Bite Registration Of Functional Appliance

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INTRODUCTION Functional  appliances  act  by  changing  the  spatial  relationship  of  the mandible  in  relation  to maxilla. This  is accomplished by  the means of  forward  repositioning of the mandible by making a  CONSTRUCTION BITE       Bite registration means  register  the bite by  intermaxillary wax record used to relate mandible to maxilla in the three dimensions of space. For  the  success  functional  appliance  --  Determination  of  the  proper  construction bite is critical        Even with great attention to the diagnostic assessment , the functional pattern, Depth of overbite, Relative position of maxilla to cranial base, Amount of sagittal discrepancy, direction of growth  are important for this determination       Some principles should be clearly understood  and  if  these principles are  followed  ,  it  is  possible  describes  the  positioning  of  mandible  in  three  planes of space  like sagittal , vertical and transverse  GENERAL PRINCIPLES OF  CONSTRUCTION BITE          Even with  great  attention  to  the  diagnostic  assessment  ,  the  functional  pattern, Depth of overbite, Relative position of maxilla to cranial base, Amount of sagittal  discrepancy, direction of growth  are important for this determination  .           Some  principles  should  be  clearly  understood   and  if  these  principles  are followed , it is possible describes the positioning of mandible in three planes of space VERTICAL OPENING OF THE MANDIBLE Amount of vertical opening of construction bite is still a subject of considerable controversy. The vertical  opening  varies from small, medium and large.  Based on clinician and type of appliances Based  On Three Major Considerations ·        Kind of dysgnathic  problem (  Sagittal and vertical relationship , morphogenic  growth pattern )  ·         Developmental state,  and age of the patient (potential incremental changes) ·         Type of functional appliance TYPE OF MALOCCLUSION AND VERTICAL OPENING  1. Class II div 1 Malocclusion   ·         Depend on how much   anterior  posturing  is  necessary  to  establish  normal  sagittal relation ship ·        Vertical opening : 1 to 4 mm  in incisal area  ·        If only small or no anterior mandibular position  is needed  : Vertical opening  should be raised more and vice versa  2. Class II div 1 Malocclusion  with Excessive overbite With  severe  curve  of  spee  +  Lower  incisors  over  erupted   impinging  palatal mucosa  and  are  significantly  retruded  with  regard  to  upper  incisors  sagittal  discrepancy as width of whole premolar  2. Class II div 1 Malocclusion  with Excessive overbite Construction bite should not be higher than  a vertical end to end  incisal relation because  the  inter-occlusal  distance  in  molar region  with  infraocclusion  of  molar   and supra  occlusion  of  lower  incisor  might  be  exceeds  7  mm  ,  which   would  excessive  because  of  possible  lateral  spread  of  tongue Labial capping of lower incisors to continue intrusive action and decrease undesirable labial tipping   3. Class II div 2 Malocclusion ·        With  deep  overbite  :  1.5   to  3 mm  between   incisal  edges  to  the most lingually inclined incisor •         Mixed dentition  :  4  to  7 mm interincisal opening •         Severe class II div II cases  in permanent dentition  : up to 9 mm opening  Bite can be opened so far in Class II div 2 cases ·        Improves   the  maxillary  incisor   inclination  because  anterior  end  of  palatal plane tipped up ·        Reduce  deep  bite  because  lower  incisors  are  under  intrusive  action  as maxillary base rotates upward  and  forward  4. Class III cases ·        1.5  to  3 mm between  incisal edges to correct the anterior cross bite ·        Lower jaw is manipulated as far posteriorly as it goes. DIFFERENT CONCEPTS OF VERTICAL OPENING 1.      Anderson and Haupl Concept 2.      Selmer-Olsen, Herren [1953], Harvold [1974], and Woodside Concept 3.      Eschler Concept  Anderson and Haupl Concept :  ·          Vertical registration should not exceed its postural rest position (not more than 4 mm) ·          Myotactic Reflex ·          Isometric contraction   Selmer-Olsen, Herren [1953], Harvold [1974], and Woodside Concept ·        Vertical dimension is opened 4 - 6 mm, a maximum of 4mm beyond the postural rest position  by Herren and Harvold ·        Vertical opening 10-15 mm beyond postural rest position by Woodside ·        Viscoelasticity of muscle and soft tissue 3. Eschler Concept : ·        Vertical opening beyond  4 mm ·        Isotonic and Isometric contraction cycle ·        Insertion of the appliance the mandible is elevated by isotonic muscle contractions. Mandible assumes a static position in contact with the appliance, isometric contractions arise. Mandible cannot reach the postural rest position, the elevators remain stretched. When fatigue occurs, the contracting muscles relax and the mandible drops.  