The aim of this retrospective study was to compare the treatment results and the number of required treatment appointments between the variable anchorage straight wire technique (VAST) and the straight wire (SW) technique. The subjects were 53 Caucasian patients of both sexes (25 males and 28 females, mean age 13.5 years at the start of treatment), with an overjet > or = 4 mm and an overbite > or = 3 mm. The patients were divided into four groups, VAST (n = 31) or SW (n = 22), extraction or non-extraction, and were treated by the same orthodontist. Variables from two lateral cephalograms obtained before and at the completion of active treatment, and the number of scheduled appointments were compared between the two techniques. The main difference between the two techniques was the bracket design. With the VAST, the bracket allowed both tipping and parallel movements with the possibility to combine double archwires. Due to the influence of the Begg technique, no extra-oral traction was needed in the VAST groups and Class II elastics were used at the start of treatment. Both techniques seemed to produce equal treatment results. However, in this study, it was shown that in deep overbite correction, the VAST required fewer scheduled appointments than the SW technique.

The influence of the anticonvulsive drug phenytoin on the periodontal tissues during orthodontic tooth movement in the rat was studied. The experimental and the control group each consisted of 10 Sprague-Dawley rats. The test group was injected daily with phenytoin during the experimental period of 6 weeks. A fixed appliance for expansion was applied on the first molars in both groups after 2 weeks (day 15). At the end of the experiment (day 42), radiographic measurements revealed less tooth movement in the phenytoin-treated rats. Compared to the control group, significant histologic changes in the periodontal tissues such as increased density of fibroblasts, decreased number of osteoclasts in contact with alveolar bone wall of the pressure side and deeper layer of non-mineralized osteoid on the tension side were observed in the phenytoin group.

Orthodontic treatment of eight overbite cases with a maxillary fixed lingual arch appliance with anterior biteplane involved a reduction in overbite of 4 to 7 mm between the upper and the lower front teeth and a first molar separation of 2 to 4 mm. After a treatment period of 3.5 to 5 months, occlusal contact between the upper and the lower molars was established. The appliance was then removed, and permanent overbite reduction was secured with an edgewise appliance. With the subtraction technique, 15 temporomandibular joints were radiographically investigated in the retruded position for change of condylar position on the glenoid fossa before and directly after insertion of the appliance, as well as after achieved molar contact. All condyles changed position directly after the bite opening, indicating that pure rotation did not occur. The direction of movement varied not only between subjects but also between the two condyles of each subject. With one exception, none or very small further positional changes occurred during treatment. No imaged signs of hard structure remodeling were observed. It may be concluded that other factors than change of condylar position must be responsible for the therapeutic effect of the bite-opening appliance that has been demonstrated in an earlier study.

A single injection of 1-hydroxyethylidene-1, 1-bisphosphonate inhibits the formation of acellular cementum in rat molars. Instead, an atypical hyperplastic cementum is formed. In this study the resistance of this cementum to resorption was tested by applying an orthodontic force. It was found that roots lacking acellular cementum were readily resorbed. The readiness with which the atypical hyperplastic cementum was resorbed without any increase in multinucleated osteoblasts may offer useful opportunities to study the different phases of hard-tissue resorption.

Light and scanning electron microscopic (SEM) examinations were used to study the hyaline zone and associated root resorption after orthodontic treatment of the upper first molars of rats. The orthodontic treatment consisted of a fixed buccal expansion appliance with an initial force of 250 mN. The animals were divided into nine experimental groups with orthodontic treatment and one control group without orthodontic treatment. Three groups were sacrificed immediately after 1, 3, and 7 days of treatment, and six groups after 7 days of treatment followed by 1, 2, 3, 4, 5, and 6 weeks without treatment. A hyaline zone on the pressure side of the mesial root was identified at the light microscopic level of examination as well as the SEM examination as early as 1 day after the initiation of treatment. In the SEM it was found that on the roots of teeth studied in the first few days after initiation of treatment the hyaline tissue was so firmly attached to the root that it remained in place during the extraction and preparation procedures. After longer treatment periods these hyaline zones were lost at extraction or during the preparation for the SEM examination. The cementum surface under the hyaline zone had a smooth appearance suggesting that the surface had been modified by substances released from the hyaline zone. After 1 week of treatment, resorption in the cementum could be noticed. The resorption extended to the dentine as uncovered dentinal tubuli were found. Formation of reparative cementum started two weeks after treatment. Changes in the cementum surface as well as root resorption cavities could be seen for as long as 6 weeks after the cessation of orthodontic treatment.

