An artificial neural network approach for rational decision-making in borderline orthodontic cases: A preliminary analytical observational in silico study.

INTRODUCTION: Artificial intelligence (AI) technology has transformed the way healthcare functions in the present scenario. In orthodontics, expert systems and machine learning have aided clinicians in making complex, multifactorial decisions. One such scenario is an extraction decision in a borderline case. OBJECTIVE: The present in silico study was planned with the intention of building an AI model for extraction decisions in borderline orthodontic cases. DESIGN: An observational analytical study. SETTING: Department of Orthodontics, Hitkarini Dental College and Hospital, Madhya Pradesh Medical University, Jabalpur, India. METHODS: An artificial neural network (ANN) model for extraction or non-extraction decisions in borderline orthodontic cases was constructed based on a supervised learning algorithm using the Python (version 3.9) Sci-Kit Learn library and feed-forward backpropagation method. Based on 40 borderline orthodontic cases, 20 experienced clinicians were asked to recommend extraction or non-extraction treatment. The decision of the orthodontist and the diagnostic records, including the selected extraoral and intra-oral features, model analysis and cephalometric analysis parameters, constituted the training dataset of AI. The built-in model was then tested using a testing dataset of 20 borderline cases. After running the model on the testing dataset, the accuracy, F1 score, precision and recall were calculated. RESULTS: The present AI model showed an accuracy of 97.97% for extraction and non-extraction decision-making. The receiver operating curve (ROC) and cumulative accuracy profile showed a near-perfect model with precision, recall and F1 values of 0.80, 0.84 and 0.82 for non-extraction decisions and 0.90, 0.87 and 0.88 for extraction decisions. LIMITATION: As the present study was preliminary in nature, the dataset included was too small and population-specific. CONCLUSION: The present AI model gave accurate results in decision-making capabilities related to extraction and non-extraction treatment modalities in borderline orthodontic cases of the present population.

Evaluation of stresses and displacement in the craniofacial region as a reaction to bone-anchored maxillary protraction in conjugation with posterior bite plane and rapid maxillary expansion in patients with Class III malocclusion: A finite element analysis study.

INTRODUCTION: Treating a Class III malocclusion is often challenging for orthodontists. Bone-anchored maxillary protraction (BAMP) is known for achieving a significant maxillary protraction. The study aimed to evaluate the stress distribution and displacement of craniofacial bones as a reaction to the forces of BAMP, along with rapid maxillary expander and the posterior bite plane, in growing patients with skeletal Class III malocclusion using a finite element method. METHODS: An finite element model was constructed from the spiral computed tomographic images of a skull from an 11-year-old growing patient with skeletal Class III malocclusion along with BAMP, rapid maxillary expander, and the posterior bite plane. The created model had 105,189 nodes and 481,066 elements. After assigning the appropriate material properties and the boundary condition, 800 g of transverse force per side and a Class III intraoral elastic 250 g of force per side were applied to the model, and after the postprocessing, the results were obtained in the form of color bands. RESULTS: The maxilla and the attached structures were displaced and expanded transversely. The maxilla was displaced anteriorly by 0.692 mm, and the mandible was displaced backward by 0.204 mm in the sagittal direction. The anterior region of the maxilla and mandible, dentition, and nasal bone were rotated counterclockwise. Displacement in an upward direction was greatest at the symphysis region of the mandible. The stresses experienced by most of the bones were tensile, with the maxilla and maxillary dentition experiencing the maximum. CONCLUSIONS: Favorable changes were appreciated with maxillary forward and mandibular backward displacement, with appreciable tensile stresses in all the bones.

Evaluation of the correlation between facial index and the cortical bone thickness of the maxilla and mandible-A computer tomography based study.

