Residents' journal review

Abstract

Poor oral hygiene has long been a problem in patients during orthodontic treatment. As a result of improper brushing and flossing, patients in braces can develop white spot lesions, which are areas of demineralized enamel. Casein phosphopeptide (CPP) and amorphous calcium phosphate (ACP) are substances used to help remineralize enamel and dentin. The authors tested the effectiveness of varnishes containing CPP and ACP in remineralizing white spot lesions. Orthodontic brackets were bonded to 120 bovine incisors. Duraphat and MI Varnish (containing CPP and ACP) were applied around the brackets according to the manufacturer’s directions. The samples were put into 8 groups: 1, control, brushing only; 2, control, brushing + mouthwash; 3, Duraphat varnish application only; 4, Duraphat + brushing; 5, Duraphat + brushing + mouthwash; 6, MI Varnish application; 7, MI Varnish + brushing; and 8, MI Varnish + brushing + mouthwash. The test specimens were stored in demineralizing saliva for 22 hours and then in remineralizing saliva for 2 hours. Optical coherence tomography was used to evaluate the enamel microstructure. The groups that received MI Varnish showed the lowest mean depth of the caries lesions. Duraphat varnish was not effective when combined with brushing only, but its potential to reduce white spot lesions was perceived when it was combined with brushing and mouthwash. This dependence was not noted with the MI Varnish. It was concluded that application of varnish containing CPP and ACP irrespective of the association with brushing and mouthwash reduced the depth of caries lesions. Reviewed by Lori Tima Orthodontists have always sought ways to prevent relapse in postorthodontic treatment patients. Since their introduction, vacuum-formed retainers have become popular and are primarily made of 2 materials: polypropylene and polyethylene polymers. However, few studies have evaluated the resistance to wear of these materials. The authors of this study aimed to clarify which material was more resistant to simulated wear. One hundred four samples were divided into 4 groups: Essix C+, Essix ACE, Duran, and Tru-Tain. All samples were polyethylene copolymers except for the Essix C+ group, which was a polypropylene polymer. They were vacuum formed according to the manufacturer's guidelines and subjected to 1000 cycles of wear simulation. A wear simulation machine was custom built to antagonize each specimen with spheres of steatite. Evaluation was carried out by using noncontact, 3-dimensional surface profilometry to determine the wear depth of each material. It was found that Essix ACE was the most resistant to wear, followed by the Duran group, the Tru-Tain group, and the Essix C+ group. Essix ACE had significantly less wear than did the Tru-Tain group, but the difference between the Duran and Tru-Tain groups was not statistically significant. It was concluded that, as a group of materials, polyethylene copolymers significantly outperformed the polypropylene materials in wear resistance. In addition, polyethylene materials have superior esthetics, since they are transparent. Although polyethylene copolymers appear to be a superior material, it is prudent to evaluate them with caution because wear is a result of many factors such as abrasion, adhesive effects of the contacting surfaces, fatigue, and corrosive effects that can hinder cross-investigation reliability. Reviewed by Michael Ponikvar An association between maxillary canine impaction (MCI) and orthodontically induced root resorption (OIRR) has not been sufficiently established. The objective of this retrospective cohort study was to compare the severity of root resorption of the maxillary incisors during orthodontic treatment in patients with surgically exposed canines and subsequent forced eruption vs patients without impactions. The sample consisted of 48 patients undergoing comprehensive orthodontic treatment with fixed appliances. Of these patients, 24 had unilateral or bilateral MCI, and 24 were matched controls without MCI. Preoperative and postoperative panoramic tomograms were used to calculate OIRR. The mean amount of root resorption ranged from 0.48 to 1.17 mm. The maxillary left central incisors showed significantly more OIRR in the impaction group, with a mean difference in resorption of 0.58 mm (P = 0.04). Subjects in the impaction group had 0.38 mm more OIRR compared with the control group with no impactions. There was no significant difference in the amount of OIRR between the impaction and the nonimpaction groups according to the multivariate analysis (P = 0.35). However, the authors did find a positive correlation between initial root length and OIRR (P <0.001). The investigation found MCI to be a weak predictor of OIRR. Studies investigating OIRR might benefit from the use of cone-beam computed tomography, since panoramic films have been shown to underestimate OIRR. Therefore, the results of this investigation should be viewed with caution. Reviewed by Brittany Carpenter