective tool for orthodontic diagnosis and treatment planning. Both of the evaluated programs are efficient in tridimensional cephalometric analysis.

Are preoperative CT parameters predictive for the outcome of septoplasty?

Background

Despite successful septoplasty surgery, some patients still complain of nasal obstruction (NO).

Aim

Our aim in the present study is to determine whether preoperative computed tomographic (CT) parameters have prognostic significance for the success of septoplasty.

Material and Methods

Retrospective data from 61 patients in a secondary care hospital who had undergone septoplasty met the inclusion and exclusion criteria. The effects of demographic and preoperative CT parameters (internal nasal valve [INV], external nasal valve area, angle of septal deviation, choana area, aperture pyriformis area, high septal deviation [HSD], transverse diameter of midnose, anterior/posterior deviation, concha and meatus diameter [superior, middle, inferior]) were studied in relation to the change in NOSE scores and the success of surgery.

Results

Of the 61 patients studied, 31 were male (51%) aged 18-55 years with a mean age ± SD (26.59 ± 9.41). It was found that the changes in NOSE scores were significantly different from each other (P < 0.01). Male gender, trauma history, moderate septal deviation, HSD, mucosal pathology, posterior deviation, bullous turbinate (right and left middle, right superior), and in the absence of allergy, paradoxical turbinate (right and left middle and superior), S-shaped deviation were found to have a significant correlation in the change of NOSE scores (P < 0.05). Age and internal valve differed with respect to outcome (P < 0.05). Variables in multiple linear regresion models of all parameters were found to be insignificant (P < 0.05).

Conclusion

Preoperative CT parameters are informative, but do not predict the postoperative success of septoplasty.

Comparison of the accuracy of 2D and 3D cephalometry: a systematic review and meta-analysis

Objectives

To compare the measurement of cephalometric parameters using 3D images obtained from CBCT to 2D images obtained from a conventional cephalogram.

Methods

An electronic literature search was conducted using PubMed, Embase, Web of Science, CNKI, CENTRAL, and the grey literature database of SIGLE (up to May 2021). The selection of the eligible studies, data extraction, and an evaluation for possible risk of bias (Quality Assessment of Measurement Accuracy Studies tool) were performed independently by two authors. Inconsistencies were judged by a third author. Statistical pooling, subgroup analysis, a sensitivity analysis and an evaluation of publication bias were performed using Comprehensive Meta-Analysis (version 2.2.064, Biostat, Englewood, NJ).

Results

A total of eight articles were eligible for final meta-analysis. The differences in two of the skeletal measurement parameters [Ar(Co)-Gn, Me-Go] and one of the dental measurement parameters (U1-L1) were found to be statistically significant when using CBCT and conventional cephalograms (P = 0.000, P = 0.004, P = 0.000, respectively).

Conclusions

CBCT can be used as a supplementary option to support conventional cephalometric measurements. In clinical situations in which three-dimensional information is required, patients can benefit from CBCT analysis to improve diagnosis and treatment planning.

Impact of thyroid gland shielding on radiation doses in dental cone beam computed tomography with small and medium fields of view

OBJECTIVE

The purpose of this study was to evaluate the impact of thyroid gland shielding on radiation doses in dental cone beam computed tomography (CBCT) with small and medium fields of view (FOVs).

STUDY DESIGN

Six CBCT protocols were investigated by exposing an adult anthropomorphic male phantom head without and with thyroid shielding, using 4 small (4 × 5 cm) and 2 medium (10 × 6 cm) FOVs. Twenty metal oxide semiconductor field-effect transistor dosimeters were placed in the phantom head to measure absorbed doses and calculate equivalent doses at 11 sites. Effective doses were calculated based on the tissue weighting factors in International Commission on Radiological Protection Publication 103. The data were analyzed using the independent samples t test.

RESULTS

Thyroid gland shielding led to significant equivalent dose reductions in many tissues for all protocols. Equivalent dose reductions to the thyroid were significant in all 6 protocols (P ≤ .037). Significant reduction depended on the FOV and ranged between 24.5% and 42.6% for the thyroid gland and 4.9% and 34.5% for other tissues and organs. Effective doses were significantly lower in all protocols (P ≤ .016).

