Perio cons in fpd /certified fixed orthodontic courses by Indian dental academy

  • 1,009 views
Uploaded on


The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

More in: Education
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
1,009
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
57
Comments
0
Likes
1

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. PERIODONTAL CONSIDERATIONS FOR FIXED PROSTHODONTICS. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • 2.               Introduction Anatomy Terminologies Pathogenesis Examination Placement of margins of restorations Tissue dilation Temporary and provisional crowns Embrasures Pontics Gingival finish lines Summary & conclusion Review of literature References www.indiandentalacademy.com
  • 3. INTRODUCTION Dental restorations and periodontal health are inseparably inter-related. The adaptation of the margins, the contours of the restorations, the proximal relationships and the surface smoothness have critical biologic impact on the gingival and supporting periodontal tissues. In addition to esthetics, the purpose of fixed prosthesis includes the improvement of masticatory efficiency and prevention of tilting and extrusion of teeth which results further in occlusal problems and food impaction. www.indiandentalacademy.com
  • 4. In the fabrication of any fixed prosthesis it is imperative that the periodontal status of the involved abutment teeth be determined. This enables the Prosthodontist to make a reliable and accurate prognosis for the restoration. Because periodontal disease is a major cause of tooth loss in adults, it is essential that the practioner be aware of the basic concepts and modes of therapy available in periodontics to develop an appropriate diagnosis and treatment plan. www.indiandentalacademy.com
  • 5. ANATOMY GINGIVA: The gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounding the necks of the teeth. The gingiva is divided anatomically into marginal, attached and interdental areas. The marginal, or unattached, gingiva is the terminal edge or border of the gingiva surrounding the tooth like a collar. www.indiandentalacademy.com
  • 6. Gingival sulcus: It is the shallow crevice or space around the tooth bounded by the surface of the tooth on one side and the epithelium lining the free margin of the gingiva on the other. It is V shaped and barely permits the entrance of the periodontal probe. In clinically healthy gingiva in humans, a sulcus of some depth can be found. The depth of this sulcus, as determined in histologic sections, has been reported as 1.8 mm, with variations of from 0 to 6 mm. www.indiandentalacademy.com
  • 7. Attached gingiva: the attached gingiva is continous with the marginal gingiva. It is firm, resilient, and tightly bound to the underlying periosteum of alveolar bone. The facial aspect of the attached gingiva extends to the relatively loose and movable alveolar mucosa, from which it is demarcated by the mucogingival junction. The width of the attached gingiva is another important clinical parameter. It is the distance between the mucogingival junction and the projection on the external surface of the bottom of the gingival sulcus or the periodontal pocket. www.indiandentalacademy.com
  • 8. Interdental gingiva: the interdental gingiva occupies the gingival embrasure, which is the interproximal space bemeath the area of tooth contact. The interdental gingiva can be pyramidal or have a col shape. Normal gingiva exhibiting no fluid exudates or inflammation due to bacterial plaque is pink and stippled. In a normal healthy patient there is no visible flow of sulcular fluid, but as disease progresses the crevicular flow increases. www.indiandentalacademy.com
  • 9. www.indiandentalacademy.com
  • 10. PERIODONTAL LIGAMENT: The periodontal ligament is the connective tissue that surrounds the root and connects it with the bone. It is continous with the connective tissue of the gingiva and communicates with the marrow spaces through vascular channels in the bone. The periodontal ligament is composed of collagen fibers arranged in bundles that are attached from the cementum of the tooth to the alveolar bone of the jaw. www.indiandentalacademy.com
  • 11. It provides attachment and support, nutrition, synthesis and resorption, aids in shock absorption, has formative and remodeling properties, supplies nutrition to cementum, bone and gingiva ( by way of blood vesels and lymphatic drainage), and transmits tactile, pressure and pain sensations thru its abundant sensory nerve fibers ( by the trigeminal pathway). It is subjected to constant flux of change attributable to disease and masticatory forces. The healthy periodontal ligament in functional occlusion is about 0.25 ±0.1 mm wide; it is widest at the margin and apex while narrowest in the middle one third. www.indiandentalacademy.com
  • 12. The two basic forms of periodontal diseases are gingivitis and periodontitis. GINGIVITIS: Gingivitis is the most common form of gingival disease, it is defined as inflammation of the gingiva. The two earliest symptoms of gingival inflammation, which precede established gingivitis are, (1) increased gingival fluid production rate, and (2) bleeding from the gingival sulcus on gentle probing. www.indiandentalacademy.com
  • 13. PERIODONTITIS: Periodontitis is an inflammatory disease of the gingiva or the deeper tissues of the periodontium and is characterized by pocket formation and bone destruction. Periodontitis is considered a direct extension of neglected gingivitis. Periodontitis is caused by extrinsic irritating factors and is complicated by intrinsic disease, endocrine disturbances, nutritional deficiencies, periodontal traumatism and other factors. www.indiandentalacademy.com
  • 14. When a loss of connective tissue attachment occurs, the lesion transforms from gingivitis into periodontitis, a disease that may be characterized by alternating periods of quiescence and exacerbations. The extent to which the lesion progresses before it is treated will determine the amount of bone and connective tissue attachment loss that occurs and will subsequently affect the prognosis of the tooth with regard to restorative demands. www.indiandentalacademy.com
  • 15. ETIOLOGY: Most gingival and periodontal diseases result from microbial plaque, which cause inflammation and its subsequent pathologic processes. Other contributors to inflammation however are calculus, acquired pellicle, material alba and food debris. TERMINOLOGIES: MICROBIAL PLAQUE: It is a sticky substance composed of bacteria and their by- products in an extra cellular matrix and also containing substances from the saliva, diet and serum. It is basically a product of the growth of bacterial colonies and is the initiating factor in gingival and periodontal disease. Left undisturbed it will gradually cover the entire tooth surface and can be removed only by mechanical means. www.indiandentalacademy.com
  • 16.    CALCULUS: Dental calculus is a chalky or dark deposit attached to the tooth structure. It is essentially microbial plaque that has undergone mineralization with the passage of time. ACQUIRED PELLICLE: Pellicle is a thin brown or grey film of salivary proteins that develops on teeth after they have been cleaned. MATERIAL ALBA: This is a white coating composed of micro-organisms, dead epithelial cells and leukocyte that is loosely adherent to the tooth. It can be removed by water spray or rinsing. www.indiandentalacademy.com
  • 17.    OCCLUSAL TRAUMATISM: Occlusal traumatism can be defined as a force originating by movement of the maxillary and mandibular teeth in a way that creates a pathologic lesion. PRIMARY OCCLUSAL TRAUMA: It is a pathologic lesion that has been created by a force strong enough to disturb a normal intact periodontium. SECONDARY OCCLUSAL TRAUMA: It is a lesion created by a normal function on a weakened periodontium because of periodontal disease. www.indiandentalacademy.com
