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journal club presentation on prosthodontics

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oral mucosa pressure caused by mandibular overdenture with different types of attachments

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journal club presentation on prosthodontics

  1. 1.  INTRODUCTION  AIM  MATERIALS AND METHODS  RESULTS  DISCUSSION  RELATED ARTICLES  CONCLUSION  REFERENCES
  2. 2.  Any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants; a dental prosthesis that covers and is partially supported by natural teeth, natural tooth roots, and/or dental implants -GPT Over denture treatment is a notion which precludes inevitability of floating plastic in edentulous mouth - George Zarb
  3. 3. higher levels of patient satisfaction, comfort and quality of life improved chewing ability less surgically invasive economically reasonable better masticatory force According to the 2002 McGill consensus and 2009 York consensus 2-IOD was recommended as first- line therapy for edentulous mandible
  4. 4. ATTACHMENT SYSTEM MATRIX RECEPTABLE COMPONENT MECHANICAL/FRIC TION FIT/MAGNETIC CLIPS OR BARS ADJUSTABLE/REP LACABLE PATRIX FITS CLOSELY WITHIN MATRIX CONNECTING BARS/FREE STANNDING BALL/MAGNETIC ABUTMENTS ONE PART-CONNECTED TO IMPLANT OTHER PART-INCORPORATED WITHIN UNDER SURFACE OF OVERDENTURE
  5. 5. SINGLE ELEMENTS(UN SPLINTED) SINGLE BALL ABUTMENTS SINGLE MAGNET ABUTMENTS INDIVIDUALLY CAST TELESCOPIC COPINGS CONNECTED ELEMENTS(SPLINTED) EGG SHAPED DOLDER BAR ROUND CLIP BAR U SHAPED BAR CUSTOMISED PRECISIONMILLED BAR STRESS BREAKING MECHANISM RIGID MECHANISM STRESS BREAKING MECHANISM RIGID MECHANISM
  6. 6. IOD LOCATORS BARS MAGNETS BALLS
  7. 7. MORPHOLOGY OF RESIDUAL RIDGE POSITION OF IMPLANT ANGLE OF IMPLANT RETENTIVE FORCES PATIENT’S LIFESTYLE PATIENT’S ABILITY TO CLEAN EASE OF MAINTENANCE
  8. 8.  To determine the appropriate attachment and design of a denture base for mandibular implant overdenture (IOD), the oral mucosa pressure caused by mandibular implant overdentures was measured using edentulous jaw models with various attachments.
  9. 9. An experimental mandibular edentulous jaw model with a 1.5mm thick artificial oral mucosa Two dental implants (3.75 11.5 mm) were placed at the position of the bilateral canines, perpendicular to a tentative occlusal plane
  10. 10. Experimental 2-IODs were fabricated • Mainly made of acrylic resin denture base material Each attachment was inserted • connected to the experimental 2-IOD with chemical cure resin material shape of 2-IODs were similar to the record base with occlusion rim morphology that was made according to the standard protocol
  11. 11. • performing retentive forces 0.7 kg , locator abutment, Bmk RP 2.0 mm, Nobel Biocare), Locator attachments with retention discs (LA) • ball abutment, Bmk RP 1 mm, Nobel Biocare Ball attachments(BA) • MA, MAGFIT IP-DXFL, Aichi Steel, Aichi, Japan Magnetic attachments(MA) • NobelProcera Impl Bar Overdenture Ti 2 Impl, Nobel Biocare resilient round-bar attachments (R- BA)
  12. 12. 6 miniature sensors Buccal premolar region Buccal shelves Lingual molar region Six miniature pressure sensors were placed to measure pressure values on the oral mucosa when the experimental dentures were loaded An experimental CD without attachment was prepared as a control
  13. 13.  The load on the experimental dentures was set at 50 N by referring to the masticatory force of CD wearer • The load points were either an area equivalent to the center of the model which should represent equivalent mastication on both sides Bilateral load • an area equivalent to the left first molar which should represent unilateral mastication Unilateral load
  14. 14. BILATERAL LOADING UNILATERAL LOADING A metal plate was placed on the experimental dentures
  15. 15. Precision universal testing machine (Instron 8874, Instron, Norwood, MA, USA). dynamic repetitive loads of 1 Hz were applied perpendicularly to the tentative occlusal plane by precision universal testing machine
  16. 16. The experiments were repeated 5 times each In the CD and the experimental 2-IOD LA BA MA R-BA The oral mucosa pressure values were defined as average values of the load with the precision universal testing machine during 5 continuous cycles. Pressure distributions during the loading were measured with 6-channel frequency sensors 200 Hz sampling rate recorded via a sensor interface