As soon as the muscles have recovered, the cycle begins again.  HORIZONTAL POSTURING OF THE MANDIBLE Four possibilities for posturing the mandible in  the  antero-posteior  dimension for functional orthopaedic appliance 1. Original sagittal jaw relationship may be maintained 2.   Mandible postured Forward equally on both 3.   Mandible postured forward in one side 4. Mandible  postured  backward  as much  as  possible  for  an  end  to end    relationship 1.   Original sagittal jaw relationship may be maintained •       As  in a neutrocclusion with class  II  type of excessive  incisor  overjet and overbite •       Class II relationship due to maxillary protraction   2. Mandible postured Forward equally on both Bilaterally symmetrical class II condition  3. Mandible postured forward in one side         Functional  midline  shift   Class  II  div,  Class  div  2  and  Class  III condition   4. Mandible postured backward as much as possible for an end to end   relationship        Class III malocclusions Analysis of  Construction Bite Maneuver : ·        Class II div I cases  :  Vertical opening accentuates the class II relationship ·        Adjustment of occlusion to Class I relationship require      :  ·        Distalization of maxillary arch  but it is not easy with functional appliance ·        So stimulation of mandibular horizontal growth component at condyle   with dental compensation by mesiovertical eruption of lower posterior teeth ·        Some labial tipping of lower incisor and lingual tipping of maxillary teeth are also part of dental compensation to be expected  ·        If the problem is Functional retrusion with the path of closure upward and backward from postural rest to occlusion, sagittal correction compensation will be less. ·        Class  I  deep  bite  malocclusion  :  Construction  bite  is  taken  with  (1-2  mm) advancement  : -       Mandible drop back as it open into class II tendency  -      Which must be compensated with this slight advancement DIFFERENT HORIZONTAL ADVANCEMENT CONCEPTS 1.      Neumann and  Eschler : Greatest possible advancement with which patient is comfortable . Try to avoid step wise advancement as recommended by Frankel 2.      Neumann   : Mandibular advancement :  the width of an entire tooth  (1st Pre) in case of mixed as well as permanent dentition 3.      Petrovic, Studzmann, Oudet, Mcnamara, Frankel  :  Greatest condylar growth from repetitive advancement in small increments TRANSVERSE POSTURING OF THE MANDIBLE •      Midline coincidence should be carefully checked •      Upper and lower midlines are coincident in habitual occlusion and the sagittal relationship is bilaterally symmetrical : No need to make any transverse compensations •      Midlines should line up in the same forward posturing in the same relationship as in habitual occlusion •      Upper and lower midlines do not coincide :  Must find due to maxillary or mandibular  fault •      Patient is observed in the postural rest to  check midlines and is then asked to slowly close the mouth into full habitual occlusion •       Any shift from one side to another, the occlusal interference should be checked. •      Construction bite should line up with midlines of maxilla and mandible , regardless of shifting of teeth in one jaw or other •      Dental midline discrepancies  : Corrected later with fixed appliance •      Unilateral asymmetry cases :  Making a flush terminal plane into a full class II malocclusion on one side  •      Thus correcting the midline in the construction bite to coincide with the muscularly determined midline in postural rest  also have an effect on the sagittal relationship •       Upper and lower midlines do not coincide :  Must find due to maxillary or  mandibular  fault •       Patient is observed in the postural rest to  check midlines and is then asked to slowly close the mouth into full habitual occlusion •      Any  shift  from  one  side  to  another,  the  occlusal  interference  should  be checked. •      Construction  bite  should  line  up  with  midlines  of  maxilla  and  mandible  , regardless of shifting of teeth in one jaw or other  INITIAL  PREPARATIONS Diagnostic Preparation •      Patient compliance  is essential •      Clinically assess not only somatic and psychological aspect  of patient but also Patient’s motivation potential •      Enhanced by creating “Instant correction” : Moving  mandible forward into an anterior , more normal sagittal relationship Study Model Analysis ·        First permanent molar relationship in habitual occlusion is determined ·        Nature  of  the  midline  discrepancy.  (  Functional   Analysis  should  made  to determine the path of  closure from postural rest to occlusion ) ·        Cast register  a change in midline from postural rest to full occlusion : Functional      Problem ·        Dentoalveolar non coincident midlines cannot be corrected ·        Symmetry of dental arches is determined ·        Curve of spee evaluation ·        Crowding and dental discrepancies are checked and measured  :  (Determine requirements and possibilities  lower incisor movement ) Functional Analysis 1.      Performed  before  taking  the  construction  bite  to  obtain  the  following information 2.      Accurate  registration  of  the  rest  position  :  Vertical  opening  of construction bite depend on this   3.      Path of closure from postural rest to habitual occlusion is analysed:  Any sagittal or transverse deviations are recorded. 4.      Prematurities, point  of  initial  contact,  occlusal  interferences,  and resultant mandibular displacements, if any, are checked. 5.      TMJ is carefully palpated for clicking, crepitus and so forth , which might  be  characteristic  of  a  functional  abnormality  :  Need modification of design of appliance 6.       Inter  occlusal  clearance  or  freeway  space  is  checked  several times ,and the mean amount is recorded. 7.      Respiration is checked for any deviation from normal Cephalometric  Analysis Most  important  information  required  for planning for the construction bite includes the following:- 1.      Direction of growth : Average , horizontal or vertical 2.      Differentiation between the position and the size of the jaw bases 3.      Axial  inclination and  the position of maxillary and mandibular incisors determined. :  (  Provide  important  diagnostic  and  prognostic  clues  for  determining the anterior  position of  mandible and appliance  design details for incisor area )  FABRICATION OF CONSTRUCTION BITE ·        Horse shoe shaped wax bite rim ·        Impressed on lower cast, edge of incisors not covered by wax ·        Midlines are marked in the wax ·        Distal half of last molars not covered by wax. ·        Not to touch the gingiva behind last molars -         For class II cases : wax rim is placed in lower arch -          For class III cases : wax rim is placed in upper arch EXECUTION OF CONSTRUCTION BITE TECHNIQUE 1.      Make the patient sit upright in the relaxed posture, guide the  mandible into desired position without exerting force 2.      Wax is placed in mouth after the operator is sure the patient can replicate 3.      Edge to edge incisal relation is maintained ( Usually ) 4.      Midline is observed for coincidence 5.      Wax bite is carefully removed  Wax Bite Visualization   Mixed dentition :  •      Sometimes difficult  to determine  precisely  how much mandible  has  been moved forward in the construction bite ( wax roll covering the tooth contact surface )  :Cutting away extruded lateral wax helps visualization  •      Bilateral symmetrical malocclusion  is  to check  the deciduous canine as a guide  : Upper  deciduous canine cusp tip  fit into embrasure  between lower deciduous  canine and lower  deciduous first molar    Permanent dentition •      Tip  of  the  buccal  cusp  of  the  upper  first  premolar  serves  well  as  a  guide point. : It Fit precisely in to the embrasure between the lower first and second  premolars.  GENERAL RULES FOR CONSTRUCTION BITE 1.      If  the  Forward  positioning  of  the  mandible  is  7mm  to  8  mm,  the  vertical opening must to slight to moderate (2mm to 4mm) 2.      If  the  forward positioning  is no more  than  3mm to 5mm,  the vertical opening should be 4mm to 6mm 3.      Midline correction          Assessment of construction bite determines the kind of muscle stimulation , the frequency of mandibular movements and the duration of the effective  forces   Frequency Of Maximal Biting {Sander} •      6 mm high CB      : 12.5 % of sleeping time •      11 mm high CB.    : 1.1 % of sleeping time •      13 mm high CB     :  0.8 % of sleeping time        Many  experimental  research  and  clinical  experience   says  increased  in  muscle  activation  with  overextended  appliances  does  not increase the efficiency of the appliance CONSTRUCTION BITE OF ACTIVATOR  Low construction with a marked forward positioning of the mandible ·        Class II functional mandibular  retrusion cases ·        Indication : Class II div I cases with sufficient overjet [ Horizontal Growers] ·        Sagittal advancement at  least 3 mm posterior  to  the most protrusive position  of mandible   : Avoid  the  possibility  to   initiating  golgi  tendon organ  activity ( Rule of thumb limitation ) ·        Vertical registration should not exceed its postural rest position (not more than  4 mm)  { Anderson  & Haupl Concept } ·        Mandible moves mesially  to engage  the appliance,  the elevator muscles of mastication are activated  and myotatic reflex occur ·        Muscle  force  during  biting  and  swallowing  +  reflex  stimulation  of muscle spindles elicit reflex muscle activity  [ K.E Principle ] ·        Horizontal “H” activator  High construction bite with slight anterior mandibular positioning: •      Indication :  Class II Div I  retromadibular cases [ Vertical Growth pattern ] •      Sagittal opening only 3-5 mm ahead of habitual occlusion •      Vertical dimension is opened 4 - 6 mm, a maximum of 4mm beyond the postural rest position { Herren , Harvold , Woodside Concept } •      Appliances induce some  Myotactic reflex  in the muscles of mastication •      Additional force by stretching of the muscles and soft tissue [ Viscoelastic property ] •      Stretching of muscles and soft tissue  cause MOA [ P.E Principle ] •      • Stretch  reflex  activation  with  increased  vertical   dimension  may  well  influence the inclination of maxillary base : Retroclination of maxilla •      Lingual tipping of upper and labial tipping of lower incisors •      V Activator  Construction Bite without Forward Positioning Of The Mandible: Vertical Dimension Problems  1.      Deep Bite 2.      Open Bite 3.      Arch Deficiency Problems  Deep Bite Cases •      Dentoalveolar overbite  (supra eruption of  incisors and  infraocclusion of molars)  : •      Moderate or high CB depend on freeway space size •      Deep overbite ( supraocclusion of the incisors ) : CB is not as high, Acrylic capping on incisors  •      Skeletal deep overbite ( Horizontal growth pattern ) : High CB  5-6 mm beyond  freeway  space  ,  extrusion  of  lower molars,  loading  of  lower incisors.  Open Bite Cases •      Bite opening 4-5 mm  :  Develop a sufficient elastic depressing force  that will load the molars that are in premature contact •       Dentoalveolar  open  bite  :   treated  by  proper  trimming  of  acrylic  in  the anterior region- allowing incisor eruption •      Retroclination  of  maxillary  base  with  restriction  of  vertical  growth pattern ( Precondition for successful therapy ) •      Closing  the  „ V  ‟  between upper and  lower maxillary bases  : Depressing the posterior maxillary segment •      Surgical open bite cannot be treat with activator ( Impacted posterior segment )  Arch Length Deficiency Problems • Advancement  :   2 mm     +     Vertical opening : 2 mm  • Advancement to compensate for downward and backward opening component  Construction Bite With Opening And Posterior Positioning Of Mandible •      Indication  : Class III malocclusion •      Construction bite  is taken in the retruded  position of lower jaw •      Vertical opening  far enough to clear the incisal guidance. CONSTRUCTION BITE OF BIONATOR               According to Balter, the equilibrium between the tongue and circumoral muscles is responsible for the shape of dental arches and intercuspation. Functional space  for  the  tongue  is essential  for  development of orofacial system . A  discoordination  of  its  functions  could   lead  to  abnormal  growth  and  actual deformation . •      Bionators modulate  the muscle activity •      Enhancing normal development of inherent growth pattern •      Eliminating abnormal and potentially deforming environmental factors CONSTRUCTION BITE OF STANDARD  BIONATOR APPLIANCE •     Objective  :  To establish a class I relationship •     Most important : Position of incisors as established by construction bite 1.      Edge to edge incisor relationship :  Maximum functional space for tongue 2.      In  Large   Overjet  cases  :  Step  by  step  protraction  is  followed  and  lower incisors must be covered by grooved rim             3.      New appliance with edge to edge incisor relationship  or   Step 3 may followed 4.      An additional maxillary incisal margin acrylic  restraint may be used ( by adding acrylic on mandibular incisor acrylic cover right at incisal margin ) Large Overjet case       Not open the bite higher because a high construction bite could impair tongue function and the patient could actually acquire a tongue thrust habit as the mandible dropped open. Open bite •      Used to inhibit abnormal posture and function of tongue •      Construction bite as low as possible •      Vertical opening allows the interposition of posterior acrylic bite blocks -         That prevent extrusion of posterior teeth.  