Comparison of galvanic corrosion potential of metal injection molded brackets to that of conventional metal brackets with nickel-titanium and copper nickel-titanium archwire combinations.

AIM: The aim of the study is to investigate the galvanic corrosion potential of metal injection molding (MIM) brackets to that of conventional brackets under similar in vitro conditions with nickel-titanium and copper nickel-titanium archwires. MATERIALS AND METHODS: Twenty-five maxillary premolar MIM stainless steel brackets and 25 conventional stainless steel brackets and archwires, 0.16 inch, each 10 mm length, 25 nickeltitanium wires, 25 copper nickel-titanium wires were used. They were divided into four groups which had five samples each. Combination of MIM bracket with copper nickel-titanium wire, MIM bracket with nickel-titanium wire and conventional stainless steel brackets with copper nickel-titanium wire and conventional stainless steel brackets with nickel-titanium wires which later were suspended in 350 ml of 1 M lactic acid solution media. Galvanic corrosion potential of four groups were analyzed under similar in vitro conditions. Precorrosion and postcorrosion elemental composition of MIM and conventional stainless steel bracket by scanning electron microscope (SEM) with energy dispersive spectroscope (EDS) was done. RESULTS: MIM bracket showed decreased corrosion susceptibility than conventional bracket with copper nickeltitanium wire. Both MIM and conventional bracket showed similar corrosion resistance potential in association with nickel-titanium archwires. It seems that both brackets are more compatible with copper nickel-titanium archwires regarding the decrease in the consequences of galvanic reaction. The EDS analysis showed that the MIM brackets with copper nickel-titanium wires released less metal ions than conventional bracket with copper nickeltitanium wires. CONCLUSION: MIM brackets showed decreased corrosion susceptibility, copper nickel-titanium archwires are compatible with both the brackets than nickel-titanium archwires. CLINICAL SIGNIFICANCE: Clinically MIM and conventional brackets behaved more or less similarly in terms of corrosion resistance. In order to decrease the corrosion potential of MIM brackets, more precise manufacturing technique should be improved to get a more smoother surface finish.

Biomechanical and clinical considerations in correcting skeletal class II malocclusion with Forsus™.

AIM: The present case report describes the importance of understanding of biomechanical and clinical considerations in application of Forsus appliance in correction of class II skeletal malocclusion. BACKGROUND: Angle's class II malocclusion is one of the most prevailing that may be either skeletal or dental presenting with different clinical manifestations. There are number of appliances to treat such a malocclusion in a growing child. Fixed functional appliances are indicated for class II corrections in patients who report late with minimal residual growth left. CASE DESCRIPTION: A case of class II skeletal and dental malocclusion treated with preadjusted edgewise appliance supplemented with Forsus Fatigue Resistant Device (FRD) (3M Unitek Corp, California, USA) is reported. CONCLUSION: Forsus device is an effective alternative in treating moderate skeletal class II malocclusion. The Forsus FRD (3M Unitek Corp, California, USA) can be used instead of class II elastics in mild cases and in place of Herbst appliance in severe cases. Alteration of force vector by modifying the archwire as shown in this case report while applying Forsus and incorporation of 10 degree labial root torque in lower archwire will minimize the effects on dentition. Engaging modules or tubing on to the pushrod and leaving 1 to 2 mm clearance between distal end of the upper tube and L-pin as shown in this case report will significantly improve the patient compliance. CLINICAL SIGNIFICANCE: Much emphasis should be given to biomechanical considerations which were discussed in this article while treating patients with Forsus to prevent the unwanted effects. Clinical considerations and certain modifications advised in this case report should be utilized while treating class II skeletal malocclusions with Forsus appliance to eliminate the patient cooperation factor and make treatment time estimates much more accurate.

Effect of thermal recycling of metal brackets on shear and tensile bond strength.

AIM: The study was undertaken to measure the changes within the mesh pad associated with reconditioning process, measure the bond strength of new and reconditioned orthodontic brackets and correlate the changes in mesh strand diameter with changes in bond strength. MATERIAL AND METHODS: 120 clinically normal premolar teeth extracted for orthodontic reasons, were divided equally for bonding with new and recycled brackets using a no-mix type of adhesive. The mesh strand diameters of new and reconditioned brackets were evaluated with a binocular light microscope. Recycling of brackets was done using Esmadent® bracket and band reconditioner. RESULTS: The mesh strand diameter, tensile and shear bond strength of new and reconditioned brackets were evaluated statistically and the latter was found to show a significant reduction (p< 0.0001). However, the bond strength values of the reconditioned brackets were found to be well above the clinically required minimum. CONCLUSION: Reduction in mesh strand diameter, as a result of reconditioning process, does not correlate with the change in bond strength between initial and recycled bondings. CLINICAL SIGNIFICANCE: The bond strength of reconditioned brackets is adequate enough to resist the magnitude of forces generated in the mouth, throughout the duration of orthodontic treatment for successful treatment results.

Cephalometric evaluation-based on Steiner's analysis on young adults of Chhattisgarh, India.

AIM: The study was conducted to establish skeletal and dental parameters for Chhattisgarhi young adults, evaluation of variability between male and female Chhattisgarhi normal occlusion subjects and comparison of Cephalometric norms of Chhattisgarh population with Caucasians as well as other non- Caucasian groups. MATERIALS AND METHODS: A Cephalometric study of 80 Chhattisgarhi young adults (40 males and 40 females) with acceptable profile and occlusion was carried out by means of Steiner's analysis. RESULTS: In comparison to the Caucasian samples, the Chhattisgarhi samples were more protrusive skeletally and dentally and exhibited a more horizontal growth pattern than the Caucasians. The females reported with an increased incisor procumbency, prominent chin and prognathic maxilla than their male counterparts. CONCLUSION: The results of the study support the fact that a case of malocclusion cannot be treated to a template of norms which have been derived from mean values of a certain select group of subjects with excellent occlusion and harmonious facial proportions. CLINICAL SIGNIFICANCE: A case of malocclusion needs to be treated based on the individual merits and demerits of that case and not based on template of norms derived from mean values of select subject groups with ideal occlusion and proportion.