Prosthesis is one of the most important component of an implant. There are various prosthetic factors that must be considered for a successful implant. Few of them include prosthesis type and material, the connection between abutment and prosthesis, occlusal factors, etc.

1. Prosthetic Considerations for Implant Patients
Dr. Oinam Monica Devi

2. Contents
1. Introduction
2. General Considerations
3. Intraoral considerations
4. Implant related considerations
5. Prosthetic Considerations for Implant Patient
6. Effect of Occlusal Considerations
7. Implant complication
8. Maintenance considerations for implant prosthesis success
9. Conclusion

3. • The overall success rate of dental implants is associated with the health of
peri-implant tissues and lowered by the complications of peri-implant
mucositis and peri-implantitis.
• The health and quality of peri-implant soft tissues is influenced by many
factors.
• The manner in which a dental implant is restored significantly contributes
to the long-term prognosis and course of peri-implant diseases
• Implant prosthesis design plays an important role in determining the
patient’s risk for developing peri-implant mucositis and peri-implantitis
Introduction

4. • Implant prosthetic treatment planning has seen a shift from surgically
driven implantology to prosthetically driven to decrease the ratio of implant
failures due to prosthetic reasons.
• This approach of prosthetically driven implantology balances implant
aesthetics and implant function by considering factors of prosthesis
planning before surgical implantation.
• Thorough evaluation of the patient and treatment planning of the prosthesis
decreases the chances of implant failures.

5. • Various aspects related to the prosthodontic treatments influence the health of
peri-implant tissues include
1. Poor treatment planning
2. Impression taking
3. Laboratory decisions
4. Temporization
5. Poorly designed restorations
6. Cementation
• Prosthetic factors such as presence of residual cement, ill-fitting prosthetic
components, insufficient crown margins on implant abutments, abutment
height, abutment-implant connections, prosthesis contours, access for oral
hygiene, and management of occlusal forces are potential etiologic factors
leading to peri-implantitis.

6. • To balance between now increasing demand of aesthetics along with
function, prosthetically driven implantology has come to play i.e. prosthetic
part of the prosthesis is considered before the surgical part.
• The prosthetic considerations include
1. The physical and medical status of the patient
2. Bone evaluation
3. Radiographic considerations,
4. Factors that implant selection will affect occlusal scheme considerations
and maintenance by the patient, and follow-up by the clinician

7. General considerations
Age
• Implant placement needs to be done after
the completion of the growth of the patient
•If done before growth completion it may
lead to complications such as submerging
of implant and/or its relocation.
Oral hygiene and habits
• Patients with poor oral hygiene or habits
such as tobacco chewing and chain-
smoking have a higher risk of implant
failures.
•Patients with a history of smoking should
cease smoking for a minimum of one week
prior and at least 8 weeks after implant
surgery.
Medical history
• Patients with cardiovascular disorders
should be advised to get clearance for
implant placement by the cardiologist or
their physician.
• In patients with pulmonary disorders,
alginate impressions should be avoided
as it can lead to suffocation.
Parafunctional activity
• Activities such as bruxism and clenching
have been identified as a major concern
in implant treatment planning as they
result in increased pressure on the
implants and eventually metal fatigue
and bone loss.

8. INTRAORAL EVALUATION
1. Soft tissue considerations: Gingival biotype plays a crucial role in the
aesthetic success of the prosthesis.
• Thick and fibrous biotype provides better aesthetic results while thin
biotype does not mask the implant and abutment parts .
• In Gingival papillae that are fine and long, aesthetic results are difficult to
obtain.
• Whereas in thick and short papillae natural regeneration is facilitated .

9. 2. Evaluation of alveolar bone:
• Alveolar bone should be evaluated for bone defects.
• In cases of the presence of difference in the bone level at the implant site
and adjacent to that, there is an increased risk to both- periodontal and peri-
implant tissue.
• Reconstruction of crest either by regeneration or bone grafting becomes
important.

