periodontology

1. Iatrogenic Factors in
Periodontal Disease
Prepared by:
Lobna El Saadawy

2. Outline
 Definition
Common factors:
1. Margins of the restoration
2. Contour and open contact
3. Restorative material
4. Design of the removable partial denture
5. Restorative dentistry procedure
6. Malocclusion
7. Orthodontic therapy
8. Extraction of impacted third molar
9. Habits and self-inflicted injuries
10. Radiation therapy

3. Definition
Inadequate dental procedures that
contribute to the deterioration of the
periodontal tissues are referred to as
iatrogenic factors

4. 1. Margins
of the
restoration
I. Overhanging restoration
II. Location of the margin
III. Marginal roughness

5. A) Overhanging
margins
1) Inhibit the
patient’s
access to
remove
accumulated
plaque

6. Overhanging
margins
1) Change the ecologic
balance of the gingival
sulcus to an area that
favors the growth of
disease-associated
organisms (predominately
gram negative anaerobic
species) at the expense of
the health associated
organisms (predominately
gram-positive facultative
species)

7. B) Location of the gingival
margin
Subgingival
margins
Equigingival
margins
Supragingiv
al margins
Severe
gingivitis
and deep
pockets
Less
severe
gingivitis
Normal as
in natural
teeth

8. C) Marginal Roughness
Sources of marginal roughness include
i. Grooves and
scratches in the
surface of even
a carefully
polished
restoration ex:
porcelain or
gold restoratian

9. c) Marginal Roughness
Sources of marginal roughness include
ii. Inadequate marginal fit of the
restoration
*subgingival margins typically shows a gap of
20-40 um between the margin of the
restoration and the unprepared tooth surface
that favors bacterial plaque colonization

10. C) Marginal Roughness
Sources of marginal roughness include:
iii. The gap that exposes the rough prepared
tooth structure following the dissolution of
the luting cement at the restoration margins
SEM photomicrograph of the
cervical margin of a 5-year old
porcelain veneer (P) showing a
small marginal defect and a border
of roughened porcelain (arrows).
(G, gingiva; C, luting composite)

12. 2.
Contour
and
Open
Contacts
I. Overcontoured Crowns
Buccal and lingual contours
Occlusal contours
II. Inadequate interproximal embrasure

13. I. Overcontoured Crowns
Overcontoured crowns and
restorations tend to accumulate plaque
and possibly prevent the self-cleaning
mechanisms of the adjacent cheek,
lips, and tongue

14. a) Buccal and Lingual
Contours
Overcontoured
Undercontoured
Prevent self
cleansing
mechanism of the
cheeks, lips and
tongue
Does not have that
much destructive
effect

15. But under contoured restorations with 
absent or shallow buccal deflection ridge
are said to cause gingival trauma due to
injury by rough food

17. b) Occlusal Contours
Established by marginal ridges
and related developmental
grooves.
Normally they deflect food away
from the inter proximal spaces

18. Occlusal Contours
Inappropriate occlusal contours leads to
Food impaction
Plaque retention
Food impaction is defined as the forceful wedging
of the food into the periodontium by occlusal forces
Cusps that tend to forcibly wedge food into
interproximal embrasures are known as plunger
cusps.

19. Occlusal Contours
Factors leading to food impaction made
by Hirschfeld:
Uneven occlusal wear.
 Open contact area as a result of the
loss of proximal support or from
extrusion
 Congenital morphologic
abnormalities
 Improperly constructed restorations

20. II. Inadequate interproximal
embrasure
associated with papillary inflammation

22. 3.
Restorative
Material

23. Restorative materials are not in
themselves injurious to the periodontal
tissues. One exception to this may be
self-curing acrylics
• Plaque retention capacity of different
restorative materials is different
but yet can be controlled if the
restoration was well polished and was
accessibile to oral hygiene measures

24. The undersurface
of pontics in fixed
bridges should
barely touch the
mucosa.
Access for oral
hygiene is
inhibited with
excessive pontic
to tissue contact.

25. 4. Design of
Removable
partial
denture

26. Removable partial dentures favor
plaque accumulation resulting in:
 gingival inflammation
 periodontal pocket formation
 mobility of the abutment teeth.

