Effect of attachment configuration and trim line design on the force system of orthodontic aligners: A finite element study on the upper central incisor.

OBJECTIVES: To use the finite element method (FEM) to investigate the effect of various attachment configurations and trimming line designs of orthodontic aligners on their biomechanical performance. METHOD: A 3D upper jaw model was imported into 3D design software. The upper right central incisor tooth (Tooth 11) was made mobile, and its periodontal ligament (PDL) and bone structures were designed. Aligners were modelled with three distinct attachment configurations: No attachment, rectangular horizontal, rectangular vertical, and two trimming line designs; scalloped and straight extended, with a homogeneous thickness of 0.6 mm. These models were then imported into an FE software. Simulations were conducted for three different movements, including facial translation, distalization, and extrusion. RESULTS: Forces were recorded at 1.3-2.6 N during facial translation, 1.4-5.9 N in distalization, and 0.0-2.0 N in extrusion. The straight extended trimming line consistently generated higher forces than the scalloped design. Attachments had no significant impact on force components during facial translation but were more effective in distalization and extrusion. The combination of a straight extended trimming line with horizontal attachments exhibited the least stresses at the apical third during distalization, and the highest stresses during extrusion, suggesting superior retention. CONCLUSIONS: Rectangular attachments offer limited benefits in facial translation, but horizontal rectangular attachments can intensify load in distalization and are crucial for force generation in extrusion. Horizontal attachments are preferred over vertical options. Additionally, the straight extended trim line enhances control of tooth movement and can replace attachments in certain cases. CLINICAL RELEVANCE: These findings provide biomechanical evidence and an optimal protocol to guide clinical practice in planning diverse teeth movements. The emphasis is on the influence of attachment utilization and the specific design of aligner trimming lines to enhance control over tooth movement.

Three-dimensional computed tomography analysis of airway volume in growing class II patients treated with Frankel II appliance.

OBJECTIVE: The purpose of this retrospective study was to assess the airway volume changes associated with the use of Frankel appliance (FR II) in Class II malocclusion patients using three-dimensional cone beam computed tomography (3D CBCT) imaging. MATERIALS AND METHODS: The sample consisted of 31 Class II malocclusion patients (mean age 9.24 ± 1.93 years old, 17 males (54.8%) and 14 females (45.2%)) treated with FR II appliance by the same orthodontist for an average of 9 months ± 20 days. CBCT images were taken before and after treatment and upper airway volume changes were measured using Dolphin 3D software version11.0 (Dolphin Imaging, Chatsworth, CA) and statistically compared. RESULTS: Airway volume of nasal cavity, nasopharynx, oropharynx, hypopharynx and the total airway volume significantly increased after the use of FR II appliance. In addition, significant increase was reported in maxillary base, inter-molar, inter-premolar and inter-canine width. Significant increase in soft tissue thickness was only recorded opposite to CV2. CONCLUSION: The use of the FR II appliance in growing subjects with Class II malocclusion led to a significant increase in the upper airway volume in addition to the anticipated dental and skeletal transverse expansion effects.

Physiochemical and mechanical characterisation of orthodontic 3D printed aligner material made of shape memory polymers (4D aligner material).

