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Biomedical subjects

H Pancherz

Publications and source records attributed to H Pancherz.

At least 19 recordsLinked to original sources
PubMed1992

[The "automatic activation" of labial arch wires during orthodontic treatment with expansion plates].

In laboratory experiments, progressive transversal jaw expansion with screw plates was simulated and the resulting increase in labial archwire force and deflection (autoactivation) was analysed. The results showed that progressive activation of a screw plate caused an initial increase in labial archwire force, which was subsequently followed by a minor reduction, and which stabilised after 90 seconds. Archwire force increases with the diameter of the wire, spring-hard wires developing higher forces than hard wires, and deflection decrease progressively with increasing size of the single activation step, as well as with increasing total activation. These results may have the following practical implications: on adjustment of the screw of the plate, the labial archwire is automatically activated to a reasonable degree for retroclination of the front teeth in screw plate treatment. This is particularly true when an 0.8 mm spring-hard wire is used. More constant archwire force is obtained by applying frequent small activations of the screw rather than a few large ones. To maintain the labial archwire force at a useful level, throughout treatment, fabrication of a new plate is recommended before the full range of screw adjustment is exhausted.

Activator Appliances↗
PubMed1992

[The orthodontic treatment needs of young adults. An epidemiological study of recruits].

In an epidemiological study of 370 recruits, the need for orthodontic treatment was investigated. Subjects who had previously received orthodontic treatment (n = 135) were compared with untreated subjects (n = 234). An unequivocal need for orthodontic treatment was ascertained in 50% of the recruits. Differences between previously treated subjects and untreated subjects were not Some 60% of the orthodontic measures had been carried out by an orthodontist, and 40% by a nonspecialist dentist. The results of treatment were generally unsatisfactory, although the success rate achieved by the orthodontists did appear somewhat higher than that seen with nonspecialist dentists.

Adolescent↗
PubMed1992

Long-term effects of Herbst treatment in relation to normal growth development: a cephalometric study.

The aim of this study was to evaluate the short- and long-term effects of Herbst appliance treatment in relation to normal growth and development. The sample consisted of 32 subjects (16 boys and 16 girls) with a Class II, division 1 malocclusion treated successfully with the Herbst appliance for an average period of 7 months. The patients were reinvestigated 6 months post-treatment when the occlusion had settled and at the end of the growth period, an average of 6.7 years (SD = 1.1 years) after therapy. The control group comprised of 32 subjects (16 boys and 16 girls) with excellent occlusion (Bolton Standards). Sagittal, skeletal, and dental changes occurring during three observation periods were evaluated on lateral cephalograms in centric occlusion. On a long-term basis, Herbst treatment improved the sagittal jaw base relationship, but did not normalize it. The sagittal dental arch relationship, on the other hand, was almost normalized.

Activator Appliances↗
PubMed1991

The nature of Class II relapse after Herbst appliance treatment: a cephalometric long-term investigation.

The purpose of this investigation was to assess the number of, and the interrelation between, skeletal and dental components that contribute to Class II relapse after Herbst treatment. A comparison was made between 15 relapse and 14 stable cases at least 5 years after treatment. Lateral cephalograms taken before and immediately after Herbst treatment, as well as 6 months and 5 to 10 years after treatment, were analyzed. The results revealed that relapse in the overjet and sagittal molar relationship resulted mainly from posttreatment maxillary and mandibular dental changes. In particular, the maxillary incisors and molars moved significantly (p less than 0.05) to a more anterior position in the relapse group than in the stable group. The interrelation between maxillary and mandibular posttreatment growth was favorable and did not contribute to the occlusal relapse. It is hypothesized that the main causes of the Class II relapse in patients treated with the Herbst appliance were a persisting lip-tongue dysfunction habit and an unstable cuspal interdigitation after treatment.

Adolescent↗
PubMed1991

Long-term effects of the Herbst appliance in relation to the treatment growth period: a cephalometric study.

The aim of this study was to analyse the long-term effects of Herbst treatment on the dentofacial complex with special reference to the growth period in which the patients were treated. The sample consisted of 40 male subjects with a Class II, division 1 malocclusion treated successfully with the Herbst appliance for an average period of 7 months. The patients were reinvestigated at the end of the growth period, on average 6.6 years (SD = 1.0 years) after therapy. Nineteen patients were treated before the maximum of pubertal growth (prepeak), 15 at the maximum (peak) and 6 after the pubertal growth maximum (post-peak). Sagittal skeletal and dental changes occurring during and after Herbst treatment were evaluated on lateral radiographs in centric occlusion. At the time of follow-up examination no group differences were seen in sagittal dental arch relationships. During the follow-up period after Herbst treatment maxillary and mandibular growth development were favourable and comparable in all three groups: mandibular growth exceeding maxillary growth by an average of 4.3 mm (SD = 2.4 mm). For natural reasons, however, the amount of jaw growth during the follow-up period was larger in the subjects treated before the maximum of pubertal growth than in the subjects treated at the later stages. The conclusion of this study was that the growth period in which Herbst treatment was performed did not seem to have any conclusive effect on the long-term results. However, in order to favour occlusal stability after treatment and to reduce the time of post-treatment retention, Herbst therapy in the permanent dentition at or just after peak height velocity of growth is recommended.

