Long-term skeletal and dental effects of facemask versus chincup treatment in Class III patients : A retrospective study.

OBJECTIVES: To investigate the skeletal and dental changes during chincup versus facemask treatment, to compare the long-term effects of the two appliances, and to document the impact of each on treatment success. METHODS: In all, 61 patients with Class III syndrome were retrospectively analyzed at three examination times: 7.8 ± 1.7 years of age (T0, pretreatment), 9.6 ± 2.4 years of age (T1, posttreatment), and around 15-20 years later (T2, long-term follow-up). RESULTS: Significant changes of specific cephalometric parameters for all treatment times: T0-T1 (SNA, interbase and gonial angle, Björk's sum angle, maxillomandibular differential, and distance of upper lip to esthetic line), T1-T2 (NL-NSL, SNB, mandibular-body length, effective mandibular length, and effective maxillary length), and T0-T2 (mandibular-body length, effective mandibular length, effective maxillary length, maxillomandibular differential, SNB, ANB, gonial angle, Björk's sum angle, and Wits appraisal). The T1-T2 results illustrate that in both treatment groups the typical Class III growth pattern often reappeared after treatment, including gains in SNB angle, condylion-gnathion length, and gonion-menton distance. CONCLUSIONS: Either a facemask or a chincup may be effectively used to treat Class III malocclusion. There were differences in long-term stability. Maxillary development was similarly favorable in both groups of patients with successful outcome. The subgroup in whom chincup treatment had failed were mainly characterized by excessive mandibular growth, or lack of maxillary catch-up growth, with deterioration of the maxillomandibular relationship notably in the initial phase of treatment. Early chincup treatment did not have an adverse impact on the temporomandibular joints.

Retrospective 25-year follow-up of treatment outcomes in angle Class III patients : Early versus late treatment.

OBJECTIVES: To assess early versus late treatment of Class III syndrome for skeletal and dental differences. METHODS: Thirty-eight Class III patients treated with a chincup were retrospectively analyzed. Baseline data were obtained by reviewing pretreatment (T0) anamnestic records, cephalograms, and casts. The cases were assigned to an early or a late treatment group based on age at T0 (up to 9 years or older than 9 years but before the pubertal growth spurt). Both groups were further compared based on posttreatment data (T1) and long-term follow-up data collected approximately 25 years after treatment (T2). RESULTS: Early treatment was successful in 74% and late treatment in 67% of cases. More failures were noted among male patients. The late treatment group was characterized post therapeutically by significantly more pronounced skeletal parameters of jaw size relative to normal Class I values; in addition, a greater skeletal discrepancy between maxilla and mandible, higher values for mandibular length, Cond-Pog, ramus height, overjet, anterior posterior dysplasia indicator (APDI), lower anterior face height, and gonial angle were measured at T1. The angle between the AB line and mandibular plane was found to be larger at T0, T1, and T2, as well as more pronounced camouflage positions of the lower anterior teeth at T0. The early treatment group was found to exhibit greater amounts of negative overjet at T0 but more effective correction at T1. CONCLUSIONS: Early treatment of Class III syndrome resulted in greater skeletal changes with less dental compensation.

Retrospective 25-year follow-up of treatment outcomes in Angle Class III patients : Success versus failure.

OBJECTIVES: Despite recommendations for early treatment of hereditary Angle Class III syndrome, late pubertal growth may cause a relapse requiring surgical intervention. This study was performed to identify predictors of successful Class III treatment. MATERIALS AND METHODS: Thirty-eight Class III patients treated with a chincup were retrospectively analyzed. Data were collected from the data archive, cephalograms, and casts, including pretreatment (T0) and posttreatment (T1) data, as well as long-term follow-up data collected approximately 25 years after treatment (T2). Each patient was assigned to a success or a failure group. Data were analyzed based on time (T0, T1, T2), deviations from normal (Class I), and prognathism types (true mandibular prognathism, maxillary retrognathism, combined pro- and retrognathism). RESULTS: Compared to Class I normal values, the data obtained in both groups yielded 11 significant parameters. The success group showed values closer to normal at all times (T0, T1, T2) and vertical parameters decreased from T0 to T2. The failure group showed higher values for vertical and horizontal mandibular growth, as well as dentally more protrusion of the lower anterior teeth and more negative overjet at all times. In adittion, total gonial and upper gonial angle were higher at T0 and T1. A prognostic score-yet to be evaluated in clinical practice-was developed from the results. The failure group showed greater amounts of horizontal development during the years between T1 and T2. Treatment of true mandibular prognathism achieved better outcomes in female patients. Cases of maxillary retrognathism were treated very successfully without gender difference. Failure was clearly more prevalent, again without gender difference, among the patients with combined mandibular prognathism and maxillary retrognathism. Crossbite situations were observed in 44% of cases at T0. Even though this finding had been resolved by T1, it relapsed in 16% of the cases by T2. CONCLUSION: The failure rate increased in cases of combined mandibular prognathism and maxillary retrognathism. Precisely in these combined Class III situations, it should be useful to apply the diagnostic and prognostic parameters identified in the present study and to provide the patients with specific information about the increased risk of failure.

