Muscle–bone relationship in temporomandibular joint disorders after partial discectomy

ObjectivesTemporomandibular joint osteoarthritis (TMJ-OA) causes degenerative changes in TMJ tissues. The inter-tissue crosstalk that exacerbates illness and organic changes in bone secondary to TMJ-OA potentially affects the muscles; therefore, patients with a muscular disease might also suffer from bone disease. However, knowledge gaps exist concerning muscle pathology at the onset of TMJ-OA. In this study, we documented the pathogeneses of the bone and muscle at the onset of TMJ-OA using a mouse model.MethodsWe performed a partial resection of the TMJ disk to establish a mouse model of TMJ-OA. After the onset of TMJ-OA, we performed various measurements at 8, 12, and 16 weeks post-surgery in the defined groups.ResultsThe volume of the mandibular head in the TMJ-OA group was significantly greater than that in the control group. The temporal muscles in the TMJ-OA group were significantly deformed compared with those in the control group; however, between-group comparisons did not reveal significant differences in the mandibular head or temporal muscles after surgery. Therefore, we hypothesized that the degree of mandibular head hypertrophy would alter the temporal muscles. A subsequent analysis of the correlation between the bone and muscle confirmed that the deformity of the temporal muscle increased with increasing hypertrophy of the mandibular head. Temporal and masseter muscle contact was observed in 25% of surgical groups.ConclusionsThis study demonstrates that TMJ-OA progressed when organic changes occurred in bones and muscles, supporting the symbiotic relationship between bones and muscles.     

Transport distraction osteogenesis compared with autogenous grafts for ramus-condyle unit reconstruction in temporomandibular joint ankylosis: a systematic review and meta-analysis

This systematic review was planned to assess the clinical outcomes of transport distraction osteogenesis (TDO) compared with autogenous grafts for reconstruction of the ramus condyle unit (RCU). We searched Medline, Embase, Cochrane Library, Clinicaltrial.gov, and the references of included trials. The primary outcome was maximal incisal opening (MIO). Of the 148 studies retrieved, five were included (TDO = 49, autogenous grafts =123). The mean difference in MIO between TDO and autogenous graft RCU reconstruction, based on the random-effects model was 1.28 mm (95% CI 0.167 to 2.403) in favour of TDO. Re-ankyosis was observed in four cases in the costochondral graft group and none in the TDO group. Reconstruction of the RCU using TDO is comparable to autogenous grafts after the release of TMJ ankylosis, though the evidence is weak considering the small number of trials, high risk of bias, and absence of long-term results.     

Osteoclast formation from mouse bone marrow cells on micro/nano-scale patterned surfaces

ObjectivesOsteoclasts can sense the surface topography of materials. However, it is difficult to identify the structural factors that affect osteoclast formation and its function. Furthermore, we hypothesized that the type of osteoclast precursor cells also affects osteoclastogenesis in the materials. In this study, we investigated the effects of defined micro/nanoscale patterns on osteoclastogenesis from bone marrow cells (BMCs).MethodsVarious cyclo-olefin polymer (COP) patterns were prepared using nanoimprinting. The effects of shape, size, and height of the patterns, and the wettability of the patterned surfaces on osteoclastogenesis from BMCs were evaluated in vitro.ResultsOsteoclast formation was promoted on pillars (diameter, 1 μm or 500 nm; height, 500 nm). Notably, osteoclastogenesis from BMCs was better promoted on hydrophobic pillars than on hydrophilic pillars. In contrast, decreased osteoclast formation was observed on the nanopillars (diameter, 100 nm; height, 200 nm).ConclusionsWe demonstrated the promotion of osteoclast formation from BMCs on hydrophobic pillars with diameters of 1 μm and 500 nm. Some cellular behaviors in the patterns were dependent on the type of osteoclast precursor cells. The designed patterns are useful for designing the surface of dental implants or bone replacement materials with a controllable balance between osteoblast and osteoclast activities.     

