Diagnosis and treatment planning in implants 2. /certified fixed orthodontic courses by Indian dental academy


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Diagnosis and treatment planning in implants 2. /certified fixed orthodontic courses by Indian dental academy

  1. 1. Diagnosis and treatment planning in implants . INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. • Pre implant considerations • Evaluation of natural teeth adjacent to implant site • Bone evaluation. 1. 2. 3. 4. Existing occlusion. Existing occlusal plane, orientation. Interarch space Existing vertical dimension of occlusion. Abutment mobility 5. 1.Maxillomandibular arch relationship Pier abutment 6. 2.Temperomandibular joint status 3. Terminal splinted abutment. 7. Existing prosthesis. 4. Crown size 8. 5.Arch form(anteroposterior distance). Crown-root ratio 9. 6.Implant ideal permucosal position. Endodontic status 7. Root configuration 10. Missing teeth: location 8. Tooth teeth: 11. Missingposition number 9. Parallelism 12. Lip line at rest and during speech. 10. Arch position 13. Mandibular flexure. 11. caries 14. Soft tissue support. 12. Periodontal status. www.indiandentalacademy.com
  3. 3. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Pre implant considerations. Existing occlusion. Existing occlusal plane, orientation. Interarch space Existing vertical dimension of occlusion. Maxillomandibular arch relationship Temperomandibular joint status Existing prosthesis. Arch form(anteroposterior distance). Implant ideal permucosal position. Missing teeth: location Missing teeth: number Lip line at rest and during speech. Mandibular flexure. www.indiandentalacademy.com Soft tissue support.
  4. 4. Existing occlusion • The relationship of centric occlusion to centric relation is to be noted because. – – – • Of potential need of occlusal adjustments to eliminate deflective tooth contacts. Evaluation of their potential noxious effects on the existing dentition. For planned restoration. Correction may involve one or more of the procedures. 1. Selective odontoplasty 2. Restoration with the crown (with or without Endodontic therapy) 3. Extraction of the offending tooth. www.indiandentalacademy.com
  5. 5. Existing occlusal plane orientation • Aids to evaluate the needed changes. – Pretreatment diagnostic wax up. – Occlusal plane analyzer. Following changes can be seen in opposing dentition – Drifting – Tilting – In partially edentulous ridge more facial resorption may require implant insertion more medial in relation to the original central fossa of the natural dentition. www.indiandentalacademy.com
  6. 6. • A proper curve of spee and curve of Wilson are indicated for proper esthetics and to prevent posterior lateral interferences during excursions. • A steep incisal guidance may help avoid posterior interferences in protrusive movements. – If its shallow,it may be necessary to plan recontouring or prosthetic restoration of any posterior offending teeth. – A mesially tipped mandibular third molar may greatly compromise the implant placed in the maxillary posterior region. • Remedy – Odontoplasty – Endodontic therapy, – And /or extrusions of adjacent or opposing natural teeth. www.indiandentalacademy.com
  7. 7. Interarch space. Type of restoration Anterior Posterior Fixed removable 8-10 mm 7 mm 12 mm. 12 mm www.indiandentalacademy.com
  8. 8. Increased space • Results from vertical loss of alveolar bone and soft tissues. • Increased space makes the placement of removable prosthesis easier. • In fixed restorations increased space makes – Replacement teeth elongated. – Placement of gingival tone materials – Increased crown height increased moment of force on implants increased risk of component and material fracture. www.indiandentalacademy.com
  9. 9. Management of increased Interarch space. • May be decreased by addition of onlay grafts before implant placement. – Autogenous and /or membrane grafts. – Alloplastic grafts • It improves – – – – – Crown –implant ratio Esthetics Permits wider implant selection. Benefit of increased surface area. Improves hygiene condition. www.indiandentalacademy.com
  10. 10. Lack of Interarch space. • Results from – migration of the opposing natural dentition into the edentulous space. – History of tooth abrasion,attrition and skeletal insufficiencies – Even when the opposing teeth are extracted or missing the Interarch space is still less as the alveolar process has followed the teeth. • Consequences. – – – – Decreased abutment height Inadequate retention. Inadequate bulk for esthetics and strength Poor hygiene conditions. www.indiandentalacademy.com
