2. Periodontal Aspects Related to Fixed
Prosthodontics
presented By
Dr: Raiesa Mohamed Hashem
lecturer of fixed prosthodontics
2
3. These are certain precautions must be followed by the
operator to preserve the periodontium heaalth which is
the foundation of the fixed prosthodontics, and hence,
successful restoration will functions without conflictions
or problems.
3
4. The periodontium:
It is a connective tissue structure attached to the periosteum
of both the mandible and the maxilla that serves to anchor the
teeth in the alveolar processes.
Components of the periodontium
1- Gingiva.
2 - Periodontal ligament.
3- Alveolar bone.
4- Cementum.
4
5. The lining of oral cavity composed of three types of
mucosa:
1- masticatory (keratinized) covering hard palate & the
gingiva,
2- lining mucosa, covering lips, cheek, floor of the mouth&
soft palate.
3- Specialized mucosa ,covering dorsum of the tongue&
taste buds.
g of oral cavity
5
6. Anatomy of the periodontium
Free gingiva
,extends from
coronal of the tooth
to the epithelial
attachment
Attached G. from
epith.atach.to
alveolar mucosa ,in
between, is the
mucogingival
junction
Interdental papillae
or(Col st.)
6
7. Periodontium provides attachment, support, nutrition , synthesis and resorption
and mechano-reception
the main bulk is periodontal ligament which gives attachment and support to
the tooth in function.
Periodontal ligament fibers
1- Transseptal fibers
2- Alveolar crest fibers
3- Horizontal fibers
4- Oblique fibers
5- Apical fibers
7
8. Periodontal disease
Any condition of the periodontium other than normal.
Most of the gingival diseases are due to microbial plaque which leads to
further progress of the
pathological lesion.
Calculus , acquired pellicle ,materia alba are subsequent results .
8
9. why periodontal disease must be eliminated prior to restorative
dentistry:
1- To locate and determine the gingival margins of restorations properly,
2-The position of teeth is frequently altered in periodontal disease.
3-Inflammation of the periodontium impairs the capacity of abutment teeth
to meet the functional demands made on them.
4-Partial prosthesis constructed on cast made from impression of
diseased gingiva and edentulous mucosa do not fit properly when
periodontal health is restored.
5- Discomfort from tooth mobility interferes with mastication and
function.
9
10. Periodontal aspect in regard to fixed prosthodontics
procedures.
(principles or aspects that should be considered when
designing a fixed restoration. To preserve the periodontium
1- occlusion and its effect on periodontium.
2- crown margin
3- crown contour
4- embrasure materials and designs
5- splinting
6- pontic materials and designs
7- furcation involvement
8- bridge design
10
11. 1- occlusion and its effect on periodontium.
Occlusal forces have a magnitude & direction.
If the magnitude exceed the capacity of the periodontium, injury will results.
Occlusal Trauma:
Occlusal trauma is defined as an injury to the attachment apparatus (periodontal
ligament, alveolar bone, and cementum) as a result of excessive occlusal force.
11
15. Primary and secondary occlusal trauma
The tissue injury associated with occlusal trauma is often divided into two categories:
primary and secondary.
In primary occlusal trauma, a lesion results from application of excessive occlusal forces
to a tooth or teeth with normal supporting structures:
In secondary occlusal trauma, the lesion is in the periodontium of a tooth with
inadequate or reduced support. The greater the amount of periodontal support lost due
to periodontitis, the more significant occlusion becomes.
15
16. Radiographic signs of the traumatic lesion may include.
-The presence of a widened periodontal ligament space,
- Discontinuity of the lamina dura surrounding the tooth roots,
- Alveolar bone and/or root resorption.
16
17. Occlusal trauma will clinically manifest itself :
- Increasing mobility and/or migration of
the teeth.
- Persistent discomfort or tenderness.
- Pain to percussion or upon biting.
17
18. To prevent occlusal trauma:
- The fixed prosthodontics appliance should be constructed so that it exerts occlusal forces along
the long axis of the tooth.
