Postretention changes in canine position. Results of a long-term follow-up.

The aim of the present study was to evaluate sagittal, vertical and transverse changes in canine position and a possible correlation with relapse of lower anterior crowding. From a sample with a long-term follow-up of 15.7 +/- 4.4 years after treatment, patients with a full dentition were enrolled in the study. Post-treatment and long-term follow-up casts of 117 patients were measured and statistically analyzed. A decrease in intercanine width was found between post-treatment and long-term follow-up records, with more lingual inclination of the mandibular canine axis in the transverse plane. There was a significant correlation between maxillary and mandibular canine inclination. Concomitant changes were an increase in lower anterior crowding and a decrease in mandibular intercanine width. Relapse of anterior crowding has a multifactorial etiology. The results of this study suggest a possible influence of the canines. Functional causes in particular might have a profound influence and should be considered during treatment planning.

Bond strength of a fluoride-releasing bracket adhesive. Experimental study.

The aim of the study was to examine a new fluoride-releasing light-cured filling composite for its bonding and debonding qualities when used as a bracket adhesive. The material investigated was a hybrid composite containing a chemically modified fluoride apatite, which is claimed to provide the enamel with phosphate, calcium, and fluoride ions in the presence of an acid pH, recharging its resources of these ions through fluoride-containing toothpastes used in daily oral hygiene. Concurrently suitability as an enamel conditioner was tested in a new self-etching primer, which does not require water rinsing but is gently air dried instead. For comparison a conventional light-cure single-component adhesive was used together with 37% orthophosphoric acid. After application of the respective conditioners, mesh-backed metal brackets were bonded to 20 human premolars in each of the 2 adhesive groups and subjected to a shear test. Bond failure location was evaluated using the Adhesive Remnant Index (ARI). Average bond strength of the experimental bracket adhesive and the conventional etchant was 8.96 MPa. Conditioning with the self-etching primer led to a decrease of mean shear bond strength values to 6.55 MPa. Highest bond strength was determined in the control group (12.19 MPa). The bond strength results obtained in the shear test recommend the new material as a bracket adhesive to be used with orthophosphoric acid for etching.

Treatment and postretention changes in dental arch width dimensions--a long-term evaluation of influencing cofactors.

The aim of the present long-term follow-up study of orthodontically treated patients was to analyze postretention changes in arch width dimension and to isolate factors that may serve as predictors of long-term prognosis. Pretreatment, end-of-treatment, and postretention (at least 10 years) models of 226 cases with different malocclusions were used to measure intercanine and intermolar width, arch length, sum of the mesiodistal dimension of the incisors, irregularity index, crowding, molar and canine relationship, overjet, and overbite. To assess the influence of initial and end-of-treatment alignment, kind of treatment (extraction versus nonextraction) and the amount of expansion in postretention stability, the sample was divided into different subgroups. The findings indicate that postretention arch width relapse occurred more frequently in the upper intermolar (25.8%) and lower intercanine region (23.9%) than in the lower intermolar (19.0%) and upper intercanine (13.8%) region. Pretreatment and posttreatment alignment as well as the kind of treatment and the amount of expansion were found to be influencing factors. The study concludes by proposing a reassessment of the definition of stability. The influence of the pretreatment anomaly, kind of treatment, amount of expansion, and posttreatment alignment on long-term stability should be recognized. Patients should be apprised of treatment limitations before treatments.

How to deal with the drop-out in clinical follow-up studies: results of a long-term follow-up study of orthodontically treated patients.

The drop-out in a long-term follow-up study of former orthodontically treated patients was analyzed to avoid biased results. Since structural conformity of the responders (n = 299) and the potential study population (n = 1464) cannot be presumed on the basis of the clinical results, roentgenologic results, and questionnaires, analysis of the participating patients, the follow-up method was used. By means of questionnaires sent to all nonresponders, a comparison of responding and nonresponding patient characteristics was completed to find a presumed selectivity bias. The comparison of the participating patients (n = 299) and the total sample revealed that the responders live closer to the health center, had a longer treatment time, and a shorter posttreatment interval. Compared with nonresponders (n = 266), the responders were satisfied with the treatment result and had a higher dental Intelligence Quotient (IQ, concerning tooth and jaw position). Although a definite answer to the question of validity of the examined subsample was difficult to give, the description and evaluation of the parameters that might be reasons for missing at random respectively, not missing at random was recommended.

