Comparative Analysis of Stiffness of Lingual Appliances: An in Vitro Study

Objective: To analyze and compare the stiffness of different lingual appliances with different archwires. Material and Methods: The three-point bending test was used to analyze the stiffness of the lingual archwires for the different lingual systems: eBrace, Harmony, Incognito, and STb. The deflection load curve of each archwire was obtained to evaluate how the section, the material and the manufacturer affect the elasticity and stiffness characteristics of the wires. The comparison of the stiffness between different systems was carried out through a factor variance analysis with three factors (manufacturer, cross-section, and material), followed by the post-hoc Tuckey test. Results: An increase in the system's rigidity was reported as the wire section increases, regardless of the manufacturer. The stainless steel archwires have ever higher stiffness values than NiTi and TMA. The STb wires of CuNiTi material, by virtue of the characteristics of the thermal wires, have flatter and lower load-deflection curves than the NiTi wires of other manufacturers. Conclusion: Archwires section and material showed a significant influence on the stiffness of the lingual systems. Archwires of the same section and material but different manufacturers show different load-deflection curves of stiffness

Direct and Indirect Bonding Techniques: A Systematic Review

Objective: To assess the scientific evidence on direct and indirect bonding techniques to analyse the differences related to treatment time, number of appointments and number of bracket detachments. Material and Methods: The MEDLINE and Cochrane Library databases were searched through to March 2021. Reference lists from the retrieved publications were also examined. The following article types that described data on the different types of direct and indirect bonding techniques in orthodontics were included: prospective and retrospective cohort studies, case-control studies and randomized controlled clinical trials (RCCTs). Two review authors independently assessed eligibility, extracted data, and ascertained the quality of the studies. Results: The search strategy initially resulted in 824 articles, and after a careful selection comprising the inclusion criteria, 12 articles were picked for the final review, specifically 2 cohort studies, 4 case-control studies and 6 RCCTs. The methodological quality was low in 4 studies, medium in 2, and high in 6 articles. Conclusion: The evidence currently available suggests that the use of computer-aided bonding is related to a reduction in treatment time and the number of appointments compared to direct and manual indirect bonding. However, the total bonding time for computer-aided bonding technique, including digital bracket placement, was longer than for direct bonding. Further high-quality RCTs on the differences between direct and indirect bonding are necessary to determine more precise data, as well as additional advantages and disadvantages

Comparison of Bracket Position Accuracy with Different CAD/CAM Indirect Bonding Systems

Objective: To evaluate the accuracy of three different digital bracket positioning systems, comparing vertical, mesiodistal and buccolingual accuracy. Material and Methods:  The same case was sent to Orapix, Insignia, and Orthocad systems and the brackets were bonded to the malocclusion models. Damon 3 MX brackets were used with all systems and the brackets were bonded to the models with the same bonding protocol and materials. The comparison of the position of each single bracket was made with digital photography, and ImageJ software was used to find the length in pixels and then convert it to hundredths of a mm for vertical, mesiodistal and buccolingual displacement, compared to the setup. Results: Insignia System reported the average higher vertical displacement (0.28 mm), compared with the other two appliances (0.22-0.23 mm), and showed the lowest average displacement for the mesiodistal and buccolingual positioning (0.14 and 0.07 mm, respectively). However, these slight bracket positioning variations between these bonding systems were not statistically different (p>0.05). Conclusion:  The three systems analyzed were shown to be accurate in positioning the brackets, and none of them was statistically better

In Vitro Study of Tooth Surfaces After Interproximal Enamel Reduction: Extraoral Scanner and SEM Analysis

Objective: To perform a morphological evaluation concerning the extent of interproximal enamel reduction (IPR) with different manual instruments in different types of teeth and a qualitative analysis of enamel surface characteristics at the contact point before and after IPR. Material and Methods: 40 freshly extracted, caries-free, and intact human teeth were used for the study (20 bicuspids and 20 incisors) and performed IPR just on the mesial surface. The morphological variation of contact point was evaluated by superimposed the stl file, obtained thanks to an extraoral scanner, at T0 and T1 for each tooth. Two types of strip were used, Intensiv Manual Ortho Strips Coarse/Medium and Steelcarbo Horico Strips. Teeth were then cut lengthwise, removed the most apical root portion and the mesial and distal halves were gilded and observed at different magnifications. Results: The morphological variation following stripping mainly depends on the extent of the stripping, while the diameter, the type of strip and the shape of the tooth itself do not appear to be relevant. The 500X and 1500X magnifications allowed to appreciate better the characteristics of the surface of the stripped enamel and the differences with the intact enamel. All teeth treated, independently from the kind of strip used, shows deep marks and grooves in the direction of stripping. In both cases, the enamel appears significantly damaged at great magnifications . Conclusion: Stripping always and inevitably leads to a change in the shape of the contact point and is directly correlated to the amount of stripping performed. The use of polishing after the removal of enamel interproximal is necessary in all cases

