resin retained fixed partial dentures
Post on 17-Jul-2016
22 Views
Preview:
DESCRIPTION
TRANSCRIPT
A prosthesis that requires minimal removal of tooth structure, particularly of intact, caries free abutment teeth as compared to conventional fixed partial dentures.
It involves bonding b/w etched enamel & metal casting.
Minimal removal of tooth structure. Minimal potential for pulpal trauma. Anaesthesia not usually required. Supragingival preparation. Easy impression making. Interim prosthesis not usually required. Reduced chair time. Reduced patient expense.
Rebonding possible. removal of retainer by Monobevel chisel. Ultrasonic scalers
1955 Buonocore described acid etching of enamel.
Bonded ponticNatural or acrylic teeth were bonded to proximal and lingual surfaces of abutment teeth with composite resin.
1973 Rochette 1977 Howe & Denehy Livaditis
Drawbacks Weakening of metal retainer by
perforations. Exposure to wear of resin at perforations. Limited adhesion of metal provided by
perforations.
50% fail in 110 months
Cast perforated resin retained FPDs cont.
”Maryland bridge” Thompson & Livaditis (Univ. of Maryland) developed a technique for electrolytic
etching of Ni-Cr and Cr-Co alloy.
Advantages Retention is improved because resin to
etched metal bond is substantially stronger than resin to etched enamel. The retainers can be thinner and still resist flexing.
The oral surface of cast retainers is highly polished and resists plaque accumulation.
First generation of resin cements – Comspan was used.
by Moon in 1987 “Lost Salt Crystal “ technique, Alternative technique using Cast
Mesh Pattern
1990 Japan Super Bond (Sun Medical, Osaka, Japan)
Could not be used with noble alloys. Panavia (Kuraray co., Osaka, Japan) has sown excellent bonds to air abraded
Ni-Cr & Co-Cr alloys as well as tin plated gold &gold palladium based alloys
Roactec system
Roactec system Initially particle abrasion with 120um
alumina particles followed by abrasion with Silicate particle containing alumina.
Reduced restoration longevity. Enamel modifications are required.
Require extensive moisture control.
Space correction is difficult. Good alignment of abutment teeth is
required. Aesthetics is compromised on posterior
teeth.
Replacing missing anterior teeth in children, adolescents and medically compromised patients.
Short span. Unrestored abutments. Single posterior teeth. Periodontal splinting. Stabilizing dentitions after
orthodontics.
Para functional habits. Long edentulous spaces. Restored or damaged abutments. Compromised enamel. Significant pontic width discrepancy. Deep vertical overlap. Nickel allergy.
Basic principles The prosthesis should have a
distinct path of insertion with axial reduction and guide planes.
Resistance form by Preparation encompassing
180degress of tooth
Proximal grooves and slots. Occlusal rest seat. Occlusal clearance of 0.5 mm in
anterior teeth. Definite gingival margin.
High speed hand piece Articulating ribbon. Small wheel and short needle
diamonds. Flat end and round end tapered
diamonds.
Maxillary central incisor
Maxillary central incisor
Maxillary central incisor
Maxillary canine Maxillary first premolar
Mandibular MandibularSecond premolar First premolar
Maxillary Mandibular first First Molar Molar
Wax the framework and cast in Ni-Cr alloy.
Build up pontic in porcelain, fire it and contour it.
Evaluate the restoration clinically. Cleaning of casting is finished by
abrading it with aluminum oxide.
Abraded FPD placed in detergent in ultrasonic unit.
Tin plating Cleaning of abutments.
Etchant application.
Drying Primer liquids
Primer application Resin pastes
Applied resin. Oxyguard
application
Final restoration.
top related