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Crowding in mixed dentitn.pptx

  2. Crowding can be classified into: Simple crowding Complex crowding
  3. Simple Crowding Definition: Simple crowding is defined as disharmony between the size of the teeth and the space available for them. It is crowding uncomplicated by skeletal, muscular, or occlusal functional features. Simple crowding is most frequently associated with a class I molar relationship, although it may be found with class II horizontal type (maxillary dental protraction and normal facial skeleton).
  4. Complex Crowding Definition: Complex crowding is crowding caused and complicated by skeletal imbalance, abnormal lip and tongue functioning, and/or occlusal dysfunction as well as disharmony between the sized of the teeth and the available space.
  5. Signs of Arch Length Deficiency Children exhibit arch length deficiencies for two general reasons: (1) the arch length of some children is too small to accommodate the size of the teeth; and (2) a child may start with an adequate arch length but may develop a deficient arch length from a variety of environmental factors that affect the dentition (e.g., caries or loss of teeth)
  6. MEASUREMENT OF THE AVAILABLE ARCH LENGTH IN THE MIXED DENTITION Measure arch length segments from the buccal and labial sides of the arch at the contact points between the teeth
  7. Diagnosis
  8. Dental Cast Analysis in mixed dentition
  9. Tooth Size–Arch Length Analysis
  10. The main purpose of the mixed dentition space analysis is to differentiate patients with severely crowded arches from those who have up to as much as 4 mm of incisor crowding but who still have enough room in the entire arch, as a result of leeway space, for successful eruption of the permanent premolars and canines and proper alignment of the incisors.
  11. These patients are excellent candidates for a lower lingual arch or palatal holding arch. Treatment of these patients with a lingual or palatal arch provides them with an important and beneficial service. Intervention with these two preventive appliances can eliminate the need for future orthodontic treatment or simplify future orthodontic treatment.
  12. Patients predicted to have crowding of 5 or more mm in an arch should be referred to the orthodontist. This is also an important service to patients and their parents. Arch length deficiencies occur in the mixed dentition for two reasons: (1) the arch length is too small to accommodate the size of the teeth and (2) arch length is lost because of local causes.
  13. When the deficiency results from an imbalance between the size of the teeth and the arch, primary canines are prematurely exfoliated by the erupting incisors and the distances between the distal surfaces of the permanent lateral incisors and mesial surfaces of the primary first molars are small or nonexistent.
  14. Prediction of the Widths of Non-erupted Canines and Premolars
  15. In the early mixed dentition, the permanent incisors and first molars are erupted.
  16. The permanent canines and premolars have not erupted. Their mesial-distal widths can be measured on periapical radiographs, but the images are enlarged in comparison to the true widths of the teeth.
  17. Orthodontists have devised several methods of predicting the size of the nonerupted canines and premolars. The prediction methods use three basic predictor variables: (1) only erupted teeth, (2) only measurements from radiographs, and (3) a combination of variables 1 and 2. All methods of prediction involve error. The error of a prediction method is called its standard error of estimate.
  18. Proportional Equation Prediction Method The late mixed dentition starts with the eruption of one of the permanent canines or premolars. If most of the canines and premolars are erupted and if the nonerupted tooth or teeth are easily measured on a periapical radiograph, an alternative prediction method can be used. The method corrects the radiographic enlargement of a nonerupted tooth.
  19. The mesial-distal widths of the nonerupted tooth and an erupted tooth are measured on the same periapical radiograph. The mesial-distal width of the erupted tooth is measured on a plaster cast. These three measurements provide the elements of a proportion that can be solved to obtain the width of the non-erupted tooth on the cast.
  20. A simple proportional relationship can be setup: True width of primary molar Apparent width of primary molar True width of unerupted premolar Apparent width of unerupted premolar True width of primary molar Apparent width of primary molar True width of unerupted premolar App width of unerupted premolar X
  21. Estimation from proportionality tables
  22. Tanaka and Johnston (1974) and Moyers (1988) created non-radiographic prediction methods by correlating the sum of the widths of the lower permanent incisors with the sum of the widths of the lower premolars and canine on one side of the arch.
