Age factors in orthodontics /certified fixed orthodontic courses by Indian dental academy


Published on

Welcome to Indian Dental Academy
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 has a unique training program & curriculum that provides students with exceptional clinical skills and enabling them to return to their office with high level confidence and start treating patients

State of the art comprehensive training-Faculty of world wide repute &Very affordable.

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

Age factors in orthodontics /certified fixed orthodontic courses by Indian dental academy

  1. 1. AGE FACTORS IN ORTHODONTICS INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. • • • • • Dental changes with age Skeletal changes with age Soft tissue changes with age Treatment options and age Tooth movement and age
  3. 3. Along with the considerations of potential growth pattern of the patient , it is important to consider the dental age , skeletal age and emotional age of the individual relating to the readiness for orthodontic treatment. There is probably no more fundamental biologic principle underlying orthodontic diagnosis and treatment planning than this concept of biologic ages A fundamentally correct treatment plan instituted at wrong time can yield poor results.Thus for certain kinds of problems , treatment timing is probably the most critical decision that orthodontist has to make
  5. 5. Changes in dental occlusion with age • From birth until adulthood and beyond , dental occlusion undergoes significant changes • It is important to understand and recognize the scope of the changes that are normally occurring in the dentition to be able to diagnose any abnormal developments and prevent treating normal conditions in the mixed dentition stage
  6. 6. • Stages of dental development 4 stages : 1.Gum pads 2.Primary dentition 3.Mixed dentition 4.Permanent dentition • Normalcy in the dentofacial region differs from age to age • There are certain features in the developing dento facial complex which are normal in a child , however when present in an adult would constitute a malocclusion • These are self correcting malocclusions or transient malocclusions
  7. 7. • Some of the transient malocclusions are 1. Open bite seen in gum pads 2.Spacing in deciduous dentition 3.First deep bite
  8. 8. Transient malocclusions ……. 4.Flush terminal plane 5.Ugly duckling stage 6.Second deep bite
  9. 9. Clinical considerations • Diastema in early mixed dentition stage - Should be left untreated to avoid impacting the permanent maxillary canine - At early stages of dental development the cusp tips of the erupting canines are too close to the apices of the lateral incisors - positioning the mesially inclined roots of the incisors upright with the orthodontic appliance could place the lateral incisor roots in the path of eruption of canine
  10. 10. - Might cause either the impaction of canines or the resorption of root of lateral incisor - Orthodontic treatment that involves such movements should be postpone until the level of the cusp tip has atleast passed beyond the apical third of the root of the lateral incisor
  11. 11. • Molar relationship - Cases with distal step in the primary dentition stage – treatment started soon because condition will not self correct with time - Patient’s with flush terminal plane relationship present a more challenging question – half of these cases progress to normal class I relationship, rest to either class II or end to end occlusion
  12. 12. - These findings imply that what is considered normal occlusion in primary or mixed dentition stage does not necessarily lead to a normal occlusion in the permanent dentition stage - Therefore it is important for the clinician to closely observe these cases and initiate orthodontic treatment at the appropriate time
  13. 13. • TSALD - Significantly increased from early adolescence until early adulthood - So,without long term retention ,adolescents who were orthodontically treated to a perfectly aligned dentition should expect some crowding to occur in the anterior part of the dental arches - Important clinical implications regarding long term stability and retention of the treatment results - The patient should be made aware of the probability of these changes occurring after the retention appliances have been discontinued
  14. 14. Dental arch changes with age • Maxillary arch - Intercanine width increases – between 3 -13 yrs by 6mm - Between13-45 yrs by 1.7mm - Intermolar width – increases - between 3 -5yrs by 2 mm - between 8-13 yrs by 2.2 mm - decreases – by 1mm by 45 yrs of age - There is a slight decrease in arch length with age because of uprighting of the incisors
  15. 15. • Mandibular arch - Intercanine width increases – between 3 -13 yrs by 3.7mm - Between13-45 yrs by 1. 2mm - Intermolar width – increases - between 3 -5yrs by 1.5mm - between 8-13 yrs by 1mm - decreases – by 1mm by 45 yrs of age - There is a slight decrease in arch length with age because of uprighting of the incisors and loss of leeway space by the mesial movement of the first permanent molars
