seminar 7 diag and rx planning in fpd pptx.pptx

Diagnosis and treatment planning in FPD

1. SEMINAR 15/09/23 -Melisa cheriyan 2 nd year postgraduate 1

2. DIAGNOSIS AND TREATMENT PLANNING IN FPD 2

3. CONTENTS INTRODUCTION DEFINITIONS HISTORY TAKING CHIEF COMPLAINT GENERAL MEDICAL HISTORY DENTAL HISTORY CLINICAL EXAMINATION EXTRA ORAL EXAMINATIONS INTRAORAL EXAMINATIONS DIAGNOSTIC CASTS 3

4. TREATMENT PLANNING FOR SINGLE TOOTH RESTORATIONS FOR REPLACEMENT OF SINGLE TOOTH FOR THE REPLACEMENT OF SEVERAL MISSING TEETH BIOMECHANICAL CONSIDERATIONS IN FPD CONCLUSION REFERENCES 4

5. INTRODUCTION 5

6. Fixed prosthodontic treatment involves the replacement and restoration of teeth by artificial substitutes that are not readily removable from the mouth. Its focus is to restore function, esthetics , and comfort. Fixed prosthodontics can offer exceptional satisfaction for both patient and dentist. 6

7. It can transform an unhealthy, unattractive dentition with poor function into a comfortable, healthy occlusion capable of years of further service while greatly enhancing esthetics . 7

8. A crown is an artificial restoration of the entire coronal portion of a natural tooth, of which it becomes an integral part. A fixed bridge or fixed partial denture is a restoration which cannot be readily removed by the patient or dentist; it is permanently attached to natural teeth or roots which furnish the primary support to the appliance. A pontic is the suspended member of a fixed partial denture or bridge; it replaces the lost natural tooth, restores its functions, and usually occupies the space previously filled by the natural crown. 8 According to Tylman

9. A retainer is that part of a dental bridge which unites the abutment tooth with the suspended portion of the bridge A connector is that part of a dental bridge which unites the retainer with the pontic . An abutment is the terminal tooth or root which retains or supports the bridge; it is united to the bridge proper by means of the retainer. 9

10. Diagnosis : the determination of the nature of a disease. – GPT 9 Prognosis : a forecast as to the probable result of a disease or a course of therapy. – GPT 9 Treatment plan : the sequence of procedures planned for the treatment of a patient after diagnosis. – GPT 9 10

11. HISTORY TAKING 11

12. Problems encountered during or after treatment can often be traced to errors and omissions during history taking and initial examination. Making the correct diagnosis is prerequisite for formulating an appropriate treatment plan. All pertinent information must be obtained. A complete history includes a comprehensive assessment of the patient’s general and dental health, individual needs, preferences, and personal circumstances 12

13. CHIEF COMPLAINT 13

14. The accuracy and significance of the patient’s primary reason or reasons for seeking treatment should be analyzed first. 14

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16. COMFORT If pain is present, its location, character, severity, and frequency should be noted, as well as the first time it occurred, what factors precipitate it (e.g., pressure, hot, cold, or sweet things), any changes in its character, and whether it is localized or more diffuse in nature. 16

17. FUNCTION Difficulties in chewing may result from a local problem such as a fractured cusp or missing teeth; they may also indicate a more generalized malocclusion or neuromuscular dysfunction. 17

18. SOCIAL ASPECTS A bad taste or smell often indicates compromised oral hygiene and periodontal disease. Social pressures prompt many affected patients to seek care. 18

19. APPEARANCE Compromised appearance is a strong motivating factor for patients to seek advice as to whether improvement is possible . 19

20. HISTORY 20

21. GENERAL MEDICAL HISTORY 21 E,g , Any disorders that necessitate the use of antibiotic premedication, any use of steroids or anticoagulants, and any previous allergic responses to medication or dental materials e.g., Previous radiation therapy, hemorrhagic disorders, extremes of age, and terminal illness

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23. DENTAL HISTORY 23

24. PERIODONTAL HISTORY The patient’s oral hygiene is assessed, and current plaque-control measures are discussed, as are previously received oral hygiene instructions. The frequency of any previous debridement should be recorded, and the dates and nature of any previous periodontal surgery should be noted. 24

25. RESTORATIVE HISTORY The patient’s restorative history may include only simple composite resin or dental amalgam fillings, or it may involve crowns and extensive fixed dental prostheses. The age of existing restorations can help establish the prognosis and probable longevity of any future fixed prostheses. 25

