Association of climacterium with temporomandibular disorders at the age of 46 years - a cross-sectional study.

OBJECTIVE: Hormonal factors have been suggested to contribute to female dominance among subjects with temporomandibular disorders (TMD). Aim of the study was to examine the association of climacteric status with TMD amongst female participants in the Northern Finland Birth Cohort (NFBC) 1966 at 46 years of age. MATERIAL AND METHODS: Among female subjects in NFBC1966, climacteric status was determined based on menstrual anamnesis and measurement of blood follicle-stimulating hormone (FSH) levels. Women with FSH > 25 IU/L and amenorrhoea > 4 months were defined as climacteric (case group, n = 71); women not diagnosed as climacteric were defined as preclimacteric (control group, n = 656). Differences between cases and controls were evaluated on self-reported TMD pain, clinical TMD signs and TMD diagnoses using modified Diagnostic Criteria for TMD (DC/TMD) protocol. Crosstabulation and logistic regression models were used to analyse differences between cases and controls. RESULTS: Compared to preclimacteric women, climacteric women had significantly more often pain on palpation in temporomandibular joints (TMJs) (OR = 2.64, 95% CI 1.12-6.21, p= .026) and more crepitus in TMJs (OR = 2.92, 95% CI 1.13-7.56, p= .027). Degenerative joint disease diagnoses were more common in climacteric than preclimacteric women (OR = 2.27, 95% CI 1.05-4.91, p= .037). Differences were statistically significant after adjusting for confounding factors (body mass index (BMI), smoking, parity). No statistically significant differences in self-reported TMD pain were noted between groups. CONCLUSION: Among females at the age of 46 years, climacterium seems associated with TMD by increasing pain on palpation in TMJs, subjective symptoms, and clinical signs indicating degenerative changes in TMJs when using DC/TMD.

Effects of Estrogen Level, Dietary Loading, and Aging on Types I, II, and X Collagen Expression and Structure of Rat Mandibular Condylar Cartilage.

AIMS: To investigate how estrogen level, dietary loading, and aging affect cartilage structure and the expression of major collagens (types I, II, and X) in rat mandibular condylar cartilage (MCC). METHODS: A total of 96 outbred Sprague Dawley female rats were randomly divided into two groups by ovariectomy (OVX) at 7 weeks old. One week later, the rats in each group were further divided into three subgroups on the basis of food hardness: hard food (diet board), normal food (pellet), and soft food (powder). The rats were sacrificed at the age of 5 or 14 months. The thickness of the fibrous, proliferative, and chondroblastic layers of the mandibular condylar cartilage were measured after toluidine blue staining. Immunohistochemical analysis was performed to evaluate the expression levels of types I, II, and X collagen. A linear regression model was used to investigate the main factors affecting changes in thickness and collagen expression. RESULTS: The expression levels of types II and X collagen were decreased by ovarian estrogen deficiency and increased by dietary loading. Increased dietary loading was the main factor affecting an increase in thickness of the cartilage layers, while aging was the main factor affecting a decrease in thickness of the fibrous layer. A significant age-related increase was found in the expression of type I collagen. There was some degree of interaction between aging and dietary loading that affected the thickness of the chondroblastic layer and the expression of type X collagen. CONCLUSION: The physiologic level of estrogen plays a role in MCC development by promoting the expression of types II and X collagen. Dietary loading is essential to increase the expression of types II and X collagen, as well as the thickness of cellular layers, to maintain the integrity of the MCC. Aging seems to reduce the ability of the MCC to withstand occlusal loading.

MMP-3 and MMP-8 in rat mandibular condylar cartilage associated with dietary loading, estrogen level, and aging.

OBJECTIVES: The structure of the mandibular condylar cartilage (MCC) is regulated by dynamic and multifactorial processes. The aim of this study was to examine the effects of altered dietary loading, estrogen level, and aging on the structure of the condylar cartilage and the expressions of matrix metalloproteinase (MMP) -3 and MMP-8 of rat MCC. METHODS: In this study, Crl:CD (SD) female rats were randomly divided into 3 groups according to dietary hardness: hard diet (diet board), normal diet (pellet), and soft diet (powder). In each group, the rats were further divided into 2 subgroups by ovariectomy at the age of 7 weeks. The rats were sacrificed at 5- and 14-month-old. Histomorphometric analysis of the MCC thickness was performed after toluidine blue staining. Immunochemical staining was done for MMP-3 and MMP-8. A linear mixed model was used to assess the effects of dietary loading, estrogen level, and aging. RESULTS: Increased dietary loading was the main factor to increase the MMP-3 expression and the anterior and central thickness of the MCC. Lack of estrogen was the main factor associated with decreased MMP-8. Aging was associated with the thickness changes of the whole condylar cartilage and the reduced expression of MMP-8. CONCLUSION: The condylar cartilage structure and metabolism of the female rats are sensitive to dietary loading changes, estrogen level as well as aging. The proper balance of these factors seems to be essential for the maintenance of the condylar cartilage.

Changes in Type I and Type II Collagen Expression in Rat Mandibular Condylar Cartilage Associated with Aging and Dietary Loading.

AIMS: To evaluate the usefulness of diet board feeding as a model for temporomandibular joint (TMJ) research, characterize dietary loading-related morphometric changes in the mandibular condylar cartilage of aging rats, and investigate changes in type I and type II collagen expression in different age, sex, and diet groups. METHODS: Material was collected from a study that examined the effects of 1-year and 2-year diet board feeding on rats. In diet board feeding, rats must gnaw wood to reach their food, leading to a higher masticatory workload. The material analyzed was comprised of 150 TMJ samples from 75 Hsd:Sprague Dawley rats grouped according to feeding method (diet board [experimental group] or ad libitum [control group]), sex, and experiment length (1 or 2 years). The rats were sacrificed at the age of 15 or 26 months (15-M rats or 26-M rats). From the TMJ samples, 5-µm-thick sections were cut parallel to the sagittal plane of the mandibular condyle. Histomorphometric analysis of the thickness of the condylar cartilage and the number of cartilage cells was performed after toluidine blue staining. Immunohistochemical staining included type I and type II collagen antigens. Differences in the thickness of the cellular layer and the number of cells in the condylar cartilage were analyzed by means of a repeated-measures analysis of variance (ANOVA) model, and differences in the type of collagen with a one-way random-effects ANOVA model. RESULTS: Condylar cartilage was significantly thicker in the 15-M diet board-fed rats than in the 15-M control rats and in the 26-M rats than in the 15-M rats. The number of cells was larger in the 26-M female rats than in the 26-M male rats. Type I collagen expression was significantly higher in the 15-M diet board-fed female rats than in the 15-M controls. Type II collagen showed increased expression in older rats compared to younger rats. CONCLUSION: Condylar cartilage is sensitive to the interplay between loading, aging, and sex of middle-aged and older rats. High loading of condylar cartilage increased the thickness of cartilage in younger rats.