Dressed Rabi Oscillation in a Crystalline Organic Radical

Free electron laser-powered pulsed electron paramagnetic resonance experiments performed at 240  GHz/8.56  T on the crystalline organic radical 1,3-bisdiphenylene-2-phenylallyl reveal a tip-angle dependent resonant frequency. Frequency shifts as large as 11 MHz (45 ppm) are observed during a single Rabi oscillation. We attribute the frequency shifts to a "dressing" of the nutation by spin-spin interactions. A nonlinear semiclassical model which includes a temperature- and sample-geometry-dependent demagnetizing field reproduces experimental results. Because experiments are performed without a cavity, radiation damping, the most common nonlinear interaction in magnetic resonance, is negligible in our experiments.

Multi-step phase-cycling in a free-electron laser-powered pulsed electron paramagnetic resonance spectrometer

Electron paramagnetic resonance (EPR) is a powerful tool for research in chemistry, biology, physics and materials science, which can benefit significantly from moving to frequencies above 100 GHz. In pulsed EPR spectrometers driven by powerful sub-THz oscillators, such as the free electron laser (FEL)-powered EPR spectrometer at UCSB, control of the duration, power and relative phases of the pulses in a sequence must be performed at the frequency and power level of the oscillator. Here we report on the implementation of an all-quasioptical four-step phase cycling procedure carried out directly at the kW power level of the 240 GHz pulses used in the FEL-powered EPR spectrometer. Phase shifts are introduced by modifying the optical path length of a 240 GHz pulse with precision-machined dielectric plates in a procedure we call phase cycling with optomechanical phase shifters (POPS), while numerical receiver phase cycling is implemented in post-processing. The POPS scheme was successfully used to reduce experimental dead times, enabling pulsed EPR of fast-relaxing spin systems such as gadolinium complexes at temperatures above 190 K. Coherence transfer pathway selection with POPS was used to perform spin echo relaxation experiments to measure the phase memory time of P1 centers in diamond in the presence of a strong unwanted FID signal in the background. The large excitation bandwidth of FEL-EPR, together with phase cycling, enabled the quantitative measurement of instantaneous electron spectral diffusion, from which the P1 center concentration was estimated to within 10%. Finally, phase cycling enabled saturation-recovery measurements of T1 in a trityl-water solution at room temperature - the first FEL-EPR measurement of electron T1.

Quantitative analysis of zero-field splitting parameter distributions in Gd(iii) complexes

The magnetic properties of paramagnetic species with spin S > 1/2 are parameterized by the familiar g tensor as well as "zero-field splitting" (ZFS) terms that break the degeneracy between spin states even in the absence of a magnetic field. In this work, we determine the mean values and distributions of the ZFS parameters D and E for six Gd(iii) complexes (S = 7/2) and critically discuss the accuracy of such determination. EPR spectra of the Gd(iii) complexes were recorded in glassy frozen solutions at 10 K or below at Q-band (∼34 GHz), W-band (∼94 GHz) and G-band (240 GHz) frequencies, and simulated with two widely used models for the form of the distributions of the ZFS parameters D and E. We find that the form of the distribution of the ZFS parameter D is bimodal, consisting roughly of two Gaussians centered at D and -D with unequal amplitudes. The extracted values of D (σD) for the six complexes are, in MHz: Gd-NO3Pic, 485 ± 20 (155 ± 37); Gd-DOTA/Gd-maleimide-DOTA, -714 ± 43 (328 ± 99); iodo-(Gd-PyMTA)/MOMethynyl-(Gd-PyMTA), 1213 ± 60 (418 ± 141); Gd-TAHA, 1361 ± 69 (457 ± 178); iodo-Gd-PCTA-[12], 1861 ± 135 (467 ± 292); and Gd-PyDTTA, 1830 ± 105 (390 ± 242). The sign of D was adjusted based on the Gaussian component with larger amplitude. We relate the extracted P(D) distributions to the structure of the individual Gd(iii) complexes by fitting them to a model that superposes the contribution to the D tensor from each coordinating atom of the ligand. Using this model, we predict D, σD, and E values for several additional Gd(iii) complexes that were not measured in this work. The results of this paper may be useful as benchmarks for the verification of quantum chemical calculations of ZFS parameters, and point the way to designing Gd(iii) complexes for particular applications and estimating their magnetic properties a priori.