Class III Bionator CB •      Construction bite  is  taken  in  the most posterior  position  that  is possible  of mandible •      Allow  labial movement  of maxillary  incisors  and  retrusive  effect  on  lower anteriors •      Bite opening  : 2  mm is recommended   Construction Bite of bionator in TMJ problem •      Special use of Bionator with success achieved ( Especially in adult cases ) •      Bionator wearing at night relaxes the muscle spasms ( LPM) •      Same design as standard appliance •      Construction bite need not move mandible as far forward •      Main purpose  :  Prevents riding of condyle over posterior edge of the disk , which causes clicking •      Bionator maintains a  forward position preventing deleterious Para  functional habits at night  •       Slight opening of construction bite with lower incisor capping is also needed CONSTRUCTION BITE IN FRANKEL FUNCTION REGULATOR General principles Primary aim of functional therapy is to : •      Overcome aberrant postural behavior of associated perioral muscles •      Treatment of Maxillo-mandibuar malrelationship to overcome the associated faulty pattern of postural performances. •      Accomplished by gradual training of muscles. •      Therefore  the extent of original change in the mandibular positioning should be minimal.    Construction Bite Of FR Ia and FR Ib   Minor sagittal problems (2-4 mm)  •      Bite is taken in an end to end  incisal position •      No obvious strain on facial muscles •      Balance between protractor and retractor muscles are not disturbed •      Frankel  recommended  the  CB  should  not  move  the  mandible  forward farther than 2.5 – 3 mm •      Vertical opening is only large enough to permit the cross over wires to pass through the interocclusal area. Schmuth( 1995)  :  •      Most Patient  tolerate  4-6 mm of  forward movement   and opening  :which  allows an end to end incisal relationship to be established for most class II malocclusions •      Vertical opening must be at  least 2.5 – 3.5 mm  in  the buccal segments  to  allow crossover wires to pass through  Construction Bite Of FR Ic    •      Indication : more severe Class II div 1 cases  overjet more than 7 mm •      Step by step advancement - 4-6 mm of forward movement - 2.5  to 3.5 mm vertical opening Construction Bite Of FR II •      Sagittal advancement is minimal : 2-3 mm •      Wider open construction bite in class II div 2 cases •      Wide  CB Enhance selective eruption of lower buccal segments.   Construction Bite Of FR III •      Construction  bite  cause  posterior  position  of   the  mandible  as  much  as possible •      Condyles occupying most posterior position of fossa •      Bite Opening  is only enough  to allow  the maxillary  incisors  to move  labially past the mandibular incisors in crossbite correction •      Bite opening is kept to a minimum to allow lip closure with minimal strain •      Lip seal exercises can  improve  redundant and everted  lower  lips of patient with mandibular prognathism  Maximal Posterior Condylar Position •      Clinician  gently  taps  on  patient’s  mandible  while  patient  opens  the  bite approximately 1 cm •      Continues tapping and  asks the patient to close slowly  •      Guides the final closure with posterior pressure applied by the thumb against the symphysis and forefinger under the chin. •      Maintains the position for 1-2 mins ( for establishment of proprioceptive learning position ) •      Posterior guidance is essential during bite taking procedure Construction bite for class III deep bite cases •      Wider vertical opening for construction bite  •      To stimulate for downward and forward eruption of maxillary teeth •      Acrylic  extension and occlusal rests  may be placed over mandibular molars provides more stability CONSTRUCTION BITEIN TWIN BLOCK APPLIANCE  Class II div 1 cases with Deep overbite ·        Exactobite is designed to register (  Blue  colour ) ·        • 5  –  10  mm  anterior   advancement  on  initial  activation    of  twinblock  depending on the freedom of movement of protrusive function ·        Bite registered at  edge to edge on incisors -         Inter incisal clearance      : 2 mm  -         Premolar clearance          : 5-6 mm  -         Molar region clearance   : 2 mm  ·        This   clearance   is  used  for  eruption  of  posterior  teeth  to  reduce  the overbite  ·        Large overjet  : Step wise  advancement  needed  Class II div 2 Cases ·        CB is registered with the incisors in edge