  11. 11. Management of less Interarch space. 1. Surgical reduction of tuberosities. 2. Osteoplasty and /or soft tissue reduction of implant region 3. Selective grinding 4. Prosthodontic restorations 5. Endodontic therapy. www.indiandentalacademy.com
  12. 12. Existing vertical dimension of occlusion • Patients who have been partially or fully edentulous for several years may exhibit a collapsed OVD. • Assessment to be done as it influences – Inter arch space – Anteroposterior jaw relationship. • Techniques used in traditional prosthodontics can be used in this. www.indiandentalacademy.com
  13. 13. Maxillomandibular arch relationship • An improper skeletal position may be modified by orthodontics and/or surgery. www.indiandentalacademy.com
  14. 14. • Anterior edentulous maxilla decreases 40% within few years at the expense of labial plate. • Implants are placed lingual to original incisal position. • Final restoration Is over contoured for •Esthetics •speech •lip position •occlusion. • Cantilevered force on the anterior implant body. • To compensate for the increase in lateral loads and moment of force • additional implants www.indiandentalacademy.com • increase in the anteroposterior distance between implants.
  15. 15. • An anterior cantilever on implants in the mandibular arch may correct an angle’s skeletal class II jaw relationship. • A complete denture cannot extend beyond the bone support or neutral zone of the lips without decreasing stability of the prosthesis. • However implants can permit the placement of the replacement teeth in a more ideal esthetic and functional position. • The anterior cantilever is dependent on the presence of sufficient anteroposterior distance between the implants. • To counter the cantilever effect, the treatment plan should provide increased implant support. www.indiandentalacademy.com
  16. 16. • Edentulous maxillary posterior arches resorb towards the palate. • Ridge is medial to the opposing mandibular tooth central fossa. • Posterior teeth may be placed in a cross bite to decrease the moment of forces developing on the maxillary posterior teeth. www.indiandentalacademy.com
  17. 17. Temporomandibular joint status • Signs and symptoms of dysfunction. – – – – – Pain Muscular tenderness Noise Clicking Limited jaw movements. • Maximal opening is noted – Normal 38-40 mm from maxillary incisal edge to mandibular incisal edge.in angle’s skeletal class I patient. www.indiandentalacademy.com
  18. 18. • Deviation on opening should be noted and typically takes place on the same side as symptomatic TMJ. • The patient should be able to perform unrestricted mandibular excursions. • Patient should ideally be free of symptoms before implant therapy can be considered. • Many patient with soft tissue prosthesis and TMJ dysfunction benefit from the stability and exacting occlusal aspects the implant therapy provide. www.indiandentalacademy.com
  19. 19. Existing prosthesis. • Removable partial soft tissue –supported restoration opposing the proposed implant supported prosthesis. • Occlusal forces will change once the implant supported prosthesis will be placed • Forces will vary as underlying bone remodels. • Constant maintenance and follow up are indicated, including reline and occlusal evaluation. www.indiandentalacademy.com
  20. 20. • Existing prosthesis which has to be replaced with implant supported prosthesis. – To be evaluated for Esthetics – Contour arrangement and position of the teeth are evaluated. • Pretreatment prosthesis is indicated when – – – – – Patient unsatisfied with esthetics TMJ dysfunction Poor soft tissue health Decreased OVD Collapse of posterior support. www.indiandentalacademy.com
  21. 21. • Acceptable preexisting maxillary removable prosthesis is used as a template for implant reconstruction. • lip position and support provided by Labial flange is evaluated . • If support is less without flange, a hydroxyapatite(HA) labial onlay graft is usually indicated. www.indiandentalacademy.com
  22. 22. Arch form (anteroposterior distance) • Edentulous arch forms are 1. Ovoid-most common. 2. Taperingfound in class II skeletal patients as a result of Para functional habits during growth and development. 1. Square. • • may result from initial formation of the basal skeletal bone Labial bone resorption of the premaxilla region when anterior teeth are lost earlier than the canine and posterior teeth. www.indiandentalacademy.com