  16. 16. Clinical considerations • Following the eruption of mandibular central and lateral incisors , the arch width measurements in the lower arch are established • Lower arch length may decrease with the loss of primary molars and the mesial movement of first permanent molars in the leeway space • Because of these limitations ,most clinicians consider the lower arch as the key to orthodontic diagnosis
  17. 17.  Dental changes in adolescence upper molar lower molar Male moved forward upright Female upright moved forward  Dental characteristics of aging - Less upper incisor show and more lower incisor show at rest and on smile. - This is of great clinical importance because surgical overintrusion of maxilla results in an esthetically disastrous aging of the patient’s face
  19. 19. Maxillary complex • Enlarges AP by deposition of bone posteriorly at the tuberosities, which also lengthens the dental arch • Forward growth - anterior displacement as the bone is laid down on its posterior aspect
  20. 20. • Downward growth - vertical development of the alveolar process, eruption of teeth and inferior drift of the hard palate • Lateral growth - displacement apart of the two halves of the maxilla,with the deposition of bone at the midline suture • Maxillary growth ceases on average at about 15 yrs in girls and about 17 yrs in boys
  21. 21. Mandible • Most mandibular growth occurs as a result of periosteal activity • Muscular processes develop at the angles of the mandible and the coronoids and the alveolar processes develop vertically to keep pace with the eruption of the teeth • As the mandible elongates with growth at the condylar cartilage, its anterior part is displaced forwards ,while at the same time periosteal remodelling maintains its shape
  22. 22. • Bone is laid down on the posterior margin of the vertical ramus and resorbed on the anterior margin and this posterior drift of the ramus allows lengthening of the dental arch posteriorly • At the same time the vertical ramus becomes taller to accommodate the increase in height of the alveolar processes • Lengthening of the mandible and anterior remodelling together cause the chin to become more prominent , an obvious feature of facial maturation • Mandibular growth ceases rather later than maxillary growth , about 17 yrs in girls and 19 yrs in boys
  23. 23. Growth rotations • Growth rotations are most obvious and have their greatest impact on mandible ,their effects on maxilla are small and are almost completely masked by surface remodelling • Forward growth rotations are more common than backward rotations • Have both vertical and AP effects – correction of class II malocclusion will be helped by a forward growth rotation but made more difficult by a backward rotation • Also have an effect on position of the lower labial segment • Thus growth rotations play an important role in the etiology of certain malocclusions and must be taken into account while planning orthodontic treatment
  24. 24. • The adolescent growth spurt in the mandible occurs in less than 25% of the cases ,but the presence ,onset , duration and magnitude of the pubertal growth spurt in facial dimensions cannot be accurately predicted for any one individual • Substantial mandibular growth occurs during adolescence over a number of years .Therefore in the presence of significant skeletal discrepancies , treatment should not be postponed in anticipation of the elusive spurt ,particularly if treatment is indicated at an earlier age
  25. 25. • For individuals with unfavorable skeletal relationships ,it is wiser to design a treatment plan with the assumption that the same facial growth pattern will be maintained during the treatment period. • Orthodontists should be familiar with the effects of the mechanics used on the facial and dental structures therefore growth projections require careful attention to the mechanics used
  26. 26. • In patient’s with a steep mandibular plane , open bite tendency , long anterior face ,and a class II malocclusion at age 10 yrs ,the probability is high that in most of these cases a vertical growth pattern will continue. • so, orthopedic correction should include the use of an extraoral highpull force to the molars or any other appropriate appliance that the clinician prefers to use
  27. 27. • In patient’s with average skeletal discrepancy ,the assumption will be that growth is going to proceed in an unfavorable direction relative to the needed correction. As treatment progresses , two possible outcomes may occur : - If the case improves as a result of favorable growth and treatment changes,the clinician can modify the mechanics accordingly - If growth proceeds in an unfavorable direction ,the mechanics are already designed with the eventuality in mind
