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Biomedical subjects

H Pancherz

Publications and source records attributed to H Pancherz.

At least 73 records · Page 4Linked to original sources
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.

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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↗
PubMed1987

Treatment with an orthopedic appliance system in relation to treatment intensity and growth periods. A study of initial effects.

The study comprises an analysis of the effect of treatment with a modified activator combined with a high-pull headgear during a standardized observation period of the initial 6 months of treatment. All patients (24 girls and 32 boys, aged 8.5 to 15 years) had severe skeletal Class II malocclusion. In the first part of the study, the effect of treatment with the appliance both day and night is compared with the effect when it was worn only at night. Only a small and nonsignificant difference was found, but the patients tended to cooperate better if they were instructed to wear the appliance continuously. In the second part of the study, the effect of treatment is related to the somatic maturation of the patients. Longitudinal records of standing height were used to assess whether treatment had been performed before maximal pubertal growth (prepeak period), during maximal pubertal growth (peak period), or after maximal pubertal growth (postpeak period). The skeletal effect was significantly greater in boys treated during the peak period than in those treated during the prepeak period and a similar tendency, although not significant, was found among girls. The number of patients treated during the postpeak period was too small for statistical analysis.

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PubMed1986

Masticatory muscle activity and hyoid bone behavior during cyclic jaw movements in man. A synchronized electromyographic and videofluorographic study.

Synchronized electromyography (EMG) and videofluorography were used to relate the EMG activity from the suprahyoid and masseter muscles and the movement of the hyoid bone to different phases of the jaw open-close-clench cycle. The subjects investigated comprised 19 adult males with normal dentofacial appearances. Five subjects were excluded from the analyses because of a uniform suprahyoid EMG pattern during cyclic jaw movements. The results from the remaining fourteen subjects revealed that mandibular opening was preceded by suprahyoid EMG activity and movement of the hyoid bone in an upward-forward direction. During jaw opening and the first half of the jaw-open phase, EMG activity was registered exclusively from the suprahyoid muscles. The hyoid bone was moved downward-backward during jaw opening. Mandibular closing was preceded by masseter EMG activity and movement of the hyoid bone in a further downward-backward direction. During jaw closing the hyoid bone moved upward and forward. Discrete EMG bursts from the suprahyoid muscles were occasionally registered simultaneously with the masseter EMG activity during jaw closing. No absolute reciprocity existed between suprahyoid and masseter muscle activity during cyclic jaw movements. A period of no EMG activity from either the suprahyoid muscle group or the masseter muscle was noted during the jaw-open phase and the occlusal phase.

Adult↗
PubMed1985

Dentofacial orthopedics in relation to somatic maturation. An analysis of 70 consecutive cases treated with the Herbst appliance.

Mandibular treatment changes were related to somatic maturation in 70 consecutive cases of Class II malocclusion (52 boys and 18 girls, aged 10 to 16 years) treated with the Herbst appliance for an average period of 7 months. Sagittal and vertical alterations in mandibular condylar growth and sagittal changes in molar and incisor tooth position were analyzed by means of mouth-open profile roentgenograms. The somatic maturity level of the patients was assessed by means of longitudinal growth records of standing height. The treatment period was related to the peak height velocity by dividing the patients into three growth-period groups: prepeak, peak, and postpeak. Herbst treatment resulted in Class I dental arch relationships in all patients. Post-Herbst treatment changes were not evaluated in this study. Sagittal condylar growth was increased and the mandibular molars and incisors were moved anteriorly. When the mandibular skeletal and dental changes were related to the subjects' somatic maturation, significant differences between the different growth periods existed in boys and tendencies were noted in girls as follows: sagittal condylar growth was most pronounced in the peak period, anterior molar movement was equally large in all growth periods, and anterior incisor movement was most extensive in the postpeak period. To take advantage of the increase in condylar growth response and to reduce the time of posttreatment retention, it is suggested that Herbst therapy be instituted close to peak height velocity.

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PubMed1985

The Herbst appliance--its biologic effects and clinical use.

The purpose of this article is to survey the Herbst bite-jumping method. An outline of appliance design and appliance construction is given. The effects of the treatment method on the dentofacial complex and on the masticatory system have been analyzed with the aid of dental casts, cephalometric roentgenograms, and electromyographic registrations from the masticatory muscles. The use and effectiveness of the Herbst appliance in the treatment of Class II malocclusions are exemplified by clinical cases, some of which were followed for 5 years after treatment. The Herbst appliance is most effective in the treatment of Class II malocclusions, provided it is used as indicated. Thus, the appliance must be limited to growing persons only. The treatment method should not be looked upon as a last resort to be used only when other treatment approaches have failed. Treatment prognosis is best in subjects with a brachyfacial growth pattern. Unfavorable growth, unstable occlusal conditions, and persisting oral habits after treatment are potential risk factors for occlusal relapses. As treatment with the Herbst appliance is performed during a relatively short period, the hard and soft tissues (teeth, bone, and musculature) would need some time for adaptation to the new mandibular position after the appliance is removed. Posttreatment retention as a routine with a removable functional appliance is therefore recommended.

