Preoperative Cone-beam Computed Tomography Scans Research Articles

Real-Time Three-dimensional Dynamic Navigation for Post Space Preparation in Root Canal-Treated Teeth: An In vitro Study

IntroductionThe aim of this study was to investigate the feasibility of a real-time three-dimensional dynamic navigation system (3D-DNS) for post space preparation (PSP) in root canal-treated teeth and to compare the accuracy and efficiency of 3D-DNS to freehand (FH) for PSP. MethodsFifty-four maxillary molars were divided into two groups: 3D-DNS (n = 27) and FH group (n = 27). Cone beam computed tomography (CBCT) scans were taken preoperatively and postoperatively. The drilling path for the PSP was virtually planned in the preoperative CBCT scan in the X-guide software (X-Nav Technologies, Lansdale, PA). For the 3D-DNS group, the PSP drilling was conducted under dynamic navigation. The 3D deviations and angular deflections were calculated. The residual dentin thickness (RDT) was determined after PSP. The operation time and the total number of mishaps were recorded. Shapiro-Wilk, t-test or Mann-Whitney rank sum, weighted Cohen's kappa, and Fisher exact tests were used (P < .05). ResultsThe PSP was completed in all samples (54/54). The 3D-DNS was more accurate than the FH, with significantly fewer 3D deviations and angular deflections (all, P < .05). The 3D-DNS required less operating time than the FH (P < .05). For the 3D-DNS, no teeth had RDT < 1 mm, whereas 6/27 in the FH showed RDT < 1 mm after the PSP. There was no difference in the total number of mishaps (P > .05). ConclusionWithin the limitations of this in vitro study, the 3D-DNS is feasible for PSP. The 3D-DNS improved the accuracy and efficiency of PSP. The dynamic navigation system can potentially become a safe and reliable technology for PSP.

Comparative Determination of Working Length by Electronic Apex Locator, Digital Radiography, and Cone-beam Computed Tomography: An In vitro Study

Abstract Purpose: The aim of the present in vitro study is to evaluate and compare the working length determination by electronic apex locator, digital radiography radio visio graphy (RVG), and cone-beam computed tomography (CBCT). Materials and Methods: Sixty extracted teeth were collected, cleaned, and stored. Preoperative digital radiograph and CBCT scans of all the samples were taken. K-file was placed into root canal after access cavity preparation. According to the method used, different groups were made to determine the working length. Group I: Actual working length of each tooth was determined and kept as a control group. Group II: Each tooth working length was measured by electronic apex locator. Group III: Each tooth working length was measured by digital radiography (RVG). Group IV: Each tooth working length was measured by CBCT. Results: When compared with the actual working length by means of analysis of variance, the difference in mean working length calculated by electronic apex locator, RVG, and CBCT was found to be statistically significant (P = 0.001). Conclusions: Electronic apex locator is the most precise (96%) method for working length determination, followed by CBCT (94%). RVG was found to be a less accurate (93%) method in this study.

Nasal and maxillary sinus volume change in patients with obstructive sleep apnea after bimaxillary advancement surgery

The airway complex is modified by bimaxillary advancement surgery performed in patients suffering from obstructive sleep apnea (OSA). The aim of the present study is to analyse the volume of nasal and maxillary sinus after bimaxillary advancement surgery in patients suffering from OSA. The maxillary sinus and nasal complex of eighteen patients with OSA was measured through cone-beam computed tomography (CBCT) before and after they were treated with bimaxillary advancement surgery. Digital planning software was used to effectively measure the upper volume changes, as well as, statistical analysis of the results was performed.Methods Eighteen patients were diagnosed with OSA the severity of which was measured by the apnea hypopnea index and were selected and submitted to preoperative and postoperative CBCT scans. Afterwards, datasets were uploaded into therapeutic digital planning software (Dolphin Imaging) to measure the volume of the right and left maxillary sinus and nasal and maxillary sinus complex. Statistically analysis between preoperative and postoperative measures was performed by Student t-test statistical analysis.Results The paired t-test showed statistically significant volumetric reductions in the left maxillary sinus (p = 0.0004), right maxillary sinus (p < 0.0001) and nasal and maxillary sinus complex (p = 0.0009) after bimaxillary advancement surgery performed in patients suffering from OSA.Conclusion The results showed that bimaxillary advancement surgery reduces the maxillary sinus volume as well as, the fossa nasal and sinus complex volume.