OBJECTIVES: To conduct a physiochemical and mechanical material analysis on 3D printed shape-memory aligners in comparison to thermoformed aligners. MATERIALS AND METHODS: Four materials were examined, including three thermoformed materials: CA Pro (CP), Zendura A (ZA), Zendura FLX (ZF), and one 3D printed material: Tera Harz (TC-85). Rectangular strips measuring 50 × 10 × 0.5 mm were produced from each material. Five tests were conducted, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), shape recovery tests, three-points bending (3 PB), and Vickers surface microhardness (VH). RESULTS: DSC recorded glass transition temperatures (Tg) at 79.9 °C for CP, 92.2 °C for ZA, 107.1 °C for ZF, and 42.3 °C for TC-85. In DMA analysis at 20-45 °C, a prominent decrease in storage modulus was observed, exclusively for TC-85, as the temperature increased. Notably, within the temperature range of 30-45 °C, TC-85 exhibited substantial shape recovery after 10 min, reaching up to 86.1 %, while thermoformed materials showed minimal recovery (1.5-2.9 %). In 3 PB test (at 30, 37, 45 °C), ZA demonstrated the highest force at 2 mm bending, while TC-85 exhibited the lowest. Regarding VH at room temperature, there was a significant decrease for both ZA and ZF after thermoforming. ZA had the highest hardness, followed by ZF and TC-85, with CP showing the lowest values. CONCLUSIONS: TC-85 demonstrates exceptional shape memory at oral temperature, improving adaptation, reducing force decay, and enabling, together with its higher flexibility, extensive tooth movement per step. Additionally, it maintains microhardness similar to thermoformed sheets, ensuring the durability and effectiveness of dental aligners. CLINICAL RELEVANCE: The 3D printed aligner material with shape memory characteristics (4D aligner) has revolutionized the orthodontic aligner field. It showed mechanical properties more suitable for orthodontic treatment than thermoforming materials. Additionally, it offers enhanced control over aligner design and thickness, while optimizing the overall workflow. It also minimizes material wastage, and reduces production expenses.

Does maxillary sinus proximity affect molar root resorption during distalization using Invisalign? a CBCT study.

BACKGROUND: This study aimed to assess the correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption during molar distalization using clear aligner therapy (CAT). MATERIALS AND METHODS: Thirty-eight cone beam computed tomography scans (CBCTs) obtained pre- (T0) and post-treatment (T1) from 19 adult patients (36.68 ± 13.50 years), who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization, were evaluated in this study At least 22 h of aligner wear per day was a main inclusion criterion. Sinus proximity and changes in root lengths were measured for 61 molars (183 roots). Spearman coefficient analysis was used for assessing correlation between sinus proximity and root resorption. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by intraclass correlation coefficient (ICC). RESULTS: Spearman coefficient revealed no significant correlation between sinus proximity and molar root resorption for mesiobuccal, distobuccal or palatal roots (p = 0.558, p = 0.334, p = 0.931, respectively). CONCLUSION: There was no correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption.

Treatment effects of Herbst appliance in skeletal Class II cases during pre-pubertal and post-pubertal periods: a cone-beam computed tomographic study.

In the present study, Thirty-six Class patients II (A condition in which the upper jaw is larger than the lower jaw) were randomly selected and assigned to one of two groups based on their maturation stage: the pre-pubertal group (18 patients, mean age 9.15 ± 1.5 years) and post-pubertal group (18 patients, mean age 16.3 ± 1.0 years). All patients were treated with a metallic splint-supported Herbst IV appliance (An appliance that acts like artificial joint working between the upper and power jaws that keeps the lower jaw in a forward position, thus improving the Class II condition). Pretreatment (T1) and post-Herbst IV treatment (T2) scans were obtained for both groups. Dental and skeletal measurements were made on the scans and statistically analyzed using paired and independent t-tests. The study hypothesis was that; the dentoskeletal changes in Class II malocclusion treatment using Herbst appliance in the Pre-pubertal is more than the Post-pubertal growth stage due to the remaining growth potential for the pre-pubertal patients. The comparison between the two groups revealed statistically significant differences in horizontal skeletal parameters in the lower jaw only, while other readings were similar.

Outcomes of Kidney Perfusion Techniques in Transplantation from Deceased Donors: A Systematic Review and Meta-Analysis.