10. • Bone density: Different densities of bone have different strengths and modulus
of elasticity and hence there is a difference in stress-strain distribution.
• In D1 bone (thick compact bone) highest stresses are observed near the crest of
the implant.
• In D2 bone, the intensity of stresses extends apically.
• Bone density is directly related to BIC and therefore influences the healing of
the implant and its primary stability.
• D1 bone has about 85% BIC, D2 has 65%-76% BIC, D3 has about 40%-50%
BIC and D4 has less than 30% BIC.

11. Bone-implant interface (BIC):
• Less the BIC more implant surface area is required to achieve more contact and
increase primary stability.
• In D3 and D4 bones, the stresses per unit area should be reduced. This is
achieved by placing implants for individual tooth and decreasing the cantilever
length.
• D4 bone may require a wider implant.
• An increase in BIC can be obtained by using a threaded implant with more
threads, it can also be obtained by using a coated implant.

12. • Radiographic evaluation helps in the determination of factors such as bone availability,
the density of bone, vital structures, pathologies, and evaluation of adjacent teeth.
1. A minimum of 1.5-2mm of bone should be taken from an anatomical landmark, the
most crucial in the mandible being the mandibular canal and mental foramen.
2. A buffer of 1.5mm-2mm is taken from the adjacent tooth. This minimum amount of
bone allows the implant to gain primary stability.
3. The minimum bone height suggested for implant placement is 12mm. Studies have
shown height less than 9mm to have a higher rate of implant failure.
4. Bone width is measured from lingual plate to labial plate. This should be at least 2mm
greater than the implant diameter.
5. Edentulous span: the length of the available bone should be such that a minimum of 1.5
mm of bone should be present from adjacent tooth and a minimum of 3mm bone from
an adjacent implant.

13. Prosthodontic option for different types of bone

14. Prosthetic options available in Division A bone
• FP-1 restorations: For ideal implant placement and natural esthetic appearance
of final prosthesis require Division A bone.
• FP-2 or FP-3 restorations: These prosthetic options may be considered
depending on amount of bone loss and lip positions.
• RP-4 or RP-5 restorations: These conditions may require osteoplasty
considering interarch space to accommodate denture teeth.

15. Prosthetic options available in Division B bone
• FP-2 or FP-3 restorations are indicated in this condition to compensate increased
clinical height.
• Osteoplasty to get Division A ridge is mostly indicated in anterior mandible
because of fewer esthetic concerns in this region.

16. Prosthetic options available in Division C bone
• More number of implants are required to expand implant bone surface area.
• In edentulous patients, RP-5 prosthesis may be considered.
• Recent studies have advocated the use of shorter textured implant more suitable
option in posterior maxilla and mandible with compromised bone height.

17. Prosthetic options available in division d bone
• Autogenous with bone grafts is indicated to upgrade the division.
• Endosteal or subperiosteal implants may be inserted depending on the
division of bone attained.

18. • As the bone density decreases, the biomechanical loads on the implants must be reduced by considering
the following prosthetic design.
1. Angle of load on the implant body should be more axial and offset loads minimized.
2. Narrower occlusal tables should be designed.
3. Splinting the crowns of adjacent implants with relatively stiff.
4. Restorative materials may be considered.
5. Cantilever length may be shortened or eliminated in case of full-arch restorations for edentulous patients.
6. RP-4 rather than FP prosthesis may be considered in edentulous patients to reduce nocturnal
parafunctional forces.
7. RP-5 prosthesis may be considered to permit the soft tissue to share the occlusal force.
8. Night guards and acrylic occlusal surfaces distribute and dissipate the parafunctional forces on an
implant system.
9. By considering progressive bone loading.

19. 3. Inter-arch distance and space evaluation:
• Inter-arch distance for proper visibility and instrumentation should be evaluated.
• Inter-arch space on the other hand is necessary to provide adequate function,
aesthetics, and phonetics to the patient.
• Decreased space may lead to implant prosthesis with occlusal plane interferences.
• A minimum of 8-10mm of inter-arch space is required in the anterior region and a
minimum of 7mm space in the posterior region for fixed implant prosthesis.
• For a removable prosthesis, a minimum of 12mm of space is needed.

