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Precision attachments1 /certified fixed orthodontic courses by Indian dental academy


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Precision attachments1 /certified fixed orthodontic courses by Indian dental academy

  1. 1. Precision Attachments INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Contents           Introduction History Uses Goals Mechanism of action Indications Contraindications Advantages Disadvantages Classification
  3. 3.           Materials used in attachment fabrication Treatment planning The free end saddle The bounded saddle Over dentures Auxiliary attachments Milling using a precision parallelometer Use of precision attachments with implants Conclusion Bibliography
  4. 4. Introduction    Precision attachments offer considerable advantages in dentistry because of their flexibility. Nevertheless they have in the past been largely ignored by most dental professionals for understandable reasons. Precision attachments consist of two halves, a matrix and a patrix, that form a precise but separable joint.
  5. 5. Precision attachments are defined as ; A retainer used in fixed and removable prosthesis construction consisting of a metal receptacle and a closely fitting part. The former is usually contained within the normal or expanded contours of the crown and the later is attached to the pontic or denture framework. 
  6. 6.
  7. 7. Synonyms Internal attachments  key and key-way attachments  parallel attachments  slotted attachment Male attachment female attachment -patrix -matrix -flange -slot -insert, fitting part -receptacle -key -keyway, crypt 
  8. 8. History     Prior to 1888, both winder and parr invented devices which were clearly attachments in principles and construction. In 1906 Dr. Herman E.S. Chayes invented a detachable suspender device which formed the fundamental feature of his dental attachment. In 1912 he designed the Chayes attachment called bucco-lingual attachment which forms the basic pattern for the modern frictional grip attachment. 1951 Mc collum made the greatest progress in the development of precision attachment.
  9. 9. Uses     They are used to overcome alignment problems where abutments have differing paths of withdrawal. As connecters in fixed partial denture construction. To retain removable partial dentures. To retain overdentures.
  10. 10. Goals    To provide an efficient masticatory replacement of lost dental organs. To relate the designed platform to the available tooth support. To allow normal anatomic forms to the abutment teeth.
  11. 11.     Should be removable and replaceable without stress and strain on the abutment teeth. Should be capable of being tissue supported in a controlled manner. Should allow for various Occlusal patterns. Should provide many years of comfortable service.
  12. 12.    To have minimum amount of tooth structure removed. To place minimum amount of strain on abutment teeth. To be esthetically acceptable.
  13. 13. Mode of action of precision attachments      Friction Binding Wedging of conical bodies Internal spring loading Active retention
  14. 14. Friction:    It occurs when parallel walls of closely fitting bodies pass over one another. The frictional force is directly related to the area of the opposing surfaces as well as to the length of axial walls. The shape of the passage also plays a substantial role.
  15. 15.  The holding ability of the frictional attachments can be enhanced by addition of active retention elements .  They are spring loaded bolts or plungers. Ring springs Leaf springs Bolts Rubber devices.
  16. 16. Binding:  It occurs when a parallel walled body tips with in the receptor site.  Eccentric loads or frictional elements produce tipping movement,which enhances trans additional binding effect significantly increases resistance to withdrawal.
  17. 17. Wedging of conical bodies:  Friction comes to play only in the terminal position and is lost as soon as the bodies began to separate.
  18. 18. Internal spring loading    This is produced by a clip with in a cylinder. The friction with in retainers is often increased by loading with internal spring clips. Slots in the male portion allows the pressure to be adjusted.
  19. 19. Active retention:    That is when one body must be temporarily deformed to be withdrawn from its fully seated position. Active retention means a physical obstruction to separation of other parts. One part must undergo elastic deformation before separation can occur.
  20. 20. Indications Depending on what the attachment is designed to accomplish.  Primary indication is for clasp elimination when esthetics is of prime importance.  For patients with reduced periodontal support.  In patients where cross arch stabilization is desired.
  21. 21.  The attachment is indicated in combination with fixed and removable prostheses.  The attachment is indicated where removable partial denture design require stress equalization which is of paramount importance.  Long span edentulous areas.  To stabilize unilateral saddles.
  22. 22. Contraindications     Poor mental attitude of the patient is a definite contraindication. Poor oral hygiene. One of the primary contraindications for these prosthesis is space, whether it be vertical, bucco-lingual, mesio-distal, circumferential, or interproximal. In healthy mouths not requiring restoration for other reasons.
  23. 23. Advantages     The principal advantage of attachments for removable partial denture is esthetics. Retention is an advantage for overdentures abutments. Stress distribution. Cross arch stabilization.