Gd3+-Gd3+ distances exceeding 3 nm determined by very high frequency continuous wave electron paramagnetic resonance

Electron paramagnetic resonance spectroscopy in combination with site-directed spin labeling is a very powerful tool for elucidating the structure and organization of biomolecules. Gd3+ complexes have recently emerged as a new class of spin labels for distance determination by pulsed EPR spectroscopy at Q- and W-band. We present CW EPR measurements at 240 GHz (8.6 Tesla) on a series of Gd-rulers of the type Gd-PyMTA-spacer-Gd-PyMTA, with Gd-Gd distances ranging from 1.2 nm to 4.3 nm. CW EPR measurements of these Gd-rulers show that significant dipolar broadening of the central |-1/2〉 → |1/2〉 transition occurs at 30 K for Gd-Gd distances up to ∼3.4 nm with Gd-PyMTA as the spin label. This represents a significant extension for distances accessible by CW EPR, as nitroxide-based spin labels at X-band frequencies can typically only access distances up to ∼2 nm. We show that this broadening persists at biologically relevant temperatures above 200 K, and that this method is further extendable up to room temperature by immobilizing the sample in glassy trehalose. We show that the peak-to-peak broadening of the central transition follows the expected 1/r3 dependence for the electron-electron dipolar interaction, from cryogenic temperatures up to room temperature. A simple procedure for simulating the dependence of the lineshape on interspin distance is presented, in which the broadening of the central transition is modeled as an S = 1/2 spin whose CW EPR lineshape is broadened through electron-electron dipolar interactions with a neighboring S = 7/2 spin.

Early cellular events in the penumbra of human spontaneous intracerebral hemorrhage

Spontaneous intracerebral hemorrhage causes high morbidity and mortality rates, and yet its treatment remains controversial, partly because of a poor understanding of the pathogenesis and timescale of injury in the surrounding brain. This study was undertaken to clarify the cellular reactions around human spontaneous intracerebral hematomas and relate these to hematoma duration and volume, in order to provide further data that might aid the development of therapeutic strategies. Brain tissue from the margin of the hematoma in 33 fatal cases of spontaneous intracerebral hemorrhage and corresponding tissue from 13 normal controls was studied using immunohistochemistry for heat-shock proteins, metallothionein, and various neuronal, glial, macrophage, and endothelial markers. Hematoma volumes were calculated from computed tomographic (CT) scans and autopsy measurements, whereas hematoma age was estimated from clinical records. The results showed that cellular events are time dependent, but not related to hematoma volume, and are identifiable in neurons, glia, and endothelium as early as 5 hours after hemorrhage. Peripheral macrophage infiltration begins at 5 days. The results suggest that the therapeutic window in humans for reperfusion of the ischemic penumbra of a hematoma is less than 5 hours, although progression of the infarcted core to the penumbral periphery within 1 to 3 days suggests a wider cytoprotective window. Edema, caused by blood-brain barrier breakdown, was also identified at 5 hours, and prompt treatment of this may reduce the space-occupying effects of the hematoma and, possibly, the morbidity and mortality.

Severe hyponatraemia in medical in-patients: aetiology, assessment and outcome

BACKGROUND

Hyponatraemia is the most commonly identified electrolyte abnormality. Published data on severe hyponatraemia in general medical in-patients is lacking.

AIM

To determine the aetiology, adequacy of assessment, and outcome of severe hyponatraemia in general medical in-patients.

DESIGN

Retrospective case-note review.

METHODS

All general medical in-patients (n = 108) with serum sodium < or =125 mmol/l were identified from the clinical chemistry database, over a six-month period. A full review of notes and computer records was undertaken at the index date and a pre-determined follow-up date.

RESULTS

Follow-up data were available in 105 patients. There was a wide range of aetiologies: diuretic therapy (loop and thiazide), congestive cardiac failure and liver disease were the most common, and 75.3% of patients had multiple causes. None of the 48% of patients whose history suggested a possible diagnosis of the syndrome of inappropriate anti-diuretic hormone (SIADH) met the generally accepted diagnostic criteria. Overall mortality was 20% during the index admission and 44.6% at follow-up, vs. 7.1% and 22%, respectively, for other patients admitted to the same directorate over the same time period (p < 0.001). Mortality was linked to aetiology, but not to reduced absolute serum sodium concentration at admission.