  28. 28. Growth modification for skeletal changes in the adolescent Facial skeletal growth patterns in adolescents that often are improved through orthodontics and growth modification include •Mandibular deficiency – redirection of skeletal growth vectors with head gear,functional appliance have the potential to improve mandibular projection and are often combined with head gear
  29. 29. • Maxillary horizontal deficiency – maxillary protraction and non surgical advancement of the maxilla • Vertical maxillary excess – vertically directed head gear , chin cups ,bite block functional therapy • Horizontal maxillary excess – either through retardation of anteroposterior growth through head gear or through camouflage via premolar extraction and retraction of anterior teeth
  30. 30. Facial skeletal growth patterns in adolescents that often are not easily corrected by orthodontics and growth modification include • Mandibular prognathism – Sutural growth of the maxilla is more easily affected than the complex growth characteristics of the mandible - Application of chin cup force can result in a down and back rotation of the mandible, so chin cup therapy is effective in cases with a short lower facial height, contraindicated in long face class III patients
  31. 31. • Vertical maxillary growth deficiency - Any influence on this growth pattern is difficult and there is little evidence that any growth modification techniques that can significantly influence this growth pattern are available • Chin deficiency - Relative improvement in chin projection may occur with treatment designed to increase AP projection of the mandible,but growth of the chin point itself is not affected by orthodontic or orthopedic treatment
  32. 32. • The process of mandibular growth and remodeling is not simply time-linked and the basis for changes in patterns are not known. • If temporal differences exist, they are not related directly to dental age. The differences in pattern are large enough to theoretically influence orthodontic treatment outcomes. • Therefore, treatments that are designed to influence growth of the mandible must take into account whether the mandible is growing in a more vertical or horizontal direction during the therapeutic phase. If orthodontic treatment plans are to be designed to “work with growth,” then it is important to know both the direction and the velocity of growth that is to be modulated.
  33. 33. • The mandibular remodeling has more variability during periods of rapid growth. • Treatment plans that concentrate on changing mandibular growth could very well be more effective if applied during a time in which growth is occurring with more variation in the pattern. (Age-related differences in mandibular ramus growth: a histologic study Mark G. Hans, Donald H.Enlow, Regina Noachtar. Angle Orthodontist 1995)
  35. 35. Changes in lip length with growth Vertical lip growth • Subtelny – longtitudinal soft tissue changes upper and lower lips , nose and soft tissue chin Upper lip length ↑ ↓ ↑ ↓ From 1-3yrs Between 3-6 yrs After 6 ( 6 – 15 )yrs Slowly after 15 yrs • Growth curve is similar to that of general body growth curve of Scammon
  36. 36. Lip separation • Seen in growing adolescents • Upper and lower lip grow more than skeletal lower face • Lower lip grow vertically than upper lip
  37. 37. Clinical importance • Lip incompetence seen at 6 yrs , is self corrected at 16 yrs • This is clinically significant b’coz : » Esthetic effect » Relation to the stability of overjet correction • At ages 6-8 yrs – lip incompetence is due to short lips ( subjectively ) , but is actually due to incomplete soft tissue growth • Growth differential between lips and dentoskeletal components is an advantage in treatment of unfavorable tooth to lips relationship • Vertical height has great influence on treatment outcomes relative to resting lip posture , resting incisor relations , and smile lines
  38. 38. • Mamandras studied lip growth Females - Maxillary lip length completed at age 14 yrs - Mandibular lip length completed at age of 16 yrs Males - Maxillary and mandibular lip length completed at 18 yrs • Genecov - between 7 – 17 yrs males have a greater increase in upper lip length than females of the same age
  39. 39. Lip thickness • Subtelny : – Upper lip thickness increases from ages 1 – 14 in both males and females – In males there is an increase in thickness after 14 yrs of age • Mamandras : - upper lip in females – maximum thickness at 14 yrs , thinning at 16 yrs - upper lip in males – maximum thickness at 16 yrs , thinning thereafter - lower lip in both males and females – growth completed by 15 yrs
  40. 40. Clinical importance • Extraction therapy on facial profile is more noticeable in female patients than male patients • Because lips do not thicken much during puberty in females , any extraction treatment plan for females with straight to convex profile should be considered with caution • In adolescent patients with marginal lip fullness orthodontic placement of upper incisors becomes very important ,this is because incisor retraction to decrease the overjet will cause undesirable treatment outcome