27. Partial dentures that are worn during
both night and day induce more
plaque formation than those worn
only during the daytime
The presence of removable partial
dentures induces both quantitative
and qualitative changes in dental
plaque promoting the emergence of
spirochetal microorganisms

28. Spirochetes are gram-negative bacteria that are 
long, thin and spiral-shaped. some of them are
pathogenic to humans.
There is one species of spirochete that is part of the 
natural environment of the human mouth called
Treponema denticola.

Although T. denticola is typically not harmful,but 
under certain conditions , it may play a role in the
progression of periodontal disease
It is one of the red complex pathogens . 

29. 5.
Restorative
Dentistry
Procedures

30. The use of rubber dam clamps,
matrix bands, and burs in such a
manner as to lacerate the gingiva
results in varying degrees of
mechanical trauma producing
transient injuries that generally
undergo repair

31. Forceful packing of a gingival retraction
cord into the sulcus to prepare subgingival
margins on a tooth or for the purpose of
obtaining an impression may
mechanically injure the periodontium and
leave behind impacted debris capable of
causing a foreign body reaction.

32. 6. Malocclusion

33. Irregular alignment of
teeth results in more
difficult plaque control
Several authers
found a positive
correlation between
crowding &
periodontal disease
but others didn’t find
any correlation.

34. Occlusal Disharmonies
Restorations that doesn’t conform to the
occlusal pattern of the dentition may cause
injury to the supporting periodontal tissues
(traumatic occlusion – T.F.O.)
Histological features of the periodontium of atooth
subjected to T.F.O. :
widened PDL space,
Reduction in the number of collagen
content in oblique and horizontal fibers
 increase in vascularity and leukocyte
infiltration,
increase in the number of osteoclasts on
bordering alveolar bone.

35. Failure to replace posterior teeth
After the extraction
of mandibular 1st
molar with the
failure to replace :
1) the initial change
is a mesial drifting
and tilting of the
mandibular second
and third molars
2) extrusion of the
maxillary first molar

36. Failure to replace posterior teeth
3) As the mandibular second molar tips
mesially, its distal cusps extrude and act as
plunger
4) The distal cusps of the mandibular second
molar wedge between the maxillary first and
second molars and open the contact by
deflecting the maxillary second molar
distally.

38. 7. Periodontal
complications
associated
with
orthodontic
therapy
I. Direct effect
II. Indirect effect

39. I. Indirect
Effect
i. Favoring plaque
retention and
food debris.

40. ii. Modifying the gingival
ecosystem resulting in
gingivitis
An increase in
Prevotella Odontolyticus
Prevotella Intermedia
 Actinomyces Odontolyticus
Aggregatibacter
actinomycetemcomitans
*With the decrease in
facaulitative microorganisms

41. II. direct effect
i. Creating excessive and/or
unfavourable forces on teeth and
supporting structures
Excessive force produce:
 necrosis of PDL and adjacent alveolar bone
 increase the risk of apical root resorption
Risk factors for root resorption include :
magnitude of force ,duration of treatment ,continous
versus intermittent force .
Direction of tooth movement ??????

42. ii. Orthodontic bands placed on
newly erupted permanents with still
attached junctional epithelium on
enamel will result in apical
migration & proliferation of the
junctional epithelium and an
increased incidence of gingival
recession

43. The mean alveolar bone loss for
adolescents who under went 2 years of
orthodontic treatment ranges from 0.1- 0.5
mm (this is found to be of little significance)
as that also noted for the control groups
The degree of bone loss during adult
orthodontic care may be higher than that
observed in adolescents,
especially if
the periodontal condition is not treated
before initiating orthodontic therapy.

44. III. Other effects
($) Surgical exposure of impacted
teeth and orthodontic-assisted
eruption has the potential to
compromise the periodontal
attachment on adjacent teeth .
However , those teeth have more
than 9o% of their attachment
remains intact

45. ($) It has been reported that the dentoalveolar 
gingival fibers that
are located within the marginal and attached 
gingiva are stretched
when teeth are rotated during orthodontic therapy 
Surgical removal of these gingival 
fibers in combination with a brief
period of retention
may reduce the incidence of relapse 
after orthodontic treatment intended
to realign rotated teeth

46. 8)
Extraction
of
impacted
third
molars

47. Extraction of impacted third molars
often results in
1) the creation of vertical defects distal
to the second molars
However this iatrogenic effect is
unrelated to flap design
*But it’s related to presence of plaque ,
bleeding on probing , pathologically widened
follicle , inclination of third molar , root
resorption of 2nd molar
* it appears to occur more often when third
molars are extracted in individuals older than
25 years.

