Expansion with transpalatal arch or continuous arch mechanics.

INTRODUCTION: This study aimed to compare the 3-dimensional force system produced by transpalatal arch (TPA) mechanics with that produced by a continuous arch (CA) on the expansion of maxillary first molars. METHODS: A patient's model with 2 molars in 4-mm crossbite had orthodontic appliances bonded to all teeth. The first and the second molars were connected to two 3-dimensional load cells to compare the forces in the transverse and anteroposterior planes (Fx and Fy) and the rotational moments (Mz) produced in both molars by the expanded TPA and by 0.016-in nickel-titanium CA. The data were evaluated using 6 independent t tests, and the net moment at the molar's center of resistance was also calculated. RESULTS: All forces and moments were different at both molars. At the first molar, CA produced Fx of 2.60 N, Fy of -0.08 N, Mz of -5.16 N·mm, and Net Mz of -5.68 N·mm, whereas the TPA produced Fx of 2.87 N, Fy of -0.60 N, Mz of -22.08 N·mm, and Net Mz of -25.09 N·mm. At the second molar, the TPA did not produce significant forces and moments, whereas the CA produced Fx of -1.00 N, Mz of 3.95 N·mm, Fy of -0.84 N, and Net Mz of -0.67 N·mm. CONCLUSIONS: Based on our findings in a clinical set up with the specific horseshoe TPA and archwire tested, with the TPA used only on the first molars and the CA used from one second molar to the other, the mechanics produced different expansion forces at the first molar. The TPA produced a larger rotational side effect on the first molar, whereas the CA produced side effects on the second molar.

Orthodontic Treatment in Adult Patient with Reduced Periodontium: A Case Report.

Patients presenting reduced periodontium represent a major concern for orthodontists. The purpose of this article is to present the clinical case of an adult patient who presented sequel of periodontal disease (diastemas) compromising her dental aesthetics. She was subjected to an orthodontic treatment with the application of light forces distant from the teeth with reduced periodontium. A periodontal support therapy was successfully implemented. The final stage of the treatment indicated satisfactory occlusal and periodontal characteristics.

Impaction of Maxillary Central Incisors: Surgical and Orthodontic Treatment--Case Report.

The aim of this paper is to report two clinical cases, which was performed with surgical exposure and orthodontic traction of a maxillary central incisors. Light forces were used during the orthodontic treatment applied on rigid wires as anchorage. It was noted that teeth presented adequate clinical crown height and gingival contours.

Influence of the vertical position of maxillary central incisors on the perception of smile esthetics among orthodontists and laypersons.

OBJECTIVE: The purpose of this study was to determine the perception of smile esthetics among orthodontists and laypeople with respect to different upper central incisor vertical positions in a frontal smile analysis. MATERIALS AND METHODS: A frontal close-up smile photo of an adult Caucasian woman was selected. The patient had healthy upper anterior dentition and had no history of orthodontic treatment. Images were altered in order to create six different central incisor vertical positions in 0.5-mm increments. All images were assessed in three different views: full smile, gingival close-up excluding incisal edges, and incisal close-up excluding gingival margins. Images were randomly assembled in an album, which was given to 120 judges: 60 orthodontists and 60 laypersons. Each rater was asked to evaluate the attractiveness of the images using the visual analog scale. The data collected were then statistically analyzed. RESULTS: The highest rated smiles showed two notable characteristics: the central-to-lateral incisal step was 1.5 mm; and the central incisor gingival margins matched the laterals, and both were 0.5 mm below the line of the canine gingival margins. The least attractive smile was the one with no step between the centrals and laterals, and with the central incisor gingival margins 1.0 mm above the canine gingival margins. CONCLUSION: The results of this study indicate that slightly extruded upper central incisors are more esthetically preferred than intruded. CLINICAL SIGNIFICANCE: The upper central incisors are the key determinant in evaluating smile esthetics, and thus, the assessment of their ideal vertical positioning is an aspect of paramount importance.

Influence of maxillary incisor edge asymmetries on the perception of smile esthetics among orthodontists and laypersons.