OBJECTIVES: cortical bone thickness confines the position of teeth and thus can be a limiting factor for orthodontic tooth movement. The study is aimed to correlate the cortical bone thickness of the maxilla and mandible with that of different face types, viz; dolichofacial, brachyfacial, and mesofacial. METHODS: Forty CT scans were analysed for the face types and were grouped into dolichofacial (13), brachyfacial (13) and mesofacial (14) face types. The scans were measured for the right and left side buccal and lingual cortical bone thickness at the central incisor, first and second molar regions on both the maxilla and mandible. Other parameters like basal cortical bone thickness, height, and width of cortical bone were also measured. To determine the correlation and difference between the different parameters, the obtained data was subjected to the correlation coefficient, t test, and ANOVA statistical analysis. RESULTS: Maxillary buccal cortical bone thickness of central incisors was found to be highly correlated to facial index with a correlation coefficient of - 0.833 * *. Mandibular buccal bone thickness correlated with face type and cortical bone thickness at the central incisor, first, and second molars by-0.531 * *, - 0.474 * *, and - 0.589 * *, respectively. There was a significant difference between the right and left side cortical bone thickness (p < 0.05) and also for all the parameters amongst the different face types (p < 0.05). CONCLUSION: There exists a definite correlation between the face type and the certain anatomical measurements of cortical bone morphology. Dolichofacial face types show thin buccal cortical bone, which implies the limitation of orthodontic tooth movement in these types of individuals.

Evaluation and Comparison of the Effect of Elastomeric Chain and Stainless Steel Ligature Wire on Maxillary Orthodontic Miniscrew Failure.

CONTEXT: Orthodontic miniscrews are used for the purpose of conservation of anchorage. AIMS: The aim of the study was to evaluate the orthodontic miniscrew failure between the elastomeric chain-supported retraction and stainless steel (SS) ligature-aided retraction. SETTINGS AND DESIGN: This was a cross-sectional split mouth randomized controlled trial. MATERIALS AND METHODS: The sample (30) was divided equally among the control group and the experimental group (15 each). Miniscrews were placed between second premolar and the first molar of maxilla. The experimental group was based on the split mouth technique wherein right or left side of the maxillary arch was treated using either an elastomeric power chain (EPC) engaged to the miniscrews directly (Group 1) or an EPC engaged indirectly to miniscrews with the help of SS ligature wire (Group 2). In control group, implants were placed in maxilla without any retraction force. Clinical signs of inflammation was assessed at the following interval; 7th day, 14th day, 1st month, 2nd month, and at the time of removal of implant. STATISTICAL ANALYSIS USED: Kruskal-Wallis ANOVA test was used. RESULTS: Mean rank of gingival inflammation was 28.33 at the 1st-month interval in Group 1 and inflammation remained high in the this group for all time intervals in comparison to Group 2. Group 2 showed highest mean rank of inflammation of 26.10 at 7th day. In control group, the inflammation remained low at all the time intervals. Moreover, the difference noted was statistically significant. CONCLUSIONS: The gingival inflammation around the peri-implant tissue with the application of EPC at various interval remained high in comparison to the EPC with SS group. The gingival inflammation in the control group was very less, and it remained less throughout the different time periods.

Evaluation of stress generation on the cortical bone and the palatal micro-implant complex during the implant-supported en masse retraction in lingual orthodontic technique using the FEM: Original research.

Background. This study aimed to evaluate and analyze the distribution of stresses on the palatal micro-implants and the cortical bone at the micro-implant site with optimal orthodontic retraction force in lingual orthodontics. Methods. ANSYS 12.1 software was used to construct the finite element model of the maxillary bone, teeth and the periodontal ligament along with the lingual bracket set-up with wire and the micro-implant. Six- and 8-mm micro-implants were constructed. The final model consisted of 99190 nodes and 324364 elements. A 200-gram of retraction force was applied from the micro-implant to the anterior retraction hook. The micro-implant was embedded between the second premolar and the first molar. Hyper-view software was used to get the results in X-Y-Z dimensions. Results. The maximum von Mises stresses detected were 52.543 MPa for 6-mm micro-implant and 54.489 MPa for 8-mm micro-implant. Maximum stress was at the neck of the micro-implant. The 8-mm implant model showed 6×10-3 mm of lingual displacement. The least displacement of 1×10-3 mm was noticed for both the implant models in the apico-occlusal direction. The maximum von Mises stresses in the cortical bone at the micro-implant site was 18.875 MPa for 6-mm micro-implant and 21.551 MPa for 8-mm micro-implant. Conclusion. Six-mm micro-implant can be the choice for the implant-supported lingual orthodontic retraction as it produced minimal stresses on the cortical bone, and the initial stress displacements produced on the micro-implant were also minimal.

