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.

Acceptability of fully guided virtual implant planning software among dental undergraduate students.

BACKGROUND: Fully guided implant surgery as a technique is gaining popularity. It has been observed that use of surgical guides improves precision and predictability for dental implant placement. However, like any other newer technology, the acceptance of fully guided dental implant technology among users is based upon its perceived usability. This study aimed at evaluating the perception about using Virtual Implant Planning Software (VIPS) among undergraduate dental students at the university of Sharjah. METHODS: Ninety-Six dental surgery students from the University of Sharjah were included in the study. One week after the Virtual Implant Planning Software (Planmeca Romexis version 6.2 procedure, students were asked to complete a Combined technology acceptance model and the theory of planned behaviour (C-TAM TPB) questionnaire. Sixty-six students responded to the questionnaire. RESULTS: Cronbach's alpha surpassed 0.7 for perceived usefulness, perceived ease of use, perceived behavioral control, and subjective norm. Attitude and behavioural intention reported Cronbach's alpha values less than 0.7. Spearman's correlation coefficient was significant for all the constructs. Perceived ease of use explained 49%, 33%, and 42% of the variance of perceived usefulness (R2 = 0.49), attitude (R2 = 0.33), and perceived behavioral control (R2 = 0.42) respectively. Perceived usefulness explained 25%, 18%, and 23% of the variance of attitude (R2 = 0.25), behavioral intention (R2 = 0.18), and perceived behavioral control (R2 = 0.23) respectively. Attitude accounted for 25%, 33%, and 29% of the variance of behavioral intention (R2 = 0.25), perceived behavioral control (R = 0.33), and subjective norm (R = 0.29) respectively. CONCLUSION: The fully guided VIPS was acceptable by dental students specifically because of its usability. This makes VIPS a very effective tool for teaching implantology for dental students. VIPS also allows students to perform multiple repetitions of the implant planning procedure which enhances understanding and content retention.

Thermography as a non-ionizing quantitative tool for diagnosing periapical inflammatory lesions.

BACKGROUND: Thermography is a contemporary imaging modality based on acquiring and analyzing thermal data using non-contact devices. The aim of the present study was to assess the validity of thermography, compared with that of the reference-standard, for the diagnosis of periapical inflammatory lesions and to evaluate the temperature ranges for acute pulpitis with apical periodontitis (AAP), acute periapical abscess (AA) and chronic periapical abscess (CA). METHODS: AAP, AA and CA were diagnosed based on clinical and radiographic criteria. Thermographic data were acquired using the FLIR E-5 Infrared Camera. Extraoral thermal images were taken from the front and right and left sides of patients whose mouths were closed, and one intraoral thermal image was taken from the palatal perspective. Agreement in the diagnoses based on the combination of clinical and radiographic assessments and the thermographic evaluation was calculated. The temperature ranges of the three diagnostic subgroups were also measured. RESULTS: A total of 80 patients were enrolled in this study. The mean intraoral thermal image temperature for AA was 37.26 ± 0.36, that for CA was 35.03 ± 0.63 and that for AAP was 36.07 ± 0.45. The differences between the mean intraoral thermal temperatures of the three diagnostic groups were statistically significant (P < 0.001). The result of the Kappa coefficient of agreement between the combination of clinical and radiographic assessments and the thermographic evaluation was significant (P < 0.001). CONCLUSIONS: Thermography is an effective, quantitative and nonionizing approach that can be used for the diagnosis of periapical inflammatory lesions. The results of the present study indicated that the highest thermal image temperatures were recorded for AA. Thermography might be able to detect inflammatory reactions during the preclinical stage, leading to early diagnosis.

Post COVID-19 lockdown: measures and practices for dental institutes.

Resuming regular clinical activities at dental premises after the COVID-19 lockdown period or post COVID-19 is likely to be a challenge for all dental institutes. When returning to the dental practice or training, staff and students alike should abide by the new rules and regulations. In the process of controlling viral spread, clinical dental facilities face a higher risk of disease transmission among patients as well as clinical and non-clinical staff. Aerosols formation and diffusion into the surrounding air can be a real concern of viral transmission, if no protective measures are established. We aim in this review to present the currently implemented measures and propose changes in clinical dental facilities to minimize the risk of transmission. Dental professionals should be prepared to treat every patient as a suspected COVID-19 carrier and be ready to receive and manage an overwhelming number of patients. We suggest that dental practices establish a sensible workforce shift schedule, improve ventilation levels, reduce dental aerosol generating procedures, and develop a comprehensive guidance to Healthcare Workers to reduce the risk of COVID-19 transmission.

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.

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.

Autologous Bone Marrow Concentrates and Concentrated Growth Factors Accelerate Bone Regeneration After Enucleation of Mandibular Pathologic Lesions.