CONCLUSIONS

Thyroid gland shielding protects the thyroid gland and other organs and should be utilized with all CBCT examinations where feasible.

Midpalatal Suture Density as a Function of Sex and Growth-Pattern-Related Variability via CBCT Evaluations of 392 Adolescents Treated with a Rapid Maxillary Expander Appliance

Background and objectives. This paper aimed to evaluate the changes in mean bone density values of the midpalatal suture (MPS) in 392 young patients treated with a rapid palatal expander (RPE) appliance, depending on sex and vertical and sagittal skeletal patterns. Materials and Methods. Evaluations were performed using a low-dose protocol for cone beam computed tomography scans at T0 (preoperative) and T1 (1 year after the beginning of the therapy). The region of interest was used to calculate bone density in Hounsfield units (HU) for the area between the maxillary incisors. Results. CBCT scan data of 196 females and 196 males (mean age of 11.7 years) showed homogeneous and similar density values of the MPS at T0 (550.17–563.70 HU) and T1 (541.92–553.85 HU). Class III skeletal individuals showed significantly higher BD than the Class II group at T0, but not at T1. Females showed significant and substantially higher BD than males at T0 and T1. No significant differences were found between the other groups and between the two time points in terms of the bone density values of the MPS. Conclusions. Females and the Class III group showed significantly higher bone density values than males and Class II, respectively. No statistically significant differences were found from T0 to T1 in any groups, suggesting that a similar rate of suture reorganization occurs after the use of an RPE, causing reorganization and bone deposition along the MPS.

Assessments of Prevalence of Ponticulus Posticus, Atlas Posterior Arch Deficiency, Sella Turcica Bridging, Maxillary Canine Impaction, and Associations Among Them in 500 CBCTs of Italian Orthodontic Patients

Background: The ponticulus posticus (PP) is an important anomaly of the atlas (C1 vertebra) with a complete or partial bone bridge that transforms the groove of the vertebral artery (VA) into a canal (arcuate foramen). The aim was to retrospectively determine prevalence of PP evaluating morphological features and the possible association with other dentoskeletal anomalies in the midface and neck area such as maxillary canine impaction (MCI), atlas posterior arch deficiency (APAD), and sella turcica bridging (SB).

Methods: This study was conducted in the Department of Medical, Oral and Biotechnological Sciences of the University “G. D'Annunzio” in Chieti. The detection of PP was performed on 500 patients with cone beam CT (CBCT) images (6 to 87 years).

Results: Analysis revealed the presence of uni- and bi-lateral PP in 110 patients (22%): 24 (4.8%) patients with bilateral complete PP, 12 (2.4%) patients with complete PP on the left, 6 (1.2%) patients with complete PP on the right, 8 (1.6%) patients with complete PP on the right and partial PP on the left, 6 (1.2%) patients with complete PP on the left and partial PP on the right, 26 (5.2%) patients with partial bilateral PP, 18 (3.6%) patients with partial left PP, and 10 (2%) patients with partial PP on the right. The Chi-squared statistic confirmed that there are significant associations between MCI and PP (p = 0.020) and between SB and MCI (p &lt;0.00001). No correlation between chronological age and presence of the PP (p = 0.982), between chronological age and morphotypes of the PP (p = 0.779), between APAD and the PP (p = 0.0757), between SB and the PP (p = 0.111), and between APAD and MCI (p = 0.222) were found.

Conclusion: This observational study showed how bilateral partial variant and bilateral complete variant are the most represented morphotypes in all the age groups. The prevalence of MCI is positively associated with PP and with SB.