26. ENDODONTIC HISTORY Patients often forget which teeth have been endodontically treated. These can be readily identified with radiographs. The findings should be reviewed periodically so that periapical health can be monitored and any recurring lesions promptly detected 26

27. ORTHODONTIC HISTORY On occasion, root resorption (detected on radiographs) may be attributable to previous orthodontic treatment. Because this may affect the crown-to-root ratio, future prosthodontic treatment and its prognosis may also be affected. 27

28. REMOVABLE PROSTHODONTIC HISTORY The patient’s experiences with removable prostheses must be carefully evaluated. For example, a partial removable dental prosthesis may not have been worn for a variety of reasons, and the patient may not even mention its existence. 28

29. ORAL SURGICAL HISTORY The clinician must obtain information about missing teeth and any complications that may have occurred during tooth removal. 29 RADIOGRAPHIC HISTORY Previously made radiographs may prove helpful in judging the progress of dental disease. They should be obtained if possible.

30. TEMPOROMANDIBULAR JOINT DYSFUNCTION HISTORY Myofascial pain, clicking in the temporomandibular joints (TMJs), or neuromuscular symptoms, such as abnormal muscle tone or tenderness to palpation, should be treated and resolved before fixed prosthodontic treatment begins. 30

31. CLINICAL EXAMINATION 31

32. GENERAL EXAMINATION General appearance, gait, and weight are assessed. Skin color is noted, and vital signs, such as respiration, pulse, temperature, and blood pressure, are measured and recorded. 32

33. TYPE OF PATIENT Generally, the teeth of a powerfully built man are stronger than those of a dainty, frail woman. Likewise, the tissue vitality, on the average, is better in the robust type of patient than in the frail. 33

34. PERSONAL HYGIENE The personal hygiene of a patient often determines the type of prosthesis to be employed. Unless mouth hygiene is rigidly pursued, the most perfectly constructed and sanitary type of fixed partial denture will soon fail. 34

35. OCCUPATION OF PATIENT For those patients whose clarity of speech or voice is a prime consideration, the appliance must be designed to meet these specifications. 35

36. EXTRAORAL EXAMINATION 36

37. Facial factors 37

38. FORM AND COLOR HARMONY Appliance that the dentist makes for the patient must conform to identical standards in order to preserve the harmonious effect. This is one of the reasons why the entire responsibility of designing and constructing an appliance cannot be left to a dental technician, for he does not have the opportunity of relating his technical work with the esthetic requirements of the patient. 38

39. FACIAL FORM 39 Madame Schimmelpennick divided face forms into

40. 40 Dr. J. Leon Williams reclassified faces into three general groups :

41. EYES The eyes should be noted, since the color of the eyes is closely related to that of the teeth. The eyes may reveal the presence of certain systemic diseases. 41

42. LIPS The patient is observed for tooth visibility during normal and exaggerated smiling. This can be critical in the planning of fixed prosthodontic treatment, especially when the need to fabricate crowns or fixed dental prostheses is anticipated in the esthetic zone. 42

43. It is important to check the position which the lip assumes during speech, laughter, or repose. If the upper lip line is low, the pontics of an upper fixed bridge may be narrowed in the gingival area for hygienic purposes. If, however, the lip line is high, thereby exposing the gingival line of the pontics during function, it will necessitate the construction of a different shape of pontic . 43

44. 44

45. Temporomandibular joints 45

46. The clinician locates the TMJs by palpating bilaterally just anterior to the auricular tragi while the patient opens and closes the mouth. This enables a comparison between the relative timing of left and right condylar movements during the opening stroke. 46

47. 47

48. Asynchronous movement may indicate a disk displacement that prevents one of the condyles from making a normal translatory movement. Auricular palpation with light anterior pressure helps identify potential disorders in the posterior attachment of the disk . Tenderness or pain on movement is noted and can be indicative of inflammatory changes in the retrodiscal tissues , which are highly vascular and innervated. 48

49. 49 Such restricted movement on opening can be indicative of intracapsular changes in the joints .

