Intrusion Movement Research Articles

Clinical trial on intrusion of overerupted maxillary molars with microscrew

To investigate the imtrusion of overerupted molars with microscrews as anchorage. Thirteen adult patients were treated with microscrew anchorage and fixed appliances. Twenty-three overerupted posterior maxillary teeth were intruded. The intrusive movement was investigated on cephalometric radiographs. The molars were intruded and the occlusal plane was corrected successfully in all patients. The treatment period of intrusion was from 5 to 18 months (mean 10.4 months). Significant true intrusion of overerupted maxillary molars, ranged from 0.45 mm to 7.00 mm [mean (2.86 +/- 1.80) mm], was achieved (P < 0.001). The apical root resorption was not clinically significant and the bone level was unchanged. The microscrew anchorage and fixed appliances were applicable and efficacious for intrusion of overerupted maxillary molars.

Tourette's and tics

Summary Tourette syndrome is now recognised as affecting 1% of school-age children and covers a wide range of severity ranging from a diagnostic combination of mild and simple motor and vocal tics to a severely intrusive movement disorder with associated co-morbidities, the most common of which are obsessive–compulsive disorder and attention deficit hyperactivity disorder. It is a familial condition, but the genetic mechanism has yet to be identified. The neurobiology is also still not understood, and the major research themes are neuroimaging and neuroimmunology, with a controversial hypothesis relating to basal ganglion antibodies secondary to group A streptococcal infection. Management is with psychological techniques, neuroleptic drugs, clonidine, stimulants and selective serotonin uptake inhibitors. Most recently, deep brain stimulation to the basal ganglia or thalami has been applied in adults, but substantial data in this area are awaited.

Uso da barra transpalatina no controle da rotação da mandíbula

Na maioria dos pacientes na fase de dentição mista, com um certo grau de mordida aberta acompanhado de deglutição atípica ou algum mau hábito, observamos que o processo dentoalveolar superior está aumentado no sentido vertical. O uso da BTP nos molares superiores nestes casos, com a alça central colocada numa altura suficiente para, durante a deglutição, exercer alguma pressão sobre o dorso da língua, tem se mostrado de grande valia, notando-se como resultado uma restrição do crescimento do processo dentoalveolar no sentido vertical. Este resultado evita o deslocamento dentário no sentido vertical podendo até provocar movimento efetivo de intrusão dos molares com conseqüente mudança do eixo de crescimento com rotação da mandíbula no sentido anti-horário.

Maxillary Molar Intrusion with Fixed Orthodontic Appliances and Bony Anchorage-A Preliminary Report with a 3-D Analysis

Overeruption of upper molars due to loss of antagonists may cause problems such as periodontal defects and occlusal interference. Molar intrusion requires anchorage support from intraoral multi-unit teeth, extraoral headgear wear or newly adopted miniscrew and miniplate as bony anchorages. The aim of this study was to investigate the amount of individual tooth movement within the same arch in cases of overerupted maxillary molars receiving partial or full-mouth fixed orthodontic treatment with miniscrews and miniplates used as anchorage. The surface topology of the cusp tips and incisal edges of the pretreatment and post-intrusion dental casts were recorded using a desktop mechanical 3D digitizer. The 3D data of the pretreatment and the post-intrusion dental casts were traced, processed, synthesized, and analyzed to distinguish the direction and magnitude & individual tooth movements. Results of this study demonstrated that the average intrusive movement of the upper first molars was 3 to 4mm with a maximum value of over 8mm. For the adjacent upper second molar and the upper first and second premolars, the amount of intrusion was around 2mm. A small difference between the buccal and palatal cusps was noted in the quantitative analysis of intrusive tooth movement. In conclusion, a significant amount of intrusion for overerupted maxillary molars can be obtained in a well-controlled manner using fixed appliances with mini-implants such as titanium miniscrews and miniplates serving as bony anchorage.

Reconstruction of the maxillary midline papilla following a combined orthodontic-periodontic treatment in adult periodontal patients.

