Digitally guided corticotomy using a customized surgical template (Suya corticotomy utility template): A technique report.

Three-dimensional surgical simulation

To investigate the accuracy and reliability of cone beam computed tomography (CBCT) measurements of buccal alveolar bone height (BBH) and thickness (BBT) using custom acquisition settings. School of Dentistry, Oregon Health & Science University. Twelve embalmed cadavers. Cadaver heads were imaged by CBCT (i-CAT® 17-19, Imaging Sciences International, Hatfield, PA) using a 'long scan' (LS) setting with 619 projection images, 360° revolution, 26.9 s duration, and 0.2 mm voxel size, and using a 'short scan' (SS) setting with 169 projection images, 180° rotation, 4.8 s duration, and 0.3 mm voxel size. BBH and BBT were measured with 65 teeth, indirectly from CBCT images and directly through dissection. Comparisons were assessed using paired t-tests (p≤0.05). Level of agreement was assessed by concordance correlation coefficients, Pearson's correlation coefficients, and Bland-Altman plots. Mean differences in measurements compared to direct measurements were as follows, LS 0.17±0.12 (BBH) and 0.10±0.07 mm (BBT), and SS 0.41±0.32 (BBH) and 0.12±0.11 mm (BBT). No statistical differences were found with any of BBH or BBT measurements. Correlation coefficients and Bland-Altman plots showed agreement was high between direct and indirect measurement methods, although agreement was stronger for measurements of BBH than BBT. Compared to the LS, the similarity in results with the reduced scan times and hence reduced effective radiation dose, favors use of shorter scans, unless other purposes for higher resolution imaging can be defined.

This study was aimed to investigate a modified buccal osteotomy technique and whether the integrity of the lingual part of the lower border influences the attachment of the neurovascular bundle to the proximal segment of the mandible during a sagittal split osteotomy without increasing the number of bad splits. The presence of self-reported sensibility disturbance in the lower lip at the last follow-up visit was assessed. This study included 220 and 133 patients with bilateral sagittal split osteotomy undergoing the classical and the new modified buccal osteotomy techniques, respectively. In the new technique, the lower border is divided into a lingual fragment that remains incorporated in the tooth-bearing fragment and a buccal fragment that comes with the proximal fragment (buccal plate). In the classical technique, the inferior alveolar nerve was attached to the proximal segment of the mandible in more than one third of operation sites (36.36% on the right and 40.91% on the left) compared with less than one fourth of the operation sites using the new technique (9.73% on the right and 23.01% on the left). The overall figure of self-reported changed sensibility was 09.40% (12/128) in the new technique compared to 15.12% in the classical technique. We present a suitable improvement to the classical buccal osteotomy technique that allows less manipulation and injury of the inferior alveolar nerve with consequent reduction in self-reported postoperative changes in lower lip sensation

Commentary: Cone-Beam Computed Tomography: An Essential Technology for Management of Complex Periodontal and Implant Cases.

Guided Access Cavity Preparation Using a New Simplified Digital Workflow

Objective (1) To apply an integrated digital maxillodental model in computer aided design and manufacturing(CAD/CAM) of individualized miniscrew surgical guides (2) and to evaluate the accuracy of miniscrew placement by using the surgical guides. Methods Integrated the cone beam computerized tomography (CBCT)-based maxillodental model and laser-scanned dental model in 12 subjects. Virtual positions of miniscrews were determined based on the integrated digital maxillodental models. 3D virtual surgical guides were designed according to the virtual implantation plans and fabricated with stereolithographic appliance(SLA). Miniscrews were implanted in the patient's upper jaw area using surgical guides (experimental group, n=12) or periapical X-ray (control group, n=12). Deviation between actual and planned placements were measured as 3D angular deviations and distance (coronal and apical) deviations. The security and stability of miniscrews implantation was evaluated. Results In the surgical guides group, the angular deviation was a mean of 4.97±1.79°, and the distance deviations in the coronal and apical areas were mean of 0.98±0.30 mm and 1.03±0.22 mm .There was no root damage from miniscrew placement, and 10 of the miniscrews were placed in the middle of roots. While in control group, 4 of the miniscrews were placed in the middle of roots. Conclusions The surgical guide has high accuracy and will be especially useful for patients who require precise miniscrew placement. Key words: integrated digital maxillodental model; CBCT; CAD/CAM; individualized miniscrew surgical guides

