2. Contents
• Introduction
• Concept of progressive bone loading
• Etiology of variable bone density
• Misch bone density classification
• Scientific rationale of Bone density based implant treatment
• Rationale for progressive loading
• Elements of progressive loading
• Progressive loading phases
• Review of literature.
• Conclusion
3. Timing of loading
IMMEDIATE = WITHIN 48 HRS OF IMPLANT
PLACEMENT
EARLY LOADING= 2 WEEKS TO 2 MONTHS
DELAYED LOADING = AFTER 3 MONTHS
PROGRESSIVE LOADING = GRADUAL
LOADING
4. The Three Most Common Causes Of Early Prosthetic
Related Implant Failure.
The implant is most at risk for failure or crestal bone loss
within the first year.
•Non Passive
Superstructures.
•Partially Unretained
Restorations.
Loading Of The Implant
Support System Beyond
The Strength Of The
Bone-to-implant
Interface
Risk and Failure
5. How to reduce implant failures???
Occlusal
loading
Strength of bone
and implant
interface
6. Density of bone reflects the biomechanical properties of bone.
7. The need for initial progressive bone loading
during prosthetic reconstruction.
Treatment
planning
Surgical
approach
Implant
design
Healing time
The density of bone in edentulous site is a determining factor
8. Early implant failure is related to bone density.
More early loading failure reported in softer bone types.
Primarily related to the early prosthetic loading.
Misch first proposed the concept of progressive loading in 1980.
Concept of progressive bone loading
9. WOLFF’S LAW
Concept of progressive bone loading
Every change in the form and
function of bones or of their
function alone is followed by
certain definite changes in their
internal architecture, and
equally definite alteration in
their external conformation, in
accordance with mathematical
laws. (1892)
10. • Bone reacts to mechanical stress similar to a muscle. When it is not stimulated, the
muscle (bone) becomes weaker. It was logical to assume when the muscle (bone)
is stimulated, the muscle (bone) will become stronger.
• The strain produced in bone on loading increases the density of the lamellar bone
which is then able to sustain functional loads.
Concept of Progressive loading
Active v/s Sedentary
11. Misch et al. reported on 364
consecutive implants in 104
patients with 98.9% survival at
stage II uncover followed by a
progressive loading format and
found no early loading failures
during the first year of function
Misch CE, Hoar JE, Hazen R, et al: Bone quality based implant system: a prospective study
of the first two years of prosthetic loading, J Oral Implantol 25:185–197, 1999.
Study result of Misch et al. (1999)
12. Mandible: Force absorption unit
Maxilla: Force distribution unit.
In general, the density change after tooth loss is greatest
in the posterior maxilla and least in the anterior
mandible.
Etiology of variable bone density
Mac Millan and Parffit
16. Bone density is directly related
to the strength of bone before
microfracture
The different
densities of bone
have a
different strength.
Type D1 bone is
strongest, and
type D4 bone is
the weakest.
Bone Strength and Density
17. It should be noted that the strength of bone
studies were performed on mature bone
types. Bone is 60% mineralized at 4 months
after implant surgery, and the strength of
bone is related to the amount of
mineralization
Bone Strength and Density
18. Healing period vs Bone strength
Hence , a healing period after
surgery of 3 to 4 months is adequate
for D1 and D2 bone.
A healing period of 5 to 6
months is beneficial in D3 to
D4 bone.
19. AT HIGHER STRESS
• MICRO STRAIN CONDITIONS.
• PATHOLOGIC OVERLOAD.
IMPLANT FAILURE
AT LOWER STRESS
• LOW MICROSTRAIN CONDITIONS
• ADAPTED WINDOW ZONE
Bone is more flexible than titanium
Load-bearing lamellar bone at
the interface.
Elastic modulus and Bone density
20. Elastic modulus and Bone density
Misch et al. found the elastic modulus of the trabecular bone in
the human jaw to be different for each bone density
107
81
35
Elastic Modulus (Mpa)
D2 D3 D4
The elastic modulus of the trabecular bone is different for each bone
density. D2 trabeculae are more stiff than D4 bone trabeculae
21. Elastic modulus and Bone density
when a stress is applied to an implant prosthesis in D1 bone, the
Ti–D1 bone interface exhibits very small microstrain difference.
In comparison, when the same amount of stress is applied to an
implant in D4 bone, the microstrain difference is greater and may
be in the pathologic overload zone
22. Misch noted that the bone density
influences the amount of bone in contact
with the implant surface.
The BIC percentage is significantly
greater in cortical bone than in
trabecular bone.
