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Presented by:Dr.m.akouchakian Supervised by: Dr. Mansour Rismanchian And Dr.saied Nosouhian Dental of implantology Dental implants research center Isfahan.

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Presentation on theme: "Presented by:Dr.m.akouchakian Supervised by: Dr. Mansour Rismanchian And Dr.saied Nosouhian Dental of implantology Dental implants research center Isfahan."— Presentation transcript:

1 Presented by:Dr.m.akouchakian Supervised by: Dr. Mansour Rismanchian And Dr.saied Nosouhian Dental of implantology Dental implants research center Isfahan university of mediacal science 1

2 chapter 16 2 m.akouchekian

3 Seventy percent of the dentate population in the United States is missing at least one tooth Single-tooth replacement will most likely comprise a larger percentage of prosthetic dentistry in the future, compared with past generations. 3 m.akouchekian

4 The first molars are the first permanent teeth to erupt in the mouth often the first to decay often play a pivotal role in the maintenance of the arch form and proper occlusal schemes 4 m.akouchekian

5 the adult patient often has had one or more crowns fabricated to restore the integrity of the tooth and replace previous large restorations. Longevity reports of crowns have yielded very disparate results, with the mean life span at failure reported to be 10.3 years. The primary cause of failure of the crown: endodontic therapy porcelain or tooth fracture (or both) uncemented restoration 5 m.akouchekian

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7 insufficient vertical space correction of the occlusal plane and maxillomandibular relationships prosthes Regardless of the treatment selected, the interocclusal space must be assessed carefully. 7 m.akouchekian

8 A common axiom in restorative dentistry : use a fixed prosthesis whenever possible RPDs are usually indicated to replace: 1. three or more posterior teeth 2. a missing canine and two or more adjacent teeth 8 m.akouchekian

9 no reported advantages exist for an RPD replacing one posterior tooth. 9 m.akouchekian

10 the fear of other teeth shifting in the arch the two primary reasons for the patient to consent to wearing the restoration esthetics 10 m.akouchekian

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13 earlier perforated designs exhibited lower survival rates The majority of resin-bonded fixed partial denture (FPO) failure occurs from cement failure survival rates : Max. Ant > mand. Ant > max. Post > mand. post 13 m.akouchekian

14 Selection: economics maintain tooth structure on the abutment teeth transitional restoration 14 m.akouchekian

15 Replace a missing tooth to prevent : tipping,extrusion, increased plaque retention,caries, periodontal disease, and collapse of the integrity of the arch 15 m.akouchekian

16 16 m.akouchekian

17 when the third molar and second molar are the only posterior mandibular teeth missing mandibular second molar is often not replaced 17 m.akouchekian

18 when the third molar is present The mandibular second molar is usually replaced 18 m.akouchekian

19 Disadvantage of not replace a mandibular second molar increased risk of caries, periodontal disease,or both loss of proper interproximal contact with the adjacent tooth extrusion and loss of the maxillary second molar To preven extrusion of the maxillary second molare a crown on the mandibular first molar include an occlusal contact with the mesial marginal ridge of the maxillary second molar the maxillary second molar bonded to the maxillary first molar 19 m.akouchekian

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23 From 1993 to the present time, single-tooth implants have become the most predictable method of tooth replacement. A review of the literature by Goodacre from 1981 to 2003: single-tooth replacement with an implant had the highest implant prosthesis survival rate(97%). 23 m.akouchekian

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25 the longevity of the implant crown has not been adequately determined However, lO-year data clearly indicate an implant and its associated crown has greater survival than an FPD most common complication reported : abutment screw loosening(did not cause the prosthesis or implant to fail) 25 m.akouchekian

26 The consequences of early failure may be greater for a single-tooth implant compared with a three unit fixed prosthesis. the implant failure almost always results in bone loss implant failure: does not compromise the adjacent teeth does not increase the risk of their loss 26 m.akouchekian

