Martina Schmid-Schwap

Sex-specific differences in patients with temporomandibular disorders.

AIMS To explore potential differences in characteristics of patients that might account for sex-specific differences in temporomandibular disorders (TMD). METHODS A total of 502 patients presenting with TMD during 2000 to 2002 at the Outpatient Unit for Functional Disorders of the Medical University of Vienna underwent detailed evaluation of their medical history and assessment of clinical findings. The data obtained were assessed for sex-specific differences by analysis of variance and multiple regression. RESULTS Overall, 404 females (mean age ± SD: 40 ± 16 years; range 12 to 96 years) and 98 males (mean age 41 ± 16 years; range 16 to 78 years) were included. Their rating of their pain on a visual analog scale (VAS) showed a significantly higher pain intensity for females than for males (P = .004). Clinical assessment showed a significantly lower degree of mouth opening for females than for males (P < .001). While no sex-specific differences were noted for clicking phenomena of the temporomandibular joint (TMJ) and for the bite class of the patients, bite anomalies were significantly more frequent in male patients (P = .03). Palpation of masticatory muscles and the TMJ revealed significantly higher tenderness on palpation in female as compared to male patients (P = .001). Grouping by clicking, crepitation, and bruxism also showed greater pain (VAS) and more tenderness on palpation in females versus males. Females also showed peaks of prevalence of TMD in the age group below 25 years and in the group 55 to 60 years, whereas males had a more even age distribution. No external factors, such as exposure to stress, were found that moderated the sex difference. CONCLUSION Female TMD patients showed greater pain and muscle tenderness on palpation as compared to male TMD patients. They also showed a different age distribution of prevalence of TMD. These results were independent of subjective symptoms, clinical findings, and external factors.

Microleakage after thermocycling of cemented crowns - A meta-analysis.

OBJECTIVES Microleakage testing of dental materials is a commonly accepted evaluation technique of margin integrity. Thermocycling has been utilized by many researchers to study the influence of temperature extremes on the marginal gap of cemented restorations. The aim of this investigation was to analyze microleakage data on cemented crowns, published in the dental literature until Dec 2009, to identify methodological factors that might potentially affect the results of in vitro microleakage tests and to compare the results. METHODS The following databases were included: Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations and Ovid MEDLINE(R) 1950 to Present, Ovid-MEDLINE(R) 1950 to Present with Daily Update, EMBASE, EBM Reviews - Cochrane Database of Systematic Reviews and Pub Med. The search was limited to articles in English, French, Italian and German published until the end of 2009. Classical reviews, comments, animal studies, in vivo articles and studies investigating restorative materials or milk teeth were excluded. 33 different studies were finally selected. The studies were entered in a database and compared using selected literature criteria: sample, restoration procedures, thermocycling and mechanical cycling, evaluation method. For statistical analysis only 16 studies could be applied. RESULTS It was not possible to make a quantitative synthesis of most of the data, due to the heterogeneity of the studies concerning methods, treatment and outcome variables. Comparing the main groups of materials (ceramics, gold alloys and base metal alloys), no significant difference in the proportion of teeth without microleakage was found. Furthermore no significant difference in the proportion of teeth showing microleakage less than two third of the wall or teeth showing microleakage including the entire wall was found. Using the mean values in the meta-analysis instead of the proportions does not change the results. Confidence intervals could only be calculated for two materials (gold alloy, metal alloy). No difference between materials was found. SIGNIFICANCE Comparison of the results from different studies is critical, since there are no generally accepted standards for experimental parameters, such as type and concentration of the storage solution, time of storage, temperature during storage, type and duration of thermal cycling and/or mechanical cycling, and the scoring criteria. There is lack of standardization of experimental conditions, which would ensure confidence in the studies and would further allow better comparability of various results.

