PERIO CONSIDERATIONS IN prosthodontics ppt

PERIO CONSIDERATIONS IN prosthodontics

1. Periodontal considerations in FPD Guided by –Dr. Ajaykumar Nayak Professor Presented by – Dr. Shilpa Soman (II MDS)

2. CONTENTS Introduction Biological width Periodontal factors in FPD / abutment selection. -Crown root ratio -PDL area and surface area -Root configuration -Tilt -Mobility -Furcation involvement -Resection -Hemisection Margin placement Gingival retraction Margin placement Gingival retraction Pontic design. Crown contours

3. Dentists face special problems in patients with history of periodontitis requiring crowns or FPD’s to restore carious or missing teeth. These problems include poor crown-root ratio, esthetic compromise, furcation invasion, progressive tooth mobility, migration, inadequate zone of attached gingiva and prominent root concavities. For prosthodontics, periodontal health plays an important role on the longevity of restorations. On the other hand, defective prostheses may contribute to progression of periodontal diseases INTRODUCTION

4. Importance of Preparation of the Periodontium for Restorative Dentistry Gingiva shrinks after periodontal treatment. The position of teeth is frequently altered in periodontal disease. Resolution of inflammation after treatment causes the teeth to move again, often back to their original position. Restorations designed for teeth before the periodontium is treated, may produce injurious tensions and pressures on the treated periodontium. Inflammation of the periodontium impairs the capacity of abutment teeth. Discomfort from tooth mobility interferes with mastication and function. It is easy to obtain accurate impressions and make precise preparations on healthy gingiva than inflamed one. To minimize the risk of trauma to the gingival tissues during preparation and impression procedures

5. BIOLOGICAL WIDTH – Sicher - “ dentogingival junction” 1961,Gargiulo et al - vertical dimension of the dentogingival junction comprising sulcus depth (SD), junctional epithelium (JE), and connective tissue attachment (CTA), is a physiologically formed and stable dimension, subsequently called ‘‘Biologic Width’. Average combined width of connective tissue Attachment + junctional epithelium = 2.04mm (biologic width)

6. Categories/ profiles of biological width Three categories of biological width based on total dimension of attachment and sulcus depth following bone sounding measurements. The measurements are made on anterior teeth mid-facially and at the facial/interproximal line angles - Normal crest High crest Low crest

7. NORMAL CREST HIGH CREST LOW CREST Midfacial measurement 3mm <3mm >3mm Proximal measurement 3mm – 4.5mm less than 3mm >4.5mm Occurrence 85% of the time 2% 13% Clinical considerations Margin of crown not to be placed closer than 2.5mm from crest Not possible to place a intracrevicular or subgingival margin Most susceptible to recession with placement of crown intracrevicular. An intracrevicular margin can be placed with a reasonable expectation of long-term stability and esthetics.

8. EVALUATION OF BIOLOGICAL WIDTH VIOLATION. If a patient experiences discomfort when the restoration margin levels are being assessed with a periodontal probe. Margin has extended into the attachment and biological width violation has occurred. Bone sounding / Transgingival probing Biological width can be identified by probing under local anesthesia and subtracting the sulcus depth from surrounding measurements. If this distance is <2mm at one or more locations, a diagnosis of biological width violation can be confirmed. RADIOGRAPHIC EVALUATION Identifies interproximal violation of biological width Parallel profile radiographic technique

9. Signs of biologic width violation – Chronic progressive gingival inflammation around restoration Bleeding on probing Localised gingival hyperplasia with minimal bone loss Gingival recession Pocket formation Clinical attachment loss Alveolar bone loss.

10. Two responses of the gingival tissue – Bone loss Gingival inflammation and recession CORRECTION OF BIOLOGICAL WIDTH VIOLATION – Surgically removing crestal bone away from the restoration margin can be achieved by crown lengthening , gingivoplasty , gingivectomy, apical repositioned flap with bone contouring.

11. MARGIN PLACEMENT Supragingival margin placement - Above the marginal gingiva Equigingival margin placement - At the crest of marginal gingiva Intracrevicular margin placement (subgingival margin) - Below marginal gingiva

12. Supragingival Equigingival Subgingival Least impact on the periodontium More plaque accumulation than supragingival or sub gingival margin resulting in gingival inflammation More quantitative and qualitative changes in the microflora. Indication Non- esthetic areas due to the marked constrast in color &opacity of traditional restorative materials against the tooth. Restorative margins can be aesthetically blended with the tooth &finished to provide a smooth, polished interface at the gingival margin esthetic demands, root caries or fracture, clinically short crowns

13. subgingival restorations were associated with greater periodontal inflammation in the sites with keratinized gingiva less than 2mm .