20. 4. Crown- height space (CHS):
• CHS affects the appearance and amount of moment force on the implant
and surrounding crestal bone.
• It is measured from the occlusal or incisal plane to the crest of the ridge.

21. Implant related considerations
1. Thread design: Thread design should be such that it maximizes BIC and therefore
reduces stress. Smaller pitch i.e. the distance between two threads indicates more surface
area for better stress distribution.
2. Thread depth: deep threads increase the surface area and contribute to the primary
stability of the implant.
3. Implant length and width: increase in implant length increases the primary stability but
it doesn't decrease the stresses. For regions where maximum stresses are concentrated, an
increase in the width of the implant is a better way to distribute the stresses.
4. Crest module: the crest module is always slightly larger than the outer thread diameter. A
parallel or same-sized crest module increases the risk of bone loss after loading.

22. Prosthetic Considerations for Implant Patient

23. Prosthetic Options in Fixed Full-arch Restorations
Porcelain-metal restoration
• The main problem encountered with this restoration is related to the added
bulk of metal used in the substructure to keep porcelain to its ideal 2 mm
thickness.
• This amount of metal acts as a heat sink during casting procedures which
results in porosities and increases the risks of fracture after loading.

24. Hybrid prosthesis
• Acrylic acts as an intermediary between the porcelain teeth and metal
substructure, the impact force during dynamic occlusal loading also may be
reduced.
• Hybrid prostheses are indicated for implant restoration in large crown
height spaces as a general rule.

25. Prosthesis for occlusion types
Class II relation
• An anterior cantilever on implants in the mandibular arch may correct an
Angle’s skeletal Class II jaw relationship.
• To counteract this force multiplier, the treatment plan is modified by:
1. Increase in implant number, size, and surface area of design
2. Increase in A-P distance between splinted implants
3. A RP-4 restoration may be indicated, rather than a FP-3, to prevent food
impaction and to facilitate daily care.

26. Class III relation
• Because the edentulous premaxilla resorbs toward the palate, a Class III
relationship is often observed.
• These patients have a full range of mandibular excursions that exerts
significant lateral forces on the maxillary restoration, which is
cantilevered off the implant base to obtain a Class I esthetic restoration.
• Additional splinted implants in the maxilla are advocated with the widest
A-P distance available. This usually requires sinus graft procedures to be
incorporated into the treatment plan.

27. Arch Form: Prosthetic Consideration
• The most ideal biomechanical arch form depends on the restorative situation:
1. The tapering arch form of residual bone is favorable for anterior implants
supporting posterior cantilevers due to a greater A-P spread.
2. The square arch form of residual bone is preferred when canine and posterior
implants are used to support anterior teeth in either arch.
3. The recommended anterior cantilever dimension in the maxilla is less than that
of the posterior cantilever in the mandible because the bone is less dense and
forces are directed outside the arch during excursions.

28. Implant Permucosal Position: Prosthetic Consideration
• An implant placed in the improper position can compromise the final results in
terms of esthetics, biomechanics, and maintenance.
• The most compromising position for an implant is too facial because no
prosthetic ‘”trick” exists to mask it, resulting in compromised esthetics,
phonetics, lip position, and function.
• The permucosal position of the implant abutment is of particular importance for
FP-1 prostheses.
• The ideal position is directly under the incisal edge position of the anterior
natural tooth and under the central fossa of posterior natural teeth to be
replaced.

29. Number of Missing Teeth: Prosthetic Consideration
• The number of implants used to support a completely implant-supported
restoration in the edentulous mandible usually ranges from 5 to 9 in the
mandible, with at least four of these implants inserted between the mental
foramens.
• A greater implant number in the completely edentulous maxilla is indicated
to compensate for the less dense bone and more unfavorable biomechanics
and ranges from 6 to 10.
• At least two or three of these implants should be placed in the premaxilla,
depending on the arch shape and other force factors.

30. • For a square maxillary arch form (most favorable), implants may be placed
in the canine position, whereas in an ovoid arch form, additional implants
in the anterior region should be planned.
• A tapered anterior maxillary arch form combined with other force factors
may require the placement of four implants from canine to canine.

