TOPIC: FIXED PARTIAL DENTURE
🎯 KEY POINTS:
🔸Maxillary first molar has maximum root surface area of 433 mm2 and Mandibular first molar has root surface area of 431 mm2; among Anterior maxillary teeth, Canine has maximum root surface area of 273 mm2 and Mandibular central incisor has minimum 154 mm2; among Posterior mandibular teeth, first premolar has minimum root surface area of 180 mm2.
🔸Tooth preparation becomes difficult, if the long axis of the tooth diverges or converges more than 25 degrees from parallelism.
🔸Multirooted posterior teeth provide better periodontal support than single conical roots.
🔸Bending or flexion of the fixed bridge varies directly to the cube of the length and inversely with the cube of cervicoincisal thickness of the pontic.
🔸More parallel the opposing walls of the preparation, more will be the retention.
🔸Optimum taper for prepared walls is 2–6 degrees.
🔸For short clinical crown, additional retentive features such as grooves, pins, slots and boxes are advocated.
🔸Self-threading pins are about five times more retentive than cemented pins.
🔸Ferrule helps in binding the remaining tooth structure together preventing root fracture during function.
🔸Lost salt technique is used to fabricate Virginia bridge.
🔸Rochette bridge was the first used perforated retainer.
🔸Maryland bridge is the etched metal prosthesis.
🔸Single piece platinum reinforced porcelain bridge is called Swann bridge.
🔶 DIFFERENT DESIGNS IN FIXED PROSTHODONTICS:
👉 Different designs in fixed prosthodontics are:
• Fixed–fixed partial denture (FPD)
• Resin-bonded tooth-supported FPD
• Implant-supported FPD
• Fixed–removable partial denture
📌 FERRULE
🔍 DEFINTION:
A metal band or ring used to fit the root or crown of a tooth. (GPT 8th Ed)
💡Roles of Ferrule
• It counteracts the lateral forces during post placement.
• It counteracts the functional leverage forces.
• It counteracts the wedging effect of tapered post.
📌 RESIN-BONDED BRIDGE
🔍 DEFINTION:
A fixed dental prosthesis that is luted to tooth structures, primarily enamel, which has been etched to provide mechanical retention for the resin cement. (GPT 8th Ed)
🔍 CLASSIFICATION:
Resin-bonded bridges can be classified into the following types on the basis of type of retention employed by the retainer.
(i) Bonded pontic
(ii) Mechanical retention – Rochette bridge
(iii) Micromechanical retention – Maryland bridge
(iv) Macroscopic mechanical retention – Virginia bridge
(v) Cast mesh FPD