Stem cell therapy is a revolutionary new way to stimulate mesenchymal tissue regeneration. The platelets concentrate products started with platelet-rich plasma (PRP), followed by platelet-rich fibrin (PRF), whereas concentrated growth factors (CGF) are the latest generation of the platelets concentrate products which were found in 2011. The aim of the present study was to evaluate the potential of combining autologous bone marrow concentrates and CGF for treatment of bone defects resulting from enucleation of mandibular pathologic lesions. Twenty patients (13 males and 7 females) with mandibular benign unilateral lesions were included, and divided into 2 groups. Group I consisted of 10 patients who underwent enucleation of the lesions followed by grafting of the bony defects with autologous bone marrow concentrates and CGF. Group II consisted of 10 patients who underwent enucleation of the lesions without grafting (control). Radiographic examinations were done immediately postoperative, then at 1, 3, 6, and 12 months, to evaluate the reduction in size and changes in bone density at the bony defects. Results indicated a significant increase in bone density with respect to the baseline levels in both groups (P < 0.05). The increase in bone density was significantly higher in group I compared with group II at the 6- and 12-month follow-up examinations (P < 0.05). The percent of reduction in the defects' size was significantly higher in group I compared with group II after 12 months (P = 0.00001). In conclusion, the clinical application of autologous bone marrow concentrates with CGF is a cost effective and safe biotechnology, which accelerates bone regeneration and improves the density of regenerated bone.

CBCT analysis of bony changes associated with temporomandibular disorders.

OBJECTIVES: The aim of the present study was to compare cone-beam computerized tomography (CBCT) findings and joint space measurement in temporomandibular disorder (TMD) and non-TMD joints, and to correlate these findings with the clinical diagnosis. METHODS: The study was conducted on patients diagnosed with temporomandibular joint (TMJ) osteoarthritis or closed lock according to the Research Diagnostic Criteria for TMDs (Group IIb, IIc, and III). CBCT and clinical records of non-TMD patients who sought treatment for purposes other than TMD were used retrospectively as a control. The following radiographic criteria were assessed: flattening, osteophyte, Ely's cyst, condylar surface irregularities, and joints' space measurements. RESULTS: Osteoarthritic joints had significantly more condylar irregularities (P50.0), osteophytes (P50.0), and condylar flattening (P50.003) than non-TMD joints. Osteoarthritic joints had significantlymore superior surface irregularities (P50.0) and osteophytes (P50.006) than closed lock joints.Non-TMDjoints had significantlymore joint space (5.64+1.88) compared with osteoarthritic joints (4.57+1.97), (P50.025). The correlation among TMD, osteophytes, and flattening of the condylar surface was statistically significant (r50.331, Pv0.000). DISCUSSION: Cone-beam computerized tomography findings are significantly associated with the clinical diagnosis of TMD. Osteophytes and flattening of the condylar surface are common features of TMD.

Impact of fully guided implant planning software training on the knowledge acquisition and satisfaction of dental undergraduate students.

BACKGROUND: A majority of dental school students do not undergo hands-on clinical training in implantology in the undergraduate curriculum. Training is usually restricted to pre-implant evaluation and post-implant prostheses. Virtual implant planning software (VIPS) provides an alternative opportunity for undergraduate students to experience implant planning much before gaining hands-on experience. However, not many studies have the contribution of VIPS to the knowledge acquisition of students. We conducted a preliminary study to evaluate the knowledge acquisition of the students when exposed to a hands-on session of VIPS. We also evaluated students' satisfaction levels, when exposed to hands-on training in fully guided implant planning software. METHODS: A two-part theory lecture on fully guided implant planning was delivered to 90, 5th (final)-year dental undergraduate students by the oral radiology faculty. The students were then randomly divided into three groups. Group A was exposed to didactic lectures only. Group B was shown a video for fully guided implant planning in addition to the didactic lecture. Group C was shown a video for fully guided implant planning in addition to a didactic lecture and then performed a hands-on session of virtual implant planning under faculty guidance. Students from all groups were given an MCQ-based test. After the completion of the test students from group A and B also received VIPS hands-on training. Students from all three groups answered and a feedback questionnaire regarding their satisfaction levels with VIPS. RESULTS: The overall test score of students in Group C was higher than their colleagues in both Groups A and B and the differences were statistically significant (p = 0.01). More than 85% of the students were satisfied with the teaching approach. CONCLUSIONS: The utilization of VIPS in the training of dental undergraduate students improves their performance confirming better knowledge acquisition and content mastery.

Analysis of the Volumetric Asymmetry of the Mandibular Condyles Using CBCT.