  • 18.  PERIODONTAL POCKET: It is a diseased periodontal attachment unit. It is caused by the apical migration of the epithelial attachment with loss of connective tissue attachment and eventually osseous support. The pocket may also result from the enlargement of the gingival tissue. www.indiandentalacademy.com
  • 19.  PATHOGENESIS: INITIAL LESION: The initial lesion is localized in the region of the gingival sulcus and is evident at approximately 2-4 days of undisturbed plaque accumulation from a baseline of gingival health. The vessels of the gingiva become enlarged and vasculitis occurs, allowing a fluid exudate of the polymorphonuclear leukocytes to form in the sulcus. Collagen is lost perivascularly, and the resultant space is filled with proteins and inflammatory cells. The most coronal portion of the junctional epithelium becomes altered. Clinically this stage is not apparent. www.indiandentalacademy.com
  • 20.  EARLY LESION: Although there is no distinct division between the stages of lesional formation, the early lesion appears within 4-7 days of plaque accumulation. This stage of development exhibits further loss of collagen from the marginal gingiva. In addition an increase in gingival sulcular fluid flow occurs with the increase in inflammatory cells and accumulation of lymphoid cells adjacent to the junctional epithelium. The basal cells of the junctional epithelium begin to proliferate and significant alterations are seen in the connective tissue fibroblasts. www.indiandentalacademy.com
  • 21.  ESTABLISHED LESION: Within 7-21 days the lesion enters the established stage. It is still located in the apical portion of the gingival sulcus and the inflammation is centered in a relatively small area. There is continuing loss of connective tissue, with persistence of the features of the early lesion. This stage exhibits a predominance of plasma cells, the predominance of immunoglobulins in the connective tissue, and a proliferation of the junctional epithelium. Pocket formation, however, does not necessarily occur. www.indiandentalacademy.com
  • 22.  ADVANCED LESION: It is difficult to pinpoint the time at which the established lesion of gingivitis results in a loss of connective tissue attachment to the tooth structure and becomes an advanced lesion, or overt periodontitis. Upon conversion to the advanced stage the features of an established lesion the features of an advanced lesion persist. The deeper layers of the connective tissues becomes involved with the ingress of inflammatory cells that enhance osteoclastic activity, resulting in a breakdown of the alveolar process if at the same time the tooth is under occlusal trauma this area will change. There can be a concomitant lesion of the periodontal disease with the occlusal traumatic lesion enhancing the loss of bone around the tooth. Periodontal pockets are formed with increased probing depths. www.indiandentalacademy.com
  • 23.   EXAMINATION: VISUAL EXAMINATION: It is important during the examination to evaluate the color, consistency, texture and shape of the gingival unit. It is also critical to recognize the initial stages of a marginal lesion. An adequate light source is essential to differentiate between normal and diseased tissues. (Normal gingiva: Colour – coral pink, physiologic melanin pigmentation, scalloped contour on facial or lingual surface, firm and resilient consistency, stippled attached gingiva, normal size, shape and position). www.indiandentalacademy.com
  • 24.  PROBING: The thinnest probe is desired. The probes are calibrated in mm. The Prosthodontist should probe six areas around the tooth. Evaluation should include bifurcation and trifurcation areas on the molars and maxillary first premolars. During probing the Prosthodontist should check for bleeding or exudation, these are also signs of periodontal disease. Clinically the bleeding of the gingiva during probing is the sign of ulceration of sulcular epithelium. Specially treated paper to monitor the intracrevicular fluid is used. www.indiandentalacademy.com
  • 25.  MOBILITY: A classification of 1-3 is used. With 1 representing the early stage of mobility and 3 representing a tooth mobile in all direction and depressible in the socket. Mobility is an indication of the loss of tooth attachment to the jaw. This can be seen radio graphically as a widened periodontal ligament space caused by occlusal trauma or orthodontic tooth movement. It can also be caused by periodontal diseases. www.indiandentalacademy.com
  • 26. RADIOGRAPHS:  They provide essential information to supplement the clinical examination. The most useful type in evaluating the tooth to bone relationship is the long cone technique. The areas to be reviewed on the radiographs are: a). Alveolar crest resorption. b). Integrity of thickness of the lamina dura. c). Evidence of generalized horizontal bone loss. d). Evidence of vertical bone loss. e). Widened periodontal ligament space. f). Density of trabeculae of both arches. g). Size and shape of the roots compared to the crown to determine crown to root ratio. www.indiandentalacademy.com
  • 27. The radiographs can determine the area of root embedded in bone, this is crucial in determining the patient’s prognosis. Often patients with short conical root will display minimal bone loss but maximal mobility, and the prognosis is thus poor. Other patients can loose 50 per cent of the bone but not exhibit mobility, and yet have an encouraging prognosis because they have normal shaped roots. www.indiandentalacademy.com
  • 28.  HABITS: The major habit to consider is bruxism. Visual examination of wear facets and radiographic interpretation of thickened lamina dura and widened periodontal ligament space determines whether a patient grinds in his sleep. One condition that indicates bruxism is a complete arch that exhibits mobility despite adequate osseous support. www.indiandentalacademy.com
  • 29. PLACEMENT OF MARGINS OF RESTORATIONS: Except for the risk of subgingival decay and esthetic considerations, it is best to terminate preparations above the gingival margins. If periodontal therapy has been performed and the gingiva has receded, the preparation should end at the cemento-enamel-junction. Even if the tissue does not recede the margin of the tooth preparation should be away from the soft tissues. Crown margins when placed sub gingivally should be located at the base of the gingival sulcus. The gingival fibers can then brace the gingiva against the tooth and the margin of the completed restoration. www.indiandentalacademy.com
  • 30.   The margins of the preparation are not usually placed at the crest of the marginal gingiva regardless of how precise the margin of the restoration. Microscopically the margins of the restoration are rough and are excellent site to harbor bacteria. Since the margins of the gingiva rapidly collect plaque, this is the site of recurrent decay. If decay does not result, the plaque causes periodontal disease at this most critical area which is not self cleansing. Conversely, restorations should not be forced subgingivally into the connective tissue, but placed in the intra crevicular space without violating the biological width. Tearing of the epithelial attachment causes it to migrate apically and the sulcus to deepen into a pocket. www.indiandentalacademy.com
  • 31. www.indiandentalacademy.com
  • 32. SUPRAGINGIVAL MARGINS: Whenever possible margins are prepared supragingivally on the enamel of the clinical crown. In addition to the favorable reaction of the gingiva, other advantages are gained, a common path of insertion; wider shoulder tooth preparations can accommodate an adequate bulk of porcelain veneering material in the cervical area without pulpal injury and metal margin finishing techniques are easier. Crown margins on exposed root surfaces but still supragingival, are necessary for extensive fixed partial dentures to secure longer retainers while encouraging gingival health. www.indiandentalacademy.com