AimThe purpose of this study was to evaluate the effect of the density and the thickness of the cortical and the cancellous bone at selected inter-radicular areas in subjects with different facial growth patterns using cone beam computed tomography (CBCT) in order to choose the optimal area for miniscrew insertion.Materials and methodsFrom 150 CBCT scans, 45 scans were included in the study. The subjects were categorized into three groups based on their skeletal growth pattern according to SN-GoMe angle and facial height index. Cortical and cancellous bone density and thickness were measured at the selected inter-radicular areas.ResultsCompared to the other two groups, the hyperdivergent group had thinner cortical bone in the anterior region of the maxilla between the central and the lateral incisors on the buccal side at 4 mm from the alveolar crest (P-value: 0.012) and on the palatal side at 7 mm from the alveolar crest (P-value: 0.030). Cancellous bone density values in these areas were higher in subjects with hypodivergent and hyperdivergent growth pattern. Furthermore, in hyperdivergent group less dense cortical bone in the posterior region of the maxilla on the palatal side between the second premolar and the first molar (p-value: 0.020) and on the buccal side between the first molar and the second molar (p-value: 0.038 & 0.047) was observed. No significant differences were found in the mandible between the three groups. No significant differences were found between the male and the female subjects.ConclusionHyperdivegents presented thinner cortical bone in the anterior of the maxilla between the central and the lateral incisors. Less dense cortical bone was found between maxillary second premolar and first molar on the palatal side and also between the maxillary first molar and the second molar on the buccal side in this group too. Normal showed higher density values in the posterior of the maxilla compared to the other two groups. No significant differences were found among three groups in mandible.

BackgroundGuided insertion of palatal miniscrews using a lateral cephalogram instead of cone beam computed tomography (CBCT) significantly reduces the radiation level for the patient. Till now no data are available on the risk of hitting the incisors in this regard, which is one of the worst clinical complications when inserting a paramedian miniscrew. Hence, this study aims to investigate the distance between the mini-implant and the roots of the central and lateral incisors.MethodsLateral cephalogram, an intraoral scan, and CBCT of 20 patients were superimposed. After a miniscrew (1.7 × 8 mm) placement based on intraoral scan and lateral cephalogram, the CBCT was used as control for the distance between the miniscrews and the roots of the incisors.ResultsThe mean value of the shortest distance between the miniscrew and roots of the incisors in the lateral cephalogram was 4.74 ± 1.67 mm. The distance between both miniscrews and the central incisors measured in the CBCT was 5.03 ± 2.22 mm and 5.26 ± 2.21 mm and between the two miniscrews and the lateral incisors was 4.93 ± 1.91 mm and 5.21 ± 2.64 mm. No significant differences between the distances in the CBCT and the lateral cephalogram could be observed. In one case, the CBCT control revealed the penetration of two palatally displaced canines after insertion based on intraoral scan and lateral cephalogram.ConclusionsThe use of an intraoral scan and a lateral cephalogram for guided paramedian insertion of palatal miniscrews can prevent incisor root damage. This may reduce the radiation since no CBCT seems necessary. The current investigation focuses on the anterior paramedian area of the palate. Outside that region and in complex cases with displaced teeth in the palatal area, a CBCT might be indicated.

Automatic segmentation of individual tooth root is a key technology for the reconstruction of the three-dimensional dental model from Cone Beam Computed Tomography (CBCT) images, which is of great significance for the orthodontic, implant and other dental diagnosis and treatment planning. Currently, tooth root segmentation is mainly done manually because of the similar gray of the tooth root and the alveolar bone from CBCT images. This study aims to explore the automatic tooth root segmentation algorithm of CBCT axial image sequence based on deep learning. We proposed a new automatic tooth root segmentation method based on the deep learning U-net with AGs. Since CBCT sequence has a strong correlation between adjacent slices, a Recurrent neural network (RNN) was applied to extract the intra-slice and inter-slice contexts. To develop and test this new method for automatic segmentation of tooth roots using CBCT images, 24 sets of CBCT sequences containing 1160 images and 5 sets of CBCT sequences containing 361 images were used to train and test the network, respectively. Applying to the testing dataset, the segmentation accuracy measured by the intersection over union (IOU), dice similarity coefficient (DICE), average precision rate (APR), average recall rate (ARR), and average symmetrical surface distance (ASSD) are 0.914, 0.955, 95.8% , 95.3% , 0.145 mm, respectively. The study demonstrates that the new method combining attention U-net with RNN yields the promising results of automatic tooth roots segmentation, which has potential to help improve the segmentation efficiency and accuracy in future clinical practice.