  24. 24. Disadvantages       The cost of the service is major factor. Attachments are expensive. Additional post-insertion care is required. Additional chair and laboratory time is needed. Greater experience and knowledge on the part of the dentist and laboratory technician are essential. Require repair and replacement.
  25. 25. Classification
  26. 26. Classified in number of ways:  Based on fabrication 1.Semi precision 2.Precision. Based on function 1.Resilient 2. Non-resilient. 
  27. 27. By Ray Active attachments e.g.: split patrix, crismani. Passive attachments e.g.: passive mega attachments
  28. 28. By Collin. R. Corwell. Based on the shape and location 1.coronal-Intracoronal ---frictional mechanical -Extra coronal eg:Dalbo hinge - circumcoronal eg:Telescopic crown 2.Radicular-eg:Rotherman 3.Interdental-eg:Ackerman 4.Auxiliary-eg:Ipsoclip 
  29. 29. Based on location or placement [by preiskel] 1.Intracoronal 2.Extracoronal 3.Studs 4.Bars 
  30. 30. According to Gareth Jenkins 1.Extra Coronal 2.Intra Coronal 3.Auxiliary 4.Achors 5.Bars
  31. 31. Extra Coronal Precision Attachments:     It can be Rigid or Resilient. Distributes the potential harmful forces away from the abutment to the edentulous ridges. This is useful with free end saddles. The Patrix is completely outside the normal contour of that retainer. The Matrix is housed with in the prosthesis.
  32. 32. Extra coronal Rigid Slide Attachments: Bi-Nat Attachments    Height : 4mm. Application: Bilateral free end saddles,Removable and fixed partial dentures. Activation:There is a synthetic friction buffer housed in the patrix , turn the locking screw to expand the synthetic friction buffer and increase the retention.
  33. 33.
  34. 34.
  35. 35. Extra coronal resilient attachment: Dalbo-s resilient joint:  Height : 5mm.  Application: Bilateral and unilateral free end saddles,long denture saddles.  Activation:Bend lamellae of the matrix towards the center with an instrument.
  36. 36.
  37. 37. PR Hinge Attachments:  Height : 4.5mm.  Application: Bilateral and unilateral free end saddles.  Activation:To increase retention ,screw in the locking screw which is housed in the matrix.
  38. 38.
  39. 39. Intra Coronal Precision Attachment    Here the matrix is contained with in the contour of the crown. It is useful during the preparation to have either the attachment or plastic dummy to help ensure that sufficient space is provided. There are two groups of intra coronal attachments, non adjustable and adjustable.
  40. 40. Non adjustable intra coronal Attachments: Rod and tube attachments   Application:Fixed partial dentures with a minor alignment problem of the abutments. Used as a connector for dentures and to support one end of the removable partial denture which is retained at the other end by an adjustable retentive attachment.
  41. 41. Key and Keyway Laboratory made attachment:  Application: used to correct minor alignment problems in fixed partial dentures and in fixed and semi fixed dentures when minor and major retainers are used.
  42. 42. Adjustable Intra Coronal Attachments: Ancra Attachments  Application : Removable fixed partial dentures,Cross arch stabilization,partial dentures and minor alignment problems with posterior abutment teeth.  Activation: Expand the slot with a suitable instrument.
  43. 43. Anchors      These attachments are used on either roots or implants to retain overdentures or removable partial dentures. The patrix is soldered to the diaphragm of a cast post and the matrix contained in the denture. There are two basic types-Rigid and Resilient. Rigid attachments are used in bounded unilateral or bilateral saddle cases. Resilient attachments are used in bilateral free end saddle cases.
  44. 44.
  45. 45. Rigid Anchors: eccentric rothermann attachment    Height: 1.1 mm Application: to retain rigid hybrid dentures. Activation: bend the clasp arms of the matrix towards the centre.
  46. 46.
  47. 47.
  48. 48. Resilient Anchors compact anchors:    Height: 2.85mm Application: To retain over dentures. Activation: bend the lamellae of the matrix towards the centre.
  49. 49. Bar Attachments      The bar being in the patrix is attached to the retainers while the matrix sleeve or clips or riders are processed into the dentures. They are used to retain overdentures or removable partial dentures. They can also be used in conjunction with crowns and implants. They are either commercially or laboratory manufactured. Bars can be Resilient or Rigid.
  50. 50. Rigid Bars Rigid Dolder bar:  Height: 3.5mm  Application: partial, hybrid and implant dentures.  Activation: Bend both sides of the sleeve towards the centre with an activating tool.
  51. 51.
  52. 52. Resilient bar: Ackermann Bar and Clip:  There are two types of Ackerman bar: 1] round 2] egg shaped The round bar is most frequently used as it can be bend more easily to follow the contour of the ridge and arch.
