Ischemia detection in women: the diagnostic value of exercise QRS duration changes

The purpose of this review article is to provide the dental practitioner with an understanding of the interrelationship between periodontics and orthodontics in adults. Specific areas reviewed are how periodontal tissue reacts to orthodontic forces, influence of tooth movement on the periodontium, effect of circumferential supracrestal fiberotomy in preventing orthodontic relapse, effect of orthodontic bands on the periodontium, specific microbiology associated with orthodontic bands, mucogingival considerations and time relationship between orthodontic and periodontal therapy. In addition, the relationship between orthodontics and implant restorations (e.g., using dental implants as orthodontic anchorage) will be discussed.     

Alterations in ultrastructural localization of growth-associated protein-43 (GAP-43) in periodontal Ruffini endings of rat molars during experimental tooth movement

It is known that orthodontic forces induce discomfort and/or abnormal sensation after application of an orthodontic appliance in patients, suggesting the adaptation of periodontal neural elements to environmental changes. However, no morphological data have been provided. The present study investigated, by immunoelectron microscopy, the localization of growth-associated protein-43 (GAP-43) in periodontal Ruffini endings in rat molars during experimental tooth movement. In the untreated control group, immunoelectron microscopy demonstrated that GAP-43-like immunoreactivity in the Ruffini endings was confined to the Schwann sheaths around the axon terminals, and was in neither the cell bodies of terminal Schwann cells nor the axon terminals themselves. Immunoelectron microscopic observation revealed alterations in the localization of GAP-43-like immunoreactivity in the periodontal Ruffini endings during experimental tooth movement. After 1 day of treatment, the cell bodies of the terminal Schwann cells associated with Ruffini endings appeared to contain immunoreaction products for GAP-43, and retained GAP-43-like immunoreactivity during tooth movement. From 5 to 7 days, a major population of the axoplasm of the periodontal Ruffini endings, which was immunonegative in control, filled the GAP-43 immunoreactions, showing a tendency to decrease in number later, and disappeared completely at 14 days. These findings suggest that orthodontic forces easily induce the remodeling of the mechanoreceptive Ruffini endings as well as the active tissue remodeling in a close relationship. Since the ultrastructural localization of GAP-43-like immunoreactivity was drastically changed in the Ruffini endings during tooth movement, GAP-43 functions as one of the key molecules in the remodeling of mechanoreceptive Ruffini endings during tooth movement.     

Dental innervation: functions and plasticity after peripheral injury

Oral tissues including the periodontal ligament, gingiva, and tooth pulp have a relatively dense sensory innervation and a rich vascular supply. Teeth and supporting tissues are susceptible to tissue injury and inflammation, partly due to lack of collateral blood and nerve supply and to their low compliance. This review focuses on dental nerve functions and adaptive changes in the trigeminal ganglion and tooth pulp after peripheral injuries. An overview of the peptidergic innervation of oral tissues is presented, followed by a discussion of plasticity in neuropeptide expression in trigeminal peripheral neurons after local insults to teeth and peripheral nerve injuries. The functional implications of these adaptive changes are considered, with special reference to nerve regeneration, inflammation, and hemodynamic regulation.     

Effect of transvascular fluid exchange on pressure-flow relationship in tumors: a proposed mechanism for tumor blood flow heterogeneity

Tumor blood flow (TBF) is characterized by spatial and temporal heterogeneities. Despite the crucial role of TBF in tumor growth, metastasis, and therapy, the mechanisms underlying these heterogeneities are not fully understood. Tumor vessels are, in general, more leaky than normal vessels and this may enhance the efficiency of fluid exchange between the vascular and the interstitial space. The coupling between transvascular fluid exchange and hemodynamics in tumors has not been explored previously. To investigate the role of transvascular fluid exchange on afferent and efferent blood flow, we modeled the tumor vasculature as an equivalent single vessel which is permeable and deformable and embedded in a fluid medium with uniform pressure. Simulations were carried out to examine the effects of vessel leakiness, vessel compliance, and interstitial fluid pressure on (a) pressure-flow relationship, (b) arterial-venous pressure relationship, and (c) pressure profile along the vessel. Experiments suggested by model simulations required an independent control of arterial and venous pressure and tumor blood flow. To this end, we perfused tissue-isolated tumors ex vivo and obtained data on perfusate flow rate vs arterial and venous pressures. The simulations predicted the following trends as a result of an enhanced fluid filtration across the vessel wall: (a) for a fixed arterial-venous pressure difference, efferent flow decreases with increasing venous pressure, (b) changes in venous pressure are not completely transmitted to the arterial side, and (c) the pressure profile along the vessel becomes less steep. The experimental results confirmed these trends and indicated that vascular and interstitial flow are coupled in isolated tumors. The implications of this coupling for the spatial and temporal heterogeneity in TBF are discussed.     