Fractal analysis of the mandible cortical bone: correlation among fractal dimension values obtained by two processing methods from periapical radiograph and micro-computed tomography with cone-beam computed tomography.

The objectives of the present study were to assess Fractal Dimension (FD) values in the mandible cortical bone obtained from digital periapical radiographs (DPR), high-resolution microtomography (µCT), and cone-beam computed tomography (CBCT), by two processing methods: binarization (FD.b) and grayscale-based method (FD.f) and, finally, to identify the correlation among these values with other micro-architectural parameters. For this, a prospective study was conducted on 18 healthy individuals (mean age 23 ± 2.4years old) who underwent third molar extraction. Pre-operative CBCT scans were conducted, bone fragments were removed from the retro-molar region, and DPR and µCT were performed on those bone samples. FD.b and FD.f values were calculated using three parasagittal sections for CBCT, one image for DPR, and three sections for µCT. The 3D bone microarchitecture was analyzed in µCT (voxel size: 19µm). As a result, FD.b mean values of 1.55 ± 0.02 and 1.80 ± 0.01 were obtained for CBCT and µCT, respectively. Furthermore, FD.f mean values of 1.22 ± 0.12 for DPR, 0.99 ± 0.04 for CBCT, and 1.30 ± 0.07 for µCT were obtained. Both FD.b and FD.f values showed a good agreement. FD.f was negatively correlated with the standard deviation of the mean gray value (p = 0.003) for DPR and intra-cortical bone surface (p = 0.02) for µCT. In conclusion, image processing with or without binarization revealed different values for FD, although showing agreement. The grayscale-based method retrieved FD values correlated with the gray levels and the cortical porous network, which means that FD can be a valuable index for mandibular cortical bone evaluation. FD is associated with mineralization and microarchitecture. Nevertheless, there was no correlation between FD values obtained from low- (DPR) and high-resolution (µCT) X-ray modalities with FD obtained from the in vivo CBCT.

Novel Three-Dimensional and Non-Invasive Diagnostic Approach for Distinction between Odontogenic Keratocysts and Ameloblastomas.

Aim of this study was to demonstrate the diagnostic ability to differentiate odontogenic keratocysts (OKCs) from ameloblastomas (AMs) based on computed tomography (CT) or cone beam computed tomography (CBCT) scans. Preoperative CT and CBCT scans from 2004 to 2019 of OKCs and AMs were analyzed in 51 participants. Lesions were three-dimensionally (3D) assessed and Hounsfield units (HU) as well as gray scale values (GSV) were quantified. Calculated HU spectra were compared within the same imaging modalities using unpaired t-tests and correlated with participants characteristics by calculating Pearsons correlation coefficients. Within the CT scans, AMs had highly significantly higher HU values compared to OKCs (43.52 HU and 19.79 HU, respectively; p < 0.0001). Analogous, within the CBCT scans, AMs had significantly higher GSV compared to OKCs (-413.76 HU and -564.76 HU, respectively; p = 0.0376). These findings were independent from participants' gender and age, anatomical site, and lesion size, indicating that the HU- and GSV-based difference reflects an individual configuration of the lesion. HU and GSV spectra calculated from CT and CBCT scans can be used to discriminate between OKCs and AMs. This diagnostic approach represents a faster and non-invasive option for preoperative diagnosis of such entities and has potential to facilitate therapeutic decision making.

Does the Protrusion of Corticobasal Implants in the Maxillary Sinuses Affect Sinus Health? A Retrospective Study.

