Straight Wire Technique Research Articles

Six-month bracket survival with a self-etch adhesive.

To evaluate, over a 6-month period, the clinical performance of a self-etch adhesive (Transbond Plus Self-Etching) compared with a conventional adhesive that uses the etch and rinse approach (Transbond XT). One operator, using the straight-wire technique, placed 567 metallic brackets in 30 patients (age range 12-18 years) such that homologous teeth from the same arch received different materials. The brackets were bonded following the manufacturer's instruction except for the fact that the self-etch system was brushed for a longer time than recommended (10-15 seconds). The failure modes were visually classified into three modes: adhesive-enamel, adhesive-bracket, and cohesive failure. The survival rate of the brackets was estimated by Kaplan-Meier and log-rank test (P < .05). The failure rates of the conventional and self-etch [corrected] adhesives were 10.6% and 7.4%, respectively. The failure rate of the conventional system was 0.43 [corrected] times greater than that of the self-etch system. The self-etch adhesive showed a higher survival rate compared with the conventional system (P < .05). Most of the failures were cohesive and at the adhesive-enamel surface. No difference in the fracture debonding mode was observed for the materials. These findings indicate that the self-etch Transbond Plus Self-Etching can be safely used for orthodontic brackets because it provides higher survival rates than does the conventional Transbond XT.

Effects of lingual orthodontics on function and aesthetics of stomatognathic system

Objective To evaluate the functional and aesthetic disturbance of patients treated with lingual orthodontic surgery and to investigate the key points of laboratory procedure and clinical treatment of lingual orthodontic deformity. Methods A total of 30 cases of Angle class Ⅰ with moder-ate crowding were selected. They were equally divided into two groups: one group was treated using lingual brackets, and the other using conventional labial brackets. Each patient completed a four-part survey right after the bracket placing and 7, 28, 56 days after the treatment. The differences of tongue-lip-cheek soreness, eating and speech difficulties and aesthetic problems were evaluated be-tween two groups. Lateral cephalograms were analyzed at the start of the treatment and the end of the overall treatment. Results Speech difficulties of lingual orthodontics were significantly greater (P<0.01) than that in the labial orthodontics group in the first week of the treatment. Eating difficulties were greater (P<0.01) in the lingual orthodontics group by 28 days, whereas aesthetic problems were greater in group using labial appliance than group lingual appliance. Conclusions In the first two months of the orthodontic treatment, eating and speech difficulties are the most severe problems for the lingual group. Lingual orthodontics offers important aesthetic advantages over labial orthodontics, and it will be one of the development directions of current orthodontics. Key words: Lingual orthodontics; Straight wire technique; Malocclusion; Cephalome-try

Evaluation of the variable anchorage straightwire technique using Ricketts' growth prediction

The purpose of this retrospective study was to evaluate the treatment effects of the variable anchorage straightwire technique (VAST) in Angle Class II patients using Ricketts' growth prediction analysis. The subjects belonged to two groups: a control, consisting of 30 untreated Class II Swedish individuals (20 girls, 10 boys) with a mean age of 11.2 years, and the other 29 Swedish patients (14 girls, 15 boys), mean age 12.6 years, post-normal and with an increased overbite (OB), treated with the VAST. Two lateral cephalograms were available for every individual. Growth prediction according to Ricketts' visual treatment objective (VTO) was used to estimate the expected growth increments for a 2-year period. It was first used in the control group to determine its validity and then applied to the treated group to evaluate the net effects of treatment. Cephalometric evaluation based on Ricketts' analysis and additional dentoalveolar variables were carried out. Statistical analysis was undertaken using a paired Student's t- and Wilcoxon signed ranks tests. The method of predicting growth according to the VTO was, in general, valid in the untreated subjects, apart from the inclination of the lower incisors, where the proclination had been underestimated. In the treated group, the net effects of treatment were significant for the dentoalveolar variables: reduction of overjet (OJ) and OB, proclination and relative intrusion of the lower incisors, extrusion of the molars, and increase in lower face height. The growth prediction method according to VTO was found to be valid in a sample of Swedish post-normal children concerning skeletal and dentoalveolar variables. The VAST treatment net effects in these growing patients were achieved mainly by dentoalveolar changes.

Eighteen-month bracket survival rate: conventional versus self-etch adhesive

The aim of this study was to evaluate, over an 18-month period, the clinical performance of a self-etch adhesive [Transbond Plus Self Etching Primer (SEP), 3M Unitek] compared with a conventional adhesive that employs the etch-and-rinse approach (Transbond XT, 3M Unitek). One operator, using the straight-wire technique, bonded 567 metallic brackets to the teeth of 30 patients (age range 12-18 years) in a way that patients acted as self-control. The brackets were bonded following the manufacturers' instructions except for the fact that the self-etch system was brushed for a longer time than recommended (10-15 seconds) since previous investigations have reported that prolonged application times can improve the bonding efficacy of self-etch systems to enamel. The failure modes were visually classified into: adhesive-enamel, adhesive-bracket, and cohesive failure. The survival rates of the brackets were estimated by Kaplan-Meier and log-rank test (P < 0.05). The failure rates of the self-etch and conventional adhesives were 15.6 and 17.6 per cent, respectively. No significant differences in the survival rate were observed between the materials (P > 0.05). Most of the failures were cohesive and at the adhesive-enamel interface. There was no difference in the fracture debonding mode. These findings indicate that Transbond Plus SEP can be safely used for orthodontic brackets since the survival rates are similar to the conventional Transbond XT.

