Selection of abutment teeth

1. SELECTION OF
ABUTMENT TEETH
Submitted by: Lana Michael
IVth year

2. DEFINITION
 An abutment can be defined as a
tooth, portion of a tooth or that
portion of an implant used for the
support of a fixed or removable
prosthesis.(GPT)
 Abutment plays a crucial role in
accepting the load acting on a
fixed partial denture.
 The choice of abutment is
important because it has to
withstand both the forces acting
on it and on the pontic.

3. FACTORS INFLUENCING THE
CHOICE OF AN ABUTMENT
Tooth
Gingivo-
periodontal
complex
Root
• Location
• Position
• Form
• Condition
• Crown-root
ratio
• Root
configuration
• Gingiva
• Periodontium

4. LOCATION, POSITION AND CONDITION OF
THE TOOTH
Characteristics of the preferred abutment:
 Teeth adjacent to edentulous spaces
 Teeth with grossly decayed crowns that can be
restored with a full veneer crown
 Modifications like dowel core and pin retained
amalgam restorations-needed to restore crown
morphology in grossly destructed teeth
 Vital teeth are preferred, though endodontic teeth can
be used
 Pulp capped teeth cannot be used as they are
always under risk of RCT

5. CROWN-ROOT RATIO
 The ratio between the length of crown and length of
root should always be less than one
 The length of crown indicates the length of tooth
structure above the crest of alveolar bone
 Ideally, the crown ratio should be 2:3
 Ratio up to 1:1 is acceptable

6. ROOT CONFIGURATION
 The forces acting on tooth are transferred to supporting
bone through the root.
 The shape of the root determines the ability of the
abutment to transfer the masticatory load to the
supporting bone.
Facts:
 Roots with greater labiolingual widths are preferred
 Roots with irregular curvature are preferred

7.  Teeth with longer roots serve as better abutments
 Tooth with conical roots can be used for short span
fixed partial denture

8. ROOT SUPPORT
 The supporting alveolar bone should be
healthy
 It should have good trabecular architecture
and shows no sign of bone defects or bone
loss
 Intra-oral radiographs should be used to
evaluate bone architecture
 The alveolar bone support is one of the most
important factors that aid to evaluate an
abutment

9. PERIODONTAL LIGAMENT AREA
 It can be used as a measurement or scale to
determine the potency of the abutment
 Tylman stated that the two abutment teeth could
support two pontics
 Johnston et al improvised Tylman’s statement and
proposed the famous Ante’s law

10. ANTE’S LAW
 The sum of the pericemental areas of the abutment
teeth should be equal to or greater than the tooth to be
replaced
 The periodontal area of the abutment should be
calculated and if it is not sufficient then an additional
tooth should be used as a secondary abutment

11. ASSESSMENT OF PULPAL HEALTH
 Usually unrestored abutments are preferred
 If caries is present, regular preparation can be done
 If large caries lesions are present they should be
scooped out and can be used for additional
retentions
 If the abutment tooth has a carious lesion with
pulpal involvement the RCT is advised. RCT not
advised for abutments with periapical lesion