  • 33. INTRACREVICULAR MARGIN PLACEMENT: This term for margin placement implies confinement within the gingival crevice. It is preferable to the term subgingival since it’s more specific. Despite the advantages of supragingival margins there are clinical situations requiring intra crevicular placement even in the periodontally treated teeth. They are: a). Esthetics. b). Caries beyond the gingival crest. c). Cervical erosions. d). Adequate crown retention in short or broken down clinical crowns. e). Elimination of persistent root hypersensitivity. www.indiandentalacademy.com
  • 34. INTRACREVICULAR DEPTH: The average crevice depth according to GARGIULO et al was between 0.5-1 mm whether adjacent to enamel or root surfaces. Therefore, the ideal intracrevicular position for the margins is 0.5 mm beneath the gingival crest, especially when the crevice is adjacent to root surfaces. While the average crevicular depths are nearly identical for enamel or root surfaces, the average length of the junctional epithelium on the root is between 0.5 and 1 mm shorter than that on enamel. Thus overextension of margin placement beneath the gingiva on root surfaces impinges on gingival connective tissues. www.indiandentalacademy.com
  • 35. www.indiandentalacademy.com
  • 36. PULPAL INVOLVEMENT:  In posterior regions, intracrevicular margin placement after the gingival margins have receded is accomplished with minimal pulpal trauma if chamfer or knife edge margins are prepared. WOUND HEALING CONSIDERATIONS  The time elapsed after completion of the periodontal treatment is crucial when intra crevicular margins are anticipated. Healing of extensive periodontal surgery usually requires at least 3 months and often more to establish a new biologic width, crevice and stable position of gingival margin and papilla. Even areas treated by scaling, root planning and plaque control may take more than 1 or 2 months for their gingival margins to stabilize. Gingival margins after surgery migrate coronally but recede apically after scaling and root planning. Margins prematurely placed intracrevicularly in the second situation often becomes exposed as healing progresses and the result may be unesthetic. www.indiandentalacademy.com
  • 37. AVOID THE GINGIVAL THIRD: The risk of irritation to the gingiva is reduced by restorations that terminate coronal to the gingival margin. Whenever possible inlays, pin ledges, and three quarter crowns should be used as individual restorations and retainers for fixed prosthesis. This does not mean substituting other restorations for purposes that can only be fulfilled by full crowns. www.indiandentalacademy.com
  • 38. ATTACHED GINGIVA: The gingiva adjacent to intracrevicular crown margins is an important pre-preparation consideration. The various steps in the fabrication of a crown are traumatic to the gingival sulcus and recession is common. The friable mucosa is especially vulnerable during instrumentation. Empirical estimates have suggested 5 mm of keratinized tissue composed of 2 mm of free gingiva and 3 mm of attached gingiva for subgingival margins. This may be excessive since it is recommended that the placing margins no further than 1.5 to 2 mm beneath the gingival crest, whereas others concluded that beyond 0.5 – 1 mm is excessive. www.indiandentalacademy.com
  • 39. Nevertheless the avoidance of traumatic gingival recessions usually depends on a zone of thick keratinized gingiva 4-5 mm in width of which 2-3 mm is attached. Despite tissue keratinization if the probe is seen thru the free gingival margin, the ability to resist trauma is doubtful. The surgical placement of a thickness free autogenous gingiva graft is indicated before the final tooth preparation. www.indiandentalacademy.com
  • 40. ATRAUMATIC PREPARATION: The free and attached gingiva resists insults more effectively if the connective tissue fibers are intact and not inflamed. DRAGOO and WILLIALS have demonstrated that the placement of retraction cord into the sulcus before preparation protects the epithelium from damage. www.indiandentalacademy.com
  • 41. GINGIVAL RETRACTION FOR TAKING IMPRESSIONS: When taking plastic impressions it is often necessary to retract the gingiva to gain access to the gingival margin of the preparation. There are methods for retracting the healthy gingiva. They are not for the removal, displacement, or shrinkage of inflamed swollen gingival tissue. The gingiva must be healthy and its position on the tooth established before the impression is made. There are several terms for the process of exposing margins when making impressions of prepared teeth. www.indiandentalacademy.com
  • 42. Tissue dilation is synonymous with tissue retraction or displacement. Tissue management is the key factor in accurately duplicating subgingival margins. In performing tissue dilation, the Prosthodontist must recognize the importance of using a regimented approach from diagnosis to cementation of the restorations. The gingival tissue should be healthy before restorative procedures begin, particularly with complete restorations that require a margin below the crest of the gingiva. www.indiandentalacademy.com
  • 43. TISSUE HEALTH: The rationale for tissue dilation does not originate with exposing gingival margins, since the health of the gingival tissues is crucial for success. Acceptable healthy gingival tissue is essential, as inflamed, redundant tissue is a liability to tissue dilation. Also, after impressions are made the tissue should be supported by appropriate treatment restorations on the newly prepared teeth. Tissue shrinkage may occur after gingival margin placement or from irritation caused by treatment restorations. www.indiandentalacademy.com
  • 44. In addition, patients receiving restorative procedures should be introduced to a regimental oral hygiene program. If gingival surgery was done, tissue should be mature before tooth preparation and tissue dilation. The healing of the gingival tissues after periodontal surgery varies, but a minimum of 3 to 5 weeks is recommended before preparation and tissue dilation. www.indiandentalacademy.com
  • 45. TISSUE DILATION: Classification The classification for tissue dilation is as follows: 1. Mechanical - the tissue is displaced or dilated strictly by mechanical methods. 2. Mechanical-chemical - a cord is used for mechanically separating the tissue from the cavity margin and is impregenated with a- chemical for hemostasis as impression are made. www.indiandentalacademy.com
  • 46. 3. Surgical - a ribbon of gingival tissue is removed from the sulcus around the cavity margin with dental electrosurgery. The procedure creates a space in the tissue surrounding the tooth, control seepage, and provides a trough for the impression material. Another method is gingitage-the literature has indicated successful exposure of the cavity margin with healing comparable to dental electrosurgery. In this technique, special diamond stones remove the sulcus epithelium as the margins are finished beneath the crest of the gingiva. The cast metal preparation is constructed to minimize tissue laceration with sub gingival margins. Tissue laceration can be reduced by avoiding sub gingival margins and creating a sulcus space by dilation with a mechanical or mechanical -chemical method. www.indiandentalacademy.com
  • 47. The entire procedure is commonly repeated before making an additional impression. When using the surgical method tissue dilation is not repeated. Only cleansing and spot coagulation to control bleeding in the created sulcus is necessary. Additionally some dentists prefer to pack an astringent medicated cord into the surgical through to control seepage. Elastomeric impression material does not displace blood, salvia, debris, or tissue. The tissue therefore is displaced laterally, or a ribbon of tissue is removed to expose the tooth preparation margin before the impressions. The tissue adjacent to the exposed preparation margin must also be reasonably dry and clean for accurate impressions. www.indiandentalacademy.com