  53. 53.  Applications: Partial dentures,over dentures and implant dentures.  Activation: Bend both sides of the clip towards center with an instrument.
  54. 54.
  55. 55.
  56. 56. Auxiliary Attachments This group of attachments covers a wide range of applications.  They serve these situations ; a.] Allows planning which will enable the clinician to remove the prostheses for repair or conversion. b.] Overcome alignment problems which arise when abutments converge, making it impossible to prepare them so that they can be mutually withdrawn when constructing fixed partial dentures. 
  57. 57. c.] Replace the loss of soft tissue in anterior fixed partial dentures. Supplements retention on bars and telescopic crowns.
  58. 58. Presso -Matic:  Application: To supplement the retention on milled laboratory- made bars and telescopic crowns used to retain removable partial dentures and over dentures.  Activation:Replace the plastic cushion and plunger.
  59. 59. Screw and Tube Attachments:  Applications : To overcome minor and major withdrawal problems where abutments cannot be paralleled and to provide contingency planning for long span fixed partial dentures and full arch restorations when used in conjunction with inner thimble crowns.
  60. 60.
  61. 61. Materials used in attachment fabrication     Platinum Iridoplatinum Gold and platinum Gold and palladium
  62. 62. Treatment planning     Essential information which must be obtained for an adequate treatment plan includes: Medical and dental history Discussion of patient expectations Extra oral examination.
  63. 63.      Intraoral examination Periodontal survey Occlusal analysis Radiographs Study models
  64. 64. Medical and dental history    It is important to know significant previous history. If the patient has already undertaken restorative work of a complex nature that has failed, then the reasons for such failure must be examined. The ability of the patient to withstand long clinical procedures should be assessed at this early stage.
  65. 65. Discussion of patient expectations   Patient should be encouraged to comment on the appearance of their existing teeth, and to discuss their desires for the new ones. These are always the most difficult to satisfy and careful counselling may be necessary to achieve an acceptable compromise.
  66. 66. Extra oral examination   An appraisal can be made almost before the patient is seated in the dental chair. Any asymmetry should be noted.
  67. 67. Intraoral examination   This must include a meticulous examination of all soft tissues, shape of the ridges, and the amount of bone loss. Where gross bone loss precludes the use of conventional fixed partial dentures, precision attachments can often overcome the problem.
  68. 68.    The teeth should be examined for caries, the extent of restorations, colour, vitality, angulations, mobi lity and bony support, tenderness. Consideration should be given to increase the length of crown sufficient for the provision of a fixed partial denture or precision attachment. A full periodontal survey should be carried out.
  69. 69. Occlusal analysis The basic principles of occlusion should be applied to the analysis of each case. These are ,  There should be a stable co-ordinated occlusal contact of the maximum number of teeth in centric relation.  Forces ideally be in line with the long axis of each teeth.
  70. 70.   There should be no non working incline contacts. There must be a balance of anterior and posterior inclines.
  71. 71. Radiographs  Radiographs are essential for assessing the suitability of teeth and their supporting structures for abutments and the retainer of precision attachments.
  72. 72. The free-end saddle     These are classified in to Bilateral free-end saddle And unilateral free-end saddle Extracoranal attachments are preferred against intracoronal attachments.
  73. 73. Bilateral free-end saddle dentures
  74. 74.
  75. 75.
  76. 76.
  77. 77.
  78. 78.
  79. 79.
  80. 80.
  81. 81.
  82. 82.
  83. 83.
  84. 84.
  85. 85. Unilateral free-end saddles  Unilateral saddles can be used in an otherwise intact arch ,or in combination with a bounded saddle on the opposite side of the arch.
  86. 86. Case
  87. 87.
  88. 88.
  89. 89.
  90. 90.
  91. 91. The bounded saddle    Bounded saddles can arise in either the anterior or posterior part of the mouth. They can be found in combination with freeend saddles or with bounded saddles on the same arch. These are easier to treat than free-end saddles.
  92. 92. Anterior bounded saddles     Problems which might arise in this situation and complicate the provision of conventional fixed partial dentures could be due to: Bone loss Unit spacing Lack of parallelism of abutment teeth and preparation.
  93. 93. Bone loss   Where bone loss has been only slight and a gum fitted fixed partial denture is acceptable in appearance, no problem arises. Small deficiencies can be corrected by adding pink porcelain between the pontics.
  94. 94. Bone loss case 1 case 2
  95. 95.
  96. 96.
  97. 97.
  98. 98.
  99. 99.
  100. 100. Posterior bounded saddles
  101. 101. Case-1
  102. 102.
