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Dive into the research topics where John O. Look is active.

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Featured researches published by John O. Look.


Pain | 2011

The effect of catastrophizing and depression on chronic pain – a prospective cohort study of temporomandibular muscle and joint pain disorders

Ana M. Velly; John O. Look; Charles R. Carlson; Patricia Lenton; Wenjun Kang; Christina Holcroft; James R. Fricton

Summary Catastrophizing and depression are shown to contribute to the progression of temporomandibular muscle and joint disorders. Abstract Although most cases of temporomandibular muscle and joint disorders (TMJD) are mild and self‐limiting, about 10% of TMJD patients develop severe disorders associated with chronic pain and disability. It has been suggested that depression and catastrophizing contributes to TMJD chronicity. This article assesses the effects of catastrophizing and depression on clinically significant TMJD pain (Graded Chronic Pain Scale [GCPS] II–IV). Four hundred eighty participants, recruited from the Minneapolis/St. Paul area through media advertisements and local dentists, received examinations and completed the GCPS at baseline and at 18‐month follow‐up. In a multivariable analysis including gender, age, and worst pain intensity, baseline catastrophizing (&bgr; 3.79, P < 0.0001) and pain intensity at baseline (&bgr; 0.39, P < 0.0001) were positively associated with characteristic of pain intensity at the 18th month. Disability at the 18‐month follow‐up was positively related to catastrophizing (&bgr; 0.38, P < 0.0001) and depression (&bgr; 0.17, P = 0.02). In addition, in the multivariable analysis adjusted by the same covariates previously described, the onset of clinically significant pain (GCPS II–IV) at the 18‐month follow‐up was associated with catastrophizing (odds ratio [OR] 1.72, P = 0.02). Progression of clinically significant pain was related to catastrophizing (OR 2.16, P < 0.0001) and widespread pain at baseline (OR 1.78, P = 0.048). Results indicate that catastrophizing and depression contribute to the progression of chronic TMJD pain and disability, and therefore should be considered as important factors when evaluating and developing treatment plans for patients with TMJD.


Journal of Dental Research | 2007

Randomized Effectiveness Study of Four Therapeutic Strategies for TMJ Closed Lock

Eric L. Schiffman; John O. Look; James S. Hodges; James Q. Swift; K. L. Decker; K.M. Hathaway; R.B. Templeton; James R. Fricton

For individuals with temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock), interventions vary from minimal treatment to surgery. In a single-blind trial, 106 individuals with TMJ closed lock were randomized among medical management, rehabilitation, arthroscopic surgery with post-operative rehabilitation, or arthroplasty with post-operative rehabilitation. Evaluations at baseline, 3, 6, 12, 18, 24, and 60 months used the Craniomandibular Index (CMI) and Symptom Severity Index (SSI) for jaw function and TMJ pain respectively. Using an intention-to-treat analysis, we observed no between-group difference at any follow-up for CMI (p ≥ 0.33) or SSI (p ≥ 0.08). Both outcomes showed within-group improvement (p < 0.0001) for all groups. The findings of this study suggest that primary treatment for individuals with TMJ closed lock should consist of medical management or rehabilitation. The use of this approach will avoid unnecessary surgical procedures.


The Journal of Pain | 2010

The Effect of Fibromyalgia and Widespread Pain on the Clinically Significant Temporomandibular Muscle and Joint Pain Disorders—A Prospective 18-Month Cohort Study

Ana M. Velly; John O. Look; Eric L. Schiffman; Patricia Lenton; Wenjun Kang; Ronald P. Messner; Christina Holcroft; James R. Fricton

UNLABELLED Although most cases of temporomandibular muscle and joint disorders (TMJD) are mild and self-limiting, about 10% of TMJD patients develop severe disorders associated with chronic pain and disability. It has been suggested that fibromyalgia and widespread pain play a significant role in TMJD chronicity. This paper assessed the effects of fibromyalgia and widespread pain on clinically significant TMJD pain (GCPS II-IV). Four hundred eighty-five participants recruited from the Minneapolis/St. Paul area through media advertisements and local dentists received examinations and completed the Graded Chronic Pain Scale (GCPS) at baseline and at 18 months. Baseline widespread pain (OR: 2.53, P = .04) and depression (OR: 5.30, P = .005) were associated with onset of clinically significant pain (GCPS II-IV) within 18 months after baseline. The risk associated with baseline fibromyalgia was moderate, but not significant (OR: 2.74, P = .09). Persistence of clinically significant pain was related to fibromyalgia (OR: 2.48, P = .02) and depression (OR: 2.48, P = .02). These results indicate that these centrally generated pain conditions play a role in the onset and persistence of clinically significant TMJD. PERSPECTIVE Fibromyalgia and widespread pain should receive important consideration when evaluating and developing a treatment plan for patients with TMJD.