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28 Use in esthetic regions during implant healing A removable transitional restoration: load the soft tissue over a bone graft compromise the result and volume of the augmentation cause bone loss, or perhaps even implant failure from the early loading around the implant during Stage I healing depress the interdental papillae of the adjacent teeth 28 m.akouchekian

29 a resin-bonded fixed restoration: replacing teeth in the esthetic zone provide an improved function protect the region In the esthetic zone when bone grafting is necessary Use transitional restoration 29 m.akouchekian

30 Dont use of transitional posterior tooth during bone augmentation and implant healing in a nonesthetic region (mandibular post) overall cost of treatment Short clinical crowns unfavorable occlusal relationships 30 m.akouchekian

31 The most common problem associated with a single tooth is abutment screw loosening 1. an antirotational feature (i.e.,external or internal hex) 2. Accuracy of component fit 3. abutment screw design 4. the number of threads 31 m.akouchekian

32 should be made of titanium alloy to reduce the risk of long-term fracture 4 times more resistant to fracture than grade 1 titanium 2 times as strong as grade 3 titanium functional surface : threaded implant > cylinderical imlplant parallel walled implant > tapered implant 32 m.akouchekian

33 The ideal diameter of a single-tooth implant is dependent on: 1. the mesiodistal dimension of the missing tooth 2. the buccolingual dimension of the implant site 1.5 to 2.0 mm from an adjacent tooth 1.5 mm from the lateral width of the ridge intratooth posterior region: at least 3 mm less than the mesiodistal dimension of the missing tooth (from CEJ to CEJ) 3 mm narrower than the buccolingual dimension of bone 33 m.akouchekian

34 The most ideal posterior tooth to replace with an implant 1. The vertical available bone is usually greater 2. almost always: anterior or below the maxillary sinus (or both) anterior to the mental foramen 3. The bone trajectory for implant insertion is more favorable 34 m.akouchekian

35 maxillary premolars: often in the esthetic zone need for bone grafting is very common Implant placement without bone grafting recessed emergence profile facial ridge lap to the crown does not allow proper hygiene or probing 35 m.akouchekian

36 To ensure a proper esthetic result and to avoid the need for a crown with a ridge lap the implant body is often positioned similar to an anterior implant, under the buccal cusp improves the cervical emergence profile of the maxillary premolar crown 36 m.akouchekian

37 at a distance of 2 mm below the CEJ The natural premolar: root diameter is 4.2 mm consequence most common implant diameter is about 4mm at the crest module. when the mesiodistal space is 7 mm or greater: 1.5 mm of bone on the proximal surfaces adjacent to the natural teeth when the mesiodistal dimension is only 6.5 mm: 3.5-mm implant is suggested 37 m.akouchekian

38 The maxillary canine root is often angled 11 degrees distally and presents a distal curve 32% of the time placed parallel to the canine root, and a shorter second premolar apices may be located over the mandibular neurovascular canal or maxillary sinus: reduced height of bone a shorter implant 38 m.akouchekian

39 Its mesiodistal dimensionusually ranges from 8 to 12 mm The magnified occlusal forces (especially important in parafunction) may cause: bone loss complicate home care Increase abutment screw loosening increase abutment or implant failure because of overload. 39 m.akouchekian

40 Rangert et al: overload-induced bone resorption appeared to precede implant fracture in a significant number of single-molar implant restorations. When possible, a larger-diameter implant should be inserted to enhance the mechanical properties of the implant System: increased surface area stronger resistance to component fracture increased abutment stability enhanced emergence profile for the crown 40 m.akouchekian

41 use of wide-diameter implants: 1. in bone of poor quality 2. for the immediate replacement of failed implant larger-diameter implant: does not require as long an implant Is a benefit in post (anatomical limitations and landmarks, such as the maxillary sinus or mandibular canaI) 41 m.akouchekian

