1. 8. Implants in Irradiated Tissues
John Beumer III, DDS, MS
Division of Advanced Prosthodontics,
Biomaterials and Hospital Dentistry
UCLA School of Dentistry
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2. Implants in Irradiated Tissues
Table of Contents
 Radiation effects and impact on osseointegration
 Changing methods of radiation delivery and the
impact of chemoradiation
 Patient selection criteria
 Animal studies
 Human data
 Osteoradionecrosis
 Role of HBO
 Timing of implant placement
 Irradiation of existing implants

3. Osseointegration
Success requires primary implant anchorage and immobilization, the
formation of a clot between the surface of the implant and the osteotomy
site, release of growth factors, angiogenesis and migration of
osteoprogenitor cells to and deposition of bone on the surface of the
implant and in the osteotomy site.
Osteoblasts
Mineral deposition
Non-collagenous
matrix
Collagen matrix

4. Osseointegrated Implants
 These biologic processes may be compromised or
absent in patients exposed to high dose radiation
and as a result anchorage of implants in bone is
probably mechanical as opposed to biological.
 In addition, long term function of osseointegrated
implants is dependent on the presence of viable
bone that is capable of remodeling and turnover as
the implant is subjected to stresses associated with
supporting, retaining, and stabilizing prosthetic
restorations. These processes are compromised or
perhaps entirely lacking in heavily irradiated bone.

5. Radiation effects
 Reduced vasculature Lamellar bone
 Loss of osteoprogenitor • Loss of central artery in
Haversian systems
cells • Death of osteocytes
 Marrow undergoes fatty
and fibrous degeneration
 Periosteum becomes
acellular and loss of
vasculature
Trabecular bone
Root
surface
Marrow

6. Radiation effects
These tissue changes lead to: Lamellar bone
• Loss of central artery in
 Compromised remodeling Haversian systems
• Death of osteocytes
 Response to infection is
compromised ie
osteoradionecrosis
 Continuing osteolytic activity
Root
Trabecular bone
surface
Marrow

7. Why are these changes important?
 Anchorage may be mechanical as opposed to biologic
 Response to infection is compromised
 Remodeling apparatus is not fully functional
 Response to occlusal forces is compromised
 Osteolytic activity continues and compromises the density
of the bone
Root Trabecular bone
surface
Marrow

8. Continued osteolytic activity
 The density of bone is diminished because bone resorption
continues secondary to the presence of isolated osteoclasts
making it more difficult to achieve primary stability of the
implant.

9. Remodeling apparatus – Osteolytic Activity
This patient received 70 Gy
to the mandible for an anterior
floor of mouth Sq Ca.
Note the dramatic change in
the prominence of the cortical
Preradiationplates (arrows) and the
differences in trabecular
patterns between preradiaton
and postradiation radiographs.
Osteolytic activity seems
more prominent in patients
treated with chemoRT
Postradiation

10. Remodeling apparatus – Osteolytic Activity
Postradiation
Hence in irradiated sites initial stabilization of
the implants is more difficult to achieve
In edentulous patients the irradiated mandible is
more susceptible to fracture

11. Remodeling apparatus – Osteolytic Activity
 Patient received 60 Gy. The mandible fractured through the left
posterior implant site (arrow) two weeks following implant
placement.
It was reduced and repaired as
shown with eventual healing. An
implant assisted overlay denture
was later fabricated and used
successfully by the patient.

12. The tissue changes are dose dependent and the
dose depends in part upon:
Mode of therapy
 CRT (Conventional radiation therapy)
 IMRT (Intensely modulated radiation therapy)
 Brachytherapy
In edentulous patients the preferred implant
sites are:
Symphyseal region of the mandible
Premaxilla
The mode of therapy will determine the dose
delivered to these regions and dose is the best
predictor of long term success and the risk of ORN.

13. Changing methods of radiation delivery
Conventional radiation therapy (CRT)
 200 cGy per fraction
 Bilateral opposed equally weighted fields
 Total doses Source: www.beaumonthospital.com
 7000 cGy definitive dose
 5000-6000 cGy post op
Intensity modulated radiation therapy (IMRT)
This technique uses multiple radiation
beams of non-uniform intensities. The
beams are modulated to the required
intensity maps for delivering highly
conformal doses of radiation to the
treatment targets, while limiting dose
normal tissue structures.
Source: www.beaumonthospital.com

14. IMRT dosimetry diagrams
Note the hot spot on anterior mandible (oval).
 With IMRT the dose distribution is not uniform.

15. (CRT) Chemoradiation (IMRT)
Source: www.beaumonthospital.com Source: www.beaumonthospital.com
• Used in combination with CRT or IMRT
• Full course of concomitant chemoradiation is theoretically
equivalent to an additional 7-10 Gy (Kashibhatla, 2006; Fowler,
2008).
Consequences (particularly with CRT):
The biologically equivalent dose (BED) is raised leading to more short
term and long term side effects (mucositis, fibrosis, trismus,
velopharyngeal incompetence, osteoradionecrosis etc).

