OBI 814 - RD5 - Exam 2

• RD-5 is about dentition and neonatal/childhood oral function development.
• The study aims to cover neonatal adaptations, reflexes, oral microbiota acquisition, oral anomalies, oral function maturation, malocclusion, and speech acquisition timelines.

Neonatal Adaptations for Survival

• Neonates need to adapt to breathing for gas exchange outside the womb.
• First breath depends on internal chemical changes and external sensory stimuli.
• Internal stimuli include decreased oxygen, increased carbon dioxide, and decreased pH, which send messages to the respiratory center in the medulla..
• External stimuli include sensory, thermal, and mechanical changes triggering the respiratory center.
• Fetal lung fluid is cleared via surfactant secretion and pulmonary vasodilation for efficient gas exchange.
• The fetus has to rely on oxygen from lungs for gas exchange because it loses oxygen supply from the placenta.

Circulatory Transition at Birth

• The pressure is raised in the left atrium of the heart and lowers the pressure in the right atrium, the foramen ovale close.
• Changes occur at the heart-lung interface.
• Initial breaths expand the lungs, clearing fluid from the alveoli, and the ductus arteriosus closes.
• Ductus arteriosus connects the pulmonary artery to the aortic arch, diverting deoxygenated blood away from the lungs and becomes the ligamentum arteriosum.
• Oxygenated blood entering the right atrium is diverted into the left atrium and delivers oxygenated blood throughout the body via the fossa ovalis.
• Oxygenated blood returning from the placenta is shunted from the liver to the inferior vena cava becoming the ligamentum venosum.

Metabolic Adaptation

• Neonates needs nutrients from breast milk when the umbilical cord is clamped.
• Milk production depends on prolactin and milk ejection relies on oxytocin.
• The newborn depends on colostrum (initial milk) rich in proteins, vitamin A, and salts, along with carbohydrates, lipids, and antibodies.
• Full breastfeeding length is positively correlated with oral health.

Newborn Reflexes - Persistent Reflexes

• Newborn reflexes are autonomic involuntary motor/muscle responses controlled by the brain stem.
• Persistent reflexes include breathing, blinking, pupillary, sneeze, cough, gag, and swallowing reflexes.
• Infant’s anatomy differs in size, composition, position, and shape.
• Breathing reflex is essential; neonates are obligate nose breathers.
• Neonates have nasal breathing aided by short larynx that moves forward towards the epiglottis.

Swallowing reflex

• Tongue and pharyngeal muscles push bolus to back of mouth.
• Three phases: oral, pharyngeal, and esophageal.
• There’s a voluntary oral phase and involuntary pharyngeal/esophageal phases.

Newborn Reflexes- Primitive Reflexes

• Primitive reflexes are present at birth and disappear by 4-6 months.
• Brain maturation initiates voluntary motor activities; reflexes may persist in neurological diseases.
• Moro (startle) reflex occur during first 2 months.
• Tonic neck reflex (fencing position) lasts until 5-7 months.
• Grasp reflex (hand grasping) occurs for 6 months.
• Babinski reflex (toes crunching).
• Step reflex (walking/dancing reflex).
• Swim reflex lasts until 6 months.
• Crawl reflex.

Oro-Pharyngeal Reflexes

• Extrusion reflex prevents choking when solids are introduced.
• The tongue extends, and lips close so solid foods should not be introduced until the reflex has disappeared.
• The Newborn muscles are not developed to swallow anything other than liquids.
• Normally disappears by 4 months.
• Persistence beyond 4 months leads to tongue thrust habit, causing speech/dental issues.

Feeding Reflexes

• Rooting, suckling, and swallowing reflexes crucial for feeding.
• The first change in the oral area occurs at 60 days in utero development.
• Suckling develops at the 10th week and swallowing at the 12th week.
• Neonates are born with feeding reflexes requiring coordinated suck-swallow breath cycle.
• Rooting prompts the baby to turn towards touch around corner of mouth.
• Sucking occurs when something touches the palate.
• Swallowing occurs when mouth fills with milk/liquid.
• Mature swallowing reflex persists while infantile swallowing reflex disappears.

Sucking and Feeding Behavior

• The sucking system may not be functionally ready for preterm infants.
• Neonatal swallowing and breathing reflexes are coordinated.
• Infants breathe through the nose with a relaxed soft palate.
• During swallowing, that soft palate lifts and stretches to close off the nose.

Neonatal Oral Anomalies

• Oral cysts occur in newborns.
• Oral cysts are found in 65-85% of newborns; no intervention is necessary.
• Epstein pearls are benign whitish-yellow cysts on the roof of the mouth from epithelium entrapment; disappear within weeks.
• Bohn's nodules are keratin-filled cysts in the gingival region (buccal or lingual surface), or the hard palate away from the midline derived from minor salivary glands.
• Dental lamina cysts are benign oral mucosal lesions of transient nature of the dental lamina; on the gums and disappear in weeks or months.