  23. 23. • The distance from the center of the most anterior implant to a line joining the distal aspect of the two most distal implants is called the anteroposterior distance or A-P spread. • It provides an indication of the amount of cantilever that can be reasonably planned. www.indiandentalacademy.com
  24. 24. • The predominant factors to determine the cantilever length are related to stress, not the A-P distance. • Factors to determine length of cantilever. • • • • • • • • • • • Parafunction (most important) Arch position Masticatory dynamics. Opposing arch Crown height Direction of force Bone density Implant number Implant width. Implant design A-P distance. www.indiandentalacademy.com
  25. 25. Posterior cantilevered • The arch form is an important determinant when anterior implants are splinted together to cantilever the restoration to the posterior regions. • In this situation square arch form provides poorer prognosis than the tapered arch forms. • As a general rule, when 5 anterior implants in the mandible are used for the prosthesis support, the cantilevered posterior section of the restoration should not exceed 2.5 times the A-P spread when all stress factors are low. www.indiandentalacademy.com
  26. 26. Anterior cantilever • In advanced anterior maxillary arch resorption the implant may have to be placed at the canine locations • The resulting restoration is a fixed,anteriorly cantilevered prosthesis when the original arch form is restored. • Greater stress results for tapered arch forms compared with square arch forms all other factors being identical. www.indiandentalacademy.com
  27. 27. www.indiandentalacademy.com
  28. 28. • The cantilever to replace a tapered arch form requires the support of additional implants of greater width and number. • In maxilla the recommended anterior cantilever dimension is less than for the posterior cantilever in the mandible as – Bone is less dense – Forces are directed outside the arch during excursions. www.indiandentalacademy.com
  29. 29. Implant ideal permucosal position. • An implant placed in the improper position can compromise the final results in esthetics biomechanics and maintainnence. • Use of surgical template for implant placement is strongly suggested in most edentulous regions. • It should provide both ideal implant permucosal placement and angulations information. www.indiandentalacademy.com
  30. 30. Facial placement • Results in compromised – esthetics Phonetics Lip position Function • Angled abutment may help improve the condition. • It increases the forces on the crest of the bone Labial cortical plate is much thinner and hence cervical bone loss is common in these conditions. www.indiandentalacademy.com
  31. 31. Lingually positioned. • It is easier to correct in final restoration. • Thicker lingual plate provides initial stability • As implant body is half the diameter of the adjacent teeth, the final crown is not necessarily over contoured on the lingual aspect. www.indiandentalacademy.com
  32. 32. • An implant placed too far mesially or too distally is of less consequence if lip does not expose the cervical third of the restoration. • The final restoration is constructed with the interproximal incisal two thirds ideal for esthetics, independent of implant placement. • Hygiene is compromised, but the crown can be designed to allow daily care. www.indiandentalacademy.com
  33. 33. Missing teeth: location • The number and location of missing teeth influences the prosthodontic treatment plan of the patient. • The second mandibular molar is not replaced in posterior implant supported prosthesis. • The mandibular first molar is designed to occlude with the mesial marginal ridge of a natural second molar to prevent extrusion. www.indiandentalacademy.com
  34. 34. Disadvantages of replacing mandibular second molar. 1. 2. 3. 4. 5. 6. 7. 90% chewing efficiency is forward of mid –first molar. More lateral interferences in occlusion. 10% greater bite force. Location of mandibular canal. Less dense bone. Submandibular fossa is greater. Less Interarch space for cement retention. 8. Less access to occlusal screws. 9. Hygiene is more difficult. 10. Cheek biting is more common. 11. Cross bite more often necessary. 12. More incision line opening post surgery. 13. Greater mandibular flexure. 14. Greater cost to patient. www.indiandentalacademy.com