INTRODUCTION: Our objective was to determine the perception of smile esthetics among orthodontists and laypeople with respect to asymmetries on the maxillary incisor edges in a frontal smile analysis. METHODS: Two frontal close-up smile photos of 2 women, 1 white and 1 Afro-Brazilian, were selected for this study. Both smiles displayed healthy maxillary anterior dentitions. The images were digitally altered to create tooth wear on the maxillary left central and lateral incisors in 0.5-mm increments. The final images were randomly assembled into a photo album that was given to 120 judges, 60 orthodontists and 60 laypersons. Each rater was asked to evaluate the attractiveness of the images with visual analog scales. The data collected were statistically analyzed with 1-way analysis of variance with the Tukey post-hoc test and the unpaired Student t test. RESULTS: The most attractive smiles in both types of smiles were those without asymmetries and the 0.5-mm wear in the lateral incisor. In general, tooth wear was considered unattractive by both groups of raters following a pattern: the more tooth wear, the more unattractive the smile; tooth wear in the central incisor was considered more unattractive than in the lateral incisor. For both group of raters, 0.5 mm of wear in the central incisor was considered unattractive, whereas the thresholds for lateral incisor discrepancies were 0.5 mm for orthodontists and 1.0 mm for laypersons. CONCLUSIONS: The result of this study corroborates the clinical assumption that symmetry between the maxillary central incisors is a paramount goal for esthetic treatments.

Preclinical in vitro study of streptococcus mutans accumulation in three fixed retainer designs: Microbiological assay.

The use of fixed retainers in the lower arch is frequent; however, its presence increases the accumulation of biofilm and dental calculus. The objective of this research was to evaluate, in vitro, the accumulation of Streptococcus mutans (S. mutans) in 3 designs of fixed retainers. Nine models were reproduced in heat-cured acrylic resin and divided into groups: straight retainer (SR), retainer with vertical strap (RVS), retainer with horizontal strap (RHS). The accumulation of S. mutans was assessed using the MTT assay (3-4,5-dimethyl-thiazol-2-yl-2,5-diphenyltetrazolium bromide) and then measured using an automated reader. The RHS group showed less biofilm accumulation compared to the other groups (p<0.05). The distance between the tooth surface and the retainer showed a strong negative correlation with biofilm accumulation (rs=-0.79, p=0.00037). The RHS showed significantly less accumulation of S. mutans due to the distance between the retainer and the tooth surface. This research provides relevant data for a future randomized clinical trial.

Accidental swallowing of orthodontic expansion appliance key.

Ingestion of a foreign object, including a dental object, can lead to a trip to the emergency room. This article describes the accidental swallowing of a key that was used to activate a rapid maxillary expander. An orthodontic patient swallowed the key while trying to activate the appliance at home. The object's trajectory was followed on radiographs until it was eliminated. Possible clinical complications, legal implications of this situation, and practices for prevention are described.

Photoelastic analysis of forces generated by T-loop springs made with stainless steel or titanium-molybdenum alloy.

INTRODUCTION: The purpose of this study was to use photoelastic analysis to compare the system of forces generated by retraction T-loop springs made with stainless steel and titanium-molybdenum alloy (TMA) (Ormco, Glendora, Calif) with photoelastic analysis. METHODS: Three photoelastic models were used to evaluate retraction T-loop springs with the same preactivations in 2 groups. In group 1, the loop was constructed with a stainless steel wire, and 2 helicoids were incorporated on top of the T-loop; in group 2, it was made with TMA and no helicoids. RESULTS: Upon using the qualitative analysis of the fringe order in the photoelastic model, it was observed that the magnitude of force generated by the springs in group 1 was significantly higher than that in group 2. However, both had symmetry for the active and reactive units related to the system of force. CONCLUSIONS: Both springs had the same mechanical characteristics. TMA springs showed lower force levels.

Continuous torque system with control of the reaction unit.