  17. 17. Example of a waveform during the dynamic repeated load. The oral mucosa pressure values were defined as average values of the load with the precision universal testing machine during 5 continuous cycles
  18. 18. Differences in oral mucosa pressure values between CD and 2-IOD Oral mucosa pressure value exerted by 2-IOD was significantly lower in the left buccal premolar region than that of CD Under the unilateral load condition
  19. 19. On the non- loading side, oral mucosa pressure values exerted by all attachments were extremely low and did not exceed 8.0 kPa in the right buccal premolar region and the right buccal shelf
  20. 20.  Changes in oral mucosa pressure values with different attachments •Pressure on the residual ridge exerted by CD was compared to that of 2-IOD with various attachments. •Oral mucosa pressure value exerted by 2-IOD was significantly lower in all sites than that of CD
  21. 21. The oral mucosa pressure value exerted by R-BA was significantly higher in the right lingual molar region than those of other attachments
  22. 22.  2-IOD reduced the oral mucosa pressure value of 37– 190 kPa at the supportive site.  The oral mucosa pressure value exerted by 2-IOD in the left lingual molar region was not always lower than that of CD.  The oral mucosa pressure value was increased significantly by MA and LA, but decreased significantly by BA
  23. 23.  Significant decrease in oral mucosa pressure value and increase in support and bracing ability were observed when 2-IOD was applied, compared with CD.  Effect of BA on the reduction of oral mucosa pressure is greater than LA, MA and R-BA in the supportive and bracing regions  BA could be the first choice to reduce oral mucosa pressure value during mastication.
  24. 24. Nobuhiro Yoda, Yoshiki Matsudate, Masaru Abue, Guang Hong and Keiichi Sasaki
  25. 25.  to investigate how several commonly used attachments of the IOD affect the load on the supporting implants and the residual ridge beneath the denture base in a model study applying those measuring systems.
  26. 26. An acrylic resin mandibular edentulous model was modified Two implants were inserted in the canine region both sides of the edentulous residual ridge, perpendicular to the occlusal plane of the experimental IOD An artificial mucosa made using a silicone impression material approximately 2-mm thick,was affixed to the edentulous molar area, posterior to the two supporting implants of the mandibular model Experiment device development
  27. 27. A film pressure distribution measurement tactile sensor was placed on the artificial mucosa on the right side The artificial mucosa was molded by initially fixing the film sensor to the basal surface of the experimental IOD, followed by polymerizing the silicone under the application of a 5-N load to the occlusal surface of the IOD. The experimental IOD was made using acrylic resin for the denture base material The basic form of the experimental IOD was a ready-made record base with an occlusal rim The occlusal table of the denture was fabricated parallel to the occlusal plane.
  28. 28. • Piezo electric force transducers LOAD ON IMPLANTS • film pressure distribution measurement tactile sensor LOAD ON RESIDUAL RIDGE  Devices for simultaneous measurement of three-dimensional (3D) loads on the supporting implants and the load on the residual ridge beneath the denture base were developed.
  29. 29.  To measure the load on the implants, three types of attachments were fabricated to be fitted accurately onto the piezoelectric force transducers: LOCATOR TYPE ATTACHMENT LA ROUND BAR ATTACHMENT RA BALL TYPE ATTACHMENT BA
  30. 30. Loads on the implants and the residual ridge beneath the denture base were measured when static and dynamic repeated loads of 100 N were applied vertically to the right first molar region of the occlusal table of the denture by a universal testing machine The load measurement was repeated five times for each of the three different attachments in the order BA, LA, and RA
  31. 31. • assumed to be the occlusal force • applied to the right first molar area • crosshead speed of 15 mm/s • continued for 10 s Static load 100N • to simulate a masticatory force • Same area • Cross head speed of 30 mm/s • loading cycle of 2 Hz Dynamic repeated load 100 N
  32. 32. Measured pressure on the residual ridge beneath the denture was converted to a force and analyzed as the total force on the measuremen t area.