SUMMARY The purpose of the present study was to compare the vertical change in the incisor and molar areas caused by insertion of a bite opening appliance and to analyse the occurrence of rotation and eruption during the following treatment period (mean 4.3 months). Eight patients between 15 and 24 years of age with vertical overlaps ≥ 4mm were treated by means of a maxillary fixed lingual arch appliance with an anterior bite plane. The retruded mandibular position was recorded with cold cure acrylic before treatment, immediately after insertion of the fixed appliance, and after removal of it. Vertical overlap and separation between the first molars was measured at each of these occasions. Finally, tooth movements during eruption were measured on the indices in the area of the second molar. The results showed that, independent of the amount of bite raise, the relation between frontal and molar area bite raise was approximately 2:1 for six and 5:3 for two patients. There was a significant difference in thickness of indices from registrations I and III in the second molar area indication not only eruption during bite opening therapy but also buccolingual rotation.

Dentoalveolar ankylosis is a common complication after replantation of teeth with injured periodontal ligaments. This is a serious complication for the tooth since it leads to progressive root resorption. In young individuals it may also cause infra-occlusion and reduced development of the alveolar process. The purpose of this study was to develop a method applicable to rats in order to follow the effect of systemic and local factors on the development of ankylosis and their possible effect on the length of the functional period of the ankylosed tooth before exfoliation.The maxillary first molars in adult rats were extracted. The periodontal ligaments were devitalized or removed before replantation of the teeth. Dentoalveolar ankylosis was clinically established 2 weeks after replantation. Induction was most reproducible after devitalization or removal of the PDL cells with Dakin's solution and after keeping the rats on a liquid diet up to 3 weeks after replantation. Exfoliation of the teeth usually occurred 6 weeks after replantation.Histological examination showed that the PDL was replaced by bone. The ankylosed teeth showed root resorption to a varying degree. The resorption was in some cases occasionally located in the supra-crestal part of the tooth. A bone-like tissue in the root canal was a rather common finding. In one of the ankylosed teeth cartilage formation was found adjacent to the cementum.

Changes in incisor inclination and position in both jaws of children during the first 5 years after adenoidectomy were studied. The main change is a significant increased labial inclination of the incisors for the adenoidectomy groups. All variables that measure the labiolingual position of the mandibular incisors confirm a significant labial incisor positioning for both sexes. Stepwise regression analysis shows that 41% to 44% of the incisor proclination after adenoidectomy is accounted for by two regressors-sex (female) and increase in the sagittal size of the nasopharynx. The study supports the hypothesis that a changed mode of breathing after adenoidectomy is associated with significant labial positioning of the incisor teeth.

Cystic fibrosis (CF) is a hereditary metabolic disorder with clinical symptoms of abnormal mucus production. This blocks the airways, gives pancreatic insufficiency, and increases sweat electrolytes. The progressive respiratory disease often leads to respiratory insufficiency and cor pulmonale. The aim of the present investigation was to examine the facial morphology in children with cystic fibrosis. The sample comprised 11 children with cystic fibrosis, who were divided in two groups, one with gastrointestinal disorders and the other with predominantly respiratory insufficiency. Eleven healthy children with normal occlusions were selected as controls. Lateral skull radiographs obtained in natural head posture were digitized, and linear and angular variables for the different groups calculated and compared statistically. The cystic fibrosis group showed open bite, decreased posterior facial height, increased mandib-ular and craniocervical inclination. Additionally, within the CF-group, the children with respiratory insufficiency differed more from the controls than the children with gastrointestinal disorders. Despite the small number of subjects, the facial morphology of the CF children showed a similar pattern to that of children with nasal respiratory obstruction due to enlarged adenoids or tonsils.

The sucking pattern and intra-oral negative air pressure were studied simultaneously with the cheek/lip pressure in 12 children when sucking a dummy. The cheek/lip pressure was measured at the canine and at the second primary molar on the right side of the upper dental arch. The cheek/lip pressure peaks followed the intra-oral negative air sucking pressure peaks continuously. In the canine region the mean value of maximum cheek/lip pressure was 54 g/cm2. The corresponding value at the second primary molar was 21 g/cm2. During dummy sucking the mean cheek/lip pressure was 3.4 times higher against the canine compared to the second molar (P less than 0.001). The intra-oral negative air pressure was approximately the same whether the cheek/lip pressure was measured at the canine or at the second primary molar. The results indicated that the circumoral muscles were especially active during dummy sucking, in addition to the cheek pressure in the canine region.