This article describes an orthodontic system used to obtain active continuous torque with movement control of both active and reactive units; the system relies on principles of the segmented technique. A cantilever system with .017 x .025-in beta-titanium alloy wire was designed to provide the desirable moment on the active unit. A transpalatal bar or a lingual arch increases the anchorage and neutralizes the side effects on the reactive unit. This technique is an efficient approach for major corrections of buccolingual inclinations of certain teeth.

Group A T-loop for differential moment mechanics: an implant study.

INTRODUCTION: When anchorage control is critical and compliance is less than ideal, efficient treatment depends on differential tooth movements. The purpose of this study was to evaluate the distal tipping of partially retracted canines and the mesial movement of the molars. METHODS: Eleven patients had their maxillary and mandibular canines partially retracted with TMA (Ormco Corp, Orange, Calif) T-loop springs with 45 degrees gable bends distal to the loops preactivated for group A (maximum anchorage). Metallic bone markers served as references. The canines were retracted until enough space was available for alignment of the incisors without proclination. Oblique (45 degrees) radiographs were taken immediately before the initial activation and after partial retraction. The radiographs were scanned, superimposed on the bone markers, and measured digitally. RESULTS: The mandibular canine crowns were retracted (4.1 +/-1.9 mm) and intruded (0.7 +/- 0.3 mm) by uncontrolled tipping. In contrast, the maxillary canine crowns were retracted (3.2 +/- 1.4 mm) by controlled tipping. The maxillary and mandibular molars crowns were protracted by similar amounts (1.0 +/- 0.6 and 1.2 +/-1.2 mm, respectively) by controlled tipping, without significant extrusion. The molars were protracted approximately 0.3 mm for every 1 mm of canine retraction. CONCLUSIONS: The T-loop spring used in this investigation produced controlled tipping of the maxillary canines, but it did not produce controlled tipping of the mandibular canines or translation of the molar as expected.

Changes over time in canine retraction: an implant study.

INTRODUCTION: The objective of this study was to analyze rates of canine movement over the first 2 months of continuous retraction, when rate changes are expected. METHODS: Ten patients with bone markers placed in the maxilla and the mandible had their canines retracted over a 2-month period. Retraction was accomplished with beta-titanium alloy T-loop springs. Standardized 45 degrees oblique cephalograms where taken initially and every 28 days thereafter. The radiographs were scanned and digitized twice (the average was used for the analyses). The radiographs were superimposed by using the bone markers and oriented on the functional occlusal plane. Paired t tests were used to compare side and jaw effects. RESULTS: There were no significant differences between sides. The maxillary cusp was retracted 3.2 mm, with less movement during the first (1.1 mm) than during the second 4 weeks (2.1 mm). The maxillary apices did not move horizontally. There were no significant vertical movements in the cusps and apices of the maxillary canines. The mandibular cusp was retracted 3.8 mm-1.1 mm during the first and 2.7 mm during the second 4 weeks. The mandibular apices were protracted 1.1 mm. The cusps and apices were intruded 0.6 and 0.7 mm, respectively. The only difference between jaws was the greater protraction of the mandibular apices during the second 4 weeks and in overall movement. CONCLUSIONS: The rate of canine cusp retraction was greater during the second than the first 4 weeks. The mandibular canines were retracted by uncontrolled tipping whereas the maxillary canines were retracted by controlled tipping.

Midsymphyseal distraction osteogenesis: a new alternative for the treatment of dental crowding.

In this article, we describe a midsymphyseal distraction osteogenesis treatment with a novel dentally supported appliance. This approach differs from that used in previous reports because the incisors were allowed to move during the distraction procedure. This report shows that midsymphyseal distraction osteogenesis can be used to expand both arches to produce a wider smile. Borderline cases can be treated with this technique without the compromising effects commonly observed with conventional therapy.

In vivo and in vitro study of the shear bond strength of brackets bonded to enamel using halogen or LED light.