DISCUSSION

Severe hyponatraemia in general medical patients is associated with a complex, multifactoral aetiology and a very poor prognosis. Outlook is governed principally by aetiology, and not by serum sodium level. Assessment of patients with hyponatraemia requires a practical clinical algorithm for diagnosing SIADH.

Thiazide diuretic prescription and electrolyte abnormalities in primary care

AIMS

Thiazide diuretics have a number of well-documented metabolic adverse effects. The aim of this study was to estimate the frequency of hyponatraemia and hypokalaemia amongst patients taking a thiazide diuretic in primary care.

METHODS

A computerized search of the electronic prescribing and laboratory records of six UK general practices was performed. Of the 32 218 adult patients identified, 3773 had received at least one prescription for a thiazide between the years 1990 and 2002.

RESULTS

Detailed prescribing data were available for 2942 patients of whom 951 (32.3%) had a recorded check of their electrolytes. One hundred and ninety-six (20.6%) had a sodium and/or potassium concentration below the normal range. The sodium distribution had a negative skew (-1.8) and in 130 (13.7%) patients was within the hyponatraemic range. Hypokalaemia was less common, occurring in 79 (8.5%) patients. Hyponatraemia was significantly associated with increased age; the odds ratio for developing hyponatraemia in patients over 70 years was 3.87 compared with those of < or = 70 years. Hypokalaemia was significantly associated with increased thiazide dose.

CONCLUSIONS

Prescription of a thiazide diuretic in primary care is associated with a high frequency of hyponatraemia and hypokalaemia. Thiazides should be prescribed at low dose and the risk of hyponatraemia, especially in the elderly, should be considered and monitored for when prescribing these agents.

Orthotopic reimplantation of cryopreserved ovarian cortical strips after high-dose chemotherapy for Hodgkin's lymphoma

BACKGROUND

Infertility is a common late effect of chemotherapy and radiotherapy, and has a substantial effect on the quality of life for young survivors of cancer. For men, semen cryopreservation is a simple way of preserving reproductive potential but for women, storage of mature eggs rarely proves successful, and the alternative-immediate in vitro fertilisation with cryopreservation of embryos-is not always appropriate. Reimplantation of cryopreserved ovarian tissue has been shown to restore natural fertility in animals. We applied this technique in a woman who had received sterilising chemotherapy for lymphoma.

METHODS

A 36-year-old woman underwent a right oophorectomy with cryopreservation of ovarian cortical strips before receiving high-dose CBV chemotherapy for a third recurrence of Hodgkin's lymphoma. 19 months later, when serum sex steroid analysis confimed a postmenopausal state, two ovarian cortical strips were thawed and reimplanted-one onto the left ovary and another at the site of the right ovary.

FINDINGS

7 months after reimplantation of ovarian cortical strips, the patient reported resolution of hot flashes and, for the first time, oestradiol was detected in the serum. This finding was associated with a decrease in the concentrations of follicle-stimulating hormone and luteinising hormone, and ultrasonography revealed a 10 mm thick endometrium, a poorly visualised left ovary, and a 2 cm diameter follicular structure to the right of the midline. The patient had one menstrual period, but by 9 months after the implantation, her sex steroid concentrations had returned to those seen with ovarian failure.

INTERPRETATION

Orthotopic reimplantation of frozen/thawed ovarian cortical strips is a well tolerated technique for restoring ovarian function in women treated with sterilising chemotherapy for cancer.