Activator Appliances↗
PubMed1990

[A critical analysis of the SNA, SNB and ANB angles in assessing orthodontic treatments].

The purpose of this longitudinal cephalometric study was to evaluate the influence of growth changes at nasion (N) on the position of the reference line NSL and consequently on the measurements of the angles SNA, SNB and ANB. Lateral head films from 46 orthodontically treated patients were evaluated over an average period of 3.7 years. The NSL reference line was defined with respect to growth changes at the N-point: A: no consideration of growth; B: consideration of growth in the sagittal plane; C: consideration of growth in the sagittal and vertical planes. The results showed that growth changes at nasion had a decisive influence on the position of the reference line NSL and thus also on the angles SNA, SNB and ANB. In order to avoid misinterpretations in the evaluation of orthodontic treatment results the growth changes at nasion must be taken into consideration.

Cephalometry↗
PubMed1990

Facial morphology and malocclusions.

The aim of this study was to determine whether sagittal and vertical aberrations in intermaxillary incisal tooth and jaw relationships were reflected in facial morphology. One hundred seventy-two children (79 girls and 93 boys), 12 to 14 years of age, were selected from the Orthodontic Department, University of Giessen. Pretreatment profile and frontal facial photographs as well as profile roentgenograms in centric occlusion for each child were made. The method consisted of (1) a personal appraisal of the existing incisal tooth and jaw relationship by visual inspection of facial photographs, (2) a validity assessment of these personal appraisals, and (3) a comparison of linear and angular measurements made from facial photographs and from lateral headfilms. The result of this investigation revealed that a large overjet and a Class II, Division 2 incisal tooth relationship were most often reflected in the face. A Class III incisal tooth relationship and an open bite, however, were difficult to detect. Sagittal maxillary and mandibular positions could only occasionally be determined on the basis of facial appearance, while a Class II jaw base relationship (large ANB angle) could easily be seen. The vertical jaw relationship (mandibular plane angle and anterior facial height index) could be determined with relatively high precision. When the measurements from the facial photographs were compared with those from the lateral headfilms, moderate to high correlations were found between skeletal and soft tissue readings: ANB angle (r = +0.63), mandibular plane angle (r = +0.93), and anterior facial height index (r = +0.86). It was concluded that sagittal and vertical dental and skeletal intermaxillary malrelationships were only partly reflected in the face.

Adolescent↗
PubMed1990

The skeletofacial growth pattern pre- and post-dentofacial orthopaedics. A long-term study of Class II malocclusions treated with the Herbst appliance.

The purpose of this investigation was to analyse cephalometrically the skeletofacial growth changes before and after dentofacial orthopaedics in 17 male subjects treated with the Herbst appliance. Herbst therapy was performed during an average time period of 7 months. The pre- and post-treatment periods in each subject were of equal lengths and amounted to an average of 31 months. No treatment was performed during the two control periods. When comparing the growth changes during Herbst treatment with those during the pretreatment control period it was found that: maxillary growth was inhibited and redirected; mandibular growth was increased; anterior mandibular growth rotation was arrested; sagittal intermaxillary jaw relationship improved; the skeletal profile straightened and the Go angle increased. During the post-treatment period several of the treatment changes reverted. The results of the study indicated that dentofacial orthopaedics using the Herbst appliance had only a temporary impact on the existing skeletofacial growth pattern.

Activator Appliances↗
PubMed1990

Long-term effects of the Herbst appliance on the craniomandibular system with special reference to the TMJ.

The purpose of this study was: (1) to analyse the long-term clinical implications of Herbst treatment on the masticatory system, and (2) to analyse the radiographic appearance of the temporomandibular joints at the time of follow-up using lateral tomography of the right and left TMJ. The sample consisted of 19 consecutive male subjects with a Class II, Division 1 malocclusion treated with the Herbst appliance for an average period of 7 months. The patients were reinvestigated at the end of the growth period (an average of 7.5 years after treatment). The anamnestic, clinical, and radiographic findings revealed that Herbst treatment did not seem to have any long-term adverse effects on the craniomandibular system.

Activator Appliances↗
PubMed1989

[The effect on chewing of treating distal bite with an activator].

