Evaluation of mechanical properties of three different screws for rapid maxillary expansion.

BACKGROUND: The aim of this in vitro study was the evaluation of the mechanical properties the screws for rapid maxillary expansion (RME). METHODS: Three commercially available screws for RME were tested: Leone A2620; Dentaurum Hyrax; Forestadent Palatal Split Screw. All expansion screws were 10 mm in size. For the evaluation of mechanical properties, the screws for RME were adjusted using the same maxillary dental model. An Instron 3365 testing machine with a load cell of 5 kN recorded the forces released by the screws at different amounts of activation (1, 5, 10, 15 and 20 quarters of a turn). Each type of screw was tested 10 times. Comparisons between the forces released by the different types of screws at different amounts of activation were carried out by means of analysis of Kruskal-Wallis test with post-hoc test di Tukey (P < 0.05). RESULTS: The results of this study showed that all 3 expansion devices were able to develop forces that could produce a separation of the palatine processes. The Hyrax and A2620 expanders developed force values over 20 kg and the Palatal Split screws about 16 kg. Both the A2620 and Hyrax expanders showed significantly greater amounts of forces at all the different amounts of activations with respect to the Palatal Split screw. CONCLUSIONS: All tested devices showed the capability of developing expansion forces (16-20 kg) adequate for RME. The A2620 and Hyrax expanders showed a greater level of rigidity than the Palatal Split screw.

Oral and craniofacial findings of Binder syndrome: two case reports.

Binder syndrome is a malformative midfacial alteration, known also as maxillonasal dysplasia or maxillonasal dysostosis. In this article, two cases of affected patients are reported, and the features of the condition are reviewed. One case presents a cleft lip. Hypotheses about etiology, pathogenesis, and classification of the syndrome are illustrated. This work provides a contribution for the delineation of a differential diagnostic procedure.

Orthodontic forces released by low-friction versus conventional systems during alignment of apically or buccally malposed teeth.

The aim of the present study was to analyse the forces released by passive stainless steel self-ligating brackets (SLBs) and by a non-conventional elastomeric ligature-bracket system on conventional brackets ([slide ligatures on conventional brackets (SLCB)]) when compared with conventional elastomeric ligatures on conventional brackets (CLCB) during the alignment of apically or buccally malposed teeth in the maxillary arch. An experimental model consisting of five brackets was used to assess the forces released by the three different bracket-ligature systems with 0.012-inch super-elastic (SE) nickel-titanium (NiTi) wires in the presence of different amounts of apical or buccal canine misalignment of the canine (ranging from 1.5 to 6 mm). The forces released by each wire/bracket/ligature combination with the three different amounts of apical or buccal canine misalignment were tested 20 times. Comparisons between the different types of wire/bracket/ligature systems were carried out by means of analysis of variance on ranks with Dunnett's post hoc test (P < 0.05). No difference in the amount of force released in presence of a misalignment of 1.5 mm was recorded among the three systems. At 3 mm of apical misalignment a significantly greater amount of orthodontic force was released by SLB or SLCB when compared with CLCB, while no significant differences were found among the three systems at 3 mm of buccal canine displacement. When correction of a large amount of misalignment (6 mm) was attempted, a noticeable amount of force for alignment was still generated by the passive SLB and SLCB systems while no force was released in presence of CLCB.

Maxillary dental anomalies in children with cleft lip and palate: a controlled study.