Occlusion and prosthodontics

Occlusion in prosthodontics is extremely important. Muscle dysfunction can interfere with prosthodontic restoration of occlusion. Occlusal interferences are the primary cause of the hyperactivity that cause muscle dysfunction. Occlusal interference can also place adverse stress on restorations and result in premature failures. Lateral stresses on restorations can cause cement failures, porcelain fractures, and solder joint failures. Our goal in prosthodontics is to restore occlusion that is occlusal interference free. This article gave an overview of how this can be done in phases. In Phase I, a diagnosis is made as to the presence or absence of muscle dysfunction. If it is present, the OIs are hidden. Occlusal splint therapy is needed to get rid of the muscle dysfunction so the OIs can be found. The occlusal splint diagnosis whether OIs are the cause of the dysfunction. The cure is to correct the occlusion. The restoration of the occlusion should be OI free. The various factors to consider in design and restoration of the occlusion were presented. After successful restoration of the occlusion, the recall appointments should include an evaluation of the occlusion. The PRI, COS, and clinical examination can all be helpful in diagnosing whether muscle dysfunction is developing and whether OIs are developing again as a result of the normal changes that can occur. Suggestions were made on how to slow these changes. This article was not meant to cover every aspect of prosthodontic occlusion in detail. The goal was to present an overview for readers to make a self-evaluation as to what areas of their practice might need to be improved to improve the restoration of the occlusion. All was not taught in dental school. As one practices and improves in skill, more knowledge and abilities must be sought through graduate and postgraduate education. Occlusion is too important for a successful practice and happy patients to be ignored. Time will make this obvious; however, the failures may be costly. The best approach would be to anticipate the failures and prepare yourself to reduce the risks. Occlusal interferences are truly the plague of dentistry.

Comparison of the intercondylar distance and the interfacial width as used with the electronic pantograph

The electronic pantograph (Pantronic) records mandibular movements and computes the articulator settings. The Pantronic pantograph does not determine the intercondylar distance but approximates it from the interfacial width at the condyles. An average distance of 12.5 mm is subtracted from each side to determine the intercondylar distance. This study recorded 45 patients' articulator intercondylar distances that had been set from a mechanical pantograph and they were compared with the Pantronic's approximation. The difference between the interfacial width and the actual intercondylar distance was 15.1 mm on the right side and 14.9 mm on the left side. A numerical value of 15.0 mm was statistically superior to the Pantronic's 12.5 mm in estimating the average distance between the intercondylar distance and the surface of the skin at the condyle. No statistically significant difference was found between the differences of interfacial width and intercondylar distance values for men and women (p greater than 0.05). The mean intercondylar distance was 56.5 mm on the right side and 56.7 mm on the left side. A statistically significant difference was found between the mean intercondylar distances of men and women (p less than 0.05).

Effects of changes in articulator settings on generated occlusal tracings. Part II: Immediate side shift, intercondylar distance, and rear and top wall settings

An occlusal scribing device attached to a fully adjustable articulator was used to generate occlusal tracings. The tracings were analyzed to determine the effect changes in immediate side shift, intercondylar distance, and rear and top wall settings had on molar occlusal morphology. When ranked from greatest to least effect, a 0.2 mm change in the immediate side shift setting had the greatest effect on the occlusion, whereas a 5-degree change in the rear and top wall settings had the least effect.

Effects of changes in articulator settings on generated occlusal tracings. Part I: Condylar inclination and progressive side shift settings

An occlusal scribing device attached to a fully adjustable articulator was used to generate occlusal tracings. The tracings were analyzed to determine the effect changes in progressive side shift and condylar inclination settings had on molar occlusal morphology. The progressive side shift adjustment affected the cusp height and ridge and groove position, primarily in the nonworking excursion. The condylar inclination adjustment affected the cusp heights in the protrusive and nonworking excursion without affecting the working excursion.

[Occlusion in osseointegrated prosthesis]

Occlusion plays a significant role in the successful restoration of natural teeth and in replacing missing teeth. Over the decades, standards for occlusion have been established. Implants, osseointegrated, have provided a rigid, usable abutment for restorations of occlusion and for the replacement of missing teeth. The natural tooth, due to it's mobility dynamics, presents problems related to occlusion. The osseointegrated, rigid implant, due to it's lack of mobility, presents in many respects problems related to occlusion. Substantial amounts of research has been presented on implants as it relates to success of osseointegration and acceptance by bone, and the acceptance of oral mucosal tissues to penetration of the implant. Failures of implant fixtures and their parts have been experienced. Not much information has been presented on the causes of failures. The question becomes obvious What is the role of the forces of occlusion? The purpose of this article is to present some aspects of occlusion that are important in restoring natural teeth and complete dentures. The problems in applying these aspects to the osseointegrated, rigid implant will be presented. The factors to consider in the control of the forces of occlusion in using implants will be established. It is not possible to cover all the possibilities of occlusion for implantation. However, the factors to consider in making intelligent choices will be presented.