  35. 35. Maxillary second molar implant is mostly indicated because. • Poor bone density in the region and need for added posterior support. • No risk of Paresthesia. • Implants do not extrude especially when they are splinted. www.indiandentalacademy.com
  36. 36. Missing teeth: number • Independent implant restorations not connected to teeth cause fewer complications and longer success. • The number of posterior pontics in fixed restoration should not extend beyond two, and even this condition is improved with independent implant supported restorations. • Non precious metals deform approximately 50% less than high noble alloys and therefore may be selected for long span restorations supported by teeth. www.indiandentalacademy.com
  37. 37. Lip line at rest and during speech. • Following lip positions are evaluated. – Resting lip line – Maxillary high lip line – Mandibular low lip line. • It is recommended to make the patient aware of these existing lip lines and impress upon them that these lip positions will be similar after treatment. www.indiandentalacademy.com
  38. 38. Resting lip line • Especially noted if maxillary anterior teeth are to be replaced. • The resting lip positions are highly variable,but in general are related to the patients age. • Older patients show fewer maxillary teeth at rest and during smiling but demonstrate more mandibular teeth during sibilant sounds. • Extending crown height in maxilla to decrease the age of smile may result into increased moment of forces. www.indiandentalacademy.com
  39. 39. Maxillary high lip line. • It is determined while the patient displays a natural, broad smile. • If patient has high lip position during smiling, the prosthodontic requirements are more demanding – Onlay grafts of HA may be indicated. – Addition of pink porcelain. www.indiandentalacademy.com
  40. 40. Mandibular low lip line. • It has to be observed during speech. • In pronunciation of the “ s” sounds, or sibilants, some patients may expose the entire anterior mandibular teeth and gingival contour. • Patients are often unaware of this preexisting lip position and blame the final restoration for the display of the mandibular gingiva, or complain that the teeth look too long. www.indiandentalacademy.com
  41. 41. Mandibular flexure. • The amplitude of the movement is 0.8 mm in molar area and 1.5 mm in ramus area. • As a consequence, complete cross-arch splinting of posterior molar rigid, fixated implants is usually contraindicated in the mandible • Options – Segment the restoration in 2 or more independent prostheses. – Non rigid connectors – Insert posterior implants only in one section. www.indiandentalacademy.com
  42. 42. Soft tissue support • Evaluation of soft tissue support is primarily needed in planning for overdenture prostheses. • Shape of the ridge. – Square: optimal resistance and stability. – Flat: compromised factor for retention and stability.support is adequate. – Tapering ridges: poor stability. www.indiandentalacademy.com
  43. 43. • Ridge parallelism – Rides parallel to occlusal plane : most favourable – Both ridges are divergent: stability of the denture will be affected. www.indiandentalacademy.com
  44. 44. Evaluation of natural teeth adjacent to implant site. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Abutment mobility Pier abutment Terminal splinted abutment. Crown size Crown-root ratio Endodontic status Root configuration Tooth position Parallelism Arch position caries Periodontal status. www.indiandentalacademy.com
  45. 45. Decision making protocol for a natural tooth abutment Prognosis >10 years 5 to 10 years Protocol Keep the tooth and restore as indicated. Make an independent implant restoration. If the natural tooth abutment must be included,make it a “living pontic” by adding more implants or splinting to additional teeth with copings and a retrievable prosthesis <5 years Extract the tooth and graft the site. Consider an implant in the site after healing. www.indiandentalacademy.com
  46. 46. Abutment mobility. • 1. 2. 3. 4. 4 important components may contribute movement to the implant –tooth rigid fixed prosthesis. The implant Bone Tooth The prosthesis and prosthetic component. www.indiandentalacademy.com
  47. 47. • • Tooth exhibits normal physiological movement in vertical horizontal and rotational directions. Amount of movement depends on 1. Roots 1. 2. 3. 4. 5. Surface area design Diameter Shape Position 2. Amount of surrounding bone. www.indiandentalacademy.com