The aim of this retrospective study is to investigate the effect of corticobasal implant penetration in the nasal and maxillary sinuses on sinus health and implant survival rate in cases of severely atrophid ridges. This retrospective study was conducted on thirty patients with 172 implants who underwent corticobasal implant treatment between 2014 and 2018. Implants were divided into two groups according to the penetration depths (Group A, <4 mm; Group B, 4 mm). Inclusion criteria for the study included: (A) patients with severe maxillary ridge resorption with an immediately loaded corticobasal implant-supported prosthesis that showed implant protrusion inside the maxillary sinus on cone-beam computed tomography (CBCT); and (B) patients with a preoperative and postoperative follow-up CBCT scan using the same standard technique and machine. (C) Patients without any history of sinusitis before implant insertion patients who fulfilled the inclusion criteria were recalled for follow-up. The presence of sinus complications was clinically assessed according to the clinical practice guidelines for adult sinusitis of the American Academy of Otolaryngology-Head and Neck Surgery and Radiologically using CBCT. Moreover, patient satisfaction was evaluated using yes-or-no questions. The result was statistically analyzed using Fisher's Exact test. Despite the differences in implant penetration depths, no clinical signs of sinusitis were evident in any patient. One patient presented with transient epistaxis after the surgery, and 2 patients with nine implants revealed nonsignificant thickening of the sinus membrane radiologically (p = 0.055). All implants showed optimum bone-implant contact with a 100% survival rate. A significant relationship was reported between the thickness of the membrane and the patient's gender, hypertension, and smoking habits. (p = 0.001*, p = 0.002*, and p = 0.034*, respectively). Penetration of corticobasal implants in the maxillary sinus did not compromise the health of the maxillary sinus or implant survival rate. Limited posterior maxillary bony support and maxillary sinus pneumatization present challenges in implant dentistry and increase the possibility of implant protrusion inside the maxillary and nasal cavities. Hence, studying the effect of this protrusion on the maxillary sinuses' health and implant survival is highly significant.

Cone-Beam Computed Tomography Evaluation of Rotary MM Files vs Manual K Files in Primary Molars: An In Vitro Study.

Rotary instrumentation in pediatric dentistry is an emerging concept, thus this study was performed to evaluate the remaining dentine thickness (RDT), canal transportation, centering ability, quality of obturation using cone-beam computed tomography (CBCT), and the time efficiency of rotary versus manual instrumentation in mandibular second primary molars. Forty mandibular primary second molars (160 canals) were randomly and equally allocated to four groups. Instrumentation was done using K files in groups I and II; in each group, the obturation was done by two different obturation techniques; incremental technique and disposable syringe technique, respectively. MM rotary files (Innovative Material and Devices, Inc. [IMD], Shanghai, China) were used in groups III and IV; in each group, the obturation was done by incremental technique and disposable syringe technique. Preoperative and postoperative CBCT scans were performed and evaluated for the RDT, centering ability, canal transportation, and the canal filling quality, which was assessed as (underfill, optimal fill, and overfill). Instrumentation time was recorded for groups I and II collectively (manual instrumentation), and groups II and III collectively (rotary instrumentation). Statistical analysis was done using Chi-square, ANOVA, and post hoc Tukey tests, at p < 0.05). The MM rotary file removed a significantly less amount of dentine at all levels specifically at the middle section (p = 0.003). The canal transportation was significantly higher in the manual group at the cervical level (p = 0.022). In all sections, the rotary group had significantly higher values of centering ratio than the manual group (p < 0.05), which means a lower deviation of rotary instruments. For both types of files, there was no significant difference between different obturation techniques (p > 0.05). Instrumentation time was significantly lower in the rotary group (p < 0.001). Regarding the dentine removal and the shaping ability of MM files acceptable results were obtained; however, no significant difference between the different obturation techniques. Notable time efficiency was reported in the rotary files as well. The use of rotary files resulted in better conservation of tooth structure, better canal centering, and obturation quality as well as less canal transportation and less instrumentation time compared to manual K files.

Comparative Evaluation of Root Canal Transportation and Centering Ability in Curved Mesiobuccal Canals of Mandibular First Molars after Instrumentation with Different File Systems-An In vitro Study.

