The classification of malocclusion

Purpose: The aim of this prospective clinical study was to assess the risk factors associated with failure of mini-implants used for orthodontic anchorage. Materials and Methods: A total of 140 miniimplants in 44 patients, including 48 miniplates and 92 freestanding miniscrews, were examined in the study. A variety of orthodontic loads were applied. The majority of implants were placed in the posterior maxilla (104/140), and the next most common location was the posterior mandible (34/140). Results: A cumulative survival rate of 89% (125/140) was found by Kaplan-Meier analysis. There was no significant difference in the survival rate between miniplates and freestanding miniscrews, but miniplates were used in more hazardous situations. The Cox proportional-hazards regression model identified anatomic location and peri-implant soft tissue character as 2 independent prognostic indicators. The estimated relative risk of implant failure in the posterior mandible was 1.101 (95% confidence interval, 0.942 to 1.301; P = .046). The risk ratio of failure for implants surrounded by nonkeratinized mucosa was 1.117 (95% confidence interval, 0.899 to 1.405; P = .026). Discussion and Conclusion: The results confirmed the effectiveness of orthodontic mini-implants, but in certain situations adjustment of the treatment plan or modifications in the technique of implant placement may lead to improved success rates. INT J ORAL MAXILLOFAC IMPLANTS 2004;19:100‐106

A Prospective Study of the Risk Factors Associated with Failure of Mini-implants Used for Orthodontic Anchorage

Intraoral scanners (IOS) are devices for capturing direct optical impressions in dentistry. The purpose of this narrative review on the use of IOS was to: (1) identify the advantages/disadvantages of using optical impressions compared to conventional impressions; (2) investigate if optical impressions are as accurate as conventional impressions; (3) evaluate the differences between the IOS currently available commercially; (4) determine the current clinical applications/limitations in the use of IOS. Electronic database searches were performed using specific keywords and MeSH terms. The searches were confined to full-text articles written in English and published in peer-reviewed journals between January 2007 and June 2017. One hundred thirty-two studies were included in the present review; among them, 20 were previous literature reviews, 78 were in vivo clinical studies (6 randomized controlled/crossover trials, 31 controlled/comparative studies; 24 cohort studies/case series; 17 case reports) and 34 were in vitro comparative studies. Optical impressions reduce patient discomfort; IOS are time-efficient and simplify clinical procedures for the dentist, eliminating plaster models and allowing better communication with the dental technician and with patients; however, with IOS, it can be difficult to detect deep margin lines in prepared teeth and/or in case of bleeding, there is a learning curve, and there are purchasing and managing costs. The current IOS are sufficiently accurate for capturing impressions for fabricating a whole series of prosthetic restorations (inlays/onlays, copings and frameworks, single crowns and fixed partial dentures) on both natural teeth and implants; in addition, they can be used for smile design, and to fabricate posts and cores, removable partial prostheses and obturators. The literature to date does not support the use of IOS in long-span restorations with natural teeth or implants. Finally, IOS can be integrated in implant dentistry for guided surgery and in orthodontics for fabricating aligners and custom-made devices.

/pdf/intraoral-scanners-in-dentistry-a-review-of-the-current-26q4ueb6fl.pdf

Intraoral scanners in dentistry: a review of the current literature

Polycyclic aromatic hydrocarbons (PAHs) are a large group of chemicals. They represent an important concern due to their widespread distribution in the environment, their resistance to biodegradation, their potential to bioaccumulate and their harmful effects. Several pilot treatments have been implemented to prevent economic consequences and deterioration of soil and water quality. As a promising option, fungal enzymes are regarded as a powerful choice for degradation of PAHs. Phanerochaete chrysosporium, Pleurotus ostreatus and Bjerkandera adusta are most commonly used for the degradation of such compounds due to their production of ligninolytic enzymes such as lignin peroxidase, manganese peroxidase and laccase. The rate of biodegradation depends on many culture conditions, such as temperature, oxygen, accessibility of nutrients and agitated or shallow culture. Moreover, the addition of biosurfactants can strongly modify the enzyme activity. The removal of PAHs is dependent on the ionization potential. The study of the kinetics is not completely comprehended, and it becomes more challenging when fungi are applied for bioremediation. Degradation studies in soil are much more complicated than liquid cultures because of the heterogeneity of soil, thus, many factors should be considered when studying soil bioremediation, such as desorption and bioavailability of PAHs. Different degradation pathways can be suggested. The peroxidases are heme-containing enzymes having common catalytic cycles. One molecule of hydrogen peroxide oxidizes the resting enzyme withdrawing two electrons. Subsequently, the peroxidase is reduced back in two steps of one electron oxidation. Laccases are copper-containing oxidases. They reduce molecular oxygen to water and oxidize phenolic compounds.

