Impact of estrogen therapy on temporomandibular joints of rats: Histological and hormone analytical study

Association between Estrogen Levels and Temporomandibular Disorders: An Updated Systematic Review

The aim of this systematic review is to evaluate the impact of estrogen levels on the occurrence of temporomandibular disorders (TMDs) in humans. Searches were conducted in the same databases as follows: PubMed, the Cochrane Collaboration database, and the Scopus database. In accordance with the MeSH database and previous work, the following keywords were used: 'estrogens' and 'temporomandibular joint disorders'. Twelve studies were included in the review and were assessed for the quality of evidence. Estrogen levels are associated with pain modulation in the temporomandibular joint and the entire orofacial region. There is insufficient evidence to either confirm or refute the influence of estrogen on the occurrence of TMDs. The study was registered under the identifier: 10.17605/OSF.IO/BC7QF.

Causal Relationship Between Autoimmune Arthritis and Temporomandibular Disorders

OBJECTIVE

Accumulating evidence has indicated a close interrelation between autoimmune arthritis (AA) and temporomandibular disorders (TMD), but the causality is still unclear. The study aimed to explore the causal inference between AA and TMD using a bidirectional Mendelian randomization analysis.

METHODS

Online genome-wide association study data on rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis, and TMD were obtained from the FinnGen and IEU databases. Causality was using the inverse variance-weighted method as the primary analysis and supplemented by other methods. Sensitivity analyses, including heterogeneity tests, horizontal pleiotropy tests, and leave-one-out methods, were conducted to investigate the stability and reliability of the results.

RESULTS

The inverse variance-weighted test indicated that several AA types could causally increase the TMD risk, including overall RA (odds ratio [OR] = 1.348, 95% confidence interval [CI] = 1.1232-1.618, P = .001), subtype nRA (OR = 1.118, 95% CI = 1.044-1.197, P = .001), and AS (OR = 1.060, 95% CI = 1.024-1.097, P = .001). Moreover, the causal association of the above combinations has been proven to be stable and reliable using sensitivity and other tests.

CONCLUSION

These findings suggest that RA and AS might be causally associated with an increased risk of TMD. However, more studies are needed to check the causal effects of AA on TMD and analyse the potential mechanisms further.

Hormone replacement therapy did not alleviate temporomandibular joint inflammatory pain in ovariectomized rats

This study had the aim of examining the relationships between variations in estrogen levels resulting from ovariectomy, and estrogen hormone replacement therapy (HRT) in rats subjected to an orofacial inflammatory pain model. Eighty adult female Wistar rats were initially divided into 2 groups: Sham or ovariectomy (OVX-D1). Seven days later (D7), the rats were subjected to an unilateral infiltration of Freund's Complete Adjuvant (CFA) or saline solution into the right temporomandibular joint (TMJ). Then, rats received 17β-estradiol (28 µg/kg/day) or placebo for 21 days (D10-D31). Nociception was evaluated by the von Frey (VF) and the Hot Plate (HP) tests, and depressive-like behavior by the Forced Swimming (FS) test. On D32 all rats were euthanized and serum, hippocampus and brainstem were collected. The CFA groups presented a mechanical hyperalgesia until day 21 (p ≤ 0.05). No differences were observed among groups in the HP (p = 0.735), and in the immobility and swimming time of the FS (p = 0.800; p = 0.998, respectively). In the brainstem, there was a significant difference in the TNF-ɑ levels (p = 0.043), and a marginal significant difference in BDNF levels (p = 0.054), without differences among groups in the hippocampal BDNF and TNF-ɑ levels (p = 0.232; p = 0.081, respectively). In conclusion, the hormone replacement therapy did not alleviate orofacial pain in ovariectomized rats. However, there is a decrease in brainstem TNF-ɑ levels in the animals submitted to both models, which was partially reverted by HRT.

Low back pain and osteoarthritis pain: a perspective of estrogen

Low back pain (LBP) is the world's leading cause of disability and is increasing in prevalence more rapidly than any other pain condition. Intervertebral disc (IVD) degeneration and facet joint osteoarthritis (FJOA) are two common causes of LBP, and both occur more frequently in elderly women than in other populations. Moreover, osteoarthritis (OA) and OA pain, regardless of the joint, are experienced by up to twice as many women as men, and this difference is amplified during menopause. Changes in estrogen may be an important contributor to these pain states. Receptors for estrogen have been found within IVD tissue and nearby joints, highlighting the potential roles of estrogen within and surrounding the IVDs and joints. In addition, estrogen supplementation has been shown to be effective at ameliorating IVD degeneration and OA progression, indicating its potential use as a therapeutic agent for people with LBP and OA pain. This review comprehensively examines the relationship between estrogen and these pain conditions by summarizing recent preclinical and clinical findings. The potential molecular mechanisms by which estrogen may relieve LBP associated with IVD degeneration and FJOA and OA pain are discussed.

Analysis of mandible trabecular structure using digital periapical radiographs to assess low bone quality in postmenopausal women

PURPOSE

To analyze the quality of mandibular trabecular structure in postmenopausal women using periapical radiographs. Postmenopausal women are subjected to low bone quality; hence, early detection methods are needed. In addition to bone mineral density (BMD), trabecular architecture must be assessed to determine bone quality. The mandible represents bone quality and allows the assessment of trabecular structure from periapical radiographs.

MATERIAL AND METHODS

Lumbar (BMDL) and femoral BMD (BMDF) examinations were performed using dual-energy X-ray absorptiometry (DXA) in 31 postmenopausal women and divided into normal, osteopenia, and osteoporotic groups. Periapical radiographs were taken at both posterior sites of the mandible. The region of interest was taken 2 mm from the apical root of the first molar. Trabecular parameters consisting of trabecular thickness (Tb.Th) and bone percentage (BA/TA) were measured using BoneJ.

RESULTS

Both trabecular parameters were significantly correlated with BMDF [BA/TA ​​(r = 0.3796; p < 0.05) and Tb.Th (r = 0.508; p < 0.05)]. BA/TA and Tb.Th were significantly different between the osteoporosis and normal groups (p < 0.05) contrast to osteopenia and normal groups (p > 0.05).

CONCLUSION

Changes in mandibular trabeculae structure in postmenopausal women can be assessed using periapical radiographs.