A T.E.M. stereological analysis of blood vessels and nerves in marmoset periodontal ligament following endodontics and magnetic incisor extrusion

The efficacy of different pre- and post-operative analgesics in the management of pain after orthodontic separator placement: A randomized clinical trial

Introduction:

Pain-free treatment to the patients is considered as an important treatment objective for orthodontic health care providers. However, many orthodontists underestimate the degree of pain experienced by the patients. Hence, this study was conducted as a randomized, double-blinded clinical trial with the following objectives.

Objective:

To study the pain characteristics after separator placement; to compare the efficacy of various commonly used analgesics in pain management and to determine the efficacy of pre- and post-operative analgesics in pain management.

Subjects and Methods:

Data were collected from 154 patients (77 males and 77 females, age group of 14-21 years, with mean age of 18.8 years) who reported to Department of Orthodontics. Patients were randomly divided in to four groups. Group 1: Paracetamol 650 mg, Group 2: Ibuprofen 400 mg, Group 3: Aspirin 300 mg, Group 4: Placebo and the study were conducted as a randomized, double-blinded clinical trial. The patients were instructed to take two tablets, one tablet 1 h before separator placement, and the other one after 6 h. The pain evaluations were made by the patients, when teeth not touching (TNT), biting back teeth together, chewing food (CF) using a 100-mm visual analogue scale for 7 days after separator placement. Patients were advised to record the severity of pain.

Results:

Group 3 (Aspirin 300 mg) showed lowest pain values, followed by Group 2 (ibuprofen 400 mg), and Group 1 (paracetamol 650 mg). All NSAID's achieved good pain control compared to Group 4 (placebo), where the intensity pain was maximum.

Conclusion:

Pre- and post-operative analgesics were found to be more effective in controlling orthodontic pain, after separator placement at all-time intervals.

Effect of duration of force application on blood vessels in young and adult rats

INTRODUCTION

Age effects on orthodontically induced periodontal vascular reactions have not been studied. The aim of the present study was to test the hypothesis that prolonged tooth movement induces age-related increases in periodontal vascularity.

METHODS

A standardized orthodontic appliance was placed in 2 groups of 30 rats aged 6 weeks and 9 to 12 months. At 1, 2, 4, 8, and 12 weeks, animals were killed. Blood vessels (BV) were identified based on their morphology and by immunohistochemical staining for alpha-smooth muscle actin. At each study region, surface areas (SA) of the periodontal ligament space and each BV were measured; BV mean SA, BV relative SA (the summed BV SA as a percentage of the periodontal ligament SA), and BV numbers were calculated.

RESULTS

Pressure and tension regions showed similar vascular changes. Young rats had lower BV relative SA and BV mean SA in the early phase of force application (< 4 weeks); this increased in the late phase, reaching the same level as adult rats. In the late phase (4-12 weeks), young rats had increases of both small- and large-sized BV that did not affect the BV mean SA; adult rats had an increase of small-sized BV only; this resulted in decreased BV mean SA.

CONCLUSIONS

The hypothesis was confirmed that prolonged tooth movement increases periodontal vascularity, which is age related. These results suggest that clinicians should consider age-related difference in tissue reactions during orthodontic tooth movement.

Histomorphometric study of the periodontal vasculature during and after experimental tipping of the rat incisor