-
- Any malocclusion should be treated first before the completion of the final restoration
-
- The occlusion must be checked in centric and lateral excursions as well. Any premature
contacts should be eliminated.
-
- The occlusion should be created at a vertical dimension that is stable for the patient. - There
should be even simultaneous contacts on all teeth during centric closure.
The distinction between primary and secondary forms of occlusal trauma, based on the
amounts of remaining periodontium, serves as primarily diagnostic purposes.
18
20. 2- crown margin.
CROWN MARGINS are the weakest point in the restoration, through which percolation
of saliva & food may cause recurrent caires.
SO…,it must be.. Smooth, rounded ,accurately fitting the preparation,& free of any
porosity.
A- Factors affecting health of the gingival tissue.
1- accuracy and fitness of the restoration margins on the preparation.
2- depth of gingival encroachment i.e length of crown margin.
Over extended margins may cause tearing of epithelial attachment and
pocket formation
3- width of gingival encroachment i.e thickness of the margin
thick margin lead to pressure on the gingival tissue and blanching.
20
21. Crown margin placement
Supragingival margin placement
Advantages:
1- Favorable reaction to gingiva.
2- Common path of insertion.
3- Easily evaluate restoration at recall appointment.
4- Avoid pulpal injury.
5- Metal finishing technique is easer.
21
23. Restorative consideration frequently dictates the placement of restoration
margins beneath the gingival tissue crest. Restorations may need to be
extended gingival:
Indications of Subgingival margin placement.
1- Esthetics
2- Sever cervical erosion, restoration or caries extending beyond
gingival crest.
3- To increase retention in case of teeth with short occlusogingival
height.
4- Elimination of persistent root hypersensitivity.
5- Patient with high caries index and bad oral hygiene.
23
24. From a periodontal point of view
Both supragingival and equigingival margins are well tolerated.
The greatest biologic risk occurs when placing margins
subgingivally.
1. These margins are not as accessible as supragingival or equigingival
margins for finishing procedures, and in addition,
2. if the margin is placed too far below the gingival tissue crest, it violates
the gingival attachment apparatus( biologic width).
24
25. The biologic width: is the dimension of space that the healthy
gingival tissues occupy above the alveolar bone. the combined
c.t.epith.attatchment from crest of alveolar bone to the base of
gingival sulcus.*
Importance of biologic width
The biologic width allows gingival fibers to
establish direct contact with the tooth and acts as
a barrier to prevent penetration of microorganisms
in the sulcus into the underlying periodontal tissues
25
26. Two different responses can be observed from the involved
gingival tissues. One possibility is that bone loss of an
unpredictable nature and gingival tissue recession.
Other factors is the likelihood of recession. These variables
include whether the gingiva is thick and fibrotic or thin and
fragile and whether the periodontium is highly scalloped or
flat in its gingival form. It has been found that highly
scalloped thin gingiva is more prone to recession than a flat
and’ thick fibrous tissue.
26
27. Two the more common finding with deep
margin placement is that the bone level
appears to remain unchanged, but
gingival inflammation develops and
persists.
27
28. Margin placement guidelines.
1. If the sulcus probes 1.5 mm or less: place the restoration margin
0.5 mm below the gingival tissue crest.
2. If the sulcus probes more than 1.5 mm: place the margin one half
the depth of the sulcus below the tissue crest.
3. If a sulcus greater than 2 mm is found: especially on the facial
aspect of the tooth, then evaluate to see whether a gingivectomy could
be performed to lengthen the teeth and create a 1.5-mm sulcus. Then
the patient can be treated using Rule 1.
28
29. Nature of the margin:
Periodontal health is enhanced by the rounding, dulling and polishing
of sharp margin.
The over extended wax pattern or failure to determine the finish
line on the impression leads to failure to determine the finish line on
the die.
29
31. Defective margin
1- open margin:
Leads to micro leakage of food debris and bacteria between tooth and restoration.
- Caries
2- overhanging margin:
Causes irritation and plaque accumulation.