14. INTRACREVICULAR MARGIN Clinical situations in periodontally treated teeth requiring these margins are: Esthetics Severe cervical erosion, restorations, caries extending beyond gingival crest Short clinical crowns or broken down crowns Elimination of persistent root hypersensitivity. WOUND HEALING CONSIDERATIONS- Time elapsed after completion of periodontal treatment is crucial for placement of intra crevicular margins. 3 months for healing of extensive surgery or more time required. Margins after periodontal surgery - coronally; scaling and after root planing - recedes

15. Carranza gave three rules have been suggested for the placement of subgingival restoration margin. To implement following rules it must be made sure that the gingival tissue is healthy: RULE 1- If the sulcus probing depth is 1.5mm or less than that, the gingival margin is placed 0.5mm below the gingival tissue crest. RULE 2- If sulcus probing depth is >1.5mm,the margin of restoration is placed one half of the depth of the sulcus below the gingival tissue crest. RULE 3- If the sulcus depth is >2mm, the gingival tissue is evaluated for going gingivectomy and for crown lengthening. Once the gingival sulcus depth around 1.5mm is achieved, the restoration margin Is placed following rule 1.

16. Healthy crevice depth 2-3mm, so margin placement 0.5-2mm from gingival crest. Histologic depth 0.5-1mm 0.5mm ideal depth for intracrevicular margins, specially when adjacent to root surface. Average cervical depth in enamel and root is similar, while crevicular length of junctional epithelium is 0.5-1mm shorter on root than on enamel. Thus overextension of margin placement beneath the gingiva on root surfaces impinges on the gingival connective tissue fibres and the junctional epithelium Chamfer or knife edge margins are indicated in cases where gingival margins have receded to root levels .

17. The chosen finish line design must have – a predictable degree of marginal honesty. Place smooth materials in the sulcus to prevent plaque buildup Maintain a pleasing appearance. conservative finish lines such as the feather edge and knife edge result in overcontoured restorations, which cause periodontal problems such as gingival recession, unattractive black triangular holes, and alveolar bone loss.

18. Different studies have demonstrated conclusively that periodontal tissues show more signs of inflammation around crowns with intracrevicular or subgingival margins than those with supragingival margins. Orkin et al demonstrated that subgingival restorations had a greater chance of bleeding and exhibiting gingival recession than supragingival restorations. Flores-de-Jacoby et al studied the effects of crown margin location on periodontal health and bacterial morphotypes in human 6-8 weeks and 1 year postinsertion. Subgingival margins demonstrated increased plaque, gingival index score and probing depths. Furthermore, more spirochetes, fusiform, rods and filamentous bacteria were found to be associated with subgingival margins. Silnes s evaluated the periodontal condition of the lingual surfaces of 385 fixed partial denture abutment teeth. He found that a supragingival position of the crown margin was the most favorable, whereas margins below the gingival margin significantly compromised gingival health.

19. PERIODONTAL FACTORS IN ABUTMENT SELECTION

20. CROWN – ROOT RATIO – Length of tooth occlusal to the alveolar crest of bone compared with length of root embedded in bone. As the level of alveolar bone moves apically, the lever arm of that portion out of bone increases, and the chance for harmful lateral forces is increased. The optimum crown root ratio for tooth to be utilized as a fixed partial denture abutment is 2:3. A ratio of 1:1 is the minimum ratio that is acceptable for a prospective abutment under normal conditions (such as number of teeth being replaced, tooth mobility and overall periodontal health is good) However there are situations where a crown –root ratio of greater than 1:1 might be considered adequate.

21. PDL AREA AND SURFACE AREA – ANTE suggested in 1926 that it was unwise to provide a FPD when the root surface area of the abutment was less than the root surface area of the teeth being replaced; this has been adopted and reinforced by other authors (Johnston, Dykema, Shillinburg , Tylman ) as ANTE’s LAW. Ante’s Law – “ T he total periodontal membrane area of the abutment teeth must equal or exceed that of the teeth to be replaced." Newman and Ericsson - demonstrating that teeth with considerably reduced bone support can be successfully used as FPD abutments. “The total mesiodistal width of the cusps of abutments should be equal or exceed the width of cusps of pontics.”