50. MUSCLES OF MASTICATION 50

51. 51

52. INTRAORAL EXAMINATION 52

53. GINGIVA The gingiva is dried for the examination so that moisture does not obscure subtle changes or detail. Color , texture, size, contour, consistency, and position are noted. 53

54. GINGIVAL BIOTYPE IN PROSTHODONTICS Tooth preparation : Margins of the preparation have to be placed supragingivally in thin biotypes. If margins are placed subgingivally for porcelain fused to metal restoration grayish discoloration of the margin is seen because of translucency of thin biotype, which leads to esthetic failure. Whereas in thick biotypes margins can be placed subgingivally in esthetic zones. Over contoured restorations will lead to gingival recession in thin biotypes. Pocket formation is seen in thick biotype. 54 Nagaraj KR, Savadi RC, Savadi AR, Prashanth Reddy GT, Srilakshmi J, Dayalan M, John J. Gingival biotype - Prosthodontic perspective. J Indian Prosthodont Soc. 2010 Mar;10(1):27-30.

55. Gingival retraction : Care to be taken to avoid injury to the soft tissue in thin biotypes. Thin retraction cord is used for retraction. If cord is retained more than 15 minutes, chances of recession are more. Retraction of gingiva can be accomplished more comfortably in thick biotype. 55 Nagaraj KR, Savadi RC, Savadi AR, Prashanth Reddy GT, Srilakshmi J, Dayalan M, John J. Gingival biotype - Prosthodontic perspective. J Indian Prosthodont Soc. 2010 Mar;10(1):27-30.

56. Prostheses should be carefully designed and performed, in harmony with the surrounding periodontium, to maintain periodontal/ peri-implant health. Defective restorations contribute to disease progression by increasing accumulation of dental plaque and retention of food debris. Adequate crown contours could provide protection of gingival margins, allow cleansing action of the musculature and facilitate the access for oral hygiene. Indeed, overcontour may have negative influence on periodontium since it increases plaque retention 56 Yung-Ting Hsu, Relationship Between Periodontics and Prosthodontics: The Two-Way Street, Journal of Prosthodontics and Implantology, 2015 PERIODONTIUM

57. Simple opening and closing movements, which the clinician carefully observes. The objective is to determine to what extent the patient’s occlusion differs from the ideal and how well the patient has adapted to any difference that may exist. Special attention is given to initial contact , tooth alignment , eccentric occlusal contacts , and jaw maneuverability . 57 OCCLUSAL EXAMINATION

58. INTIAL TOOTH CONTACT The clinician should ask the patient to “close feather- light” until any of the teeth touch and to have the patient help identify where that initial contact occurs by asking him or her to point at the location. Any discrepancy between CR and MI should be evaluated in the context of other signs and symptoms that may be present 58

59. GENERAL ALIGNMENT Any crowding, rotation, supra- eruption, spacing, malocclusion, and vertical and horizontal overlap are recorded 59

60. LATERAL AND PROTRUSIVE CONTACT The degree of vertical and horizontal overlap of the teeth is noted. When asked, most patients are capable of making an unguided protrusive movement. During this movement, the degree of posterior disclusion that results from the overlaps of the anterior teeth is observed. Excursive contacts on posterior teeth may be undesirable The patient is then guided into lateral excursive movements, and the presence or absence of contacts on the nonworking side and then the working side is noted 60

61. JAW MANEUVERABILITY The ease with which the patient moves the jaw and the way the mandible can be guided through hinge closure and excursive movements should be evaluated because this information is useful for assessing neuromuscular and masticatory function. 61

62. RADIOGRAPHIC EXAMINATION Digital radiographs provide essential information to supplement the clinical examination Panoramic films provide useful information about the presence or absence of teeth. They are especially helpful in assessing third molars and impactions, evaluating the bone before implant placement 62

63. DIAGNOSTIC CASTS 63

64. Accurate diagnostic casts transferred to a semiadjustable articulator are essential in planning fixed prosthodontic treatment. This enables examination of static and dynamic relationships of the teeth without interference from protective neuromuscular reflexes, and unencumbered views from all directions reveal aspects of the occlusion not always easily detectable intraorally 64

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66. Prosthodontic Diagnostic Index (PDI) for Partially Edentulous and Completely Dentate Patients Potential benefits of the system include (1) improved intraoperator consistency, (2) improved professional communication, (3) insurance reimburse- ment commensurate with complexity of care, (4) improved screening tool for dental school admission clinics, (5) standardized criteria for outcomes assessment and research, (6) enhanced diagnostic consistency, and (7) simplified decision to refer a patient. 66

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68. CLASS 1 This class is characterized by ideal or minimal compromise in the location and extent of an edentulous area (which is confined to a single arch), abutment conditions, occlusal characteristics, and residual ridge conditions. All four of the diagnostic criteria are favorable . 68