Clinical predictors of persistent temporomandibular disorder in people with first-onset temporomandibular disorder: A prospective case-control study

BackgroundWhen patients first develop a painful temporomandibular disorder (TMD) and seek care, 1 priority for clinicians is to assess prognosis. The authors aimed to develop a predictive model by using biopsychosocial measures from the Diagnostic Criteria for Temporomandibular Disorders (DC-TMD) to predict risk of developing TMD symptom persistence.MethodsAt baseline, trained examiners identified 260 participants with first-onset TMD classified by using DC-TMD–compliant protocols. After follow-up at least 6 months later, 72 (49%) had examiner-classified TMD (persistent cases), and 75 (51%) no longer had examiner-classified TMD (transient cases). For multivariable logistic regression analysis, the authors used blocks of variables selected using minimum redundancy maximum relevance to construct a model to predict the odds of TMD persistence.ResultsAt onset, persistent cases had multiple worse TMD clinical measures and, among Axis II measures, only greater baseline pain intensity (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.04 to 2.2; P = .030) and more physical symptoms (OR, 1.8; 95% CI, 1.2 to 2.9; P = .004) than did transient cases. A multivariable model using TMD clinical measures showed greater discriminative capacity (area under the receiver operating characteristic curve, 0.74; 95% CI, 0.73 to 0.75) than did a model involving psychosocial measures (area under the receiver operating characteristic curve, 0.63; 95% CI, 0.62 to 0.64).ConclusionsClinical measures that clinicians can assess readily when TMD first develops are useful in predicting the risk of developing persistent TMD. Psychosocial measures are important predictors of onset but do not add meaningfully to the predictive capacity of clinical measures.Practical ImplicationsWhen TMD first develops, clinicians usefully can identify patients at higher risk of developing persistence by using clinical measures that they logically also could use in treatment planning and for monitoring outcomes of intervention.     

Oromandibular dystonia and temporomandibular disorders

BackgroundThe aim of this study was to characterize clinical features of patients with oromandibular dystonia (OMD) who had temporomandibular disorder (TMD) symptoms.MethodsA retrospective chart review of patients seeking treatment at a tertiary-level orofacial pain clinic from January 2015 through December 2020 was undertaken. The inclusionary criteria consisted of a diagnosis of OMD (International Classification of Diseases, Revision 10 code G24.4), which had been confirmed by a neurologist.ResultsEleven patients met the inclusion criteria. Focal dystonia and jaw deviation OMD were the most frequent diagnoses. A dental procedure was a triggering or aggravating factor in 36.4% of patients. All but 2 patients had a sensory trick, or tactile stimulus to a particular body part, and approximately one-half of the patients used an oral appliance as a sensory trick device. All but 1 patient had received a diagnosis of TMD, with myofascial pain of the masticatory muscles being the most prevalent diagnosis. Four patients had received a recommendation for orthodontic treatment. About one-half of the patients had undergone 1 or more invasive dental or maxillofacial surgical interventions to address their dystonia. Anxiety was the most common psychological comorbidity.ConclusionsBecause patients with OMD commonly experience TMD symptoms, they can receive a misdiagnosis of TMD while the OMD is overlooked.Practical ImplicationsOwing to concomitant TMD symptoms, patients most often seek dental consultations and undergo treatments such as orthodontic interventions and temporomandibular joint surgeries. A dentist’s competency in recognizing these patients can prevent unnecessary procedures and facilitate appropriate patient care.     