Evaluation of initial displacement and stresses in the maxillary dentition following en masse retraction using fixed lingual appliance and micro-implants: A finite element analysis.

OBJECTIVE: To evaluate and compare the stress and displacement pattern between conventional and micro-implant supported retraction in lingual orthodontic system. MATERIALS AND METHODS: A finite element model of the maxilla, teeth, periodontal ligament, lingual-orthodontic appliance and a micro-implant complex was constructed using ANSYS 12.1 software. Two sizes of micro-implants, 6mm and 8mm, were constructed producing a simulated model of 99,190 nodes and 32,4364 elements. A retraction force of 200g was applied from an anterior retraction hook to the molar tube in the conventional model and from the micro-implants in the implant supported model. The initial displacement and stress patterns in the X-Y-Z axes were obtained using Hyper-view software. RESULTS: The maximum von Mises stresses in the 6mm, 8mm and conventional model were 22.164 Megapascals (MPa), 28.603MPa and 16.491MPa respectively. The bucco-lingual displacement of the maxillary anteriors was greater in the 8mm implant model with 23×10-3mm lingual displacement observed. The least lingual displacement of 11×10-3mm was noted for the conventional model while a slightly higher moderate reading of 15×10-3mm was seen in the 6mm micro-implant supported model. The maximum displacement of the periodontal ligament was noted in the 8mm micro-implant model. CONCLUSION: Within the limitations of this research, the 8mm micro-implant model displayed high initial stresses and greater initial displacement of the anterior teeth in the X-Y-Z coordinates in comparison to conventional retraction method.

Evaluation of determinants for the nickel release by the standard orthodontic brackets.

AIM: The study was aimed to assess the effect of different pH and immersion time on the amount of nickel release from simulated orthodontic appliance of 3M Unitek company. MATERIAL AND METHOD: Nickel ion release was evaluated after subjecting the brackets to the simulated artificial oral environment. In this study, 90 stainless steel brackets of 3M Unitek Company were tested by immersing them in artificial saliva of pH 4.2, pH 6.5 and pH 7.6 for a time interval of 1hour, 1 week and 1 month (T1 - 1h, T2 - 7 days, T3 - 30 days) respectively. The data was subjected for the one-way ANOVA and the post-hoc test for the statistical comparison. RESULTS: Means of 2.99±0.77, 9.53±4.26 and 12.65±2 .52 ppb (parts per billion by volume) of nickel were released for 4.2 pH at a time interval of 1hour, 7 days and 1 month respectively. Means of 5.37±2.26, 10.94±1.51 and 16.92±1.69 ppb of nickel were released for 6.5 pH at a time interval of 1hour, 7 days and 1 month respectively. A mean of 2.13±0.92, 0.74±0.54 and 18.83±1.02 ppb of nickel was released for 7.6 pH at a time interval of 1 hr, 7 days and 1 month respectively. CONCLUSION: pH of the artificial saliva significantly affected the amount of nickel release. Acidic pH was found to increase the amount of nickel release in the artificial saliva. Time duration of bracket immersion significantly affected the amount of nickel release.

Prevalence of tobacco usage and its effect on the periodontal health parameters in the mining employees and the general population - A comparative study