Assessing health in musculoskeletal disorders--the appropriateness of a German version of the Sickness Impact Profile

Intra-coronal bleaching of root-filled teeth has been associated with invasive cervical root resorption. It is considered that during bleaching hydrogen peroxide diffuses through the tooth structure into the cervical periodontium, resulting in periodontal tissue destruction and initiating a resorptive process. Hydrogen peroxide is capable of generating hydroxyl radical, an oxygen-derived free radical, in the presence of ferrous salts. Hydroxyl radicals are extremely reactive and have been shown to degrade components of connective tissue, particularly collagen and hyaluronic acid. The aim of the present study was to determine whether hydroxyl radicals are generated during the bleaching of root-filled teeth which have been discoloured by blood. Forty extracted human premolar teeth were root-filled with gutta-percha and AH26 sealer cement. Twenty of the teeth were experimentally discoloured by blood. All teeth were then thermo-catalytically bleached using 30% hydrogen peroxide while tooth roots were seated in a test solution of sodium salicylate. Hydroxyl radical generation was determined by the detection of reaction products of this radical with salicylate using high performance liquid chromatography with electrochemical detection (HPLC-ECD). The presence of hydroxyl radicals was detected in twenty-five of the teeth. There was a significant association between the production of hydroxyl radicals and the presence of tooth discolouration caused by blood components. Greatest yields of hydroxyl radicals occurred in teeth in which EDTA had been used to clean the pulp chamber prior to bleaching. It was concluded that hydroxyl radicals are generated during the thermo-catalytic bleaching of root-filled teeth. Generation of this toxic chemical species may be one mechanism underlying periodontal tissue destruction and root resorption after intra-coronal bleaching.     

Outcomes of the surgical exposure, bonding and eruption of 82 impacted maxillary canines

BACKGROUND: Advances in bonding techniques and materials allow for reliable bracket placement on ectopically positioned teeth. This prospective study evaluates the outcome of forced orthodontic eruption of impacted canine teeth in both palatal and labial positions. METHODS: Eighty-two impacted maxillary canines in 54 patients were included in the study and were observed for 18 to 30 months after exposure. Following exposure by means of a palatal flap or an apically repositioned buccal flap, an orthodontic traction hook, with a ligation chain attached, was bonded to each impacted tooth using a light cured orthodontic resin cement. A periodontal dressing was placed over the surgical site for a period of time. RESULTS: All teeth were successfully erupted. Complications consisted of: failure of initial bond, at the time of surgery, which required rebonding; premature debonding at the time of pack removal and; debonding of brackets during orthodontic eruption. There was no infection, eruption failure, ankylosis, resorption or periodontal defect (pocket greater than 3 mm) associated with any of the exposed teeth. Attached gingiva of less than 3 mm was seen in only two of the buccally positioned canines (9%). CONCLUSION: Forced orthodontic eruption of impacted maxillary canines with a well bonded orthodontic traction hook and ligation chain, used in conjunction with a palatal flap or an apically repositioned labial flap, results in predictable orthodontic eruption with few complications.     

Periapical replacement resorption of permanent, vital, endodontically treated incisors after orthodontic movement: report of two cases

Radiographic observations show that periapical replacement resorption (PARR) is a frequent and unpredictable sequella of orthodontic movement of permanent maxillary incisors. Only the apical root portion undergoes resorption, and it is subsequently replaced with normal bone. PARR also occurs without orthodontic tooth movement, but these resorptions differ as to type and location. PARR clearly occurs in teeth with vital pulps after orthodontic movement; however, our two cases and a review of 43 other cases indicate that endodontically treated incisors show a statistically significant lesser frequency and severity of apical resorption than untreated teeth. The role the vital pulp plays in this apical resorption is yet to be determined. A hypothetical explanation is offered suggesting that pulpal neuropeptides may be involved in PARR in both vital and endodontically treated incisors. The role calcium hydroxide plays in endodontically treated teeth is also considered.     