  103. 103. Over dentures  Anchors or stud attachments: Are made in rigid form for bounded saddle situations and in resilient form for free –end saddles. They are generally used in conjuction with posts and diaphragms placed in root canals following root canal therapy. Anchors are usually retained by means of posts with diaphragms.
  104. 104. Case-1
  105. 105.
  106. 106.
  107. 107.
  108. 108.
  109. 109.
  110. 110.
  111. 111. Bar attachments      Spaced teeth which are splinted by a bar are mutually supportive. Burnout resin patterns are available and custom-made bars can be milled in the laboratory. There are two types of bar—round and egg shaped. One advantage of round bar is that it can be bent in all directions. The egg shaped bar has extra rigidity making binding more difficult.
  112. 112. Case-1
  113. 113.
  114. 114.
  115. 115.
  116. 116.
  117. 117.
  118. 118.
  119. 119.
  120. 120.
  121. 121.
  122. 122.
  123. 123. Case-2
  124. 124.
  125. 125.
  126. 126.
  127. 127.
  128. 128.
  129. 129.
  130. 130.
  131. 131.
  132. 132.
  133. 133. Auxiliary attachments a wide variety of attachments all in to this category.these are: 1.screw and tube 2.key and keyway 3.presso-matic or ipsoclip 4.sectional denture 
  134. 134.
  135. 135.
  136. 136.
  137. 137.
  138. 138.
  139. 139.
  140. 140.
  141. 141.
  142. 142.
  143. 143.
  144. 144.
  145. 145. Key and keyway
  146. 146. Pressomatic or ipsoclip
  147. 147. Sectional dentures
  148. 148.
  149. 149.
  150. 150. Milling using a precision parallelometer  The milling of crowns is a precise procedure for creating bracing, ledges and rests in full or partial veneer crowns which serve to retain conventional removable partial dentures.
  151. 151. Milling process
  152. 152.
  153. 153.
  154. 154.
  155. 155.
  156. 156.
  157. 157. The use of precision attachments with implants  Use of precision attachments , in conjunction with the Esthetic cone abutment and the SteriOss PME abutment, to overcome alignment problems between implants and teeth.
  158. 158. EsthetiCone abutments   The estheticone abutment has an overall height of 6.7mm and the abutment collars are either 1, 2 or 3mm in height so that marginal placement can be varied to give the best esthetic results. The interocclusal space must be sufficient to accommodate the height of the abutment as well as the superstructure, otherwise it cannot be used.
  159. 159. Case-1
  160. 160.
  161. 161. Short cantilever fixed partial dentures and overdentures:   If short implants are placed in the anterior part of the mandible in a very shallow curvature, it is unwise to cantilever more than a single unit distally as stresses would be transferred to the screw and fixtures. The design in the following case allows for a complete restoration of the mandibular arch.
  162. 162. Case
  163. 163.
  164. 164.
  165. 165. PME abutments   The PME abutments comes in the lengths of 2, 3, 4, 5 or 6mm. It is made of titanium alloy and is capable of as much as 40 misalignment correction between implants.
  166. 166. Applications are: 1.Fixed-removable full arch reconstructions on six or more attachments. 2.Overdentures supported on implants attached to bar on four to six implants. 3.Tissue supported overdentures attached to a bar on two implants. 4.Fixed-removable partial denture on two or more implants. 5.Fixed-removable partial denture attached to natural teeth with precision attachment.
  167. 167.
  168. 168.
  169. 169.
  170. 170.
  171. 171.
  172. 172. Interlocks    Interlocks are extremely useful in restorative dentistry as they allow a degree of both splinting and retrievability. They are also relatively inexpensive. It is necessary to consider the extent and direction of the added force, the length and diameter of the implant, the quality of the bone and the angulation of the implants in that bone.
  173. 173.
  174. 174. Conclusion   The success of prostheses depends on careful treatment planning and attention to the Prosthodontic problems. Careful use of precision attachments with emphasis on advantages, disadvantages, indications, contraindicati ons and mode of action is important for the success of treatment. The dental surgeon who familiarizes himself with precision attachments will add new dimension to his treatment options.
  175. 175. Bibliography     Precision attachments-a link to successful restorative treatment---Gareth Jenkins. Precision attachments in Prosthodontics--preiskel. Removable Partial Prosthodontics – Ernest L. Miller & Joseph .E.Grasso. Essentials of complete denture Prosthodontics – Sheldon Winkler 2nd edition.
  176. 176.     Theory and Practice of Fixed Prosthodontics- Tylman. Prosthodontic treatment for edentulous Patients – -Zarb & Bolender. Removable Partial Prosthodontics- Mc.Cracken’s. Removable Partial Prosthodontics- Stewart.
  177. 177.
  178. 178. Thank you