16 A Flashcards
the artificial teeth of a partial fixed dental prosthesis (FPD) that replace missing natural teeth, restoring function and appearance
PONTIC
incorporate mechanical principles for strength and longevity, as
well as esthetic principles
PONTIC
→ meets hygienic requirements and prevent irritation of the residual ridge
→ particular attention to form and shape of the gingival surface
→ facilitate plaque control
→ adjust to existing occlusal condition
PONTIC DESIGN
FDP is to prevent tilting or drifting of the adjacent teeth into the edentulous space
PONTIC SPACE
→ if orthodontic repositioning is not possible, contours of adjacent teeth may be better than making an FPD with undersized pontics
orthodontic repositioning is not possible, increasing proximal
→ careful diagnostic waxing procedures help determine the most appropriate treatment
PONTIC SPACE
ridge has a smooth, regular surface of attached gingiva which facilitates maintenance of a plaque-free environment
RESIDUAL RIDGE CONTOUR
its height and width should allow placement of a pontic that appears to emerge from the ridge and mimics the appearance of the neighboring teeth
RESIDUAL RIDGE CONTOUR
→ it must be free of frenum attachment and be of adequate facial height
→ design a pontic that meets hygienic requirements and prevents irritation of the residual ridge
RESIDUAL RIDGE CONTOUR
(“black triangles” → food impaction) and percolation of saliva during speech
RESIDUAL RIDGE CONTOUR
→ resorption occurs at the buccal plate resulting horizontal defect
→ 0.3 to 5 mm at 6 months after extraction
GINGIVAL ARCHITECTURE PRESERVATION
→ 50% of the width of alveolar ridge is lost at 12 months
→ the alveolar process can be preserved through immediate
restorative and periodontal intervention at the time of tooth
removal
GINGIVAL ARCHITECTURE PRESERVATION
by conditioning the extraction site and providing a matrix for
healing
GINGIVAL ARCHITECTURE PRESERVATION
→ preserving the facial plate of bone; if bone levels are compromised before or during extraction, the sockets can be grafted with an allograft material (hydroxyapatite, tricalcium phosphate, or freeze-dried bone)
→ immediately after preparation of the extraction site, a carefully shaped interim FDP is placed
→ orthodontic extrusion and root submergence
GINGIVAL ARCHITECTURE PRESERVATION
soft tissue procedure
→ Siebert classified residual ridge deformities into three
categories:
SURGICAL MODIFICATION
faciolingual loss of tissue width with normal ridge height’s
Class I Defects
loss of ridge height with normal ridge width
Class II Defects
a combination of loss in both dimensions involved
Class III Defects
→ not aesthetically challenging
→ surgical augmentation of ridge width is uncommon
CLASS I DEFECTS
→ roll technique tissue augmentation
→ the epithelium is removed and the tissue is thinned and rolled
back upon itself
CLASS I DEFECTS
a wedge-shaped connective tissue graft is inserted into a pouch preparation on the facial aspect of the residual ridge
INTERPOSITIONAL GRAFT
→ a thick “free gingival graft” harvested from partial or full thickness palatal donor sites
→ designed to increase ridge height but also contributes to ridge width
ONLAY GRAFT
striation cuts are made in connective tissue to encourage revascularization
ONLAY GRAFT
→ ridge-lap
→ modified ridge-lap
→ ovate
→ conical
Mucosal Contact
→ sanitary (hygienic)
→ modified sanitary
(hygienic)
No Mucosal Contact
→ easy cleaning because its tissue surface remains clear of the residual ridge
→ disadvantages include entrapment of food particles, which may lead to tongue habits that annoy the patient
Sanitary or Hygienic Pontic
concave fitting surface that overlaps the residual ridge buccolingually
Saddle and Ridge-Lap Pontic
should be avoided because the concave gingival surface of the pontic is not accessible to cleaning with dental floss, which leads to plaque accumulation
Saddle and Ridge-Lap Pontic
→ combines the best features of hygienic and saddle pontic designs, combining esthetics with easy cleaning
→ pontic overlaps the residual ridge on the facial side but clears the ridge on the lingual side
Modified Ridge-Lap Pontic
egg-shaped, bullet-shaped, or heart-shaped
Conical Pontic
→ easy for the patient to keep clean
→ recommended for the replacement of
mandibular posterior teeth, for which esthetic
appearance is a lesser concern
Conical Pontic
only one point of contact: at the center of the
residual ridge
Conical Pontic
→ its convex tissue surface resides in a soft tissue depression or hollow in the residual ridge, which makes it appear that a tooth is literally emerging from the gingiva
Ovate Pontic
