Development of occlusion /certified fixed orthodontic courses by Indian dental academy


Published on

The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit ,or call

Published in: Health & Medicine, Business
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Development of occlusion /certified fixed orthodontic courses by Indian dental academy

  1. 1. DEVELOPMENT OF OCCLUSION INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. . Occlusion is better defined as the dynamic morphologic and functional relationship between all components of masticatory system including teeth, supporting tissues, neuromuscular system, TMJ, and craniofacial skeleton It is a complex set of relationships involving the CNS, masticatory muscles, TMJ, teeth and their associated structures and a complex neuromuscular network integrating all of these elements.
  3. 3. Ideal occlusion is a theoretical concept of ideal arrangement of teeth within dental arches combined with an ideal interarch relationship, which concentrates optimal esthetics, function and stability of dentition and supporting structures.
  4. 4. Graber defined occlusion as the normal relations of the occlusal inclined planes of teeth when the jaws are closed . Normal occlusion (or) orthodontically referred, as angle class1 occlusion is the mesiobuccal cusp of maxillary 1st molar should occlude in the mesiobuccal groove of mandibular 1st permanent molar.
  5. 5. Anterior guidance occlusion During protrusive mandibular excursion, contacts between maxillary incisors and mandibular anterior teeth guide the mandible downward to create dis-articulation of all other teeth.
  6. 6. Canine guidance occlusion During lateral mandibular excursion the distolabial surface of mandibular canine on the working side comes into contact with the mesiolingual surface of maxillary canine causing dis-articulation of all other teeth
  7. 7. DEVELOPMENT OF TEETH  The first sign of tooth development appears late in the third embryonic week. Both ectodermal and mesodermal tissue contribute to the formation of the teeth. The epithelial dental organ which molds the shape of the entire tooth and is responsible for the formation of Enamel is derived from the ectoderm of oral cavity. The other parts of the tooth including dentin, pulp, cementum and periodontal ligament arise from mesoderm
  8. 8. The teeth progress through a series of developmental stages which have been arbitrarily defined as follows a) The dental lamina and bud stage b)The cap stage c) The Bell stage d) The Hertwig’s epithelial root sheath and root formation stage 
  9. 9. Bud Stage  During the 6th week inutero, a thickening of the oral epithelium in the area of future dental arch occurs as a result of Cellular Proliferation and extends along the entire free margin of Jaw. This represents the Primordium of ectodermal portion of teeth called the dental lamina from each dental lamina 10 oval swellings, the buds, which are precursors of Primary dentition arise at 10 different points corresponding to future position of the primary teeth.
  10. 10. Cap Stage  By differential proliferation, the buds progress into cap stage which is characterized by shallow invagination on deep surface of bud. The peripheral cells of cap stage appear in two portions, outer and inner enamel epithelium. Outer cells of the cap are cuboidal and are called O.E.E. The cells lining the concavity of the cap become tall columnar and called I.E.E. Between the 2 layers, the cells of epithelial dental organ separate by an increase in intercellular fluid and become arranged in stellate pattern called stellate Reticulum (or) Enamel pulp.
  11. 11.  Under the influence of proliferating epithelium of dental organ, the mesodermal tissue, which is partly covered by invaginated portion of inner dental epithelium. Proliferates and condenses to form dental papilla, which is formative organ of dentin and precursor of pulp. The cells adjacent to inner dental epithelium eventually differentiate into odontoblasts. During this developmental period, there is a marginal condensation of mesenchymal tissue surrounding the outside border of enamel organ and the dental papilla which becomes organized into dental sac. Enamel organ, dental papilla and dental follice are collectively called tooth germ.
  12. 12. Bell Stage   With continued invagination and growth enamel organ progresses into bell stage. In this stage, cells of inner dental epithelium which assume a position similar to future crown of tooth differentiate into Ameloblasts. The peripheral influence of epithelium differentiates into odontoblasts. The dental lamina for all teeth except 1st permanent molar, Proliferates at deep and to produce dental organ of permanent successor. The invaginated aspects of enamel organ covers most of dental papilla, which produces dentin in outer layers. As primary dentin is produced, dental papilla is converted to dental pulp. In later part of bell stage connection between dental and enamel organs begin to disappear.