  23. There is a reasonably good correlation between the size of the erupted permanent incisors and the unerupted canines and premolars. These data have been tabulated for white American children by Moyers.
  24. To utilize the Moyers prediction tables, the mesiodistal width of the lower incisors is measured and this number is used to predict the size of both the lower and upper unerupted canines and premolars. The size of the lower incisors correlates better with the size of the upper canines and premolars than does the size of the upper incisors, because upper lateral incisors are extremely variable teeth.
  25. Moyers Prediction Values Total mandibular incisor width 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 Predicted width of canine and premolars Maxilla 20.6 20.9 21.2 21.3 21.8 22.0 22.3 22.6 Mandible 20.1 20.4 20.7 21.0 21.3 21.6 21.9 22.2
  26. Despite a tendency to overestimate the size of unerupted teeth, accuracy with this method is fairly good for the northern European white children on whose data it is based. No radiographs are required, and it can be used for the upper or lower arch. Tanaka and Johnston Prediction Method
  27. Tanaka and Johnston developed another way to use the width of the lower incisors to predict the size of unerupted canines and premolars. For children from a European population group, the method has a good accuracy despite a small bias toward overestimating the unerupted tooth sizes.
  28. TANAKA JOHNSTON PREDICTION VALUES TANAKA AND JOHNSTON PREDICTION VALUES One half of the mesiodistal width of the four lower incisors +10.5 mm = +11.0 mm= Estimated width of mandibular canine and premolars in one quadrant Estimated width of maxillary canine and premolars in one quadrant
  29. Interpretation of a Mixed- Dentition Arch Length Analysis
  30. If the analysis predicts borderline crowding of +2mm to −4mm in both arches of a Class I patient, consider holding arch length with a palatal (Nance) arch and a lower lingual holding arch. This intervention may prevent the need for future orthodontic treatment, or at least reduce the severity of the malocclusion.
  31. If the analysis predicts severe crowding in excess of −6 mm in one or both arches of a Class I patient, holding arches are not needed. In patients with crowding, primary canines may be extracted in both upper and lower arches to allow the permanent lateral incisors to erupt and to prevent the erupting incisors from shifting to the right or left of the facial midline. The crowded malocclusion will require comprehensive orthodontic treatment. These patients may benefit from serial extraction treatment.
  32. If the analysis predicts borderline crowding between +2mm and −5mm in the lower arch of a Class II patient, it is important to place a lower lingual holding arch to preserve arch length. If the lower holding arch allows the permanent teeth mesial to the first molars to erupt, the eventual treatment of a nonsurgical Class II malocclusion will be simplified. It should be clear that holding lower arch length per se with an appliance will not correct the Class II malocclusion.
  33. If the analysis predicts severe crowding in excess of −5mm in the lower arch of a Class II patient, a lingual holding arch may still be appropriate for the nonsurgical malocclusion. These patients have a malocclusion that is very difficult to treat, and they should be referred for comprehensive orthodontic treatment.
  34. If the analysis predicts borderline crowding of +2mm to −5mm in the upper arch of a Class III patient, it is important to place a palatal holding arch to preserve arch length. In these patients, extraction of premolars to relieve upper arch crowding complicates orthodontic treatment. Holding upper arch length will not correct the Class III malocclusion but can assist in the eventual treatment of a nonsurgical malocclusion.
  35. If the analysis predicts severe crowding in excess of −6mm in the lower arch of a Class III patient, a holding arch may be appropriate. The arch length preserved by the holding arch could enable an orthodontist to retract lower anterior teeth in a nonsurgical Class III malocclusion. These patients should be referred for comprehensive orthodontic treatment.
  36. Crowding can be classified as Mild crowding – upto 1.5mm Moderate crowding – 1.5 to 5mm Severe crowding – 6 to 8 mm
  37. Mild crowding can be treated by several methods. Cases that require only a simple tipping movement may often be treated with a removable appliance such as a spring retainer Moderate crowding may be treated with either extraction or nonextraction of permanent teeth. Severe crowding teeth would need to be extracted to create adequate space.
