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Slow maxillary expansion with extra slides /prosthodontic courses

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Slow maxillary expansion with extra slides /prosthodontic courses

  2. 2. CONTENTSCONTENTS • Introduction. • Slow Maxillary Expansion. • Classification of Slow Maxillary Appliances. • Indications and Contra-indications. • Advantages of SME. • Expansion Mechanics. • Appliances used for SME: Coffin Spring. Active Plate. W-Arch. Quad Helix. Schwartz Appliance. Y-plate. Minne Expander Appliance. NiTi Palatal Expander- NPE 1 NPE 2 Spring Jet. Spring Loaded Expander. m
  3. 3. • Expansion Screw/ Spring. • Expansion due to Slow Maxillary Appliances. • Changes in arch width perimeter. • Retention Period. • Relapse Tendencies. • Influence of Age on treatment outcome. • Skeletal Changes induced at Mid-palatal Expander. • Mandibular Influence of SME. • Histological Changes. • Comparison Between RME and SME. m
  4. 4. INTRODUCTIONINTRODUCTION Maxillary expansion treatments have been used for more than a century to correct maxillary transverse deficiency. Three expansion treatment modalities include Rapid Maxillary Expansion (RME), Slow Maxillary Expansion (SME) and Surgically-assisted Maxillary Expansion. Since each treatment modality has its advantages and disadvantages, controversy regarding their use exists. m
  5. 5. RME has been used extensively. However, clinical and histological studies have shown that relapse, micro-trauma of the temporomandibular joint and the mid-palatal suture, root resorption, tissue impingement and pain, and external root resorption are observed in RME procedures (Linder Aronson and Lindgren,1979; Barber and Sims,1981; Langford,1982).3,14 m
  6. 6. Hence, to eliminate these disadvantages and obtain increased physiological tissue reaction, SME has become more popular (Mew, 1983; Vardimon et al, 1991). 3 So, SME as an effective and biocompatible treatment of choice for maxillary arch expansion will be discussed. m
  7. 7. SLOW MAXILLARYSLOW MAXILLARY EXPANSIONEXPANSION Slow Maxillary expansion has traditionally been termed dento-alveolar expansion, which involves increase of arch width by movement of few teeth (or many teeth) although some skeletal changes can be observed. Slow maxillary expansion with a fixed split acrylic appliance was evaluated by Hicks (1978) with the use of frontal and lateral cephalograms. 5 The linear arch width changes are due to bodily translation of the teeth and the maxillary segments. m
  8. 8. The total expansion is half skeletal and half dental from the beginning (1:1). Total treatment time ranges from 2- 6 months. Large midline diastema never appears . It employs the use of lingual arch wire appliances with expansive capability. m
  9. 9. CLASSIFICATIONCLASSIFICATION REMOVABLE FIXED • Coffin Spring · Quad Helix. • Active Plate. · W-arch. • Schwartz Appliance. · Minne Expander. • Y-Plate. · NiTi Palatal Expander (NPE 1, NPE 2) · Spring Jet · Spring Loaded Expander. m
  10. 10. INDICATIONSINDICATIONS • For treatment of mild maxillary deficiency (arch expansion) in early or mixed dentition. • For correction of unilateral or bilateral crossbite(s) in early or mixed dentition. CONTRA-INDICATIONS • In adults where growth is completed. m
  11. 11. ADVANTAGESADVANTAGES 88 • It requires minimal adjustment throughout its use, and allows easy adjustment when necessary. •It delivers a constant physiologic force until the required expansion is obtained. •There is minimum tipping of anterior teeth. •Least strain is exerted on anchored teeth. •The appliance is light and comfortable to the patient. •It can be used for sufficient retention after the expansion . •Relapse tendencies are less. •Retention time is less. m
  12. 12. DISADVANTAGESDISADVANTAGES • Treatment time is long as compared to RME. m
  13. 13. Activation of expansion screw/ spring = One quarter turn (900 ) per week. The expansion rate is 0.4 - 1.1mm. per week. 5 To produce expansion at this rate, 2 to 4 lbs (10- 20 N) of force is optimal (depending on the age of patient). (Proffit)5, 16 The expansion of the maxillary dental arch is the result of dento-alveolar movement as well as splitting of the midpalatal suture and moving the maxillae apart.5 EXPANSION MECHANICSEXPANSION MECHANICS m
  15. 15. 1. COFFIN SPRING1. COFFIN SPRING1313 • Walter Coffin – 1875. • It is a removable appliance capable of slow dento-alveolar expansion • The appliance consists of an omega shaped wire of 1.25mm thickness, placed in the mid palatal region • The free ends of the omega wire are embedded in acrylic covering the slopes of the palate • The spring is activated by pulling two sides apart m