In a sample of 107 boys and girls registered at 8, 11, and 15 years of age and 22 adults the statural height and the height and length of the cervical vertebrae, measured from lateral skull radiographs, were studied. The height and length of the vertebrae increased with age among the children and were non-significantly higher for the girls in each age group. The 15-year-old girls matured earlier, reaching adult values at this age. The 15-year-old boys still showed significantly smaller values for vertebral height and length compared with the adult men. Statural height was significantly correlated with the variables for vertebral growth at 8 and 11 years, whereas there was no correlation at 15 years of age among the children who had passed the pubertal peak height. The development of the vertebrae showed similarities with earlier reported skeletal maturity indicators found in the hand-wrist area and could as such offer an alternative method of assessing maturity without the need for hand roentgenograms.

The present investigation was undertaken in order to study the velocity of orthodontic tooth movement in rats and the effect of the hormonal changes that occur during pregnancy or with fluoride, which is one of several trace elements that affect hard tissue metabolism. Adult, female Sprague-Dawley rats were separated into three groups: non-pregnant, pregnant, and non-pregnant NaF-supplied. All rats were treated with a fixed orthodontic appliance which moved the upper first molars in a buccal direction during 21 days. The appliances delivered an initial force of 150 mN. Repeated intra-oral, standardized radiographs were taken during the experimental period, and at the end of the experiment the maxillae were examined histologically. The velocity of tooth movement was calculated after measurement of the radiographs. The first molars were moved in a buccal direction in all groups. The mean value of the expansion from day 0 to 21 was significantly higher among the pregnant rats (0.64 mm) compared to the non-pregnant, control animals (0.46 mm) while the NaF-supplied rats had a significantly lower expansion (0.22 mm) compared to the control animals. In the histological examination of the pressure sides of the PDL of the upper first molars, the mean value of osteoclasts per microns x 10(-3) increased non-significantly in the group of pregnant rats and decreased significantly among the NaF-supplied animals compared to the non-pregnant control rats. The present experiment in rats indicated that the velocity of orthodontic tooth movement is influenced by hormones as well as trace elements.

This study investigated the effect of a maxillary fixed lingual arch with anterior bite plane on adult patients with craniomandibular disorders (CMD) and increased overbite. The sample comprised 11 patients with an increased overbite (greater than 5 mm) and a normal or Class II molar relationship. The main CMD symptoms were daily tension headache in the region of anterior temporal muscles and/or pain or clicking in the temporomandibular joint. Previous treatment with stabilization splints, removal bite plates, or occlusal grinding had not given satisfactory results. When the maxillary lingual arch with anterior bite plane was fitted, molar separation was approximately 4 mm, and occlusal contact occurred only between the acrylic bite plane and the lower six anterior teeth. The permanent appliance could be removed only by the orthodontist. All patients reported relief of CMD symptoms 1 to 2 weeks after initiation of treatment. After a mean time of 3 months, a flatter curve of Spee, molar contact, and reduced overbite could be seen in all cases. The excessive overbite had decreased approximately 3.4 mm. Subsequent treatment involved orthodontic or prosthetic therapy to normalize and stabilize the sagittal and vertical dimensions. After an average posttreatment observation period of 2 years, all patients remained free of CMD pain.

The maximum bite force and position of the hyoid bone during natural and extended head posture were studied in 15 adults. All participants had normal occlusions and full dentitions. In addition, there were no signs or symptoms of craniomandibular disorders. The bite force was measured with a bite force sensor placed between the first molars. Six registrations of gradually increasing bite force up to a maximum were made with randomized natural and extended head postures. With one exception, the mean maximum bite force value was found to be higher for every subject with extended head posture compared to natural head posture. The sample mean was 271.6 Newton in natural head posture and 321.5 Newton with 20 degrees extension. With changed head posture, the cephalometric measurements pointed towards a changed position of the hyoid bone in relation to the mandible and pharyngeal airway. The cephalometric changes in the position of the hyoid bone could be due to a changed interplay between the elevator and depressor muscle groups. This was one factor which could have influenced the registered maximum bite force.

In a sample of 20 adults the associations between cervical lordosis, craniocervical inclination, position of the hyoid bone and cross-sectional dimensions of the pharyngeal airway were studied. Lateral skull radiographs were obtained in natural head posture and also at 20 degrees extension with the subjects' teeth in the intercuspal position. Cervical lordosis was measured from the second to the sixth vertebra and the position of the hyoid bone was calculated in horizontal and vertical directions. The dimensions of the free airway were measured between the dorsal tongue surface and the posterior pharyngeal wall and at the level of the second and fourth vertebra. A change from natural head posture to 20 degrees extension resulted in an increase in cervical lordosis and craniocervical inclination, changed position of the hyoid bone and increased cross-sectional dimensions of the pharyngeal airway. The changes in lordosis produced by changing natural head posture to 20 degrees extension showed significant correlations with the size of changed craniocervical inclination and free airway.