  48. 48. Physiologic movement. Healthy posterior tooth Vertical direction Rigid implant Zero. Clinical 28 µm actual 2-3 µm Single pontic –6 under 10 Ib µm. force. Two pontic span 48 µm Under 25 Ib force. Horizontal Anterior 90-108 11-66 tooth µm labilingual mobility Zero clinical 8-140 in mesiodistal Posterior 56-75 direction µm www.indiandentalacademy.com Fixed prostheses
  49. 49. • There is extensive documentation that implants can be connected rigidly to stable teeth. • However occlusion should be modified so that implant does not bear the major portion of the load. www.indiandentalacademy.com
  50. 50. • Visual clinical evaluation by the human eye can detect movement above 90 µm. • When mobility of natural tooth can be observed,it is above 90 µm and too great to be compensated by the implant,bone,and prosthesis movement. • criterion for joining an implant to natural teeth – is that there be no observable clinical mobility of the natural abutment. – No lateral forces should be designed on the implant. www.indiandentalacademy.com
  51. 51. • Implants should rarely be connected to anterior teeth because – Anterior teeth often exhibit greater clinical mobility than the implant can tolerate. – Lateral forces applied to the restoration during mandibular excursions will be transmitted to the abutments,implants included. • When natural abutments show clinical mobility two options are available. – Place additional implants and avoid inclusion of natural abutment. – Splinting of additional natural abutment to improve stress distribution and obtain 0 clinical mobility. www.indiandentalacademy.com
  52. 52. Pier abutment. • When an implant serves as a pier abutment between two natural teeth,the differences in movement between implant and tooth may be magnified. • Implant act as fulcrum of class I lever. • Leads to uncemented abutment and subsequent decay. www.indiandentalacademy.com
  53. 53. • To prevent the implant pier abutment from acting as a fulcrum, a non rigid attachment may connect the implant and the least retentive crown or most mobile tooth. • An implant does not undergo mesial movement during function,so the nonrigid connector location can be more variable. www.indiandentalacademy.com
  54. 54. • When natural abutment is the pier abutment between two implants, a stress breaker is rarely indicated. • The tooth may then act as living pontic,contributing less to the support, provided the number of pontics is limited and the implants are of sufficient dimension. www.indiandentalacademy.com
  55. 55. Crown size. • The retention of a crown is influenced by the diameter and height of the abutment. • Crown height may be affected when Interarch space is limited. • Management of decrease d crown size. – Splinting –improves retention but compromises access for hygiene in the interproximal areas. – Crown lengthening – Minimal tapering – Retentive elements such as grooves or boxes. www.indiandentalacademy.com
  56. 56. Crown-root ratio. • The crown root ratio represents the height of the crown from the most incisal or occlusal position to the crest of the alveolar ridge around the tooth compared with the height of the root within the bone. • Is important when lateral forces are expected against the crown,as in mandibular excursions. • The lateral forces develop a class I lever condition on the tooth with fulcrum at the crest of the bone. • Splinting may be indicated for better stress distribution. www.indiandentalacademy.com
  57. 57. • Found rarely but most ideal crown root ratio for a fixed prosthetic abutment is 1:2. • Common condition 1: 1.5 • Minimum requirement. 1:1. • Crown to root ratio when opposing natural teeth or implants and when serving as an abutment for an implant tooth prosthesis. www.indiandentalacademy.com
  58. 58. Endodontic status. • A natural abutment included in a combination of tooth and implant supported prosthesis should present a satisfactory pulpal condition or a root canal obturation. • Exacerbation of Endodontic lesion after implant surgery may result in adjacent implant failure. • Some anterior teeth show wide incisal edges and narrow cervical portions,especially if recession of the gingiva has occurred. • Pulpal exposure of the lateral horns are common when preparing www.indiandentalacademy.com crowns such teeth for full
  59. 59. • Past periodontally involved teeth are more at risk of pulpal disease after tooth preparation. • Apicoectomy procedures ,when indicated ,are best performed without use of amalgam retrograde filling to avoid corrosion byproducts in the area, which may contaminate metal implants. www.indiandentalacademy.com