OBJECTIVES: The aim of this study was to analyse volumetric asymmetries between the right and left condyles in relation to age, gender, and dental status. MATERIALS AND METHODS: A retrospective analysis of 150 cone beam computed tomography (CBCT) scans was conducted. A single investigator performed the volumetric analysis of the CBCT scans using Vesalius 3D software. The volumetric data were analysed in relation to the gender, age, and dental status. RESULTS: The mean right condylar volume was significantly higher (P < .01) than the left condylar volume. Right and left condylar volumes were significantly higher (P < .01) in male study participants when compared to female study participants. There was no significant difference (P = .47) in the volumetric asymmetry between the male and female study participants. The volumetric asymmetry was significantly higher (P < .01) in the older age groups when compared to the younger age groups. The volumetric asymmetry was significantly higher (P < .01) in the partially and completely edentulous patients when compared to the dentate study participants. The condylar volume on the side having a partially edentulous area was significantly lower than the condylar volume of the contralateral dentate side (P < .001). CONCLUSIONS: The volumetric asymmetry between the right and left condyle significantly increases with age and edentulousness. The result of the study encourages the clinicians to perform volumetric evaluation of the condyles in cases of radiographically evident condylar asymmetries to obtain a more accurate diagnosis.

The consequences and outcomes associated with dental implants encroaching on adjacent teeth.

BACKGROUND: Dental implant placement carries a risk of iatrogenic damage to adjacent root surfaces. PURPOSE: To classify and understand different types of trauma to the tooth root body by dental implants. MATERIALS AND METHODS: This prospective case series included 43 implants placed between February 2017 and June 2020 that had primary stability and were in a position that accidentally invaded the adjacent teeth. The type and degree of the injury were evaluated clinically and radiographically. Tenderness, mobility, and sensitivity tests of the injured teeth were conducted at different visits. Implant failure was confirmed by the presence of implant mobility during the healing period. RESULTS: Overall, 43 patients had root injuries due to dental implant surgeries. Regarding the 43 injured roots, 32 developed transient tenderness to percussion, 16 developed variable degrees of resorption in the cementum, three lost pulp sensitivity and one had persistent tenderness to percussion. No injured teeth were lost. In three patients, implant periapical lesions were confirmed radiographically as radiolucency near the apex of the involved implants. Out of the 43 implants, 11 failed and were removed within 6 months, with an implant failure rate of (25%). CONCLUSIONS: Root damage after implant surgery varies depending on the type and severity of injury. Periodic clinical and radiographical examination is necessary to monitor root resorption and implant integration and to rule out pulp necrosis.

Evaluation of different surgical approaches to remove dental implants from the maxillary sinus.

Dental implant surgery on atrophied maxilla has many risks; in some patients, simultaneous sinus lifting with implant placement must be performed to increase the chances of successful implantation; this procedure can cause implant migration. Eleven patients were diagnosed with implant migration into the maxillary sinus in four anatomical areas: the sinus floor above the alveolar bone, near the junction of the sinus and nasal floor, near the floor of the orbit, and the most posterior aspect of the sinus. Surgical removal was performed through four different direct non-endoscopic transoral approaches depending on the location of the displaced implant. Surgical challenges, surgery duration and postoperative complications were reported. The least challenging surgical intervention was noted when removing the displaced implants from the floor of the sinus through the crestal approach. More challenges were experienced during the surgical removal of anteriorly displaced implants near the roof of the orbital floor due to surgical access and the proximity of vital anatomical structures. Bleeding from the pterygoid venous plexus was profound with the posterior lateral approach. The choice of an appropriate surgical approach to retrieve displaced dental implants from the maxillary sinus depends on the location of the implant and the surrounding vital anatomical structures.

Nanoscale Thermosensitive Hydrogel Scaffolds Promote the Chondrogenic Differentiation of Dental Pulp Stem and Progenitor Cells: A Minimally Invasive Approach for Cartilage Regeneration.

PURPOSE: Several scaffolds and cell sources are being investigated for cartilage regeneration. The aim of the study was to prepare nanocellulose-based thermosensitive injectable hydrogel scaffolds and assess their potential as 3D scaffolds allowing the chondrogenic differentiation of embedded human dental pulp stem and progenitor cells (hDPSCs). MATERIALS AND METHODS: The hydrogel-forming solutions were prepared by adding ß-glycerophosphate (GP) to chitosan (CS) at different ratios. Nanocellulose (NC) suspension was produced from hemp hurd then added dropwise to the CS/GP mixture. In vitro characterization of the prepared hydrogels involved optimizing gelation and degradation time, mass-swelling ratio, and rheological properties. The hydrogel with optimal characteristics, NC-CS/GP-21, was selected for further investigation including assessment of biocompatibility. The chondrogenesis ability of hDPSCs embedded in NC-CS/GP-21 hydrogel was investigated in vitro and compared to that of bone marrow-derived mesenchymal stem cells (BMSCs), then was confirmed in vivo in 12 adult Sprague Dawley rats. RESULTS: The selected hydrogel showed stability in culture media, had a gelation time of 2.8 minutes, showed a highly porous microstructure by scanning electron microscope, and was morphologically intact in vivo for 14 days after injection. Histological and immunohistochemical analyses and real-time PCR confirmed the chondrogenesis ability of hDPSCs embedded in NC-CS/GP-21 hydrogel. CONCLUSION: Our results suggest that nanocellulose-chitosan thermosensitive hydrogel is a biocompatible, injectable, mechanically stable and slowly degradable scaffold. hDPSCs embedded in NC-CS/GP-21 hydrogel is a promising, minimally invasive, stem cell-based strategy for cartilage regeneration.