Journal Article The relationship between craniofacial morphology, head posture and spinal curvature in 8, 11 and 15-year-old children Get access Eva Hellsing, Eva Hellsing *Department of Orthodontics, Karolinska Institutet Dr Eva Hellsing Department of Orthodontics Karolinska Institutet Box 4064 S-14104 HUDDINGE Sweden Search for other works by this author on: Oxford Academic PubMed Google Scholar John McWilliam, John McWilliam *Department of Orthodontics, Karolinska Institutet Search for other works by this author on: Oxford Academic PubMed Google Scholar Thomas Reigo, Thomas Reigo **Department of Orthopaedics, Huddinge University HospitalSweden Search for other works by this author on: Oxford Academic PubMed Google Scholar Erik Spangfort Erik Spangfort **Department of Orthopaedics, Huddinge University HospitalSweden Search for other works by this author on: Oxford Academic PubMed Google Scholar European Journal of Orthodontics, Volume 9, Issue 1, 1987, Pages 254–264, https://doi.org/10.1093/ejo/9.1.254 Published: 01 January 1987

The changes in upper and lower resting lip pressures following extension and flexion of the head and at changed mode of breathing were studied in a sample of 15 adults with Class I molar relationship. The lip pressure was measured with bonded strain gauge transducers on the upper and lower central incisors. The transducers could be calibrated directly in the subject's mouth. The upper and lower lip pressures during natural head posture had a mean value of 3.91 g/cm2 and 8.58 g/cm,2 respectively. The mean values of the differences between pressures obtained during natural head posture and during 5 degrees, 10 degrees, and 20 degrees of extension showed a continuously, highly significant increase in pressure. During 5 degrees, 10 degrees, and 20 degrees of flexion, the upper lip pressure continuously decreased with highly significant values. Changes in the lower lip pressure during flexion were difficult to measure because of intense muscle activity. A significant decrease was shown for the difference in upper and lower lip pressures between nose breathing and mouth breathing, whereas there was a significant increase in pressure when the subject extended the head 5 degrees during mouth breathing.

In a sample of 125 boys and girls registered at 8,11 and 15 years of age the curvature of the cervical, thoracic and lumbar spine was studied. Cervical lordosis was calculated from the second, fourth and sixth vertebra on lateral skull radiographs. Thoracic kyphosis and lumbar lordosis were measured using a kyphometer. The results showed a decrease in the cervical lordosis and an increase in thoracic kyphosis and lumbar lordosis with increasing age in both sexes. In order to eliminate the systematic effects of sex and age a multiple stepwise regression analysis providing residuals corrected for the above mentioned variables was employed. When the entire sample was analysed again a highly significant correlation between thoracic and lumbar curvature was obtained. An almost significant, negative correlation was found between the inclination of the lower part of the cervical spine to a true vertical and the thoracic curvature. An almost significant correlation was also obtained between the inclination of the upper and lower part of the cervical spine to a true vertical, however no correlation was found between thoracic kyphosis and cervical lordosis. An almost significant negative correlation was furthermore found between the upper part of the cervical spine and the lumbar spine.

The aim of the present investigation was to induce oral respiration in human subjects and to study how this, in the short term (30 minutes), affected head posture, mandibular posture, and postural activity in the postcervical, supra- and infrahyoid, anterior temporal, masseter and sternocleidomastoid muscles. The study comprised of 30 adults. Head posture, mandibular posture and postural muscle activity were recorded: (a) during normal breathing when the subjects were standing in natural posture and with the mandible at rest, (b) immediately following obstruction of the nasal airways and then after 1, 3, 5, 10, 15, 20 and 30 minutes of obstruction, and (c) after nose breathing had been re-established. Obstruction of the nasal airways resulted in an extension of the head and a lowered mandibular posture. Postural activity decreased significantly in the postcervical and anterior temporal muscles and tended to increase in the suprahyoid muscles. In the infrahyoid, masseter and sternocleido-mastoid muscles no change in activity could be recorded. When nasal obstruction was removed and nose breathing was resumed, the readings of the variables studied did not differ significantly from the values recorded before the mouth breathing experiment. The results of the present study suggest that a change in the mode of breathing is able to influence head posture, mandibular posture and postural activity in neck and masticatory muscles.