16. Implants in Irradiated Tissues
Issues to consider
 Potential benefit to the patient
 What are the objectives and wishes of
the patient?
 Risk – reward ratio?
 Risk of osteoradionecrosis?
 Morbidity?
 Short term success rates?
 Long term success rates?

17. Risk vs Reward Edentulous
Maxillectomy Patients
 As indicated by the following data, without implants to help retain and
stabilize the complete denture-obturator prosthesis, mastication is not
restored
 With the retention provided by the implants mastication levels are restored
to presurgical levels of function (Garrett et al, 2008).
 The risk of osteoradionecrosis secondary to implant placement is very low.
 Since the risk is minimal and the rewards are significant we do not hesitate
to recommend the use of implants in patients with palatal defects that have
been irradiated.

18. Masticatory Performance
Maxillectomy
N=5
(‘0’ score if not able to chew)
50 46.2
45 40.5
% performance
40
35
30
Defect
25
Intact
20 15.6
15
8.2 8.8
10 6.2 6.6 8.1
5
0
Entry Post-Surgery Post-CP Post-IP
Garret et al, 2008 *p<0.01

19. Masticatory Performance
Maxillectomy
N=5
(‘0’ score if not able to chew) * *
50 46.2
45
% performance
40.5
40
35
30
Defect
25
Intact
20 15.6
15
8.2 8.8
10 6.2 6.6 8.1
5
0
Entry Post-Surgery Post-CP Post-IP
Garret et al, 2008; Garrett et al, 2009 *p<0.01

20. Tongue-Mandible Defects
Reconstructed with Free Flaps
Patients with dentition on the unresected side
 As indicated from the following data you can see that patients retain their
ability to masticate effectively on the nonresected side after mandibular
reconstruction.
 Implant placement on the fibula side does not add substantially to their
mastication efficiency.
 In addition if the tongue is restored with the flap the patient lacks the
sensory and motor innervation to control the food bolus on the resected
side.
 The risk reward ratio is not as favorable and therefore in most such
situations we therefore recommend a conventional RPD when the implant
sites have been heavily irradiated.

21. Masticatory Performance
Fibula free flaps - Mandible (dentate patients)
(“0” if unable to attempt test; n=15)
% performance
45 Defect
40 Intact 41.6
36
35 34.5
30 32.7
25
21.1 24.9
20 20.3
15
10
5 7.3
0
Entry Post-Surgery Post-CP Post-IP Garrett et al, 2005

22. Tongue-Mandible Defects Reconstructed
with Free Flaps - Edentulous Patients
The functional benefit derived from implant placement in
irradiated edentulous patients depends on several factors, the
most important being the status of tongue function.
 If the tongue and/or mandible has been resected and reconstructed and the bulk,
mobility and control of the reconstructed tongue results in reasonable tongue
function, the placement of implants may significantly improve mastication
performance particularly if the denture bearing surface has been compromised or is
not ideal.

23. Tongue-Mandible Defects Reconstructed with
Free Flaps - Edentulous Patients
 Patient had hemiglossectomy and reconstruction of tongue with
a free flap and received 55 Gy post operatively.
 Tongue bulk is restored and tongue mobility is excellent
 Without implants use of a lower complete denture would have
been problematic.
 The dose is low. The risk reward ratio is favorable and
therefore in such patients implants were placed to stabilize and
retain the denture.
Note: The patient must masticate on the sensate unresected side.

24. Facial Prostheses – Quality of retention
Quality of life
When patients present with facial defects implant retention improves
patient satisfaction and frequency of use (Chang et al, 2005).
With large combination facial defects adhesive retention is ineffective and
implant retention is required for most patients
Although the implant loss rates are high the benefits are great particularly in
patients with large facial defects such as this one.
Therefore, we recommend the placement of implants in most patients with
large facial defects even though the implant sites have been irradiated.

25. Facial Prostheses - Retention During Daily Activities
* Adhesive Implant
*
95 *
100 89
90 84 85
79
80
70 63
57
60
% 'Excellent'
50 44 44
38
40
30
20
10
0
Chang et al, 2005 Home Eating Exercise Perspire Sneeze/Cough

26. Frequency of Wear Facial Prostheses
Chang et al, 2005
Adhesive Implant
120
95 100
100 89 88
80 *63
% Wearing
60 44
40
20
3 0
0
Home Work Social Never

27. Implants in Irradiated Tissues
Biologic viability (animal studies)
 Hum and Larsen, (1990)
 Weinlander et al, (2006)
 Nishimura et al, (1996)
 Asikainen et al, (1993)
 Ohrnell et al, (1997)
 Jacobsson et al, (1988)