  33. 33. • Lateral direction • coincident with the occlusal surface of the IODX axis • Antero-posterior direction • coincident with the occlusal surface of the IODY axis • vertical direction, which was defined to be perpendicular to the occlusal surface of the denture • same in the implant inserted direction. Z axis
  34. 34.  Regardless of the attachment type, the direction of the load exerted on both implants was consistently in a posterior direction.  Force vector on the non loading side implant for the three attachments occurred in an upward direction.
  35. 35. LOADING SIDE • BA>LA>RA NON LOADING SIDE • BA>RA>LA The horizontal component, that is, the resultant force value of the load on the implants in the X- and Y-axes when a static load of 100 N was applied,
  36. 36. LOADING SIDE • BA>RA>LA NON LOADING SIDE • Little difference among 3 • LA Significantly low BOTH LOADING AND NON LOADING SITES • BA>RA>LA
  37. 37. With all attachments- higher load in the distal parts of the sensor area. load centers of the three attachments in similar position, loci of the load center were different among the three attachments. shows the typical pattern of load distribution on the residual ridge beneath the denture under a static and dynamic repeated load of 100 N
  38. 38. RA LA BA
  39. 39. load on the residual ridge beneath the denture base when a static load of 100 N was applied • RA>LA>BA
  40. 40. shows an example of the calculated 3D resultant force data for the three attachments when a dynamic repeated load of 100 N was applied five times. The three attachments showed different wave patterns., but this was • plateau phase between the peaks of the waves BA AND RA • not evident on the loading side implant. LA
  41. 41. 1. This model experiment using piezoelectric 3D force transducers and a tactile sheet sensor enabled us to clarify the effects of the attachments used in an IOD on loading to implants and the underlying residual ridge. 2. Using RA in an IOD is effective for reducing the load to the supporting implants. 3. The load on the residual ridge beneath the denture in IODs can be efficiently reduced using a BA.
  42. 42. Jin Suk Yoo, Kung-Rock Kwon, Kwantae Noh, Hyeonjong Lee, Janghyun Paek
  43. 43.  The design of the attachment must provide an optimum stress distribution around the implant. In this study, for implant overdentures with a bar/clip attachment or a locator attachment, the stress transmitted to the implant in accordance with the change in the denture base length and the vertical pressure was measured and analyzed.
  44. 44. For the strain gauge to have a tight contact with the surface of the implant, buccal and mesial threads of the #43 implant and lingual and distal threads of the #33 implant were properly adjusted, and flat surfaces were obtained. model base was created with epoxy resin Tissue-level Straumann implants were used (diameter 4.1 mm, length 10 mm, to reproduce the implant mandibular overdentures A ridge replication plastic model made for an actual patient was impressed with silicone. alveolar mucosa (2 mm thick) was reproduced with a previously taken impression and polyether impression material
  45. 45. STRAIN GAUGES were attached to the implants using an adhesive In the replicated epoxy model, holes 8 mm in diameter were made at both canine sites and implants were placed. Resin cement was used to represent the osseo integration of actual implants. The maxillary and mandibular dentures on the replication model were fabricated in a conventional manner, and the same dentures were used repeatedly in the experiment by modifying their bases. POSITION OF STRAIN GAUGES CLOSE TO NECK OF IMPLANT BUCCAL SIDE LINGUAL SIDE CLOSE TO APEX MESIAL SIDE DISTAL SIDE
  46. 46. A universal testing machine was used to exert a vertical pressure on the mandibular implant overdenture. To measure the strain rate of the implants placed in the replication epoxy model, a strain gauge was used. An A/D converter was connected to a personal computer to amplify and quantify the electrical signal from the gauge.
  47. 47. • RN synOcta abutment • RN synOcta gold coping • SCS occlusal screw • CM bar • female component of 10 mm length BAR/CLIP ATTACHMENT • RN Locator abutment • BLUE replacement male piece LOCATOR ATTACHMENT
  48. 48. RN synOcta gold coping RN Locator abutment
  49. 49. DENTURES BASED ON LENGTH OF DENTURE BASE GROUP 1: pressure with no modification (intact denture) GROUP 2: pressure after eliminating the denture base distal to mandibular second molar GROUP 3:pressure after eliminating the denture base distal to the mandibular first molar.
