This document discusses occlusion and its development from birth through adulthood. It begins by defining static and dynamic occlusion. It then discusses ideal, normal, and physiologic occlusion. It describes the periods of occlusal development from pre-dental through deciduous, mixed, and permanent dentition. It provides details on eruption sequences, spacing, and transitional periods. It also discusses occlusal curvatures like the Curve of Spee and Wilson. In summary, it provides a comprehensive overview of occlusion, its classifications, development through life stages, and related anatomical concepts.

1. Dr. Abhishek Solanki Dr. Parvind Gumber

2. INTRODUCTION
 The term occlusion has both static and dynamic aspects
 Static refers to form, alignment and articulation of teeth
within & between dental arches and relationship of teeth
to their supporting structures
 It may be defined also as the contact relationship of the
teeth in function or parafunction

3. IDEAL OCCLUSION:
 Pre-conceived theoretical concept of occlusal structural &
functional relationships that include idealized principles
and characteristics that an occlusion should be
NORMAL OCCLUSION:
 It is class I relationship of maxillary & mandibular 1st
molars in centric occlusion
PHYSIOLOGIC OCCLUSION:
 Occlusion that deviates in one or more ways from ideal
yet it is well adapted to that particular environment is
esthetic & shows no pathologic manifestations

4. FUNCTIONAL OCCLUSION:
 An arrangement of teeth which will provide highest
efficiency during excursive movements of mandible which
is necessary during function
BALANCED OCCLUSION:
 An occlusion in which balance & equal contacts are
maintained throughout entire arch during all excursions of
mandible
 Others : Therapeutic occlusion, Traumatic Occlusion,
Centric Occlusion etc.

5. PERIODS OF OCCLUSAL DEVELOPMENT:
 PRE-DENTAL PERIOD
 DECIDUOUS DENTITION PERIOD
 MIXED DENTITION PERIOD
 PERMANENT DENTITION PERIOD

6. PRE-DENTAL PERIOD
 The period after birth during which the neonate does not
have teeth
 Lasts for 6 months

7. GUM PADS
 Alveolar processes at the time of birth
 Pink, firm and are covered by a dense layer of fibrous
periosteum

8.  Horse-shoe shaped and developed in two parts
 Labio-buccal portion & lingual portion
 Two portions of gum pads are separated by dental
groove

9.  Gum pad are divided into 10 segments by certain grooves
called transverse grooves
 Each of these segment consist of developing deciduous
tooth sac
 Gingival groove separate gum pads from palate & floor of
the mouth

10.  Transverse groove between canine & and first deciduous
molar segment is called the lateral sulcus
 Lateral sulci are useful in judging the inter-arch
relationship at a very early stage
 The lateral sulcus of the mandibular arch is normally
more distal to that of the maxillary arch
Lateral sulcus

11.  The upper and lower gum pads are almost similar to
each other
 The upper gum pad is both wider as well as longer than
the mandibular gum pad
 Thus when upper and lower gum pads are approximated,
there is a complete overjet all around

12.  Contact occurs b/w upper & lower gum pads in first
molar region and a space exists between them in
anterior region
 This infantile open bite is considered normal and it helps
in suckling
Infantile open bite for
suckling

13. Status of dentition
 Neonate is without teeth for about 6 months of life
 At birth gum pads are not sufficiently wide to
accommodate developing incisors, which are crowded in
their crypts
 During 1st year of life gum pads grow rapidly permitting
incisors to erupt in good alignment

14.  Teeth that are present at the time of birth are called natal
teeth.
 Teeth that erupt during the first month of age are called
neonatal teeth.
 The natal and neonatal teeth are mostly located in the
mandibular incisor region and show a familial tendency.

15. DECIDUOUS DENTITION PERIOD
 Initiation of primary tooth buds occurs during first six
weeks of intra-uterine life
 Primary teeth begin to erupt at age of about 6 months
 Eruption time for primary teeth : 21/2 - 3 1/2 years

16. Eruption age and sequence of
deciduous dentition
 A-B-D-C-E
 6months – 3 Years

17. ERUPTION SEQUENCE

18. SPACING IN DECIDUOUS DENTITION
 Spacing usually present b/w deciduous teeth & called
physiological spaces or developmental spaces
 Spaces in primary dentition is important for normal
development of permanent dentition

19.  Absence of spaces in primary dentition can cause
crowding (when the larger permanent teeth erupt)
 Spacing invariably is seen mesial to maxillary canines &
distal to mandibular canines

20.  These physiological spaces are called primate spaces or
simian spaces or anthropoid spaces as they are seen
commonly in primates
 These spaces help in placement of the canine cusps of
the opposing arch

21. Flush terminal plane
 Mesio-distal relation b/w distal surfaces of upper & lower
second deciduous molars is called the terminal plane
 A normal feature of deciduous dentition is a flush terminal
plane where distal surfaces of upper & lower second
deciduous molars are in same vertical plane

22. Deep bite
 A deep bite may occur in initial stages of development
 Deep bite is accentuated by fact that deciduous incisors
are more upright than their successors

