BRACKET PLACEMENT IN ORTHODONTIC BONDING

SEMINAR

1. DR. SHEHNAZ JAHANGIR Iind YEAR MDS DEPT. OF ORTHODONTICS BRACKET PLACEMENT IN ORTHODONTIC BONDING

2. CONTENTS INTRODUCTION FACC FA POINT ANDREW’S PLANE BRACKETS PARTS BASE OF THE BRACKET MESIODITAL POSITIONING OF BRACKETS MODIFICATIONS

3. AXIAL POSITIONING OF BRACKETS MODIFICATIONS VERTICAL POSITIONING OF BRACKETS DIFFERENT GUIDELINES ANDREWS ROTH ALEXANDER MBT VIAZIS MODIFICATIONS BRACKET POSITIONING GAUGES BRACKET PLACEMENT ERRORS CONCLUSION

4. Introduction: I n the past, the best results were achieved by orthodontists who were the the best wire benders. The emphasis has changed since the development of the pre-adjusted appliance by Andrews. The best results in the future will be achieved by those orthodontists who are best at accurate bracket positioning.

5. Orthodontic treatment is based upon specific force applications to the dentition, the maxilla and the mandible. In order to obtain these forces in a fixed appliance, orthodontic brackets are attached to the teeth.

6. The brackets themselves produce no force. They are merely handles for attachment of the force producing agents. However, brackets can effect the directions of the force vectors when torque, angulations, and in/out are built in to the brackets. The accurately placed brackets will give better control on three dimension position of the teeth during treatment. An accurately placed bracket will also result in better expression of its built in prescription and orthodontist will need less wire bending and complex mechanics during the course of treatment.

7. Facial Axis of the Clinical Crown (FACC). The most prominent portion of the central lobe on each crown’s facial surface. For molars, the buccal groove that separates the two facial cusps

8. The point on the facial axis that separates the gingival half of the clinical crown from the occlusal half. Facial Axis Point (FA point ):

9. The surface or plane on which the mid-transverse plane of every crown in an arch will fall when the teeth are optimally positioned. This plane virtually connects the appliance th r ough t h e F A p oin t . Andrews® Plane :

10. Upper Arch FA Point & FACC Upper Arch Brackets On Andrews® Plane Line

11. Lower Arch FA Point & FACC Lower Arch Brackets On Andrews® Plane Line

12. BRACKETS DEFINITION: Raymond C. Thurow has defined bracket as an orthodontic attachment secured to a tooth for the purpose of engaging on arch wire and to transmit the adjacent force to the tooth in proper , precise and effective manner.

13. Bracket base Slot base Slot Point Slot axis Bracket stem Base point PARTS OF A BRACKET

14. Welding tab, solder or a bonding mesh Curved to conform tooth structure Mode of retention of bracket base may be: Mechanical Micromechanical Chemical Mechanical and chemical retention BASE OF BRACKET

15. Mesh type The sizes of the wire mesh used in the manufacturing of the various single mesh type bases were 40, 60, 80 and 100 meshes. ( dickinson 1980) Non mesh type BRACKET BASE TYPES

16. MESH TYPE BASES

17. NON-MESH TYPE BASES

18. Mesiodistal positionING of brackets

19. It is a general saying in orthodontics that brackets should be placed at mesiodistal center of the teeth. This statement is partially correct as this rule can't be applied to all the teeth.

20. A more clear description for right mesiodistal position of brackets was given by Andrew that brackets should ideally be placed at the mid developmental ridge of the teeth.

21. Maxillary and mandibular incisors Bracket should ideally be placed at mesiodistal center of maxillary and mandibular incisors. The mid developmental ridge of these teeth is also present at their mesiodistal center of the labial surface .

22. Maxillary and mandibular incisors

23. Vertical lines showing mesiodistal center of the upper and lower incisors. Brackets should be placed at the recommended height on this line .

24. Maxillary and mandibular Canines Placing brackets at the mesiodistal center of the canines will result in contact point error and slight rotation of the teeth as the mid developmental ridge of upper and lower canines lies slightly mesial to the mesiodistal center of the teeth and is more mesial in case of lower canines. So bracket is placed slightly off center and toward mesial, in case of canines.

