Shear bond strength of orthodontic brackets to enamel under different surface treatment conditions

The purpose of the present study was to evaluate the shear bond strength to enamel and the adhesive remnant index (ARI) of both metallic and polycarbonate brackets bonded under different conditions. Ninety bovine permanent mandibular incisors were embedded in acrylic resin using PVC rings as molds and assigned to 6 groups (n=15). In Groups 1 (control) and 3, metallic and polycarbonate orthodontic brackets were, respectively, bonded to the enamel surfaces using Transbond XT composite according to the manufacturer's recommendations. In Groups 2 and 4, both types of brackets were bonded to enamel with Transbond XT composite, but XT primer was replaced by the OrthoPrimer agent. In Groups 5 and 6, the polycarbonate bracket bases were sandblasted with 50-mm aluminum-oxide particle stream and bonded to the enamel surfaces prepared under the same conditions described in Groups 3 and 4, respectively. After bonding, the specimens were stored in distilled water at 37ºC for 24 hours and then submitted to shear bond strength test at a crosshead speed of 0.5 mm/min. The results (MPa) showed no statistically significant difference between Groups 4 and 6 (p>;0.05). Likewise, no statistically significant differences (p>;0.05) were found among Groups 1, 2, and 5, although their results were significantly lower than those of Groups 4 and 6 (

Skeletal and dental Class II malocclusion, with anterior open bite and accentuated overjet

Open bite is defined as a deficiency in normal vertical contact between antagonist teeth and may manifest in a limited region, or more rarely throughout the entire dental arch. If the lack of contact between teeth is located in the incisor and/or canine region when occlusion is in centric relation, it is called anterior open bite (AOB). Some studies have demonstrated that AOB is strongly associated with non-nutritional sucking habit. This article relates the treatment of a female African-Brazilian patient, with 20 years and 7 months of age, who presented Angle's Class II, division 1 malocclusion, AOB, accentuated overjet, lingual interposition during swallowing and difficulty with pronouncing some phonemes. Orthodontic treatment began by mounting an Edgewise Standard fixed appliance system, with a fixed palatal crib appliance and extraction of maxillary first premolars. This case was presented to the Brazilian Board of Orthodontics and Facial Orthopedics (BBO), as part of the requisites to become a BBO Diplomate

Cytotoxicity of intraoral orthodontic elastics

Aim: The present study compared in vitro four types of latex intraoral elastics (5/16 = 7.9 mm, mean load) regarding their possible cytotoxic effects. Material and Methods: The sample was allocated to four groups of 24 elastics: Group A (American Orthodontics), Group M (Morelli), Group T (TP Orthodontics), and Group U (Uniden). Cytotoxicity assays were performed using cell culture medium containing epithelioid-type cells (Hep-2 line) derived from human laryngeal carcinoma. Two methods for evaluating the cytotoxicity, the agar overlay test and "dye-uptake" test, were employed at two different moments (0 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey&apos;s test (p<0.05). Results: The results showed statistically significant difference (p<0.05) between Groups T and M, T and U, A and M, and A and U, for dye-uptake test at 0 and 24 h. No cell lysis was found in Groups T and A for the agar overlay test, whereas 80% cell lysis was found in Groups M and U after 24 h according to the Stanford&apos;s response index (RI). Conclusion: Both TP Orthodontics and American Orthodontics elastics evoked less cell lysis than Morelli and Uniden elastics

Incisor proclination and gingival recessions: is there a relationship?

test the hypothesis that there is no relationship between the amount of vestibular inclination of mandibular incisors and the appearance of gingival recession in this region. Methods: This study included 20 patients selected in accordance with the following inclusion criteria: 1. adult patients without gingival recession in the mandibular incisors before treatment (T0), 2. no previous orthodontic treatment, 3. treated without tooth extraction in the mandibular arch, 4. bonded mandibular splinting from one canine to another after the active stage of orthodontic treatment (T1), 5. no visible wear of the incisal edge of the mandibular incisors, 6. Pre- and post-treatment teleradiography and plaster casts, and plaster casts 3 years post-treatment (T2). Depending on the amount of inclination of the mandibular incisors after treatment, the sample was divided into two groups: Group 1- 10 individuals (IMPA T1-T0 &#8804; 5&#730;) and Group 2- 10 individuals (IMPA T1-T0 > 5&#730;). The measurement of length of the clinical crown (LCC) of the four mandibular incisors, distance between the incisal edge and vestibular marginal gingiva were made in plaster casts at T0, T1 and T2. Results: In spite of Group 1 presenting a reduction in LCC at T2, there was no statistically significant difference in LCC in the 3 time intervals evaluated in the two groups. Conclusions: The null hypothesis was accepted. The variation in the amount of vestibular inclination of the mandibular incisors during orthodontic treatment and 3 years after conclusion of treatment did not promote the appearance of gingival recessions in this group of patients

Cytotoxicity of intraoral orthodontic elastics

e present study compared in vitro four types of latex intraoral elastics (5/16 = 7.9 mm, mean load) regarding their possible cytotoxic effects. Material and Methods: The sample was allocated to four groups of 24 elastics: Group A (American Orthodontics), Group M (Morelli), Group T (TP Orthodontics), and Group U (Uniden). Cytotoxicity assays were performed using cell culture medium containing epithelioid-type cells (Hep-2 line) derived from human laryngeal carcinoma. Two methods for evaluating the cytotoxicity, the agar overlay test and dye-uptake test, were employed at two different moments (0 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukeys test (p<0.05). Results: The results showed statistically significant difference (p<0.05) between Groups T and M, T and U, A and M, and A and U, for dye-uptake test at 0 and 24 h. No cell lysis was found in Groups T and A for the agar overlay test, whereas 80% cell lysis was found in Groups M and U after 24 h according to the Stanfords response index (RI). Conclusion: Both TP Orthodontics and American Orthodontics elastics evoked less cell lysis than Morelli and Uniden elastics