  16. 16. 2. ACTIVE PLATE2. ACTIVE PLATE 55 • Pierre Robin in 1902 was the first one who constructed a split plate which incorporated a screw. • Active plate - This serves as a base in which screws or springs are embedded and to which clasps are attached. • Most screws open 1mm per complete revolution, so that a single quarter turn produces 0.25mm of tooth movement. (Proffit) m
  17. 17. 3. W- Arch3. W- Arch1313 Ricketts - 1975Ricketts - 1975 • The W – arch is a fixed appliance constructed of 36 mil Stainless steel wire soldered to molar bands to avoid soft tissue irritation ,the lingual arch should be constructed so that it rests 1-1.5mm off the palatal soft tissue . • The w –arch is activated simply by opening the apices of w- arch and is easily adjusted to provide more anterior than posterior expansion ,or vice versa if this is desired . m
  18. 18. • The appliance delivers proper force levels when opened 3-4mm wider than the passive width and should be adjusted to this dimension before being inserted . • Expansion should continue at the rate of 2mm per month until the cross bite is slightly overcorrected. m
  19. 19. 4. QUAD-HELIX4. QUAD-HELIX 1313 (Rickets, 1978)(Rickets, 1978) • Quad-helix expansion appliance was popularized by Ricketts, 1978. • It is a modification of W- arch. • Depending on age of patient, quad helix can produce dento-skeletal (SME) or dental effects. m
  20. 20. INDICATIONSINDICATIONS • All cross- bites in which the upper arch needs to be widened. • Mild expansion in the mixed dentition or permanent dentition, which frequently exhibits lack of space for the upper laterals. • Class III – Expansion needed. • Class II cases . • Thumb sucking or Tongue thrusting cases • Cleft palate conditions either unilateral or bilateral. m
  21. 21. • It is fabricated from .038" blue Elgiloy wire and is either soldered to the upper first molar or bent to fit into a lingual sheath. • The lingual arm of the appliance extends to the premolar or cuspid. • The posterior helix is beveled slightly to lay against the palatal vault and is as close to the upper molar as possible to prevent impingement on the soft tissue. The anterior helices are brought as far forward as possible. Anterior Bridge Posterior Bridge m
  22. 22. • The anterior segment of the W expansion should be as wide as possible so that the appliance is maintained away from the swallowing position of the tongue. • All the helices should roll to the top and should be tightly wound to increase their mechanical efficiency. • Quad-helix appliance applies approx 5N of force on the dental structures.16 m
  23. 23. The quad-helix appliance demonstrating the ability forThe quad-helix appliance demonstrating the ability for lateral expansion of the maxillary buccal segments aslateral expansion of the maxillary buccal segments as well as a rotation of the banded molar.well as a rotation of the banded molar. m
  24. 24. ACTIVATION OF QUAD HELIXACTIVATION OF QUAD HELIX Quad Helix can be pre-activated by stretching the two molar bands apart prior to cementation or by using three prong pliers after cementation. • Initial activation of quad-helix appliance during insertion. In Class II cases, most of the arch form change should occur in the anterior portion of the buccal segments. As the upper molars are expanded approximately 1cm per side, the anterior segments are expanded approximately 3cm overall. An initial expansion of 8mm will produce approx. 14 ounces of force. • Intra-oral activation of quad-helix appliance. When an intraoral bend is made in the anterior segment to increase the amount of overall expansion, a reciprocal bend must be made in the posterior section in order to compensate for the tendency for mesial rotation of the upper molars. m
  25. 25. EXPANDS MOLARS m
  27. 27. For rotating the molars. For expanding arch. For breaking a finger habit, and providing for headgear attachment. JCO, 1979, FEB m
  28. 28. 5. SCHWARTZ APPLIANCE5. SCHWARTZ APPLIANCE 55 SCHWARTZ 1966SCHWARTZ 1966 • The appliance basically consists of an acrylic plate with a midline split incorporating one / two expansion screws, the acrylic does not cap the occlusal surface / incisal edges. • The appliance in addition has a labial bow & is retained by means of Adam's / ball end clasps. m
  29. 29. 6. Y PLATE6. Y PLATE 55 • The acrylic sectioning is done in a Y shape. The appliance incorporates two screws on each side. • The incisor segment is expanded anteriorly whereas the posterior segment moves laterally. m