25. { The vertical lines on maxillary and mandibular canines indicate the mid developmental ridge of the canines and ideally the middle of the brackets should coincide with this line.

26. Mandibular Premolars Roth p ro posed that premolars brackets should be placed at area of maximum convexity which is usually the mesiodistal center of the teeth and mid developmental ridge also lies in this area.

27. Mandibular Premolars

28. Sometimes the area of maximum convexity lies slightly mesial to the mesiodistal center but degree of mesial deviation is less than that of canines. The difference between bracket placement on premolars and anterior teeth is presence of a lingual cusp on premolars which must be taken into consideration while placing the brackets. M D

29. Maximum convexity lies slightly mesial to the mesiodistal center. The cast of the patient should be examined to detect position of the maximum convexity

30. In mandibular premolars the buccal and lingual cusps lies at the same level in the mesiodistal perspective. So when placing lower premolar brackets the scribe line of the bracket should coincide with line connecting the buccal and lingual cusps.

31. In maxillary premolars, brackets should be placed so that the scribe line of the bracket is slightly mesial of up to 0.5 mm to the line connecting the buccal and lingual cusps MAXILLARY PREMOLARS

32. Bracket placement on maxillary premolars is different from mandibular premolars as maxillary premolars should have slightly rotated position at the end the treatment while the lingual cusps have cusp fossa relationship with lower premolars in class I & II molar occlusion

33. According to Andrew six keys of normal occlusion the buccal cusps of upper premolars should have a cusp embrasure relationship with lower premolars

34. According to An d r ew1 the b u c c al cusps of upper premolars should be slightly more distal than the lingual cusps in the mesiodistal perspective

35. A. Keeping the buccal and lingual cusps of maxillary premolars in the same mesiodistal perspective will cause poor occlusal results.. D. A bracket bonded slightly mesial to line connecting the buccal and lingual cusp of maxillary 2nd premolar. Bonding the bracket in this position will rotate the buccal cuspsdistally and lingual cusp slightly mesial to get ideal relationship in a class I molar relationship

36. B&C. When the buccal cusp tips of the maxillary premolars are in line with lower embrasures their lingual cusps lies slightly mesial to embrasures and rest at their corresponding teeth fossa

37. Checking mesiodistal position of the brackets The mesiodistal position of the bracket can be checked under both direct and indirect vision. For indirect vision diagnostic mirror is used . Generally mesiodistal position of upper incisors, premolars and molars brackets is checked under indirect vision

38. Modifications in mesiodistal position of the bracket Alteration in mesiodistal position of the bracket will alter the prescription of the bracket in terms of counter rotation. Some situations where mesiodistal position of the bracket is altered are given.

39. Rotated teeth In case of rotated teeth the bracket should always be placed more on side of rotation in the mesiodistal plane . This overcorrected position of the bracket will result in early correction of the rotation and will also accommodate the relapse factor after debonding . A rotated maxillary 2nd premolar, As the tooth is distopalatally rotated so the bracket is placed slightly more distal than its required position

40. Clinical Notes Sometimes due to severe rotation or crowding the position of the tooth is such that it's not possible to place bracket at the correct mesiodistal center of the tooth

41. Rotated right upper central incisor. Correct mesiodistal position of the bracket is not possible on the first bonding visit due to rotation. The bracket should be placed as far mesial as possible. The mesial side of the bracket should not come in contact with left side incisor because it will hinder the full insertion of the wire .

42. In such situations the bracket should be placed as far as possible toward the mesiodistal center of the tooth or toward the rotation. A flexible wire is passed and only the brackets wings toward the rotation are ligated. At subsequent visit the tooth is usually derotated enough to place bracket at the right mesiodistal position So the bracket is debonded and either a recycled or new bracket is rebonded at the correct mesiodistal position

43. Clinical Notes Sometimes the tooth is rotated 180° so that the lingual side is on the facial side. Many times this form of rotation is accepted. In such situation the bracket is bonded on the side of the tooth which is facing labial or buccal . Right lower lateral is rotated 180°.The rotation was accepted and bracket placed on lingual side of the tooth which was facing labially

44. Another situation is maxillary lateral incisor substitution by canine. In this situation the slightly convex labial surface of canine is made flat to give it shape of lateral incisor and bracket is bonded at mesiodistal center of reshaped canine instead of slightly mesial.