AIM: To evaluate the shear bond strength in vivo and in vitro of metallic brackets bonded to human teeth with light-curing bonding material, using two types of light-curing units. METHODS: Sixty human premolars were divided into six groups. In the GI and GII groups, the brackets were directly bonded to volunteers' maxillary and mandibular second premolars on the right and left sides, respectively, of their mouths. In the other groups, the brackets were bonded to extracted first premolars. The polymerization was performed in GI, GIII, and GV with an LED (light-emitting diode) device, while in GII, GIV, and GVI, a halogen light was used. In GI and GII, shear strength tests were conducted using a portable digital dynamometer placed directly in the patients' mouths. The teeth from GIII, GIV, GV, and GVI were stored in distilled water at 37 degrees C for 24 hours. Afterward, they were thermocycled between 5 degrees and 55 degrees C. Then, in GIII and GIV, a Universal Testing Machine was used; in GV and GVI, mechanical tests were performed with a digital dynamometer. The bracket/adhesive failure modes were evaluated with the Adhesive Remnant Index (ARI). RESULTS: The average values of the shear strengths in MPa were: GI = 3.65; GII = 4.39; GIII = 6.45; GIV = 7.11; GV = 4.67; and GVI = 4.21. CONCLUSIONS: The type of light-curing unit did not interfere with the results of the mechanical tests in vivo or in vitro. The tests performed with a portable digital device obtained average values that were significantly lower than those performed with the Universal Testing Machine.

Which one closes extraction spaces faster: en masse retraction or two-step retraction? A randomized prospective clinical trial.

OBJECTIVES: To compare the time to close extraction spaces between en masse (ER) and two-step retraction (TSR). MATERIALS AND METHODS: Forty-eight patients with bimaxillary protrusion underwent treatment with extraction of four first premolars. All patients were randomly allocated to one of two groups: ER (n = 24) or TSR (n = 24). The main outcome was the time required to close spaces between ER and TSR; the closing time of spaces between females and males was a secondary outcome. The size of premolars was measured on the models and data were collected on clinical records at the following times: retraction start date (T1) and space closure completion date (T2). The total time to close the extraction spaces was calculated for each extracted premolar (T1 to T2). The Kaplan Meier method and the Log-Rank test were used to compare the groups. RESULTS: The time to close extraction spaces showed significant differences between the ER and TSR groups. While ER took between 12.1 and 13.8 months, TSR took between 24.7 and 26.8 months. The TSR group showed a significant difference between sexes; male patients took 5.5 months longer than female patients for the extraction spaces to close. CONCLUSIONS: TSR takes between 1.8 and 2.2 times longer than ER to close the extraction spaces and it took longer in males than females.

Optimizing the design of preactivated titanium T-loop springs with Loop software.

A TMA (Ormco Corp, Glendora, Calif) T-loop spring (TTLS), preactivated with a gable bend distal to the loop, holds promise for producing controlled tipping of the canines and translation of the posterior segment. However, there is currently no consensus as to where the preactivated gable bend or the loop should be placed, what the height of the loop should be, or how the interbracket distance changes the moments produced. Using the Loop software program (dHal, Athens, Greece), we systematically modified a .017 x .025-in TTLS (10 x 6 mm) that was preactivated with a 45 degrees gable bend distal to the loop, and simulated the effects. As the gable bend was moved posteriorly, the moment increased at the posterior bracket more than it decreased at the anterior bracket. As the loop was brought closer to the anterior bracket, the posterior moment decreased at the same rate that it increased anteriorly. As the loop was increased in size, the moments increased both posteriorly and anteriorly. As the interbracket distance increased, the posterior moment decreased, and the anterior moment remained constant. We concluded that the size of the loop should be slightly increased, to 10 x 7 mm, and it should be placed 2 mm from the anterior bracket, with a preactivation bend of 45 degrees , 4 to 5 mm from the posterior bracket (after 4 mm of activation).

Influence of orthodontic dental movement on the healing process of teeth with periapical lesions.