28. Implants in Irradiated Tissues
Biologic viability (animal studies)
Asikainen, 1998
 Dogs received either 4000, 5000, or 6000 cGy
 Two months later TPS screw type implants were
inserted
 Four months later the implants were loaded
 Success rates:
 4000 cGy group – 100%
 5000 cGy group – 20%
 6000 cGy group – 0 %

29. Implants in Irradiated Tissues
Weinlander et al, (2006)
 Dogs were partially edentulated
 Following a suitable healing period three implants were
placed on each side
 All seven dogs received radiation therapy, starting three
weeks post implantation on one side of the mandible,
consisting of a dose equivalent to 5000 cGy delivered in 4
fractions during a 2 week period

30. Methods – Histomorphometric Calculations
 A scanning electron
microscope was used
to image the
background electron
density of the three
elements – bone, soft
tissue and implant.
The histometry calculation yielded volume
and boundary fractions for the implant, bone
and soft tissue components.
Weinlander et al, 2006

31. Bone contact area in control specimens
80
70
60
50
40 Bone
30 Appositional
Index %
20
10
0
Machined Plasma HA
Surface Spray Coated
Weinlander et al,

32. Bone contact area in irradiated tissue
70
60
50
40
Bone
30 Appositional
20 Index %
10
0
Machined Plasma HA
Surface Spray Coated
Weinlander et al,
2006

33. Nishimura et al,1996
Dosage of Radiation Therapy Administered
A rabbit tibia model was used in this study. The rat tibia were
exposed to equivalents of the following doses and implants were
placed 3 months following completion of radiation treatments.
Polyfluorochrome labeling was performed three months after
implant placement and the animals sacrificed 2 days later,
(cGy)
4000 5800
4600 6400
5200 7000

34. Nishimura et al, 1996
Results
Normal 5200 cGy 5800 cGy
Three months after implant placement the tissue samples were
harvested and were evaluated with light and fluorescent
microscopy. Fluorochrome labeling documented a steady
decrease in biologic activity at the higher doses.

35. Nishimura et al, 1996
Results
Normal bone Irradiated bone
At lower doses irradiated specimens had more
woven bone at the bone implant interface than did
the normal specimens at the time of sacrifice.

36. Additional animal studies (summaries)
 Jacobsson et al (1988) - Reduction in bone
formation capacity, an increase in bone
resorption and a reduction in the number of
capillaries.
 Ohrnell et al (1997) - Fibrosis of the bone
marrow, bone resorption, less bone adjacent to
the implants and an overall reduction in the
remodeling capacity of bone.
 Hum and Larsen (1990) - The bone contact area
for irradiated specimens was significantly less
than nonirradiated specimens

37. Summary of tissue changes affecting
osseointegration based on animal studies
 At higher doses (70 Gy) virtually little or no bone will be
deposited on the implant surface. Anchorage is primarily
mechanical as opposed to biologically driven.
 At lower doses a greater component of woven bone is seen in
the interface. Compromise of the remodeling apparatus may
preclude this woven bone from being replaced with lamellar
bone
 Death of osteocytes, loss of osteoprogenitor cells and the basic
multi-cellular unit of the remodeling apparatus (BMU)
compromises the remodeling of bone at the bone implant
interface and compromises the bone’s response to occlusal
load.

38. Summary of tissue changes affecting
osseointegration based on animal studies
• Poor blood supply in the marrow predisposes
to infection and implant loss
• At lower doses radiation induced tissue effects
significantly reduced the bone appositional
index as compared to controls and probably
compromise implants load bearing capacity.

39. Disclaimer
 No animal model truly reflects human biology. Lower form
vertebrates are more tissue and vascular tolerant of radiation
damage than humans.
Using the mathematical biologic equivalent of human doses
in a single administration or using fewer fractions with large
doses, serves a mathematical purpose but does not
guarantee biologically equivalent outcomes.
Animal studies have yet to be reported assessing
the impact of chemoradiation on osseointegration.

40. Anticipated outcomes in humans based on
animal studies
 Because anchorage is essentially mechanical as opposed to
biologic, the load carrying capabilities of osseointegrated
implants in irradiated bone will be less than seen in
nonirradiated bone.
 The success rates of osseointegrated implants in irradiated
bone should be less than that seen in nonirradiated bone. The
higher the dose, the more profound the tissue changes and the
lower the success rates.

