Oral Anatomy Lecture: Eruption and Development

Covers the eruption timeline for deciduous and permanent teeth. Explains abnormal occlusion, physiological spacing, and factors affecting tooth alignment. Details tooth development stages from natal teeth to full permanent dentition. Includes primary and secondary factors affecting dental stability and function. Discusses key anatomical curves: Curve of Spee, Curve of Wilson, and Curve of Monson. Describes phylogenetic tooth forms and evolutionary stages. Breaks down basic tooth shapes and their functional significance. Ideal for dental students reviewing for exams or clinical practice.

Natal Teeth

Sometimes mandibular incisors may be present in newborns.

Neonatal Teeth

Erupts within the first 30 days of life.

Abnormal occlusion / Malposition / Malocclusion

Kapag hindi nabuo ang ngipin at nagkukulang sa spacingdue todental neglect

Physiological Space / Developmental Space

Resulting from the jaw growth manifestation at 5 years old. This is the spacing of the deciduous teeth

Coalescence

Union / Fusion

3 to 4 months / 11 months

The enamel of the crowns of all deciduous teeth begins to calcify between __ to __ months in utero and completes calcification at about __ months.

14 months

For mandibular teeth, the completion of deciduous roots takes place __ months after emergence in the oral cavity.

6 to 30 months, 2 to 3 years old

All deciduous teeth erupt from __ to __ months of post natal life (it will be completed from __ to __ years old—from initial calcification of the deciduous incisors to the completion of roots of deciduous 2nd molars).

Four mandibular incisors

Occasionally all ___ erupt before others.

2 or 2½

When the child is years of age, all of the deciduous teeth are expected to be in use.

Central > Lateral > First molar > Canine > Second molar

Usual order of appearance (deciduous)

5 years old

At __ years old, there is a jaw growth manifested by some separation of the deciduous teeth — Physiological spacing (developmental spacing).

1. Premature loss of deciduous teeth

2. Their retention

3. Congenital absence of teeth

4. Insufficient spacing

Important factors in the development of an abnormal occlusion.

Loss of arch length

Their premature loss from dental neglect is likely to cause a ___ with consequent tendency for crowding of permanent teeth.

Timing of eruption

Is a large part of heredity and sometimes environmental factors.

Lunt and Law

Lateral Incisors, canine, and first molar tend to erupt earlier in the maxilla.

29 months

Deciduous maxillary second molar eruption

20 months

Mandibular canine eruption

1st permanent molars

What is the six-year molars?

Right at birth

When does the calcification of 1st permanent molars start?

Mandibular Central Incisor (6 - 7 y.o)

What is the second tooth to erupt? And when does it erupt? (It may erupt simultaneously or even before the mandibular 1st molar)

Lingual to the deciduous roots

Where are the follicles of the developing incisors and canines located?

Permanent Dentition

Which dentition allows the eruption of teeth in females to occur earlier?

Deciduous Dentition

Which dentition allows the eruption of teeth in females to occur later?

Premolars

In permanent dentition, mandibular teeth tend to erupt earlier except ___?

Bifurcation

The developing premolars are within the ____ of deciduous molar roots.

Deciduous 2nd Molar

Which tooth dictates the type of occlusion in the teeth?

It is essential in maintaining the position of the teeth.

1st permanent molar and 1st permanent mandibular central incisors

What might simultaneously erupt together?

Lingual

The lower incisors ___ to deciduous dentition.

Exfoliate

Before the permanent central incisors erupt, the deciduous central incisor must ____ first.

Resorbed

The root of the deciduous tooth gets ____ during the transition stage.

Failure of deciduous roots to resorb may bring about prolonged retention of deciduous tooth.

1. First molars

2. Mandibular Central & Lateral incisors

3. Maxillary central incisors

4. Maxillary lateral incisors

5. Mandibular canines

6. First premolars

7. Second premolars

8. Maxillary canines

9. Second molars

10. Third molars

Tooth eruption sequence in permanent dentition

Grooves/Developmental grooves

What can be found in lobes?

4

What’s the minimum number of lobes formation?

Coalescence

• It refers to the process where separate structures, such as lobes of a tooth, merge to become one.

• This can occur in tooth development when the individual lobes of a tooth unite to form a single, cohesive structure.

Cusps

Lobes will become _____.

1. Prepare food for wallowing

2. Facilitate digestion

3. Articulate speech

4. Personal appearance (Esthetics)

What are the primary functions of teeth?

