Displacement and stress distribution pattern during complete mandibular arch distalization using buccal shelf bone screws - A three-dimensional finite element study.

BACKGROUND: To evaluate and compare the distribution of stress and displacement of teeth during mandibular arch distalization using buccal shelf screws. MATERIALS AND METHODS: Three three-dimensional finite element models of mandibular arch were constructed with third molars extracted. Models 1, 2, and 3 were constructed on the basis of the lever arm heights of 0 mm, 3 mm, and 6 mm, respectively, between the lateral incisor and canine. A buccal shelf screw was placed at the area in the second molar region with the initial point of insertion being inter-dental between the first and second molars and 2 mm below the mucogingival junction. MBT pre-adjusted brackets (slot size 0.022 × 0.028") were placed over the clinical crown's center with a 0.019 × 0.025" stainless-steel archwire on three models. A retraction force of 300 g was applied with buccal shelf screws and a lever arm bilaterally using nickel-titanium closed coil springs. The displacement of each tooth was calculated on X, Y, and Z axes, and the von Mises stress distribution was visualized using color-coded scales using ANSYS 12.1 software. RESULT: The maximum von Mises stress in the cortical and cancellous bones was observed in model 1. The maximum von Mises stress in the buccal shelf screw and the cortical bone decreased as the height of the lever arm increased. Applying orthodontic forces at the level of 6 mm lever arm height resulted in greater biomechanical bodily movement in distalization of the mandibular molars compared to when the orthodontic forces were applied at the level of 0 mm lever arm height. CONCLUSION: Displacement of the entire arch may be dictated by a direct relationship between the center of resistance of the whole arch and the line of action generated between the buccal shelf screw and force application points at the archwire, which makes the total arch movement highly predictable.

Effect of Mini-implant assisted Micro-osteoperforation on the rate of orthodontic tooth movement-A randomized clinical trial.

OBJECTIVE: To evaluate the effectiveness of micro-osteoperforation (MOP) over a 56-day period and to determine the influence of number of perforations on the rate of canine retraction. In addition, the amount of pain and discomfort caused by the MOP was evaluated. TRIAL DESIGN: A single-center, split-mouth, triple-blind, randomized, controlled trial. METHODS: 22 patients (18-30 years) who need fixed orthodontic treatment were recruited and randomly assigned to MOP1 and MOP2 groups. The recruited patients were divided into two groups with 1:1 allocation ratio. Randomization for the determination of experimental side and number of perforations was done using sealed envelopes. On each patient, the other side of mouth worked as control side with no MOPs. 4 months after first premolar extraction, patients in MOP1 received 3MOPs on the buccal surface of alveolar bone, whereas patients in MOP2 received three buccal and three palatal MOPs in the experimental side. The amount of canine retraction was measured every 28 days at two intervals on both sides of mouth. Pain perception was measured after 1 hr, 24 hr, 72 hr, 7 days, and 28 days of procedure. RESULTS: Result of the intra-examiner reliability using ICC is more than 0.97 (P < 0.001), indicating excellent repeatability and reliability of the measurements. The baseline characteristics between groups were similar (P > 0.05). A statistically significant difference in the rate of canine retraction on the MOP side was observed at the end of 56 days, amounting to two folds more than that of the control side. No significant difference was seen between MOP1 and MOP2 groups (P > 0.05). Mild-to-moderate pain was experienced only in first 72 hours of procedure. CONCLUSION: The study recommends that MOP procedure has substantial potential to be used as an adjunct to the routine mechanotherapy for accelerating tooth movement, as it may reduce treatment time by half in the first four weeks after the MOP procedure. TRIAL REGISTRATION: Clinical trial registry of India (CTRI/2022/12/048181).

Correction to: Employing Multivariate Statistics and Latent Variable Models to Identify and Quantify Complex Relationships in Typical Compression Studies.

During the transmission process in publishing the article online, the equal (=) sign was replaced with "0" in Equations 1 to 5. The original article has been corrected.

Employing Multivariate Statistics and Latent Variable Models to Identify and Quantify Complex Relationships in Typical Compression Studies.