31. • All implants in either arch should be splinted together when fewer implants are
used.
• The final restoration may be segmented (canine to canine and two posterior
segments) when the number of implants permits so.
• Posterior cantilevers in the fixed prosthesis should be limited in the maxilla and
rarely extend more than one tooth.
• Posterior cantilevers in full arch mandibular restorations are not uncommon,
but the cantilever length rarely extends more than two teeth.
• The number of cantilevered pontics in both arches depends directly on overall
stress conditions.

32. Effect of the Implant-Connection
• The external hexagon does not prevent the formation of a micro gap between
the implant and the abutment, which would cause technical and
biological complications, mainly when this connection is subjected to high
occlusal loads.
• Internal connection implants have a greater contact area between the implant
and the abutment, allowing better load dissipation along the axis and providing
greater joint stability.
• Only the morse taper connection provides close contact between implant and
abutment, thus achieving the best antibacterial seal and subsequently best
marginal bone stability.

33. Effect of Loading Time
• Immediate loading could be performed in implants if the operator is properly
trained on implant-prosthodontics protocols and if implants are
1. Preferably self-tapping
2. Microroughed
3. Properly sized (8 mm height + Æ 4 mm)
4. Placed in good-quality mature bone
5. Reaching enough primary stability (>40 Ncm)
6. Restored with a provisional prosthesis screwed for at least 6 weeks with
minimal functional occlusion
7. Preferably splinted to other comparable implants
• Chen (2019), Pardal-Peláez(2020) in their meta-analyses concluded that,
compared with conventional loading, immediate loading is associated with a
higher incidence of implant failure.

34. Effect of Transmucosal Abutments
• The use of transmucosal abutments of at least 2 mm height for minimizing the
marginal bone loss of implants , which is probably the best clinical indicator of
implant success.
• Implants with a shorter polished collar not only show additional bone resorption, but
also maintain higher crestal bone levels.
• The transmucosal abutment should be inserted on the same day of implant surgery,
whenever possible, to minimize marginal bone loss and subsequent soft tissue
changes.
• The use of transmucosal abutments avoids the repeated connection/disconnection of
distinct additments at the implant platform level, hence enhancing the stability of
marginal bone

35. Effect of Prosthetic Fit
• If a dental implant is considered the endoprosthesis (infrastructure in direct
contact with the bone), the transmucosal abutment is the mesostructure and the
prosthesis itself is the suprastructure.
• The fit between infrastructure and mesostructure occurs at a bone-level and
should ideally be hermetic (impenetrability), whereas the fit between
mesostructure and suprastructure happens at the gingival level and should ideally
be passive (passive fit).
• The presence of pathogens is more threatening at the implant-abutment interface
than at the abutment-prosthesis interface.
• Machine-prefabricated additments have better fit than those manufactured by the
technicians, whose misfit usually ranges between 40 m and 120 m with distinct
techniques.

36. • The quality of sealing at the implant-abutment interface will affect the stability of
peri-implant bone.
• Misfit between abutment-prosthesis interphases is thought to create uncontrolled
strains in the prosthetic components and lead to technical complications such as
screw loosening, component fractures and, at worst, loss of implants or prostheses.
• Passive fit is the maximal spatial congruence between implant/abutment and
frameworks after tightening all screws.
• Visual assessment of the passive fit is difficult or even impossible for sub-
gingivally positioned and conical type implants, which is another reason for
working on transmucosal abutment rather than on implant level for the prosthesis
construction.

37. Jokstad, A, 2014: In a well-performed retrospective study with a large
observation period (mean: 19 years; range: 12 to 32 years) including 30
mandibular full-arch implant supported prostheses, it was found that the
average misfit of patients with history of screw-related adverse events
was slightly but significantly higher (169 32 m) than counterparts (134
30 m), although no linear correlation between misfit and marginal bone
loss was found.