Natal Teeth

• Natal teeth are uncommon but present at birth.
• Intervention is necessary: natal teeth need to be removed shortly after birth.
• Natal teeth often develop on the lower gum.
• Natal teeth that attached to the end of the gum by soft tissue are may cause a risk of “breathing in” the tooth.
• Natal causes irritation or injury to the tongue of the infant.
• Causes of natal teeth include Ellis van Creveld syndrome, Hallermann-Streiff syndrome, cleft palate, Pierre-Robin syndrome/sequence, Sotos syndrome.

Tongue-Tie (Ankyloglossia)

• A shortened, thickened, or wrongly placed frenulum (lingual frenulum) may restrict the tongue's movement.
• Tongue-tie could cause problems with breastfeeding and speech later in life.
• Intervention advised for with sterile scissors or laser.

Oral Microbiota

• Newborn's mouth is inhabited by microbes from mother's mucous membranes/urogenital system during childbirth.
• Early colonizers include streptococcus, staphylococcus, fusobacterium, veillonella, lactobacillus, and candidia.
• Adult/Primary Dentition consists of development of a specific set of microorganisms.
• Second colonizers appear around 3-6 months including gemella, granulicatella, haemophilus, and rothia.

Development of Taste

• Taste buds are present at birth and newborns can discriminate tastes.
• Neural connections to the brain are immature thus taste perception is not fully developed.
• Infants have acute sense of taste by 3 months.
• Taste buds are activated during the 30th week of gestation;
• Amnionic fluid influenced by the maternal diet stimulates fetal taste receptors.

Development of Salivary Function

• Salivary glands develop from ectodermal proliferations.
• Small amounts are produced by the newborn, increase at 3 months (before teething).
• Salivary glands at birth produces small amounts of saliva
• Lip closure matures which reduces drooling at about 2 years old
• Drooling is seen until the muscular reflexes mature and irritation can stimulate drooling

Growth of Mandible

• Mdndibular bone is formed by intramembranous ossification off the first pharyngeal arch at 6 weeks in utero.
• Growth is mediated by endochondral ossification of the condylar cartilage.
• Small mandible with short ramus.
• The mandibular fossa is flat and there is a low mandibular canal
• Growth is the most vertically in its first year.
• Growth continues during primary teeth appearance and replacement.

Maturation of Oral Functions -Swallowing-Breathing

• Size and shape of oral and pharyngeal structures change.
• Infant: Tongue filling oral cavity, high hyoid bone/larynx location decreases elevation during pharyngeal phase.
• Toddler: Adult-like phases with less larynx elevation and discrete swallow.
• Older Child: Mandible grows down/forward as intraoral space increases, and the tongue/palate space increases.
• The larynx and hyoid bone lower as that pharynx elongates/enlarges.

Acquisition of Speech:

• Sound is created by the vibration of the vocal cords.
• During speech, the soft palate lifts off from the mouth.
• Air passes through the voice box and lungs up through the windpipe .
• Speech acquisition is shaped into words by muscles controlling the soft palate, tongue, and lips.
• Bilabial (p, b, m, w) are formed by closure/near closure of lips at 2-3 years.
• Labial velar sound (q, we) via moving lips & air from back of mouth at 2-4 years.
• Velar sounds (k, g) - raising the back of the tongue and create quick air burst at the back of the mouth at 2.5-4 years.
  • There is no teeth involved

Maturation of Oral Functions - Dentition & Mastication

• Masticatory force increases with the second primary molar eruption.
• Biting force is further increased when the first permanent molars are occluded at 6 years.

Speech Acquisition

• Alveolar sounds (†)- tongue tapping inside of top teeth at 2.5-4
• Top teeth are being added now

Deciduous Teeth

• There’ll be a slight change from now

Speech Acquisition w/ teeth present:

• Speech occurs through the help of the teeth
• labial-dental sound (f) - formed via top teeth on top of the bottom lip at 3-4 years.
• Alveolar sounds- formed with tongue touching behind the top teeth : developed often at age of 3. 5-5 years.
• Alveolar sound (sh) emerge (spider, snake, slide, skip, swim and stop etc) at 4-6 years.
• Affricate sounds (ch and J) at 4.

The lesson covers neonatal adaptations and the development of oral function in neonates and children. It addresses the transition to breathing, reflexes, oral microbiota acquisition, and the maturation of oral functions. It also includes an overview of malocclusion and speech acquisition.