  • 48. Mechanical tissue Dilation Mechanical dilation is possible, but most is carefully performed to minimize trauma. Oversized copper bands are contoured to the gingiva and restricted towards the preparation margin when gently seated over the tooth. A resin or compound plug is placed on the top for stability, and band is vented for escape of excess elastomeric impression materials. A loop of dental floss is threaded through the vent to ease band removal after the impression material has set. www.indiandentalacademy.com
  • 49. The dentist must not exert excessive pressure on the band, or the tissue may be stripped from the tooth. Since tissue dilation can be accomplished effectively by other method s mechanical dilation has limited application, but is a superb method to confirm gingival margins, ie multiple abutments, full arch impressions with one or two questionable margins. www.indiandentalacademy.com
  • 50. Mechanical Chemical Dilation Mechanical chemical dilation consists of cords impregnated with chemical that are eased into the intracrevicular space beneath the preparation margin without force. The area must be kept dry but not dessicated if the hemostatic chemical in the cord is to have maximum affectiveness .After 5 to 10 minutes, the cord is gently removed and the sulcus surrounding the preparation margin is exposed and hemostasis maintained. If bleeding is still evident, the crevice is repacked for an additional 5 minutes. www.indiandentalacademy.com
  • 51. If the area has been isolated with cotton rolls, the packed cord is damped before removal, as occasionally a dry cord adheres to the sealed capillaries and, on removal, cause bleeding. subgingivally , the packing insrument is directed towards the area where the cord is already secure. Pushing away from the area previously retracted dislodges the cord. Cords impregnated with alum or aluminium choloride provide a styptic action to control the seepage. Hemostatic agents like epinepheine are not recommended in patients with cardiac problems. www.indiandentalacademy.com
  • 52. Surgical Tissue Dilation Continues visualization of the subgingival margin is difficult for the dentist. Cords chemicals, rubber or leather rings, copper stainless steel and aluminium bands with other materials have been suggested for this purpose. With refinement of dental electro surgery, many of the problems of securing impressions of multiple abutment preparation can be alleviated. www.indiandentalacademy.com
  • 53. Electrosurgery requires profound local anesthesia. Odor is controlled by an outside ventilated oral evacuator system. Plastic suction tips are used, since momentary contact of an activated working electrode with a metal aspirator tip causes spot coagulation where ever the metal touches the tissue. For the same reason, plastic mounted mouth mirrors are indicated. The passive or indifferent plate is positioned under the patient's shoullder for biterminal application. Monoterminal applications are rare. www.indiandentalacademy.com
  • 54. CURRENTS AND ELECTRODE SELECTION Selection of electrodes varies, depending on the tooth and its arch position. This procedure can be performed without patient discomfort in relatively bloodless field. With each electrode the basics of electrosurgery are sustained. The working electrode must be clean and without carbonization. In exacting marginal dilation, a carbonised electrode has a tendency to drag, tearing the tissue and causing bleeding. If a straight wire tip, varitip, or minute continuous loop electrode is used; they should be cleaned between each application. www.indiandentalacademy.com
  • 55. The depth of tissue removal is determined by the morphology of the tissue and the biologic width. The tissue should extend about 0.3 to 0.5 mm below the margin of the cast restoration for definite margin detection in the impression and on the master dies. When using a continuous loop there is usually a small amount of tissue left beneath of the margin because of the shape of the loop. This tissue tag is removed using a single-wire or variabletip electrode wire. The variable-tip electrode wire can be adjusted to the desired length. The troughting procedure is pressureless, and if additional tissue refinement is required, a time laps of at least 5 second is needed to dissipate heat. www.indiandentalacademy.com
  • 56. Posner Electrode With the AP 1½ electrode, the insulated portion of the electrode is directed around the tooth, removing the gingival sulcular epithelium. The 1½ disignation of the AP 1½ mm beyond the insulation. This offers a precise, uniform 1½ mm sulcus depth incision. If less trough depth is desired, part of the tip is removed to create the desired depth at 0.5 mm, 0.75 mm, or 1.0 mm. www.indiandentalacademy.com
  • 57. Electrode Tip Variable-tip or straight-wire electrodes are popular. Tooth preparation with the desired margin is completed, and margins are terminated above the soft tissue. The single wire of the variable tip is adjusted to the desired subgingival depth, and the tooth is then circumscribed by repeated approaches around the tooth in segments. First the lingual subgingival trough; then the facial surface; and then the mesial and distal surfaces are established. This prevents heat accumulation in the tissue. For most dentists, it is virtually impossible to circumscribe a tooth with one or two connecting passes. If a straight-wire electrode or the variabletip electrode is used, the operator may find that the electrode is too fine to remove enough tissue to provide adequate bulk of impression material in the sulcus. www.indiandentalacademy.com
  • 58. This is especially true if the end of the working electrode is positioned parallel with the long axis of the tooth. By angling the working electrode at approximately 15 to 20 degrees and carrying the tip through the tissue until it rests against the tooth, a small wedge of tissue can be removed. If bleeding occurs, it is usually interproximal and controlled with the same electrode using coagulation current. Another method uses equal parts of hydrogen peroxide and water to arrest slight local hemorrhage. After the area is dry, the extended sulcus is debris free and the root and crown easily visualized. The margins can then be finished to the desired depth, the area again flushed with water and peroxide and the impressions secured. www.indiandentalacademy.com
  • 59. In the anterior quadrants where the gingiva is especially thin, the angle of the working electrode is changed to be more nearly parallel to the long axis of the tooth. Again with the segmented approach, the sulcular epithelium is removed, and if a narrow facial-lingual sulcus has been created, the cord is placed before the impression to retract the tissue away from the tooth. It is axiomatic that the treatment restoration be suitably adapted to the existing margins without luting material impinging on the regenerating sulcular epithelium. www.indiandentalacademy.com
  • 60. Dental impressions ideally extend 0.3 to 0.5 mm below the preparation margin to ensure accuracy. Electro-surgical removal of a ribbon of tissue around the preparation margin provides necessary space for adequate bulk of the elastic impression material. After securing the final impression or impressions, tincutre of myrrh and benzoin (Oringer's solution) is placed on the surgical area and air dried, this procedure is repeated three to five times before the treatment restoration is placed. Orabase may replace or supplement myrrh and benzoin in this procedure. The tissue healing is rapid, and the subgingival trough heals in 5 to 7 days. Discipline is imperative to the uneventful exposure of the cavity margin for making impressions for cast restorations. Tissue trauma, expenditure of time, and the shrinkage of tissue restricts traditional mechanical tissue dilation. www.indiandentalacademy.com