  31. 31. • Minne Expander is a fixed, Slow maxillary expansion appliance cemented to the first permanent molars and first premolars. • It is used to increase maxillary width by activating the palatal compressed-coil spring. • The Minne-expander appliance spring applies forces of up to 10 N (2 pounds). (Hicks, 1978)16 • Each incremental activation of the Minne-expander produces one half the amount of expansion produced by the jackscrew appliances (0.125 mm. as compared to 0.25 mm.) 16 • It is more physiologic because of the lessened effect to the maxillary sutures and the consequent healing and repair of the latter during the expansion procedure. Disadvantage: Prevents proper oral hygiene maintenance. m
  32. 32. 8. NiTi PALATAL EXPANDER8. NiTi PALATAL EXPANDER77 • It is a tandem-loop, nickel titanium, temperature-activated palatal expander that produces light, continuous pressure on the midpalatal suture while simultaneously uprighting, rotating, and distalizing the maxillary first molars. (NPE – 1) By- Wendell, Arndt, 1993 m
  33. 33. • It has adjustable stainless steel extensions which are inserted into standard horizontal lingual sheaths that are spot- welded to the molar bands. • A locking indent on the lingual attachment holds the expander to the molar band for patient safety. m
  34. 34. The nickel titanium expander has a transition temperature of 94°F. When it is chilled before insertion, it becomes flexible and can easily be bent to facilitate placement. As the mouth begins to warm the appliance, the metal stiffens, the shape memory is restored, and the expander begins to exert a light, continuous force on the teeth and the midpalatal suture. • Nickel titanium expanders come in eight different intermolar widths, ranging from 26mm to 47mm, that generate forces of 180-300g. The 26-32mm sizes have softer wires that produce lower force levels for younger patients m
  35. 35. A. Passive appliance. B. Initial activation and insertion for expansion and distal molar rotation. C. After expansion and rotation correction. m
  36. 36. ADVANTAGES: • The nickel titanium palatal expander is self-activated by body temperature. • It automatically expands to its predetermined shape. • Requires little manipulation by the clinician. • Produces a light, constant pressure on the teeth and midpalatal suture. • It is safe and permits the patient to mitigate the pressure response. m
  37. 37. 9. NiTi PALATAL EXPANDER9. NiTi PALATAL EXPANDER 88 By-By- ROBERT MARZBAN, NANDA,1999ROBERT MARZBAN, NANDA,1999 • It delivers a uniform, slow, continuous force for maxillary expansion, molar rotation and distalization, and arch development. • This appliance expands at a rate that maintains tissue integrity during repositioning and remodeling of the teeth and bone. • As the palate expands, regeneration matches the rate of expansion. (NPE 2) m
  38. 38. m
  39. 39. • The NPE2 is made up of an innovative lingual attachment with .036" Ortholoy arms and molar loops for unilateral and bilateral adjustments. • A locking indentation in the lingual attachment ties the appliance securely to the maxillary molar band. • To prevent removal or accidental dislodging, the appliance should also be tied in with ligatures. m
  41. 41. • The expander is available in sizes from 26mm to 44mm in 2mm increments. • The appropriate expander is selected as follows- Measure across the mandibular arch between the central pits of the first molars , then subtract 4mm to determine the size of NPE2 to use. m
  42. 42. • The nickel titanium expander has a transition temperature of 94°F. • Seating the Appliance: After trial, the band of expander is coated with triple cure GIC It is sprayed with a ‘tetrafuoroethane refrigerant spray’ before insertion. As the mouth begins to warm the appliance, the metal stiffens and begins to exert a light, continuous force on the teeth and the midpalatal suture . • The NPE2 delivers a force of 350g in 3mm increments. If a 4mm expansion appliance is placed, the force will initially be higher, but will return to 350g once 3mm of expansion has occurred. • Because the force application is preprogrammed, it is self-limiting. m
  43. 43. •Majority of palatal expansion patients need at least 4mm of expansion at the maxillary first molars (2mm per side). An additional 2-3mm can be gained by adjusting the palatal Nitanium loop of the NPE2. •If more than 8mm of expansion is needed, two separate expanders may need to be used in sequence. m
  44. 44. • Other functions of NPE 2- • Ortholoy arms of appliance do not contact bicuspids at initial placement. After molar expansion, distal rotation, and distalization, Ortholoy arms contact bicuspids. The appliance initially appears to move palatally, but as it expands, it will move occlusally. This will produce a lower tongue posture that can promote expansion and transverse growth in the mandibular arch. • The NPE2 frees the growth restriction of posterior functional crossbite and provides space for impacted and causes orthopedic changes in the maxilla and often mandibular repositioning. • After expansion, the NPE2 can act as a stabilizing wire for molar intrusion. m