Bone Density and Bone – Implant Contact Percentage
23. • D1 bone provides the highest percentage of
bone in contact with an endosteal implant and
may approximate more than
85% BIC.
• D2 bone, after initial healing, usually has 65%
to 75% BIC.
• D3 bone typically has 40% to 50% BIC
after initial healing
• The bone–implant contact for D4 bone is less
than 30% after initial healing.
24. Crestal bone loss after loading may
occur from excess stress at the
implant–bone interface.
Bone density BIC stress
transfer
Bone Density and stress transfer
25. • Bone physiology
• Clinical studies supporting
progressive loading
Rationale for progressive loading
26. Density of trabecular bone evolves as a result of
mechanical deformation from microstrain.
FROST
Bone physiology
27. DYNAMIC /CYCLIC LOADING
MORE BONE FORMATION
LOWER MAGNITUDE LOADS FOR MANY CYCLES
HAVE SAME ANABOLOIC EFFECTS OF LARGER
LOADS FOR A LIMITED NO OF CYCLES.
Bone physiology
28. Many studies were done to assess the pros
and cons of progressive loading .
Misch did a clinical assessment using 250
implants over a 2- year period using a
Periotest
Misch CE: Progressive bone loading. In Misch CE, editor:
Contemporary implant dentistry, St Louis, 1993, Mosby
This instrument evaluates the dampening effect of
implants, prostheses, and teeth, which is related
directly to mobility.
Studies Supporting Progressive Loading
29. • The Periotest valuescanrangefrom−8to+50
• A range of −8to-6Periotest value is applicable to a structure with
an absence of clinical mobility.
• The implants in D1 bone, after progressive loading, did not improve
statistically, although a −7 Periotest value was recorded more often.
• The implants in D2 bone exhibited a mean decrease of 1 Periotest
value.
• The implants in D3 bone had a slightly greater than 2 Periotest
value decrease after progressive loading.
• The greatest change was seen in D4 bone where the mean decrease
in Periotest value was almost 4 units.
Studies Supporting Progressive Loading
30. Therefore, the poorer the bone
density
-- D3 and D4 -- the more
dramatic the decrease in
Periotest values –(which relates
to mobility and density of bone
around the implant).
Studies Supporting Progressive Loading
31. • Appleton :Evaluated peri-implant bone changes in
response to progressive bone loading development of
denser trabeculae:
There was a less bone loss in progressively loaded implant.
• Pierazzini: Demonstrated development of denser
trabeculae around progressively loaded implants.
• Piattelli: Demonstrated regions of lamellar cortical bone
around loaded implants compared to unloaded implants.
Studies Supporting Progressive Loading
32. Progressive bone loading aims at
• Increasing the density of bone,
• Decreasing the risk of implant–
bone failure, and
• Decreasing crestal bone loss.
34. The progressive loading protocol
uses a cement-retained
prosthesis when implants are
splinted together.
Screw retained splinted
restoration is
Not completely
passive
Torque force applied to a
screw is greater than a
bite force
A traditional screw-retained restoration cannot use progressive
loading to gradually load the bone
36. Time - Initial Healing
The ideal bone for implant prosthetic support is
lamellar bone.
Woven bone is the fastest and first type of bone to form
around the implant interface; however, it is mineralized
only partly and demonstrates an unorganized structure
Lamellar bone is highly organized but takes about 1 year
to mineralize completely after the trauma induced by
implant placement.
37.
38. At 16 weeks, the surrounding bone is only 70%
mineralized and still exhibits woven bone as a
component.
The percentage of bone mineralization and the type of supporting
bone influence whether a load to the bone– implant interface is
within its physiologic limits.
BIC
Bone density
Healing time
D1 & D2 BONE ---3-4 MONTHS
D3 & D4 BONE ----5-6 MONTHS
Intial Healing time
39. The four prosthetic steps are
(1) Abutment insertion, preparation, final impression
and temporary (of the esthetic zone).
(2) Metal try-in and new bite registration.
(3) Initial delivery of the prosthesis.
(4) Final evaluation of the restoration and hygiene
appointment.
Four prosthodontic steps are suggested for the
reconstruction of a partially or completely edentulous
patient, with endosteal Implants & they are separated by
a period of time related to the bone density observed at
the initial time of surgery.
40. This schedule allows sufficient time for
mature lamellar, mineralized bone to develop
at the interface of the implant.
41. When the dentist uses multiple implants,
the weakest bone area determines the
gradual load protocol.
Hence, if the anterior maxilla and
posterior maxilla are restored together,
the posterior maxilla
Initial healing
period
Time period between
each prosthetic
appointment
DETERMINES
42. Diet
1. During the initial healing
phase:
Avoid chewing in the area, especially
when the implants are placed in a one-
stage approach.