  • 61. The mechanical-chemical method with cords can reduce trauma to the tissue but may produce a thin layer of impression material at the preparation margin once the cord is removed, since the tissue returns immediately to its original position. If a thin layer of Impression material persists; marginal distortion of the individual dies results because of insufficient material in a critical area. www.indiandentalacademy.com
  • 62. Dental electrosugery provides a rapid efficient method for tissue dilation, with adequate impression material in crucial areas. It does not cause significant shrinkage of the tissue or patient discomfort if appropriate post operative medication is used. The key factors for successful electro surgery are: profound anesthesia; appropriate current selection; a light stroke with a 5 second time interval between applications of the electrode; and maintaining the biologic width after tissue healing. www.indiandentalacademy.com
  • 63. TEMPORARY AND PROVISIONAL CROWNS: Temporary and provisional crowns with intracrevicular margins are usually associated with gingival recession. The gingiva recovers its original position after the permanent crown is in place, but the possibility of permanent recession increases the longer the temporary restoration is in place. Gingival recession is avoided around temporary crowns by careful preparations and by making contours of the treatment restoration resemble those of the natural teeth. www.indiandentalacademy.com
  • 64. EMBRASURES: Restorative dental procedures too often result in the restorative materials taking up place that is normally occupied by the interdental papilla. This problem has been accentuated with the advent of restorations in which porcelain is bounded to metal. The problem begins when there is under preparation of the tooth, so that the technician is left with no other choice except to place an excessive amount of restorative material into the inter proximal space. During the preparation of dies for cast preparation, the technician first removes all the replicated gingival tissue to gain access to the margins, thus it is impossible to visualize the space available for dental restorations in the inter proximal enclosure areas. www.indiandentalacademy.com
  • 65. If two models are poured from the same impression and the second one is used as an indication of how much space is currently occupied by the gingival tissues, the technician can have a better understanding of what the contour of the final restoration should be. Over crowding of the inter dental space results in a narrowed embrasure area that makes maintaining oral hygiene difficult. The space available for gingival tissues is reduced also, so that a thin strand of collagen is often all that can occupy this place. This reduction in the space available for the gingiva means that the space where collagen should form an effective seal in association with the junctional epithelium is diminished. www.indiandentalacademy.com
  • 66. This may lead to periodontal destruction, pocket formation and bone loss. In fixed bridge work the soldered joint is frequently carried too far in an apical direction and so it invades the embrasure space from its coronal aspect. This also leads to inadequate space for the interdental papilla. For patients who require increased strength in a soldered joint it is best obtained by extending the soldered joint buccally and lingually. The Prosthodontist and not the technician should determine the size of the soldered joint because he is aware of how much gingiva is available in the inter proximal embrasure. www.indiandentalacademy.com
  • 67. BIOLOGIC WIDTH EMBRASURES: The teeth touch in area called proximal contact, the spaces below the contact are known as embrasures. In health, the embrasures are usually filled with tissue. Embrasures protect the gingiva from food impaction and deflect the food, to massage the gingival surface. They provide spillways for food during mastication and relieve occlusal forces when resistant food is chewed. The proximal surfaces of dental restorations are important because they determine the embrasures essential for gingival health. www.indiandentalacademy.com
  • 68. In disease and periodontal therapy this tissue is reduced, the new restorations create another embrasure that will locate the restorations close to the new level of the gingiva. The proximal surfaces of crowns should taper away from the contact area on all surfaces. Excessively broad proximal contact areas and inadequate contour in the cervical areas suppress the gingival papillae. These prominent papillae trap food debris, leading to gingival inflammation. www.indiandentalacademy.com
  • 69. Proximal contacts that are too narrow buccolingually create enlarged embrasures without sufficient protection against interdental food impaction. The inter dental brush (proxa brush) and dental floss are effective in deplaquing the tooth surface at the gingival margin. The proximal contact should be such that the brush snuggly fits in the embrasure areas. www.indiandentalacademy.com
  • 70. PONTICS: Porter recommends the elimination of embrasures between pontics to simplify oral hygiene and curtain saliva expectoration. The ridge lap and conical shape designs are infrequently recommended. The ridge lap creates an uncleansible contact area leading to inflammation of the edentulous mucosa below the prosthesis. The spheriodal pontic contacts without pressure the top of the ridge at the buccal surface, depending upon the relationship of the residual ridge to the opposing dentition. All in all a pontic should have only minimal passive contact with the ridge, excessive pressure causes inflammation and proliferation of the tissues. The pontic should not blanch the tissues or be placed on the movable mucosa. www.indiandentalacademy.com
  • 71. www.indiandentalacademy.com
  • 72. CONTOURS OF RESTORATIONS: The facial and lingual contours of restorations are also important in the preservation of gingiva health. The most common error in creating the contours of the tooth in dental restorations is over contouring of facial and lingual surfaces. This overcontouring generally occurs in the gingival third of the crown and results in an area where oral hygiene procedures are unable to control plaque. Consequently plaque accumulates and gingiva becomes inflamed. Over contouring on the buccal or labial surfaces frequently in porcelain fused to metal crowns owing to the technicians attempt to obtain a thickness of porcelain adequate to mask the underlying metal and provide an aesthetic appearance to the crown. www.indiandentalacademy.com
  • 73. Hence, it is important for the Prosthodontist to remove enough tooth material during tooth preparation. In patients in whom periodontal disease causes the gingival margin to be in a much apical position than it was during health, the facial and lingual contours become even more significant. In these cases the bulge on the facial contour of the crown which would be sub gingival normally appears supra gingivally. This makes the position of the exposed root immediately apical to the bulge less accessible for oral hygiene with resultant plaque accumulation and gingival inflammation. www.indiandentalacademy.com
  • 74. OCCLUSAL SURFACE: They should restore occlusal dimensions and cuspal contours in harmony with remainder of the natural dentition after occlusal abnormalities have been eliminated by occlusal adjustment. The occlusal surface of the teeth should not be arbitrarily narrowed. Proper occlusal relationships are more important than the width of the occlusal table in the attainment of physiologic occlusal surfaces. The anatomy of the occlusal surface should provide well formed marginal ridges and occlusal sluiceways to prevent inter proximal food impaction. www.indiandentalacademy.com