3- sharp margin :
Continuous irritation to the gingiva.
4- rough margin:
Cause accumulation of plaque
Gingival inflammation and periodontal disease.
31
32. Margin examination.
Examined with finger tip for any rough or sharp margin.
- Casting with overhangs precipitate colonization of the
subgingival area with micro flora resembling chronic
periodontal disease, while the ideal casting harbored only
bacteria that are found in healthy gingival crevices.
32
33. 3- Crown contours:
Buccal&lingual contour of the crown should be simulating the
adjacent tooth.
Ideal contour provides access for hygiene and has the fullness
to create the desired gingival form (improving Esthetics)
33
34. A) Buccal and lingual contour
1- Normal contour
-
Favorable to periodontium
-
Allow massage of the gingiva
-
2-Over contoured
-
Causes : under reduction
- Leads to lead to accumulation of food and subsequent gingivitis&
periodontitis. In addition, bad esthetics will results .
-
3- Under contoured
-
will results in flat surface , abnormal esthetics, & food impaction
to bone resorpition.
-
34
36. b)Proximal surfaces
1- Normal contact
Allow passage of dental floss with slight resistant
2- Open contact.
Leads to food impaction between teeth leading to pocket formation,
periodontal ligament problems and caries in adjacent teeth.
3- Tight contact.
Leads to pressure on neighboring teeth preventing complete seating of
restoration
36
37. Open C.A.
Adding gold solder
Addition of low fusing
porcelain to close the open
contact
37
38. 4- Embrasure design.
It is the space that widen out from the proximal contact areas
of healthy teeth.
The design of the embrasure should be as normal teeth as possible, to the
limit of passing dental floss.
It serve to
1- protect gingiva from food impaction
2- deflect the food to massage the gingiva
3- Provide spillway to the food during mastication
4- relief occlusal stresses when resistant food is chewed.
38
39. It should not to be too wide or too narrow
TOO narrow embrasure means tight contact with crushed gingiva in-
between, too wide embrasure means open contact with resultant food
impaction & gingival trauma.
39
40. Pontics are fixed partial denture components that replace missing teeth and restore function
and appearance compatible with continued oral health and comfort.
There are certain requirements of the pontic:
1- Restores function efficiently.
2- Meet the esthetic demands.
3- Biologically accepted.
4- Hygienic design.
5- Easily constructed
The principles guiding the design of the pontic are:
1. Cleansability.
2. Appearance.
3. Strength.
5. Pontic design
40
41. The pontics can be classified according to tissue
contact into:
Mucosal Contact
1- Saddle
2- Ridge Lap
3- Modified Ridge Lap
4- Ovate
5- Conical
No Mucosal Contact
1- Sanitary
2- Modified Sanitary
41
43. 1- Gingival surface:
The demands of esthetics often dictate tissue contact, whereas hygienic
requirements favor tissue clearance.
So
1- The Portion of pontic touching the ridge should be :
a- Small
b- Convex
c- Passive contact (pressure free)
2- The tip of the pontic should never extend past the mucogingival junction.
It should only contact attached keratinized gingiva.
43
44. Form of the gingival surface
1- Anterior and premolar area:
Due to esthetic demand tissue contact is recommended
So
ridge lap or modified ridge lap is indicated.
2- Posterior area due to hygienic demand tissue clearance is
recommended
So
sanitary or modified sanitary is indicated.
44
45. 2- Occlusal surface
3 concepts exist relative to the occlusal surface of a pontic.
a) The reduction of the occlusal table to 1/5-1/3 the bucco-lingual dimension to control force
on the abutment
b) Another maintains the normal occlusal width to provide soft tissue protective mechanism
during mastication and to provide adequate occlusion with opposing arch.
c) The 3rd tends to minimize the significance of the occlusal dimensions based upon the
importance of the proprioceptive mechanism in regulating the occlusal forces.