Localization of uncalcified cementum in adult rat molar roots and its relation to physiological tooth movement

The study was designed to elucidate the effect of physiological tooth movement on cellular cementum, using the upper molar roots of 10-week-old rats. Paraffin sections stained with haematoxylin and eosin displayed two types of cellular cementum, lightly and darkly staining. The lightly stained was present on the distal half of all molar roots except the mesial root of the first molar. The alveolar bone facing the lightly stained cementum showed resorption lacunae and multinucleated osteoclasts, while the opposite bone surface was lined with osteoblasts. In contact microradiographs of undemineralized ground sections, the X-ray density of the lightly stained cementum was similar to that of the periodontal ligament and pulp, while the X-ray density of the darkly stained cementum was similar to that of alveolar bone. Tetracycline labelling lines were seen at the interface between the two types of cellular cementum as well as on surfaces of bone and cementum located mesially to the root dentine. The results suggest that the mechanical stress of tooth movement differently affects the alveolar bone and cellular cementum; the bone is resorbed whereas the cementum resists resorption and its calcification is inhibited under the compressive force of tooth movement.     

Effective mechanisms of laser photocoagulation for neovascularization in diabetic retinopathy

The present study compared the effect of acetaminophen, ibuprofen and misoprostol on PGE2 synthesis and orthodontic tooth movement. Guinea pigs were randomly assigned into one of three test groups or a control group. Each group received study treatments every 12 hours as an orthodontic force was applied to the maxillary incisors. Direct linear measurements of tooth separation were recorded at days 2, 4, 6, 10, and 11, and inflammatory exudate from the periodontal ligament (PDL) space was extracted and quantitatively analyzed radioimmunologically for the presence of PGE2 at days 4 and 9. Comparing the concentration of PGE2 in sample extracts, a significant difference (P = 0.001) was found among drug groups. A highly significant difference was found between the mean tooth separation among the various drug groups (P < 0.001). At day 11 the misoprostol group exhibited 4.49 +/- 0.49 mm of separation; ibuprofen 2.56 +/- 0.11 mm, and the control and acetaminophen groups exhibited similar degrees of tooth separation: 3.31 +/- 0.07 mm and 3.31 +/- 0.08 mm, respectively. A highly significant difference occurred between the mean rates of tooth separation among the various drug groups after day 8 (P < 0.001). Results of this study suggest that acetaminophen is the analgesic of choice for the relief of minor discomfort associated with orthodontic treatment.     

A novel adrenaline derivative, AZ002, and its hypoglycemic action in yellow KK mice

A new device has been designed to provide anchorage for orthodontic tooth movement. It is a disk, textured and hydroxylapatite coated on one side, with an internal thread on the other side. It is placed on palatal bone and, after integration, can be connected to teeth for anchorage. This article reviews a dog study demonstrating unilateral tooth movement towards the "onplant" and a monkey study mimicking its use to anchor the molars for anterior retraction.     

Dose-response effects of adrenergic drugs on axial movements of the rat mandibular incisor and on arterial blood pressure

Axial tooth movements and arterial blood pressure were measured following the intravenous injection of 0, 0.01, 0.1, 1, or 10 micrograms/kg of adrenaline, noradrenaline or isoprenaline. Adrenaline caused a dose-dependent, rapid, extrusive tooth movement with a nearly simultaneous increase in blood pressure, followed by a marked intrusive tooth movement and a decrease in blood pressure. Noradrenaline caused a dose-dependent, rapid, extrusive tooth movement and an increase in blood pressure, but a subsequent intrusive tooth movement and decrease in blood pressure were not so marked. Isoprenaline caused a marked intrusive tooth movement and a decrease in blood pressure, without an extrusive tooth movement and increase in blood pressure. The time required to reach the maximum intrusive tooth movement was delayed after that to reach the maximum decrease in blood pressure. The recovery time of the intrusive tooth movement was much more delayed than that of blood pressure. These results suggest that the extrusive movement of the rat incisor was primarily related to the rise of arterial blood pressure due to stimulation of vascular alpha-receptors. It is also suggested that stimulation of beta-receptors would probably cause vasodilatation of arteries that would make the pressure in the small vessels in the microcirculation of the socket fall, so reducing the volume of blood and interstitial fluid in the socket followed by a marked and continuing intrusive tooth movement.     

Tooth splinting for severely mobile mandibular incisor teeth in a dog

Periodontal disease, in its advanced stages, causes tooth mobility. The tooth movement further damages the periodontium, accelerating the disease process leading to tooth loss. Dental splinting can provide coaptive stability to the teeth as an important component of a periodontal treatment plan. This report documents results four years following splinting of the mandibular incisor teeth in a 3 year old Miniature Schnauzer dog.     