  13. 13. Root formation stage   After enamel and dentin formation reaches future CEJ, roots of teeth begin to form. The shape of root is governed principally by Hertwig’s epithelial sheath, which is formed in epithelial dental organ. After odontoblast produces dentin along contour established by sheath, the sheath disappears. This generally takes place between 6th –14th week until 6th month and both enamel and dentin grow by bone apposition.
  14. 14.
  15. 15. Development of Dental Arch   It represents the changes that occur in mandible, maxilla and their alveolar regions to provide adequate space and bone for teeth. Since approximate time span for tooth eruption is from 6 months to 18 yrs dental arch developmental time is atleast 18 yrs. Most dimensional changes in dental arches occur during the time of eruption (or) exfoliation of teeth, otherwise they are reasonably static. The greatest rate of increase of dental arches occurs between birth and 3 yrs. further increments from 4 to 18 yrs are comparatively small.
  16. 16. Cont…      The arch length mesial to 1st permanent molar may be longest during early primary dentition, in part because of Posterior inter dental spaces. Changes in the dental arch are measured by using arch dimensions. The usual arch dimensions are 1) widths at the canines, primary molars and 1 st permanent molars. It is important to keep in mind 3 important facts when studying width changes a)Width dimensional increase involves alveolar process growth almost totally since there is little skeletal width increase at this time.
  17. 17. b) There are important clinical differences in the magnitude and manner of width changes in maxilla and mandible. Dental arch width increases highly with vertical alveolar process growth. maxilla alveolar process diverse while mandible alveolar process are more parallel. c)Increase in dental arch width is closely related to events of dental development, less to endocrinally mediated events of overall skeletal growth.
  18. 18. Cont…..  The inter canine diameter increases only slightly in the mandible and some of this increase is result of distal tipping of primary cuspids into primate space. In mandible the only significant increase in inter canine width occurs during the eruption of incisors when the primary cuspids are moved distally into primate spaces. It does not widen significantly thereafter.
  19. 19. Cont…  Maxillary 1st premolar width increases significantly more than the mandible, especially in males. Although the alveolar process growth is almost vertical in the mandible, the crowns of first molars erupt tipped somewhat lingually and do not upright fully until the time of eruption of the second molars. As the 1st molars upright, they cause an increase in bimolar width, but this is not an increase in the diameter of mandible itself.
  20. 20. 2. Arch length (Depth)  It is measured at the midline from a point midway between the central incisors to a tangent touching the distal surfaces of the second primary molars (or) second premolars. This does not have the clinical importance of the circumference. Sometimes one-half of the circumference is referred to as ‘arch length’.
  21. 21.
  22. 22. 3. Circumference (Perimeter)   This is usually measured from the distal surface of 2nd primary molar around the arch over the contact points and incisal edges in a smoothed curve to the distal surface of 2nd primary molar of the opposite side. The reduction in mandible arch circumference during the transitional and early adolescent dentition is result of a) late mesial shift of the 1 st permanent molars as leeway space is preempted b) mesial drifting tendency of posterior teeth throughout the life c) slight amounts of inter proximal wear of teeth d) lingual positioning of incisors as a result of the differential mandibular maxillary growth e) original tipped positions of incisors and molars.
  23. 23.   The last point is a reflection of skeletal pattern, steepness of occlusal plane and vertical alveolar growth which in some cases i.e. where incisors are tipped lingually and molars are tipped mesially, shortens arch perimeter markedly. The mandibular arch perimeter shows great variability during natural development. The variation is caused by differences in skeletal pattern, sex (women’s arches shorten more) and caries experience (it increase perimeter loss).
  24. 24.  Maxillary arch perimeter typically increases slightly although it has an equal chance to either increase (or) decrease. The very marked difference in angulation of maxillary permanent incisors as compared with the primary and great increases in width probably account for tendency to preserve the circumference of upper jaw even though the permanent molars are drifting mesially.
  25. 25. Dental development can be divided into  (1)   Calcification  (2)   Eruption 
  26. 26. Calcification        Calcification of primary teeth are as follows: Central incisors 14 weeks 1st molars 15½ weeks Lateral incisors 16 weeks Canine 17 weeks 2nd molar 18 weeks Maxillary teeth calcify before the mandibular teeth with the exception of mandibular canine which calcifies before maxillary canine.
  27. 27. Calcification of permanent teeth     It begins at birth, with the calcification of cusps of 1 st permanent molars and extends as late as 25th year. At 5½ to 6 yrs, calcification of maxillary permanent canine is complete and the clinical emergence takes place soon after the completion of 1/3rd of root is completed. Girls are more advanced in calcification of permanent teeth than boys. Permanent teeth eruption begins between 6-8 yrs and extends to 21st yr and frequently much later. The teeth in mandible with the exception of 2nd premolars erupt in a short period of time than the maxillary teeth.