42 When the mesiodistal dimension is 14 mm or greater two 4-mm-diameter implants should be considered Eliminate the mesiodistal offset loads to the prosthesis greater total surface area More stress reduction reduces the incidence of abutment screw loosening 42 m.akouchekian

43 whenever possible, two implants should be used to replace a larger singlemolar space to reduce cantilever loads and abutment screw loosening 43 m.akouchekian

44 subtracting 6 mm: 1.5 mm from each tooth for soft tissue and surgical risk 3 mm between the implants and dividing by 2 44 m.akouchekian

45 When the mesiodistal space is 12 to 14 mm: the treatment plan of choice is less obvious A 5-mm-diameter implant may result in cantilevers up to 5 mm on each marginal ridge of the crown two implants present a greater surgical, prosthetic, and hygiene risk The primary goal is to obtain at least 14 mm of space 45 m.akouchekian

46 Additional space may be gained in several ways: 1. Enamoplasty of the adjacent teeth's proximal contours 2. Orthodontics to upright a tilted Second molar 46 m.akouchekian

47 3. one implant is placed buccal and the other on a diagonal toward the lingual increases the mesiodistal space by 0.5 to 1.0 mm 47 m.akouchekian

48 In the mandible: Ant. implant is placed to the lingual distal implant is placed to the facial access of a floss threader from the vestibule into the intrairmplant space occlusal contacts on the central fossa of buccal aspect of the mesial implant 48 m.akouchekian

49 In the maxilla: anterior implant is placed to the buccal distal implant to the palatal region, to improve the esthetics distal occlusal contact is Placed over the lingual cusp mesial occlusal contact is located in the central fossa access of a floss threader from the palatal 49 m.akouchekian

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52 is often the most difficult procedure to perform in all of implant dentistry highly esthetic zone requires both hard (bone and teeth) and soft tissue restoration The soft tissue drape is often the most difficult aspect of treatment 52 m.akouchekian

53 53 m.akouchekian

54 can be fabricated in shorter time is more predictable in the short term often satisfies the criteria of normal contour, comfort,function, esthetics, speech, and health However, 7-to 9-year survival estimates for a three-unit FPO are often less than 75% 54 m.akouchekian

55 The most common complications associated with FPD failure: caries endodontic complications(including fractures) uncemented restorations(leading to decay) risk of endodontic treatment : 15% for an FPD abutment 3% to 5% risk for a single crown additional tooth preparation for parallelism of the abutments the repreparation of teeth after prosthesis failure the increased risk of decay on the abutment teeth 55 m.akouchekian

56 Patient Compliance and Patient Fear an implant restoration: many steps of treatment Orthodontics,Soft tissue surgeries, bone graft surgery, implant surgery, and several prosthetic steps 56 m.akouchekian

57 Time of Treatment The time required for an implant to heal and be restored :3 to 6 months If bone grafting and soft tissue rehabilation are required: more than 1 year a traditional three-unit fixed prosthesis:less than 3 weeks m.akouchekian 57

58 Consequence of Failure The consequences of short-term failure of bone graft, implant, or prosthetic are greater for a single-tooth implant, compared with a three- unit fixed prosthesis The implant failure may result in: bone loss (especially when it occurs in the anterior regions) may include the support system of the adjacent teeth soft tissue recession devastating effects on the esthetics bone grafting may be required Additional soft tissue reconstruction These additional procedures are most often at the expense of the doctor m.akouchekian 58

59 m.akouchekian 59 The most common contraindication for a traditional fixed prosthesis and indication for a single-tooth implant in the anterior regions of the mouth is the patient's desire

60 Cost to Patient The laboratory fee to the doctor for three crowns:low. The implant body, abutment,analog, and final crown fee:more expensive Although the initial cost of treatment for an implant single crown: higher implant reconstruction was a better financial option in the long term m.akouchekian 60

61 Adjacent Tooth Mobility the adjacent teeth of the anterior implant site should exhibit minimum mobility if all other periodontal indices are normal, Natural tooth longevity is not related to mobility a traditional FPD decrease the abutment mobility m.akouchekian 61