Cephalalgia | 2012

Diagnostic criteria for headache attributed to temporomandibular disorders

Eric L. Schiffman; Richard Ohrbach; Thomas List; Gary C. Anderson; Rigmor Jensen; Mike T. John; Donald R. Nixdorf; Jean-Paul Goulet; Wenjun Kang; Ed Truelove; Al Clavel; James R. Fricton; John O. Look

Aims: We assessed and compared the diagnostic accuracy of two sets of diagnostic criteria for headache secondary to temporomandibular disorders (TMD). Methods: In 373 headache subjects with TMD, a TMD headache reference standard was defined as: self-reported temple headache, consensus diagnosis of painful TMD and replication of the temple headache using TMD-based provocation tests. Revised diagnostic criteria for Headache attributed to TMD were selected using the RPART (recursive partitioning and regression trees) procedure, and refined in half of the data set. Using the remaining half of the data, the diagnostic accuracy of the revised criteria was compared to that of the International Headache Society’s International Classification of Headache Diseases (ICHD)-II criteria A to C for Headache or facial pain attributed to temporomandibular joint (TMJ) disorder. Results: Relative to the TMD headache reference standard, ICHD-II criteria showed sensitivity of 84% and specificity of 33%. The revised criteria for Headache attributed to TMD had sensitivity of 89% with improved specificity of 87% (p < 0.001). These criteria are (1) temple area headache that is changed with jaw movement, function or parafunction and (2) provocation of that headache by temporalis muscle palpation or jaw movement. Conclusion: Having significantly better specificity than the ICHD-II criteria A to C, the revised criteria are recommended to diagnose headache secondary to TMD.


International Journal of Oral and Maxillofacial Surgery | 2014

Effects of four treatment strategies for temporomandibular joint closed lock

Eric L. Schiffman; Ana M. Velly; John O. Look; James S. Hodges; James Q. Swift; K. L. Decker; Q. N. Anderson; R.B. Templeton; Patricia Lenton; Wenjun Kang; James R. Fricton

A previous randomized controlled trial (RCT) by Schiffman et al. (2007)(15) compared four treatments strategies for temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock). In this parallel group RCT, 106 patients with magnetic resonance imaging (MRI)-confirmed TMJ closed lock were randomized between medical management, non-surgical rehabilitation, arthroscopic surgery, and arthroplasty. Surgical groups also received rehabilitation post-surgically. The current paper reassesses the effectiveness of these four treatment strategies using outcome measures recommended by the International Association of Oral and Maxillofacial Surgeons (IAOMS). Clinical assessments at baseline and at follow-up (3, 6, 12, 18, 24, and 60 months) included intensity and frequency of TMJ pain, mandibular range of motion, TMJ sounds, and impairment of chewing. TMJ MRIs were performed at baseline and 24 months, and TMJ tomograms at baseline, 24 and 60 months. Most IAOMS recommended outcome measures improved significantly over time (P≤0.0003). There was no difference between treatment strategies relative to any treatment outcome at any follow-up (P≥0.16). Patient self-assessment of treatment success correlated with their ability to eat, with pain-free opening ≥35mm, and with reduced pain intensity. Given no difference between treatment strategies, non-surgical treatment should be employed for TMJ closed lock before considering surgery.


Journal of Prosthetic Dentistry | 1990

Preliminary results from disinfection of irreversible hydrocolloid impressions

John O. Look; David J. Clay; Ke Gong; H.H. Messer

The virucidal efficacy of germicides acting on an irreversible hydrocolloid surface is not known. Tests that are currently performed on germicides do not simulate the conditions under which the germicides are often used. One major concern for the dental profession is the disinfection of dental impressions, particularly irreversible hydrocolloid impressions. This study was designed to test the biocidal action of germicides against an enveloped virus on an irreversible hydrocolloid surface. The disinfection model, which was developed to simulate clinical conditions, specified the use of vesicular stomatitus virus, an animal virus amenable to safe handling. A 0.5% sodium hypochlorite spray inactivated the virus when the spray was allowed to remain on the impression 3 to 10 minutes. The iodophor disinfectant required a 3- to 10-minute immersion for total inactivation. Although 2% glutaraldehyde achieved total viral inactivation in less than 1 minute, the authors conclude that short disinfectant sprays, in general, are not an appropriate disinfection method.