Diet and risk of colon cancer in a large prospective study of older women: an analysis stratified on family history (Iowa, United States)

The aim of this study was to determine if diffusible angiogenic growth factors were released in human dental pulp during orthodontic tooth movement. These factors, if diffusible, could induce angiogenesis in other tissues, and may then be isolated and identified. The pulps from 14 premolar teeth treated with straight wire fixed orthodontic appliances for 2 weeks were compared with those of 14 untreated control premolar teeth from the same subjects. Following tooth extraction and sectioning, 1-mm horizontal sections of pulp tissue were embedded in collagen with 1-mm sections of rat aorta and co-cultured in growth media for up to 4 weeks. Sections of rat aorta alone were also cultured. Angiogenic changes in the form of microvessel growth were observed by light microscopy. Microvessel identification was confirmed by electron microscopy and by immunohistochemistry using staining for factor VIII-related antigen marker for endothelial cells. When compared at days 5, 10, and 14 of co-culture, the number of microvessels was significantly greater in the pulps from orthodontically moved teeth than in those from the control teeth. The number of rat aorta microvessels was also significantly greater when co-cultured with pulp from orthodontically moved teeth than with pulp from control teeth and when compared with control cultures of rat aorta alone. There were no significant differences in microvessel numbers between the rat aorta co-cultured with pulp from control teeth and control cultures of rat aorta alone. These results indicate an increase in angiogenic growth factors in the pulp of orthodontically moved teeth, and the enhanced response of the rat aorta when co-cultured with this pulp shows that these factors appear to be diffusible.     

Testosterone stimulates angiogenesis and vascular regrowth in the ventral prostate in castrated adult rats

The castration-induced regression and testosterone stimulated regrowth of the vasculature in the rat ventral prostate lobe were studied using stereological techniques. Seven days after castration, the endothelial cell proliferation rate (bromodeoxyuridine labeling index); the total weights of blood vessel walls, blood vessel lumina, endothelial cells, glandular epithelial cells; and total organ weight were all decreased. Within 2 days after sc treatment with testosterone, the total weights of blood vessel walls, endothelial cells, and vascular lumina, as well as the endothelial cell proliferation rate, were all normalized. In contrast to the rapid response of the vasculature, the total weight of glandular epithelium and total organ weight were not normalized during the 4 days of testosterone treatment. Growth of the vasculature apparently precedes growth of the glandular epithelium. The testosterone- dependent factors stimulating the vasculature are unknown, but factors derived from epithelial cells, mast cells (which accumulate in the prostate during the first day of testosterone treatment), and tissue macrophages could all be involved. Castration-induced regression and testosterone-stimulated regrowth of the prostatic vasculature can be used as an experimental model to study factors regulating angiogenesis and organ growth in the prostate.     

The regenerative potential of oxytalan fibers. An experimental study in the monkey

Although a number of studies have described the oxytalan fibers as being a natural component of the periodontal ligament, little information exists about the regenerative potential of these connective tissue fibers. The aim of the present study was to examine whether oxytalan fibers have the capacity to reform after regenerative periodontal therapy. Intrabony defects were produced surgically at the mesial aspects of teeth 37, 35, 45, 47 and at the distal aspects of teeth 11, 21, 31, 41 in one monkey (Macaca fascicularis). After 3 months, the defects were exposed using a full-thickness flap procedure. The root surfaces were debrided and subsequently PDGF-growth factors were placed in the defects. 4 of the 8 sites were covered with a bioresorbable membrane before closure of the wound. Post-surgically, antibiotics were given systemically for 1 week, and tooth cleaning was carried out 1x a week during the entire experimental period. After 5 months, the animal was sacrificed and the oral tissues were fixed by perfusion with 10% buffered formalin. Specimens containing the defects and surrounding tissues were dissected free and histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin or with the oxone-aldehyde-fuchsin-Halmi staining method and subsequently examined in the light and in the electron microscope. The results revealed that new oxytalan fibers oriented mainly in an apico-occlusal direction had developed in the regenerated periodontal ligament. Many of the newly-formed fibers were inserted into the new cementum, thus suggesting a strong relationship between this tissue and the oxytalan fibers. It is concluded that the regenerated periodontal ligament connective tissue formed after surgery contains oxytalan fibers similar to those present in the original tissue. These results demonstrate that oxytalan fibers develop de novo in the newly-formed periodontal ligament.     

Interdisciplinary concepts in treating adult patients

Pre-prosthetics, as a part of orthodontic treatment in adults has gained increasing importance during recent years. Through coordinated orthodontic, prosthetic and periodontal treatment plans, patients with partial dentition can be offered further treatment possibilities. Such planning would allow for fixed prosthetic treatment possibilities and the survival of critical teeth. They would provide for better aesthetics and avoid functional disturbances. The aim of the present study was to present reports of patients treated by coordinated work at the Dental School of Hamburg University. In patients with partial dentition, premolars were uprighted and distally moved and molars were extruded to be used as abutments for fixed prosthetic reconstructions. Following trauma, the position of the remaining anterior teeth was improved to provide for optimal aesthetics after prosthetic treatment. Extraction of a subalveolarly fractured tooth is avoided through root extrusion and post-core reconstruction. The results demonstrate the advantages of pre-prosthetic treatment as regards stability, aesthetics and function. With the help of pre-prosthetic orthodontic treatment, complicated treatment situations could be handled more successfully than would have been the case without such treatment.     