  41. 41. Nasal growth • Subtelny (1959 ) - downward and forward growth of nose - more vertically than A-P - In males spurt is between 10 – 16 yrs - In females , there is a steadier growth curve and there is more nasal growth than boys during early adolescents - In Angle’s class II there is more pronounced elevation of the bridge of the nose than in angle’s class I
  42. 42. Nasal projection • Males – greater rate of growth (from 12 – 17 yrs ) • Females – constant from age 12 Clinical importance - Orthodontist evaluating class II female at age 12 – expect minimal increase in nasal projection over the next 2 yrs - In males , if upper lip retraction is done in combination with expected nasal growth , will produce less than optimal relationship between lips and nose
  43. 43. Chin • Chin thickness – Genecov et al - females greater than males – from ages 7-9 yrs - males greater than females till 17 yrs • Nanda – - The increased projection of chin seen in females is attributable to increased mandibular growth
  44. 44. Adulthood • Behrent’s research  Nasal changes - increase in nasal projection - nasal tip moved inferiorly  Lip thickness - upper lip tended to rotate down and back from the base of the nose - so , less maxillary incisor would be exposed on rest and on smile  Nasolabial changes - With decrease in lip prominence and lowering of nasal tip , the nasolabial angle becomes more acute
  45. 45. • Treatment planning decisions may be influenced by the knowledge that soft tissue contour thickness will be established by about age 16, but significant soft tissue projection may still be expected on the basis of continued skeletal growth. • Treatment modalities involving extraction and/or surgery should be influenced by the fact that there will be a differential change in the soft tissue topography, with the nose and chin areas exhibiting more growth relative to the midface and nasal regions. • The net perceptual effect of the midface flattening or receeding within the facial complex is created by the differential soft tissue movements rather than the perceived result of orthodontic manipulations.
  46. 46. • It would appear that soft tissue profile changes are caused by both skeletal movement and soft tissue thickening. • As nose and chin growth are expected to exceed lip growth, allowances at the treatment planning stage for this differential tendency may minimize any untoward growth effects on the soft tissue profile.(Angle Orthodontist 1997 No. 5, 373 - 380: Soft tissue profile changes in late adolescent males Timothy F. Foley, Peter G. Duncan.)
  48. 48. Treatment planning in the primary dentition 1. Reasons for treatment - To remove obstacles to normal growth of the face and dentition - To maintain or restore normal function
  49. 49. 2. Conditions that should be treated - Anterior and posterior cross bites - Cases in which primary teeth have been lost and loss of arch space may result
  50. 50. - Unduly retained primary incisors which interfere with normal eruption of the permanent incisors - Malpositioned teeth which interfere with normal occlusal function or induce faulty patterns of mandibular closure - All habits or malfunctions which may distort growth
  51. 51. 3. Conditions that may be treated - Distoclusions that are atleast partly positional.Occlusal equilibration or tooth movements may restore normal function , the rest of the problem may be treated at this time or later - Certain distoclusions of a skeletal nature are best treated at this age , but the patient must be socially mature and the cases must be carefully chosen - Open bite due to tongue thrusting or digital sucking habit
  52. 52. 4.Contraindication to treatment in the primary dentition - when there is no assurance that the results will be sustained - when a better result can be achieved with less effort at another time - when social immaturity of the child makes treatment impractical
  53. 53. Treatment planning in the transitional dentition 1. Reasons for treatment - To remove obstacles to normal growth of the face and dentition - When the malocclusion cannot be treated more efficiently in the permanent dentition 2. Conditions that should be treated - Loss of primary teeth endangering the available space in the arch - Closure of space due to premature loss of primary teeth - Crossbites of permanent teeth - Supernumerary teeth that may cause malocclusion - Class II cases of functional , dental and skeletal type - Space supervision problems
  54. 54. 3. Conditions that may be treated - Class II malocclusion of skeletal type - Class III malocclusion where early treatment is possible - All malocclusions accompanied by extremely large teeth . If serial extractions are to be undertaken , treatment must be instituted in the mixed dentition - Gross inadequacies or disharmonies of the apical base
  55. 55. Serial extraction procedures • when properly executed, will result in self-correction or prevention of the development of irregularities in the incisal segments of both maxillary and mandibular dentures.