  38. Serial Extraction in Severely Crowded Cases in the Mixed Dentition When a patient is diagnosed with a Class I malocclusion and a severe TSALD of 8 to 10 mm or greater during the early mixed dentition, a decision may be made by the orthodontist that the patient would ultimately require extraction of four premolars to allow space for the proper alignment of the remaining teeth.
  39. Crowding The stepwise management of crowding involves the following steps : 1.Observation 2.Disking of primary teeth 3.Extractions of overretained teeth/ rootpieces etc.Serial extractions if crowding is severe. 4.Corrective orthodontic referral.
  40. Observation Clinical observation reveals that if the physiologic spaces are between 2 -6mm there is a fifty percent chance that the crowding will self resolve. If the physiologic spaces are more than 6 mm then there will be no crowding.
  41. Transient Incisor liability occurs because the mesiodistal dimentions of the permanent incisors is much larger than the deciduous teeth.
  42. SELF CORRECTED BY: 1.Existing interdental spaces 2.Intercanine arch growth 3.Labial positioning of incisors
  43. CAUSES OF CROWDING IN MODERN DENTITIONS : 1.Inherited discrepancy between tooth size and jaw size 2.Increase in cross racial marriages 3.Change in dietary habits 4.Early loss of primary teeth 5.Over retained deciduous teeth.
  44. Classification of Crowding 1.Premature tooth loss but no space loss 2.Localised crowding : less than 3 mm 3.Localised crowding : more than 3 mm 4.Moderate generalized crowding : less than 4 mm 5.Severe generalised crowding : 4 to 9 mm 6.Very severe generalised crowding : more than 10mm
  45. Premature Tooth Loss With Adequate Space: Space Maintenance Early loss of a primary tooth presents a potential alignment problem because drift of permanent or other primary teeth is likely unless it is prevented. Space maintenance is appropriate only when adequate space is available and all unerupted teeth are present and at the proper stage of development. If there is not enough space or if succedaneous teeth are missing, space maintenance alone is inadequate.
  46. PREMATURE TOOTH LOSS BUT ADEQUATE SPACE 1. Band & loop space maintainer 2. Partial denture space maintainer 3. Distal shoe space maintainer 4. Lingual arch space maintainer 5. Mild to moderate crowding of incisors with adequate space.
  47. Band and Loop Space Maintainers The band and loop is a unilateral fixed appliance indicated for space maintenance in the posterior segments The simple cantilever design makes it ideal for isolated unilateral space maintenance.
  48. Because the loop has limited strength, this appliance must be restricted to holding the space of one tooth and is not expected to accept functional forces of chewing. Although bonding a rigid or flexible wire across the edentulous space has been advocated as an alternative, this has not proved satisfactory clinically. It also is no longer considered advisable to solder the loop portion to a stainless steel crown because this precludes simple appliance removal and replacement. Teeth with stainless steel crowns should be banded like natural teeth
  49. If a primary second molar has been lost, the band can be placed on either the primary first molar or the erupted permanent first molar. Some clinicians prefer to band the primary tooth in this situation because of the risk of decalcification around any band, but primary first molars are challenging to band because of their morphology, which converges occlusally and makes band retention difficult. A more important consideration is the eruption sequence of the succedaneous teeth.
  50. The primary first molar should not be banded if the first premolar is developing more rapidly than the second premolar, because loss of the banded abutment tooth would require replacement of the appliance
  51. Before eruption of the permanent incisors, if a single primary molar has been lost bilaterally, a pair of band and loop maintainers are recommended instead of the lingual arch that would be used if the patient were older. This is advisable because the permanent incisor tooth buds are lingual to the primary incisors and often erupt lingually. The bilateral band and loops enable the permanent incisors to erupt without interference from a lingual archwire At a later time the two band-and-loop appliances can be replaced with a single lingual arch if necessary.