Indications for compensatory extractions in orthodontic space closure in the frontal segments

This follow-up study presents patients who underwent orthodontic space closure in the maxilla after traumatic loss of frontal teeth or aplasia of a lateral incisor. Comparison covers findings obtained from casts and cephalograms in 24 patients with or without compensatory extraction. The findings indicate that acceptable results regarding axial tooth positioning and profile can be obtained without compensatory extraction. Prerequisites are distal occlusion of the first molars by one premolar width and continuous monitoring for regular overbite and uncrowded lower incisors. If orthodontic space closure can be achieved only by compensatory extraction, the indication for this space closure procedure calls for even more critical judgement.     

Primary surgery of skeletal dysgnathias

Three case studies from the patient population of the University Hospital of Aachen (RWTH) are used to describe indications for primary surgical intervention in skeletal dysgnathia. Such preconditions may apply in the case of mandibulo-alveolar protrusion, anomalies where there is little or no option to fixing orthodontic appliances (enamel hypoplasia or shortened crowns), severe transversal discrepancies and skeletal dysgnathia with pronounced malpositioning in the alveolar process and the teeth. The advantages are improved compliance (through the patient experiencing success at the outset of treatment) and limitation of postoperative orthodontic treatment to occlusive fine adjustments of the occlusion, resulting in an appreciable reduction in both the degree and duration of tooth movement and tissue damage.     

Shear stress in cerebral arteries supplying arteriovenous malformations

Arteries supplying cerebral arteriovenous malformations (AVMs) are known to dilate with time. These changes are reversible, and the feeders have been shown to slowly decrease in calibre after removal of the AMV. There is evidence that arteries alter their internal diameters in response to sustained changes of blood flow so that shear stress is kept constant. This implies that blood flow-induced shear stress might be the driving force for remodelling of the cerebral vascular network in the presence of an AVM, and for reversion of these changes after radical operation. The objective of this study is to examine the hypothesis that the shear stress in cerebral arteries supplying AMVs is of the same magnitude as in arteries supplying normal brain tissue in spite of larger blood flow rate. Fifteen patients with supratentorial cerebral AVMs admitted for endovascular treatment were examined with transcranial Doppler ultrasound in the distal Willisian vessels. Vessel calibres were measured in angiograms with magnification correction. Shear stress was estimated assuming a constant value for blood viscosity. Corresponding arteries in the cerebral hemisphere with AVM and in the contralateral one were compared in pairs. Thirty-four pairs of homonymous arteries were studied. The arteries on the AVM side presented larger calibres, higher axial blood flow velocities, lower pulsatility index and larger blood flow rates than the contralateral side. There was a clear positive correlation between blood flow velocities and vessel calibres. The estimates of shear stress did not differ significantly in corresponding arteries of both hemispheres (p = 0.18). The results indicate a precise adjustment of cerebral arterial calibre and blood flow-induced shear stress that presumably induces the progressive dilation of AVM feeders, and the slow regression of the vessel calibres to average dimensions after removal of the lesion. Each vessel seems to remodel itself in response to long-term changes in blood flow rate so that the vessel calibre is reshaped to maintain a constant level of wall shear stress.     

Immunohistochemical localization of endothelin-1 in placenta and fetal membranes in term and preterm human pregnancy

A case is reported in which an intruded incisor was initially treated by an endodontic dressing with calcium hydroxide and then extruded using a removable orthodontic appliance. A follow-up examination seven years after completion of endodontic therapy and bleaching showed a favourable response. A review of the relevant literature indicates that intrusion occurs in five to twelve per cent of luxation cases. In this type of injury maximum damage occurs to the pulp and all supporting structures because the tooth is driven into the alveolar process. Complications which have been reported include: pulp necrosis, apical radiolucencies, partial or total pulp calcification, root resorption (surface, inflammatory or replacement), marginal periodontal bone breakdown, and arrested or disturbed root development. The prognosis for pulp survival after intrusion is much more favourable for teeth with incomplete root formation than for teeth with complete root formation. Treatment options available to bring an intruded tooth into alignment are: to await spontaneous re-eruption which may occur if root formation is incomplete, uncovering of the intruded crown, orthodontic extrusion which is allied with gentle luxation if the tooth does not move, and immediate surgical repositioning.