Comparative bond strength of new and reconditioned brackets and assessment of residual adhesive by light and electron microscopy.

An average rate of bracket loss of between 4.7 and 6 per cent is to be expected in daily clinical orthodontic practice during a typical 2 year treatment period. For reasons of economy, detached brackets are commonly reattached after sandblasting to remove adhesive, or replaced with used brackets reconditioned by specialist companies. In the present study, sandblasting and specialist bracket-reconditioning procedures were systematically compared by comparative shear testing of rebonded, reconditioned, and new brackets (n = 160) using light- and chemically cured adhesives. Statistical analysis was carried out with Kruskal-Wallis and Mann-Whitney tests. The mean bond strength of reconditioned brackets was, in each case, lower than that of new brackets, with the lowest value obtained with sandblasted brackets. This nevertheless exceeded the minimum recommended value of 5-8 MPa. Bond strength was generally higher with chemically than with light-curing adhesive; the chemically curing adhesive provided bond strength on previously bonded enamel higher than the light-curing adhesive on intact teeth. Consistent with this, the results of the adhesive remnant index (ARI) demonstrated improved bonding with the chemically curing than the light-curing adhesive to the bracket base. Despite resulting in a weaker bond strength compared with new brackets, sandblasting brackets accidentally detached during orthodontic treatment will generally allow effective reattachment to be achieved. Bond strength can be improved with the use of a chemically cured adhesive. Used brackets reconditioned by specialist companies provide a second alternative to new brackets and higher bond strengths than sandblasted brackets.

In vitro release of phosphoric acid ester from self-etching primer.

Self-etching primers have simplified the process of direct bonding of dental resins, by eliminating the rinsing step after etching in conventional bonding, for example. Although it is generally assumed that all of the applied self-etching primer is incorporated into the resin, the possibility that a substantial amount remains free and extractable into a person's saliva has not been investigated. The aim of the present study was to examine this issue by bonding brackets to extracted teeth with self-etching primers under controlled conditions and determining the proportion of the applied phosphoric acid ester that is subsequently extractable by high-performance liquid chromatography. Approximately half of the applied acid ester was extractable and thus not integrated into the polymeric network following standard light curing. This was reduced to 40% when the curing time was doubled. Acid ester leaching was a rapid process that was essentially completed within an hour.

Indirect bonding--a new transfer method.

The aim of this in vitro study was to investigate both shear bond strength (SBS) by shear testing of indirectly bonded brackets, and the accuracy of a new transfer method, the Aptus bonding device (ABD). For comparison, the SBS of directly bonded brackets in two experimental arrangements was also measured. The precision of the positioning of the indirect bracket transfer was assessed by photographic superimposition and three-dimensional (3D) measurement of the bracket positions on the working and plaster models using a 3D laser scan. Statistical analysis was carried out by means of descriptive and explorative data using the SPSS program. To compare groups, a one-factor analysis of variance and post hoc tests (Tukey-HSD) were used. The level of significance was set at P < 0.05. SBS using indirect and direct bonding, with the same experimental arrangement and the same adhesives (Concise and Transbond), showed no significant differences. For direct bonding, using only one adhesive (Transbond), lower values were observed, but they were only statistically significant for the premolar teeth. The clinically required minimum bond strength of 6 MPa was achieved in all groups. Superimposition of the photographs of the indirectly bonded upper labial segment brackets showed no deviations. The results of the 3D measurement of the positions of the brackets on the working and plaster models only yielded small deviations (0.15 mm along the X-axis in the centre, 0.17 mm along the Y-axis, and 0.19 mm along the Z-axis). The ABD is a useful adjunct to bond placement and does not compromise bond strength.

A comparative in vitro study of the strength of directly bonded brackets using different curing techniques.

