Abstract Background Few studies have focused on the impact of malocclusion on lip – tooth relationships during smiling and speech. Aim To evaluate the impact of different malocclusions on lip – tooth ...relationships during smiling and speech, using video images. Methods One hundred and three subjects with Class I (N = 31), Class II division 1 (N = 26), Class II division 2 (N = 16) and Class III malocclusions (N = 30) were asked to repeat the same sentence and then smile in front of a video camera. Nine frames were extracted from each subject’s video clip: at rest, posed smile, unposed smile and during the pronunciation of the sounds: ‘che’, ‘fa’, ‘se’, ‘chee’, ‘tee’ and ‘mee’. On each frame, up to 10 parameters describing the lip – tooth relationships were measured. Results In all frames, there were no statistically significant differences in the upper central incisor display ratios among the malocclusion groups ( p > 0.05). The buccal corridor ratio in the posed and unposed smiles did not differ significantly among the malocclusions ( p > 0.05). The most frequently visible last maxillary tooth was the first premolar in the posed smile, and the second premolar in the unposed smile. In each malocclusion group, the upper central incisor display ratio varied significantly among the nine frames and the buccal corridor ratio during the unposed smile was less than the ratio during the posed smile; although this was only significant in the Class II division 2 subjects. The smile arc was similar in all malocclusions. Conclusions In each malocclusion the upper central incisor display ratio varied significantly among the nine frames. In each group, the buccal corridor ratio during the unposed smile was less than that during the posed smile, but only the Class II division 2 group was significantly different. The smile arc did not differ among the malocclusions.
Abstract
Background
Selection of the appropriate curing time and light direction may enable the appropriate shear bond strength to be obtained and avoid enamel fracture during debonding.
Aims
To ...determine the effects of different curing times and light directions on the shear bond strengths of ceramic and stainless steel brackets.
Method
Ninety-two recently extracted, upper premolars were randomly assigned to six groups. Either stainless steel or ceramic brackets were bonded to the buccal surfaces of the teeth. Group 1, stainless steel brackets cured for 40 seconds from buccal surface; Group II, stainless steel brackets cured for 40 seconds from palatal surface; Group III, stainless steel brackets cured for 80 seconds from palatal surface; Group IV, ceramic brackets cured for 40 seconds from the buccal surface; Group V, ceramic brackets cured for 40 seconds from the palatal surface; Group VI, ceramic brackets cured for 80 seconds from the palatal surface. The shear bond strength was measured with a universal testing machine and the resin remaining after debonding scored with the Adhesive Remnant Index (ARI). The data were analysed with the one-way ANOVA, Tukey’s HSD test and the Kruskal-Wallis test. Associations between the ARI and shear bond strength were determined with Pearson’s correlation coefficient.
Results
Group IV (ceramic brackets cured for 40 seconds from buccal surface) had the highest shear bond strength (21.26 MPa) and Group II (metal brackets cured for 40 seconds from palatal surface) had the lowest shear bond strength (6.95 MPa).There was no significant difference in ARI scores among the groups. The association between the ARI scores and bond strength values was not statistically significant.
Conclusions
Curing from the buccal surface for 40 seconds gave unacceptably high shear bond strength values for both stainless steel and ceramic brackets. Lower shear bond strengths occurred when the light was directed from the palatal surface, but a shorter curing time is more likely to be preferred by clinicians. Future studies should investigate the possibility of reducing the curing time for both brackets.
The effects of bracket removal on enamel Heravi, Farzin; Rashed, Roozbeh; Raziee, Leila
Australasian Orthodontic Journal,
12/2023, Letnik:
24, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract Background Enamel cracks, which may develop during debonding orthodontic brackets, may jeopardise the integrity of the enamel and detract from the appearance of the teeth. Aim To compare the ...adhesive remnant scores (ARI), the number, lengths and directions of enamel cracks before bonding and after debonding metal orthodontic brackets with three different methods. Methods Metal brackets were bonded with a self-curing orthodontic adhesive to the buccal surfaces of 75 recently extracted upper and lower premolars. The teeth were randomly divided into three groups, and the brackets removed either with a sidecutter, a single-blade bracket remover or a two-blade bracket remover. The number, directions and lengths of the enamel cracks before bonding and after debonding were compared. The number of ‘pronounced’ cracks (i.e. cracks that could be identified with the naked eye) and the ARI scores in each group were also compared. Results After debonding, the number of enamel cracks and pronounced cracks, and the lengths of the enamel cracks increased in all groups ( p < 0.001). There were no statistically significant differences between the groups. The ARI scores and the direction of propagation of the enamel cracks were not influenced by the debonding method used ( p = 0.73). Conclusions Concerns about the enamel damage caused by the three methods of debonding justify caution. Despite widespread use of these methods, it would be sensible to search for methods that result in less enamel damage.
