Fitting RPD Framework & Delivery

examination of framework

-was the proposed design closely followed?

-does the framework fit the master cast accurately?

was the proposed design closely followed?

-has the major connector been positioned as requested?

-are the finish lines for acrylic resin denture bases properly positioned?

-have the required rests been included?

-are the designated clasp assemblies present and complete?

-do the retentive clasp arms display the appropriate sizes, shapes, and positions?

-have soft tissue undercuts been handled as directed?

-dental laboratory personnel should never alter a design without consulting the dentist who submitted the work authorization order

does the framework fit the master cast accurately?

-are the rests fully seated in their preparations?

-are reciprocal clasp arms and/or lingual plating in intimate contact with tooth surfaces?

-have finishing and polishing procedures been carried out correctly (no polishing on intaglio surfaces)?

-is the major connector sufficiently rigid?

clinical procedures- appointment objectives

1) fit the framework to the teeth and soft tissues of the supporting arch

2) adjust the framework to the opposing occlusion

-frameworks that are close to being accurately fitted can be as damaging to the oral structures as poorly fitting frameworks

-partial denture that is not quite seated can produce discomfort and destruction beyond expected

-”near fit” is not sufficient

-accurate fit is essential for prosthodontics success

-if practitioner determines that adjustment of the framework will not yield a suitable result, a new impression should be made and a new master cast should be generated

clinical procedures- after framework has been fitted to teeth

-must be adjusted to the opposing occlusion

-pt should be in upright position (not supine)

-framework must not keep the natural teeth from making normal occlusal contacts in centric or eccentric closures

-simplest and most reliable method for correcting occlusal errors is to have patient close into desired positions with nothing in mouth- relationships of maxillary and mandibular teeth can be noted

-practitioner must ensure same pattern of contact exists when each framework is placed individually

-pattern must also exist when maxillary and mandibular frameworks are placed in the mouth simultaneously

contact that occurs on framework

-interferes with normal closure

-undesirable contact eliminated by grinding the offending area or areas of the metal framework

-when pt’s original contacts have been reestablished, practitioner should evaluate all eccentric movements- accomplished by having the pt make lateral and protrusive movements with articulating paper between the teeth

-if maxillary and mandibular frameworks have been constructed, the frameworks should be fitted individually

-frameworks placed simultaneously after each framework has been corrected individually

next appointment

-corrected cast impression procedures: necessary for pts requiring mandibular distal extension RPD, those requiring long-span maxillary distal extension RPD, and those requiring long-span anterior replacements

-jaw relation records

-esthetic try-in

-insertion

occlusal schemes for RPDs

1) simultaneous bilateral occlusal contact of opposing posterior teeth should be present when pt is in MIP; contact must occur between natural teeth, natural and artificial teeth, and between artificial teeth; prosthesis must not hold opposing natural teeth apart or some form of destruction will occur

2) for a tooth-borne RPD, occlusion should be similar to a harmonious natural dentition; in most pts, mutually protected articulation is goal

3) for RPD opposing a complete denture, balanced articulation is desirable

4) in class IV applications, desirable to have light contact with the opposing natural teeth in MIP; prevents further eruption of natural teeth and improves stability of dental arch; eccentric occlusion must be developed so the prosthetic teeth are in harmony with the chosen occlusal scheme

5) artificial teeth should not be positioned on the upward incline of the mandibular ridge; placement of forces in this region produces an inclined plane effect involving the intaglio surface of the prosthesis and the tissues of the mandibular ridge

aesthetic try-in

-denture base doesn’t need to be waxed to full contour, but should be neat/clean/resistant to tooth displacement

-carefully insert RPD and tell pt to avoid application of biting forces

-pt then directed to close lightly to ensure that no interferences are present

-evaluate positions of anterior teeth and assess lip support

-tooth length should be carefully evaluated

-if all anterior teeth are being replaced and upper lip is normal length, edges of the central incisors should be visible when the lip is relaxed

-when lip is drawn upward, the gingival contours of the denture base should be minimally evident

-pay attention to horizontal and vertical overlap of anterior teeth- if some natural anterior teeth remain, overlap should be duplicated

-pay attention to maxillary midline

-verification of tooth shade should be accomplished during the evaluation process

-treatment should not proceed until pt approval has been gained

verification of jaw relation- jaw relation only needs to be verified in limited instances

1) if problems were encountered during jaw relation procedures and there is any doubt regarding the accuracy of the articulator mounting