69. CLASS 2 This class is characterized by mod- erately compromised location and extent of edentulous areas in both arches, abutment conditions that necessitate localized adjunctive therapy, occlusal characteristics that necessitate localized adjunctive therapy, and residual ridge conditions. 69

70. CLASS 3 This class is characterized by substantially compromised location and extent of edentulous areas in both arches, abutment condition that necessitates substantial localized adjunctive therapy, occlusal characteristics that necessitate reestablishment of the entire occlusion without a change in the occlusal vertical dimension, and residual ridge conditions. 70

71. CLASS 4 This class is characterized by severely compromised location and extent of edentulous areas with guarded prognosis, abutment conditions that necessitate extensive therapy, occlusion characteristics that necessitate reestablishment of the occlusion with a change in the occlusal vertical dimension, and residual ridge conditions. 71

72. TREATMENT PLANNING 72

73. Treatment planning consists of developing a logical sequence of treatment designed to restore the patient’s dentition to good health, optimal function, and optimal appearance. The plan should be presented in writing and discussed in detail with the patient. Good communication with the patient is critical as the plan is formulated. 73

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75. Treatment planning for single tooth restorations 75

76. 76 The selection of the material and design of the restoration is based on several factors

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78. INTRACORONAL RESTORATIONS Glass ionomer cement Small lesions where extensions can be kept minimal and where preparation retention will be minimal can be restored with this material. It is useful for restoring class 5 lesions caused by erosion or abrasion Glass ionomer has found a niche in the restoration of root caries in geriatric and periodontal patients 78

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80. Composite resins Esthetically critical areas Usually used to treat class 3 and class 5 lesions 80

81. Simple amalgam The simple amalgam, without pins or other means of auxiliary retention, for decades has been the standard one- to three-surface restoration for minor- to moderate-sized lesions in esthetically noncritical areas. Approximately 100 million or more simple amalgam restorations are placed annually. 81

82. Complex amalgam Amalgam augmented by pins or other auxiliary means of retention can be used to restore teeth with moderate to severe lesions in which less than half of the coronal dentin remains Amalgam used in this manner can be employed as a final restoration when a crown is contraindicated because of limited finances or poor oral hygiene. 82

83. Metal inlay Minor to moderate lesions on teeth where the esthetic requirements are low can be restored with this restoration type The indications for this type of restoration are much the same as those for an amalgam, since this restoration only replaces lost tooth structure and will not protect remaining tooth structure 83

84. Ceramic inlay This restoration is utilized to restore teeth with minor- to moderate-sized lesions that will permit a narrow preparation isthmus in an area of the mouth where the esthetic demand is high. 84

85. MOD onlay This design can be used for restoring moderately large lesions on premolars and molars with intact facial and lingual surfaces. It will accommodate a wide isthmus and up to one missing cusp on a molar. 85

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87. EXTRACORONAL RESTORATIONS 87

88. Full Metal Crown The conventional full crown can be used to restore teeth with multiple defective axial surfaces. It will provide the maximum retention possible in any given situation, but its use must be restricted to situations where there are no esthetic expectations. This will usually limit it to second molars, some mandibular first molars, and occasionally mandibular second premolars. 88

89. Metal-Ceramic Crown This crown can also be used to restore teeth with multiple defective axial surfaces It too is capable of providing maximum retention, but it also will meet high esthetic requirements. It can be used as a fixed partia l denture retainer where full coverage and a good cosmetic result must be combined. 89

90. All-Ceramic Crown When full coverage and maximum esthetics must be combined, this crown is the choice. All-ceramic crowns are not as resistant to fracture as metal-ceramic crowns, so their use must be restricted to situations likely to produce low to moderate stress. They are usually used for incisors. 90

91. Ceramic Veneer This restoration also can be used to restore moderate incisal chipping The use of a veneer requires only a minimum tooth preparation, so it offers an alternative to crowns that is attractive to patient and dentist alike 91

92. Replacement of a Single Missing Tooth 92

93. Single missing tooth can almost always be replaced by a three-unit FPD that includes one mesial and one distal abutment tooth. 93

94. Cantilever Fixed Dental Prostheses FPDs in which only one side of the pontic is attached to a retainer are referred to as cantilevered. An example would be a lateral incisor pontic attached only to an extracoronal metal-ceramic retainer on a canine tooth 94