Prevalence of temporomandibular disorders discovered incidentally during routine dental examination using the Research Diagnostic Criteria for Temporomandibular Disorders.

OBJECTIVES: The aim of this study was to assess the prevalence of temporomandibular disorders (TMDs) discovered incidentally during routine dental examination, identify disease patterns, and evaluate patients' attitude toward accepting treatment. STUDY DESIGN: A total of 3009 patients were examined at the University Dental Hospital Sharjah (Sharjah, United Arab Emirates). Research Diagnostic Criteria for TMD (RDC/TMD) Axes I and II were used for assessment. Patients with acute/serious dysfunction symptoms underwent cone beam computed tomography examination. Magnetic resonance imaging was used to confirm the diagnosis of disk displacement. RESULTS: Non-self-reported TMD prevalence was 10.8% (n = 325). Among patients with TMDs, women were diagnosed more often (65.85%) (P < .05) and those between ages 25 and 45 years (65.54%) (P < .05). Axis I assessment revealed disk displacement with reduction (group IIa) was the most common (40.92%). Axis II chronic pain grade showed that 32.62% of patients with TMDs experienced chronic pain, whereas 66.77% had mild disability. Interest in pursuing treatment was indicated by 92.31% of patients. Cone beam computed tomography and magnetic resonance imaging assessments changed the primary diagnosis in 26.08% and 18.47% of cases, respectively. CONCLUSIONS: TMD screening during routine dental examination led to the diagnosis of non-self-reported TMDs, most commonly related to disk displacement with reduction. Radiographic assessment was important to confirm TMD diagnosis. Patients diagnosed with TMD during dental screening expressed interest in pursuing treatment.

Sleep medicine education and knowledge among undergraduate dental students in Middle East universities.

OBJECTIVES: The aim of this study was to assess the undergraduate dental education in sleep medicine in Middle East universities as well as the students' knowledge in this field. METHODS: A cross-sectional observational study was carried out during the period from September 2013 to April 2014.Two different questionnaires were used. A self-administered questionnaire and a cover letter were emailed and distributed to 51 randomly selected Middle East dental schools to gather information about their undergraduate sleep medicine education offered in the academic year 2012-2013.The second questionnaire was distributed to the fifth-year dental students in the 2nd Sharjah International Dental Student Conference in April 2014, to assess their knowledge on sleep medicine. A survey to assess knowledge of sleep medicine in medical education (Modified ASKME Survey) was used. RESULTS: Thirty-nine out of 51 (76%) responded to the first questionnaire. Out of the responding schools, only nine schools (23%) reported the inclusion of sleep medicine in their undergraduate curriculum. The total average hours dedicated to teaching sleep medicine in the responding dental schools was 1.2 hours. In the second questionnaire, 29.2% of the respondents were in the high score group, whereas 70.8% scored low in knowledge of sleep-related breathing disorders. DISCUSSION: Dental students in Middle East universities receive a weak level of sleep medicine education resulting in poor knowledge in this field.

Single-needle arthrocentesis (Shepard cannula) vs. double-needle arthrocentesis for treating disc displacement without reduction.

OBJECTIVES: To compare single- vs. double-needle arthrocentesis with viscosupplementation for treating disc displacement without reduction of the temporomandibular joint. METHODS: Fifty-six patients with a magnetic resonance imaging diagnosis of non-reducing disc displacement were included. Arthrocentesis with viscosupplementation was performed on patients in group I using the Y-shaped needle (Shepard cannula) technique; the standard double-needle technique was performed on patients in group II. Patients were evaluated on postoperative day 1, and 1, 3, and 6 months later, patient- and procedure-related parameters were assessed. RESULTS: In both groups, significant improvement in the baseline levels was achieved (p < 0.01). Both techniques were equally effective at reducing pain and increasing the maximal mouth opening. The single-needle technique was easier to perform and required a shorter operative time (p < 0.01). DISCUSSION: Single-needle (Shepard cannula) arthrocentesis can be an alternative to the standard technique; however, it might add to the cost of the procedure.