OBJECTIVE: To evaluate the prevalence of dental abnormalities of the primary and permanent maxillary dentitions in children affected by unilateral (UCLP) and bilateral (BCLP) cleft of the lip and palate. METHODS: One hundred and fifty-six Caucasian patients (64 females and 92 males) affected by non-syndromic UCLP or BLCP were selected. A control sample of 1000 subjects (482 males and 518 females) without CLP was selected. All comparisons were carried out by means of z-tests on proportions. RESULTS: The prevalence rate for missing primary lateral incisors in UCLP subjects was 8.1% and it was 27.9% for the permanent lateral incisors. In BLCP subjects, the prevalence rates were 17% for the primary lateral incisors and 60% for the permanent lateral incisors. The second premolar was absent in 5.4% of UCLP subjects and in 8.8% in the BCLP sample. The statistical analysis revealed significant differences for the prevalence rates of all dental anomalies compared with the control group except for second premolar agenesis. CONCLUSIONS: In both UCLP and BCLP subjects the most prevalent missing teeth were the lateral incisors. The dental anomalies occurred predominantly in the cleft area, thus suggesting that the effect of the cleft disturbance is more local than general on the dentition.

Drilling Capability of Orthodontic Miniscrews: In Vitro Study.

The aims of this study were to assess the values and mechanical properties of insertion torque (IT) of steel miniscrews inserted in artificial bone blocks (Sawbones, Pacific Research Laboratories, Vashon, WA, USA) with different bone densities and to detect any scratches on the surface of the miniscrews after insertion. Forty self-drilling miniscrews (Leone S.p.A. ø 1.75 mm, L 8 mm) have been inserted into bone blocks that mimic different stability conditions (density: 20 PCF-pounds per cubic foot, 40 PCF, and 30 + 50 PCF with 2 mm and 4 mm of cortical bone). Before insertion and after removal, all miniscrews were inspected with a stereomicroscope 5x and a SEM to detect potential microscopic cracks. Using an electronic surgical motor (W&H Dentalwerk Bürmoos GmbH, Werner Bader Str. 1, 5111 Bürmoos, Austria), the maximum insertion torque value was registered. Stereomicroscope and SEM examination did not indicate any morphological and surface structural changes to the miniscrews, irrespective of the bone density they were inserted into. The findings showed that IT increased significantly with increasing bone density. In each artificial bone block, morphostructural analysis demonstrated the adequate mechanical properties of the self-drilling miniscrews. IT measurements indicated torque values between 6 and 10 Ncm for blocks with a density of 30 + 50 PCF, whereas the suggested values are between 5 and 10 Ncm.

Forces released by nonconventional bracket or ligature systems during alignment of buccally displaced teeth.

INTRODUCTION: The aim of this study was to analyze the forces released by 4 types of passive stainless steel self-ligating brackets and 2 nonconventional elastomeric ligature bracket systems compared with conventional elastomeric ligatures on stainless steel brackets during the alignment of buccally displaced teeth. METHODS: A model consisting of 5 brackets (from second premolar through central incisor) was used to assess the forces released by the 7 bracket-ligature systems with 0.012- or 0.014-in superelastic wires with various amounts of buccal canine displacement (1.5-6.0 mm). The comparisons between the different types of bracket-wire-ligature systems were performed with 3-way ANOVA with the Tukey post-hoc test (P <0.05). RESULTS: For buccal misalignments of 1.5 and 3.0 mm, both low-friction and conventional systems released forces for bracket alignment ranging from about 30 to 160 g. For greater buccal displacements (4.5 and 6.0 mm), the low-friction systems produced a significant magnitude of force, but it dropped to 0 g for the conventional system. CONCLUSIONS: Nonconventional elastomeric ligature bracket systems produced levels of force for tooth movement that were similar to those generated by passive self-ligating brackets.

Forces produced by different nonconventional bracket or ligature systems during alignment of apically displaced teeth.