23.  Lower incisal edges often contact cingulum area of
maxillary incisors
 This deep bite is later reduced due to following factors:
a. Eruption of deciduous molars
b. Attrition of incisors
c.Forward movement of mandible due to growth

24. MIXED DENTITION PERIOD
 Mixed dentition period begins at approximately 6 years of
age with eruption of 1st permanent molars
 During mixed dentition period, deciduous teeth along with
some permanent teeth are present in oral cavity

25.  Mixed dentition period classified into three phases:
 1st transitional period
 Inter-transitional period
 2nd transitional period

26. 1st transitional period
 Characterized by emergence of 1st permanent molars &
exchange of deciduous incisors with permanent incisors
 1st permanent molar erupts at 6 yrs guided into dental arch
by distal surface of 2nd deciduous molar

27.  Mesio-distal relation b/w distal surfaces of upper and
lower 2nd deciduous molars can be of three types:
1. FLUSH TERMINAL PLANE
2. DISTAL STEP
3. MESIAL STEP

28. Flush terminal plane
 Distal surface of upper & lower 2nd deciduous molars are
in one vertical plane
 Normal feature of deciduous dentition
 Erupting 1st permanent molars may also be in a flush or
end on relationship

29.  For transition of such an end on molar relation to a Class I
molar relation, lower molar has to move forward by about
3-5 mm relative to upper molar
 Utilization of physiologic spaces & leeway space in
lower arch & by differential forward growth of mandible
 Shift in lower molar from a flush terminal plane to a Class I
relation can occur in two ways - Early and Late shift

30. Early shift
 Early shift occurs during early mixed dentition period
 Eruptive force of 1st permanent molar is sufficient to push
deciduous 1st & 2nd molars forward in arch to close primate
space & establish a Class I molar relationship
 Since this occurs early in mixed dentition period it is called
early shift

31. Late shift
 Many children lack primate space & thus erupting
permanent molars are unable to move forward to establish
Class I relationship
 In these cases, when deciduous second molars exfoliate
permanent 1st molars drift mesialy utilizing leeway space
 This occurs in late mixed dentition period & is thus called
late shift

32. Mesial step terminal plane
 Distal surface of lower second deciduous molar is more
mesial than that of upper
 Permanent molars erupt directly into Angle's Class I
occlusion
 Mesial step terminal plane most commonly occurs due to
early forward growth of mandible

33.  If differential growth of mandible in a forward direction
persists, it can lead to Angle's Class III molar relation
 If forward mandibular growth is minimal, it can establish a
Class I molar relationship

34. Distal step terminal plane
 Distal surface of lower second deciduous molar being
more distal to that of the upper
 Thus erupting permanent molars maybe in Angle's Class
II occlusion

35. Occlusal Relationship of Primary & Permanent Molars

36. Exchange of incisors:
 During first transitional period deciduous incisors are
replaced by permanent incisors
 Mandibular central incisors : 1st to erupt
 Permanent incisors > deciduous incisors

37.  This difference b/w amount of space needed for
accommodation of incisors & amount of space available
for this is called Incisal liability
 Incisal liability (maxillary arch ) : about 7 mm
 Incisal liability (mandibular arch ) : about 5 mm

38.  The incisal liability is overcome by the following factors:
A. Utilization of interdental spaces seen in primary
dentition:
 Physiologic or developmental spaces that exist in primary
dentition are utilized to partly account for
incisal liability
 Permanent incisors are much more easily
accommodated in normal alignment in cases exhibiting
adequate inter-dental spaces than in an arch that has no
space

39. B. Increase in inter - canine width:
 During transition from primary incisors to permanent
incisors, increase in inter-canine width of both maxillary &
mandibular arches takes place
 This is an important factor that allows much larger
permanent incisors to be accommodated in arch
previously occupied by the deciduous incisors

40. C. Change in incisor inclination:
 One of differences b/w deciduous & permanent incisors
is their inclination
 Primary incisors are more upright than permanent
incisors
 Since permanent incisors erupt more labially inclined,
they tend to increase dental arch perimeter

41. A. Primary incisors are more
upright in alignment than
permanent incisors
B. Permanent incisors are
more labialy inclined

42. PRIMARY
DENTITION PERMANENT
DENTITION

43. Inter - transitional period
 In this period the maxillary and mandibular arches consist
of sets of deciduous and permanent teeth.
 Between permanent incisors and first permanent molars
are deciduous molars and canines.
 This phase during the mixed dentition period is relatively
stable and no change occurs.