45. Placing the bracket at the mid developmental ridge area will cause poor contact point with the central incisor as canine is also reshaped mesiodistally. On premolar tooth which will become future canine the canine bracket is placed distal to the mesiodistal center of the tooth.

46. It is necessary to position these brackets gingivally to permit the re-contouring of the canines required for esthetics and function. The orthodontist should place the brackets according to gingival margin height rather than incisal edge or cusp tip.

47. Axial or long axis position of the brackets

48. Axial or long axis position of the bracket is related to the angulation or tip of the teeth. In conventional edgewise system where there was no built in tip, the brackets were placed angulated on the tooth. The amount of bracket angulation on the tooth was equal to the amount of tip required .

49. Standard edgewise brackets has no built in tip. Bracket position didn't follow long axis of the crown or root and were placed angular on the tooth equal to the amount of tip required.

50. In pre adjusted edgewise system as the tip is already built within the brackets so placing the bracket similar to standard edgewise will result in increase or decrease of built in tip. In pre adjusted edgewise system brackets are positioned on the tooth so that their wings and scribe line are parallel to long axis of the tooth .

51. A pre adjusted bracket of maxillary left lateral incisor . Placing the bracket parallel to long axis of THE TOOTH will cause tooth to rotate in a clockwise direction and express the built in tip.

52. But there is always some difference between the angulation of long axis of the crown and long axis of the tooth in the mesiodistal plane . There is always some difference between long axis of clinical crown and long axis of the tooth

53. Also placing bracket according to long axis of tooth may result in wrong mesiodistal position of bracket on the crown.

54. Andrew p ro posed that as the clinical crown is only visible in the mouth so the angulation of the tooth should be taken by taking the angulation of long axis of clinical crown (LACC) and not the long axis of the entire tooth. But taking only the long axis of clinical crown may result in poor root parallelism and in some cases root resorption due to roots approximation of adjacent t ee th c an occur.

55. A lateral incisor bracket placed with reference to long axis of clinical crown. X ray showing that long axis of bracket not coinciding with long axis of the root and because of this root of the lateral incisor is in close contact with central incisor root increasing chances of root resorption in this area.

56. Taking the long axis of tooth can results in poor proportions of connectors and embrasures . These proportions can be corrected at end of treatment either by composite build up or interproximal reduction .

57. A. Golden proportion of connectors that ideally should be present in finished cases. B . A case with dilacerated central incisor root. If there is root dilacerations, placing bracket by following the clinical crown will result in ideal connector areas but greater chances of root approximation and so root resorption.

58. C. Bracket placed by following the long axis of the roots. The golden proportion of connectors is distorted. They can be res t ored by composite built up or interproximal stripping at the end of treatment

59. Clinical notes Some clinicians also take incisor edge as guideline for long axis positioning of brackets. But incisor edge is mostly uneven due to trauma, attrition and mamelons. So incisor edge shouldn't be taken as a reference point for long axis position of the bracket .

60. Also gingival zenith(top) shouldn't be taken as a reference for long axis position of the bracket as it can be effected by uneven pattern of gingival recession .

61. A. Mamelons on central incisors. These mamelons will give a different long axis position of the tooth if taken as reference for bracket positioning. B . Attrition of the incisor edge will also effect long axis position of the teeth. C . Gingival zenith shifted mesial from their ideal position due to gingival recession. Taking gingival zenith as reference for axial position of the bracket in these cases will result in wrong placement of the brackets .

62. Importance of axial position of brackets Correct axial position of the bracket is very important for proper occlusal and esthetic relationship. As preadjusted brackets have built in tip, a poor axial position of the bracket will result in expression of increase or decrease positive or negative tip. Increase in tip may increase space requirement in the arch and also increase risk of adjacent root approximation

63. Checking axial position of brackets The axial position of the brackets is checked under both direct and indirect vision. Usually maxillary anterior brackets and mandibular brackets are checked under direct vision from labial side of the tooth while maxillary posterior brackets are checked under indirect vision using diagnostic mouth mirrors.