OBJECTIVE: To analyze the forces released by four types of passive stainless steel self-ligating brackets (SLBs), and by two nonconventional elastomeric ligature-bracket systems when compared with conventional elastomeric ligatures on conventional stainless steel brackets during the alignment of apically displaced teeth at the maxillary arch. MATERIALS AND METHODS: An experimental model consisting of five brackets was used to assess the forces released by the seven different ligature-bracket systems with 0.012'' or 0.014'' superelastic nickel titanium wire in the presence of different amounts of apical displacement of the canine (ranging from 1.5 mm to 6 mm). Comparisons between the different types of bracket/wire/ ligature systems were carried out by means of ANOVA on ranks with Dunnett's post hoc test (P < .05). RESULTS: When correction of a misalignment greater than 3 mm is attempted, a noticeable amount of force for alignment is generated by passive SLBs and nonconventional elastomeric ligature-bracket systems, and a null amount of force is released in the presence of conventional elastomeric ligatures on conventional brackets. CONCLUSIONS: When minimal apical displacement is needed (1.5 mm), the differences in performance between low-friction and conventional systems are minimal. These differences become significant when correction of a misalignment of greater than 3.0 mm is attempted.

Forces released during sliding mechanics with passive self-ligating brackets or nonconventional elastomeric ligatures.

INTRODUCTION: The aim of this study was to evaluate the frictional forces generated by 4 types of passive stainless steel self-ligating brackets (SLBs) and by nonconventional elastomeric ligatures (NCEL) and conventional elastomeric ligatures (CEL) during sliding mechanics. METHODS: An experimental model consisting of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces produced by the SLBs, NCEL, and CEL with a 0.019 x 0.025-in stainless steel wire. RESULTS: Significantly smaller static and kinetic forces were generated by the SLBs and NCEL (<2 g) compared with the CEL (>500 g). No significant differences were found within the different types of SLBs, or between these and the NCEL. CONCLUSIONS: SLBs and NCEL are valid alternatives for low friction during sliding mechanics.

Forces in the presence of ceramic versus stainless steel brackets with unconventional vs conventional ligatures.

OBJECTIVE: To compare the forces resulting from four types of bracket/ligature combinations: ceramic brackets and stainless steel brackets combined with unconventional elastomeric ligatures (UEL) and conventional elastomeric ligatures (CEL) during the leveling and aligning phases of orthodontic therapy. MATERIALS AND METHODS: The testing model consisted of five 0.022-inch preadjusted brackets (second premolar, first premolar, canine, lateral incisor, and central incisor) for each of the two bracket types. The canine bracket was welded to a sliding bar that allowed for different amounts of offset in the gingival direction. The forces generated by a 0.014-inch superelastic nickel titanium wire in the presence of either the UEL or CEL bracket/ligature systems at different amounts of upward canine misalignment (1.5 mm, 3 mm, 4.5 mm, and 6 mm) were recorded. RESULTS: Significant differences were found between UEL and CEL systems for all tested variables (P < .01) with the exception of the canine misalignment of 1.5 mm. The average amount of recorded force in the presence of CEL was negligible with 3.0 mm or greater of canine misalignment. On the contrary, during alignment, a force available for tooth movement was recorded in the presence of both ceramic and stainless steel brackets when associated with UEL. CONCLUSIONS: The type of ligature used influenced the actual amount of force released by the orthodontic system significantly more than the type of bracket used (stainless steel vs ceramic).

Morphometric investigation in the skulls of young adults. A comparative study between 19th century and modern Italian samples.

OBJECTIVE: To test the hypothesis that there are no differences in the shape of the cranial complex between two samples from the same restricted geographical area and separated by almost 150 years. MATERIALS AND METHODS: A group of 35 skulls from the 19th century were selected and compared with a modern sample composed of 43 young adult subjects by means of lateral cephalograms and using a morphometric analysis. The peculiarity of this work is the uniformity of the two samples involving adults coming from the same restricted birthplace and with homogeneity for the orthodontic classification. RESULTS: Although the time spans are short, significant differences were found between the two samples. Shape changes included maxillary elongation toward the posterior region and a marked change in shape configuration in the mandible's points that shows a posterior rotation of the mandibular body. The global result of this cranial base point's movements symbolizes a tiny tendency toward closure of the cranial base angle. CONCLUSIONS: The hypothesis is rejected. Changes were evident, and environmental influences can be responsible for these changes.