/pdf/biodegradation-of-polycyclic-aromatic-hydrocarbons-pahs-by-4hm2boq8ux.pdf

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by fungal enzymes: A review.

Background Until now, only a few studies have compared the ability of different intraoral scanners (IOS) to capture high-quality impressions in patients with dental implants Hence, the aim of this study was to compare the trueness and precision of four IOS in a partially edentulous model (PEM) with three implants and in a fully edentulous model (FEM) with six implants Methods Two gypsum models were prepared with respectively three and six implant analogues, and polyether-ether-ketone cylinders screwed on These models were scanned with a reference scanner (ScanRider®), and with four IOS (CS3600®, Trios3®, Omnicam®, TrueDefinition®); five scans were taken for each model, using each IOS All IOS datasets were loaded into reverse-engineering software, where they were superimposed on the reference model, to evaluate trueness, and superimposed on each other within groups, to determine precision A detailed statistical analysis was carried out Results In the PEM, CS3600® had the best trueness (458 ± 16μm), followed by Trios3® (502 ± 25μm), Omnicam® (588 ± 16μm) and TrueDefinition® (614 ± 30μm) Significant differences were found between CS3600® and Trios3®, CS3600® and Omnicam®, CS3600® and TrueDefinition®, Trios3® and Omnicam®, Trios3® and TrueDefinition® In the FEM, CS3600® had the best trueness (606 ± 117μm), followed by Omnicam® (664 ± 39μm), Trios3® (672 ± 69μm) and TrueDefinition® (1064 ± 231μm) Significant differences were found between CS3600® and TrueDefinition®, Trios3® and TrueDefinition®, Omnicam® and TrueDefinition® For all scanners, the trueness values obtained in the PEM were significantly better than those obtained in the FEM In the PEM, TrueDefinition® had the best precision (195 ± 31μm), followed by Trios3® (245 ± 37μm), CS3600® (248 ± 46μm) and Omnicam® (263 ± 15μm); no statistically significant differences were found among different IOS In the FEM, Trios3® had the best precision (315 ± 98μm), followed by Omnicam® (572 ± 91μm), CS3600® (655 ± 167μm) and TrueDefinition® (753 ± 438μm); no statistically significant differences were found among different IOS For CS3600®, For CS3600®, Omnicam® and TrueDefinition®, the values obtained in the PEM were significantly better than those obtained in the FEM; no significant differences were found for Trios3® Conclusions Significant differences in trueness were found among different IOS; for each scanner, the trueness was higher in the PEM than in the FEM Conversely, the IOS did not significantly differ in precision; for CS3600®, Omnicam® and TrueDefinition®, the precision was higher in the PEM than in the FEM These findings may have important clinical implications

/pdf/accuracy-of-four-intraoral-scanners-in-oral-implantology-a-28fetn1rtx.pdf

Accuracy of four intraoral scanners in oral implantology: a comparative in vitro study.

Statement of problem Because the digital workflow can begin directly in the oral cavity, intraoral scanners are being adopted in dental treatments. However, studies of the relationship between the experience of the practitioner and the accuracy of impression data are needed. Purpose The purpose of this clinical study was to investigate the effect of the experience curve on changes in trueness when a patient's complete dental arch is scanned. Material and methods Twenty dental hygienists with more than 3 years of experience in dental clinical practice (group 1 had 3 to 5 years; group 2 had >6 years) were recruited to learn to operate 2 intraoral scanner systems. All learners scanned the assigned patient's oral cavity 10 times during the experience sessions. Precision was calculated as the mean deviation among all superimposition combinations from the 10 scanned data sets of each learner [n= 10 C 2 =45]. Trueness was evaluated by superimposing the 10 consecutive intraoral scan data onto the impression scan data from each patient's rubber impression body (n=10). The acquired images were processed and analyzed using a 3-dimensional analysis software. For statistical analysis, the independent 2-sample t test and repeated measures ANOVA were performed (α=.05). Results The mean precision of the Trios scanner was greater than that of the iTero (Trios, 52.30 μm; iTero, 60.46 μm; P P P >.05). In the iTero group but not in the Trios group, the length of clinical experience influenced the change of trueness as a result of repeated experience ( P P Conclusions The single-image based system required repeated learning sessions for effective clinical application. The newer system offered better trueness and precision and was less likely to be influenced by the length of clinical career or the region being scanned.

Comparison of digital intraoral scanner reproducibility and image trueness considering repetitive experience.