64. If there is doubt in position of maxillary anterior brackets especially lateral incisor brackets , some clinicians favor to use indirect vision by diagnostic mirror and use guidance from lingual side of tooth.

65. Modifications in axial position of brackets Modifications are made in axial position in the following circumstances To avoid chances of root resorption due to adjacent root approximation. To avoid root resorption from orthodontic implants .

66. . ) . 3.To avoid root resorption from impacted teeth in bones :-canines or mesiodens

67. 5. In some surgical cases bracket position is modified to move roots away from surgical site (Wassmound procedure in maxilla, Subapical osteotomy). 4. To accommodate crown morphology for achieving golden proportions of connectors and embrasures

68. VERTICAL POSITION OF BRACKETS

69. Edgewise and Begg brackets were placed on tooth with help of gauges using one standard measurement for all the patients. • The vertical positioning errors were corrected by wire bending which was integral part of the treatment .

70. With the advent of straight wire Appliance, vertical position of the bracket gained more importance. As morphology of tooth is not uniform throughout its length, changing the vertical position of the bracket will result in different expression of its built-in prescription.

71. Different guidelines for vertical positioning of the brackets

72. Andrew Guidelines for bracket placement It should be free of occlusal and gingival interference. The brackets siting site on a tooth should have consistent angular relationship with its occlusal plane and to the occlusal plane of arch when all the teeth are ideally placed .

73. 3) When the teeth are ideally positioned, the middle of each bracket site must be at the Andrew plane, where Andrew plane is a surface plane on which mid transverse plane of every crown in an arch will fall when the teeth are optimally positioned.

74. • In case gingival recession, Andrew quoted that “1.8 mm should be subtracted from anatomical crown to find the correct value of clinical crown. This measurement must be adjusted while placing bracket at FA point in cases with gingival recession”. • Andrew proposed that bracket must be accurately placed within 2° of FACC and base point or middle of the bracket should be within 0.5 mm of FA point.

75. • Where FA point (facial axis point) is center of facial axis of clinical crown (FACC) and it virtually divides the clinical crown into occlusal half and gingival half. • The FACC on each tooth correspond to mid-developmental ridge and in case of molar it is dominant vertical buccal groove.

76. Andrew also proposed using LA point (long axis point) for bracket positioning, where LA point is the mid of long axis of clinical crown (LACC).Though Andrew later disown LACC and LA point but amazingly description of LACC or FACC remain the same in Andrew writings that was mid developmental ridge and dominant vertical buccal groove in case of molars.

77. Limitations of Andrew's Recommendations • Placing brackets with only guessing the correct position will result in vertical positioning errors. Not every orthodontist will place the bracket at the same height. Even the same orthodontist, after accidental debonding of bracket will rebond the bracket at a slightly different height • Placing bracket is also troublesome in gingival recession and gingival enlargement as vertical adjustment in bracket height in millimeters is again a matter of guesswork .

78. • Also no consideration was given for incisal and occlusal edges which are functional and esthetic units of teeth. Even an error of 0.5 mm in anterior teeth is noticed by esthetic conscious patients . • Eliades found out that positioning bracket at FA point results in marginal ridge discrepancy and poor occlusal contacts.

79. • Roth like Andrew also proposed center of clinical crown for ideal bracket placement to be used with his prescription. • Roth advocated that for his prescription anterior brackets should be placed slightly more incisal than Andrew proposed center of clinical crown or FA point to level the curve of spee . Roth Guidelines

80. • According to Roth the upper central and lateral incisor should either be at the same level or lateral incisor should be 0.5 mm less prominent than central incisor. • The central incisors will elongate 0.5 mm to 1mm more than the lateral incisor after settling. maxillary canine should be 1 to 1.5 mm below the occlusal plane while mandibular canine should be 0.5 to 1 mm above the occlusal plane. • The upper and lower canines also should be 1mm more prominent than lateral incisors and bicuspid.