  60. 60. Root configuration. • Root configuration of a natural abutment may affect the amount of additional stress the tooth may withstand without potential complications. • Favorable root configuration – Dilacerations – Curvatures of root. • Unfavorable root configuration. – – – – Tapered Fused roots Blunted apices. www.indiandentalacademy.com Maxillary second molar often presents varied root configuration
  61. 61. • Any adjacent natural tooth with curved roots at the apex must be carefully evaluated before implant placement. • Maxillary canine is often tilted 11 degrees and exhibits a distal curvature to its roots. • An implant placed in the premolar region may inadvertently placed into the canine root apex when the topography of the area is not appreciated. www.indiandentalacademy.com
  62. 62. • Roots with circular cross-section do not represent as good a prosthodontic abutment as those with an ovoid cross section. • Therefore maxillary premolar is a better abutment than the maxillary central incisor,although their root surface areas are similar. • Maxillary lateral incisor exhibit les lateral mobility than central incisor,as a result of its cross-sectional anatomy. www.indiandentalacademy.com
  63. 63. Tooth position. • When adjacent teeth have been missing for a long time ,the remaining natural abutment has often drifted form its ideal position • Tipping • Tilting • Rotation • Extrusion. www.indiandentalacademy.com
  64. 64. • Correction of natural abutment should be considered. – Crown preparation – Endodontic therapy before restoration – Orthodontic movement. • Orthodontic treatment can be planned in conjunction with the healing phase for rigid fixated implants. www.indiandentalacademy.com
  65. 65. Parallelism. • Splinting incisor teeth is more common in implant dentistry than traditional prosthodontics. • Joining nonparallel teeth or splinting anterior and posterior teeth in same prosthesis may be required. • Several abutments may need Endodontic therapy to achieve this goal. • Selective extraction of incisors may even be indicated if rotations or overlapping of teeth represent unrealistic conditions for oral hygiene after restoration. www.indiandentalacademy.com
  66. 66. • Indications for knife edged margin preparation for a crown, – Interproximal areas of incisors,so pulp horns are not encroached upon – Onside of tooth tipped more than 15 degrees • Apply when splinting anterior teeth or nonparallel abutments. – On an implant post much smaller than the emergence profile of its crown – In the furcation region of multirooted teeth. www.indiandentalacademy.com
  67. 67. Root surface area. • Greater the root surface area of proposed abutment tooth ,the greater the support. • Teeth affected by periodontal disease lose surface area and represent poorer support elements for a prosthesis. • For a maxillary first molar, bone loss to the beginning of the root furcation corresponds to a root surface area reduced by 30%. www.indiandentalacademy.com
  68. 68. • Ante’s law requires the root surface area of the abutment teeth to be equal to or greater tan that of the teeth replaced by the pontics of the fixed restoration. • Although originally presented without research or documentation,it has withstood the test of time and serves as a clinical guideline. www.indiandentalacademy.com
  69. 69. Caries. • All carious lesions should be eliminated before implant placement,even when the teeth will be restored with crowns after implant healing for the final prosthesis. • As implants most often require several months of healing after initial placement,the progression of decay may alter the final treatment plan and loss f desired abutment. • If Endodontic therapy becomes indicated ,obturation of the canals ideally should be completed before implant surgery. www.indiandentalacademy.com
  70. 70. Periodontal status. • The periodontal evaluation of natural abutments to be connected to implants is identical to evaluation of other fixed partial denture abutments. • Adjacent implant sit e may be contaminated by bacteria during periodontal surgery. • Implant surgeon should decide if periodontal therapy is indicated on the abutment teeth at the same time as implant placement. • Active infection should be kept to a minimum during implant placement. • If conditions of increased risk are present,tetracycline is administered before implant surgery to decrease the sulcular flora,which may contaminate the implant site. www.indiandentalacademy.com