→ socket-preservation techniques should be performed at the time of extraction to create the tissue recess from which the ovate pontic form will appear to emerge
→ a socket depression is sculpted into the ridge with surgical diamonds, electrosurgery, or a dental laser
Ovate Pontic
→ socket-preservation techniques should be performed at the time of extraction to create the tissue recess from which the ovate pontic form will appear to emerge
→ a socket depression is sculpted into the ridge with surgical diamonds, electrosurgery, or a dental laser
Ovate Pontic
→ pontic possesses an ovate form with the apex positioned more facially on the residual ridge, rather than at the crest of the ridge
→ cleansing of this pontic is also purported to be easiest of all pontic types
Modified Ovate Pontic
→ pressure-free contact between the pontic and the underlying tissues
→ passive contact should occur exclusively on keratinized attached tissue
Ridge Contact
→ should provide good esthetic results
→ biocompatibility, rigidity, and strength to withstand occlusal
forces and longevity
PONTIC MATERIAL
→ glazed porcelain is generally considered the most biocompatible of the available pontic materials
→ highly polished surfaces accumulate plaque if oral hygiene measures are ignored
→ well-polished gold is smoother, less prone to corrosion, and less retentive of plaque than is an unpolished or porous casting
PONTIC MATERIAL
T or f
the buccal and lingual width of the pontic reduced by 30% to lessen occlusal force only when food of uniform consistency is chewed
T
T or f
harmful forces are more likely to be encountered if an FDP is loaded by the accidental biting on a hard object or by parafunctional activities such as bruxism, rather than by chewing of foods
T
T or f
narrowing the occlusal surface may actually impede or even preclude the development of a harmonious and stable occlusal relationship
T
→ strong, easy to keep clean, looks natural
→ uniform veneer of porcelain (approximately 1.2 mm)
→ voids at the porcelain-metal interface will reduce bond strength
and increase the possibility of mechanical failure
→ sharp angles on the veneering area should be rounded
→ occlusal centric contacts must be placed at least 1.5 mm away
from the junction
METAL-CERAMIC PONTICS
→ acceptable only as longer-term interim restorations
→ their resistance to abrasion was lower than that of enamel or porcelain and noticeable wear occurred with normal
toothbrushing
RESIN-VENEERED PONTICS
→ no chemical bond existed between the resin and the metal
framework and so the resin was retained by mechanical means
→ easy to manipulate and repair and do not require the
high-melting range alloys
→ new-generation indirect resins have a higher density of
inorganic ceramic filler
RESIN-VENEERED PONTICS
→ can be used in partial FPDs without a metal substructure
→ a substructure matrix of impregnated glass or polymer fiber
provides structural strength
→ excellent marginal adaptation and esthetics
→ long-term clinical performance is not yet known
FIBER-REINFORCED COMPOSITE RESIN PONTICS
the modified ridge-lap pontic is recommended for most anterior situations; it compensates for lost buccolingual width in the residual ridge by overlapping what remains
→ sometimes the ridge tissue must be surgically reshaped to enhance the result
GINGIVAL INTERFACE
→ duplicating the original tooth is not possible
→ ridge resorption makes such a pontic look too long in the
cervical region
→ shape the pontic to simulate a normal crown and root with
emphasis on the cementoenamel junction
→ the root can be stained to simulate exposed dentin
→ use pink porcelain to simulate the gingival tissues
INCISOGINGIVAL LENGTH
→ space available for a pontic is greater or smaller than the width of the contralateral tooth
→ if possible, such a discrepancy should be corrected by orthodontic treatment
→ an acceptable appearance may be obtained by incorporating visual perception principles into the pontic design
MESIODISTAL WIDTH
→ a pontic of abnormal size may be designed to give the illusion of being a more natural size
→ alteration in the shape of the proximal areas
→ retainers and the pontics can be proportioned to minimize the
discrepancy
MESIODISTAL WIDTH
→ allows for easy plaque removal and has good strength, wear resistance, and esthetics
→ the metal framework for the pontic and one or both of its retainers is then cast in one piece
METAL-CERAMIC PONTICS
→ wax pattern is made to the final anatomic contour
→ to assess connector design adequacy and the relationship between the connectors and the proposed configuration of the
ceramic veneer
ANATOMIC CONTOUR WAXING