Journal of Endodontics | 2012

Large-scale clinical endodontic research in the national dental practice-based research network: Study overview and methods

Donald R. Nixdorf; Alan S. Law; John O. Look; D. Brad Rindal; Emily U. Durand; Wenjun Kang; Bonita S. Agee; Jeffrey L. Fellows; Valeria V. Gordan; Gregg H. Gilbert

INTRODUCTION This article reports on the feasibility of conducting a large-scale endodontic prospective cohort study in The National Dental Practice-Based Research Network. This study was designed to measure pain and burden associated with initial orthograde root canal therapy (RCT) and to explore potential prognostic factors for pain outcomes. The main objectives of this first report in a series are to describe the projects feasibility and methods and the demographics of the sample obtained. METHODS Sixty-two dentist practitioner-investigators (ie, 46 generalists and 16 endodontists) in 5 geographic areas were certified within the network and trained regarding the standardized study protocol. Enrollment and baseline data collection occurred over 6 months with postobturation follow-up for another 6 months. Patients and dentists completed questionnaires before and immediately after treatment visits. Patients also completed questionnaires at 1 week, 3 months, and 6 months after obturation. RESULTS Enrollment exceeded target expectations, with 708 eligible patient-participants. Questionnaire return rates were good, ranging between 90% and 100%. Patient demographics were typical of persons who receive RCT in the United States (ie, mean age = 48 years [standard deviation = 13 years], with most being female [59%], college educated [81%], white non-Hispanic [86%], and having dental insurance [81%]). The tooth types being treated were also typical (ie, 61% molars, 28% premolars, and 11% anteriors, with maxillary teeth being predominant [59%]). CONCLUSIONS This study shows the feasibility of conducting large-scale endodontic prospective cohort studies in the network. Patients were rapidly recruited with high levels of compliance in data collection.


Journal of Dental Research | 2017

Longitudinal Stability of Common TMJ Structural Disorders

Eric L. Schiffman; Mansur Ahmad; Lars Hollender; Krishnan Kartha; Richard Ohrbach; Edmond L. Truelove; Lei Zhang; James S. Hodges; Earl Sommers; Gary C. Anderson; Yoly Gonzalez; X. Guo; John O. Look

The longitudinal course of temporomandibular joint (TMJ) disc displacement (DD) and degenerative joint disease (DJD) has never been conclusively described with magnetic resonance imaging and computed tomography, respectively. This 8-y observational study’s objective was to assess the longitudinal stability of DD and DJD among 401 subjects. The Validation Project provided baseline measures; follow-up was performed in the TMJ Impact Project. With magnetic resonance imaging, 2 radiologists rendered a consensus diagnosis of normal/indeterminate, DD with reduction, or DD without reduction. Computed tomography consensus diagnoses included normal/indeterminate, grade 1 DJD, or grade 2 DJD. Radiologist reliability was assessed by kappa; a Hui-Walter model was used to estimate, after accounting for diagnostic disagreement, the frequency of diagnostic progression and reversal. Permutation tests were used to test the statistical influence of concurrent baseline diagnoses on diagnostic changes at follow-up. Of 789 baseline joint-specific soft tissue diagnoses of DD, 598 (76%) joints showed no change; 109 (14%) demonstrated progression; and 82 (10%) had reversal. Of 794 joints with baseline joint-specific hard tissue diagnoses of DJD, progression was observed in 122 (15%) joints, no change in 564 (71%), and reversal in 108 (14%). Radiologist reliability (kappa) was 0.73 (95% CI, 0.64 to 0.83) for DD and 0.76 (95% CI, 0.68 to 0.83) for DJD. After accounting for the influence of diagnostic disagreement, progression of hard tissue diagnoses in the right TMJ occurred in 15.2% of subjects (95% CI, 10.5% to 20.8%) and reversal in 8.3% (95% CI, 4.9% to 12.3%); results were similar for soft tissue diagnoses and the left TMJ. Concurrent baseline soft tissue diagnoses were associated with hard tissue diagnostic changes at follow-up (P < 0.0001). Baseline hard tissue diagnoses showed no statistical association with soft tissue changes at follow-up (P = 0.11). Longitudinally, 76% of baseline TMJ soft tissue diagnoses and 71% of the baseline hard tissue diagnoses remained stable. Diagnostic reversal and progression were confirmed for both soft and hard tissues.