22. ROOT CONFIGURATION – Roots broader labiolingually preferred. Multirooted posterior teeth with widely separated roots will offer better periodontal support than roots that are short converge, fuse, blunted, or generally present a conical configuration. A single rooted tooth with evidence of irregular configuration or with some curvature in the apical third of the root is preferable to the tooth that has a nearly perfect taper.

23. Long axis Relationship - The long axis relationship of abutment teeth should be no more than 25- 30 degree from the parallel. A severely inclined tooth will not withstand forces as well as one that is erect. MESIALLY TILTED MOLARS - encountered when a mandibular first molar is to be replaced after the second and third molars have drifted and tilted mesially and lingually. AItered path of insertion. The mesial one- half crown preparation, the non - rigid attachment (semi- precision or stress breaker) and the telescopic prosthesis have been suggested to solution to the problem.

24. Mobility Abutments with greater than normal mobility are frequently capable of with standing force and are suitable as abutments. A Miller mobility value of one is generally acceptable, whereas a mobility value of two require assessment. If the mobility is related to deflective occlusal contacts, that can be eliminated and if short span prosthesis is involved, the tooth is likely to be a suitable abutment. If mobility is caused by considerable bone loss and more than one tooth is to be replaced, it is unlikely the tooth to be a suitable abutment unless it can be splinted to another sound tooth.

25. Splinting – in dentistry the joining of two or more teeth into a rigid unit by means of fixed or removable restorations or devices (GPT-9) Splints – a rigid or flexible device that maintains in position a displaced or movable part; also used to keep in place and protect an injured part. (GPT-9). A periodontal splint is an appliance used for maintaining or stabilising mobile teeth in their functional position. Mobile tooth/ teeth is splinted to adjacent healthy teeth and act as a unit and redirects the masticatory forces to the whole unit . Also augments crown root ratio and a net decrease of force on individual teeth. Types – Temporary splints / Provisional splints Permanent splints

26. Furcation flutes Sometimes the crown margins on a molar must extend far enough apically that the preparation finish line approaches the furcation, where the common root trunk divides into two or three roots. The designs of both the tooth preparations and the crowns for these teeth must be different from those customarily used. caused by the intersection of the preparation finish line with the vertical flutes or concavities in the common root trunk, extending from the actual furcation in the direction of the cementoenamel junction. The axial contours of crowns placed on teeth whose furcation flutes are intercepted by preparation finish lines must likewise reflect the concavity rising from the furcation flute. The facial surface should be invaginated into a concavity above the bifurcation that extends occlusally until it meets the facial groove in the occlusal one-third of the facial surface. There must be no interruption in the vertical concavity rising at the margin of the restoration .

27. Preparations for Root Resections Root amputation is removal of a root without disturbing the crown. A hemisection is a procedure in which the tooth is separated through the crown and the furcation producing two essentially equal-sized teeth. One or more roots of a molar may be removed to eradicate areas of the tooth that create problems in the maintenance of good hygiene and plaque control. One or more roots can be eliminated because of an invasion or uncovering of the furcation by severe vertical bone loss. The severe loss of bone or attachment around one root may also necessitate the removal of a root .

28. When a root has been removed from a tooth, both the tooth preparation and the contours of the crown will be different because of the altered tooth shape. Maxillary distofacial root The proximal contact is restored to its normal faciolingual size. In the finished restoration, it is important that the contours of the distofacial cusp apical to the contact area have a definite concave shape. This ensures that crown contours will be aligned with the root configuration in that critical area, preventing impingement on the gingiva

29. Maxillary mesiofacial root Loss of the mesiofacial root represents a greater loss of support for the remaining tooth than does the loss of the distofacial root. The mesiofacial root accounts for 25% to 36% of the first molar root area, depending on the amount of loss of bone around the root trunk. Resulting occlusal outline tends to be more triangular in configuration finish line will extend apically past the pulp chamber, but it will not include all of the area where the mesiofacial root was removed. There will be a concavity gingivofacial to the proximal contact on the mesial surface of the crown.