81. Most variation in bracket position are found in bicuspids. In bicuspids the bracket should be placed at area of maximum convexity which in most cases is center of clinical crown. In case of increase curve of spee the lower canine brackets should be placed more occlusal than the premolar brackets to avoid future wire bending to level the curve of spee .

82. LIMITATIONS OF ROTH GUIDELINES Roth recommendations are good to attain a functional occlusion but merely guessing the right height while placing brackets with such accuracy in millimeters is usually not possible. According to Roth canine or premolar teeth should be taken as reference while placing brackets. A bracket positioning chart advocated for speed brackets having Roth prescription is given. • No reference is found in literature whether this chart is supported by Roth or it's just manufacturer recommendation.

83. Alexander Guidelines Alexander advocated individualizing bracket positioning for each patient to effectively use his bracket prescription. • According to Alexander , the premolar clinical crown height is the most variable in the arch so premolar bracket height (X) should be taken as reference. All the other brackets are placed with reference to premolar bracket height (X).

84. To find premolar bracket height, premolar clinical crown height is taken and is divided into half. • The premolar normal bracket height (X) is usually 4.5 mm. The chart for bracket height measurement is given.

85. Limitation of Alexander Guidelines Premolars in upper and lower arch were bonded at same height. As 1st premolars cusps are longer than 2nd premolars especially in lower arch. so bonding all the premolar at the same height will result in marginal ridges discrepancy and premature occlusal contacts . • Also no value was given for lower 2nd molars. To correct these discrepancies , Alexander modified his bracket positioning chart

86. Alexander modified his bracket positioning chart X=4mm for small crown and 4.5 mm for average crown and 5 mm for large size crown. In case of 1st premolar extraction 2nd premolar is taken as reference Alexander advocated specific positioning gauges for bracket placement. For ideal smile arc relationship Alexander proposed that maxillary lateral incisors brackets should be placed 0.25 mm more incisal from central incisor.

87. Limitations of modified Alexander Guidelines Alexander bracket positioning chart though help to level incisor edges and give good anterior aesthetics but taking premolar clinical crown height as a reference mean, the clinician is denying all the variations in other teeth clinical crown heights and morphology. • Taking half the height of clinical crowns in premolars may result in marginal ridges discrepancy and occlusal interferences. • Wire bending is usually needed to accommodate height differential and settle down the occlusion

88. In modified chart the lateral incisor bracket position was 0.25 mm more incisal than central incisor. It is extremely difficult to place bracket with 0.25 mm accuracy even with the help of gauge because of the play between slot supporting part of the gauge and slot of the bracket. In modified Alexander bracket positioning chart upper 2nd molar height is 1 mm greater than 1st molar, this can create marginal ridge discrepancy between the maxillary molars in many cases .

89. McLaughlin or MBT vertical bracket positioning The method is given as follow: 1 ) Measure the clinical crown height of fully erupted teeth on the upper and lower study cast by dividers and millimeter rulers. 2 ) To obtain middle of clinical crown divide the measured height of each crown into half and round the obtained value to the nearest 0.5mm.For example if crown height is 10.75mm.Half the crown height would be 5.4 mm. Make this measurement to 5.5 mm

90. 3) Create separate rows of measurements for maxillary and mandibular teeth. Now compare your values of maxillary and mandibular teeth with that of proposed charts. If your chart measurement don't exactly tally with that of proposed MBT charts then find a row on the chart which matches most of your recorded measurement .

91. McLaughlin or MBT vertical bracket positioning

92. Versatility of MBT system: Options for palatally displaced upper lateral incisors.(-10 o ). Three torque options for the upper canines(-7 o ,0 o , +7 o ). Three torque options for the lower canines(-6 o , 0 o ,+6 o ) Interchangeable lower incisor brackets-same tip and torque Interchangeable upper premolar brackets-same tip and torque Use of upper second molar tubes on first molars in non HG cases. Use of lower second molar tubes for the upper first and second molars of the opposite side, when finishing the cases to a class II molar relationship .