Journal of Oral and Maxillofacial Surgery | 2009

A Quantitative Evaluation of Inflammatory Cells in Human Temporomandibular Joint Tissues From Patients With and Without Implants

Aurelio A. Alonso; Shanti Kaimal; John O. Look; James Q. Swift; James R. Fricton; Sandra L. Myers; Lois J. Kehl

PURPOSE Previous studies made only qualitative assessments of immune cell responses to temporomandibular joint (TMJ) implant wear debris. The aim of this study was to perform a quantitative comparison of inflammatory cell types in TMJ tissues with implant wear debris, TMJ tissues with a history of disc pathology without implant debris, and TMJ tissues from normal control subjects. MATERIALS AND METHODS TMJ tissues were collected from the following 3 groups of subjects: 1) individuals with failed TMJ implants (implant group, n = 10), 2) patients with TMJ disc pathology but no history of implant placement (nonimplant surgery group, n = 10), and normal cadaveric tissues with no history of surgery (control group, n = 10). Tissue sections (5 microm) from all subjects were stained with hematoxylin-eosin, after which cell counts were done for 2 types of inflammatory cells: multinucleated giant cells and lymphocytes. Mean inflammatory cell counts from the 3 groups were compared by use of a 1-way analysis of variance procedure and Bonferroni adjustment to maintain an overall type I error rate of .05. RESULTS Implant group tissues contained significantly more inflammatory cells than tissues from the nonimplant surgery and control groups (P < .0001). Multinucleated giant cells were only present in implant group tissues. Although the high number of multinucleated giant cells present in the implant group obscured a total count of lymphocytes for that group, lymphocyte cell counts were still significantly greater (P < .005) in implant group tissues than in tissues from the other 2 groups. CONCLUSIONS Our data provide quantitative confirmation that the presence of Proplast-Teflon implant (Vitek, Houston, TX) wear debris is associated with a significant increase in the number of local multinucleated giant cells and lymphocytes.


BMC Musculoskeletal Disorders | 2009

Electric toothbrush application is a reliable and valid test for differentiating temporomandibular disorders pain patients from controls

Donald R. Nixdorf; Azar Hemmaty; John O. Look; Eric L. Schiffman; Mike T. John

BackgroundCurrent methods for identifying patients with pain hypersensitivity are sufficiently complex to limit their widespread application in clinical settings. We assessed the reliability and validity of a simple multi-modal vibrotactile stimulus, applied using an electric toothbrush, to evaluate its potential as a screening tool for central sensitization.MethodsFourteen female temporomandibular disorders (TMD) subjects with myofascial pain (RDC/TMD Ia or Ib) and arthralgia (RDC/TMD IIIa) were compared to 13 pain-free controls of matched age and gender. Vibrotactile stimulus was performed with an electric toothbrush, applied with 1 pound pressure for 30 seconds in four locations: over the lateral pole of the temporomandibular joint, masseter, temporalis, and mid-ventral surface of forearm. Pain intensity (0–10) was recorded following the stimulus at 0, 15, 30, and 60 seconds. Test-retest reliability was assessed with measurements from 8 participants, taken 2–12 hours apart. Case versus control differentiation involved comparison of area under the curve (AUC). A receiver operating characteristic (ROC) curve was used to determine cutoff AUC scores for maximum sensitivity and specificity for this multi-modal vibrotactile stimulus.ResultsTest-retest reliability resulted in an ICC of 0.87 for all 4 pooled sites. ROC-determined AUC cutoff scores resulted in a sensitivity of 57% and specificity of 92% for all 4 pooled sites.ConclusionThe electric toothbrush stimulus had excellent test-retest reliability. Validity of the scores was demonstrated with modest sensitivity and good specificity for differentiating TMD pain patients from controls, which are acceptable properties for a screening test.

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Ana M. Velly

Jewish General Hospital

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Mike T. John

University of Minnesota

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Wenjun Kang

University of Minnesota

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