To assess the canal transportation and centering ability in the mandibular first molars' curved mesiobuccal canals after instrumentation with file systems XP endo Shaper, self-adjusting File (SAF), Hyflex EDM, Pro Taper NEXT, WaveOne Gold, and K files with the help of Cone-Beam Computed Tomography (CBCT). Ninety recently extracted mandibular first molars with mesiobuccal roots that had a 25-30 degree canal curvature were assessed. Following preoperative CBCT scans, teeth were allocated randomly to six experimental groups of fifteen. After preparation with XP endo Shaper, SAF, Hyflex EDM, Pro Taper Next, WaveOne Gold, and K files, post-instrumentation scans were taken using same parameters as pre operative scans. At 3 mm, 6 mm, and 9 mm from the apex, samples were assessed for canal transportation and centering ratio. Apical transportation was least for XP endo Shaper as compared to other groups except SAF and the results were statistically significant. K file showed the highest apical transportation toward the lateral wall of the root canal. XP endo Shaper was better in maintaining centering ability of middle and apical third of canal and SAF was better in maintaining centering ability of coronal third. In root canal preparation, least apical transportation and better centering ability with XP endo Shaper than other file systems compared. K file showed the highest transportation.

A Cadaver-based Comparison of Sleeve-guided Implant-drill and Dynamic Navigation Osteotomy and Root-end Resections

IntroductionThis study compared the accuracy and efficiency of fully guided static and dynamic computer-assisted surgical navigation techniques for osteotomy and root-end resection (RER). MethodsFifty roots from cadaver heads were divided into two groups: fully guided static computer-assisted endodontic microsurgery (FG sCAEMS) and dynamic computer-assisted endodontic microsurgery (dCAEMS) (all, n = 25). Cone-beam computed tomography scans were taken pre and postoperatively. The osteotomy and RER were planned virtually in the preoperative cone-beam computed tomography scan and guided using 3D-printed surgical guides in the FG sCAEMS and 3D-dynamic navigation system in the dCAEMS. The 2D and 3D deviations and angular deflection were calculated. The osteotomy volume, resected root length, and resection angle were measured. The osteotomy and RER time and the number of procedural mishaps were recorded. ResultsFG sCAEMS was as accurate as dCAEMS, with no difference in the 2D and 3D deviation values or angular deflection (P > .05). The osteotomy and RER time were shortened using FG sCAEMS (P < .05). The FG sCAEMS showed a greater number of incomplete RERs than dCAEMS. Osteotomy volume, RER angle, and root length resected were similar in both groups (P > .05). FG sCAEMS and dCAEMS were feasible for osteotomy and RER. ConclusionsWithin the limitations of this cadaver-based study, FG sCAEMS was as accurate as dCAEMS. Both FG sCAEMS and dCAEMS were time-efficient for osteotomy and RER.

D21. Failure Rates Based on Alveolar Cleft Size: An Analysis of the Critical Size Defect for rhBMP-2/DBM and Iliac Crest in Alveolar Bone Grafting

PURPOSE: Iliac crest bone graft (ICBG) is the standard of alveolar bone grafting (ABG). However, recombinant human bone morphogenetic protein(rhBMP-2) with demineralized bone matrix (DBM) has been proposed as an alternative. We aim to identify the critical size defect of failure rates for ICBG and rhBMP-2/DBM. METHODS: A retrospective review evaluated patients undergoing ABG from 2016-2022. Patients with genetic syndromes, bilateral clefts, and missing postoperative cone beam computed tomography (CBCT) were excluded. The 3-dimensional volumetric defect sizes were calculated using preoperative CBCT scans. The primary outcome was bony bridge formation based on postoperative imaging. Logistic regression was used to model graft failure rates and identify the maximal point, which defined the critical point. RESULTS: Among 148 patients screened, 62 were included who underwent ABG (ICBG: n=28; rhBMP-2/DBM: n=34). There was no significant difference in bridge formation between graft types. The critical point in failure rate was calculated to be 829.3mm3 and 857.8mm3 for rhBMP-2/DBM and ICBG, respectively. Upon Fisher-exact analysis, there were increased bridge failures in clefts greater than the critical point for both ICBG (p<0.001) and rhBMP-2/DBM (p=0.005). The critical point did not vary between graft types (p=0.772) CONCLUSION: Our findings identified a higher probability of graft failure beyond the predicted critical size defect for each respective bone graft. Clinicians can better counsel families of patients with larger defects with a higher probability of treatment failure using either ICBG or rhBMP-2/DBM.