41. Anticipated outcomes in humans based on
animal studies
 In the mandible at higher doses (above 6500 cGy with
conventional fractionation) the risk of osteoradionecrosis
is most likely quite significant.
 Because of essentially mechanical anchorage and
compromise of the remodeling apparatus of bone, late
implant failures should be expected, even in good quality
bone sites such as the anterior mandible

42. Anticipated outcomes in humans based on
animal studies
 Persistent osteoclastic activity secondary to residual
functioning osteoclasts leads to bone which is less dense,
and therefore initial anchorage and stabilization may be
difficult to achieve in irradiated sites.
 Because of the compromised remodeling apparatus and
impaired anchorage, long term clinical observations will be
needed to properly assess the success-failure rates of
implants in irradiated tissues

43. Human studies
 Yerit et al, 2006
 Roumanas et al, 1997 (Maxilla)
 Roumanas et al, 2002 (Craniofacial sites)
 Nimi et al, 1998 (Maxilla)
 Esser et al, 1997 (Mandible, maxilla)
 Granstrom et al, 1994 (Craniofacial sites)
 Granstrom, 2005 (All sites)

44. Implants in irradiated mandible
Yerit et al, 2006 (Pt base 1990-2003)*
 Patients – 71
 Dose 5000 cGY
 Number of implants - 316
 Implant survival
• Nonirradiated – 95%
• Irradiated sites – 72%
*HBO was not used

45. Implants in irradiated mandible
Yerit et al, 2006 (Pt base 1990-2003)*
Success rates – Irradiated sites -154 implants)
 93% at 1 year
 90% at 2 years
 84% at 5 years
 72% at 8 years followup. The survival rates for the 84
implants placed
Success rates - nonirradiated residual mandibular
sites (84 implants)
 99% at one year
 99% at 2 years
 99% at 5 years
 95% at 8 years followup

46. Implants in irradiated mandible
Esser and Wagner, 1997
Post op dose (CRT) – up to 6000 cGy
Opposed mandibular fields – Symphysis?
Pts - 58 (from 1985-1995)
Implants placed – 221
Implants lost – 32
Before loading - 18
After loading -17
Success rate 84.2%
Granstrom, 2005
63% survival rate for 15 implants placed in
the mandible *HBO was not used

47. Implants in the irradiated maxilla
Predictability-Maxilla %
 Roumanas et al, 1997* 55
 Nimi et al, 1998* 63
*Without HBO

48. Implants in edentulous maxillectomy patients
Patients Number of implants Success
Treated placed uncovered buried failed %
Irradiated 13 50 29 3 10 55.2
Non-
Irradiated 10 35 25 3 2 80.0
Totals 23 85 54 6 12 66.7
Roumanas et al, 1997
Failures in the irradiated group tend to be late, after the implants
have been loaded.

49. Implants in nonirradiated tissues
Craniofacial sites*
Implant Pts Implants Implants Implants Implants Survival
sites placed uncovered buried failed rates (%)
Auricular 35 111 97 8 5 94
Nasal 16
Piriform 27 25 0 5 80
Glabella 2 2 0 2 0
Orbital 9 28 25 2 7 70
Overall 60 172 153 10 21 85
*Roumanas et al, 2002

50. *Roumanas et al, 2002
Implants in irradiated tissues
Craniofacial sites*
Implant Pts Implants Implants Implants Implants Survival
sites placed uncovered buried failed rates (%)
Auricular 2 6 6 0 0 100
Nasal 4
Piriform 8 6 0 1 83
Glabella 2 2 0 2 0
Orbital 6 19 15 0 11 27
Overall 12 35 29 0 14 52
Failures in the irradiated group tend to be late, after the implants have been loaded.
loaded

51. Implants in the Irradiated
Supraorbital Rim
Success is poor and
failures are late
because:
 Mostly cortical bone
• Blood supply from periosteum
and is compromised
• Anchorage is primarily
mechanical
 More radiation absorption
 Compromised remodeling

52. Implant failures -Irradiated sites
Case report
Flange exposure Eventually led to loss of
implants
This patient received more than
6000 cGy to the implant sites

53. Implant failures – Irradiated sites
Auricular defects
 Flange exposure led to
loss of implants three
years post insertion
 Noteexposed bone
(ORN) (arrows)

54. Risk of osteoradionecrosis
Esser et al, 1997.
In this retrospective
analysis, 2 patients out
60 (3.4%), developed
osteoradionecrosis, both
in the mandible. All
patients received 6000
cGy with CRT
postoperatively via
opposed mandibular
fields.

55. Risk of osteoradionecrosis
Granstrom (2009)
 10 out of 116 patients – 8.6%
 Dose
• Mean 79 Gy
• 4 had two courses of radiation
• 23- 145 Gy
 Sites
• Mandible
• Orbit
• Mastoid
• Frontal bone

56. Osteoradionecrosis
Case report
This patient received 6600 cGy for a
squamous carcinoma of the lateral
tongue. Three years later implants
were placed.
Three years after
implant placement the
patient developed an
infection associated
with left posterior
implant.
Eventually, the patient developed an osteoradionecrosis, a
pathologic fracture of the mandible and subsequently the
mandible was resected.