  56. 56. • Such procedures, excluding the existence of abnormal tongue and swallowing habits, will permit the mandibular incisors to tip and move lingually to positions of functional balance, thus giving the orthodontist a valuable clue to the correct location and inclinations of these teeth. • If such information is recorded and the positions and inclinations of the mandibular incisors maintained until the conclusion of orthodontic treatment, little difficulty will be experienced during the retention period. –Charles H. Tweed, 1966 (Angle Orthodontist, 1990: Serial extraction of first premolars – postretention evaluation of stability and relapse Robert M. Little, Richard A...)
  57. 57. Maxillary expansion • Expansion of the maxillary arch is the most common treatment intervention to correct posterior cross bite ,and the treatment approach is related to the age of the patient • Before the mid palatine suture fusion orthopedic forces may be applied to separate the suture and allow the bone to fill in the expanded midpalatine area
  58. 58. • Once the suture closes , at about 16 yrs of age ,a decline in the ability of rapid palatal expansion occurs as a result of the progressive interdigitation and fusion of the various sutures as well as the resistance of the skeletal and soft tissue structures , which in turn become less responsive to the expansion forces • Although , it is relatively easy to widen the maxilla by opening the mid palatal suture during adolescence , it becomes gradually more difficult during late adolescence • As a result , the effectiveness of RME decreases and after 16 yrs of age is usually not recommended
  59. 59. Surgically assisted expansion • The ability to increase the skeletal transverse dimension in the adults may be accomplished with a surgically assisted rapid palatal expansion or during orthognathic surgery when a two or three piece maxillary osteotomy widens the maxilla
  60. 60. Adolescent treatment 1. General characteristics of adolescent malocclusion - Dentition and occlusal relationships are established - Skeletal growth may be mostly over and decelerating - Muscle function is matured - Functional malocclusions are less frequent since they have largely been accommodated by dentoalveolar , skeletal , or mandibular joint adaptations
  61. 61. 2. Advantages of adolescent treatment - Control of all permanent teeth except third molars is now possible - It is beneficial to treat when bone turnover rates are still high though adult dimensions are nearly achieved - Motivation for treatment is high , especially when facial esthetics are affected - Since treatment is less dictated by developmental events , treatment options are lessened
  62. 62. 3.Some difficulties in adolescent treatment - The best opportunities for control and manipulation of severe skeletal dysplasia are past - Sports and social activities so important to adolescent , often compete with plans for orthodontic treatment - The time necessary for treatment may be longer for certain malocclusions - Tooth positioning is often more difficult when the occlusion is fully established and root formation is complete than was tooth guidance during eruption
  63. 63. Adult orthodontics • When treating adults orthodontist needs to be prepared to do the following - Diagnose different stages of periodontal disease and their associated risk factors - Diagnose TMJ dysfunction before , during , after tooth movement - Determine which cases require surgical management and which ones require incisor reangulation to camouflage the skeletal base discrepancy - Work cooperatively with a team of other specialists to give the patient the best outcome
  64. 64. Indications • To improve tooth - periodontal relationship • To establish an improved plane of occlusion in order to distribute forces through the broadest area possible • To balance the existing space between teeth for better prosthetic replacement • To improve spaces to provide for normal tooth to tooth contact • To improve occlusion and coordination with the masticatory muscles and TMJ • To satisfy the esthetic desires of the patient
  65. 65. Contra indications • • • • • • Severe skeletal discrepancies Advanced local or systemic disease Excessive alveolar bone loss Inability to obtain a satisfactory result Poor stability prognosis Lack of patient motivation