À propos d'une charte adaptée à la forme des arcades

Arch wires used in orthodontic treatment must conform to the shape of the dental arches so that in their final positions teeth will be set in a pathway of neuromuscular equilibrium. However, sometimes distortions of the alveoli deform the shape of the arch. In such cases the treatment charts constructed on the actual alveolo-dental relationship will not reflect desired objectives. We believe that the transverse muco-gingival dimension Andrews called the Wala line responds better to therapeutic requirements. Moreover, molar attachments, key elements of a full-banded appliance, are in harmony with it. So the type of chart that the authors propose for use with the Straight Wire technique, one based on the Wala line, will help orthodontists place teeth at the conclusion of orthodontic treatment in the best possible relationships to patients' specific anatomic configurations.

The variable anchorage straight wire technique compared with the straight wire technique in deep overbite correction

The aim of this retrospective study was to compare the treatment results and the number of required treatment appointments between the variable anchorage straight wire technique (VAST) and the straight wire (SW) technique. The subjects were 53 Caucasian patients of both sexes (25 males and 28 females, mean age 13.5 years at the start of treatment), with an overjet > or = 4 mm and an overbite > or = 3 mm. The patients were divided into four groups, VAST (n = 31) or SW (n = 22), extraction or non-extraction, and were treated by the same orthodontist. Variables from two lateral cephalograms obtained before and at the completion of active treatment, and the number of scheduled appointments were compared between the two techniques. The main difference between the two techniques was the bracket design. With the VAST, the bracket allowed both tipping and parallel movements with the possibility to combine double archwires. Due to the influence of the Begg technique, no extra-oral traction was needed in the VAST groups and Class II elastics were used at the start of treatment. Both techniques seemed to produce equal treatment results. However, in this study, it was shown that in deep overbite correction, the VAST required fewer scheduled appointments than the SW technique.

Torque capacity of metal and polycarbonate brackets with and without a metal slot.

The aim of the present study was to investigate slot deformation and the equivalent torque capacity of polycarbonate brackets with and without a metal slot in comparison with those of a metal bracket. For this purpose, the expansion characteristics and, in a further investigation, the labial crown torque of an upper central incisor, were measured in a simulated intra-oral clinical situation, using the orthodontic measuring and simulation system (OMSS). Three types of bracket with a 0.018 inch slot were tested: polycarbonate Brillant without a metal slot, Elegance with a metal slot and the metal bracket, Mini-Mono. For testing purposes the brackets were torqued with 0.016 x 0.022 inch (0.41 x 0.56 mm) and 0.018 x 0.022 inch (0.46 x 0.56 mm) ideal stainless steel archwires. In the activating experiments, significantly higher torque losses and lower torquing moments were registered with both rectangular archwires with the polycarbonate brackets than with the metal bracket. In the simulation tests, significantly higher torquing moments were registered with the metal bracket than with the polycarbonate brackets. The values for the Elegance bracket were between those of the Mini-Mono and Brillant brackets. The OMSS model approximates the clinical situation, with the torque loss being notably higher than in the in vitro activating experiments. This is due to the adjacent teeth giving the archwire additional play. In addition, the torquing process may twist the archwire, resulting in subsidiary forces. On the basis of the present results, all three brackets can be recommended for torquing. However, in view of the high torque losses, the torques programmed in the straightwire technique must be seen as questionable. Data should be provided by the manufacturer on the bending to be expected in polycarbonate brackets, which has to be offset by additional torque, or the bracket torque should be omitted from the technical specifications.

Preliminary study of non-surgical treatment of severe Class III malocclusion in 18 patients of 12-20 years old

To analyze effects of non-surgical treatment on subjects of 12-20 years old with severe skeletal Class III deformity and to directly evaluate dental and facial profile changes. Eighteen patients with severe skeletal Class III malocclusion (male 5, female 13), diagnosed as indication for orthognathic surgery, were included in the study. The average age was 14.6 +/- 2.5 years old., with age range from 12 years old to 20 years old. 12 cases were treated with Tip-Edge straight-wire technique and 6 cases with Begg light wire technique. The average treatment time was 2.5 +/- 0.8 years. The selection criteria included: (1) mesial or superior mesial Class III molar relationship, with maxillary first molar occlude the buccal groove of the mandibular second molars (2) no mandibular shift (3) ANB < -1.5 degrees (4) high angle cases with average value of SN-MP 34.9 degrees +/- 5.9 degrees, 4 cases present with openbite (5) concave facial profile (6) originally classified as surgery cases. Lateral cephalometric films taken at the beginning and the end of the treatment were analyzed with traditional cephalometric analysis. The arithmetic mean (Mean) and standard deviation (SD) were calculated for each variable. Paired t-test was performed to evaluate the significant treatment change. Normal overjet and overbite were established with proclination of upper incisors and retroclination of lower incisors. Inclination of upper incisors was increased 5.9 degrees when measured with the angle of upper incisor to SN plane (P < 0.01). Inclination of lower incisors was decreased 6.6 degrees when measured with the angle of lower incisor to mandibular plane (P < 0.001). Negative value of the distance difference of upper lip and lower lip to Sn-Pg' at the beginning of treatment changed to positive value with significant difference (P < 0.001). Successful treatment effects could be obtained with non-surgical therapy in severe skeletal Class III malocclusion in permanent dentition. Remarkable soft-tissue change was noted after the treatment and concave facial profile changed to straight profile.