93. BONDING MODIFICATIONS VARIATION RATIONALE INDICATION Invert Maxillary lateral Additional labial root torque Palatally placed lateral Reverse lower canine additional distal crown tip Class III camouflage to reduce arch length Invert maxillary canine Additional palatal root torque Buccally placed canine Maxillary 4 on maxillary 3 Limit mesial crown tip Finishing in class II Invert mandibular anterior Additional lingual root torque In recession cases Invert mandibular premolar Additional lingual root torque Scissor bite Invert maxillary premolars Additional lingual root torque Posterior cross bite

94. Limitations of McLaughlin or MBT vertical bracket positioning chart Due to individual variation of cusps height in premolar region, marginal ridges height difference is seen in finished cases as posterior bracketing is not optimum to level marginal ridges.

95. Central incisors brackets are taken as reference . maxillary central incisor bracket (X) mandibular central incisor bracket (Y) Both of them (x)(y) placed at FA point which is center of clinical crown. VIAZIS GUIDELINES FOR BRACKET PLACEMENT

96. The distance from the incisor edge to FA point is measured. Rest of the brackets are placed with reference to these brackets at proposed distance (Table 7.9) with the help of bracket positioning gauges

97. MODIFICATIONS IN VERTICAL POSITION OF THE BRACKETS Bracket placement needed recommended alteration under certain situations as in. :1 . Open bite . 2 . deep bite . 3 . Irregular incisors edges. 4 . Long canine tip . 5 . Attrition of canine . 6 . High buccally placed teeth 7 . Gingival recession . 8 . Premolar extraction

98. OPEN BITE This is done by placing the brackets more gingival on the tooth which are in open bite. In most case of open bite, only maxillary anterior teeth are contributing to open bite and so bracket position alteration should be done in maxillary arch only. But if mandibular arch has a reverse curve of spee then bracket position alteration should also be done in mandibular arch too.

99. The Clinician advocate different rule for bracket placement during treatment of open bite: Alexander proposed that the teeth which are in open bite should be bonded .5 mm more gingival while teeth in occlusion should be .5 mm more occlusal . MBT proposed that teeth which are in open bite should be bonded .5 mm more gingival than their prescribed position, and the rests of brackets are bonded at their normal height.

100. DEEP BITE In deep bite cases the rules of bonding brackets are opposite that of open bite cases.

101. In MBT system teeth which are in deep bite are bonded 0.5mm more incisal while in Alexander discipline teeth which are in deep bite are bonded 0.5 mm more incisal while other teeth are bonded 0.5 mm more gingival.

102. IRREGULAR INCISORS EDGES Clinician suggest 3 options for manage long cusp tip and irregular edges : 1. Recontouring of the incisor edges or cusp tips before bracket placement. 2 . Recontouring of the incisor edges or cusp tips at end of treatment. 3 . Composite filling of the incisor edges and cusp tips.

103. Ideally teeth should be recontoured prior to bracket placement. If teeth are recontoured previous to orthodontic treatment so there is no need to alter the bracket height. But if it is planned to recontour at the end of orthodontic treatment or composite filling is needed at the end of treatment , then height modification of bracket is done at the start of treatment.

104. LONG CANINE TIP In cases where canine tip is long, it's better to place brackets 0.5mm more gingival than standard values and reshape canine tips at the end of treatment. Another option is : to reshape canine tip at the start of the treatment and place bracket at its ideal position. Long canine tips are usually found in impacted canines or canine placed out of occlusion. buccally placed canine lack of function and attrition

105. ATTRITION OF THE CANINE . In case of attrition of the canine the brackets are placed 0.5-1 mm more gingival, depending upon the severity of attrition. The canine tip is reshaped at the end of treatment.

106. HIGH BUCCALLY PLACED TEETH

107. GINGIVAL RECESSION Individual teeth with up to 1.5mm gingival recession can be bonded more gingival so that at end of treatment their gingival margins should be at the ideal height. But incisor or occlusal edge needed to be reshaped by equal amount. In teeth with more than 1.5 mm of gingival recession an expert opinion from periodontist should be taken and many a time gingival grafting is a viable option than bracket position alteration.