62 Unfavorable Tooth Size and Position the maxillary anterior central incisors may be misplaced, angled, rotated, or smaller than ideal => An FPD replacing a lateral incisor: improve the position and size of the central incisor The canine may be made slightly narrower to make the lateral incisor similar in size to the contralateral incisor several cosmetic advantages especially when the lateral edentulous sites are smaller than 5 mm in width m.akouchekian 62

63 m.akouchekian 63

64 worse prognosis than a traditional FPD The genesis of failure is usually an uncemented restoration m.akouchekian 64 when the canti lever is short,limited occlusion on the pontic exists, limited mesiodistal space exists(less than 5 mm) => a cantilever may be indicated in the anterior region

65 No short- or long-term clinical studies exist in the literature for single anterior tooth replacement with an RPD. The usual indication :economics the easiest interim treatment modality during submerged implant healing Loading of a bone graft with an RPD during initial healing : increase the risk of micromovement decrease the success rate of a bone augmentation Therefore if a bone augmentation is indicated and an RPD is used, it should have a cast framework with occlusal rests to prevent rotation and loading of the soft tissue during function. m.akouchekian 65

66 has a higher survival rate in the maxillary anterior region than any other location in the mouth. The primary indication: a transitional restoration during bone and soft tissue grafts before implant placement m.akouchekian 66

67 Two modifications: 1. no enamel preparation exists on the abutment teeth and the metal substructure design is extended in areas of enamel that are gingival to the occlusal contact zones (decreases retention) 2. An acrylic removable overlay prosthesis, or a flipper is fabricated m.akouchekian 67

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69 More clinical studies have been conducted for a maxillary anterior single-tooth replacement with an implant than any other treatment option. Retrospective reports are available many prospective clinical studies confirm the data of previous reports m.akouchekian 69

70 The maxillary anterior single-tooth implant has the highest success rate compared with any other treatment option to replace missing teeth with an implant restoration recently, a trend toward single-stage and immediate- extraction implants has emerged. This appears especially attractive in the maxillary anterior region, where the soft tissue drape is ideal before the extractionand patients are more anxious to have a fixed replacement. m.akouchekian 70

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72 The minimum age of the implant patient is more often a concern for maxillary anterior tooth replacement,especially for congenitally missing teeth implants: 1. do not erupt along with adjacent teeth 2. Do not become secondarily displaced in space as do ankylosed teeth during growth of the jaws m.akouchekian 72 many implants placed in adolescents with residual growth may be in infraposition after 10 years 1.a greater soft tissue pocket around the implant 2.Tissue shrinkage 3.peri-implant conditions

73 The growth of the maxilla occurs in three distinct planes: 1. transverse (width) 2. sagittal (length) 3. vertical The transverse growth of the anterior maxilla is completed before adolescence The sagittal growth is the result of growth at the suture and bone apposition in the maxillary tuberosity region m.akouchekian 73

74 The most variable growth of concern is the sagittal growth, because the premaxilla may advance downward and forward or primarily downward As much as 25% of this displacement is lost as the result of resorption at the anterior =>facial bone resorption of the maxillary implants placed before completionof growth m.akouchekian 74

75 In premaxilla growth should be completed before implant placement. when cessation of growth and development is undetermined => Multiple implants should not be splinted across the midline in the adolescent. m.akouchekian 75

76 during the growth, teeth shift mesially. between the ages of 10 and 21: posterior segment (canine to molar): moves anaverage of 5 mm mesially the anterior segment: moves an average of 2.5 mm Therefore an implant placed too early in the growthperiod could impede the mesial shift, thus resulting in an asymmetrical arch m.akouchekian 76

77 The vertical growth continues well after transverse and sagittal growth. The Clinical reports have shown that: implants in the anterior maxilla at the age of 7 may be located up to 10 mm apically compared with the neighboring teeth 9 years later solitary implants placed at the age of 12 will be in infraocdusion 5 to 7 mm 4 years later m.akouchekian 77