45
46. 3-The buccal and lingual surfaces:
The buccal and lingual surfaces of the pontic may differ according to:
1. Esthetics. 2. hygiene. 2. Ridge morphology.
For esthetic the buccal surface of the pontic should follow the contour of the adjacent
teeth
In maxillary and mandibular anterior region
For esthetic demand maintain normal facial contour , axial alignment and length.
In mandibular posterior region
The buccal and lingual surfaces follow normal tooth form from cusp tip to the height of
contour, sanitary design
46
48. Excessively broad proximal contact areas crowed out the facial and lingual gingival papillae. These
prominent papillae trap food debris that leads to gingival inflammation.
Too narrow proximal contact areas create enlarged facial and lingual embrasures that don't provide
sufficient protection against interdental food impaction.
4- Proximal surface:
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49. Pontic Material
The need for strength , rigidity and durability has been established.
The material must also permit acceptable color, contour and be biocompatible
regarding effect of the material itself or the effects of the surface finish.
Glazed porcelain the most biocompatible material.
- easy to clean
- plaque removal easier
49
50. 6- Splinting
Splinting refers to any joining together of two or more teeth for the
purpose of stabilization.
Function of splinting:
1- Protect loose teeth from injury while stabilizing them in a favorable occlusal
relationship.
2- To distribute occlusal forces so that teeth weakened by loss of periodontal
support do not become loose.
3- To prevent natural tooth from becoming loose and migrating.
4- stabilization of teeth during and after trauma.
50
51. Advantages of splinting.
1- Redirecting the forces on the abutment teeth in favorable direction.
2- Redistribution of forces on more than one tooth.
3- Prevent lateral forces which is destructive to periodontal ligament.
4- Single tooth begin to function as multi-rooted teeth or as molars
Types of splints:
Classification of dental splints according to the duration
1- Temporary or short term splints.
2- Intermediate or long term Splints:
3- Permanent splints.
Splints can also be classified as:
1- Removable splints.
2- Fixed splints.
51
52. I. Temporary or short term splints:
–Used for less than 6 months.
–Mainly indicated to immediately stabilize a tooth loosened by a blow, or
and replanted.
(bad esthetics and biologic problems may result)
Types of splints :
1) Wire and Composite Splint:
2) Composite resin splint:
3) wire and acrylic splint:
4) Ligature wire:
5) Orthodontic band:
6) Removable temporary splits:
A) Acrylic bite-guards (mouth guard) or occlusal splint:
B) Cast continuous clasp splint:
52
53. 1) Wire and Composite Splint:
•A horizontal groove 2-3 mm wide and 1.5 mm depth is prepared in the
lingual surface of anterior teeth or the occlusal surface of posterior
teeth. A braided wire is fitted and imbedded in the groove, light-cured
composite fills the groove. After hardening, the surface is polished
•
53
54. The right central incisor was partly displaced by a
blow. This wire and composite splint is rigid allows
the tooth to be positioned correctly in the occlusion
while the splint is attached. It was removed after
three weeks by which time the injured tooth was
firm.
54
55. 2- Composite resin splint:
•Splints made from wire and composite resin, are not chemically integrated with dental
resins, thus were easily disrupted by shear stress.
•It is a well accepted technique for stabilization used for:
1.Treatment post acute trauma to prevent mobility.
2.Preventing tooth drifting after loss of an adjacent tooth.
3.Splinting of periodontally involved mobile teeth.
55
56. 3)The wire and acrylic splint:
Frequently used for the stabilization of incisors. It is stronger and
more reliable than the composite-filling splint. Usually the teeth from
canine to canine, or first premolar to first premolar, are included in the
splint.
A wire and acrylic splint. The roots of the four incisors were
resected. The splint has remained effective until complete alveolar
healing has occurred. The patient is ready for a bridge
56
57. 4) Ligature wire
When anterior teeth require splinting
- Involve wrapping wire around the teeth.
5) Orthodontic band
Orthodontic bands are used especially in posterior
segments, where they are not obvious
(
stainless-steel bands are fitted to the
teeth to be splinted and welded together
.