Comparative evaluation of the effect of conventional and truss access cavities on remaining dentin thickness, canal transportation, and canal centering ability in mandibular molars using cone-beam computed tomography

Aim: To evaluate and compare the effect of conventional and truss access cavity preparations on remaining dentin thickness (RDT), canal transportation, and centering ability in mandibular molars using cone-beam computed tomography (CBCT). Methods: Ethical approval was obtained before the commencement of the study. Thirty extracted mandibular molars were selected, disinfected, and stored in normal saline. Preoperative CBCT scans were taken for all the samples and randomly divided into two groups. (n = 15). Group A; Conventional access preparation group; Group B; Truss access preparation group. Cleaning and shaping were performed with the mesiobuccal canal of all the samples. Postoperative CBCT scans were compared with preoperative CBCT scans to evaluate the RDT, canal transportation, and canal centering ability in mandibular molar with conventional and truss access cavity preparation. Results: Data obtained from CBCT were analyzed by independent sample t-test with the P < 0.05 and found that RDT was higher in Group A as compared to Group B at the 3 and 9 mm levels, whereas it was higher in Group B at 6 mm level in both the mesial and distal side, but it was statistically insignificant at 3, 6, and 9 mm level. Canal transportation was higher in Group B than in Group A, but it was statistically insignificant at 6 and 9 mm levels but statistically significant at 3 mm. Canal centering ability was higher in Group A than in Group B, but it was not statistically significant at 3, 6, and 9 mm levels. Conclusion: Regarding RDT and canal centering ability, there is no statistically significant difference at all levels. Both groups present a statistically significant difference at 3 mm from the apex when comparing canal transportation. This suggests that conventional access cavity preparation is better than truss access preparation to maintain original canal anatomy.

A completely digital workflow aided by cone beam computed tomography scanning to maintain jaw relationships for implant-supported fixed complete dentures: A clinical study

Statement of problemThe conventional workflow for the fabrication of implant-supported fixed complete dentures (IFCDs) is complex and makes it impossible to maintain jaw relationships. A fully digital workflow might solve this problem. PurposeThe purpose of this clinical study was to develop a completely digital workflow aided by a cone beam computed tomography (CBCT) scan for the fabrication of IFCDs and to evaluate the accuracy of this workflow with regard to the maintenance of jaw relationships. Material and methodsAll participants received a preoperative CBCT scan while wearing radiographic diagnosis dentures and occluding in the maximum intercuspal position. After the implant surgery, CBCT scanning, intraoral scanning, and stereophotogrammetry were performed to identify jaw anatomy, soft tissue, and the 3-dimensional (3D) locations of the implants, respectively. Then, all data were merged to transfer jaw relationships and generate digital casts to fabricate interim prostheses. A posttreatment CBCT scan was performed while the participants were wearing the interim prostheses and occluding in the maximum intercuspal position. The preoperative and postoperative jaw relationships were compared by CBCT cephalometric analysis. A meaningful and unacceptable difference was defined as 0.8 degrees and 2.4 degrees, respectively. ResultsSix participants (6 jaw relationships, 9 arches, and 58 implants) were included. All interim prostheses were stable and achieved symmetric occlusion after only minimal adjustment. A total of 18 angles were measured. Three angles revealed a meaningful minimal difference, and 1 angle revealed an unacceptable minimal difference. No prosthodontic complications were reported during the study. ConclusionsA completely digital workflow for fabricating IFCDs achieved sufficient accuracy for the maintenance of jaw relationships throughout the treatment.