  50. 50.  Vertical pressure, 0.5 mm/min up to 50 N, was placed on the three types of complete denture  repeated 10 times  Whenever the attachment was replaced or the length of the denture base was modified, 20 minutes were given for recovery  Results measured with the four strain gauges were analyzed statistically
  51. 51. • vertical pressure on the mandibular right first molar (A) and the mandibular right posterior area (B), the implants on the working side generally showed higher strain than those on the non-working side LOCATOR ATTACHMENT • vertical pressure on the mandibular right first molar (A) and the mandibular right posterior area (B), the implants on the both non-working and working sides showed high strain BAR/CLIP ATTACHMENT
  52. 52.  For the mandibular right first molar, the mandibular right posterior area, and the whole mandibular denture base, the strain was statistically significantly different between the locator attachment and the bar/clip attachment
  53. 53. TENSILE FORCE • Applied on mesial surface of the implant on the working side COMPRESSIVE FORCE • applied to the buccal surface and on the surfaces of the implant on the non-working side all surfaces except the mesial surface of the implant on the non- working side showed a compressive force when applying vertical pressure at three different areas (cases A, B, and C), the bar/clip attachment generally showed a higher strain than the locator attachment For both attachments, the shorter denture base resulted in a higher strain on the implants
  54. 54.  For mandibular implant overdentures, locator attachments result in lower strain on implants than do bar/clip attachments. Longer denture bases have the same effect. Therefore, to minimize the strain on implants in mandibular implant overdentures, this study may provide the clinical implication that the use of locator attachment would be more preferable in regard of strain on implants than bar /clip attachment, and the denture base needs to be extended as much as possible.
  55. 55. Takaharu Goto, DDS, PhD, Kan Nagao, DDS, PhD, Yuichi Ishida, DDS, PhD, Yoritoki Tomotake, DDS, PhD, & Tetsuo Ichikawa, DDS, PhD
  56. 56.  This in vitro study investigated the effect of attachment installation conditions on the load transfer and denture movements of implant overdentures, and aims to clarify the differences among the three types of attachments, namely ball, Locator, and magnet attachments.
  57. 57. Three types of attachments, namely ball, Locator, and magnetic attachments were used. An acrylic resin mandibular edentulous model with two implants placed in the bilateral canine regions and removable overdenture were prepared. The two implants and bilateral molar ridges were connected to three-axis load-cell transducers
  58. 58. Universal testing machine was used to apply a 50N vertical force to each site of the occlusal table in the first molar region. Thedenturemovement was measured using a G2 motion sensor. Three installation conditions, namely, the application of 0, 50, and100 N loads were used to install each attachment on the denture base. The load transfer and denture movement were then evaluated.
  59. 59. X axis- along length Y axis- along width Z axis- as vertical direction Twelve signals from the four transducers and one signal from the load cell were digitized by a digital data recorder with 14-bit accuracy at a rate of 50 Hz, and then transferred to a computer resultant force (FR) was calculated using the following: FR=(M2 x +M2 y +F2 z)
  60. 60. The output of the G2 motion sensor was calculated from the flexibility of the Euler angles (i.e., the pitch, yaw, and roll) using original software with a C-based synthesis system
  61. 61.  A 50 N static load was applied to the loading points of the first molar regions on the right side by a universal testing machine with a 2.0 mm/min crosshead speed.  The magnitude of the applied load was based on the bite force of edentulous patients with complete dentures.  Six complete experimental dentures were fabricated,and six artificial mucosal materials modified for the respective denture bases were also prepared.  The recording was repeated five times for each experimental condition, allowing intervals of at least 5 minutes for recovery
  62. 62. shows the time patterns of the resultant forces acting on the implant and residual ridges on the loading side.The time patterns were obtained by averaging the signal at the onset of the universal testing machine measurements for each condition. The resultant force acting on the implants on the loading side of the magnetic attachment exhibited a two- phase pattern
  63. 63.  For the residual ridges on the loading side, the direction of the forces for all attachments changed to downward with increasing installation load. Furthermore, the yaw Euler angle increased with increasing installation load for the magnetic attachment
  64. 64.  The resultant force acting on the implants on the loading side for the ball and Locator attachments transmitted homogeneous increases without a two-phase pattern. When the attachments were installed using a 50N load, which was the same as the resultant force acting on the implants on the loading side, all the attachments transmitted a homogeneous increase with out a two-phase pattern. The increase in the resultant force acting on the residual ridges on the loading side was greater for a 50 N installation load than for 0 N, especially for the Locator attachment. No distinctive pattern was observed in the resultant force acting on the implant residual ridges on the non loading side.