48. 2) Another consequence of removal 
of third molars include permanent
paresthesia (numbness of the lip,
tongue, and cheek), d.t injury of the
lingual nerve passing distal to third
mandibular molar

49. 9. Habits
and Self
Inflicted
Injuries

50. I. Tooth brush trauma
1. Acute
 Erosions & diffuse erythema
 Ulcers
 Acute gingival abscess d.t.
forcefully embeded tooth
brush bristle
history : Signs of acute gingival
abrasion are frequently noted when the
patient first uses a new brush
2. Chronic
 Buccal and lingual recession
and attachment loss
 Cervical abrasion

51. II . Chemical Injury 
1) allergic inflammatory states, the gingival 
changes range from simple erythema to
painful vesicle formation and ulceration.
E.x. mouthwashes, dentifrices, or denture 
materials are often explain
2) nonspecific injurious effect of chemicals 
on the gingival tissues.
* topical application of
corrosive drugs such as aspirin , phenol or 
silver nitrate

52. III. Tobacco use
It results in : 
1) oral leukoplakia 
2) Increased incidence of gingival recession, 
3) cervical root abrasion, and root caries 
4) high incidence of severe periodontitis 

53. 10.
Radiation
Therapy

54. Radiation Therapy
 Radiation therapy has cytotoxic effects on both
normal and malignant cells
 The typical total dose of radiation for head and
neck tumors is in the range of 5000 to 8000
centiGrays (cGy = 1rad)
 The total dose of radiation is given in partial
incremental doses (Fractionation where the typical
dose administrated is in the range of 100 to 1000
cGys per week).
 this helps to minimize the adverse effects of the
radiation while maximizing the death rate of the
tumor cells.

55. Radiation therapy induces
Obliterative Endarteritis resulting in:
i. Soft tissue ischemia and fibrosis
ii. Hypo vascular and hypoxic bone
iii. Osteoradionecrosis
iv. Dermatitis and mucositis
v. muscle fibrosis and trismus (restricting
access to oral cavity)
vi. Xerostomia (greater plaque accumulation)
vii. Caries
viii. periodontal attachment loss and teeth loss
ix. Greater risk to periodontal infections

56. How to prevent the
complications of radiotherapy?
1. The severity of the
mucositis can be reduced by
asking the patient to avoid
secondary sources of
irritation to the mucous
membrane, such as smoking,
alcohol, and spicy foods.

57. 2. Use of a chlorhexidine
digluconate mouthrinse may help
reduce the mucositis. However,
chlorhexidine mouthrinses having
a high alcohol content that may
act as an astringent, which
dehydrates the mucosa, thereby
intensifying the pain.

58. 3. Fluoride application, effective oral hygiene
measures and frequent dental
examination.
4. Consult the oncologist before any surgical
or periodontal procedure to decrease
incidence of osteoradionecrosis
5. Prophylactic antibiotics to avoid
osteomyilitis
6. Restricted use of local anesthetic with
vasoconstrictor.
7. Hyperbaric oxygen therapy for treatment
of osteoradionecrosis

60. Complications
of the Use of
Laser in
Periodontology

61. Nd:YAG (neodymium-doped yttrium
aluminum garnet; Nd:Y3Al5O12)
1. Pitting and crater formation in
cementum
2. Exposure of dentinal tubules,
and cementum “peeling”
3. A reduced attachment of
fibroblasts to Nd:YAG laser
treated cementum was
observed

62. In conclusion the use of the
Nd:YAG laser in periodontal
treatment is restricted to the area
of the soft tissue management. No
safe removal of calculus is possible
using a Nd:YAG laser.

63. Erbium:YAG laser
Roughness of the enamel surface after
Er:YAG laser irradiation

64. After irradiation with the Er:YAG laser
enamel prisms at the rugged surface are
clearly visible, the border between lased
and non lased surface can be seen

65. Calculus is removed from cementum
using an Er:YAG laser, the irradiated
track is visible, the upper layer of
cementum
is removed, too
calculus
cementum
dentine