The high demand for organs in kidney transplantation and the expansion of the donor pool have led to the widespread implementation of machine perfusion technologies. In this study, we aim to provide an up-to-date systematic review of the developments in this expanding field over the past 10 years, with the aim of answering the question: "which perfusion technique is the most promising technique in kidney transplantation?" A systematic review of the literature related to machine perfusion in kidney transplantation was performed. The primary outcome measure was delayed graft function (DGF), and secondary outcomes included rates of rejection, graft survival, and patient survival rates after 1 year. Based on the available data, a meta-analysis was performed. The results were compared with data from static cold storage, which is still the standard of care in many centers worldwide. A total of 56 studies conducted in humans were included, and 43 studies reported outcomes of hypothermic machine perfusion (HMP), with a DGF rate of 26.4%. A meta-analysis of 16 studies showed significantly lower DGF rates in the HMP group compared to those of static cold storage (SCS). Five studies reported outcomes of hypothermic machine perfusion + O2, with an overall DGF rate of 29.7%. Two studies explored normothermic machine perfusion (NMP). These were pilot studies, designed to assess the feasibility of this perfusion approach in the clinical setting. Six studies reported outcomes of normothermic regional perfusion (NRP). The overall incidence of DGF was 71.5%, as it was primarily used in uncontrolled DCD (Maastricht category I-II). Three studies comparing NRP to in situ cold perfusion showed a significantly lower rate of DGF with NRP. The systematic review and meta-analysis provide evidence that dynamic preservation strategies can improve outcomes following kidney transplantation. More recent approaches such as normothermic machine perfusion and hypothermic machine perfusion + O2 do show promising results but need further results from the clinical setting. This study shows that the implementation of perfusion strategies could play an important role in safely expanding the donor pool.

Development and Comparison of Conventional and 3D-Printed Laboratory Models of Maxillary Defects.

BACKGROUND: Recording accurate impressions from maxillary defects is a critical and challenging stage in the prosthetic rehabilitation of patients following maxillectomy surgery. The aim of this study was to develop and optimize conventional and 3D-printed laboratory models of maxillary defects and to compare conventional and digital impression techniques using these models. METHODS: Six different types of maxillary defect models were fabricated. A central palatal defect model was used to compare conventional silicon impressions with digital intra-oral scanning in terms of dimensional accuracy and total time taken to record the defect and produce a laboratory analogue. RESULTS: Digital workflow produced different results than the conventional technique in terms of defect size measurements which were statistically significant (p < 0.05). The time taken to record the arch and the defect using an intra-oral scanner was significantly less compared with the traditional impression method. However, there was no statistically significant difference between the two techniques in terms of the total time taken to fabricate a maxillary central defect model (p > 0.05). CONCLUSIONS: The laboratory models of different maxillary defects developed in this study have the potential to be used to compare conventional and digital workflow in prosthetic treatment procedures.

Management of mandibular incisors crowding by using passive lower lingual holding arch: a case series and literature review.

Mandibular incisor crowding is a frequently encountered problem in daily orthodontic treatment. Success of the treatment greatly depends on the orthodontist's ability to manage the factors contributing to the existing crowding and implementing the proper interceptive means. The passive lower lingual holding arch (LLHA) helps maintain the position of the permanent first molars after the exfoliation of primary molars and canines. Thus, relieving the mandibular incisor crowding during transitional dentition. Four case reports age ranged from 11-13.5 years old were used to report the effect of using LLHA on mandibular incisor crowding. Little's Irregularity Index (LII) was used to assess the severity of mandibular incisors crowding as well as to compare the severity of the crowding before and after the use of LLHA. Passive LLHA could be considered the appliance of choice for space maintenance during the mixed dentition. Mandibular incisor crowding was reduced as measured by LII after the use of the passive LLHA over a duration of twenty months.

Wearable Orofacial Technology and Orthodontics.

Wearable technology to augment traditional approaches are increasingly being added to the arsenals of treatment providers. Wearable technology generally refers to electronic systems, devices, or sensors that are usually worn on or are in close proximity to the human body. Wearables may be stand-alone or integrated into materials that are worn on the body. What sets medical wearables apart from other systems is their ability to collect, store, and relay information regarding an individual's current body status to other devices operating on compatible networks in naturalistic settings. The last decade has witnessed a steady increase in the use of wearables specific to the orofacial region. Applications range from supplementing diagnosis, tracking treatment progress, monitoring patient compliance, and better understanding the jaw's functional and parafunctional activities. Orofacial wearable devices may be unimodal or incorporate multiple sensing modalities. The objective data collected continuously, in real time, in naturalistic settings using these orofacial wearables provide opportunities to formulate accurate and personalized treatment strategies. In the not-too-distant future, it is anticipated that information about an individual's current oral health status may provide patient-centric personalized care to prevent, diagnose, and treat oral diseases, with wearables playing a key role. In this review, we examine the progress achieved, summarize applications of orthodontic relevance and examine the future potential of orofacial wearables.