78 As a general rule: the lateral incisor may be inserted at a younger ge than a central incisor or canine less obvious to the eye when lateral incisors are at different height positions, compared with central incisors. It is not unusual for a lateral incisor to be shorter than the adjacent teeth m.akouchekian 78

79 Misch et al have created four guidelines for implants placed in younger patients: 1. the chronological age of the patient The chronological age of growth cessation : for girls from 9 to 15 years and for boys 11 to 17 years As a general rule: implant insertion inthe anterior maxilla is delayed: for female patients untilat least 15 years male patients until 18 years of age. However, this guideline is too variable to be used alone => ideally, age is related to the patient's biological age m.akouchekian 79

80 2. endocrine changes The female patient should be able to menstruate the male patient should have body hair, voice changes 3. size of the the child implant patient should have greater height than their same-sex parent The size of the patient is more important than the age m.akouchekian 80

81 4. the patient has not grown in the last 6- month period This criterion is easier to observe than cephalograms or hand-wrist films with a 2-year evaluation period. m.akouchekian 81

82 The two criteria that make the implant site most at risk: 1. a male patient 2. a central incisor a delayed growth spurt : a male patient :4-inch change in height female patient may grow 1 to 2 inches If all four criteria are fulfilled (i.e., minimum age, endocrine changes, recent stature growth, 2-year lateral cephalometric radiographs with no changes) => it is very likely the patient has completed their maxillary anterior jaw growth =>the implant may be inserted with little risk or compromise m.akouchekian 82

83 the natural central incisor and canine teeth are often larger in their faciopalatal dimension at the CEl than the mesiodistal dimension The implant is round in cross section the cervical esthetics of a single-implant crown must accommodate a round-diameter implant and balance hygiene and esthetic parameters Often a soft tissue model is required to transfer the soft tissue clinical condition to the laboratory. Rarely are these unique needed for a crown on a natural tooth m.akouchekian 83

84 m.akouchekian 84 Patients with: 1. Angle's Class II Division II skeletal patterns inadequate maxillornandibular relationship 3.severe deficiency in the VD Patients with: 1. Angle's Class II Division II skeletal patterns inadequate maxillornandibular relationship 3.severe deficiency in the VD are poor candidates for many treatment options without prior corrections,they are contraindicated for dental implants

85 The smallest-diameter implant body:3.2 mm the crest module of these two-piece implants :3.5 mmmor more the mesiodistal edentulous space for a two-piece implant should be 6.5 mm or greater The average maxillary lateral incisor is 6.6 mm patients with congenitally missing teeth often have contralateral anterior teeth narrower than typical=> orthodontic therapy to increase the intra tooth space is inadequate when the lateral incisor is missing, the root of the adjacent teeth may be angled toward the edentulous site, further decreasing the intratooth bone dimension for implant => Orthodontic treatment to reposition the roots out of the edentulous root space may not be accepted by the patient m.akouchekian 85

86 One-piece dental implants may be fabricated in 2.5- mm to 3.0-mm diameters to accommodate a reduced mesiodistal dimension criterion do not have a microgap the vertical defect is narrower than most two-piece implant systems they may be placed as close as 1 mm from an adjacent tooth can accommodate a 5-mm mesiodistal missing tooth space m.akouchekian 86

87 The available bone for implant insertion in esthetic regions will greatly influence: the soft tissue drape implant size Implant position (angulation and depth) The final esthetic outcome not only the available bone volume is necessary also the position of the osseous crest is specific The ideal midcrestal position of the edentulous site:2 mm below the facial CEj of the adjacent teeth m.akouchekian 87

88 the interproximal bone: should be scalloped 3 mm more incisal than the midcrestal position Becker et al. Found: the range of interproximal bone height above the midfacial scallop was from less than 2.1 mm to more than 4.1 mm 2.1 mm :flat 2.8 mm : scalloped 4.1 mm :pronounced scalloped m.akouchekian 88