Virtual planning and volumetric evaluation of wound healing following regenerative surgical treatment of intrabony periodontal defects

Digital workflow has become an important tool for surgical dentistry and helpsclinicians plan and treat several conditions. The excessive gingival display, also known as a gummy smile, is one of the conditions where digital planning and 3D-printed surgical guides bring benefits to both patients and surgeons, by increasing the accuracy of the execution, as close as possible, to the proposed planning. The objective of this case report is to show a case of altered passive eruption treated with aesthetic crown lengthening with the use of a 3D-printed surgical guide. After the patient accepted the proposed treatment plan, a surgical guide was printed according to the digital planning. The surgery had an initial gingivectomy guided by the 3D-printed guide, and after raising the mucoperiosteal flap, osteotomy was also guided by a 3D-printed guide. After three months, the patient was sent to the prosthodontist to replace a composite veneer on the left upper central incisor, with the margins exposed after the gingival healing.With 30 months of follow-up, the patient presents great margin stability and periodontal health. The use of digital workflow appears to facilitate the predictability of periodontal aesthetic treatments and may have more applicability shortly.

Computer-assisted orthognathic surgery: feasibility study using multiple CAD/CAM surgical splints

Accuracy of an optical robotic computer-aided implant system and the trueness of virtual techniques for measuring robot accuracy evaluated with a coordinate measuring machine in vitro

Dental study models are essential records for orthodontic diagnosis, planning and treatment evaluations. As plaster models are prone to damage and loss, require storage space and inefficient to retrieve and transfer, digital models are been used to eliminate drawbacks of plaster model regarded as potential replacement of traditional plaster models. Aim: To compare the accuracy and reliability of linear measurements on digital models derived from Cone Beam Computed Tomography (CBCT) and three-dimensional (3D) laser scanned impressions with conventional plaster models. Objectives: i. To compare the accuracy and reliability of measurements made on Plaster and CBCT derived digital models. ii. To compare the accuracy and reliability of measurements made on plaster and 3- dimensional laser scanned impression models. iii. To compare the accuracy and reliability of measurements made on CBCT models and 3D laser scanned impression models. Materials and Methods: CBCT and plaster models will be prepared from 12 patients. Rubber base impressions will be scanned using 3D dental laser scanner. Landmarks will be marked and the linear measurements of all the three models will be compared using 3D software. Results: The derived data was subjected to ANOVA test, Post Hoc Tukey test, Intraclass correlation coefficients (ICCs) and Method Error to evaluate the reliability of repeated measurements. No significant difference was found between plaster models, CBCT models and impression scanned laser models. Conclusion: Plaster models, CBCT models and models obtained from laser scan of impressions are three different diagnostic records. Each have their own advantages and disadvantages. The present study shows that models obtained from laser scanned impressions are comparable to plaster models. The accuracy is adequate for initial diagnosis and treatment planning in clinical orthodontics Keywords: Digital models, Cone beam computed tomography, Laser scan, Meshlab, DIC

Part 2 of this clinical study aims to compare the radiographic change in periapical status of individual roots determined using digital periapical radiographs versus cone beam computed tomography (CBCT) 1year after primary root canal treatment and to determine the radiological outcome of treatment for each tooth. Periapical radiographs and CBCT scans of 123 teeth in 99 patients assessed 1year after completion of primary root canal treatment by a single operator were compared with their respective pre-treatment (diagnostic) periapical radiographs and CBCT scans. The presence or absence as well as the increase or decrease in size of existing periapical radiolucency was assessed by a consensus panel consisting of two calibrated examiners. The panel viewed the images under standardized conditions. Paired comparison of the outcome diagnosis of individual roots and teeth was performed using generalized McNemar's or Stuart-Maxwell test of symmetry analysis. The 'healed' rate (absence of periapical radiolucency) for all roots combined was 92.7% using periapical radiographs and 73.9% for CBCT (P<0.001). This rate increased to 97.2% and 89.4%, respectively, when the 'healing' group (reduced size of periapical radiolucency) was included (P<0.001). A statistically significant difference in outcome diagnosis of single roots was observed between DPA and CBCT in single-rooted teeth and the buccal or mesio-buccal roots of multi-rooted teeth (P<0.05). Analysis by tooth revealed that the 'healed' rate (absence of periapical radiolucency) was 87% using periapical radiographs and 62.5% using CBCT (P<0.001). This increased to 95.1% and 84.7%, respectively, when the 'healing' group (reduced size of periapical radiolucency) was included (P<0.002). Outcome diagnosis of teeth showed a statistically significant difference between systems (P<0.001). Reconstructed CBCT images revealed more failures (17.6%) in teeth with no pre-operative periapical radiolucencies compared with periapical radiographs (1.3%) (P=0.031). In teeth with existing pre-operative periapical radiolucencies, reconstructed CBCT images also showed more failures (13.9%) compared with periapical radiographs (10.4%). Diagnosis using CBCT revealed a lower healed and healing rate for primary root canal treatment than periapical radiographs, particularly in roots of molars. There was a 14 times increase in failure rate when teeth with no pre-operative periapical radiolucencies were assessed with CBCT compared with periapical radiographs at 1year.