Arch Technique Research Articles

Orthodontic movement into infrabony defects in patients with advanced periodontal disease: a clinical and radiological study.

In cases of advanced periodontal disease with a pathologic flaring of frontal teeth, a combined periodontic-orthodontic therapy may be a reliable approach in order to solve both functional and esthetic problems. The aim of the present study was to evaluate the periodontal tissue alterations following periodontal surgery and orthodontic intrusion in migrated upper central incisors with intrabony defects. Ten patients with advanced periodontal disease and an extruded maxillary central incisor infrabony defect at its mesial aspect and probing depth (PD) > or = 6 mm were included in the present study. At baseline, PD and clinical attachment level (CAL) were measured. The vertical and horizontal dimensions of the defects were assessed on standardized radiographs. Seven to 10 days after surgery the active orthodontic treatment started using the segmented arch technique, in order to intrude and move the teeth into the defects. Maintenance therapy was performed every 2 to 3 months until the orthodontic treatment was completed. At the end of treatment, mean PD reduction was 4.35 mm, with a residual mean PD of 2.80 mm. Mean CAL gain was 5.50 mm. The mean radiological vertical and horizontal bone fills were, respectively, 1.35 mm and 1.40 mm. All differences were of statistical significance (P<0.001). The present study showed that the combined orthodontic and periodontic therapy performed resulted in the realignment of extruded teeth with infrabony defects, obtaining a significant probing depth reduction, clinical attachment gain, and radiological bone fill.

The mechanical plan of the segmented arch technique

The mechanical plan of the segmented arch technique

Volatility and cross correlation across major stock markets

Several papers have documented the fact that correlations across major stock markets are higher when markets are more volatile—this is done by comparing unconditional correlations over sub-periods or by using conditional correlations that are time varying. In this paper we examine the relation between correlation and variance in a conditional time and state varying framework. We use a switching ARCH (SWARCH) technique that does two things. One, it enables us to model variance as state varying. Two, a bivariate SWARCH model allows us to go from conditional variance to state varying covariances and correlations and hence test for differences in correlations across variance regimes. We find that the correlations between the U.S. and other world markets are on average 2 to 3.5 times higher when the U.S. market is in a high variance state as compared to a low variance regime. We also find that, compared to a GARCH framework, the portfolio choices resulting from our SWARCH model lead to higher Sharpe ratios.

Rectangular wire and third-order torque: A new perspective

The Differential Straight Arch technique, more commonly known as "Tip-Edge" (TP Orthodontics Inc.), uses a modified edgewise type bracket to allow differential tooth movement. As bracketed teeth incline toward their finishing positions, the geometry of the arch wire slot causes the vertical slot dimension available to the arch wire to increase. Advantage has been taken of this facility, to evolve an entirely new torquing system for final finishing, during the root correction phase. Instead of increasing rectangular arch wire size to fit the arch wire slot, as with conventional edgewise brackets, the Tip-Edge method reduces the vertical arch wire slot dimension to achieve a precise, three-dimensional relationship to a full-sized rectangular arch wire. The active component is provided by auxiliary springs. The method, which awaits mathematical analysis, is described and illustrated with two case reports.

Volatility and Cross Correlation Across Major Stock Markets

Several papers have documented the fact that correlations across major stock markets are higher when markets are more volatile - this is done by comparing unconditional correlations over sub-periods or by using conditional correlations that are time varying. In this paper we examine the relation between correlation and variance in a conditional time and state varying framework. We use a switching ARCH (SWARCH) technique that does two things. One, it enables us to model variance as state varying. Two, a bivariate SWARCH model allows us to go from conditional variance to state varying covariances and correlations and hence test for differences in correlations across variance regimes. We find that the correlations between the U.S. and other world markets are on average 2 to 3.5 times higher when the U.S. market is in a high variance state as compared to a low variance regime. We also find that, compared to a GARCH framework, the portfolio choices resulting from our SWARCH model lead to higher Sharpe ratios.