89 The flat anatomy => square tooth shape the scalloped => ovoid tooth shape pronounced scalloped =>triangular-shaped tooth However, these relationships do not always exist When a flat interdental-to-crest dimension is found on triangular teeth => the interproximal space will usually not be filled with soft tissue because the dimension of the interproximal contact to the bone will be greater than 5 mm. when a single-tooth site has inadequate bone height at the crest and the adjacent roots also have lost bone => Orthodontic extrusion of the teeth may be considered (To grow crestal bone height on the adjacent roots,in relation to the ideal crest of the ridge) m.akouchekian 89

90 Most of the conditions that lead to single-tooth loss result in the loss of some or all of the facial bone within the first year of tooth loss :a 25% decrease in faciopalatal within 3 years: a 30% to 40% decrease After 3 years: it almost never presents adequate available bone for the properly sized implant. m.akouchekian 90

91 Because: 1. the labial plate is very thin compared with the palatal plate 2. facial undercuts are often found over the roots of the teeth => The bone width loss is primarily from the facial region m.akouchekian 91

92 The amount of available bone width (faciopalatal) should be at least 2.0 mm greater than the implant diameter at implant insertion and ideally more than 3 mm greater in width m.akouchekian 92

93 When a tooth is lost: the thin interseptal bone disappears the bone remodels in a sloping fashion from the palatal to the more apical facial bony plate the interdental papillae are often depressed The use of a soft tissue removable prosthesis often accelerates the collapse of the soft tissue and its apical migration Soft tissue manipulation to restore their proper contour is often required in conjunction with implant therapy. m.akouchekian 93

94 m.akouchekian 94

95 Anodontia The most common maxillary anterior tooth replaced by an implant is a central incisor lost from trauma (e.g.,endodontic failure, fracture, root resorption) and/or a lateral incisor lost as a result of agenesis in a lateral incisor: the ideal cervical region of the tooth is similar to the implant diameter m.akouchekian 95 the roots of the adjacent natural teeth often impinge on the edentulous bone the mesiodistal length is insufficient orthodontic therapy before implant placement should often be considered

96 When the patient is missing a maxillary lateral incisor, space closure is less often indicated: When a maxillary canine is orthodontically moved to a lateral position: 1. The midline between the central incisors is often shifted to the missing tooth side. 2. The canine eminence over the canine root is positioned under the nose=>creat a depression lateral to the naris, and a less full maxillary lip on one side of the midline. These differences are more evident as the patient ages 3. The maxillary canine is larger faciopalatally than mesiodistally => the cervical emergence is different from the contralateral incisor, even when restored with a laminate facing. 4. The height of gingival contour is also higher than the lateral incisor on the other side of the arch. m.akouchekian 96

97 m.akouchekian 97 The missing maxillary lateral incisor is the tooth most often replaced with a dental implant because the other orthodontic or prosthetic options are usually poor alternatives.

98 The treatment options are usually different for a mandibular second premolar compared with a maxillary lateral incisor. A congenital missing mandibular second premolar 1. the deciduous molar may be extracted patient in 5 to 6 years old. 2. The permanent first molar may then erupt in a more mesial position 3. When the first deciduous molar is lost naturally (around the age of 9 to 11 years) 4. the first permanent premolar and first molar may be orthodontically positioned adjacent to each other This approach eliminates the need for a second premolar replacement no required to bone graft, implant surgery, or crown (or combination of these treatments) Very few disadvantages exist to the use of orthodontics to eliminate this posterior missing tooth space. m.akouchekian 98

99 When the deciduous second molar is maintained: it often becomes ankylotic the opposing maxillary second premolar extrudes the mesiodistal space is larger than the usual premolar(Because the deciduous molar is 1.9 mm larger than a premolar) The deciduous tooth does not have a buccolingual width of bone => can not use a larger-diameter implant. The crown for this larger tooth dimension is supported by a regular-size implant, which increases forces on the abutment screw and increases the risk of screw-loosening complications. m.akouchekian 99