Guided endodontics of calcified canals: The drilling path of rotary systems and intracanal dentin wear.

This study evaluated the drilling path (mm) and the dentin wear (mm3 ) of two instruments used during guided endodontic access. Twenty mandibular incisors with calcified canals were selected using cone-beam computed tomography (CBCT) and fixed in articulated models. Preoperative CBCT scans were performed in combination with intraoral scanning, and the images were reconstructed in the Blue Sky Bio software for access planning and printing the guides. The access cavity was drilled with 1.0-mm-diameter bur (DSP) and 0.8-mm-diameter bur (Munce). Postoperative CBCT was performed, and the images obtained preoperative and postoperative were superimposed for the analyses. Data were analysed by a t-test and linear regression (α=0.05). No difference was found in the drilling path (p= 0.422). However, the Munce bur had higher dentin wear than the DSP bur (p= 0.011). A positive linear correlation (R2 = 0.859) was found between the factors.

Horizontal guided bone regeneration on knife-edge ridges: A retrospective case-control pilot study comparing two surgical techniques.

Studies evaluating guided bone regeneration (GBR) on knife-edge ridges using absorbable membranes with staged approaches have reported various horizontal bone gains. This study compared the horizontal bone gain obtained via a conventional technique of GBR and a recently-reported technique. Bone loss during the healing process was also measured. Consecutive patients who underwent GBR on knife-edge ridges via a conventional technique (control group) or the Sausage Technique (test group) were included in this study. GBR was performed using a collagen membrane and deproteinized bovine bone mineral combined with an autogenous graft at a 1:1 ratio. Cone-beam computed tomography (CBCT) was performed preoperatively, postoperatively, and after the patient healed. Horizontal bone width was measured on CBCT images 2 mm apical from the top of the crest. The preoperative CBCT and posthealing CBCT were superimposed to calculate the bone gain after healing, and the preoperative and postoperative CBCT scans were superimposed to calculate the bone gain after surgery. Bone loss during healing was calculated by subtracting the width of the ridge after healing from the postoperative width. The mean horizontal bone gain was significantly lower in the control group (2.7 ± 1.8 mm; 83.2%) than in the test group (5.3 ± 2.3 mm; 216.8%) (p=0.003). The average horizontal bone loss between regeneration and implant placement was 0.9 mm in the control group (27.9%) and 2.1 mm in the test group (29.4%). While the absolute bone loss was significantly different (p=0.012), the percentage of bone resorption was not (p=0.608). The new technique resulted in significantly more bone gain than a conventional GBR technique. The rate of graft resorption during healing was stable regardless of the amount of grafted material.

Value of cone beam computed tomography for detecting bone invasion in squamous cell carcinoma of the maxilla

To determine the diagnostic value of cone beam computed tomography (CBCT) in detecting bone invasion in maxillary squamous cell carcinoma (MSCC). In this retrospective cohort study, preoperative CBCT scans were independently assessed by a single surgeon in imaging assessment 1 (IA 1) and by 1 surgeon with 2 dentists in consensus (IA 2) for the presence of bone invasion in MSCC. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, area under the receiver operating characteristic curve (AUC), and Cohen's κ were calculated. Histopathologic results of resection specimens served as the reference standard. Of 27 patients, 19 (70%) had proven bone invasion. IA 1 yielded 68.4% sensitivity, 75.0% specificity, 86.7% PPV, 50.0% NPV, 70.4% accuracy, and 0.717 AUC. All results of IA 2 were true-positive and true-negative, resulting in 100% sensitivity, specificity, PPV, NPV, accuracy, and AUC. The assessments differed in 6 cases. Interobserver κ was fair (0.38, 95% CI 0.04-0.72, P=.038). There was a significant association between CBCT detection of bone invasion and extent of surgical treatment (P=.006) CONCLUSIONS: The diagnostic accuracy of CBCT was high but observer-dependent. CBCT examination may be useful in surgical treatment planning.