Post-retention crowding and incisor irregularity: a long-term follow-up evaluation of stability and relapse.

The aim of the present long-term follow-up study of orthodontically-treated patients (mean: 15.7 years) was to analyse post-retention changes and to reveal factors which may play a role as predictors for long-term prognosis. Pretreatment, end-of-treatment, and post-retention models of 226 cases with all types of anomaly were used to measure intercanine and intermolar width, arch length, and sum of the mesiodistal dimension of the incisors, Irregularity Index, crowding, molar and canine relationship, overjet, and overbite. In order to assess the influence of sex, initial and end-of-treatment alignment, type of therapy, amount of tooth movement, and presence of third molars on the extent of post-retention changes, the total sample was divided into subgroups. Findings indicated that post-retention crowding and incisor irregularity increased more frequently in the mandible than in the maxilla. Pretreatment variables such as increased mesiodistal incisor dimension, severe crowding and incisor irregularity, arch length deficiency, arch constriction, and increased overbite as well as post-treatment spacing, arch expansion, increased arch length, and residual Class II or III molar relationships were found to be associated factors in the process of post-retention increase of crowding and incisor irregularity. 'Overexpansion' was found to be a factor in mandibular incisor relapse.

[The effect of molar position on the distalization behavior of indirect headgear]. / Der Einfluss der Molarenposition auf das Distalisationsverhalten des indirekten Headgears.

The asymmetric indirect headgear is a frequently used method to achieve an unilateral distalization of a molar. Cases have been observed, however, in which the distalization does not proceed in the way or to the degree predicated by the geometry of the outer bow. Among other factors, this discrepancy can be attributed to the geometry of the inner bow. This study demonstrates quantitatively and qualitatively the influence unilateral mesial movement and/or molar rotation exerts on the force system of the indirect headgear. The study makes evident that a neutralization of the molar's sagittal asymmetrical position by means of adjusting the length of the inner bow cannot be omitted. The study recommends the use of special headgear tubes extended in an oro-vestibular direction to eliminate the asymmetrical dynamics which arise in cause of the mesial rotation of a molar.

[The force transmission of positioners in different degrees of incisor protrusion. An in-vitro study]. / Die Kraftabgabe von Positionern bei unterschiedlicher Schneidezahnprotrusion. Eine In-vitro-Untersuchung.

The purpose of this study was to examine the forces exerted on protruded upper incisors by tooth positioners. Methodologically an in vitro force measurement model was used. The tooth positioners were made of 7 readily available materials commonly used in orthodontics. The study found that the values of the forces, which ranged from 0.4 N to 14.0 N per tooth, are dependent on the material used and the degree of tooth protrusion. In addition, the study analyzed the changes in force over a 3-month period during which time the positioners were stored at 37 degrees +/- 1 degree C in an aqueous environment. This environment corresponds closely to that found in the mouth.

[A retrospective examination of the acceptance of removable appliances]. / Retrospektive Akzeptanzprüfung herausnehmbarer Geräte.

In order to study the subjective attitudes of patients and their parents to orthodontic treatment questionnaires were handed out to both groups. One hundred and forty five patient questionnaires and those answered by 114 parents formed the base of the study. The majority of the patients were only able to provide partial answers to precise questions about their treatment. Speech impairment, pressure, and salivation were given as being the most vexatious aspects of the treatment. The majority of the patients and the majority of parents favored removable appliances over fixed appliances. The patients' social environment did not negatively influence their attitude to orthodontic treatment.