On the management of extraction sites

Extraction sites may be needed to achieve specific orthodontic goals of positioning the dentition within the craniofacial complex. The fundamental reality that determines the final position of the dentition, however, is the control exercised by the clinician in closure of the extraction sites. A specific treatment objective may require the posterior teeth to remain in a constant position anteroposteriorly as well as vertically, while the anterior teeth occupy the entire extraction site. Another treatment objective may require the reverse, or any number of purposeful alternatives of extraction site closure. An appliance system developed over time, which provides this control, is described. The system takes advantage of aspects of continuous arch therapy that provides constant, positive orientation of the anterior and posterior groups of teeth to each other in three-dimensional space across an extraction site, combined with aspects of the segmented arch technique that permit definable and predictable force systems to be applied to these teeth. Consequently, the clinician has the ability to forecast treatment outcomes with confidence.(Am J Orthod Dentofac Orthop 1997;112:645-55.)

Evaluation of continuous arch and segmented arch leveling techniques in adult patients—a clinical study

The purpose of this study was to compare the efficacy of overbite correction achieved by a conventional continuous arch wire technique and the segmented arch technique as recommended by Burstone. The sample comprised 50 adult patients (age 18 to 40 years) with deep bites. Twenty-five patients were treated with a continuous arch wire technique (CAW); in the second half of the sample, the segmented arch technique (Burstone) was used for correction of the vertical malocclusion. Lateral cephalograms and plaster cast models taken before and immediately after treatment were evaluated. Statistical analysis was performed on the collected data. The results showed that both techniques produced a highly significant overbite reduction (CAW: -3.17 mm, p < 0.001; Burstone: -3.56 mm, p < 0.001). The CAW group showed an extrusion in the molar area with subsequent posterior rotation of the mandible (6occl-ML: +1.30 mm; 6occl-NSL: +1.63 mm; ML/NSL: +1.94 degrees, all p < 0.001). The Burstone group, however, showed overbite reduction by incisor intrusion without any substantial extrusion of posterior teeth (upper 1-NSL: -1.50 mm; lower 1-ML: -1.72 mm; both p < 0.001). As a consequence, no significant posterior rotation of the mandible took place (ML/NSL: +0.52 degrees, n.s.). It is concluded that in adult patients the segmented arch technique (Burstone) can be considered as being superior to a conventional continuous arch wire technique if arch leveling by incisor intrusion is indicated.

Conditional volatility and the production smoothing hypothesis of inventory investment

This paper introduces a conditional second moment approach to the production smoothing hypothesis of inventory investment. The multivariate ARCH technique makes it possible to calculate the time series of the relevant conditional variances and covariances. The importance of explaining the production and inventory decision rules in terms of the sales anticipation errors is emphasized. The time varying conditional volatility measures suggest that the factors affecting the production and inventory investment are changing over time. It is shown that the buffer stock motive can be the source of production smoothing when firms face unanticipated sales changes, but the stock adjustment behavior may cause production bunching through the intended change in production if the desired stock of inventories is proportional to anticipated sales, and demand shifts are considerably durable.

Space closure with T loops (Burstone)--a clinical study

The theoretically favourable aspects of orthodontic space closure with segmented arch technique and the T-loop type A are clinically reproducible. In our study of eleven patients we found for the isolated canine retraction, as well as for the en masse retraction, controlled types of movement for the active units and maximum anchorage situations for the passive units produced by the torquing force. Because of these good anchorage conditions space closure could be done without headgear. The level of the anchorage segments was negligibly influenced but in the anterior segments a marked tilting was found in several cases. Besides other factors the intrusive force of the T-loops type A must be considered. As a rule the positioning of the T-loop between central and lateral incisor is to be recommended.

Cellular arch technique for large-span station cavern : Lunardi, P Tunn TunnlgV23, N11, Nov 1991, P23–26

The Venezia Station on the Milan Rail Link is being constructed using a novel technique to cope with drawbacks such as unconsolidated ground and the presence of old foundations. This article discusses the planning aspects of the project, the cellular arch, excavation of Venezia Station, excavation of the thrust pit, and controls and measurements of the excavation.