95. Evaluation of Abutment Teeth Radiographs are made Pulpal health by evaluating the response to thermal or electrical stimulation Teeth in which pulpal health is doubtful should be treated endodontically before fixed prosthodontic treatment is initiated 95

96. Endodontically Treated Abutments If a tooth is properly treated endodontically, it can serve well as an abutment with a post and core foundation for retention and strength. 96

97. Unrestored Abutments An unrestored, caries-free tooth is an ideal abutment. It can be prepared conservatively for a strong retentive restoration with optimum esthetics . In an adult patient, an unrestored tooth can be safely prepared without jeopardizing the pulp as long as preparation design and technique are wisely chosen. 97

98. Mesially Tilted Second Molar Loss of a permanent mandibular first molar to caries early in life is still relatively common In such cases mandibular second molar may drift mesially and makes it impossible to make a satisfactory FPD because the positional relationship no longer allows for parallel paths of placement without interference from the adjacent teeth. 98

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100. Replacement of a Several Missing Teeth 100

101. OVERLOADING OF ABUTMENT TEETH The ability of the abutment teeth to accept applied forces without drifting or becoming mobile must be estimated and has a direct influence on the prosthodontic treatment plan. These forces can be particularly severe during parafunctional grinding and clenching, and the need to eliminate them becomes obvious during the restoration. 101

102. DIRECTION OF FORCES The magnitude of any applied force is difficult to regulate, a well-fabricated FPD can distribute these forces in the most favorable way: namely, directing them along the long axes of the abutment teeth. 102

103. ROOT SURFACE AREA “the total periodontal membrane area of the abutment teeth must equal or exceed that of the teeth to be replaced ”- Ante’s law 1926 The root surface area of potential abutment teeth must be evaluated when fixed prosthodontic treatment is planned 103

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105. ROOT SHAPE AND ANGULATION A molar with divergent roots provides better support than does a molar with conical roots and little or no interradicular bone. A single-rooted tooth with an elliptic cross section offers better support than does a tooth with similar root surface area but with a circular cross section. Similarly, a well- aligned tooth provides better support than a tilted one 105

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107. PERIODONTAL DISEASE Successful FPDs can be fabricated on teeth with severely reduced periodontal support if the periodontal tissues have been returned to excellent health and long-term maintenance has been ensured. When extensive prosthetic rehabilitation is attempted without complete control over the health of the periodontal tissues, the results can be disastrous. Healthy periodontal tissues are a prerequisite for all fixed restorations 107

108. SPAN LENGTH Excessive flexing under occlusal loads may cause failure of a long-span FPD. It can lead to fracture of a porcelain veneer, breakage of a connector, loosening of a retainer, or an unfavorable soft tissue response and thus render a prosthesis useless. All FPDs flex slightly when subjected to a load; the longer the span, the greater the flexing. 108

109. When anterior teeth are replaced, special considerations include problems with appearance The four mandibular incisors can usually be replaced by a simple FPD with retainers on each canine tooth. It is not usually necessary to include the first premolars 109 REPLACING MULTIPLE ANTERIOR TEETH

110. Unlike the mandibular incisors, the maxillary incisors are not positioned in a straight line (particularly in patients with narrow or pointed dental arches). These tipping forces must be resisted by means of additional abutment teeth at each end of a long-span anterior FPD. Thus in general, when the four maxillary incisors are replaced, the canine teeth and first premolars should be used as abutment teeth. 110

111. BIOMECHANICAL CONSIDERATIONS 111

112. Compared with a fixed partial denture having a single- tooth pontic span, a two-tooth pontic span will bend 8 times as much. A three-tooth pontic will bend 27 times as much as a single pontic . To minimize flexing caused by long and/or thin spans, pontic designs with a greater occlusogingival dimension should be selected. The prosthesis may also be fabricated of an alloy with a higher yield strength, such as nickel-chromium. 112

113. Double abutments are sometimes used as a means of overcoming problems created by unfavorable crown-root ratios and long spans. 113

114. Arch curvature has its effect on the stresses occurring in a fixed partial denture. When pontics lie outside the interabutment axis line, the pontics act as a lever arm, which can produce a torquing movement. This is a common problem in replacing all four maxillary incisors with a fixed partial denture, and it is most pronounced in the arch that is pointed in the anterior. Some measure must be taken to offset the torque 114

