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Purpose The presented study utilized an in vitro Orthodontic SIMulator (OSIM) to study how Class II elastic configuration effects the forces and moments acting on maxillary canine teeth when using a straight archwire fixed lingual appliance. Materials and methods Maxillary in-Ovation L self-ligating brackets were bonded to anatomically shaped stainless steel teeth on OSIM. A 0.016″ × 0.022″ stainless steel straight lingual archwire was used to provide a relevant arch shape and to position simulated teeth in a passive position. A mandibular typodont was positioned above the OSIM arch in a half cusp Class II malocclusion to serve as attachment points for elastics. Four different elastic configurations were tested: 1. maxillary–buccal to mandibular-buccal; 2. maxillary–lingual to mandibular–lingual; 3. maxillary–buccal to mandibular–lingual; 4. maxillary–lingual to mandibular–buccal. A new 4.5 oz 3/16″ elastic (n = 40 per configuration) was attached to the maxillary canine and mandibular first molar teeth for each trial. Forces and moments at the maxillary canine simulated center of resistance were considered. ANOVA was used to assess the effect of elastic configuration, and pairwise comparisons using Bonferroni correction were conducted to investigate configuration differences. Results Of the thirty-four pairwise comparisons, only two were statistically insignificant. Configurations 1, 2, and 4 were found to produce over 1 N of force in the desired distal direction, whereas Configuration 3 was significantly lower at 0.65 N. Conclusions Overall, the configuration of Class II elastics had a significant effect on forces and moments at maxillary canine teeth for a simulated straight archwire fixed lingual appliance.

Purpose Recently, we developed glass fiber-reinforced plastic (GFRP) orthodontic wire made from polycarbonate and E-glass fiber. The purpose of this study was to investigate the utility of GFRP wire in a clinical orthodontic treatment setting, the typodont model was simulated with a Class I malocclusion and mild crowding (arch length discrepancy: 4.5 mm). Materials and methods GFRP round wire with a diameter of 0.45 mm (0.018 in.) was prepared using 7 μm glass fibers. As control, nickeltitanium (Ni–Ti: 0.018 inch) alloy was also evaluated. For both wire groups, we examined the difference the arch widh and the arch length in the maxillary and mandibular using superimposition of 3D virtual models before and after immersion in typodont model. We also examined the strain force and permanent deformation. Results The inclination toward the labial aspect and the major axis of the upper and lower incisors increased, respectively, after the experiment. No significant differences before and after treatment were noted between the wires. On comparing the strain force of both wires after ligating the wire (4 weeks) in the strain test, the force of the GFRP wire was slightly lower than that of the Ni–Ti wires. In addition, there was more permanent deformation in the GFRP wire than in the Ni–Ti wire (P Conclusion GFRP wire showed equivalent efficiency to that of commercial Ni–Ti wire in improving mild anterior crowding in a typodont experiment. Therefore, GFRP wire can be used in place of Ni–Ti wire during the initial leveling stage.

To assess the reliability of inter-radicular measurements taken using dental pantomograms (DPT), long cone periapical radiographs (LCPA) and cone bean computed tomography (CBCT).A typodont simulating a hypodontia patient undergoing fixed appliance treatment was used. LCPAs, DPT, I-CAT and Accuitomo CBCT images were taken and the distances between the edentulous spans were measured at the midpoint of the roots and the cemento-enamel junctions (CEJ) of adjacent teeth. The results of each modality were compared to each other to the actual inter-radicular space.The DPT overestimated inter-radicular widths by 2 mm or more [mean: 2.48; 95% confidence interval (CI): -1.09 to 6.05 mm]. The LCPA overestimated the inter-radicular widths by 1.5 mm with a 95% CI of -0.095 to 4.03 mm. The mean differences between gold standard (model) and Accuitomo was 0.57 mm (95% CI: -0.37 to 1.51 mm) for the root mean and 0.22 mm (95% CI: -0.52 to 0.96 mm) for the CEJ. This was similar to the differences between the model and I-CAT where the inter-radicular root mean difference was 0.38 mm (95% CI: -0.38 to 1.14 mm) and the CEJ mean difference was 0.21 mm (95% CI: -0.50 to 0.92 mm).The CBCT overestimated the root distance by 0.48 mm and the CEJ width by 0.22 mm, which is clinically irrelevant for implant placement. The DPT overestimated inter-radicular width by 2 mm and the LCPA by 1.5 mm and this difference may put roots of adjacent teeth at risk during implant placement.

Objective: To compare the accuracy of cone-beam CT (CBCT) with conventional horizontal and vertical parallax for the localization of ectopic maxillary canines. Design: Observational study. Methods: A typodont was constructed using human teeth embedded in radio-dense impression material, containing a simulated ectopic canine. Image sets (vertical/horizontal parallax and CBCT scans) were obtained for nine positions. A photograph confirmed the true position of the canine. Six observers used horizontal (HP) and vertical (VP) parallax techniques with conventional radiographs and the axial, coronal and sagittal CBCT views to locate the canine tip. Images were manipulated as required using proprietary software (http://www.carestream.com and http://www.i-cat.com). Intra-observer reproducibility was calculated by one observer re-evaluating the image sets after 2 months. Individual observer validity was calculated in relation to the photographic position of the canine using weighted Kappa. Differences in t...

The aim of this study was to determine whether the morphology of three different self-ligating brackets affects the accuracy of their positioning when compared with a conventionally ligating bracket.An ex vivo prospective comparison of the accuracy of positioning self-ligating brackets with conventionally ligating brackets.Orthodontic Department, Eastman Dental Institute, London, UK.Twenty-five clinicians with 2 or more years experience of bracket placement bonded four identical typodont malocclusions with Damon MX(TM), In-Ovation System R(TM) and SmartClip(TM) self-ligating brackets and also Victory Series(TM) conventionally ligating brackets. Four hundred brackets of each type were positioned. Vertical, horizontal and angular bracket position errors were assessed by reference to the FA point and FACC respectively, using digital images and image analysis software.Method error analysis showed no evidence of bias and minimal random error. The Victory Series brackets were the most accurately positioned. Although the amount of positioning error for all the self-ligating brackets was small, a greater number were positioned outside vertical and horizontal tolerance limits compared to the conventionally ligated brackets (P0·001). The Damon MX bracket type was nearly 10 times more likely to be inaccurately placed relative to the FA point compared with the Victory Series bracket. The differences relating to angular positioning error were not statistically significant (P0·05).The findings indicate that the positioning of three types of self-ligating brackets was less accurate than the conventional pre-adjusted edgewise bracket, when using a direct bonding technique. This may have implications for their clinical application.

This ex vivo study was designed to investigate Andrews' hypothesis that there is a space implication when incisors are torqued correctly. A working model was constructed to allow acrylic typodont incisors of varying known values of inclination to be substituted into the model. The arch lengths of the various 'set-ups' were measured using a reflex microscope linked to a PC. In order to quantify the space requirement of clinical relevance for adequate incisor torque, the method was repeated by substituting replicas of patients' 'natural' incisors. For both acrylic and natural incisors it was found that, as the inclination of the teeth increased, there was an increase in all arch lengths, this being greater for the natural incisors. This larger increase for the natural incisors was related not only to their increased size, but was also dependent on the morphology of the incisor. Those incisors which were parallel-sided showed the greatest increase in arch length, whereas the incisors that were relatively triangular in shape showed the smallest increase. When the inclination of an 'average' set of 21/12 is increased by 5 degrees, an increase in the arch length of approximately 1 mm may be expected.