  66. 66. • Mandibular skeletal problem in pre adolescent child –  AP direction - Excess – orthopedic posterior force (chin cup ) - Deficiency - orthopedic anterior force (functional appliances )
  67. 67.  Vertical direction - Excess - orthopedic vertical maxillary force ( vertical pull chin cup + bite block ) - Deficiency – Appliance to increase the vertical alveolar development ( bite plane )
  68. 68. • Mandibular skeletal problem in non growing patients  AP direction - Excess – mild - camouflage - severe – surgical mandibular set back - Deficiency - mild - camouflage - severe – surgical mandibular advancement
  69. 69.  Vertical direction - Excess - mild - camouflage - severe – surgical height reduction - Deficiency - mild - camouflage - severe – surgical height increase
  70. 70. • Maxillary skeletal problem in pre adolescent child –  AP direction - Excess – orthopedic posterior force (head gear ) - Deficiency - orthopedic anterior force ( reverse pull head gear )
  71. 71.  Vertical direction - Excess - orthopedic vertical maxillary force ( high pull head gear ) - Deficiency – Appliance to increase the vertical alveolar development (functional appliance )
  72. 72. • Maxillary skeletal problem in non growing patients  AP direction - Excess – mild - camouflage - severe – surgical maxillary set back - Deficiency - mild - camouflage - severe – surgical maxillary advancement  Vertical direction - Excess - mild - camouflage - severe – surgical maxillary impaction - Deficiency - mild - camouflage - severe – surgical maxillary inferior position
  73. 73. Factors in the selection of the orthodontic treatment plan Adolescent EXISTING ORAL PATHOSIS Dental caries More likely to have simple limited caries lesions, but more susceptible to caries Periodontal disease More resistant to bone loss , but highly susceptible to gingival inflammation Faulty restorations Few significant restorative problems TMJ Small percentage with symptoms , because of high degree of TMJ adaptability Adult More likely to have recurrent decay , restorative failures , root decay and pulpal pathosis High susceptibility to periodontal bone loss Frequent restorative problems with economic and treatment planning implications Frequent appearance of symptoms with dysfunction
  74. 74. Adolescent Adult Dentofacial esthetics Reasonable concern , frequently matched to severity of condition Occlusal awareness Infrequent cause of problem SKELETAL RELATIONSHIPS Because of growth , an orthopedic treatment option available , stable correction of skeletal discrepancies possible , vertical corrections most difficult , AP next and transverse least BIOLOGIC CONSIDERATIONS Significant neuromuscular adaptability , allowing variety of biomechanical choices Concern occasionally disproportionate to degree of existing pathosis Heightened;may lead to accelerated enamel wear with adverse change in supporting tissue No growth , surgical changes necessary for moderate to severe skeletal disharmonies ,orthodontic correction of skeletal transverse problems most difficult , AP problems somewhat less and vertical problems least Mechanical options limited because of lack of neuromuscular ability
  75. 75. Adolescent Adult • Growth is a positive factor in the resolution of many adolescent malocclusions No growth is present , so potential for significant skeletal alterations without orthognathic procedures is minimized • Rate of tooth movement Predictable and rapid, particularly during eruptive stages when permanent root development is not yet completed Initially somewhat slower , but more rapid and predictable once initial movement has begun THERAPEUTIC APPROACHES AVAILABLE Tooth movement Most require some tooth moving force Most require some tooth moving force Orthopedics Effective in only small percent About half require this
  76. 76. Adolescent Adult Functional appliances Benefit possible in 20 % - 30 % Orthognathic surgery Major skeletal alterations needed in 1%-5% EXTRACTION VERSUS NON EXTRACTION THERAPY Four premolar extraction more frequent to resolve crowding symmetrically Small percent benefit Alterations needed in 10%50% Four premolar extraction less frequent to resolve crowding , upper premolar extraction , asymmetric extraction and lower incisor extraction , stripping of over bulked restoration are more common
  77. 77. Adult Adolescent ANCHORAGE REQUIREMENTS More frequent incorporation of headgear to maximize anchorage and the retraction of anterior teeth Greater anchorage potential because of completely erupted 1st and 2nd molars,in addition accentuated mesial drift , particularly in the mandibular arch means that fewer adult cases will be categorized as maximum anchorage problems