38. Effect of Provisionalization
• In recent years, the use of provisional restorations on implants during healing has
been considered a key factor for achieving predictable outcomes in the esthetic
zone.
• The provisional prosthesis provides patients with a quick restoration of esthetics
and function, serves as a diagnostic template for the final restoration, and acts as
a scaffold to guide soft tissue contour for enhanced esthetics.
• Removable provisionals are cheaper and easier to manufacture/adapt, but due to
their insufficient stability (static and dynamic mobility), these prostheses could
put the underlying healing implant/graft at risk.
• Removable provisionals should be avoided when grafting tissues or when the
primary stability of implants is low.

39. Effect of Type of Retention (Screw vs. Cement)
• The main advantage of screw-retained implant reconstruction is probably its predictable
retrievability, which facilitates its removal for hygiene maintenance, repairs, or surgical
interventions.
• The main advantages of cement-retained prostheses are the improved esthetics, since the
morphology and position of the replacement tooth is not as conditioned by the prosthetic
screw access hole.
• Cemented reconstructions seem to show more serious biological complications, whereas
screw-retained reconstructions present more technical problems.
• Clinicians are more afraid of biological than technical complications, screw-retained
prostheses are probably the preferred option for most clinicians today.

40. Effect of Impression Techniques
• Within the conventional method, the impression copings can be either retained in the
cured impression material (pick-up method/direct technique) or can remain on the
implants and be repositioned later in the negative track left in the impression (transfer
method/indirect technique).
• The pick-up method needs open impression trays, whereas the transfer method is
performed with closed impression trays.

41. • For making an impression of neighboring implants (partial or full arch), especially when
there is certain angulation between each other or when implants are deep subgingivally
(>3 mm), the pick-up impression copings should be splinted to each other with a rigid
material (acrylic resin, stainless steel pins, plaster) before adding impression material to
obtain a reliable record.
• The more rigid the splinting material is, the more accurate master cast will be.

42. • Digital implant impressions allow the acquisition of implant positions by connecting scan
bodies to either implant or abutments in order to create an accessible surface for optical
acquisition by intraoral scanning devices.
• Conventional implant impressions of angulated implants are significantly less accurate
compared to parallel implants.
• Digital implant impressions are as accurate as conventional implant impressions, mainly
for single and partial edentulous spaces.

43. Effect of Manufacturing Technique
Fernández, M, 2014: When three common manufacturing techniques were
compared (milled, laser-sintered, and casted) in terms of microroughness of
the mating surfaces, it was found that milled structures were significantly
smoother (29 m on average) than laser-sintered (115 m) or casted components
(98 m). Similarly, the magnitude of the marginal micro gap was found to be
significantly smaller within milled abutments (0.73 m), than the gap of
sintered (11.30 m) and cast (9.09 m) abutments. The linear correlation
between microroughness and micro gap was found to be huge (r = 0.96).

45. Effect of Occlusal Considerations
• The following directives seem advisable to reduce excessive load in an attempt
to minimize the potential harmful effects on the system:
1. Using the occlusal scheme mutually protected whenever possible.
2. Trying to avoid, whenever possible, non-axial loading of implant-borne
(mainly for single restorations).
3. Fabricating low cusp inclinations and fitting the occlusion with shim stock
clearance at intercuspal position and centric occlusion.
4. Giving low prominence to the implant-prostheses during mandibular
excursions.

46. Occlusal considerations
1. One of the main factors that influence the prognosis of implant prosthesis is a poor occlusal scheme
which leads to increased mechanical stresses causing crestal bone loss and resulting in implant failure.
2. Occlusal contacts: occlusal adjustments should be done using an articulating paper of less than 25 μm
thickness, this relieves the initial contact leading to increased load on adjacent teeth.
3. Surface area: the occlusal table of the implant crown should be narrow which reduces the magnitude
of the force acting by decreasing the cantilever.
• Another method to decrease the magnitude of force acting is to use additional implants,
ridge augmentation, reduction of crown height, and increasing the implant diameter.
4. Cusp angle: steeper cusps are seen to increase torquing forces.
5. Cantilever length: cantilevers act as class I lever, increasing the occlusal load on the implants. The
force and length of the cantilever are directly proportional to the force acting on the implant.
6. Occlusal contact position: according to Peter K Thomas, there should be a tripod contact on each
occluding cusp, marginal ridge, and central fossa.

