Changes in mandibular mobility after different procedures of orthognathic surgery.

A prospective study including 63 adult Class II and Class III patients was carried out in order to examine short- and long-term effects of four different treatment methods on mandibular mobility. The patients were treated either (Group A, control-group) orthodontically alone or (Group B) by a LeFort I-osteotomy, a (Group C) mandibular advancement or (Group D) a two-jaw surgery/mandibular set-back. In the surgery-groups (B, C, and D) maximum opening, protrusion and lateral excursions were measured 2 days pre-operatively (T0), and 3, 8, 14.5, and 25.5 months post-operatively (T1-T4). In the control-group (A) at T0 and T4 was measured, only. Significantly differing effects of the four treatment methods on mandibular mobility were detected. (A) Orthodontic treatment alone, (B) maxillary advancement by LeFort I osteotomy, and (D) two-jaw surgery/mandibular set-back osteotomy did not influence mandibular mobility permanently. Temporary decreases in groups B and D (P less than or equal to 0.05) were observed, however. In contrast, permanent reductions after (C) mandibular advancement took place (P less than or equal to 0.001). Longitudinal survey showed that in all surgery groups recoveries were limited to a short period of 3-14.5 months, depending on the movement. Surprisingly, a closer similarity between the LeFort-I group (B) and the two-jaw surgery group (D), rather than between the sagittal-split groups (C and D), was seen indicating that the problem of reduced mobility after orthognathic surgery can be limited to Class II therapy. It was concluded that in Class III therapy, the application of rigid fixation in combination with a method of maintaining condyle-position, thereby dispensing with maxillomandibular fixation, prevents permanent reductions in mobility and guarantees a rapid recovery to pre-operative mobility levels.

Positioning control of the upper incisors in orthognathic surgery. Pre-operative planning with the Model Positioning Device and intra-operative application of the Sandwich Splint.

In orthognathic surgery a three-dimensional positioning of the maxilla is possible by means of the Le Fort I osteotomy and subsequent maxillary movement. In treatment planning and at the time of surgery it is very important to achieve an exact positioning of the upper incisors in relation to the upper lip and the rest of the skull. The Model Positioning Device described here allows three-dimensional positioning of the upper incisors in one- or two-jaw surgery. The reference plane is the upper surface of the upper part of a semi-individually adjustable articulator. The application of the Sandwich Splint enables the three-dimensional positioning of the maxilla in relation to the rest of the skull. The Sandwich Splint ensures that the vertical position of the mandible in relation to the rest of the skull above the osteotomy plane is exactly reproducible in the pre- and post-operative situation in both model surgery and at time of surgery. To this mandibular position the maxilla is positioned in three dimensions, as preplanned. The vertical dimension, which is identically reproducible before and after surgery is measured with a caliper. After surgery the mandible can be rotated into the planned new intercuspidation.

[Clinical and instrumental examination of tongue motor function]. / Zur klinischen und instrumentellen Untersuchung motorischer Zungenfunktionen.

The examination of tongue motor functions requires a clinical examination of voluntary movements as well an objective evaluation of the intraoral movements during speech, deglutition, mastication and during rest. For a comparison with the simple visual assessment of voluntary movements with the mouth opened, intraoral tongue movements have been studied using various techniques. The use of lateral x-ray palatography and electromagnetic articulography (EMA) for objective intraoral measurement of tongue motor activitiesis described. Case examples are given for simultaneous recording of midsagittal movements of the tongue, the mandible and the velum during swallowing and speaking.

[Intraoral condyle-related positioning of the maxilla in Le Fort 1 osteotomies]. / Intraorale gelenkbezügliche Positionierung des Oberkiefers bei Umstellungsosteotomien.

A new technique for positioning control in Le Fort I osteotomies is presented. This intraoral procedure allows three-dimensional positioning of the condyles in the desired centric or therapeutic relation and of the maxilla at the same time. It combines the intraoperative use of the "Condylar Positioning Appliance" with the "3D Doublesplint Method".

[Growth of the facial skeleton and biomechanics of the stomatognathic system]. / Wachstum des Gesichtsschädels und Biomechanik des stomatognathen Systems.

Biomechanical analysis of the stomatognathic system yields that the linkage between posterior and anterior guidance can be modelled by a link quadrangle (throttle crank) with closed linkage. Within this gear system the biochemical ideal position of the couple-line (functional length of the mandible) possesses a special meaning in centric occlusion: Along this line the gear system can be stretched without altering its essential mechanical properties. Interindividual comparison of the arrangement of mandibulary and maxillary structures related to the ideal initial position of the couple-line presents interindividual constants of arrangement and of growth. It is possible to define an individual, non-orthogonal system of coordinates. Its origin represents the individual center of growth. During growth special skeletally defined points run along radius vectors of this center. The rate of growth can depend on the angle between radius vector and couple-line.

