Dental Anatomy and Natal Teeth Quiz

Introduction to Dental Occlusion

• Dental occlusion is the normal relationship of the occlusal planes of the teeth when the jaws are closed.
• Salzman defines occlusion as the changing interrelationship of opposing tooth surfaces during mandibular movements and the subsequent terminal contact.
• Wheeler defines occlusion as any functional contact of teeth from the maxillary and mandibular dental arches.
• Angle defines occlusion as the normal relation of the occlusal inclined planes of the teeth when the jaws are closed.

Periods of Occlusal Development

• Pre-Dental Period: Starts at birth and lasts for six months, encompassing the period before the first primary tooth erupts; typically marked by gums pads.
• Deciduous Dentition Period: Occurs from 6 months to 6 years and is marked by the eruption of primary teeth.
• Mixed Dentition Period: Extends from 6-12 years; a transitional period featuring both primary and permanent teeth.
• Permanent Dentition Period: begins when the permanent teeth replace the primary/deciduous teeth and continues till all teeth are fully erupted.

Andrews Six Keys to Occlusion

• Key 1: Class 1 molar relationship, wherein the buccal groove of the maxillary first molar sits in the mesiobuccal groove of the mandibular first molar.
• Key 2: Correct crown angulation: The facial axis of every clinical crown should be positive and the gingival portion must be distal compared to the incisal portion.
• Key 3: Correct crown inclination: The gingival portion of the upper incisors' crown should be lingual relative to the incisal portion; the labial/buccal portion should be labial or buccal to the incisal/occlusal portion in all other teeth.
• Key 4: No rotation: Teeth should be free from rotations.
• Key 5: No spaces: Contact points should be tight, without any spaces.
• Key 6: Flat to slight curve of Spee: The curve of Spee should have no more than a slight arch, and intercuspation of teeth should be relatively flat.

Ideal Occlusion

• An ideal occlusion entails a harmonious interdigitation of upper and lower teeth arising from the developmental process, encompassing jaw growth, tooth formation, and eruption.
• In simpler terms, it is aesthetically and physiologically good.

Normal Occlusion

• Angle's Class I is a normal occlusion where the mesiobuccal cusp of the maxillary first molar occludes with the mesiobuccal groove of the mandibular first molar.
• Ideal occlusion has a coinciding midline, no crowding, spacing, or rotation; acceptable overjet is 2-4mm; crown angulation and inclination are correct; and a flat curve of Spee.

Malocclusion

• Malocclusion refers to any deviation from the ideal that is deemed aesthetically or functionally unsatisfactory.

Static Occlusion

• Static occlusion focuses on contacts between the teeth when the jaw is stationary, which are seen as dots using articulating paper.

Dynamic Occlusion

• Dynamic occlusion analyzes contacts between the teeth during mandibular movements (sideways, forward, backward, or angled). Tooth contacts are no longer represented as dots but rather as lines.

Gum Pads

• Alveolar processes are present at birth and are covered by a dense layer of fibrous periosteum.
• The gum pads are pink and firm.
• The gum pad gets segmented into labiobuccal and lingual portions.
• The lateral sulcus is used to evaluate interarch relationships at an early stage.

Status of Dentition at Birth

• Neonates are toothless for approximately the first six months.
• The gum pads are not wide enough to accommodate the crowding of the developing incisors.
• During the first year of life, the gum pads expand to accommodate the eruption of incisors in a good alignment.
• Precise jaw relationships are usually not established yet.

Natal/Neonatal Teeth

• Natal teeth are very rare and usually found in the mandibular incisor region.
• Neonatal teeth are also rare, typically located in the mandibular incisor region, and may display familial tendencies.
• The conditions frequently classify natal/neonatal teeth into four categories.

Complications

• Natal teeth can cause interference with feeding, risk of aspiration, and potential trauma to the baby's tongue or the mother's breast.
• Early tooth eruption may lead to mucosal ulceration.

Diagnosis

• Radiographic verification assists in assessing the normal relationship between natal/neonatal teeth and adjacent and nearby teeth, as well as the presence of/absence of a tooth germ in the primary dentition.

Treatment

• Natural teeth are the preferred treatment for maintaining the correct position if there's no interference with the baby's health or feeding.
• Tooth removal should be considered only when teeth impair feeding; or the teeth are mobile enough to risk aspiration.
• The presence of trauma and the risk of aspiration necessitate consideration of immediate tooth removal.