30. Maxillary palatal root In those situations where the palatal root has been removed from a maxillary molar, the palatal surface of the preparation will be flat, reflecting the general configuration of the remaining root stump. The preparation and resulting restoration usually will have a distinct concave flute on the facial surface arising from the facial bifurcation. Essentially there will be no palatal cusp. The presence of palatal cusps would produce an area inaccessible to hygiene maintenance in the palatogingival segment of the crown. It would also create a severe torquing moment on the tooth, which could either tip the tooth palatally or fracture the tooth preparation under the crown.

31. CROWN PREPARATION Whenever possible margins should be placed supragingivally. Intracrevicular margin placement may be required to cover portions of the root resected area. Crown margin should be apical to pulp chamber floor or root canal that was exposed by resection, especially if these structures have not been sealed by amalgam. To prevent impingement of biologic width; intracrevicular margins to cover the pulpal canal structures should be no close than 3mm to the alveolar crest. Gingival third is fabricated with flat emergence profile from gingiva for hygiene and cleansing. Open embrasures between crowns and apical to rigid connectors allow proximal cleansing with interdental brushes

32. MANDIBULAR HEMISECTION When separating the roots of mandibular molars. Frequently one root is removed while the other remains. The distal root could be used as an abutment for a short-span fixed partial denture replacing the mesial root . Occasionally the one root may be used as the distal abutment for a longer-span fixed partial denture replacing an entire molar.

33. SKY FURCATION Occasionally it may be desirable to separate the roots of a maxillary molar without removing a root. This is possible only if the roots are long, well supported by bone, and distinctly separate. The roots are cut apart and then rejoined by a “crown” that in reality is a very short interradicular splint with concave connectors from one root to the other. The occlusal configuration of the splint is pretty much that of an ordinary molar. This procedure, in effect, makes the furcation metal and moves it occlusally while separating the roots. This improves access to the furcation and protects a caries-prone area .

34. The contours for full and partial coverage restorations play a supportive role in establishing a favorable periodontal climate. Three prominent theories of crown contour have evolved: (1)Gingival protection, (2) Muscle actions, and (3)Access for oral hygiene. 1- Gingival protection theory – advocates that contours of cast restorations be designed to protect the marginal gingiva from mechanical injury . Protection of gingival margins . This concept implies that under contouring of the clinical crown will cause deflection of masticated food onto the gingival margin, forcing it into the sulcus, thus initiating gingivitis.

35. Gingival stimulation . This concept reasons that, as food is masticated, it will pass over the gingiva, stimulating it and causing increased keratinization of the epithelium. The keratinized epithelium would be more resistant to periodontal breakdown. Self-cleansing contours . This concept asserts that, as food passes over the tooth during mastication, the tooth will be cleansed. While certain prominent buccal and lingual surfaces of teeth do not accumulate plaque even in neglected mouths ,

36. Thus, the critical areas which must be appropriate to maintain the health and position of the gingival tissues are marginal fit, contour and surface finish. Poorly adapted margins, over-contoured or under-contoured restoration, and rough or porous surface can cause: Inflammation, gingival recession or overgrowth. Open margins can provide shelter for micro-organisms and may be responsible for inflammatory response. When creating crown contours: 1. Buccal and lingual contours should be ‘‘flat, not fat’’; 2. Embrasures should be kept open; 3. The location of contact areas should be oriented toward the incisal and the buccal aspects of the restored tooth. 4.The crown margins over furcation areas in molars and premolars should be fluted or barreled out.

37. 2-Muscle action theory Lindhe and Wicen - stated in absence of oral hygiene , “self cleansing mechanisms do nothing to prevent gingivitis. Even if there was some self cleansing of the buccal and lingual surfaces from muscle action, interproximal cleansing wuld still not occur. These authors strive for an intermediate design of crown contour which allows for both gingival protection and muscular action. 3-Theory of access for oral hygiene based on the concept that plaque is the prime etiologic factor in caries and gingivitis. four guidelines to contouring crowns with emphasis on access for oral hygiene – Buccal and lingual contours-flat, not fat! Reduction or elimination of the infrabulge Under contouring may promote gingival health – Perel a normal tooth at the bucco cervical bulge is usually ≤ 0.5 mm wider than the CEJ.

38. Open embrasures - open embrasure spaces will allow for easy access into interproximal areas. overcontoured embrasure will reduce the space intended for the gingival papilla. The result is a broadening of the co1 area, causing pressure and irritation on the papilla. This also inhibits effective oral hygiene. Interdental brushes Location of contact areas . Contacts should be high and buccal in relation to central fossa. contact area of all teeth, except between the maxillary first and second molars, should be buccal to the central fossa. creates a large lingual embrasure for optimum health of the lingual papilla. Ramfjord recommends placement of contact areas as far occlusally as possible to facilitate access for interproximal plaque control.