A clinical study of joint sounds in subjects with restored occlusions

It has been implied that temporomandibular joint sounds must be treated to eliminate the sounds before restorative treatments are attempted. This study explored the possibility that joint sounds do not present a problem when other symptoms are absent. A group of 35 subjects with restored occlusions were studied for the presence of temporomandibular joint dysfunction symptoms using clinical examination, questionnaires, and the pantographic reproducibility index. Forty-six percent had some degree of temporomandibular joint dysfunction. Seventeen of 18 subjects (94%) with joint sounds were free of other symptoms. Therefore, the use of joint sounds as a symptom of temporomandibular joint dysfunction is questionable when not accompanied by other clinical symptoms. Subjects who had temporomandibular joint dysfunction symptoms were treated with occlusal splint therapy and occlusal adjustments. The period of time to eliminate the symptoms was 2 to 16 weeks with an average of 7 weeks. This study concludes that the presence of only joint sounds does not seem to be a hindrance to restorative treatments.

A graphic comparison of mandibular border movements generated by various articulators. Part II: Results

A method was described in Part I in which mandibular border movements of a subject can be compared with the movements generated by various articulators (fully adjustable Denar SE and semiadjustable Denar Mark II) by using an electronic pantograph, the Pantronic. The mean values of 12 sets of plots from this device were calculated and graphs were generated. For the subject studied, differences were detected by the Pantronic pantograph between human border movements and those generated by each articulator and method of adjusting it. In the horizontal table, the semiadjustable articulator without immediate side shift always showed the potential of greater errors, especially as excursions started. When the semiadjustable instrument was programmed with immediate side shift, its movements were comparable with the fully adjustable articulator. Neither articulator exactly simulated the subjects' movements.

A graphic comparison of mandibular border movements generated by various articulators. Part I: Methodology

A method was described by which mandibular border movement of a subject can be compared with the movements generated by various articulators. The fully adjustable articulator, Denar SE, and the semiadjustable instrument, Denar Mark II, were used in this study. The movements were recorded by an electronic pantograph, the Pantronic. The mean values of 12 sets of print-out plots from this device were calculated by using Microsoft Excel software. These mean values were then used by CricatGraph software to generate combined graphs. Both software programs were used with an Apple Macintosh Plus personal computer. The clinical significance of the findings will be discussed in Part II of this study.

Evaluation of a digitizer and computer system designed to analyze articulator-generated occlusal tracings

Occlusal tracings generated on a Denar fully adjustable articulator were photographed, projected, digitized, and stored in a computer data file. These steps were accomplished with sufficient accuracy for clinical analysis. This study demonstrated that appropriately referenced tracing data can be transferred accurately into a machine-readable form. Studies of pantographic tracings for mandibular movements are facilitated by this convenient and accurate method of handling data.

An electronic, computerized pantographic reproducibility index for diagnosing temporomandibular joint dysfunction

One of the signs and symptoms of TMJ dysfunction is incoordinated mandibular movements. The PRI quantitates the incoordinated movements and gives a muscle dysfunction score and the relative severity of TMJ dysfunction. An electronic, computerized pantograph (Pantronic) has been developed that can be used in place of the mechanical pantograph. This study was undertaken to determine if the Pantronic can be programmed to produce PRI scores that are comparable to the M-pantograph PRI scores. Several programs were written for the computer until the Pantronic PRI was comparable to the M-pantograph PRI. The Pantronic PRI was within zero to 5 points of the M-pantograph PRI in all of the 25 patients studied. Because of this close comparison, studies used to validate the M-pantograph PRI also validate the Pantronic PRI. There was, however, a statistically significant difference (.05 level) between the two PRI scores. In spite of this difference the categories of TMJ dysfunction remained the same. The Pantronic PRI can be determined clinically in 20 to 30 minutes. It can be used to determine the presence and, more important, the absence of TMJ dysfunction; the success of occlusal splint therapy, occlusal adjustment, and restorative treatment; the changes in dysfunction over time; the success of other treatment modalities; and the level of dysfunction in TMJ dysfunction research.

