Page 14 - Dental Technology 12-3

14-16-Rhein article-Q8_6-7-8-Ivoclar.qxd 10/6/2022 8:38 PM Page 1

14 prosthetic section DENTAL TECHNOLOGY, JULY-SEPTEMBER 2022

A HYBRID SOLUTION USING PRECISION

ATTACHMENT AND CONVENTIONAL CLASP

SYSTEM INCORPORATED WITH AN OBTURATOR

FOR CLASS 1 POSTERIOR END SADDLE SITUATION

A LABORATORY PROTOCOL

CLINICAL PROCEDURES: PROF. DR T.V PADMANABHAN
LABORATORY WORK: NANDHA KUMAR C.D.T / CADET

The patient is a 65-year-old male presenting
with a unilateral (left) posterior edentulous
space and small palatal defect adjacent to
it. Teeth to be replaced 24, 25, and 26.

Treatment plan: Removable partial den-
ture with unilateral precision attachment
along with a cast partial Clasp on the oppo-
site side of the arch, inclusive of coverage of
the palatal defect (obturator).
In this article we have tried to share the
lab procures involved in processing this
prosthesis

WORK FLOW
1. Due to severe attrition of the existing
natural teeth the dentist decided to pre-
pare (11, 12, 13, 21, 22, 23) all six teeth
and involve them as a part of the primary
structure for the precision attachment.
This will enhance the stability of the
removable prosthesis.
2. Impressions are made with putty and
light body as seen in the Figure 1.
lateral stability and axial stability thus of the situation this will ensure the smooth
offering the secondary prosthesis vertical flow of alloy material and the runner bar
MODEL PREPARATION resistance and lateral resistance so the pros- will act as a reservoir (Figure 9). The pri-
Two models are poured (Figures 2 & 3) thesis will not dislodge during chewing, mary framework (alloy - chrome cobalt) is
using a pressure chamber (strengthening and opening function. casted (Figure 10) with Vacuum pressure
unit) from Dreve Germany. This process will casting (Lukacast). Vacuum Pressure cast-
control the expansion of the gypsum and POSITIONING THE ATTACHMENT ing technique is best suited for precision
gives the sharp details of the prepared After completing the wax pattern for the castings of attachments and implants com-
tooth. One model is used as a working cast ceramics, An OT Strategy with an OT ponents to achieve sharp details.
with die sectioning using uni-lock tray sys- Steady (Rhein 83) is placed on the marked
tem and the other model is used as control crest of the ridge using a parallelometer Important Note: Use only glass beads for
cast. (Figures 4 & 5). and Strategy key (Figure 6). An OT strat- divesting and cleaning attachment compo-
egy is used for the precision attachment due nents.
CHOICE OF ATTACHMENTS to reduced ridge width and to counter lat-
The OT strategy is the choice of attachment eral masticatory forces. An OT Steady is CERAMIC LAYERING
used to place the OT Strategy closer to the
used here due to reduced ridge width adja- After finishing the frame work and sand-
cent to the abutment tooth, and it also remanent ridge. This helps to dissipate the blasting IPS style ceramics is used for layer-
counters lateral movements. An OT Steady vertical forces and counters the stress on ing as completed as shown in (Figures 11
is used to position the OT Strategy lower the abutment teeth (Figures 7 & 8). to 15)
because of loss of the alveolar ridge. A cast
partial design is adopted for the opposite Note: Place the attachments parallel to PRIMARY FRAME CEMENTATION AND PICK-UP
side of the arch to provide adequate cover- the occlusal plane The primary attachment is cemented in the
age for the palatal defect and to provide
patient’s mouth and a pick-up impression is
additional stability to the prosthesis. INVESTING AND CASTING obtained using a yellow retentive elastic
Strategy attachment is a bi-functional Primary frame work wax pattern is sprued cap (Rhein 83) (Figure 15). The lab ana-
attachment, it functions like a combination in indirect technique using runner bar. A log is inserted in this yellow cap and model
of OT cap and OT vertical. Strategy gives
4mm sprue is selected due to the long span is poured (Figures 16 & 17).