  78. 78. Factors affecting patient’s acceptance of the orthodontic treatment plan Adolescent • Adult Duration of treatment Usually not of concern;2-21/2 yrs in orthodontic appliance is handled quite easily by most adolescents • Cost of treatment Insurance may cover cost, parents frequently will make sacrifices to accommodate their child’s need Adults are much more cognizant of the duration of treatment and may assume something is going wrong if they are not finished at projected time Adult orthodontics not covered by insurance, so orthodontist must be sensitive to these factors,so patients will receive optimal treatment and not be “turned off” to quality dental care
  79. 79. Adolescent • Adult Perceived risk / benefit ratio Greater sense of benefits compared to minimal risks Must be assessed by the orthodontist and honestly discussed with the patient,explanations given to the patient about the responsibilities during treatment , especially periodontal maintainence and more frequent recall to the hygienist while in appliance
  81. 81. Tipping • The adult supporting structures react somewhat differently when compared to the young tissues because the anatomic environment in the adults is different • The periodontal structures , particularly the labial and lingual bony plates are composed of a dense lamellated bone tissue with relatively small marrow spaces,Spongy bone exists in the interseptal areas • So,tooth movement in a MD direction within the “alveolar trough”is more favorable than in a labiolingual direction
  82. 82. • Along the inner bone surface of adults ,a series of darkly stained resting lines are seen ,indicating that only minor tissue changes have occurred over a long time • The root exhibits a thick layer of cementum and strong apical fibres • The apical third of the root is more firmly anchored in adults than in young patients • Hence , when an adult tooth is tipped over a short distance there is comparatively little tooth movement of the apical third of the root • On the other hand , if the tipping is prolonged , the tooth will begin to act as a two – armed lever • There may be apical resorption and destruction of alveolar bone wall as well
  83. 83. Extrusion • Successful extrusion of teeth is largely dependent on whether the treatment is performed during favorable growth period • Extrusion in a mass movement may result in complete and permanent closure of the bite provided the treatment is performed shortly after the eruption of the teeth • Such a favorable result is due to the readiness by which the supporting tissues of young persons are transformed and rearranged after tooth movement
  84. 84. • After the age of 18 – 20 yrs there is less growth activity • The pdl fiber bundles will become stretched after extrusion , but are less readily elongated and rearranged • There is also a tendency for more distant fibers along the alveolar crest to stretch • Extrusion of adult teeth in a mass movement may thus result in relapse after displacement and subsequent contraction of the whole gingival fiber system • In such cases , closure of an open bite may be performed with greater success if front teeth are extruded individually and not in a mass movement
  85. 85. Intrusion • Some practitioners state that intrusion of adult teeth cannot be undertaken without a corresponding shortening of the apices by root resorption • If carefully measured forces are applied , there will be less tendency for such shortening of roots • Stabilisation of tooth position after intrusion of adult teeth can be attained only by establishing a correct MD relationship between the dental arches
  86. 86. Timing of surgical treatment • Early jaw surgery has little inhibitory effect on further growth • Actively growing patient’s with mandibular prognathism can be expected to outgrow surgical correction and require retreatment • So , the correction of mandibular growth must be delayed until the late teens
  87. 87. • In contrast to mandibular set back , mandibular advancement at age 14 – 15 is quite feasible • Maxillary advancement should be delayed until the early adolescent growth spurt unless there are preponderant psycological considerations