Computer-aided finite element model for biomechanical analysis of orthodontic aligners.

OBJECTIVES: To design a finite element (FE) model that might facilitate understanding of the complex mechanical behavior of orthodontic aligners. The designed model was validated by comparing the generated forces - during 0.2-mm facio-lingual translation of upper left central incisor (Tooth 21) - with the values reported by experimental studies in literature. MATERIALS AND METHODS: A 3D digital model, obtained from scanning of a typodont of upper jaw, was imported into 3-matic software for designing of aligners with different thicknesses: 0.4, 0.5, 0.6, 0.7 mm. The model was exported to Marc/Mentat FE software. Suitable parameters for FE simulation were selected after a series of sensitivity analyses. Different element classes of the model and different rigidity values of the aligner were also investigated. RESULTS: The resultant maximum forces generated on facio-lingual translation of Tooth 21 were within the range of 1.3-18.3 N. The force was direction-dependent, where lingual translation transmitted higher forces than facial translation. The force increases with increasing the thickness of the aligner, but not linearly. We found that the generated forces were almost directly proportional to the rigidity of the aligner. The contact normal stress map showed an uneven but almost repeatable distribution of stresses all over the facial surface and concentration of stresses at specific points. CONCLUSIONS: A validated FE model could reveal a lot about mechanical behavior of orthodontic aligners. CLINICAL RELEVANCE: Understanding the force systems of clear aligner by means of FE will facilitate better treatment planning and getting optimal outcomes.

The C-shaped root canal systems in mandibular second molars in an Emirati population.

Our study aimed to describe the root and canal morphology of mandibular second molars in Emirati population and to study the prevalence and types of morphological change in C-shaped canal configuration along the root length in an effort to describe C-shaped molars as a unit. Cone beam computed tomography (CBCT) scans of Emirati patients were analyzed in multiple plans and root and canal configuration of mandibular second molars were evaluated. Moreover, specific types of morphological change in C-shaped canal configuration along root length were studied and reconstructed using 3D reconstruction software. A total of 508 mandibular second molars were evaluated. Among the non-C-shaped mandibular second molars, two separate roots were the most prevalent root morphology (78.3%). The mesial root's most common root canal configuration was Vertucci Type II (46.5%), and in the distal root, Vertucci Type I (90.5%). The prevalence of C-shaped mandibular second molars was 17.9% and was significantly prevalent (P < 0.001) in females. Specific types of morphological change in C-shaped molars along the root length were observed and described for the first time, in which the most common types of morphological change were C1-C2-C3d (18%), C1-C3c-C3d (15.4%), C4-C3c-C3d (7.7%), and C3c-C3c-C3d (7.7%). This study showed wide variations in the root and canal morphology in mandibular second molars in Emirati population with a relatively high prevalence of C-shaped canal configuration (17.9%). Moreover, specific types of morphological change in C-shaped configuration were detected and described for the first time in this population.

Primary Evaluation of Shape Recovery of Orthodontic Aligners Fabricated from Shape Memory Polymer (A Typodont Study).

As an innovative approach to overcome the rate-limiting staging of conventional aligners, using shape memory polymers (SMPs) as aligners' materials was investigated in this in vitro study. The ability of SMPs to shape recover and consequently move tooth, upon appropriate stimuli, was evaluated on a typodont model before clinical application. The study design was to achieve 1.9 mm correction movement of an upper central incisor by one aligner after multiple steps/activation. A custom-made aligned typodont model with a movable upper central incisor was scanned. Using an orthodontic software and a 3D printer, resin-models were generated. Seven aligners of ClearX sheets (SMPs) were fabricated by thermoforming on the resin aligned model. Each aligner was tested for repositioning of the central incisor in the typodont model. The model was scanned after each step and the corrective movement was measured through the superimposition of scans. Results showed that the total correction efficiency of the SMPs' aligner was ≈93% (1.76 mm). The corrective movement was 0.94 ± 0.04 mm after the reforming step, 0.66 ± 0.07 mm after the first activation step, and 0.15 ± 0.10 mm after the second activation step. It was concluded that aligners made of SMPs could have a promising future-use in orthodontic aesthetic treatment.