The effect of storage condition (% RH) on flufenamic acid:nicotinamide (FFA:NIC) cocrystal compressibility, compactibility, and tabletability profiles was not observed after visual evaluation or linear regression analysis. However, multivariate statistical analysis showed that storage condition had a significant effect on each compressional profile. Shapiro and Heckel equations were used to determine the compression parameters: porosity, Shapiro's compression parameter (f), densification factor (Da), plastic yield pressure (YPpl), and elastic yield pressure (YPel). Latent variable models such as exploratory factor analysis, principal component analysis, and principal component regression were employed to decode complex hidden main, interaction, and quadratic effects of % RH and the compression parameters on FFA:NIC tablet mechanical strength (TMS). Statistically significant correlations between f and Da, f and YPpl, and Da and YPel supported the idea that both rearrangement and fragmentation, and plastic deformation are important to FFA:NIC TMS. To the authors knowledge, this is the first time that simultaneously operating dual mechanisms of fragmentation and plastic deformation in low and midrange compression, and midrange plastic deformation have been identified and reported. A quantitative PCR model showed that f, Da, and YPel had statistically significant main effects along with a significant antagonist storage condition-porosity "conditional interaction effect". f exhibited a 2.35 times greater impact on TMS compared to Da. The model root-mean-square error at calibration and prediction stages were 0.04 MPa and 0.08 MPa, respectively. The R2 values at the calibration stage and at the prediction stage were 0.9005 and 0.7539, respectively. This research demonstrated the need for caution when interpreting the results of bivariate compression data because complex latent inter-relationships may be hidden from visual assessment and linear regression analysis, and result in false data interpretation as illustrated in this report.

Effects of different adhesion promoters and deproteinizing agents on the shear bond strength of orthodontic brackets: An in vitro study.

OBJECTIVE: To evaluate the effects of different adhesion promoters, namely, Enhance LC, Ortho Solo, Assure Universal Bonding Resin and deproteinizing agents such as 5.25% NaOCl, 10% papain gel on the shear bond strength of orthodontic brackets. MATERIALS AND METHOD: The present study was approved by the Ethics Committee of Teerthanker Mahaveer Dental College and Research Centre, affiliated to Teerthanker Mahaveer University, Moradabad, India. Around 150 extracted sound human upper bicuspids were taken and divided into six groups. Group 1 control (37% H3PO4), Group 2 (37% H3PO4 + Ortho Solo), Group 3 (37% H3PO4 + Assure Universal Bonding Resin), Group 4 (37% H3PO4 + Enhance LC), Group 5 (5.25% NaOCl + 37% H3PO4), and Group 6 (10% papain gel + 37% H3PO4). In all the groups (n = 150) orthodontic metal brackets were bonded with TransbondTM XT and all the samples were subjected for evaluation of shear bond strength using Instron universal testing machine at a cross speed of 0.5 mm/min. The bracket failure mode was examined using Adhesive Remnant Index (ARI). The Kruskal-Wallis test and the Mann-Whitney test were used to compare the shear bond strength. The Chi-square test was used to determine significant differences in the ARI scores among the groups. The significance for all statistical tests was P < 0.05. RESULTS: Mean values of shear bond strength showed statistically significant differences between the evaluated groups (P < 0.005). The lowest and highest shear bond strength was attributed to Group 1 (control) and Group 2 (Ortho Solo), respectively. No statistically significant difference was noted for the mean ARI scores between control, adhesion promoters, and deproteinized group (P < 0.05). CONCLUSION: It was concluded that adhesion promoters and deproteinizing agents can be used to enhance the shear bond strength of orthodontic brackets. Among all the groups Ortho Solo showed the highest bond strength when used with TransbondTM XT.

Effects of different deproteinizing agents on topographic features of enamel and shear bond strength - An in vitro study.

OBJECTIVES: To evaluate and compare the effect of different enamel deproteinizing agents on topographic features of enamel and shear bond strength before acid etching. MATERIALS AND METHOD: In total, 120 sound human maxillary premolars were taken and divided into three groups: Group 1 control (37% phosphoric acid (H3PO4), Group 2, (5.25% Sodium Hypochlorite (NaOCl)+ 37% H3PO4, and Group 3, (10% Papain gel + 37% H3PO4). These groups were further divided into A and B subgroups. In subgroups 1A, 2A, and 3A (n30) topographic features were evaluated using Scanning electron microscope (SEM) at different magnifications. Insub-groups 1B, 2B, and 3B (n90) metal brackets were bonded with Transbond™ XT, and all the samples were subjected for Shear Bond Strength (SBS) evaluation using universal testing machineat a cross speed of 0.5 mm2/min. The failure mode was analyzed using adhesive remnant index (ARI). Statistical analysis was done using one-way ANOVA for the shear bond strength, and Kruskal-Wallis test followed by Mann-Whitneywas performed for ARI scores. RESULTS: SEM showed predominance of type 3 etching pattern in control Group (1A) and type 1 and type 2 in deproteinizedGroups (2A and 3A). Mean values of shear bond strength showed statistically significant differences between evaluated groups (P < 0.005). The lowest and highest shear bond strength was attributed to Group 1B (Control) and 3B (10% papain gel), respectively. Statisticallysignificant differences were noted for the mean ARI scores between control and deproteinized group (P < 0.05). CONCLUSION: 10% papain geland 5.25% NaOCl can be used as deproteinizing agents on enamel surface before acid etchingto enhance the shear bond strength of orthodontic brackets.