Diagnosis of temporomandibular dysfunction syndrome—image quality at 1.5 and 3.0 Tesla magnetic resonance imaging

The purpose of this study was to examine the differences in expert ratings of quality of magnetic resonance images (MRI) of the temporomandibular joint in 24 patients with suspected anterior disc displacement examined in randomized order at 1.5 and 3.0 T. Parasagittal (closed and opened mouth) and paracoronal sections were performed with a surface coil. Two experienced examiners blinded to patient status and type of MRI diagnosed the images according to position of condyle, position and changes in the signal, and disc shape. In addition, perceptibility of position and disc shape were assessed. A highly significant difference in the perceptibility of disc shape (P < 0.001) and position (P < 0.001) was obtained. With comparable examination sequences and identical resolution, the 3.0 T MRI of the temporomandibular joint increases the perceptibility of joint structures.

Wear of two artificial tooth materials in vivo: A 12-month pilot study

STATEMENT OF PROBLEM Wear of methacrylate artificial teeth resulting in vertical loss is a problem for both dentists and patients. PURPOSE The purpose of this study was to quantify wear of artificial teeth in vivo and to relate it to subject and tooth variables. MATERIAL AND METHODS Twenty-eight subjects treated with complete dentures received 2 artificial tooth materials (polymethyl methacrylate (PMMA)/double-cross linked PMMA fillers; 35%/59% (SR Antaris DCL, SR Postaris DCL); experimental 48%/46%). At baseline and after 12 months, impressions of the dentures were poured with improved stone. After laser scanning, the casts were superimposed and matched. Maximal vertical loss (mm) and volumetric loss (mm(3)) were calculated for each tooth and log-transformed to reduce variability. Volumetric loss was related to the occlusally active surface area. Linear mixed models were used to study the influence of the factors jaw, tooth, and material on adjusted (residual) wear values (alpha=.05). RESULTS Due to drop outs (n=5) and unmatchable casts (n=3), 69% of all teeth were analyzed. Volumetric loss had a strong linear relationship to surface area (P<.001); this was less pronounced for vertical loss (P=.004). The factor showing the highest influence was the subject. Wear was tooth dependent (increasing from incisors to molars). However, these differences diminished once the wear rates were adjusted for occlusal area, and only a few remained significant (anterior versus posterior maxillary teeth). Another influencing factor was the age of the subject. CONCLUSIONS Clinical wear of artificial teeth is higher than previously measured or expected. The presented method of analyzing wear of artificial teeth using a laser-scanning device seemed suitable.

Correlation Between Disk Morphology on MRI and Time Curves Using Electronic Axiography

Abstract This retrospective series was intended to determine whether morphological disk findings in open and closed mouth magnetic resonance imaging (MRI) may be correlated with the time curves in axiography. In this series, 45 temporomandibular joints of 33 patients were subjected to a retrospective evaluation. Magnetic resonance images obtained with closed and open mouth and joint movements assessed by electronic axiography were analyzed. Disk morphology in MRI was classified as normal, partly flattened, partly thickened, or completely thickened. For the axiographic tracings, time curves of the free movements of the respective joint were developed and evaluated. Data obtained were analyzed for any potential correlation using scatter plots and discriminance analysis. No correlation between these data was found suggesting that the axiographic time curves do not provide for any conclusions with regard to disk morphology. Apart from patient history and a thorough clinical evaluation, recording of jaw movements, but also using MRI continues to be of particular value in the diagnostic assessment of anterior disk displacement.

Testing for aerobic heterotrophic bacteria allows no prediction of contamination with potentially pathogenic bacteria in the output water of dental chair units