  28. 28. Eruption of permanent teeth     Pre emergent eruption Two process are necessary i) there must be resorption of bone and primary tooth roots overlying the crown of erupting tooth. ii) the eruption mechanism itself then must more the tooth in the direction of where the path has been cleared. Although, the 2 mechanisms normally operate in concert, in some circumstances they do not. The rate of bone resorption and tooth eruption are not controlled physiologically by the same mechanism.
  29. 29. –Theories of Eruption         Numerous theories have been proposed .among  these Root elongation ,Alveolar bone  remodeling,P.D.L.Traction &Vascular are important. Bone remodeling theory supposes that selective  deposition & resorption of bone brings about eruption. Root growth theory supposes that proliferating root  impinges on a fixed case thus converting an apically  directed force into occlusal movement
  30. 30.       Vascular pressure theory supposes that a local  increase in tissue fluid pressure in the periapical  region is sufficient to form the tooth.            The Ligament traction theory propose that  cells & fibers of the ligament pull the tooth into  occlusion.      Eruption is a multi factorial process in which  cause &effect are difficult to separate….
  31. 31.    Despite many yrs of study, the precise mechanism through which the eruption force is generated remains unknown. From animal studies, it seems clear that the major eruption mechanism is localized within periodontal ligament. Other possibilities for eruption mechanism are localized variations in B.P (or) flow, forces delivered from contraction of fibroblasts and alterations in extracellular ground substances of periodontal ligament. Normally the rate of eruption is such that the apical area remains at same place while the crown mores occlusally, but if eruption is mechanically blocked, proliferating apical area will move in opposite direction, inducing resorption where it usually doesn’t occur. This causes distortion of root form which is called dilaceration.
  32. 32. Post emergent eruption    Once tooth emerges into mouth, it erupts rapidly until it approaches the occlusal level and is subjected to forces of mastication. At this point, the eruption slows and than as it reaches occlusal level of other teeth and is in complete function, eruption halts. The stage of relatively rapid eruption from the time a tooth first penetrates gingiva until it reaches the occulsal level is called the post emergent spurt, in contrast to the following, phase of slow eruption is termed the juvenile occlusal equilibrium.
  33. 33.   During juvenile equilibrium, teeth that are in function erupt at a rate that parallels the rate of vertical growth of mandibular ramus. As the mandible continues to grow, it moves away from the maxilla, creating a space into which the teeth erupts. Since the rate of eruption parallels the rate of jaw growth, it is not surprising that a pubertal spurt in eruption of teeth accompanies pubertal spurt in jaw growth. This reinforces the concept that after a tooth is in occlusion, the rate of eruption is controlled by forces opposing eruption not promoting it. The forces opposing eruption in mouth are those from chewing, soft tissue pressures from lip, cheeks (or) tongue contacting the teeth.
  34. 34.  When the pubertal growth spurt ends, a final phase in tooth eruption called adult occlusal equilibrium is achieved. During adult life, teeth continue to erupt at on extremely slow rate. It its antagonist is lost at any age, a tooth can again erupt more rapidly, demonstrating that the eruption mechanism remains active and capable of producing significant tooth movement even late in life
  35. 35.  In studies of denitions of Australian aborigines, begg noted severe interproximal and occlusal attrition and concluded that this attritional process produced the “only anatomically correct occlusion”. He said “The accepted text book normal occlusion of civilized man is anatomically incorrect because his food is too soft and concentrated to cause tooth Attrition (Begg, 1954).
  36. 36.  High unworn cusps are wrongly considered to have evolved to maintain stability of occlusion throughout life, whereas the only advantage of high cusps is that they help to guide the teeth into their occlusal relationships at the time the teeth are erupting and then to hold them only for a short time after eruption”. He concluded that high rate of attrition is supposed to occur in modern humans and is result of natural evolutionary process.  Beyron also studied Australian aborigine dentition and masticatory movements of live subjects, findings the same severe occlusal and inter proximal wear that seems common in primitive culture with their abrasive diets and more frequent use of teeth as tools.