Qualitative and quantitative assessment of condylar displacement after orthognathic surgery: A voxel-based three-dimensional analysis

PurposeThis study aimed to evaluate the morphometric changes in the position of the mandibular condyles before and after orthognathic surgery. MethodsA retrospective single-center cohort study was conducted and included patients with a presurgical (T1) and postsurgical (T2) Cone Beam computed tomography (CBCT). The primary predictor variable was the orthognathic surgical treatment. Pre-operative and post-operative CBCT scans were superimposed using voxel-based registration. Semitransparent overlays of the models of condylar regions at T1 and T2 were created for the qualitative analysis. The primary outcome variable was the quantitative displacement of condyles (CoR; CoL) analyzed in X, Y, Z axis and the 3D distances. Descriptive and bivariate statistical analysis was performed, setting α=0.05. ResultsThe study sample included 33 patients (mean age: 25.33±2.49 years) affected by skeletal class III malocclusion with or without skeletal asymmetry. The X-axis showed a mean movement of 0.25 ± 0.17 mm for CoR, and 0.52 ± 0.51 mm for CoL. The Y-axis showed a mean movement of 0.29 ± 0.2 mm for CoR, and 0.51 ± 0.8 mm for CoL. The Z-axis was 0.33 ± 0.2 mm for CoR, and 0.5 ± 0.49 mm for CoL. No statistically significant difference was calculated comparing the movement of condylar surface between asymmetric and not asymmetric patients (p = 0.26 for CoR; p = 0.13 for CoL). No statistically significant difference was found in intercondylar distance between T1 and T2 (p = 0.39). ConclusionNo statistically nor clinically significant condylar displacement are recorded in orthognathic surgery patients at 12 to 18 months of follow-up.

A semi-automatic approach for longitudinal 3D upper airway analysis using voxel-based registration.

To propose and validate a reliable semi-automatic approach for three-dimensional (3D) analysis of the upper airway (UA) based on voxel-based registration (VBR). Post-operative cone beam computed tomography (CBCT) scans of 10 orthognathic surgery patients were superimposed to the pre-operative CBCT scans by VBR using the anterior cranial base as reference. Anatomic landmarks were used to automatically cut the UA and calculate volumes and cross-sectional areas (CSA). The 3D analysis was performed by two observers twice, at an interval of two weeks. Intraclass correlations and Bland-Altman plots were used to quantify the measurement error and reliability of the method. The relative Dahlberg error was calculated and compared with a similar method based on landmark re-identification and manual measurements. Intraclass correlation coefficient (ICC) showed excellent intra- and inter-observer reliability (ICC ≥ 0.995). Bland-Altman plots showed good observer agreement, low bias and no systematic errors. The relative Dahlberg error ranged between 0.51 and 4.30% for volume and 0.24 and 2.90% for CSA. This was lower when compared with a similar, manual method. Voxel-based registration introduced 0.05-1.44% method error. The proposed method was shown to have excellent reliability and high observer agreement. The method is feasible for longitudinal clinical trials on large cohorts due to being semi-automatic.

A Comparative Analysis of the Piezoelectric Ultrasonic Appliance and Trephine Bur for Apical Location: An In Vitro Study.

To compare and contrast the accuracy of piezoelectric ultrasonic insert (PUI) and trephine bur (TB) osteotomy site preparation techniques for apical location. (1) Material and methods: A total of 138 osteotomy site preparations were randomly distributed into one of two study groups. Group A: TB technique (n = 69) and B: PUI technique (n = 69). A preoperative cone-beam computed tomography scan and an intraoral scan were performed and uploaded to implant-planning software to plan the virtual osteotomy site preparations for apical location. Subsequently, the osteotomy site preparations were performed in the experimental models with both osteotomy site preparation techniques and a postoperative CBCT scan was performed and uploaded into the implant-planning software and matched with the virtually planned osteotomy site preparations to measure the deviation angle and horizontal deviation as captured at the coronal entry point and apical end-point between osteotomy site preparations using Student’s t-test statistical analysis. (2) Results: The paired t-test found statistically significant differences at the coronal entry-point deviations (p = 0.0104) and apical end-point deviations (p = 0.0104) between the TB and PUI study groups; however, no statistically significant differences were found in the angular deviations (p = 0.309) between the trephine bur and piezoelectric ultrasonic insert study groups. (3) Conclusions: The results showed that the TB is more accurate than the PUI for apical location.