Abstract Background Fibre reinforced composites (FRC) can be used to join teeth as a rigid unit for anchorage purposes and/or for tooth movement. The utility of FRCs for these applications depends on ...the fracture characteristics and durability of the material under masticatory loads. Aims To evaluate the effect of simulated masticatory loads on the fracture characteristics of FRC bars joining two bicuspids. Methods Eighty extracted maxillary bicuspids were used. Pairs of bicuspids were joined with FRC bars on the buccal surfaces. The specimens were divided into two equal groups. In group A the fracture loads of the FRC bars were measured, and in group B the specimens were placed in a simulator and subjected to 4x10 5 chewing cycles, simulating a 2-year period of mastication. At the conclusion of this test the fracture loads of the FRC bars were measured in the intact specimens. All specimens were examined stereomicroscopically to determine the fracture pattern. Results There were no bond failures in group B during the simulated masticatory forces. The mean fracture loads in groups A and B were 195.8 N and 190.6 N, respectively. Stereomicroscopic examination showed that most fractures occurred at the enamel-composite interfaces in both groups. There were no significant differences between the groups in the fracture loads and fracture patterns. Conclusions Fibre reinforced composite bars bonded to bicuspids had sufficient durability to withstand the loads simulating a 2-year period of function. The fracture loads and fracture patterns of the FRC bars were not affected by the loads exerted by the simulator.
Background: This clinical trial investigated the effectiveness of two remineralizing creams on regression of white spot lesions (WSLs) after orthodontic therapy.
Materials and Methods: The study ...included patients with WSLs on their upper anterior teeth who recently completed orthodontic treatment at the Department of Orthodontics of Mashhad Dental School and two private offices. The participants were randomly assigned into three groups by treatment: (1) a 12-week regimen of a cream containing casein phosphopeptide-amorphous calcium phosphate and fluoride (MI Paste Plus); (2) a 12-week regimen of a cream containing hydroxyapatite and fluoride (Remin Pro); and (3) usual home care (control). Thirty-nine patients participated and three withdrew. The main outcomes including area, mineral content, and color of WSLs were measured at enrolment and 4, 8, and 12 weeks later, respectively. Blinding was applied for outcome assessment only. The data were analyzed by analysis of variance and repeated measures analysis at the statistical significance of P < 0.05.
Results: Over a 3-month period, the application of both MI Paste Plus and Remin Pro caused significantly greater reduction in area and significantly higher increase in mineral content of WSLs compared to the control group (P < 0.05). The appearance of WSLs improved significantly in both experimental groups (P < 0.05), but not in the control group. No side effect was observed throughout the experiment.
Conclusion: The application of either MI Paste Plus or Remin Pro was effective in reducing the area, increasing the mineral content and improving the appearance of demineralized enamel, indicating that these products could be recommended for managing postorthodontic WSLs.
Treatment of impacted canine teeth is a challenge for most clinicians, especially in adult patients with high risk of ankylosis. Conventionally, leveling and alignment of the teeth are first ...performed and after heavy arch wire placement in slot of brackets, de-impaction force is applied. However, this method has some disadvantages, such as inability to detect ankylosis of the impacted tooth until load application, risk of root resorption of incisors or necrosis of them, distortion of dental arch form, the need for early extraction of primary canines, which is esthetically unfavorable for patients, and long-term presence of fixed orthodontic appliances in the oral cavity. This study aims to introduce approach that can be easily used by busy clinicians to guide palatally impacted canines into the dental arch using a cantilever spring supported by two palatal miniscrews prior to the initiation of fixed orthodontic treatment, and report some cases treated with this technique. This technique does not have the shortcomings of the conventional technique. In addition, the total duration of treatment, and duration of presence of orthodontic appliances in the oral cavity are shorter than the conventional technique. In addition, is less technique sensitive and do not need time complex and time consuming wire bending.
