OBI 814 - RD1 - Exam2

• Changes in systemic physiology have direct correlation to oral health
• Reproduction and development are key components in physiology

Reproduction and Development Topics

• Men's health: Hypogonadism, anabolic steroids (AAS), ED, & Andropause
• Women's Health: Menstrual Cycle, Oral Contraceptives and STDs, & Menopause
• Pregnancy Hormones, Morning-sickness, Gestational Diabetes, & Supine Hypotension
• Fetal Development and Teratogens & Sex Differentiation and Intersex
• Dentition & Neonatal and Childhood Oral Function Development
• Puberty and Skeletal Maturation Indicators & Aging Changes in Oral Tissues

Human Life Cycle

• Fertilization leads to a zygote, then an embryo and finally a fetus

Sex Steroid Hormones

• Sex Steroid Hormones directly impact the reproduction & development during the human life cycle
• These hormones are active from birth to growth and then to puberty through the reproductively active period and finally aging

Hormones and Periodontal Status

• Sex steroid hormones impact periodontal status by modifying oral microbiota and the immune system
• Gums, periodontal ligaments, cementum, and alveolar bone are impacted by these hormones

Gamete Production and Genetics of Embryo

• Mitosis: 1 diploid parent cell (2n) creates 2 diploid daughter cells (2n)
• Sister chromatids are separated into 1 daughter cells
• Mitosis occurs in somatic (non-germ) cells during duplication
• Meiosis: 1 diploid parent cell (2n) creates 4 haploid daughter cells (n)
• Meiosis is a cellular process used by germ cells for gametogenesis
• Meiosis 1 has homologous chromosomes are separated into daughter cells
• Meiosis 2 has sister chromatids separated into daughter cells

Chromosomes

• Haploid is one chromosome set (n), which is 23
• Diploid is 2 chromosome sets (2n) which is 46
• Triploid is 3 sets of chromosomes (3n), which is 69
• Aneuploidy is when there are fewer or more chromosomes in an individual
• Aneuploidy happens when one or more chromosomes fail to disjunct during cell division
• Monosomy is (2n-1), with 45 chromosomes
• Trisomy is (2n+1), with 47 chromosomes

Aneuploidy Example 1: Turner Syndrome

• In monosomy XO oral manifestations include variation in tooth eruption
• Permanent dentition often erupts 12 months earlier than normal
• Smaller primary and permanent teeth can occur
• Mandibular first and second premolars can have two roots
• Abnormal teeth include changes in crown and root development as well as thinner enamel and abnormal dentin
• Abnormal palatal and gingival indices lead to higher than normal tooth mobility
• Recessed and small mandible is present, with distal molar occlusion, cross-bite, over-bite
• Increased risk for root absorption or tooth loss

Aneuploidy Example 2: Klinefelter Syndrome

• In Trisomy XXY (47) oral manifestations include a tendency toward mandibular prognathism and decreased facial height
• Higher rates of caries and periodontal disease
• Taurodontism occurs with an increased apico-occlusal dimension of the pulp chamber, accompanied by an alteration in the external root configuration

Aneuploidy Example 3: Down Syndrome

• In Trisomy 21 (47) oral manifestations Delayed eruption, Small maxilla leading to crowding and impaction, Small and missing teeth, Large wrinkled tongue

Hormonal and Genetic Factors Impacting Oral Health

• Sex steroid hormones can alter blood supply, bone health, & oral microbes
• Sex Steroids cause changes in the oral microbiome and can alter bacterial growth
• Sex Steroids affect bone formation and resorption

Sexual Dimorphism

• Young adult women are more susceptible to conditions like gingivitis whereas Older men are more susceptible to periodontitis

Plasma Testosterone and Gonadotropins

• Testosterone, IB, FSH, and LH fluctuate as men age from 3 years old uptown 80 years of age

Hypothalamic-Pituitary-Testis Axis

• GnRH stimulates the anterior pituitary to secrete FSH and LH to the tests
• FSH stimulates the sertoli cells where LH stimulates the Leydig cells
• Testosterone inhibits GnRH & LH release (inhibits indirectly FSH) and stimulates spermatogenesis