  52. The partial denture is most useful for bilateral posterior space maintenance when more than one tooth has been lost per segment and the permanent incisors have not yet erupted. In these cases because of the length of the edentulous pace band and loop space maintainers are contraindicated and the lingual position of the unerupted permanent incisors and their likely lingual position at initial eruption make the lingual arch a poor choice. The partial denture also has the advantage of replacing occlusal function.
  53. Another indication for this appliance is posterior space maintenance in conjunction with replacement of missing primary or delayed permanent incisors, for esthetics. Anterior space maintenance is unnecessary because arch circumference generally is not lost even if the teeth drift and redistribute the space, so replacement of missing anterior teeth is done solely to improve appearance. This has social advantages even for young children.
  54. Distal Shoe Space Maintainers The distal shoe is the appliance of choice when a primary second molar is lost before eruption of the permanent first molar. This appliance consists of a metal or plastic guide plane along which the permanent molar erupts. The guide plane is attached to a fixed or removable retaining device.
  55. When fixed, the distal shoe is usually retained with a band instead of a stainless steel crown so that it can be replaced by another type of space maintainer after the permanent first molar erupts. Unfortunately, this design limits the strength of the appliance and provides no functional replacement for the missing tooth. If primary first and second molars are missing, the appliance must be removable and the guide plane is incorporated into a partial denture because of the length of the edentulous span. This type of appliance can provide some occlusal function.
  56. To be effective, the guide plane must extend into the alveolar process so that it contacts the permanent first molar approximately l mm below the mesial marginal ridge, at or before its emergence from the bone. An appliance of this type is tolerated well by most children, but is contraindicated in patients who are at risk for subacute bacterial endocarditis or are immuno- compromised, because complete epithelialization around the intra-alveolar portion has not been demonstrated.
  57. Careful measurement and positioning are necessary to ensure that the blade will ultimately guide the permanent molar. Faulty positioning is the most common problem with this appliance
  58. Distal Shoe Space Maintainer
  59. Distal Shoe Space Maintainer
  60. Measurement on the radiograph: The outline of the distal shoe is designed on radiograph. The mesio-distal length of the horizontal position of the distal shoe should be as long as the maximum width of the second primary molar and vertical height should be about 1 mm under the mesial contour of the unerupted first permanent molar
  61. Distal Shoe Space Maintainer Intra alveolar appliance Molar guidance appliance. Indication: Loss of ‘E; before eruption of ‘6’
  62. Lingual Arch Space Maintainers A lingual arch is indicated for space maintenance when multiple primary posterior teeth are missing and the permanent incisors have erupted.
  63. A conventional lingual arch, attached to bands on the primary second or permanent first molars and contacting the maxillary or mandibular incisors, prevents anterior movement of the posterior teeth and posterior movement of the anterior teeth.
  64. A lingual arch space maintainer is usually soldered to the molar bands but can be removable, depending on the number of adjustments anticipated and the care of the appliance expected from the patient. Removable lingual arches (e.g.,those that fit into attachments welded onto the bands) are more prone to breakage and loss.
  65. Regardless of whether it is removable, the lingual arch should be positioned to rest on the cingula of the incisors, approximately 1 to l.5 mm off the soft tissue, and should be stepped to the lingual in the canine region to remain away from the primary molars and unerupted premolars. The most common problems with lingual arches are distortion, breakage and loss. Careful instructions to parents and patients can reduce these problems.
  66. Maxillary lingual arches as space maintainers are not familiar to many clinicians but are contraindicated only in patients whose bite depth causes the lower incisors to contact the archwire on the lingual of the maxillary incisors. When bite depth does not allow use of a conventional design, either the Nance lingual arch or a transpalatal arch can be used.
  67. The Nance arch is an effective space maintainer, but soft tissue irritation can be a problem. The best indication for a transpalatal arch is when one side of the arch is intact and several primary teeth are missing on the other side. In this situation, the rigid attachment to the intact side usually provides adequate stability for space maintenance. When primary molars have been lost bilaterally however, both permanent molars may tip mesially despite the transpalatal arch, and a conventional lingual arch or Nance arch is preferred.