  65. 65. The resultant force on th implants decreased with increasing installation load for all attachments The resultant force acting on the residual ridges on the loading side increased with increasing installation load for all the attachments. The resultant force acting on the residual ridges on the non loading side was not greater than that acting on the ridges on the loading side for all attachments
  66. 66. • The resultant force acting on the implant on the nonloading side significantly decreased when the installation load was increased from 0 to 50 N BALL AND LOCATOR ATTACHMENT • smaller resultant force than the ball and Locator attachments for all installation loads MAGNETIC ATTACHMENT • significantly decreased when the installation load was increased from 0 to 50 N Locator attachment • significantly decreased when the installation load was increased from 50 to 100 N Magnetic attachment
  67. 67. • 18.1 to 23.9 N 0 N • 4.01 to 15.9 N 50 N • 0.44 to 11.0 N 100 N The resultant force acting on the implants on the loading side The resultant force acting on the residual ridge on the loading side • 0.87 to 1.15 N0 N • 1.22 to 2.21 N 50 N • 1.65 to 2.43 N 100 N
  68. 68. Installation load 0N BALL ATTACHMENT DOWNWARD LOCATOR ATTACHMENT BACKWARD AND DOWNWARD MAGNETIC ATTACHMENT FORWARD AND DOWNWARD NON LOADING SIDE Residual ridges on loading sides Installation load 0 N BALL ATTACHMENT DOWNWARD LOCATOR AND MAGNETIC ATTACHMENT DOWNWARD TO BACKWARD
  69. 69. ON INCREASING INSTALLATION LOAD LOCATOR AND MAGNETIC ATTACHMENTS DOWNWARDS TO BACKWARDS AND AGAIN TO DOWNWARDS BALL ATTACHMENTS DOWNWARDS The direction of the forces of all the attachments changed to downward with increasing installation load. None of the forces of the attachments acting on the residual ridges on the nonloading side had a distinctive direction. when the installation load was 0 N, the forces of the ball and Locator attachments were horizontal and large compared to that of the magnetic attachment.
  70. 70.  The magnetic attachment had a high yaw Euler angle compared to the ball and Locator attachments for all installation loads.  The yaw Euler angle increased with increasing installation load for the magnetic attachment, and particularly increased significantly when the installation load was increased from 50 to 100 N.  Simultaneously, the Euler angles of pitching and rolling slightly increased in the negative direction.The ball and Locator attachments did not exhibit this distinctive movement
  71. 71.  Subject to the limitations of this study, the use of any installation load greater than 0N is recommended for the installation of ball and Locator attachments on a denture base. Regarding magnetic attachments, our results also recommend installation on a denture base using any installation load greater than 0N, and suggest that the resultant force acting on the implant can be decreased by increasing the installation load; however, a large installation load of 100 N should be avoided when installing the attachment on the denture base to avoid increasing the denture movement
  72. 72. AsukaHaruta, YasuyukiMatsushita, YoshihiroTsukiyama,YoshinoriSawae, NobuoSakai, and Kiyoshi Koyano
  73. 73.  to compare the effects of mucosal thickness on the stress pattern around implants and movement of implant-supported overdentures with ball/female and three different types of magnetic attachments.
  74. 74. Two rootform implants were inserted into mandibular model Surface of the model was covered with a 1.5- or 3-mm layer of impression material to simulate the oral mucosa removable overdentures were fabricated on each model A 50-N vertical force was applied to the right first molar the resultant stress distribution and denture movement were measured
  75. 75. Each experiment was repeated five times under the same conditions. Each sequence of strain data was used to calculate the axial force and the bending moment transmitted to the implant Loads from 0 to 50N were applied gradually to simulate a moderate level of biting force on an implant-retained overdenture Autograph applied a load to the occlusal surface of the right first molar region Point to receive the load with the largest force during function
  76. 76. Experimental Mandibular Model. An edentulous mandibular acrylic resin model Two implants were placed bilaterally in the canine region vertical to the residual ridge. They were set at 22 mm apart, similar to the distance between two natural canines. The implants were retained using resin cement
  77. 77.  A 1.5-mm layer was removed from the denture- supporting surface of the resin model and replaced with polyvinyl siloxane impression material to simulate the resilient edentulous ridge mucosa. An experimental acrylic resin denture was conventionally fabricated on the model.  In the same way, a 3-mm layer of impression material and a denture were fabricated on the same mandibular model. All experiments for the four attachments were carried out with one model of each mucosal thickness.
