ABSTRACT
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.
ABSTRACT
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.
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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.
ABSTRACT
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.