The periodontal vasculature encircling the entire length of the rat lower incisor was studied at the time of tipping movement and 3 months later. In 12 rats (212+/-4 g b.w.), loads (0.19+/-0.016 N) were applied to the lower left incisor in a linguointrusive direction. After 2 weeks of loading, six experimental animals were killed with the loading springs in place. The springs were removed in the six remaining rats, which were killed 12 weeks later. Six additional rats with intact teeth served as control. All incisors were fixed, demineralized, embedded in glycol methacrylate and cross-sectioned perpendicular to the long axis of the tooth. The distance of each section (2 microm) from the apex was calculated. A computerized image-analysis program was used to measure the width and area of the labial and lingual periodontal ligament to establish whether the measured segments corresponded to the compressed or expanded zones. In each cross-section, the various types of blood vessels were counted and the cross-sectional area of all venous vessels was measured. The results showed that after 2 weeks of loading (1) the general trend of vascular changes was similar under pressure and tension; (2) the large-diameter vessels were unaffected by loading; (3) the mean number of terminal arterioles had decreased significantly, while the number of capillaries and postcapillary venules had increased significantly in the apical tooth part; (4) the venous blood vessel area had decreased significantly in the apical tooth part; (5) the intensity of the vascular reaction was dependent on the degree of tissue distortion; and (6) after 12 weeks' recovery the vascular changes were still present, demonstrating a rebound effect. The findings suggest that microvascular alterations following tooth loading are not directly related to the spatial effect of loading itself and are of a much longer duration than expected.

Endodontic-orthodontic relationships: a review of integrated treatment planning challenges

Literature review There is a paucity of information on the concise relationship between endodontics and orthodontics during treatment planning decisions. This relationship ranges from effects on the pulp from orthodontic treatment and the potential for resorption during tooth movement, to the clinical management of teeth requiring integrated endodontic and orthodontic treatment. This paper reviews the literature based on the definition of endodontics and the scope of endodontic practice as they relate to common orthodontic-endodontic treatment planning challenges. Literature data bases were accessed with a focus on orthodontic tooth movement and its impact on the viability of the dental pulp; its impact on root resorption in teeth with vital pulps and teeth with previous root canal treatment; the ability to move orthodontically teeth that were endodontically treated versus nonendodontically treated; the role of previous tooth trauma; the ability to move teeth orthodontically that have been subjected to endodontic surgery; the role of orthodontic treatment in the provision for and prognosis of endodontic treatment; and, the integrated role of orthodontics and endodontics in treatment planning tooth retention. Orthodontic tooth movement can cause degenerative and/or inflammatory responses in the dental pulp of teeth with completed apical formation. The impact of the tooth movement on the pulp is focused primarily on the neurovascular system, in which the release of specific neurotransmitters (neuropeptides) can influence both blood flow and cellular metabolism. The responses induced in these pulps may impact on the initiation and perpetuation of apical root remodelling or resorption during tooth movement. The incidence and severity of these changes may be influenced by previous or ongoing insults to the dental pulp, such as trauma or caries. Pulps in teeth with incomplete apical foramen, whilst not immune to adverse sequelae during tooth movement, have a reduced risk for these responses. Teeth with previous root canal treatment exhibit less propensity for apical root resorption during orthodontic tooth movement. Minimal resorptive/remodelling changes occur apically in teeth that are being moved orthodontically and that are well cleaned, shaped, and three-dimensionally obturated. This outcome would depend on the absence of coronal leakage or other avenues for bacterial ingress. A traumatized tooth can be moved orthodontically with minimal risk of resorption, provided the pulp has not been severely compromised (infected or necrotic). If there is evidence of pulpal demise, appropriate endodontic management is necessary prior to orthodontic treatment. If a previously traumatized tooth exhibits resorption, there is a greater chance that orthodontic tooth movement will enhance the resorptive process. If a tooth has been severely traumatized (intrusive luxation/avulsion) there may be a greater incidence of resorption with tooth movement. This can occur with or without previous endodontic treatment. Very little is known about the ability to move successfully teeth that have undergone periradicular surgical procedures. Likewise, little is known about the potential risks or sequelae involved in moving teeth that have had previous surgical intervention. Especially absent is the long-term prognosis of this type of treatment. During orthodontic tooth movement, the provision of endodontic treatment may be influenced by a number of factors, including but not limited to radiographic interpretation, accuracy of pulp testing, patient signs and symptoms, tooth isolation, access to the root canal, working length determination, and apical position of the canal obturation. Adjunctive orthodontic root extrusion and root separation are essential clinical procedures that will enhance the integrated treatment planning process of tooth retention in endodontic-orthodontic related cases.

