Microsoft Word - Belge7ANNOTATION TO THE LESSON 11 Loss of teeth is followed by formation of tooth alignment defects that involves need in their
replacement with dentures. Absence on a jaw from 1 to 15 teeth is considered to be a partial defect of the tooth alignment. There are small defects (absence from 1 to 3 teeth), average defects (absence from 4 to 6 teeth) and large defects (absence of more than 6 teeth). Partial defects of tooth alignments are also classified by their topography. In fig. 1 Kennedy classification of tooth alignments partial defects is presented. Defects can be limited by teeth only from one side (defects are located posterior to the natural teeth) (fig. 1a, b) or from two sides (included) (fig. 1c, d).
a
d
Fig. 1. Types of tooth alignments defects (according to Kennedy): a – bilateral edentulous area located posterior to the remaining natural teeth; b – unilateral edentulous area located posterior to the remaining natural teeth; c – unilateral edentulous area with natural teeth both anterior and posterior to the area; d – single but bilateral (crossing the midline) edentulous area located to the anterior of the remaining natural teeth.
The dentures, applied for the restoration of the tooth alignment integrity, are classified by ways
of fixation in the oral cavity and by principles of a masticatory load transfer on the tissues under the denture. Depending on ways of fixation in the oral cavity there are fixed dentures (which are constantly fixed on abutment teeth by means of special fixing materials), removable dentures (dentures designed in such a way that their imposing and removal from tissues of a prosthetic bed are carried out by the patient) and the dentures which are fixed on implants (fig. 2).
a b c Fig. 2. The dentures used for orthopedic treatment of partial teeth loss: a – fixed; b – removable; c – dentures on
implants. Depending on which fabrics a masticatory load is transformed from false teeth, Rumpel
allocates physiological, not physiological and semi-physiological ways of the masticatory pressure transfer on the tissues (fig. 3). Fixed dentures (fig. 3a) provide transfer of the load on the periodontium of abutment teeth that limit defect of the tooth alignment. The teeth periodontium is adapted for perception and amortization of the masticatory pressure, and such way of the load transfer is called physiological. Removable base dentures (fig. 3b) transfer pressure from false teeth to the mucous membrane that covers a prosthetic bed and the underlying fabrics which aren't adapted for the load. Such way of the load transfer is called not physiological. All-cast (bugel) removable dentures (fig. 3c) distribute the masticatory load from false teeth between the
periodontium of abutment teeth and the mucous membrane of prosthetic fabrics. It is accepted to call a combined method of the masticatory load transfer semi-physiological.
a
b
c
Fig. 3. Schematic images of ways of the masticatory load transfer on the underlying tissues by dentures that eliminate partial defects of tooth alignments: a – a physiological way; b – not physiological way; c – a semi- physiological way (on the basis of fig. from the R.Markskors book "All-cast removable artificial dentures", 2000).
At the choice of dentures design a defect size, its topography, a condition of abutment teeth and
some other factors are considered. Usually small defects of the tooth alignment, limited on both sides by abutment teeth, are compensated by fixed dentures. Large defects are compensated mainly by removable base dentures. All-cast removable dentures are applied at special indications.
Fixed dentures can be divided into two parts: supporting elements and an intermediate part (artificial teeth) (fig. 4).
Fig. 4. Main elements of a fixed denture: a – supporting elements, b – an intermediate part
(artificial teeth).
According to the fabrication technology fixed dentures can be divided into all-cast and
stamped-soldered (fig. 5).

Fig. 5. Types of fixed dentures according to the technology of their fabrication: a – all-cast; b – stamped-soldered
Metal, metal-ceramic and other combined crowns, inlays, onlays can be supporting elements
of the fixed dentures (fig. 6).
A B c
Fig. 6. Supporting elements of the fixed denture: a- artificial crowns, b – inlays, c – lingual onlays
In all-cast fixed dentures (fig. 5a) supporting elements and the intermediate part are made by casting. Sequence of laboratory fabrication stages of all-cast fixed dentures is the same as the sequence of cast metal crowns fabrication stages.
In stamped-soldered dentures (fig. 5b) supporting crowns (retainers) are made by the method of metals processing by pressure (stamping) and the intermediate part is made by the method of an individual casting on previously created wax pattern. Then supporting elements are connected with the intermediate part by means of solders.
The part of the denture which is located between supporting elements is called an intermediate. Depending on a relation of the intermediate part and the mucous membrane of the alveolar bone there are washing, tangent and saddle types of intermediate parts (fig. 7). A choice of the intermediate part depends on the defect topography, a constructional material and manufacturing techniques of the fixed denture. In stamped-soldered fixed dentures, eliminating defects in the area of posterior teeth, from a position of hygienic requirements the washing design is the most rational (fig. 7a). In the stamped-soldered fixed dentures, eliminating defects in the area of frontal teeth (sometimes in the zone of premolars), the tangent type of intermediate part that provides esthetic effect and prevents violations of phonetics (fig. 7b) is the best. At production of ceramic and metal- ceramic dentures designing of the intermediate part of the saddle type (fig. 7c) is possible.
a b c Fig. 7. Main types of the intermediate part of the fixed dentures according to the relation between it and a mucous membrane: a – washing, b- tangent, c – saddle
The intermediate part of the fixed dentures can be made of one material (all-cast, plastic,
ceramic) (fig. 8a), of the metal cast framework covered by plastic (fig. 8b), and also of the metal cast framework covered by ceramics (metal-ceramics) or photopolymeric plastic (metal-plastic) (fig. 8c).
Fig. 8. Types of the fixed dentures
intermediate part based on the constructional material
a b c
Fixed dentures can differ depending on the topography of supporting elements and the tooth
alignment defect (fig. 9). The classical bridge-like fixed denture has not less than two supporting elements located on teeth on both sides of the defect (fig. 9a). Another type of fixed dentures is the denture which can have the support located distally from the defect (fig. 9b) and mesially from the defect (fig. 9c). There are also combined dentures (fig. 9d).
a b c d
Fig. 9. Types of fixed dentures: a – fixed denture with supporting elements located on teeth on both sides of the defect; b – fixed dentures with supporting elements located distally from the defects; c – fixed dentures with
supporting elements located mesially from the defects); d – combined dentures Fixed dentures with the retainers located on teeth on both sides of the defect have the most
rational design, because the masticatory load is transferred to the periodontium of abutment teeth in the direction of their longitudinal axes (fig. 10.1). While using the denture with the retainer only on one side of the defect the masticatory load, falling on the artificial tooth, promotes rotation of the denture around the center (fig. 10.2). A lever causes appearance of side overturning loads in the abutment tooth that can be harmful for periodontium tissues. That's why fixed dentures with supporting elements located distally or mesially from the defect have limited indications.
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