Objective: Comparison of the prevalence of usage of tobacco products and its effect on the periodontal health parameters of the mining laborers and the general population of Udaipur city, India. Materials and methods: the cross sectional study was performed on the sample of 980 adults including 500 mining employees and 480 subjects from the general population. The presence or absence of the tobacco products usage was noted. The ADA type III examination using the community periodontal probe was done. The data obtained was subjected to chi-square and Cramer' v statistical analysis. Results: 79.40% of the mining-employees and 61.67% of the general population used different tobacco products, the difference noted was statistically significant (p=0.000). The most common periodontal condition amongst the mining employees and the general population was the presence of calculus (39% and 35.63% respectively) followed by the 4-5mm periodontal probing depth (29.20% and 26.04% respectively). The difference spotted was significant (p=0.018). There was statistically significant difference between the tobacco users and non- users for the different periodontal conditions (p=0.000). Conclusion: the tobacco product usage was high in mining employees group. There was a positive correlation between the usage of tobacco products and the periodontal health parameters (AU)

Comparison and evaluation of stresses generated by rapid maxillary expansion and the implant-supported rapid maxillary expansion on the craniofacial structures using finite element method of stress analysis.

BACKGROUND: The study aimed to evaluate and compare the stress distribution and 3-dimensional displacements along the craniofacial sutures in between the Rapid maxillary Expansion (RME) and Implant supported RME (I-RME). METHODS: Finite element model of the skull and the implants were created using ANSYS software. The finite element model thus built composed of 537692 elements and 115694 nodes in RME model & 543078 elements and 117948 nodes with implants model. The forces were applied on the palatal surface of the posterior teeth to cause 5mm of transverse displacement on either side of the palatal halves, making it a total of 10mm. The stresses and the displacement values were obtained and interpreted. RESULTS: Varying pattern of stress and the displacements with both positive and negative values were seen. The maximum displacement was seen in the case of plain RME model and that too at Pterygomaxillary suture and Mid-palatal suture in descending order. In the case of I-RME maximum displacement was seen at Zygomaticomaxillary suture followed by Pterygomaxillary suture. The displacements produced in all the three planes of space for the plain RME model were greater in comparison to the Implant Supported RME model. And the stresses remained high for all the sutures in case of an I-RME. CONCLUSIONS: There is a definite difference in the stress and the displacement pattern produced by RME and I-RME model and each can be used according to the need of the patient. The stresses generated in case of conventional RME were considerably less than that of the I-RME for all the sutures.

Prevalence of Need of Orthodontic Treatment in 7-16-Year-Old School Children in Udaipur City, India.

OBJECTIVE: The study aimed to estimate the need of orthodontic treatment in 7-16-year-old school children in Udaipur city, India. METHODS: This cross sectional study enrolled 1029 subjects (661 males and 368 females) belonging to Udaipur city, Rajasthan, India. Subjects who had not undergone orthodontic treatment were randomly selected. The need for orthodontic treatment was assessed using the Dental Health Component of the Index of Orthodontic Treatment Need (IOTN) by the same calibrated examiner. Collected data were quantitatively analyzed, and the difference pertaining to prevalence between males and females was measured using the chi-square test. RESULTS: A Grade 1 IOTN score was observed in 48.4% of the population. Grade 2 was observed in 22.9% of the population. A significant difference was noted for the prevalence of Grades 1, 2, and 3 between male and female children, with male children showing greater prevalence of malocclusion grades. Grades 4 and 5, which were noted less frequently, did not show a significant difference with respect to sex. CONCLUSION: A higher percentage of the sample required moderate orthodontic treatment. This necessitates proper education and motivation to undergo orthodontic treatment.

Predictability and Reliability of Different Anterio-Posterior Skeletal Discrepancy Indicators in Different Age Groups - A Cephalometric Study.