47. Occlusal scheme selection: implant-supported fixed
prosthesis
1. Edentulous ridge opposing natural dentition- Group function occlusion is
preferred. In cases of shallow anterior guidance, mutually protected occlusion is
given.
• Simultaneous contact bilaterally and anterio-posteriorly during maximum
intercuspation and in centric relation.
• Freedom in centric should be provided in centric and MIP (1-1.5mm).
Infraocclusion by 100nm decreases the risk of fatigue and failure of the
prosthesis.
2. Completely edentulous arch opposing a complete denture- Bilaterally balanced
occlusion scheme is preferred.

48. Occlusal scheme for implant-supported overdenture
1. Completely edentulous arch with normal/healthy ridges:- An optimal
occlusal scheme in such cases is bilaterally balanced occlusion with lingualized
occlusion. A minimum of 3 point contact during lateral and protrusive
movements should be established.
2. Completely edentulous arch with severely resorbed ridges: optimal occlusal
scheme in such cases is monoplane occlusion as it reduces the forces acting on
the ridge.

49. Occlusal scheme for fixed partial dentures
1. Class i or ii partially edentulous:- mutually protected occlusal scheme is
preferred or group function when anterior teeth are periodontally compromised.
2. Class iii and class iv partially edentulous:- The optimal occlusal scheme is
group function. Freedom in centric of 1-1.5mm to be given along with a narrow
occlusal table.

50. All-on-four concept
• The concept was developed to maximize the use of available remnant bone in atrophic
jaws, allowing immediate function and avoiding regenerative procedures that increase
the treatment costs and patient morbidity, as well as the complications inherent to these
procedures.
• The prinicple of all-on-four concept is to use four implants on the anterior part of the
completely edentulous jaws to support a provisional, fixed, and immediately loaded
prosthesis.
• The two most anterior implants are placed axially, whereas the two posterior implants
are placed distally angled to minimize the cantilever length and to allow the application
of prosthesis with upto 12 teeth.
• Final prosthetic solutions can either be fixed (FPD) or removable dental prosthesis.

52. Platform switching
• The most important criteria for the success of dental implants are the presence of
good quantity and quality of bone around the implants.
• Crestal bone loss can result in increased bacterial accumulation resulting in
secondary peri-implantitis and loss of bone support, which leads to occlusal
overload resulting in implant failure.
• Platform switching (PLS) is a method used to preserve alveolar bone levels
around dental implants.
• The concept refers to placing restorative abutment of narrower diameter on
implants of wider diameter, rather than placing abutments of similar diameters,
referred to as platform matching (PLM).

53. Rationale of Platform switching
• The remodeling of crestal bone occurs in response to the stress that develops
between the neck of an implant system and cortical bone.
• Prevention of horizontal and vertical marginal peri-implant bone resorption
during the postloading period is fundamental in maintaining stable gingival
levels and profiles around implant-supported restorations.
• Reduced stress in the coronal portion of Platform Switching Implant (PLSI)
helps to prevent crestal bone loss.
• The platform switching concept is based on the use of an abutment smaller than
the implant neck; this type of connection moves the perimeter of IAJ to the
center of implant axis.

54. • The implant abutment junction (IAJ) is always encircled by an inflammatory cell
infiltrate (0.75 mm above and below the IAJ).
• The current theory of the benefit of Platform switching (PLS) is related to the
physical repositioning of the IAJ away from the outer edge of the implant and the
surrounding bone, thereby containing the inflammatory infiltrate within the width of
the platform switch.
• The magnitude of the implant abutment diameter mismatch makes a statistically
significant difference in bone levels when the implant abutment diameter mismatch
was >0.8 mm, providing a 0.4 mm circumferential width of platform switch when
the center of the abutment is aligned with and fixed to the center of the implant

55. How Platform Switch helps
• It results in a circular horizontal step, which enables a horizontal extension of the biologic
width and diminution in alveolar bone loss reduced the potential influence of microgap on
the crestal bone and decreased stress levels in the peri-implant bone and increases the force
in and around the screw.
• It provides the clinician with additional surgical and prosthetic treatment options for use
with wide diameter implants.