Association between primary headaches and temporomandibular disorders: A systematic review and meta-analysis

BackgroundThe primary objective of this systematic review was to answer the following question systematically: Is there any association between primary headaches (PHs) and temporomandibular disorders (TMDs) in adults?Types of Studies ReviewedThe protocol was registered with the International Prospective Register of Systematic Reviews. The authors performed the search in 6 main databases and 3 gray literature sources. The included articles had to have adult samples. PHs must have been diagnosed using the International Classification of Headache Disorders, and TMDs must have been diagnosed using Research Diagnostic Criteria for Temporomandibular Disorders, Diagnostic Criteria for Temporomandibular Disorders, or International Classification of Orofacial Pain. Risk of bias was evaluated using the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument tools. The meta-analysis was performed using Review Manager software, Version 5.4. Certainty of evidence was screened according to Grading of Recommendations Assessment, Development and Evaluation.ResultsNine of 2,574 articles reviewed met the inclusion criteria for qualitative analysis and, of these, 7 met the inclusion criteria for quantitative analysis. Odds ratios (ORs) for painful TMD and tension-type headache (OR, 1.94 [95% CI, 0.56 to 6.76] to OR, 7.61 [95% CI, 1.84 to 31.48]), migraines (OR, 4.14 [95% CI, 1.38 to 12.43] to OR, 5.44 [95% CI, 3.61 to 8.21]), and chronic headaches (OR, 40.40 [95% CI, 8.67 to 188.15] to OR, 95.93 [95% CI, 12.53 to 734.27]) were calculated. Articular TMDs without pain were evaluated in 2 articles, and both did not show positive association with tension-type headache nor migraine. Three studies were classified as moderate risk of bias and 6 as low risk of bias. The certainty of evidence varied between very low and low.Conclusions and Practical ImplicationsRecognizing the positive association between painful TMD and PHs can help dentists and physicians treat the pain and avoid it, or recommend the patient to a specialist.     

Management of painful temporomandibular disorders: Methods and overview of The National Dental Practice-Based Research Network prospective cohort study

BackgroundPatients often seek consultation with dentists for temporomandibular disorders (TMDs). The objectives of this article were to describe the methods of a large prospective cohort study of painful TMD management, practitioners’ and patients’ characteristics, and practitioners’ initial treatment recommendations conducted by The National Dental Practice-Based Research Network (the “network”).MethodsParticipating dentists recruited into this study treated patients seeking treatment for painful TMDs. The authors developed self-report instruments based on well-accepted instruments. The authors collected demographics, biopsychosocial characteristics, TMD symptoms, diagnoses, treatments, treatment adherence, and painful TMDs and jaw function outcomes through 6 months.ResultsParticipating dentists were predominately White (76.8%) and male (62.2%), had a mean age of 52 years, and were general practitioners (73.5%) with 23.8% having completed an orofacial pain residency. Of the 1,901 patients with painful TMDs recruited, the predominant demographics were White (84.3%) and female (83.3%). Patients’ mean age was 44 years, 88.8% self-reported good to excellent health, and 85.9% had education beyond high school. Eighty-two percent had pain or stiffness of the jaw on awakening, and 40.3% had low-intensity pain. The most frequent diagnoses were myalgia (72.4%) and headache attributed to TMDs (51.0%). Self-care instruction (89.4%), intraoral appliances (75.4%), and medications (57.6%) were recommended frequently.ConclusionsThe characteristics of this TMD cohort include those typical of US patients with painful TMDs. Network practitioners typically managed TMDs using conservative treatments.Practical ImplicationsThis study provides credible data regarding painful TMDs and TMD management provided by network practitioners across the United States. Knowledge acquired of treatment recommendations and patient reports may support future research and improve dental school curricula.     

Oral health–related quality of life of patients with acute and chronic temporomandibular disorder diagnostic subtypes