  71. 71. Divisions of available bone • Classification of available bone follows the natural patterns of bone resorption in the jaws. • Each division presents unique surgical and prosthetic approaches. www.indiandentalacademy.com
  72. 72. Misch and Judy (1985) Mandible : by Atwood. Maxilla by fallschussel www.indiandentalacademy.com
  73. 73. other bone classifications. • Cawood and Howell. • Weiss and Judy 1974 classification of mandibular atrophy and its influence on subperiosteal implant therapy. • Louisiana state university and Kent (1982) classification of alveolar ridge deficiency designed for Alloplastic bone augmentation. • Zarb and lekholm (1985) residual jaw morphology with the insertion of Branemark fixtures. www.indiandentalacademy.com
  74. 74. Available bone • Available bone describes the amount of bone in the edentulous area considered for implantation. • It is measured in height length angulation and crown –implant body ratio. www.indiandentalacademy.com
  75. 75. www.indiandentalacademy.com
  76. 76. Available bone height. • The minimum height of available bone for endoosteal implants is in part related to the density of bone. • The minimum bone height for predictable long term Endoosteal implant survival approaches 10mm. www.indiandentalacademy.com
  77. 77. • Height of available bone is measured from the crest of the edentulous ridge to the opposing landmark. Which may be A. B. C. D. E. F. G. Maxillary canine region Floor of the nares Maxillary sinus Tuberosity Mandibular canine region Anterior mandible Bone above the inferiorwww.indiandentalacademy.com mandibular canal
  78. 78. Available bone width. • It is measured between the facial and lingual plates at the crest of the potential implant site. • Root form implants of 4.0 mm crestal diameter usually require more then 5.o mm of bone to ensure sufficient bone thickness and blood supply around the implant for predictable survival. www.indiandentalacademy.com
  79. 79. Available bone length. • The mesiodistal length of avialble bone in an edentulous area is often limited by adjacent teeth or implants. • For a bone more tan 5 mm wide, a minimum mesiodistal length of 7 mm is usually sufficient for each implant. • For bone less than 5 mm requires a 3.2 mm implant with compromises such as less surface area and greater crestal concentration of stress. www.indiandentalacademy.com
  80. 80. Available bone angulation. • Ideally it is aligned with the forces of occlusion and is parallel to the long axis of the prosthodontic restoration. • The alveolar one angulation represents the root trajectory in relation to the occlusal plane. • Rarely does this bone angulation remain constant after the loss of teeth. www.indiandentalacademy.com
  81. 81. • Maxillary anterior region – Maxillary anterior teeth are angled more to occlusal forces than any other teeth. – Labial undercuts and resorption after tooth loss mandate greater angulation of the implants. • Posterior mandibular region. – Submandibular fossa mandates implant placement with increasing angulation as they progress distally. – Second premolar region –10 degrees – First molar region –15 degrees – Second molar region –20-25 degrees. www.indiandentalacademy.com
  82. 82. • In edentulous areas with a wide ridge, – wider root form implants may be selected. – Decreases the amount of stress transmitted to the crestal bone. – Such implants allow modifications up to 30 degrees divergence. • Narrow yet adequate width ridge. – Requires narrower design root form implant. – Smaller diameter designs cause greater crestal stress and may not offer the same range of custom abutments. – The limits of the acceptable angulation of bone in narrow ridge to 20 degrees from the axis of the adjacent clinical crowns or a line perpendicular to the occlusal forces. www.indiandentalacademy.com
  83. 83. Crown –implant body ratio. • The crown –implant body ratio impacts the appearance of the final prosthesis and the amount of moment of force on the implant and surrounding crestal bone. • The greater the crown height,the greater the moment force or lever arm with any lateral force. • As the crown-implant ratio increases,the number of implants and/or wider implants should be inserted to counteract the increase in stress. www.indiandentalacademy.com
  84. 84. Divisions of available bone. www.indiandentalacademy.com
  85. 85. Division A(abundant bone) www.indiandentalacademy.com
  86. 86. Division B (Barely sufficient Bone) www.indiandentalacademy.com