  45. 45. FUNCTIONS OF NPE 2: • Unilateral molar correction. • Unilateral posterior crossbite correction. • Bilateral or unilateral contraction with smaller appliance sizes. • Distal rotation and expansion of both the first molars and second bicuspids. • Distal rotation and expansion of the molars and second bicuspids, followed by initial cuspid retraction. • Leveling, alignment, and rotation of the incisors while the buccal segments are expanded—a fixed, three-way sagittal appliance. m
  46. 46. • Leveling, alignment, and rotation of the buccal segments while the molars are expanded and the incisors are retracted. • Retention of expansion while the incisors are advanced overexpansion of the palatal Nitanium loop in cleft palate cases m
  47. 47. Advantages of the Nitanium Palatal Expander2 overAdvantages of the Nitanium Palatal Expander2 over traditional rapid palatal expanders.traditional rapid palatal expanders. • Better physiologic response and stability. • Preprogrammed to deliver the exact amount of expansion required and to stop at that point. • No severe suture splitting. • Less tipping of abutment teeth. • Can influence the direction of maxillary and mandibular growth. • Rotates molars buccally or distally. • Can be used for anchorage. • Shorter retention m
  48. 48. • Placed at the chair, without laboratory procedures. • Individually adjustable molar loops. • Does not require frequent operator or patient adjustments. • Built-in safety retention system. • Less patient discomfort. • Allows the patient to adjust the wire temperature to mitigate pressure. • Less effect on speech and eating. • Hygienic. m
  49. 49. 10. SPRING JET10. SPRING JET 77 Aldo Carano, 1999Aldo Carano, 1999 • The active components of the spring jet are soldered or attached to the molar bands . • The transpalatal arch replaced by a telescopic unit with NiTi coil spring and a lockscrew • . LOCKSCREW m
  50. 50. • The telescopic unit is placed high 5 mm up from center of molar bands so that the line of force passes close to the center of resistance of maxillary teeth . Hence, tipping is prevented at molars and pre-molars. • But it should be 1.5 mm away from palatal tissue to avoid irritation to the tongue. BALL STOP LOCKSCREW m
  51. 51. Activation: •By moving the lock screw horizontally along the telescopic tube. • A ball stop on the transpalatal wire allows the spring to be compressed. Force Application: • Two coil springs can be used - Spring with force application of 240g – for mixed dentition, and 400g – for permanent dentition. • Force levels tend to decrease as the springs, hence, lockscrew is designed to maintain full spring compression to assure constant force level through out the expansion. m
  52. 52. ADVANTAGES- •The Spring Jet Appliance allows a constant expansion force as long as necessary. •After correction, the appliance can easily be inactivated and used as a retainer. •The molars will move with little change in angulation, and can be used for anchorage during correction of the other dental inclinations. m
  54. 54. 11. SPRING LOADED EXPANDER11. SPRING LOADED EXPANDER (SLE) – By Leone, 2003(SLE) – By Leone, 2003 1010 •The SLE is a new Orthodontic device designed to provide expansion of the upper arch by means of pre – determined, continuous forces. •It maintains an accurate control over the direction and intensity of the forces applied when Maxillary Dentoalveolar Expansion (SME) is carried out in patients whose growth has almost finished. m
  55. 55. • Nickel-Titanium spring coils were added to the arms of the expander to absorb the intensity of the force generated by its screw. • SLE may contain either a 500g or a 800g. Coil spring that provides a continuous force, sufficient to promote a Dental-Alveolar re-modelling that is biologically ideal and biomechanically controlled. • The screw has a self-stop mechanism at the end of expansion to prevent it from disassembling in case of excessive activation. m
  56. 56. 1. SLE is fully compressed 2. Spring coil completely open at the start of treatment. (passive). 3. SLE has been re-activated 4. 8mm is the maximum expansion spring coil is compressed again. obtainable with the SLE. m
  57. 57. • The device is activated on average, 4-8 activations (0, 4-0, 8 mm) every 6 weeks. • A different number of activations will not alter the intensity of the force delivered to the dental structures, as this stays constant (500 or 800g.) • There is no risk of over-expansion as the screw, upon reaching the pre-determined expansion, will become passive. • However, by changing the activation pattern, Rapid Maxillary Expansion can also be achieved using SLE. m
