FPD- pontic design

consequences of tooth loss

• adjacent teeth may drift/tilt mesially/distally

• the opposing tooth may retrude into the edentulous space

• premature contacts may be created during protrusive movement

options for replacing missing tooth/teeth

• implant supported restoration

• partial fixed dental prosthesis

• removable partial denture

• resin bonded FDP

what is usually the first choice of replacing a missing tooth

implants

sometimes pt can decline implants, what tooth replacement would you offer to the pt next

FPD- fixed partial denture (bridge)

what might be some reasons a pt would decline implants/wouldn't be a good candidiate

• declines surgery

• hx of failed implants

• limited finances

• adjacent teeth on edentulous space already require complete coverage

• pt desires quick tx completion

dentists should avoid indiscriminate preparation of healthy unrestored teeth to replace missing teeth because…

FPDs can increase the risk of future complications

what are the main components of a fixed partial denture (FPD)

• retainer

• pontic

• connector

what is the abutment in a FPD

a tooth, a portion of a tooth, or that portion of a dental implant that serves to support and/or retain a prosthesis (tooth that supports the FDP)

what is the retainer in a fixed partial denture

any type of device used for the stabilization or retention of a prosthesis- part of the FDP cemented or luted to the abutment

what is the retainer in a fixed dental prosthesis

the part of a fixed partial denture or fixed complete denture that unites the abutments to the remainder of the restoration

what is the pontic in a FPD

an artificial tooth on a fixed dental prosthesis that replaces a missing natural tooth, restores its funx, and usually fills the space previously occupied by the clinical crown

what is the connector

in fixed dental prosthodontics, the portion of a fixed dental prosthesis that unites the retainer(s) and pontic(s)

when considering FPD as tx, what should be evaluated

• potential abutment teeth

• super-erupted teeth

• mesially or distally tilted adjacent teeth to edentulous area

when considering FPD as tx, what should be examined when looking at the potential abutment teeth

• root shape

• periodontal tissue

• crown:root

• if RCT → ferrule

• quality and extension of caries/restoration

• height/width of edentulous area at MIP

what Law is thought about when looking at root surface area

Ante’s law

what is Ante’s law

root surface area of the abutments should be more than the root surface area of the teeth being replaced

what Law is thought about when thinking of span length

Law of Beams

what is the Law of Beams

span of edentulous site: bending or deflection varies directly with the cube of the length and inversely w the cube of the occlusogingival thickness of the pontic

according to the Law of Beams, excessive flexing under occlusal loads can cause…

• premature failure

• fx of porcelain veneer

• connector fx

• loosening of a retainer

• tooth mobility

• unfavorable soft tissue response

according to the Law of Beams, ______________ is a common contraindication for FDP

excessive span length

ranks these from most to least prognosis

FDP w 2 pontics in anterior region

FPD w 1 pontic

FPD w 2+ pontics in posterior region

FPD w 1 pontic > FPD w 2 pontics in anterior region > FPD w 2+ pontics in posterior region

what are the exceptions to a longer span length in FPD

• when the FPD is opposing a complete denture → occlusal loads tend to be lower

• a successful FPD in the mandibular anterior region includes a 6-unit FPD from canine to canine

what is a cantilever fixed partial denture

where only one side of the pontic is attached to one or multiple retainers

what is a classic popular example of a cantilever FPD

a lateral incisor pontic attached to only the adjacent canine retainer

cantilever FPDs can be made out of….

• metal-ceramic

• ceramic materials- zirconia

in an unideal situation: what do you do when the FPD is replacing either a maxillary or mandibular canine tooth

the small lateral incisor may be splinted to the central incisor to prevent lateral drift of the FPD

in an unideal situation, sometimes you need to double-abutt, what are the requirements for the secondary abutment

• must have at least as much root surface area and as favorable a crown:root as the primary abutment

• retainers on secondary abutment must be at least as retentive as the retainers on the primary abutments

what 3 things should be evaluated in a metal-ceramic restoration framework design

