15. Jan. 2007
Pages: 7 - 83
no abstract available
Aim: To compare the shear bond strength of a nano-hybrid restorative material, Grandio (Voco, Cuxhaven, Germany), to that of a traditional adhesive material (Transbond XT; 3M Unitek, Monrovia, CA, USA) when bonding orthodontic brackets.
Material and methods: Forty teeth were randomly divided into 2 groups: 20 teeth were bonded with the Transbond adhesive system and the other 20 teeth with the Grandio restorative system, following manufacturer's instructions. Student t test was used to compare the shear bond strength of the 2 systems. Significance was predetermined at P ¡Ü .05.
Results: The t test comparisons (t = 0.55) of the shear bond strength between the 2 adhesives indicated the absence of a significant (P = .585) difference. The mean shear bond strength for Grandio was 4.1 ¡À 2.6 MPa and that for Transbond XT was 4.6 ¡À 3.2 MPa. During debonding, 3 of 20 brackets (15%) bonded with Grandio failed without registering any force on the Zwick recording. None of the brackets bonded with Transbond XT had a similar failure mode.
Conclusions: The newly introduced nano-filled composite materials can potentially be used to bond orthodontic brackets to teeth if its consistency can be more flowable to readily adhere to the bracket base.
The Clear Aligner represents an easy way to treat orthodontic patients when a minor tooth movement is necessary (crowding or spacing less than 4 mm) or when relapse occurs during the retention phase. During the retention phase, the Clear Aligner acts as a passive retainer but it is activated if relapse occurs. The Clear Aligner is an esthetic, efficient, comfortable, and low-cost appliance. In this article, the authors explain the indications and limitations of the Clear Aligner, as well as the laboratory and clinical protocol.
Aim: To report preliminary results of treatment with gradual repositioning of the anterior mandibular segment using distraction osteo-genesis in patients with anterior tooth crowding and/or an unfavorable anteroposterior relationship between the anterior dentoalveolar area and the skeletal base.
Methods: The following outcome measures were considered: ability of the technique to achieve the desired skeletal jaw position, resolution of the crowding, periodontal condition (recessions and probing pocket depths), temporomandibular joint symptoms, tooth sensitivity, permanent nerve injury, additional complications, and patient satisfaction. Four patients were treated.
Results: All outcome measures indicated that the therapy goal was achieved and the results maintained to date. Periodontal conditions were slightly improved. Two patients were very satisfied; 2 were only partially satisfied with the therapy. In 1 patient the root of the mandibular right first premolar was damaged during the vertical osteotomy procedure and the mandibular right central incisor did not respond to the postoperative sensitivity test. Another patient reported tension at the temporomandibular joint when chewing hard food.
Conclusion: The preliminary results are encouraging. However, larger trials are needed to acquire sufficient knowledge of the efficacy, predictability, and ideal indications for the mandibular osteo-distraction technique.
Aim: The Forsus fatigue-resistant device spring is a 3-piece telescoping compression spring used for Class II correction. The aims of this study were: (1) to measure the mean force delivered at different amounts of deflection; (2) to determine and compare the mean stiffness between loading and unloading; and (3) to determine the resilience of the fatigue-resistant device springs.
Material and methods: Twelve fatigue-resistant device springs were tested with a universal testing machine and Winrcon software, with the load cell of 100 N, crosshead speed at 0.5 mm/second. Force-deflection data during loading and unloading were recorded at 2-mm intervals up to 12 mm compression.
Results: (1) The mean force-deflection loading and unloading curves generally were linear, with a small area of hysteresis; (2) the loading mean stiffness (19.4 g/mm) was significantly greater than the unloading mean stiffness (18 g/mm), although this is clinically insignificant; (3) fatigue-resistant device springs exhibited good resiliency. A calibrated table of force-deflection of fatigue-resistant device springs is presented for clinicians to select the appropriate length of the device for the particular orthodontic force needed.
Aim: To compare the effects of 3 molar distalization appliances, the intraoral bodily molar distalizer, the Keles slider, and the acrylic cervical occipital appliance, from the viewpoint of skeletal and soft tissue changes.
Material and methods: Lateral cephalometric films taken before and immediately after distalization of 51 patients comprised the study material of this investigation. The lateral cephalograms were digitized and measured with Dolphin Imaging 9.0.
Results: The intraoral bodily molar distalizer showed the most forward movement of the lips, with respect to E-plane. The maxillary incisal proclination presented by the U1-SN angle revealed that the most prominent proclination was caused by the intraoral bodily molar distalizer, followed by the acrylic cervical occipital appliance. The appliance that showed the most vertical opening was the intraoral bodily molar distalizer, followed by the acrylic cervical occipital appliance. ANB is the only sagittal skeletal parameter with a change: an increase with the intraoral bodily molar distalizer.
Conclusion: The most prominent soft tissue profile changes were observed with the intraoral bodily molar distalizer. The acrylic cervical occipital appliance and the Keles slider generated milder changes on the profile. When selecting the appropriate method for maxillary molar distalization, the initial soft tissue profile should be considered.
Aim: Evidence-based decision making is gaining increased emphasis in medicine and dentistry. Since orthodontics is both an art and a science, not all decisions can be based solely on scientific findings. However, to the extent that orthodontics is a science and is based on the principles of scientific method, the clinician can practice evidence-based decision making. This article summarizes the results of 6 case-controlled studies on treatment changes in deep bite or open bite.
Material and methods: All studies used the Bolton Brush Growth Study as a source for untreated controls. Strategies for correction of deep bite included cervical pull headgear, bionator therapy, and Tweed edgewise mechanotherapy. Open-bite strategies included 4 premolar extraction, 4 first molar extraction, and active vertical corrector therapy. The changes in 6 variables involved in overlap of the incisor teeth (changes in the maxilla and mandible, as well as tipping and bodily movements of the maxillary and mandibular incisors) were summed at the occlusal plane.
Results: Extraction of permanent teeth influences vertical facial growth, growth of the mandible is a major factor in the correction of deep bite, and tipping of the incisor teeth is an important contributor to open-bite correction. Two clinical cases that demonstrate the application of this analysis are presented. The first case involves an open bite treated with extraction of 4 premolars, and the second is a nonextraction deep-bite case treated with a Herbst appliance, followed by fixed appliances.
Conclusion: Case-controlled studies can help practitioners decide among various treatment strategies for vertical overbite problems.
This article summarizes the treatment progress for a patient with a severe dolichofacial pattern with a convex profile, severe lip incompetency, and concomitant mouth breathing. Her maxillary occlusal plane had a cant and the maxillary and mandibular midlines were shifted 2 and 4 mm to the left side, respectively. The treatment plan summary was as follows: (1) maxillary rapid expansion for the elimination of maxillary constriction; (2) extraction of maxillary right first molar; (3) extraction of mandibular first premolars; (4) preoperative orthodontic treatment to correct dental protrusions; (5) surgical repositioning of the maxilla and mandible; and (6) postoperative orthodontic treatment and retention. Orthodontic treatment lasted a total of 28 months, with a good intercuspation and significantly improved facial esthetics at the end of treatment. The 1-year postretention lateral cephalometric measurements did not indicate any significant relapse. Dental protrusion and crowding in both jaws were eliminated. Facial and dental asymmetry was resolved and the profile was improved. The cant of the occlusal plane and the lips were corrected. Evaluation of pre- and posttreatment profiles revealed a decrease in convexity. Dentally, Class I canine and Class III molar relationships were present at the end of the treatment. Maxillary and mandibular incisors were uprighted, improving the interincisal angle and the bite relationship.
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