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.

Space closure in adult patients using the segmented arch technique.

Periodontally compromised adult patients may benefit from modified appliance designs for space closure. TMA T-loops of .016" x .022" and .017" x .025" cross sections, with angulations incorporated via concentrated bends and gradual curvature bends are presented. The force systems these appliances produce are measured, and their clinical performances discussed. Templates for these T-loops are presented. By producing lower forces and higher moment to force ratios, this type of T-loop may benefit patients with bony loss.

Extraction and metabolism of circulating catecholamines by the trout gill.

Extraction and metabolism of [3H]-norepinephrine (NE) and [3H]epinephrine (E) by the respiratory (efferent branchial) and filamental (venous) vasculature of the trout gill were examined using an isolated perfused arch technique in which outflow from the two circulations was separated. Deaminated and O-methylated metabolites in the effluent were identified by ion-exchange chromatography. Metabolism by tissue homogenates was also measured. Gill homogenates deaminate catecholamines (CAs) faster than homogenates of liver, kidney, and skeletal muscle; branchial O-methylation was comparable to that of liver and kidney. The perfused gill extracted 60% of a NE pulse and 47% of an E pulse. During continuous CA perfusion the gill removed greater than 30% of the NE from the circulation through extraction and metabolism; only 7% of the E was removed. The gill venous system extracts and metabolizes more CAs than the efferent. NE is the preferred substrate for extraction and metabolism. A mechanism is proposed whereby high circulating CA levels, common during stress, are maintained through CA-induced reduction in venous blood flow. After the stress is alleviated, CA levels begin to fall, flow to the venous pathway increases, and the rate of inactivation of circulating CAs increases.

Biomechanical design and clinical evaluation of a new canine-retraction spring

Use of the sectional arch technique facilitates the creation of an optimal force system fulfilling the biomechanical requirements imperative for planned tooth movements. Controlled canine retraction, usually in extraction cases, requires the creation of a biomechanical system to deliver a predetermined force and a relatively constant moment-to-force ratio in order to avoid distal tipping and rotation. The responsive couple delivered to the anchorage unit should be adjusted in such a way that no single tooth is subjected to unwanted side effects and that undesirable changes in the occlusal plane are avoided. On the basis of a series of theoretical considerations described in the present report, a canine-retraction spring was constructed from 0.016 × 0.022 inch stainless steel wire, the principal element being a double ovoid loop 10 mm in height. A “sweep” bend was incorporated to avoid unwanted side effects at the second premolar. Load deflection and moment/force curves were derived experimentally and demonstrate the ability of the spring to generate and maintain biomechanical conditions necessary for optimal canine retraction (that is, load deflection = 45 gm per millimeter of activation, antitip moment/force ratio of approximately 11:1, and antirotation moment/force ratio of approximately 7:1). The clinical applicability of the spring is demonstrated in the present report by the presentation of two treated cases.

The segmented arch approach to space closure

The clinical application of frictionless attraction springs using the segmented arch technique is described. Differential space closure is achieved by varying the force system between the anterior and posterior segments. A specially designed force transducer allowed accurate force and moment determination for each spring design. By duplicating predetermined spring geometries, the orthodontist can reproduce the required force system within narrow ranges. The most important considerations in the clinical use of attraction springs are the amount of distal activation, the angulation differential between the anterior and posterior teeth, and the centricity or eccentricity of the loop. Improvements in design have lead to a more efficient, hygienic, and comfortable mechanism for space closure.

