OBI 814 - RD1 - Exam2

• Changes in systemic physiology can affect oral health.
• Reproduction and development involve physiology and pathophysiology.
• Key topics include men's and women's health, pregnancy, fetal development, and changes during puberty and aging.
• The human life cycle spans from fertilization to aging.
• Sex steroid hormones play critical roles in reproduction and development.
• Interactions between genes and the in-utero environment impact embryo health and can lead to oral manifestations.
• Changes in sex steroid hormones can alter periodontal status by modifying both oral microbiota and the immune system.
• Multiple hormones influence periodontal homeostasis, with effects varying by hormone type and concentration.

Gamete Production and Genetics

• Mitosis creates two diploid daughter cells from one diploid parent cell, separating sister chromatids, and is used by somatic cells during duplication.
• Meiosis creates 4 haploid daughter cells from one diploid parent cell, and is a cellular process used by germ cells for gametogenesis.
• Meiosis has meiosis 1 during which homologous chromosomes separate, and meiosis 2 during which sister chromatids separate.

Aneuploidy and Chromosomal Abnormalities

• Aneuploidy happens when there are not the normal amount of chromosomes in individuals due to chromosomes failing to separate during cell division.
• Monosomy involves one less chromosome (2n-1), resulting in 45 chromosomes.
• Trisomy involves one extra chromosome (2n+1), resulting in 47 chromosomes.
• Trisomy 21 (Down syndrome) affects 1 in 800 births.
• Trisomy 18 (Edwards syndrome) affects 1 in 6,000 births.
• Trisomy 13 (Patau syndrome) affects 1 in 10,000 births.
• Trisomy of sex chromosomes XXY (Klinefelter syndrome) affects 1 in 500 births.
• Monosomy of a sex chromosome XO (Turner syndrome) affects 1 in 2,500 births.

Turner Syndrome (Monosomy XO)

• Oral manifestations include early tooth eruption, smaller teeth, abnormal tooth development like thinner enamel, and higher tooth mobility.
• Individuals may have a recessed, small mandible and increased risk for root absorption or tooth loss.

Klinefelter Syndrome (Trisomy XXY)

• Oral manifestations include a tendency toward mandibular prognathism and decreased facial height.
• Individual has an increased risk of caries and periodontal disease
• Taurodontism, which is an increase in the apico-occlusal dimension of the pulp chamber, may occur.

Down Syndrome (Trisomy 21)

• Oral manifestations include delayed eruption, a small maxilla leading to crowding, small and missing teeth, and a large, wrinkled tongue.

Hormonal and Genetic Effects on Oral Health

• Sex steroid hormones, such as estrogen, progesterone, and testosterone, can alter blood supply, bone health, and oral microbes.
• Steroids can cause changes in the oral microbiome, affecting bacterial growth.
• Sex steroids affect bone formation and resorption.
• The body's blood supply must remain at a normal level for the cells of gums, teeth, and bones.
• Saliva contains hormones, which affect the oral microbiome which affects the gum epithelia.

Sexual Dimorphism & Periodontal Diseases

• Young adult women are more susceptible to gingivitis.
• Older men are more susceptible to periodontitis.

Plasma Testosterone and Gonadotropins

• Plasma testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels in XY males change throughout their life.
• This includes changes from childhood, through puberty, to adulthood.

Hypothalamic-Pituitary-Testis Axis

• Luteinizing hormone (LH) stimulates testosterone (T) production from Leydig cells.
• Testosterone inhibits GnRH and LH release, stimulates spermatogenesis, and inhibits FSH indirectly.
• Follicle-stimulating hormone (FSH) stimulates inhibin and androgen-binding protein (ABP) production from Sertoli cells which then stimulates spermatogenesis.

Androgens and Their Function

• Androgens in XY males' blood include testosterone and androstenedione.
• Dihydrotestosterone (DHT) has greater potency than testosterone.
• Testosterone functions directly or indirectly via metabolites.
• Testosterone activates androgen receptors (AR).
• It can also be converted to estradiol by aromatase, which then activates estrogen receptors (ER).
• Lastly it can be converted into DHT (5a-reducatase), which also activates AR.

Androgen Functions in Males

• Androgens dictate the growth and development of sex organs in utero.
• Testosterone causes deepening of voice and stimulates libido and spermatogenesis.
• Testosterone opposes estrogen's effect on breast development.
• Androgens stimulate the growth of public and axillary hair, increase muscle bulk, and affect cardiovascular health by decreasing HDL and increasing LDL/RBC.

Spermatogenesis

• Spermatogenesis requires testosterone, which is when males are born with spermatogonia which are precursor cells that create sperm in testes.
• During puberty testes/genetalia grow causing spermatogenesis occurs.
• Spermatogenesis requires high testosterone levels and functioning Sertoli cells.
• Follicle-stimulating hormone (FSH) stimulates the production of androgen-binding protein.
• Spermatogenesis occurs in seminiferous tubules.
• Tight junctions between Sertoli cells create the blood-testis barrier in order to protect germ cells from harmful substances and immune cells.
• Spermatogenesis is heat-sensitive, since testes are located in the scrotum at 35C.

Testosterone/Muscle Growth

• Testosterone promotes lean muscle mass growth and function.

DHT in Gingival Fibroblasts

• Testosterone converts to DHT in gingival fibroblasts.
• This Conversion can lead to proinflammatory cytokines and inflammation.

Androgen Deficiency

• Primary hypogonadism, (ex. Klinefelter Syndrome) can cause androgen deficiency.
• Oral manifestations of Klinefelter include mandibular prognathism, caries, periodontal disease, and taurodontism.

Andropause

• Andropause refers to a period in a man's life where they experience deficiencies in sexual function, such as low libido.
• It can cause less spontaneous erections, infertility and insomnia.
• It also is marked by increased body fat and reduced muscle mass as well as decreased motivation.

Erectile Dysfunction

• Erectile dysfunction (ED) is associated with hypogonadism/low testosterone and is an early sign of cardiovascular dysfunction.
• The erectile reflex is controlled by the parasympathetic pathway.
• Nitric oxide (NO) is secreted to cause vasodilation.

Viagra (Sildenafil)

• Viagra (sildenafil) which is a PDE5 inhibitor, is a choice of drug for ED.
• There is a strong correlation between ED and periodontitis
• The medication should not be taken with nitrates.
• Using Viagra with organic nitrates can cause sudden drops in systemic blood pressure.

Androgenic Anabolic Steroids (AAS)

• Anabolic Steroids are synthetic medications which mimic endogenous testosterone
• Steroids activate androgen receptors (ARs).
• Used to treat male hypogonadism and certain types of breast cancer.
• Misused or abused for building lean muscle mass.

Anabolic Steroids

• Anabolic Steroids are synthetic androgens that activate ARs.
• Can increase muscle mass, athletic performance, and libido.
• Side effects include acne and aggression.
• Can cause decreased LH, GnRH, and FSH levels, plus decreased endogenous testosterone and spermatogenesis coupled with testicular hypertrophy or atrophy.

Adverse Effects of Anabolic Steroids

• Anabolic Steroids can cause hirsutism, acne, and cutaneous striae.
• Other effects include gingival hyperplasia, hypertension, gynecomastia, and testicular atrophy.

Gingival Hyperplasia

• Gingival Hyperplasia is when Statistically significant levels of gingival enlargement/hyperplasia compared to non-users.
• This condition makes it harder to clean plaque found in bacteria which attack what keeps the teeth in place.