  87. 87. • Division B ridge may be converted to division A by augmentation or Osteoplasty. • the augmentation requires 4 to 6 months but can result in improved crown – implant ratio and more natural looking abutments. • Implants may be placed at the same time as Osteoplasty,but the crownimplant ratio is increased. www.indiandentalacademy.com
  88. 88. Division C (compromised bone) www.indiandentalacademy.com
  89. 89. Division D (Deficient bone) www.indiandentalacademy.com
  90. 90. www.indiandentalacademy.com
  91. 91. Bone density. • Linkow (1970) • Class I bone structure – The ideal bone type consists of evenly spaced trabeculae with small cancellated spaces. – Very satisfactory foundation for implant prosthesis. • Class II bone structure – The bone has slightly larger cancellated spaces with less uniformity of the osseous pattern. – Satisfactory for implants • Class III bone structure. – Large marrow filled spaces exist between bone trabeculae. – Results into loose fitting implants. www.indiandentalacademy.com
  92. 92. • Lekholm and zarb(1985) • Quality 1 – Homogeneous compact bone • Quality 2 – Thick layer of compact bone surrounding a core of dense trabecular bone. • Quality 3 – Thin layer of cortical bone surrounding dense trabecular bone of favorable strength. • Quality 4 – Thin layer of cortical bone surrounding a core of low density trabecular bone. www.indiandentalacademy.com
  93. 93. Misch bone density classification • D1 dense cortical bone • D2 thick dense to porous cortical bone on crest and coarse trabecular bone within. • D3 thin porous cortical bone on crest and fine trabecular bone within. • D4 fine trabecular bone • D5 immature, nonmineralized bone. www.indiandentalacademy.com
  94. 94. www.indiandentalacademy.com
  95. 95. Factors of stress • Normal forces exerted on teeth. • Bite forces – – – – – Perpendicular to occlusal plane Short duration Brief total period (9 min/day) Force on each tooth : 20 to 30 psi Maximum bite force: 50 to 500 psi • Peri oral forces. – – – – – More constant Lighter Horizontal Maximum when swallowing (3 to 5 Psi ) Brief total swallow time (20 min/day) www.indiandentalacademy.com
  96. 96. • 1. 2. 3. 4. 5. 6. Dental factors that affect stress primarily include. Parafunction The position of the abutment in the arch Masticatory dynamics The nature of the opposing arch The direction of load forces The crown –implant ratio. www.indiandentalacademy.com
  97. 97. Parafunction. • The most common cause of early loss of rigid fixation during the first year of implant loading is the result of Parafunction. • Such complications occur with greater frequency in the maxilla because of a decrease in bone density and an increase in the moment of force. • Parafunction may be categorized as absent,mild moderate or severe. www.indiandentalacademy.com
  98. 98. bruxism • It is the vertical and horizontal ,or nonfunctional grinding of teeth. • Bruxism does not necessarily represent a contraindication for implants but it dramatically influences the treatment plan. • Best way to diagnose is the to evaluate the wearing of teeth. www.indiandentalacademy.com
  99. 99. Clenching • It is the force exerted from one occlusal surface to the other without any movement. • The forces are directed more vertically to the plane of occlusion,at least in the posterior regions of the mouth. • Wearing of the teeth is not likely. • Common clinical finding is the scalloped border of the tongue. www.indiandentalacademy.com
  100. 100. Tongue trust and size. • Parafuctional tongue thrust is the unnatural force of the tongue against the teeth during swallowing. www.indiandentalacademy.com
  101. 101. Position of abutment within the arch. • Biting force is greater in molar region and decreases as it progresses anteriorly. www.indiandentalacademy.com
  102. 102. Masticatory dynamics • Masticatory muscle dynamics are responsible for the amount of force exerted on the implant system. • Forces recorded in woman are 20 lb less than those in men. • Younger patients need additional implant support for the prosthesis for the longer time. www.indiandentalacademy.com
  103. 103. Opposing arch • Natural teeth transmit greater impact forces through occlusal contacts than do soft tissue borne complete dentures. • Partial denture patients may record forces which are intermediate between that of natural teeth ad complete dentures and depends on the location and condition of the remaining teeth,muscles ,and joints. www.indiandentalacademy.com
  104. 104. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com