  37. 37. Relationship between calcification and eruption  Permanent teeth do not begin eruptive movements until after, the crown is completed. They pass through the crest of alveolar process at varying stages of root development. It takes from 2-5 yrs for the posterior teeth to reach the alveolar crust following the completion of their crowns and from 12-20 months to reach occlusion after reaching the alveolar margin. The roots are usually completed a few months after occlusion is attained. The moment of emergence into oral cavity often is spoken as the “time of eruption”. 
  38. 38. Periods of occlusal development  a) Pre-dental period  This is the period after birth where the neonate does not have any teeth. It usually lasts for 6 months after birth. Gum pads  The alveolar processes at the time of birth are known as gum pads. They are pink, firm and are covered by a dense layer of fibrous periosteum. They are horseshoe shaped and develop in two parts. They are the labio-buccal portion and the lingual portion. The 2 portions are separated from each other by a groove called dental groove. The gum pads are divided into ten segments by grooves called transverse grooves. Each of these segment consists of one developing deciduous tooth sac. 
  39. 39.
  40. 40.   The gingival groove separates the gum from palate and floor of the mouth. The transverse groove between canine and first deciduous molar segment is called lateral sulcus. The lateral sulci are useful in judging the inter arch relationship at a very early stage. 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. Contact occurs between upper and lower gum pads in the 1st molar region and a space exists between them in the anterior region. This infantile open bite is considered normal and it helps in suckling.
  41. 41.  Very rarely teeth are present at the time of birth. Such teeth are called natal teeth. Teeth that erupt during the 1st month are called neonatal teeth. The natal and neonatal teeth are mostly located in the mandibular incisor region and show a familial tendency.
  42. 42.
  43. 43. b) The deciduous dentition period   The initiation of primary tooth buds occurs during the 1st 6 weeks of intra uterine life. The primary teeth begin to erupt at the age of about 6 months and eruption is completed by 2½-3½ yrs of age when the deciduous 2nd molars come into occlusion. The mandibular central incisors are the 1st teeth to erupt into oral cavity. They erupt at around 6-7 months of age. The sequence of eruption of deciduous dentition is A-B-D-C-E. The primary dentition is established by 3 yrs of age. Between 3-6 yrs of age, dental arch is relatively stable and very few changed occur.
  44. 44.   Spacing usually exists between deciduous teeth. These spaces are called physiological (or) developmental spaces. The presence of spaces in the primary dentition is necessary for the normal development of permanent dentition. Absence of spaces is an indication that crowding of teeth may occur when larger permanent teeth erupt. Spacing is seen mesial to maxillary canines and distal to mandibular canines. These physiological spaces are called primate (or) simian (or) Anthropoid spaces as they are commonly seen in primates. These spaces help in the placement of canine cusps of the opposing arch.
  45. 45.
  46. 46.
  47. 47. Deep bite  A deep bite may occur in initial stages of development. This is accentuated by the fact that deciduous incisors are more upright than their successors. The lower incisal edges often contact the cingulum area of the maxillary incisors. The deep bite is later reduced due to i) Eruption of deciduous molars. ii) Attrition of incisors. iii) forward movement of mandibular due to growth.
  48. 48.     c) The mixed dentition period It begins approximately at 6 yrs of age with the eruption of 1st permanent molars. It can be classified into 3 phases. i) First transitional period This is characterized by the emergence of 1st permanent molars and exchange of deciduous molars with permanent incisors. The location and relationship of 1st permanent molar which is first permanent tooth depends much upon the distal surface relationship between upper and lower 2nd deciduous molars. The 1st permanent molars are guided into dental arch by distal surface of 2nd deciduous molars. The mesio-distal relationship between distal surfaces of upper and lower 2nd deciduous molars can be of 3 types.
  49. 49.   a) Flush terminal plane The distal surface of upper and lower deciduous 2nd molars are in 1 vertical plane. This is called flush (or) vertical terminal plane. This is a normal feature of deciduous dentition. Thus the erupting 1st permanent molars may also be in flush (or) end on relationship. For the transition of such an end on molar relation to a class I molar relation, the lower molar has to move forward by about 3-5 mm relative to upper molar. This occurs by utilization of physiologic spaces and leeway space in mandibule and differential growth of mandibule.
  50. 50.  The shift in lower molar from a flush terminal plane to a class I relation can occur in 2 ways which are designated as early and late shift. Early shift occurs during early mixed dentition period. The eruptive force of 1st permanent molar is sufficient to push the deciduous 1st and 2nd molars forward in the arch to close the primate space and thereby establish a class I molar relationship. Since this occurs in early mixed dentition period it is called early shift.