to edge  occlusion ·        Overbite is excessive : Clearance between the posterior teeth is correspondingly increased ·        These patients require more vertical development : So thicker occlusal bite block in premolar region to allow clearance of upper and lower incisor  Open bite cases ·        Thicker  Exactobite is designed to register (  White colour) -         Interincisal clearance                                      :  4 mm  -         Clearance 1st  premolars  or deciduous molars   :  5 mm ·        Necessary to accommodate  blocks of sufficient thickness between the  posterior teeth to open the bite beyond the free-way space so as to intrude  the posterior teeth ·        Objective is to make  it difficult for the patient to disengage the blocks ·        Bite registration process is similar as  described for treatment of deep overbite Class III Cases  ·        Blue exactobite is used to register CB ·        Teeth closed to the position of maximum retrusion ·        2 mm interincisal clearance – sufficient space for occlusal bite blocks ACCESSORIES FOR BITE REGISTRATION 1. Warm water bath 2. Modelling wax 3. Dowel 4. Exacto bite 5. George gauge 6. 3D Bite Dowel-up Bite Registration For Functional Appliances ·        The bite opening can vary from 2 to 8 mm ·        Vertical  opening  with  the  jaw  protruded  can  be  controlled  by  adjusting where the patient bites on the conical end of the dowel ·        Bite opening  in excess of 8 mm needed  : Wooden dowel of appropriate diameter can be used. • The point of a dowel is placed between the patient's anterior teeth at the midline ·        The stick may be sharpened in an ordinary pencil sharpener         The dowel is held firmly between the teeth in the patient's habitual bite  Procedural steps for the dowel-up technique are follows:        Rehearse  the  procedure  by  having  the  patient  bite  lightly  on  the  end  of  a wooden dowel (Fig 1)  Place  the  opposite  spines  on  the  dowel  shaft  on  the  upper  and  lower midlines. 1.        Insert  or withdraw  the  conical  end  of  the  sharpened  dowel  until  the  patient's jaw is at the  desired vertical position.  2.        Request  the  patient  to  raise  the  tip  of  the  dowel  until  the  required  amount of jaw protrusion is obtained  (Fig. 2). 3.        Remove the dowel and place a roll of heavy-bodied impression material on the  occlusal and  incisal surfaces of the lower teeth  Again have the patient bite on the  sharpened end  of the dowel and repeat step 1 (b)While the impression material is  setting, the patient can  support the dowel with their hand  4.    Mould the impression material to the buccal sections and around the dowel ( 5.        Remove dowel with  the bite  registration when  the  impression material has  set. 6.        Place casts in the impression for laboratory procedures. Exacto bite ·        Accurate control in registering a protrusive bite ·        Gauge allows clinician  to choose variable amounts of sagittal activation by  selecting  appropriate  groove  to  engage  the  upper  incisors  in registering protrusive bite   Two types : 1.    Blue exactobite      :  Registers a 2mm vertical interincisal clearance  2.    White exactobite      :  Registers a 4mm vertical interincisal clearance     Activation  aims  to  achieve  reduction  of  overjet  ,correction  of  distal occlusion and midline correction.    GEORGE GUAGE Adjustable  George  Gauge  can  be  preset  to  guide  the  mandible  into  the desired  construction  bite  position,  relative  to  either  the  incisors  or  the protrusive path   Parts of George Gauge 1.    Lower incisor clamp 2.    Bitefork 3.    Body  Lower incisor clamp slides in and out of the body,  forming the lingual wall of the lower incisor notch. It  can be adjusted to fit over rotated incisors. Bitefork  :  which also slides in and out, contains the perforated prongs that hold the registration material,  the upper  incisor notch, and the shaft whose anterior  end  indicates mandibular  position  on  the millimeter  scale  of  the body . Bite forks are available in two incisor notch sizes, one producing a 2mm interincisal distance and the other, 5mm. 1. Registration Technique 1.             With the bitefork removed, center the lower incisor notch over the lower anterior teeth . Move the lower incisor clamp up so that it grips the teeth firmly, and tighten the lower turnscrew 2.             Remove the instrument from the mouth and insert the bite fork -         Replace the gauge in the mouth with the lower incisor notch centered over the lower midline. -         Instruct the patient to close into the upper incisor notch while the midline indicator is   positioned between the upper incisors   If the incisors are badly rotated, the upper notch can be modified with an acrylic bur. 3.             