39. Furcations involvement . Furcations that have been exposed owing to loss of periodontal attachment should be “fluted” or “barreled out”. eliminates “plaque traps” and facilitate plaque control.‘

40. PULPAL INVOLVEMENT Chamfer or knife edge margins are indicated in cases where gingival margins have receded to root levels in posterior regions. If a shoulder is prepared for a metal ceramic crown axial walls converge towards pulp chamber with serious consequences : even if axial walls are parallel. Intentional vital root canal therapy is indicated before crown completion. Endodontically treated teeth have a good prognosis in periodontal prosthesis.

41. Occlusal patterns in periodontal therapy Indications for group functions : If existing occlusion is in group function and there is no TMJ or muscular dysfunction or tooth mobility, group function relation is acceptable. If a cuspid is periodontally weakened or presents mobility on lateral excursive contacts, a group function is indicated. Even if a cuspid is periodontally compromised, it should still be adjusted to remain in contact during group function.

42. Indications for mutually protected occlusion : Anterior teeth should be periodontally healthy. In case of anterior bone loss or missing canines, mouth should be restored to group function.

43. PONTIC DESIGN Based on tissue contact two types- Mucosal contact – ridge lap pontics - modified ridge lap pontic - ovate pontic - conical pontic Non mucosal contact – sanitary pontic - modified sanitary pontic FUNCTION S - restore function, provide esthetics and comfort, be biologically acceptable, permit effective oral hygiene, and preserve underlying residual mucosa

44. The sanitary and ovate pontics have convex undersurfaces that facilitate cleaning. The ridge lap and modified ridge lap designs have concave surfaces that are more difficult to access with dental floss. A modified ridge lap design can be given where there is inadequate ridge to place an ovate pontic. Whereas the facial aspect of the undersurface has a concave shape, adequate access for oral hygiene is allowed by the more open lingual form. The modified ridge-lap design in the posterior region and the ridge-lap facing design in the anterior region. Sanitary / hygienic pontic

45. GINGIVAL RETRACTION All retraction methods induce transient trauma to junctional epithelium and connective tissue of gingival sulcus. Retraction cord: provides limited gingival recession; if pressed deep can cause reactions. 2. chemicals used for the treatment of chords include: 0.1% and 8% recemic epinephrine 100% aluminum solution (potassium aluminum sulfate) 5% and 25% aluminum chloride solution Ferric subsulfate ( Monsel’s solution) 13.3% ferric sulfate solution 8% and 40% zinc chloride solution 20% and 100% tannic acid solution

46. Ruel and coworkers reported that gingival displacement methods may cause 0.1-0.2 mm gingival recession and the destruction of the junctional epithelium that took 8 days to heal. Chemical agents as well as the mechanical force of retraction cords could trigger temporary gingival recession and gingival inflammation. The proper manipulation of different gingival retraction techniques such as materials and time-control are the key factors to avoid permanent tissue damage while impression-taking process is made. Kaiser and Newell stated – margins not to be placed over 1.0mm subgingivally to the retracted level of the free gingival margin to ensure that the margin is hidden under healthy tissue. Emphasised potential for tissue recession is greatly dependant on its health before preparation. Best way to avoid irritation is to extend gingival margin into the sulcus after cord retraction.

47. Retraction cord – The retraction cord technique produces limited gingival recession and can protect sulcular tissues during preparation. If inadequate attached gingiva , injury to gingival fibres occurs. Forces impression material to be forced into gingival connective tissue and bone, producing a foreign body reaction. Periodontal abcess or diffuse cellulitis. Radiographs – diagnosis. Extensive damage when pressured into marrow spaces

48. For a Rule 1 margin (sulcus depth 1.5 mm or less), the cord should be placed so that the top of the cord is located in the sulcus at the level in which the final margin is to be established, which will be 0.5 mm below the previously prepared margin.