1. Facilitate prehension (combat/battle) [Canine]

2. Incision [Incisors]

3. Trituration of food [Premolars & Molars]

Form of Teeth (Which tooth has the SHAPE - Incisors = canine)

Omnivorous

Teeth, joints, and muscles of man have the form and alignment that enables masticcations of both animal and vegetables foods.

This dentition is referred as ____?

Occlusion

When teeth in the lower jaw comes in contact with those in the upper jaw in any functional relation.

Basal bones

No ngipin = no centric occlusion

It’s the maxillary and mandibular jaw that are left without the teeth.

What is now left?

Occlusion

Used to designate the anatomic alignment the of the teeth and their relationship to the rest of the masticatory system.

Centric relation

When there are teeth = centric occlusion.

If there are teeth, the maxillary and mandibular bones are related such that the condyle is in its most relaxed position within the glenoid fossa of the sphenoid bone.

Malocclusion

Used to describe deviations in relations of the teeth and/or jaws.

Interdental/interproximal space

What can be found in the interdental/interproximal papilla?

Interdental/interproximal papilla

• Contacts of each tooth with its neighbors in the jaw.

• It protects the gingiva between them in the interproximal/interdental spaces.

Gingival line

It follows the curvature, but not necessarily at same level with the cervical line.

Cervical line

It is a more stable anatomic demarcation whereas gingival line is variable and merely represents the gingival level on the tooth in a man’s life.

Form

“____” of a tooth is the anatomical shape of the tooth and is closely related to the function the tooth performs

1. It relates to masticating food without damaging the supporting tissues.

2. It relates to masticating food by providing desired stimulation and exercise to the periodontium and cleaning tooth surfaces.

3. It relates to the jaw, occlusal forces, tooth angulation, and stability in maintaining dental arches.

What are the PRIMARY FACTORS that affect the stability of teeth by affecting efficiency during function?

1. Cusp form (if pudpod na, di na masyado makakapagchew).

2. The proportional measurement of crown and root.

3. Root anchorage and angulation of teeth to the jaw.

What are the SECONDARY FACTORS that affect the stability of teeth by affecting efficiency during function?

Occlusal Contacts

When the teeth in mandibular arch come in contact with the maxillary arch in any functional relation.

Alignment and Contact

Anatomic alignment of the teeth and their relationship to the rest of masticatory system.

Interdental Papilla

Gum tissues that occupy the interproximal space.

The interdental space is formed by the alveolar process as the base, with the sides being the proximal surfaces of the adjacent teeth. The apex of this space is the area of contact between the two teeth.

How is the interproximal space formed?

Gum tissue between the two teeth, located in the middle of the interproximal area, is known as the ____.

It is a curvature of the gingiva.

Where can you find COL? What is COL?

Col

A valley-like depression which connects the gingival papillae situated in the interproximal space between two teeth.

4

How many embrasures in between the teeth?

Anteriors

Contact point =

Posteriors

Contact area =

Root Form

It includes both the length , shape, and angle at which the incisal and occlusal surfaces of crown of tooth are placed with respect to the root bases.

Centered, Root

The mesial view of an anterior tooth will show that the incisal ridge is ___ over the ____.

Root

_____ is wider than the width of cusp to cusp (for posteriors).

Stabilization

The flare of the roots in multirooted teeth add to their _______.

Compensating Curves

• Curve of mandibular arch - concave

• Curve of maxillary arch - convex

• Curve of the maxilla compensates on the curve of the mandible.

• Cusps and the incisal edges compensate to the location of edges and occlusal surface of occlusion teeth.

Curves of Spee

• Graf von Spee

• From the occlusal surfaces of the teeth, starting at the tip of the mandibular canine and extending to the buccal cusp tip of the molars.

• Sagittal relationship (anteroposterior-relationship line).

• Established the occlusal alignment of the teeth as projected into the median plane.

Bonwill Equilateral Triangle

• 1899

• Dentist Bonwill

• Measured from his patient/skeleton from central incisors to the condyles is 4 inches/ 10.16 cm both right and left

• From center of condyle to the other center of condyle is also 4 inches/ 10.16 cm

• 4 inch = 10.16 cm

Curve of Wilson

• U-shape

• Also called the compensating curve, it is formed by the concave and convex arches.

• Mediolateral Curve

• This imaginary curve extends from the buccal cusps of one molar to the buccal cusps of the opposite molar.