Severe Hypokalemia Mimicking Brain Death.

We discuss a case of a 20-year-old female who presented with history of fever, vomiting, and decreased oral intake for 10 days followed by one episode of generalized tonic-clonic seizure and altered sensorium for 5-6 h. On arrival in the emergency room, she had Glasgow Coma Scale 3 (E1V1M1), both pupils fixed and dilated, low blood pressure, low oxygen saturation, and few gasping breaths. She appeared to be brain dead and was assumed to have a very poor prognosis. Investigations revealed severe hypokalemia. She had also suffered acute hypoxic-ischemic injury to the brain. However, she recovered and was discharged about 2 weeks later.

Crystal anisotropy explains structure-mechanics impact on tableting performance of flufenamic acid polymorphs.

Anisotropic features with other crystallographic properties like d-spacing, and attachment energy (Eatt) can predict material performance during the secondary pharmaceutical processing. A newly developed state-of-the-art compression cell lodged in a powder X-ray diffractometer was used to measure anisotropic Young's moduli (YM) of flufenamic acid (FFA) polymorphs in this study. Methodology is based on the generation of a single crystal deformation in this cell, which reflects as a change in the d-spacing in the PXRD pattern. Anisotropic YM was calculated from such information gathered along different FFA planes. Measured FFA crystallographic molecular features were concatenated to understand macroscopic compaction (Heckel and Shapirao's parameters) and tableting performance. Block shaped crystals of FFA form I, and III after initial characterization with SEM, DSC, PXRD, and FTIR were compressed normal to X, Y, and Z-planes, identified from calculated PXRD pattern using the reported single crystal structure. YM of X and Y planes of form I was significantly higher than corresponding planes of form III. Z plane of form III showed significantly higher YM than that for form I. Low YM of form III can be attributed to its large d-spacing regardless of their high Eatt than form I, as well as orientation of supramolecular acid dimer (OH⋯O) homosynthon chains in the FFA planes. FFA form I stiffness was further confirmed with lower densification and higher yield pressure of deformation than form III. Clearly, form III exhibited better compressibility, compactibility, and tableting performance than form I due to favorable molecular and macroscopic features. Thus, developed anisotropic measurement approach can be used to distinguish material performance in the early development stage of the pharmaceutical processes.

Aggregate Elasticity, Crystal Structure, and Tableting Performance for p-Aminobenzoic Acid and a Series of Its Benzoate Esters.

The tableting performance for p-aminobenzoic acid (PABA) and a series of its benzoate esters with increasing alkyl chain length (methyl-, ethyl-, and n-butyl) was determined over a broad range of compaction pressures. The crystalline structure of methyl benzoate (Me-PABA) exhibits no slip systems and does not form viable compacts under any compaction pressure. The ethyl (Et-PABA) and n-butyl (Bu-PABA) esters each have a similar, corrugated-layer structure that displays a prominent slip plane and improves material plasticity at low compaction pressure. The compact tensile strength for Et-PABA is superior to that for Bu-PABA; however, neither material achieved a tensile strength greater than 2 MPa over the compression range studied. Complementary studies with powder Brillouin light scattering (BLS) show the maxima of the shear wave, acoustic frequency distribution red shift in an order consistent with both the observed tabletability and attachment energy calculations. Moreover, zero-porosity aggregate elastic moduli are determined for each material using the average acoustic frequency obtained from specific characteristics of the powder BLS spectra. The Young's moduli for Et- and Bu-PABA is significantly reduced relative to PABA and Me-PABA, and this reduction is further evident in tablet compressibility plots. PABA, however, is distinct with high elastic isotropy as interpreted from the narrow and well-defined powder BLS frequency distributions for both the shear and compressional acoustic modes. The acoustic isotropy is consistent with the quasi-isotropic distribution of hydrogen bonding for PABA. At low compaction pressure, PABA tablets display the lowest tensile strength of the series; however, above a compaction pressure of ca. 70 MPa PABA tablet tensile strength continues to increase while that for Et- and Bu-PABA plateaus. PABA displays lower plasticity relative to either ester, and this is consistent with its crystalline structure and high yield pressure determined from in-die Heckel analysis. Overall the complementary approach of using both structural and the acoustic inputs uniquely provided from powder BLS is anticipated to expand our comprehension of the structure-mechanics relationship and its role in tableting performance.

Quantitative assessment of interradicular bone density in the maxilla and mandible: implications in clinical orthodontics.