INTRODUCTION: The lateral cephalometric skeletal discrepancy indicators play a major role in diagnosing and preparing a case for orthognathic surgeries and the dentofacial corrections. AIM: The study was aimed to check the reliability and the predictability of different anterio-posterior skeletal discrepancy indicators in different age groups and to derive the most reliable indicator for the orthodontic diagnosis. MATERIALS AND METHODS: A cross-sectional study was conducted on a sample of 100 subjects including 29 adolescent (15 males and 14 females) and 71 adult (41 males and 30 females) subjects with the mean age of 19.05 ± 5.78 years. All the subjects had Angle's Class I molar relationship. The lateral cephalograms of the sample were taken under the standard setting and hand tracing of the cephalometric radiographs using a sharp 4H pencil were made on acetate tracing paper. The anterio-posterior cephalometric indicators like ß-angle, Wits appraisal (mm), Sella- Nasion plane to Point A and Point B distance (SN-AB mm) and Maxillo-Mandibular plane angle bisector to Point A and Point B distance (MM-AB mm) were measured. Intra-examiner reliability of tracings was evaluated using Intra Class Correlation (ICC) test. Mann Whitney U-test was applied for comparison of parameters between different malocclusion groups. Concurrent validity of various parameters was calculated using Cohen's kappa. A p-value <0.05 was considered statistically significant. RESULTS: The comparison of intra-examiner reliability of tracings in Angle's Class I adolescent group showed, MM-AB to have an almost perfect agreement followed by Wits. Intra-examiner reliability of tracings in Angle's Class I adult group showed moderate agreement for Wits and MM-AB showed almost perfect agreement and all the parameters showed statistically significant ICC. Comparison of parameters between adolescent and adult, Angle's Class I malocclusion group showed significant difference between adolescent and adult group for the Wits and SN-AB parameter. CONCLUSION: The final outcome of the present study revealed that, the MM-AB is highly reliable in the reproducibility and also highly valid parameter for checking antero-posterior discrepancies and ANB angle was least reliable for diagnosing the antero-posterior skeletal discrepancies.

Effect of Dental Chair Light on Enamel Bonding of Orthodontic Brackets Using Light Cure Based Adhesive System: An In-Vitro Study.

AIM: The aim of this in vitro study was to evaluate the influence of the Dental chair light on the bond strength of light cured composite resin. MATERIALS AND METHODS: Sixty therapeutically extracted human premolar teeth were randomly allocated to two groups of 30 specimens each. In both groups light cured composite resin (Transbond XT) and MBT premolar metal brackets (3M Unitek) was used to bond brackets. In group I and II light curing was done using Light-emitting diode light curing units without and with the dental chair light respectively. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength and Adhesive Remnant Index (ARI) scores. Data was subjected to Mann Whitney U statistical test. RESULTS: Results indicated that there was significantly higher shear bond strength (7.71 ± 1.90) for the Group II (composite cured with LED and dental chair light) compared with Group I (composite cured with LED LCU only) (5.74 ± 1.13).the obtained difference was statistically significant. There was no statistical significant difference between ARI scores in between the groups. CONCLUSIONS: light cure bonding with dental chair light switched on will produce greater bond strength than the conventional bonding. However, the ARI score were similar to both the groups. It is advised that the inexperienced orthodontist should always switch off the dental chair light while bonding for enough working time during the bracket placement.

Evaluation of Pharyngeal Space in Different Combinations of Class II Skeletal Malocclusion.

OBJECTIVES: The study was aimed to evaluate the pharyngeal airway linear measurements of untreated skeletal class II subjects with normal facial vertical pattern in prognathic maxilla with orthognathic mandible and orthognathic maxilla with retrognathic mandible. MATERIALS AND METHOD: the sample comprised of lateral Cephalograms of two groups (30 each) of class II malocclusion variants. Group 1 comprised of class II malocclusion with prognathic maxilla and orthognathic mandible, whereas group 2 comprised of class II malocclusion with orthognathic maxilla and retrognathic mandible. Each group was traced for the linear measurements of the pharyngeal airway like the oropharynx, nasopharynx and soft palate. The obtained data was subjected to independent t test and the Mann Whitney test to check the difference between the two groups and within the groups respectively. RESULTS: there was significant difference between all the linear measurements at the soft palate region and the distance between the tip of soft palate to its counter point on the pharyngeal wall in oropharynx region (p-ppm). CONCLUSION: the pharyngeal airway for class II malocclusion with various combination in an average growth pattern adult showed significant difference. The present results suggested, that the pharyngeal airway space might be the etiological factor for different sagittal growth pattern of the jaws and probable usage of different growth modification appliance can influence the pharyngeal airway.

Finite element study on modification of bracket base and its effects on bond strength.