  58. 58. • Easy, less activations are required. • Tipping is easy to control through bodily vestibular movement. • An accurate monitoring of expansive movement is possible. • Occlusal forces cannot influence or alter the activation, so safety is certain. • Only continuous, predetermined forces work in between appointments. • If patient misses an appointment, there is no harm as there can be no over-expansion. ADVANTAGESADVANTAGES m
  59. 59. EXPANSION SCREW/ SPRINGEXPANSION SCREW/ SPRING Slow Expansion can be accomplished either by activating a special spring designed to produce desired 2 to 4 lbs of force, or by turning the typical jackscrew once per week. (Proffit) The jackscrew used is similar to the one used for rapid maxillary expansion but with a comparatively smaller pitch. m
  60. 60. 1. EXPANSION SCREW1. EXPANSION SCREW • The baseplate in an active plate, when is used as a working part, is divided and driven apart by screws. • A typical screw consists of an oblong body divided into two halves, each half has a threaded inner side to receive one end of a double ended screw. • The screw has a central bossing that has four holes. These holes receive a key to activate the screw. A single adjustment of the screw brings about 1/4 rotation causing 0.18mm linear m
  61. 61. The screw when turned 900 , will move the parts of plate apart 0.2mm thereby narrowing the periodontal membrane 0.1mm on each side without interrupting any blood supply. Thus, arch expansion is brought about in a harmless and effective way. Different Screws for particular action of plate are: • Encased Expansion Screw. • Skeleton – Type Expansion Screw. • Special Screws: • Encased Pull Screw. • Encased Screw with Incorporated Spring: Hausser • For Expansion in Three Dimensions: Bertoni. • Eccentric m
  62. 62. 2. EXPANSION SCREW2. EXPANSION SCREW They are sturdy and resist stress. They are used in upper expansion plate. When screw is expanded, the spiral is pulled out of acrylic. m
  63. 63. 3. SKELETON TYPE EXPANSION SCREW3. SKELETON TYPE EXPANSION SCREW The spiral embedded in acrylic plate does not turn back. Broader screw is used for maxillary expansion plate and narrower for mandibular expansion plates. Smaller size also causes effective distal movement of teeth. FOR MAXILLARY m
  64. 64. 4. SCREW OF HAUSSER: ENCASED SCREW WITH4. SCREW OF HAUSSER: ENCASED SCREW WITH INCORPORATED SPRINGINCORPORATED SPRING1313 It is the screw that activates limited spring action. A quarter turn of this screw will expand both the sides by 0.1mm. The spring incorporation will limit the pressure on both sides and further keeps it constant. m
  65. 65. 5. SCREW OF BERTONI5. SCREW OF BERTONI It causes forceful expansion of active plate in all the three directions. m
  66. 66. 6. ECCENTRIC SCREW: FOR FANWISE6. ECCENTRIC SCREW: FOR FANWISE MAXILLARY EXPANSIONMAXILLARY EXPANSION The screw is made up of two parts : a hinge, and a special screw permitting slight rotation inside the disk. When opened, the two parts of plate come together at posterior end while anterior part opening fanwise about 4mm. With a special screw, fanwise opening can be increased to 8mm. m
  67. 67. EXPANSION DUE TOEXPANSION DUE TO SLOW MAXILLARY APPLIANCESSLOW MAXILLARY APPLIANCES Upon the application of transverse biomechanical forces, initial changes involve the lateral tipping of the posterior maxillary teeth as the periodontal and palatal soft tissues are compressed and stretched. If applied transverse forces are of sufficient magnitude to overcome the bio-elastic strength of sutural elements, orthopedic separation of the maxillary segments takes place (Cleafill,1965; Hicks, 1978, Cotton, 1978, Storey, 1973). 4 The separation and repositioning of the palatal segments continue until the force distribution is reduced below the tensile strength of the sutural elements (Storey, 1973; Barber, 1981).14 m
  68. 68. Reorganization and remodeling of the sutural connective and skeletal tissues may then proceed in the stabilization of the expanded maxillary arch. Subsequent orthodontic movements occur through bodily translation as the compressed buccal alveolar plate resorbs at the root-periodontal interface from continued force application. (Storey, 1973 ; Barber, 1981).14 No diastema occurs at the end of slow maxillary expansion.3 Similar to RME, palatal expansion is greater at the alveolar crest and less at the palatal vault, and maxillary bones swing laterally with the center of rotation near the fronto-nasal suture (Storey, 1973). m
  69. 69. CHANGES INCHANGES IN ARCH WIDTH PERIMETERARCH WIDTH PERIMETER 33 • Mossaz- Joelson and Mossaz (1989)3 reported that inter-canine width showed a smaller increase than inter-molar width in the maxillary arch both in bonded and banded Minne Expander SME devices. • Arch perimeter gain through treatment 0.60times the amount of posterior expansion for SME . (Akkaya et al, 1998) • SME was found to produce increase in maxillary arch perimeter at the rate of 0.52 times the change in 1st pre-molar width at the end of retention period. (Akkaya et al, 1998) m