Background: Currently, to our knowledge, quality of output water of dental chair units is not covered by specific regulations in the European Union, and national recommendations are heterogeneous. In Germany, water used in dental chair units must follow drinking water quality. In the United States of America, testing for aerobic heterotrophic bacteria is recommended. The present study was performed to evaluate whether the counts of aerobic heterotrophic bacteria correlate with the presence of potentially pathogenic bacteria such as Legionella spp. or Pseudomonas aeruginosa. Methods: 71 samples were collected from 26 dental chair units with integrated disinfection device and 31 samples from 15 outlets of the water distribution pipework within the department were examined. Samples were tested for aerobic heterotrophic bacteria at 35°C and 22°C using different culture media and for Legionella spp. and for Pseudomonas aeruginosa. Additionally, strains of Legionella pneumophila serogroup 1 were typed with monoclonal antibodies and representative samples of Legionella pneumophila serogroup 1 were typed by sequence based typing. Results: Our results showed a correlation between different agars for aerobic heterotrophic bacteria but no correlation for the count of aerobic heterotrophic bacteria and the presence of Legionella spp. or Pseudomonas aeruginosa. Conclusion: Testing for aerobic heterotrophic bacteria in output water or water distribution pipework within the departments alone is without any value for predicting whether the water is contaminated with potentially pathogenic bacteria like Legionella spp. or Pseudomonas aeruginosa.

Regional Collagen Fiber Network in the Articular Disc of the Human Temporomandibular Joint: Biochemical 3-Tesla Quantitative Magnetic Resonance Imaging Compared to Quantitative Histologic Analysis of Fiber Arrangement

AIMS To evaluate the regional collagen fiber network in the human temporomandibular joint (TMJ) disc by using biochemical magnetic resonance imaging (MRI) and quantitative histology. METHODS MRI of 5 heads (10 TMJ discs) obtained from partially dentate or edentulous cadavers was performed at 3-Tesla MRI by using a flexible, 8-channel transmit-receive coil. After MRI, all 10 discs were processed histologically. Percentages of coronal, sagittal, and transverse collagen fibers were assessed stereologically for the anterior, central, and posterior parts of the disc. An anisotropy index was calculated for collagen fiber arrangement in all three regions of interest. RESULTS In the central part of the TMJ disc, collagen fibers were arranged anisotropically with a preferentially sagittal direction. In the anterior and posterior parts, evidence for fibers being arranged isotropically (randomly) without preferred direction was found. Mean MRI T2 values appeared to be correlated with the anisotropy index of collagen fibers (r = -0.45; P < .05). When tested individually, T2 values of the isotropic anterior and posterior disc regions showed a partial but significant correlation with the anisotropy index of collagen fibers (r = -0.54; P < .05), whereas the anisotropic central part did not (P > .05). CONCLUSION This study has provided the first systematic comparison of quantitative data on collagen fiber isotropy and anisotropy assessed in histologic sections with biochemical quantitative MRI for human TMJ fibrous cartilage.

Delayed gadolinium-enhanced MRI of the fibrocartilage disc of the temporomandibular joint--a feasibility study.

Objective To 1) test the feasibility of delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) at 3 T in the temporomandibular joint (TMJ) and 2) to determine the optimal delay for measurements of the TMJ disc after i.v. contrast agent (CA) administration. Design MRI of the right and left TMJ of six asymptomatic volunteers was performed at 3 T using a dedicated coil. 2D inversion recovery (2D-IR) sequences were performed at 4 time points covering 120 minutes and 3D gradient-echo (3D GRE) dual flip-angle sequences were performed at 14 time points covering 130 minutes after the administration of 0.2 mmol/kg of Gd-diethylenetriamine pentaacetic acid ion (Gd-DTPA)2-, i.e., 0.4 mL of Magnevist™ per kg body weight. Pair-wise tests were used to assess differences between pre-and post-contrast T1 values. Results 2D-IR sequences showed a statistically significant drop (p < 0.001) in T1 values after i.v. CA administration. The T1 drop of 50% was reached 60 minutes after bolus injection in the TMJ disc. The 3D GRE dual flip-angle sequences confirmed these results and show plateau of T1 after 60 minutes. Conclusions T1(Gd) maps calculated from dGEMRIC data allow in vivo assessment of the fibrocartilage disc of the TMJ. The recommended measurement time for dGEMRIC in the TMJ after i.v. CA administration is from 60 to 120 minutes.