  51. 51.  Many children lack primate space and thus the erupting permanent molars are unable to move forward to establish class I relationship. in these cases, when the deciduous 2nd molars exfoliate the permanent 1st molars drift mesially utilizing the leeway space. This occurs in late mixed dentition period and hence called late shift.
  52. 52.   b) Mesial step terminal plane The distal surface of lower 2nd deciduous molar is more mesial than that of upper. Thus the permanent molars erupt directly into angles class I occlusion. This type of mesial step terminal plane most commonly occurs due to early forward growth of the mandible. If the differential growth of mandible in a forward direction persists, it can lead to an angle’s class III molar relation. If it is minimal it can establish class I molar relationship.
  53. 53.    c) Distal step terminal plane This is characterized by the distal surface of lower 2nd deciduous molar being more distal to that of upper. Thus the erupting permanent molars may be in Angle’s class II occlusion. During this period the deciduous incisors are replaced by permanent incisors. The mandibular central incisors are usually first to erupt. The permanent incisors are considerably larger than the deciduous teeth they replace. This difference between the amount of space needed for accommodation of incisors and the amount of space available for this is called incisal liability. It is roughly about 7mm in max arch and about 5mm in mandibular arch. The incisal liability is overcome by following factors. i) Utilization of interdental spaced seen in primary dentition. ii) Increase in inter canine width. iii) Change in incisor inclination.
  54. 54.
  55. 55.
  56. 56. ii) Inter transitional period  In this period the maxillary and mandibular arches consist of sets of deciduous and permanent teeth. Between the permanent incisors and 1st permanent molars are the deciduous molars and canines. This phase during the mixed dentition period is relatively stable and no change occurs. 
  57. 57.   iii) Second transitional period This is characterized by replacement of deciduous molars and canines by premolars and permanent cuspids respectively. The combined mesio distal width of permanent canines and premolars is usually less than that of deciduous canines and molars. This is called leeway space of nance. This is about 1.8mm in maxillary arch and about 3.4mm in mandibular arch. This excess space available after the exchange of the deciduous molars and canines is utilized for mesial drift of the mandibular molars to establish class I molar relation.
  58. 58.
  59. 59.    The ugly duckling stage Sometime a transient (or) self – correcting malocclusion is seen in maxillary incisor region between 8-9 yrs of age. This is seen during the eruption of permanent canines. As the developing permanent canines erupt, they displace the roots of lateral incisors mesially. This results in transmitting of force on the roots of central incisor which also get displaced mesially. A resultant distal divergence of crowns of the two central incisor causes a midline spacing. This situation has been described by broadbent as the ugly duckling stage as children tend to look ugly during this phase. This condition usually corrects by itself when the canines erupt and the pressure is transferred from the roots to the coronal area of incisors.
  60. 60.
  61. 61. Overjet and overbite  Over bite and overjet undergo significant changes during primary and transitional dentitions. During primary dentition, overbite normally decreases a slight amount and overjet is often reduced to zero. From the early mixed dentition to the completion of permanent occlusion the average overbite increases slightly and then decreases. Overbite is co-related with a number of vertical facial dimensions whereas overjet is a reflection of anteroposterior skeletal relationship.
  62. 62.       d) The permanent dentition period The permanent dentition forms within the jaws soon after birth, except for the cusps of the 1st permanent molars which form before birth. The permanent incisors develop lingual (or) palatal to the deciduous incisors and move labially as they erupt. The premolars develop below the diverging roots of the deciduous molars. The frequently seen eruption sequences in maxillary arch are 6-1-2-4-3-5-7 (or) 6-1-2-3-4-5-7 Mandibular arch 6-1-2-3-4-5-7 (or) 6-1-2-4-3-5-7
  63. 63.
  64. 64.         Clinical implication Determinants of occlusion are a.     Condylar guidance b.     Incisal guidance c.      Plane of occlusion d.     Compensating curve e.     Cusp height The exact integration of these determinants does not apply to a natural dentition where balance is not a naturally occuring condition. Each has some influence on the attritional pattern of dentition and in that sense considered an occlusal determinant.