The aim of the present study was to evaluate the role of a combined orthodontic-periodontic treatment in determining the reconstruction of midline papilla lost following periodontitis. Twenty-eight patients, with infrabony defect and extrusion of one maxillary central incisor, were treated. At baseline, all patients presented opening of the interdental diastema and loss of the papilla. At 7-10 days after open-flap surgery, the intrusive movement started. For each patient, probing pocket depth (PPD), clinical attachment level (CAL) and papilla presence index (PI) were assessed at baseline, end of treatment and after 1 year. PI was also evaluated independently in patients with narrow or wide periodontal biotype (NPB-WPB). All parameters showed statistical improvement between the initial and final measurements, and showed no changes at follow-up time. The mean residual PPD was 2.50 mm, with a decrease of 4.29 mm, while the mean CAL gain was 5.93 mm. Twenty-three out of 28 patients improved the PI score at the end of therapy. No statistical difference was recorded in PI values between groups NPB and WPB. The presented clinical protocol resulted in the improvement of all parameters examined. At the end of orthodontic treatment, a predictable reconstruction of the interdental papilla was reported, both in patients with thin or wide gingiva.

Initial stress produced in the periodontal membrane by orthodontic loads in the presence of varying loss of alveolar bone: a three-dimensional finite element analysis.

The aim of this study was to investigate the stress components (S1 and S3) that appear in the periodontal membrane (PDM), when subjected to transverse and vertical loads equal to 1 N. A further aim was to quantify the alteration in stress that occurs as alveolar bone is reduced in height by 1, 2.5, 5, 6.5, and 8 mm, respectively. Six three-dimensional (3D) finite element models (FEM) of a human maxillary central incisor were designed. The models were of the same configuration except for the alveolar bone height. Special attention was paid to changes of the stress components produced at the cervical, apical, and sub-apical levels. In the absence of alveolar bone loss, a tipping force of 1 N produced stresses, which reached 0.072 N/mm2 at the cervical margin, up to 0.0395 N/mm2 at the apex and up to 0.026 N/mm2 sub-apically. In the presence of 8 mm of alveolar bone loss, the findings were -0.288, 0.472, and 0.722 N/mm2, respectively. Without bone loss, an intruding force of the same magnitude produced stresses of -0.0043, -0.0263, and 0.115 N/mm2, respectively, for the same areas and sampling points. In the presence of 8 mm of alveolar bone loss the findings were -0.019, -0.043, and 0.185 N/mm2 for intrusive movement. The results showed that alveolar bone loss caused increased stress production under the same load compared with healthy bone support (without alveolar bone resorption). Tipping movements resulted in an increased level of stress at the cervical margin of the PDM in all sampling points and at all stages of alveolar bone loss. These increased stress components were found to be at the sub-apical and apical levels for intrusive movement.

Intrusion of migrated incisors with infrabony defects in adult periodontal patients.

This report describes the orthodontic treatment of 10 adult patients who had severe periodontal disease, with migration and radiological evidence of an infrabony defect on a maxillary central incisor. Orthodontic tooth movement, using light and continuous forces, was initiated 7 to 10 days after periodontal surgical therapy. Mean orthodontic treatment time was 10 months. Before surgery and at the end of orthodontic treatment, the following parameters were registered clinically and with standardized intraoral radiographs: probing depth, clinical crown length, marginal bone level, bone defect radiological dimension, and root length. Comparison of pre- and posttreatment values showed a statistically significant improvement for all parameters without a remarkable decrease of root length. The mean residual probing depth was 2.80 mm, and the mean intrusion of the incisors was 2.05 mm. Moreover, radiographs showed a reduction of the infrabony defects. These results show the efficacy of a combined orthodontic-periodontal approach. Intrusive movement, after proper periodontal surgical therapy, can positively modify both the alveolar bone and the soft periodontal tissues.

Axial movements of rat mandibular incisors measured under artificial respiration with halothane anaesthesia

The axial movements of rat incisors were recorded continuously for over 20 h. The rats were anaesthetized with halothane delivered by intratracheal intubation using an artificial respirator. A haemostatic clamp was used to immobilize the jaw and the displacement detector exhibited high resolution, good linearity and low drift. The previously impeded and unimpeded eruption rates (the average extrusive movements) were 406 and 548 μm/24 h, respectively. The previously unimpeded rate was lower than the normal unimpeded rates obtained by other investigators. It appears that the eruptive movement of the previously unimpeded incisor was inhibited by halothane anaesthesia. Circadian rhythm was not observed in the eruption rates of previously impeded or unimpeded incisors. Following the i.p. injection of a lethal dose of pentobarbital sodium, the incisors retracted. The average intrusive movement was significantly greater in the previously impeded group (29 μm) than in the previously unimpeded group (12 μm) at 30 min after the lethal injection. It is assumed that the elimination of the pushing force at death may cause the stretched periodontal fibres to recoil, thereby pulling the tooth in an intrusive direction. It is also likely that the mechanical strength of the ligament is reduced in the previously unimpeded group by repeated shortening of the incisors; therefore the force needed to retract previously unimpeded incisors may be less than that needed to retract previously impeded incisors.