Electronic PRI consistency in diagnosing temporomandibular joint dysfunction

Pantographic reproducibility was compared using electronic and mechanical pantographs. The scores were calculated electronically or manually by a single scorer. It can be concluded that (1) with 65.4% of dysfunction-free patients, the electronic pantograph is more consistent than the mechanical pantograph within sessions and over time in recording PRI dysfunction, (2) operators with varying experience need not cause P-PRI fluctuations with dysfunction-free patients, and (3) PRI fluctuations can be caused by temporomandibular joint dysfunction.

Comparison of mandibular movements recorded by two pantographs

Denar and Stuart pantographic tracings were obtained at 10 separate appointments with one patient. Twenty pantographic recordings were transferred to the Stuart fully adjustable articulator. One pantograph from each appointment was used to set the articulator. The second pantograph of each appointment was mounted on the articulator without altering the setting adjustments and compared to the first pantograph of the previous 10 sessions. Overlay tracings were generated on the articulator as a permanent record of how accurately the articulator had been set and to compare measurements to the nearest 0.1 mm. Each working and orbiting path tracing was measured at four locations with a total of 960 measurements. Paired and Student t tests determined statistically significant differences. Mean data showed a 0.007 mm difference between Stuart and Denar recordings and was not statistically significant. Of the 12 lines on each set of tracings, the right vertical working path revealed significant data. Of the 48 measuring sites, the right vertical working path and the left vertical orbiting path displayed noteworthy data.

A pantographic reproducibility index for use in diagnosing temporomandibular joint dysfunction: a report on research

The pantographic reproducibility index (PRI) has been developed to quantitate incoordinated mandibular movements; one of the signs and symptoms of TMJ dysfunction. The PRI has been proven valid clinically in controlled research using more than 200 patients and scoring more than 2300 pantographic tracings during the past 10 years. The PRI can be used to determine (1) the presence or absence of TMJ dysfunction; (2) the success of treatment modalities such as occlusal splints, occlusal adjustments, and restorative treatments; (3) the prevalence of TMJ dysfunction; and (4) the level of TMJ dysfunction on experimental patients.

A technique for evaluation of centric relation tooth contacts. Part II: Following use of an occlusal splint for treatment of temporomandibular joint dysfunction

The purpose of this study was to determine the effect of TMJ dysfunction on the recording of centric relation. Centric relation was recorded using an anterior occlusal stop and by bimanual manipulation. Changes in occlusal contacts were recorded before and after occlusal splint therapy in six subjects with TMJ dysfunction. The pantographic reproducibility index and clinical signs and symptoms were used to determine the presence or absence of dysfunction. Use of the anterior occlusal stop resulted in a more posterior, superior initial tooth contact position when compared with bimanual manipulation. Occlusal contact positions were less consistent in TMJ dysfunction subjects than in control subjects. Initial occlusal contacts changed toward centric relation as the dysfunction disappeared. Final occlusal contact was found on the side where clinical signs and symptoms occurred. The condyle on the affected side appeared to be repositioned posteriorly and superiorly in most instances. Occlusal splint therapy was more effective when the splint was adjusted weekly. This study indicates the need to eliminate TMJ dysfunction before recording centric relation or adjusting the occlusion. Occlusal interferences found with TMJ dysfunction are not the same as occlusal interferences found when TMJ dysfunction is absent. Abnormal features on pantographic tracings may aid in indicating the presence of occlusal interferences. Occlusal adjustment in the presence of TMJ dysfunction would result in erroneous occlusal reduction.

A technique for evaluation of centric relation tooth contacts. Part I: During normal temporomandibular joint function

An indirect method to locate the first tooth contacts in centric relation was described in this study. Mounted casts with an associated table and styli were used to locate the position of contact points in three planes. The method was tested using the anterior occlusal stop with chin point guidance and bimanual manipulation for recording centric relation. Ten records from one subject were analyzed statistically for each method. At the p less than .05 level of significance, the anterior occlusal stop produced a centric relation position more posterior than that found with bimanual manipulation. There was no statistically significant difference in the vertical and mediolateral planes. The anterior occlusal stop method produced more consistent tooth contacts in all three planes. The centric relation points found on the recording plates correlated well with the initial tooth contacts marked on the cast. This indirect method is an accurate means of recording and reevaluating changes in tooth contact positions in three planes.