[Early deciduous tooth loss--the mature or immature eruption of their permanent successors]. / Frühzeitiger Milchzahnverlust--reifer oder unreifer Durchbruch der bleibenden Nachfolger.

On the basis of 147 panoramic radiographs of 49 patients, this study investigated the influence of the premature loss of deciduous teeth on the formation of their permanent successors at the time of their eruption. Furthermore the study investigated the eruptive movement of the successor teeth at the time of eruption. In addition to detecting the accelerated emergence of still immature successor premolars, the study also determined that the extraction ot the deciduous molars before the age of eight years delayed the eruption of the permanent successors given the absence of an infected deciduous tooth with abscess formation. In relation to the eruptive movement of the permanent molars due to the premature loss of the second deciduous molar, the study ascertained a mesial movement of the first permanent molars and an accelerated eruption of the second permanent molars.

[Ethyl cyanoacrylate (Cyano-Veneer) as an orthodontic bracket adhesive. A comparative in-vitro study with Cyano-Veneer and a conventional orthodontic bracket adhesive]. / Athylcyanoacrylat (Cyano-Veneer) als kieferorthopädischer Bracketkleber. In-vitro-Vergleichsstudie mit Cyano-Veneer und einem konventionellen kieferorthopädischen Bracketkleber.

According to the claims of the manufacturer, aethylcyanoacrylate can be used to bond orthodontic brackets and some orthodontists have already adopted its use for this purpose. Because, however, the use of the material as thus applied has not yet been the object of research, the question of its adhesion to tensile forces immediately after bonding and after 50, 100, and 150 days of placement in a physiologic saline solution (0.9% NaCl) is the subject of this study. 40 bovine upper incisors were extracted from 20 animals for each of the four points in time. The brackets were bonded with Cyano-Veneer and Mono-Lok according to a randomized list. Mono-Lok, an adhesive from the group of common orthodontic adhesives, functioned as the reference material. The bonding strength of the brackets in relation to the tensile forces was measured by means of a "Zwickuniversalprüfmaschine" (Zwick universal testing machine). Immediately after bonding, the cyanoacrylate demonstrated significantly higher bonding strength values than Mono-Lok. At 50, 100, and 150 days in the physiologic saline solution, the bonding strength of both materials showed no significant difference. It can thus be concluded that, when wires are employed immediately after bonding, the danger of bracket loss is significantly reduced through the use of cyanoacrylate.

[The materials properties of the stock for positioners--an in-vitro study. I. The elastic behavior]. / Materialeigenschaften der Werkstoffe für Positioner--eine In-vitro-Untersuchung. I. Das elastische Verhalten.

The purpose of this study was to compare the physical and mechanical properties of materials for tooth positioners. 15 of these materials are in general use and four are experimental. Tensile strength at 20% elongation was observed and analyzed over a three-month period during which time the specimens were stored at 37 degrees +/- 1 degree C in an aqueous environment. The values of tensile strength covered a range from 24.9 MPa to 1.5 MPa depending on the particular material. Most of the materials displayed an increase in the module of elasticity over three-month period, but this increase was statistically significant in only one material (t-test, pmax < 0.00005).

[The subjective and objective assessment of the long-term follow-up findings an average of 17 years after the conclusion of therapy]. / Subjektive und objektive Bewertung von Langzeitnachuntersuchungsbefunden durch-schnittlich 17 Jahre nach Therapieabschluss.

Posttreatment and seven to 28-year postretention records and actual questionnaires of 240 orthodontically treated patients were assessed to evaluate dental awareness and the patients evaluation of posttreatment changes. 80% have regular dental visits and 44% of them have periodontal disease whereas 60% of those who responded having irregularly or no dental controls. 38% were aware of posttreatment changes, only increased and decreased overjet showed a significance in patients evaluation and objective situation.