Impaired prepulse inhibition of acoustic and tactile startle response in patients with Huntington's disease.

The corpus striatum serves a critical function in inhibiting involuntary, intrusive movements. Striatal degeneration in Huntington's disease results in a loss of motor inhibition, manifested by abnormal involuntary choreiform movements. Sensorimotor inhibition, or "gating", can be measured in humans using the startle reflex: the startle reflex is normally inhibited when the startling stimulus is preceded 30-500 ms earlier by a weak prepulse. In the present study, prepulse inhibition (PPI) was measured in patients with Huntington's disease to quantify and characterise sensorimotor gating. Compared with age matched controls, patients with Huntington's disease exhibit less PPI. Startle gating deficits are evident in patients with Huntington's disease when startle is elicited by either acoustic or tactile stimuli. Even with stimuli that elicit maximal PPI in normal subjects, patients with Huntington's disease exhibit little or no PPI, and their pattern of startle gating does not show the normal modulatory effects usually elicited by changing the prepulse interval or intensity. Startle amplitude and habituation and latency facilitation are largely intact in these patients, although reflex latency is significantly slowed. In patients with Huntington's disease, startle reflex slowing correlates with cognitive impairment measured by the dementia rating scale, and with the performance disruptive effects of interference measured by the Stroop test. These findings document a profound disruption of sensorimotor gating in patients with Huntington's disease and are consistent with preclinical findings that identify the striatum and striatopallidal GABAergic efferent circuitry as critical substrates for sensorimotor gating of the startle reflex.

The finite element analysis of stress in the periodontal ligament when subject to vertical orthodontic forces.

In the past, vertical intrusive movement of teeth has been considered difficult and most routine clinical vertical movement of teeth has been confined to extrusion. It has been suggested that attempts at intrusion may result in an increased incidence of root resorption and also in occasional devitalization. The displacement and resulting stress fields associated with such treatment can be successfully studied using the finite element method. In the case being considered initial movements are known to be small; therefore, the assumption in the study that the material behaves linear-elastically is considered to be reasonable. This study of vertical tooth movement demonstrated that the maximum cervical margin stress in the periodontal ligament was 0.0046 N/mm2, whilst the highest apical stress was 0.00205 N/mm2 when intrusive and extrusive forces of 1 Newton were applied to the buccal surface of the crown of a tooth model. These stresses were evaluated in the light of previous studies and found to be within the suggested clinical optimum level. However, the periodontal stress distribution following orthodontic loading within this three-dimensional finite element model was found to be highly complex.

Acute changes in intra-alveolar tooth position and local clearance of125I from the periodontal ligament

Changes in intra-alveolar tooth position and local 125I clearance from the periodontal ligament (PDL) were monitored simultaneously in cats. Axial tooth movements, reflecting periodontal ligament volume changes, were measured with an ultrasonic transit time technique. Local blood flow changes in the PDL were studied indirectly by measuring the local clearance of 125I-. Stimulation of the cervical sympathetic trunk caused an intrusive movement of the tooth with a concomitant reduction of the 125I- clearance. Infusion of noradrenaline induced a similar response. Stimulation of the inferior alveolar nerve during systemic treatment with phentolamine caused an extrusive movement of the tooth with a concomitant increase in the clearance of the tracer from the PDL. Intra-arterial infusion of the vasodilator substance P mimicked that response. Fixation of the tooth to the jaw bone, thus preventing an intrusive movement, did not change the reductions in clearance seen on sympathetic stimulation, indicating that this blood flow reduction was not dependent on tooth movement. A qualitative relation between PDL blood flow (as measured by local 125I clearance) and PDL volume (as measured by tooth position) is shown. The two variables measured are suggested to reflect two aspects of blood flow in the PDL.