49. For Rule 2 situations in which the sulcus is deeper, two larger-diameter cords are used to deflect the tissue before extending the margin apically

50. CROWN CONTOURS Two general types of gingival forms. -Scalloped thin Flat –thick If intracrevicular margins are adjacent to thin gingiva on the root, sulcular contours of the artificial crown should be flat mimicking shape of the root , to prevent overcontouring. If thick free gingiva is present against a flat root it often presents with a slight , chronic, marginal gingivitis . Advisable to create thicker intracrevicular crown contour similar to natural crown.

51. PROXIMAL CONTOURS Inter dental site is frequently the first site for gingivitis and periodontitis. Instead of single interdental papilla, interdental gingiva has separate facial and lingual peaks with connecting valley under contact area called Col (thin, nonkeratinized permeable to toxins). Embrasures: Common error – over contouring proximally (intracravicularly) due to deficient tooth reduction in an attempt to prevent pulpal damage. Therefore in minimal embrasure space, selective extraction or orthodontic correction or both can be considered.

52. Interdental cleaning aids like dental floss and interdental brushes should be easy to use in embrasure areas. Floss is incapable of removing plaque in concave proximal surfaces. So artificial crown contour and solder joins are created to accommodate passage for this device. Interdental brush is ineffective if its fit is lose in large embrasure, therefore proximal over contouring is indicated for snug fit of the brush These problems should be identified after periodontal therapy and before tooth preparation.

53. All phases of clinical dentistry are intimately related to a common objective: The preservation and maintenance of the natural dentition in health. In an integrated multidisciplinary approach to dental care, it is logical that periodontal treatment precede final restorative procedures. For restorations to survive long-term, the periodontium must remain healthy so that the teeth are maintained. For the periodontium to remain healthy, restorations must be critically managed in several areas so that they are in harmony with their surrounding periodontal tissues. The integration of periodontal considerations with restorative planning is now the standard of care. Direct and frequent communication between the periodontist and restorative dentist is a prerequisite for predictable and satisfactory results SUMMARY

54. REFERECES Malone WF, Tylman SD, Koth DL. Tylman's theory and practice of fixed prosthodontics. Ishiyaku EuroAmerica , Incorporated; 1989. Shillingburg HT, Hobo S, Whitsett LD, Jacobi R, Brackett SE. Fundamentals of fixed prosthodontics. Quintessence Publishing Company; 1997 Jan. Sood S, Gupta S. Periodontal-restorative interactions: A review. Indian Journal of Multidisciplinary Dentistry. 2011 May 1;1(4). Hsu YT, Huang NC, Wang HL. Relationship between periodontics and prosthodontics: The two-way street. Journal of Prosthodontics and Implantology. 2015;4(1):4-11.

55. Becker CM, Kaldahl WB. Current theories of crown contour, margin placement, and pontic design. The Journal of prosthetic dentistry. 1981 Mar 1;45(3):268-77. Shenoy A, Shenoy N, Babannavar R. Periodontal considerations determining the design and location of margins in restorative dentistry. Journal of Interdisciplinary Dentistry. 2012 Jan 1;2(1):3.

56. THANK YOU

57. CORDLESS TECHNIQUES- Merocel : Merocel retraction strips are made of a synthetic material that is specifically chemically extracted from a biocompatible polymer(hydroxylate polyvinyl acetate). Expasyl: It is a paste for gingival retraction that not only opens the sulcus but also leaves the field dry, ready for impression making or cementation .

58. The mesial one half crown requires an unblemished distal surface on the molar abutment. The non rigid attachment must not be used indiscriminately. Because of mesial component of force, the female portion of attachment is usually placed on distal surface of mesial abutment. The cantilever effect on the non- rigid design can pace additional stress on the abutment with the rigid connector, therefore rigid connector is only placed on a strong abutment, and the non rigid design is avoided altogether with long span pontics. Telescopic prosthesis requires radical tooth preparation to provide adequate space for the telescopic coping and the overcasting . The mesial one- half crown preparation, the non - rigid attachment (semi- precision or stress breaker) and the telescopic prosthesis have been suggested to solution to the problem. The mesial one half crown requires an unblemished distal surface on the molar abutment. The non rigid attachment must not be used indiscriminately. Because of mesial component of force, the female portion of attachment is usually placed on distal surface of mesial abutment. The cantilever effect on the non- rigid design can pace additional stress on the abutment with the rigid connector, therefore rigid connector is only placed on a strong abutment, and the non rigid design is avoided altogether with long span pontics. Telescopic prosthesis requires radical tooth preparation to provide adequate space for the telescopic coping and the overcasting