2) if the partial denture is opposed by a complete denture

3) if all posterior teeth in both arches are being replaced

4) if there are no opposing natural teeth in contact and verification of the occlusal vertical dimension is necessary

delivering RPD- objectives of insertion appointment

1) evaluate and correct the fit of the denture base

2) correct the occlusion

3) adjust the retentive clasps

-provide verbal and written instructions regarding appropriate oral hygiene, RPD hygiene, and need for future evaluation and maintenance

fit of denture base

-denture bases often display heavy contact with the lateral walls of the ridge and little or no contact with the ridge crest

-pattern of tissue contact results from the predictable distortion that occurs during polymerization of heat-activated denture base resins

-chemically-activated resins display slightly less distortion and therefore require less adjustment during the insertion appointment

-cast metal bases are not subject to the difficulties associated with polymerization shrinkage and usually do not require adjustment during the insertion appointment

-any correction to a cast metal base should have been performed at the framework try-in appointment

fit of denture base- extension of denture flanges

-important role in support and stability of an RPD

-maximum flange extension, within physiologically tolerable limits, provides optimal support and stability for the prosthesis

-extension into the facial vestibules and lingual sulk enhances resistance to horizontal displacement

-acrylic resin denture base flanges should not be arbitrarily reduced- instead, should be critically evaluated and adjusted only when physiologic limits have been exceeded

posterior denture base flanges

-should be at least 2mm thick and should display rounded borders

-should be slightly thinner at the distolingual aspects of mandibular extension base RPDs and distofacial aspects of maxillary extension base RPDs

-decreased flange thickness in these areas provides additional tongue space in the mandibular arch and freedom of movement for the coronoid processes in the maxillary arch

-leading edges of maxillary and mandibular posterior denture base flanges also should be thinned

-^helps to disguise the presence of the flange when the patient is viewed from the front during normal conversation while smiling

correction of occlusal contacts

-must not be initiated until the RPD can be completely and comfortably seated in the patient’s mouth

-occlusal contacts that exist when the RPD is out of the mouth must also exist when the prosthesis is in place

-RPD should not interfere with the mandible attaining the prescribed occlusal vertical dimension, nor with required guidances during eccentric mandibular movements

-if metallic components were properly adjusted during the framework try-in, occlusal interferences that occur during the insertion appointment should be limited to the prosthetic teeth

goals of occlusal evaluation and correction during insertion appointment

1) maintenance of existing natural tooth contacts

2) establishment of occlusal harmony in all centric and eccentric positions

-process of marking and adjusting occlusal surfaces is continued until contact between opposing natural teeth has been restored

-at the same time, denture teeth should display firm occlusal contact

adjusting retentive c lasps

-in most instances, no adjustment of the direct retainers is indicated during the insertion appointment

-when clasp adjustment is necessary, goals are to limit unnecessary force application to the abutments and assure that sufficient RPD retention is provided

-chromium-based alloys are relatively tough- clasps relatively resistant to fracture and can withstand moderate bending adjustments if properly managed

-clasps should be adjusted in small increments and frequently checked to determine if the desired results have been achieved

-use No. 139 “bird-beak” plier and No. 200 “three-prong” plier

adjusting wrought-wire clasp arms

-most commonly require adjustment

-partially due to early distortion of clasps resulting from inappropriate design and application (placed into excessive undercuts)

-^as a result, the yield strength of the wrought metal is exceeded and permanent deformation or fracture results

cast infrabulge clasp adjustments

-cast infrabulge clasps have half-round, cross-sectional forms

-adjustment of an infrabulge clasp can only be accomplished in a plane perpendicular to the flat surface of the clasp

-clasp must be adjusted directly toward the abutment or directly away from the abutment

patient instructions

-appropriate methods for dental hygiene should be demonstrated

-emphasis given to physically brushing the denture on a daily basis rather than relying on a cleaning or soaking agent to remove debris

-use of common toothpaste should be avoided since pastes often contain abrasive particles

-pt must understand that denture should never be brushed while in mouth- prosthesis should be removed to permit access to all surfaces

-pt should be instructed to clean the denture over a partially filled basin of water so that if the denture is dropped, little harm will be done

-remove prosthesis before going to bed- soft tissues covered by the denture bases and the major connectors must be given the opportunity to recover from constant mechanical stresses applied when the prosthesis is in place

-store prosthesis in water when not in the oral cavity- failure to do so may result in drying/cracking/warpage of acrylic resin components

teaching pt how to insert and remove a dental prosthesis

-essential

-pt’s ability to adequately manage task depends to some extent on manual dexterity, muscular coordination, visual acuity, and physical condition

-design of RPD, number and position of direct retainers, and total amount of retentive force affect ease that prosthesis can be removed from mouth

-before leaving the office, pt should be asked to demonstrate the proper methods of RPD insertion and removal for the dentist