Patients with restored occlusions. Part III: The effect of occlusal splint therapy and occlusal adjustments on TMJ dysfunction

An earlier study of 50 patients with occlusions restored by fixed partial dentures indicated a high percent (68%) of TMJ dysfunction. Occlusal interferences can play a significant role in causing TMJ dysfunction. To determine the significance of occlusal interferences, occlusal splints were placed in 10 of these restored patients who had moderate to severe dysfunction. The PRI was used to detect the presence or absence of TMJ dysfunction. The PRI TMJ dysfunction scores were reduced in all 10 patients after use of the occlusal splint. Five of the patients achieved reproducible tracings (no TMJ dysfunction) during the experiment time of 7 months. The occlusion of two patients was adjusted to eliminate the need for the occlusal splint. Patients who wore the splint 24 hours a day showed a significant (0.0004 level) reduction in TMJ dysfunction. Those patients who did not wear the splint regularly or had high levels of stress had PRI scores that varied. This finding indicates that the occlusal splint is not a treatment, as its removal permits reactivation of the occlusal interference. Resolution of dysfunction did not occur until occlusal interferences were removed. The changes in PRI scores to different dysfunction categories (none, slight, moderate, and severe) for the experimental group were significant at the 0.01 level. A control group of five patients had similar pantographic tracings but no other treatment. Their PRI scores varied, but there was no significant change in PRI scores or dysfunction categories. It was concluded that occlusal interferences were active causes of TMJ dysfunction in 10 of 36 patients in a population with restored occlusions.

Restored occlusions. Part II: The relationship of clinical and subjective symptoms to varying degrees of TMJ dysfunction

Fifty subjects restored with fixed restorations were examined by means of pantographic tracings and the PRI in order to determine the prevalence of TMJ dysfunction. In addition to the prevalence of dysfunction, the PRI categorized subjects as to the degree of dysfunction and clinical and subjective symptoms were related to the varying degrees of dysfunction. There were positive relationships (X)2 between the PRI categories and any dysfunction and many of the variables at the 0.1 level. There were positive correlations (Spearman R) at the 0.5 level between PRI categories and any level of TMJ dysfunction and many variables. The absence of clinical symptoms did not always indicate the absence of dysfunction as determined by the PRI.

Patients with restored occlusions. Part I: TMJ dysfunction determined by a pantographic reproducibility index

In a population of 50 subjects restored with fixed prostheses, the prevalence of TMJ dysfunction was 38% slight, 20% moderate, and 10% severe for a total of 68% showing some degree of dysfunction as recorded by pantographic tracings quantitated by the PRI. SD varied between categories. Higher PRI scores produced larger SD. The SD was 2.96 for the reproducible category, increasing progressively in each category, to 12.91 for the severe dysfunction category. The one session (four sets of tracings) used in the study to determine the degree of TMJ dysfunction appeared to be an accurate sample of a subject's PRI score for a given time. Control subject's scores appeared to stay relatively stable (p = .3649) over a period of time (1 to 3 months). While the scores did fluctuate, the category remained essentially the same. Those subjects with higher PRI scores showed the most fluctuation. The results indicated that pantographic tracings quantitated by the PRI can be used as a suitable instrument in epidemiologic studies to determine the prevalence of TMJ dysfunction.

Influence of TMJ dysfunction on Bennett movement as recorded by a modified pantograph. Part III: Progress report on the clinical study

The purpose of this investigation was to provide further insight into the characteristics of the induced and voluntary Bennett movement by determining the influence of TMJ dysfunction on the lateral side shift of the mandible as recorded by a modified pantograph. Twelve subjects were examined using pantographic tracings quantitated with the PRI to establish a baseline pattern of dysfunction for each subject. The PRI was used to categorize the subjects as to the degree of dysfunction. Following categorization, eight subjects were used as an experimental group and for subjects as a control group. On all subjects, induced and voluntary Bennett movement registrations were taken at the initial and final adjustment. Only the experimental subjects underwent an occlusal therapy consisting of an occlusal splint and an occlusal adjustment. Success of the therapy was monitored via the PRI. Following occlusal therapy, the reduction in PRI scores and categorization for the experimental group was significant to the 0.0042 level. There was no significant change inthe scores for the control group. Post-treatment Bennett movement registrations (voluntary and induced) indicated a statistically significant increase of the movement at the 0.043 level. The control group showed no significant change. Furthermore, on all subjects studied in this investigation, the voluntary Bennett movement was always within the borders of the induced Bennett movement, suggesting that the subject's neuromusculature was an important component in registering the lateral side shift of the mandible.