Blood volume in human bicuspid periodontal ligament determined by electron microscopy

The microvascular volume of periodontal ligament is reported to range from 1.63 to 3.5% in man, whereas that of animals varies from 7.5 to 11.5%. This transmission electron-microscopic investigation was undertaken to determine stereologically the volume in human periodontal ligament. The hypothesis tested was that the ligament blood volume in man is similar to that in animals. Left and right segments of mandible containing first and second premolars came from an adult burns' victim who underwent jaw reconstruction. The segments were immersion-fixed in 2.5% glutaraldehyde, demineralized at 4 degrees C in 0.1 M EDTA and processed for microscopy. Segments of distal periodontal ligament were sectioned at 150-micron intervals from the alveolar crest to the root apex and random tissue quadrats recorded for point counting and data analysis using a generalized linear-regression statistical model. Mean adjusted microvascular luminal volume was 9.52 +/- 2.28% (SEM) and the abluminal volume 12.91 +/- 2.76%; the wall volume was 3.39%. Significant differences existed between the luminal and abluminal volumes of the different vessel type (p < 0.05) and their distribution across the circumferential thirds of the ligament (p < 0.05). Total length density of the blood vessels was 149.84 x 10(3) cm/cm3 and the surface density 330.19 cm2/cm3. Postcapillary-sized venules held 69.1% of the total blood volume and provided 49.3% of the luminal surface area. Venous capillaries were the most common vessel, comprising 48.5%, and they contributed 71.5% of the overall length density. This study confirmed the hypothesis for the blood volume in the periodontal ligament in man. Blood volumes do not reflect the configurations of microvascular beds.

Cervical root resorption associated with guided tissue regeneration: a case report

Root surface resorption, ankylosis (replacement resorption) and alveolar bone resorption are not uncommon sequelae to periodontal healing in both animal and human trials whether the treatment objective is regenerative, preventive, or conservative. The present report describes a case with progressive cervical root resorption in a patient who received periodontal regenerative treatment with guided tissue regeneration (GTR). A 46-year-old woman was referred for treatment of severe periodontitis. Remaining radiographic attachment was less than 50%. Following a period of 18 months, during which non-surgical and surgical therapies were performed, angular defects were diagnosed on radiographs and recurrent bleeding periodontal pockets (6 mm) were found in the proximal areas of 24 and 25. Root caries was not present. Periodontal surgery with GTR was performed in this area. No immediate postsurgical complications were noted. Two years later, clinical and radiographic examinations revealed gingival recession with bleeding periodontal pockets (6 mm) which had partly uncovered severe proximal cervical resorptions in 25. Root surface caries was not present. Following surgical inspection, the root of 25 was removed. The root was subsequently prepared for histological analysis. Resorption cavities covered almost the entire cervical proximal surface of the root above intact infracrestal cementum and were covered by numerous CD68+, both mononuclear and multinucleated cells. In a central area as indicated on the radiographs, the cavities penetrated into the root canal. There was no evidence of root caries.

Intrusion of teeth in the combination implant-to-natural-tooth fixed partial denture: a review of the theories

This article reviews the literature dealing with the combination implant-to-natural-tooth-supported fixed partial denture. The restoration of masticatory function with a combination implant-to-natural-tooth fixed partial denture is associated with a variety of undesirable clinical sequelae, including the breakage of implant components, damage to the abutment teeth, or intrusion of the abutment teeth. Theories regarding intrusion of abutment teeth combined with implants for fixed partial dentures are only speculative. Several theories are presented to explain the intrusion of natural teeth in association with implant-to-natural-tooth fixed partial dentures. One of the first theories was based on the idea that a lack of normal stimulation of the periodontal ligament produces atrophy of the periodontal ligament and intrusion of the tooth. The remaining theories relate to excessive forces being placed on the natural tooth, resulting in movement of the tooth to a less stressful position. These forces are placed on the tooth by differential energy dissipation, mandibular flexion and torsion, flexion of the fixed partial denture framework, impaired rebound memory, debris impaction or microjamming, or ratchet effect related to the use of precision attachments. Based a review of the literature, a philosophy for treating combination implant-to-natural-tooth restorations is presented.