OBJECTIVE: This article aims to analyze the difference in stresses generated in the bracket-cement-tooth system by means of a peel load in single and double-mesh bracket bases using a three-dimensional finite element computer model. MATERIAL AND METHODS: A three-dimensional finite element model of the bracket-cement-tooth system was constructed and consisted of 40,536 bonds and 49,201 finite elements using a commercial mesh generating programmer (ANSYS 7.0). Both single and double-mesh bracket bases were modified by varying the diameter from 100-400 µm progressively, and the spacing between the mesh wires was kept at 300 µm for each diameter of wire. A peel load was applied on the model to study the stresses generated in different layers. RESULTS: In case of double-mesh bracket base, there was reduction in stress generation at the enamel in comparison to single-mesh bracket base. There was no difference in stress generated at the bracket layer between single and double-mesh bracket bases. At the impregnated wire mesh (IWM), layer stresses increased as the wire diameter of the mesh increased. CONCLUSION: Results show that bracket design modification can improve bonding abilities and simultaneously reduce enamel damage while debonding. These facts may be used in bringing about the new innovative bracket designs for clinical use.

An assessment of sexual dimorphism in relation to facial asymmetry in esthetically pleasing faces.

OBJECTIVE: The aim of the study is to detect gender-wise difference in the skeletal asymmetry in the esthetically pleasing faces. MATERIALS AND METHODS: a cross sectional study was conducted on 25 females and 25 males of age 18 -25 years using the posterior-anterior cephalograms. The selected part of grummon's frontal analysis for analyzing the vertical skeletal asymmetries, mandibular morphology, transverse asymmetry and mandibular deviation was used. The obtained data was subjected to independent student's't' test for comparing the difference between males and females. RESULTS: there was statistically significant difference between the males and females for the measurements like Gonion-Menton length for the mandibular morphology and for the transverse parameters like zygomatico frontal suture length, jular length and antegonial notch length. There was no significant difference for the sidedness of asymmetry for the males and females. CONCLUSION: frontal facial asymmetry showed sexual dimorphism with males showing greater asymmetric values than the females. The asymmetry showed right sided prominence for both the males and females. This knowledge can be utilized for planning facial reconstruction and remodeling surgeries.

Finite element study on modification of bracket base and its effects on bond strength

OBJECTIVE: This article aims to analyze the difference in stresses generated in the bracket-cement-tooth system by means of a peel load in single and double-mesh bracket bases using a three-dimensional finite element computer model. MATERIAL AND METHODS: A three-dimensional finite element model of the bracket-cement-tooth system was constructed and consisted of 40,536 bonds and 49,201 finite elements using a commercial mesh generating programmer (ANSYS 7.0). Both single and double-mesh bracket bases were modified by varying the diameter from 100-400 µm progressively, and the spacing between the mesh wires was kept at 300 µm for each diameter of wire. A peel load was applied on the model to study the stresses generated in different layers. RESULTS: In case of double-mesh bracket base, there was reduction in stress generation at the enamel in comparison to single-mesh bracket base. There was no difference in stress generated at the bracket layer between single and double-mesh bracket bases. At the impregnated wire mesh (IWM), layer stresses increased as the wire diameter of the mesh increased. CONCLUSION: Results show that bracket design modification can improve bonding abilities and simultaneously reduce enamel damage while debonding. These facts may be used in bringing about the new innovative bracket designs for clinical use. .