57
58. 6) Removable temporary splits:
i. Acrylic bite-guards (mouth guard) or occlusal splint: is a removable, rigid
acrylic appliance used for treatment of bruxism, may also be used as splint.
.
.
58
59. i. ii. Cast continuous clasp splint: A removable continuous clasp is fabricated like
a partial denture framework. It rests at the height of contour and the cingulum of
anterior teeth and at the buccal and lingual surfaces of posterior teeth. The
appliance is rigid and does not enter undercuts as does a partial denture clasp
59
60. II. Intermediate or long term Splints:
• This type of splints is used when teeth need to be stabilized for several months
or years.
Heat polymerized full coverage acrylics:
This method is commonly used with periodontally compromised patients where
there is a commitment to fixed splints after periodontal therapy. These splints are
then removed, periodontal therapy performed, and the interim splints is replaced.
After healing ,permanent cast restoration is cemented.
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61. III) Permanent splints.
It can performed using a removable prosthesis, fixed partial denture either with rigid
connector or non rigid connector.
Minimum preparation splint-bridge of Rochette type. fixed partial denture splints:
61
62. The normal position of the osseous crest is approximately 1.5 mm apical to the CEJ in
young and healthy adults.
Root complex is the portion of a tooth that is located apical of the cemento-enamel
junction (CEJ), i.e. the portion that normally is covered with a root cementum. The root
complex may be divided into two parts the root trunk and the root cone(s).
6- Furcation involvements
The root trunk represents the undivided region of the root. The height of the
root trunk is defined as the distance between the CEJ and the separation
line (furcation) between two root cones (roots). Depending on the position
of the separation line the height of the root trunk may vary from one surface
to the next in one given molar or premolar.
62
63. Furcation entrance: the transitional area between
the undivided and the divided part of the root.
Furcation fornix: the roof of the furcation.
Degree separation: the angle of separation between two roots (cones).
Divergence is the distance between two roots; this distance normally
increases in apical direction.
63
64. Classification of furcation involvements
Class I: vertical loss of bone support is less than 3mm apical to the CEJ no
radiographic evidence of bone loss.
Class II: vertical loss greater than 3mm but the total horizontal width of the
furcation is not involved osseous loss in evident in x-ray.
Class III: horizontal through-and-through lesion that is occluded by gingiva
but allows passage of an instrument from the buccal, lingual , or palatal
surface.
Class IV: horizontal through-and-through lesion that is not occluded by
gingiva.
64
66. Different methods of therapy are recommended according to the
degree of furcation involvement as following:
Treatment of a defect in the furcation region of multi-rooted tooth is intended to meet two
objectives:
1- The elimination of the microbial plaque from the exposed surfaces of the root complex.
2- The establishment of an anatomy of the affected surfaces that facilitates proper self-
performed plaque control.
Furcation involvement class I
Recommended therapy: Scaling , root planning and Furcation plasty.
Furcation involvement class II
Recommended therapy: Furcation plasty, Tunnel preparation, Root resection, Tooth
extraction, and Guided tissue regeneration at mandibular molars.
66
67. Furcation involvement class III, IV
Recommended therapy: Tunnel preparation, Root resection,
and Tooth extraction.
Root amputation is removal of root without touching the
crown.
Hemisection is a procedure in which the tooth is separated
through the crown and furcation, producing two equally-sized
teeth.
67
68. Treatment of furcation involvement:
1. Scaling and root planning
in the furcation entrance of a class I involvement in most situations
result in the resolution of the inflammatory lesion in the gingiva.
2. Odontoplasty-osteoplasty
This procedure involves recontouring of both the tooth structure and the
supporting bone to improve access for cleaning. A minimal amount of
tooth structure and bone is lost in this procedure. This can be used in
class I and incipient class II lesions.
68
69. Tunnel preparation
Tunnel preparation is a technique used to treat deep class II and class III furcation
defects in mandibular molars. This type of resective therapy can be offered at
mandibular molars, which have a short root trunk, a wide separation angle and
long divergence between the mesial and distal root.