Attractive magnets for orthodontic extrusion of crown-root fractured teeth

A subgingival crown-root fracture presents the clinician with a difficult restorative problem, including reaching the fracture line, and is complicated by the need to maintain the periodontal tissues in good health. The treatment options up to now have usually been limited to extrusion of the remaining root with a conventional orthodontic appliance, surgical intraalveolar transplantation of the root or extraction with bridge replacement. In this report, a new method of orthodontic extrusion with attractive magnets is presented. One or two neodymium-iron-boron magnets were attached to the remaining root and a second, larger neodymium-iron-boron magnet was incorporated in a removable appliance. The roots were extruded 2 to 3 mm with a force range from 50 to 240 cN during a treatment period of 9 to 11 weeks. Good force control at short distances, no friction, and no material fatigue of permanent rare earth magnets resulted in successful rapid extrusion. No evidence of soft tissue dehiscences, aberrant tooth mobility, or root resorption was found.

Microvascular luminal volume changes in aged mouse periodontal ligament

Data for the microvascular bed in the aged periodontal ligament have not been established. This investigation tested the hypothesis that the luminal microvascular volume decreased in the aged ligament. Mice 35 days old and one year old were vascular-perfused and the mandibular first molar periodontal ligament processed for electron microscopy. Tissue quadrats from each circumferential third ligament region were recorded at 150-microns intervals from the alveolar crest to the apex for randomized sampling of blood vessel lumina. The data were analyzed with a generalized linear model at the p < 0.01 level for the interaction of the aging effect with differences across regions. Stereological parameters were established for vessel lumen volume, and for surface and length densities. Mean ligament width decreased from 119.9 +/- 16.94 (micron +/- SE) in young mice to 60.0 +/- 10.58 (micron +/- SE) in aged mice. The luminal volume of 8.63 +/- 1.37 (% +/- SE) in young ligament increased to 9.83 +/- 2.14 (% +/- SE) in aged ligament. Collecting venules and the combined group of arterio-venous anastomoses with terminal arterioles showed a two-fold increase in luminal volume density (p < 0.01). In aged ligament, regional shifts affected the microvascular bed distribution, but these changes were not consistent across regions, or with depth. The average cross-sectional tissue area served per capillary decreased from 2117 microns 2 to 1451 microns 2 for young and old. Average ligament thickness served per capillary dropped from 52.5 microns to 27.5 microns. These reductions in average diffusion distances indicated a change in the quality of the diffusion barrier with age.

Extrusion of root-filled incisors in beagles--a light microscope and scanning electron microscope investigation

The response of the periodontal ligament to orthodontic extrusion of the incisor of a beagle was examined with light microscope and scanning electron microscope techniques. The ligament morphology was slightly altered by the procedure but was essentially normal. Teeth that were extruded and retained for 12 weeks exhibited partial relapse. Where a full thickness mucogingival flap was raised and immediately replaced in lieu of retention, continued extrusion was observed. Root resorption was observed at the interproximal region of the cervical third in three out of five specimens. The resorption had been repaired with cellular cementum.

Ultrastructural morphology of vascular endothelial junctions in periodontal ligament

The TEM was used to categorize vessels and their junctions in normal and tensioned rat maxillary molar periodontal ligament. In tensioned periodontal ligament mean luminal diameters of capillaries were significantly smaller (p < 0.001). Goniometer tilting of sections with apparent tight regions revealed that only 16 per cent were actual tight junctions. The other regions proved to be close junctions (85 per cent) and open junctions (4 per cent). No gap junctions were found. These findings establish that morphologically the periodontal ligament contains a microvascular bed of 'leaky' endothelium with a potentially high permeability factor.