In Vitro Study of Tooth Surfaces After Interproximal Enamel Reduction: Extraoral Scanner and SEM Analysis

Objective: To perform a morphological evaluation concerning the extent of interproximal enamel reduction (IPR) with different manual instruments in different types of teeth and a qualitative analysis of enamel surface characteristics at the contact point before and after IPR. Material and Methods: 40 freshly extracted, caries-free, and intact human teeth were used for the study (20 bicuspids and 20 incisors) and performed IPR just on the mesial surface. The morphological variation of contact point was evaluated by superimposed the stl file, obtained thanks to an extraoral scanner, at T0 and T1 for each tooth. Two types of strip were used, Intensiv Manual Ortho Strips Coarse/Medium and Steelcarbo Horico Strips. Teeth were then cut lengthwise, removed the most apical root portion and the mesial and distal halves were gilded and observed at different magnifications. Results: The morphological variation following stripping mainly depends on the extent of the stripping, while the diameter, the type of strip and the shape of the tooth itself do not appear to be relevant. The 500X and 1500X magnifications allowed to appreciate better the characteristics of the surface of the stripped enamel and the differences with the intact enamel. All teeth treated, independently from the kind of strip used, shows deep marks and grooves in the direction of stripping. In both cases, the enamel appears significantly damaged at great magnifications . Conclusion: Stripping always and inevitably leads to a change in the shape of the contact point and is directly correlated to the amount of stripping performed. The use of polishing after the removal of enamel interproximal is necessary in all cases

Dentoalveolar Effects Following Maxillary Expansion: Comparison Between Dental and Skeletal Anchorage

Objective: To compare the dento-alveolar effects between dental and skeletal anchored expansion devices to achieve maxillary expansion in different groups of patients: pure dental anchorage was used in growing patients and skeletal anchorage in adult patients. Linear, angular and volumetric parameters have been analysed. Material and Methods: 22 patients has been selected from the total archive of patients treated in the Orthodontics Department of the University of Ferrara, Italy, divided into 3 groups according to the appliance used to obtain the transversal maxillary correction. Digital files of the upper arch were obtained from scans performed using an intro-oral scanner before treatment (T0) and at the end of expansion (T1). Therefore, linear, angular and volumetric measurements have been performed. Results: There is a highly significant statistic variation of the 3-3, 4-4 and 6-6 diameter as a function of time. There was a statistically significant variation of the palatal vault angle and of the 6-6 distance at the cusp level as a function of time. Moreover, it appears that these parameters are reduced in the group with skeletal anchored expander. No tooth considered have encountered a statistically significant change in tip and torque values, no matter the type of RPE and the treatment time. For all patients, we have recorded the superimposition of the maxillary dental cast before and after treatment. Conclusion: In all patients, we obtained a resolution of the maxillary transverse deficit. Patients treated by pure skeletal anchored devices have recorded a less variations of palatal vault angle and the distance between first molar cusps, as if the expansion was gained more parallel. The expansion obtained showed reduced dental side effects, as tip and torque values haven’t changed in a statistically significant way

3D Assessment of the Correlation between Neonatal Morphology and Occlusal Outcomes in 5-Year-Old Patients with Complete Unilateral Cleft Lip and Palate