The purpose of this study was to histomorphologically evaluate (in dog's teeth) the influence of tooth movement in the healing of chronic periapical lesions. Thirty roots of incisors and premolars of two dogs (1-year-old) were used in this research. After pulpectomy, the root canals remained exposed to the oral environment for 6 months for achievement of periapical lesions. Twenty root canals were biomechanically prepared and received a calcium hydroxide dressing for 14 days before being filled with gutta-percha points and Sealapex sealer. After root canal treatment, some incisors were submitted to orthodontic movement, whereas the other roots remained without orthodontic movement. The orthodontic appliance was removed at 5 months and 15 days after treatment, the dogs were killed 15 days later and the specimens were prepared for histomorphological analysis. The results showed that the orthodontic movement delayed, but did not hinder, the periapical healing process.

Esthetic influence of negative space in the buccal corridor during smiling.

The purpose of this study was to measure and verify the esthetic influence of the bilateral spaces between maxillary teeth and lip corners, called negative space (NS), during smile. The sample was comprised of 60 smile photographs obtained from 60 individuals (30 men and 30 women) aged 18 to 25 years old. Two orthodontists and two lay people evaluated these pictures regarding esthetics by a visual analogue scale. In each picture, the right and left NS were measured in millimeters and in proportion to the smile width (SW). Data were analyzed for statistical significance (P = .05). The mean NS of the sample was 6.68 +/- 1.99 mm, and the NS proportion in relation to the SW was 9.6 +/- 2.56%, for both sides of the arch. No significant asymmetries were observed between the right and left sides. The NS was significantly larger in men than in women when measured in millimeters (P = .028) (7.08 +/- 2.24 mm in men vs 6.28 +/- 1.62 mm in women), but the NS proportion to the SW was similar (9.94 +/- 2.24% in men vs 9.26 +/- 1.61% in women). When the 12 individuals with the smallest NS in proportion to SW were compared with the 12 individuals with the largest NS in proportion to SW, there was no statistical difference regarding the esthetic evaluation (P = .11). It was concluded that the NS did not influence the esthetic evaluation of smile photographs in the sample in this study, for both orthodontists and lay people.

Analysis of the smile photograph.

Optimal facial esthetics is one of the objectives in orthodontic treatment and an important issue in modern society. In this context, orthodontic treatment permits individuals with dental malpositions to achieve improved dentofacial esthetics. To reach this result, the orthodontist needs to recognize the characteristics considered normal and pleasant in dental arches and smiles. The objective of this article is to review and discuss criterion adopted by dental literature to technically analyze the smile, such as dental midline, smile line, dental exposure, negative space, dental proportion, and symmetry. This article proposes a way to visualize an ideal smile for each patient.

Scientific use of the finite element method in Orthodontics.

INTRODUCTION: The finite element method (FEM) is an engineering resource applied to calculate the stress and deformation of complex structures, and has been widely used in orthodontic research. With the advantage of being a non-invasive and accurate method that provides quantitative and detailed data on the physiological reactions possible to occur in tissues, applying the FEM can anticipate the visualization of these tissue responses through the observation of areas of stress created from applied orthodontic mechanics. OBJECTIVE: This article aims at reviewing and discussing the stages of the finite element method application and its applicability in Orthodontics. RESULTS: FEM is able to evaluate the stress distribution at the interface between periodontal ligament and alveolar bone, and the shifting trend in various types of tooth movement when using different types of orthodontic devices. Therefore, it is necessary to know specific software for this purpose. CONCLUSIONS: FEM is an important experimental method to answer questions about tooth movement, overcoming the disadvantages of other experimental methods.

Comparison surface characteristics and chemical composition of conventional metallic and nickel-free brackets.

This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracket surface was performed using SEM, whereby surface features were described and compared. The elemental composition was analyzed by EDS. According to surface analysis, groups ABZ and RL showed a homogeneous surface, with better finishing, whereas the surfaces in groups NF and RM were rougher. The chemical components with the highest percentage were Fe, Cr and C. Groups NF and MR showed no nickel in their composition. In conclusion, the bracket surface of the ABZ and RL groups was more homogeneous, with grooves and pores, whereas the surfaces in groups NF and RM showed numerous flaws, cracks, pores and grooves. The chemical composition analysis confirmed that the nickel-free brackets had no Ni in their composition, as confirmed by the manufacturer's specifications, and were therefore safe to use in patients with a medical history of allergy to this metal.