100 In specific situations, the management of the patient in the early treatment phase may require orthodontics before the implant insertion to replace the missing tooth: 1. Space oppening 2. congenitally missing teeth 3. If bone height is insufficient and bone loss is also present on the adjacent teeth 4. when the patient has a failing tooth m.akouchekian 100

101 Missing lateral incisor in a child before the eruption of the permanent canine, Kokich proposed the following treatment modality: 1. The maxillary deciduous lateral incisor is prematurely extracted. 2. The permanent canine is encouraged to erupt in the missing lateral incisor position => the bone around the canine forms in the lateral incisor position. 3. after the eruption of the permanent canine in the lateral position, The deciduous canine is extracted 4. The canine is orthodontically retracted into the ideal canine position. 5. The remaining lateral incisor bone volume is abundant and ideal for an endosteal single-tooth implant. 6. After growth and development of the child has occurred, an implant may be inserted. In this manner, a bone graft will not be required before implant m.akouchekian 101

102 Root resorption may cause the loss of a single anterior tooth. Two major categories of root resorption: 1. external 2. Internal when structural failure is evident and the extraction of the tooth is eminent, two different treatment options related to the type of resorption exist. Internal root resorption: The treatment of choice is often orthodontic extraction m.akouchekian 102

103 a 3-month extraction process produces sufficient movement so that the remaining root diameter in the bone is smaller than the implant diameter. after 3 months of orthodontic extrusion, no void exists around the implant at the time of extraction and implant insertion. m.akouchekian 103

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105 When external root resorption is the cause of structural failure of the tooth root, Bone, replacing the root defect No evidence of a periodontal ligament space around the defect is seen orthodontic extrusion is not possible Delaying the extraction as long as possible the remaining root segments may be cored out during the implant osteotomy procedure If the surgical defect is too large for immediate implant insertion, then the osteotomy is grafted and the implant procedure is delayed. m.akouchekian 105

106 to obtain an ideal result When the maxillary incisor single-tooth replacement: not only evaluate the edentulous site but also the remaining anterior teeth the adjacent teeth most often dictate its length, contour, shape, and position The patient, once fully informed of the existing discrepancies and their potential negative effect on the envisioned result, may decide to: address and correct the existing problems of the adjacent teeth simply elect to accept the compromise m.akouchekian 106

107 The two maxillary central incisors should appear symmetrical and of similar size when the missing tooth is a central incisor with a mesiodistal space less or more than the size of the corresponding central incisor: 1. Orthodontic correction is strongly encouraged 2. modify the existing central incisor with a veneer to make it similar in size and shape to the missing tooth restoration lowering the mesial interproximal contact Making the two centrals more square shaped Decreases the height requirement of the papilla The shades of the two centrals are also easier to match when made at the same time in the laboratory. m.akouchekian 107

108 Because the clinical crown height of an implant supported central incisor is often longer than the adjacent tooth, an esthetic crown lengthening on the natural tooth may be used to align the gingival margins a crown-lengthening procedure on the natural tooth, may be more predictable than attempting to cover the implant crown with soft tissue m.akouchekian 108

109 Three basic shapes of maxillary anterior teeth exist: 1. square 2. ovoid 3. Triangular The tooth shape will influence the interproximal contact and the gingival embrasure. The square tooth shape is the most favorable to obtain an ideal soft tissue drape and papillae around the crown the interproximal contact is more apical more tooth structure fills the interproximal region a triangular tooth shape has a more incisal interproximal contact a steeper gingival scallop farther from the interproximal bone a space often exists between the interproximal contact and the interdental papilla of the remaining teeth When the soft tissue fills the interproximal space of the remaining anterior teeth that have a triangular shape, the tissues may be very liable and easily vanish during the healing phases after implant surgery. m.akouchekian 109