  70. 70. • Maxillary arch-width increases ranged from 3.8mm to 8.7mm with slow expansion of as much as 1mm per week, using 900g of force (Hicks, 1978). m
  71. 71. PERIOD OF RETENTIONPERIOD OF RETENTION44 Retention periods of 3 months or less are reported to be adequate in allowing sutural regeneration and stabilization of slowly separated maxillary segments. (Storey, 1973; Eckstrom,1973; Hicks, 1978; Bell, 1981) m
  72. 72. RELAPSE TENDENCIESRELAPSE TENDENCIES The slower expansion techniques have been associated with a more physiological adjustment to maxillary expansion, producing greater stability and less relapse potential than in rapid expansion procedures (Krebs, 1959; Krebs, 1964; Issacson, 1964; Skieller, 1964; Cleall, 1965; Zimring, 1965; Cotton, 1978; Hicks, 1978; Storey, 1978). This is due to the lower forces applied on the suture over a longer period, which permits a continuous adaptation of the tissues to the skeletal and dental changes. Hicks,1978 reported that the relapse was 10 to 23 percent with fixed retention, 22 to 25 percent with removable retention, and 45 percent with no retention following SME. Reduced skeletal relapse tendency was also observed in the slow maxillary expansion cases due to reduced stress within the involved tissues and in maintenance because of the sutural integrity (Storey, 1973; Cotton, 1978; Mossaz- Joelson and Mossaz, 1989) m
  73. 73. However, overexpansion is necessary to compensate for the tendency of the posterior teeth to return to their pretreatment axial inclinations. (Storey, 1973) m
  74. 74. INFLUENCE OF AGE ONINFLUENCE OF AGE ON TREATMENT OUTCOMETREATMENT OUTCOME The increase in rigidity of the facial skeleton with advancing age restricts bony movement remote from the appliance of expansion.(Chaconas, Caputo, 1982)16 However, expansion can be carried out just before and during the pubertal growth spurt when response is increased. Expansion lingual arches that produce 1-2lbs of force, open the suture in young children, but in adolescents these appliances produce more dental than skeletal expansion. (Proffit) 5 In general, the effect of expansion of the dental arch on the maxillary bases diminishes as age advances. m
  75. 75. A direct relationship between increased resistance to skeletal expansion and increasing patient age has been associated with the formation of mechanical interlockings at maxillary articulations as early as 12 to 13 years of age (Isaacson, 1964; Melsen, 1972).16 Also, the enhanced skeletal response in younger age groups has been associated with a greater cellular activity in the growing suture (Cleall, 1965; Cotton, 1978; Storey, 1955; Ten Cate, 1977). 3 SME in adults- During treatment of adults, the intermaxillary and surrounding sutures are less patent and, in some cases, fused, which makes orthopedic results difficult to obtain. 16 There is an increase in interdental width along with severe tipping of the posterior teeth in adults with SME. Increased activation creates minimal expansion in such cases. However, aggressive activation causes increased tipping of the posterior teeth, especially those used for anchorage. m
  76. 76. Bills (1981) stated that, although the literature (Hicks, 1978; Barber and Sims, 1981) has revealed that fixed appliances may effectively increase maxillary width during the deciduous and mixed dentitions, older patients may require the higher force systems of rapid expansion procedures or surgical intervention (Bell and Turvey, 1974; Kennedy et al., 1976). 16 m
  77. 77. SKELETAL CHANGES INDUCED ATSKELETAL CHANGES INDUCED AT MID-PALATAL SUTUREMID-PALATAL SUTURE 44 Skeletal expansion involves separation of the right and left halves of the maxilla at the midpalatal suture; dental expansion results from buccal tipping of the maxillary posterior teeth (Krebs, 1958; Haas, 1961; Wertz, 1970; Melsen, 1972; Cotton, 1978; Hicks,1978). Skieller, 1964 demonstrated that 20% of the widening of the dental arch induced by slow maxillary expansion devices in younger patients was due to sutural separation. The slow expansion procedures increase the percentage of orthodontic movements as the tensile strength of the suture elements is not overwhelmed. (Moyers, 1974; Storey, 1973, Hicks, 1978) m