A visual evaluation of oral plaque removal utilizing an adjunct enzyme pre-rinse in orthodontic subjects.

OBJECTIVE: To determine if an adjunct proteolytic pre-rinse along with contemporary methods of dental cleaning may more effectively remove visual plaque in subjects with fixed orthodontic appliances. MATERIALS AND METHODS: Forty-three orthodontic subjects, ages 10 to 25, completed this single site, double-blind, crossover clinical trial. Subjects randomly received bromelain enzyme or a powdered-sugar placebo pre-rinse, followed by manual tooth brushing and use of a Waterpik. Subjects received the alternate pre-rinse during the subsequent visit. Baseline and residual plaque accumulation were recorded via disclosing tablet and digital photography. A single, blinded examiner scored visual plaque scores from randomized photographs. Treatment effects on composite plaque score were evaluated using repeated-measures analysis of variance. A 5% significance level was used for all tests. RESULTS: No significant differences in plaque scores were noted at baseline or post-rinse between the enzyme and placebo. The changes from baseline to post-rinse (P = .190), post-brushing (P = .764), and post-Waterpik (P = .882) were not significantly different between interventions. Significant reduction in plaque scores were observed in both arms of the study after brushing (P < .01) and waterjet use (P < .01). Neither age (P = .220) nor gender (P = .449) impacted plaque scores. CONCLUSIONS: Use of a bromelain enzyme pre-rinse alone did not significantly enhance plaque removal. A significant reduction in retained plaque was observed with the application of brushing and or Waterpik.

Human herpes virus 8-positive germinotropic lymphoproliferative disorder: first case diagnosed in the UK, literature review and discussion of treatment options.

We present this case of human herpes virus 8-positive germinotropic lymphoproliferative disorder in a 20-year-old woman seen in the surgical oncology clinic for localised lymphadenopathy. This is the first case to be reported in the UK, and we discuss it along with a literature review including investigations and treatment options. This will demonstrate the importance of preoperative workup and multidisciplinary teamwork in deciding management plans and serve as a guide for future encounters of this rare condition in clinical practice.

Improving the accuracy of publicly available search engines in recognizing and classifying dental visual assets using convolutional neural networks.

AIM: To assess the accuracy of DigiBrain4, Inc (DB4) Dental Classifier and DB4 Smart Search Engine* in recognizing, categorizing, and classifying dental visual assets as compared with Google Search Engine, one of the largest publicly available search engines and the largest data repository. MATERIALS AND METHODS: Dental visual assets were collected and labeled according to type, category, class, and modifiers. These dental visual assets contained radiographs and clinical images of patients' teeth and occlusion from different angles of view. A modified SqueezeNet architecture was implemented using the TensorFlow r1.10 framework. The model was trained using two NVIDIA Volta graphics processing units (GPUs). A program was built to search Google Images, using Chrome driver (Google web driver) and submit the returned images to the DB4 Dental Classifier and DB4 Smart Search Engine. The categorical accuracy of the DB4 Dental Classifier and DB4 Smart Search Engine in recognizing, categorizing, and classifying dental visual assets was then compared with that of Google Search Engine. RESULTS: The categorical accuracy achieved using the DB4 Smart Search Engine for searching dental visual assets was 0.93, whereas that achieved using Google Search Engine was 0.32. CONCLUSION: The current DB4 Dental Classifier and DB4 Smart Search Engine application and add-on have proved to be accurate in recognizing, categorizing, and classifying dental visual assets. The search engine was able to label images and reject non-relevant results.

