Iran Dental Board - Prosthodontics flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Occlusal convergence angle

Total taper between opposing axial walls; about 6 degrees is ideal for retention, while angles above 20 degrees reduce frictional retention and require auxiliary features.

Ferrule effect

A 1.5–2.0 mm circumferential collar of sound dentin above the preparation margin that resists fracture of endodontically treated teeth by counteracting wedging forces.

Chamfer finish line

A rounded gingival margin with a defined cavosurface angle, commonly used for metal and metal-ceramic crowns because it provides adequate thickness without excessive tooth reduction.

Provisional crown cement

Temporary luting agent for interim restorations; eugenol-containing types can interfere with subsequent resin bonding, so eugenol-free cements are preferred before adhesive final cementation.

Freeway space

The interocclusal distance between the maxillary and mandibular teeth when the mandible is at physiologic rest; normally 2–4 mm and preserved during complete denture construction.

Posterior palatal seal

A compressive seal placed between the vibrating line and the hard-soft palate junction, extending to the hamular notches, that improves maxillary denture retention by preventing air entry.

Neutral zone

The potential space where the tongue, lips, and cheeks exert balanced forces; placing denture teeth within this zone improves stability and comfort during function.

Balanced occlusion

Bilateral simultaneous occlusal contacts in centric relation with stabilizing contacts during eccentric movements; required in complete dentures to limit tipping and tissue trauma.

Kennedy Class I

A removable partial denture situation with bilateral edentulous areas located posterior to the remaining natural teeth, creating distal extension bases on both sides.

Occlusal rest seat

A prepared depression, usually 1.0–1.5 mm deep and 2.5 mm buccolingual, that directs forces along the abutment's long axis and prevents the framework from settling.

RPI clasp assembly

Mesial rest, proximal plate, and I-bar; it reduces torque on distal extension abutments by allowing rotation around a mesial fulcrum during functional loading.

Altered cast technique

A functional impression of a distal extension ridge made after framework try-in, capturing tissue under load so the denture base has optimal support and stability.

Osseointegration

Direct structural and functional connection between living bone and the surface of a load-bearing implant without intervening soft tissue, confirmed clinically by absence of mobility.

Platform switching

Use of a restorative abutment narrower than the implant platform; it shifts the implant-abutment junction inward and may reduce crestal bone remodeling.

Insertion torque

Rotational resistance measured during implant placement; values of at least 35 N·cm in good bone support immediate loading by limiting micromotion.

Peri-implant mucositis

Reversible inflammation confined to peri-implant soft tissue, with bleeding on probing and no progressive bone loss; distinguish from peri-implantitis, which includes bone loss.

Centric relation

A maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their discs in the anterior-superior position against the articular eminence.

Mutually protected occlusion

An occlusal scheme in which posterior teeth protect anterior teeth in centric occlusion, while anterior teeth disclude posterior teeth during excursive mandibular movements.

Reciprocal click

A pair of temporomandibular joint sounds, one on opening and one on closing, typically indicating disc displacement with reduction as the condyle moves on and off the disc.

Stabilization splint

A full-arch removable appliance with a flat occlusal plane, adjusted for even centric contacts and anterior guidance, used to reduce parafunction and temporomandibular symptoms.

C-factor

The ratio of bonded to unbonded surface area in a cavity preparation; high C-factor increases polymerization shrinkage stress and marginal gap risk in resin composites.

Transformation toughening

A strengthening mechanism in zirconia where stress-induced phase change from tetragonal to monoclinic increases volume and inhibits crack propagation.

Addition silicone

A vinyl polysiloxane impression material with high dimensional stability and accuracy; it is hydrophobic and may require a hydrophilic wash or dry field.

Type IV dental stone

A high-strength, low-expansion gypsum product used for making dies and precision casts in fixed prosthodontics; it is mixed with a measured water-to-powder ratio.

Value in shade selection

The lightness or darkness of a tooth color; it is usually assessed first because value mismatches are more visible than hue or chroma errors in restorations.

Intraoral scanner

A digital device that captures optical impressions as STL data; accuracy depends on surface moisture, reflectivity, scanner path, and adequate tooth preparation.

Monolithic restoration

A restoration fabricated from a single material block, such as zirconia or lithium disilicate, avoiding veneering porcelain and reducing chipping risk.

Digital smile design

A software-based planning method that overlays proposed tooth proportions and incisal edges onto facial photographs to guide wax-ups, mock-ups, and final restorations.

Obturator prosthesis

A removable prosthesis that closes an acquired oral defect, restoring separation between oral and nasal cavities to improve speech, swallowing, and mastication.

Denture stomatitis

Chronic erythematous inflammation of denture-bearing mucosa, often associated with Candida albicans, poor denture hygiene, and continuous denture wearing.

Radiation caries

Rapidly progressing cervical and incisal caries after head and neck radiotherapy, driven by xerostomia, reduced buffering, and altered oral flora.

Residual ridge resorption

Progressive loss of alveolar bone after tooth extraction; it is usually greater in the mandible than the maxilla and continues throughout life at variable rates.