  68. Lingual Arch
  69. Localized Space Loss (3mm or less): Space Regaining After premature loss of a primary tooth, space may be lost from drift of other teeth before a dentist is consulted. Repositioning the teeth to regain space rather than just space maintenance is required. Up to 3 mm of space can be reestablished in a localized area with relatively simple appliances and a good prognosis
  70. Maxillary Space Regaining Generally, space is easier to regain in the maxillary than in the mandibular arch, because of the increased anchorage for removable appliances afforded by the palatal vault and the possibility for use of extraoral force (headgear). Permanent maxillary first molars can be tipped distally to regain space with either a fixed or removable appliance, but bodily movement requires a fixed appliance.
  71. Because the molars tend to tip forward and rotate mesiolingually, distal tipping to regain 2- 3mm often is satisfactory. A removable appliance retained with Adams' clasps and incorporating a helical fingerspring adjacent to the tooth to be moved is very effective. This appliance is the ideal design for tipping one molar.
  72. One posterior tooth can be moved up to 3 mm distally during 3 to 4 months of full-time appliance wear. The spring is activated approximately 2 mm to produce 1 mm of movement per month. The molar generally will derotate spontaneously as it is tipped distally.
  73. For unilateral bodily space regaining, a fixed intra-arch appliance is preferred. The excellent anchorage provided by the remaining teeth and palate can support the forces generated by a coil spring on a segmental archwire to produce distal movement of the molar on only one side, with good success.
  74. If bodily movement of both permanent maxillary first molars is necessary in regaining space, this can be accomplished by using a banded and bonded fixed appliance or headgear. Sometimes both molars need to be moved distally but one requires substantially more movement than the other.
  75. To accomplish this, an asymmetric facebow with a neckstrap attachment can be used. ’This will result in more movement on the side with the longer outer bow but will also move that tooth toward lingual crossbite. Asymmetric cervical headgear is neither as easyt o adjust nor as comfortable to wear as symmetric headgear, and it requires excellent patient compliance. For space regaining, it should be used only to deal with bilateral but asymmetric space loss-not true unilateral space loss, which is treated best with a removable or fixed appliances
  76. Regardless o f the method used to regain these limited amounts of space a, space maintainer is required when adequate space has been restored. A fixed space maintainer is recommended rather than trying to maintain the space with the removable appliance that was used for space regaining.
  77. Moderate and Severe Generalized Crowding For children with amoderate space deficiency, usually there is generalized but not severe crowding of the incisors. Other times the primary canines are lost to ectopic eruption of thelateral incisors and more severe crowding goes largely unrecognized. Usually when the permanent canines are erupting the real extent of the problem is noted.
  78. Children with moderate crowding and inadequate space in the early mixed dentition face one of two choices. Either the arch will need to be expanded to accommodate the permanent teeth or some permanent teeth will need to be extracted. Generally, if the lower incisor position is normal or somewhat retrusive, lips are normal or retrusive, the overjet is adequate, the overbite is not excessive, and there is good keratinized tissue facial to the lower incisors, some facial movement of the incisors and expansion can be accommodated. If facial movement is anticipated and the amount and quality of tissue is questionable, a periodontal consultation about a gingival graft is appropriate.
  79. Surgical or nonsurgical management of the tissue may be required prior to beginning the tooth movement. A conservative approach to this dilemma is to place a Iingual arch after the extraction of the primary canines and allow the incisors to align themselves. Ultimately the lingual arch or another appliance can be used to increase the arch length. A word of caution is necessary here. Clinical experi-ence indicates that a considerable degree of faciolingual irregularity will resolve if space is available, but rotational irregularity will not. If the incisors are rotated, severely irregular or spaced and early correction is felt to be important, a multiply bonded and banded appliance is indicated
  80. Lower incisor teeth usually can be tipped 1 to 2mm facially without much difficulty, which create sup to 4mm of additional arch length. If the overbite is excessive and the upper and lower incisors are in contact, however, facial movement of the lower incisors will not be possible unless the upper incisors also are proclined. When expansion by tipping the incisors facially is indicated, two methods should be considered.