Forces released by esthetic preadjusted appliances with low-friction and conventional elastomeric ligatures.

INTRODUCTION: In this in-vitro study, we compared the forces generated by 2 types of esthetic brackets (Aqua [Leone Orthodontic Products, Sesto Fiorentino, Florence, Italy] and Mystique [GAC International, Bohemia, NY]) in association with low-friction ligature systems (Slide [Leone Orthodontic Products] and Neo-Clips [GAC International], respectively) and by the same brackets combined with conventional elastomeric ligatures (CEL) during the leveling and aligning phases. METHODS: The testing model consisted of 5 esthetic ceramic 0.022-in preadjusted brackets for the second premolar, the first premolar, the canine, the lateral incisor, and the central incisor. The canine bracket was bonded to a sliding bar that allowed for various vertical positions. The forces generated by a 0.014-in superelastic nickel titanium wire, with the 2 types of esthetic low-friction systems (Aqua with Slide and Mystique with Neo-Clips) and the same esthetic brackets with CEL at various amounts of canine misalignment (1.5, 3, 4.5, and 6 mm) were recorded. RESULTS AND CONCLUSIONS: A significantly greater amount of force was released with low-friction systems when compared with CEL systems for all the tested variables (P < .05), with the exception of the 1.5-mm canine misalignment, and the 6.0-mm canine misalignment limited to Mystique with Neo-Clips. Similar forces were released with both esthetic low-friction systems. The average amount of released force with CEL was approximately zero at 3.0 mm or more of canine misalignment.

An experimental study on the forces released by ceramic preadjusted brackets with low friction vs. conventional elastomeric ligatures.

AIM: This in vitro study compared the forces generated by ceramic brackets (Aqua) in presence of low friction ligatures (Slide) and by the same brackets utilized with conventional elastomeric ligatures (CEL) during leveling and aligning phases of orthodontic therapy. MATERIALS AND METHODS: The testing model consisted of five 0.022" preadjusted brackets (second premolar, first premolar, canine, lateral incisor, and central incisor). The canine bracket was welded to a sliding bar that allowed for different vertical positions. The forces generated by means of 0.014" super elastic nickel titanium wire in presence of either low friction bracket/ligature systems or CEL at different amounts of upward canine misalignment (1.5 mm, 3 mm, 4.5 mm, and 6 mm) were recorded. RESULTS AND CONCLUSIONS: Significant differences between the low friction systems and CEL were found for all tested variables (p < 0.01) with the exception of the canine misalignment of 1.5 mm. The average amount of released force in the presence of CEL with 3.0 mm of canine misalignment or greater was approximately zero.

Maxillary arch changes during leveling and aligning with fixed appliances and low-friction ligatures.

INTRODUCTION: The aim of this study was to evaluate the changes in the transverse dimension and the perimeter of the maxillary arch produced by a low-friction system during the leveling and aligning phases of fixed appliance therapy. METHODS: The low-friction protocol consisted of a combination of preadjusted brackets, superelastic nickel-titanium archwires, and nonconventional elastomeric ligatures; it was used in 20 consecutively treated patients with mild crowding. RESULTS: Statistically significant increases were recorded for all dentoalveolar widths (with the exception of intermolar width measured lingually) and arch perimeter (3.5 mm on average). The increase in arch perimeter showed a significant negative relationship with the individual perimeter of the maxillary arch before treatment. No significant change was found for arch depth. CONCLUSIONS: The low-friction system produced statistically significant increases in the transverse dentoalveolar width and the perimeter of the maxillary arch during the leveling and aligning phases of treatment with an average duration of 6 months.

Ceramic brackets and low friction : A possible synergy in patients requiring multiple MRI scanning.