BACKGROUND: Bone density at the interradicular area plays an important role during orthodontic treatment. In view of this fact, the study was designed to quantitatively evaluate the bone density at the interradicular areas of the alveolar and basal bones of maxilla and mandible by computed tomography. METHODS: One hundred and nine computed tomographic images were randomly selected, and bone density was measured in Hounsfield units (HU) with bone mineral density software (Siemens VA20A_SP3A). The sample consisted of 78 males (mean age 29.5 years, range 20 to 40 years) and 31 females (mean age 27.6 years, range 20 to 40 years). Cortical and cancellous bone density was measured at the interradicular areas at the alveolar and basal bone levels of the maxilla and mandible, and the data was subjected to statistical analysis for comparisons. RESULTS: The highest cortical bone density was observed between the second premolar and first molar at the alveolar bone level and between the first and second molars at the basal bone level in the maxilla. Maxillary tuberosity showed the least bone density. The density of the cortical bone was greater in the mandible than in the maxilla and showed a progressive increase from the incisor to the retromolar area. The basal bone showed a higher density thanthe alveolar bone. CONCLUSION: Different qualities of the bone were found in the anatomic regions studied, which confirms the importance of knowledge of site-specific bone tissue density to correlate with various clinical findings.

Bone density and its importance in orthodontics.

BACKGROUND: Researchers have generally focused on tissue reactions occurring within the periodontal ligament and bone to find possible explanation for various clinical phenomena, with less attention being paid to the inherent bone density. Recently, regional differences in jaw anatomy and bone structure including bone density have become important issue to explain some of the variation in clinical practice with respect to tooth movement, implant success rate, anchorage loss etc. MATERIALS AND METHODS: The intent of this review is to discuss various methods and classification proposed to determine bone density in particular area and its importance in field of orthodontia. Various clinical studies and research done in relation to bone density were searched using PubMed. RESULTS AND CONCLUSION: This review endeavours to compile the research of bone density in maxilla and mandible. Many clinical studies have demonstrated relation between bone density and various clinical phenomena in dentistry. Knowledge of bone density in particular area of oral cavity may help the clinician to plan proper site for implant placement and various anchorage augmentation techniques in order to increase success rate of the treatment.

Non-extraction treatment of skeletal class II malocclusion.

Every orthodontist at some point in his clinical practice has faced the dilemma of how 'best' to manage a mild to moderate Class II malocclusion. To demonstrate the efficacy of Forsus™ Fatigue Resistant Device in the management of Class II malocclusion. A patient having Class II division 1 malocclusion with functional jaw retrusion was treated using MBT 0.022" prescription and Forsus FRD appliance. Pre- and post-treatment photographs and lateral cephalograms were taken. Cephalometric analysis was done, and results were superimposed. 7-8 months of Forsus wear obtained stable and successful results with improvement in facial profile, skeletal jaw relationship, and mild increase in IMPA. Greater forward displacement of the mandible was the predominant factor for successful treatment Class II patient. Forsus gives good results for class II management, and it would be wise to consider treating such cases by non-extraction approach rather than contemplating extractions.

Essentiality of early diagnosis of molar incisor hypomineralization in children and review of its clinical presentation, etiology and management.

Molar incisor hypomineralization (MIH) is a common developmental condition resulting in enamel defects in first permanent molars and permanent incisors. It presents at eruption of these teeth. One to four molars, and often also the incisors, could be affected. Since first recognized, the condition has been puzzling and interpreted as a distinct phenomenon unlike other enamel disturbances. Early diagnosis is essential since, rapid breakdown of tooth structure may occur, giving rise to acute symptoms and complicated treatment. The purpose of this article is to review MIH and illustrate its diagnosis and clinical management in young children. How to cite this article: Garg N, Jain AK, Saha S, Singh J. Essentiality of Early Diagnosis of Molar Incisor Hypomineralization in Children and Review of its Clinical Presentation, Etiology and Management. Int J Clin Pediatr Dent 2012;5(3):190-196.

L-carnitine in beta thalassemia.

This study was conducted to determine L-carnitine levels in regularly transfused and chelated beta thalassemia patients (n=40; mean age, 17.5+/-5.0 years). Ten age matched controls were also studied. The mean L-carnitine level in thalassemic patients was 23.71+/- 7.3 microM as compared to control 29.26+/-2.37 microM (P<0.0001). Mean carnitine was significantly lower (P=0.037) in those with ferritin greater than 2000 ng/dL (22.80+/-6.97 microM) in comparison to those with ferritin less than 2000 ng/dL (30.1+/-7.77 microM). Although carnitine levels in non vegetarians was higher (26.91+/-8.4 microM) than in vegetarians (22.34+/-6.55 microM), this difference was not statistically significant (P=0.072). We conclude that L-carnitine levels were found to be lower in thalassemics as compared to age matched controls.