Educating children and adults on coping with Tourette syndrome.

cologic treatment but not to traditional psychotherapy (3). However, supportive counseling, behavior therapy, and special education can be helpful in managing the stress and psychoeducational sequela associated with this syndrome. The authors have evaluated or provided workshops or counseling to over 130 children and ad.ults with Tourette syndrome. In managing these children, three topic areas are relevant for these children and their families, and for psychologists, counselors. and educators who work with them. The first area concerns information about Tourette syndrome and the diverse symptomotology observed in affected children, including the causes of the syndrome and circumstances which affect the severity of the symptoms, differentiation of one's own behavior from the symptoms of thc syndrome, differentiation of tics and habits, symptomatic changes with age, and treatment alternatives and their relative effectiveness. The second area pertains to the disorder's effects on the individual's relationships and work experiences. These children and their families need to understand how symptoms affect peer reactions, discipline. dating, and problems with schoolwork, such as, writing, concentration and obsessive thinking. Insight and emotional support for psychological reactions to symptoms of the disorder comprise the final area. The intrusive movements and verbalizations can lead. to depression, feelings of loss of concrol and of being different from others, anxiety in groups, concerns about medication, and frustrations about having to explain unusual behavior.

Extrusive mobility of teeth in adult monkeys ( Macaca fascicularis)

Extrusive mobility of 15 teeth in 4 adult macaques was compared with intrusive mobility of the same teeth. The character of the load displacement and recovery records was similar; the qualitative response to repeated 4 N thrusts, 4 N loads sustained for 30 s and residual loading with 50, 30 and 10 mN, was the same whether the force was applied in an intrusive or extrusive direction. Fast and slow loading rates (100 and I Ns −1) both caused greater intrusion than extrusion at 4 N ( p < 0.001). Thus the mechanisms of tooth support are similar for intrusive and extrusive force. The oblique orientation of the principal fibres of the ligament may allow a greater degree of initial intrusive movement, before tension is generated, than occurs in axially-aligned fibres under extrusive force. Extrusive loading may be a convenient method for studying tension in the periodontal ligament.

Effects of sympathetic nerve activity on changes in the position of the rabbit incisor tooth evoked by acute alterations in arterial blood pressure

The influence of the sympathetic innervation of periodontal blood vessels on the responses of the upper incisor tooth to sudden changes in mean arterial pressure was studied in 15 anaesthetized rabbits. Changes in axial position of the tooth were measured by ultrasonic transit time technique. With intact sympathetic nerves, the tooth showed small, if any, intrusive movements in response to 6–42 mm Hg reductions in arterial pressure evoked by stimulation of the aortic baroreceptor nerve. When exposed to similar periods of hypovolaemic hypotension, the intrusions were, on an average, 1 μm larger ( p < 0.01). After bilateral sectioning of the cervical sympathetic nerves, tooth intrusions in response to both types of pressure reduction became more marked, as did the extrusive movements evoked by abrupt increases in aortic pressure (produced by inflation of intra-aortic balloon). After sympathectomy, a 19 ± 6 mm Hg rise in pressure caused extrusions of 6 ± 3 μm, or 2 μm more than before the sympathectomy ( p < 0.01). The results suggest that the activity in sympathetic nerves to periodontal blood vessels may be inhibited by central nervous mechanisms and that the sympathetic innervation of the periodontal vasculature serves to minimize changes in tooth position brought on by sudden alterations in arterial pressure.

The influence of vascular beta-adrenoceptors on the position and mobility of the rabbit incisor tooth.

The influence of vascular beta-adrenoceptors on the tooth-supporting functions of the periodontal ligament were studied in 30 anesthetized rabbits. Propranolol and the beta 2-adrenoceptor antagonists ICI 118,551 and H 35/25 induced a marked extrusion of the incisor, probably due to reduced vasodilator tone in periodontal postcapillary blood vessels. Isoprenaline reversed the movement. beta 1- and beta 2-receptor antagonists decreased the intrusive responses to sympathetic nerve stimulation in teeth close to control position, but had no effect on responses in fully extruded teeth. Intrusive mobility, as tested by intermittent loading with 5-10 g, remained unaffected by beta-adrenoceptor blockade. The results suggest that vascular beta 2-adrenoceptors are important in the regulation of tooth position by their control of periodontal postcapillary resistance. Prejunctional beta-receptors enhancing the vasoconstrictor--and intrusive--responses to sympathetic nerve stimulation are probably a mixture of beta 1- and beta 2-receptors. It would seem that the periodontal vasculature is important for the position of the rabbit tooth but, due to rapid adaptive mechanisms of the tooth-supporting tissues, the vasculature contributes little to the resistance against load-induced intrusive movements of the tooth.