Introduction: In orthodontic treatment, adequate anchorage is necessary to move the intended teeth. In some cases, just anterior teeth are malaligned, while posterior occlusion is acceptable. ...Therefore, the posterior teeth could be integrated by fiber-reinforced composite (FRC) to provide a rigid anchorage. This method proved advantageous since brackets are bonded just to anterior segment, while posterior segments remain intact.
Case description: The current article presents the orthodontic treatment of an adolescent girl with malalignment and rotation of upper incisors and canines. Posterior occlusion was admissible. Posterior anchorage was provided by FRC bars, while anterior teeth alignment was performed by routine fixed orthodontic appliances. Orthodontic treatment was completed within six months. It is worthy to note that the posterior occlusion was maintained as before treatment.
Introduction Although various aspects of smile esthetics have been considered in many studies, few of them have compared laypeople’s preferences for an esthetic smile with regard to the shape of the ...anterior teeth. The aim of this study was to evaluate the effects of the shapes of the maxillary anterior teeth in men and women on the perception of an esthetic smile by different age and sex groups of laypeople. Methods Two pamphlets, each consisting of 9 smile images that differed only in the shapes of the canines and incisors, were shown to 4 groups of judges of different ages and sexes. They were asked to rank feminine and masculine smile images according to their preferences using a 10-cell linear horizontal visual analog scale. Results Neither in the men’s nor in the women’s pamphlets were there significant differences between the scores of the 4 groups of judges to the various tooth forms. In both pamphlets, regardless of canine shape, all groups of judges gave significantly different scores to square, square-round, and round incisors so that the median of scores for square incisors was significantly lower than those of the 2 other incisor forms. Conclusions Sex and age of the laypersons did not affect their esthetic perception of the shapes of the maxillary anterior teeth. Incisor shape was the key determinant of their esthetic preferences; round incisors were the most esthetic. It is recommended to improve smile esthetics by mildly rounding the mesial and distal corners of square incisors.
The aim of this study was to evaluate the movement of impacted canines away from the roots of neighboring teeth before full-mouth bracket placement, performed by means of TADs to decrease undesired ...side effects on adjacent teeth.
The study sample consisted of 34 palatally impacted canines, being 19 in the experimental group and 15 in the control group. In the experimental group, before placement of brackets, the impacted canine was erupted by means of miniscrews. In the control group, after initiation of comprehensive orthodontics, canine disimpaction was performed by means of a cantilever spring soldered to a palatal bar. At the end of treatment, volume of lateral incisors and canine root resorption were measured and compared by means of a CBCT-derived tridimensional model. Visual Analogue Scale (VAS) score, bleeding on probing (BOP) and gingival index (GI) were recorded. Clinical success rate was also calculated.
The volume of root resorption of lateral teeth in the control group was significantly greater than in the experimental group (p < 0.001). At the end of treatment, VAS score, GI and BOP were not significantly different between the two groups.
Based on our results, it seems that disimpaction of canines and moving them to the arch can be done successfully carried out with minimal side effects by means of skeletal anchorage.
Introduction Conventional orthodontic techniques do not intrude posterior teeth effectively, and almost all methods result in anterior extrusion rather than posterior intrusion. New absolute ...anchorages (miniscrews and miniplates) are said to make posterior tooth intrusion possible. The aim of this study was to evaluate the clinical success of a new method for molar intrusion with miniscrews and its probable accompanying side effects. Material and methods Ten women with overerupted upper first molars participated in this study. Upper molar bands with brackets were cemented. Two miniscrews were placed, 1 in the mesiopalatal and another in the mesiobuccal aspect of the upper first molars; a spring made of 0.017 × 0.25-in titanium-molybdenum alloy (TMA) wire was used to apply 100 g of force through the attachments (50 g each side). Molar intrusion and external apical root resorption were evaluated by comparing parallel periapical radiographs with bite blocks at 3 intervals: beginning of treatment (T0), at the end of active treatment (T1), and 6 months after treatment completion (T2). Results The mean value of intrusion was 2.1 mm after completion of active treatment. On average, 0.4 ± 0.2 mm relapse had occurred during 6 months of retention, and the mean residual intrusion was 1.7mm, which was statistically significant. Mean root resorption of 0.3 ± 0.2 mm for palatal root and 0.4 mm for mesiobuccal and distobuccal root was measured. Conclusions Statistically significant intrusion (2.1 ± 0.9 mm) was obtained during active treatment. The mean value of relapse was 0.4 ± 0.2 mm, and the mean value for residual intrusion was 1.7 ± 0.6 mm. Minor apical root resorption occurred during treatment.
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