  65. 65.   The teeth are aligned in dental arches with varying degrees of inclination both mesiodistally and buccolingually. When viewed laterally, a line from tip of canine touching the tips of buccal cusps of posterior teeth will describe a relatively smooth curve, the curve of spee. In transverse plane alignments of long axis of posterior teeth cause occlusal surfaces of mandibular molars to be directed somewhat lingually whereas those of max molars are directed buccally. For each pair of left and right posterior teeth, a transverse occlusal curve the curve of wilson can be described.
  66. 66.   It was once suggested that curves of spee and wilson are related three dimensionally so that all cusp tips and incisal ridges of all teeth are aligned on the curved surface of sphere (sphere of monsoon). However attempts to demonstrate such spherical curves in natural dentition have failed. An accurate diagnosis based on adequate history, examination and utilization of relevant information is fundamental to treatment of patients. Whenever possible specific causes and effect relationships should be established as a prelude to treatment decisions. These principles apply to management of patients with occlusal and dysfunctional problems of masticatory system.
  67. 67.     Theoretically ideal occlusion It is a preconceived view of structural and functional relationships. Such an occlusion occasionally represents the characteristics of a given individual. An occlusion and masticatory system should ideally be a. All components of masticatory system are present. b. In centric occlusion, the supporting cusps of all posterior teeth occlude with marginal ridges except disto buccal cusps of mandibular molars and mesio lingual cusps of maxillary molars which occlude with central fossae of opposing teeth.
  68. 68.     c.The occlusion is stable i.e. teeth do not migrate (or) change position other than slow physiological compensatory movement. d.Teeth do not exhibit attritional wear beyond what is expected for the age of individual. e.During protaction, posterior teeth disoclude so as not to interfere with ability of opposing incisor teeth to occlude and function properly. f.During lateral movements, the teeth on non working side disoclude so as not to interfere with the ability of opposing working side teeth to contact and function properly.
  69. 69.  g.All masticatory, deglutition, speech articulation, esthetics and respiratory requirements are met and are satisfactory to patient.  h.Minimum parafunctional activity, that is little phasic muscle activity occurs.  i.No signs (or) symptoms of pain (or) dysfunction from any component of masticatory system can be detected.
  70. 70.    Physiological occlusion Usually found in adults, it deviates in one (or) more ways from theoretically ideal occlusion but is well adapted, is esthetically satisfactory to patient and has no pathological manifestations (or) dysfunctional problems. This does not require therapeutic intervention. This demonstrated maxillomandibular relationships different from theoretical criteria, but no untoward effects are observed. Para-functional activity may be present, but all components of masticatory system are responding well and no pain (or)- dysfunctional signs (or) symptoms can be demonstrated.
  71. 71.         The criteria for physiological occlusion are a. Occlusal stability b.Masticatory function is satisfactory to patient. c. Speech articulation is acceptable to patient d. Esthetic considerations are acceptable. e. Freedom from signs (or) symptoms involving periodontal attachment apparatus. f.Freedom from signs (or) symptoms of conditions involving the teeth themselves. g. Freedom from signs (or) symptoms involving TMJ or musculature associated with mandibular function.
  72. 72.  Non-physiologic occlusion  It is one in which there are signs (or) symptoms of pathology, dysfunction, (or) inadequate adaptation of one (or) more components of the masticatory system that can be attributed to faulty structural relationship (or) mandibular functional (or) para functional activity. It also includes patients non-acceptance of occlusally related esthetics, speech articulation (or) masticatory function parameters.
  73. 73. In addition to subjective criteria for treatment there are objective criteria like signs (or) symptoms of  a.      Periodontal conditions attributed to functional loading.  b.     Pathological conditions of teeth that can be attributed to mandibular functional (or) para functional activity.  c.     TMJ disorders. 
  74. 74.    Therapeutic occlusion It is one that has been modified by appropriate therapeutic modalities in order to change a non-physiologic occlusion to one that at least falls within the parameters of physiologic occlusion, if not theoretically ideal. Such an occlusion may contain structural modifications not necessarily found in order to optimize the health and adaptive potential of masticatory system. Eg. cusp to fossae posterior occlusal relationship instead of cusp to marginal ridge relationship.
  75. 75. Conclusion  It is apparent that many unassociated factors exist in transition from deciduous to permanent dentition. Some can be defined with considerable precision i.e. size of teeth. While others such as incremental changes in anterior arch perimeter as incisors erupt are less clear.  Although changes are small, the alignment of permanent teeth depends on relationship between arch perimeter in primary dentition, changes in arch length and breadth in mixed dentition and the size of succedaneous teeth.
  76. 76. Thank you For more details please visit m