The aim of this study was to compare, by shear testing, the bond strengths after 1 and 24 hours of a light-cured resin (Enlight) and a light-cured glass ionomer cement GIC (Fuji Ortho LC) using various polymerization lamps (halogen, high performance halogen, xenon, and diode) for the direct bonding of brackets. The self-curing resin (Concise) was used as the control. The analysis was carried out using the SPSS program. For group comparison purposes, the single factor variance analysis (ANOVA) and the post-hoc test (Tukey's HSD) were used. The level of significance was established at P < 0.05. When comparing two mean values the t-test for independent random samples was employed. All polymerization lamps achieved the minimum bond strength of 5-8 MPa. With Enlight LV, bond strength was dependent on curing time (the halogen lamp achieved the highest bond strength of 10.0 MPa, P < 0.001, with a curing time of 40 seconds. The other lamps showed similar results) and on the mode of cure (the highest bond strength values were achieved by four-sided curing, P= 0.04). Fuji Ortho LC, on the other hand, was independent of the duration of light curing and the type of lamp used. The bond strengths of the resin-modified glass ionomer cement (RMGIC) were similar to or somewhat higher than those achieved with light-cured composite resin (P = 0.039) when lamps with short polymerization times were used, but were significantly lower (P< 0.001) when compared with the self-curing composite adhesive. After 24 hours, the bond strengths of all adhesives showed a significant increase: Enlight 19 per cent, Fuji Ortho LC 6.6 per cent, Concise 16 per cent. Bond failure occurred for Enlight at the bracket-composite resin adhesive interface in 90 per cent and with Concise in 57 per cent. However, Fuji Ortho LC showed far more cohesive and mixed failures, indicating an improved bond between bracket and cement.

A comparative study of polymerization lamps to determine the degree of cure of composites using infrared spectroscopy.

The aim of this study was to compare polymerization lamps of various technologies (halogen, high performance halogen, xenon, i.e. plasma arc, as well as diode lamps) to determine the degree of polymerization of composite probes using Fourier-transform infrared (FTIR) spectroscopy. To observe the light-induced curing reaction under a bracket, an attenuated total reflection (ATR)-FTIR was used. The results showed that the recommended curing times for all the polymerization lamps tested were adequate for successful polymerization of the composite used (degree of conversion approximately 60 per cent, which did not exceed 66 per cent after longer curing times). However, even after very long curing times, delayed curing of the composite must be taken into consideration as there was a decrease of approximately 10 per cent in FTIR band intensities (1637 and 3104 cm(-1)). ATR-FTIR spectroscopy showed that when bonding brackets with materials cured by light, uncured areas remain in the centre of the lowest layer of the adhesive.

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.

[The orthodontic treatment of deep bite in adults--a comparison of the straight-wire appliance and the segmented arch technic]. / Die kieferorthopädische Tiefbissbehandlung bei Erwachsenen--ein Vergleich der Straight-wire-Apparatur und der segmentierten Bogentechnik.

The purpose of the study was to analyse and compare deep overbite correction in adult patients carried out by a straight wire appliance and the segmented arch technique as recommended by Burstone. The sample comprised 50 adult, deep bite patients, 25 each treated with straight wire appliance and segmented arch technique. Plaster casts and lateral cephalograms made before and immediately after finishing treatment were analysed. Both techniques were successful in overbite correction; overbite reduction amounted to 3 to 3.5 mm. The straight wire appliance group demonstrated predominantly molar extrusion and as a result posterior mandibular rotation. A slight intrusion of 1 mm was seen in the lower incisor area. The segmented arch technique resulted in an incisor intrusion of 1.5 mm in the upper and 1.7 mm in the lower jaw. No substantiate extrusion in the molar area was found. The advantages of this technique are discussed.

Data and patterns of transverse dentofacial structure of 6- to 15-year-old children: a posteroanterior cephalometric study.

The aims of the present cross-sectional investigation were to provide normative data of selected dentofacial posteroanterior cephalometric measures and to describe the patterns of transverse dentofacial structure. The material comprised the P-A cephalograms of 588 Austrian schoolchildren (157 girls and 431 boys, who were 6 to 15 years old). All subjects were healthy, presented various types of occlusions, and did not receive orthodontic or orthopedic therapy. In studying the P-A cephalograms, 8 linear and 2 angular variables, as well as 10 ratios were used. The results of the study revealed that all skeletal widths and all ratios representing relations between the various breadths of the facial skeleton and the interorbital width demonstrated an increase when the measurements at the initial and final ages of 6 and 15 years, respectively, were compared. However, the maxillary intermolar width during the period from 9 to 12 years did not present any increase, and the mandibular intermolar width remained approximately the same during the whole observation period. The transverse dentoalveolar relationship in the incisal region remained very symmetric during aging. The standard deviations of most cephalometric variables were small when they were compared with their corresponding mean values. The present data are of value for the diagnosis of various types of dentofacial anomalies, for monitoring growth of persons or groups of corresponding age and race, and for comparison with other studies.