Control of vertical position of the maxilla in orthognathic surgery: clinical application of the sandwich splint.

The Le Fort I osteotomy can be used to change the position of the maxilla in all three dimensions. A presurgically fabricated occlusal splint is used to reproduce the planned sagittal and transverse position of the maxilla. Various methods for determining the proper vertical position have been described. The major difficulty in vertical control when these techniques are used is the sagittal change of the lower reference point as the maxilla is advanced. The relative error in the vertical plane increases with larger sagittal movements. The sandwich splint technique, with two stable intraoral reference points, can be used to ensure proper vertical positioning of the maxilla. This method enables exact measurement of the vertical dimension during cast surgery and in the operating room. Vertical measurements are based on the relationship between the mandible and skull base. This distance remains constant during splint fabrication and when the splint is used at surgery. Postoperatively, the mandible can be rotated into the new centric occlusion.

Condylar position control during maxillary surgery: the condylar positioning appliance and three-dimensional double splint method.

A new method for positioning the maxilla and condyle after Le Fort I osteotomy maintains the patient's vertical dimension (ie, the relation of the mandible to the skull above the osteotomy plane) in the preoperative and postoperative positions during both cast surgery and actual surgery. During surgery the condylar positioning appliance is fixed to the anterolateral zygoma and the lateral cortex of the mandibular ramus bilaterally to orient the mandible in centric relation. The condylar positioning appliance is used with the three-dimensional double splint method. Two prefabricated splints enable three-dimensional positioning of the maxilla in the fixed mandibular position during surgery. Postoperatively, the mandible can be rotated into the new centric occlusion.

[Arrangement of the stomatognathic coupling system in the cranium]. / Die Anordnung des stomatognathen Koppelsystems im Schädel.

Interindividually the stomatognathic coupling system is coordinated with the base of the skull with relative consistency. This observation allows the gearing parameters of the posterior guidance to be determined with the aid of conventional axiography. Thus, the curvature of the individual anterior guidance can be assessed for reconstructive purposes and the coordination of the anterior and posterior guidance can be generally estimated by means of functional analysis. Thus, the simple, commonly used diagnostic methods of functional analysis can be applied for the biomechanically harmonic coordination of the anterior and posterior guidances in reconstructive treatment and functional analysis.

[Differences of clinical and axiographic function parameters in patients with skeletal Class II and Class III anomalies]. / Die Unterkiefermobilität bei Klasse II und III Individuen.

21 young individuals with skeletal and dental class II-relationships were compared to an analogous group of class III individuals as to their mandibular range of motion. The measurements of clinical movements in pro- and laterotrusion as well as the lengths of axiographic tracings showed a significantly reduced capacity of motion in the class III group. Because all examined individuals exhibited undisturbed TMJ-function or, at most, had mild symptoms (Helkimo-indexes 0 or 1), the reported findings cannot be interpreted as signs of pathology, but seem to demonstrate the broad range of normality.

Mobile connection of veneer crowns after orthodontic closure of a wide diastema in the maxillae. A clinical report.

A new, mobile splint for artificial crowns is suggested after orthodontic closure of a wide diastema mediale. A smooth mandibular movement in all excursions in considered essential. This approach sustains a physiologic load on the periodontium and prevents a recurrence of the diastema. The restorations in Fig. 6 have been stable and comfortable for 2 1/2 years with independent mobility of each tooth. Similar splinted prosthodontic devices inserted have also been successful.

[The results of scanning electron microscopy research on interdental stripping in vitro]. / Ergebnisse rasterelektronenmikroskopischer Untersuchungen zum interdentalen Strippen in vitro.

In an in-vitro study the abrasive qualities of different orthodontic finishing strips were evaluated on the enamel surfaces of human teeth by means of a scanning electron microscope. As a result we can state that even the use of the finest finishing strip cannot eliminate the deep furrows that resulted from prior abrasion with a strip that is more coarse. The remaining furrows caused by the abrasive procedure are so deep and wide, that plaque accumulation may well be expected therein, and thus be predisposing for caries and periodontal pathology.

[Changes in axiographic patterns in orthodontic treatment. A comparison of findings in upper and lower early displacement pre- and two month post-operation]. / Die Veränderung axiographischer Aufzeichnungen durch kieferorthopädische-kieferchirurgische Eingriffe. Ein Vergleich von Befunden bei Ober- und Unterkiefer-Vorverlagerungen prä- und zweieinhalb Monate postoperationem.