  • 75. EFFECT OF SURFACE FINISH ON THE PERIODONTIUM: The surface of the restorations should be as smooth as possible to limit plaque accumulation. All restorations should have a very high polish and smooth surface texture. CEMENTATION: Retained cement particles irritate the gingiva and should be removed. It is important that the restoration be sealed as close to the tooth preparation as possible. After cementation it is very important that no cement is left in the interproximal spaces. Oral hygiene procedures become a problem if the cement is left behind. Hence floss should be passed along the interproximal margins to ensure that no cement is left back and the margins are free. www.indiandentalacademy.com
  • 76. GINGIVAL FINISH LINES: Margins are one of the most important and weakest lines in the success of any fixed partial denture restorations. Tooth preparations for fixed prosthodontics requires a decision regarding the marginal configurations. The design dictates the shape and bulk of the casting and influences the fit at the margin. Although many factors such as materials, esthetics and access influence this selection, most dentists probably have a preferred design. However, there is disagreement about what constitutes ideal margin, geometry and width. www.indiandentalacademy.com
  • 77. GINGIVAL TERMINATION OF TOOTH PREPARATION: Tooth preparations terminate in a finish line. Some terminate on the occlusal and axial surfaces and are referred to as cavo surface angles. The most controversial, however, are the gingival finish lines. The previous recommendations were to extend crown margins into the intracrevicular space because the gingival crevice was supposed to be immune to caries. Deviation from this norm was supposed to be irresponsible, despite the fact that strong evidence supported supragingival margins. www.indiandentalacademy.com
  • 78. Conversely, subgingival margins are considered necessary for the following reasons: a). Esthetics. b). Presence of existing restorations extending into the intracrevicular space. c). Insufficient vertical length for retention. d). Higher D.M.F rate of younger patients. One commonly ommited fact is that the soft tissue approximating the tooth is usually unhealthy before preparation. www.indiandentalacademy.com
  • 79. Therefore, the removal of tissue with questionable architecture and re growth of healthier tissue is a rational direction of treatment. Interceptive periodontics resulting from the early recognition of tissue symptoms is recommended. Question, where the finish lines should be placed for proper contour of the restoration requires analysis. The sub gingival area is not an immune area. Additionally, if there is any validity to the theory of passive eruption, the sub gingival margin could become supra gingival in a short time. Therefore, the dentist’s evaluation should include enquiry into the longevity of the restoration. www.indiandentalacademy.com
  • 80. MARGIN PLACEMENT: Whenever possible, the margin of the preparations should be supra gingival. Sub gingival margins of cemented restorations have been identified as a major factor in periodontal diseases, particularly where they encroach upon the epithelial attachment. Supra gingival margins are easier to prepare accurately without trauma to the soft tissues. They can usually also be situated on hard enamel whereas sub gingival margins are often on dentin or cementum. www.indiandentalacademy.com
  • 81. Other advantages of supra gingival margins include the following: a). They can be easily finished. b). They are more easily kept clean. c). Impressions are more easily made, with less potential for soft tissue damage. d). Restorations can be easily evaluated at recall appointments. www.indiandentalacademy.com
  • 82. However, a sub gingival margin is justified if any of the following pertain: a). Dental caries, cervical erosions or restorations extend sub gingivally and a crown lengthening procedure is not indicated. b). The proximal contact area extends to the gingival crest. c). Additional retention is needed. d). The margin of a metal ceramic crown is to be hidden behind the labiogingival crest. e). Root sensitivity cannot be controlled by more conservative procedures. f). Modification of the axial contour is indicated. www.indiandentalacademy.com
  • 83. MARGIN ADAPTATION: The junction between a cemented restoration and the tooth is always a potential site for recurrent caries because of the dissolution of the luting agent. Where possible it should be kept as short as possible. Rough or irregular junctions greatly increase the length of the margins and reduce the possibility of obtaining a good fitting restoration. The importance of smooth margins is emphasized. Time spent obtaining a smooth margin will make the subsequent steps of tissue displacement, impression making die formation, waxing and finishing much easier and ultimately will provide the patient with a longer lasting restoration. www.indiandentalacademy.com
  • 84. MARGIN GEOMETRY: The cross-sectional configuration of the margin has been the subject of much analysis and debate. Different shapes have been described and advocated. For evaluation the following guidelines should be considered: a). It should be easy to prepare without over extension. b). It should be readily identified in the impression and on the die. c). It should give a distinct margin to which the wax pattern can be finished. d). It should provide for sufficient bulk of material. This will enable the wax pattern to be handled without distortion as well as give the restoration strength and, where porcelain is used esthetics. e). It should be as conservative as possible provided the other criteria are met. www.indiandentalacademy.com
  • 85. TYPES OF FINISH LINES: Feather edge or shoulder less: Feather edge or shoulder less crown preparations should be avoided because although they are conservative preparations; they fail to provide adequate bulk at the margins. Over contoured restorations are often the result of featheredge margins; this is because the technicians can handle the wax pattern without distortion only by increasing the bulk of the margins. www.indiandentalacademy.com
  • 86. •A. Feather edge •B. Chisel •C. Chamfer •D. Bevel •E. Shoulder •F. Sloped shoulder •G. Beveled shoulder www.indiandentalacademy.com
  • 87. A variation of the feather edge, the chisel edge margin, is formed when there is a larger angle between the axial surfaces and the unprepared tooth structure. Unfortunately this is frequently associated with an excessively tapered preparation or one in which the axial reduction is not correctly aligned with the long axis of the tooth. Under most circumstances, feather edge and chisel edges are unacceptable. Historically their main advantage was that they facilitated the making of modeling compound impressions in copper bands. Since there was ledge on which a band could catch. www.indiandentalacademy.com
  • 88. Chamfer margin: is particularly suitable for cast metal crowns and the metal only portion of metal ceramic. It is distinct, leaves adequate bulk of material, and can be placed with precision. Probably the most suitable instrument for making a chamfer margin is a tapered diamond bur with a rounded tip the margin being formed as the exact image of the instrument. The accuracy of the margin depends on having a high quality diamond and true running hand piece. The gingival margin is prepared with the diamond held precisely in the path of withdrawl of the restoration. Tilting it away from the tooth will create an undercut whereas angling it towards the tooth will lead to over reduction and loss of retention. The chamfer should never be prepared wider than half the tip of the diamond, lest an unsupported lip of enamel result. www.indiandentalacademy.com
  • 89. www.indiandentalacademy.com
  • 90. Under some circumstances a beveled margin is more suitable for cast restorations, particularly if a ledge or shoulder already exists, possibly from dental caries, cervical erosion or a previous restoration. The objective in beveling is three fold • To allow the cast metal margin to be bent or burnished against the prepared tooth structure. • To minimize the marginal discrepancy caused by the complete crown that fails to seat completely and • To protect the unprepared tooth structure from chipping. www.indiandentalacademy.com