Statement of problem Conventional impression-making methods are being replaced by intraoral digital scanning. How long dental professionals take to master the new technologies is unknown. Purpose The purpose of this human subject study was to compare the experience curves of 2 intraoral scanners among dental hygienists and determine whether repeated scanning experience could change the scan time (ST). Material and methods A total of 29 dental hygienists with more than 3 years of working experience were recruited (group 1: 3-5 years; group 2: >6 years of clinical experience) to learn the iTero and Trios systems. All learners scanned the oral cavities of 4 human participants (participants A, B, C, and D) 10 times (T1-T10) throughout the learning sessions and the experimental dentoform model twice at the beginning and end of the 10 sessions. ST was measured, and changes in ST were compared between the 2 devices. Results The average ST for 10 sessions was greater with iTero than with Trios, but the decrease in the measured ST was greater for iTero than for Trios. Baseline and postexperience STs with iTero showed statistically significant differences, with a decrease in time related to the clinical experience levels of the dental hygienists (group 1: T2 and T4, P P Conclusions Although the learning rate of iTero was rapid, the average ST for iTero was longer than Trios, and clinical experience levels influenced the operator's ability to manipulate the device. In contrast, the learning rate of Trios was slow, and measured ST was shorter than iTero, and was not influenced by clinical experience.

Comparison of experience curves between two 3-dimensional intraoral scanners.

Objective: The purpose of this study was to compare the precision of threedimensional (3D) images acquired using iTero® (Align Technology Inc., San Jose, CA, USA) and Trios® (3Shape Dental Systems, Copenhagen, Denmark) digital intraoral scanners, and to evaluate the effects of the severity of tooth irregularities and scanning sequence on precision. Methods: Dental arch models were fabricated with differing degrees of tooth irregularity and divided into 2 groups based on scanning sequence. To assess their precision, images were superimposed and an optimized superimposition algorithm was employed to measure any 3D deviation. The t-test, paired t-test, and one-way ANOVA were performed (p < 0.05) for statistical analysis. Results: The iTero® and Trios® systems showed no statistically significant difference in precision among models with differing degrees of tooth irregularity. However, there were statistically significant differences in the precision of the 2 scanners when the starting points of scanning were different. The iTero® scanner (mean deviation, 29.84 ± 12.08 mm) proved to be less precise than the Trios® scanner (22.17 ± 4.47 mm). Conclusions: The precision of 3D images differed according to the degree of tooth irregularity, scanning sequence, and scanner type. However, from a clinical standpoint, both scanners were highly accurate regardless of the degree of tooth irregularity. [Korean J Orthod 2016;46(1):3-12]

/pdf/a-comparison-of-the-precision-of-three-dimensional-images-17txmu1y2v.pdf

A comparison of the precision of three-dimensional images acquired by 2 digital intraoral scanners: effects of tooth irregularity and scanning direction

Lateral cephalometry has been widely used for skeletal classification in orthodontic diagnosis and treatment planning. However, this conventional system, requiring manual tracing of individual landmarks, contains possible errors of inter- and intravariability and is highly time-consuming. This study aims to provide an accurate and robust skeletal diagnostic system by incorporating a convolutional neural network (CNN) into a 1-step, end-to-end diagnostic system with lateral cephalograms. A multimodal CNN model was constructed on the basis of 5,890 lateral cephalograms and demographic data as an input. The model was optimized with transfer learning and data augmentation techniques. Diagnostic performance was evaluated with statistical analysis. The proposed system exhibited >90% sensitivity, specificity, and accuracy for vertical and sagittal skeletal diagnosis. Clinical performance of the vertical classification showed the highest accuracy at 96.40 (95% CI, 93.06 to 98.39; model III). The receiver operating characteristic curve and the area under the curve both demonstrated the excellent performance of the system, with a mean area under the curve >95%. The heat maps of cephalograms were also provided for deeper understanding of the quality of the learned model by visually representing the region of the cephalogram that is most informative in distinguishing skeletal classes. In addition, we present broad applicability of this system through subtasks. The proposed CNN-incorporated system showed potential for skeletal orthodontic diagnosis without the need for intermediary steps requiring complicated diagnostic procedures.

Automated Skeletal Classification with Lateral Cephalometry Based on Artificial Intelligence

Volumetric changes in the upper airway after bimaxillary surgery for skeletal class iii malocclusions: A case series study using 3-dimensional cone-beam computed tomography

Minji Kim

Papers

Comparison of digital intraoral scanner reproducibility and image trueness considering repetitive experience.

Comparison of experience curves between two 3-dimensional intraoral scanners.

A comparison of the precision of three-dimensional images acquired by 2 digital intraoral scanners: effects of tooth irregularity and scanning direction

Automated Skeletal Classification with Lateral Cephalometry Based on Artificial Intelligence

Volumetric changes in the upper airway after bimaxillary surgery for skeletal class iii malocclusions: A case series study using 3-dimensional cone-beam computed tomography