115. CONTENTS INTRODUCTION DEFINITIONS HISTORY TAKING CHIEF COMPLAINT GENERAL MEDICAL HISTORY DENTAL HISTORY CLINICAL EXAMINATION EXTRA ORAL EXAMINATIONS INTRAORAL EXAMINATIONS DIAGNOSTIC CASTS 115

116. TREATMENT PLANNING FOR SINGLE TOOTH RESTORATIONS FOR REPLACEMENT OF SINGLE TOOTH FOR THE REPLACEMENT OF SEVERAL MISSING TEETH 116

117. ABUTMENT SELECTION IN FPD SPECIAL CASES Tilted abutments Cantilever abutments Pier abutments COMPLEX FPDs RESIN BONDED FPD CONCLUSION REFERENCE 117

118. ABUTMENT SELECTION 118

119. Crown length Taller the crown, more the torsional load; so more stress is expected on the abutments. Hence pontics with increased occluso -gingival height will require additional abutments If the abutment teeth have less than 4mm of crown structure additional support by splinting multiple abutment teeth may be required 119

120. Crown form If the pontics have a larger occlusal table than the abutment teeth then additional abutments may be required to evenly distribute the load. 120

121. Crown-root ratio The root support should be greater than the crown height. Ideally the crown-root ratio should be 2:3 The least accepted crown root ratio is 1:1 121

122. Ante's law In 1926, Irwin H.Ante made a statement which was popularised as "Ante's Law" by Johnston in 1971. According to Ante, the total pericemental area of the abutment teeth should be equal to or greater than the pericemental area of the missing teeth If the pericemental area of the abutment teeth were less then additional abutments were chosen to provide support. 122

123. 123

124. Axial alignment The term axial alignment refers to the alignment of the long axis of the abutment teeth to each other. 124

125. Tilted molar abutments: Selecting mandibular molar abutments is more challenging because they are often mesially tilted. There are common methods that can be used to manage a tilted molar as abutment tooth for FPD 125

126. Mesial half crowns This preparation design is simply a three-quarter crown that has been rotated 90 degrees so that the distal surface is uncovered. This retainer can be used only if the distal surface itself is untouched by caries or decalcification and if there is a very low incidence of proximal caries throughout the mouth. 126

127. Telescopic crowns A full crown preparation with heavy reduction is made to follow the long axis of the tilted molar. An inner coping is made to fit the tooth preparation, and the proximal half crown that will serve as the retainer for the fixed partial denture is fitted over the coping This restoration allows for total coverage of the clinical crown while compensating for the discrepancy between the paths of insertion of the abutments. 127

128. Non rigid connectors A full crown preparation is done on the molar, with its path of insertion parallel with the long axis of that tilted tooth. A box form is placed in the distal surface of the premolar to accommodate keyway in the distal of the premolar crown. 128

129. 129

130. Arch form Arch curvature has its effect on the stresses occurring in a fixed partial denture. This is a common problem in replacing all four maxillary incisors with a fixed partial denture, and it is most pronounced in the arch that is pointed in the anterior . 130

131. Acutely curved arches require additional abutment teeth to dissipate the lateral stresses occurring in two directions at the region of curvature. 131

132. Alveolar ridge form Wide ridges are ideal for FPD Thin and low ridges due to severe resorption increase the pontic height and increase torsional loads on the abutment teeth. 132

133. Mobility Teeth with firm periodontal support are ideal abutments In case the abutment tooth has grade 1 mobility it can be splinted with additional abutments for support Teeth with grade 2 mobility are contraindicated as abutments for FPD 133

134. Periodontal health Periodontally compromised teeth should not be selected as abutments for FPDs. If the tooth had bone loss but the periodontal condition is stabilised and it is not mobile, then it can be used as an abutment 134

135. Pulpal health FPD abutments should preferably be vital teeth to have better proprioception. 135

136. Root length and form Longer roots like the canine teeth are excellent abutments. Anterior teeth have triangular roots and can withstand lateral loads whereas posterior teeth have cylindrical roots that can take up vertical loads. Curved roots offer better anchorage and may serve as better abutments 136

137. Occlusion Based on each scheme of occlusion, the abutment can be selected. For FPDs with mutually protected occlusion, minimal lateral load is expected and so a single abutment should be sufficient on either side. If group function is planned and if the patient has para-functional habits, it may be advisable to have a secondary abutment splinted to the FPD to improve load distribution. 137