AIM: To investigate any advantages of low friction biomechanics in orthodontic patients with fixed appliances without producing metal artifacts during magnetic resonance imaging (MRI). MATERIALS AND METHODS: Frictional resistance generated by bracket-wire-ligature systems was analyzed via an experimental model that reproduced upper canine misalignment. Each sample was tested 10 consecutive times in a dry state; a total of 160 tests were carried out. We documented the frictional forces generated by a 0.012- and 0.014-inch superelastic nickel-titanium wire (SENT) with ceramic self-ligating brackets (SLB) with metal insert and ceramic monocrystalline brackets with nonconventional elastic ligatures (NCEL) in conjunction with various degrees of canine misalignment (1.5, 3.0, 4.5, and 6.0 mm). Comparisons between the frictional forces released by the two different bracket-wire-ligature systems were made by conducting 3-way analysis of variance (ANOVA) with Tukey HSD pairwise test (P < 0.005). RESULTS: We observed no clinically relevant difference between the frictional forces released by ceramic SLB and ceramic brackets in conjunction with a 0.012- and 0.014-inch SENT. Statistically significant differences were apparent with a 0.012-inch SENT at 4.5 and 6.0 mm of canine misalignment, where the SLB revealed higher frictional forces. CONCLUSIONS: Ceramic brackets with NCEL revealed frictional forces similar to those generated in conjunction with ceramic SLB, thereby helping to avoid metal artifacts in case of expected necessary MRI during orthodontic treatment with fixed appliances.

Frictional resistance in monocrystalline ceramic brackets with conventional and nonconventional elastomeric ligatures.

BACKGROUND: The objective of this study was to compare the frictional forces generated by three types of monocrystalline ceramic brackets coupled with conventional elastomeric ligatures (CEL) and nonconventional elastomeric ligatures (NCEL) during the alignment of apically displaced teeth at the maxillary arch. METHODS: All tests (a total of 480 tests) were carried out in a dry state on a universal testing machine with a testing model consisting of three 0.022-in. monocrystalline ceramic preadjusted brackets (from the maxillary right second premolar through the right central incisor). The canine bracket was bonded to a sliding bar that allowed for different vertical positions. The frictional forces generated by a 0.012- and 0.014-in. superelastic nickel titanium wire (SENT) with conventional and nonconventional ligatures at various amounts of canine misalignment (1.5, 3.0, 4.5, and 6.0 mm) were recorded. Comparisons between the different types of bracket-wire-ligature systems were carried out by means of analysis of variance on ranks with Tukey's post hoc test (P<0.05). RESULTS: No significant differences were assessed among the three types of monocrystalline brackets with NCEL when coupled with 0.012-in. SENT. Radiance brackets with NCEL coupled with 0.014-in. SENT showed significantly greater frictional force than Inspire Ice brackets and Pure brackets with NCEL. A significantly greater amount of frictional force was generated with CEL when compared with NCEL for all the tested variables, with the exception of the Pure brackets with 0.012-in. SENT at 1.5 and 3.0 mm of canine misalignment where similar frictional forces were found. CONCLUSIONS: Nonconventional elastomeric ligatures are able to reduce friction in monocrystalline ceramic brackets.

Thin-plate spline analysis of arch form in a Southern European population with an ideal natural occlusion.

The purpose of the present study was to identify the mean configuration of the clinical arch form in a sample of Southern European subjects with ideal natural occlusion by means of Procrustes analysis, and to compare the identified configuration with 10 commercially produced arch forms by means of thin-plate spline (TPS) analysis. The sample comprised the study casts of 50 subjects (26 males and 24 females). The mean age of the sample was 26 years +/- 4 years. All subjects were young Caucasian adults of Southern European ancestry, and presented with an ideal natural occlusion. The three-dimensional (3D) co-ordinates of all dental points (facial axis points) were digitized using a 3D electromagnetic digitizer. The morphometric technique of TPS analysis with permutation tests was used to compare the configurations of landmarks in the various specimens. No sexual dimorphism was found for either upper or lower arch forms when the shape of the arches was assessed independently from size. The commercially available arch form that showed the least, though statistically significant, shape difference with respect to the average calculated configuration was the Brader arch form.