108. PREMOLAR EXTRACTION CASES

109. IMPORTANCE OF VERTICAL POSITION OF BRACKETS

110. BRACKET POSITIONING GAUGES • Bracket positioning gauges are used to ensure vertical accuracy of brackets on the teeth. Many different instruments have been recommended to check for vertical accuracy of seated brackets ranging from periodontal probes to rulers but

111. In contemporary orthodontics two types of gauges or their variations are usually used. These are : 1. Star shaped gauges or Boone bracket gauges.

112. 2.Straight rod shaped gauges or Dougherty gauges.

113. PARTS OF GAUGES All bracket positioning gauges have a holding arm for holding the gauge with fingers during bracket positioning, a tooth supporting arm which rest on the incisor or occlusal surface of the tooth and a slot supporting arm which is seated in slot of the bracket. The holding arm is the longest part of gauges while the slot supporting arm is the shortest part of the gauges. Different slot supporting arms are available for 0.018” and 0.022” slots.

114. POSITION OF THE GAUGE DURING BRACKET PLACEMENT For correct positioning the gauge should be held in hand at right angle so that the orthodontist vision should also be at right angel to the gauge. The gauge should always be placed perpendicular to the labial or buccal surface of the teeth. This makes the gauges parallel to the occlusal surface in all the teeth except incisors. In lower arch if the incisors are upright the gauge should be placed parallel to the occlusal plane .

115. In case of upper incisors the gauge is placed slightly upward angulated usually 15° to 20° to the occlusal plane to make it perpendicular to the labial surface of the tooth as the upper incisor are slightly inclined forward over basal bone. But if the lower incisors are proclined the gauge is placed below the occlusal plane and if the lower incisors are retroclined the gauge is directed from above the occlusal plane .

116. • In case class II div 1 incisor relationship where the upper incisors are proclined the gauge is angulated more upward as compared to normal incisor inclination . • In case of class II div 2 the gauge lies below the occlusal plane angulated at an angle depending upon the severity of malocclusion.

117. BRACKET PLACEMENT BY WIRE GUIDANCE In this technique all the steps of conventional bonding are done in usual way but before curing the bracket a heavy wire is passed through the bracket slot and its bonded neighboring brackets and bands. The mesiodistal position of the bracket is corrected manually while axial and vertical positions are guided by the heavy wire . Orthodontic brackets can be placed by wire guidance if brackets are debonded when 0.016x0.022 inch or heavier wire is in place. If brackets are placed in usual way then due to small human errors, mostly it is not possible to place the existing working wire after bracket rebonding and clinician need to move back on lighter wires.

118. Bracket Placement errors with the Preadjusted Appliance 1 . Horizontal errors . Placing the bracket to the mesial or distal of the vertical long axis leads to undesirable tooth rotation. Such errors can be avoided by visualizing the vertical long axis—directly from the facial surface, or with a mouth mirror from the incisal or occlusal aspect. Some orthodontists even draw a line on the tooth to indicate the correct vertical long axis. Horizontal bracket placement errors can be avoided with careful technique.

119. 2 . Axial or paralleling errors . If the bracket wings are not parallel to the long axis, the result will be unwanted crown tipping. These errors can be avoided in the same way as horizontal errors. Axial or paralleling errors can be avoided with careful placement technique.

120. 3. Thickness errors. Leaving excess adhesive under a portion of the bracket base or failing to conform the base accurately to the contour of the tooth can cause improper torque or rotation. This problem is overcome by expressing all excess adhesive from beneath the bracket during placement and by more accurate contouring. Excess adhesive beneath bracket base can cause thickness and rotational errors.

121. 4. Vertical errors. Improper vertical placement can lead to extrusion or intrusion of teeth, as well as to torque and in-out errors Improper vertical placement can lead to extrusion or intrusion and to torque and in-out errors.

122. POSITION OF CLINICIAN DURING BRACKETS PLACEMENT The clinician position for bracket placement given here are for right handed orthodontist. For left handed orthodontist similar positions would be used from the left side.

123. Conclusion Accurate bracket positioning is essential, so that the built in features of the bracket system can be fully and efficiently expressed.This helps in treatment mechanics and improves the consistency of the results.

124. THANK YOU