Experimental intrusion of rat incisors with continuous loads of varying magnitude

The present investigation deals with the relationship between continuous intrusive loads and the rate of intrusion of rat incisors. A method for the application of constant, defined loads by means of a closed coil spring is described. In seventeen rats the left mandibular incisor was shortened to prevent occlusion. The animals were exposed to direct light, medium, and heavy intrusive loads for a period of 12 days. Light loads (1.5 to 8.0 Gm./cm. 2) did not cause active intrusion of the teeth. Medium loads (12.0 to 18.5 Gm./cm. 2) initially elicited marked intrusion, followed by a short rest period after which the intrusive movement progressed steadily at a daily rate of about 25 μm. Heavy loads (30.5 to 32.0 Gm./cm. 2) brought about active intrusion, which commenced only after 8 days of force application. The medium loads, having a magnitude in the range of rat systolic blood pressure, proved to be optimal for the intrusive movement.

The effects of section and stimulation of the cervical sympathetic trunk on eruption of the rabbit mandibular incisor

The immediate and short-term effects of section and stimulation of the cervical sympathetic trunk on the eruption of the ipsilateral mandibular incisor in rabbits were investigated using a displacement transducer which enables continuous monitoring of tooth movement. Compared with mean rates of eruption determined for a control group, 30 min following sympathectomy in 12 rabbits, the rates were significantly increased for approx. 1 h. The effects of stimulation for 3 min of the peripheral cut end of the cervical sympathetic trunk were assessed using a further group of 11 rabbits which showed eruptive movements. The pulse duration for every stimulation was 1 ms. In 8 rabbits, intrusive movements resulted where the stimulus strength and frequency exceeded 2 V and 3 Hz. For 3 rabbits, eruption was uninterrupted. The results were consistent with a haemodynamic hypothesis of eruption.

The effects of some vaso-active drugs on the eruption of the rabbit mandibular incisor

Because the forces of tooth eruption may be generated by vascular/tissue hydrostatic pressures, the effects on the rabbit incisor of hypotensive agents (hexomethonium, guanethidine and hydrallazine) and of noradrenaline and acetylcholine were investigated using a technique for continuously monitoring tooth movements. Following the intravenous administration of hexomethonium (10 mg/kg), guanethidine (3 mg/kg) or hydrallazine (1 mg/kg), the rates of eruption-like movements increased for approximately 2 h and then the hexomethonium ones returned to control values, the other two showed a similar trend to return. In some rabbits treated with guanethidine or hydrallazine, however, the initial response was an intrusion of the incisor. Injection of noradrenaline (0.003 mg/kg) was associated with intrusive movements initially. Acetylcholine (0.01 mg/kg) was associated with a rapid extrusive movement initially where there was little or no prior eruption. Where eruption was present, reactions were difficult to show. These initial effects of noradrenaline and acetylcholine were occasionally followed by eruption-like movements, the rates of which were much higher than expected. Changes in periodontal tissue hydrostatic pressure could be responsible for all the drug effects.

中部地方上松町西方の小川花こうせん緑岩体について Ｉ

Ogawa Granodiorite Mass, one of the late Cretaceous granite, can be classified into the following three rock facies: (a) medium-grained facies, (b) porphyritic facies, (c) finegrained facies. According to the mode of occurrence and microscopic observations, these three rock facies are considered to be formed in situ through the crystallization differentiation process, after the intrusive movement of Ogawa Mass. Zoning patterns of plagioclases consisting the above-stated rock facies are investigated, and the following results were obtained. In the case of Ogawa Granodiorite Mass, zoning structures of plagioclases are correlative among the most crystals of the three rock facies. The type of zoning pattern of plagioclases of Ogawa Mass is distinguishable as follows from inner part to the outward. -inner patchy zone-inner oscillatory zone-outer patchy zone-outer oscillatory zone-rim. From the comparison of zoning structures of plagioclases in above three rock facies, the present author concluded that the outer oscillatory zone might have been formed after/or the same time of crystallization differentiation.

On the structure and intrusive movement of the Yoshimagawa granitic pluton in the central Abukuma Mountains

On the structure and intrusive movement of the Yoshimagawa granitic pluton in the central Abukuma Mountains