• margin

• occlusion

• proximal contacts

what are the 3 designs for margin or metal ceramic crown

• metal collar

• metal disappearing

• ceramic margin

an optical pontic design should have what 3 components

• biologic

• mechanical

• esthetic

___________________ may prove especially valuable for determining optimal pontic deisgn

diagnostic cast and waxing procedures

what should be in your pre-treatment assessment for FPD

• pontic space

• residual ridge contour

• surgical modification

• gingival architecture preservation

what do you want to look at for pontic space

• mesial-distal

• bucco-lingual width

• occluso-gingival height

what to use to evaluate/grade the residual ridge contour

siebert residual ridge classification- I, II, III

siebert residual ridge C-I defects

faciolingual loss (horizontal loss) of tissue width w normal ridge height

siebert residual ridge C-II defects

loss of ridge height (vertical loss) w normal ridge width

siebert residual ridge C-III

a combination of loss in both dimension (horizontal and vertical loss)

the incidence of residual ridge deformity after anterior tooth loss is high at ___%. the majority of these pts are within the C-____ defects

91%; C-III defects

loss of residual ridge contour may lead to…

unesthetic gingival embrasures (black triangles), food impaction, and percolation of saliva during speech

correction of ridge defects can be done through surgical modifications such as…

soft tissue grafts

• pedicle graft procedure: roll flap procedure

• free graft procedure: pouch graft procedure, interpositional graft procedure, onlay graft procedure

what soft tissue graft could you do for C-I defect

• roll technique (top pic)

• pouch technique (bottom pic)

what soft tissue graft could you do for a C-II and C-III defect

• interpositional graft (top pic)

• onlay graft (bottom pic)

describe the gingival architecture preservation

• immediate restoration and periodontal intervention at the time of tooth removal

• preparing the abutment before ext

• fabricate an interim FPD indirectly, ready for immediate insertion

you want ___ mm apical to facial free gingival margin for gingival architecture preservation

2.5 mm

the contour of the ______ tissue side of the pontic is critical and must conform to within __ mm of the interproximal and facial bone contour to act as a template for healing

ovate tissue; 1 mm

the interim restoration should be highly __________

polished

approximately after 1 month of healing, oral hygiene access is improved by recontouring the pontic to provide __ to __ of relief from the tissue

1-1.5 mm

when the gingival levels are stable, approximately ____________ after healing, the definitive restoration can be fabricated

6-12 months

options for gingival architecture preservation

• bond the ext tooth to the adjacent tooth

• socket preservation- graft

• secondary surgical augmentation later down the line

• ortho extrusion

• root submergence techniques

if bone levels are compromised before or during ext, to preserve the sockets, they can be grafted w an __________ material

allograft

types of allograft material

• hydroxyapatite

• tricalcium phosphate

• freeze-dried bone

rarely can socket preservation completely preserve the alveolar ridge frame, ________________ may still be necessary for some pts

additional surgical augmentation of the ridge

how does ortho extrusion aid in gingival architecture preservation

as teeth are extruded, apposition of bone occurs at the root apex, thereby filling the socket w bone as the tooth is slowly ext orthodontically

disadvantages of ortho extrusion aiding in gingival architecture preservation

• additional time and expense

• endodontic tx necessary beforehand

________________ technqiues hav been recommended to preserve alveolar bone height

root submergence techniques

pontic selection depends primarily on ________ and ________

esthetics and oral hygeine

pontic densign classification

• mucosal contact

• no mucosal contact

pontic classification sunder mucosal contact

• ridge-lap

• modified ridge-lap

• ovate

• conical

pontic classification under no mucosal contact

• sanitary (hygienic)

• modified sanitary (hygienic)