57. Osteoradionecrosis - Mastoid
 Note exposed bone (ORN)
(arrows)
 The necrosis eventually
resolved with conservative
measures and the two
inferiorly positioned
implants failed.

58. Implants in irradiated mandible
Role of hyperbaric oxygen
The data is all retrospective, but based on the reports of
Granstrom et al (1993, 2005), there appears to be an
advantage. Success rates appear to be higher and the risk of
osteoradionecrosis may be reduced depending upon the
dosage to the implant sites.
• 63% survival rate for 15 implants placed in the mandible
without HBO
• 100% survival rate for 30 implants placed in the mandible
with pre-operative HBO therapy.

59. Impact of HBO
Granstrom 2005 -- All sites – 25 years
Implants placed Implants lost ORN
Without HBO 291 117 5
With HBO 340 29 0

60. Impact of HBO
 Periosteal blood supply improvement vs revascularizing the
marrow and repopulating it with stem cells?
 It is not known which of these two phenomenon is most important
 Success rates improved over the short term particularly in
ideal sites such as the anterior mandible
 Experience in the orbit
 Late failures with short implants even with HBO

61. Impact of HBO - Maxilla
Implants can be inserted with little or no risk of
osteoradionecrosis regardless of dose as long as
the dosage is within customary therapeutic levels.
The use of hyperbaric oxygen can be justified only
on the basis of improving success rates.

62. Time from irradiation
Impact of time – After cancerocial doses of
radiation do the tissues recover?
 At cancericidal doses the irradiated tissues do
not recover. With time the irradiated tissues
continue to deteriorate and become less
vascular, more fibrotic etc.
 The longer the time from radiotherapy the
poorer the results (Granstrom, 2005)

63. Implants in Irradiated Tissues
Recommendations
 Patient selection
Edentulous patients receive
the most benefit
Consider risk – reward ratio
Determine tumor status – 80%
of recurrences occur within the
1st year
Check the dosimetry of the
radiation

64. Implants in Irradiated Tissues
Recommendations
 Longer implants are recommended
 Use more implants than the usual
number
 Splint implants together with rigid
frameworks
 Implant assisted tissue bar designs
are preferred with overlay dentures
 No cantilevers
 HBO or pentoxyfilline-tocopherol
protocol recommended to improve
success rates and reduce risk of
ORN

65. Implants in the irradiated mandible
Doses 5500 cGy and below
 Implants can be inserted with little or no risk of osteoradionecrosis
 Success rates will be probably be 15-20% lower than normal
Doses between 5500 and 6500 cGy
 Individual patient factors such as fractionation, tissue responses,
clinical findings, dental history etc. impact the decision. Success
rates not well documented
Doses above 6500 cGy
 The risk of osteoradionecrosis becomes significant and implants
should not placed unless HBO is given.
 In such patients the success rates have been in the 75-80%
range with little osteoradionecrosis seen.

66. Implants in the irradiated edentulous mandible
At doses above 55 Gy
anchorage is probably primarily
mechanical as opposed to
biologic.
Without HBO long term
success rates may be
problematic (Granstrom, 2005; Yerit
et al, 2006)
Therefore if implants are used
we recommend:
 Four implants splinted together with a implant assisted
overlay denture.
 In this design the “Hader” segment anteriorly serves as the
axis of rotation. The resilient “ERA” attachments
posteriorly allow the prosthesis to rotate around the Hader
segment when posterior occlusal forces are applied.

67. Implants in the irradiated mandible
Patient had hemiglossectomy and reconstruction
of tongue with a free flap and received 55 Gy
post operatively. Without implants use of a
complete denture would have been problematic.

68. Implants irradiated maxillary sites
 Risk of osteoradionecrosis is negligible unless the doses are
extremely high (above 7500 cGy)
 Success rate has generally been less than the mandible
presumably because less bone density and depends on:
 Dose to bone
 Load biomechanics, etc.
 Quality and quantity of bone
 Implant length
For maxillectomy patients
Splint implants together with rigid frameworks
Tissue bars should be implant assisted

69. Implants - Irradiated craniofacial sites
Floor of nose
 Little biomechanical stress
 Success rates will probably be
60-80% depending on the dose
Mastoid
 Little biomechanical stress but
implants are short
 Success rates will probably be
60-80% depending on the dose
Supraorbital rim
 All cortical bone
 Success rates will be very low,
long term, probably less that 25%

70. CRT - Implants in irradiated patients
vs implants in the radiation field
Check fields and dose
 Fields are often reduced in size as treatment progresses
Implants can be placed in the anterior mandible and anterior maxilla in such
patients and the success will be equivalent to normal non irradiated patients

71. CRT - Implants in irradiated patients vs
implants in the radiation field
 These implants were positioned anterior to the field of
radiation (note the pattern of hair loss).