[The effect of adhesive agents on the bonding strength of ceramic-composite. An in-vitro comparative study with 6 "porcelain primers" and a control group]. / Einfluss von Haftvermittlern auf die Verbundstärke Keramik--Composite. Eine In-vitro-Vergleichsstudie mit sechs "porcelain primern" und einer Vergleichsgruppe.

Orthodontic brackets were bonded to a total of 240 Biodent porcelain surfaces pretreated with a number of different porcelain primers. In a control group, 40 surfaces were pumiced, etched, rinsed and dried, and then bonded to similar brackets without the use of a primer. The test objects of group 1 (n = 140) and those of group 2 (n = 40) were tested for bond shearing strength in a material testing machine (Zwick 1441) after prior incubation in a corrosive fluid at a pH of 2.3 and a temperature of 37 degrees C for 24 hours and 21 days, respectively. The fracture sites were inspected and analysed. Incubation in corrosive fluid reduces the strength of the porcelain-composite bonding, the shearing strength and the number of fractures in the bonding decreasing. Damage to the porcelain was seen to occur after the use of Lee-Ortho-Prime and Bond-Por primers. All the primers tested can be used, although a bond shearing strength of less than 2 N/mm2 is at the lower limit of what can be accepted under the usual conditions of daily practice.

[Data analysis in long-term follow-ups of previously treated orthodontic patients]. / Datenanalyse bei Langzeitnachuntersuchungen ehemals kieferorthopädisch behandelter Patienten.

The structure of former orthodontically treated patients, who underwent a long-term follow-up study in October 1989, was evaluated. An attempt was made to contact 1429 former patients, whereby 28.8% did not get the invitations because they had changed their address. As the compliance of approximately 17 years postretention of the 1,018 patients depends on change of address, job, interest and death, 20% of these were willing to participate and get examined. A structural conformity of the controlled group and the patient total cannot be presumed due to the patients' answers in the follow-up study. Questionnaires will be sent to patients, who did not participate in the analysis, in order to avoid unilateral results.

[The subjective and objective assessment of the functional treatment results after combined orthodontic and oral surgical measures]. / Subjektive und objektive Bewertung der funktionellen Behandlungsergebnisse nach kombiniert kieferorthopädisch-kieferchirurgischen Massnahmen.

The status of temporomandibular joint and muscle function was examined in a group of 22 adult patients, who underwent combined orthodontic and surgical treatment. Even though nearly all patients were very content with the results of the therapy, 2/3 showed a rather reduced movement of the condyle after mandibular sagittal split osteotomy. The causing factors are: arthrosis, permanent displacement of the disc or a change of muscle function after surgery.

[[Klippel-Trenaunay syndrome--an embryonic developmental disorder. A case report with reference to the orthodontic symptoms]. / Das Klippel-Trenaunay'-Syndrom--eine embryonale Entwicklungsstörung. Fallbericht unter Berücksichtigung der kieferorthopädischen Symptomatik.

The Klippel-Trenaunay syndrome is a disturbance in the development of the mesodermal and ectodermal tissues occurring in utero. It is characterized by the clinical triad of unilateral soft tissue and bone hypertrophy, varicosities and hemangiomas. For dentists the orofacial manifestations of the syndrome are interesting: unilateral hypertrophy of the maxilla and mandible, mandibular joint and alveolar processes and tooth germs. In addition, the gingival margins are thickened, eruption is premature and there is marked facial asymmetry.

[Disorders of the sensitivity of the anterior teeth in children and adolescents]. / Sensibilitätsstörungen der Frontzähne bei Kindern und Jugendlichen.

1435 permanent incisors and canines were examined in 134 children and juveniles undergoing orthodontic treatment. Nearly 50% of the subjects had sustained trauma to their anterior teeth with equal numbers of boys and girls. Girls, however, were less often injured by direct contact. Pulp testing with dry ice from liquid CO2 showed disturbed sensitivity mainly of the upper anterior teeth. In the group with trauma the frequency of this phenomenon was increased compared to the group without trauma. The electric pulp tester did not prove suitable for sensitivity tests compared with dry ice testing.