  • 91. Because a shoulder margin allows for room for porcelain, it is recommended for an all ceramic crown and the facial part of a metal ceramic crown. It should form a 90 degree angle with the unprepared tooth surface. An acute angle is likely to chip. Some authorities have recommended a heavy chamfer rather than a shoulder margin, and some find a chamfer easier to prepare with precision. However, experimental studies show that a metal framework with a shoulder margin distorts less than a chamfer margin during porcelain fixing presumably because of the additional bulk provided by the shoulder. www.indiandentalacademy.com
  • 92. To conclude, the margin is one of the components of the cast restoration most susceptible to failure, both biologically and mechanically. Most of the investigative proof shows that supragingival margins are kinder to the gingival than are subgingival margins. However, practicality dictates that supragingival margins are not always usable. There is some indication that quality of the margin may be of as much importance to gingival health as location. Research on the configuration of margins seems to agree with the majority of authors writing technical articles. Most agree that feather edge or knife edge margins are not always the most acceptable. Apparently bulky margins with rounded internal line angles are best. www.indiandentalacademy.com
  • 93.     Complete shoulders are the classic finish lines for complete porcelain crowns. Beveled shoulders are used in preparations for veneers and selected posterior teeth. The chamfer possessed internal bulk and satisfactory margin adaptation extra coronally; it is the traditional gingival termination for posterior crowns and the lingual surfaces of anterior ceramic / metal crowns. Knife edge finish lines are used for younger patients, pin ledge three quarter crowns, inaccessible areas of the oral cavity, and finish lines on the cementum. www.indiandentalacademy.com
  • 94. www.indiandentalacademy.com
  • 95. SUMMARY AND CONCLUSION One of the primary goals of restorative therapy is to establish a physiologic periodontal climate and facilitate the maintenance of periodontal health. Traumatic occlusal relationships should be eliminated before restorative procedures are begun and restorations should be constructed in conformity with the newly established occlusal patterns. If this is not done the prostheis will perpetuate occlusal relationship injurious to the periodontium. Subgingival margins should be avoided as far as possible except in cases of caries, extending apically, short crowns hence to obtain retention, and in labial surfaces of anterior maxillary teeth in patients who demand for esthetics as a primary criteria. www.indiandentalacademy.com
  • 96. In impression making, ginival retraction methods should be followed deligently keeping the ginival health in mind. All interim restorations should be so constructed that they cause no trauma to the gingival during the time they are in the mouth. The teeth should taper away from their proximal contacts to get good healthy embrasures. Over contouring of the facial and lingual surfaces should be avoided. Over contouring in gingival third causes plaque accumulation and gingival inflammation. Pontic design greatly influences gingival health. If esthetics is a primary concern a spheriodal Pontic for the posteriors and a modified ridge lap for the anteriors is ideal. www.indiandentalacademy.com
  • 97. The occlusal surfaces should be designed to direct masticatory forces along the long axis of the tooth. The occlusal table should not be too wide to prevent undue pressure on the periodontium of the abutment teeth. A sanitary Pontic is the periodontium’s best friend. Lastly the surface of restorations should be as smooth as possible to limit plaque accumulation. But eventually after taking all these precautions, patient education and motivation towards plaque control and healthy oral habits is the secret of every treatment success. www.indiandentalacademy.com
  • 98. REVIEW OF LITERATURE: 1. Melvin L. Morris 1962 did a study on artificial crown contours and gingival health. According to him the theory of the artificial bulge in the crown is an inaccurate view of gingival coronal anatomy and physiology. This rational produces crown that are contoured in excess of anything in Nature and Causes, rather than prevents, gingival inflammation. www.indiandentalacademy.com
  • 99. 2. Sheldon Stein in 1966 did a research on Pontic ­residual ridge relationship. Pontic design was the foremost factor in obtaining inflammatory free pontic ridge relationships. The ideal design was shown to be a modified ridge lap in the posterior region and a lap facing in the anterior region, with a pin­point contact on the facial contiguous slope of the residual ridge. The ideal design should include surface smoothness and a fine finish. No distinguishing advantage was found with porcelain acrylic resin. A successful artificial tooth replacement was characterized by a healthy tissue response with the appearance of a lack of contact between the residual ridge and under surface of the pontic. www.indiandentalacademy.com
  • 100. 3. James S. Marcum in 1967 did a study on Crown Marginal depth and gingival tissue 66 gold crowns were placed and finished above, below and even with the gingival crest in 6 dogs. The crowns were left in place until the dogs were put to death at time intervals one, two and three months. Two dogs were sacrificed at each interval and block specimens of the teeth and gingiva were taken at this time. Control specimens of unoperated teeth were also taken. The block specimens were decalcified, sectioned stained, histologically examined and graded for security of inflammatory response. 600 metological slides of the tissue sections were graded as having evidence of none, slight, moderate and severe gingival inflammation. www.indiandentalacademy.com
  • 101. The investigation showed that crowns with margins located at a even with the gingival crest caused the least inflammatory response. The length of time "the restoration was in place had little, if any, effect upon severity of degree of inflammation. However it appears from results of this investigation that crowns with margins finished even with the gingival crest would be least likely to cause gingival inflammation. www.indiandentalacademy.com
  • 102. 4. Edmand Cauazos in 1968 did a study on tissue response to fixed partial denture pontics. This study demonstrates that the adaptation of a Pontic "to the ridge or the amount of relief (scraping of the cast) provided in the cast is highly significant and directly proportional to the amount of unfavourable tissue change. Absolute minimal contact (O.O ­ .25 mm of cast scraping) produces nochange. When the cast scraping was increased to 1 mm, tissue changes were produced varying from mild inflammation to acute ulceration. www.indiandentalacademy.com
  • 103.    5. Joseph Clayton in 1970 did a study to compare the surface roughness, following final finishing and polishing, of pontics constructed from cast gold, acrylic resin and glazed porcelain. With a profilometer statistical analysis indicated that the test surfaces of glazed porcelain were significantly rougher than the polished test surfaces of acrylic resin or cast gold. There was no significant difference in surface roughness between the polished acrylic resin and polished cast gold sample pontic surfaces. Clinical test showed that plaque formation occurred on polished surfaces of pontics constructed of cast gold, acrylic resin and glazed porcelain. The surfaces of these pontics were as smooth as the sample pontics which were measured in this study. Therefore pontic surfaces which are as smooth as possible must be cleaned regularly to prevent the www.indiandentalacademy.com accumulation of dental plague.