The effect of cigarette smoke on the shear bond strength of metallic and ceramic orthodontic brackets: An in vitro study.

OBJECTIVE: The bond strength between enamel and the bracket base is influenced by exposure to the oral environment. The aim of the current study was to determine the effect of cigarette smoke on the shear bond strength (SBS) of bonded metallic and ceramic orthodontic brackets. MATERIALS AND METHODS: a sample of 60 sound extracted premolars were divided into four groups (n=15 each) as follows: group (A): ceramic brackets without smoke exposure, (B): metallic brackets without smoke exposure, (C): ceramic brackets with smoke exposure, (D): metallic brackets with smoke exposure. Smoking exposure was simulated using the British American Tobacco's exposure chamber manufactured by Curbridge Engineering (Hampshire, UK). Metallic and ceramic brackets were bonded to the enamel using conventional acid etching technique. SBS (MPa) was tested using the universal Instron testing machine at a constant cross head speed of 1mm/min until failure. Kolmogorov-Smirnov test was used to test the normality of the measurements. One-way analysis of variance (ANOVA) was used to compare the means of SBSs between the four groups, Post-hoc with least significance difference was used to perform a pairwise comparison between means. Statistical significance was set at P<0.05. RESULTS: The highest SBS corresponded to the ceramic type brackets bonded to a non-smoking sample (15.7±9.5) while the lowest levels of SBS was related to metallic type brackets bonded to smoke exposed sample (2.8±0.7) and the difference was statistically significant (P<0.05). CONCLUSION: Cigarette smoke consumption has significant effects on the SBS of orthodontic brackets. SBS levels were significantly lower in the smoke exposure groups and the lowest values corresponded to the cigarette smoke exposed metallic brackets.

High risk of septic complications following surgery for Crohn's disease in patients with preoperative anaemia, hypoalbuminemia and high CRP.

AIM: Bowel resection in Crohn's disease still has a high rate of complications due to risk factors including immune suppression, malnutrition and active inflammation or infection at the time of operating. In this study, we use serological levels and inflammatory markers to predict the potential of complications in patients undergoing resections for complicated Crohn's disease. METHODS: All patients undergoing laparoscopic bowel resection for Crohn's disease from 5th of November 2012 to 11th of October 2017 were included in this retrospective observational study. Patients were divided into 4 groups scoring 0, 1, 2 or 3 depending on their pre-operative haemoglobin concentration (Hb), C-reactive protein (CRP) and albumin (Alb) where 1 point was given for an abnormal value in each as detailed in the definitions. They were then grouped into a low risk group comprised of those scoring 0 and 1, and a high risk group for those scoring 2 and 3 and data was collected to compare outcomes and the incidence of septic complications. RESULTS: Seventy-nine patients were included. Eleven (13.9%) and 2 (2.5%) patients had 2 or 3 abnormal values of CRP, Alb and Hb and were categorized as high risk. High risk patients had a significantly higher rate of post-operative septic complications (30.7%) compared with low risk patients (10.6%) p value < 0.0001. CONCLUSION: Pre-operative CRP, haemoglobin and albumin can serve as predictors of septic complications after surgery for Crohn's disease and can therefore be used to guide pre-operative optimisation and clinical decision-making.

Three-dimensional evaluation of the holographic projection in digital dental model superimposition using HoloLens device.