1. the reflection of buccal and lingual mucosal flaps
2. the granulation tissue in the defect is removed and the root
surfaces are scaled and planned.
3. The furcation area is widened by the removal of some of the
interradicular bone, mesial and distal to the tooth in the region is
also removed.
4. Following hard tissue resection enough space has been
established in the furcation region to allow access for cleaning
devices.
69
70. 3- Root amputation= [ Root resection]
Root amputation is indicated in:
1. Severe vertical bone loss involving one root of a mandibular molar or
one or two roots of a maxillary molar.
2. Furcation involvement that is not treatable by odontoplasty-
osteoplasty. [ class II, III].
3. Vertically or horizontally fractured roots.
5. Severe root caries. Internal or external resorption.
6. Inability to treat one root canal successfully.
7. Sever dehiscence and sensitivity of a root
8. Failure of abutment in long span splint or FPD.
9. Strategic removal of a root to improve prognosis of an adjacent tooth.
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71. Contraindication to root resection.
1-Closely approximated and fused roots.
2-Significantly decreased general osseous support or increased crown root ratio.
3-Remaining structure that will not provide adequate resistance against the force of
mastication.
4- Excessive loss of supporting root structure.
5- Inability to be treated enodontically.
6- Remaining structure that cant be restored
71
72. Hemisection
- cutting the tooth in half. In the case of mandibular molars, when one
hemisected root is to be extracted, then subsequent restoration of the
remaining root is done. Sometimes the roots are to be maintained and each
half of the tooth is restored separately, a procedure known as
Bicuspidization. The individual roots may then be separated orthodonticaly.
72
77. Crown configuration:
1- Maxillary distofacial root:
It doesn't create any esthetic problem, because it
is hidden by the mesiofacial cusp in normal tooth
alignment.
77
78. 2. Maxillary mesiofacial root:
The resulting occlusal outline tends to the
more " triangular “ because of the greater
faciolingual dimension of the root that has
been removed.
78
79. 3- Maxillary palatal root:
The presence of lingual cusps would:
a) Produce an area inaccessible to hygiene maintenance,
b) Create a severe torquing moment on the tooth which could be either
tip the tooth lingually OR fracture tooth under the crown.
79
80. 4- Maxillary facial roots:
Preparation of the tooth overlying this root will result in either
"oval or circular: configuration depending upon the shape
of the root itself.
Occlusal contacts should occur on the lingual cusp tip.
There should be minimal occlusion facial to the central
groove of the crown.
80
81. 5- Sky furcation:
To separate the roots of maxillary molar without removing a root.
This is possible only if roots are:1 - long- well supported by bone. 2-- distinctly
separate
Roots are cut apart and then rejoined by a crown which
acts as interadicular splint with concave connectors from
one root to the other.
81
82. 8- Bridge design
The magnitude of tipping force varied according to different design of fixed partial
denture.
1- cantilever bridge:
- If the edentulous span is long comparing to the number of abutment
So may occur looseness of the bridge and its failure.
- while if there is increase in the surface area of the resisting periodontium
comparing to the tipping force
- This means that when the edentulous span is short comparing to the number of
the abutment so the lamina dura will thickened to give rise to increasing retention.
The cantilever bridge has a deleterious effect on both the single abutment &
periodontium,
82
83. The advantage of this type of bridge is that the semi rigid connector can be separated
before the bridge is cemented and so the two parts of the bridge can be
cemented separately to reduce forces on a compromised abutment
2- Fixed-supported bridge
The fixed-supported bridge force distribution is11/16
towards the soldered abutment , &5/16 towards the rest
seat on the inlay or onlay
retainer.
83
84. Long span bridge (alloy with high rigidity is a must
3- Fixed-fixed bridge
The best bridge design regarding force distribution
Extra hard material must be used in long span bridge.
If no the stressed periodontium may suffer deleterious effect
There is one unit of deflection (X) The deflection will be
8 times as great for a given span length (p) (8X) if the
span length is doubled (2p).
84