Preliminary investigation of nonsurgical treatment of severe skeletal Class III malocclusion in the permanent dentition.

The purpose of the study was to analyze the effects of nonsurgical treatment on subjects with a severe skeletal Class III deformity and to directly evaluate dental and facial profile changes. Eighteen patients with severe skeletal Class III malocclusions (5 males, 13 females), diagnosed as indication for orthognathic surgery, were included in the study. The average age was 13.7 +/- 2.5 years. All the cases were treated with Tip-Edge straight-wire technique or Begg light wire technique. Lateral cephalometric films taken at the beginning and at the end of treatment were analyzed with the Pancherz analysis and traditional cephalometric analysis. The arithmetic mean and standard deviation were calculated for each variable and paired t-test was performed. A mean reduction of 6.5 mm in the overjet was noted (P < .001), with skeletal changes and dental changes contributing 20% and 80% to the overjet correction, respectively. The inclination of the upper incisors to the SN plane was increased 5.9 degrees (P < .01). The inclination of the lower incisors to the mandibular plane was decreased 6.6 degrees (P < .001). The difference between the distance of the upper lip and lower lip to Sn-Pg' at the beginning of treatment changed from a negative value to a positive value with a significant difference (P < .001). Successful treatment effects can be obtained with nonsurgical therapy in severe skeletal Class III malocclusions in the permanent dentition. A remarkable soft tissue change was noted after the treatment, and the concave facial profile changed to a straight profile (see two case reports).

Straight wire technique in lingual orthodontics

Straight wire technique in lingual orthodontics

Directions of orthodontic tooth movements associated with external apical root resorption of the maxillary central incisor

External apical root resorption is a multifactorial problem encountered in all disciplines of dentistry, but it is most commonly seen in cases treated orthodontically. Specific tooth movements that are most likely to exacerbate external apical root resorption are poorly understood. Purpose of the present investigation was twofold: (1) to quantify apical and incisal movements of the maxillary central incisor in the sagittal and vertical planes from cephalograms and (2) to use stepwise multivariate linear regression analyses to see which tooth movements and skeletodental relationships are most predictive of external apical root resorption. The sample consisted of 110 adolescents with similar pretreatment malocclusions (Class I crowded or bimaxillary protrusive) and treatment planned similarly (extraction of four first premolars) by experienced private practitioners. Each of three practitioners used a different orthodontic appliance; the sample was divided proportionately into cases treated with Tweed standard edgewise technique, Begg lightwire technique, and Roth-prescription straightwire technique. Lateral cephalograms were analyzed at the start, middle, and end of treatment. There was no statistical difference in average external apical root resorption between sexes or among techniques. Measures of tooth movement were highly predictive, explaining up to 90% of the variation in root resorption. Apical and incisal vertical movements and increase in incisor proclination were the strong predictors of external apical root resorption for each regression model. Incisor intrusion with increase in lingual root torque together were the strongest predictors of external apical root resorption. In contrast, distal bodily retraction, extrusion, or lingual crown tipping had no discernible effect. (Am J Orthod Dentofacial Orthop 1998;114:677-83)

Der Einfluß der vertikalen Bracketposition auf das kieferorthopädische Finish

As during orthodontic treatment and in particular during the phase of the precise adjustment of occlusion by applying the "straight-wire technique" problems arise as far as the vertical dimensions are concerned, the usual distances between the bracket slots and the edges of the incisors respectively the top of the cusps have been verified. Measurements were done on models at the end of treatment of ten patients treated with fixed attachments who may represent ideal occlusion as far as profile radiographs and gnathology were concerned. After regulation of the plane of occlusion the vertical distances between the slot base plane (parallel to the plane of occlusion) and the edge of the incisors respectively tops of cusps were measured by means of a modified parallelometer in connection with a special slot and tube support as well as a specially developed dial test indicator, while a maximum fit between bracket base and buccal crown surface was given. In case of the upper front brackets (torque + 22 degrees) large vertical measurement to the edge of the incisors were recorded, 8.25 respectively 8.33 mm). This may be attributable to excessive torque of the applied brackets. Only approximate figures for the vertical positioning for other teeth could be given, as anatomical variations have to be considered.

Erfahrungen mit der Segmentbogentechnik nach Burstone im Erwachsenengebiß

In comparison to the straight wire technique the segmental arch approach offers numerous biomechanical and clinical advantages. Three typical examples: controlled tooth movement, en masse space closure and deep overbite correction serve to show the spectrum and the efficiency of the segmented arch technique.