2. The implant connected to an
abutment for cement
retention:
43. The patient is limited to a soft diet such as pasta and
fish, from the final impression stage until the initial
delivery of the final prosthesis
The masticatory force for this type of food is
about 10 psi
44. 3. After the initial delivery of the
final prosthesis:
Include meat in the diet, which requires about 21
psi in bite force.
The final restoration can bear the greater force
without risk of fracture or uncementation
45. 4. After the final evaluation appointment:
Include raw vegetables, which require an average 27
psi of force.
A normal diet is permitted only after evaluation of the final prosthesis
function, occlusion, and proper cementation
46. Occlusal Material
1. During the initial healing:
The implant has no occlusal contact.
2. At subsequent appointments:
The dentist uses acrylic as the occlusal
material, with the benefit of a lower impact
force than metal or porcelain.
3. Final occlusal material:
Either metal or porcelain can be used
47. In this way, the bone has a longer time to mineralize
and organize to accommodate the higher forces.
PARAFUNCTION or CANTILEVER LENGTH
SOFTER DIET AND ACRYLIC RESTORATION
PHASE SEVERAL MONTHS.
Extend
48. Occlusion
STEP 1: No occlusal contacts are
permitted during initial healing .
STEP 2: The first transitional prosthesis is
left out of occlusion in partially edentulous
patients.
STEP 3: In second transitional
prosthesis, occlusal contacts then are
similar to those of the final restoration
for areas supported by implants. No
occlusal contacts are made on
cantilevers or offset loads
49. Prosthesis Design
1. During initial healing:
• Avoid load on implants , including
soft tissue loads.
• Relief and a soft tissue conditioner
used for CD.
In a completely edentulous patient:
50. Prosthesis Design
2. First transitional acrylic restoration in
partially edentulous patients :
No occlusal contact and No cantilevers.
Its purpose is to splint the implants
together and reduce stress.
Purpose
54. The dentist instructs the patient with a
posterior implant in a partially
edentulous arch not to wear any
removable restoration.
If anterior teeth are part of the
removable prosthesis, a 7-mm-
diameter hole is placed completely
through the partial denture framework
around each PME
so it will not load the implant.
55. In completely edentulous patients, the
tissue surface of the denture is
relieved at least 5 mm over and around
the implants and replaced by a tissue
conditioner.
The conditioner also is relieved a few
millimeters. The patient returns in 2
weeks for suture removal and to
replace the tissue conditioner with a
soft liner.
57. THE PROGRESSIVE BONE-LOADING APPOINTMENT SEQUENCE IS AS FOLLOWS :
1. Initial abutment selection, Final impression and transitional prosthesis I
2. Metal superstructure try-in and transitional
prosthesis II
3. Initial insertion of final prosthesis
4. Final delivery and evaluation
PARTIALLY EDENTULOUS KENNEDY CLASS I OR CLASS II PATIENT
58. An abutment for cement retention is
inserted and torqued into the implant bodies
1. Initial abutment selection, Final impression and
transitional prosthesis I
59. The final abutment for cement retention is
torqued into position after a radiograph
confirms its position.
61. The first transitional restoration is
cemented with temporary cement. It is
completely out of occlusion.
62. Pour the impression with dental stone
Mounted to the opposing arch with the bite registration
Full-contour wax-up
Cutdown of 2 mm in regions of porcelain for the prosthesis
framework.
Precious metal superstructure is made
Occlusal acrylic index to indicate the occlusal registration recorded
for the implant-supported prostheses
LABORATORY PHASE -1
63. The laboratory technician fabricates
a metal framework that splints the
abutments together
Mounted to the opposing
arch with the bite
registration
64. A metal try-in evaluates the casting
2. METAL TRY –IN APPOINTMENT
66. The original transitional restoration is modified by
adding acrylic on the occlusal surface, and a heavy
bite force occlusal adjustment is made.
67. Eliminates the nonworking and working occlusal contacts.
Pontic areas and angled abutments into light centric
occlusion.
Heavier contacts are developed on the implants in ideal
position.
No cantilevers unless for esthetics.
Occlusal scheme is similar to that of the final prosthesis.
Diet remains soft with pasta, fish, or softer food types.
Occlusal schemes of second transitional prosthesis
68. The prosthesis is completed with an occlusal scheme
that follows IPO guidelines and with occlusal contact,
corresponding to the long axis of each implant body.
LABORATORY PHASE -II
73. Completely Edentulous Patient Protocol
Before or during surgical phases, the dentist may
fabricate treatment prosthesis that restores the
patient to the proper occlusal vertical dimension .