56. Biologic width and Platform Switching
• The peri-implant soft tissue seal comprises of a junctional epithelium and connective tissue. This
biologic soft tissue coats the implant supporting bone in a 3–4 mm wide zone.
• Tarnow et al., showed that not only this width progresses apically, but also a lateral component of
the biologic width exists around implants that varies from 1.04 mm when two adjoining implants
are placed <3 mm apart to 0.45 mm when the implants are placed more than 3 mm apart.
• If the implants are placed too close together, the overlap of the horizontal components of each
implants biologic width serves to increase the effective vertical crestal bone loss between the
implants.
• By PLS implants can be placed closer to teeth and to each other while maintaining more crestal
bone.
• PLS has been shown to have the potential to reduce the vertical bone resorption by as much as
70%.

57. Indications for Platform Switched Implants
• If anatomic structures limit the residual bone height
• Where implants are placed <3 mm apart in narrow edentulous ridge
• If shorter implants are used in atrophic areas
• To achieve good esthetic results in anterior maxilla

58. Advantages
• Inflammatory cell infiltrate which surrounds the IAJ in a collar-like fashion is contained
within the angle formed at the interface, and thus prevented from spreading further
apically along the implant resulting in inflammatory changes to bone crest.
• The horizontal dimension of the step allows for an additional area where biologic
attachment can take place, thus limiting the extent of physiologic remodeling of the bone
crest needed to accommodate the biological zone.
• Optimal management of restorative space with the crestal bone preserved both
horizontally and vertically, thus support is retained for the interdental
papillae.Maintenance of midfacial bone height helps to maintain facial gingival tissues.
• • Improved bone support for shorter implants.

59. Disadvantages
• Need for components that have similar design
• Need for sufficient space to develop proper emergence profile

61. Angled abutments
• As early as 1990 Kallus et al. demonstrated prototype angled abutments of the Branemark
(Nobel Biocare, Göteborg, Sweden) implant system.
• The advent of angled abutments has simplified the management of situations when
implant placements are suboptimal.
• It is known that the loading on angled abutments is mostly off-axis, which raises the
concern of how angled abutments generally perform with such an unfavorable loading
regimen.

62. 1. The clinical performance of angled abutments is comparable to that of straight
abutments.
2. The stresses/strains generated through off-axis loading increase as the abutment
angulation increases, but there is no consensus as to what extent of angle increase
will cause implant or bone failure.
3. Off-axis loads are said to be detrimental to the surrounding bone. However, the
clinical performances of angled abutments have mostly been satisfactory.

64. Maintenance considerations for implant prosthesis success
1. Maintenance of implant is important for long-term success.
2. Regular recall visits at 1, 3, 6, and 12 months after implant prosthesis delivery
should be carried out.
3. Home care instructions should be given.
4. The patient's role in the maintenance of the prosthesis is crucial. Plaque control
by using floss, soft toothbrushes, antibacterial mouthwashes, and slim sonic
brushes for cleansing of dentures.
5. Brushes are dipped in chlorhexidine (0.12% solution), this has been found to
kill 100% bacteria in a 30-sec rinse.

65. • The success of the implants depends on the stability of the marginal bone when
the prosthesis is connected to them and in function ; thus, the potential weight
of the prosthetic factors on the prognosis is evident.
• Current conception of implant success also includes prosthetic parameters and
even patient-focused variables such as satisfaction , in addition to the traditional
implant and peri-implant level criteria.

66. Conclusion
• Arch relationships often are affected in edentulous ridges due to the faciolingual
direction of resorption.
• As a result, implants often need to be placed more lingual in comparison to the original
incisal tooth position.
• The final restoration is subsequently overcontoured facially to restore the incisal two-
thirds for improved esthetics.
• This results in a cantilevered force on the anterior implant body.
• The maxilla is affected more often than the mandible because the incisal edge position
cannot be modified and is dictated by esthetics, speech, lip position,
and occlusion.
• The hygiene of the prosthesis is compromised due to the overcontour.

67. References
• Gowd MS, Shankar T, Ranjan R, Singh A. Prosthetic consideration in
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69. Thank you