Diagnostic Accuracy of Cystic Lesions Using a Pre-Programmed Low-Dose and Standard-Dose Dental Cone-Beam Computed Tomography Protocol: An Ex Vivo Comparison Study

Background: This study aimed to analyze the diagnostic reliability of radiographic assessment of cystic lesions using a pre-set, manufacturer-specific, low-dose mode compared to a standard-dose dental cone-beam computed tomography (CBCT) imaging protocol. Methods: Forty pig mandible models were prepared with cystic lesions and underwent both CBCT protocols on an Orthophos SL Unit (Dentsply-Sirona, Bensheim, Germany). Qualitative and quantitative analysis of CBCT data was performed by twelve investigators independently in SIDEXIS 4 (Dentsply-Sirona) using a trial-specific digital examination software tool. Thereby, the effect of the two dose types on overall detectability rate, the visibility on a scale of 1 (very low) to 10 (very high) and the difference between measured radiographic and actual lesion size was assessed. Results: Low-dose CBCT imaging showed no significant differences considering detectability (78.8% vs. 81.6%) and visibility (9.16 vs. 9.19) of cystic lesions compared to the standard protocol. Both imaging protocols performed very similarly in lesion size assessment, with an apparent underestimation of the actual size. Conclusion: Low-dose protocols providing confidential diagnostic evaluation with an improved benefit–risk ratio according to the ALADA principle could become a promising alternative as a primary diagnostic tool as well as for radiological follow-up in the treatment of cystic lesions.

Efficiency of advanced-PRF usage in the treatment of alveolar cleft with iliac bone graft: A retrospective study

The aim of this study was to evaluate the efficiency of a new alveolar bone grafting protocol using advanced-PRF (a-PRF) by comparing the volumes of newly formed bone after a bone graft combining autogenous iliac crest bone with either PRF or a-PRF. Patients presenting with unilateral or a bilateral alveolar cleft were included retrospectively in two groups: one group was grafted using cancellous iliac crest bone with PRF (PRF group), whereas for the other group the same procedure was followed using a-PRF (a-PRF group). CBCT scans were performed 3 months preoperatively and 6 months postoperatively. The volume of newly formed bone was measured by subtracting the postoperative cleft volume from the preoperative cleft volume. The mean volume of newly formed bone was compared between the two groups using Student's t-test. Twenty-four patients were included, with 12 allocated to each group. Forty-eight CBCT scans were analyzed. The mean volume of newly formed bone was 0.29 (±0.09) cm³ in the a-PRF group, versus 0.20 (±0.08) cm³ in the PRF group (Student's t-test, p = 0.024). The percentage of newly formed bone was 60.4 (±10.4) % in the a-PRF group versus 51.4 (±18.4) % in the PRF group (Student's t-test, p = 0.165). Our study demonstrated improved bone regeneration in the a-PRF group. While bearing in mind the limitations of this study, the a-PRF procedure should be adopted in cleft bone grafting whenever possible.

Indications for 3-D diagnostics and navigation in dental implantology with the focus on radiation exposure: a systematic review

Background

Dental implants are a common restorative method used to replace missing teeth. Implant placement techniques guided by three-dimensional imaging and navigation are becoming more widely available.

Objective

The present review focused on the following questions: 1. What are the advantages and disadvantages of 2-D versus 3-D imaging in dental implantology? 2. What are the advantages and disadvantages of freehand implant placement in comparison with navigation-guided implant placement?

Methods

A systematic review was performed, based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. The following libraries were searched for relevant literature: PubMed, Embase, Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF) Online, and the Cochrane Library. The risk of bias was assessed using the Scottish Intercollegiate Guidelines Network (SiGN) checklist. A total of 70 studies were included after screening, and the evidence from these was gathered for review.

Results

Three-dimensional imaging is advantageous in terms of image quality, and it provides a distortion-free evaluation of the implant site. However, it is also associated with higher costs and increased radiation exposure. Dynamic and static navigation are equal in accuracy and are both more accurate compared with the freehand method. No benefit in terms of implant survival could be demonstrated within the first 5 years for any specific method.

Discussion

A panoramic X-ray with a reference body often provides sufficient imaging and is the primary method for two-dimensional imaging. Cone beam computed tomography with low-dose protocol settings should be used if three-dimensional imaging is needed. Navigational support should be considered in the event of especially complex cases.

Conclusion

The guidance technique used for implant placement should be decided on an individual basis. With the increasing availability of three-dimensional imaging, there should also be an increase in awareness of radiation exposure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-021-00328-9.