• The lower teeth serve as the basis for determining the Curve of Wilson, which highlights the prominence of the buccal cusps and ensures heavy occlusal contact on the working side.

Curve of Monson

• Curve of Spee + Curve of Wilson

• Anteroposterior and mediolateral positions of the curvatures.

• Forms inverted cup.

• Fixed point is = glabella.

• Contacts the compensating curve of curve of spee and compensating curve of curve of wilson.

• Based in spherical theory of occlusion or inverted cup.

• A surface of a sphere of 8 inches/20.32cm in diameter considering the glabella (noo banda); shape of inverted cone on a cup.

Bunodont

• Primates and relatively Isognathus.

• Limited lateral jaw movement.

• Tooth-bearing conical cusp.

Lophodont

Cusps in line.

Isognathus

• Equally jawed.

• Upper and lower jaws are same width.

• EXS: Pigs

Selenodont Molars

Crescent-shape cusp.

Anisognathus

• Unequal jaws.

• EXS: Domestic animals, cats, dogs, human beings.

• Lower dental arch is narrower in comparison to the upper.

1. Single cone (haplodont)

2. Three cusps in line (triconodont)

3. Three cusps in a triangle (tritubercular molar)

4. Four cusps in a quadrangle (quadritubercular molar)

What are the four phylogenetic clases of tooth forms?

1. Reptilian stage (haplodont)

2. Early mammalian stage (triconodont)

3. Triangular stage (tribercular molar)

4. Quadritubercular stage

What are the four stages of tooth forms?

Single cone

Haplodont

Three cusps in the line

Triconodont

Three cusps in a triangle

Tritubercular molar

Four cusps in a triangle

Quadritubercular molar

Reptilian Stage

Haplodont

Reptilian stage (Haplodont)

• Represented by the simplest form of tooth, the single cone

• Usually includes many teeth in both jaws that limit jaw movement

• There is no occlusion of the teeth in this class

• Teeth being used mainly for

  1. Prehension or combat

  2. Procurement of food

Early Mammalian stage (Triconodont)

• Exhibits 3 cusps in the development of posterior teeth

• The largest, or anthropologically the original cusp, is centered with a smaller cusp located anteriorly and another posteriorly.

Triangular Stage (Tritubercular molar)

• Exhibits teeth of three-cornered

• Shape (triangle), with the teeth bypassing each other more or less when the jaw opened or closed

• This stage created projections that is triangular in form that occluded with an antagonist in the opposing jaw.

Triangular Stage

(Tritubercular molar)

Early Mammalian stage (Triconodont)

Triconodont

Quadritubercular stage (lower molar)

• Exhibits teeth of four projections to established

• Occlusion with tritubercular molars (upper molars)

Quadritubercular stage

(lower molar)

FACIAL AND LINGUAL ASPECTS OF ALL TEETH

May be represented by trapezoids of various dimensions shortest of the uneven sides is toward the tooth cervix. The longest of the uneven sides is toward the occlusal or incisal aspect.

1. TRIANGLE

2. TRAPEZOID

3. RHOMBOID

All aspects of each tooth crown except the incisal or occlusal aspects may be outlined schematically within three geometric figures:

• The interproximal spaces accommodate interproximal tissue. Spacing between roots allows sufficient investment.

• Each tooth in either dental arch occludes with two adjacent teeth in the opposing arch except the lower central incisor and the upper third molar.

• The contact between the teeth in the same dental arch help protect the interproximal gingival tissue from trauma during mastication.

FUNDAMENTALS OF THE TRAPEZOID FORM

Interproximal tissue

The interproximal spaces accommodate_______. Spacing between roots allows sufficient bone investment.

Mandibular central incisor AND Maxillary third molar

Each tooth in either dental arch occludes with two adjacent teeth in the opposing arch except the ______ and the _______.

interproximal gingival tissue, mastication

The contact between the teeth in the same dental arch help protect the_______ from trauma during _______.

FUNDAMENTALS OF THE TRIANGULAR FORM

A wide base of the crown for strength. Tapered outlines (labially and lingually) to a thin ridge to facilitate the penetration of food

Triangle

Mesial of maxillary central incisor

Triangle

Distal of maxillary canine

TRIANGLE

Proximal surfaces of anterior teeth.

Trapezoid

• Uneven sides. 1 mahaba, 1 maigsi