BackgroundStudies have indicated the negative effects of temporomandibular disorders (TMDs) on oral health–related quality of life (OHRQoL). The authors investigated the OHRQoL of patients with acute and chronic TMD subtypes.MethodsThe authors recruited a total of 830 patients. They derived TMD diagnoses using the Diagnostic Criteria for TMDs protocol involving symptom history, physical examination, and diagnostic imaging as indicated. The authors categorized patients into acute (≤ 3 months) or chronic (> 3 months) pain-related TMD (PT), nonpainful intra-articular TMD (IT), and combined TMD (CT) groups. They also gathered sociodemographic information and assessed OHRQoL with the Oral Health Impact Profile (OHIP)-TMDs. The authors evaluated data using 2-way analysis of variance and Bonferroni test and multiple regression analysis.ResultsPatients in the chronic PT and CT subgroups had significantly higher mean global OHIP scores than their acute counterparts. The authors observed significant acute-chronic differences in OHIP-TMDs domain scores in 5 and 2 domains for the PT and CT groups, respectively. Patients in the acute IT group had significantly higher functional limitation scores than those in the chronic IT group. The ranking of mean global scores, in descending order was CT, PT, and IT for acute TMDs and PT, CT, and IT for chronic TMDs, with significant differences observed among the 3 TMD subtypes (P < .001).ConclusionsBoth TMD chronicity and subtypes influenced OHRQoL. Painful TMDs (PT and CT) were associated with significantly poorer OHRQoL than nonpainful TMDs. TMD chronicity appeared to affect OHRQoL only for the painful TMD conditions. Future work on the impact of TMDs on OHRQoL should strive to stratify patients by TMD chronicity and subtypes.Practical ImplicationsTMD chronicity and subtypes influence the impact of TMDs on OHRQoL. Given that chronic painful TMDs impair quality of life, early biopsychosocial intervention of acute TMD pain is important for minimizing chronification and OHRQoL deterioration.     

A Ser252Trp substitution in mouse FGFR2 results in hyperplasia of embryonic salivary gland parenchyma

ObjectivesMutations in the fibroblast growth factor receptor 2 (FGFR2) gene are responsible for several severe forms of craniosynostotic disorders, such as Apert and Crouzon syndromes. Patients with craniosynostotic disorders caused by a mutation in Fgfr2 present with several clinical symptoms, including hypersalivation. Here we used a transgenic mouse model of Apert syndrome (Fgfr2^+/S252W mice) to evaluate the morphology of the submandibular glands at embryonic day 15.5 (E15.5), the time point reported to mark the start of lumen formation.MethodsFgfr2^+/S252W mice were generated by crossing ACTB-Cre^+/+ and Fgfr2^+/Neo-S252W mice. After measuring body weight, the submandibular glands were collected at E15.5. H&E staining, immunostaining, and RT-qPCR were performed to investigate the development of the submandibular gland.ResultsThe number of ducts and acini in Fgfr2^+/S252W mice was significantly higher than in control littermates; however, lumen formation was not affected. The mRNA expression of Fgf1, Fgfr1, Mmp2, Bmp4, Bmp7, Dusp6, and Etv5 in Fgfr2^+/S252W mice was significantly higher compared to control littermates. Immunoreactivity for FGF3, FGF1, BMP4, and F4/80 was detected in the parenchyma of Fgfr2^+/S252W mice. The area of apoptotic cells stained with TUNEL in Fgfr2^+/S252W mice was significantly larger than that of the control littermates.ConclusionsThese results suggested that increased FGFR1 signaling and apoptosis in the submandibular glands of Fgfr2^+/S252W mice occurred at E15.5, leading to parenchymal hyperplasia. This study demonstrated that a Ser252Trp substitution in mouse FGFR2 resulted in hyperplasia of the submandibular gland parenchyma during development.     

The prevalence of comorbid chronic pain conditions among patients with temporomandibular disorders: A systematic review