OBJETIVO: o objetivo do presente artigo é analisar a diferença entre as tensões geradas na interface braquete-cemento-dente por meio do teste peel load em bases de braquete de malha simples e dupla e do método de elementos finitos tridimensional. MÉTODOS: foi construído um modelo de elementos finitos do sistema composto pela interface braquete-cemento-dente. Esse modelo consistiu de 40.536 nós e 49.201 elementos finitos. A análise foi feita com a ajuda do programa ANSYS 7.0. Tanto a base de braquete de malha única quanto a de malha dupla sofreram modificações no diâmetro, que variou de 100 a 400µm, progressivamente. O espaço entre os fios das malhas foi mantido a 300µm para o diâmetro de cada fio. O teste peel load foi aplicado ao modelo para investigar as tensões geradas nas diferentes camadas. RESULTADOS: quando comparadas às bases de braquetes de malha simples, as bases de braquetes de malha dupla geraram menos tensão no esmalte dentário. Não foram detectadas diferenças entre as tensões geradas na superfície dos braquetes com bases de malha simples e dupla. Na malha de fios impregnados (MFI), houve um aumento na tensão com o aumento do diâmetro dos fios que compõem a malha. CONCLUSÃO: os resultados revelam que as modificações no desenho do braquete podem aumentar a colagem e, ao mesmo tempo, minimizar os danos causados no esmalte durante o processo de descolagem. Esses fatos podem ser utilizados no desenvolvimento de desenhos de braquetes inovadores, destinados à utilização clínica. .

Simple "TRS" Auxiliary tube for retraction of anterior segment using segmental T loop mechanics.

Segmental T loop is the most popular frictionless mechanics so far. This biomechanically sound system was designed for the Burstone's canine bracket, which can be extra inventory for the clinicians who want to practice the segmental T loop routinely. The present manuscript provides the alternate to Burstones canine bracket for the retraction of the anterior segment.

Traumatic injuries in the primary teeth of 4- to 6-year-old school children in gulbarga city, India. A prevalence study.

AIMS: The aims of the study were: to assess the prevalence of traumatic injuries to the teeth of 4- to 6-year-old children living in Gulbarga City, India, to determine prevalence of such dental traumatic injuries at the ages of 4, 5, and 6 years and to compare the prevalence of these injuries between male and female children. METHODS: A cross-sectional survey was performed. It consisted of a clinical examination of upper and lower deciduous anterior teeth by one examiner and an interview using a questionnaire with a sample of 1500 children aged 4 to 6 years who attended kindergarten and primary schools in Gulbarga city. Garcia-Godoy's (1981) classification was used to classify the traumatic injuries. Intra-examiner consistency was assessed by kappa values on tooth-by-tooth basis. The chisquare test was used to analyse any gender and age differences. RESULTS: The prevalence of traumatic dental injuries was 76.13%, of which crown fracture with enamel involvement of teeth was the most prevalent, followed by crown fracture with both enamel and dentine involvement. Significant and highly significant differences were found between boys and girls for discoloration of teeth (P<0.05), crown fracture involving enamel (P<0.001) and crown fracture involving both enamel and dentine (P<0.001). The prevalence of traumatic dental injuries in the 5-year-old children was higher than that in the 4- and 6-year-olds. The commonest cause of injury was due to a fall (60%) and in 40% of cases of traumatic injury, they occurred in a field/playground. CONCLUSIONS: The prevalence of traumatic injuries to the anterior teeth of the 4- to 6-year-olds who took part in this study was very high. There is a need to run educational programmes to increase parents' awareness of the risks of dental trauma.

Evaluation of the stresses generated by altering the bracket mesh base design in the bracket-cement-tooth continuum using the finite element method of stress analysis.

AIM: To analyze the influence of bracket base mesh geometry on the stresses generated in the tooth-cement-bracket continuum by a shear/peel load case and to compare the stress generated by three different loads (masticatory, peel, and twisting) on the bracket mesh base by employing a three-dimensional (3D) finite element computer model. METHODS: A validated 3D finite element model of the bracket-cement-tooth system was constructed consisting of 40,536 nodes and 49,201 finite elements. RESULTS: An increase in the diameter of the bracket mesh base wire resulted in a decrease in the stress at the enamel and cement. Increase in wire spacing (200 to 500 mm) increased the stresses in the enamel and cement at all wire diameters, but within the impregnated wire mesh, the major stress decreased with the increase in the wire spacing. Peel load produced comparatively less stress on enamel than masticatory and twisting force. CONCLUSION: Alteration in mesh spacing and wire diameter influences the magnitude and distribution of stresses within the bracket-cement-tooth continuum. Peel load and twisting load are best to debond the bracket since they produced minimal stress on the enamel, which is suggestive of lower chances of enamel damage.