44. 2nd transitional period
 2nd transitional period is characterized by replacement of
deciduous molars & canines by premolars & permanent
cuspids respectively
 Combined mesio-distal width of permanent canines &
premolars is usually less than that of deciduous canines
and molars & this Surplus space is called leeway space
of Nance

45.  Leeway space (mandibular arch) : about 3.4mm (1.7mm
on each side of the arch)
 Leeway space (maxillary arch) : about 1.8mm (0.9 mm
on each side of the arch)
 Excess space available after exchange of deciduous
molars & canines is utilized for mesial drift of mandibular
molars to establish Class I molar relation

46. Ugly duckling stage
 Sometimes a transient or self correcting malocclusion is
seen in maxillary incisor region b/w 8-9 years of age
 This is a particular situation seen during eruption of
permanent canines

47.  As developing permanent canines erupt, they displace
roots of lateral incisors on to roots of central incisors,
which also get displaced mesialy
 A resultant distal divergence of crowns of two central
incisors causes a midline spacing

48.  Described by Broadbent ( hence also known as
Broadbent phenomenon) as ugly duckling stage as
children tend to look ugly during this phase of
development
 This condition usually corrects by itself when canines
erupt & pressure is transferred from roots to coronal area
of incisors

49. PERMANENT DENTITION PERIOD
 Permanent dentition forms within jaws soon after birth,
except for cusps of first permanent molars, which form
before birth
 Permanent incisors develop lingual or palatal to deciduous
incisors and move labially as they erupt
 Premolars develop below diverging roots of deciduous
molars

50.  Eruption sequence of permanent dentition may exhibit
variation:
6-1-2-4-3-5-7 or 6-1-2-3-4-5-7
 In mandibular arch sequence is:
6-1-2-3-4-5-7 or 6-1-2-4-3-5-7

51. Occlusal Curvatures & Axial Position
a. Curve of Spee
b. Curve of Wilson
c. Sphere of Monson
d. Axial position

52. Curve of Spee
 The curvature which begins at the tip of canines & follows
buccal cusp tips of premolars & molars posteriorly, when
viewed from their facial aspect
 Two dimensional and curves upward from anterior to
posterior

53.  Inclination of some of individual posterior teeth must be
offset from vertical long axis of body, if their occlusal
surfaces are to conform to this curve
 Maxillary molar roots are inclined mesialy & mandibular
molar roots distally

54. Curve of Wilson
 Medio-lateral curvature of occlusal plane of posterior
teeth
 Two dimensional, at right angle to Curve of Spee
 Purpose of this arc in occlusal curvature is to
complement paths of condyles during movements of
mandible

55.  Crowns of mandibular posterior teeth must incline to
lingual, while crowns of maxillary posterior teeth must
incline toward buccal
 This curve becomes deeper posteriorly, so that molars
inclination is greater than that of premolars
 Because of this curve & associated tooth inclinations,
buccal cusps of mandibular molars & lingual cusps of
maxillary molars usually appear to be longer

56. Sphere of Monson
 Compensating Occlusal Curvature
 Three dimensional curvature of the occlusal plane, which
is the combination of the Curve of Spee and the Curve of
Wilson
 This curvature is in form of a portion of a ball, or sphere
 This curvature is concave for mandibular arch & convex
for the maxillary arch

57. Axial Position
 Inclination of a tooth from a vertical axis
 Normally described in mesio-distal & facio-lingual directions
 It is normally described in terms of root's inclination, which
means that crown is normally inclined in opposite direction

58.  These inclinations are necessary for proper occlusal &
incisal function of teeth
 As these axial positions are described, it should be of value
to relate them to individual tooth's functions, as well as its
inclination relative to Curves of Spee and Wilson

59. Axial Positions of teeth
TEETH DIRECTION INCLINATION (ROOT)
ANT. MAXILLARY TEETH FACIOLINGUAL LINGUAL
ANT. MAXILLARY TEETH MESIODISTAL INCISORS : MESIAL
CANINE : DISTAL

60. TEETH DIRECTION INCLINATION
(ROOTS)
MAXILLARY
PREMOLARS
FACIOLINGUAL LINGUAL
MAXILLARY
PREMOLARS
MESIODISTAL DISTAL
MAXILLARY MOLARS FACIOLINGUAL LINGUAL
MAXILLARY MOLARS MESIODISTAL MESIAL

61. TEETH DIRECTION INCLINATION
MANDIBULAR INCISOR &
CANINES
FACIOLINGUAL LINGUAL (ROOT)
MANDIBULAR INCISOR MESIODISTALLY MESIAL (ROOT)
MANDIBULAR CANINES MESIODISTALLY DISTAL (ROOT)

62. TEETH DIRECTION INCLINATION
MANDIBULAR
PREMOLAR
MESIODISTALLY DISTAL (ROOT)
MANDIBULAR
PREMOLAR 1st
FACIOLINGUAL LINGUAL (ROOT)
MANDIBULAR
PREMOLAR 2nd
FACIOLINGUAL BUCCAL (ROOT)
MANDIBULAR MOLAR MD & FL DISTAL & BUCCAL
MD : Mesio-distal
FL: Facio-lingual

63. References
 CONCISE DENTAL ANATOMY & MORPHOLOGY : JAMES L
FULLER
 DENTAL ANATOMY, PHYSIOLOGY & OCCLUSION: WHEELER’S
 TEXTBOOK OF DENTAL ANATOMY, PHYSIOLOGY &
OCCLUSION: RASHMI GS (PHULARI)
 MOYERS RE: HANDBOOK OF ORTHODONTICS
 ORTHODONTICS - THE ART & SCIENCE : S.I. BHALAJHI
 INTERNET

64. THANK YOU