Could implant position influence the peri-implant parameters in edentulous mandibles of diabetics rehabilitated with overdentures? A split-mouth randomized study

This randomized controlled trial assessed the impact of crestal level position of implants installed in type 2 diabetes mellitus (T2DM) patients rehabilitated with overdentures. Twenty-two mandibular edentulous T2DM patients were submitted to implant placement for retention of an overdenture. By means of a split-mouth design, two implants were installed: one at supracrestal level (SL) and one at crestal level (CL). Clinical, immunoenzymatic and tomographic analyses were performed at prosthesis placement (baseline) and after 6, 12 and 24 months following implant loading. Increased peri-implant probing depths were detected in CL implants when compared with SL implants at all time-points (baseline P=0.047; 6 months P=0.014; 12 months P=0.027; 24 months P=0.036). Indeed, augmented clinical attachment levels were also detected in CL implants when compared with SL implants at all time-points (baseline P=003; 6 months P=0.045; 12 months P=0.029; 24 months P=0.026). CL implants demonstrated increased amounts of interleukin-6 (IL-6) at 6 months (P=0.043) and higher IL-17 (P=0.021), IL-21 (P=0.034) and tumour necrosis factor alpha (TNF-α) concentrations (P=0.030) at 24 months in comparison with SL implants. CL group revealed enhanced bone loss from baseline to 6 (P=0.032), 12 (P=0.043) and 24 months (P=0.028) when compared with SL. In conclusion, this study showed that implants placed supracrestally in T2DM patients rehabilitated with overdentures demonstrated lower bone loss and better clinical parameters with beneficial modulation of peri-implant immunoinflammatory biomarkers when compared with implants positioned at crestal level.

Evaluation of various low-dose cone-beam computed tomography protocols in the diagnosis of specific condylar defects

INTRODUCTION

This study aimed to determine the identifiability and measurement accuracy of defined bony defects of the temporomandibular joint (TMJ) in cone-beam computed tomographies, depending on different milliampere-second (mAs)-reduced protocols.

METHODS

Defined artificial defects were prepared on 30 condyles from 15 intact pig heads, with a maximum of surrounding soft tissue preserved. Three-dimensional imaging was performed using ProMax 3D Mid (Planmeca, Helsinki, Finland). The scan protocol with maximum resolution and without mAs-reduction was defined as control. Twenty-six mAs-reduced imaging protocols were analyzed by 1 examiner regarding the protocol-specific measurement accuracy. Defect depth (DD) was divided into 3 categories: I, <2 mm; II, 2-3 mm; and III, >3 mm. The protocol-specific sensitivity and specificity were evaluated in relation to localization and defect size as determined from the results of 3 examiners.

RESULTS

There was a significant difference from the control protocol in DD measurement in 8 mAs-reduced protocols, P <0.001-0.027. In most protocols, there was no significant difference in measurement accuracy concerning defect size and localization. The mean sensitivity reached values between 93.3% and 98.6% and differed significantly among protocols (P = 0.002). The mean specificity amounted to 97.0%-98.1% and did not differ among protocols (P = 0.462). The specificity of DD III (99.1%) was higher than DD I (97.7%) and DD II (97.1%). There was a significant difference in specificity and sensitivity concerning defect localization (P <0.001).

CONCLUSIONS

This study showed that mAs-reduced cone-beam computed tomographies protocols are suitable for the analysis of defined osseous TMJ defects. When 3-dimensional TMJ imaging is indicated because of potential erosive defects, validated mAs-reduced scan protocols should be applied instead of high-definition protocols.

Buccal bone defects and transversal tooth movement of mandibular lateral segments in patients after orthodontic treatment with and without piezocision: A case-control retrospective study

INTRODUCTION

This study aimed to compare the extent of buccal bone defects (dehiscences and fenestrations) and transversal tooth movement of mandibular lateral segments in patients after orthodontic treatment with and without piezocision in cone-beam computed tomography and digital dental models.

METHODS

The study sample of this study consisted of cone-beam computed tomography scans and digital dental models taken before (T0) and after (T1) orthodontic treatment of 36 patients with moderate mandibular anterior crowding. The experimental group consisted of 17 patients that had piezocision performed at the beginning of treatment with the goal of accelerating tooth movement, which was compared with 19 patients who did not receive piezocision. The measurement of bone defects, buccolingual inclination, and transversal distances of the tooth in the mandibular lateral segments (mandibular canines, premolars, and first molars) were evaluated at baseline and at the end of the orthodontic treatment.