It has been shown that electronic axiographic tracings of patients 2.5 months after a surgical advancement of the maxilla by Le-Fort-I osteotomie changed only slightly in comparison to preoperative tracings. The sagital opening path as well as the sagital protrusive path showed alterations in curvature. On the other hand sagital split osteotomie with consecutive advancement of the mandible influenced axiographic patterns profoundly. We found almost regularily shortenings of the tracings and often loss of curvature.

[Basic documentation in the interdisciplinary cleft lip, alveolus, and palate consultation. Development of computer-corrected basic data]. / Basisdokumentation in der interdisziplinären LKG-Sprechstunde. Entwicklung eines computergerechten Befundbogens.

The presented anamnestic sheet with its detailed subcategories is the basis for a computer-aided documentation system for longterm follow-up of patients with lip, alveolar, and palatal clefts. The expected result is a reduction of later treatment requirements.

Plaque accumulations caused by interdental stripping.

Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evaluated with the scanning electron microscope (SEM). Even under in vitro conditions with the finest finishing strips, it was not possible to produce an enamel surface free of the furrows that result from the initial abrasion caused by the coarse strip. Enamel surfaces stripped gradually from coarse to superfine were left in the mouths of patients for 12 weeks and evaluated with the SEM. The edges of the furrows were found to be smoother but the furrows remained wide and deep enough to facilitate more plaque accumulations than those on untreated surfaces. The use of dental floss did not result in prevention of plaque accumulations along the bottom of the furrows.

Interactions between motor units in modulating discharge patterns of primary muscle spindle endings.

Discharge patterns of group Ia afferents of muscle spindles in the (isometric) cat semitendinosus muscle were recorded when subjected to the influence of contractions of three motor units elicited by stimulation of three alpha-efferents with different regular or stochastic stimulus patterns. In order to study conditioning interactions between motor unit contractions, defined time constellations of stimuli to different motor units were isolated from the stimulus trains by electronic means. This technique was also applied to discharge patterns of two Ia fibres to isolate "correlated discharges." The effects of defined time constellations of stimuli upon discharge patterns of single Ia afferents or "correlated discharges" of pairs of Ia afferents were assessed by poststimulus time histograms (PSTHs). It turned out that the influence exerted by one motor unit on spindle discharges was more or less strongly modulated by actions of the other motor units, dependent on the relative timing of their contractions. These effects could in part be explained by the relative locations of motor units and spindles within the muscle. These results are discussed with respect to possible mechanisms of low-amplitude physiological tremor.

Some methods to study information transmission through multi-channel neuronal systems.

Methods are proposed to isolate nearly simultaneous events or events with specific time relations to each other from two (or more) stimulus or spike trains. The methods can be implemented by means of a digital computer, but were implemented here with simple electronic hardware to present an alternative. The usefulness of these methods is demonstrated on data from cat experiments in which the influences of several motor units activated in parallel upon muscle spindle discharge patterns were studied by use of poststimulus time histograms (PSTHs). The contractions of one motor unit can interfere with the effects of others on muscle spindle discharges. In order to show this conditioning influence quantitatively, the integral of the PSTH is shown graphically as a function of the time interval between contractions of two motor units. These methods may help to elucidate some features of interactions between parallel neuronal channels bearing on the problem of the kind of information and how the latter is transmitted through complex multichannel systems.

Patterns of parallel signal transmission between multiple alpha efferents and multiple Ia afferents in the cat semitendinosus muscle.

1. Certain features of signal transmission from multiple alpha-axons to multiple Ia fibres via extrafusal muscle tissue were studied by stimulating three ventral root filaments separately and simultaneously and by recording spike trains from three dorsal root filaments. 2. Post-stimulus time histograms (PSTH) revealed widely graded influences of single motor unit contractions on different muscle spindles, thus confirming results of Binder et al. (1976, 1980a). 3. In most instances, the signal transmission from a single motor unit to a single Ia fibre was disturbed to varying degrees by concomitant activity from other motor units. 4. This deterioration of signal transmission can probably be compensated for, at least in part, by correlations between discharge patterns of two or more Ia fibres induced by the "common input" of motor unit activity. 5. These correlations showed a topographical pattern such that a peak in the cross-correlogram (CCH) occurred at zero time for pairs of spindles located virtually in parallel to each other, and was shifted away from zero time as a function of the serial distance between spindles in the longitudinal muscle fibre direction. 6. Fusimotor innervation had complex effects on correlations between Ia fibre discharge patterns. It might de-correlate the latter as well as favour new correlations. 7. The possible role of topographical correlation patterns in the afferent reflex limb for tremor suppression is discussed.