138. Span length 138

139. Special cases 139

140. PIER ABUTMENT Rigid connectors ( eg , solder joints) between pontics and retainers are the preferred way of fabricating most fixed partial dentures. A fixed partial denture with the pontic rigidly fixed to the retainers provides desirable strength and stability to the prosthesis while minimizing the stresses associated with the restoration. 140

141. 141

142. It has been theorized that forces are transmitted to the terminal retainers as a result of the middle abutment acting as a fulcrum leading to failure of the retainer 142

143. The use of a nonrigid connector has been recommended to reduce this hazard. The nonrigid connector is a broken-stress mechanical union of retainer and pontic , instead of the usual rigid connector The most commonly used nonrigid design consists of a T-shaped key that is attached to the pontic , and a dovetail keyway placed within a retainer 143

144. A nonrigid fixed partial denture transfers shear stress to supporting bone rather than concentrating it in the connectors. It appears to minimize mesiodistal torquing of the abutments while permitting them to move independently 144

145. The location of the stress-breaking device in the five- unit pier-abutment restoration is important. It usually is placed on the middle abutment, since placement of it on either of the terminal abutments could result in the pontic acting as a lever arm. The keyway of the connector should be placed within the normal distal contours of the pier abutment, and the key should be placed on the mesial side of the distal pontic . 145

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147. TILTED MOLAR ABUTMENT 147

148. CANTILEVER FIXED PARTIAL DENTURES A cantilever fixed partial denture is one that has an abutment or abutments at one end only, with the other end of the pontic remaining unattached. 148

149. 149

150. Abutment teeth for cantilever fixed partial dentures should have 150 A cantilever can be used for replacing a maxillary lateral incisor

151. A cantilever pontic can also be used to replace a missing premolar. This scheme will work best if occlusal contact is limited to the distal fossa. The teeth must exhibit excellent bone support. 151

152. Complex FPDs 152

153. ONE TOOTH 153

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155. TWO TEETH 155

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157. PIER ABUTMENTS 157

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161. Resin bonded FPDs 161

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163. MECHANISM Retention in these prostheses relies on the adhesive bonding between etched enamel and the metal casting (retainer) They are held in place by resin which lock mechanically into: Microscopic undercuts on etched enamel Undercut present in the casting 163

164. INDICATION 164

165. CONTRAINDICATION Insufficient occlusal clearance Thin anterior teeth faciolingually Short clinical crowns Deep vertical overlap Parafunctional habits Long span bridges Insufficient enamel available for bonding :caries, restorations. 165

166. CLASSIFICATION Based on the technique used to finish the tissue surface of the retainer, resin bond fixed partial denture can be classified as Rochette bridge (Mechanical) Maryland bridge (Micromechanical) Cast Mesh Virginia bridges ( Macromechanical ) 166

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168. CONCLUSION A comprehensive history and a thorough clinical examination provide sufficient data for the practitioner to formulate a successful treatment plan. If they are too hastily accomplished, details may be missed, which can cause significant problems during treatment, when it may be difficult or impossible to make corrections. Also, the overall outcome and prognosis may be adversely affected. In particular, it is crucial to develop a thorough understanding of each patient’s special concerns relating to previous care and his or her expectations about future treatment 168

169. REFERENCES Fundamentals of fixed prosthodontics, Herbert T Shillingburg - 3 rd edition Theory and practice of crown and bridge prosthodontics, Tylamn – 4 th edition Contemporary fixed prosthodontics, Rosensteil,Land,Fujimoto - 5 th edition 169

170. Nagaraj KR, Savadi RC, Savadi AR, Prashanth Reddy GT, Srilakshmi J, Dayalan M, John J. Gingival biotype - Prosthodontic perspective. J Indian Prosthodont Soc. 2010. Yung-Ting Hsu, Relationship Between Periodontics and Prosthodontics: The Two-Way Street, Journal of Prosthodontics and Implantology, 2015. 170

171. 171 THANKYOU!

172. Thick gingival biotype Relatively flat soft tissue and bony architecture Dense fibrotic soft tissue Relatively large amount of attached gingiva Thick underlying osseous form Relatively resistant to acute trauma Reacts to disease with pocket formation and infrabony defect formation 172

173. Thin gingival biotype Highly scalloped soft tissue and bony architecture Delicate friable soft tissue Minimal amount of attached gingiva Thin underlying bone characterized by bony dehiscence and fenestration Reacts to insults and disease with gingival recession 173