The aim of this study was to analyse the influence of activator treatment on chewing efficiency. The subject material consisted of 60 children, adolescents and adults: Twelve children (ten years of age) with a Class II, Division 1 malocclusion were treated successfully with activators to a normal occlusion (16 years of age). Three normal occlusion samples, ten years (n = 12), 16 years (n = 12) and 29 years (n = 12) of age as well as an untreated Class II sample (n = 12), 16 years of age, served as control groups to the activator patients. The chewing ability was evaluated with the aid of a chewing efficiency test. The dental occlusion was appraised on dental casts. Recordings were made of number of erupted teeth, number of intermaxillary occlusal tooth contacts, overjet and overbite. The results revealed that chewing efficiency in activator patients was doubled from ten to 16 years of age. When comparing untreated subjects 16 years and ten years of age a greater chewing efficiency was seen in the older subjects. This was true for both Class II malocclusion and normal occlusion cases. Furthermore, in 16 year old subjects the chewing efficiency was comparable in treated and untreated normal occlusions as well as untreated Class II malocclusions. Thus, the investigation did not ascertain whether activator treatment per se resulted in an improved chewing efficiency. Furthermore, in the activator group no direct association existed between improvement in chewing efficiency and increased number of erupted teeth on one hand and increased number of intermaxillary occlusal tooth contacts, reduced overjet and overbite on the other. It is suggested that chewing efficiency is partly age related. The sagittal intermaxillary dental arch relationship doesn't seem to play an important role in determining chewing ability. However, harmonious interplay between the occluding teeth and the muscles influencing them (the muscles of mastication, the tongue-, lip- and cheek-musculature) is certainly of importance.

Activator Appliances↗
PubMed1989

Class II correction in Herbst and Bass therapy.

The purpose of this study was to make a quantitative evaluation on lateral cephalograms of skeletal and dental changes contributing to Class II correction in Herbst and Bass appliance therapy. From two male patient samples treated with either the Herbst appliance (n = 72) or the Bass appliance (n = 32) 18 pairs of subjects were selected. The subjects within each pair had to be in the same growth period at the time of therapy and to exhibit a similar pretreatment sagittal (ANB angle) and vertical (ML/NSL angle) jaw base relationship. Lateral cephalograms in centric occlusion taken before treatment and after 6 months were analysed according to the method of Pancherz (1982a). After six months of treatment the Bass appliance seemed to have a greater influence on mandibular jaw base position than the Herbst appliance, although no statistical significant differences existed between the treatment groups. The correction in overjet and sagittal molar relationships was more complete in the Herbst than in the Bass patients. This was due to greater dental changes (distal movement of the maxillary molars, proclination of the mandibular incisors) taking place in the Herbst subjects.

Activator Appliances↗
PubMed1989

[Morphology and position of mandible in Herbst treatment. Cephalometric analysis of changes to end of growth period].

The purpose of this investigation was to analyse mandibular morphologic and jaw position changes in Herbst treatment on a short and long term basis. The patient material consisted of 12 boys with a Class II, Division 1 malocclusion treated with the Herbst appliance for a period of 6 months. The subjects were examined before treatment, after treatment, 1 year after treatment and at completion of growth (7 years after treatment). 10 boys with the same malocclusion as the Herbst cases served as controls. The method comprised of an analysis of profile roentgenograms in centric occlusion and with the mouth wide open. Herbst treatment resulted in an increase in jaw length and mandibular prognathism. The gonion angle was opened. These changes were accomplished by an increase in sagittal condylar growth and by bone resorption at the posterior part of the mandibular lower border. During the follow up period after removal of the Herbst appliance the treatment changes reverted and were comparable to those of the control subjects. No statistically significant long-term influence of Herbst treatment on mandibular morphology and jaw position could be verified.

Activator Appliances↗
PubMed1989

[Position changes of mandibular condyle in Herbst treatment. Radiographic study].

The study aimed to analyse the short- und long-term changes in condyle position in Class II/1 malocclusions treated with the Herbst appliance. Cephalometric reoentgenograms from a Herbst group (n = 30, mean age 12.1 years) were compared to those of a Control group (n = 12, mean age 11.0 years). The total observation period was 3 1/2 years. Centric occlusion and mouth open profile roentgenograms (to visualize the condyle) were analysed at four occasions. Mandibular tracings from the mouth open headfilms were superimposed on the centric occlusion headfilms using the Nasion-Sella-Line (NSL) for reference. NSL and its perpendicle NSLP through Sella (S) were used as a reference grid for linear measurements. When starting Herbst treatment the condyle was displaced 6 mm anteriorly and caudally. After 7 months of treatment the condyle was located 0.8 mm caudally to the pre-treatment position. No difference existed, however, between the Herbst and Control group. During the total observation period of 3 1/2 years the condyle in both examination groups moved caudally and posteriorly. This was thought to be a result of normal growth changes. It was concluded that Herbst treatment did not have an adverse effect on the position of the condyle.

Activator Appliances↗
PubMed1988

Head posture and hyo-mandibular function in man. A synchronized electromyographic and videofluorographic study of the open-close-clench cycle.

Synchronized electromyography and videofluorography (lateral projection) were used to investigate the influence of altered head posture on hyo-mandibular movements, suprahyoid muscle length, suprahyoid working angle, and timing of suprahyoid and masseter muscle activity. Twelve adult male subjects with normal dentofacial morphology were investigated during the open-close-clench cycle. Using upright head position (Frankfort horizontal) as reference, several statistically significant observations were made during forward flexion and backward extension of the head. The results indicate that head posture is a significant factor in studies of mandibular and hyoid bone movements, and masseter and suprahyoid muscle function.

Adult↗