72. Radiation delivery factors - IMRT
Check dosimetry
Dose varies considerably and
there may be hot spots in unusual
areas
3 fields 5 fields 7 fields

73. Irradiation of Existing Implants - Backscatter
These implants
were irradiated 2
years following
placement. Note
the exposure of
the implant  Dose enhancement of about 15%
flanges. within 1 mm of implant surface
(Schwartz et al, 1978:;Wang et al,1996).

74. Irradiation of existing implants- Backscatter
Implants were placed simultaneous with tumor
resection and reconstruction of this large body-
symphyseal defect with a fibula free flap. The
patient received 6000 cGy post operatively.

75. Irradiation of existing implants- Backscatter
Several months later and just after delivery of the
tissue bar, the tissues on the labial surfaces of the
implants dehisced and the bone overlying the implants
sequestrated leading to loss of the implants.

76. Irradiation of existing implants- Backscatter
Following loss of the implants, the mucosa
recovered the area. The graft remained viable and
mandibular continuity was maintained.

77. Irradiation of Existing Implants
Options
• Do nothing
• Remove the prosthesis and close the wound (Granstrom et al,
1993)
• Remove the bridge and place healing abutments on the implants
(No data is available but our experience has led us to favor we
favor this option)

78. Irradiation of Existing Implants
Remove the prosthesis and close the wound (Granstrom et al,
1993)
In this patient the fixed partial denture was removed and the
implants surgically buried beneath the mucosa. However
they soon became exposed to the oral cavity

79. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
conside
 Dose to bone anchoring the implants
 Mandible vs maxilla
 Target volume/fields
 Chemoradiation or radiation alone
 Hygiene access - Beware of posterior ridge laps
 Patient compliance issues

80. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
conside
Dose to bone anchoring the implants
If the implants are located in the mandible and the dose t
the implant sites exceeds 65 Gy the risk of ORN is
significant and replacing the prosthesis may predispose to
a high level of risk.

81. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
Mandible vs maxilla
Since the risk of ORN in the maxilla is very low and the
morbidity is minimal reinserting an implant retained
prostheses in the maxilla carries very low risk.

82. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
conside
Target volume/fields
Implants sites out of the field of radiation when CRT is
used receive virtually no radiation and implant sites
beyond the clinical tumor volume when IMRT is used will
receive lower dose. Therefore prostheses can be
reinserted in these situations in both the mandible and
maxilla with little or no risk of ORN.

83. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
conside
Chemoradiation or radiation alone
ChemoRT raise the BED (biologically equivalent dose by
700 – 1000 cGy. The implant sites are in the mandible
and exposed to these dose levels replacement of the
prosthesis may predispose to a high risk of developing an
ORN

84. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
conside
Hygiene access and patient compliance issues
Beware of posterior ridge laps of fixed implant supported
prostheses in the mandible in the marginally compliant
patient. These patient are at high risk for periimplantitis
and ORN.

85. Irradiation of Existing Implants
Remove the bridge and replace with healing abutments
 Minimizes backscatter
Following completion of radiation therapy should we
replace the bridge, tissue bar etc.? Factors to consider
conside
In summary in the mandible if the BED (biologically
equivalent dose) to the implant sites exceeds 6500 cGy we
do not recommend placing the prosthesis back into position in
most patients because compromised hygiene and the risk of
a peri-implant soft tissue infection may lead to an
osteoradionecrosis (see slide #56).
In the maxilla and craniofacial sites the prosthesis can be
reinserted with little risk to the patient.

86. Placement of implants in patients to
receive postoperative radiation.
Should the clinician place these implants at the
time of tumor ablation or wait until after the
radiation treatments have been completed?
We consider this issue from two perspectives:
Quality of implant anchorage and prospects for
long term success
Risk of osteoradionecrosis

87. Quality of implant anchorage and prospects
for long term success
This issue is debatable but from this perspective it is probably best to place
implants at the time of tumor ablation. Given the bio-reactivity of the micro-
rough or nano-enhanced surfaces the implants will become very well
anchored in bone by 6 weeks – the period of time usually employed to allow
the surgical wounds to heal prior to commencing postoperative radiation
treatments. Admittedly the dose enhancement effect will render this bone
nonvital and the implant anchorage becomes primarily mechanical.
If one delays implant placement until radiation treatments are completed
the postoperative doses used today (usually 60 Gy and above) will also
render the anchoring bone relatively nonvital and the implant anchorage will
also be primarily mechanical as opposed to biologic.
The implant anchorage of the former will be considerably better than the
later approach.

88. Risk of osteoradionecrosis
 In the mandible the risk of ORN
secondary to dose enhancement may be
significant
 If there is the chance that the postop BED
to mandibular implant sites will exceed
6500 cGy it is probably best to defer.