A clear template (0.008
inch) is made over the
patient’s denture and
trimmed to the soft tissue
borders.
This acts as a
customized impression
tray and records a bite
registration to the
opposing arch
74. A two-piece transfer coping engages the hexagon of the implant
body.
A closed-tray impression is made with the customizedimpression
tray over these implant body transfers
FIRST PROSTHETIC APPOINTMENT
76. The impression transfer
copings are attached to
the implant analogue,
poured, and mounted to
the opposing arch with
the customized
impression tray.
The final abutments
are selected and
prepared for
parallelism and tooth
position.
LABORATORY PHASE-1
77. First transitional restoration is
made over the prepared
implant abutments.
• The transitional prosthesis
does not have a cantilever.
• Pontics should be left out of
occlusion.
• No contacts during excursive
movements.
• Only implants that can be
loaded with axial forces with in
20 degrees should exhibit
occlusal forces.
LABORATORY PHASE -1
78. The laboratory-prepared
abutments are positioned
over the anti-rotation
component of the implant
body and are secured
with an abutment screw
at 30 N-cm of torque.
• Check the incisal edge position of transitional prosthesis –I .
• If satisfactory , then make a final impression before cementation
of the prosthesis
SECOND PROSTHETIC APPOINTMENT
79. • The first transitional restoration, without
cantilever, is delivered.
• The patient is instructed to limit the diet to
only soft food.
80. Laboratory phase II
Master cast is mounted on an articulator using a face-bow and
centric registration
.
A wax-up of the final restoration is made.
The metal framework is then fabricated.
White wax may be used for the shape and size of the six anterior
teeth.
Acrylic occlusal indices are fabricated on the posterior regions
81. • At the metal try-in appointment, the
framework of the prosthesis is
evaluated.
• White wax is used to evaluate
the incisal edge position.
• Acrylic posterior indexes are used to
evaluate the occlusal vertical
dimension and centric occlusal
registration
3rd PROSTHETIC APPOINTMENT METAL TRY-IN & TRANSITIONAL PROSTHESIS-II
82. • Light centric occlusion in pontic areas and
angled abutments.
• Heavier contacts on the implants in ideal
position.
• No cantilevers.
• Continue with soft diet.
TRANSITIONAL PROSTHESIS -II
85. Aim: To update and summarize the progressive loading
protocols and to describe its possible effect on dental implant
success.
Conclusion: According to All authors progressive loading
produces less crestal bone loss and tends to high bone density
around dental implants placed in low density bones.
A Vergara-Buenaventura- A literature review on
progressive loading ,Journal of osseointegration Sep
2019.11(3).
Review of Literature
86. Turner PS, Nentwig GH. Evaluation of the value of bone
training (progressive bone loading) by using the Periotest: A
clinical study.ContempClinDent.2014 Oct;5(4):461-5.
Turner et al. used the Periotest to study implant mobility in
the progressively loaded and conventionally loaded group
and recommended the use of PL when there is poor bone
quality.
Review of Literature
87. Appleton RS, Nummikoski PV, Pigno MA, et al. A radiographic
assessment of progressive loading on bone around single
osseointegrated implants in the posterior maxilla. Clin Oral
Implants Res. 2005 Apr;16(2):161-7.
In 2005, Appleton et al. conducted a study to compare the
effectiveness of PL versus direct load to preserve crestal bone loss
and improving peri-implant bone density around dental implants
supporting single tooth restorations after a healing period of 5
months. They demonstrated that progressively loaded group
reported less crestal bone loss (0.2 ±0.27 mm) compared to
conventional loading (0.59±0.27 mm). These differences were
statistically significant (P ≤ 0.05).
Review of Literature
88. CONCLUSION
PL produces less crestal bone loss and produce to
high bone density around dental implants.
PL may stimulate bone
growth and maturation
Benefits in bone
quality and
density
Use of gradual loading is
recommended especially in bones with
low density.
89. • Carl E Misch: Contemporary Implant Dentistry.pp 913-937.
• W E Roberts: Fundamental principles of bone physiology, metabolism and
loading.
• Appleton RS, Nummikoski PV, Pigno MA, et al. A radiographic assessment of
progressive loading on bone around single osseointegrated implants in the
poterior maxilla. Clin Oral Implants Res. 2005 Apr;16(2):161-7.
• Turner PS, Nentwig GH. Evaluation of the value of bone training (progressive
bone loading) by using the Periotest: A clinical study. Contemp Clin Dent. 2014
Oct;5(4):461-5.
• A Vergara-Buenaventura- A literature review on progressive loading ,Journal of
osseointegration Sep 2019.11(3).
References