Influence of TMJ dysfunction on Bennett movement as recorded by a modified pantograph. Part II: Pilot articulator study

Within the limits of this study and when using pantographic instruments for research, the following conclusions can be drawn. Mechanical errors in the graphic tracings can result when the posterior vertical styli do not move with the mandible and are not zeroed in relationship to the terminal hinge axis. The errors were significant at the 0.035 level for the following variables: (1) an increase in the vertical dimension, up to 6 mm, (2) a change in the angle of the styli and/or of the tables relative to each other, up to 30 degrees, and (3) an increase in the distance between the posterior horizontal tables. If conclusions are to be drawn directly from tracings in research of mandibular movements, the recording styli should be orientated in relation to the terminal hinge axis and should move with the mandible.

The University of Michigan School of Dentistry, Ann Arbor

A pilot study has been described in which edentulous subjects were examined for their ability to reproduce lateral border movements, as measured by the PRI. The results of this study suggest that edentulous subjects, utilizing stabilized baseplates to support a pantograph, are capable of making reproducible lateral border movements as measured by the PRI.

Effects of occlusal splint therapy on TMJ dysfunction

A study was conducted to ascertain what happens to dysfunction symptoms followed only by occlusal splint therapy. Four hundred eighty-six pantograms were made on 15 experimental patients over a period of 5 months to 1 year. Five control patients were monitored over this same period but received no occlusal therapy. The experimental patients with TMJ dysfunction were treated with occlusal splint therapy. The occlusal splints were worn until the dysfunction symptoms were reduced and the pantographic PRI scores were reproducible. The occlusal splints were than removed without occlusal adjustments and the patients were monitored pantographically. A statistical analysis was performed on the PRI scores to determine the relationship between experimental and control patients. Experimental patients had an average drop of 21.7 points during occlusal splint therapy as compared to 3.8 points for control patients. All experimental patients had an increase in the PRI score levels following the removal of the occlusal splints.

Effects of occlusal therapy on pantographic reproducibility of mandibular border movements

A clinical experiment was undertaken to study the relationship between occlusal therapy and pantographic reproducibility. Twenty-six subjects were categorized according to their ability to reproduce pantographic border movements and were put into either a control nonreproducible, control reproducible, or experimental nonreproducible group. From each subject a sequence of five pantographic surveys consisting of two morning and two afternoon pantographic recordings was taken. Each survey period lasted a minimum of 30 days. The experimental subjects alone were given occlusal splint therapy and occlusal adjustment therapy during the sequence of recall periods. The relationship between the effect caused by occlusal therapy and pantographic reproducibility was analyzed. For the purpose of analysis, the pantographic recordings were assessed a numerical score using a pantographic reproducibility index. A double-blind technique was used until all data were collected.

Using pantographic tracings to detect TMJ and muscle dysfunctions

Forty-six subjects were examined using the HDI and a PRI. Two sets of pantographic tracings were used to determine if subjects experiencing dysfunction could differentiate between degrees of dysfunction. Subjects were divided into groups according to their clinical symptoms: none (D0), sligh (D1), and moderate dysfunction (D5). Each subject was further classified into one of two groups according to his state of occlusion/articulation. The PRI detected differences between the group with moderate dysfunction and those groups with no dysfunction and slight dysfunction on the basis of differences between the first and second sets of tracings; no difference was found between the groups with slight and moderate dysfunction. Subjects with poor occlusions had higher PRI scores. The diagnosis of TMJ dysfunction may require the use of several modalities such as subjective responses, clinical examination, radiographs, and pantographic tracings.

Pantographic records on TMJ dysfunction subjects treated with occlusal splints: a progress report

Five subjects with TMJ dysfunction showed difficulty in making reproducible mandibular border movements as recorded by a pantograph. These subjects were treated with occlusal bite splints, and muscle activity was studied by electromyography. After one month of treatment, most subjects showed relief of clinical symptoms and improved EMG muscular activity. Most of the subjects' mandibular movements did not improve to the point of making reproducible border movements on a pantograph. The length of time and the type of treatment may have had a significant effect on the results. This should be investigated further.