110 The tooth shape also affects the topography of the underlying hard tissues. The roots of triangular tooth shapes are positioned farther apart : Have thicker facial and interproximal bone Decrease the amount of crestal bone loss after an extraction the prognosis for an immediate implant insertion is more favorable provide the recommended 1.5 mm or more of interproximal bone from the adjacent tooth The square shaped tooth: have less interproximal bone between the roots a greater risk of crestal or interproximal bone loss with an immediate implant insertion less favorable for immediate implant insertion after extraction. m.akouchekian 110

111 The height of the maxillary lip when smiling (high lip line) is one of me most important criterion to evaluate when observing me cervical region of the maxillary anterior teeth. Ideally: the height of the maxillary lip should rest at the junction of the free gingival margin on the facial aspect of the maxillary centrals and canine teeth => the interdental papillae are visible, but little gingival display is seen over the clinical crowns. Almost 70% of patients have this ideal smile position. A "gummy"smile displays more than 2 mm of soft tissue above the clinical maxillary crowns and is more acceptable in the female patient. m.akouchekian 111

112 Under ideal conditions in the maxillary anterior region: interproximal contact should begin in the incisal third the bone: In midfacial: 2 mm below the CEl in the interproximal region : 3 mm more incisal the CEl The soft tissue: In midfacial :3 mm above the bone at the midfacial position (1 mm above the CEl) in the interproximal region : 3 to 5 mm above the interproximal bone Therefore if the interproximal contact is within 3 to 5 mm of the interproximal bone, then the interdental papilla will most often completely fill the space m.akouchekian 112

113 The higher the gingival scallop: the higher the risk for gingival loss after extraction the less likely the surgical and restorative procedures will be able to restore an ideal soft tissue contour a flatter gingival scallop: minimal tissue shrinkage more ideal outcome m.akouchekian 113

114 The biotype of the gingiva is usually called thick or thin. Thicker tissue: more resistant to the shrinkage or recession more often leads to the formation of a periodontal pocket after bone loss. Thin gingival tissues: more prone to shrinkage after tooth extraction more difficult to elevate or augment after tooth loss. m.akouchekian 114

115 According to Kois: predictability of the maxillary anterior single-tooth implant is ultimately determined by the patient's own presenting anatomy. Favorable conditions include: 1. when the tooth position is more coronal relative to the full gingival margin 2. square tooth shapes 3. flat scallop periodontium forms 4. thick periodontium biotypes, and 5. high (<3 mm) facial osseous crest positions of the teeth and midcrestal m.akouchekian 115

116 Unfavorable patient anatomy : 1. aligned or apical preexisting tooth (relative to the free gingival margin) 2. Triangular tooth shapes 3. high scallop periodontium form 4. thin periodontium types 5. low (>4 mm) facial osseous crest positions in relation to adjacent teeth and midcrestal m.akouchekian 116

117 The two most common complications of anterior singletooth implant replacement: 1. abutment screw loosening 2. crestal bone loss Both of these conditions are in part related to the implant crest module design to decrease in abutment screw loosening: an antirotational feature to decrease crestal bone loss: The crest module of an implant body should also be designed to transmit some compression and tensile forces to the crestal bone. Smooth metal on the crest module transmits shear forces to the bone => increases the crestal bone loss smooth metal collars on the implant crest module should be limited to approximately 0.5 mm m.akouchekian 117

118 the implant body should obviously not be as wide as the natural tooth or clinical crown=>the emergence contour and interdental papillae region cannot be properly established. m.akouchekian 118

119 The ideal width of bone would allow at least 1.5 mm on the facial aspect of the implant if a vertical defect forms around the crest module, that defect would not become horizontal and change the cervical contour of the facial gingiva the faciopalatal width dimension is not as critical on the palatal aspect of the implant 1. the palatal bone is dense cortical bone and more resistant to bone loss 2. the palatal area is not within the esthetic zone m.akouchekian 119

120 m.akouchekian 120

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