RESULTS

Overall, an increase in dehiscences, buccal inclination, and arch width from T0 to T1 was observed in both groups, but no statistically significant difference was found between groups. A significant increase in fenestrations from T0 to T1 was observed only for the canines in the experimental group. No statistically significant association was found between the increase of dehiscences and the amount of buccolingual inclination or transversal width changes. However, the changes in transversal width were statistically significantly associated with the increase in buccal inclination at the canines, first and second premolars.

CONCLUSIONS

No significant differences were found in buccal dehiscences and transversal tooth movement (buccolingual inclination and arch width) of mandibular lateral segments between patients after orthodontic treatment with and without piezocision. Dehiscences, buccal inclination, and arch width significantly increased from T0 to T1 in both groups.

Dose Reduction in Dental CT: A Phantom Study With Special Focus on Tin Filter Technique

OBJECTIVE. The purpose of this study was to determine in a phantom the dose exposure of different dental 3D sectional imaging methods (CT and cone-beam CT [CBCT]) and different CT protocols. The aim was to establish optimal protocols with the lowest possible dose and diagnostically high image quality with special consideration given to tin prefiltration. MATERIALS AND METHODS. Dose was determined with thermoluminescence detectors at 20 different measuring points on an anthropomorphic phantom. Eight different CT protocols with and without tin filtering were compared with iterative reconstruction methods and a standard CBCT protocol. Objective and subjective image evaluations and a figure-of-merit analysis of the image data were performed by radiologists and maxillofacial surgeons. RESULTS. The determined dose-length products of the nine examinations were 5.0-111.9 mGy · cm with a calculated effective whole body dose of 20.7-505.9 μSv. Cone-beam CT was in the upper midfield with an effective dose of 229.3 μSv. On the basis of dose, objective image quality, and clinical evaluation results, tin filter protocols performed best. Protocols with higher doses were significantly less useful in the figure of merit comparison but because of their detailed bony representation are particularly necessary to answer certain questions about trauma and tumors. CONCLUSION. The use of tin filtering can reduce dose in dental CT examinations, compared with standard low-dose examinations, while maintaining good image quality. The dose performance is significantly inferior even to that of a cone-beam CT examination. High-dose protocols are necessary only for certain questions.

Effective doses of dental cone beam computed tomography: effect of 360-degree versus 180-degree rotation angles

OBJECTIVES

The aims of this study were to compare radiation absorbed dose (AD) and effective dose (ED) to tissues from cone beam computed tomography (CBCT) scans with 360-degree versus 180-degree rotations with use of different fields of view (FOV), to compare EDs calculated from measured ADs versus dose area product (DAP) values, and to compare doses to the lens of the eye (LOE) from different scan parameters.

STUDY DESIGN

ADs for each protocol were measured in tissues, including the LOE, by using an anthropometric phantom. EDs were calculated on the basis of dosimetry (EDm) and DAP values (EDd). Dose differences were determined with analysis of variance (ANOVA).

RESULTS

ADs and EDs were substantially lower for 180-degree rotation scans compared with 360-degree rotation scans (P < .01). Remainder tissues had the greatest effect on effective dose for most FOVs. Doses were generally lower with small FOVs compared with large FOVs. Most EDm values were lower than EDd values in large FOVs but higher in small FOVs. Differences in EDm and EDd were variable and unpredictable. LOE doses were smaller with the 180-degree scans and smaller FOVs.

CONCLUSIONS

Radiation doses were generally lower with 180-degree rotation scans and smaller FOVs. These parameters should be used for CBCT acquisitions, whenever possible, and should be made available in all units.

CONE BEAM CT IN DENTAL IMPLANT PLANNING: HOW CLOSE ARE PATIENT DOSIMETRY RESULTS WITH DATA FROM PHANTOM STUDIES FOUND IN LITERATURE?