89. Nano-enhanced and genetically
engineered implant surfaces
Will these phenomenon be clinically
significant in the irradiated patient?
Probably not. Anchorage is mechanical as
opposed to biologic. The macro-surface
topography, the quality of bone and the skill
of the surgeon are the most critical factors.
The major problem in the irradiated patient is
loss of vasculature and fibrosis and with it the loss
of osteoprogenitor cells (mesenchymal stem cells)
in the marrow.

90. Dental development
 Levels as low as 2500 cGy effect tooth development
(Gorlin and Meskin, 1963; Pietrokovski and Menczel,
1966; Dahllof et al, 1994; Kaste et al, 1994)
 Changes reflect a variety of defects that indicate the
several stages of development existing during the
course of radiotherapy
This patient is 16 years of age. He received 3600 cGy of radiation
when he was 4 years of age for treatment of a rhabdomyosarcoma.

91. Dental development
 Levels as low as 2500 cGy effect tooth development
(Gorlin and Meskin, 1963; Pietrokovski and Menczel,
1966; Dahllof et al, 1994; Kaste et al, 1994)
 Changes reflect a variety of defects that indicate the
several stages of development existing during the course
of radiotherapy
Are these patients candidates for implants?
Yes! If t dose is below 4000 cGy.

92. Early Radiation to the Enamel Organ
Implant supported fixed partial denture
This patient was irradiated as a young child for
a rhabdomyosarcoma. She received slightly less
than 40 Gy along with several courses of
chemotherapy which arrested the development
of her permanent dentition.
Eventually all her teeth were lost or extracted
and several implants were placed in the maxilla
and mandible
PFM fixed prostheses were then fabricated

93.  Visit ffofr.org for hundreds of additional lectures
on Complete Dentures, Implant Dentistry,
Removable Partial Dentures, Esthetic Dentistry
and Maxillofacial Prosthetics.
 The lectures are free.
 Our objective is to create the best and most
comprehensive online programs of instruction in
Prosthodontics

94. Coming soon
Implant Biomechanics and Treatment
Planning in partially Edentulous Patients
Abutment selection in partially edentulous
patients
Early and Immediate loading

95. References
 Garrett N. (2008) Outcomes of Maxillectomies with conventional and implant
restorations. Presented at International Congress on Maxillofacial Rehabilitation
Bangkok, Thailand September 24-27.
 Garrett NR, Kapur K, Hamada M, et al. (1998) A randomized clinical trial
comparing the efficacy of mandibular implant supported overdentures and
conventional dentures in diabetic patients. Part II. Comparisons of masticatory
performance. J Prosthet Dent 79:632-40.
 Geertmen M, Slagter A, van Waas M et al. (1994) Comminution of food with
mandibular implant-retained overdentures. J Dent Res 73:1858-64.
 Geertmen M, Marinus A, van Waas M et al. (1996) Denture satisfaction in a
comparative study of implant-retained mandibular overdentures: A randomized
clinical trial. J Oral Maxillofac Implants 11:194-200.
 Chang T, Garrett N, Roumanas E, et al. (2005) Treatment satisfaction with
facial prostheses. J Prosthet Dent 94:275-80.
 Jacobsson M, Tjellstrom A, Thomson P, et al. (1988) Integration of titanium
implants in irradiated bone. Histologic and clinical study. Ann. Otol. Rhinol.
Laryngol. 97:337-40.
 Hum S, Larsen P. (1992) The effect of radiation at the titanium/bone interface.
In: Tissue integration in oral, orthopedic and maxillofacial reconstruction. ed. by
Laney, W. and Tolman, D. Quintessence Publishing Co. Chicago. pp.234-9.

96. References
 Nishimura R, Roumanas E, Sugai, T et al. (1996) Nasal defects and
osseointegrated implants: UCLA experience. J Prosthet Dent 76:597-602.
 Asikainen P, Kotilianinen R, Vuillemin, et al. (1993) Osseointegration of dental
implants in radiated mandibles: An experimental study with beagle dogs. J Oral
Implant 17:48-54.
 Weinlander M, Beumer J, Kenney B, et al. (2006) Histomorphometric and
fluorescence microscopic evaluation of interfacial bone healing around 3
different dental implants before and after radiation therapy. Int J Oral
Maxillofac Implants 21:212-24.
 Parel S, Tjellstrom A. (1991) The United States and Swedish experience with
osseointegration and facial prostheses. Int J Oral Maxillofac Implants 6:675-9.
 Roumanas E, Nishimura, R, Beumer J. (1994) Craniofacial defects and
osseointegrated implants: Six year follow-up report on the success rates of
craniofacial implants at UCLA. Int J Oral Maxillofac Implants 9:579-85.
 Granstrom, G., Jacobsson, M., Tjellstrom, A. (1992) Titanium implants in
irradiated tissue: Benefits from hyperbaric oxygen. Int J Oral Maxillofac Implants
7:15-25.
 Granstrom G, Bergstrom K, Tjellstrom. (1994) A detailed analysis of fixture
losses in irradiated tissue. Int J Oral and Maxillofac Implant 9:653-62