  • 104. 6. Martin Henry Berman in 1973 did a study on the interrelationship between complete coverage restoration and the gingival sulcus. The terminal margin plays an important role in maintaining gingival health. perio­dontal disease is minimal with restorations which do not invade the sulcus, but the caries attack rate, retention and esthetic requirements may compel entry into the sulcus. The technique described in this report permits entry into the sulcus with permanent damaging. 7. Dayton Krajicek in 1973 presented a paper on periodontal consideration in prosthetic patients. He mentions that Crown contours should be adequate to deflect food and contoured gradually so as to permit clearing and to avoid forming a food trap. Margins should be placed supragingivally as far as possible. www.indiandentalacademy.com
  • 105.  8. William A Richter in 1973 did a study in the influence of Crown­margin location on the gingival tissue for 12 cast complete crown. Evaluation were made yearly upto three years.To avoid significant variables, each of the 12 crowns was designed with both sub gingival and supra gingival margins on the gingival margins of facial surface. A comparison of the two margins location using four different methods of evaluation revealed no difference in the 1) health of the gingiva, 2) change in sulcus depth, 3) gingival contour and 4) plague accumulation. In view of reported gingival problems near restoration margins, the result of this study suggest that the fit and finish of full crown restorations may be more significant to gingival health than the location of finish lines. www.indiandentalacademy.com
  • 106. 9.Dominick C. Larato in 1975 did a study on margin extension, brushing and gingival pocket depth. A total of 111 males vetern patients ranging in age 21­ 73 years were selected for the study. Each had at least one tooth which was restored with a complete cast gold veneer crown and a non­restored contralateral tooth with no clinical or radiographic evidence of cervical caries. All artificial crowns had sub gingival margins. The gingival tissues adjacent to the crown and unrestored teeth were probed to determine individual pocket depths. www.indiandentalacademy.com
  • 107. The results are ­ 1. The average pocket depth adjacent to non­ restored teeth was.2.7mm. The average pocket depth adjacent to teeth having crowns will sub gingival margins was 3.4mm. 2.54 non­restored teeth had at least one pocket depth greater than 3mm while 84 crowned teeth had at least one or more measurements greater than 3 mm. 3. No positive relationship could be found between tooth brushing frequency and the pocket depth adjacent to teeth restored with complete cast crowns. 4. In non­restored teeth pocket depth increased with reduced frequency of non­ brushing. www.indiandentalacademy.com
  • 108. 10.Francisco Palomo and John Pedar in 1976 did a study on periodontal relationship with regards 1. Placement of margins, 2. Marginal fit, 3. Inter dental space and contour of restorations and 4. Surface texture 11. Jan Ruel, Peter Schrussler, Kenneth Malament in 1980 did a study on the effect of retraction procedures on the periodontium in humans. On basis of wound healing and gingival recession caused by the cord, electro surgery and copper band, the copper band ret­ raction method was the most satisfactory. Retraction methods must be evaluated relative to the impression procedure and fit of the restoration. www.indiandentalacademy.com
  • 109. 12. Curtis M. Beker and Wayne Kaldanl in 1981 suggested that crown contours which promote favourable tissue response follow these guidelines a) Buccal and lingual contours should be flat, b) Embrasure spaces should be kept open, c) Contact should be high (incisal 1/3 and buccal to central fossa (except between first and second molars) d) Margins should be supra gingival wherever possible. The pontic design of choice is the modified ridge lap for posteriors and ridge lap for anteriors. www.indiandentalacademy.com
  • 110. 13) Lee M. Jamson and William Malane in 1982 did a study on crown contours and gingival response.The conclusions drawn were 1) Deflective contours and or over contouring should be avoided in the cervical third and the inter­proxinial surfaces of tooth restorations. 2) Over contouring of the inter proximal region is common and harmful to periodontal health. 3) Adequate tooth reduction at the gingival margins and inter proximally provides for restoration materials and lessens the potential for overcontouring in these critical regions. 4) Minimal disruption with the intra crevicular space sheering tooth preparation allows a more predictable, favourable periodontal response to satisfactorily contoured restorations. www.indiandentalacademy.com
  • 111. 14) David L Kath in 1982 did a study on full crown restorations and gingival inflammation in a controlled population. The amount of the crevicular fluid around full crown restoration was measured with an instrument to compare the gingival inflammation between restored and unrestored teeth in the same patient. 38 full crown restorations were compared to non restored teeth used as controls in 26 patients. The results were as follows:­ 1. Full crowns have the potential for causing gingival inflammation. However, not so in a highly motivated patient. 2. Gingival inflammation surrounding full crown resto­ rations may be controlled regardless of gingival margin placement when the gingiva is healthy and restorations are adequate and the patient is in a strict recall programme. www.indiandentalacademy.com
  • 112. 15) John Soumson, Micheal Rewman and Thomas Fleming in 1991 did a study assessing the efficacy of a 12%chlorhexidene gluconate rinse on the enhancement and maintenance of gingival health in patients receiving fixed prosthesis. Adjunctive use of chlorhexidine with F.P.D. significantly reduced plague levels and improved gingival health compared and controlled patients. 16) Martin Treelich, Lary C Breeding et al in 1991 did a study testing the effect of fixed partial dentures on hypermobile abutment teeth with substantially reduced levels of periodontal attachment. One abutment tooth and one control (non­abutment) tooth of the same type and periodontal condition were selected for study in adults. Treatment consisted of periodontal therapy and a 3 or 4 unit F.P.D. after which all subjects were placed on a quarterly maintenance schedule. No differences were found between the mean baseline and 24 month measures for all dependent variables at test or control sites. www.indiandentalacademy.com
  • 113. 17) Martin a Treilhich, Christin Mekrash, Katx et al in 1992 studied the periodontal response to posterior fixed partial denture relevant with different marginal configurations and locations. One posterior proximal site restored with a clinically acceptable F.P.D. and one matched, unrestored posterior proximal site were examined in 60 patients. Statistical analysis showed that clinically acceptable F.P.D.'s which had clinically detectable deviation from an ideal (flat) retainer/tooth configuration were not associated with increased probing depths, nor were the sub gingival retainer margins to the supragingival retainer margins. These findings suggest that long­term exposure to variations of F.P.D. margin configuration and location, within clinically acceptable but less than ideal parameters are not associated with destruction of supporting periodontal tissues. www.indiandentalacademy.com
  • 114. REFERENCES 1. Gengers, Snack, Vagels ­ Over containing in resin bonded prosthesis Plague accumulation and gingival health J.P.D. 59:17:Jan 88. 2. Cuetis Becker, Wayne Kaldaht: Current theories of crown contour margin placement and pontic design J.P.D. ­ 45:268:1981. 3. Dayton K Periodontal considerations for prosthetic patients J.P.D. 30:15:July73. 4. DominickC.L. Effect of artificial crown margin extensions and tooth brushing frequency on gingival pocket depth. 5. David Koth: Full crown preparation and gingival inflammation in a controlled population. J.P.D. 48:681:1982. 6. Edmand C: Tissue response to fixed partial denture prosthesis. J.P.D. 23:407:1970. 7. Francisco P. John pedar, Periodontal relationship and F.P.D. J.P.D. 387:36:1976. www.indiandentalacademy.com
  • 115. 8. James Marcum: The effect of crown marginal depth upon gingival tissues J.P.D. 17:479:1967. 9. Jon Ruel, Peter S., Keneth M: Effect of retraction procedures on periodontium in humans J.P.D. 44:508:1980. 10. John Lorensonl6, Micheal N. Gingival enhancement in F.P.D. 65:100­107:1991. 11. Joseph Clayton: Roughness of pontic materials and dental plague ­ J.P.D. 23:407:1970. 12. Lee M. Jamson,William M: Crown contains and gingival response J.P.D. 47:620:1982. 13. Martin Bermar. The complete coverage restoration and the gingival sulcus ­ J.P.D.: 29:301:1973. 14. Martin Frelich, Lasy c.: F.P.D. supported by periodontally compromised teeth ­ J.P.D.65:607:1991. 15. Martin Frelich, C. Riekrash: Periodontal effects of F.P.D. retainer margins: configurment and location J.P.D. 67:184:1992.www.indiandentalacademy.com
  • 116. 16. Melvin L. Mories Artificial crown contours and gingival health J.P.D. 12:l146:Dec.'62. 17. Sheldan Stein: pontic residual ridge relationship: A report­ J.P.D:16:251:1966. 18. William Richter, Veno: Relationship of crown margin placement to gingival inflammation ­ J.P.D.30:156:1973. 19.Contemporary fixed prosthodontics – Rosenstiel. 20.Fundamentals of fixed prosthodontics – Shillingburg. 21.Clinical periodontology – Carranza 22. Tylman’s theory and practise of fixed prosthodontics. www.indiandentalacademy.com
  • 117. www.indiandentalacademy.com