Treatment o f palatally impacted canine teeth

The etiology of canine impactions is unknown. The migration of the crown palatally will usually result in impaction because of the hard, dense tissues that it encounters. A simple surgical exposure is all that is necessary to allow the tooth to erupt. Normal eruption is usually faster than can be accomplished by mechanical methods. A 4- to 6-month waiting period is advised to shorten the over-all period of treatment. Any method of treatment best known to the orthodontist can be used to move the teeth to their correct arch position. I prefer gold cast onlays with loops or Johnson brackets with ligature holes soldered to the gold onlays and the Johnson twin arch technique. No retention is necessary for holding canines labial to the lower dental arch. I hope that Figs. 5, 6, and 7 will demonstrate my own methods of treating palatally impacted canine teeth on the basis of simplicity and patience.

Augmentation of cardiac contractile force and heart rate by medulla oblongata stimulation in the cat.

AbstractElectrical stimulation in two relatively well circumscribed regions of the medulla oblongata elicited tachycardia and augmentation of the right ventricular contractile force recorded by a strain gauge arch technique. One of the two regions was found to be situated within the more central part of the pressor area. Stimulation in this region generally produced vasoconstriction in skeletal muscle parallel with the increased cardiac activity. The second region was found to be located in the“sympathetic vasodilator area” in the ventrolateral part of the medulla. Muscle vasodilatation elicited by stimulation in that region was accompanied by an increase in the cardiac functions. The augmentation of cardiac activity with stimulation of the two regions was mediated by the sympathetic innervation of the heart and, to a minor extent, by an elevated secretion from the adrenal medulla.

Some clinical applications of the modified Johnson twin arch wire technique

The Johnson twin arch appliance is an effective mechanism for treating the various types of malocclusion. If used to treat the so-called extraction case, however, the appliance has certain deficiencies. These deficiencies are overcome, for the most part, when (1) a more efficient method of moving canines distally is employed, (2) the intraoral anchorage is angmented by extraoral anchorage, and (3) the operator has more effective control over the positions of the mandibular incisors and the maxillary and mandibular premolars. In the modified Johnson twin arch technique that has been described, several methods of overcoming these deficiencies have been outlined.

The improved modified edgewise arch technique

The improved modified edgewise arch technique

The efficiency of the russell attachment

E LEVEN years ago this writer1 reported the Russell attachment (Fig. 1) with enthusiasm for its unique simplicity. Today, after many years of continuous use of this attachment, I endeavor to report and demonstrate its ef6ciency and the value of its precision and timesaving qualities. Successful orthodontic results have been accomplished by various appliance techniques. There are several ways of reaching an objective. Some may adopt a long course, some a roundabout way, and others will look for short cuts. Each in his endeavor will reach the same destination. In orthodontics there have been many philosophies of mechanical therapy, and each in the hands of its respective operator has proved successful. For the past twenty-five years the writer, has had the opportunity to use almost every type of appliance; of the numerous appliances used, the Russell attachment has proved most satisfactory for the labial arch technique. It has the advantages of all the other labial attachments, and, in addition, can be handled with less time and effort, and lends itself to various applications with the’greatest efficiency. The Russell attachment is of two types: one, an 0.022 by 0.028 channeled block for the edgewise technique; and the other, an 0.022 by 0.036 for the ribbon arch wire. The attachment in the molar or the anchor teeth is larger than the anterior ones and is either 0.040 channeled, or 0.022 by 0.028 channeled. The 0.040 Russell molar attachment is used for the 0.040 round labial arch or the ribbon arch. For the edgewise technique the 0.022 by 0.028 attachment is used. No matter which labial procedure is employed, the Russell attachment affords simple and easy application. In order to align teeth or move them posteriorly, the multiple band technique is best employed with the Russell attachment bands. It is the writer’s preference to use the 0.036 attachment bands on the maxillary teeth, and the 0.022 by 0.028 attachment on the mandibular teeth for the edgewise technique. In an endeavor to conclude a satisfactory result, the operator does not stop to evaluate the nervous strain imposed upon himself by the tedious manipulation of some of our orthodontic mechanisms. The Russell attachment by virtue of its design lends itself to simple handling and innumerable possibilities. In many instances, in comparison with other attachments, it reduces operating time at the chair conservatively by 50 per cent or more.