Graft Materials and Canine Vertical Position Associated with Alveolar Bone Graft Outcomes Assessed by 3D Cone Beam CT

The introduction of Cone Beam Computed Tomography (CBCT) into the alveolar bone grafting protocol now allows surgeons to look at pre- and postoperative bony structures to determine surgical success. Until recently, pre- and postoperative assessment have been determined by 2-dimensional (2D) periapical and panoramic radiographs. CBCTs can now be used to volumetrically assess defects. Yet to date, no scale has been standardized to classify alveolar bone grafting levels postoperatively to determine the success of the procedure. This study aims to analyze pre- and postoperative cone bean CBCT scans to determine if variables such as cleft size, canine position, and bone grafting material can help predict surgical outcomes. A total of 79 patients (average 10.4 years) with non-syndromic complete unilateral cleft lip and palate had been treated with ABG and bone morphogenetic protein-2 with demineralized bone matrix (BMP2/DBM) versus iliac crest bone (ICB) were compared. Preoperative CBCT scans (n = 27) were available to determine the cleft width. The postoperative CBCT was analyzed by the Bergland scale score. A novel method for categorizing canine eruption separated post-graft patients into 5 groups. The cleft width might be correlated with bone graft outcomes, but limited to the sample size, with no statistical significance (n = 27, R2 = 0.378, P > .05). In total, 21 (26.6%) patients have supernumerary or impacted teeth in the cleft, but not related to bone graft outcomes. There is no statistical difference between the 4 surgeons’ cleft repair. The 2D modalities traditionally used to interpret SABG results possess inherent limitations of structure overlapping and distortion of the relationship of anatomy. Since the advent of the CBCT, 3D volumetric analysis has largely accounted for these errors. Yet to date, no scale standardized to the CBCT has been developed to assess SABG results.The authors' results suggest that graft outcomes correlate with pre-graft canine positions. An unerupted, high permanent canine vertical position will yield poor results, likely due to previously documented growth-inhibiting scarring of soft tissue, and the ideal timing of SABG may be when two-thirds of the canine crown is located below the palatal plane with the adjacent premolars not fully erupted. This may be due to the optimal timing for the canine to complete its eruption into the grafting site to influence the maintenance of the graft and periodontal support of the adjacent teeth. In a patient with complete unilateral cleft lip and palate, iliac crest bone graft tended to have better graft outcomes than BMP2/DBM in this sample. This may be attributed to BMP2/DBM's osteoconductive properties vs. ICB's osteogenic, osteoinductive, and osteoconductive properties. There was no evidence that cleft width correlates with the grafting outcome. However, results were limited to sample size.

Microguided endodontics: Accuracy evaluation for access through intraroot fibre-post.

In this work, we intended to assess the reliability of guided endodontic technique to remove a bonded fibre-post when there are artefacts in the cone-beam computed tomography (CBCT) images caused by composite dental materials. We mounted natural posterior teeth on ten simulated models. Forty fibre-post and composite-core restorations were inserted in the teeth. We merged a pre-operative CBCT and optical surface scan on the BlueskyplanTM software to digitally design and subsequently 3D-printed the guides. Two operators initiated endodontic access into the fibre-post restorations using the template to guide the drill. Post-operative CBCT was taken and merged onto the pre-operative plan to measure the deviations at the coronal and apical segments. The mean deviation between the planned and actual drill paths were, respectively, of 0.39 ± 0.14 mm coronally and 0.40 ± 0.19 mm apically. Microguided endodontics is a predictable and accurate method to remove fibre-post restorations efficiently.