Androgens and Their Function

• Androgens in XY male's blood include with the following ratios: Testosterone from testes > androstenedione
• The potency of androgens is ranked in the following order: DHT > Testosterone >> androstenedione > DHEA

Testosterone

• Testosterone(T) functions directly or indirectly as a metabolite
• T activates AR
• T→ estradiol (aromatase) and estradiol activates ER
• T → DHT (5a-reducatase) and DHT activates AR

Functions of Androgens

• In utero, growth & development of the sex organs is caused by T or DHT
• T causes voice deepening (laryngeal growth), stimulates libido(sex drive) and spermatogenesis
• DHT induces growth of pubic, axillary and facial hair
• E results in growth of long bones and fusion of epiphyseal plates
• Increased muscle bulk is attributed to T, T induces cardiovascular effects

Testosterone is needed for Spermatogenesis

• Males are born with spermatogonia (2n, precursor cells for sperm) in testes
• During puberty, testes and genitalia grow and go through spermatogenesis in seminiferous tubules of testes
• Spermatogenesis requires high T (LH stimulated T secretion from Leydig cells) and functioning Sertoli cells
• FSH stimulated production of androgen-binding protein

Heat Effects

• Spermatogenesis is sensitive to heat; therefore, testes are located in the scrotum.

Lean Muscle Growth

• Testosterone Stimulates Lean Muscle Growth & Muscle Function by inducing proliferation and differentiation

DHT Conversion

• Testosterone Is Converted to DHT in Gingival Fibroblast which can lead to Proinflammatory cytokines and finally Inflammation

Androgen Deficiency Causes

• Primary Hypogonadism is due to Klinefelter Syndrome, XXY

Andropause

• Andropause is characterized by Deficiency in sexual function, with low libido, fewer spontaneous erections, and infertility
• Insomnia or other sleep disturbances, Increased body fat, Reduced muscle mass and strength, Decreased bone density symptoms also appear

Erectile Disfunction

• Erectile Dysfunction is Associated with Hypogonadism/Low T and is recognized as an Early Sign of Cardiovascular Dysfunction
• The Erectile Reflex is controlled by the parasympathetic pathway
• Viagra (Sildenafil), a PDE5 inhibitor, is a common choice of drug for ED

Viagra and the heart

• Chest pain in patients taking Viagra must not be treated with nitrates, as nitroglycerin because they together can cause severe low blood pressure leading to a heart attack and cardiac arrest
• The concomitant use of Viagra and organic nitrates (vasodilating effects) can lead to drops in systemic blood pressure which could result in myocardial infarction and cardiac arrest

Androgenic Anabolic Steroids

• Androgenic Anabolic Steroids (AAS) are synthetic medications which mimic endogenous testosterone and activate androgen receptors (ARs)
• AAS are often misused or abused for building lean muscle mass, but can be prescribed to treat male hypogonadism and certain types of breast cancer

Effects of AAS

• Increased muscle mass, athletic performance, & libido, and Acne are possible. The latter can be associated with aggression
• AAS Can potentially decrease LH & GnRH levels; this in turn also decreases FSH levels, Endogenous T secretion and even Spermatogensis
• Testicular hypertrophy or atrophy has been recorded. Side effects are common

Side Effects of AAS

• These can include Hirsutism in females, Acne, Cutaneous striae,Hypertension
• Side effects also include Irritable/aggressive behavior, gingival hyperplasia, Gynecomastia and Testicular atrophy

Anabolic Steroids

• Gingival Hyperplasia with Abuse of Anabolic Androgenic Steroids (AAS) can occur with enlarged gums
• This happens when gums make it easier for bacteria that is found in plaque to accumulate and attack supporting structures of the teeth, potentially leading to periodontal infection.

Explore the intricate relationship between systemic physiology and oral health, focusing on reproduction and development. Covering men's and women's health issues, pregnancy, fetal development, and the impact of sex steroid hormones. Also includes the stages of the human life cycle.