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treatment planning for REPLCEMENT OF MISSING TEETH - Coggle Diagram
treatment planning for REPLCEMENT OF MISSING TEETH
Prosthetic technique replacing missed tooth or teeth
1- RPD
2- Tooth supported FPD
Conventional FPD
Resin bonded FPD
3- Implant supported FPD
4- implant
3. Treatment planning
- Treatment planning consists of formulating a logical sequence of treatment designed to restore the patient’s dentition to good health, with optimal function and appearance.
Factors Affecting the Selection of prosthesis Type:
The biomechanical considerations
The prospective abutment
Esthetic requirements
Patient’s desire
Financial factors
Clinician’s skills
Laboratory support
Patient’s motivation and expected cooperation
5. The biomechanical considerations
A) The decision to remove a tooth
questionable tooth of poor prognosis should be carefully assessed
The decision to remove a tooth is part of the treatment- planning process and is made after assessing the advantages and disadvantages associated with retention of the tooth.
Sometimes it is possible to retain a tooth with an apparently hopeless prognosis by using highly specialized and complex techniques.
At other times, removing the tooth will be the treatment of choice.
A decision about replacing a missing tooth is best made at the time its removal is recommended, rather than months or years after the fact
The consequences of removal without replacement
Supra occlusion of the opposing tooth or teeth.
Tilting of the adjacent teeth.
Loss of proximal contact.
Esthetics.
Loss of a mandibular first molar not replaced with an FPD. The typical consequences are
supraclusion of opposing teeth(1),
tilting of adjacent teeth (2),
and loss of proximal contacts (3).
B) The edentulous span:
I. Distribution:
An edentulous space with no distal abutment will usually require RPD
Other alternative treatments are :
.Implant –supported FPD
.In very selected case cantilever FPD
II. Length:
- It has been reported that all FPD , long or short possesses a certain degree of bending or flexing when subjected to a load , the longer the span the greater the flexing .
Clinical sequelae of bridge flexing :
fracture of porcelain veneer
connector breakage
retainer loosening
an unfavorable soft tissue response
Clinical implication of the principle of bridge in flexing treatment planning:
replacing 3 posterior teeth with FPD usually exhibits unfavorable prognosis especially in mandibular arch
constructing a long span FPD on short mandibular teeth is expected to have a very disappointing prognosis
Alternative treatment modalities for long edentulous span :
An implant supported FPD
requirement needed:
Sufficient alveolar bone and satisfactory density broad flat ridge
2.Favorable opposing occlusion
RPD
III. Arch form:
Arch curvature affects the amount of stresses occurring in FPD constructed in the anterior segment , especially in the upper anterior teeth.
In case of point arch anteriorly . pontics of FPD would lie outside the inter-abutment axis line thus acting as lever arm producing torqueing movement on the supporting abutment.
To offset the leverage action , the resistance arm should be at least equal to the lever arm
6. The prospective Abutment
(A) The pulpal condition:
I. Vital sound tooth
II. Carious tooth
III. Endodontically treated abutments
(B) Coronal variations and tooth alignment:
I. Over erupted teeth
II. Short crowns
III. Mesially tilted second molar:
Different treatment modalities :
Uprighting the tilted abutment orthodontically
proximal (mesial) ½ crown can be used as retainer on the distal tilted abutment
non-rigid connector on the distal aspect of the premolar retainer to compensate for the inclination of the tilted molar
telescope crown and coping can be constructed as a retainer on the distal abutment
(C) Root portion and periodontal condition:
I. Crown –root ratio
II. Root shape and angulation
III. Periodontal ligament surface area
I.Crown root ratio
It is the ratio between the linear length of that part of tooth above the level of alveolar crest of bone to that part of root embedded in the bone
The optimum C/R ratio 2:3
The minimum acceptable C/R ratio 1:1
Significant of the C/R ratio
The root portion embedded in the alveolar bone is considered the supporting tooth part resisting the leverage action of occlusal forces falling on the crown portion (that part above level of alveolar bone crest) thus to resist any leverage destructive forces falling on the prospective abutment, the root portion (resistant arm) should be greater than the crown portion (force arm)
The C/R ratio is liable to changes throughout life, being manifested by the apical movement of the alveolar bone level
II. ROOT SHAPE AND ANGULATION
Broader roots labio-lingually than mesio-distally are preferable to roots that are round in cross section.
Multi-rooted posterior teeth with widely separated roots offers better periodontal support than converging ones.
Single rooted tooth with elliptic cross section offers better support than those of circular ones.
Well aligned tooth provide better support than tilted one.
III.Periodontal ligament surface area
It’s a prime requisite when planning treatment FPD to asses the root surface area or the area of periodontal ligament attachment of the root to the bone
Ante’s law:
The root surface area of the abutment teeth should be equal to or more than that of the tooth or teeth to be replaced with pontics