  88. 88. Biomechanical considerations • In an adult patient the amount of bone support of each tooth is an important consideration • When bone has been lost ,the Pdl area decreases,and the same force against the crown produces greater pressure in the Pdl of a periodontally compromised tooth than a normally supported one • The absolute magnitude of force used to move teeth must be reduced , to prevent damage to the Pdl ,bone , cementum and root • The greater the loss of attachment,the smaller the area of supported root and the further apical the center of resistance will become
  89. 89. • The magnitude of tipping moment produced by a force is equal to the force times the distance from the point of force application to the center of resistance • Orthodontic force must be applied to the crown of a tooth, and the further the point of force application is from the COR,the greater will be the tipping moment produced by any given force
  90. 90. Age related changes in periodontal ligament • The number of adult patients in most clinical orthodontic practices has increased in recent years. Because orthopedic jaw control through growth is impossible in adult patients and periodontal disease is more likely,orthodontic tooth movement is more complex in adults than in adolescents. • In particular, adults who have periodontal problems risk permanent damage to the periodontal tissues • The periodontal ligament (PDL), plays a significant role in bone remodeling at the PDL-alveolar bone interface during tooth movement.
  91. 91. • Proliferative activity of fibroblast-like cells in the PDL decreases with age, and faster or more efficient tooth movement can be achieved in younger individuals (AO1997 Influences of aging changes in proliferative rate of PDL cells during experimental tooth movement in rats Shingo Kyo)
  92. 92. Age related bone changes • Orthodontic tooth movement as a result of bone modeling and remodeling also depends greatly on age related changes of the skeleton • Cortical bone becomes more dense while the spongeous bone reduces with age and the structure changes from that of a honeycomb to a network
  93. 93. The biologic background for orthodontic tooth movement in adults indicates that 1.The forces used in adults should be at a lower level than those used in children 2.The initial forces should be kept low because the immediate pool of cells available for bone resorption is low 3.The moment – to – force ratio should be increased according to the periodontal status of the individual teeth 4.With increasing marginal bone loss , light continuous intrusive force should be maintained during tooth displacement
  94. 94. Retention • The amount of growth remaining after orthodontic treatment will obviously depend on the age , sex , and relative maturity of the patient • After growth modification treatments ,post treatment rebound is likely ,with more growth of the upper than the lower jaw • Relapse tendency controlled in 2 ways - To continue head gear on the upper molar on a reduced basis - Functional appliance of the activator – bionator type to hold tooth position and the occlusal relationship
  95. 95. • Adult patient’s should be brought to their final orthodontic relationship with archwires and then stabilized with immediately placed retainers before eventual detailing of occlusal relationship by equilibration • A suckdown plastic wafer is the best choice immediately upon removing the orthodontic appliance
  96. 96. Conclusion • Don’t disturb transient malocclusions. • Attempts at orthopedic change to be timed…to maximize the growth potential of the patient. • Class II malocclusions due to mandibular deficiencies and class III malocclusions due to a deficient maxilla are treatable…when treatment is undertaken or properly timed. • Although the periodontal and alveolar support is generally weaker…adult patient can be treated through alterations in the bio-mechanical approach.
  97. 97. References • Orthodontics – current principles and techniques – Graber and Vanarsdall • Orthodontics – current principles and techniques – Graber and Swain • Textbook of orthodontics – Samir.E .Bishara • Orthodontics – Principles and practice – T.M.Graber • Contemporary orthodontics – William.R.Profitt • Orthodontic and orthopaedic treatment in mixed dentition – - Mc Namara and Brudon • Biomechanics in clinical orthodontics – Ravindra Nanda • Handbook of facial growth – Enlow • Esthetic orthodontics and orthognathic surgery – - David.M.Sarver
  98. 98. THANK YOU Leader in continuing dental education