[A new method for the quantitative and qualitative measurement of tooth movements]. / Eine neue Methode zur quantitativen und qualitativen Messung von Zahnbewegungen.

A new method for the in vivo measurement of the movements of teeth is described. Measuring blocks are attached to brackets and tubes. Calibrated holes are drilled in each side of the blocks. Using an electronic sliding caliper, measurements are made in all three dimensions between moving teeth and blocks of anchored segments. With the aid of a computer programme, these measurements can be used to construct pictures of various teeth. By taking measurements at different stages of treatment, the movements of the teeth can be shown in three-dimensional images.

[Anterior tooth intrusion with the base arch: preactivation by tip-back bending or curvature?]. / Frontintrusion mit dem "Base-arch". Voraktivierung mittels Tip-back-Biegung oder Kurvatur?

Burstone's intrusion mechanics has been found to be effective in the treatment of a deep bite due to intrusion of the anterior teeth. The pre-activation of the intrusion arch by a tip-back bending shows a shortening in the activation. Measurements objectified the extent of the shortening and the resulting horizontal forces for TMA arches of a dimension of 0.017 x 0.025 inch relating to different distances between molars and anterior teeth and pre-activation by means of tip-back bending or curvature. The change of the vertical force in connection with a simulated intrusion of 5 mm was also registered. Clinical consequences of the therapy are discussed.

[The tooth transplant in orthodontic treatment planning]. / Das Zahntransplantat in der kieferorthopädischen Behandlungsplanung.

The analysis of all examined transplant cases combined treated with orthodontics shows a success rate of 76%. It must be underlined that the germ development at the time of the transplantation is of utmost importance. The best possible time proved to be at a root development of 2/3 to 3/4. Exact indication position, a careful atraumatic operation method and a short time of operation are also important factors of a successful transplantation. If all these preconditions are met, this method can be recommended.

[The effect of the vertical bracket position on the orthodontic finish]. / 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.

[The early treatment of progenia in the deciduous dentition compared to treatment in the mixed dentition]. / Die Frühbehandlung der Progenie im Milchgebiss im Vergleich zur Behandlung im Wechselgebiss.

The aim of this research was to examine the effect of the chin cap on mandibular prognathism (Angle class III) with or without a Fränkel appliance. 30 class III patients were examined. Head plates and casts made before and after active treatment were evaluated. The patients were divided into group I (initial X-ray incisivi decidui ID) and group II (initial X-ray incisivi permanentes IP). Group I (ID) showed a stronger skeletal response. Group II (IP) already showed more severe prognathic values in the initial X-rays. In group I (ID) a decrease of the gonial angle, SNB- and SNPog angle as well as an increase of both the ANB- and articulare angle were observed, however not in group II (IP) or at least not to the same extend. Overbite and overjet values reached the ideal values. In both groups dental compensation was observed.

[The positioner--a possibility for the fine adjustment of the occlusion objectively assessed by condylar measurements of the discrepancy between the ICP and RCP]. / Der Positioner--eine Möglichkeit zur Feineinstellung der Okklusion, objektiviert durch Kondymetermessungen der Diskrepanz zwischen IKP und RKP.

A group of ten adolescents was treated with fixed appliances at the Department of Stomatology and Oral and Maxillofacial Surgery, Graz. Subsequently the patients were fitted with a gnathological positioner. On the day of band removal ten sets of models were made and subsequently two, four and twelve weeks later. They were mounted on an articulator and cephalometric measurements were taken three times by each of the examiners. These records served to provide evidence of discrepancies of the condylar position between ICP and RCP in all three planes. In the second part of the examination, the patients were instructed to wear the appliance at night for another year. Casting of models, mounting in articulators and condymetric measurements were repeated as above. After wearing the positioner for three months, we observed a definite improvement of the occlusion and a wide conformity of the RCP and ICP measurements. After one year of night-time retention there was a slight increase of the mean values. In addition, we could establish statistically that condymetric model measurements are independent of the examiner and the method employed.