  78. 78. Four strain gauges were attached to the mesiodistal and buccolingual sides of the neck part of each implant to measure the strain on the implants The electric signals from the strain gauges were amplified, transmitted, and recovered by a personal computer following A/D conversion The sensor used electromagnetic fields to determine the position and orientation of a remote object. The output of the movement sensor was input into a computer and a mathematic algorithm calculated the position of the receiver relative to the transmitter and recorded the results.
  79. 79. denture movement at the loading side (right first molar region) was measured by vertical displacement of Autograph .
  80. 80. The ball attachment consisted of an anchor head and a metal female component
  81. 81. The flat type was a typical magnetic attachment,whilethedome-shaped type had a dome-shaped surface of the magnet and keeper, and the cushion type had a stress distributor with a magnet
  82. 82. plus-force -tensile stress minus-force - compressed stress.
  83. 83. 1.5mmmodel3mmmodel  the ball attachment showed a significantly higher axial force on the implants than all the magnetic attachments at both the loading and non-loading sides  ball attachment had a lower vertical force than all the magnetic attachments at the loading side and had a tensile stress at the non-loading side.  dome-shaped type caused the highest axial force at the loading side.  no significant differences among the three magnetic attachments in the 3-mm mucosal model at the non-loading side.
  84. 84. 1.5mm3mm  all the magnetic attachments showed significantly lower bending moments on the implants than the ball attachment at both the loading and non-loading sides  the magnetic attachments were higher than that of the ball attachment at the loading side. At the non-loading side, all the magnetic attachments showed lower bending moments than the ball attachment. The dome- shaped type caused the largest bending moment at the loading side, while it caused the lowest bending moment at the non-loading side. The flat type made a smaller bending moment than the dome-shaped type and cushion type at the loading side in each mucosal model.
  85. 85. plusmovement - upward displacement Minus movement -downward displacement
  86. 86. 1.5mmmucosalmodel3mmmucosalmodel  denture base movements were larger on the ball attachment at both the loading and non- loading sides. At the loading side, the denture movement was the lowest on the flat type. On the other hand, at the non-loading side, the denture movement was very small on the magnetic attachments  Denture base movement was larger on the cushion type. At the non-loading side on the 3-mm mucosal model, upward movement was shown on the magnetic attachments.
  87. 87.  In the 1.5-mm mucosal model, the magnetic attachments showed significantly lower bending moments than did the ball attachment.  The denture base displacement was the lowest on a magnetic attachment.  In this study, use of magnetic attachments could be advantageous for mandibular implant- supported overdentures based on lower stress and better denture stability especially in the thin mucosalmodel.
  88. 88.  Within the limits of this study, the findings indicated that the magnetic attachments were more favorable than the ball attachment in terms of the stress distribution and the denture base stability on a thin mucosa. For a thick mucosa, the flat type caused the smallest bending moment and denture base movement among all the attachments, suggesting that the flat type was the most favorable for this condition.
  89. 89.  H. Sato, et al., Oral mucosa pressure caused by mandibular implant overdenture with different types of attachments, J Prosthodont Res (2019)  Goto T, Nagao K, Ishida Y, Tomotake Y, Ichikawa T. Influence of matrix attachment installation load on movement and resultant forces in implant overdentures. J Prosthodont 2015;24:156–63  Yoda N, Ogawa T, Gunji Y, Kawata T, Kuriyagawa T, Sasaki K. The analysis of the load exerted on the implants supporting an overdenture based on in vivo measurement. Prosthodont Res Pract 2008;7:258–60.
  90. 90.  Yoda N, Matsudate Y, Abue M, Hong G, Sasaki K. Effect of attachment type on load distribution to implant abutments and the residual ridge in mandibular implant-supported overdentures. J Dent Biomech 2015;6:1–10  Assunção WG, Barão VA, Tabata LF, de Sousa EA, Gomes EA, Delben JA. Comparison between complete denture and implant-retained overdenture: effect of different mucosa thickness and resiliency on stress distribution. Gerodontology 2009;26:273–81.

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