Advantages of Cone Beam Computed Tomography (CBCT) include high-quality 3D imaging and reduced radiation exposure with relatively low cost. In this study, patient radiation exposure in CBCT implant planning dentistry was measured in terms of Kerma Area Product (KAP). Data were obtained from 217 CBCT scans on 168 individuals using a CS9300 Carestream system. Scans were made using 80-90 kVp, 4-5 mA, 8 and 13.3 s exposure time (depending on voxel size) and a fixed field of view (FOV) of 10 × 10 cm2 (medium). Mean KAP was estimated using two voxel sizes 180 × 180 × 180 μm3 and 200 × 200 × 200 μm3 and found to be 399 and 314 mGycm2, respectively. Corresponding KAP values found in literature ranged between 210 and 2140 mGycm2. Mean E was estimated using conversion coefficient factors found in literature, according to FOV size and tube voltage value and found to range between 24 and 161 μSv.

Effect of micro-osteoperforation on the rate of canine retraction: a split-mouth randomized controlled trial

Background

Among the recent modalities introduced to accelerate orthodontic tooth movement (OTM) is micro-osteoperforations (MOPs), in other words, bone puncturing. The aim of this split-mouth trial was to investigate the effects of MOPs on the rate of OTM.

Methods

Eighteen patients requiring bilateral first premolar extraction and upper canine retraction with maximum anchorage were enrolled in this study. Immediately before canine retraction, three MOPs were randomly allocated to either the right or left sides. MOPs were performed using a mini-screw (1.8 mm diameter, 8 mm length) distal to the canine. Canine retraction continued for 4 months. Data were collected from monthly digital models, in addition to pre- and post-retraction maxillary CBCT images. The primary outcomes were the rate of canine retraction per month and the total distance moved by the canines. The secondary outcomes were the effect of MOPs on anchorage loss, canine root resorption, and pain.

Results

The mean rate of canine retraction in both sides was 0.99 ± 0.3 mm/month. The total distance moved by the canine cusp tip was greater in the MOP than the control side (mean difference 0.06 ± 0.7 mm), which was statistically insignificant (P > 0.05(. The total distances moved by the canine center and apex were significantly greater in the MOP than the control side (mean difference 0.37 ± 0.63 mm (P < 0.05) and 0.47 ± 0.56 mm (P < 0.01) respectively). Insignificant differences were detected regarding anchorage loss and root resorption between both sides (P > 0.05). Mild to moderate pain was experienced following the MOP procedure, which rapidly faded away within 1 week.

Conclusions

Micro-osteoperforations were not able to accelerate the rate of canine retraction; however, it seemed to facilitate root movement.

Evaluation of mandibular calcification on 3D volume images

Objectives

Bone and soft-tissue calcifications are often coincidentally diagnosed on digital panoramic radiographs (DPRs). As the use of three-dimensional (3D) images has increased in the past decade for diagnostics in the mandibular region, we evaluated 3D volume images derived from 2D panoramic images to determine if this method is suitable for early detection of calcifications in this region.

Methods

In this study, three investigators retrospectively and independently evaluated 822 DPRs. If one or more calcifications were present, the 3D volume image from that patient was retrospectively evaluated to confirm the incidental findings. A radiographic system with a low-dose mode and a high-resolution 3D-image function was used. The investigators focussed on the most common calcifications, including tonsilloliths (TL), idiopathic osteosclerosis (IO) of the mandible, carotid artery calcifications (CAC), calcified submandibular lymph nodes (hereafter, CSL), and sialoliths of the submandibular salivary gland (SSG).

Results

One or more calcifications were identified in 415 (50.5%) DPRs. In total, 718 calcifications were detected, 30.2% of which were TL, 16.3% IO, 11.3% CAC, 8.8% CSL, and 1.7% SSG. Only 287 (39.97 %) of the calcifications were confirmed on 3D volume images; of these, 29.2% were TL, 58.5% IO, 0.2% CAC, and 1.4% SSG. No CSLs were detected.

Conclusions

Not all areas shown on the DPRs were visible in the retrospectively obtained 3D volume images. Whereas DPRs are used to diagnose calcifications such as IO, TL, SSG, CAC, and CSL, the 3D volume images were only useful for confirming the existence of IO, TL, and SSG calcifications.