  78. 78. Sutural separation occurs at a rate allowing the maintenance of sutural integrity during maxillary repositioning and remodeling (Storey, 1973; Ekström et al., 1977; Cotton, 1978), with less traumatic disruption, a greater reparatory reaction, and greater sutural stability than rapid expansion of sutures. 8 The rate of midpalatal suture separation by slow expansion systems apparently allows a more physiologically tolerable response by the sutural elements than the disruptive nature of rapidly expanded maxillary segments (Bell, 1982).4 Ekstrom et al (1977) reported that the slowly expanded suture normally becomes well organized by mineralized tissue in about 30 days and is established within 3 months.2 m
  79. 79. MANDIBULAR INFLUENCE OF SLOW MAXILLARY EXPANSION11 It has been observed that the position of the lower dentition may be influenced more by maxillary skeletal morphology than by the size and shape of the mandible itself (McNamara, 1999). The widening of the lower arch is due primarily to decompensation, an uprighting movement of the lower posterior teeth, which often have erupted into occlusion in a more lingual orientation because of the associated constricted maxilla. Haas observed that the mandibular arch tended to follow the maxillary teeth by tipping laterally (Haas, 1961). m
  80. 80. The neuromuscular adaption of the mandible to the maxilla in slow expansion allows a normal vertical closure.(Bell, Le Compte, 1981)4 Patients whose maxillae had been expanded orthopedically showed a post-retention increase of 1.1 mm in the mandibular intercanine dimension (Sandstrom et al., 1988; Adkins et al., 1990). m
  81. 81. HISTOLOGICAL CHANGESHISTOLOGICAL CHANGES44 Due to slow rate of suture separation, the tearing and hemorrhaging are minimized. The increased sutural and skeletal response has been related to growth periods of high cellular activity with increased reparability potential and treatment prior to the formation of bony interlockings at maxillary articulations. Cleall, 1965; Cotton, 1978; Storey, 1955; Ten Cate, 1977 reported greater cellular activity in the growing suture.4 Brin and co-workers, measured the cyclic nucleotides as indicators of cellular activity and new bone formation, and reported that the sutural bone cells of young cats were more responsive to palatal expansion forces than the corresponding cells of old animals.2 No midline diastema appears during treatment since the treatment time for SME is longer that allows trans-septal fibers to tip the crowns before end of active m
  82. 82. SLOW MAXILLARY RAPID MAXILLARYSLOW MAXILLARY RAPID MAXILLARY EXPANSIONEXPANSION 1.Indicated for correcting transverse maxillary deficiencies during early or mixed dentition. 2.Biomechanical Effect- Orthodontic (mainly) 3. Light Forces are applied per activation is- 2-3 lbs (10- 20N).16 4.Screw Activation: Quarter turn per week. 1.Indicated for correcting transverse maxillary deficiencies between 13- 15yrs. Of age. 2. Orthopedic 3. Heavy Forces are applied per activation is approx. 10-20lbs (100N).16 4.Screw Activation: Up to 15 yrs: 90° rotation once in the morning & once in the evening. 15-20 yrs : 45° activation m
  83. 83. SLOW MAXILLARY RAPID MAXILLARYSLOW MAXILLARY RAPID MAXILLARY EXPANSIONEXPANSION 5. Rate of expansion- 0.4- 1.1 mm per week. 6. Duration of treatment: 2 - 6 months. 7.No transient diastema appears during treatment. 8.Low relapse tendencies after treatment. Hence, shorter retention periods: 1-3 months. 9.Reduced evidence of tooth tipping and decreased residual loads within the expanded segments reported. 5. Rate of expansion-0.5- 1 mm per day. 6. Duration of treatment: 1-4 wks. 7. Transient diastema appears during treatment. 8. Higher relapse tendencies after treatment. Hence, greater retention periods: 3-6 months. 9. Mesial tipping of incisors and lateral tipping of maxillae. Increased residual loads reported within expanded m
  84. 84. SLOW MAXILLARY RAPID MAXILLARYSLOW MAXILLARY RAPID MAXILLARY EXPANSIONEXPANSION 10. Rate of midpalatal suture separation allows a more physiologically tolerable and adaptive response by the sutural elements. 11. Histologically, tear and haemorrhage of vessels is less. 12. Arch perimeter gain through treatment is about and 0.60 times the amount of posterior expansion for SME . (EJO) 3 13.Increase in inter-canine width – less than that in RME. 14. Increase in maxillary arch perimeter is at the rate of 0.52 times the change in 1st pre- molar width at the end of 3 10. Rate of midpalatal suture separation of rapidly expanded maxillary segments is disruptive in nature . 11.Histologically, tear and haemorrhage of vessels is more. 12. Arch perimeter gain through treatment is about 0.65 times the amount of posterior expansion. (EJO) 3 ???? 13.Increase in inter-canine width – higher than that in SME. 14. Increase in maxillary arch perimeter is at the rate of 0.54 times the change in 1st pre- molar width at the end of retention period. m