OBJECTIVE: To assess validity and reliability of palatal superimposition of holograms of 3D digital dental models using a customized software, (Ortho Mechanics Sequential Analyzer OMSA), installed on Microsoft HoloLens device as compared to the OMSA application running on a regular computer screen. METHODS: The sample consisted of pre- and post-treatment digital maxillary dental models of 20 orthodontic cases (12.3 ± 1.9 years) treated by rapid maxillary expansion (two turns per day). For each case, the pre- and post-treatment digital models were superimposed using hand gestures for marking the dental models holograms in mixed reality using the Microsoft HoloLens. The same models were then superimposed using the conventional landmark-based method with OMSA software running on a regular computer screen. The same set of dental arch parameters was measured on the superimposed 3D data by the two software versions for comparison. Agreement in the superimposition outcomes among the two superimposition methods was assessed using Dahlberg error (DE), concordance correlation coefficients (CCCs) using two-way ANOVA mixed model for absolute agreement and Bland-Altman analysis. RESULTS: Repeatability was acceptable for all variables based on the high values of CCCs over 0.99 with a lower 95% confidence limit over 0.95 for any variable. The DE ranged from 0.14 mm to 0.36 mm. The absolute error did not exceed 0.5 mm for any variable. CONCLUSION: Using the depth vision capabilities of the Microsoft HoloLens, 3D digital dental models can be reliably superimposed allowing virtual assessment of orthodontic treatment outcomes.

Three-dimensional evaluation of labial alveolar bone overlying the maxillary and mandibular incisors in different skeletal classifications of malocclusion.

OBJECTIVES: The purpose of this study was to investigate differences in the thickness of the labial bone overlying the maxillary and mandibular incisors in class I, II, and III skeletal classifications using three-dimensional cone-beam computed tomographs (CBCT) technology. METHODS: Pretreatment CBCTs of 54 Caucasian subjects (44 males, 10 females) were collected from the archives of a graduate orthodontic clinic. The subjects were divided into three groups based on their skeletal classification. CBCT scans were oriented to the long axis of each maxillary and mandibular incisor from the root apex to incisal tip and the axial inclination of each incisor was measured and recorded. Labial bone thickness was measured at the apex (A) and at the midpoint (MP) on each maxillary and mandibular incisor. A linear measurement, perpendicular to the long axis, was recorded from the labial bone surface to the most anterior root surface at two points. The effects of skeletal classification, jaw, incisor position, and side on A, MP, and Inclination were evaluated using mixed-model ANOVA. A 5% significance level was used for all tests. RESULTS: Significantly greater bone thickness at the apex and midpoint was reported in class III individuals than class I or II. Central incisors had significantly greater bone thickness at both the root apex and midpoint. Significantly greater bone thickness was noted in the mandible at the level of the apex. At the level of the midpoint, significantly greater thickness was reported in the maxilla. There was a positive correlation between thickness and angle within each jaw-incisor combination for class I patients and for central incisors in class III patients. CONCLUSION: The thickness of labial alveolar bone over the incisors varies based on the underlying skeletal discrepancy in each patient. Skeletal discrepancy influences the inclination of the maxillary and mandibular incisors.

Precision of the virtual occlusal record.

OBJECTIVES: To evaluate the precision of the virtual occlusal record using the Carestream CS3600 Intraoral Scanner (Carestream Dental, Atlanta, Ga). MATERIALS AND METHODS: A total of 20 participants were recruited for this prospective study using preestablished inclusion/exclusion criteria. A complete intraoral scan and two bite registrations were obtained. The participants were instructed to bite with normal pressure when bite registrations were acquired. Contact locations, size (circumference), and intensity were identified on the maxillary first molars and canines. Agreement between contact size and intensity was assessed with intraclass correlation coefficients. Kappa statistics evaluated agreement in contact locations. Statistical significance was set at P < .05. RESULTS: All participant data were included for statistical analysis. Between the two bite registrations, nonstatistically significant differences were observed in the proportion of locations with contacts (P = .7681). A nonstatistically significant difference (-0.25 mm, P = .8416) in mean contact circumference size was observed. A statistically significant difference in mean contact intensity was observed (P = .0448). When evaluating agreement between the bite registrations, a weak correlation for size (intraclass correlation coefficient = 0.35) and intensity (intraclass correlation coefficient = 0.32) was observed as well as a moderate agreement for contact location (κ coefficient = 0.67). CONCLUSIONS: The findings suggest that the Carestream intraoral scanner software possesses adequate precision when acquiring the location and size of the contacts in bite registrations. The scanner failed to demonstrate adequate precision when acquiring contact intensities in bite registrations. Additional research is warranted to further investigate the precision of virtual occlusal records with currently available software systems.