_________ or _______ designs should be avoided because the concave gingival surface of the pontic is not accessible to cleaning w dental floss

saddle or ridge-lap designs

the saddle or ridge-lap designs can lead to

• plaque accumulation

• tissue inflammation

the modified ridge-lap pontic combines ________ with easy ___________

esthetics w easy cleaning

describe the design of the conical pontic

• egg shaped, bullet-shaped, or heart shaped

• one point of contact

pro of conical pontic

easy to clean

indication for conical pontic

mandibular posterior teeth: esthetic is a lesser concern

contraindications for conical pontic

unsuitable for broad residual ridges (bc the emergence profile associated w the small tissue contact point may create areas of food entrapment)

the __________ pontic form may be a better alternative than the conical pontic

sanitary pontic

describe the design of the ovate pontic

emerges from the gingiva, very esthetic

pros of ovate pontic

• most esthetic

• stronger than modified ridge-lap pontic

• not susceptible to food impaction

• easy to clean

con for ovate pontic

need for surgical tissue management/surgical augemntation of soft tissue → socket preservation techniques should be performed at the time of ext

why is the ovate pontic stronger than the modified ridge-lap pontic

the broad convex geometry makes it stronger because the porcelain at the gingivofacial extent of a pontic is supported

what is prosthetic biologic width

the thickness of tissue necessary between a pontic and the alveolar bone; 3.36 ± 0.6 mm

for the ovate pontic, when an adequate volume of ridge tissue is established, a _______ is sculpted into the ridge w…

a socket depression is sculpted; surgical diamonds, electrosurgery, or a dental laser

ovate pontic vs modified ovate pontic

ovate form with the apex positioned more facially on the residual ridge, rather than at the crest of the ridge

indication for modified ovate pontic

horizontal ridge width is not sufficient for a conventional ovate pontic

pros for sanitary/hygeienic pontic

easier plaque control

cons of sanitary/hygienic pontic

• entrapment of food

• poor esthetics

requirements for sanitary/hygienic pontic

• >/= 2 mm ridge-to-pontic space

• pontic O-G thickness >/= 3 mm

what are the available pontic systems

• metal-ceramic

• metal

• ceramic

advantages of metal-ceramic pontic system

• esthetics

• biocompatible

advantages of metal pontic system

• strength

• straight forward procedure

advantages of `ceramic pontic system

• best esthetics

• biocompatible

disadvantages of metal-ceramic pontic system

• difficult to fabricate if an abutment is not metal-ceramic

• weaker than metal

disadvantages of metal pontic system

nonesthetic

disadvantages of ceramic pontic system

• risk of fx

• unable to be sectioned and reconnected

• large connectors needed

indications for metal-ceramic pontic system

most situations

indications for metal pontic system

mandibular molars- especially under high occlusal force

indications for ceramic pontic system

high esthetic demand

contraindications for metal-ceramic pontic system

long span w high stress

contraindications for metal pontic system

where esthetics are important

contraindications for ceramic pontic system

long span w high stress

biological considerations for oral hygiene

• cleansable tissue surface

• access to abutment teeth (gingival embrasure)

biological considerations fro pontic material

• glazed porcelain is most biompatible

• glazed porcelain looks smooth, BUT shows many voids and is rougher than either polished gold or acrylic resin under microscope

• metal should be highly polished

• zirconia is biocompatible, and the soft tissue response is SUPERIOR to other porous materials bc of its low bacterial colonization potential

when vertical space is minimal, which design may be contraindicated

4: when looking at the sectional diameter of the metal substructure, it is the weakest

biological considerations for occlusal forces

recommend to reduce occlusal surface vs normal occlusal width

it is recommended to reduce occlusal surface vs normal occlusal width; what is the exception to this situation

where the residual alveolar ridge has collapsed buccolingually → reducing pontic width may be desiered and would thereby lessen the lingual contour and facilitate plaque-control measures

mechanical considerations when thinking of failure of FPD

• may be caused by improper choice of materials, poor framework design, poor tooth preparation, or poor occlusion

• long-span FPD are particularly susceptible to mechanical problems

__________ pontics have a high fx resistance which make it sutible to be used in long-span fixed restorations w multiple pontics and abutments

zirconia pontics

____________ is required for adequate strength for zirconia pontics, what affect does this have on the restoration

large connector size; diminishes the natural appearance and compromises the ability for oral hygiene maintenance

the metal-ceramic pontic framework must provude a uniform veneer of porcelain, approximately ___ mm

1.2 mm