# ABSTRACTS

## ENLARGED TONSILS AND THE EFFECT OF TONSILLECTOMY

Characteristics of the dentition and facial skeleton, posture of the head, hyoid bone and tongue.

Mode of breathing
Kerstin Behlfelt

Associations between craniofacial morphology, its development and growth on the one hand and functional factors on the other hand have been eagerly debated in the literature during the last 20 years.

The aim of the present thesis, based on five publications, was to evaluate the effect of enlarged tonsils and tonsillectomy on the dento-facial morphology, the posture of the head, the position of the hyoid bone and tongue, and on the mode of breathing. The material comprised 146 Swedish children (66 boys and 80 girls), 5.3-17.3 years old, with a mean age of 10.1 years. Of these children 73 were judged by one otolaryngologist to have enlarged tonsils and were, on this criterion, selected for the investigation. The remaining 73 children comprised the control group and matched the tonsil group for sex and age. The controls were nosebreathers and had no history or symptoms of Ear-Nose- and Throat problems. During the investigation 18 of the tonsil children underwent tonsillectomy and 29 remained unoperated. Comparisons between the groups were based on anamnestic and clinical records,

measurements on plaster study models and lateral skull radiographs.

The results indicate that the children with enlarged tonsils, when compared with the control children, had retroclined lower incisors, protruded upper incisors, shorter lower dental arch, smaller overbite, larger overjet and a greater incidence of lateral crossbites. Furthermore, they had retrognathic, posteriorly inclined mandibles, larger anterior lower facial height and skeletal open bite. They also displayed extended headpostures, low posture of the hyoid bone, anterio-inferior posture of the tongue and large oro-pharyngeal depth. 62.5% of the children in the tonsil group were mouthbreathers during the day and 84.7% during the night.

The effect of tonsillectomy was mainly associated with a dorsal reposturing of the base of the tongue, change in hyoid bone posture cranially and change to nosebreathing during the night. Furthermore, a decrease in lower inter-molar width and in the tendency to lateral crossbite, as well as a slight increase in the posterior lower facial height had occurred postoperatively. Associations between postural and functional changes mutually, as well as between these changes and morphological changes were found.

Enlarged tonsils thus seem to be associated with characteristic postural and functional pattern, which in its turn seems to have had some influence on the dentition and craniofacial morphology.

Department of Orthodontics
School of Dentistry
Karolinska Institute
Stockholm, Sweden

## THE CR-CO DISCREPANCY AND ITS EFFECT ON CEPHALOMETRIC MEASUREMENTS

Madelaine Shildkraut,
David P Wood, W Stuart Hunter

The purpose of the present study was to compare cephalometric measurements derived from a centric occlusion (CO) tracing with those of a converted centric relation (CR) tracing. The sample consisted of 68

consecutively treated patients, with a CR-CO discrepancy of 2 mm or greater in either the horizontal and/or vertical planes, measured at the condyles from mounted models. Comparisons were also made within the sample between 39 females and 29 males; and the 35 skeletal Class I and 33 Class II patients.

In analyzing the CR-CO discrepancy, the vertical component was greater than the horizontal in 96% of the sample. Every patient had a vertical component, although 10% had no horizontal component. Correlations between the horizontal discrepancy and the two tracings showed high values for approximately 50% of the measures, whereas little correlation was found with the vertical discrepancy.

Paired t-tests used to compare the CO and CR cephalometric values demonstrated significant differences (p<0.05) for the majority of the values studied. However, there were generally no differences between the groups of males and females, or between the skeletal Class I and Class II individuals. The results of this study suggest that to make a correct orthodontic diagnosis the mandible should be placed in centric relation rather than in the more traditional centric occlusion.

Angle Orthod
1994; 64(5): 333-342.

## SOFT TISSUE FACIAL PROFILE CHANGES AFTER ORTHODONTIC TREATMENT WITH FOUR PREMOLARS EXTRACTED

Luis Alberto Bravo

A study of the changes occurring in the soft tissue facial profile in a sample of 16 orthodontic female patients treated with extraction of four premolars led to the following observations: (1) The upper and lower lips moved back an average of 3.4 and 3.8 mm to the E line respectively; Sulcus superior and Sulcus inferior moved back an average of 1.6 and 2.3 mm to the E line respectively. (2) The mean change in the labiomental angle after treatment was almost null (0.1°). The mean change in the nasolabial angle after treatment showed an increase of 3.7°. There was an important individual
variability for both angular measurements. (3) The mean upper and lower lip protrusion relative to the Sn-Pg' line decreased 2.4 and 3.1 mm respectively. (4) The sulcus superior depth measured following Holdaway showed an average decrease of 0.9 mm. The mean changes of the integumental profile of the face relative to the H Line after treatment showed that the lower lip moved back an average of 1.4 mm; the distance from Sulcus superior to the H line decreased an average of 2.4 mm, and the distance from Sulcus inferior to the H line increased an average of 0.8 mm. (5) When comparing these changes to acceptable esthetic values for the variables used, we observed that only 12% of patients in our sample finished treatment with a clearly more flattened facial profile. (6) To avoid unesthetic soft tissue profile changes, extraction of premolars should not be performed, if possible, when the pretreatment cephalogram shows any of the following characteristics: Nasolabial angle ≥110°, Ls to Sn-Pg' line ≤3mm, Li to Sn-Pg' line ≤2mm, Ss to H Line ≤3mm, Li to H line ≤0mm.