  81. One is to use an active lingual arch
  82. The other method is to band the permanent molars, bond brackets on the incisors, and use a compressed coil spring on a labial archwire to gain the additional space.
  83. Early Treatment of Severe Crowding A key question, which remains unanswered, is whether early expansion of the arches (before all permanent teeth erupt) gives more stable results than later expansion (in the early permanent dentition). Partly in response to the realization that recurrent crowding occurs in many patients who were treated with premolar extractions a number of approaches to early arch expansion recently have regained some popularity in spite of a lack of data to document their effectiveness.
  84. Expansion can involve any combination of several possibilities: maxillary dental or skeletal expansion, moving the teeth facially or opening the midpalatal suture; mandibular buccal segment expansion by facial movement of the teeth; or advancement of the incisors and distal movement of the molars in either arch.
  85. A less aggressive approach is to expand the upper arch in the early mixed dentition, using a lingual arch (or perhaps a jack screw expander but this must be done carefully and slowly in the early mixed dentition) to produce dental and skeletal change
  86. Late Mixed Dentition Treatment for Severe Crowding One alternative is a functional appliance that incorporates lip and buccal shields or a lip bumper to reduce the resting pressure of the lips and cheeks and produce dental expansion Lip pads and buccal shields will lead to anterior movement of the incisors and buccal movement of the primary molars or premolars, which allows the teeth to align themselves along a larger arch circumference
  87. Last, several approaches can be used for either severe crowding or severe localized space loss that focus on increasing arch circumference by repositioning molars distally and often moving incisor forward sometimes with the same appliance and its side effects
  88. There are three major limitations to this approach: the long duration of treatment from the primary or early mixed dentition through the eruption of the permanet teeth; the possibility of creating unesthetic dentoalveolar protrusion; and the uncertain stability of the long-term result.
  89. Distal Molar Movement If bodily distal movement of one or both permanent maxillary first molars is necessary to adjust molar relationships and gain space, if there are adequate anterior teeth for anchorage, and if some anterior incisor movement can be tolerated, several appliances can be considered. All are built around the use of a heavy lingual arch, usually with an acrylic pad against the anterior palate to provide anchorage.
  90. Extraoral Appliances To tip or bodily move molars distally, extraoral force via a facebow to the molars is the most effective and straightfor- ward methods The force is directed specifically to the teeth that need to be moved, and reciprocal forces are not distributed on the other teeth that are in the correct positions. The force should be as nearly constant as possible to provide effective tooth movement and should be light because it is concentrated against only two teeth. The more the child wears the headgear,the better; 14 to 16 hours per day is minimal. Approximately100gm of force per side is appropriate.
  91. Mandibular Space Regaining
  92. LOCALISED SPACE LOSS : LESS THAN 3 MM SPACE REGAINING : In the mandibular Arch With Fixed appliances Lip Bumper Active lingual Arch In the Maxillary Arch Pendulum appliance
  93. 1/22/2023 Free template from
  94. REINFORCED ANCHORAGE……Nance button
  95. 1/22/2023 Free template from
  97. LIP BUMPERS 1.Removable lip bumper 2.Semifixed lip bumper 3.Denholtz appliance
  99. DENHOLTZ APPLIANCE It is a maxillary active semifixed lip bumper which incorporates open coil springs to induce a distalizing force on the maxillary first permanent molars
  101. LIP BUMPERS Lip bumpers are capable of the following:- Correct lip biting habit Upright lingually tipped lower incisors Correct mild crowding of anterior teeth Distalize the molar teeth Act as space regainer Help to re-inforce anchorage
  102. LIP BUMPERS They are screen like devices, which shield the dentition from perioral musculature. They are also referred to as Lip plumpers. They may be made for the maxillary or mandibular arch. The type of anchorage used is Intra- oral,Intramaxillary,Re-Inforced Muscular.
  103. CRANIUM
  104. Cervical pull head gear High pull head gear