  85. 85. Skeletal and dental expansion rates in slow expansion treatment over a 10-week period. The amount of skeletal and dental changes is consistent through the total observation period (Hicks 1978) 5 Skeletal and dental expansion rates in rapid maxillary expansion treatment over a 10-week period. The skeletal reaction is highest at the start of treatment and decreases constantly with time. Conversely, the dental component of the movement is rather low at the beginning but increases with treatment time (Hicks, 1978) m
  86. 86. •Erlangung des and Zahnmedizinischen et al carried out a retrospective study in 2004 to evaluate the stability of orthodontically corrected unilateral crossbite by comparing the patients treated either with rapid maxillary expansion (RME) or with slow expansion devices in the early (mean age: 7.2 years) or in the late mixed dentition (mean age: 9.9 years). •Maxillary expansion was performed either with a removable expansion plate (n= 50), or with a rapid maxillary expansion technique (RME) using a tissue-borne, fixed, split acrylic appliance (n= 50). • The slow expansion appliance (n= 50) was activated by 0.2 mm per week and the result was retained for 3 to 6 months after expansion had been achieved. •The RME device (n= 50) was activated twice a day (0.4 mm) and the treatment result was retained for a minimum of m
  87. 87. The observation periods were approximately 8 years for the early-treatment groups and 6.5 years for the late-treatment groups. The mean change was 1.1 ± 2.8 mm in the maxillary interpremolar arch width and 2.3 ± 2.1 mm in the intermolar arch width in the slow expansion groups. The RME groups showed a mean change of 3.6 ± 2.7 mm in interpremolar arch width and of 3.8 ± 2.7 mm in intermolar arch width; this was significantly greater than in the comparison groups. •The transverse increase was significantly greater for patients treated with RME as compared to those treated with SME. m
  88. 88. BIBLIOGRAPHYBIBLIOGRAPHY 1. Arndt, W.V.- Nickel titanium palatal expander, J. Clin. Orthod. 1993(27):129-137. 2. Corbett, M.C.-Slow and continuous maxillary expansion, molar rotation, and molar distalization, J. Clin. Orthod. 1997,31,(3):253- 263,. 3. Akkaya S, Lorenzon S, Ucem TT. Comparison of dental arch and arch perimeter changes between bonded rapid and slow maxillary expansion procedures. Eur J Orthod, 1998;20(3):255-61. 4. Bell RA. A review of maxillary expansion in relation to rate of expansion and patient’s age. Am J Orthod 1982;81(1):32-7. 5. Proffit WR, Fields HW. Contemporary orthodontics. 3rd ed. St. Louis: Mosby; 2000:508-11. 6. Bishara SE, Staley RN-Maxillary expansion: Clinical Iimplications. Am J Orthod Dentofacial Orthop, 1987, 91 m
  89. 89. 7. Aldo Carano: The Spring Jet for Slow Palatal Expansion, JCO, 1999, 33 (9): 527- 31 8. Robert Marzban, Ravindra Nanda, Nickel Titanium Palatal Expander , JCO, 1999,32 (8): 431-441. 9. William L. Wilson Modular 3D Lingual Appliances Part 1 Quad Helix - JCO, 1983 (11): 761-66. 10. Dr. Claudio lanteri, Dr. Fabrizio Lerda, Cuneo, Italy - Slow Maxillary Expansion using a new spring – loaded device. 11. Roberto, Antonio Carlos: Mandibular Behavior with Slow and Rapid Maxillary Expansion in Skeletal Class II Patients, Angl Orthod, 2007, 77 (4): 625-31. 12. Graber and Neumann, The Active Plate; Removable Orthodontic Appliances, 2nd edn, Saunders, 1984: 28-34, 67- 74. m
  90. 90. 13. Roberts M. Rickets, Bio Progressive Therapy, Rocky Mountain Orthodontics, 2002 , 255- 258. 14. Barber and Sims: Rapid maxillary expansion and external root resorption in man: A scanning electron microscope study, AJO-DO: 1981 (6): 630 – 652. 15. Dr. Robert M. Ricketts on Early Treatment: Part 2, JCO, 1979 (2): 115-127. 16. MANUEL O. LAGRAVERE :Skeletal and dental changes with fixed slow maxillary expansion treatment, JADA, 2005, 136 (2): 194-99. 17. Robert Marzban, Ravindra Nanda, Nickel Titanium Palatal Expander , JCO, 1999,32 (8): 431-441. m
  91. 91. m
  93. 93. The intermolar distance, however, was found to be stable (Gardner and Chaconas,1976; Sondhi et al., 1980), while Glynn et al. (1987) reported a slight decrease in molar width. During the initial expansion, the teeth tilt to some extent but tend to upright spontaneously during the long period of retention. A permanent expansion of 3.5 mm was obtained with little tendency to relapse (Skieller, 1964). The increase of 1.1 mm in intercanine width found in that study was clearly the result of treatment and not of growth, since the presence of the permanent canines in the initial models was required. It has been shown that no further increase in intercanine width is to be expected after the eruption of the permanent canines, but a decrease, ranging from 0.5 to 1.5 mm is 16 Literature review possible (Brown and Jensen, 1951; Barrow and White, 1952; Moorrees and Chadha, 1965; Knott, 1972). m