With the upper and lower incisors in their respective notches, have the patient move the mandible first into centric relation, then into full protrusion, and note these positions on the millimeter scale 4.      Select the desired bite position from this range of protrusion. Remove the gauge from the mouth, set the bitefork to the desired position on the millimeter scale, and tighten the upper turn screw. 5.       Cover the prongs of the bitefork with registration material (Fig. 5).    •      Baseplate wax cut into 3'‘ x 1½'' pieces can be heated in water or over a flame and wrapped around each prong. •      Silicone putty is easier to use and provides a more accurate and durable record. 6.      Return the gauge with the impression material to the mouth, with the lower incisor notch centered over the lower midline. Hand the patient a mirror, and instruct the patient to close into the upper incisor notch, taking care to align the upper incisors with the midline indicator (Fig. 6). ₋        If a midline discrepancy is to be maintained, a mark can be made on the maxillary incisor to guide the patient. 7.       Excess registration material trimmed to about t mm from occlusal surfaces 3D bite”:  A new appliance device   for registration of construction  bite How  It works -         After a thorough examination of the patient, and according to the treatment concept and patient’s need, the clinician decides to advance the mandible for  x mm  ,to open the bite for  y mm  and to displace the midline  z mm To advance the mandible for  x mm  By moving the  upper part  [Figure  1a‑number 1] against the lower  part  [Figure  1a‑number  2], the clinician can obtain x mm of advancement and this number is shown in the anterioposterior ruler [Figure 1a‑number 3] located on the upper part. To open the bite for  y mm A vertical opening can be obtained by opening the screw  [Figure  1a‑number4] and the  amount of bite opening is shown by the vertical ruler  [Figure  1a‑number 5] To displace the midline  z mm Midline correction  can be done by locating the upper midline blade [Figure 1a‑number 6] between upper centrals moving  the transverse bar  [Figure  1b‑number  7] through its  sheath  [Figure  1b‑number 8]; the amount of midline  shift is shown on the top of the transverse bar ·        Then the clinician adds a bite wax to the device [Figure 2a]  and lets the patient bite by locating his or her incisors in the groove [Figure  2b ·        Calibrated appliance is ready to come together with the fork and wax , and it is ready to use ·        Calibrated appliance is ready to come together with the fork and wax. Then it is ready to use Advantages of 3D Bite 1.      It controls the position of the mandible  in three planes (sagittal, transverse, and vertical) 2.      The amount of anterioposterior advancement, vertical opening, and lateral shift is not limited. 3.      It can hold the mandible forward during cooling of the wax. 4.      There is a minimal need for patient cooperation. 5.      Numerical amount of change can be determined. 6.      The clinician can separate fork and wax and send it to the laboratory for the fabrication of a functional appliance. 7.      Less chair time 8.      It  is very useful in clinical studies that address functional appliances   because of its numerical documentation and high reproducibility       CONCLUSION            The  recording of Construction  bite  is  the most  crucial  step  in  treatment with  functional  appliance  as  the  anterio  -  posterior  and  vertical  dimension introduced in CB brings about anatomical and physiological changes in relation to  mandible  ,thereby  influence  its  final  position  and  therefore  the  treatment outcome.            So  better   understanding  of    construction  bite  and  bite  registration  is necessary for the treatment success as an orthodontist as concerned REFERENCE 1.      Removable orthodontic appliance  :  T.M Graber , Bedrich Newmann, 2nd ed 2.      Dentofacial orthopaedics with functional appliances :Graber ,Rakosi ,Petrovic – 2nd ed 3.      3. Twin block functional therapy   : William J Clarke 4.      Frankel appliance therapy  5.      The dowel-up bite registration for functional appliances. John J. Sheridan AJO DO 1983 ; 84(5) 5. 6.      A  New  Instrument  for  Functional  Appliance  Bite  Registration  .  PETER  T. GEORGE. JCO 1992: 26(11) 721-3 7.      “3D bite”: A new appliance device for registration of construction bite Mojgan Kachoei and Ahmad Behroozian. Dent Res J (Isfahan). 2012 Nov-Dec; 9(6): 826–827