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PubMed1984

A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment.

The purpose of this investigation was to evaluate cephalometrically the mechanism of anteroposterior occlusal changes in activator treatment. The analysis used made it possible to relate alterations in the occlusion to sagittal skeletal and dental changes in the maxilla and mandible. The sample consisted of thirty Class II, Division 1 malocclusion cases treated successfully with activators during an average time period of 32 months. Before- and after-treatment head films in centric occlusion were analyzed. The occlusal line (OL) and occlusal line perpendicular (OLp) through sella were used for reference. Linear measurements were performed parallel to OL. The following results were found: (1) The improvement in occlusal relationships in the molar and incisor segments was about equally a result of skeletal and dental changes. (2) Overjet correction averaging 5.0 mm was a result of 2.4 mm more mandibular growth than maxillary growth, a 2.5 mm distal movement of the maxillary incisors, and a 0.1 mm mesial movement of the mandibular incisors. (3) Class II molar correction averaging 5.1 mm was a result of 2.4 mm more mandibular growth than maxillary growth, a 0.4 mm distal movement of the maxillary molars, and a 2.3 mm mesial movement of the mandibular molars. (4) When the findings were compared with longitudinal records of persons with normal occlusion (Bolton standards), activator treatment seemed to inhibit maxillary growth, move the maxillary incisors and molars distally, and move the mandibular incisors and molars mesially. Mandibular growth appeared not to be affected by activator treatment.

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PubMed1984

The nasion-sella reference line in cephalometry: a methodologic study.

This investigation was undertaken to examine the effects of the registration error of the nasion-sella reference line (NSL) upon the values of angular and linear head film measurements. A comparison was made between two methods of constructing the NSL: (1) using the anatomically defined landmarks nasion and sella (L method) and (2) using the stable skull structures in the anterior cranial base (S method). Double registrations of sixteen pairs of lateral head films, from before and after 3 years of activator treatment, were performed by two observers. The results of the investigation revealed the following: (1) The registration error of the NSL affected angular and linear head film measures to a considerable degree. (2) The registration error was larger for the S method than for the L method. (3) The two observers differed in locating the NSL. The interobserver difference was especially apparent for the S method. The clinician should be aware of the NSL-registration error in the analysis of both single and serial radiographs. A misjudgment of the position of the reference line may result in diagnostic misinterpretations, thus affecting treatment planning or leading to false conclusions when the outcome of a particular treatment procedure is evaluated. In longitudinal studies covering a short period of growth, the L method would be the method of choice.

Adolescent↗
PubMed1982

The mechanism of Class II correction in Herbst appliance treatment. A cephalometric investigation.

Sagittal skeletal and dental changes contributing to Class II correction in Herbst appliance treatment were evaluated quantitatively on lateral roentgenograms. The material consisted of forty-two Class II. Division 1 malocclusion cases. Twenty-two of these were treated with the Herbst appliance for 6 months. The other twenty cases served as a control group. The results of the investigation revealed the following: (1) Bite jumping with the Herbst appliance resulted in Class 1 occlusal relationships in all treated cases. (2) The improvement in occlusal relationships was about equally a result of skeletal and dental changes. (3) Class II molar correction averaging 6.7 mm. was mainly a result of a 2.2 mm. increase in mandibular length, a 2.8 mm. distal movement of the maxillary molars, and a 1.0 mm. mesial movement of the mandibular molars. (4) Overjet correction averaging 5.2 mm. was mainly a result of a 2.2 mm. increase in mandibular length and a 1.8 mm. mesial movement of the mandibular incisors. (5) Anterior condylar displacement (0.3 mm.), redirection of maxillary growth (0.4 mm.), and distal movement of the maxillary incisors (0.5 mm.) were of minor importance in the improvement in molar and incisor relationships seen. (6) A direct relationship existed between the amount of bite jumping at the start of treatment and the treatment effects on the occlusion and on mandibular growth. For a maximal treatment response, it is suggested that the Herbst appliance be constructed with the mandible jumped anteriorly as much as possible, namely, to an incisal edge-to-edge position. The clinician should be aware of the dental changes occurring during Herbst appliance treatment and make sure that these changes are not incongruous with his over-all treatment goal.

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PubMed1982

Hemifacial microsomia treated with the Herbst appliance. Report of a case analyzed by means of roentgen stereometry and metallic implants.

The effect of Herbst appliance treatment on facial growth of one patient was recorded in terms of displacement of the mandible and the maxillary bones in relation to the frontal bone. The recordings were made with an accuracy of 0.1 degree and 0.05 mm. (S.D.). Before treatment the jaws were displaced posteriorly and to the affected side with growth, increasing the degree of retrognathia and facial asymmetry. During treatment facial growth was redirected and the jaws were displaced anteriorly and to the unaffected side, decreasing th degree of retrognathia and asymmetry. At the same time, however, the tilt of the mandible to the affected side was increased, possibly because of the morphologic and functional conditions of the jaws in hemifacial microsomia. The dental malocclusion was corrected partly through displacement of the jaws and partly through dentoalveolar adaptation.

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