Objective: To exploit 3D measurement technology to determine any correlation between neonatal palate morphology and occlusal outcomes at five years in patients receiving surgery for unilateral cleft lip and palate (CLP). Material and Methods: Twenty-nine neonatal and 5-year models treated by the same surgeon using the same protocol for CLP correction were scanned using a high-resolution structured-light scanner and stored in stl format. Dedicated software was used to make linear and surface area measurements on the neonatal models, and each digitized 5-year model was assigned a Five-Year-Old (5YO) index score on three separate occasions by the same investigator. Results: Minimum, maximum, mean, standard deviation and standard error were calculated for each variable considered, and the Pearson coefficient was used to identify any correlations between neonatal variables and 5YO scores. Linear regression analysis showed that the only variable to approach significance was the posterior width of the cleft, which showed an R2 equal to 0.111, indicating that it accounts for 11% of the variability of the 5YO index. There was no other appreciable correlation between linear measurements, surface areas, or their inter-relationships. Conclusion: There is no correlation between neonatal morphological characteristics and occlusal outcomes at 5 years in CLP patients treated via the surgical protocol considered

Phonetic Alterations Caused by Different Lingual Appliances

Objective: To evaluate the differences in phonetic alterations caused by three different lingual appliances, all bonded in sequence on the same patients. Material and Methods: Lingual brackets (STb, Incognito and Harmony) were bonded from 1.3 to 2.3 with a 0.013 CuNiTi archwire. The text was formulated to evaluate the phonetic variations in a controlled context (logatomi) and more casual sentences. The recording of the text was performed at time t0 (before positioning the brackets), t1 (after positioning the brackets) and t2 (60 minutes after positioning the brackets). An ANOVA-type analysis was performed. Results: A significant correlation was confirmed between the effects of all the linguistic methods used compared to the absence of the same. The most influenced acoustic variables were the center of gravity of the acoustic spectrum of the analyzed sounds (CoG) and the number of zero crossings of the instantaneous amplitude curve of the considered signal. Conclusion: The effects deriving from the positioning of the various brackets were relatively contained: in some cases, for some subjects, for some consonants and in specific contexts, some brackets may occasionally be less invasive than others. However, no lingual system was systematically better than others regarding phonetic alterations

Correlation Between Mesio-Distal Teeth Diameters and Arch Width

Objective: To verify the existence of a correlation between the mesio-distal size of teeth and the arch width by analyzing the data separately for maxillary and mandibular arch in patients with ideal occlusion. Material and Methods: 58 patients with ideal occlusion were studied, for a total of 276 files analyzed. Dental casts were then scanned using a professional scanner (Epson Perfection v 330) and images were obtained in TIFF format at 600 dpi. All single teeth measurements were carried out for all teeth of both arches using the VAM software (Vectra, Canfield Scientific, Fairfield, NJ, USA). The repeatability and reproducibility of the measurement method were evaluated using the Gauge R&R method. In case a correlation between tooth size and arch size is found to be significant, a linear regression analysis can be applied through the following statistical relationship: y=a+b*x, where y is the result (inter-molar distance “AvgB66” or inter-canine distance “Cusp 33”), and x the specific tooth. The a and b respectively represent the intercept (point of intersection between the line and the y axis) and the slope of the line that describes the regression ratio. Results: The statistical analysis highlights a significant correlation (p<1%) between the results of the mesio-distal measurements of each tooth and the two variables considered to define the size of each arch (“AvgB66” and “Cusp 33”). Based on these results, a numerical relationship "y=a+b*x" has been extrapolated. Thus, it is possible to calculate the estimated inter-molar or inter canine distance necessary to have the teeth aligned. Conclusion: The inter-canine and inter-molar distances can be estimated starting from measuring the mesio-distal diameter of a single tooth

Comparative Analysis of Sliding Resistance of Different Lingual Systems

Objective: To analyse and compare the frictional properties of 4 lingual systems combined with two types of stainless steel archwire (0.016x0.022, 0.018x0.025) and a 0.018x0.025 TMA archwire by simulating different misalignment situations in vitro. Material and Methods: Five randomly chosen brackets from each system (e-Brace, Harmony, Incognito, and STb) were used for the measurements and to simulate an upper first premolar extraction case. The friction tests were performed using a material testing machine in combination with a specialized test rig. Results: The lowest absolute friction values were found with the 0.016x0.022 SS wire in a passive configuration. STb provided the lowest mean friction, while Harmony brackets displayed the highest friction. The TMA Beta Titanium wire showed the highest friction values, but maintained proportions similar to those of the other wires as tip and torsion increased. Conclusion: The type of bracket has a significant impact on friction, and there is a positive correlation between mesiodistal bracket width and resistance to sliding. The archwire sections and materials and the vertical displacement, also significantly affect the friction generated by the system