BackgroundThis systematic review was designed to evaluate the presence of comorbid conditions among patients with temporomandibular disorders (TMDs).Types of Studies ReviewedThe authors reviewed studies that reported the prevalence or incidence of chronic pain conditions or psychiatric disorders (anxiety, mood, personality disorders) among patients with any type of TMD. The authors calculated sample size–weighted prevalence estimates when data were reported in 2 or more studies for the same comorbid condition.ResultsA total of 9 prevalence studies and no incidence studies were eligible for review; 8 of the studies examined chronic pain comorbidities. Weighted estimates showed high prevalence of pain comorbidities across studies, including current chronic back pain (66%), myofascial syndrome (50%), chronic stomach pain (50%), chronic migraine headache (40%), irritable bowel syndrome (19%), and fibromyalgia (14%). A single study examined psychiatric disorders and found that current depression was the most prevalent disorder identified (17.5%).Conclusions and Practical ImplicationsThere is a high prevalence of comorbid chronic pain conditions among patients with TMDs, with more than 50% of patients reporting chronic back pain, myofascial syndrome, and chronic stomach pain. Psychiatric disorders among patients with different types of TMDs were studied less commonly in this pain population. Knowledge of the distribution of these and other comorbid disease conditions among patients with different types of TMDs can help dentists and other health care providers to identify personalized treatment strategies, including the coordination of care across medical specialties.     

Three-dimensional cellular visualization in mouse apical periodontitis using combined whole-mount staining and optical tissue clearing

Apical periodontitis is an inflammatory disease involving lesions located within the jawbone. Histological evaluations generally require decalcification and sectioning, which has limited our understanding of the three-dimensional (3D) organization and spatial distribution of different immune cell types in these lesions. A recently developed technique combining tissue clearing and whole-mount immunofluorescent labeling allows us to acquire such information from the deep tissue without sectioning. However, whole-mount immunofluorescent labeling in the jawbone requires further development. Here we provide a straightforward and efficient protocol to achieve 3D immunofluorescent imaging of murine periapical lesions.     

Occlusal splints-types and effectiveness in temporomandibular disorder management

BackgroundOcclusal splints are routinely used in dental offices to diagnose and treat abnormalities of the masticatory system. There are different occlusal splints, each of which can address various conditions. They may treat individuals with temporomandibular disorders (TMDs) and bruxism or be used for occlusal stabilization and dentition wear reduction.MethodsThe literature in the National Library of Medicine's Medline Database was reviewed using the Mesh terms 'occlusal splints' AND 'Temporomandibular Disorders.ConclusionOcclusal splints can treat a wide variety of TMDs. They can treat bruxism, headaches, postural imbalances related to TMDs, and decreased vertical dimension of occlusion (VDO). However, there is no clear evidence that occlusal splints are superior to physiotherapy in treating TMDs. In the long-term follow-up, they were equally effective as other therapies.     

Effect of Myd88 deficiency on gene expression profiling in salivary glands of female non-obese diabetic (NOD) mice

ObjectivesSjögren's syndrome (SS) is a chronic autoimmune disease characterized by inflammatory lesions in the salivary and lacrimal glands, which are caused by distinct lymphocytic infiltrates. Female non-obese diabetic (NOD) mice spontaneously develop inflammatory lesions of the salivary glands with SS-like pathological features. Previous studies have shown that MyD88, a crucial adaptor protein that activates innate immune signaling, affects lymphocytic infiltration, but its detailed role remains unclear. In this study, we investigated the role of MyD88 through gene expression profiling in the early phase of pathogenesis in the salivary glands of female NOD mice.MethodsSubmandibular glands collected from 10-week-old female wild-type and Myd88-deficient NOD mice were used for RNA preparation, followed by microarray analysis. The microarray dataset was analyzed to identify Myd88-dependent differentially expressed genes (DEGs). Data generated were used for GO enrichment, KEGG pathway, STRING database, and INTERFEROME database analyses.ResultsMyd88 deficiency was found to affect 230 DEGs, including SS-associated genes, such as Cxcl9 and Bpifa2. Most of the DEGs were identified as being involved in immunological processes. KEGG pathway analysis indicated that the DEGs were putatively involved in autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. Furthermore, the DEGs included 149 interferon (IFN)-regulated genes.ConclusionsMyD88 is involved in the expression of specific genes associated with IFN-associated immunopathological processes in the salivary glands of NOD mice. Our findings are important for understanding the role of MyD88-dependent innate immune signaling in SS manifestation.