**Angle Orthod**
1994; 64(1): 31-42.

## TEMPOROMANDIBULAR JOINT STRUCTURES: A COMPARISON BETWEEN ANATOMIC AND MAGNETIC RESONANCE FINDINGS IN A CORONAL AND AN ANGULATED CORONAL PLANE
MH Steenks, RLAW Bleys, TD Witkamp

Two temporomandibular joints from one specimen were investigated using magnetic resonance imaging and cryosectioning. Magnetic resonance images, photography of the tissue block surface, and on-tape histologic sections were compared. The left joint was imaged and sectioned in a coronal plane, and the right joint in an angulated coronal plane parallel to the long axis of the condyle. The temporomandibular joint disc could be seen in coronal and angulated coronal scans. The posterior band was imaged in

angulated coronal magnetic resonance scans throughout the temporomandibular joint both medially and laterally. In coronal scans only parts of the disc proper could be seen, depending on the level of imaging or sectioning. The densely plaited fibrous tissue of the intra-articular tissues could be seen in magnetic resonance imaging, primarily anterior to the condyle; this tissue corresponded to the low signal intensity in magnetic resonance imaging. Medial and lateral disc attachments as well as the temporomandibular joint capsule were imaged in some of the magnetic resonance scans in both the coronal and the angulated coronal scans. In diagnosing anteromedial, medial, and lateral disc displacements, angulated coronal temporomandibular joint scanning is preferred over coronal scanning.

**J Orofacial Pain**
1994; 8: 335-349.

## THYROID FUNCTION AND ROOT RESORPTION

**Efstratios Poumpros, Eric Loberg, Christer Engström**

The regulation of degradative activity such as phagocytosis and bone resorption in the periodontal region is greatly influenced by factors controlling general bone modelling. The purpose of this study was to determine if thyroxine has any influence on the occurrence of force-induced root resorption. Young male rats were divided into three groups: a group of normal rats, a control group in which appliances were placed, and an experimental group in which appliances were placed and I-thyroxine was administered (5 micrograms/kg bw for 12 days).

Root resorptions were induced by orthodontic force on the maxillary incisors. Fewer force-induced root resorption lesions occurred in the thyroxine group than in the control group. Alkaline phosphatase activity in the thyroxine group was significantly different from the normal and control groups. Thus, the decrease of resorptive lesions in the thyroxine group seemed correlated to a change in the bone modeling process, especially as related to the resorption activity.

**Angle Orthod**
1994; 64(5): 389-394.

## THE EFFECT OF INCISAL BITE FORCE ON CONDYLAR SEATING

**David P Wood, Kent J Floreani, Khadry A Galil, Walter R Teteruck**

The purpose of this study was to investigate the relationship between different incisal biting forces and condylar seating. Bite force was measured with strain gauges at the incisors in 22 adult subjects. The subjects were positioned with mandibles in retruded centric and with an opening not exceeding the range of hinge axis movement. Condylar movement was measured using standard true hinge axis location procedures. Condylar position was measured with no force, then with bite forces of 4.5 kg, 7.5 kg and a comfortable maximum.

Biting force significantly affected condylar movement (p<0.001). As incisal bite forces increased, so did the amount of condylar seating to an average of 0.49 mm anteriorly and 0.27 mm superiorly using maximum biting force.

Therefore when taking a centric relation record, a technique involving an anterior stop and sufficient biting force should seat the condyles more fully.

**Angle Orthod**
1994; 64(1): 53-62.

## REPELLING MAGNETS VERSUS SUPERELASTIC NICK-TITANIUM COILS IN SIMULTANEOUS DISTAL MOVEMENT OF MAXILLARY FIRST AND SECOND MOLARS

**Lars Bondemark, Jüri Kurol, Mats Bernhold**

Eighteen subjects, aged 12.5 to 18.3 years, with Class II malocclusion, deep overbite and moderate space deficiency in the maxilla were treated orthodontically using repelling rare earth magnets on one side and superelastic nickel-titanium coils on the contralateral side for simultaneous distalization of maxillary first and second molars. The force values of the magnets and the coils were calibrated to 225g at the start of treatment and when reactivation was performed every
fourth week [sic]. Tooth movement was analyzed by measuring dental casts, lateral photographs of dental casts, and lateral skull radiographs before and after 6 months of treatment. Mean distal molar movement was 3.2 mm for the supercoils and 2.2 mm for the magnets. Mean reduction of the overbite was 3.6 mm. Complaints of discomfort were more frequent for the magnet sides. The results indicate that superelastic coils are more effective than repelling rare earth magnets in molar distalization.

Angle Orthod

1994; 64(3): 189-198.

## QUANTITATIVE EVALUATION OF CRANIOFACIAL CHANGES WITH JASPER JUMPER THERAPY

Jason B Cope, Peter H Buschang, Donald D Cope, John Parker, HO Blackwood

Although the Jasper Jumper is becoming widely accepted orthodontic appliance, no quantitative guidelines exist for therapy. The purpose of this investigation was to describe the orthopedic and orthodontic changes associated with Jasper Jumper therapy.

A sample of 31 consecutively treated Class II patients was collected from three orthodontic practitioners who were using the same procedures and methods. Lateral cephalograms were taken immediately before appliance placement and immediately after appliance removal (mean interval of 0.4 years). The sample was case matched to untreated controls based on age, sex, and mandibular plane angle. The cephalograms were superimposed using anterior cranial base, maxillary, and mandibular reference structures to distinguish between growth/displacement and tooth movement. The results show that the majority of Class II correction was due to dental, rather than skeletal change. The maxilla underwent significant posterior displacement. The maxillary incisors retroclined and the maxillary molars tipped distally. Clockwise or backwards rotation was evident for the mandible. The mandibular incisors proclined significantly and the mandibular molars translated and tipped mesially.

Jasper Jumper therapy is a valuable procedure for the correction of Class II dental malocclusions. Like all other treatment modalities, there are both indications and contra-indications for its use.

Angle Orthod

1994; 64(2): 113-122.