97. References
 Roumanas E, Nishimura R, Davis B, et al. (1997) Clinical evaluation of
implants retaining edentulous maxillary obturator prostheses. J Prosth Dent
77:184-90.
 Esser E, Wagner W. (1997) Dental implants following radical oral cancer
surgery and adjuvant radiotherapy. Int J Maxillofac Implants 12:552-57.
 Nimi A, Ueda M, Kaneda T. (1993) Maxillary obturator supported by
osseointegrated implants placed in irradiated bone. Report of cases. J Oral
Maxillofac Surg 51:804-9.
 Nimi A, Ueda M, Kaneda T. (1998) Maxillary obturator supported by
osseointegrated implants placed in irradiated tissues: A preliminary report. Int J
Oral Maxillofac Implants 13:407.
 Visch L, van Waas M, Schmitz P, et al. (2002) A clinical evaluation of implants
in irradiated oral cancer patients. J Dent Res 81:856-59.
 Roumanas E, Freymiller E, Chang T, et al. (2002) Implant retained
prostheses for facial defects: An up to 14 year followup report on the survival
rates of implants at UCLA. Int J Prosth 15:325-32.
 Granstrom G. (2005) Osseointegration in irradiated cancer patiens: An
analysis with respect to implant failures. J Oral Maxillofac Surg 63:579-85.

98. References
 Yerit K, Posch M, Seemann S, et al. (2006) Implant survival in mandibles or
irradiated oral cancer patients. Clin Oral Impl Res 17:337-44.
 Visser A. (2007) Aftercare of implant-retained facial prostheses. In
Proceedings of Maxillofacial Rehabilitation-New technologies improve quality of
life? University Medical Center, Groningen. Abstract #11.
 Salinas TJ, Valmont PD, Katsnelson A, et al. (2010) Clinical evaluation of
implants in radiated fibula free flaps. J Oral Maxillofac Surg 68:524-9.
 Flood T, Downie I, Ethunandan M. (2009) Prosthetic reconstruction after
rhinectomy-evolution of bone anchored epistheses and adjunctive surgical
techniques in nasal reconstruction from one unit. (Presentation at the 2nd
International Symposium. Bone Conduction Hearing-Craniofacial
Osseointegration. June 11-13, 2009, Gothenburg, Sweden (Abstract O-24. pp
32).
 Proops D, Worrollo S, Jeynes P et al. (2009) Head and neck reconstruction in
adults-The Birmingham experience. (Presentation at the 2nd International
Symposium. Bone Conduction Hearing-Craniofacial Osseointegration. June
11-13, 2009, Gothenburg, Sweden (Abstract O-22 pp 31).
 Marx R. (1993) Preprosthetic surgery in a radiated cancer patient. (abstract #
61) In: Proceedings of the 5th International Congress on Preprosthetic Surgery.
15-18 April, Vienna: 75.

99. References
 Granstrom G. (2006) Placement of dental implants in irradiated bone: The
case for using hyperbaric oxygen. J Oral Maxillofac Surg 64:812-18.
 Dudziak M, Saadeh P, Mehara B et al. (2000) The effect of ionizing radiation on
osteoblast-like cells in vitro. Plast Reconstr Surg 106:1049-61.
 Donoff RB. (2006) Treatment of the irradiated patient with dental implants: The
case against hyperbaric oxygen treatment. J Oral Maxillofac Surg 64:819-22.
 Nishimura R, Roumanas E, Sugai T, et al. (1995) Auricular prostheses and
osseointegrated implants: UCLA experience. J Prosthet Dent 73:553-58.
 Nishimura R, Roumanas, E, Sugai T, et al. (1998) Osseointegrated implants
and orbital implants: UCLA experience. J Prosthet Dent 79:304-9.
 Kirk I, Gray W, Watson E. (1971) Cumulative radiation effect. Clin Radiol
22:145-55.
 Schwartz H, Wollin M, Leake D, et al. (1979) Interface radiation dosimetry in
mandibular reconstruction. Arch. Otolaryngol. 105:293-5.
 Miam TA, Van Putten MC, Kramer DC et al. (1987) Backscatter radiation at
bone titanium interface from high energy X and gamma rays. Int J Radiol Oncol
Biol Phys 13:1943-47.
 Granstrom G, Tjellstrom A, Albrektsson T: (1995) Post implant irradiation of
osseointegrated implants. In proceedings of the First International Congress on
Maxillofacial Prosthetics. Eds Zlotolow I, Esposito S, Beumer J. pp 292-6.

100. The End
Thank you for your kind attention