Cleaning of Gum Pads

• Begin cleaning gum pads in the first week after birth.
• Position the baby with its head on your lap and feet outstretched.
• Gently wipe the gum pads with a gauze.

Self-Correcting Anomalies

• Certain developmental anomalies in the jaw and teeth can potentially correct themselves over time.
• Various factors, such as jaw growth, tooth eruption, and dietary changes, can influence these corrections.

Deciduous Dentition Period (6 Months - 6 Years)

• This is the period when primary teeth erupt.

Chronology of Primary Dentition

• This details the timelines involved in the eruption of primary teeth.

Overbite

• Overbite is the amount of vertical overlap between the upper and lower central incisors.
• It is typically expressed as a percentage or in millimeters.
• Normal overbite in primary dentition varies between 10-40%.

Overjet

• Overjet refers to the horizontal distance between the upper and lower central incisors.
• It is usually measured in millimeters.
• A normal overjet in the primary dentition range is 0–4 mm.

Spacing

• Spacing concerns the presence or absence of gaps between the teeth in the primary dentition.
• Generalized spacing is a common occurrence in primary dentition.
• Other tooth spaces can be observed, such as primate spaces, which develop between the canines and first molars.

Canine Relationship

• Deciduous canine relationship is typically stable in primary dentition.
• Class I relationship entails the mandibular canine aligning in the embrasure between the maxillary lateral and canine teeth.
• Class II relationship involves the mandibular canine positioning within the distal embrasure of the maxillary canine.

Molar Relationship

• Flush terminal plane indicates that molar relationships align vertically with a tangent line passing through the molars.
• Mesial step means the mandibular cusp sits ahead of the maxillary cusp in a mesial direction.
• Distal step indicates that the maxillary cusp lies ahead of the mandibular cusp in a distal direction.

Mixed Dentition Period (6-12 Years)

• Concurrent presence of primary and permanent teeth characterize this phase.
• This is a critical period of development for occlusion and dentition.
• Alveolar processes are more adaptive, making it an ideal time for orthodontic intervention.

First Transitional Phase (6-9 Years)

• First permanent molar and incisor eruption.
• Presence of early molar mesial shifts, associated with lower molar movement.
• Space is created through differential growth of the lower jaw and physiological leeway spaces.

Second Transitional Phase (10-12 Years)

• Final canine and premolar replacement from primary to permanent.
• "Leeway" space refers to the dimensional difference between primary and permanent canines and premolars.
• The combined mesiodistal width of permanent canine and premolars is less than the combined width of deciduous canine, first molar, and second molar.

Incisor Liability

• Difference in mesiodistal dimensions between deciduous and succedaneous permanent incisors.
• A more upright angle for primary incisors in comparison to permanent incisors is typical.
• Decline in the incisor angle, from approximately 150-123 degrees.

Space Required and Space Gained

• Shows a breakdown of the required and gained space during mixed dentition.

Safety Valve Mechanism

• Natural occlusion mechanism that maintains proper occlusion and balances potential jaw growth mismatches.
• The intercanine width of the maxilla serves as an important safety valve for the occlusion.

Intertransitional Phase (8-10 Years)

• Stable period of mixed dentition.
• Presence of deciduous canines between permanent molars and incisors.

Ugly Duckling Stage

• A self-correcting malocclusion phase that appears in the maxillary incisor region between 8-10 years.
• Erupting upper permanent canines often cause mid-line diastema accompanied by distal flaring of the incisors.

Permanent Dentition Stage

• Period where the final primary/deciduous teeth are replaced by permanent teeth.
• Jaw bone growth typically slows and ceases towards the end of this stage.
• Eruption sequence of permanent teeth in the maxillary and mandibular arches.

Occlusal Plane

• Occlusal plane is a plane that passes through the occlusal surfaces of the teeth.
• Determining the occlusal plane using a visual method is possible.

The Development of The Concepts of Occlusion

• Three approaches to understanding occlusion: fictional, hypothetical, and factual.
• Observation helps develop a factual understanding of occlusion.

Six Keys to Normal Occlusion

• Collection of 120 models of naturally excellent occlusions and criteria used for selections (no orthodontic treatment; straight and pleasing;bite was generally correct; no benefit from further treatment).
• Key 1: Class 1 molar relationship.
• Key 2: Correct crown angulation.
• Key 3: Correct crown inclination.
• Key 4: No rotation.
• Key 5: No spacing.
• Key 6: Flat to slight curve of Spee.
• Key 7: Correct tooth size or the Bolton's ratio.